Nox4-derived H2O2 mediates endoplasmic reticulum signaling through local ras activation

Ru Feng Wu, Zhenyi Ma, Zhe Liu, Lance S. Terada

Research output: Contribution to journalArticle

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Abstract

The unfolded-protein response (UPR) of the endoplasmic reticulum (ER) has been linked to oxidant production, although the molecular details and functional significance of this linkage are poorly understood. Using a ratiometric H 2O2 sensor targeted to different subcellular compartments, we demonstrate specific production of H2O2 by the ER in response to the stressors tunicamycin and HIV-1 Tat, but not to thapsigargin or dithiothreitol. Knockdown of the oxidase Nox4, expressed on ER endomembranes, or expression of ER-targeted catalase blocked ER H2O2 production by tunicamycin and Tat and prevented the UPR following exposure to these two agonists, but not to thapsigargin or dithiothreitol. Tat also triggered Nox4-dependent, sustained activation of Ras leading to ERK, but not phosphatidylinositol 3-kinase (PI3K)/mTOR, pathway activation. Cell fractionation studies and green fluorescent protein (GFP) fusions of GTPase effector binding domains confirmed selective activation of endogenous RhoA and Ras on the ER surface, with ER-associated K-Ras acting upstream of the UPR and downstream of Nox4. Notably, the Nox4/Ras/ERK pathway induced autophagy, and suppression of autophagy unmasked cell death and prevented differentiation of endothelial cells in 3-dimensional matrix. We conclude that the ER surface provides a platform to spatially organize agonist-specific Nox4-dependent oxidative signaling events, leading to homeostatic protective mechanisms rather than oxidative stress.

Original languageEnglish (US)
Pages (from-to)3553-3568
Number of pages16
JournalMolecular and Cellular Biology
Volume30
Issue number14
DOIs
StatePublished - Jul 2010

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Endoplasmic Reticulum
Unfolded Protein Response
Tunicamycin
Thapsigargin
Dithiothreitol
Autophagy
Phosphatidylinositol 3-Kinase
Cell Fractionation
MAP Kinase Signaling System
GTP Phosphohydrolases
Green Fluorescent Proteins
Oxidants
Catalase
HIV-1
Oxidoreductases
Oxidative Stress
Cell Death
Endothelial Cells

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Nox4-derived H2O2 mediates endoplasmic reticulum signaling through local ras activation. / Wu, Ru Feng; Ma, Zhenyi; Liu, Zhe; Terada, Lance S.

In: Molecular and Cellular Biology, Vol. 30, No. 14, 07.2010, p. 3553-3568.

Research output: Contribution to journalArticle

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