Grant: Operating Grant

Work from several laboratories has demonstrated that cell shape, cytoskeletal tension and substratum elasticity direct differentiation in many cell types including embryonic stem cells. Calreticulin, a Ca-binding protein either by its role in intracellular Ca homeostasis or as a helper protein, modulates signalling pathways that control cell lineage specification and tissue formation. The growth substratum also influences the formation of tissues by affecting the cell adhesion and shape, which are modulated by calreticulin. Thus, both cell shape and signalling pathways are affected by calreticulin expression level. Consequently, we postulate that the cell fate choice is controlled by the combinatorial action of calreticulin level of expression and biomechanics of the substratum. While the role of calreticulin in adipogenesis and cardiomyogenesis from ES cells has been established, its role in skeletogenesis is not yet clear. In the present proposal, we thus wish to first elucidate the role of calreticulin in differentiation of embryonic stem cells towards skeletal tissue. Next, we will elucidate the role of substratum biomechanics in directing differentiation of embryonic stem cells in the presence or absence of calreticulin. These experiments will allow us to delineate the role of calreticulin in cell differentiation from embryonic stem cells and will address the emerging question of the impact of the biomechanics of the environment on cell fate. The results may have important implications for tissue engineering and regenerative medicine.