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ATP-binding cassette A1 protein and HDL homeostasis
1Department of Medicine, Royal Free and University College Medical School, Royal Free Campus, London NW3 2PF, UK. j.owen@rfc.ucl.ac.uk
Insights
High-density lipoprotein (HDL) research lagged until scavenger receptor class B, type I and ATP-binding cassette transporter A1 (ABCA1) were identified. ABCA1 is key for cholesterol efflux and HDL maturation, offering therapeutic potential for cardiovascular disease.
Area of Science:
- Cardiovascular Science
- Molecular Biology
- Biochemistry
Background:
- Low-density lipoprotein (LDL) research overshadowed high-density lipoprotein (HDL) for decades, limiting understanding of HDL's role in cardiovascular disease.
- Knowledge gaps existed regarding HDL receptors and cellular cholesterol efflux mechanisms.
- Atheroprotective HDL's function in removing cholesterol from peripheral cells was poorly understood.
Purpose of the Study:
- To highlight the significance of high-density lipoprotein (HDL) in cholesterol metabolism and atherosclerosis.
- To discuss the identification and importance of key HDL receptors, scavenger receptor class B, type I and ATP-binding cassette transporter A1 (ABCA1).
- To explore the therapeutic potential of targeting ABCA1 for cardiovascular disease treatment.
Main Methods:
- Literature review and synthesis of existing research on HDL metabolism and receptors.
- Focus on the discovery of scavenger receptor class B, type I's role in HDL cholesteryl ester extraction.
- Emphasis on the genetic basis of Tangier disease and the crucial function of ABCA1 in cholesterol efflux.
Main Results:
- Scavenger receptor class B, type I identified as the primary HDL receptor in hepatocytes and steroidogenic tissues.
- Mutations in ATP-binding cassette transporter A1 (ABCA1) gene linked to Tangier disease, characterized by near-absent HDL.
- ABCA1 established as critical for cellular cholesterol efflux and HDL particle formation.
Conclusions:
- ABCA1 is a pivotal protein for cellular cholesterol homeostasis and HDL biogenesis.
- Targeting ABCA1 activity and HDL homeostasis presents a promising therapeutic strategy for cardiovascular disease.
- Modulating ABCA1 may promote cholesterol efflux from foam cells, potentially regressing atherosclerotic lesions.
Abstract:
For three decades, low-density lipoprotein (LDL) dominated research into cholesterol metabolism and atherosclerosis, whereas scant attention was paid to high-density lipoprotein (HDL), an equally important risk factor for cardiovascular disease. This low interest reflected the lack of knowledge about physiological HDL receptors. As a result, our understanding of HDL-cell interactions failed to develop alongside that of LDL, and mechanisms through which atheroprotective HDL promoted clearance of cholesterol from peripheral cells remained poorly-defined. Interest was kindled with the recognition that scavenger receptor class B, type I is the cell-surface protein in hepatocytes and steroidogenic tissues which selectively extracts cholesteryl esters from HDL. Greater impetus still was given by the discovery that mutations in the gene encoding the ATP-binding cassette transporter, class A1 (ABCA1) are the cause of Tangier disease, a rare recessive disorder with near-absent plasma HDL. The ABCA1 transmembrane protein is crucial for efficient efflux of cellular cholesterol and HDL maturation and has emerged as a promising therapeutic target for cardiovascular disease. The hope is that new drugs, regulating ABCA1 activity and HDL homeostasis, will accelerate cholesterol efflux from lipid-laden foam cells and thus promote regression of atherosclerotic lesions.