Hepatic lipase induces the formation of pre-beta 1 high density lipoprotein (HDL) from triacylglycerol-rich HDL2. A study comparing liver perfusion to in vitro incubation with lipases.
High density lipoprotein subfractions with a pre-beta migration play a key role in the reverse cholesterol transport. The origin of these particles is not yet clearly defined. We propose to verify a possible origin of these particles during the catabolism of high density lipoprotein2 (HDL2) by hepatic lipase using two different models. A rat liver perfusion of native human HDL2 in the presence of heparin induced, after 30 min, the formation of the pre-beta 1 HDL subspecies. Human HDL2 enriched with triacylglycerols, perfused in the same conditions, led after 15 min to an enhanced production of this pre-beta 1 HDL population, as compared with the results obtained with native HDL2. A reduction of the alpha-HDL2 fraction was also evident. After perfusion, a similar formation of pre-beta 1 HDL from triacylglycerol-rich HDL2 was observed in absence of heparin. When these HDL2 were incubated in vitro for 120 min at 37 degrees C in the presence of partially purified rat hepatic lipase, the appearance of pre-beta 1 HDL was again found and associated with a decrease in size of the remaining alpha-HDL subfractions as compared with original HDL2. On the contrary, the incubation of the same HDL2 with snake venom phospholipase A2 produced no pre-beta HDL. These results evidence the role of the triacylglycerol lipase activity of hepatic lipase in the formation of pre-beta 1 HDL from triacylglycerol-rich HDL2.
Barrans
A
A
Institut National de la Santé et de la Recherche Médicale, Hopital Purpan, Toulouse, France.
Collet
X
X
Barbaras
R
R
Jaspard
B
B
Manent
J
J
Vieu
C
C
Chap
H
H
Perret
B
B
D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism*; D001711:Biotransformation; D015180:Electrophoresis, Gel, Two-Dimensional; D006493:Heparin / Q000494:pharmacology; D053442:High-Density Lipoproteins, Pre-beta; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000302:isolation & purification / Q000378:metabolism*; D053439:Lipoproteins, HDL2; D008099:Liver / Q000201:enzymology*; D008954:Models, Biological; D010477:Perfusion; D051381:Rats; D014280:Triglycerides / Q000378:metabolism*
D016632:Apolipoprotein A-I; D053442:High-Density Lipoproteins, Pre-beta; D008075:Lipoproteins, HDL; D053439:Lipoproteins, HDL2; D014280:Triglycerides; D006493:Heparin; D008049:Lipase