MGF

also known as: Mechano Growth Factor, IGF-1Ec, IGF-1 Ec variant

The native, non-pegylated splice variant of IGF-1 produced by skeletal muscle in response to mechanical overload — extremely short-lived in vivo and therefore superseded by PEG-MGF in research-chemical markets.

The endogenous mechano-growth-factor splice variant of IGF-1 (IGF-1Ec), produced transiently by loaded skeletal muscle and thought to activate satellite-cell proliferation as part of the hypertrophy response; systemic half-life of only a few minutes makes the unmodified peptide impractical for administration and is the reason the PEGylated analog was developed.

Mechanism of action

MGF is generated by alternative splicing of the IGF-1 primary transcript following mechanical overload in skeletal muscle, producing an IGF-1 isoform with a unique C-terminal Ec extension. The Ec peptide appears to act independently of the IGF-1 receptor in the initial satellite-cell proliferation phase, while the IGF-1 portion of the full splice variant drives subsequent differentiation. Local, autocrine/paracrine action dominates — systemic administration of the unmodified peptide is largely ineffective because of near-immediate degradation.

Primary uses

Research into muscle hypertrophy signaling and satellite-cell biology

Regulatory status

Not approved in any jurisdiction. Distinct from PEG-MGF (the pegylated research analog). Native MGF is the endogenous peptide produced by the body; exogenous unmodified MGF has not been developed as a therapeutic because of its extremely short systemic half-life.

References

[pubmed] Yang SY, Goldspink G. "Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation." FEBS Lett, 2002;522:156-160.
[pubmed] Hill M, Goldspink G. "Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite (stem) cell activation following local tissue damage." J Physiol, 2003;549:409-418.

Related peptides

PEG-MGF

A pegylated fragment of a proposed muscle-specific IGF-1 splice variant — the underlying "MGF" biology remains scientifically contested, and PEG-MGF itself has no human clinical data.

IGF-1 LR3

A 13-amino-acid N-terminal extension plus Arg3 substitution gives IGF-1 LR3 roughly 2–3× the potency of native IGF-1 in bioassays — a research-reagent favorite that became a bodybuilding staple despite no human approval.

IGF-1 DES(1-3)

Deleting the first three amino acids of IGF-1 cripples IGFBP binding while preserving receptor activity — giving DES(1-3) roughly 10× the in vitro potency of native IGF-1 at promoting cell growth in IGFBP-rich environments.

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.