title: Homocysteine promotes human endothelial cell dysfunction via site-specific epigenetic regulation of p66shc.
abstract: OBJECTIVE
  Hyperhomocysteinaemia is an independent risk factor for atherosclerotic vascular disease and is associated with vascular endothelial dysfunction. Homocysteine modulates cellular methylation reactions. P66shc is a protein that promotes oxidative stress whose expression is governed by promoter methylation. We asked if homocysteine induces endothelial p66shc expression via hypomethylation of CpG dinucleotides in the p66shc promoter, and whether p66shc mediates homocysteine-stimulated endothelial cell dysfunction.
  
  
  RESULTS
  Homocysteine stimulates p66shc transcription in human endothelial cells and hypomethylates specific CpG dinucleotides in the human p66shc promoter. Knockdown of p66shc inhibits the increase in reactive oxygen species, and decrease in nitric oxide, elicited by homocysteine in endothelial cells and prevents homocysteine-induced up-regulation of endothelial intercellular adhesion molecule-1. In addition, knockdown of p66shc mitigates homocysteine-induced adhesion of monocytes to endothelial cells. Inhibition of DNA methyltransferase activity or knockdown of DNA methyltransferase 3b abrogates homocysteine-induced up-regulation of p66shc. Comparison of plasma homocysteine in humans with coronary artery disease shows a significant difference between those with highest and lowest p66shc promoter CpG methylation in peripheral blood leucocytes.
  
  
  CONCLUSIONS
  Homocysteine up-regulates human p66shc expression via hypomethylation of specific CpG dinucleotides in the p66shc promoter, and this mechanism is important in homocysteine-induced endothelial cell dysfunction.
authors.affiliation: Heart and Vascular Institute, University of Pittsburgh Medical Center, Scaife S620, 200 Lothrop St, Pittsburgh, PA 15213,  USA.
authors.forename: Cuk-Seong
authors.initials: CS
authors.lastname: Kim
authors.forename: Young-Rae
authors.initials: YR
authors.lastname: Kim
authors.forename: Asma
authors.initials: A
authors.lastname: Naqvi
authors.forename: Santosh
authors.initials: S
authors.lastname: Kumar
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Hoffman
authors.forename: Saet-Byel
authors.initials: SB
authors.lastname: Jung
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.forename: Byeong-Hwa
authors.initials: BH
authors.lastname: Jeon
authors.forename: Dennis M
authors.initials: DM
authors.lastname: McNamara
authors.forename: Kaikobad
authors.initials: K
authors.lastname: Irani
mesh_terms: D002448:Cell Adhesion; D003324:Coronary Artery Disease / Q000097:blood; D018899:CpG Islands; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019175:DNA Methylation; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044127:Epigenesis, Genetic / Q000187:drug effects; D045325:HCT116 Cells; D057809:HEK293 Cells; D006710:Homocysteine / Q000097:blood / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D020298:U937 Cells; D015854:Up-Regulation; D000097584:DNA Methyltransferase 3B
chemical_list: D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D004791:Enzyme Inhibitors; D006710:Homocysteine; D018836:Inflammation Mediators; D018799:Intercellular Adhesion Molecule-1; D009569:Nitric Oxide; D017382:Reactive Oxygen Species; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D000097584:DNA Methyltransferase 3B; C528024:SHC1 protein, human