MGF (Mechano Growth Factor) is a locally acting splice variant of the IGF‑1 gene (human IGF‑1Ec; rodent IGF‑1Eb) that is upregulated by mechanical stress and tissue injury. It helps initiate repair by activating resident stem/progenitor cells—most notably muscle satellite cells—and shows context‑specific roles in skeletal muscle, heart, and brain in preclinical models. (PubMed)
Fast Answer — Executive Summary (40–60 words).
MGF is an IGF‑1 splice variant that rises in tissue after mechanical stress to “prime” regeneration by expanding local progenitor cells, especially in muscle. In humans, MGF (IGF‑1Ec) increases within hours after resistance exercise—an effect blunted with aging—and it differs mechanistically and temporally from systemic IGF‑1. Evidence remains preclinical and mixed. (PubMed)
Entity Properties (Educational)
| Property | Details |
|---|---|
| Aliases/Synonyms | Mechano Growth Factor (MGF); IGF‑1Ec (human), IGF‑1Eb (rodent) (PubMed) |
| Family/Pathway | Alternative splice variant of IGF‑1; part of the GH/IGF axis; produced and acts locally (autocrine/paracrine) after load/injury (PMC) |
| Sequence (AA) | Human MGF E‑domain peptide (24 aa): YQPPSTNKNTKSQRRKGSTFEEHK (synthetic form used in several studies) (PMC) |
| Molecular Weight (Da) | ~2,847 Da (calculated from the 24‑aa sequence above; monoisotopic) |
| CAS (if applicable) | Not assigned for the 24‑aa research peptide (isoform‑specific E‑domain) |
| Typical Diluent(s) | Sterile saline or buffered saline in preclinical models (e.g., osmotic‑pump infusion in mice; intracoronary delivery in sheep). Cell‑culture studies commonly use aqueous buffers. (PMC) |
| Example Concentration(s) | In vitro: 100 nM E‑peptides used to study signaling and myoblast behavior. In vivo: continuous infusion ~4.5 mg/kg/day of stabilized MGF E‑peptide in post‑MI mouse models. (Illustrative, research‑only.) (PLOS) |
| Storage (lyophilized / after reconstitution) | Lyophilized peptides are generally more stable when kept cold and dry (low temperature, protection from moisture/light). In solution, stability is shorter; minimize time at ambient conditions. (General peptide‑stability guidance.) (PMC) |
Normalization note: You may see “IGF‑1Eb/Ec,” “MGF‑E,” or “MGF‑24aa‑E.” We standardize to MGF (IGF‑1Ec) for human and use MGF E‑domain peptide for the 24‑amino‑acid synthetic research fragment. (PLOS)
Core Concepts & Key Entities
What is MGF at the gene level? MGF is an alternative 3′ splice variant of the IGF‑1 gene that encodes a distinct C‑terminal E‑domain (Ec in humans). Mechanical overload and injury shift IGF‑1 splicing toward this variant in the affected tissue. The MGF mRNA pulse is rapid, preceding (and differing from) the later rise of “classical” IGF‑1Ea. (Physiology Journals)
Where does MGF show up physiologically? Skeletal muscle is the canonical site: MGF mRNA increases within ~2–3 h after heavy resistance exercise in young adults but is attenuated in older adults. Rodent studies report similar “first‑responder” dynamics after damage or GH perturbation. (PubMed)
How is MGF different from circulating IGF‑1? IGF‑1 is a 70‑aa hormone that circulates and signals via IGF‑1 receptor (IGF‑1R) in many tissues. MGF is produced locally and is thought to prime regeneration by expanding progenitor pools; its E‑peptide biology (and receptor usage) is distinct and still debated. (Physiology Journals)
Related entities: IGF‑1 (IGF‑1Ea), E‑peptides/E‑domains, satellite cells (muscle stem cells), PEG‑MGF (pegylated MGF analogs), and MAPK/ERK signaling often appear in the MGF literature. (PLOS)
What MGF Does (Mechanism → Outcomes)
MGF acts as an early, local “prime” for regeneration by expanding progenitor cells and modulating repair signaling. In skeletal muscle, the MGF E‑domain peptide can increase proliferation and delay differentiation of human muscle progenitors in vitro—conceptually supplying more building blocks for later regeneration. (PubMed)
Is MGF independent of the IGF‑1 receptor? Evidence is conflicting across models:
- Independent effects reported: The MGF C‑terminal peptide showed neuroprotection in ischemia models without classical IGF‑1–like behavior, suggesting distinct signaling. (PubMed)
- Dependent/modulatory effects reported: E‑peptide activity (including MGF‑like EB peptides) often requires IGF‑1R and can tune IGF‑1 signaling toward MAPK/ERK, not AKT, in myoblasts. (PLOS)
- Full‑length MGF vs. E‑peptide: Full‑length pro‑IGF‑1Ec (MGF) can activate IGF‑1R at higher concentrations in vitro, blurring boundaries between “independent” and “modulatory” models. (PLOS)
Key practical takeaway: MGF’s regenerative role is best framed as a short‑lived, local signal that cooperates with (not replaces) IGF‑1—amplifying pro‑proliferative cascades early so differentiation and tissue rebuilding can proceed later. This “prime‑then‑build” sequence aligns with observed early MGF and later IGF‑1Ea expression kinetics after load. (PubMed)
How long does MGF last? In cell media, the E‑peptide analogous to MGF (EB) exhibits a short full‑length half‑life (~20 min) before proteolysis, with fragments persisting longer—underscoring why many in vivo studies stabilize or modify the peptide. (PLOS)
Therapeutic Implications (What the Data Actually Show)
Bottom line: MGF is promising but preclinical. Several animal and cell studies support regenerative or cytoprotective roles; human outcome data are lacking, and some experiments report null effects of synthetic MGF on muscle cells.
Skeletal Muscle: Recovery & Hypertrophy
- Acute exercise studies (humans): After heavy resistance exercise, MGF mRNA rises in young muscle (∼2.5 h post‑session) while older adults show a blunted MGF response—one plausible factor in age‑related recovery differences. (PubMed)
- Mechanistic cell data: The MGF E‑peptide can increase proliferation and fusion potential of human muscle progenitors in vitro, consistent with a “more cells to repair” model. (PubMed)
- Regeneration timing: During muscle damage/regeneration cycles, IGF‑1 isoforms change over time—with MGF/Ec expression in early phases and IGF‑1Ea later as fibers mature. (IIAR Journals)
- Contradictory results: A rigorous study found no apparent effect of synthetic MGF peptide on myoblast proliferation or primary muscle stem cells, highlighting model/peptide‑chemistry sensitivity and caution in extrapolation. (Physiology Journals)
Heart: Injury & Remodeling
- Myocardial infarction (mice): Continuous delivery of a stabilized 24‑aa MGF E‑peptide preserved cardiac function and delayed decompensation after MI—both in acute and chronic windows. (PMC)
- Localized cardiac delivery: Cardiac‑restricted administration (polymeric microstructures) of MGF E‑domain peptide mitigated adverse remodeling, supporting local‑delivery strategies. (PMC)
Brain & Nerve: Neuroprotection and Aging
- The MGF C‑terminal peptide showed strong neuroprotection in ischemia models, reducing neuronal death in vivo and in vitro. (PubMed)
- MGF expression appears in neurogenic brain regions and declines with age in mice; overexpression improved specific neural measures—suggesting a role in neural progenitor dynamics. (BioMed Central)
Other Tissues
- MGF‑related signaling has been explored in connective tissue/cellular migration and vascular contexts, though translation is preliminary. (Journal of Molecular Endocrinology)
Evidence grade: Most results are preclinical (cells/rodents/large animals). Human therapeutic evidence is absent, and the synthetic peptides used can differ (sequence length, modifications), affecting outcomes. Balance enthusiasm with skepticism. (OUP Academic)
Step‑by‑Step (Educational) — Designing an MGF Research Workflow
What’s the practical, educational “how‑to”? Design around MGF’s short‑lived, local biology: choose models, dosing windows, and endpoints that capture early proliferative effects and later differentiation separately.
1) Define the model and window you want to study
Pick in vitro (human myoblasts/myogenic progenitors) for mechanistic endpoints or in vivo injury/overload models (e.g., post‑MI mice, muscle injury). Time your sampling to early hours to days post‑stimulus where MGF/Ec dynamics appear. (PubMed)
2) Choose the form of MGF and validate identity
Decide between full‑length pro‑IGF‑1Ec vs 24‑aa E‑domain peptide. Verify sequence (e.g., YQPPSTNKNTKSQRRKGSTFEEHK) and purity (HPLC/MS). Note that full‑length Ec can activate IGF‑1R at high concentrations; E‑peptides often modulate IGF‑1R signaling. (PMC)
3) Set concentrations and controls (anchored to literature)
For cells, start in the 10–100 nM range (commonly used to probe E‑peptide biology) with vehicle and IGF‑1 comparators. If in vivo, reference prior dosing paradigms (e.g., continuous infusion ~4.5 mg/kg/day post‑MI mice) and include sham and IGF‑1 arms. (PLOS)
4) Plan readouts that map to “prime‑then‑build”
Early: proliferation markers (EdU/BrdU, Ki‑67), satellite cell counts, MAPK/ERK activation. Later: myogenic differentiation (Myogenin, MyHC), fiber cross‑sectional area, functional metrics (force, ejection fraction for heart). (PLOS)
5) Use appropriate vehicles and delivery
For cells: aqueous buffers compatible with viability. For animal models: sterile saline or buffered saline (as in cardiac studies) and delivery that matches your hypothesis (local vs systemic). Record pH/osmolality to reduce confounders. (PMC)
6) Address stability up front
E‑peptides are labile (e.g., EB half‑life ~20 min in media). Minimize bench time in solution; consider stabilization (e.g., D‑Arg substitutions, amidation) when scientifically justified, and document it transparently. (PLOS)
7) Store and handle like any research peptide
Keep lyophilized peptide cold and dry; protect from moisture/light; limit freeze–thaw. Use fresh aliquots for reconstituted solutions. These are general peptide‑stability best practices from biopharmaceutics literature. (PMC)
Compliance note: MGF is a research peptide. No human therapeutic indications are approved. MGFs and IGF‑1 are prohibited in sport (WADA S2); competitive athletes must avoid use. (Wada-Ama)
Comparison / Alternatives
Answer first: MGF is a local, short‑window primer; IGF‑1 is a systemic builder; PEG‑MGF seeks longer exposure via chemistry, but direct clinical data for PEG‑MGF are lacking. (Physiology Journals)
| Feature | MGF (IGF‑1Ec / E‑domain) | IGF‑1 (IGF‑1Ea / mature 70‑aa) | PEG‑MGF (pegylated MGF analog) |
|---|---|---|---|
| Biological role | Early, local response to load/injury; expands progenitor pools (pro‑proliferative) | Endocrine/paracrine growth factor; drives differentiation and anabolic signaling broadly | Designed to prolong MGF exposure via PEG; preclinical/pharmacologic rationale, limited peptide‑specific PK data |
| Receptor behavior | E‑peptide effects often modulate/require IGF‑1R; full‑length Ec can activate IGF‑1R at high concentration; literature mixed | Binds IGF‑1R with well‑characterized downstream AKT & MAPK pathways | PEGylation typically extends half‑life and reduces clearance for peptides/proteins (general principle) |
| Temporal profile | Short‑lived; E‑peptides are labile in media/tissues | Longer‑lived (binding proteins prolong exposure) | Prolonged vs native MGF (by design) |
| Evidence base | Cell/animal data; mixed findings across assays | Robust physiology; approved drug forms for specific deficiencies (outside this article’s scope) | Concept supported by PEG literature; no standardized human PK/efficacy for PEG‑MGF |
| Use context | Local delivery post‑injury/overload in models | Systemic actions; broad anabolic/metabolic roles | Hypothetical reduced dosing frequency if PK extended |
Citations (table synthesis): MGF early/local kinetics and aging effect (J Physiol 2003); E‑peptide dependence on IGF‑1R (PLOS One 2012); full‑length Ec activating IGF‑1R (PLOS One 2016); short‑lived E‑peptide (PLOS One 2012); PEGylation extends peptide half‑life (general) (Expert Opin Drug Deliv, Front Pharm 2024). (PubMed)
Templates / Checklist (Copy‑Ready)
Educational MGF Research Planning Checklist
- Define the question (e.g., “Does MGF expand satellite cells after acute overload?”).
- Select the form (full‑length IGF‑1Ec vs 24‑aa E‑domain); document modifications. (PMC)
- Choose comparators (vehicle, IGF‑1, possibly stabilized analogs). (PLOS)
- Anchor concentrations to literature (10–100 nM for cells; published mg/kg/day regimens for animals). (PLOS)
- Time your sampling to capture early proliferation and later differentiation phases. (PubMed)
- Pre‑register endpoints (e.g., Ki‑67, Myogenin, ERK/Akt, function). (PLOS)
- Plan delivery (e.g., local vs systemic; saline vehicles consistent with prior studies). (PMC)
- Mitigate instability (aliquot, cold chain, minimize bench time); consider stabilized analogs where justified. (PLOS)
- Follow storage best practices (lyophilized cold/dry; fresh solutions). (PMC)
- Document ethics & compliance; avoid prohibited use in sport (WADA S2). (Wada-Ama)
FAQs (NLP‑Friendly, Answer‑First)
What is MGF?
MGF is an IGF‑1 splice variant (IGF‑1Ec) that rises locally after mechanical stress to prime tissue repair by expanding progenitor cells, especially in muscle. It is distinct from circulating IGF‑1 in timing and likely in signaling nuance. Evidence is largely preclinical. (PubMed)
Is MGF the same as IGF‑1?
MGF is not the same as IGF‑1; MGF is a locally acting splice variant with a unique E‑domain. IGF‑1 is systemic and binds the IGF‑1 receptor to drive differentiation and growth, whereas MGF surges early, locally, and emphasizes progenitor expansion. (PubMed)
Does MGF act through the IGF‑1 receptor?
MGF’s receptor story is mixed. Several studies show E‑peptide actions require or modulate IGF‑1R, while full‑length IGF‑1Ec can ligate IGF‑1R at higher concentrations; other reports describe IGF‑1R‑independent effects in specific neural models. (PLOS)
Is MGF banned in sports?
Yes. MGFs and IGF‑1 (and analogs) appear on the WADA Prohibited List (S2). Athletes subject to anti‑doping rules should not use MGF in any form. (Wada-Ama)
How stable is MGF in solution?
E‑peptides analogous to MGF degrade quickly in biological media (full‑length EB half‑life ~20 min in vitro); many studies therefore use stabilized analogs or delivery systems. Store lyophilized peptide cold/dry and limit time in solution. (PLOS)
What is PEG‑MGF and why is it used?
PEG‑MGF is a pegylated MGF analog designed to extend exposure by slowing clearance—consistent with how PEGylation prolongs half‑life for many peptides/proteins. Direct human PK/efficacy data for PEG‑MGF are not established. (PMC)
Next Steps
If you’re evaluating MGF academically or for laboratory research, center your design on early, local effects and use rigorous controls against IGF‑1. Treat every claim skeptically—the literature contains both positive and null findings depending on peptide form and model. No human therapeutic indications are established. (Physiology Journals)
For researchers seeking test materials, ensure supplier transparency (identity, purity analytics). For educational reference, MGF (2 mg) for research use is available from PureLabPeptides: purelabpeptides.com/buy-peptides/buy-mgf-2mg/.
Key take‑home: MGF appears to “prime” regeneration (especially in muscle) with a short, local signal that likely cooperates with IGF‑1; translating that into therapy will require standardized peptides, delivery, and human trials. (PubMed)