TRPM2 enhances ischemic excitotoxicity by associating with PKCγ.

N-methyl-D-aspartate receptor (NMDAR)-mediated glutamate excitotoxicity significantly contributes to ischemic neuronal death and post-recanalization infarction expansion. Despite tremendous efforts, targeting NMDARs has proven unsuccessful in clinical trials for mitigating brain injury. Here, we show the discovery of an interaction motif for transient receptor potential melastatin 2 (TRPM2) and protein kinase Cγ (PKCγ) association and demonstrate that TRPM2-PKCγ uncoupling is an effective therapeutic strategy for attenuating NMDAR-mediated excitotoxicity in ischemic stroke. We demonstrate that the TRPM2-PKCγ interaction allows TRPM2-mediated Ca²⁺ influx to promote PKCγ activation, which subsequently enhances TRPM2-induced potentiation of extrasynaptic NMDAR (esNMDAR) activity. By identifying the PKCγ binding motif on TRPM2 (M2PBM), which directly associates with the C2 domain of PKCγ, an interfering peptide (TAT-M2PBM) is developed to disrupt TRPM2-PKCγ interaction without compromising PKCγ function. M2PBM deletion or TRPM2-PKCγ dissociation abolishes both TRPM2-PKCγ and TRPM2-esNMDAR couplings, resulting in reduced excitotoxic neuronal death and attenuated ischemic brain injury. [Display omitted] • TRPM2's PBM directly binds to PKCγ's C2 domain • TRPM2-PKCγ binding promotes the activation of each other • TRPM2-PKCγ coupling enhances ischemic excitotoxicity • Uncoupling TRPM2-PKCγ interaction by TAT-M2PMB mitigates ischemic brain injury Zong et al. reveal that the C2 domain of PKCγ directly interacts with the PBM of TRPM2. The TRPM2-PKCγ interaction not only promotes PKCγ activation but also enhances NMDAR-induced ischemic excitotoxicity during stroke. Uncoupling TRPM2-PKCγ association using a small interfering peptide, TAT-M2PBM, mitigates ischemic brain injury in mice. [ABSTRACT FROM AUTHOR]