J Biol Chem. 2010 Feb 5;285(6):4213-23. doi: 10.1074/jbc.M109.060301. Epub 2009 Dec 8.
Cell-cell contact formation governs Ca2+ signaling by TRPC4 in the vascular endothelium: evidence for a regulatory TRPC4-beta-catenin interaction.
Graziani, A., Poteser, M., Heupel, W. M., Schleifer, H., Krenn, M., Drenckhahn, D., Romanin, C., Baumgartner, W., Groschner, K.,
["Institute of Pharmaceutical Sciences-Pharmacology and Toxicology, University of Graz, Universitatsplatz 2, 8010 Graz, Austria."]
["Institute of Pharmaceutical Sciences-Pharmacology and Toxicology, University of Graz, Universitatsplatz 2, 8010 Graz, Austria."]
TRPC4 is well recognized as a prominent cation channel in the vascular endothelium, but its contribution to agonist-induced endothelial Ca(2+) entry is still a matter of controversy. Here we report that the cellular targeting and Ca(2+) signaling function of TRPC4 is determined by the state of cell-cell adhesions during endothelial phenotype transitions. TRPC4 surface expression in human microvascular endothelial cells (HMEC-1) increased with the formation of cell-cell contacts. Epidermal growth factor recruited TRPC4 into the plasma membrane of proliferating cells but initiated retrieval of TRPC4 from the plasma membrane in quiescent, barrier-forming cells. Epidermal growth factor-induced Ca(2+) entry was strongly promoted by the formation of cell-cell contacts, and both siRNA and dominant negative knockdown experiments revealed that TRPC4 mediates stimulated Ca(2+) entry exclusively in proliferating clusters that form immature cell-cell contacts. TRPC4 co-precipitated with the junctional proteins beta-catenin and VE-cadherin. Analysis of cellular localization of fluorescent fusion proteins provided further evidence for recruitment of TRPC4 into junctional complexes. Analysis of TRPC4 function in the HEK293 expression system identified beta-catenin as a signaling molecule that enables cell-cell contact-dependent promotion of TRPC4 function. Our results place TRPC4 as a Ca(2+) entry channel that is regulated by cell-cell contact formation and interaction with beta-catenin. TRPC4 is suggested to serve stimulated Ca(2+) entry in a specific endothelial state during the transition from a proliferating to a quiescent phenotype. Thus, TRPC4 may adopt divergent, as yet unappreciated functions in endothelial Ca(2+) homeostasis and emerges as a potential key player in endothelial phenotype switching and tuning of cellular growth factor signaling.
PMID: 19996314

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Screening
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Experimental screening | Non-experimental screening | Reference | ||||||||
TRP channel construct | Interactor source | |||||||||
TRP channel | Interactor | Method | Species | Region | Species | Organ/tissue | Sample type | |||
TRPC4 |
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Ƣ-catenin | Inference | Prediction | 19996314 | |||||
TRPC4 |
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VE-cadherin | Inference | Prediction | 19996314 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

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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 | ||||
TRPC4 |
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Ƣ-catenin | Co-immunoprecipitation | Human microvascular endpthelial cell-1 | Mouse | Full-length | Not specified | Full-length | 19996314 | |
TRPC4 |
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Ƣ-catenin | Co-immunofluorescence staining | HEK293 | Mouse | Full-length | Not specified | Full-length | 19996314 | |
TRPC4 |
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Ƣ-catenin | Fluorescence resonance energy transfer | HEK293 | Mouse | Full-length | Not specified | Full-length | 19996314 | |
TRPC4 |
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VE-cadherin | Co-immunoprecipitation | Human microvascular endpthelial cell-1 | Mouse | Full-length | Mouse | Full-length | 19996314 | |
TRPC4 |
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VE-cadherin | Fluorescence resonance energy transfer | HEK293 | Mouse | Full-length | Mouse | Full-length | 19996314 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

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Functional consequence
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TRP channel | Interactor | Method | Post-translational modification | Subcellular trafficking | Activity | Reference | ||||||
TRPC4 |
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Ƣ-catenin | Calcium measurement | Activation | 19996314 |
(
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
