title: Rapamycin Promotes the Autophagic Degradation of Oxidized Low-Density Lipoprotein in Human Umbilical Vein Endothelial Cells.
abstract: OBJECTIVE
  Oxidized low-density lipoprotein (ox-LDL) has been extensively implicated in the initiation of atherosclerosis. Our previous studies reported that ox-LDL could activate autophagy in human umbilical vein endothelial cells (HUVECs). Because of this, subsequent studies were designed to elucidate the possible role of the autophagic inducer, rapamycin, on ox-LDL degradation in endothelial cells.
  
  
  METHODS
  Intracellular cholesterol content was measured using a tissue total cholesterol assay kit. ox-LDL trafficking within endothelial cells was analyzed by flow cytometry. Levels of proteins involved in the autophagic process, microtubule-associated protein 1 light chain 3 (MAP1-LC3), lysosome-associated membrane protein 1 (LAMP1), Beclin 1 and p62, were assessed by Western blot analysis.
  
  
  RESULTS
  We discovered that rapamycin could decrease the ox-LDL content in HUVECs at the 3-hour time point. Rapamycin also mediated an obvious increase in Dil-labeled ox-LDL (Dil-ox-LDL)/LC3 and Dil-ox-LDL/LAMP1 co-localization, which was inhibited by 3-methyladenine (3-MA), an autophagic inhibitor. In addition, significant co-localization of LC3 and LAMP1 occurred in cells pretreated with rapamycin. In the presence of rapamycin, p62 levels were reduced, and autophagic flux was enhanced.
  
  
  CONCLUSIONS
  These data demonstrate that the activation of the autophagy-lysosome pathway by rapamycin may accelerate ox-LDL degradation.
authors.affiliation: Department of Neurology, Second Affiliated Hospital of Soochow University, Suzhou, China.
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qiao
authors.initials: Q
authors.lastname: Han
authors.forename: Shoujiang
authors.initials: S
authors.lastname: You
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Cao
authors.forename: Xia
authors.initials: X
authors.lastname: Zhang
authors.forename: Huihui
authors.initials: H
authors.lastname: Liu
authors.forename: Lifang
authors.initials: L
authors.lastname: Hu
authors.forename: Chun-Feng
authors.initials: CF
authors.lastname: Liu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D000071186:Beclin-1; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D021381:Protein Transport; D059748:Proteolysis; D000071456:Sequestosome-1 Protein; D020123:Sirolimus / Q000494:pharmacology*; D013997:Time Factors; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D002784:Cholesterol; D008077:Lipoproteins, LDL; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D000071456:Sequestosome-1 Protein; D020123:Sirolimus; C491997:BECN1 protein, human; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C477012:MAP1LC3A protein, human; C099718:SQSTM1 protein, human; C099252:oxidized low density lipoprotein