Manipulation of the HIF-Vegf Pathway Rescues Methyl Tert-Butyl Ether (MTBE)-induced Vascular Lesions

Toxicol Appl Pharmacol. 2013 Dec 15;273(3):623-34. doi: 10.1016/j.taap.2013.10.008. Epub 2013 Oct 12.

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.

Keywords: Hypoxia inducible factor; Methyl tert-butyl ether; N-oxalylglycine; Vascular endothelial growth factor; Vascular toxicity; von Hippel-Lindau protein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Down-Regulation
  • Hypoxia-Inducible Factor 1 / genetics
  • Hypoxia-Inducible Factor 1 / metabolism*
  • Methyl Ethers / toxicity*
  • Neovascularization, Physiologic / drug effects
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Signal Transduction
  • Transcriptome
  • Vascular Diseases / chemically induced
  • Vascular Diseases / drug therapy*
  • Vascular Diseases / genetics
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism*
  • Von Hippel-Lindau Tumor Suppressor Protein / genetics
  • Von Hippel-Lindau Tumor Suppressor Protein / metabolism
  • Zebrafish / embryology
  • Zebrafish Proteins / genetics
  • Zebrafish Proteins / metabolism*

Substances

  • Hypoxia-Inducible Factor 1
  • Methyl Ethers
  • RNA, Messenger
  • Vascular Endothelial Growth Factor A
  • Vegfaa protein, zebrafish
  • Zebrafish Proteins
  • methyl tert-butyl ether
  • Von Hippel-Lindau Tumor Suppressor Protein