title: Oxidative stress-mediated thrombospondin-2 upregulation impairs bone marrow-derived angiogenic cell function in diabetes mellitus.
abstract: OBJECTIVE
  Circulating angiogenic cells play an essential role in angiogenesis but are dysfunctional in diabetes mellitus characterized by excessive oxidative stress. We hypothesize that oxidative stress-mediated upregulation of thrombospondin-2 (TSP-2), a potent antiangiogenic protein, contributes to diabetic bone marrow-derived angiogenic cell (BMAC) dysfunction.
  
  
  RESULTS
  BMACs were isolated from adult male type 2 diabetic db/db mice and control db/+ (C57BLKS/J) mice. In Matrigel tube formation assay, angiogenic function was impaired in diabetic BMACs, accompanied by increased oxidative stress and nicotinamide adenine dinucleotide phosphate oxidase activity. BMAC angiogenic function was restored by overexpression of dominant negative Rac1 or by overexpression of manganese superoxide dismutase. TSP-2 mRNA and protein were both significantly upregulated in diabetic BMACs, mediated by increased oxidative stress as shown by a decrease in TSP-2 level after overexpression of dominant negative Rac1 or manganese superoxide dismutase. Silencing TSP-2 by its small interfering RNA in diabetic BMACs improved BMAC function in tube formation, adhesion, and migration assays. Notably, the upregulation of TSP-2 was also found in BMACs from streptozotocin-induced type 1 diabetic mice, and normal BMACs with high glucose treatment. let-7f, a microRNA which has been related to endothelial angiogenic function, is found to play key role in TSP-2 increase, but let-7f did not directly interact with TSP-2 mRNA.
  
  
  CONCLUSIONS
  The upregulation of TSP-2 mediated by increased oxidative stress contributes to angiogenesis dysfunction in diabetic BMACs.
authors.affiliation: Department of Cardiology, Center of Clinical Pharmacology, Third Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Ok-Nam
authors.initials: ON
authors.lastname: Bae
authors.forename: Jie-Mei
authors.initials: JM
authors.lastname: Wang
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Baek
authors.forename: Qingde
authors.initials: Q
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Yuan
authors.forename: Alex F
authors.initials: AF
authors.lastname: Chen
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000473:pathology; D003925:Diabetic Angiopathies / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D006943:Hyperglycemia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D019699:Thrombospondins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein; D000099262:Thrombospondin 2
chemical_list: D008562:Membrane Glycoproteins; D035683:MicroRNAs; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D009479:Neuropeptides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013482:Superoxide Dismutase; D019699:Thrombospondins; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000099262:Thrombospondin 2; C548145:MIRNLET7 microRNA, rat; C484602:Rac1 protein, mouse; C488842:Cybb protein, mouse; C060505:neutrophil cytosolic factor 1
keywords: angiogenesis inhibitors; diabetes; oxidative stress; stem cells; thrombospondin-2, human