Arterioscler Thromb Vasc Biol. 2012 Feb;32(2):378-85. doi: 10.1161/ATVBAHA.111.241018. Epub 2011 Dec 8.
The proteoglycan syndecan 4 regulates transient receptor potential canonical 6 channels via RhoA/Rho-associated protein kinase signaling.
Liu, Y., Echtermeyer, F., Thilo, F., Theilmeier, G., Schmidt, A., Schulein, R., Jensen, B. L., Loddenkemper, C., Jankowski, V., Marcussen, N., Gollasch, M., Arendshorst, W. J., Tepel, M.,
["Odense University Hospital and University of Southern Denmark, Institute for Molecular Medicine, Cardiovascular and Renal Research, Institute of Clinical Research, Winslowparken 21.3, DK-5000 Odense C, Denmark."]
["Odense University Hospital and University of Southern Denmark, Institute for Molecular Medicine, Cardiovascular and Renal Research, Institute of Clinical Research, Winslowparken 21.3, DK-5000 Odense C, Denmark."]
OBJECTIVE: Syndecan 4 (Sdc4) modulates signal transduction and regulates activity of protein channels. Sdc4 is essential for the regulation of cellular permeability. We hypothesized that Sdc4 may regulate transient receptor potential canonical 6 (TRPC6) channels, a determinant of glomerular permeability, in a RhoA/Rho-associated protein kinase-dependent manner. METHODS AND RESULTS: Sdc4 knockout (Sdc4(-/-)) mice showed increased glomerular filtration rate and ameliorated albuminuria under baseline conditions and after bovine serum albumin overload (each P<0.05). Using reverse transcription-polymerase chain reaction and immunoblotting, Sdc4(-/-) mice showed reduced TRPC6 mRNA by 79% and TRPC6 protein by 82% (each P<0.05). Sdc4(-/-) mice showed an increased RhoA activity by 87% and increased phosphorylation of ezrin in glomeruli by 48% (each P<0.05). Sdc4 knockdown in cultured podocytes reduced TRPC6 gene expression and reduced the association of TRPC6 with plasma membrane and TRPC6-mediated calcium influx and currents. Sdc4 knockdown inactivated negative regulatory protein Rho GTPase activating protein by 33%, accompanied by a 41% increase in RhoA activity and increased phosphorylation of ezrin (P<0.05). Conversely, overexpression of Sdc4 reduced RhoA activity and increased TRPC6 protein and TRPC6-mediated calcium influx and currents. CONCLUSIONS: Our results establish a previously unknown function of Sdc4 for regulation of TRPC6 channels and support the role of Sdc4 for the regulation of glomerular permeability.
PMID: 22155451
 Screening
Validation: In vitro validation
Validation: In vivo validation
Characterization
Functional consequence
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Validation: In vivo validation
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| Assay with endogenous proteins | Assay with overexpressed proteins | Reference | ||||||||
| Cell or tissue | Cell or tissue | TRP channel construct | Interactor construct | |||||||
| TRP channel | Interactor | Method | Species | Region | Species | Region | ||||
| TRPC6 |
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Nephrin | Co-immunoprecipitation | HEK293 | Mouse | Full-length | Mouse | Full-length | 22155451 | |
| TRPC6 |
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Nephrin | Co-immunoprecipitation | Mouse podocyte lysates | 22155451 | |||||
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