Evidence for transient receptor potential cation channel 1 (TRPV1) association with caveolin-1 and -2

초록

The transient receptor potential cation channel, subfamily V, member 1 (TRPV1; also known as the vanilloid receptor, VR1), is a ligand-gated cation channel localized mainly in a subset of sensory (nociceptive) neurons. The receptor can be activated by vanilloids such as capsaicin and its ultrapotent analog, resiniferatoxin. Besides such exogenous factors, endogenous stimuli such as low-threshold heat, acidosis, bradykinin, eicosanoids, and other arachidonic acid derivatives may also act on TRPV1. Caveolins are integral membrane proteins present in caveolae, the small flask-shaped and detergent insoluble invaginations in plasma membrane and are implicated to function in the vesicular transport processes and the transduction of receptor generated signals. Recent studies have shown that many receptor, signal proteins and enzymes are localized in the caveolae by being anchored through caveolins. The purse of this study was to investigate the relationship between TRPV1 and caveolins. As the first step for this study, we cloned rat TRPV1 using RT-PCR. This PCR product was subcloned in eukaryotic expression vector, pcDNA 3.1 (+) and transfected to Chinese hamster ovary cells or C6 rat glioma cells. After selection with geneticin, we have checked the expression of TRPV1 gene and protein using RT-PCR and Western blot analysis. Cells had expressions of mRNA and protein of TRPV1. To clarify the association of caveolin and TRPV1, Western blot analysis was performed using isolated caveolae. Caveolin-1, -2 and TRPV1 were located in caveolae (fraction number 5). For the direct evidence of association between TRPV1 and caveolin, immunoprecipitaion result showed TRPV1 was bound to caveolin-1 and -2. In addition, the immunocytochemistry data also support these results. From these results, TRPV1 was associated with caveolins and the further study on functional regulation of caveolins over the function of TRPV1 should be needed.