The p53 R72P polymorphism does not affect the physiological response to ionizing radiation in a mouse model.
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ABSTRACT:
SUBMITTER: Dominguez ER
PROVIDER: S-EPMC5499914 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Ionizing radiation is a harsh environmental factor that could induce plant aging. We hypothesized that radiation-related aging remodels proteome, particularly triggering the accumulation of prion-like proteins in tissues. The object of this study, pea (Pisum sativum), is an agriculturally important legume. Research on the functional importance of amyloidogenic proteins was never performed on this species. Pea seeds were irradiated by 50 Gy of X-rays. Afterwards, Fourier-transform infrared spectroscopy (FTIR) was used to investigate changes in the secondary structure of proteins in germinated seedlings. Specifically, we evaluated the ratio between the amide I and II peaks. Next, we performed protein staining with Congo red to compare the presence of amyloids in the samples. In parallel, we profiled detergent-resistant proteome fraction by ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS). Differentially accumulated proteins were functionally analyzed in MapMan software, and the PLAAC tool was used to reveal putative prion-like proteins. We showed a reduced germination rate, yet higher plant height and faster appearance of reproductive organs in the irradiated group compared with the control; furthermore, we demonstrated more β-sheets and amyloid aggregates in the leaves of stressed plants. We detected 531 proteins in detergent-resistant fraction extracted from roots, and 62 were annotated as putative prion-like proteins. Notably, 29 proteins were significantly differentially abundant between the irradiated and the control groups. These proteins belong to several functional categories: amino acid metabolism, carbohydrate metabolism, cytoskeleton organization, regulatory processes, protein biosynthesis, and RNA processing. Thus, discovery proteomics provided deep data on novel aspects of plant stress biology. Our data hinted that protein accumulation stimulated seedlings' growth and affected the regulatory system, primarily through translation and RNA processing. Increased abundance of primary metabolism-related proteins points to more intensive metabolic processes triggered in germinating pea seeds upon X-ray exposure. The functional role of detected putative amyloidogenic proteins should be validated in overexpression or knockout follow-up studies.
2024-03-18 | PXD044798 | Pride
Project description:In response to ionizing radiation (IR), cells activate a DNA damage response (DDR) pathway to re-program gene expression. Previous studies using total cellular RNA analyses have shown that the stress kinase ATM and the transcription factor p53 are integral components required for induction of IR-induced gene expression. These studies did not distinguish between changes in RNA synthesis and RNA turnover and did not address the role of enhancer elements in DDR-mediated transcriptional regulation. To determine the contribution of synthesis and degradation of RNA and monitor the activity of enhancer elements following exposure to IR, we used the recently developed Bru-seq, BruChase-seq and BruUV-seq techniques. Our results show that ATM and p53 regulate both RNA synthesis and stability as well as enhancer element activity following exposure to IR. Importantly, many genes in the p53-signaling pathway were coordinately up-regulated by both increased synthesis and RNA stability while down-regulated genes were suppressed either by reduced synthesis or stability. Our study is the first of its kind that independently assessed the effects of ionizing radiation on transcription and post-transcriptional regulation in normal human cells.
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Project description:Developing pharmacological strategies for controlling ionizing radiation (IR)-induced cell death is important for both mitigating radiation damage and alleviating the side effects of anti-cancer radiotherapy manifested in surrounding tissue morbidity. Exposure to IR often triggers the onset of p53-dependent apoptotic pathways. Here we build a stochastic model of p53 induced apoptosis comprised of coupled modules of nuclear p53 activation, mitochondrial cytochrome c release and cytosolic caspase activation that also takes into account cellular heterogeneity. Our simulations show that the strength of p53 transcriptional activity and its coupling (or timing with respect) to mitochondrial pore opening are major determinants of cell fate: for systems where apoptosis is elicited via a p53-transcription-independent mechanism, direct activation of Bax by p53 becomes critical to IR-induced-damage initiation. We further show that immediate administration of PUMA inhibitors following IR exposure effectively suppresses excessive cell death, provided that there is a strong caspase/Bid feedback loop; however, the efficacy of the treatment diminishes with increasing delay in treatment implementation. In contrast, the combined inhibition of Bid and Bax elicits an anti-apoptotic response that is effective over a range of time delays.
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Project description:Background: Ionizing Radiation (IR) is a known pro-inflammatory agent and in the process of development of biomarkers for radiation biodosimetry a chronic inflammatory disease condition could act as a confounding factor. Hence, it is important to develop radiation biodosimetry that can distinguish between IR-induced inflammatory responses and pre-existing disease. In this study, we compared the gene expression response of a genetically modified mouse model of inflammatory bowel disease (Il10-/-) with that of a normal wild-type mouse to potentially develop transcriptomic based biodosimetry markers for individual susceptibility to radiation. Results: Wild-type (WT) and Il10-/- mice were exposed to whole body irradiation of 7Gy (LD50/30 for IL10-/-) X-rays. Gene expression responses were studied using high throughput whole genome microarrays in peripheral blood after 24h post-irradiation. Analysis resulted in identification of 1962 and 1844 genes differentially expressed (p < 0.001, FDR < 10%) after radiation exposure in Il10-/- and WT mice respectively. A set of 155 genes were also identified as differentially expressing between WT and Il10-/- mice at the baseline pre-irradiation level. Gene ontology analysis revealed that the baseline differentially expressing genes (155) were mainly involved in Inflammatory response, Glutathione metabolism and fibrosis. Analysis of radiation responsive genes revealed commonality of immune function genes between WT and Il10-/- mice. Gene ontology analysis revealed that innate immune response and p53 signaling processes were strongly associated with up-regulated genes whereas, B-cell development process was found to be significant amongst downregulated genes in response to radiation in the two genotypes. However, specific immune response pathways like MHC class I antigen presentation and response to viral/bacterial infection were particularly associated with radiation responsive genes of Il10-/- mice but not with WT mice. Further analysis of activation status of specific canonical pathways and upstream regulators using IPA-prediction tool revealed significant difference in the activation status of T-cell and hormone mediated signaling as well as regulators of inflammation between WT and Il10-/- after irradiation.
2019-04-04 | GSE114142 | GEO
Project description:Thymic epithelial cells (TECs) are the main components of the thymic stroma that support and control T-cell development. Preparative regimens using DNA-damaging agents, such as total body irradiation and/or chemotherapeutic drugs, that are necessary prior to bone marrow transplantation (BMT) have profound deleterious effects on the hematopoietic system, including the thymic stroma, which may be one of the main causes for the prolonged periods of T-cell deficiency and the inefficient T cell reconstitution that are common following BMT. The DNA damage response (DDR) is a complex signaling network that allows cells to respond to all sorts of genotoxic insults. Hypoxia is known to modulate the DDR and play a role affecting the survival capacity of different cell types. In this study, we have characterized in detail the DDR of cortical and medullary TEC lines and their response to ionizing radiation, as well as the effects of hypoxia on their DDR. Although both mTECs and cTECs display relatively high radio-resistance, mTEC cells have an increased survival capacity to ionizing radiation (IR)-induced DNA damage, and hypoxia specifically decreases the radio-resistance of mTECs by upregulating the expression of the pro-apoptotic factor Bim. Analysis of the expression of TEC functional factors by primary mouse TECs showed a marked decrease of highly important genes for TEC function and confirmed cTECs as the most affected cell type by IR. These findings have important implications for improving the outcomes of BMT and promoting successful T cell reconstitution.
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Project description:The cellular response to DNA damage is vital for maintaining genomic stability and preventing undue cell death or cancer formation. The DNA damage response (DDR), most robustly mobilized by double-strand breaks (DSBs), rapidly activates an extensive signaling network that affects numerous cellular systems, leading to cell survival or programmed cell death. A major component of the DDR is the widespread modulation of gene expression. We analyzed together six datasets that probed transcriptional responses to ionizing radiation (IR) - our novel experimental data and 5 published datasets - to elucidate the scope of this response and identify its gene targets. According to the mRNA expression profiles we recorded from 5 cancerous and non-cancerous human cell lines after exposure to 5 Gy of IR, most of the responses were cell line-specific. Computational analysis identified significant enrichment for p53 target genes and cell cycle-related pathways among groups of up-regulated and down-regulated genes, respectively. Computational promoter analysis of the six datasets disclosed that a statistically significant number of the induced genes contained p53 binding site signatures. p53-mediated regulation had previously been documented for subsets of these gene groups, making our lists a source of novel potential p53 targets. Real-time qPCR and chromatin immunoprecipitation (ChIP) assays validated the IR-induced p53-dependent induction and p53 binding to the respective promoters of 11 selected genes. Our results demonstrate the power of a combined computational and experimental approach to identify new transcriptional targets in the DNA damage response network.
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