title: A new recombinant human apolipoprotein E mimetic peptide with high-density lipoprotein binding and function enhancing activity.
abstract: We generated a novel human apolipoprotein E (apoE)-mimetic peptide, designated EpK. EpK contains an N-terminal cysteine residue, a low-density lipoprotein receptor-binding fragment, a 6 × lysine linker and a lipid-binding fragment. The recombinant peptide was expressed in Escherichia coli, and purified with a chitin bead column followed by a Heparin Sepharose CL-6B column to yield pure peptide. EpK displayed high solubility in aqueous solution at neutral pH and adopted a low content of α-helical structure which was significantly increased in 2,2,2-trifluoroethanol or upon lipid binding. EpK retained similar 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine binding activity as human apoE3 albeit with slower kinetics. Cell culture studies showed that EpK mediated cholesterol efflux from cholesterol-loaded primary murine macrophages with higher mass-based efficiency than human apoAI and human apoE3, and that EpK inhibited lipopolysaccharide (LPS)-induced proinflammatory cytokine expression in murine macrophages. When injected into apoE(-/-)mice, EpK predominantly associated with high-density lipoprotein (HDL), which was also shown in in vitro incubation experiments. Moreover, association of EpK with HDL enhanced the ability of HDL in mediating cholesterol efflux and suppressing LPS-induced proinflammatory cytokine expression in cholesterol-loaded human acute monocytic leukemia cell line (THP-1) macrophages. These data suggest that this novel recombinant apoE mimetic peptide enhances HDL function and harbors antiatherogenic potential.
authors.affiliation: Department of Cell Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC 29209,  USA.
authors.forename: Wentao
authors.initials: W
authors.lastname: Zhao
authors.forename: Fen
authors.initials: F
authors.lastname: Du
authors.forename: Michelle
authors.initials: M
authors.lastname: Zhang
authors.forename: Shengfang
authors.initials: S
authors.lastname: Sun
authors.forename: Hong
authors.initials: H
authors.lastname: Yu
authors.forename: Daping
authors.initials: D
authors.lastname: Fan
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050197:Atherosclerosis / Q000517:prevention & control; D001665:Binding Sites; D002460:Cell Line; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D015202:Protein Engineering; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001057:Apolipoproteins E; D008075:Lipoproteins, HDL; D011994:Recombinant Proteins