GSK-3β/β-TrCP regulates Nrf2-mediated oxidative stress response in Cristaria plicata

Summary: Nuclear factor erythroid 2-related factor 2 (Nrf2) orchestrates antioxidant and cytoprotective responses. Beyond classical Keap1-dependent redox regulation, Nrf2 activation can occur via the GSK-3β/β-TrCP pathway during Keap1 inhibition. This study investigated this non-canonical pathway in the stress adaptation of the bivalve (Cristaria plicata). We found that the CpGSK-3β and Cpβ-TrCP genes underwent significant changes in the hepatopancreas, gills, and kidneys after immune (LPS, PGN, Poly(I:C)) or oxidative (H2O2) challenges. Knockdown of either gene increased Nrf2 and NQO1 expression. Protein interaction assays confirmed CpGSK-3β/Cpβ-TrCP binding to the Neh6 domain of CpNrf2, with CpGSK-3β phosphorylating this domain in vitro. Overexpression enhanced cellular resistance to H2O2. These findings reveal the conserved physiological significance of the GSK-3β/β-TrCP-Nrf2 axis in molluscan stress responses, providing new insights into redox regulation mechanisms in invertebrates and potential biomarkers for aquatic environmental stress assessment.