Biomaterial Database

Uptake and metabolism of lactosylceramide on low density lipoproteins in cultured proximal tubular cells from normal and familial hypercholesterolemic homozygotes. 1986

S Chatterjee, and K S Clarke, and P O Kwiterovich

The metabolism of low density lipoproteins (LDL), and LDL modified by reductive methylation (M-LDL) of lysine residues, was studied in proximal tubular (PT) cells both from normal human kidney and from urine of patients with homozygous (LDL receptor-negative) familial hypercholesterolemia (FH). LDL and M-LDL was labeled either in the protein moiety with 125I or in the lactosylceramide moiety with 3H. The binding and degradation of 125I-LDL in normal cells was saturable and displaced by unlabeled LDL but not by M-LDL. The uptake of [3H]lactosylceramide (LacCer) low density lipoprotein in normal renal cells was saturable, and time and temperature-dependent. Exogenously derived [3H]LacCer on LDL was rapidly taken up and catabolized to monoglycosylceramide, or it was utilized for the endogenous synthesis of globotriaosylceramide (trihexosylceramide) and globotetraosylceramide (tetraglycosylceramide). [3H]LacCer M-LDL was taken up less avidly and metabolized less extensively than [3H]LacCer-LDL in normal cells. In homozygous FH renal cells the binding of 125I-LDL was not saturable and not displaced by unlabeled LDL. 125I-LDL degradation did not occur in FH cells. The homozygous FH PT cells took up a 2-fold greater amount of exogenously derived [3H]LacCer on LDL than normal cells. Yet, most of the [3H]LacCer taken up by FH PT cells accumulated as LacCer, and only small amounts were metabolized to monoglycosylceramide, globotriaosylceramide (trihexosylceramide), or globotetraosylceramide (tetraglycosylceramide). When normal and FH PT cells were preincubated with LDL (0-100 micrograms/ml medium), there was a 5-fold increase in cellular LacCer levels in FH cells at saturating levels of LDL, whereas there was about a 50% decrease in LacCer levels in normal cells. While the high affinity binding of LDL was not essential for the delivery of LacCer to cells, the data support the conclusion that LDL binding to the LDL receptor facilitates further LacCer processing and metabolism in normal renal cells. We speculate that [3H] LacCer is taken up by FH homozygous cells via a LDL receptor-independent mechanism and accumulates in the cells without significant metabolism. LacCer taken up by this mechanism contributes to the storage of LacCer in FH PT cells.

UI	MeSH Term	Description	Entries
D007457	Iodine Radioisotopes	Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.	Radioisotopes, Iodine
D007687	Kidney Tubules, Proximal	The renal tubule portion that extends from the BOWMAN CAPSULE in the KIDNEY CORTEX into the KIDNEY MEDULLA. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the U-shaped LOOP OF HENLE.	Proximal Kidney Tubule,Proximal Renal Tubule,Kidney Tubule, Proximal,Proximal Kidney Tubules,Proximal Renal Tubules,Renal Tubule, Proximal,Renal Tubules, Proximal,Tubule, Proximal Kidney,Tubule, Proximal Renal,Tubules, Proximal Kidney,Tubules, Proximal Renal
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007790	Lactosylceramides	Glycosphingolipids which contain as their polar head group a lactose moiety bound in glycosidic linkage to the hydroxyl group of ceramide. Their accumulation in tissue, due to a defect in lactosylceramide beta-galactosidase, is the cause of lactosylceramidosis.	Lactosyl Ceramides,Ceramides, Lactosyl
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
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D006028	Glycosphingolipids	Lipids containing at least one monosaccharide residue and either a sphingoid or a ceramide (CERAMIDES). They are subdivided into NEUTRAL GLYCOSPHINGOLIPIDS comprising monoglycosyl- and oligoglycosylsphingoids and monoglycosyl- and oligoglycosylceramides; and ACIDIC GLYCOSPHINGOLIPIDS which comprises sialosylglycosylsphingolipids (GANGLIOSIDES); SULFOGLYCOSPHINGOLIPIDS (formerly known as sulfatides), glycuronoglycosphingolipids, and phospho- and phosphonoglycosphingolipids. (From IUPAC's webpage)	Asialoganglioside,Asialogangliosides,Glycosphingolipid,Sphingoglycolipid,Sphingoglycolipids
D006720	Homozygote	An individual in which both alleles at a given locus are identical.	Homozygotes
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
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