Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In kidney epithelial cells, a variety of physiological processes are dependent on the active recycling of membrane proteins between intracellular vesicles and the cell surface. Although clathrin-mediated endocytosis occurs in several renal cell types, endocytosis can also occur by non-clathrin-coated vesicles, including pinocytotic structures known as caveolae that contain a novel coat protein, caveolin. Exo- and endocytosis of a vacuolar H+-ATPase in intercalated cells also occurs via specialized "coated" vesicles that do not contain clathrin. The aim of this study was to localize caveolin in the kidney and, in addition, to determine whether it could be a component of the H+-ATPase recycling process. Using an antibody against the alpha- and beta-isoforms of caveolin-1, our immunocytochemical data show a marked heterogeneity in the cellular expression of this isoform of caveolin in kidney. In contrast, caveolin-3 was not detectable in renal epithelial cells. Caveolin-1 was abundant in endothelial cells and smooth muscle cells and was present in the parietal cells of Bowman's capsule. Distal tubule cells, connecting tubule cells, and collecting duct principal cells exhibited marked punctate basolateral staining, corresponding to the presence of caveolae detected by electron microscopy, whereas all intercalated cells were negative in both cortex and medulla. These data indicate that although caveolin-1 may participate in basolateral events in some kidney epithelial cell types, it does not appear to be involved in the regulated recycling of H+-ATPase in intercalated cells. Therefore, these cells recycle H+-ATPase by a mechanism that involves neither clathrin nor caveolin-1.
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PMID:Basolateral distribution of caveolin-1 in the kidney. Absence from H+-atpase-coated endocytic vesicles in intercalated cells. 944 27

We previously showed that ENaC is present in lipid rafts in A6 cells, a Xenopus kidney cell line. We now demonstrate that ENaC can be detected in lipid rafts in mouse cortical collecting duct ((MPK)CCD(14)) cells by detergent insolubility, buoyancy on density gradients using two distinct approaches, and colocalization with caveolin 1. Less than 30% of ENaC subunits were found in raft fractions. The channel subunits also colocalized on sucrose gradients with known vesicle targeting and fusion proteins syntaxin 1A, Vamp 2, and SNAP23. Hormonal stimulation of ENaC activity by either forskolin or aldosterone, short or long term, did not alter the lipid raft distribution of ENaC. Methyl-beta-cyclodextrin added apically to (MPK)CCD(14) cells resulted in a slow decline in amiloride-sensitive sodium transport with short circuit current reductions of 38.1 +/- 9.6% after 60 min. The slow decline in ENaC activity in response to apical cyclodextrin was identical to the rate of decline seen when protein synthesis was inhibited by cycloheximide. Apical biotinylation of (MPK)CCD(14) cells confirmed the loss of ENaC at the cell surface following cyclodextrin treatment. Acute stimulation of the recycling pool of ENaC was unaffected by apical cyclodextrin application. Expression of dominant negative caveolin isoforms (CAV1-eGFP and CAV3-DGV) which disrupt caveolae, reduced basal ENaC currents by 72.3 and 78.2%, respectively; but, as with cyclodextrin, the acute response to forskolin was unaffected. We conclude that ENaC is present in and regulated by lipid rafts. The data are consistent with a model in which rafts mediate the constitutive apical delivery of ENaC.
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PMID:The epithelial sodium channel (ENaC) traffics to apical membrane in lipid rafts in mouse cortical collecting duct cells. 1793 48