Promotion of mouse embryonic stem cell differentiation by Rho kinase inhibitor Y-27632.

Rho kinase (ROCK) is one of the major downstream mediators of Rho. Rho plays crucial regulatory roles in the cellular proliferation and differentiation. Because a ROCK inhibitor, Y-27632, is known to inhibit the dissociation-induced cell death in human embryonic stem (ES) cells, we investigated the effects of this ROCK inhibitor on the differentiation of the mouse ES cells. The ROCK inhibitor promoted the differentiation of the ES cells into neurons, particularly motor and sensory neurons. The addition of both ROCK inhibitor and nerve growth factor (NGF) strongly stimulated the differentiation of the ES cells into neurons. Moreover, the ROCK inhibitor promoted the differentiation of the ES cells into muscle cells. The ES cells primarily differentiated into neurons rather than muscle cells. We found that the ROCK inhibitor may promote the neuronal differentiation of the ES cells by activating the extracellular signal-regulated kinase (ERK) signaling pathway. These results suggest that the ROCK inhibitor has a significant potential to regulate the differentiation of the ES cells.