Cholesteryl ester hydrolase activity is abolished in HSL macrophages but unchanged in macrophages lacking KIAA1363[S]
- Marlene Buchebner*,
- Thomas Pfeifer*,
- Nora Rathke*,
- Prakash G. Chandak*,
- Achim Lass§,
- Renate Schreiber§,
- Adelheid Kratzer*,
- Robert Zimmermann§,
- Wolfgang Sattler*,
- Harald Koefeler†,
- Eleonore Fröhlich†,
- Gerhard M. Kostner*,
- Ruth Birner-Gruenberger†,
- Kyle P. Chiang**,
- Guenter Haemmerle§,
- Rudolf Zechner§,
- Sanja Levak-Frank*,
- Benjamin Cravatt** and
- Dagmar Kratky1,*
- *Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
- †Center of Molecular Medicine, and Center for Medical Research, Medical University of Graz, Graz, Austria
- §Institute of Molecular Biosciences, University of Graz, Graz, Austria
- **Skaggs Institute for Chemical Biology and Department of Chemical Physiology, Scripps Research Institute, La Jolla, CA
Abstract
Cholesteryl ester (CE) accumulation in macrophages represents a crucial event during foam cell formation, a hallmark of atherogenesis. Here we investigated the role of two previously described CE hydrolases, hormone-sensitive lipase (HSL) and KIAA1363, in macrophage CE hydrolysis. HSL and KIAA1363 exhibited marked differences in their abilities to hydrolyze CE, triacylglycerol (TG), diacylglycerol (DG), and 2-acetyl monoalkylglycerol ether (AcMAGE), a precursor for biosynthesis of platelet-activating factor (PAF). HSL efficiently cleaved all four substrates, whereas KIAA1363 hydrolyzed only AcMAGE. This contradicts previous studies suggesting that KIAA1363 is a neutral CE hydrolase. Macrophages of KIAA1363−/− and wild-type mice exhibited identical neutral CE hydrolase activity, which was almost abolished in tissues and macrophages of HSL−/− mice. Conversely, AcMAGE hydrolase activity was diminished in macrophages and some tissues of KIAA1363−/− but unchanged in HSL−/− mice. CE turnover was unaffected in macrophages lacking KIAA1363 and HSL, whereas cAMP-dependent cholesterol efflux was influenced by HSL but not by KIAA1363. Despite decreased CE hydrolase activities, HSL−/− macrophages exhibited CE accumulation similar to wild-type (WT) macrophages. We conclude that additional enzymes must exist that cooperate with HSL to regulate CE levels in macrophages. KIAA1363 affects AcMAGE hydrolase activity but is of minor importance as a direct CE hydrolase in macrophages.
Footnotes
-
↵1 To whom correspondence should be addressed. e-mail: dagmar.kratky@medunigraz.at
-
- Abbreviations:
- AcMAGE
- 2-acetyl monoalkylglycerol ether
- apo
- apolipoprotein
- CE
- cholesteryl ester
- CP
- cholesteryl phosphonate
- DG
- diacylglycerol
- FC
- free cholesterol
- HSL
- hormone-sensitive lipase
- LacZ
- β-galactosidase
- MPM
- mouse peritoneal macrophage
- NBD
- 7-nitrobenz-2-oxa-1,3-diazole
- PAF
- platelet-activating factor
- PC
- phosphatidylcholine
- PI
- phosphatidylinositol
- PNPV
- p-nitrophenolvalerate
- TC
- total cholesterol
- TGH
- TG hydrolase
- WT
- wild-type
-
This work was supported by the Austrian Federal Ministry of Science and Research [GEN-AU project Genomics of Lipid-associated Disorders (GOLD)]; the Austrian Science Fund FWF (P19186, SFB-LIPOTOX F30); the Molecular Medicine PhD program at the Medical University of Graz; and the National Institutes of Health (CA-087660). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health or other granting agencies.
-
↵[S] The online version of this article (available at http://www.jlr.org) contains supplementary data in the form of seven figures and one table.
- Received November 23, 2009.
- Revision received July 12, 2010.
- Copyright © 2010 by the American Society for Biochemistry and Molecular Biology, Inc.
Author's Choice—Final version full access.
Creative Commons Attribution Non-Commercial License applies to Author Choice Articles
