MGF 2mg – Research Grade Mechano Growth Factor

MGF (mechano growth factor) is the common name for the C-terminal E-peptide of the IGF-1Ec splice variant of the IGF1 gene (the rodent ortholog is termed IGF-1Eb; in humans the equivalent transcript is IGF-1Ec). The MGF research program originated in the laboratory of Geoffrey Goldspink at University College London in the mid-1990s. Goldspink's group identified an alternatively spliced IGF1 transcript whose expression in skeletal muscle was sharply upregulated by mechanical loading and damage and whose translated product included a unique 24-residue C-terminal E-domain peptide distinct from the standard IGF-1Ea / Ec architecture.

The MGF transcript encodes the same mature IGF-1 sequence as the IGF-1Ea transcript — both transcripts produce the same 70-residue mature IGF-1 after E-peptide cleavage. The biological distinction between "MGF" and "IGF-1" therefore lies not in the mature IGF-1 portion of the molecule but in the unique 24-residue C-terminal E-peptide (Ec or Eb, depending on species), which is released by proteolytic processing and which has been shown to have its own biological activity, independent of the IGF-1 receptor, on muscle satellite-cell proliferation and migration.

Synthetic "MGF" sold as a research peptide is typically the 24-residue E-peptide alone (sometimes called the "MGF peptide" or "C-terminal E-peptide"), not the full splice-variant pro-protein. This research peptide is used in published in-vitro studies of satellite-cell biology and muscle regeneration and has been studied in animal-model investigations of muscle damage and repair.

This page is a research-only educational reference. MGF supplied as a research peptide is intended for laboratory and analytical work; no therapeutic or human-use claims are made.

The human IGF1 gene generates three principal pre-pro-IGF-1 transcripts by alternative splicing of the 3' end: IGF-1Ea (the dominant hepatic and systemic form), IGF-1Eb (a minor variant), and IGF-1Ec (the human ortholog of rodent IGF-1Eb, expressed in skeletal muscle in response to mechanical loading). All three transcripts contain the same mature IGF-1 coding sequence; they differ in the C-terminal E-domain that is removed by proteolytic processing during pre-pro-IGF-1 maturation.

The Ec/Eb E-peptide is 24 amino acids long and contains a unique 24-residue sequence that is not present in the dominant Ea E-peptide. The MGF research program established that this 24-residue E-peptide has biological activity on its own — it is not merely a discarded propeptide. The published in-vitro literature reports that the synthetic MGF E-peptide stimulates proliferation and migration of cultured muscle satellite cells (myogenic precursor cells associated with the basement membrane of muscle fibers) by a mechanism that does not require the IGF-1 receptor and that operates by a still incompletely characterized receptor target.

Synthetic MGF as supplied for research use is most commonly the 24-residue C-terminal E-peptide alone. The peptide is rapidly hydrolyzed in serum (with a half-life of minutes), which is one reason the pegylated derivative PEG-MGF was developed for in-vivo research models that require a longer circulating half-life. Native MGF activity in vivo is therefore inferred to be largely local and short-acting, consistent with the model in which mechanical loading or muscle damage transiently upregulates IGF-1Ec transcription, locally generates pro-IGF-1Ec, and locally releases both mature IGF-1 (engaging IGF-1R on satellite cells and fibers) and the E-peptide (acting on satellite cells through its IGF-1R-independent target).

It is important to be clear about what MGF is not. It is not mature IGF-1 — the mature IGF-1 sequence is shared across all IGF1 splice variants, and the distinctive biology of MGF lies in the E-peptide. It is not an approved medicine in any jurisdiction. And it is not a "muscle-building drug" in the lay sense; its published research role is as a satellite-cell-active research peptide for in-vitro and animal-model muscle-regeneration biology.

Geoffrey Goldspink's laboratory at University College London began investigating mechanical-load-induced gene expression in skeletal muscle in the 1980s and 1990s. The group's interest was in identifying genes whose expression was acutely upregulated by stretch, overload, or contraction-induced damage and whose products might mediate the adaptive hypertrophy and regenerative response of muscle to such loading.

In the mid-1990s, Goldspink and colleagues identified a 3'-alternatively-spliced IGF1 transcript that was sharply upregulated by mechanical loading in skeletal muscle but minimally expressed in resting muscle. They named the variant "mechano growth factor" (MGF) to distinguish it from the dominant systemic IGF-1Ea form and to highlight its mechanical-load responsiveness. Subsequent work characterized the splice-variant 3' UTR structure, mapped the unique E-peptide sequence, and developed antibodies and synthetic peptides for in-vitro and in-vivo study.

The 1999-2005 period saw the publication of a series of papers from the Goldspink group and collaborators describing the in-vitro effects of the synthetic 24-residue E-peptide on cultured muscle satellite cells (the myogenic precursors that mediate adult muscle regeneration), the upregulation of IGF-1Ec/Eb in response to resistance exercise in human and rodent muscle, and the relevance to age-related muscle wasting (sarcopenia) where the IGF-1Ec response to loading is attenuated. The work was published primarily in muscle-biology and sports-science journals and provided the foundational research basis for the MGF research peptide community.

Subsequent work from other laboratories has both extended and complicated the picture. Independent groups have confirmed E-peptide biological activity in some assay systems but have noted that the receptor target for the E-peptide remains incompletely defined, that some reported effects depend on assay conditions, and that the in-vivo biological role of the E-peptide as distinct from local mature IGF-1 release is challenging to dissect cleanly because both come from the same pro-protein. The PEG-MGF pegylated derivative was developed in this context to allow in-vivo research models with extended circulating half-life.

MGF has not been developed as a clinical therapy in any major jurisdiction. The IGF-1 family member that has been developed for clinical use is native recombinant IGF-1 (mecasermin, FDA-approved 2005 for severe primary IGF-1 deficiency); MGF is studied as a research peptide and as a satellite-cell-active tool reagent in muscle-biology research.

Skeletal muscle regeneration depends on a resident population of satellite cells — quiescent myogenic precursor cells anchored beneath the basement membrane of muscle fibers, identified by Mauro in the 1960s. In response to damage, mechanical loading, or local growth-factor signals, satellite cells are activated to proliferate, migrate to the site of damage, fuse with damaged fibers (repairing them) or with one another (forming new fibers), and re-establish the quiescent satellite-cell pool. This satellite-cell cycle is the foundational mechanism of adult muscle regeneration and adaptive hypertrophy.

IGF-1 plays multiple roles in this process. Mature IGF-1 acts via IGF-1R on satellite cells to drive proliferation (Ras-ERK pathway) and on differentiated muscle fibers to drive protein synthesis and hypertrophy (PI3K-AKT-mTOR pathway). The IGF-1 system is therefore central to muscle adaptive biology, and the alternative-splicing biology of the IGF1 gene generates locally expressed, load-responsive variants that complement the systemic hepatic IGF-1Ea pool.

The MGF E-peptide (the 24-residue C-terminal portion of pro-IGF-1Ec) is reported in the published in-vitro literature to have a distinct biological activity on satellite cells, separate from the IGF-1R-mediated effects of the mature IGF-1 portion of the same pro-protein. In cell-culture studies, the synthetic MGF E-peptide has been reported to stimulate satellite-cell proliferation and migration without activating IGF-1R (as measured by IGF-1R-knockout cells or by IGF-1R-blocking antibody). The receptor target for the E-peptide is not definitively established; candidate receptors and mechanisms have been proposed in the literature but no single high-affinity receptor has been confirmed.

The temporal pattern of IGF-1Ec/Eb expression after mechanical loading is informative: published rodent and human studies report a sharp transient upregulation of IGF-1Ec transcription in the hours following exercise or damage, followed by a subsequent upregulation of IGF-1Ea on a longer time scale. The interpretation in the Goldspink model is that the IGF-1Ec transcript and its E-peptide play an early, satellite-cell-activating role, while the IGF-1Ea transcript and its systemic-mature IGF-1 contribute to the slower hypertrophic phase. Both transcripts produce the same mature IGF-1, so the unique contribution of IGF-1Ec is attributed to the E-peptide.

In the aging-muscle literature, the IGF-1Ec response to mechanical loading is attenuated in older muscle compared to younger muscle, providing a mechanistic candidate for the impaired adaptive response of aged muscle to exercise (the "anabolic resistance" of sarcopenia). This is one of the contexts in which MGF biology has been studied as research-domain insight into muscle aging.

The half-life and pharmacokinetics of the synthetic MGF E-peptide in serum are unfavorable for in-vivo applications — the peptide is rapidly hydrolyzed, with a serum half-life of minutes. The pegylated derivative PEG-MGF was developed to extend circulating exposure in animal-model studies that require systemic exposure.

Synthetic MGF supplied for research use is most commonly the 24-residue C-terminal E-peptide of the human IGF-1Ec (or rodent IGF-1Eb) splice variant. The peptide sequence in the human IGF-1Ec context is generally given as YQPPSTNKNTKSQRRKGSTFEERK (or close variants depending on species and the specific published reference). The peptide has a calculated molecular weight near 2.9 kDa and is a relatively basic peptide due to the multiple lysine and arginine residues.

The peptide is produced by standard solid-phase peptide synthesis (SPPS), typically using Fmoc chemistry on appropriate resin. The crude product is purified by reversed-phase HPLC to ≥98% purity for research use and verified by analytical HPLC and mass spectrometry. The peptide is supplied as a lyophilized powder, typically as the acetate or trifluoroacetate salt, and is reconstituted in sterile aqueous buffer for laboratory work.

The unstructured small-peptide character and the abundance of basic residues contribute to the rapid serum hydrolysis observed in research models. The pegylated derivative (PEG-MGF) addresses this limitation for studies requiring longer circulating exposure.

In published muscle-biology research, MGF and the synthetic MGF E-peptide have been used in several principal applications:

Satellite-cell biology. Cultured primary and immortalized satellite-cell lines are treated with synthetic MGF E-peptide to interrogate proliferation, migration, and activation responses. These in-vitro studies are the principal evidence base for MGF E-peptide biological activity.

Mechanical-loading and exercise studies. IGF-1Ec/Eb expression in rodent and human muscle is measured by qPCR or in-situ hybridization following resistance exercise, electrical stimulation, stretch, or contraction-induced damage. The transcript-level response provides a research readout of the locally generated MGF response to loading.

Aging and sarcopenia research. The attenuated IGF-1Ec response to loading in aged muscle compared to younger muscle is investigated as a mechanism contributing to the anabolic resistance of sarcopenia. Synthetic MGF E-peptide has been used in some aging-muscle studies as a research tool.

Muscle damage and regeneration. Animal-model studies of cardiotoxin- or eccentric-contraction-induced muscle damage have used MGF or PEG-MGF to investigate whether exogenous E-peptide accelerates satellite-cell activation and regeneration. Results in published animal-model studies have been mixed and depend on dose, route, timing, and species.

Comparative IGF-1 family pharmacology. MGF E-peptide, mature IGF-1, LR3 IGF-1, and other IGF-1 family research tools are compared in matched cell-culture or animal-model systems to dissect IGF-1R-dependent from IGF-1R-independent effects within the broader IGF-1 family.

Cardiac biology. A separate body of literature has investigated MGF E-peptide expression and effects in cardiac muscle following ischemic damage, building on the muscle-regeneration framework to investigate whether comparable satellite-cell-like progenitor activation occurs in heart.

All applications are research-context. Nothing on this page describes a clinical protocol, dose, or therapy for human use.

MGF sits at the intersection of the IGF-1 family and the broader muscle-regeneration research landscape.

MGF (mechano growth factor) is the 24-residue C-terminal E-peptide of the IGF-1Ec splice variant of the IGF1 gene, named and characterized by Geoffrey Goldspink's laboratory at University College London in the mid-1990s. The IGF-1Ec transcript is sharply upregulated in skeletal muscle in response to mechanical loading and damage, and its pro-protein is processed into mature IGF-1 (shared with the IGF-1Ea transcript) plus the unique MGF E-peptide. The synthetic 24-residue E-peptide has been reported in published in-vitro studies to stimulate satellite-cell proliferation and migration by an IGF-1R-independent mechanism whose receptor target is not definitively established.

In published research, MGF is used as a satellite-cell-active research peptide in muscle-biology, mechanical-loading, sarcopenia, and regeneration studies. The peptide is rapidly hydrolyzed in serum (half-life of minutes), which is one reason the pegylated derivative PEG-MGF was developed for in-vivo research models. MGF has not been developed as a clinical therapy in any major jurisdiction; the FDA-approved IGF-1 product is native recombinant IGF-1 (mecasermin).

This page is research educational only. MGF supplied as a research peptide is intended for laboratory and analytical work; no therapeutic or human-use claims are made.