Growth hormone promotes skeletal muscle cell fusion independent of insulin-like growth factor 1 up-regulation.

ABSTRACT: Growth hormone (GH) participates in the postnatal regulation of skeletal muscle growth, although the mechanism of action is unclear. Here we show that the mass of skeletal muscles lacking GH receptors is reduced because of a decrease in myofiber size with normal myofiber number. GH signaling controls the size of the differentiated myotubes in a cell-autonomous manner while having no effect on size, proliferation, and differentiation of the myoblast precursor cells. The GH hypertrophic action leads to an increased myonuclear number, indicating that GH facilitates fusion of myoblasts with nascent myotubes. NFATc2, a transcription factor regulating this phase of fusion, is required for GH action because GH is unable to induce hypertrophy of NFATc2-/- myotubes. Finally, we provide three lines

SUBMITTER: Sotiropoulos A 

PROVIDER: S-EPMC1456062 | biostudies-literature | 2006 May

REPOSITORIES: biostudies-literature