Study summary · research use only
Gene expression in skeletal muscle
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This review discussed gene expression changes underlying skeletal muscle adaptation to activity; species not specified. The authors described muscle's capacity to alter mass and phenotype via changes in gene expression, including myosin heavy chain isogenes and metabolic genes affecting fatigue resistance and power output. They reported cloning cDNAs for local and systemic isoforms of insulin-like growth factor-I (IGF-I) from exercised muscle, noting that one isoform, detectable only after injury or mechanical activity, was termed mechano growth factor (MGF). Due to a reading-frame shift, MGF has a different 3' sequence and mode of action compared with systemic or liver IGF-I, and the authors suggested MGF may function more as a local repair factor than as a classic growth factor.
Abstract
Muscle has an intrinsic ability to change its mass and phenotype in response to activity. This process involves quantitative and qualitative changes in gene expression, including that of the myosin heavy chain isogenes that encode different types of molecular motors. This, and the differential expression of metabolic genes, results in altered fatigue resistance and power output. The regulation of muscle mass involves autocrine as well as systemic factors. We have cloned the cDNAs of local and systemic isoforms of insulin-like growth factor-I (IGF-I) from exercised muscle. Although different isoforms are derived from the IGF-I gene by alternative splicing, the RNA transcript of one of them is only detectable following injury and/or mechanical activity. Thus this protein has been called mechano growth factor (MGF). Because of a reading-frame shift, MGF has a different 3' sequence and a different mode of action compared with systemic or liver IGF-I. Although MGF has been called a growth factor, it may be regulated as a local repair factor.
pepmg summarizes the peer-reviewed literature and links to every source — it sells nothing, ships nothing, and gives no medical, dosing, or human-use guidance. Don't just trust this summary: follow the citation to its source and read it yourself. Research use only.