Follistatin 344
preclinicalAlso known as: FST-344, FS-344
**Mechanism of Action** Follistatin 344 (FST-344) is a 344-amino acid splice variant of the follistatin gene, functioning as an activin-binding glycoprotein. It neutralizes myostatin (GDF-8) and other TGF-β superfamily ligands (e.g., activin A, GDF-11) by forming inactive complexes, thereby blocking their interaction with cell-surface receptors. This antagonism removes the negative regulatory "brake" on skeletal muscle growth, promoting myoblast proliferation and differentiation via downstream Smad2/3 signaling inhibition. **Key Research Findings** Preclinical studies in rodent and non-human primate models demonstrate that systemic or local administration of FST-344 induces significant, dose-dependent increases in muscle mass and strength, with minimal off-target effects. Transgenic overexpression of follistatin in mice results in a hypermuscular phenotype (up to 200% increase in muscle weight), while acute FST-344 delivery via adeno-associated virus (AAV) vectors shows sustained muscle hypertrophy for months. Notably, FST-344 exhibits higher potency than follistatin-315 due to enhanced heparin-binding affinity and tissue retention. However, concerns regarding potential off-target effects on reproductive tissues (e.g., ovarian function) and cardiac remodeling remain unresolved in long-term studies. **Clinical Relevance** FST-344 is under preclinical investigation for muscle-wasting disorders (e.g., cachexia, sarcopenia, muscular dystrophy) and metabolic conditions. Its ability to simultaneously inhibit multiple TGF-β ligands offers a broader therapeutic window than myostatin-specific inhibitors. No human trials have been initiated; safety and efficacy data are limited to animal models. Potential applications include enhancing muscle regeneration in injury or age-related atrophy, though risks of uncontrolled hypertrophy or systemic endocrine disruption require further evaluation. For research purposes only — not medical advice.
Key data
Research & studies
Unapproved peptides like AOD-9604 and BPC-157 show favorable tissue repair in animal models but have scarce human safety data.; A parallel 'gray market' of unapproved peptides operates outside regulatory oversight, posing potential serious harm to patients.; The placebo effect and social media amplification significantly influence perceived peptide efficacy in sports medicine.; Approved peptides (e.g., tesamorelin) have undergone rigorous evaluation, unlike many marketed unapproved compounds.
All resistance training groups increased skeletal muscle mass, strength, power, follistatin, and adiponectin while reducing fat mass, myostatin, CRP, and TNF-α.; Combined upper- and lower-body training produced the largest increases in follistatin and adiponectin and the largest decreases in myostatin and CRP.; Changes in myostatin and CRP had strong positive correlations with fat mass, while follistatin and adiponectin had strong negative correlations with fat mass.; Performing only upper- or lower-body resistance training still achieved systemic improvements in muscle and inflammatory markers.
Both Cr-HCl and CrM significantly increased strength, skeletal muscle mass, and arm/thigh cross-sectional area while reducing body fat.; Supplementation groups showed significant increases in growth hormone, IGF-1, follistatin/myostatin ratio, and testosterone/cortisol ratio.; Cortisol and ACTH levels significantly decreased in all supplementation groups compared to placebo.; Cr-HCl did not demonstrate any benefit over CrM in any measured outcome.
Frequently asked questions
What is Follistatin 344?
**Mechanism of Action** Follistatin 344 (FST-344) is a 344-amino acid splice variant of the follistatin gene, functioning as an activin-binding glycoprotein. It neutralizes myostatin (GDF-8) and other TGF-β superfamily ligands (e.g., activin A, GDF-11) by forming inactive complexes, thereby blocking their interaction w
How does Follistatin 344 work?
Activin-binding glycoprotein that antagonizes myostatin (GDF-8) to release the brake on skeletal muscle growth.
What is the research status of Follistatin 344?
Follistatin 344 is currently classified as preclinical, with 27 research references on record. This is for research purposes only and is not medical advice.
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