title: Tyrosine phosphorylation-dependent activation of TRPC6 regulated by PLC-γ1 and nephrin: effect of mutations associated with focal segmental glomerulosclerosis.
abstract: 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.
authors.affiliation: Division of Cellular Proteomics (BML), Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan.
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Kanda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Harita
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Shibagaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Sekine
authors.forename: Takashi
authors.initials: T
authors.lastname: Igarashi
authors.forename: Takafumi
authors.initials: T
authors.lastname: Inoue
authors.forename: Seisuke
authors.initials: S
authors.lastname: Hattori
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D005923:Glomerulosclerosis, Focal Segmental / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D020125:Mutation, Missense; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D051966:Phospholipase C gamma / Q000378:metabolism*; D010766:Phosphorylation; D050199:Podocytes / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D011994:Recombinant Proteins; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000074287:TRPC6 Cation Channel; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C113267:nephrin; D014443:Tyrosine; D019061:src-Family Kinases; D051966:Phospholipase C gamma