TB-500
Thymosin Beta-4 (synthetic fragment)
The actin-sequestering peptide behind cellular motility and cardiac repair.
Half-life
~ several hours (fragment); full Tβ4 is endogenous
Mol. weight
~ 4.9 kDa (full Tβ4); fragment varies
Sequence
Fragment of thymosin beta-4 (actin-binding domain)
Discussions
1 threads
Overview
TB-500 is a synthetic fragment of thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide that is the most abundant G-actin (monomeric actin) binding protein in mammalian cells. Tβ4 is implicated in cell migration, proliferation, angiogenesis, inhibition of apoptosis, and inflammation control — and has shown remarkable cardiac repair potential in developmental biology research by reactivating embryonic repair programs in adult hearts.
Mechanism of action
Tβ4's primary action is sequestering G-actin, maintaining a pool of monomeric actin that cells can rapidly polymerize into filaments for migration — essential for wound healing and tissue remodeling. In the heart, Tβ4 activates integrin-linked kinase (ILK) and downstream Akt, promoting cardiac cell survival and migration. It also activates capsulin-positive progenitor cells and triggers organ-wide epicardial thickening, effectively reminding adult organs of their embryonic state to initiate regeneration. TB-500 is the short synthetic fragment (commonly the N-terminal actin-binding domain, ~17 amino acids) used in research to deliver the actin-sequestering and tissue-repair signaling of the full-length molecule.
Researched benefits
- Promotes cell migration and tissue remodeling via actin sequestration
- Stimulates angiogenesis and inhibits apoptosis
- Demonstrated cardiac cell survival and repair in animal models (ILK/Akt pathway)
- Activates progenitor cells and embryonic-like repair programs in the heart
- Anti-inflammatory and wound-healing activity in preclinical studies
Considerations
- Clinical evidence in humans is limited; most data is preclinical
- TB-500 is a fragment of full-length thymosin beta-4 — distinct from the native molecule
- Not FDA-approved; research use only
- Should be researched under professional guidance
Key Academic Literature & Studies
Search more in PubMedPeer-reviewed citations and clinical trials evaluating TB-500 in scientific literature.
Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair
Nature · 2004 · PMID: 15549095 · DOI: 10.1038/nature03173
Thymosin beta4: actin-sequestering protein and its multifunctional therapeutic applications
Expert Opinion on Biological Therapy · 2010 · PMID: 20074005 · DOI: 10.1517/14712590903525287
Articles & logs
Actin Sequestration, Explained
Why the most abundant actin-binding protein in your cells is central to wound healing.
By Editorial Team
Cardiac Regeneration: The Embryonic Program
How Tβ4 reactivates embryonic repair programs in adult hearts — the Bock-Marquette / Srivastava line of research.
By Community Member