Over-expression of thymosin β4 promotes abnormal tooth development and stimulation of hair growth

Thymosin β4 has multi-functional roles in cell physiology. It accelerates wound healing, hair growth and angiogenesis, and increases laminin-5 expression in corneal epithelium. Furthermore, thymosin β4 stimulates tumor growth and metastasis by induction of cell migration and vascular endothelial growth factor-mediated angiogenesis. Using a construct on the skinspecific keratin-5 promoter, we have developed thymosin β4 over-expressing transgenic mice to further study its functional roles. Thymosin β4 in adult skin and in embryonic stages of the transgenic mouse was analyzed by both Western blot and immunohistochemistry. The overexpression of thymosin β4 was observed especially around hair follicles and in the teeth in the transgenic mice. We examined the phenotype of the thymosin β4 over-expressing mice. Hair growth was accelerated. In addition, the transgenic mice had abnormally-shaped white teeth and dull incisors. We found that the expression of laminin-5 was up-regulated in the skin of the transgenic mice. We conclude that thymosin β4 has an important physiological role in hair growth and in tooth development.