Suofu Qin’s work on studies of cell survival signaling in cancer and epithelial cells

Figure 3 Proposed model for Syk in mediating oxidative stress-induced calcium release. Phosphorylation of Syk by Lyn and autophosphorylation is required for oxidative stress-induced activation of Syk. How Lyn senses oxidative stress in DT40 cells is currently unknown. Oxidative stress might inhibit tyrosine phosphatase, thereby activating Lyn; Activated Syk phosphorylates phospholipase Cγ2 (PLCγ2) and adaptor protein B cell linker protein (BLNK). Phosphorylated BLNK provides docking sites for PLCγ2 and Btk, enable Btk phosphorylates PLCγ2. Simultaneous phosphorylation of PLCγ2 by Syk and Btk is indispensable for oxidative stress-induced activation of PLCγ2; Activated PLCγ2 cleaves phosphatidylinositol 4,5-biphosphate, releases IP₃, triggering Ca²⁺ release via binding to ryanodine receptor. Oxidative stress also activates PI3K pathway signaling through recruitment of p85 PI3K to the particulate fraction, producing phosphatidylinositol 3,4,5-trisphosphate that targets the activated PLCγ2 to its substrate site for maximal catalytic efficiency.