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Basolateral cholesterol depletion of mpkCCD cells results in ubiquitylation of aquaporin‐2
Author(s) -
Fuglsang Cecilia H,
Fenton Robert A,
Moeller Hanne B
Publication year - 2016
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.30.1_supplement.968.15
Subject(s) - aquaporin 2 , apical membrane , internalization , microbiology and biotechnology , chemistry , aquaporin , phosphorylation , epithelial polarity , vasopressin , endocytosis , ubiquitin , biochemistry , endocrinology , biology , water channel , cell , membrane , mechanical engineering , gene , engineering , inlet
Apical expression of the water channel aquaporin‐2 (AQP2) is regulated by the antidiuretic hormone arginine‐vasopressin (AVP). Post‐translational modifications (PTMs) of the C‐terminal tail of AQP2 mediate AQP2 function by various mechanisms. Ubiquitylation of K270 can mediate apical membrane AQP2 internalization, whereas phosphorylation of AQP2 (at S256 and S269) promotes its apical membrane accumulation. Here, we examined the effect of the cholesterol depleting reagent methyl‐β‐cyclodextrin (MβCD) on AQP2 PTM. The aim was to understand if a specific distribution of AQP2 in the lipid bilayer is involved in its apical membrane accumulation. mpkCCD cells grown on filters and exposed to MβCD from both apical and basolateral sides increased apical expression of AQP2. These effects may be due to inhibition of AQP2 endocytosis. MβCD‐treatment decreased dDAVP induced S269 phosphorylation of AQP2 and dramatically increased ubiquitylation of AQP2. The effects of MβCD on AQP2 ubiquitylation occurred in a dose dependent manner, and only following basolateral and not apical application of MβCD. Basolateral MβCD also decreased AQP2 phosphorylation (S269). Treatment of mpkCCD cells with cAMP increased S269 phosphorylation, whereas this effect was decreased in the presence of basolateral MβCD. In conclusion our data suggest that basolateral cholesterol depletion affects proper regulation of AQP2 trafficking by disturbing PTMs of the protein.