title: Rapamycin Inhibits Oxidized Low Density Lipoprotein Uptake in Human Umbilical Vein Endothelial Cells via mTOR/NF-κB/LOX-1 Pathway.
abstract: BACKGROUND
  Lectin-like oxidized low-density lipoprotein-1 (LOX-1) is the major receptor for oxidized low density lipoprotein (ox-LDL) uptake in human umbilical vein endothelial cells (HUVECs). Previously, we found that rapamycin inhibited ox-LDL accumulation in HUVECs, and this effect was related to its role in increasing the activity of autophagy-lysosome pathway. In this study, we determined whether rapamycin could also reduce ox-LDL uptake in HUVECs and investigated the underlying signaling mechanisms.
  
  
  RESULTS
  Flow cytometry and live cell imaging showed that rapamycin reduced Dil-ox-LDL accumulation in HUVECs. Furthermore, rapamycin reduced the ox-LDL-induced increase in LOX-1 mRNA and protein levels. Western blotting showed that rapamycin inhibited mechanistic target of rapamycin (mTOR), p70s6k and IκBα phosphorylation triggered by ox-LDL. Flow cytometry implied that mTOR, NF-κB knockdown and NF-κB inhibitors significantly reduced Dil-ox-LDL uptake. Moreover, immunofluorescent staining showed that rapamycin reduced the accumulation of p65 in the nucleus after ox-LDL treatment for 30 h. mTOR knockdown decreased LOX-1 protein production and IκBα phosphorylation induced by ox-LDL. NF-κB knockdown and NF-κB inhibitors reduced LOX-1 protein production, but did not inhibit mTOR phosphorylation stimulated by ox-LDL.
  
  
  CONCLUSIONS
  These findings demonstrate that rapamycin reduce mTOR phosphorylation and subsequently inhibit NF-κB activation and suppresses LOX-1, resulting in a reduction in ox-LDL uptake in HUVECs.
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
authors.forename: Yan-De
authors.initials: YD
authors.lastname: Zhou
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
authors.forename: Xue-Qin
authors.initials: XQ
authors.lastname: Cao
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
authors.forename: Zhi-Hua
authors.initials: ZH
authors.lastname: Liu
authors.affiliation: Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Cao
authors.affiliation: Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.|Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, China.
authors.forename: Chun-Feng
authors.initials: CF
authors.lastname: Liu
authors.affiliation: Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
authors.forename: Yan-Lin
authors.initials: YL
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xie
mesh_terms: D050197:Atherosclerosis / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D018450:Disease Progression; D015971:Gene Expression Regulation, Enzymologic; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000493:pharmacokinetics*; D008247:Lysosomes / Q000378:metabolism; D052002:NF-kappa B p50 Subunit / Q000378:metabolism*; D010766:Phosphorylation; D051127:Scavenger Receptors, Class E / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014162:Transfection
chemical_list: D007166:Immunosuppressive Agents; D008077:Lipoproteins, LDL; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; C495137:OLR1 protein, human; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus