IGF1 is thought to induce muscle hypertrophy, by distinct mechanisms.
The IGF1 receptor is a
tyrosine-kinase receptor which induces cellular signal transduction chains by adding phosphate groups
or “phosphorylating” specific proteins within the cell....
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IGF1 is thought to induce muscle hypertrophy, by distinct mechanisms.
The IGF1 receptor is a
tyrosine-kinase receptor which induces cellular signal transduction chains by adding phosphate groups
or “phosphorylating” specific proteins within the cell.
Activation of the PI3K/AKT kinases cause
phosphorylation of the FOXO transcription factors, which prevents them from entering the nucleus and
promoting the expression of atrophic factors, like MuRF1.
The AKT pathway (often called “PKB”
instead of “AKT”) also inhibits the secretion of myostatin, thereby increasing both muscle cell
differentiation, and protein synthesis.
(ref) Myostatin inhibition results in a positive feedback cycle,
since myostatin also inhibits the AKT pathway.
(ref, ref) IGF1 also activates the mTOR pathway, which
is well-known to play a central role in muscle growth.
Apparently, PI3K activates mTOR by moving
tuberous sclerosis complexes (mTOR inhibitors) from the membrane to the cytosol.
(ref) (Independent
of growth
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