Cadmium-induced DAG-PKC/IP3-Ca2+ double signaling pathway and cell injury in gill of freshwater crabs Sinopotamon henanense

Cadmium (Cd) is an extremely toxic heavy metal and widespread in the environment, which has been demonstrated closely associated with numerous organs damage and even death. To evaluate the signaling pathway and the toxicity induced by Cd2+ in aquatic organisms, freshwater crabs Sinopotamon henanense were exposed to Cd2+ (0, 14.5, 29 and 58 mg/L) for 4 d. The results showed that Cd2+ induced the increase of diacylglycerol (DAG) and inositol-1,4,5-triphosphate (IP3), the rapid change of Ca2+ concentration in the cytoplasm and activation of protein kinase C (PKC) in the gill of crab. Also, Cd2+ raised the expressions of 6 genes relating with protein detoxification and folding, including cytochrome P450 (CYP450), BAG regulator 3 (BAG3), protein disulfide isomerase (PDI) and 3 genes encoding heat shock proteins (Hsp21, Hsp27 and Hsp70). And, it was observed that Cd2+ exposure aggravated filament swelling and raised the number of dead epidermal cell in gill. Meanwhile, Cd2+ exposure degraded DNA which was accompanied by an obvious decrease in ATP level. In conclusion, Cd2+ triggered DAG-PKC/IP3-Ca2+ double signaling pathway, caused gene expression, DNA degradation and ATP decrease, and finally induced the cell injury in S. henanense based on histological observation. This study would provide us fundamental information to discover the underlying mechanism of Cd2+-induced cytotoxicity.