title: Human carotid plaque phosphatidylcholine specifically interacts with paraoxonase 1, increases its activity, and enhances its uptake by macrophage at the expense of its binding to HDL.
abstract: Human carotid atherosclerotic plaque is in direct contact with circulatory blood components. Thus, plaque and blood components may affect each other. The current study presents the effects of plaque chloroform:methanol (C:M) extract on the HDL-associated enzyme paraoxnase 1 (PON1). This study is part of our investigation on the mutual effects of the interactions between atherosclerotic lesions and blood components. Recombinant PON1 (rePON1) was incubated with the human carotid plaques C:M extract and PON1 activities were analyzed. Lactonase and paraoxonase activities were elevated due to C:M treatment, by 140 and by 69%, respectively. Analytical chemistry analyses revealed specific phosphatidylcholines (PCs) as the plaque active components. Tryptophan fluorescence quenching assay, together with molecular docking, shows that PON1 activity is enhanced in correlation with the level of PC affinity to PON1. Molecular docking revealed that PCs interact specifically with H2-PON1 α-helix, which together with H1 enzyme α-helix links the protein to the HDL surface. These findings are supported by additional results from the PON1 ∆20 mutant that lack its H1-α-helix. Incubation of this mutant with the plaque C:M extract increased PON1 activity by only 20%, much less than the wild-type PON1 that elevated PON1 activity at the same concentration by as much as 95%. Furthermore, as much as the affinity of the enzyme to the PC was augmented, the ability of PON1 to bind to the HDL particle decreased. Finally, PON1 interaction with PC enhance its uptake into the macrophage cytoplasm. In conclusions, Specific lesion phosphatidylcholines (PCs) present in the human carotid plaque significantly enhance PON1 catalytic activities due to their interaction with the enzyme. Such a lesion׳s PC-PON1 interaction, in turn, competes with HDL PCs and enhances PON1 uptake by macrophage at the expense of PON1 binding to the HDL.
authors.affiliation: Department of Oxidative Stress and Human Diseases, MIGAL-Galilee Research Institute, P.O. Box 831, Kiryat Shmona 11016, and Tel Hai College, Israel; Rappaport Family Institute for Research in the Medical Sciences, Rambam Medical Center, Haifa 31096, Israel.
authors.forename: Elad
authors.initials: E
authors.lastname: Cohen
authors.affiliation: Rappaport Family Institute for Research in the Medical Sciences, Rambam Medical Center, Haifa 31096, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Aviram
authors.affiliation: Department of Oxidative Stress and Human Diseases, MIGAL-Galilee Research Institute, P.O. Box 831, Kiryat Shmona 11016, and Tel Hai College, Israel.
authors.forename: Soliman
authors.initials: S
authors.lastname: Khatib
authors.affiliation: Department of Oxidative Stress and Human Diseases, MIGAL-Galilee Research Institute, P.O. Box 831, Kiryat Shmona 11016, and Tel Hai College, Israel.
authors.forename: Fadi
authors.initials: F
authors.lastname: Artoul
authors.affiliation: Department of Vascular Surgery, Carmel Medical Center, Haifa, Israel.
authors.forename: Asaf
authors.initials: A
authors.lastname: Rabin
authors.affiliation: Department of Vascular Surgery, Carmel Medical Center, Haifa, Israel.
authors.forename: Dalit
authors.initials: D
authors.lastname: Mannheim
authors.affiliation: Department of Vascular Surgery, Carmel Medical Center, Haifa, Israel.
authors.forename: Ron
authors.initials: R
authors.lastname: Karmeli
authors.affiliation: Vascular Surgery Unit, Ziv Medical center, Zefat, Israel.
authors.forename: Tal
authors.initials: T
authors.lastname: Salamon
authors.affiliation: Department of Oxidative Stress and Human Diseases, MIGAL-Galilee Research Institute, P.O. Box 831, Kiryat Shmona 11016, and Tel Hai College, Israel. Electronic address: vaya@migal.org.il.
authors.forename: Jacob
authors.initials: J
authors.lastname: Vaya
mesh_terms: D043303:Aryldialkylphosphatase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002339:Carotid Arteries / Q000378:metabolism* / Q000473:pathology; D002853:Chromatography, Liquid; D005230:Fatty Acids, Nonesterified; D006801:Humans; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D062105:Molecular Docking Simulation; D009154:Mutation / Q000235:genetics; D010713:Phosphatidylcholines / Q000378:metabolism*; D058226:Plaque, Atherosclerotic / Q000378:metabolism* / Q000473:pathology; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D005230:Fatty Acids, Nonesterified; D008075:Lipoproteins, HDL; D010713:Phosphatidylcholines; D011994:Recombinant Proteins; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human
keywords: Atherosclerosisl; Human carotid plaque; Macrophage; Paraoxonase 1 (PON1); Phosphatidylcholine