Phospholipids mediated conversion of HDLs generates specific apoA-II pre-beta mobility particles.
Apolipoproteins (apo)A-I and A-II are major proteins of human HDL. The cycling of apoA-I between lipid-poor and lipid-rich forms of HDL plays a key role in the transport of cholesterol by these particles. ApoA-II resides only in part of HDL particles, and little is known about its role in HDL metabolism. Our study investigates the redistribution of apoA-II after HDL remodelling induced by exogenous phospholipids (PL). During incubation with egg yolk lecithin (EYL) liposomes, human HDL became PL-enriched and free cholesterol (FC)-depleted, and lost small amounts of apoA-I and apoA-II. The loss of FC and apolipoproteins correlated with the rise of PL content in HDL. Agarose gel electrophoresis demonstrated the appearance of new pre-beta mobility fractions containing apoA-I and apoA-II in liposomes and HDL mixtures. Two-dimensional nondenaturing 2-27% PAGE has shown that the pre-beta mobility fraction that appeared at initial liposome-PL/HDL-PL ratio 5:1 consisted of two distinct heterogeneous subpopulations of particles containing either apoA-I or apoA-II. Our study provides evidence that during HDL conversion mediated by PL apoA-II dissociated from HDL particles yielding apoA-II-specific pre-beta mobility particles. This observation supports the hypothesis that apoA-II in plasma, like apoA-I, may cycle between lipid-poor and lipid-rich forms of HDL.
Wróblewska
Malgorzata
M
Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland. wroblew@amg.gda.pl
Kortas-Stempak
Barbara
B
Szutowicz
Andrzej
A
Badzio
Tadeusz
T
D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism; D016633:Apolipoprotein A-II / Q000378:metabolism*; D053442:High-Density Lipoproteins, Pre-beta / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D054709:Lecithins / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008081:Liposomes; D010316:Particle Size; D010743:Phospholipids / Q000378:metabolism*
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D053442:High-Density Lipoproteins, Pre-beta; D054709:Lecithins; D008075:Lipoproteins, HDL; D008081:Liposomes; D010743:Phospholipids