Fig. 7.

TRPM7 is required for ROS-induced Zn²⁺ release from intracellular stores. (A–C) Zn²⁺ release from M7Vs was monitored in WT (A and C) or TRPM7^−/− (B and C) HEK293T cells expressing the VIP36-eCALWY4 intravesicular Zn²⁺ sensor. Cells first were incubated with 500 µM Zn²⁺ and then were perfused with 100 µM H₂O₂ in Zn²⁺-free HBT-A containing 250 µM EGTA and 4 mM MgCl₂. WT and TRPM7^−/− cells were compared by Student’s t test; *P < 0.0001, n = 21–39 cells. (D–F) FluoZin-3–loaded WT (D and F) or TRPM7^−/− (E and F) HEK293T cells were similarly loaded with Zn²⁺ and then were treated with H₂O₂ in Zn²⁺-free extracellular medium. The means and SEMs of 44–67 cells are plotted; *P < 0.0001 compared with WT, Student’s t test. (G–I) Experiments were performed as in A–F, but 10 mM sodium dithionite, instead of H₂O₂, was applied to induce Zn²⁺ release from intracellular stores, and glucose was omitted from HBT-A. WT mCherry-TRPM7 was overexpressed to rescue the Zn²⁺ release in TRPM7^−/− cells. The means and SEMs of 8–30 cells are plotted; *P < 0.0001 compared with WT, Student’s t test. a.u., arbitrary units.