GPIHBP1 and lipolysis: an update.
OBJECTIVE
This review will provide an update on the structure of GPIHBP1, a 28-kDa glycosylphosphatidylinositol-anchored glycoprotein, and its role in the lipolytic processing of triglyceride-rich lipoproteins.


RESULTS
Gpihbp1 knockout mice on a chow diet have milky plasma and plasma triglyceride levels of more than 3000 mg/dl. GPIHBP1 is located on the luminal surface of endothelial cells in tissues where lipolysis occurs: heart, skeletal muscle, and adipose tissue. The pattern of lipoprotein lipase (LPL) release into the plasma after an intravenous injection of heparin is abnormal in Gpihbp1-deficient mice, suggesting that GPIHBP1 plays a direct role in binding LPL within the tissues of mice. Transfection of CHO cells with a GPIHBP1 expression vector confers on cells the ability to bind both LPL and chylomicrons. Two regions of GPIHBP1 are required for the binding of LPL - an amino-terminal acidic domain and the cysteine-rich Ly6 domain. GPIHBP1 expression in mice changes with fasting and refeeding and is regulated in part by peroxisome proliferator-activated receptor-gamma.


CONCLUSIONS
GPIHBP1, an endothelial cell-surface glycoprotein, binds LPL and is required for the lipolytic processing of triglyceride-rich lipoproteins.
Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA. abeigneux@mednet.ucla.edu
Anne P
AP
Beigneux
Michael M
MM
Weinstein
Brandon S J
BS
Davies
Peter
P
Gin
André
A
Bensadoun
Loren G
LG
Fong
Stephen G
SG
Young
D000818:Animals; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006949:Hyperlipidemias / Q000378:metabolism; D008066:Lipolysis; D008071:Lipoprotein Lipase / Q000378:metabolism; D017434:Protein Structure, Tertiary; D018110:Receptors, Lipoprotein / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism
C472779:GPI-HBP1 protein, mouse; D006023:Glycoproteins; D018110:Receptors, Lipoprotein; D008071:Lipoprotein Lipase