Structural mechanism of human TRPC3 and TRPC6 channel regulation by their intracellular calcium-binding sites
Structural mechanism of human TRPC3 and TRPC6 channel regulation by their intracellular calcium-binding sites
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DOI：
10.1016/j.neuron.2021.12.023
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发表时间：
2022-03-16
期刊：
影响因子：
16.2
通讯作者：
Chen, Lei
中科院分区：
文献类型：
--
作者：
Guo, Wenjun;Tang, Qinglin;Chen, Lei
TRPC 3和TRPC 6通道是钙渗透性非选择性阳离子通道，参与许多生理过程。TRPC 6的功能获得性（GOF）突变导致人类家族性局灶节段性肾小球硬化症（FSGS），但其致病机制仍不清楚。在这里，我们报告了人TRPC 3在高钙和低钙条件下的冷冻电镜结构。基于这些结构和伴随的电生理学研究，我们确定了TRPC 3中的抑制性和激活性钙结合位点，其将细胞内钙浓度与基础通道活性偶联。这些钙传感器在TRPC 6中也是结构和功能保守的。我们发现TRPC 6的GOF突变通过别构消除细胞内钙的抑制作用来激活通道。此外，与结合在不同配体结合口袋的两种化学上不同的抑制剂复合的人TRPC 6的结构揭示了跨膜结构域的不同构象，为进一步基于结构的靶向TRPC 6相关疾病（如FSGS）的药物设计提供了模板。
TRPC3 and TRPC6 channels are calcium-permeable non-selective cation channels that are involved in many physiological processes. The gain-of-function (GOF) mutations of TRPC6 lead to familial focal segmental glomerulosclerosis (FSGS) in humans, but their pathogenic mechanism remains elusive. Here, we report the cryo-EM structures of human TRPC3 in both high-calcium and low-calcium conditions. Based on these structures and accompanying electrophysiological studies, we identified both inhibitory and activating calcium binding sites in TRPC3 that couple intracellular calcium concentrations to the basal channel activity. These calcium sensors are also structurally and functionally conserved in TRPC6. We uncovered that the GOF mutations of TRPC6 activate the channel by allosterically abolishing the inhibitory effects of intracellular calcium. Furthermore, structures of human TRPC6 in complex with two chemically distinct inhibitors bound at different ligand-binding pockets reveal different conformations of the transmembrane domain, providing templates for further structure-based drug design targeting TRPC6-related diseases such as FSGS.