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MicroRNA in Muscle: Characterising the Powerlifter Phenotype
Author(s) -
D'Souza R. F.,
Bjornsen T.,
Aasen K. M.,
Raastad T.,
Mitchell C. J.,
CameronSmith D.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1083.7
Subject(s) - isometric exercise , muscle hypertrophy , anabolism , microrna , vastus lateralis muscle , skeletal muscle , endocrinology , medicine , gene expression , phenotype , sarcopenia , downregulation and upregulation , chemistry , gene , biochemistry
Skeletal muscle has a remarkable capacity to adapt in response to imposed external loads. Powerlifters are the epitome of this adaptation and are able to generate extremely high muscular forces. The molecular mechanisms underpinning the significant capacity for force generation and hypertrophy are unclear. MicroRNAs (miRs) are short non‐coding RNA sequences that control gene expression via promotion of transcript breakdown and/or translational inhibition. Differences in miR expression at rest may account for phenotypic differences in muscle mass and function between powerlifters and untrained age‐matched controls. The primary object of this study was to characterize the expression profiles of a subset of miRs known to exert an influence on key aspects of myogenic regulation in the muscles of highly trained powerlifters. Muscle biopsies were obtained from the vastus lateralis of 17 national level powerlifters (25.1 ± 5.8 years) and 17 untrained controls (24.1 ± 2.0 years). The powerlifters were stronger than the controls (isometric knee extensions: 297.9 ± 56.1 Nm, 193.6 ± 46.6 Nm, respectively p <0.001), and also had bigger muscle fibres (type I CSA 8869 ± 1366 μm 2 compared to 4196 ± 963 2 μm 2 p<0.001 and type II CSA 10636 ± 2029 μm 2 compared to 5327 ± 1342 μm 2 p<0.001). Of the 15 miRs species analysed, 12 were differently expressed between groups. 7 were upregulated in powerlifters; miR ‐15a (p<0.001), ‐16 (p=0.008), ‐23a (p<0.001), ‐23b (p<0.001), ‐451a (p=0.012), ‐30b (p=0.010) and ‐206 (p=0.032). Conversely, 5 were reduced in the powerlifters; miR‐486 (p=0.002), ‐499 (p=0.018), ‐126 (p<0.001), ‐133a (p=0.001) and ‐1 (p=0.013). Whilst, miRs‐208a, ‐208b and ‐145 did not differ between groups. Powerlifters have larger muscle fibres capable of producing greater contractile force. The unique miR expression profiles of powerlifters compared to the healthy untrained controls indicates miRs may be a component of the post‐transcriptional regulation necessary for the maintenance of increased muscle mass and strength. The miRs of interest have putative roles in muscle atrophy, hypertrophy and angiogenesis indicating a possible involvement in regulation of muscle mass and contractile capacity.