Submitted on May 10, 2007
Revised on September 27, 2007
Accepted on October 5, 2007
Remodelling of apolipoprotein E-containing spherical reconstituted high density lipoproteins by phospholipid transfer protein
Nongnuch Settasatian, Philip J. Barter, and Kerry A. Rye
Lipid Research Group, The Heart Research Institute, Camperdown, NSW 2050
Corresponding Author: karye{at}ozemail.com.au
Phospholipid transfer protein (PLTP) transfers phospholipids between HDL and other lipoproteins in plasma. It also remodels spherical, apolipoprotein (apo) A-I-containing HDL into large and small particles in a process involving the dissociation of lipid-free/lipid-poor apoA-I. ApoE is another apolipoprotein that is mostly associated with large, spherical HDL which do not contain apoA-I. Three isoforms of apoE have been identified in human plasma: apoE2, apoE3 and apoE4. This study investigates the remodelling of spherical apoE-containing HDL by PLTP, and the ability of PLTP to transfer phospholipids between apoE-containing HDL and phospholipid vesicles. Spherical reconstituted HDL (rHDL) containing apoA-I, (A-I)rHDL, apoE2, (E2)rHDL, apoE3, (E3)rHDL or apoE4, (E4)rHDL, as the sole apolipoprotein were prepared by incubating discoidal rHDL with low density lipoproteins and lecithin:cholesterol acyltransferase. PLTP remodelled the spherical, apoE-containing rHDL into large and small particles without the dissociation of apoE. The PLTP-mediated remodelling of apoE-containing rHDL was more extensive than that of (A-I)rHDL. PLTP transferred phospholipids from small unilamellar vesicles to apoE-containing rHDL in an isoform-dependent manner, but at a rate slower than that for spherical (A-I)rHDL. It is concluded that apoE enhances the capacity of PLTP to remodel HDL, but reduces the ability of HDL to participate in PLTP-mediated phospholipid transfers.
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