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Lp(a) lipoprotein enters cultured fibroblasts independently of the plasma membrane low density lipoprotein receptor
Author(s) -
MaartmannMoe Kjell,
Berg Kare
Publication year - 1981
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.1981.tb01047.x
Subject(s) - lipoprotein , ldl receptor , low density lipoprotein , receptor , low density lipoprotein receptor related protein 8 , plasma lipoprotein , chemistry , lipoprotein(a) , endocrinology , medicine , microbiology and biotechnology , biology , cholesterol , very low density lipoprotein , biochemistry
Lp(a) lipoprotein shares the apoB antigen with low density lipoprotein (LDL). The Lp(a) antigen is unique for Lp(a) lipoprotein. Fibroblast association (i.e. plasma membrane binding plus intracellular accumulation), plasma membrane binding, intracellular accumulation and degradation of 125 I‐Lp(a) lipoprotein were studied in strains from subjects with or without autosomal dominant hypercholesterolemia (HC). Subjects without HC (non‐HCs) have cell surface receptors for low density lipoprotein (LDL receptors). On the average, HC heterozygotes have half‐normal LDL receptor activity and “receptor‐negative” HC homozygous cell strains lack functional receptors. Fibroblast processing of 125 I‐Lp(a) lipoprotein was compared to fibroblast processing of 125 I‐LDL. LDL receptor‐dependent processing of 125 I‐LDL was saturated at about 50 μg apo 125 I‐LDL ml ‐1 in non‐HC fibroblasts. 125 I‐Lp(a) lipoprotein was, however, largely processed independently of receptor mechanisms by non‐HC cells (highest concentration examined 150 μg apo 125 I‐Lp(a) lipoprotein ml ‐1 ). Lp(a) lipoprotein did not interfere with 125 I‐LDL for fibroblast association, but inhibited 125 I‐LDL degradation. The interference with 125 I‐LDL degradation was time dependent Only slightly higher 125 1‐Lp(a) lipoprotein processing values were found in non‐HC and HC heterozygous strains than in “receptor‐negative” HC homozygous strains. However, non‐HC cells had more than tenfold higher 125 I‐LDL processing values than “receptor‐negative” HC homozygous cells.