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

Abstract

Cadmium (Cd) which is an extremely toxic heavy metal and widespread in the environment has been 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 a obvious decrease in ATP level, this might be the key reasons causing cell apoptosis and necrosis. In conclusion, Cd2+ triggered DAG-PKC/IP3-Ca2+ double signaling pathway, caused DNA degradation and ATP decrease, and finally induced the cell injury in S.henanense based on histological observation. This study provided more information to know the signaling events underlying Cd2+-induced cytotoxicity.