Follistatin 315 1 mg

Overview of Follistatin 315

Follistatin 315 is one of several naturally occurring versions of the follistatin protein, a globular glycoprotein that controls the activity of members of the TGF-beta signaling family. It binds and neutralizes activin, a regulatory molecule that can either promote or restrain cell division depending on the tissue context, so follistatin often produces the opposite effect by blocking activin’s actions. Follistatin also attaches to myostatin in muscle, easing the brake that myostatin places on muscle growth and allowing muscle cells to expand and multiply more readily. Experimental work links follistatin to roles in inflammation control, early development, and reproductive function.

Follistatin 315 Structure

Sequence: G NCWLRQAKNG RCQVLYKTEL SKEECCSTGR LSTSWTEEDV NDNTLFKWMI FNGGAPNCIP CKETCENVDC GPGKKCRMNK KNKPRCVCAP DCSNITWKGP VCGLDGKTYR NECALLKARC KEQPELEVQY QGRCKKTCRD VFCPGSSTCV VDQTNNAYCV TCNRICPEPA SSEQYLCGND GVTYSSACHL RKATCLLGRS IGLAYEGKCI KAKSCEDIQC TGGKKCLWDF KVGRGRCSLC DELCPDSKSD EPVCASDNAT YASECAMKEA ACSSGVLLEV KHSGSCNSIS EDTEEEEEDE DQDYSFPISS ILEW
Molecular Weight: 3470 g/mol
PubChem CID: 178101631 (Full follistatin protein)
Synonyms: Activin-Binding Protein, FSH-Suppressing Protein, FST, FST-315

Follistatin 315 Research

Follistatin was first described as a factor in ovarian fluid that suppressed follicle-stimulating hormone release. Subsequent work showed that the original precursor protein is processed into several shorter variants, including follistatin 315. These related forms share overlapping biological actions but are distributed somewhat differently across organs and tissues. Genetic disruption of the follistatin gene in animal models leads to severe developmental abnormalities and rapid death shortly after birth, highlighting its essential role in organ formation. When a functional version of the human 315 variant is introduced into such models, partial rescue of defects has been observed, pointing to involvement in blood vessel formation, skeletal muscle development, fat storage, inflammatory regulation, and heart performance.

Follistatin 315 and Skeletal Muscle Growth

Interest in follistatin 315 increased dramatically after experiments in which alterations to growth-regulating pathways produced animals with unusually large musculature. Blocking the gene for myostatin alone roughly doubled muscle mass in certain models. When this approach was combined with increased expression of follistatin, the gain in muscle size was even more dramatic, with some animals displaying several times the normal muscle volume. These results suggest that follistatin not only counteracts myostatin’s inhibitory influence but also enhances muscle growth through at least one additional, myostatin-independent route that has not yet been fully mapped.

In models of neuromuscular disease where nerve cells that innervate muscles gradually degenerate, administration of follistatin has been shown to help maintain muscle size and strength. Treated animals display larger muscle fibers, improved movement, and greater survival compared with untreated counterparts. Notably, the protection is seen not only in muscle tissue but also in specific nerve cell populations in the spinal cord, implying that follistatin may indirectly support motor neurons as well as muscle fibers.

Studies in primates with muscle-wasting conditions have likewise reported increases in muscle volume and function when follistatin levels are experimentally boosted. Together, these findings position follistatin 315 as a powerful amplifier of muscle-building signals with relevance for both inherited and acquired muscle disorders.

Follistatin 315 in Inflammation and Tissue Remodeling

Follistatin and activin form a counterbalancing pair in many inflammatory settings. When activin A is overabundant or follistatin levels are relatively low, inflammatory processes and tissue scarring tend to worsen. In autoimmune joint disease models, excess activin intensifies joint damage, while supplemental follistatin dampens the inflammatory response and eases clinical symptoms. These opposing patterns fit with the known ability of follistatin to bind and neutralize activin.

Similar trends have been documented in chronic airway disease, where higher activin levels correlate with more severe respiratory symptoms and underlying airway remodeling. Although baseline follistatin is present, it is insufficient to counteract the excess activin. When experimental animals receive additional follistatin directly to the airways, long-term structural changes in the bronchial walls are reduced, suggesting a potential avenue for limiting permanent lung damage in chronic respiratory conditions.

Because chronic inflammation and progressive scarring are key factors in the failure of transplanted lungs and other organs, there is interest in whether carefully dosed follistatin therapy could help preserve graft function by limiting destructive remodeling. More broadly, activin-driven pathways have been implicated in wasting syndromes, severe systemic infection, and fibrotic diseases, and follistatin is being evaluated as a possible countermeasure in several of these contexts.

Follistatin has also shown promise in reducing scarring associated with radiation exposure. In experimental models of skin and soft-tissue irradiation, treatment with follistatin lessened typical signs of fibrotic change, including thickening of tissue layers and upregulation of key fibrosis markers. Similar protective effects have been noted in models where certain anticancer drugs commonly provoke lung scarring. By moderating these responses, follistatin may one day help make intensive treatments more tolerable while preserving long-term organ function.

Influence on Blood Vessel Growth and Repair

Activin and follistatin exert different effects depending on the cell type. In vascular smooth muscle, activin tends to encourage proliferation, whereas in endothelial cells that line blood vessels it suppresses growth. Endothelial cells themselves produce follistatin during early stages of vessel formation, likely as a local safeguard against excessive activin signaling. In this way, follistatin helps create conditions that are more favorable to healthy vessel growth.

Experimental work in models of reduced blood supply shows that providing follistatin can enhance the ability of the vascular system to recover. Treated animals demonstrate improved vessel function and more efficient restoration of blood flow to regions that were previously deprived of oxygen. These findings suggest that follistatin 315 could be useful in conditions where rapid revascularization is needed, such as after blockage of arteries in the heart or brain, or in the recovery phase after major trauma, surgery, or burns, when tissues are heavily dependent on timely return of circulation.

Follistatin 315 and Kidney Protection

Chronic kidney disease involves a combination of ongoing inflammation, oxidative stress, cell loss, and gradual replacement of normal tissue with scar tissue. Given follistatin’s role in controlling inflammatory mediators and influencing blood vessel responses, researchers have explored its effects in kidney injury models. In these studies, administration of follistatin reduces markers of cell death and oxidative damage while limiting the extent of fibrotic remodeling. Animals receiving follistatin retain more functional kidney tissue and show a slower progression of structural damage, suggesting that the protein may help preserve organ function and delay the need for advanced interventions.

Follistatin as a Marker of Disease State

Because follistatin is tightly linked to inflammation and tissue remodeling, its circulating level appears to rise as the body attempts to counteract emerging pathology. In individuals with early signs of cardiovascular disease, higher follistatin concentrations have been detected in association with developing vessel wall changes. This has led to the proposal that follistatin could serve as a biomarker of metabolic and vascular stress, potentially flagging disease processes before they manifest clearly on imaging or through symptoms.

In more advanced stages of heart disease, increased follistatin has been associated with structural changes in the main pumping chamber of the heart, reflecting attempts to adapt to ongoing injury. Tracking these levels over time may help clinicians follow the course of heart failure and refine decisions about when to adjust therapy, escalate treatment, or consider more definitive options.

Engineered Variants and Therapeutic Design

While naturally produced proteins like follistatin can have powerful protective effects, they are not always ideal in their original form for therapeutic use. They may be cleared from the body too quickly, be difficult to formulate, or produce unintended actions at higher doses. Research on follistatin is being used as a template for systematically modifying protein structure to improve stability, extend circulation time, and fine-tune selectivity for desired targets. Engineered follistatin derivatives have already demonstrated more favorable pharmacokinetic properties than the native molecule in experimental settings, illustrating how rational redesign can turn endogenous regulators into more practical therapeutic candidates.

Follistatin 315 has shown moderate side effects in animal models, with poor activity after oral delivery and strong bioavailability when administered by subcutaneous injection. The dosages used in these studies are tailored to the specific species and experimental conditions and cannot be directly applied to people. At present, follistatin 315 is intended exclusively for controlled laboratory and scientific research and is not approved for human use or unsupervised application.