Thromb Haemost 2008; 100(01): 110-118
DOI: 10.1160/TH07-12-0737
Cardiovascular Biology and Cell Signalling
Schattauer GmbH

Potential protective role of apoprotein J (clusterin) in atherogenesis: Binding to enzymatically modified low-density lipoprotein reduces fatty acid-mediated cytotoxicity

Margarethe Schwarz*
1   Institute of Biochemistry
,
Lena Spath*
2   Institute of Medical Microbiology and Hygiene
,
Cornelia A. Lux
,
Kerstin Paprotka
2   Institute of Medical Microbiology and Hygiene
,
Michael Torzewski
3   Institute of Clinical Chemistry and Laboratory Medicine, Johannes Gutenberg-University, Mainz, Germany
,
Katrin Dersch
2   Institute of Medical Microbiology and Hygiene
,
Claudia Koch-Brandt
1   Institute of Biochemistry
,
Matthias Husmann
2   Institute of Medical Microbiology and Hygiene
,
Sucharit Bhakdi
2   Institute of Medical Microbiology and Hygiene
› Author Affiliations

Financial support: This study was supported by the Deutsche Forschungsgemeinschaft (Bh 2/3–5).
Further Information

Publication History

Received 13 December 2007

Accepted after minor revision 14 May 2008

Publication Date:
22 November 2017 (online)

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Summary

Following entrapment in the arterial intima, low-density lipoprotein (LDL) can be modified by hydrolytic enzymes to yield a lipoprotein derivative that binds C-reactive protein, activates complement, and is rapidly taken up by monocytes/macrophages. Free fatty acids contained in enzymatically modified LDL (E-LDL) render the lipoprotein cytotoxic due to their capacity to trigger programmed cell death. Apoprotein J (ApoJ) alias clusterin is a multifunctional glycoprotein with cytoprotective and anti-inflammatory properties. It interacts with diverse substrates, is present in the intima and the media of arteries with atherosclerotic lesions and is also synthesized by smooth muscle cells during development of atherosclerosis. We report that ApoJ binds to E-LDL but not to native LDL. Binding resulted in marked reduction of cytotoxicity of E-LDL on smooth muscle cells, as revealed by determination of caspase activity, annexin binding, and cellular ATP. ApoJ was detected immunohistochemically in early atherosclerotic lesions, where it was found to colocalize with E-LDL. In atherosclerotic lesions, ApoJ may thus subserve protective functions through its capacity to inactivate C5b-9 complement complexes and by reducing the cytotoxic effects of modified LDL on cells that gain contact with the lipoprotein.

* These authors contributed equally to this work.