Sterol carrier protein-2 (SCP-2) involvement in cholesterol hydroperoxide cytotoxicity as revealed by SCP-2 inhibitor effects. J Lipid Res 2010 Nov;51(11):3174-84
Date
07/27/2010Pubmed ID
20656919Pubmed Central ID
PMC2952558DOI
10.1194/jlr.M008342Scopus ID
2-s2.0-78149304368 (requires institutional sign-in at Scopus site) 23 CitationsAbstract
Sterol carrier protein-2 (SCP-2) plays an important role in cholesterol trafficking and metabolism in mammalian cells. The purpose of this study was to determine whether SCP-2, under oxidative stress conditions, might also traffic hydroperoxides of cholesterol, thereby disseminating their cytotoxic effects. Two inhibitors, SCPI-1 and SCPI-3, known to block cholesterol binding by an insect SCP-2, were used to investigate this. A mouse fibroblast transfectant clone (SC2F) overexpressing SCP-2 was found to be substantially more sensitive to apoptotic killing induced by liposomal 7α-hydroperoxycholesterol (7α-OOH) than a wild-type control. 7α-OOH uptake by SC2F cells and resulting apoptosis were both inhibited by SCPI-1 or SCPI-3 at a subtoxic concentration. Preceding cell death, reactive oxidant accumulation and loss of mitochondrial membrane potential were also strongly inhibited. Similar SCPI protection against 7α-OOH was observed with two other types of SCP-2-expressing mammalian cells. In striking contrast, neither inhibitor had any effect on H(2)O(2)-induced cell killing. To learn whether 7α-OOH cytotoxicity is due to uptake/transport by SCP-2, we used a fluorescence-based competitive binding assay involving recombinant SCP-2, NBD-cholesterol, and SCPI-1/SCPI-3 or 7α-OOH. The results clearly showed that 7α-OOH binds to SCP-2 in SCPI-inhibitable fashion. Our findings suggest that cellular SCP-2 not only binds and translocates cholesterol but also cholesterol hydroperoxides, thus expanding their redox toxicity and signaling ranges under oxidative stress conditions.
Author List
Kriska T, Pilat A, Schmitt JC, Girotti AWAuthors
Albert W. Girotti PhD Adjunct Professor in the Biochemistry department at Medical College of WisconsinTamas Kriska PhD Research Scientist I in the Pharmacology and Toxicology department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AcetanilidesAnimals
Apoptosis
Benzoxazines
Biological Transport
Carrier Proteins
Cell Line
Cholesterol
Humans
Hydrogen Peroxide
Membrane Potential, Mitochondrial
Mice
Rats
Reactive Oxygen Species
Thiazoles
