Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
J Biol Chem. 2020 Jul 17;295(29):9986-9997. doi: 10.1074/jbc.RA120.014325. Epub 2020 Jun 3.
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 nonselective 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 angiotensin II-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 Ca/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.
G 蛋白偶联受体(GPCRs)是广泛表达的受体蛋白家族,可调节多种生理功能和其他蛋白质。它们通过两种可分离的信号通路发挥作用:与 G 蛋白相连的 GDP 到 GTP 的交换,以及β-arrestin 的募集。GPCR 调节瞬时受体电位(TRP)通道家族的几个成员,这些通道是非选择性阳离子通道。TRP 通道如何相互调节 GPCR 信号尚不清楚。在这里,我们使用一系列生化方法,包括免疫沉淀和荧光、钙成像、磷酸盐放射性标记和β-arrestin 依赖性荧光素酶测定,在原代小鼠脉络丛上皮细胞和永生化细胞系中对 GPCR-TRP 通道对,血管紧张素 II 受体 1(AT1R)和瞬时受体电位香草醛 4(TRPV4)进行了表征。我们发现 AT1R 和 TRPV4 是结合伴侣,血管紧张素 II(ANGII)激活 AT1R 会引发β-arrestin 依赖性 TRPV4 抑制和内化。用内源性和合成激动剂激活 TRPV4 可抑制血管紧张素 II 介导的 G 蛋白偶联第二信使积累、AT1R 受体磷酸化和β-arrestin 募集。我们还注意到,TRPV4 通过以 Ca2+/钙调蛋白依赖的方式激活钙激活磷酸酶钙调神经磷酸酶来抑制 AT1R 磷酸化,从而防止β-arrestin 募集和受体内化。这些发现表明,当 TRP 通道和 GPCR 共同表达在同一组织中时,许多这些通道可以抑制 GPCR 脱敏。