HIGH-LEVELS OF MOUSE THYMOSIN BETA(4) MESSENGER-RNA IN DIFFERENTIATING P19 EMBRYONIC-CELLS AND DURING DEVELOPMENT OF CARDIOVASCULAR TISSUES

The self assembly of actin and the large number of actin-binding prote ins are important in the establishment of cell shape and function duri ng embryogenesis. Thymosin beta(4) (T beta(4)) is a small acidic pepti de that participates in the regulation of actin polymerization in mamm alian cells. In the present work, we report the presence of the mRNA e ncoding for T beta(4) in mouse embryonic stem cells and its induction in P19 embryonal cells stimulated to differentiate into ectodermal-lik e (neurons and glia) or mesodermal-like cells (cardiac and skeletal mu scle). The induction of T beta(4) mRNA in P19 cells was confirmed by i n 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, s uggesting a role for this peptide in angiogenesis. In conclusion, the results presented here demonstrate the expression of T beta(4) gene du ring early embryogenesis which immediately suggests an important role for this peptide in developmental processes requiring actin-based func tions such as the formation of cardiovascular system.