G2Cdb::Gene report

Gene id
G00001794
Gene symbol
ACTN3 (HGNC)
Species
Homo sapiens
Description
actinin, alpha 3
Orthologue
G00000545 (Mus musculus)

Databases (7)

Gene
ENSG00000204633 (Ensembl human gene)
89 (Entrez Gene)
169 (G2Cdb plasticity & disease)
ACTN3 (GeneCards)
Literature
102574 (OMIM)
Marker Symbol
HGNC:165 (HGNC)
Protein Sequence
Q08043 (UniProt)

Literature (55)

Pubmed - human_disease

  • ACTN3 genotype in professional endurance cyclists.

    Lucia A, Gómez-Gallego F, Santiago C, Bandrés F, Earnest C, Rabadán M, Alonso JM, Hoyos J, Córdova A, Villa G and Foster C

    European University of Madrid, Madrid, Spain. alejandro.lucia@uem.es

    The Z-disk protein alpha-actinin-3 is only expressed in type II muscle fibres, which are responsible for generating forceful contractions at high velocity. Despite the evolutionary conservation of alpha-actinin-3, approximately one in every five Caucasians of European ancestry is totally deficient in this protein, due to homozygosity for a R577X polymorphism in the ACTN3 gene. This, together with the results of recent research on elite athletes, suggests that the "null" XX polymorphism might confer some advantage to endurance performance events. To test this hypothesis, we studied the frequency distribution of R577X genotypes in a group of 50 top-level male professional cyclists (26.9 +/- 0.4 yrs [mean +/- SEM]; VO2max: 73.5 +/- 0.8 ml x kg (-1) x min (-1)). Their results were compared with those of a group of 52 Olympic-class male endurance runners (26.8 +/- 0.6 yrs; VO2max: 73.3 +/- 0.8 ml x kg (-1) x min (-1)) and 123 healthy, sedentary male controls. All subjects were Caucasian, and of European ancestry. No significant differences (p > 0.05) were found between groups: RR: 28.5 %; RX: 53.6 % and XX: 17.9 % in controls; RR: 28.0 %; RX: 46.0 % and XX: 26.0 % in cyclists; and RR: 25.0 %; RX: 57.7 %; XX: 17.3 % in runners). No differences were found in indices of endurance performance (VO2peak or ventilatory thresholds) between athlete carriers of each R577X genotype. In summary, although the alpha-actinin-3 deficient XX genotype may be detrimental for sprint performance in humans, the R577X polymorphism of the ACTN3 gene does not appear to confer an advantage on the ability of male athletes to sustain extreme endurance performance.

    International journal of sports medicine 2006;27;11;880-4

Pubmed - other

  • Is there an association between ACTN3 R577X polymorphism and muscle power phenotypes in young, non-athletic adults?

    Santiago C, Rodríguez-Romo G, Gómez-Gallego F, González-Freire M, Yvert T, Verde Z, Naclerio F, Altmäe S, Esteve-Lanao J, Ruiz JR and Lucia A

    Department of Physiology and Biomedicine, Universidad Europea de Madrid, Madrid, Spain.

    We investigated the association between ACTN3 R577X polymorphism and jumping (vertical squat and counter-movement jump tests) and sprint ability (30 m dash) in non-athletic, healthy young adults [N=284 (217 male), mean (SD) age: 21 (2) years]. We analyzed the differences in the study phenotypes among ACTN3 R577X genotypes by one-way analysis of covariance before and after adjusting for sex, age, weight and height (confounders). We also compared the genotype and allele frequencies between those with the best and worst results in the aforementioned tests (≥90th vs <90th of the sex-specific percentile, respectively). We used logistic regression to calculate the odds ratio (OR) for having the best performance. We did not observe a significant association between ACTN3 R577X genotypes and the study phenotypes before and after adjusting for potential confounders, nor after analyzing males and females separately. We did not observe significant differences in genotype frequencies between those with the best or the worst performance. The OR for an individual with the RR genotype to be in the top 10 percentile was <1.00 for jump tests and <1.015 for sprint tests (all P>0.05). In summary, α-actinin-3 deficiency does not negatively influence the ability to generate explosive leg muscle power in a young non-athletic population.

    Scandinavian journal of medicine & science in sports 2010;20;5;771-8

  • World-class performance in lightweight rowing: is it genetically influenced? A comparison with cyclists, runners and non-athletes.

    Muniesa CA, González-Freire M, Santiago C, Lao JI, Buxens A, Rubio JC, Martín MA, Arenas J, Gomez-Gallego F and Lucia A

    Universidad Europea de Madrid, Villaviciosa de Odón, Madrid 28670, Spain.

    In this study, genotype frequencies of several polymorphisms that are candidates to influence sports performance (ie, ACTN3 R577X, ACE ID, PPARGC1A Gly482Ser, AMPD1 C34T, CKMM 985bp/1170bp and GDF8 (myostatin) K153R) were compared in 123 nonathletic controls, 50 professional cyclists, 52 Olympic-class runners and 39 world-class rowers (medallists in world championships, lightweight category). Significant differences in genotype distributions among the groups were not found except for the ACE gene, that is, lower (p<0.05) proportion of II in rowers (10.3%) than in the total subject population (22.3%). In summary, sports performance is likely polygenic with the combined effect of hundreds of genetic variants, one possibly being the ACE ID polymorphism (at least in the sports studied here), but many others remain to be identified.

    British journal of sports medicine 2010;44;12;898-901

  • The ACTN3 R577X polymorphism in Russian endurance athletes.

    Ahmetov II, Druzhevskaya AM, Astratenkova IV, Popov DV, Vinogradova OL and Rogozkin VA

    Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, 2 Dynamo Ave, 197110 St Petersburg, Russia. genoterra@mail.ru

    Objective: The functional 577R allele of the alpha-actinin-3 (ACTN3) gene has been reported to be associated with elite power athlete status, while the nonfunctional 577XX genotype (predicts an alpha-actinin-3 deficient phenotype) has been hypothesised as providing some sort of advantage for endurance athletes. In the present study, the distribution of ACTN3 genotypes and alleles in Russian endurance-oriented athletes were examined and association between ACTN3 genotypes and the competition results of rowers were sought.

    Methods: 456 Russian endurance-oriented athletes of regional or national competitive standard were involved in the study. ACTN3 genotype and allele frequencies were compared with 1211 controls. The data from the Russian Cup Rowing Tournament were used to search for possible association between the ACTN3 genotype and the long-distance (approximately 6 km) rowing results of 54 athletes. DNA was extracted from mouthwash samples. Genotyping for the R577X variant was performed by PCR and restriction enzyme digestion.

    Results: The frequencies of the ACTN3 577XX genotype (5.7% vs 14.5%; p<0.0001) and 577X allele (33.2% vs 39.0%; p = 0.0025) were significantly lower in endurance-oriented athletes compared with the controls, and none of the highly elite athletes had the 577XX genotype. Furthermore, male rowers with ACTN3 577RR genotype showed better results (1339 (11) s) in long-distance rowing than carriers of 577RX (1386 (12) s) or 577XX (1402 (10) s) genotypes (p = 0.016).

    Conclusion: Our data show that the ACTN3 577X allele is under-represented in Russian endurance athletes and is associated with the rowers' competition results.

    British journal of sports medicine 2010;44;9;649-52

  • Is the interaction between HIF1A P582S and ACTN3 R577X determinant for power/sprint performance?

    Eynon N, Alves AJ, Meckel Y, Yamin C, Ayalon M, Sagiv M and Sagiv M

    Genetics and Molecular Biology Laboratory, Life Sciences Division, The Zinman College of Physical Education and Sport Sciences at the Wingate Institute, Netanya 42902, Israel. eynon@wincol.ac.il

    Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that regulates gene expression in response to hypoxia and has been associated with athletic performance. The aims of this study were (1) to determine the frequency distribution of HIF1A Pro582Ser (rs11549465) polymorphism among 155 Israeli athletes (sprinters and endurance athletes) and 240 healthy controls and (2) to analyze the influence of the interaction between HIF1A Pro582Ser and ACTN3 R577X (rs1815739) genotypes on sprint performance. There were no differences across the HIF1A genotype and allele frequencies among endurance athletes, sprinters, and controls. Similarly, no differences were found between the subgroups of top-level and national-level endurance athletes, or between top-level and national-level sprinters. Conversely, interaction effects were found between HIF1A Pro582Ser and ACTN3 R577X polymorphisms and sprinters. The proportion of HIF1A Pro/Pro + ACTN3 R/R genotypes was significantly higher in sprinters than in endurance athletes and healthy controls (P = .002). In addition, the odds ratio for HIF1A Pro/Pro + ACTN3 R/R genotype carriers being a sprinter was 2.25 (95% confidence interval, 1.24-4.1); and that for HIF1A Pro/Pro + ACTN3 R/R genotype carriers being an endurance athlete was 0.5 (95% confidence interval, 0.2-1.24). We conclude that HIF1A Pro582Ser polymorphism by itself is not critical in determining sprint performance. However, sprinter performance is determined by the interaction between the wild-type HIF1A Pro/Pro genotype and ACTN3 RR genotype.

    Metabolism: clinical and experimental 2010;59;6;861-5

  • Associations of polymorphisms of eight muscle- or metabolism-related genes with performance in Mount Olympus marathon runners.

    Tsianos GI, Evangelou E, Boot A, Zillikens MC, van Meurs JB, Uitterlinden AG and Ioannidis JP

    Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina 45 110, Greece.

    Athletic endurance performance is probably partly under genetic control, but genetic association studies have yielded inconclusive results. The objective of the present study was to evaluate the association of polymorphisms in eight muscle- or metabolism-related genes with endurance performance in participants of the Olympus Marathon running race. We recruited 438 athletes who participated in the 2007 and 2008 annual running events of the Olympus Marathon: a 43.8-km race with an ascent from sea level to 2,690-m altitude and then a descent to 300 m. Phenotypes of interest were the competitive event time at the specific Olympus Marathon where the athlete was enrolled, the fastest reported timing ever achieved in an Olympus Marathon, and how many kilometers per week the athlete ran during the previous year. Eleven polymorphisms in alpha(3)-actinin (ACTN3), AMP deaminase-1 (AMPD1), bradykinin B(2) receptor (BDKRB2), beta(2)-adrenergic receptor (ADRB2), peroxisome proliferator-activated receptor (PPAR)-gamma coactivator-1 alpha (PPARGC1A), PPAR-alpha (PPARA), PPAR-delta (PPARD), and apoliprotein E (APOE) were evaluated. Hardy-Weinberg equilibrium testing on the overall cohort of male athletes showed a significant deviation for BDKRB2 rs1799722 (P = 0.018; P = 0.006 when limited to 316 habitual male runners) with an excess of the TT genotype. Across all athletes, no associations showed nominal statistical significance for any of the three phenotypes, and the same was true when analyses were limited to men (n = 417). When limited to 316 male athletes who identified running as their preferred sport, ADRB2 rs1042713 had nominally significant associations with faster times for the minor (A) allele for the fastest time ever (P = 0.01). The direction of effect was identical as previously postulated only for BDKRB2 rs1799722 and ADRB2 rs1042713, indicating consistency. BDKRB2 rs1799722 and ADRB2 rs1042713 have some support for being implicated in endurance performance among habitual runners and require further investigation.

    Journal of applied physiology (Bethesda, Md. : 1985) 2010;108;3;567-74

  • Can we identify a power-oriented polygenic profile?

    Ruiz JR, Arteta D, Buxens A, Artieda M, Gómez-Gallego F, Santiago C, Yvert T, Morán M and Lucia A

    Dept. of Biosciences and Nutrition at NOVUM, Unit for Preventive Nutrition, Karolinska Institutet, Huddinge 14157, Sweden. ruizj@ugr.es

    Using the model originally developed by Williams and Folland (J Physiol 586: 113-121, 2008), we determined 1) a "total genotype score" (TGS, from the accumulated combination of the 6 polymorphisms, with a maximum value of "100" for the theoretically optimal polygenic score) in a group of elite power athletes, endurance athletes, and nonathletic controls, and 2) the probability for the occurrence of Spanish individuals with the "perfect" power-oriented profile (i.e., TGS = 100). We analyzed six polymorphism that are candidates to explain individual variations in elite power athletic status or power phenotypes (ACE I/D, ACTN3 R577X, AGT Met235Thr, GDF-8 K153R, IL6 -174 G/C, and NOS3 -786T>C) in 53 elite track and field power athletes (jumpers, sprinters), 100 nonathletic controls, and 100 elite endurance athletes (distance runners and road cyclists) (all Spanish Caucasian males). The mean TGS was significantly higher in power athletes (70.8 +/- 17.3) compared with endurance athletes (60.4 +/- 15.9; P < 0.001) and controls (63.3 +/- 13.2; P = 0.012), whereas it did not differ between the latter two groups (P = 0.366). A total of five power athletes (9.4%, all sprinters) had a theoretically "optimal" TGS of 100 vs. 0 subjects in the other two groups. The probability of a Spanish individual possessing a theoretically optimal polygenic profile for up to the six candidate polymorphisms we studied was very small, i.e., approximately 0.2% (or 1 in 500 Spanish individuals). We have identified a polygenic profile that allows us, at least partly, to distinguish elite power athletes from both endurance athletes and nonathletic population.

    Journal of applied physiology (Bethesda, Md. : 1985) 2010;108;3;561-6

  • Does the polygenic profile determine the potential for becoming a world-class athlete? Insights from the sport of rowing.

    Santiago C, Ruiz JR, Muniesa CA, González-Freire M, Gómez-Gallego F and Lucia A

    Universidad Europea de Madrid, Madrid, Spain.

    We determined whether the polygenic profile computed with seven candidate polymorphisms (i.e., ACE, ACTN3, AMPD1, CKMM, HFE, GDF-8 and PPARGC1A) for endurance performance is different in 39 world-class and 15 national-class Spanish (Caucasian) lightweight rowers. The second purpose was to examine the impact of possessing a "preferable" polygenic profile on the sport success in terms of the number of medals won in World and National Championships. Finally, we also compared the polygenic profile of world- and national-class Spanish rowers with that of the general Spanish population. The polygenic profile did not differ between groups of rowers. We did not observe an association between having a preferable polygenic profile and medals won in World and National Championships. Finally, we observed that rowers tend to have a more "favorable" polygenic profile than the general Spanish population. These findings argue against the idea that genetic endowment differentiates athletic champions from elite, yet less accomplished athletes. In contrast, we cannot discard the fact that, overall, elite athletes are endowed with a more "favorable" polygenic profile than the general population.

    Scandinavian journal of medicine & science in sports 2010;20;1;e188-94

  • ACTN3 and ACE genotypes in elite Jamaican and US sprinters.

    Scott RA, Irving R, Irwin L, Morrison E, Charlton V, Austin K, Tladi D, Deason M, Headley SA, Kolkhorst FW, Yang N, North K and Pitsiladis YP

    University of Glasgow, Glasgow, United Kingdom.

    Unlabelled: The angiotensin-converting enzyme (ACE) and the alpha-actinin-3 (ACTN3) genes are two of the most studied "performance genes" and both have been associated with sprint/power phenotypes and elite performance.

    Purpose: To investigate the association between the ACE and the ACTN3 genotypes and sprint athlete status in elite Jamaican and US African American sprinters.

    Methods: The ACTN3 R577X and the ACE I/D and A22982G (rs4363) genotype distributions of elite Jamaican (J-A; N = 116) and US sprinters (US-A; N = 114) were compared with controls from the Jamaican (J-C; N = 311) and US African American (US-C; N = 191) populations. Frequency differences between groups were assessed by exact test.

    Results: For ACTN3, the XX genotype was found to be at very low frequency in both athlete and control cohorts (J-C = 2%, J-A = 3%, US-C = 4%, US-A = 2%). Athletes did not differ from controls in ACTN3 genotype distribution (J, P = 0.87; US, P = 0.58). Similarly, neither US nor Jamaican athletes differed from controls in genotype at ACE I/D (J, P = 0.44; US, P = 0.37). Jamaican athletes did not differ from controls for A22982G genotype (P = 0.28), although US sprinters did (P = 0.029), displaying an excess of heterozygotes relative to controls but no excess of GG homozygotes (US-C = 22%, US-A = 18%).

    Conclusions: Given that ACTN3 XX genotype is negatively associated with elite sprint athlete status, the underlying low frequency in these populations eliminates the possibility of replicating this association in Jamaican and US African American sprinters. The finding of no excess in ACE DD or GG genotypes in elite sprint athletes relative to controls suggests that ACE genotype is not a determinant of elite sprint athlete status.

    Medicine and science in sports and exercise 2010;42;1;107-12

  • Is there an ACE ID - ACTN3 R577X polymorphisms interaction that influences sprint performance?

    Eynon N, Alves AJ, Yamin C, Sagiv M, Duarte JA, Oliveira J, Ayalon M, Goldhammer E, Sagiv M and Meckel Y

    Zinman College of Physical Education and Sports Sciences at the Wingate Institute, Genetics and Molecular Biology, Netanya, Israel. eynon@wincol.ac.il

    Functional R577X (rs.1815739) and ID (rs.5186) polymorphisms in the alpha-actinin-3 ( ACTN3) and the angiotensin converting enzyme (ACE) genes, respectively, have been associated with sprint performance. The aim of this study was to determine their effect on sprint performance among 81 Israeli sprinters and 240 healthy controls. Results revealed that the ACE II genotype+ ACTN3 R allele (P=0.003 for sprinters vs. controls), and the ACTN3 RR genotype +ACE I allele (P=0.001 for sprinters vs. controls) might be the genotype for sprinters. In the whole cohort the probability of ACTN3 RR genotype+ ACE I allele being a sprinter (odds ratio 2.67, 95% confidence interval 1.45-4.93) and of ACE II genotype+ ACTN3 R allele being a sprinter (odds ratio 3.57, 95% confidence interval 1.78-7.15) was significantly higher than that in the controls. In conclusion, the above data suggest that ACE ID/ ACTN3 R577X genotype combination is associated with sprint ability. However, ACE ID/ ACTN3 R577X genotype combination is not related to the level of performance.

    International journal of sports medicine 2009;30;12;888-91

  • ACTN3 R577X polymorphism and Israeli top-level athletes.

    Eynon N, Duarte JA, Oliveira J, Sagiv M, Yamin C, Meckel Y, Sagiv M and Goldhammer E

    The Zinman College of Physical Education and Sports Sciences at the Wingate Institute, Netanya, Israel. eynon@wincol.ac.il

    A common genetic variation in the alpha-actinin-3 ( ACTN3) gene causes a replacement of an arginine (R) with a premature stop codon (X) at amino-acid 577 (rs1815739). While the R allele has been found to be associated with power-oriented performance, the XX genotype may be linked with endurance ability. To test this hypothesis, we studied the distribution of ACTN3 genotypes in 155 Israeli athletes (age=35.9+12.2 years) classified by sport (endurance runners and sprinters) and in 240 sedentary individuals. The sprinters' allele frequencies (AF: R/X=0.7/0.3) and 577RR genotype distribution percentage (GD: RR=52%) differed markedly from those of the endurance athletes (AF: R/X=0.53/0.47, p=0.000007; GD: RR=18%, p=0.00009) and the control group (AF: R/X=0.55/0.45, p=0.0002; GD: RR=27.3%, p=0.000003). A comparison between the top-level and national-level sprinters revealed that the R allele occurs more often in the top-level sprinters. A significantly higher proportion of the XX genotype was observed in endurance athletes (34%) compared with controls (18%, p=0.02) and sprinters (13%, p=0.002). However, top-level and national level endurance athletes had similar allele and genotype frequencies. We conclude that the ACTN3 R allele is associated with top-level sprint performance and the X allele and XX genotypes may not be critical but rather additive to endurance performance.

    International journal of sports medicine 2009;30;9;695-8

  • Association between the ACTN3 R577X polymorphism and artistic gymnastic performance in Italy.

    Massidda M, Vona G and Calò CM

    Department of Experimental Biology, University of Cagliari, Cagliari, Italy.

    The ACTN3 (R577X) gene encodes for a structural protein that is exclusively expressed in the Z-disc of type II muscle fibers. Homozygosis (577XX) for the stop codon in the ACTN3 polymorphism results in alpha-actinin-3 complete deficiency. Previous studies have shown low frequencies of the ACTN3 XX genotype in elite sprinters compared to the general population. This study tests 35 Italian elite gymnasts and 53 controls. ACTN3 XX genotype (2.8% vs. 18.8%; p < 0.04) and X allele (27.1% vs. 43.3%; p < 0.04) frequencies were significantly lower in gymnasts compared to controls. The ACTN3 XX genotype was underrepresented in female and male gymnasts compared to controls, but was only significant for males (male: 0% vs. 16.1%, p < 0.04; female: 5.5% vs. 22.7%, p = 0.39). These results suggest that alpha-actinin-3 is beneficial to skeletal muscle function in generating forceful contractions at high velocity. In conclusion, our results associated the ACTN3 R577X polymorphism with male and possibly female elite gymnastic performance.

    Genetic testing and molecular biomarkers 2009;13;3;377-80

  • Is there an optimum endurance polygenic profile?

    Ruiz JR, Gómez-Gallego F, Santiago C, González-Freire M, Verde Z, Foster C and Lucia A

    Department of Biosciences and Nutrition at NOVUM, Karolinska Institutet, Huddinge, Sweden.

    We analysed seven genetic polymorphisms that are candidates to explain individual variations in human endurance phenotypic traits, at least in Caucasian people (ACE Ins/Del, ACTN3 Arg577Ter, AMPD1 Gln12Ter, CKMM 1170 bp/985 + 185 bp, HFE His63Asp, GDF-8 Lys153Arg and PPARGC1A Gly482Ser) in 46 world-class endurance athletes and 123 controls (all Spanish Caucasians). Using the model developed by Williams & Folland we determined (1) the 'total genotype score' (TGS, from the accumulated combination of the seven polymorphisms, with a maximum value of '100' for the theoretically optimal polygenic score) in the non-athlete (control) group, in the athlete group and in the total Spanish population, and (2) the probability for the occurrence of Spanish individuals with the 'perfect' polygenic endurance profile (i.e. TGS = 100). The probability of a Spanish individual possessing a theoretically optimal polygenic profile for up to the seven candidate genetic polymorphisms we studied was very small, i.e. approximately 0.07% (or 1 in 1351 Spanish individuals). The mean TGS was higher in athletes (70.22 +/- 15.58) than in controls (62.43 +/- 11.45) and also higher than predicted for the total Spanish population (60.80 +/- 12.1), suggesting an overall more 'favourable' polygenic profile in the athlete group. However, only three of the best Spanish endurance athletes (who are also amongst the best in the world) had the best possible score for up to six genes and none of them had the optimal profile. Other polymorphisms yet undiscovered as well as several factors independent of genetic endowment may explain why some individuals reach the upper end of the endurance performance continuum.

    The Journal of physiology 2009;587;Pt 7;1527-34

  • Neisseria meningitidis Opc invasin binds to the cytoskeletal protein alpha-actinin.

    Sa E Cunha C, Griffiths NJ, Murillo I and Virji M

    Department of Cellular and Molecular Medicine, School of Medical Sciences, University of Bristol, Bristol, UK.

    Neisseria meningitidis Opc protein is an effective invasin for human endothelial cells. We have investigated novel human endothelial receptors targeted by Opc and observed that Opc-expressing bacteria interacted with a 100 kDa protein in whole-cell lysates of human endothelial and epithelial cells. The identity of the protein was established as alpha-actinin by mass spectrometry. Opc expression was essential for the recognition of alpha-actinin whether provided in a purified form or in cell extracts. The interaction of the two proteins did not involve intermediate molecules. As there was no demonstrable expression of alpha-actinin on the surfaces of any of the eight cell lines studied, the likelihood of the interactions after meningococcal internalization was examined. Confocal imaging demonstrated considerable colocalization of N. meningitidis with alpha-actinin especially after a prolonged period of internalization. This may imply that bacteria and alpha-actinin initially occur in separate compartments and co-compartmentalization occurs progressively over the 8 h infection period used. In conclusion, these studies have identified a novel and an intracellular target for the N. meningitidis Opc invasin. Since alpha-actinin is a modulator of a variety of signalling pathways and of cytoskeletal functions, its targeting by Opc may enable bacteria to survive/translocate across endothelial barriers.

    Funded by: Medical Research Council: G0500644; Wellcome Trust

    Cellular microbiology 2009;11;3;389-405

  • Strength, power, fiber types, and mRNA expression in trained men and women with different ACTN3 R577X genotypes.

    Norman B, Esbjörnsson M, Rundqvist H, Osterlund T, von Walden F and Tesch PA

    Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska University Hospital, Huddinge, Stockholm, Sweden. Barbara.Norman@ki.se

    Alpha-actinins are structural proteins of the Z-line. Human skeletal muscle expresses two alpha-actinin isoforms, alpha-actinin-2 and alpha-actinin-3, encoded by their respective genes ACTN2 and ACTN3. ACTN2 is expressed in all muscle fiber types, while only type II fibers, and particularly the type IIb fibers, express ACTN3. ACTN3 (R577X) polymorphism results in loss of alpha-actinin-3 and has been suggested to influence skeletal muscle function. The X allele is less common in elite sprint and power athletes than in the general population and has been suggested to be detrimental for performance requiring high power. The present study investigated the association of ACTN3 genotype with muscle power during 30-s Wingate cycling in 120 moderately to well-trained men and women and with knee extensor strength and fatigability in a subset of 21 men performing isokinetic exercise. Muscle biopsies were obtained from the vastus lateralis muscle to determine fiber-type composition and ACTN2 and ACTN3 mRNA levels. Peak and mean power and the torque-velocity relationship and fatigability output showed no difference across ACTN3 genotypes. Thus this study suggests that R577X polymorphism in ACTN3 is not associated with differences in power output, fatigability, or force-velocity characteristics in moderately trained individuals. However, repeated exercise bouts prompted an increase in peak torque in RR but not in XX genotypes, suggesting that ACTN3 genotype may modulate responsiveness to training. Our data further suggest that alpha-actinins do not play a significant role in determining muscle fiber-type composition. Finally, we show that ACTN2 expression is affected by the content of alpha-actinin-3, which implies that alpha-actinin-2 may compensate for the lack of alpha-actinin-3 and hence counteract the phenotypic consequences of the deficiency.

    Journal of applied physiology (Bethesda, Md. : 1985) 2009;106;3;959-65

  • Endurance performance: genes or gene combinations?

    Gómez-Gallego F, Santiago C, González-Freire M, Muniesa CA, Fernández Del Valle M, Pérez M, Foster C and Lucia A

    Biomedical Laboratory, Universidad Europea de Madrid, Madrid, Spain.

    We assessed the possible association between variants of the genes encoding for the angiotensin-converting enzyme ( ACE) and alpha-actinin-3 ( ACTN3) (both individually and combined) and several endurance phenotypic traits, e.g., peak power output (PPO), ventilatory (VT) and respiratory compensation threshold (RCT), among others, in professional road cyclists and sedentary controls (n = 46 each). We applied an ANCOVA test using the aforementioned phenotype traits as dependent variables, ACE and/or ACTN3 genotype as the fixed (independent) factor and age and body mass as covariates. We only found a significant genotype effect with no concomitant covariate effect for ACTN3, with cyclists who were not alpha-actinin-3 deficient (RR + RX genotypes) having higher PPO and VT values than their XX counterparts (mean [SEM]: 7.4 (0.1) vs. 7.1 (0.1) W/kg, p = 0.035; and 4.5 (0.1) vs. 4.3 (0.1) W/kg, p = 0.029, respectively). Cyclists with an "extreme" ACTN3 and ACE genotype combination, i.e., most strength/power oriented (DD + RR/RX), had higher RCT values than those with the "intermediate" combinations (II + RX/RR, p = 0.036; and DD + XX, p = .0004) but similar to those with the most endurance oriented genotype (II + XX). No significant differences (p > 0.05) were found in controls. In summary, in world-class cyclists, we only found an association between ACTN3 genotypes and VT and PPO, and between ACTN3/ACE genotype combinations and RCT.

    International journal of sports medicine 2009;30;1;66-72

  • Human angiotensin-converting enzyme I/D and alpha-actinin 3 R577X genotypes and muscle functional and contractile properties.

    McCauley T, Mastana SS, Hossack J, Macdonald M and Folland JP

    School of Sport and Exercise Sciences, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU, UK. t.m.mccauley@lboro.ac.uk

    The angiotensin-converting enzyme (ACE) I/D and alpha-actinin 3 (ACTN3) R/X polymorphisms have been suggested to influence variations in skeletal muscle function. This study investigated the association between ACE I/D and ACTN3 R/X polymorphisms and muscle strength and contractile properties in young UK Caucasian men. Measurements of the knee extensor muscles were taken from 79 recreationally active but non-strength-trained males on two occasions. Isometric knee extensor strength was measured using a conventional strength-testing chair. Maximal twitches were electrically evoked by percutaneous stimulation to assess time-to-peak tension, half-relaxation time and peak rate of force development. The torque-velocity relationship was measured at four angular velocities (0, 30, 90 and 240 deg s(-1)) using isokinetic dynamometry, and the relative torque at high velocity was calculated (torque at 240 deg s(-1) as a percentage of that at 30 deg s(-1)). The ACE I/D and ACTN3 R/X polymorphisms were genotyped from whole blood by polymerase chain reaction. Serum ACE activity was assayed from serum using automated spectrophotometry. Physical characteristics were independent of either genotype. Absolute and relative high-velocity torque were not influenced by ACE or ACTN3 genotypes. Isometric strength and the time course of a maximal twitch were independent of ACE and ACTN3 genotypes. Serum ACE activity was significantly dependent on ACE genotype (P < 0.001), but was not associated with any measure of functional or contractile properties. Knee extensor functional and contractile properties, including high-velocity strength, were not influenced by ACE and ACTN3 polymorphisms in a cohort of UK Caucasian males. Any influence of these individual polymorphisms on human skeletal muscle does not appear to be of sufficient magnitude to influence function in free-living UK Caucasian men.

    Experimental physiology 2009;94;1;81-9

  • alpha-actinin-3 and performance.

    Yang N, Garton F and North K

    Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, University of Sydney, Sydney, NSW, Australia.

    The human sarcomeric alpha-actinins (ACTN2 and ACTN3) are major structural components of the Z line in skeletal muscle; they play a role in the maintenance of sarcomeric integrity and also interact with a wide variety of structural, signaling and metabolic proteins. ACTN2 is expressed in all muscle fibers, and expression of ACTN3 is restricted to the type 2 (fast glycolytic) fibers that are responsible for forceful contraction at high velocity. There is a common stop codon polymorphism R577X in the ACTN3 gene. Homozygosity for the R577X null-allele results in the absence of alpha-actinin-3 in fast muscle fibers with frequencies that vary from < 1% in Africans to approximately 18% in Caucasians. A number of association studies have demonstrated that the ACTN3 R577X genotype influences athletic performance in Caucasians; the frequency of the XX genotype is significantly lower than controls in sprint athletes, and it appears that alpha-actinin-3 deficiency is detrimental to sprint performance. In the general population, the ACTN3 genotype contributes to the normal variations in muscle strength and sprinting speed. In an Actn3 knockout mouse model, alpha-actinin-3 deficiency is associated with a shift in the characteristics of fast, glycolytic 2B muscle fibers towards a slow phenotype, with decreased muscle mass and fiber diameter, slower contractile properties, increased fatigue resistance, and an increase in oxidative enzyme activity. The shift towards a more efficient oxidative metabolism may underlie the selective advantage of the X-allele during evolution. In turn, the shift towards a 'slow' muscle phenotype in fast muscle fibers likely explains why loss of alpha-actinin-3 is detrimental to sprint performance.

    Medicine and sport science 2009;54;88-101

  • ACTN3 genotype is associated with muscle phenotypes in women across the adult age span.

    Walsh S, Liu D, Metter EJ, Ferrucci L and Roth SM

    Department of Kinesiology, School of Public Health, University of Maryland, College Park, MD 20742-2611, USA.

    The R577X polymorphism in the alpha-actinin-3 encoding gene (ACTN3) has been associated with elite athletic performance, and recently with differences in isometric and dynamic muscle strength and power in the general population. In this study we sought to determine the association of ACTN3 R577X genotype with muscle strength and mass phenotypes in men and women across the adult age span. Eight hundred forty-eight (n = 848) adult volunteers (454 men and 394 women) aged 22-90 yr were genotyped for ACTN3 R577X. Knee extensor (KE) shortening and lengthening peak torque values were determined using isokinetic dynamometry and fat-free mass (FFM) by dual-energy X-ray absorptiometry. Women deficient in alpha-actinin-3 (X/X; n = 53) displayed lower KE shortening peak torque (30 degrees /s: 89.5 +/- 3.5 vs. 99.3 +/- 1.4 N.m, P = 0.011; 180 degrees /s: 60.3 +/- 2.6 vs. 67.0 +/- 1.0 N.m, P = 0.019) and KE lengthening peak torque (30 degrees /s: 122.8 +/- 5.7 vs. 137.0 +/- 2.2 N.m, P = 0.022; 180 degrees /s: 121.8 +/- 5.8 vs. 138.5 +/- 2.2 N.m, P = 0.008) compared with R/X + R/R women (n = 341). Women X/X homozygotes also displayed lower levels of both total body FFM (38.9 +/- 0.5 vs. 40.1 +/- 0.2 kg, P = 0.040) and lower limb FFM (11.9 +/- 0.2 vs. 12.5 +/- 0.1 kg, P = 0.044) compared with R/X + R/R women. No genotype-related differences were observed in men. In conclusion, our results indicate that the absence of alpha-actinin-3 protein (i.e., ACTN3 X/X genotype) influences KE peak torque and FFM in women but not men.

    Funded by: NIA NIH HHS: AG-021500, AG-022791, K01 AG022791, K01 AG022791-02, K01 AG022791-03, K01 AG022791-04, K01 AG022791-05, L30 AG024705, L30 AG024705-02, L30 AG024705-03, R01 AG021500, R01 AG021500-01A1, R01 AG021500-02, R01 AG021500-03

    Journal of applied physiology (Bethesda, Md. : 1985) 2008;105;5;1486-91

  • Association of the ACTN3 genotype and physical functioning with age in older adults.

    Delmonico MJ, Zmuda JM, Taylor BC, Cauley JA, Harris TB, Manini TM, Schwartz A, Li R, Roth SM, Hurley BF, Bauer DC, Ferrell RE, Newman AB and Health ABC and MrOS Research Groups

    Department of Epidemiology, University of Pittsburg , Pittsburg, PA, USA. delmonico@uri.edu

    Objective: The purpose of this study was to examine the association of the alpha-actinin-3 (ACTN3) R577X polymorphism on muscle function and physical performance in older adults.

    Methods: We measured knee extensor torque, midthigh muscle cross-sectional area, muscle quality, short physical performance battery score, and 400-meter walk time at baseline and after 5 years in white older adults aged 70-79 years in the Health, Aging and Body Composition Study cohort (n = 1367). Incident persistent lower extremity limitation (PLL) over 5 years was additionally assessed. We also examined white men in the Osteoporotic Fractures in Men Study, a longitudinal, observational cohort (n = 1152) of men 65 years old or older as a validation cohort for certain phenotypes.

    Results: There were no significant differences between genotype groups in men or women for adjusted baseline phenotypes. Male X-homozygotes had a significantly greater adjusted 5-year increase in their 400-meter walk time compared to R-homozygotes and heterozygotes (p =.03). In women, X-homozygotes had a approximately 35% greater risk of incident PLL compared to R-homozygotes (hazard ratio = 0.65, 95% confidence interval = 0.44-0.94). There were no other significant associations between any of the phenotypes and ACTN3 genotype with aging in either cohort.

    Conclusions: The ACTN3 polymorphism may influence declines in certain measures of physical performance with aging in older white adults, based on longitudinal assessments. However, the influence of the ACTN3 R577X polymorphism does not appear to have a strong effect on skeletal muscle-related phenotypes based on the strength and consistency of the associations and lack of replication with regard to specific phenotypes.

    Funded by: Intramural NIH HHS; NCRR NIH HHS: UL1 RR024140; NIA NIH HHS: 1-AG-6-2101, 1-AG-6-2103, 1-AG-6-2106, AG-022791, K01 AG022791, K01 AG022791-01, K01 AG022791-05, N01 AG062101, N01 AG062103, N01 AG062106, R01 AG021024, R01 AG021024-05, R01-AG021024, T32 AG000181, T32 AG000181-19, U01 AG018197, U01 AG027810, U01 AG027810-01A1, U01 AG027810-02, U01 AG027810-03, U01 AG18197, U01-AG027810; NIAMS NIH HHS: R01 AR051124, R01 AR051124-04, R01-AR051124, U01 AR045580, U01 AR045583, U01 AR045632, U01 AR045647, U01 AR045647-01, U01 AR045647-02, U01 AR045647-03, U01 AR045647-04, U01 AR045647-04S1, U01 AR045647-05, U01 AR045647-06, U01 AR045647-07, U01 AR045654, U01 AR45580, U01 AR45583, U01 AR45614, U01 AR45632, U01 AR45647, U01 AR45654

    The journals of gerontology. Series A, Biological sciences and medical sciences 2008;63;11;1227-34

  • The parafibromin tumor suppressor protein interacts with actin-binding proteins actinin-2 and actinin-3.

    Agarwal SK, Simonds WF and Marx SJ

    National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland, USA. sunitaa@mail.nih.gov

    Background: Germline and somatic inactivating mutations in the HRPT2 gene occur in the inherited hyperparathyroidism-jaw tumor syndrome, in some cases of parathyroid cancer and in some cases of familial hyperparathyroidism. HRPT2 encodes parafibromin. To identify parafibromin interacting proteins we used the yeast two-hybrid system for screening a heart cDNA library with parafibromin as the bait.

    Results: Fourteen parafibromin interaction positive preys representing 10 independent clones encoding actinin-2 were isolated. Parafibromin interacted with muscle alpha-actinins (actinin-2 and actinin-3), but not with non-muscle alpha-actinins (actinin-1 and actinin-4). The parafibromin-actinin interaction was verified by yeast two-hybrid, GST pull-down, and co-immunoprecipitation. Yeast two-hybrid analysis revealed that the N-terminal region of parafibromin interacted with actinins. In actin sedimentation assays parafibromin did not dissociate skeletal muscle actinins from actin filaments, but interestingly, parafibromin could also bundle/cross-link actin filaments. Parafibromin was predominantly nuclear in undifferentiated proliferating myoblasts (C2C12 cells), but in differentiated C2C12 myotubes parafibromin co-localized with actinins in the cytoplasmic compartment.

    Conclusion: These data support a possible contribution of parafibromin outside the nucleus through its interaction with actinins and actin bundling/cross-linking. These data also suggest that actinins (and actin) participate in sequestering parafibromin in the cytoplasmic compartment.

    Funded by: Intramural NIH HHS

    Molecular cancer 2008;7;65

  • Association of the ACTN3 R577X polymorphism with power athlete status in Russians.

    Druzhevskaya AM, Ahmetov II, Astratenkova IV and Rogozkin VA

    Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, 2 Dynamo Avenue, St Petersburg, Russia. a.druzhevskaya@gmail.com

    The alpha-actinin-3 (ACTN3) gene encodes a Z-disc structural protein which is found only in fast glycolytic muscle fibers. A common nonsense polymorphism in codon 577 of the ACTN3 gene (R577X) results in alpha-actinin-3 deficiency in XX homozygotes. Previous reports have shown a lower proportion of the ACTN3 XX genotype in power-oriented athletes compared to the general population. In the present study we tested whether XX genotype was under-represented in Russian power-oriented athletes. The study involved 486 Russian power-oriented athletes of regional or national competitive standard. ACTN3 genotype and allele frequencies were compared to 1,197 controls. The frequencies of the ACTN3 XX genotype (6.4 vs. 14.2%; P < 0.0001) and X allele (33.3 vs. 38.7%; P = 0.004) were significantly lower in power-oriented athletes compared to controls. Furthermore, the lowest (3.4%) frequency of the ACTN3 XX genotype was found in a group of highly elite athletes, supporting the hypothesis that the presence of alpha-actinin-3 has a beneficial effect on the function of skeletal muscle in generating forceful contractions at high velocity. In conclusion, ACTN3 R577X polymorphism was associated with power athlete status in Russians.

    European journal of applied physiology 2008;103;6;631-4

  • Why is alpha-actinin-3 deficiency so common in the general population? The evolution of athletic performance.

    North K

    Institute for Neuromuscular Research, The Children's Hospital at Westmead, Sydney, Australia. kathryn@chw.edu.au

    'We can now explain how this common genetic variation influences athletic performance as well as why it has become so common in the general population. There is a fascinating link between factors that influence survival in ancient humans and the factors that contribute to athletic abilities in modern man.' The human ACTN3 gene encodes the protein alpha-actinin-3, a component of the contractile apparatus in fast skeletal muscle fibers. In 1999, we identified a common polymorphism in ACTN3 (R577X) that results in absence of alpha-actinin-3 in more than one billion people worldwide, despite the ACTN3 gene being highly conserved during human evolution. In 2003, we demonstrated that ACTN3 genotype influences elite athletic performance, and the association between ACTN3 genotype and skeletal muscle performance has since been replicated in athletes and non-athlete cohorts. We have also studied the evolution of the R577X allele during human evolution and demonstrated that the null (X) allele has undergone strong, recent positive selection in Europeans and Asian populations. We have developed an Actn3 knockout mouse model that replicates alpha-actinin-3 deficiency in humans and has already provided insight into the role of alpha-actinin-3 in the regulation of skeletal muscle metabolism, fibre size, muscle mass and contractile properties. In particular, mouse muscle lacking alpha-actinin-3 uses energy more efficiently, with the fast fibers displaying metabolic and contractile properties of slow oxidative fibers. While this favors endurance activities, the trade off is that the muscle cannot generate the rapid contractions needed to excel in sprinting. We propose that the shift towards more efficient aerobic muscle metabolism associated with alpha-actinin-3 deficiency also underlies the adaptive benefit of the 577X allele. Our future studies will focus on the effect of ACTN3 genotype on response to exercise and ageing, and the onset and severity of muscle disease phenotype.

    Twin research and human genetics : the official journal of the International Society for Twin Studies 2008;11;4;384-94

  • The ACTN3 gene in elite Greek track and field athletes.

    Papadimitriou ID, Papadopoulos C, Kouvatsi A and Triantaphyllidis C

    Laboratory of Sports Biomechanics, Aristotle University, Serres, Greece.

    The study of genetic influence in the making of an Olympic champion is still in its nascence, but recent work has provided findings regarding the association of the ACTN3 gene on athletic performance. The aim of this study was to examine genetic differences among elite Greek track and field athletes by analysing a mononucleotide polymorphism in exon 15 of the ACTN3 gene. Results showed that ACTN3 genotype and allele frequencies in the top power-oriented athletes were statistically significantly different from those in a representative random sample of the Greek population: the frequency of the RR ACTN3 genotype in power-oriented athletes vs. the general population was 47.94 % vs. 25.97 %. This result was even more prominent for comparison of the subgroup of sprinters to controls. The results suggest an overall strong association between the presence of the RR genotype and elite power performance.

    International journal of sports medicine 2008;29;4;352-5

  • The ACTN3 R577X nonsense allele is under-represented in elite-level strength athletes.

    Roth SM, Walsh S, Liu D, Metter EJ, Ferrucci L and Hurley BF

    Department of Kinesiology, University of Maryland College Park School of Public Health, College Park, MD, USA. sroth1@umd.edu

    Previous reports have shown a lower proportion of the ACTN3 X/X genotype (R577X nonsense polymorphism) in sprint-related athletes compared to the general population, possibly attributed to impairment of muscle function related to alpha-actinin-3 deficiency. In the present study, we examined the frequency of the X/X genotype in both Black and White elite-level bodybuilders and strength athletes in comparison to the general population. A reference population of 668 Whites (363 men and 305 women) and 208 Blacks (98 men and 110 women) was genotyped for the ACTN3 R577X polymorphism. Strength athletes (52 white and 23 black; 4 women) consisting predominantly of world class and locally competitive bodybuilders, and elite powerlifters were recruited and similarly genotyped. Significantly lower X/X genotype frequencies were observed in the athletes (6.7%) vs controls (16.3%; P=0.005). The X/X genotype was significantly lower in White athletes (9.7%) vs controls (19.9%; P=0.018). No black athletes (0%) were observed with the X/X genotype, though this finding only approached statistical significance vs controls (4.8%; P=0.10). The results indicate that the ACTN3 R577X nonsense allele (X) is under-represented in elite strength athletes, consistent with previous reports indicating that alpha-actinin-3 deficiency appears to impair muscle performance.

    Funded by: Intramural NIH HHS: Z99 AG999999; NIA NIH HHS: K01 AG022791, L30 AG024705, L30 AG024705-03, R01 AG021500, R01 AG021500-03

    European journal of human genetics : EJHG 2008;16;3;391-4

  • ACTN3 genotype in professional soccer players.

    Santiago C, González-Freire M, Serratosa L, Morate FJ, Meyer T, Gómez-Gallego F and Lucia A

    Universidad Europea de Madrid, Villaviciosa de Odón, Madrid 28670, Spain. alejandro.lucia@uem.es

    The authors studied the frequency distribution of alpha-actinin-3 (ACTN3) R577X genotypes in 60 top-level professional soccer players. The results were compared with those of 52 elite endurance athletes and 123 sedentary controls. The per cent distribution of RR and RX genotypes in soccer players (48.3% and 36.7%) was significantly higher and lower, respectively, than controls (28.5% and 53.7%) and endurance athletes (26.5% and 52%) (p = 0.041). Although there are notable exceptions, elite soccer players tend to have the sprint/power ACTN3 genotype.

    British journal of sports medicine 2008;42;1;71-3

  • ACTN3 (R577X) genotype is associated with fiber type distribution.

    Vincent B, De Bock K, Ramaekers M, Van den Eede E, Van Leemputte M, Hespel P and Thomis MA

    Research Centre for Exercise and Health, Department of Biomedical Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.

    alpha-Actinin-3 is a Z-disc structural protein found only in type II muscle fibers. The X allele of the R577X polymorphism in the ACTN3 gene results in a premature stop codon and alpha-actinin-3 deficiency in XX homozygotes. Associations between the R577X polymorphism and the muscle-power performance of elite athletes have been described earlier. About 45% of the fiber type proportions are determined by genetic factors. The ACTN3 variant could be one of the contributing genes in the heritability of fiber type distribution through its interaction with calcineurin. The aim of this study was to quantify the association between the polymorphism and muscle fiber type distribution and fast-velocity knee extension strength. Ninety healthy young men (18-29 y) were genotyped for ACTN3 R577X. Knee extensor strength was measured isometrically (45 degrees ) and at different dynamic velocities (100-300 degrees /s) on a programmable dynamometer. Twenty-two XX and twenty-two RR subjects underwent a biopsy of the right vastus lateralis muscle. Fiber type composition was determined by immunohistochemistry. Homozygotes for the R allele show significantly higher relative dynamic quadriceps torques at 300 degrees /s, compared with XX carriers (P < 0.05). Fiber type characteristics differed significantly between the two genotype groups. The percentage surface and number of type IIx fibers were greater in the RR than the XX genotype group (P < 0.05), and alpha-actinin-3 protein content is systematically higher in type IIx compared with type IIa fibers (staining intensity ratio IIx to IIa = 1.17). This study shows that the mechanism, by which the ACTN3 polymorphism has its effect on muscle power, might rely on a control function of fiber type proportions.

    Physiological genomics 2007;32;1;58-63

  • The ACTN3 R577X polymorphism in East and West African athletes.

    Yang N, MacArthur DG, Wolde B, Onywera VO, Boit MK, Lau SY, Wilson RH, Scott RA, Pitsiladis YP and North K

    Institute for Neuromuscular Research, Children's Hospital at Westmead, Sydney, Australia.

    Purpose: To determine the frequency of the ACTN3 R577X polymorphism (functional R allele and nonfunctional X allele) in a variety of African populations and to examine its influence on the success of elite East African endurance runners and West African sprinters.

    Methods: The R577X polymorphism was genotyped in 198 Ethiopian controls and 76 elite Ethiopian endurance athletes, 158 Kenyan controls and 284 elite Kenyan endurance runners, and 60 Nigerian controls and 62 elite Nigerian power athletes. Statistical analyses were performed by exact tests of population differentiation, using Arlequin, version 3. Analyses were carried out using 1 x 10(6) Markov chain steps, and 1 x 10(5) dememorization steps.

    Results: The frequency of the X allele was extremely low among Kenyans and Nigerians (approximately 1% homozygosity) and higher in Ethiopians (approximately 11% homozygosity). The low baseline frequencies of the three populations tested mean that any associations with sprint performance would likely be obscured. In Ethiopians, where baseline levels of 577XX were about 11%, there was no increased frequency in the endurance athletes.

    Conclusion: Our data suggest that alpha-actinin-3 deficiency is not a major influence on performance in African athletes.

    Medicine and science in sports and exercise 2007;39;11;1985-8

  • No association of the ACTN3 gene R577X polymorphism with endurance performance in Ironman Triathlons.

    Saunders CJ, September AV, Xenophontos SL, Cariolou MA, Anastassiades LC, Noakes TD and Collins M

    MRC/UCT Research Unit for Exercise Science and Sports Medicine of the Department of Human Biology, University of Cape Town, South Africa.

    Alpha-actinins are major structural components of the Z-discs in skeletal muscle. Alpha-actinin 3 is encoded by the ACTN3 gene and is expressed only in type II muscle fibres. Homozygosity for the nonsense mutation, 577X, within ACTN3 results in deficiency of alpha-actinin-3 but does not result in an abnormal muscular phenotype. Previous research has found an association of the 577R allele with sprinting and/or power performance. It has also been suggested that the 577X allele may confer an advantage during endurance events. Four hundred and fifty seven Caucasian male triathletes who completed either the 2000 and/or 2001 226 km South African Ironman Triathlons, and 143 Caucasian controls, were genotyped for the R577X mutation within the ACTN3 gene. There were no significant differences in either the genotype (P = 0.486) or allele (P = 0.375) frequencies within the fastest, middle of the field or slowest Caucasian male finishers and the control population. In conclusion, the R577X polymorphism within the ACTN3 gene was not associated with ultra-endurance performance in the 2000 and 2001 South African Ironman Triathlons.

    Annals of human genetics 2007;71;Pt 6;777-81

  • The 577X allele of the ACTN3 gene is associated with improved exercise capacity in women with McArdle's disease.

    Lucia A, Gómez-Gallego F, Santiago C, Pérez M, Maté-Muñoz JL, Chamorro-Viña C, Nogales-Gadea G, Foster C, Rubio JC, Andreu AL, Martín MA and Arenas J

    Universidad Europea de Madrid, Madrid, Spain. alejandro.lucia@uem.es

    We assessed the possible association existing between alpha-actinin-3 (ACTN3) R577X genotypes and the capacity for performing aerobic exercise in McArdle's patients. Forty adult McArdle's disease patients and forty healthy, age and gender-matched sedentary controls (21 men, 19 women in both groups) performed a graded test until exhaustion and a constant-load test on a cycle-ergometer to determine clinically relevant indices of exercise capacity as peak oxygen uptake (VO(2peak)) and the ventilatory threshold (VT). In the group of diseased women, carriers of the X allele had a higher (P<0.01) VO(2peak) (15.0+/-1.2 ml/kg/min) and a higher (P<0.05) oxygen uptake (VO(2)) at the VT (11.2+/-1 ml/kg/min) than R/R homozygotes (VO(2peak): 9.6+/-0.5 ml/kg/min; VO(2) at the VT: 8.2+/-0.7 ml/kg/min). No differences were found in male patients. In women with McArdle's disease, ACTN3 genotypes might partly explain the large individual variability that exists in the phenotypic manifestation of this disorder.

    Neuromuscular disorders : NMD 2007;17;8;603-10

  • Genotype modulators of clinical severity in McArdle disease.

    Rubio JC, Gómez-Gallego F, Santiago C, García-Consuegra I, Pérez M, Barriopedro MI, Andreu AL, Martín MA, Arenas J and Lucia A

    Centro de Investigación, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain.

    The phenotypic manifestation of McArdle disease varies considerably from one individual to the next. The purpose of this study was to assess the possible association between the clinical severity of the disease, and each of the genotypes PYGM (R50X), ACE (I/D), AMPD1 (Q12X), PPARGC1A (G482S) and ACTN3 (R577X). We also assessed links between clinical disease severity and other potential phenotype modulators such as age or gender. McArdle disease was diagnosed in 99 patients of Spanish origin (60 male, 39 female; age range 8-81 years) by identifying the two mutant alleles of the PYGM gene. Disease severity was assessed using the grading scheme previously reported by Martinuzzi et al. [A. Martinuzzi, E. Sartori, M. Fanin, et al., Phenotype modulators in myophosphorylase deficiency, Ann. Neurol. 53 (2003) 497-502]. Significant correlation was observed (exact two-sided P<0.0001) between the number of D alleles of the ACE gene and the disease severity score. Rank-order correlation coefficients were 0.296 (95% CI: 0.169, 0.423) (Kendall's tau) and 0.345 (95% CI: 0.204, 0.486) (Somer's D). No significant relationships were detected between clinical severity and the remaining genotypes examined. Finally, disease severity was significantly worse in women with the disease. Our findings indicate that both ACE genotype and gender contribute to how McArdle disease manifests in an individual patient. The role of other candidate genes remains to be elucidated.

    Neuroscience letters 2007;422;3;217-22

  • ACTN3 genotyping by real-time PCR in the Italian population and athletes.

    Paparini A, Ripani M, Giordano GD, Santoni D, Pigozzi F and Romano-Spica V

    Department of Health Sciences, University of Movement Sciences, Rome, Italy.

    Purpose: Development of two novel sets of primers and probes to detect R577X and Q523R polymorphisms of the alpha-actinin-3 (ACTN3) gene by real-time PCR. We report the allelic frequencies observed in Italian individuals from the general population and athletes. Athletic performance is influenced by training, environmental factors, and genetic predisposition. Actn3 belongs to a family of actin-binding proteins and is supposed to influence sport performance.

    Methods: Primer-probe set design and protocol optimization for real-time PCR genotyping of R577X and Q523R polymorphisms. The assay was verified using a traditional PCR-RFLP approach and applied on an Italian population sample (102 male subjects and 42 athletes).

    Results: Haplotype distribution confirmed the presence of linkage disequilibrium between the polymorphisms, both in the Italian general population and athletes (respectively: chi = 54.4, P < or = 0.001 and chi = 24.5, P < or = 0.001). Within the general population, a large percentage of homozygous subjects (21.6%) was deficient for Actn3. No significant differences were observed in athletes. The concordance between PCR-RFLP and real-time PCR results was 100and 93% for polymorphisms Q523R and R577X, respectively.

    Conclusion: Real-time PCR represents an effective approach for typing ACTN3 alleles. Allelic frequencies in the Italian population are consistent with those seen in other studies on Caucasians.

    Medicine and science in sports and exercise 2007;39;5;810-5

  • Alpha-actinin-3 (ACTN3) R577X polymorphism influences knee extensor peak power response to strength training in older men and women.

    Delmonico MJ, Kostek MC, Doldo NA, Hand BD, Walsh S, Conway JM, Carignan CR, Roth SM and Hurley BF

    Department of Kinesiology, University of Maryland, College Park, MD 20742, USA.

    Background: The alpha-actinin-3 (ACTN3) R577X polymorphism has been associated with muscle power performance in cross-sectional studies.

    Methods: We examined baseline knee extensor concentric peak power (PP) and PP change with approximately 10 weeks of unilateral knee extensor strength training (ST) using air-powered resistance machines in 71 older men (65 [standard deviation = 8] years) and 86 older women (64 [standard deviation = 9] years).

    Results: At baseline in women, the XX genotype group had an absolute (same resistance) PP that was higher than the RR (p =.005) and RX genotype groups (p =.02). The women XX group also had a relative (70% of one-repetition maximum [1-RM]) PP that was higher than that in the RR (p =.002) and RX groups (p =.008). No differences in baseline absolute or relative PP were observed between ACTN3 genotype groups in men. In men, absolute PP change with ST in the RR (n = 16) group approached a significantly higher value than in the XX group (n = 9; p =.07). In women, relative PP change with ST in the RR group (n = 16) was higher than in the XX group (n = 17; p =.02).

    Conclusions: The results indicate that the ACTN3 R577X polymorphism influences the response of quadriceps muscle power to ST in older adults.

    Funded by: NIA NIH HHS: 1-AG-4-2148, AG-021500, AG-022791, AG-1620501

    The journals of gerontology. Series A, Biological sciences and medical sciences 2007;62;2;206-12

  • Association analysis of the ACTN3 R577X polymorphism and complex quantitative body composition and performance phenotypes in adolescent Greeks.

    Moran CN, Yang N, Bailey ME, Tsiokanos A, Jamurtas A, MacArthur DG, North K, Pitsiladis YP and Wilson RH

    Institute of Diet, Exercise and Lifestyle (IDEAL) and Division of Molecular Genetics, Faculty of Biomedical & Life Sciences, University of Glasgow, Glasgow, UK.

    The functional allele (577R) of ACTN3, which encodes human alpha-actinin-3, has been reported to be associated with elite athletic status and with response to resistance training, while the nonfunctional allele (577X) has been proposed as a candidate metabolically thrifty allele. In a study of 992 adolescent Greeks, we show that there is a significant association (P=0.003) between the ACTN3 R577X polymorphism and 40 m sprint time in males that accounts for 2.3% of phenotypic variance, with the 577R allele contributing to faster times in an additive manner. The R577X polymorphism is not associated with other power phenotypes related to 40 m sprint, nor with an endurance phenotype. Furthermore, the polymorphism is not associated with obesity-related phenotypes in our population, suggesting that the 577X allele is not a thrifty allele, and thus the persistence of this null allele must be explained in other terms.

    European journal of human genetics : EJHG 2007;15;1;88-93

  • Disruption of alpha-actinin-integrin interactions at focal adhesions renders osteoblasts susceptible to apoptosis.

    Triplett JW and Pavalko FM

    Dept. of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.

    Maintenance of bone structural integrity depends in part on the rate of apoptosis of bone-forming osteoblasts. Because substrate adhesion is an important regulator of apoptosis, we have investigated the role of focal adhesions in regulating bone cell apoptosis. To test this, we expressed a truncated form of alpha-actinin (ROD-GFP) that competitively displaces endogenous alpha-actinin from focal adhesions, thus disrupting focal adhesions. Immunofluorescence and morphometric analysis of vinculin and tyrosine phosphorylation revealed that ROD-GFP expression dramatically disrupted focal adhesion organization and reduced tyrosine phosphorylation at focal adhesions. In addition, Bcl-2 protein levels were reduced in ROD-GFP-expressing cells, but caspase 3 cleavage, poly(ADP-ribose) polymerase cleavage, histone H2A.X phosphorylation, and cytotoxicity were not increased due to ROD-GFP expression alone. Increases in both ERK and Akt phosphorylation were also observed in ROD-GFP-expressing cells, although inhibition of either ERK or Akt individually or together failed to induce apoptosis. However, we did find that ROD-GFP expression sensitized, whereas alpha-actinin-GFP expression protected, cells from TNF-alpha-induced apoptosis. Further investigation revealed that activation of TNF-alpha-induced survival signals, specifically Akt phosphorylation and NF-kappaB activation, was inhibited in ROD-GFP-expressing cells. The reduced expression of antiapoptotic Bcl-2 and inhibited survival signaling rendered ROD-GFP-expressing cells more susceptible to TNF-alpha-induced apoptosis. Thus we conclude that alpha-actinin plays a role in regulating cell survival through stabilization of focal adhesions and regulation of TNF-alpha-induced survival signaling.

    Funded by: NIAMS NIH HHS: R01 AR-49728, R01 AR052682, R01 AR052682-01A1

    American journal of physiology. Cell physiology 2006;291;5;C909-21

  • ACTN3 and MLCK genotype associations with exertional muscle damage.

    Clarkson PM, Hoffman EP, Zambraski E, Gordish-Dressman H, Kearns A, Hubal M, Harmon B and Devaney JM

    Dept. of Exercise Science, University of Massachusetts, Amherst, MA 01003, USA. clarkson@excsci.umass.edu

    Strenuous exercise results in damage to skeletal muscle that is manifested in delayed muscle pain, prolonged strength loss, and increases in muscle proteins in the blood, especially creatine kinase (CK) and myoglobin (Mb). Some individuals experience profound changes in these variables in response to standard laboratory exercise or recreational activities. We proposed that variations in genes coding for two myofibrillar proteins [alpha-actinin 3 (ACTN3) and myosin light chain kinase (MLCK)] may explain the large variability in the response to muscle-damaging exercise. We hypothesized that subjects with specific single nucleotide polymorphisms (SNPs) in ACTN3 and MLCK would show a greater loss in muscle strength and/or a greater increase in blood CK and Mb in response to eccentric exercise. Blood from 157 subjects who performed a standard elbow flexion eccentric exercise protocol was tested for association between genotypes of ACTN3 (1 SNP tested: R577X) and MLCK (2 SNPs tested: C49T and C37885A) and changes in blood CK and Mb and isometric strength. Subjects possessing the ACTN3-deficient genotype (XX) had lower baseline CK compared with the heterozygotes (P = 0.035). After the eccentric exercise, those subjects homozygous for the MLCK 49T rare allele had a significantly greater increase in CK and Mb (P < 0.01) compared with the heterozygotes, and those heterozygous for MLCK C37885A had a significantly greater increase in CK compared with the homozygous wild type (P < 0.05). There was only one subject homozygous for the rare MLCK 37885A allele. MLCK C37885A was also associated with postexercise strength loss (P < 0.05); the heterozygotes demonstrated greater strength loss compared with the homozygous wild type (CC). These results show that variations in genes coding for specific myofibrillar proteins influence phenotypic responses to muscle damaging exercise.

    Journal of applied physiology (Bethesda, Md. : 1985) 2005;99;2;564-9

  • Mitochondrial DNA and ACTN3 genotypes in Finnish elite endurance and sprint athletes.

    Niemi AK and Majamaa K

    Department of Neurology, University of Oulu, Finland.

    Differences in ACTN3 (alpha-actinin 3) genotypes have been reported among endurance and power athletes. Elite athletic performance in endurance sports should also depend on mitochondrial oxidative phosphorylation (OXPHOS) that produces ATP for muscle metabolism. We determined mitochondrial DNA (mtDNA) and ACTN3 genotypes in Finnish elite endurance (n = 52) and sprint (n = 89) athletes, and found that the frequencies of mtDNA haplogroups differed significantly between the two groups. Most notably, none of the endurance athletes belonged to haplogroup K or subhaplogroup J2, both of which have previously been associated with longevity. The frequency of ACTN3 XX genotype was higher and that of RR was lower among Finnish endurance athletes, and, in addition, none of the top Finnish sprinters had the XX genotype. Lack of mtDNA haplogroup K and subhaplogroup J2 among elite endurance athletes suggests that these haplogroups are 'uncoupling genomes'. Such genomes should not be beneficial to endurance-type athletic performance but should be beneficial to longevity, since uncoupling of OXPHOS reduces the production of ATP, reduces the release of reactive oxygen species and generates heat.

    European journal of human genetics : EJHG 2005;13;8;965-9

  • ACTN3 genotype is associated with increases in muscle strength in response to resistance training in women.

    Clarkson PM, Devaney JM, Gordish-Dressman H, Thompson PD, Hubal MJ, Urso M, Price TB, Angelopoulos TJ, Gordon PM, Moyna NM, Pescatello LS, Visich PS, Zoeller RF, Seip RL and Hoffman EP

    Dept. of Exercise Science, Univ. of Massachusetts, Amherst, MA 01003, USA. clarkson@excsci.umass.edu

    The alpha-actinin 3 (ACTN3) gene encodes a protein of the Z disk of myofibers, and a polymorphism of ACTN3 results in complete loss of the protein. The ACTN3 genotype (R577X) has been found to be associated with performance in Australian elite athletes (Yang N, MacArthur DG, Gulbin JP, Hahn AG, Beggs AH, Easteal S, and North K. Am J Hum Genet 73: 627-631, 2003). We studied associations between ACTN3 genotype and muscle size [cross-sectional area of the biceps brachii via magnetic resonance imaging (MRI)] and elbow flexor isometric (MVC) and dynamic [1-repetition maximum (1-RM)] strength in a large group of men (N = 247) and women (N = 355) enrolled in a 12-wk standardized elbow flexor/extensor resistance training program of the nondominant arm at one of eight study centers. We found no association between ACTN3 R577X genotype and muscle phenotype in men. However, women homozygous for the ACTN3 577X allele (XX) had lower baseline MVC compared with heterozygotes (P < 0.05) when adjusted for body mass and age. Women homozygous for the mutant allele (577X) demonstrated greater absolute and relative 1-RM gains compared with the homozygous wild type (RR) after resistance training when adjusted for body mass and age (P < 0.05). There was a trend for a dose-response with genotype such that gains were greatest for XX and least for RR. Significant associations were validated in at least one ethnic subpopulation (Caucasians, Asians) and were independent of training volume. About 2% of baseline MVC and of 1-RM strength gain after training were attributable to ACTN3 genotype (likelihood-ratio test P value, P = 0.01), suggesting that ACTN3 is one of many genes contributing to genetic variation in muscle performance and adaptation to exercise.

    Funded by: NINDS NIH HHS: R01 NS40606

    Journal of applied physiology (Bethesda, Md. : 1985) 2005;99;1;154-63

  • Synaptopodin regulates the actin-bundling activity of alpha-actinin in an isoform-specific manner.

    Asanuma K, Kim K, Oh J, Giardino L, Chabanis S, Faul C, Reiser J and Mundel P

    Department of Medicine, Albert Einstein College of Medicine, New York, New York, USA.

    Synaptopodin is the founding member of a novel class of proline-rich actin-associated proteins highly expressed in telencephalic dendrites and renal podocytes. Synaptopodin-deficient (synpo(-/-)) mice lack the dendritic spine apparatus and display impaired activity-dependent long-term synaptic plasticity. In contrast, the ultrastructure of podocytes in synpo(-/-) mice is normal. Here we show that synpo(-/-) mice display impaired recovery from protamine sulfate-induced podocyte foot process (FP) effacement and LPS-induced nephrotic syndrome. Similarly, synpo(-/-) podocytes show impaired actin filament reformation in vitro. We further demonstrate that synaptopodin exists in 3 isoforms, neuronal Synpo-short (685 AA), renal Synpo-long (903 AA), and Synpo-T (181 AA). The C terminus of Synpo-long is identical to that of Synpo-T. All 3 isoforms specifically interact with alpha-actinin and elongate alpha-actinin-induced actin filaments. synpo(-/-) mice lack Synpo-short and Synpo-long expression but show an upregulation of Synpo-T protein expression in podocytes, though not in the brain. Gene silencing of Synpo-T abrogates stress-fiber formation in synpo(-/-) podocytes, demonstrating that Synpo-T serves as a backup for Synpo-long in synpo(-/-) podocytes. In concert, synaptopodin regulates the actin-bundling activity of alpha-actinin in highly dynamic cell compartments, such as podocyte FPs and the dendritic spine apparatus.

    Funded by: NIDA NIH HHS: DA18886, R01 DA018886; NIDDK NIH HHS: DK062472, DK064236, DK57683, P50 DK064236, R01 DK057683, R01 DK062472

    The Journal of clinical investigation 2005;115;5;1188-98

  • The crystal structure of the actin binding domain from alpha-actinin in its closed conformation: structural insight into phospholipid regulation of alpha-actinin.

    Franzot G, Sjöblom B, Gautel M and Djinović Carugo K

    Structural Biology Laboratory, Elettra-Sincrotrone Trieste in Area Science Park, S.S. 14 Km 163,5 34012 Trieste, Italy.

    Alpha-actinin is the major F-actin crosslinking protein in both muscle and non-muscle cells. We report the crystal structure of the actin binding domain of human muscle alpha-actinin-3, which is formed by two consecutive calponin homology domains arranged in a "closed" conformation. Structural studies and available biochemical data on actin binding domains suggest that two calponin homology domains come in a closed conformation in the native apo-form, and that conformational changes involving the relative orientation of the two calponin homology domains are required for efficient binding to actin filaments. The actin binding activity of muscle isoforms is supposed to be regulated by phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), which binds to the second calponin homology domain. On the basis of structural analysis we propose a distinct binding site for PtdIns(4,5)P2, where the fatty acid moiety would be oriented in a direction that allows it to interact with the linker sequence between the actin binding domain and the first spectrin-like repeat, regulating thereby the binding of the C-terminal calmodulin-like domain to this linker.

    Journal of molecular biology 2005;348;1;151-65

  • The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

    Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Morrin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J and MGC Project Team

    The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

    Funded by: PHS HHS: N01-C0-12400

    Genome research 2004;14;10B;2121-7

  • A gene for speed? The evolution and function of alpha-actinin-3.

    MacArthur DG and North KN

    The Children's Hospital at Westmead, Westmead, Sydney, Australia.

    The alpha-actinins are an ancient family of actin-binding proteins that play structural and regulatory roles in cytoskeletal organisation and muscle contraction. alpha-actinin-3 is the most-highly specialised of the four mammalian alpha-actinins, with its expression restricted largely to fast glycolytic fibres in skeletal muscle. Intriguingly, a significant proportion ( approximately 18%) of the human population is totally deficient in alpha-actinin-3 due to homozygosity for a premature stop codon polymorphism (R577X) in the ACTN3 gene. Recent work in our laboratory has revealed a strong association between R577X genotype and performance in a variety of athletic endeavours. We are currently exploring the function and evolutionary history of the ACTN3 gene and other alpha-actinin family members. The alpha-actinin family provides a fascinating case study in molecular evolution, illustrating phenomena such as functional redundancy in duplicate genes, the evolution of protein function, and the action of natural selection during recent human evolution.

    BioEssays : news and reviews in molecular, cellular and developmental biology 2004;26;7;786-95

  • The adenosine A2A receptor interacts with the actin-binding protein alpha-actinin.

    Burgueño J, Blake DJ, Benson MA, Tinsley CL, Esapa CT, Canela EI, Penela P, Mallol J, Mayor F, Lluis C, Franco R and Ciruela F

    Department of Biochemistry and Molecular Biology, University of Barcelona, 08028 Barcelona, Spain.

    Recently, evidence has emerged that heptaspanning membrane or G protein-coupled receptors may be linked to intracellular proteins identified as regulators of receptor anchoring and signaling. Using a yeast two-hybrid screen, we identified alpha-actinin, a major F-actin-cross-linking protein, as a binding partner for the C-terminal domain of the adenosine A2A receptor (A2AR). Colocalization, co-immunoprecipitation, and pull-down experiments showed a close and specific interaction between A2AR and alpha-actinin in transfected HEK-293 cells and also in rat striatal tissue. A2AR activation by agonist induced the internalization of the receptor by a process that involved rapid beta-arrestin translocation from the cytoplasm to the cell surface. In the subsequent receptor traffic from the cell surface, the role of actin organization was shown to be crucial in transiently transfected HEK-293 cells, as actin depolymerization by cytochalasin D prevented its agonist-induced internalization. A2ADeltaCTR, a mutant version of A2AR that lacks the C-terminal domain and does not interact with alpha-actinin, was not able to internalize when activated by agonist. Interestingly, A2ADeltaCTR did not show aggregation or clustering after agonist stimulation, a process readily occurring with the wild-type receptor. These findings suggest an alpha-actinin-dependent association between the actin cytoskeleton and A2AR trafficking.

    The Journal of biological chemistry 2003;278;39;37545-52

  • ACTN3 genotype is associated with human elite athletic performance.

    Yang N, MacArthur DG, Gulbin JP, Hahn AG, Beggs AH, Easteal S and North K

    Institute for Neuromuscular Research, Children's Hospital at Westmead, Sydney, Australia.

    There is increasing evidence for strong genetic influences on athletic performance and for an evolutionary "trade-off" between performance traits for speed and endurance activities. We have recently demonstrated that the skeletal-muscle actin-binding protein alpha-actinin-3 is absent in 18% of healthy white individuals because of homozygosity for a common stop-codon polymorphism in the ACTN3 gene, R577X. alpha-Actinin-3 is specifically expressed in fast-twitch myofibers responsible for generating force at high velocity. The absence of a disease phenotype secondary to alpha-actinin-3 deficiency is likely due to compensation by the homologous protein, alpha-actinin-2. However, the high degree of evolutionary conservation of ACTN3 suggests function(s) independent of ACTN2. Here, we demonstrate highly significant associations between ACTN3 genotype and athletic performance. Both male and female elite sprint athletes have significantly higher frequencies of the 577R allele than do controls. This suggests that the presence of alpha-actinin-3 has a beneficial effect on the function of skeletal muscle in generating forceful contractions at high velocity, and provides an evolutionary advantage because of increased sprint performance. There is also a genotype effect in female sprint and endurance athletes, with higher than expected numbers of 577RX heterozygotes among sprint athletes and lower than expected numbers among endurance athletes. The lack of a similar effect in males suggests that the ACTN3 genotype affects athletic performance differently in males and females. The differential effects in sprint and endurance athletes suggests that the R577X polymorphism may have been maintained in the human population by balancing natural selection.

    American journal of human genetics 2003;73;3;627-31

  • New N-RAP-binding partners alpha-actinin, filamin and Krp1 detected by yeast two-hybrid screening: implications for myofibril assembly.

    Lu S, Carroll SL, Herrera AH, Ozanne B and Horowits R

    Laboratory of Muscle Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

    N-RAP, a muscle-specific protein concentrated at myotendinous junctions in skeletal muscle and intercalated disks in cardiac muscle, has been implicated in myofibril assembly. To discover more about the role of N-RAP in myofibril assembly, we used the yeast two-hybrid system to screen a mouse skeletal muscle cDNA library for proteins capable of binding N-RAP in a eukaryotic cell. From yeast two-hybrid experiments we were able to identify three new N-RAP binding partners: alpha-actinin, filamin-2, and Krp1 (also called sarcosin). In vitro binding assays were used to verify these interactions and to identify the N-RAP domains involved. Three regions of N-RAP were expressed as His-tagged recombinant proteins, including the nebulin-like super repeat region (N-RAP-SR), the N-terminal LIM domain (N-RAP-LIM), and the region of N-RAP in between the super repeat region and the LIM domain (N-RAP-IB). We detected significant alpha-actinin binding to N-RAP-IB and N-RAP-LIM, filamin binding to N-RAP-SR, and Krp1 binding to N-RAP-SR and N-RAP-IB. During myofibril assembly in cultured chick cardiomyocytes, N-RAP and filamin appear to co-localize with alpha-actinin in the earliest myofibril precursors found near the cell periphery, as well as in the nascent myofibrils that form as these structures fuse laterally. In contrast, Krp1 is not localized until late in the assembly process, when it appears at the periphery of myofibrils that appear to be fusing laterally. The results suggest that sequential recruitment of N-RAP binding partners may serve an important role during myofibril assembly.

    Journal of cell science 2003;116;Pt 11;2169-78

  • Differential expression of the actin-binding proteins, alpha-actinin-2 and -3, in different species: implications for the evolution of functional redundancy.

    Mills M, Yang N, Weinberger R, Vander Woude DL, Beggs AH, Easteal S and North K

    Neurogenetics Research Unit, Children's Hospital at Westmead, Westmead, Sydney, NSW 2145, Australia.

    The alpha-actinins are a multigene family of four actin-binding proteins related to dystrophin. The two skeletal muscle isoforms of alpha-actinin (ACTN2 and ACTN3) are major structural components of the Z-line involved in anchoring the actin-containing thin filaments. In humans, ACTN2 is expressed in all muscle fibres, while ACTN3 expression is restricted to a subset of type 2 fibres. We have recently demonstrated that alpha-actinin-3 is absent in approximately 18% of individuals in a range of human populations, and that homozygosity for a premature stop codon (577X) accounts for most cases of true alpha-actinin-3 deficiency. Absence of alpha-actinin-3 is not associated with an obvious disease phenotype, raising the possibility that ACTN3 is functionally redundant in humans, and that alpha-actinin-2 is able to compensate for alpha-actinin-3 deficiency. We now present data concerning the expression of ACTN3 in other species. Genotyping of non-human primates indicates that the 577X null mutation has likely arisen in humans. The mouse genome contains four orthologues which all map to evolutionarily conserved syntenic regions for the four human genes. Murine Actn2 and Actn3 are differentially expressed, spatially and temporally, during embryonic development and, in contrast to humans, alpha-actinin-2 expression does not completely overlap alpha-actinin-3 in postnatal skeletal muscle, suggesting independent function. Furthermore, sequence comparison of human, mouse and chicken alpha-actinin genes demonstrates that ACTN3 has been conserved over a long period of evolutionary time, implying a constraint on evolutionary rate imposed by continued function of the gene. These observations provide a real framework in which to test theoretical models of genetic redundancy as they apply to human populations. In addition we highlight the need for caution in making conclusions about gene function from the phenotypic consequences of loss-of-function mutations in animal knockout models.

    Funded by: NIAMS NIH HHS: K02 AR02026, R01 AR44345

    Human molecular genetics 2001;10;13;1335-46

  • Myopalladin, a novel 145-kilodalton sarcomeric protein with multiple roles in Z-disc and I-band protein assemblies.

    Bang ML, Mudry RE, McElhinny AS, Trombitás K, Geach AJ, Yamasaki R, Sorimachi H, Granzier H, Gregorio CC and Labeit S

    European Molecular Biology Laboratory, Heidelberg 69117, Germany.

    We describe here a novel sarcomeric 145-kD protein, myopalladin, which tethers together the COOH-terminal Src homology 3 domains of nebulin and nebulette with the EF hand motifs of alpha-actinin in vertebrate Z-lines. Myopalladin's nebulin/nebulette and alpha-actinin-binding sites are contained in two distinct regions within its COOH-terminal 90-kD domain. Both sites are highly homologous with those found in palladin, a protein described recently required for actin cytoskeletal assembly (Parast, M.M., and C.A. Otey. 2000. J. Cell Biol. 150:643-656). This suggests that palladin and myopalladin may have conserved roles in stress fiber and Z-line assembly. The NH(2)-terminal region of myopalladin specifically binds to the cardiac ankyrin repeat protein (CARP), a nuclear protein involved in control of muscle gene expression. Immunofluorescence and immunoelectron microscopy studies revealed that myopalladin also colocalized with CARP in the central I-band of striated muscle sarcomeres. Overexpression of myopalladin's NH(2)-terminal CARP-binding region in live cardiac myocytes resulted in severe disruption of all sarcomeric components studied, suggesting that the myopalladin-CARP complex in the central I-band may have an important regulatory role in maintaining sarcomeric integrity. Our data also suggest that myopalladin may link regulatory mechanisms involved in Z-line structure (via alpha-actinin and nebulin/nebulette) to those involved in muscle gene expression (via CARP).

    Funded by: NHLBI NIH HHS: HL03985, HL57461, HL61497, HL62881, R01 HL057461, R01 HL061497, R01 HL062881, R29 HL057461, T32 HL007249

    The Journal of cell biology 2001;153;2;413-27

  • Myozenin: an alpha-actinin- and gamma-filamin-binding protein of skeletal muscle Z lines.

    Takada F, Vander Woude DL, Tong HQ, Thompson TG, Watkins SC, Kunkel LM and Beggs AH

    Division of Genetics, Children's Hospital, Boston, MA 02115, USA.

    To better understand the structure and function of Z lines, we used sarcomeric isoforms of alpha-actinin and gamma-filamin to screen a human skeletal muscle cDNA library for interacting proteins by using the yeast two-hybrid system. Here we describe myozenin (MYOZ), an alpha-actinin- and gamma-filamin-binding Z line protein expressed predominantly in skeletal muscle. Myozenin is predicted to be a 32-kDa, globular protein with a central glycine-rich domain flanked by alpha-helical regions with no strong homologies to any known genes. The MYOZ gene has six exons and maps to human chromosome 10q22.1-q22.2. Northern blot analysis demonstrated that this transcript is expressed primarily in skeletal muscle with significantly lower levels of expression in several other tissues. Antimyozenin antisera stain skeletal muscle in a sarcomeric pattern indistinguishable from that seen by using antibodies for alpha-actinin, and immunogold electron microscopy confirms localization specifically to Z lines. Thus, myozenin is a skeletal muscle Z line protein that may be a good candidate gene for limb-girdle muscular dystrophy or other neuromuscular disorders.

    Funded by: NIAMS NIH HHS: K02 AR02026, R01 AR044345, R01 AR44345; NICHD NIH HHS: P30 HD018655, P30 HD18655

    Proceedings of the National Academy of Sciences of the United States of America 2001;98;4;1595-600

  • The human non-muscle alpha-actinin protein encoded by the ACTN4 gene suppresses tumorigenicity of human neuroblastoma cells.

    Nikolopoulos SN, Spengler BA, Kisselbach K, Evans AE, Biedler JL and Ross RA

    Department of Biological Sciences, Fordham University, Bronx, New York, NY 10458 USA.

    alpha-Actinins are actin-binding proteins important in organization of the cytoskeleton and in cell adhesion. We have cloned and characterized a cDNA from human neuroblastoma cell variants which encodes the second non-muscle alpha-actinin isoform designated ACTN4 (actinin-4). mRNA encoded by the ACTN4 gene, mapped to chromosome 4, is abundant in non-tumorigenic, substrate-adherent human neuroblastoma cell variants but absent or only weakly expressed in malignant, poorly substrate-adherent neuroblasts. It is also present in many adherent tumor cell lines of diverse tissue origins. Cell lines typically co-express ACTN4 and ACTN1, a second non-muscle alpha-actinin gene. Expression is correlated with substrate adhesivity. Analysis of deduced amino acid sequences suggests that the two isoforms may differ in function and in regulation by calcium. Moreover, ACTN4 exhibits tumor suppressor activity. Stable clones containing increased levels of alpha-actinin, isolated from highly malignant neuroblastoma stem cells [BE(2)-C] after transfection with a full-length ACTN4 cDNA, show decreased anchorage-independent growth ability, loss of tumorigenicity in nude mice, and decreased expression of the N-myc proto-oncogene.

    Oncogene 2000;19;3;380-6

  • A common nonsense mutation results in alpha-actinin-3 deficiency in the general population.

    North KN, Yang N, Wattanasirichaigoon D, Mills M, Easteal S and Beggs AH

    Funded by: NIAMS NIH HHS: K02 AR02026, R01 AR44345

    Nature genetics 1999;21;4;353-4

  • Human skeletal muscle-specific alpha-actinin-2 and -3 isoforms form homodimers and heterodimers in vitro and in vivo.

    Chan Y, Tong HQ, Beggs AH and Kunkel LM

    Howard Hughes Medical Institute, Children's Hospital, Boston, Massachusetts, USA.

    Alpha-actinins belong to a family of actin-binding and crosslinking proteins and are expressed in many different cell types. Multiple isoforms of alpha-actinin are found in humans and are encoded by at least four distinct genes. Human skeletal muscle contains two sarcomeric isoforms, alpha-actinin-2 and -3. Previous studies have shown that the alpha-actinins function as anti-parallel homodimers but the question of heterodimer formation between two different isoforms expressed in the same cell type has not been explored. To address this issue, we expressed both alpha-actinin-2 and -3 in vitro and were able to detect their interaction by both blot overlay and co-immunoprecipitation methods. We were also able to demonstrate the presence of heterodimers in vivo in human skeletal muscle and in COS-1 cells transiently transfected with both isoforms. Our results clearly demonstrate the potential for alpha-actinin isoforms to form heterodimers which might have unique functional characteristics.

    Funded by: NIAMS NIH HHS: AR02026, AR44345; NINDS NIH HHS: NS23740

    Biochemical and biophysical research communications 1998;248;1;134-9

  • Activation of human neutrophils induces an interaction between the integrin beta 2-subunit (CD18) and the actin binding protein alpha-actinin.

    Pavalko FM and LaRoche SM

    Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46202.

    Mac-1 and LFA-1, members of the leukocyte or CD18 integrin subfamily of adhesion molecules, rapidly change from a low avidity to a high avidity state on activation of neutrophils by various agonists. The control of CD18 integrin-dependent neutrophil adhesion and the mechanisms that regulate integrin avidity are poorly understood. Cytoplasmic domain deletion experiments indicate that the cytoplasmic domains of integrins are necessary for proper integrin function and suggest that interactions with intracellular proteins are involved. We have focused on identifying cytoskeletal proteins that interact with the cytoplasmic domain of the beta-subunit (beta 2 or CD18) common to the leukocyte subfamily of integrins, which include LFA-1, Mac-1, and p150,95. The actin binding protein alpha-actinin associates in vitro with a peptide corresponding to a portion of the CD18 cytoplasmic domain in solid phase binding assays and affinity chromatography experiments. The peptide sequence within the CD18 cytoplasmic domain that binds alpha-actinin is homologous with a region in the cytoplasmic domain of the integrin beta 1-subunit, which also binds alpha-actinin. We demonstrate that the association of alpha-actinin with CD18 is physiologically relevant by coimmunoprecipitating CD18 with alpha-actinin from stimulated human neutrophils under nondenaturing conditions. Using a mAb against CD18 to probe Western blots of immunoprecipitated complexes, CD18 was found to coprecipitate with alpha-actinin when cells were activated with the chemotactic peptide FMLP or with the cytokines leukotriene B4 or TNF-alpha. Very little CD18 coprecipitates with alpha-actinin from unactivated cells. FMLP concentrations as low as 10 nM were sufficient to induce the association of CD18 with alpha-actinin; very little association was detected in cells activated with 1 nM FMLP. The association between alpha-actinin and CD18 was transient, peaking 5-10 min after activation and decreasing to near resting levels by 20 min. CD18 did not coimmunoprecipitate with talin or vinculin in vivo. We conclude that activation of neutrophils results in an alpha-actinin-mediated association between CD18 integrins and actin filaments. In addition to its actin bundling activity, alpha-actinin has a major function as an actin membrane linker molecule, and integrin avidity may be affected by an association with the actin cytoskeleton involving alpha-actinin.

    Journal of immunology (Baltimore, Md. : 1950) 1993;151;7;3795-807

  • Cloning and characterization of two human skeletal muscle alpha-actinin genes located on chromosomes 1 and 11.

    Beggs AH, Byers TJ, Knoll JH, Boyce FM, Bruns GA and Kunkel LM

    Division of Genetics, Children's Hospital, Boston, Massachusetts.

    Conserved sequences of dystrophin, beta-spectrin, and alpha-actinin were used to plan a set of degenerate oligonucleotide primers with which we amplified a portion of a human alpha-actinin gene transcript. Using this short clone as a probe, we isolated and characterized full-length cDNA clones for two human alpha-actinin genes (ACTN2 and ACTN3). These genes encode proteins that are structurally similar to known alpha-actinins with approximately 80% amino acid identity to each other and to the previously characterized human nonmuscle gene. ACTN2 is the human homolog of a previously characterized chicken gene while ACTN3 represents a novel gene product. Northern blot analysis demonstrated that ACTN2 is expressed in both skeletal and cardiac muscle, but ACTN3 expression is limited to skeletal muscle. As with other muscle-specific isoforms, the EF-hand domains in ACTN2 and ACTN3 are predicted to be incapable of binding calcium, suggesting that actin binding is not calcium sensitive. ACTN2 was mapped to human chromosome 1q42-q43 and ACTN3 to 11q13-q14 by somatic cell hybrid panels and fluorescent in situ hybridization. These results demonstrate that some of the isoform diversity of alpha-actinins is the result of transcription from different genetic loci.

    Funded by: NICHD NIH HHS: HD18658; NINDS NIH HHS: NS23740

    The Journal of biological chemistry 1992;267;13;9281-8

  • Alpha-actinin and vinculin in human neutrophils: reorganization during adhesion and relation to the actin network.

    Yürüker B and Niggli V

    Department of Pathology, University of Bern, Switzerland.

    We have studied the reorganization of vinculin and alpha-actinin during the process of adhesion in human neutrophils using immunofluorescence microscopy and interference reflection microscopy (IRM). Neutrophils in contact with uncoated glass formed black IRM areas in the cell periphery, indicative of very close contact with the substratum. Eight to twelve minutes after addition of cells to glass, vinculin was found to become concentrated in small patches at the cell periphery, partially colocalizing with the black IRM areas and with small F-actin-containing adherent protrusions. In contrast, vinculin was not significantly enriched in the less adherent F-actin-rich large pseudopods. alpha-Actinin became enriched during cell adhesion in retraction fibers and, in 40-50% of the inspected cells, also in large less adherent pseudopods where it colocalized with F-actin. The latter finding suggests a continuous dynamic reorganization of pseudopods, with incorporation of alpha-actinin at a certain stage. Disruption of the actin network with cytochalasin D revealed a differential interaction of alpha-actinin and vinculin with the actin network. alpha-Actinin was strongly influenced by cytochalasin D, comparable to F-actin, and both proteins formed colocalizing peripheral caps in 10(-5) M of the drug. Vinculin organization in contrast was not affected by up to 10(-6) M cytochalasin. At 10(-5) M of the drug, however, the patches disappeared completely, vinculin now assuming a diffuse cytoplasmic location. Our results suggest a specialized function of vinculin in adhesion sites of human neutrophils, whereas alpha-actinin may structure the actin network in retraction fibers and in less adherent pseudopods.

    Journal of cell science 1992;101 ( Pt 2);403-14

Gene lists (5)

Gene List Source Species Name Description Gene count
L00000015 G2C Homo sapiens Human NRC Human orthologues of mouse NRC adapted from Collins et al (2006) 186
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000061 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus (ortho) 984
L00000069 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list 1461
L00000071 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list (ortho) 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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