Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz

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"Köpfe" der aktuellen Meldungen:

Nina Höller

Nariae Baik-Schneditz

Bernhard Schwaberger

Lukas Peter Mileder

Niels Hammer

Gerhard Pichler

Roland Malli

Gewählte Publikation:

SHR Neuro Krebs Kardio Lipid Stoffw Microb

Marsche, G; Frank, S; Raynes, JG; Kozarsky, KF; Sattler, W; Malle, E.
The lipidation status of acute-phase protein serum amyloid A determines cholesterol mobilization via scavenger receptor class B, type I.
Biochem J. 2007; 402(1): 117-124. Doi: 10.1042/BJ20061406 [OPEN ACCESS]
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Führende Autor*innen der Med Uni Graz: Malle Ernst; Marsche Gunther
Co-Autor*innen der Med Uni Graz: Frank Sasa; Sattler Wolfgang
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Abstract:: During the acute-phase reaction, SAA (serum amyloid A) replaces apoA-I (apolipoprotein A-I) as the major HDL (high-density lipoprotein)-associated apolipoprotein. A remarkable portion of SAA exists in a lipid-free/lipid-poor form and promotes ABCA1 (ATP-binding cassette transporter A1)-dependent cellular cholesterol efflux. In contrast with lipid-free apoA-I and apoE, lipid-free SAA was recently reported to mobilize SR-BI (scavenger receptor class B, type I)-dependent cellular cholesterol efflux [Van der Westhuyzen, Cai, de Beer and de Beer (2005) J. Biol. Chem. 280, 35890-35895]. This unique property could strongly affect cellular cholesterol mobilization during inflammation. However, in the present study, we show that overexpression of SR-BI in HEK-293 cells (human embryonic kidney cells) (devoid of ABCA1) failed to mobilize cholesterol to lipid-free or lipid-poor SAA. Only reconstituted vesicles containing phospholipids and SAA promoted SR-BI-mediated cholesterol efflux. Cholesterol efflux from HEK-293 and HEK-293[SR-BI] cells to lipid-free and lipid-poor SAA was minimal, while efficient efflux was observed from fibroblasts and CHO cells (Chinese-hamster ovary cells) both expressing functional ABCA1. Overexpression of SR-BI in CHO cells strongly attenuated cholesterol efflux to lipid-free SAA even in the presence of an SR-BI-blocking IgG. This implies that SR-BI attenuates ABCA1-mediated cholesterol efflux in a way that is not dependent on SR-BI-mediated re-uptake of cholesterol. The present in vitro experiments demonstrate that the lipidation status of SAA is a critical factor governing cholesterol acceptor properties of this amphipathic apolipoprotein. In addition, we demonstrate that SAA mediates cellular cholesterol efflux via the ABCA1 and/or SR-BI pathway in a similar way to apoA-I.
Find related publications in this database (using NLM MeSH Indexing): ATP-Binding Cassette Transporters - antagonists and inhibitors; Animals - antagonists and inhibitors; Antigens, CD36 - metabolism; Apolipoprotein A-I - metabolism; CHO Cells - metabolism; Cells, Cultured - metabolism; Cholesterol - metabolism; Cricetinae - metabolism; Cricetulus - metabolism; Humans - metabolism; Lipid Metabolism - metabolism; Lipoproteins, HDL - metabolism; Phospholipids - metabolism; Serum Amyloid A Protein - metabolism; Signal Transduction - metabolism
Find related publications in this database (Keywords): apolipoprotein; ATP-binding cassette transporter A1 (ABCA1); cholesterol; phospholipid; scavenger receptor; serum amyloid A