Generation of pre-beta 1-HDL and conversion into alpha-HDL. Evidence for disturbed HDL conversion in Tangier disease.
HDL encompasses several apoA-I-containing particles that differ by size and show pre-beta- or alpha-mobility on agarose gel electrophoresis: pre-beta 1-LpA-I, pre-beta 2-LpA-I, pre-beta 3-LpA-I, alpha-LpA-I2, and alpha-LpA-I3. The quantitatively minor subclass pre-beta 1-LpA-I serves as an initial acceptor of cell-derived cholesterol. In this study, we generated a pre-beta 1-LpA-I-like particle in vitro by the incubation of biotinylated apoA-I with cholesterol-loaded macrophages. Both native pre-beta 1-LpA-I and in vitro-generated pre-beta 1-LpA-I were indistinguishable from lipid-free apoA-I by two-dimensional nondenaturing polyacrylamide gradient gel electrophoresis but exhibited a different size upon gel filtration. In vitro-generated biotin-pre-beta 1-LpA-I took up twofold to threefold more [3H]cholesterol from labeled fibroblasts during a 1-minute pulse incubation than lipid-free apoA-I. The in vitro conversion of biotin-pre-beta 1- LpA-I was investigated in the presence of plasmas of healthy probands and patients with Tangier disease, with apoA-I deficiency, and with lecithin-cholesterol acyltransferase (LCAT) deficiency. Incubation of biotin-pre-beta 1-LpA-I with plasmas either from normoalphalipoproteinemic probands or from a patient with apoA-I deficiency generated a biotinylated particle with the size and electrophoretic mobility of alpha-LpA-I2. This conversion was sensitive to heating at 56 degrees C but not to the removal of calcium. Inhibition of LCAT by dithiobisnitrobenzoic acid led to the formation of alpha-LpA-I3 instead of alpha-LpA-I2.(ABSTRACT TRUNCATED AT 250 WORDS)
Huang
Y
Y
Institut für Arterioskleroseforschung an der Universität Münster, Federal Republic of Germany.
von Eckardstein
A
A
Wu
S
S
Langer
C
C
Assmann
G
G
D000328:Adult; D016632:Apolipoprotein A-I / Q000172:deficiency; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D008297:Male; D013631:Tangier Disease / Q000378:metabolism*
D016632:Apolipoprotein A-I; D008075:Lipoproteins, HDL