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Mechanism of Sterol Transport by Cyclodextrin
Author(s) -
Xu Zhi,
McCauliff Leslie,
Storch Judith
Publication year - 2010
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.24.1_supplement.691.3
Subject(s) - sterol , membrane , cholesterol , chemistry , biophysics , phospholipid , cyclodextrin , npc1 , biochemistry , biological membrane , filipin , biology , intracellular , endosome
We examined the regulation and mechanism of sterol transport by cyclodextrin(CD) using in vitro model systems and fluorescence spectroscopy, and NPC2‐deficient fibroblasts. We demonstrate that cholesterol transport from the lysosomal cholesterol binding protein‐NPC2, to three different species of CD occurs via aqueous diffusional transfer, which is very slow; the rate limiting step appears to be dissociation of cholesterol from NPC2, suggesting that specific interactions between NPC2 and CD do not occur. In contrast the transfer rate of the fluorescent cholesterol analogue dehydroergosterol(DHE) from CD to phospholipid membranes is very rapid, and is directly proportional to the acceptor membrane concentration; this suggests that sterol transfer from CD to membranes occurs by a collisional transfer mechanism, involving direct interaction of CD with membranes. Marked enhancement of sterol transport by CD was also found in cells, where addition of CD rapidly rescued the cholesterol accumulation phenotype of NPC2‐deficient fibroblasts, as quantified by filipin staining. Thus, the recent observations of CD efficacy in mouse models of NPC disease are likely the result of CD enhancement of cholesterol transport between membranes, with rapid sterol transfer occurring during CD‐membrane interactions. Supported by the Ara Parseghian Medical Research Foundation and the American Heart Association.