Glia. 2005 Feb;49(3):418-29.
Canonical transient receptor potential channel 4 (TRPC4) co-localizes with the scaffolding protein ZO-1 in human fetal astrocytes in culture.
Song, X., Zhao, Y., Narcisse, L., Duffy, H., Kress, Y., Lee, S., Brosnan, C. F.,
["Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA."]
["Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA."]
Members of the mammalian transient receptor potential (TRP) family form cation-permeable channels at the plasma membrane implicated in capacitative calcium influx after activation by either second-messenger-mediated pathways or store depletion, or both. This study shows that with the use of RT-PCR, Western blotting, and immunohistochemistry, resting astrocytes express TRPC4 at the cell membrane, particularly at sites of cell-to-cell contact. By confocal imaging and immunoelectron microscopy, we detected co-localization of TRPC4 with the scaffolding protein zonula occludens 1 (ZO-1), and demonstrated that immunoprecipitation with antibodies to ZO-1 brought down TRPC4, and vice-versa. It has been proposed that the targeting of TRPC4 to the cell membrane is dependent on the interaction of the C-terminal TRL motif with PDZ domains. Using transfection of astrocytes with myc-tagged TRPC4 or TRL-motif truncated TRPC4 (deltaTRL), we found that deltaTRL localized predominantly to a juxtanuclear compartment, whereas the wild-type protein showed cell surface distribution. Deletion of the TRL motif also reduced plasma membrane expression as assessed by cell surface biotinylation experiments. Using GST fusion proteins, we found that TRPC4 interacted with the PDZ1 domain of ZO-1 and that this was also dependent on the TRL motif. Thus, our data demonstrate that the PDZ-interacting domain of TRPC4 controls its cell surface localization. These data implicate TRPC4 in the regulation of calcium homeostasis in astrocytes, particularly as part of a signaling complex that forms at junctional sites between astrocytes.
PMID: 15540229

![]() ![]() ![]() ![]() ![]() |
![]() |
Screening
![]() |
||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Experimental screening | Non-experimental screening | Reference | ||||||||
TRP channel construct | Interactor source | |||||||||
TRP channel | Interactor | Method | Species | Region | Species | Organ/tissue | Sample type | |||
TRPC4 |
![]() |
GJA1 | Inference | Prediction | 15540229 | |||||
TRPC4 |
![]() |
ZO-1 | Inference | Prediction | 15540229 |
(
:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

![]() ![]() ![]() ![]() ![]() |
![]() |
Validation: In vivo validation
![]() |
||||||||||
---|---|---|---|---|---|---|---|---|---|---|
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 |
![]() |
GJA1 | Co-immunofluorescence staining | Human fetal brain astrocytes | 15540229 | |||||
TRPC4 |
![]() |
GJA1 | Co-immunoprecipitation | Human fetal brain astrocytes | 15540229 | |||||
TRPC4 |
![]() |
NHERF1 | Co-immunoprecipitation | Human fetal brain astrocytes | 15540229 | |||||
TRPC4 |
![]() |
ZO-1 | Co-immunofluorescence staining | Human fetal brain astrocytes | 15540229 | |||||
TRPC4 |
![]() |
ZO-1 | Co-immunoprecipitation | Human fetal brain astrocytes | 15540229 |
(
:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

![]() ![]() ![]() ![]() ![]() |
![]() |
Characterization
![]() |
||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Binding region mapping | Stoichiometry | Affinity (Kd) | Reference | |||||||
TRP channel | Interactor | |||||||||
TRP channel | Interactor | Method | Species | Region | Species | Region | ||||
TRPC4 |
![]() |
ZO-1 | Fusion protein-pull down assay | Human | 890-892 | Not specified | First PDZ domain | 15540229 |
(
:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
