Document Detail

Enhancement of the binding of triglyceride-rich lipoproteins to the very low density lipoprotein receptor by apolipoprotein E and lipoprotein lipase.
MedLine Citation:
PMID:  7797576     Owner:  NLM     Status:  MEDLINE    
The low-density lipoprotein (LDL) receptor plays a crucial role in cholesterol metabolism. A related protein, designated the very low density lipoprotein (VLDL) receptor, that specifically binds apolipoprotein (apo) E has recently been characterized and shown to be expressed in heart, muscle and adipose tissue and the human monocyte-macrophage cell line THP-1. The VLDL receptor binds and internalizes VLDL and intermediate density lipoprotein from Watanabe heritable hyperlipidemic (WHHL) rabbits as well as beta-migrating VLDL from cholesterol-fed rabbits but not LDL from WHHL rabbits. Chinese hamster ovary (CHO) cells transfected with the rabbit VLDL receptor cDNA have now been shown to bind or internalize VLDL (d < 1.006 g/ml) isolated from fasted normolipidemic human subjects with lower affinity than WHHL-VLDL or rabbit beta-VLDL. However, binding and internalization were markedly enhanced when fasted human VLDL was preincubated with either recombinant human apoE (3/3) or lipoprotein lipase (LPL) in CHO cells overexpressing the rabbit or human VLDL receptor. CHO cells transfected with both the rabbit VLDL receptor cDNA and the human LPL cDNA effectively bound, internalized, and degraded fasted human VLDL without pretreatment. Treatment of heparinase reduced the effect of LPL-mediated binding at 4 degrees C, but the inhibitory effect was lower at 37 degrees C. Pseudomonas LPL also enhanced the binding of human fasted VLDL to the VLDL receptor at 37 degrees C in CHO cells overexpressing the human VLDL receptor. Taken together, LPL causes the enhancement of triglyceride-rich lipoproteins binding to the VLDL receptor via both the formation of bridge between lipoproteins and heparan sulfate proteoglycans and its lipolytic effect. Ligand blot analysis showed that the apparent molecular mass of the VLDL receptor is 118 kDa, which is smaller than that of the LDL receptor. These results indicate that the VLDL receptor recognizes both triglyceride-rich lipoproteins that are also relatively rich in apoE, as well as the remnants of triglyceride-rich lipoproteins after catabolism and the interaction with heparan sulfate proteoglycans by LPL. The VLDL receptor may thus function as a receptor for remnants of triglyceride-rich lipoproteins in extrahepatic tissues.
S Takahashi; J Suzuki; M Kohno; K Oida; T Tamai; S Miyabo; T Yamamoto; T Nakai
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  270     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1995 Jun 
Date Detail:
Created Date:  1995-08-01     Completed Date:  1995-08-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  15747-54     Citation Subset:  IM    
Third Department of Internal Medicine, Fukui Medical School, Japan.
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MeSH Terms
Apolipoproteins E / physiology*
Cells, Cultured
Lipoprotein Lipase / physiology*
Lipoproteins / metabolism*
Lipoproteins, VLDL / metabolism
Receptors, LDL / metabolism*
Triglycerides / metabolism*
Reg. No./Substance:
0/Apolipoproteins E; 0/Lipoproteins; 0/Lipoproteins, VLDL; 0/Receptors, LDL; 0/Triglycerides; 0/VLDL receptor; EC Lipase

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