TRPV1‐Caveolin 1 direct association and its regulation of NO production: implications for vascular regulation

Abstract

Caveolin‐1 (Cav‐1), a scaffolding protein responsible for the formation of caveolae, is ubiquitously expressed, but predominately in endothelial cells. Moreover, Cav‐1 is known to associate with several ion channels including various Kv and TRP subtypes. It is well established when Cav‐1 and endothelial nitric oxide synthase (eNOS) are bound; Cav‐1 exerts an inhibitory effect on eNOS activity and NO production until a Ca2+ dependent signal untethers the proteins. Our lab and others have shown that TRPV1 regulates eNOS activity and NO production; specifically, via an AKT‐CaMKII‐AMPK signaling cascade. Therefore, we hypothesize that TRPV1, Cav‐1, and eNOS form a protein complex in endothelial cells responsible for the regulation of NO production. Examination of the TRPV1 amino acid sequence revealed 4 potential Cav‐1 binding motifs (where Ø represents any aromatic amino acid and X represents any amino acid): ØXXØXXXXØØ, ØXXØXXXØ, ØXXXØXXØ, and ØXXXØXØ. Using computational modeling we confirmed potential interactions between TRPV1 and Cav‐1. Staining bovine aortic endothelial cells (BAEC) demonstrate TRPV1 and Cav‐1 co‐localization. Further verification of a direct interaction between Cav‐1 and TRPV1 was established using co‐immunoprecipitation. Treatment of BAECs with capsaicin decreased the association between Cav‐1 and eNOS resulting in increased NO production. Interestingly, this treatment also results in the increased complex formation of Cav‐1 with TRPV1. In conclusion, this is the first evidence of a direct interaction between TRPV1 and Cav‐1 and its implications in the regulation of eNOS and vascular function.