title: Rat C-reactive protein causes a charge modification of LDL and stimulates its degradation by macrophages.
abstract: We have previously shown the binding of low-density lipoprotein (LDL) to immobilized rat C-reactive protein (CRP) and the formation of a fluid-phase complex between these two proteins. In this report we used immunoelectrophoresis and agarose gel electrophoresis to show increased anodic migration of the LDL particle as a result of the modification of LDL by rat CRP. The degradation of the modified 125I-LDL by rat peritoneal macrophages was increased more than twofold in the presence of rat CRP. The increase in rat CRP-mediated 125I-LDL degradation by macrophages was dependent on the concentrations of 125I-LDL and rat CRP. This increased 125I-LDL degradation was inhibited by phosphorylcholine. In contrast, the degradation of 125I-acetyl-LDL by macrophages was not affected by rat CRP, although acetylated LDL inhibited the rat CRP-stimulated degradation of 125I-LDL. Increasing concentrations of LDL did not affect the degradation of rat 125I-CRP by the macrophages, which suggested that the rat CRP and the modified LDL did not enter the cell as a complex. Our results suggested that the increased degradation of 125I-LDL was caused by the charge modification of 125I-LDL by rat CRP, due to a fluid-phase complex formation between 125I-LDL and rat CRP, and that the degradation involved the scavenger receptor present on the macrophages.
authors.affiliation: Department of Biochemistry, Memorial University, St John's, Newfoundland, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Mookerjea
authors.forename: J
authors.initials: J
authors.lastname: Francis
authors.forename: D
authors.initials: D
authors.lastname: Hunt
authors.forename: C Y
authors.initials: CY
authors.lastname: Yang
authors.forename: A
authors.initials: A
authors.lastname: Nagpurkar
mesh_terms: D000818:Animals; D002097:C-Reactive Protein / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry; D004587:Electrophoresis, Agar Gel; D007122:Immunoelectrophoresis; D008077:Lipoproteins, LDL / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D009994:Osmolar Concentration; D010767:Phosphorylcholine / Q000494:pharmacology; D051381:Rats
chemical_list: D008077:Lipoproteins, LDL; C032629:acetyl-LDL; D010767:Phosphorylcholine; D002097:C-Reactive Protein