Calreticulin, a calcium-binding molecular chaperone, is required for stress response and fertility in Caenorhabditis elegans

Calreticulin (CRT), a Ca2+-binding protein known to have many cellular func tions, including regulation of Ca2+ homoeostasis and chaperone activity, is essential for heart and brain development during embryogenesis in mice. He re, we report the functional characterization of Caenorhabditis elegans cal reticulin (crt-1). A crt-1 null mutant does not result in embryonic lethali ty but shows temperature-dependent reproduction defects. In C. elegans CRT- 1 is expressed in the intestine, pharynx, body-wall muscles, head neurons, coelomocytes, and in sperm. crt-1 males exhibit reduced mating efficiency a nd defects late in sperm development in addition to defects in oocyte devel opment and/or somatic gonad function in hermaphrodites. Furthermore, crt-1 and itr-1 (inositol triphosphate receptor) together are required for normal behavioral rhythms. crt-1 transcript level is elevated under stress condit ions, suggesting that CRT-1 may be important for stress-induced chaperoning function in C. elegans.