Chromobox Protein Homolog 3 Is Essential for Stem Cell Differentiation to Smooth Muscles In Vitro and in Embryonic Arteriogenesis

Objective-Smooth muscle cell (SMC) differentiation is a critical process during cardiovascular formation and development, but the underlying molecular mechanism remains unclear. Methods and Results-Here we demonstrated that chromobox protein homolog 3 (Cbx3) is crucial for SMC differentiation from stem cells and that the chromodomain and chromoshadow domain of Cbx3 are responsible for Cbx3-induced SMC differentiation. Moreover, we identified that 4 amino acids (165 to 168) within the chromoshadow domain of Cbx3 are key elements for Cbx3 interaction with Dia-1- and Cbx3-induced SMC differentiation. Mechanistically, we found that Cbx3 mediates SMC differentiation through modulating serum response factor (SRF) recruitment to the promoters of SMC genes, in which the interaction between Cbx3 and Dia-1/SRF plays a crucial role in this process. Moreover, our in vivo study demonstrated that the misexpression of Cbx3 within neural crest cells of chick embryos resulted in the death of chick embryos at early stages because of the maldevelopment of branchial arch arteries. Conclusion-Our findings suggest that the interaction between Cbx3 and Dia-1/SRF is essential for SMC differentiation from stem cells and for the development of functional cardiovascular system. (Arterioscler Thromb Vasc Biol. 2011;31:1842-1852.)