Involvement of GSK-3β in regulating endoplasmic reticulum stress-mediated apoptosis in Patinopecten yessoensis under high temperature stress

Glycogen synthase kinase-3β (GSK3β), a conserved regulator involved in glycogen metabolism and signal transduction, was identified in Yesso scallop (Patinopecten yessoensis) as PyGSK-3β, containing a conserved S_TKc domain and phosphorylation sites at Ser9 and Tyr216. The gene expression, protein phosphorylation and apoptosis under high temperature (HT) stress were assessed by using quantitative real-time PCR, Western blotting, and immunohistochemistry. PyGSK-3β mRNA was ubiquitously expressed in all the examined tissues and haemocytes. HT stress significantly upregulated the mRNA expression of PyGSK-3β, PyGRP78, PyIRE1, PyJNK, and PyCaspase-3, as well as the phosphorylation level of PyGSK-3β (Tyr216) and PyJNK (Thr183) in gills, and decreased the mRNA expression of PyBCL-2. Furthermore, the GSK-3 inhibitor SB216763 significantly suppressed the mRNA expression of PyGSK-3β, PyGRP78, PyJNK and PyCaspase-3, decreased the phosphorylation level of PyGSK-3β (Tyr216) and PyJNK (Thr183), and reduced HT stress-induced cell apoptosis after HT treatment. However, SB216763 had no effect on the mRNA expression of PyBCL-2. These findings highlight the pivotal role of PyGSK-3β in ER stress-mediated apoptosis and offer insights into scallop high temperature stress adaptation, suggesting its potential as a molecular target for breeding or further functional studies in aquaculture.