TB-500 — Published Research

Thymosin beta-4 is the principal G-actin-sequestering peptide in mammalian cells, maintaining the pool of unpolymerized actin monomers. The binding interaction occurs primarily through the central LKKTETQ motif and flanking residues, with a 1:1 stoichiometry and Kd of approximately 0.7 µM. By regulating the G-actin/F-actin equilibrium, Tβ4 modulates actin-dependent cellular processes including motility, division, and morphogenesis. NMR studies reveal that Tβ4 is intrinsically disordered in solution but adopts a helical conformation upon actin binding.

Safer D et al. “Thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable.” J Biol Chem. 1991. PubMed

In vitro scratch wound assays using dermal keratinocytes demonstrated that thymosin beta-4 at concentrations of 1–100 ng/mL increased the rate of keratinocyte migration across the wound gap. The migration effect was associated with increased lamellipodial protrusion and was abolished by cytochalasin D (an actin polymerization inhibitor), confirming actin-dependent mechanisms. Boyden chamber assays further demonstrated directed chemotaxis of endothelial cells toward Tβ4 concentration gradients.

Malinda KM et al. “Thymosin beta4 accelerates wound healing.” J Invest Dermatol. 1999. PubMed

Epicardial progenitor cell studies in murine models demonstrated that Tβ4 activates Akt signaling in epicardial cells, inducing their mobilization and differentiation. The mechanism involves Tβ4 interaction with integrin-linked kinase (ILK) and PINCH-1 in a complex that activates PI3K/Akt survival signaling. In embryonic heart explant cultures, Tβ4 promoted epicardial cell outgrowth and neovascularization, as measured by von Willebrand factor staining and vessel density quantification.

Smart N et al. “Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization.” Nature. 2007. PubMed

In vitro and in vivo studies have investigated Tβ4’s effects on NF-κB signaling in inflammatory models. In LPS-stimulated macrophage cultures, Tβ4 reduced nuclear translocation of NF-κB p65 and decreased production of pro-inflammatory cytokines TNF-α and IL-1β in a concentration-dependent manner. Corneal injury models in mice demonstrated that topical Tβ4 application reduced neutrophil infiltration and MMP-9 expression, with the anti-inflammatory effects mediated through suppression of the NF-κB/IκBα pathway.

Sosne G et al. “Thymosin beta 4 suppresses LPS-induced NF-κB activation in corneal epithelial cells.” Exp Eye Res. 2007. PubMed