DNA methylation across the genome in aged human skeletal muscle tissue and muscle-derived cells: the role of HOX genes and physical activity.

Skeletal muscle tissue demonstrates global hypermethylation with age. However, methylome changes across the time-course of differentiation in aged human muscle derived cells, and larger coverage arrays in aged muscle tissue have not been undertaken. Using 850K DNA methylation arrays we compared the methylomes of young (27 ± 4.4 years) and aged (83 ± 4 years) human skeletal muscle and that of young/aged heterogenous muscle-derived human primary cells (HDMCs) over several time points of differentiation (0, 72 h, 7, 10 days). Aged muscle tissue was hypermethylated compared with young tissue, enriched for; pathways-in-cancer (including; focal adhesion, MAPK signaling, PI3K-Akt-mTOR signaling, p53 signaling, Jak-STAT signaling, TGF-beta and notch signaling), rap1-signaling, axon-guidance and hippo-signalling. Aged cells also demonstrated a hypermethylated profile in pathways; axon-guidance, adherens-junction and calcium-signaling, particularly at later timepoints of myotube formation, corresponding with reduced morphological differentiation and reductions in MyoD/Myogenin gene expression compared with young cells. While young cells showed little alterations in DNA methylation during differentiation, aged cells demonstrated extensive and significantly altered DNA methylation, particularly at 7 days of differentiation and most notably in focal adhesion and PI3K-AKT signalling pathways. While the methylomes were vastly different between muscle tissue and HDMCs, we identified a small number of CpG sites showing a hypermethylated state with age, in both muscle tissue and cells on genes KIF15, DYRK2, FHL2, MRPS33, ABCA17P. Most notably, differential methylation analysis of chromosomal regions identified three locations containing enrichment of 6-8 CpGs in the HOX family of genes altered with age. With HOXD10, HOXD9, HOXD8, HOXA3, HOXC9, HOXB1, HOXB3, HOXC-AS2 and HOXC10 all hypermethylated in aged tissue. In aged cells the same HOX genes (and additionally HOXC-AS3) displayed the most variable methylation at 7 days of differentiation versus young cells, with HOXD8, HOXC9, HOXB1 and HOXC-AS3 hypermethylated and HOXC10 and HOXC-AS2 hypomethylated. We also determined that there was an inverse relationship between DNA methylation and gene expression for HOXB1, HOXA3 and HOXC-AS3. Finally, increased physical activity in young adults was associated with oppositely regulating HOXB1 and HOXA3 methylation compared with age. Overall, we demonstrate that a considerable number of HOX genes are differentially epigenetically regulated in aged human skeletal muscle and HDMCs and increased physical activity may help prevent age-related epigenetic changes in these HOX genes.

Genetic variants influencing effectiveness of exercise training programmes in obesity - an overview of human studies.

Frequent and regular physical activity has significant benefits for health, including improvement of body composition and help in weight control. Consequently, promoting training programmes, particularly in those who are genetically predisposed, is a significant step towards controlling the presently increasing epidemic of obesity. Although the physiological responses of the human body to exercise are quite well described, the genetic background of these reactions still remains mostly unknown. This review not only summarizes the current evidence, through a literature review and the results of our studies on the influence of gene variants on the characteristics and range of the body's adaptive response to training, but also explores research organization problems, future trends, and possibilities. We describe the most reliable candidate genetic markers that are involved in energy balance pathways and body composition changes in response to training programmes, such as FTO, MC4R, ACE, PPARG, LEP, LEPR, ADRB2, and ADRB3. This knowledge can have an enormous impact not only on individualization of exercise programmes to make them more efficient and safer, but also on improved recovery, traumatology, medical care, diet, supplementation and many other areas. Nevertheless, the current studies still represent only the first steps towards a better understanding of the genetic factors that influence obesity-related traits, as well as gene variant x physical activity interactions, so further research is necessary.

CKM gene polymorphism in Russian and Polish rowers.

Muscle-specific creatine kinase (CKMM) plays a vital role in the energy homeostasis of muscle cells. The A/G variation (rs8111989) located in the 3'-untranslated region of the CKM gene has been found to be the most relevant in terms of genetic testing in sport. The aim of the presented study was to test the hypothesis that the G allele might represent a genetic element that contributes to the improvement of endurance performance in Polish and Russian rowers. The distribution of the CKM genotypes was examined in a group of Polish and Russian athletes in comparison with non-athlete controls. There were no statistical differences between the rowers and the control groups across the CKM genotypes when Polish or Russian participants were analyzed. Based on the obtained results, it may be speculated that the CKM A/G polymorphism is not an important determinant of endurance performance level in Polish and Russian rowers. However, these results should be interpreted with caution as they can be limited by many factors.

Actn3 genotype is associated with testosterone levels of athletes.

UNLABELLED: α-Actinin-3 (ACTN3) has been proposed to regulate skeletal muscle differentiation and hypertrophy through its interaction with the signalling protein calcineurin. Since the inhibition of calcineurin potentiates the production of testosterone, we hypothesized that α-actinin-3 deficiency (predicted from the ACTN3 XX genotype) may influence serum levels of testosterone of athletes. OBJECTIVE: To investigate the association of ACTN3 gene R577X polymorphism with resting testosterone levels in athletes. METHODS: A total of 209 elite Russian athletes from different sports (119 males, 90 females) were genotyped for ACTN3 gene R577X polymorphism by real-time PCR. Resting testosterone was examined in serum of athletes using enzyme immunoassay. RESULTS: The mean testosterone levels were significantly higher in both males and females with the ACTN3 R allele than in XX homozygotes (males: RR: 24.9 (5.7), RX: 21.8 (5.5), XX: 18.6 (4.9) ng · mL(-1), P = 0.0071; females: RR: 1.43 (0.6), RX: 1.21 (0.71), XX: 0.79 (0.66) ng · mL(-1), P = 0.0167). CONCLUSIONS: We found that the ACTN3 R allele was associated with high levels of testosterone in athletes, and this may explain, in part, the association between the ACTN3 RR genotype, skeletal muscle hypertrophy and power athlete status.

SOD2 gene polymorphism and muscle damage markers in elite athletes.

Exercise-induced oxidative stress is a state that primarily occurs in athletes involved in high-intensity sports when pro-oxidants overwhelm the antioxidant defense system to oxidize proteins, lipids, and nucleic acids. During exercise, oxidative stress is linked to muscle metabolism and muscle damage, because exercise increases free radical production. The T allele of the Ala16Val (rs4880 C/T) polymorphism in the mitochondrial superoxide dismutase 2 (SOD2) gene has been reported to reduce SOD2 efficiency against oxidative stress. In the present study we tested the hypothesis that the SOD2 TT genotype would be underrepresented in elite athletes involved in high-intensity sports and associated with increased values of muscle and liver damage biomarkers. The study involved 2664 Caucasian (2262 Russian and 402 Polish) athletes. SOD2 genotype and allele frequencies were compared to 917 controls. Muscle and liver damage markers [creatine kinase (CK), creatinine, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP)] were examined in serum from 1444 Russian athletes. The frequency of the SOD2 TT genotype (18.6%) was significantly lower in power/strength athletes (n = 524) compared to controls (25.0%, p = 0.0076) or athletes involved in low-intensity sports (n = 180; 33.9%, p < 0.0001). Furthermore, the SOD2 T allele was significantly associated with increased activity of CK (females: p = 0.0144) and creatinine level (females: p = 0.0276; males: p = 0.0135) in athletes. Our data show that the SOD2 TT genotype might be unfavorable for high-intensity athletic events.

The association of gene polymorphisms with athlete status in ukrainians.

UNLABELLED: Athletic performance is a polygenic trait influenced by both environmental and genetic factors. OBJECTIVE: To investigate individually and in combination the association of common gene polymorphisms with athlete status in Ukrainians. METHODS: A total of 210 elite Ukrainian athletes (100 endurance-oriented and 110 power-orientated athletes) and 326 controls were genotyped for ACE I/D, HIF1A Pro582Ser, NOS3 -786 T/C, PPARA intron 7 G/C, PPARG Pro12Ala and PPARGC1B Ala203Pro gene polymorphisms, most of which were previously reported to be associated with athlete status or related intermediate phenotypes in different populations. RESULTS: Power-oriented athletes exhibited an increased frequency of the HIF1A Ser (16.1 vs. 9.4%, P = 0.034) and NOS3 T alleles (78.3 vs. 66.2%, P = 0.0019) in comparison with controls. Additionally, we found that the frequency of the PPARG Ala allele was significantly higher in power-oriented athletes compared with the endurance-oriented athletes (24.7 vs. 13.5%; P = 0.0076). Next, we determined the total genotype score (TGS, from the accumulated combination of the three polymorphisms, with a maximum value of 100 for the theoretically optimal polygenic score) in athletes and controls. The mean TGS was significantly higher in power-oriented athletes (39.1 ± 2.3 vs. 32.6 ± 1.5; P = 0.0142) than in controls. CONCLUSIONS: We found that the HIF1A Ser, NOS3 T and PPARG Ala alleles were associated with power athlete status in Ukrainians.

A 24-hour ambulatory ecg monitoring in assessment of qt interval duration and dispersion in rowers with physiological myocardial hypertrophy.

UNLABELLED: Myocardial hypertrophy (MH) due to cardiac pathology is characterized by an increase in QT interval duration and dispersion, while the findings for exercise-induced myocardial hypertrophy are contradictory. The majority of published research findings have not explored this relationship, but there have only been a few conducted studies using 24-hour ECG monitoring. The aim of the study was to determine the QT interval duration and dispersion in short-term and 24-hour ECG in endurance athletes with myocardial hypertrophy and without it. METHODS: A total of 26 well-trained rowers underwent a resting 12-lead ECG, 24-hour ECG monitoring and echocardiography. RESULTS: Athletes with MH (n = 7) at rest did not show any increase in QTc interval duration and dispersion, or mean and maximal QTc duration in Holter monitoring compared to athletes without MH (n = 19). Left ventricular mass was not significantly correlated with any QTc characteristics. Furthermore, athletes with MH had significantly longer mean QT (P = 0.01) and maximal QT (P = 0.018) intervals in Holter monitoring and higher 24-hour heart rate variability indexes due to stronger vagal effects. CONCLUSIONS: The present study demonstrated that athlete's heart syndrome with myocardial hypertrophy as a benign phenomenon does not lead to an increase in QT interval duration, or increases in maximal and mean duration in a 24-hour ECG. An increase in QT interval duration in athletes may have an autonomic nature.

The ACTN3 R577X polymorphism in Russian endurance athletes.

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.

PPARG Gene polymorphism and locomotor activity in humans.

The distribution of PPARG gene allele frequencies (Pro/Ala polymorphism) was studied in sportsmen specialized in speed and force athletics. A relationship between genotypes and human muscle transverse section area was evaluated. The PPARG Ala allele was significantly more incident in athletes than in controls, the incidence increasing with higher athletic qualification. A hypertrophic effect of PPARG Ala allele on muscle fibers was detected. Hence, the PPARG Pro12Ala polymorphism is associated with human motor activity.

Effect of HIF1A gene polymorphism on human muscle performance.

Allele distribution of hypoxia-inducible factor gene (HIF1A; Pro582Ser polymorphism) was studied in power-oriented athletes and controls practicing no athletics; genotype relationships with muscle fiber composition were studied in speed skaters. Genotyping was carried out by PCR. The composition of muscle fibers was evaluated by the immunohistochemical analysis of m. vastus lateralis. The incidence of HIF1A Ser allele was significantly higher in weight-lifters than in controls (17.9 vs. 8.5%; p=0.001) and increased with athletic skill improvement. A relationship between HIF1A Ser allele and predominance of fast-twitch muscle fibers was shown (Pro/Ser 46.2 (13.8)%, Pro/Pro 31.4 (8.2)%; p=0.007). Hence, HIF1A Pro582Ser polymorphism is associated with muscle activity in humans.