Biomaterial Database

Impaired receptor-mediated catabolism of low density lipoprotein in the WHHL rabbit, an animal model of familial hypercholesterolemia. 1982

D W Bilheimer, and Y Watanabe, and T Kita

The homozygous WHHL (Watanabe heritable hyperlipidemic) rabbit displays either no or only minimal low density lipoprotein (LDL) receptor activity on cultured fibroblasts and liver membranes and has therefore been proposed as an animal model for human familial hypercholesterolemia. To assess the impact of this mutation on LDL metabolism in vivo, we performed lipoprotein turnover studies in normal and WHHL rabbits using both native rabbit LDL and chemically modified LDL (i.e., methyl-LDL) that does not bind to LDL receptors. The total fractional catabolic rate (FCR) for LDL in the normal rabbit was 3.5-fold greater than in the WHHL rabbit. Sixty-seven percent of the total FCR for LDL in the normal rabbit was due to LDL receptor-mediated clearance and 33% was attributable to receptor-independent processes; in the WHHL rabbit, essentially all of the LDL was catabolized via receptor-independent processes. Despite a 17.5-fold elevated plasma pool size of LDL apoprotein (apo-LDL) in WHHL as compared to normal rabbits, the receptor-independent FCR-as judged by the turnover of methyl-LDL-was similar in the two strains. Thus, the receptor-independent catabolic processes are not influenced by the mutation affecting the LDL receptor. The WHHL rabbits also exhibited a 5.6-fold increase in the absolute rate of apo-LDL synthesis and catabolism. In absolute terms, the WHHL rabbit cleared 19-fold more apo-LDL via receptor-independent processes than did the normal rabbit and cleared virtually none by the receptor-dependent pathway. These results indicate that the homozygous WHHL rabbit shares a number of metabolic features in common with human familial hypercholesterolemia and should serve as a useful model for the study of altered lipoprotein metabolism associated with receptor abnormalities. We also noted that the in vivo metabolic behavior of human and rabbit LDL in the normal rabbit differed such that the mean total FCR for human LDL was only 64% of the mean total FCR for rabbit LDL, whereas human and rabbit methyl-LDL were cleared at identical rates. Thus, if human LDL and methyl-LDL had been used in these studies, the magnitude of both the total and receptor-dependent FCR would have been underestimated.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008055	Lipids	A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)	Lipid
D008077	Lipoproteins, LDL	A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues.	Low-Density Lipoprotein,Low-Density Lipoproteins,beta-Lipoprotein,beta-Lipoproteins,LDL(1),LDL(2),LDL-1,LDL-2,LDL1,LDL2,Low-Density Lipoprotein 1,Low-Density Lipoprotein 2,LDL Lipoproteins,Lipoprotein, Low-Density,Lipoproteins, Low-Density,Low Density Lipoprotein,Low Density Lipoprotein 1,Low Density Lipoprotein 2,Low Density Lipoproteins,beta Lipoprotein,beta Lipoproteins
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D011973	Receptors, LDL	Receptors on the plasma membrane of nonhepatic cells that specifically bind LDL. The receptors are localized in specialized regions called coated pits. Hypercholesteremia is caused by an allelic genetic defect of three types: 1, receptors do not bind to LDL; 2, there is reduced binding of LDL; and 3, there is normal binding but no internalization of LDL. In consequence, entry of cholesterol esters into the cell is impaired and the intracellular feedback by cholesterol on 3-hydroxy-3-methylglutaryl CoA reductase is lacking.	LDL Receptors,Lipoprotein LDL Receptors,Receptors, Low Density Lipoprotein,LDL Receptor,LDL Receptors, Lipoprotein,Low Density Lipoprotein Receptor,Low Density Lipoprotein Receptors,Receptors, Lipoprotein, LDL,Receptor, LDL,Receptors, Lipoprotein LDL
D004195	Disease Models, Animal	Naturally-occurring or experimentally-induced animal diseases with pathological processes analogous to human diseases.	Animal Disease Model,Animal Disease Models,Disease Model, Animal
D006938	Hyperlipoproteinemia Type II	A group of familial disorders characterized by elevated circulating cholesterol contained in either LOW-DENSITY LIPOPROTEINS alone or also in VERY-LOW-DENSITY LIPOPROTEINS (pre-beta lipoproteins).	Hyperbetalipoproteinemia,Hypercholesterolemia, Essential,Hypercholesterolemia, Familial,Apolipoprotein B-100, Familial Defective,Apolipoprotein B-100, Familial Ligand-Defective,Familial Combined Hyperlipoproteinemia,Hyper-Low Density Lipoproteinemia,Hyper-Low-Density-Lipoproteinemia,Hyper-beta-Lipoproteinemia,Hypercholesterolemia, Autosomal Dominant,Hypercholesterolemia, Autosomal Dominant, Type B,Hypercholesterolemic Xanthomatosis, Familial,Hyperlipoproteinemia Type 2,Hyperlipoproteinemia Type IIa,Hyperlipoproteinemia Type IIb,Hyperlipoproteinemia, Type II,Hyperlipoproteinemia, Type IIa,LDL Receptor Disorder,Apolipoprotein B 100, Familial Defective,Apolipoprotein B 100, Familial Ligand Defective,Autosomal Dominant Hypercholesterolemia,Autosomal Dominant Hypercholesterolemias,Combined Hyperlipoproteinemia, Familial,Combined Hyperlipoproteinemias, Familial,Density Lipoproteinemia, Hyper-Low,Density Lipoproteinemias, Hyper-Low,Disorder, LDL Receptor,Disorders, LDL Receptor,Dominant Hypercholesterolemia, Autosomal,Dominant Hypercholesterolemias, Autosomal,Essential Hypercholesterolemia,Essential Hypercholesterolemias,Familial Combined Hyperlipoproteinemias,Familial Hypercholesterolemia,Familial Hypercholesterolemias,Familial Hypercholesterolemic Xanthomatoses,Familial Hypercholesterolemic Xanthomatosis,Hyper Low Density Lipoproteinemia,Hyper beta Lipoproteinemia,Hyper-Low Density Lipoproteinemias,Hyper-Low-Density-Lipoproteinemias,Hyper-beta-Lipoproteinemias,Hyperbetalipoproteinemias,Hypercholesterolemias, Autosomal Dominant,Hypercholesterolemias, Essential,Hypercholesterolemias, Familial,Hypercholesterolemic Xanthomatoses, Familial,Hyperlipoproteinemia Type 2s,Hyperlipoproteinemia Type IIas,Hyperlipoproteinemia Type IIbs,Hyperlipoproteinemia Type IIs,Hyperlipoproteinemia, Familial Combined,Hyperlipoproteinemias, Familial Combined,Hyperlipoproteinemias, Type II,Hyperlipoproteinemias, Type IIa,LDL Receptor Disorders,Lipoproteinemia, Hyper-Low Density,Lipoproteinemias, Hyper-Low Density,Receptor Disorder, LDL,Receptor Disorders, LDL,Type 2, Hyperlipoproteinemia,Type II Hyperlipoproteinemia,Type II Hyperlipoproteinemias,Type IIa Hyperlipoproteinemia,Type IIa Hyperlipoproteinemias,Xanthomatoses, Familial Hypercholesterolemic,Xanthomatosis, Familial Hypercholesterolemic
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia