20-Hydroxyecdysone Affects Hepatopancreatic Vitellogenin Synthesis in Chinese Mitten Crabs (Eriocheir sinensis) Through the PLC-PKC Pathway

In crustaceans, 20-hydroxyecdysone (20E), the primary bioactive form of ecdysteroid hormones, regulates molting and ovarian development. In vivo and in vitro approaches were used to examine the potential nongenomic mechanisms through which 20E modulates ovarian maturation in Chinese mitten crabs (Eriocheir sinensis) and its effects on signaling components and associated genes within the phospholipase C (PLC)-protein kinase C (PKC) pathway. The results demonstrate that the administration of 20E considerably upregulated the hepatopancreatic mRNA expression of G proteins (Gs and Gq), calmodulin-dependent protein kinase II, and inositol 1,4,5-trisphosphate receptors. Concurrent increases in phosphatidylinositol-specific PLC activity were observed, along with elevated levels of its catalytic products (i.e., inositol 1,4,5-trisphosphate and diacylglycerol). Moreover, 20E stimulation activated the phosphorylation and enhanced the transcriptional expression of PKC. Notably, in vitro pharmacological inhibition with U73122 (a PLC inhibitor) and Go6983 (a PKC inhibitor) resulted in the effective suppression of 20E-induced expression of downstream target genes, including the ecdysone receptor (EcR), retinoid X receptor (RXR), vitellogenin (Vg), and Vg receptor (VgR). These findings suggest that 20E modulates hepatopancreatic Vg synthesis in the Chinese mitten crab through PLC-PKC signaling transduction, thereby exerting indirect regulatory effects on ovarian development.