High levels of mouse thymosin beta4 mRNA in differentiating P19 embryonic cells and during development of cardiovascular tissues.

The self assembly of actin and the large number of actin-binding proteins are important in the establishment of cell shape and function during embryogenesis. Thymosin beta4 (Tbeta4) is a small acidic peptide that participates in the regulation of actin polymerization in mammalian cells. In the present work, we report the presence of the mRNA encoding for Tbeta4 in mouse embryonic stem cells and its induction in P1 9 embryonal cells stimulated to differentiate into ectodermal-like (neurons and glia) or mesodermal-like cells (cardiac and skeletal muscle). The induction of Tbeta4, mRNA in P19 cells was confirmed by in situ hybridization analysis of early mouse postimplantation embryos. Noteworthy, we observed an important hybridization signal in several areas of the embryo specially in blood vessels and in heart tissues, suggesting a role for this peptide in angiogenesis. In conclusion, the results presented here demonstrate the expression of Tbeta4 gene during early embryogenesis which immediately suggests an important role for this peptide in developmental processes requiring actin-based functions such as the formation of cardiovascular system.