Oxidative stress induces mitochondrial dysfunction and a protective unfolded protein response in RPE cells

Marisol Cano, Lei Wang, Jun Wan, Bradley P. Barnett, Katayoon Ebrahimi, Jiang Qian, James Handa

Research output: Contribution to journalArticle

Abstract

How cells degenerate from oxidative stress in aging-related disease is incompletely understood. This study's intent was to identify key cytoprotective pathways activated by oxidative stress and determine the extent of their protection. Using an unbiased strategy with microarray analysis, we found that retinal pigmented epithelial (RPE) cells treated with cigarette smoke extract (CSE) had overrepresented genes involved in the antioxidant and unfolded protein response (UPR). Differentially expressed antioxidant genes were predominantly located in the cytoplasm, with no induction of genes that neutralize superoxide and H2O2 in the mitochondria, resulting in accumulation of superoxide and decreased ATP production. Simultaneously, CSE induced the UPR sensors IRE1α, p-PERK, and ATP6, including CHOP, which was cytoprotective because CHOP knockdown decreased cell viability. In mice given intravitreal CSE, the RPE had increased IRE1α and decreased ATP and developed epithelial-mesenchymal transition, as suggested by decreased LRAT abundance, altered ZO-1 immunolabeling, and dysmorphic cell shape. Mildly degenerated RPE from early age-related macular degeneration (AMD) samples had prominent IRE1α, but minimal mitochondrial TOM20 immunolabeling. Although oxidative stress is thought to induce an antioxidant response with cooperation between the mitochondria and the ER, herein we show that mitochondria become impaired sufficiently to induce epithelial-mesenchymal transition despite a protective UPR. With similar responses in early AMD samples, these results suggest that mitochondria are vulnerable to oxidative stress despite a protective UPR during the early phases of aging-related disease.

Original languageEnglish (US)
Pages (from-to)1-14
Number of pages14
JournalFree Radical Biology and Medicine
Volume69
DOIs
StatePublished - Apr 2014

Fingerprint

Unfolded Protein Response
Mitochondria
Oxidative stress
Oxidative Stress
Epithelial Cells
Smoke
Tobacco Products
Epithelial-Mesenchymal Transition
Antioxidants
Genes
Macular Degeneration
Superoxides
Proteins
Adenosine Triphosphate
Aging of materials
Cell Shape
Microarray Analysis
Microarrays
Cell Survival
Cytoplasm

Keywords

  • Aging-related disease
  • Epithelial-mesenchymal transition
  • ER stress
  • Free radicals
  • Mitochondria
  • Oxidative stress

ASJC Scopus subject areas

  • Biochemistry
  • Physiology (medical)

Cite this

Oxidative stress induces mitochondrial dysfunction and a protective unfolded protein response in RPE cells. / Cano, Marisol; Wang, Lei; Wan, Jun; Barnett, Bradley P.; Ebrahimi, Katayoon; Qian, Jiang; Handa, James.

In: Free Radical Biology and Medicine, Vol. 69, 04.2014, p. 1-14.

Research output: Contribution to journalArticle

@article{bde2d1617eaf4659ac5d5d85891f4687,
title = "Oxidative stress induces mitochondrial dysfunction and a protective unfolded protein response in RPE cells",
abstract = "How cells degenerate from oxidative stress in aging-related disease is incompletely understood. This study's intent was to identify key cytoprotective pathways activated by oxidative stress and determine the extent of their protection. Using an unbiased strategy with microarray analysis, we found that retinal pigmented epithelial (RPE) cells treated with cigarette smoke extract (CSE) had overrepresented genes involved in the antioxidant and unfolded protein response (UPR). Differentially expressed antioxidant genes were predominantly located in the cytoplasm, with no induction of genes that neutralize superoxide and H2O2 in the mitochondria, resulting in accumulation of superoxide and decreased ATP production. Simultaneously, CSE induced the UPR sensors IRE1α, p-PERK, and ATP6, including CHOP, which was cytoprotective because CHOP knockdown decreased cell viability. In mice given intravitreal CSE, the RPE had increased IRE1α and decreased ATP and developed epithelial-mesenchymal transition, as suggested by decreased LRAT abundance, altered ZO-1 immunolabeling, and dysmorphic cell shape. Mildly degenerated RPE from early age-related macular degeneration (AMD) samples had prominent IRE1α, but minimal mitochondrial TOM20 immunolabeling. Although oxidative stress is thought to induce an antioxidant response with cooperation between the mitochondria and the ER, herein we show that mitochondria become impaired sufficiently to induce epithelial-mesenchymal transition despite a protective UPR. With similar responses in early AMD samples, these results suggest that mitochondria are vulnerable to oxidative stress despite a protective UPR during the early phases of aging-related disease.",
keywords = "Aging-related disease, Epithelial-mesenchymal transition, ER stress, Free radicals, Mitochondria, Oxidative stress",
author = "Marisol Cano and Lei Wang and Jun Wan and Barnett, {Bradley P.} and Katayoon Ebrahimi and Jiang Qian and James Handa",
year = "2014",
month = "4",
doi = "10.1016/j.freeradbiomed.2014.01.004",
language = "English (US)",
volume = "69",
pages = "1--14",
journal = "Free Radical Biology and Medicine",
issn = "0891-5849",
publisher = "Elsevier Inc.",

}

TY - JOUR

T1 - Oxidative stress induces mitochondrial dysfunction and a protective unfolded protein response in RPE cells

AU - Cano, Marisol

AU - Wang, Lei

AU - Wan, Jun

AU - Barnett, Bradley P.

AU - Ebrahimi, Katayoon

AU - Qian, Jiang

AU - Handa, James

PY - 2014/4

Y1 - 2014/4

N2 - How cells degenerate from oxidative stress in aging-related disease is incompletely understood. This study's intent was to identify key cytoprotective pathways activated by oxidative stress and determine the extent of their protection. Using an unbiased strategy with microarray analysis, we found that retinal pigmented epithelial (RPE) cells treated with cigarette smoke extract (CSE) had overrepresented genes involved in the antioxidant and unfolded protein response (UPR). Differentially expressed antioxidant genes were predominantly located in the cytoplasm, with no induction of genes that neutralize superoxide and H2O2 in the mitochondria, resulting in accumulation of superoxide and decreased ATP production. Simultaneously, CSE induced the UPR sensors IRE1α, p-PERK, and ATP6, including CHOP, which was cytoprotective because CHOP knockdown decreased cell viability. In mice given intravitreal CSE, the RPE had increased IRE1α and decreased ATP and developed epithelial-mesenchymal transition, as suggested by decreased LRAT abundance, altered ZO-1 immunolabeling, and dysmorphic cell shape. Mildly degenerated RPE from early age-related macular degeneration (AMD) samples had prominent IRE1α, but minimal mitochondrial TOM20 immunolabeling. Although oxidative stress is thought to induce an antioxidant response with cooperation between the mitochondria and the ER, herein we show that mitochondria become impaired sufficiently to induce epithelial-mesenchymal transition despite a protective UPR. With similar responses in early AMD samples, these results suggest that mitochondria are vulnerable to oxidative stress despite a protective UPR during the early phases of aging-related disease.

AB - How cells degenerate from oxidative stress in aging-related disease is incompletely understood. This study's intent was to identify key cytoprotective pathways activated by oxidative stress and determine the extent of their protection. Using an unbiased strategy with microarray analysis, we found that retinal pigmented epithelial (RPE) cells treated with cigarette smoke extract (CSE) had overrepresented genes involved in the antioxidant and unfolded protein response (UPR). Differentially expressed antioxidant genes were predominantly located in the cytoplasm, with no induction of genes that neutralize superoxide and H2O2 in the mitochondria, resulting in accumulation of superoxide and decreased ATP production. Simultaneously, CSE induced the UPR sensors IRE1α, p-PERK, and ATP6, including CHOP, which was cytoprotective because CHOP knockdown decreased cell viability. In mice given intravitreal CSE, the RPE had increased IRE1α and decreased ATP and developed epithelial-mesenchymal transition, as suggested by decreased LRAT abundance, altered ZO-1 immunolabeling, and dysmorphic cell shape. Mildly degenerated RPE from early age-related macular degeneration (AMD) samples had prominent IRE1α, but minimal mitochondrial TOM20 immunolabeling. Although oxidative stress is thought to induce an antioxidant response with cooperation between the mitochondria and the ER, herein we show that mitochondria become impaired sufficiently to induce epithelial-mesenchymal transition despite a protective UPR. With similar responses in early AMD samples, these results suggest that mitochondria are vulnerable to oxidative stress despite a protective UPR during the early phases of aging-related disease.

KW - Aging-related disease

KW - Epithelial-mesenchymal transition

KW - ER stress

KW - Free radicals

KW - Mitochondria

KW - Oxidative stress

UR - http://www.scopus.com/inward/record.url?scp=84893171710&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84893171710&partnerID=8YFLogxK

U2 - 10.1016/j.freeradbiomed.2014.01.004

DO - 10.1016/j.freeradbiomed.2014.01.004

M3 - Article

C2 - 24434119

AN - SCOPUS:84893171710

VL - 69

SP - 1

EP - 14

JO - Free Radical Biology and Medicine

JF - Free Radical Biology and Medicine

SN - 0891-5849

ER -