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Fiber type specific myogenic and proteolytic gene expression after acute resistance exercise in young women
Author(s) -
Raue Ulrika,
Jemiolo Bozena,
Conley Travis,
Louis Emily,
Trappe Scott
Publication year - 2007
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.21.6.a1303-b
Subject(s) - myogenin , myod , myosin , myostatin , medicine , myogenic regulatory factors , major histocompatibility complex , endocrinology , chemistry , microbiology and biotechnology , biology , skeletal muscle , gene , myogenesis , biochemistry
The purpose of this investigation was to analyze fiber type specific gene expression (GE) of select myogenic [myogenic differentiation factor (MyoD), muscle regulatory factor 4 (MRF4), and myogenin] and proteolytic markers [atrogin‐1, muscle RING finger‐1 (MuRF‐1), Forkhead box 3A (FOXO3A), cysteine‐dependent aspartate protease (caspase‐3)] and myostatin before and after resistance exercise (RE). Eight young women (23 ± 2 y, 67 ± 5 kg) performed 3 × 10 knee extensions at 70% of 1‐repetition maximum. Muscle biopsies were taken from vastus lateralis pre and 4‐h post RE. Using real‐time RT PCR, mRNA from pooled myosin heavy chain (MHC)‐I and IIa fibers was amplified and normalized to GAPDH. Myogenic GE was higher (p<0.05) in MHC‐I compared to MHC‐IIa at rest (25–58%) and 4‐h post RE (66–70%). With RE, both fiber types increased (p<0.05) myogenic GE; MyoD (I: 58% IIa: 50%) myogenin (58%, 33%), and MRF4 (96%, 47%). Both fiber types also had a decrease (p<0.05) (38%, 52%) in myostatin mRNA with RE. Atrogin‐1 GE was higher (p<0.05) in MHC‐I vs MHC‐IIa fibers at rest (80%) and 4‐h post (67%). With RE, MuRF‐1 increased (p<0.05) in MHC‐I (87%) and MHC‐IIa (200%), while RE had no effect on atrogin‐1, FOXO3A, and caspase‐3. In summary, at baseline MHC‐I fibers express higher levels of myogenic and atrogin‐1 mRNA compared to MHC‐IIa. Both fiber types appear to respond to RE, with a myogenic, myostatin, and MuRF‐1 mRNA regulation. These single RE data support the concept that young women may adapt in both MHC‐I and MHC‐IIa fibers during a chronic resistance‐training program. Supported by NIH grant AG18409.