Role of thymosin beta 4 in hair growth

Although thymosin beta 4 (T beta 4) is known to play a role in hair growth, its mechanism of action is unclear. We examined the levels of key genes in a T beta 4 epidermal-specific over-expressing mouse model and T beta 4 global knockout mouse model to explore how T beta 4 affects hair growth. By depilation and histological examination of the skin, we confirmed the effect of T beta 4 on hair growth, the number of hair shafts and hair follicle (HF) structure. The mRNA and protein expression of several genes involved in hair growth were detected by real-time PCR and western blotting, respectively. Changes in the expression of beta-catenin and Lef-1, the two key molecules in the Wnt signaling pathway, were similar to the changes observed in T beta 4 expression. We also found that compared to the control mice, the mRNA and protein expression of MMP-2 and VEGF were increased in the T beta 4 over-expressing mice, while the level of E-cadherin (E-cad) remained the same. Further, in the T beta 4 global knockout mice, the mRNA and protein levels of MMP-2 and VEGF decreased dramatically and the level of E-cad was stable. Based on the above results, we believe that T beta 4 may regulate the levels of VEGF and MMP-2 via the Wnt/beta-catenin/Lef-1 signaling pathway to influence the growth of blood vessels around HFs and to activate cell migration. T beta 4 may have potential for the treatment of hair growth problems in adults, and its effects should be further confirmed in future studies.