Calreticulin is essential for integrin-mediated calcium signalling and cell adhesion

The cytoplasmic areas of integrins, which are important mediators of cell adhesion, have a role in the regulation of cell shape, growth, motility and differentiation. The development of calreticulin-deficient embryonic stem cells and isolated embryonic fibroblasts from calreticulin mutant mice is described. Integrin-mediated adhesion was found to be severely impaired and cytosolic calcium was absent from calreticulin-deficient cells. This indicates that calreticulin is essential in the modulation of both integrin adhesive functions and integrin signalling.