title: Advanced glycation end product Nε-carboxymethyllysine induces endothelial cell injury: the involvement of SHP-1-regulated VEGFR-2 dephosphorylation.
abstract: N(ε)-carboxymethyllysine (CML), a major advanced glycation end product, plays a crucial role in diabetes-induced vascular injury. The roles of protein tyrosine phosphatases and vascular endothelial growth factor (VEGF) receptors in CML-related endothelial cell injury are still unclear. Human umbilical vein endothelial cells (HUVECs) are a commonly used human EC type. Here, we tested the hypothesis that NADPH oxidase/reactive oxygen species (ROS)-mediated SH2 domain-containing tyrosine phosphatase-1 (SHP-1) activation by CML inhibits the VEGF receptor-2 (VEGFR-2, KDR/Flk-1) activation, resulting in HUVEC injury. CML significantly inhibited cell proliferation and induced apoptosis and reduced VEGFR-2 activation in parallel with the increased SHP-1 protein expression and activity in HUVECs. Adding recombinant VEGF increased forward biological effects, which were attenuated by CML. The effects of CML on HUVECs were abolished by SHP-1 siRNA transfection. Exposure of HUVECs to CML also remarkably escalated the integration of SHP-1 with VEGFR-2. Consistently, SHP-1 siRNA transfection and pharmacological inhibitors could block this interaction and elevating [(3)H]thymidine incorporation. CML also markedly activated the NADPH oxidase and ROS production. The CML-increased SHP-1 activity in HUVECs was effectively attenuated by antioxidants. Moreover, the immunohistochemical staining of SHP-1 and CML was increased, but phospho-VEGFR-2 staining was decreased in the aortic endothelium of streptozotocin-induced and high-fat diet-induced diabetic mice. We conclude that a pathway of tyrosine phosphatase SHP-1-regulated VEGFR-2 dephosphorylation through NADPH oxidase-derived ROS is involved in the CML-triggered endothelial cell dysfunction/injury. These findings suggest new insights into the development of therapeutic approaches to reduce diabetic vascular complications.
authors.affiliation: Institute of Toxicology, College of Medicine, National Taiwan University, Taiwan.
authors.forename: Shing Hwa
authors.initials: SH
authors.lastname: Liu
authors.forename: Wayne Huey Herng
authors.initials: WH
authors.lastname: Sheu
authors.forename: Maw Rong
authors.initials: MR
authors.lastname: Lee
authors.forename: Wen Jane
authors.initials: WJ
authors.lastname: Lee
authors.forename: Yu Chiao
authors.initials: YC
authors.lastname: Yi
authors.forename: Tzung Jie
authors.initials: TJ
authors.lastname: Yang
authors.forename: Jen Fon
authors.initials: JF
authors.lastname: Jen
authors.forename: Hung Chuan
authors.initials: HC
authors.lastname: Pan
authors.forename: Chin Chang
authors.initials: CC
authors.lastname: Shen
authors.forename: Wen Bao
authors.initials: WB
authors.lastname: Chen
authors.forename: Hsing Ru
authors.initials: HR
authors.lastname: Tien
authors.forename: Meei Ling
authors.initials: ML
authors.lastname: Sheu
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D020868:Gene Silencing; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D017127:Glycation End Products, Advanced; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C048496:N(6)-carboxymethyllysine; D040301:Vascular Endothelial Growth Factor Receptor-2; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D008239:Lysine