The Wnt/β-catenin signalling pathway regulates ovarian development in the swimming crab Portunus trituberculatus

Wnt/β-catenin signalling regulates many physiological processes in organisms, including development and tissue homeostasis maintenance. Signal transduction in this pathway involves the regulation of its multiprotein complex, which targets β-catenin for proteasomal degradation. The genes encoding the cytoplasmic regulatory proteins β-catenin and GSK-3β in Portunus trituberculatus were successfully cloned and characterized here. Ptβ-catenin was most highly expressed in hemocytes, PtGSK-3β in ovarian tissue, and both genes were significantly upregulated at ovarian stage III, as revealed by quantitative real-time RT-PCR analysis. Continuous injection of the Wnt/β-catenin signalling activator CHIR-98014 resulted in decreased expression of PtGSK-3β, increased expression of Ptβ-catenin, decreased expression of PtVg (vitellogenin) and the content of rPtVn (vitellin). Additionally, it resulted in a significant reduction in both gonadosomatic index (GSI) and oocyte diameter. HE staining revealed diminished vitellogenic granules and the formation of cytoplasmic vacuoles in the oocytes. By contrast, continuous injection ETC-159, a potent inhibitor of Wnt/β-catenin signalling caused increased expression of PtGSK-3β, decreased expression of Ptβ-catenin, increased expression of PtVg and the content of rPtVn. Furthermore, it resulted in an increased GSI, larger oocyte diameter, and HE staining revealed a greater number of yolk granules and a tight arrangement of oocytes. This study elucidates the critical regulatory function of Wnt/β-catenin signaling in P. trituberculatus ovarian development, establishing a foundation for future investigations into the molecular mechanisms governing crustacean reproductive physiology.