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Regulation of ENaC by Cholesterol: Role of Microvilli and PIP 2
Author(s) -
Ma He-Ping
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1068.3
Subject(s) - epithelial sodium channel , apical membrane , chemistry , chinese hamster ovary cell , microbiology and biotechnology , cell membrane , cell , biophysics , sodium , membrane , biochemistry , biology , receptor , organic chemistry
We previously showed that cholesterol (Cho) stimulates the renal epithelial sodium channel (ENaC). However, the underlying mechanism remains unclear. Using the cell‐attached configuration, we found that depletion of Cho in the outer leaflet of A6 cell apical membrane with methyl‐β‐cyclodextrin (MβCD) reduced the number of ENaC, which is consistent with the data from immunohistochemical staining and biotinylation of ENaC. Atomic force microscopy scanning of A6 cell apical membrane showed that MβCD induced destruction of microvilli. These data indicate that depletion of Cho reduces the number of ENaC probably by causing destruction of microvilli. Further, confocal microscopy data showed that ENaC is co‐localized with both Cho and PI(4,5)P 2 in the microvilli and that depletion of Cho reduced PI(4,5)P 2 . In inside‐out patches, MβCD significantly reduced ENaC open probability (P O ); the effect was reversed by Cho. However, MβCD and Cho failed to regulate ENaC when PI(4,5)P 2 is sequestered with its antibody. Since ENaC is mainly located in microvilli and stimulated by PI(4,5)P 2 , these data suggest that depletion of Cho reduces ENaC density via destruction of microvilli and decreases ENaC P O via reduction of PI(4,5)P 2 .