title: SIRT1 deficiency downregulates PTEN/JNK/FOXO1 pathway to block reactive oxygen species-induced apoptosis in mouse embryonic stem cells.
abstract: Silent mating type information regulation 2 homolog 1 (SIRT1) plays a critical role in reactive oxygen species-triggered apoptosis in mouse embryonic stem (mES) cells. Here, we investigated a possible role for the PTEN/Akt/JNK pathway in the SIRT1-mediated apoptosis pathway in mES cells. Akt was activated by removal of anti-oxidant 2-mercaptoethanol in SIRT1(-/-) mES cells. Since PTEN is a negative regulator of Akt and its activity can be modulated by acetylation, we investigated if SIRT1 deacetylated PTEN to downregulate Akt to trigger apoptosis in anti-oxidant-free culture conditions. PTEN was hyperacetylated and excluded from the nucleus in SIRT1(-/-) mES cells, consistent with enhanced Akt activity. SIRT1 deficiency enhanced the acetylation/phosphorylation level of FOXO1 and subsequently inhibited the nuclear localization of FOXO1. Cellular acetylation levels were enhanced by DNA-damaging agent, not by removal of anti-oxidant. c-Jun NH2-terminal kinase (JNK) was activated by removal of anti-oxidant in SIRT1-dependent manner. Although p53 acetylation was stronger in SIRT1(-/-) mES cells, DNA-damaging stress activated phosphorylation and enhanced cellular levels of p53 irrespective of SIRT1, whereas removal of anti-oxidant slightly activated p53 only with SIRT1. Expression levels of Bim and Puma were increased in anti-oxidant-free culture conditions in an SIRT1-dependent manner and treatment with JNK inhibitor blocked induction of Bim expression. DNA-damaging agent activated caspase3 regardless of SIRT1. Our data support an important role for SIRT1 in preparing the PTEN/JNK/FOXO1 pathway to respond to cellular reactive oxygen species.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
authors.forename: Hee-Don
authors.initials: HD
authors.lastname: Chae
authors.forename: Hal E
authors.initials: HE
authors.lastname: Broxmeyer
mesh_terms: D000107:Acetylation; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015536:Down-Regulation; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008623:Mercaptoethanol / Q000494:pharmacology; D051379:Mice; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D010766:Phosphorylation; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D056564:Sirtuin 1 / Q000172:deficiency* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D000873:Anthracenes; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C467200:Foxo1 protein, mouse; D008565:Membrane Proteins; C488588:PUMA protein, mouse; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C432165:pyrazolanthrone; D008623:Mercaptoethanol; D048031:JNK Mitogen-Activated Protein Kinases; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1