Regulator of G-protein signalling and GoLoco proteins suppress TRPC4 channel function via acting at Gαi/o.
Regulator of G-protein signalling and GoLoco proteins suppress TRPC4 channel function via acting at Gαi/o.
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DOI：
10.1042/bcj20160214
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发表时间：
2016-05-15
期刊：
影响因子：
--
通讯作者：
Zhu MX
中科院分区：
文献类型：
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作者：
Jeon JP;Thakur DP;Tian JB;So I;Zhu MX
瞬时受体电位典型4（TRPC 4）形成涉及多种生理功能调节的非选择性阳离子通道。以前，TRPC 4被证明是由异源三聚体G蛋白的Gi/o亚组激活的，涉及Gαi/o亚基，而不是Gβγ亚基。由于Gα-GTP的寿命和可用性分别通过其GTP酶激活蛋白（GAP）和鸟嘌呤核苷酸解离抑制剂（GDI）功能由G蛋白信号传导（RGS）和Gαi/o-Loco（GoLoco）结构域蛋白的调节剂调节，因此我们测试了RGS和GoLoco结构域蛋白如何影响通过Gi/o偶联受体激活的TRPC 4电流。使用全细胞膜片钳记录，我们发现RGS和GoLoco蛋白[RGS 4，RGS 6，RGS 12，RGS 14，LGN或G蛋白信号传导激活剂3（AGS 3）]抑制受体介导的TRPC 4激活，而不会引起可检测的基础电流或改变通道蛋白的表面表达。抑制作用依赖差距和GoLoco结构域，并通过增强GoLoco蛋白AGS 3的膜靶向来促进。此外，RGS，而不是GoLoco，蛋白加速受体激活诱发的TRPC 4电流的脱敏。RGS和GoLoco结构域的抑制作用是相加的，并且对于含有RGS和GoLoco结构域两者的RGS 12和RGS 14最为突出。我们的数据支持Gi/o信号传导的Gα而不是Gβγ臂参与TRPC 4活化的观点，并揭示了RGS和GoLoco结构域蛋白在微调TRPC 4活性中的新作用。RGS和GoLoco蛋白在调节G蛋白信号传导中的多功能和多样性功能可能是在不同条件下各种细胞类型中受体操作的TRPC 4激活的复杂性的基础。
Transient receptor potential canonical 4 (TRPC4) forms nonselective cation channels implicated in the regulation of diverse physiological functions. Previously, TRPC4 was shown to be activated by the Gi/o subgroup of heterotrimeric G-proteins involving Gαi/o, rather than Gβγ, subunits. Because the lifetime and availability of Gα-GTP are regulated by regulators of G-protein signalling (RGS) and Gαi/o-Loco (GoLoco) domain-containing proteins via their GTPase-activating protein (GAP) and guanine-nucleotide-dissociation inhibitor (GDI) functions respectively, we tested how RGS and GoLoco domain proteins affect TRPC4 currents activated via Gi/o-coupled receptors. Using whole-cell patch-clamp recordings, we show that both RGS and GoLoco proteins [RGS4, RGS6, RGS12, RGS14, LGN or activator of G-protein signalling 3 (AGS3)] suppress receptor-mediated TRPC4 activation without causing detectable basal current or altering surface expression of the channel protein. The inhibitory effects are dependent on the GAP and GoLoco domains and facilitated by enhancing membrane targeting of the GoLoco protein AGS3. In addition, RGS, but not GoLoco, proteins accelerate desensitization of receptor-activation evoked TRPC4 currents. The inhibitory effects of RGS and GoLoco domains are additive and are most prominent with RGS12 and RGS14, which contain both RGS and GoLoco domains. Our data support the notion that the Gα, but not Gβγ, arm of the Gi/o signalling is involved in TRPC4 activation and unveil new roles for RGS and GoLoco domain proteins in fine-tuning TRPC4 activities. The versatile and diverse functions of RGS and GoLoco proteins in regulating G-protein signalling may underlie the complexity of receptor-operated TRPC4 activation in various cell types under different conditions.