Characterization and functional analysis of GSK3β from Epinephelus coioides in Singapore grouper iridovirus infection

The function of β-catenin and GSK-3β in Procambarus clarkii Wnt signaling pathway during Spiroplasma eriocheiris infection

Wnt signaling pathway plays an important role in both the regulation of host innate immunity and the nervous system. In this study, two key genes in the Wnt signaling pathway, β-catenin and GSK-3β, were first characterized from Procambarus clarkii, and significantly upregulated in hemocytes during Spiroplasma eriocheiris infection. At the cellular level, overexpression of Pcβ-catenin in Drosophila S2 cells significantly increased the cell viability and reactive oxygen species (ROS) production, decreased the cell necrosis and intracellular S. eriocheiris replication, while PcGSK-3β overexpression exerted an opposite effect. The Co-IP results revealed that PcGSK-3β could interact with Pcβ-catenin. Further, co-transfection of PcGSK-3β and Pcβ-catenin into S2 cells markedly reduced the cell survival and ROS level upon S. eriocheiris infection. At the individual level, knockdown of Pcβ-catenin significantly induced the apoptosis of hemocytes and increased the mortality of the crayfish following S. eriocheiris infection. Conversely, PcGSK-3β deficiency significantly elevated the ROS level in hemocytes thereby enhancing the resistance of P. clarkii to S. eriocheiris infection. In conclusion, this study has proved the regulation mechanism of Wnt signaling pathway in response to S. eriocheiris infection, which may contribute to our understanding of innate immunity in invertebrates.

Dual phosphorylation of glycogen synthase kinase 3β differentially integrates metabolic programs to determine T cell immunity across vertebrates

The integration of metabolic programs with T cell signaling establishes a molecular foundation for immune metabolism. As a key metabolic regulator, GSK3β's activity is dynamically modulated by phosphorylation at Ser9 and Tyr216. However, the contribution of these phosphorylation sites on metabolism-driven T cell response remains unclear. Using tilapia and mouse models, we investigated the regulation of GSK3β on T cell metabolism and its evolutionary variation. In tilapia, T cell activation induces GSK3β signaling, linking to both glycolysis and oxidative phosphorylation (OXPHOS). Tyr216 phosphorylation preferentially promotes glycolysis, facilitating T cell activation, proliferation, and antibacterial immunity; while inhibition of Ser9 phosphorylation specifically enhances OXPHOS to sustain T cell responses. Differently, Tyr216 phosphorylation supports both glycolysis and OXPHOS in mouse, ensuring CD4+ T and CD8+ T cell activation, proliferation, and cytokine production. Although Ser9 phosphorylation controls OXPHOS, its inhibition impairs rather than enhances OXPHOS and CD4+ T cell responses in mouse. We thus revealed a previously unknown mechanism underlying T cell metabolism and proposed that, through evolution, GSK3β has restructured the regulatory strategy, enabling bidirectional control of T cell metabolism and immunity in mammals and enhancing the flexibility of the adaptive immune system.