Profiling Of Gene Expression Related To Individual Differences On Resistance Training In The Elderly Men

Abstract

Individual differences of trainability by resistance training are influenced by many gene expression phenotypes. Gene expression phenotypes are affected by polymorphism in the promoter region or intron of gene. PURPOSE To detect gene polymorphisms related to the individual differences in the elderly men, the present study implemented the profiling of gene expression related to individual differences on resistance training by using DNA microarrays. METHODS Eleven healthy untrained volunteers (age range 60–69 years) participated in a 14-week unilateral isokinetic training program (10 repetitions/set; 3 sets/day; 2days/week) at maximum effort. Knee extensor muscle cross-sectional area (CSA) of mid-thigh from magnetic resonance image (MRI) was estimated before and after 14 weeks of strength training. Muscle biopsy samples were also obtained from vastus lateralis before and after training. RNA was extracted from before and after strength training and cross-hybridized to DNA microarrays (Human Oligo Chip 30K; HITACHI, Japan) representing 10368 known human genes before and after RNA samples. Intra-individual variation of skeletal muscle gene expression was examined in the top 2 (High trainability (HT) group n=2) and the lowest 2 ranked subjects (Low trainability (LT) group n=2) by assessment of CSA. Range of detection of fluorescence intensity was higher than the background non-specific spots. The criterion of expression level was either greater than or equal to 1.5 or less than or equal to −1.5. RESULT By strength training of a 14-week, CSA of mid-thigh increased 6.9% (p < 0.05) and range of CSA was 2.5% to 14.5%. Three genes were identified as common change (>1.5-fold) in HT group and no change LT group after strength training. These genes were downregulated in HT group after training. However there was not able to detect upregulation gene. Five genes were identified as common change (>1.5-fold) LT group and no change HT group. There was only one gene that upregulated, and four genes were downregulated. Thus, the majority of these were downregulated. CONCLUSION In the present study eight genes were detected as related to individual differences on resistance training. These results may help to refine the candidate genes. Supported by the Special Coordination Funds of the Ministry of Education, Culture, Sports, Science and Technology, the Japanese Government.