J Biol Chem. 2003 Dec 19;278(51):51448-53. Epub 2003 Sep 28.
Microtubule-associated [corrected] protein 7 increases the membrane expression of transient receptor potential vanilloid 4 (TRPV4).
Suzuki, M., Hirao, A., Mizuno, A.,
["Department of Pharmacology, Jichi Medical School 3311-1, Yakushiji, Minamikawachi, Tochigi, 329-0498, Japan. macsuz@jichi.ac.jp"]
["Department of Pharmacology, Jichi Medical School 3311-1, Yakushiji, Minamikawachi, Tochigi, 329-0498, Japan. macsuz@jichi.ac.jp"]
The molecular mechanism of the transmission of changes in the shape of the cell surface to ion channels remains obscure. Ca2+ influx induced by cell deformity is inhibited by actin-freezing reagents, suggesting that the actin microfilament couples with an ion channel. Transient receptor potential vanilloid 4 (TRPV4) is a candidate in the calcium-permeable, swelling-activated mechanosensitive channel in heterogeneously expressed cells. To investigate the mechanosensitive molecular complex, we found that microtubule-associated protein 7 (MAP7) is the mouse TRPV4 C-terminal binding protein. MAP7 was coimmunoprecipitated with TRPV4. The results of a pull-down assay demonstrated that the alignment of amino acids 798-809 of TRPV4 was important in this interaction. TRPV4 and MAP7 colocalized in the lung and kidney. The coexpression of these two molecules resulted in the redistribution of TRPV4 toward the membrane and increased its functional expression. The alignment of amino acids 798-809 of TRPV4 was also important in the functional expression. The activated current was abolished by actin-freezing but not by microtubule-freezing reagents. We therefore believe that MAP7 may enhance the membrane expression of TRPV4 and possibly link cytoskeletal microfilaments.
PMID: 14517216

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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 | |||
TRPV4 |
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MAP7 | Yeast two-hybrid | Mouse | 783-871 | Mouse | Kidney | cDNA library | 14517216 |
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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 vitro validation
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Assay with recombinant proteins | Reference | |||||||||
TRP channel construct | Interactor construct | |||||||||
TRP channel | Interactor | Method | Species | Region | Expression system | Species | Region | Expression system | ||
TRPV4 |
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MAP7 | Fusion protein-pull down assay | Mouse | Full-length | HEK293 lysates | Mouse | Full-length | In vitro translation | 14517216 |
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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 | ||||
TRPV4 |
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MAP7 | Co-immunoprecipitation | Mouse renal tissue | 14517216 | |||||
TRPV4 |
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MAP7 | Co-immunoprecipitation | HEK293 | Mouse | 785-808 | Mouse | Full-length | 14517216 | |
TRPV4 |
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MAP7 | Co-immunofluorescence staining | Mouse lung section | 14517216 | |||||
TRPV4 |
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MAP7 | Co-immunofluorescence staining | Mouse kidney section | 14517216 | |||||
TRPV4 |
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MAP7 | Co-immunofluorescence staining | HEK293 | Mouse | Full-length | Mouse | Full-length | 14517216 |
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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 | ||||||
TRPV4 |
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MAP7 | Cell surface biotinylation | Increase in plasma membrane level | 14517216 | |||||||
TRPV4 |
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MAP7 | Patch clamp | Activation | 14517216 |
(
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
