Differential signaling pathways of HO-1 gene expression in pulmonary and systemic vascular cells. Academic Article uri icon

Overview

MeSH

  • Animals
  • Blotting, Northern
  • Cell Hypoxia
  • Cells, Cultured
  • DNA-Binding Proteins
  • Endothelium, Vascular
  • Enhancer Elements, Genetic
  • Gene Expression Regulation, Enzymologic
  • Heme Oxygenase-1
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Muscle, Smooth, Vascular
  • Nuclear Proteins
  • Protein Binding
  • Pulmonary Artery
  • RNA, Messenger
  • Rats
  • Transcription Factor AP-1

MeSH Major

  • Heme Oxygenase (Decyclizing)
  • Signal Transduction
  • Transcription Factors

abstract

  • Heme oxygenase-1 (HO-1) is induced by oxidative stress and plays an important role in cellular protection against oxidant injury. Increasing evidence also suggests that HO-1 is markedly modulated by hypoxia in vitro and in vivo. Our group has previously demonstrated that the transcription factor hypoxia-inducible factor (HIF)-1 mediates hypoxia-induced HO-1 gene transcription and expression in systemic (aortic) vascular smooth muscle (AoVSM) cells (P. J. Lee, B. -H. Jiang, B. Y. Chin, N. V. Iyer, J. Alam, G. L. Semenza, and A. M. K. Choi. J. Biol. Chem. 272: 5375-5381, 1997). Because the pulmonary circulation is an important target of hypoxia, this study investigated whether HO-1 gene expression in pulmonary arterial vascular smooth muscle was differentially regulated by hypoxia in comparison to AoVSM cells. Interestingly, hypoxia neither induced HO-1 gene expression nor increased HIF-1 DNA binding activity in pulmonary arterial vascular smooth muscle cells. Conversely, pulmonary arterial endothelial cells (PAECs) demonstrated a marked induction of HO-1 gene expression after hypoxia. Electrophoretic mobility shift assays detected an increase in activator protein-1 rather than in HIF-1 DNA binding activity in nuclear extracts of hypoxic PAECs. Analyses of the promoter and 5'-flanking regions of the HO-1 gene were performed by transiently transfecting PAECs with either the hypoxia response element (HIF-1 binding site) or the HO-1 gene distal enhancer element (AB1) linked to a chloramphenicol acetyltransferase reporter gene. Increased chloramphenicol acetyltransferase activity was observed only in transfectants containing the AB1 distal enhancer, and mutational analysis of this enhancer suggested that the activator protein-1 regulatory element was critical for hypoxia-induced HO-1 gene transcription. Collectively, our data demonstrate that the molecular regulation of HO-1 gene transcription during hypoxia differs between the systemic and pulmonary circulations and also provide evidence that hypoxia-induced HO-1 gene expression in PAECs and AoVSM cells is regulated through two discrete signaling pathways.

publication date

  • December 1999

has subject area

  • Animals
  • Blotting, Northern
  • Cell Hypoxia
  • Cells, Cultured
  • DNA-Binding Proteins
  • Endothelium, Vascular
  • Enhancer Elements, Genetic
  • Gene Expression Regulation, Enzymologic
  • Heme Oxygenase (Decyclizing)
  • Heme Oxygenase-1
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Muscle, Smooth, Vascular
  • Nuclear Proteins
  • Protein Binding
  • Pulmonary Artery
  • RNA, Messenger
  • Rats
  • Signal Transduction
  • Transcription Factor AP-1
  • Transcription Factors

Research

keywords

  • Journal Article

Identity

Language

  • eng

PubMed ID

  • 10600883

Additional Document Info

start page

  • L1133

end page

  • L1141

volume

  • 277

number

  • 6 Pt 1