Neutrophil association and degradation of normal and acute-phase high-density lipoprotein 3
Date
1987
Authors
Shephard E.G.
De Beer F.C.
De Beer M.C.
Jeenah M.S.
Coetzee G.A.
Van Der Westhuyzen D.R.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The interaction of normal and acute-phase high-density lipoproteins of the subclass 3 (N-HDL3 and AP-HDL3) with human neutrophils and the accompanying degradation of HDL3 apolipoproteins have been studied in vitro. The chemical composition of normal and acute-phase HDL3 was similar except that serum amyloid A protein (apo-SAA) was a major apolipoprotein in AP-HDL3 (approx. 30% of total apolipoproteins). 125I-labelled AP-HDL3 was degraded 5-10 times faster than 125I-labelled N-HDL3 during incubation with neutrophils or neutrophil-conditioned medium. Apo-SAA, like apolipoprotein A-II (apo-A-II), was more susceptible than apolipoprotein A-I (apo-A-I) to the action of proteases released from the cells. The amounts of cell-associated AP-HDL3 apolipoproteins at saturation were up to 2.8 times greater than N-HDL3 apolipoproteins; while apo-A-I was the major cell-associated apolipoprotein when N-HDL3 was bound, apo-SAA constituted 80% of the apolipoproteins bound in the case of AP-HDL3. The associated intact apo-SAA was mostly surface-bound as it was accessible to the action of exogenous trypsin. α1-Antitrypsin-resistant (α1-AT-resistant) cellular degradation of AP-HDL3 apolipoproteins also occurred; experiments in which pulse-chase labelling was performed or lysosomotropic agents were used indicated that significant intracellular degradation occurred which points to the involvement of cell-surface proteases in this degradation.
Description
Keywords
alpha 1 antitrypsin, apolipoprotein, high density lipoprotein, human, human cell, neutrophil, Acute-Phase Proteins, Apolipoproteins, Cells, Cultured, Electrophoresis, Polyacrylamide Gel, Human, Lipids, Lipoproteins, HDL, Neutrophils, Peptide Hydrolases, Proteins, Support, Non-U.S. Gov't
Citation
Biochemical Journal
248
3
248
3