PIP2 regulation of TRPC5 channel activation and desensitization

Abstract

Transient receptor potential canonical type 5 (TRPC5) channels are expressed in the brain and kidney, and have been identified as promising therapeutic targets whose selective inhibition can protect against diseases driven by a leaky kidney filter. They are activated by elevated levels of extracellular Ca2+ or application of lanthanide ions but also by G protein (Gq/11) stimulation. Phosphatidylinositol bis-phosphate (PIP2) hydrolysis leads to protein kinase C- (PKC-) mediated phosphorylation of TRPC5 channels and desensitization of their activity. Even though PIP2 regulation of TRP channels is being widely studied, the roles of PIP2 in maintaining TRPC5 channel activity, the PIP2 involvement in channel stimulation by its hydrolysis product diacyl glycerol (DAG), or the desensitization of activity by DAG-stimulated PKC activity remain unclear. Here, we show that PIP2 controls both the PKC-mediated inhibition of TRPC5 currents as well as the activation by DAG and lanthanides and that it accomplishes this through control of gating rather than channel cell surface density. The mechanistic insights achieved by the present work promise to aid in the development of more selective and precise molecules to block TRPC5 channel activity and illuminate new therapeutic opportunities for targeted therapies for a group of diseases for which there is currently a great unmet need.