Apo A-II participates in HDL-liposome interaction by the formation of new pre-β mobility particles and the modification of liposomes.
Interaction between high density lipoproteins (HDL) and liposomes results in both a structural modification of HDL and the generation of new pre-β HDL-like particles. Here, phosphatidylcholine liposomes and human HDL were incubated at liposomal phospholipid/HDL phospholipid (L-PL/HDL-PL) ratios of 1:1, 3:1 and 5:1 with a subsequent assessment of the distribution of apolipoprotein (apo) A-I, apo A-II, free cholesterol (FC) and PL between newly generated pre-β mobility lipoproteins and non-disrupted liposomes. Both at L-PL/HDL-PL ratios of 3:1 and 5:1 the fraction of liposomal-derived PL associated with pre-β fraction was significantly higher than those accepted by α-HDL. We found that 78% of apo A-I released from HDL was incorporated into pre-β mobility fraction. The relative contents of PL and apo A-I in pre-β fraction were constant irrespective of the initial L-PL/HDL-PL ratio in the incubation mixture and accounted for approximately 83 and 11%, respectively. Apo A-II was detached from HDL to a similar extent as apo A-I and distributed evenly between pre-β fraction and non-disrupted liposomes. Apo A-II constituted approximately 1%, by weight, in these fractions at all L-PL/HDL-PL ratios investigated. It corresponded approximately to 10% of pre-β fraction protein mass. Both liposomes and pre-β fraction accepted comparable amounts of FC released from HDL. This data indicated that during the interaction between human HDL and phosphatidylcholine liposome apo A-II participates both in structural modification of liposomes and in the generation of pre-β mobility fraction of constant content of PL, apo A-I and apo A-II. Involvement of apo A-II in HDL-liposome interaction may influence the anti-atherogenic properties of liposomes.
Wróblewska
Małgorzata
M
Department of Laboratory Medicine, Medical University of Gdańsk, Dębinki 7, 80-211 Gdańsk, Poland. wroblew@amg.gda.pl
Czyżewska
Marta
M
Wolska
Anna
A
Kortas-Stempak
Barbara
B
Szutowicz
Andrzej
A
D016633:Apolipoprotein A-II / Q000502:physiology*; D015153:Blotting, Western; D006801:Humans; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008081:Liposomes
D016633:Apolipoprotein A-II; D008075:Lipoproteins, HDL; D008081:Liposomes