Endoplasmic reticulum stress and unfolded protein response in Atm-deficient thymocytes and thymic lymphoma cells are attributable to oxidative stress.
Both oxidative stress and endoplasmic reticulum (ER) stress have been implicated in carcinogenesis. It is well documented that cells deficient in the ataxia-telangiectasia mutated (ATM) gene undergo oxidative stress, which is critically involved in thymic lymphomagenesis in Atm-/- mice. Here we demonstrate that undifferentiated Atm-/- thymocytes show signs of ER stress and of the unfolded protein response (UPR). Using two-dimensional (2-D) gel electrophoresis and mass spectrometry (MS) analysis, we identified 22 differentially expressed proteins, including the ER stress marker glucose-regulated protein 78 (GRP78), in Atm-/- thymocytes and in Atm-/- thymic lymphoma cells relative to Atm+/+ thymocytes. The phosphorylated alpha subunit of eukaryotic translation initiation factor 2 (p-eIF2alpha), a UPR marker, was also increased in Atm-/- thymocytes. Cells of the ATL-1 line, which were derived from an Atm-/- mouse thymic lymphoma, were more sensitive to the ER stress inducer tunicamycin than were Atm+/+ thymic leukemia ASL-1 cells. Notably, treatment with hydrogen peroxide duplicated the effects of ATM deficiency in cultured thymocytes, and treatment with the novel cell-permeable thiol antioxidant N-acetylcysteine amide (AD4) reduced elevated p-eIF2alpha levels in thymocytes of Atm-/- mice. Thus, we propose that ER stress and the UPR are secondary to oxidative stress in Atm-/- thymocytes.
Yan
Mingshan
M
Department of Carcinogenesis, The University of Texas MD Anderson Cancer Center, Science Park-Research Division, Smithville, TX 78957, USA. mingyan@mdanderson.org
Shen
Jianjun
J
Person
Maria D
MD
Kuang
Xianghong
X
Lynn
William S
WS
Atlas
Daphne
D
Wong
Paul K Y
PK
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D053148:Caspase 3 / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008223:Lymphoma / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018832:Molecular Chaperones / Q000378:metabolism; D018384:Oxidative Stress; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency* / Q000235:genetics; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D013953:Thymus Neoplasms / Q000378:metabolism* / Q000473:pathology; D025521:Tumor Suppressor Proteins / Q000172:deficiency* / Q000235:genetics; D014415:Tunicamycin / Q000494:pharmacology
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D015852:Eukaryotic Initiation Factor-2; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D008565:Membrane Proteins; D018832:Molecular Chaperones; D025521:Tumor Suppressor Proteins; C018551:glucose-regulated proteins; D014415:Tunicamycin; D006861:Hydrogen Peroxide; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D053148:Caspase 3