Interaction between PSD 95 and TRPV4 through PDZ Domain Controls TRPV4’s Localization and Activity

Author(s): Eun Jeoung Lee, Kiwol Kim, Otgonnamjil Davaadorj, Sung Hwa Shin, and Sang Sun Kang

The TRPV4 cation channel, is expressed in a broad range of tissues where it participates in generation of Ca2+ signal and/or depolarization of membrane potential. Here, we identified post synaptic density protein 95 (PSD95) as an interacting protein of this epithelial Ca2+ channel using confocal microscopy analysis and immunological assay. Using co-immunoprecipitation assays, we demonstrated that PSD95 was part of the TRPV4 protein complex. PSD95 protein was specifically associated with the C-terminal tail of TRPV4 to form a complex. A TRPV4 tail deletion mutant (ΔDAPL871: 4d) exhibited a diminished capacity to bind PSD95. Confocal microscopy analysis suggested that apical localization of TRPV4 required PSD95–TRPV4 interaction. Our data clearly suggest that formation of a complex between TRPV4 and PSD95 can regulate TRPV4 membrane localization. Both TRPV4 Ca2+ channel and its autophagy activity of 4d were reduced by more than 80% compared to those of the TRPV4 wild type. Our observation suggests that PSD95–TRPV4 complex plays crucial roles in routing TRPV4 to the apical plasma membrane and maintaining its authentic Ca2+ channel and biological function.