Tissue biology · Thymosin β4
Thymosin β4: actin binding and cardiac cell signaling in mouse models
October 22, 2026 · 1 min read · Models: Mouse, Cell culture
Thymosin β4 is a 43-amino-acid actin-sequestering protein. Two landmark mouse studies in Nature linked it to ILK–Akt signaling in cardiomyocytes and to the reactivation of adult epicardial progenitor cells.
A summary of published research for scientific reference. It is not product information or medical advice, and it does not describe or endorse use in humans or animals. Findings from cell culture and animal models often do not carry over to other systems.
An actin-binding protein with signaling roles
Thymosin β4 (Tβ4) is one of the most abundant intracellular peptides in mammalian cells. It binds monomeric G-actin and regulates the pool available for filament assembly, so it affects cell motility. Its actin-binding motif (centered on the sequence LKKTETQ) is the basis of shorter synthetic fragment peptides.
Landmark studies
Bock-Marquette and colleagues (Nature, 2004) reported that Tβ4 activates integrin-linked kinase (ILK) and Akt in cardiomyocytes. In a mouse coronary ligation model, they compared infarct size and cardiac function with controls and linked the differences to ILK–Akt signaling.
Smart and colleagues (Nature, 2007) showed that Tβ4 could mobilize adult epicardial cells. These cells re-expressed embryonic programs and contributed to new vasculature after injury. This made Tβ4 a widely used tool for studying epicardial reactivation.
Caveats
Later work questioned how much epicardium-derived cells give rise to new cardiomyocytes, as opposed to vascular and fibroblast lineages. Results also depend on timing, delivery and model. Researchers should also note that fragment peptides do not necessarily reproduce every activity of full-length Tβ4.
References
- Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432:466–472.
- Smart N, Risebro CA, Melville AAD, et al. Thymosin β4 induces adult epicardial progenitor mobilization and neovascularization. Nature. 2007;445:177–182.
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