Granulocyte function in grancalcin-deficient mice.

Grancalcin, one of the penta-EF-hand Ca(2+) binding proteins, is expressed at high levels in polymorphonuclear granulocytes (neutrophils). EF-hand proteins are implicated in the regulation of diverse processes including cell migration, apoptosis, and mobilization of neutrophil effector functions. To determine the role of grancalcin in vivo, we inactivated the gene encoding grancalcin (Gca) in embryonic stem cells and generated grancalcin-deficient mice. Homozygous Gca mutants appeared healthy and reproduced normally. Leukocyte recruitment into the peritoneal cavity upon induction of inflammation was not significantly affected by the absence of grancalcin. The mutants also resisted systemic fungal infection similarly to wild-type mice, and in vitro killing of Staphylococcus aureus by inflammatory cells was not significantly impaired. While marginally increased survival rates of mutants faced with endotoxic shock may indicate a contribution of grancalcin to immunopathogenesis, it is not essential for vital leukocyte effector functions required to control microbial infections.