Cooperation of Tyrosine Kinases P72syk and P53/56lyn Regulates Calcium Mobilization in Chicken B Cell Oxidant Stress Signaling

Abstract
A chicken B cell line DT40 and its syk‐negative or lyn‐negative mutants were used to investigate the roles of protein‐tyrosine kinases in oxidant stress signaling. The data presented here for wild‐type cells demonstrate that hydrogen peroxide stimulates p53/56lyn‐dependent tyrosine phosphorylation and activation of p72syk, and induces a rapid and prolonged elevation of intracellular calcium, which consists of calcium release from intracellular stores and influx from the extracellular space. Hydrogen‐peroxide‐triggered calcium mobilization was impaired in both syk ‐negative and lyn ‐negative cells, which was mainly due to the loss of calcium release from intracellular stores. Further studies indicated that inositol trisphosphate production was also abolished in both syk ‐negative and lyn ‐negative cells, which is consistent with the loss of calcium release. Taken together, these observations suggest that the defect of p72syk or p53/56lyn was responsible for the abnormality of calcium mobilization in both lyn ‐negative and syk ‐negative cells, and that both p72syk and p53/56lyn might regulate calcium mobilization through the phospha‐tidylinositol pathway in B cell oxidant stress signaling.