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Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions
09:17

Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions

Published on: August 2, 2018

The NADPH oxidase subunit NOX4 is a new target gene of the hypoxia-inducible factor-1

Isabel Diebold1, Andreas Petry, John Hess

  • 1Experimental and Molecular Pediatric Cardiology, Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Munich at the Technical University, 80636 Munich, Germany.

Molecular Biology of the Cell
|April 30, 2010
PubMed

Insights

Hypoxia increases NADPH oxidase 4 (NOX4) expression via HIF-1alpha in pulmonary artery cells, contributing to reactive oxygen species (ROS) and proliferation. This NOX4-HIF-1alpha axis is crucial for cardiovascular responses to hypoxia.

Area of Science:

  • Molecular Biology
  • Cellular Physiology
  • Cardiovascular Research

Background:

  • NADPH oxidases (NOX) generate reactive oxygen species (ROS), implicated in disorders with enhanced cell proliferation.
  • NOX4 is involved in vascular signaling and responses to hypoxia, but its regulatory mechanisms remain unclear.

Purpose of the Study:

  • To elucidate the mechanisms controlling NOX4 expression under hypoxic conditions.
  • To investigate the role of the hypoxia-inducible factor 1-alpha (HIF-1alpha) in regulating NOX4.

Main Methods:

  • Studied NOX4 mRNA and protein levels in pulmonary artery smooth muscle cells (PASMCs) and mouse pulmonary vessels under hypoxia.
  • Utilized HIF-1alpha overexpression and depletion to assess its role in NOX4 regulation.
  • Analyzed the NOX4 promoter for hypoxia-responsive elements and confirmed HIF-1alpha binding via chromatin immunoprecipitation.

Main Results:

  • Hypoxia rapidly increased NOX4 mRNA and protein levels in PASMCs and pulmonary vessels.
  • This induction was dependent on HIF-1alpha, as its overexpression enhanced NOX4 expression and its depletion prevented it.
  • HIF-1alpha directly binds to the NOX4 gene promoter, activating its expression.

Conclusions:

  • NOX4 is identified as a novel target gene of HIF-1alpha, playing a significant role in the cellular response to hypoxia.
  • HIF-1alpha-induced NOX4 contributes to maintaining ROS levels and promoting PASMC proliferation under hypoxic conditions.
  • The NOX4-HIF-1alpha signaling axis is critical for cardiovascular adaptation to hypoxia and may be implicated in various cardiovascular disorders.

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