title: Simulated Microgravity Promotes Cell Apoptosis Through Suppressing Uev1A/TICAM/TRAF/NF-κB-Regulated Anti-Apoptosis and p53/PCNA- and ATM/ATR-Chk1/2-Controlled DNA-Damage Response Pathways.
abstract: Microgravity has been known to induce cell death. However, its underlying mechanism is less studied. In this study, BL6-10 melanoma cells were cultured in flasks under simulated microgravity (SMG). We examined cell apoptosis, and assessed expression of genes associated with apoptosis and genes regulating apoptosis in cells under SMG. We demonstrate that SMG induces cell morphological changes and microtubule alterations by confocal microscopy, and enhances apoptosis by flow cytometry, which was associated with up- and down-regulation of pro-apoptotic and anti-apoptotic genes, respectively. Moreover, up- and down-regulation of pro-apoptotic (Caspases 3, 7, 8) and anti-apoptotic (Bcl2 and Bnip3) molecules was confirmed by Western blotting analysis. Western blot analysis also indicates that SMG causes inhibition of an apoptosis suppressor, pNF-κB-p65, which is complemented by the predominant localization of NF-κB-p65 in the cytoplasm. SMG also reduces expression of molecules regulating the NF-κB pathway including Uev1A, TICAM, TRAF2, and TRAF6. Interestingly, 10 DNA repair genes are down-regulated in cells exposed to SMG, among which down-regulation of Parp, Ercc8, Rad23, Rad51, and Ku70 was confirmed by Western blotting analysis. In addition, we demonstrate a significant inhibition of molecules involved in the DNA-damage response, such as p53, PCNA, ATM/ATR, and Chk1/2. Taken together, our work reveals that SMG promotes the apoptotic response through a combined modulation of the Uev1A/TICAM/TRAF/NF-κB-regulated apoptosis and the p53/PCNA- and ATM/ATR-Chk1/2-controlled DNA-damage response pathways. Thus, our investigation provides novel information, which may help us to determine the cause of negative alterations in human physiology occurring at spaceflight environment. J. Cell. Biochem. 117: 2138-2148, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Aerospace Institute of Medical Engineering and Biotechnology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.
authors.forename: Tuo
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Aerospace Institute of Medical Engineering and Biotechnology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Tang
authors.affiliation: Cancer Research Cluster, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada.
authors.forename: Channakeshava Sokke
authors.initials: CS
authors.lastname: Umeshappa
authors.affiliation: Aerospace Institute of Medical Engineering and Biotechnology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
authors.affiliation: Aerospace Institute of Medical Engineering and Biotechnology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Gao
authors.affiliation: Aerospace Institute of Medical Engineering and Biotechnology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.
authors.forename: Yulin
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Freywald
authors.affiliation: Aerospace Institute of Medical Engineering and Biotechnology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.|Cancer Research Cluster, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada.
authors.forename: Jim
authors.initials: J
authors.lastname: Xiang
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1 / Q000235:genetics / Q000378:metabolism*; D064447:Checkpoint Kinase 2 / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D051379:Mice; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D047992:TNF Receptor-Associated Factor 2 / Q000235:genetics / Q000378:metabolism*; D048029:TNF Receptor-Associated Factor 6 / Q000235:genetics / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*; D014893:Weightlessness
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D064007:Ataxia Telangiectasia Mutated Proteins; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D018809:Proliferating Cell Nuclear Antigen; D047992:TNF Receptor-Associated Factor 2; D048029:TNF Receptor-Associated Factor 6; D051996:Transcription Factor RelA; D016159:Tumor Suppressor Protein p53; D044763:Ubiquitin-Conjugating Enzymes; C498144:Rela protein, mouse; C476286:Ticam1 protein, mouse; C000622387:TRAF2 protein, mouse; C524395:UBE2V1 protein, mouse; C576325:Atm protein, mouse; C000605869:Chek1 protein, mouse; C578633:Chek2 protein, mouse
keywords: APOPTOSIS; ATM/ATR; NF-κB; P53; SIMULATED MICROGRAVITY