title: Manipulation of the HIF-Vegf pathway rescues methyl tert-butyl ether (MTBE)-induced vascular lesions.
abstract: Methyl tert-butyl ether (MTBE) has been shown to be specifically anti-angiogenic in piscine and mammalian model systems at concentrations that appear non-toxic in other organ systems. The mechanism by which MTBE targets developing vascular structures is unknown. A global transcriptome analysis of zebrafish embryos developmentally exposed to 0.00625-5mM MTBE suggested that hypoxia inducible factor (HIF)-regulated pathways were affected. HIF-driven angiogenesis via vascular endothelial growth factor (vegf) is essential to the developing vasculature of an embryo. Three rescue studies were designed to rescue MTBE-induced vascular lesions: pooled blood in the common cardinal vein (CCV), cranial hemorrhages (CH), and abnormal intersegmental vessels (ISV), and test the hypothesis that MTBE toxicity was HIF-Vegf dependent. First, zebrafish vegf-a over-expression via plasmid injection, resulted in significantly fewer CH and ISV lesions, 46 and 35% respectively, in embryos exposed to 10mM MTBE. Then HIF degradation was inhibited in two ways. Chemical rescue by N-oxaloylglycine significantly reduced CCV and CH lesions by 30 and 32% in 10mM exposed embryos, and ISV lesions were reduced 24% in 5mM exposed zebrafish. Finally, a morpholino designed to knock-down ubiquitin associated von Hippel-Lindau protein, significantly reduced CCV lesions by 35% in 10mM exposed embryos. In addition, expression of some angiogenesis related genes altered by MTBE exposure were rescued. These studies demonstrated that MTBE vascular toxicity is mediated by a down regulation of HIF-Vegf driven angiogenesis. The selective toxicity of MTBE toward developing vasculature makes it a potentially useful chemical in the designing of new drugs or in elucidating roles for specific angiogenic proteins in future studies of vascular development.
authors.affiliation: Rutgers, The State University of New Jersey, Joint Graduate Program in Toxicology, 170 Frelinghuysen Road, Piscataway, NJ 08854, USA; Rutgers, The State University of New Jersey, Department of Biochemistry & Microbiology, 76 Lipman Dr., New Brunswick, NJ 08901, USA; Oregon State University, Department of Environmental & Molecular Toxicology, 1011 Agricultural & Life Sciences Bldg, Corvallis, OR 97331, USA. Electronic address: josephine.bonventre@oregonstate.edu.
authors.forename: Josephine A
authors.initials: JA
authors.lastname: Bonventre
authors.forename: Tiffany S
authors.initials: TS
authors.lastname: Kung
authors.forename: Lori A
authors.initials: LA
authors.lastname: White
authors.forename: Keith R
authors.initials: KR
authors.lastname: Cooper
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D015536:Down-Regulation; D051793:Hypoxia-Inducible Factor 1 / Q000235:genetics / Q000378:metabolism*; D008738:Methyl Ethers / Q000633:toxicity*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D059467:Transcriptome; D014652:Vascular Diseases / Q000139:chemically induced / Q000188:drug therapy* / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D051793:Hypoxia-Inducible Factor 1; D008738:Methyl Ethers; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C583604:Vegfaa protein, zebrafish; D029961:Zebrafish Proteins; C043243:methyl tert-butyl ether; D051794:Von Hippel-Lindau Tumor Suppressor Protein
keywords: Hypoxia inducible factor; Methyl tert-butyl ether; N-oxalylglycine; Vascular endothelial growth factor; Vascular toxicity; von Hippel-Lindau protein