Tyrosine phosphorylation-dependent activation of TRPC6 regulated by PLC-γ1 and nephrin: effect of mutations associated with focal segmental glomerulosclerosis.
Tyrosine phosphorylation-dependent activation of TRPC6 regulated by PLC-γ1 and nephrin: effect of mutations associated with focal segmental glomerulosclerosis.
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DOI：
10.1091/mbc.e10-12-0929
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发表时间：
2011-06-01
影响因子：
3.3
通讯作者：
Hattori S
中科院分区：
文献类型：
--
作者：
Kanda S;Harita Y;Shibagaki Y;Sekine T;Igarashi T;Inoue T;Hattori S
瞬时受体电位典型6（TRPC 6）的表面表达和通道激活受酪氨酸磷酸化及其与刺激性PLC-γ1和抑制性nephrin结合的调节。致病突变使TRPC 6对nephrin抑制不敏感，表明TRPC 6的细胞类型特异性调节可能参与发病机制。瞬时受体电位（TRPC）在细胞内钙离子浓度的调节中起重要作用。TRPC 6基因突变见于局灶节段性肾小球硬化（FSGS）患者，FSGS是一种蛋白尿疾病，其特征是肾小球上皮细胞（足细胞）功能失调。然而，在分子基础上对TRPC 6的激活机制还没有清楚的了解，其通道活性与发病机制之间的关联仍然不清楚。我们在这里证明，TRPC 6的酪氨酸磷酸化诱导与磷脂酶C（PLC）-γ1形成复合物，这是TRPC 6表面表达的先决条件。此外，nephrin是足细胞足突之间的粘附蛋白，通过其胞质结构域与磷酸化的TRPC 6结合，竞争性抑制TRPC 6-PLC-γ1复合物的形成、TRPC 6表面定位和TRPC 6活化。重要的是，FSGS相关突变使突变的TRPC 6对nephrin抑制不敏感，从而促进其表面表达和通道活化。这些结果描述了酪氨酸磷酸化调节TRPC 6激活的机制，并暗示了细胞类型特异性调节，其将FSGS突变与TRPC 6通道活性失调相关。
The surface expression and channel activation of transient receptor potential canonical 6 (TRPC6) were regulated by tyrosine phosphorylation and resultant binding with stimulatory PLC-γ1 and inhibitory nephrin. Disease-causing mutations made the TRPC6s insensitive to nephrin suppression, suggesting that the cell-type–specific regulation of TRPC6 might be involved in the pathogenesis. Transient receptor potential canonicals (TRPCs) play important roles in the regulation of intracellular calcium concentration. Mutations in the TRPC6 gene are found in patients with focal segmental glomerulosclerosis (FSGS), a proteinuric disease characterized by dysregulated function of renal glomerular epithelial cells (podocytes). There is as yet no clear picture for the activation mechanism of TRPC6 at the molecular basis, however, and the association between its channel activity and pathogenesis remains unclear. We demonstrate here that tyrosine phosphorylation of TRPC6 induces a complex formation with phospholipase C (PLC)-γ1, which is prerequisite for TRPC6 surface expression. Furthermore, nephrin, an adhesion protein between the foot processes of podocytes, binds to phosphorylated TRPC6 via its cytoplasmic domain, competitively inhibiting TRPC6–PLC-γ1 complex formation, TRPC6 surface localization, and TRPC6 activation. Importantly, FSGS-associated mutations render the mutated TRPC6s insensitive to nephrin suppression, thereby promoting their surface expression and channel activation. These results delineate the mechanism of TRPC6 activation regulated by tyrosine phosphorylation, and imply the cell type–specific regulation, which correlates the FSGS mutations with deregulated TRPC6 channel activity.