Follistatin

Overview

Follistatin is a naturally occurring secreted glycoprotein that acts as a potent endogenous antagonist of myostatin, activin A, activin B, and several other members of the TGF-β superfamily. By binding to and neutralizing these ligands before they can engage their receptors, Follistatin promotes skeletal muscle hypertrophy and has been studied as a research tool for understanding muscle regulation, muscular dystrophy, sarcopenia, and metabolic conditions. FenaLife supplies Follistatin for laboratory research use only.

Research Background

Follistatin’s role in muscle biology was underscored by early animal studies demonstrating dramatic muscle mass increases in mice overexpressing the protein — with some models showing two-fold gains in muscle mass compared to wild-type controls. Gene delivery studies in non-human primates (Lee et al., Science Translational Medicine) confirmed significant muscle hypertrophy following follistatin gene therapy. In human research, early gene therapy trials targeting muscular dystrophy and Becker muscular dystrophy explored intramuscular AAV-mediated follistatin delivery, with functional improvements observed in some subjects. Engineered follistatin variants (e.g., FST315-ΔHBS-Fc) have been developed to extend serum half-life while limiting off-target effects on reproductive tissue, a known concern with full-length follistatin isoforms.

Studied Mechanisms

Follistatin operates by directly binding the mature, active forms of myostatin and activin A/B with high affinity, forming stable complexes that prevent receptor engagement. It acts upstream of ActRIIA/B, effectively functioning as a sink for multiple pro-catabolic TGF-β ligands simultaneously. This broad inhibitory profile distinguishes Follistatin from antibodies like Trevogrumab (myostatin-selective) or Bemagromab (receptor-level blockade), making it a valuable tool for studying the comparative roles of individual TGF-β family members in muscle regulation. Follistatin has also been studied in reproductive biology, bone metabolism, and inflammatory signaling due to its diverse ligand-binding profile.

Molecular Profile

Type: Glycoprotein (endogenous secreted protein). Primary targets: Myostatin (GDF-8), Activin A, Activin B, GDF-11, BMP-2, BMP-4, BMP-7. Key isoforms: FST288 (cell-bound), FST315 (circulating), FST344 (extended form). Molecular weight: ~35 kDa (protein backbone); glycosylation increases apparent MW. Purity: ≥98% by HPLC.

Storage and Handling

Store lyophilized Follistatin at -20°C or -80°C for long-term preservation. Reconstitute with sterile or bacteriostatic water. Store reconstituted solution at 4°C and use within 4 to 6 weeks. Avoid repeated freeze-thaw cycles. Carrier protein (e.g., 0.1% BSA) may be added to improve stability in solution.

Research Use Only

For laboratory research purposes only. Not for human or veterinary use. Certificate of Analysis available per batch.