2020.06.26 Journal club

The nonselective cation channel TRPV4 inhibits angiotensin II receptors

Nicholas W. Zaccor, Charlotte J. Sumner, Solomon H. Snyder

Abstract

G protein-coupled receptors (GPCRs) are a ubiquitously expressed family of receptor proteins that regulate many physiological functions and other proteins. They act through two dissociable signaling pathways, the exchange of GDP to GTP by linked G proteins and the recruitment of β-arrestins. GPCRs modulate several members of the transient receptor potential (TRP) channel family of non-selective cation channels. How TRP channels reciprocally regulate GPCR signaling is less well explored. Here, using an array of biochemical approaches, including immunoprecipitation and -fluorescence, calcium imaging, phosphate radiolabeling, and a β-Arrestin dependent luciferase assay, we characterize a GPCR-TRP channel pair, angiotensin II receptor type 1 (AT1R) and transient receptor potential vanilloid 4 (TRPV4), in primary murine choroid plexus epithelial cells and immortalized cell lines. We found that AT1R and TRPV4 are binding partners, and that activation of AT1R by angiotensin II (ANGII) elicits β-arrestin-dependent inhibition and internalization of TRPV4. Activating TRPV4 with endogenous and synthetic agonists inhibited ANGII-mediated G-protein associated second messenger accumulation, AT1R receptor phosphorylation and β-arrestin recruitment. We also noted that TRPV4 inhibits AT1R phosphorylation by activating the calcium-activated phosphatase calcineurin in a Ca2+/calmodulin dependent manner, preventing β-arrestin recruitment and receptor internalization. These findings suggest that when TRP channels and GPCRs are co-expressed in the same tissues, many of these channels can inhibit GPCR desensitization.