Myogenic gene expression at rest and after a bout of resistance exercise in young (18–30 yr) and old (80–89 yr) women

Abstract

Raue, Ulrika, Dustin Slivka, Bozena Jemiolo, Chris Hollon, and Scott Trappe. Myogenic gene expression at rest and after a bout of resistance exercise in young (18 -30 yr) and old (80 -89 yr) women. J Appl Physiol 101: 53-59, 2006. First published April 6, 2006 doi:10.1152/japplphysiol.01616.2005.-The purpose of this study was to investigate mRNA expression of several key skeletal muscle myogenic controllers; myogenic differentiation factor (MyoD), muscle regulatory factor 4 (MRF4), myogenic factor 5 (Myf5), myogenin, myostatin, and myocyte enhancer factor 2 (MEF2) at rest and 4 h after a single bout of resistance exercise (RE) in young and old women. Eight young women (YW; 23 Ϯ 2 yr, 67 Ϯ 5 kg) and six old women (OW; 85 Ϯ 1 yr, 67 Ϯ 4 kg) performed 3 sets of 10 repetitions of bilateral knee extensions at 70% of one repetition maximum. Muscle biopsies were taken from the vastus lateralis before and 4 h after RE. Using real-time RT PCR, mRNA from the muscle samples was amplified and normalized to GAPDH. At rest, OW expressed higher (P Ͻ 0.05) levels of MyoD, MRF4, Myf5, myogenin, and myostatin compared with YW. In response to RE, there was a main time effect (P Ͻ 0.05) for the YW and OW combined in the upregulation of MyoD (2.0-fold) and MRF4 (1.4-fold) and in the downregulation of myostatin (2.2-fold). There was a trend (P ϭ 0.08) for time ϫ age interaction in MRF4. These data show that old women express higher myogenic mRNA levels at rest. The higher resting myogenic mRNA levels in old women may reflect an attempt to preserve muscle mass and function. When challenged with RE, old women appear to respond in a similar manner as young women. mRNA; skeletal muscle; muscle regulatory factors; real-time reverse transcriptase-polymerase chain reaction AGING RODENT (1, 31) AND HUMAN (16, 23) skeletal muscle has been shown to express high mRNA levels of muscle regulatory factors.

Expression of growth-related genes in young and older human skeletal muscle following an acute stimulation of protein synthesis

“…4) are consistent with the work of others that have shown elevations in myogenic regulatory factor mRNA in the old at rest and that resistance exercise alters the expression of human skeletal muscle mRNAs associated with satellite cell regulation in both young and older subjects (8,28,33,34,45). We also report for the first time in human skeletal muscle, an age-related differential expression pattern post REϩEAA of a novel gene known as mindbomb 2 (mib2; Fig.…”

“…The sequence of satellite cell events involves activation, proliferation, and fusion to existing myofibers (19). Regulation of satellite cell function is controlled by many different factors, including growth factors (i.e., IGF-1, myostatin) and members of the myogenic regulatory family (i.e., myoD, myogenin), all of which are acutely responsive to a single bout of resistance exercise in humans (7,8,34,39,45,57). However, no information is available in humans on the E3 ubiquitin ligase, mindbomb2 (mib2; also known as skeletrophin).…”

Human Sarcopenia Reveals an Increase in SOCS-3 and Myostatin and a Reduced Efficiency of Akt Phosphorylation

“…One such factor may be myostatin, which has recently been reported to reduce Akt phosphorylation in both cardiomyocytes 31 and in mouse C2C12 cells. 32 Myostatin mRNA, but not protein, levels have been measured and compared previously in older versus younger skeletal muscle, with investigations showing either increases in older subjects 29 or no difference 12 when compared to younger subjects. However, it was deemed relevant to measure the myostatin mRNA and protein levels in the present study and to determine if an association existed with Akt phosphorylation levels.…”

“…Myostatin, a member of the transforming growth factor-␤ family, inhibits muscle development. 27,28 Myostatin mRNA in elderly skeletal muscle has been shown to be either increased 29 or unchanged, 12 when compared to younger skeletal muscle, while myostatin protein levels in elderly muscle have not been reported. Myostatin levels are inhibited by GH in human muscle, 30 suggesting that a perturbation in GH levels, or GH activity, may result in increased myostatin levels.…”

Efeitos do treinamento de força de baixa intensidade associado à restrição parcial do fluxo sanguíneo na força, hipertrofia e modulação das células satélites musculares em idosos

“…As células satélites são células mononucleares, quiescentes e caracterizadas por estarem localizadas entre o sarcolema e a lamina basal apresentando a capacidade de proliferação e diferenciação estando intimamente ligadas ao processo de hipertrofia muscular (MUIR, KANJI e ALLBROOK, 1965;HAWKE e GARRY, 2001;PETRELLA et al, 2008;BELLAMY et al, 2014;BLAAUW e REGGIANI, 2014). Tanto a idade como o nível de treinamento parecem ser capazes de modular as respostas dos genes e das proteínas envolvidas no processo de ativação das células satélites, bem como a quantidade das mesmas que são fundidas às células musculares esqueléticas PETRELLA et al, 2006;RAUE et al, 2006;VERDIJK et al, 2009). De maneira oposta, o fator miogênico 6 (myf 6) apresentou aumentos na sua quantidade total, porém sem aumento de expressão gênica.…”