On the regulation of the p53 tumour suppressor, and its role in the cellular response to DNA damage

1995 ◽  
Vol 347 (1319) ◽  
pp. 83-87 ◽  
Keyword(s):  
Dna Damage ◽  
Ionizing Radiation ◽  
Mammalian Cells ◽  
Cellular Response ◽  
P53 Gene ◽  
Viral Proteins ◽  
Biologically Active ◽  
Discrete Control ◽  
Apoptotic Response ◽  
P53 Activation

The p53 gene is required for the normal apoptotic response of mammalian cells to DNA damage caused by ionizing radiation and DNA damaging drugs. DNA damage results in the accumulation of biologically active p53. This response is potentially lethal and is therefore highly regulated. By using both biochemical and cell biological approaches a number of discrete control pathways have been identified. These include analysis of cellular and viral proteins that bind to p53 to inactivate its function, the discovery of cells with defects in the p53 activation pathway and the analysis of an allosteric regulation of p53 function controlled by phosphorylation.

scholarly journals MORC2 regulates DNA damage response through a PARP1-dependent pathway

2019 ◽  
Vol 47 (16) ◽  
pp. 8502-8520 ◽  
Author(s):  
Lin Zhang ◽  
Da-Qiang Li
Keyword(s):  
Dna Damage ◽  
Zinc Finger ◽  
Chromatin Remodeling ◽  
Dna Damage Response ◽  
Mammalian Cells ◽  
Cellular Response ◽  
Genotoxic Stress ◽  
Underlying Mechanism ◽  
Dna Lesions ◽  
Damage Response

Abstract Microrchidia family CW-type zinc finger 2 (MORC2) is a newly identified chromatin remodeling enzyme with an emerging role in DNA damage response (DDR), but the underlying mechanism remains largely unknown. Here, we show that poly(ADP-ribose) polymerase 1 (PARP1), a key chromatin-associated enzyme responsible for the synthesis of poly(ADP-ribose) (PAR) polymers in mammalian cells, interacts with and PARylates MORC2 at two residues within its conserved CW-type zinc finger domain. Following DNA damage, PARP1 recruits MORC2 to DNA damage sites and catalyzes MORC2 PARylation, which stimulates its ATPase and chromatin remodeling activities. Mutation of PARylation residues in MORC2 results in reduced cell survival after DNA damage. MORC2, in turn, stabilizes PARP1 through enhancing acetyltransferase NAT10-mediated acetylation of PARP1 at lysine 949, which blocks its ubiquitination at the same residue and subsequent degradation by E3 ubiquitin ligase CHFR. Consequently, depletion of MORC2 or expression of an acetylation-defective PARP1 mutant impairs DNA damage-induced PAR production and PAR-dependent recruitment of DNA repair proteins to DNA lesions, leading to enhanced sensitivity to genotoxic stress. Collectively, these findings uncover a previously unrecognized mechanistic link between MORC2 and PARP1 in the regulation of cellular response to DNA damage.

scholarly journals Interaction between Fibroblasts and Immune Cells Following DNA Damage Induced by Ionizing Radiation

2020 ◽  
Author(s):  
Kalaiyarasi Ragunathan ◽  
Nikki Lyn Esnardo Upfold ◽  
Valentyn Oksenych
Keyword(s):  
Dna Damage ◽  
Tumor Microenvironment ◽  
Ionizing Radiation ◽  
Immune Cells ◽  
Mammalian Cells ◽  
Cancer Associated Fibroblasts ◽  
Cell Type ◽  
Dna Damages ◽  
Damage Response ◽  
High Doses

Cancer-associated fibroblasts (CAF) form the basis of tumor microenvironment and possess immunomodulatory functions by interacting with other cells surrounding tumor, including T lymphocytes, macrophages, dendritic cells and natural killer cells. Ionizing radiation is a broadly-used method in radiotherapy to target tumors. In mammalian cells, ionizing radiation induces various types of DNA damages and DNA damage response. Being unspecific, radiotherapy affects all the cells in tumor microenvironment, including the tumor itself, CAFs and immune cells. CAFs are extremely radio-resistant and do not initiate apoptosis even at high doses of radiation. However, following radiation, CAFs become senescent and produce a distinct combination of immunoregulatory molecules. Radiosensitivity of immune cells varies depending on the cell type due to inefficient DNA repair in, for example, monocytes and granulocytes. In this minireview, we are summarizing recent findings on the interaction between CAF, ionizing radiation and immune cells in the tumor microenvironment.

Zap-70 and IgVH Mutation Status in Combination with p53 Functional Analysis Identifies the Response of Poor Prognosis B-CLL Patients to Conventional Cytotoxic Agents.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1907-1907 ◽  
Author(s):  
N. I. Folarin ◽  
R. J. Baker ◽  
V. Duke ◽  
B. C. Yogashangary ◽  
C. Vadikolia ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ionizing Radiation ◽  
Poor Prognosis ◽  
Parp Cleavage ◽  
Malignant Cells ◽  
Apoptotic Response ◽  
P53 Pathway ◽  
Mutation Status ◽  
Mutational Status ◽  
Igvh Mutational Status

Abstract B-Chronic lymphocytic leukemia (B-CLL) patients whose malignant cells harbour unmutated immunoglobulin heavy chain variable region (IgVH) genes or express the zeta-associated protein tyrosine kinase ZAP-70 show a worse prognosis than do patients with mutated IgVH genes or ZAP-70−ve expression. The inability of malignant cells to activate the pro-apoptotic p53 pathway in response to ionizing radiation (IR) also correlates with a poor prognosis. We studied ZAP-70 expression and IgVH mutation status in 161 patients with B-CLL in order to determine the degree of concordance between these two prognostic criteria (M104/F57, wbc 2.44–576x109/l lymphocytes 0.56–287x109/l). We also studied the functional status of the p53 pathway and the apoptotic response to ionizing radiation in cells from a subset of patients from both prognostic categories. A human ZAP-70 antibody (clone 2F3-2) was conjugated to the Alexa Fluor 488 dye using a zenon mouse IgG labelling kit and used for a FACS based assay. FACS results were expressed as a ratio of B-cell mean cell fluorescence to T-cell mean cell fluorescence with a cut off at > 0.75 identifying a ZAP-70+ve sub-group. IgVH mutational status was studied by sequence analysis of FR1/JH polymerase chain reaction products. The ability of 5Gy ionizing radiation to augment levels of p53 and its transcriptional target p21CIP1 was quantified by western blot analysis. Cleavage of the caspase 3 target poly(ADP ribose) polymerase (PARP) was used as a measure of apoptosis induction. ZAP-70+ve expression was observed in 25% (41/161) of the samples with a median ratio of 0.85 (range 0.76–1.46) while the remaining 120 samples were ZAP-70−ve, with a median ratio of 0.56 (range 0.19–0.73). IgVH mutation status was analysed in 92 of these patients. Assignment of prognostic category by both criteria was concordant in 72/92 (78.2%) of the cases of which 54/92 (58.6%) were ZAP−ve/IgVH mutated (good prognosis) and 18/92 (19.5%) were ZAP+ve/IgVH unmutated (poor prognosis) patients. The remaining 21.7% were discordant, ie., either ZAP+ve/IgVH mutated (5.4%) or ZAP−ve/IgVH unmutated (16.3%). Isolates from 5/6 ZAP+ve/IgVH unmutated patients upregulated p53 in response to IR but nevertheless failed to initiate PARP cleavage, suggestive of a block in the apoptotic pathway distal to p53 induction. In 9 ZAP−ve/IgVH mutated isolates studied, 7 induced p53, p21 and PARP cleavage following IR. In conclusion, this large cohort of CLL patients demonstrated a good correlation between ZAP-70 expression and IgVH mutational status in identifying a poor prognosis sub-group. However, this prognostic category, as defined by both IgVH mutation status and ZAP-70 expression failed in some cases to predict the ability of B-CLL cells to induce an apoptotic response to DNA damage in vitro. Induction of the p53 pathway was not always sufficient to secure an apoptotic response, especially in the poor prognosis group. A combination of ZAP-70 and IgVH analysis with a functional assay for DNA damage-induced apoptosis will identify individuals in either prognostic category who are unlikely to respond to conventional cytotoxic drugs. Alternative therapeutic strategies independent of DNA damage-inducing agents may be of value in the treatment of these patients.

scholarly journals hSnm1 Colocalizes and Physically Associates with 53BP1 before and after DNA Damage

2002 ◽  
Vol 22 (24) ◽  
pp. 8635-8647 ◽  
Author(s):  
Christopher T. Richie ◽  
Carolyn Peterson ◽  
Tao Lu ◽  
Walter N. Hittelman ◽  
Phillip B. Carpenter ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ionizing Radiation ◽  
Cellular Response ◽  
Alkylating Agents ◽  
Crosslinking Agent ◽  
Physical Interaction ◽  
Nuclear Staining ◽  
Focus Formation ◽  
Before And After ◽  
Interstrand Crosslinking

ABSTRACT snm1 mutants of Saccharomyces cerevisiae have been shown to be specifically sensitive to DNA interstrand crosslinking agents but not sensitive to monofunctional alkylating agents, UV, or ionizing radiation. Five homologs of SNM1 have been identified in the mammalian genome and are termed SNM1, SNM1B, Artemis, ELAC2, and CPSF73. To explore the functional role of human Snm1 in response to DNA damage, we characterized the cellular distribution and dynamics of human Snm1 before and after exposure to DNA-damaging agents. Human Snm1 was found to localize to the cell nucleus in three distinct patterns. A particular cell showed diffuse nuclear staining, multiple nuclear foci, or one or two larger bodies confined to the nucleus. Upon exposure to ionizing radiation or an interstrand crosslinking agent, the number of cells exhibiting Snm1 bodies was reduced, while the population of cells with foci increased dramatically. Indirect immunofluorescence studies also indicated that the human Snm1 protein colocalized with 53BP1 before and after exposure to ionizing radiation, and a physical interaction was confirmed by coimmunoprecipitation assays. Furthermore, human Snm1 foci formed after ionizing radiation were largely coincident with foci formed by human Mre11 and to a lesser extent with those formed by BRCA1, but not with those formed by human Rad51. Finally, we mapped a region of human Snm1 of approximately 220 amino acids that was sufficient for focus formation when attached to a nuclear localization signal. Our results indicate a novel function for human Snm1 in the cellular response to double-strand breaks formed by ionizing radiation.

scholarly journals Genomic Expression Responses to DNA-damaging Agents and the Regulatory Role of the Yeast ATR Homolog Mec1p

2001 ◽  
Vol 12 (10) ◽  
pp. 2987-3003 ◽  
Author(s):  
Audrey P. Gasch ◽  
Mingxia Huang ◽  
Sandra Metzner ◽  
David Botstein ◽  
Stephen J. Elledge ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Ionizing Radiation ◽  
Cellular Response ◽  
Expression Patterns ◽  
Wild Type ◽  
Data Set ◽  
Genomic Expression ◽  
Dna Damaging Agents

Eukaryotic cells respond to DNA damage by arresting the cell cycle and modulating gene expression to ensure efficient DNA repair. The human ATR kinase and its homolog in yeast, MEC1, play central roles in transducing the damage signal. To characterize the role of the Mec1 pathway in modulating the cellular response to DNA damage, we used DNA microarrays to observe genomic expression inSaccharomyces cerevisiae responding to two different DNA-damaging agents. We compared the genome-wide expression patterns of wild-type cells and mutants defective in Mec1 signaling, includingmec1, dun1, and crt1 mutants, under normal growth conditions and in response to the methylating-agent methylmethane sulfonate (MMS) and ionizing radiation. Here, we present a comparative analysis of wild-type and mutant cells responding to these DNA-damaging agents, and identify specific features of the gene expression responses that are dependent on the Mec1 pathway. Among the hundreds of genes whose expression was affected by Mec1p, one set of genes appears to represent an MEC1-dependent expression signature of DNA damage. Other aspects of the genomic responses were independent of Mec1p, and likely independent of DNA damage, suggesting the pleiotropic effects of MMS and ionizing radiation. The complete data set as well as supplemental materials is available at http://www-genome.stanford.edu/mec1 .

scholarly journals NLRP3 controls ATM activation in response to DNA damage

2020 ◽  
Author(s):  
Mélanie Bodnar-Wachtel ◽  
Anne-Laure Huber ◽  
Julie Gorry ◽  
Sabine Hacot ◽  
Laetitia Gerossier ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cellular Response ◽  
Dna Double Strand Breaks ◽  
Functional Link ◽  
Atm Kinase ◽  
Damage Sensing ◽  
Pathway Activation ◽  
Genomic Stress ◽  
P53 Activation ◽  
Atm Signaling

ABSTRACTThe DNA damage response (DDR) is essential to preserve genomic integrity and acts as a barrier to cancer. The ATM pathway orchestrates the cellular response to DNA double strand breaks (DSBs), and its attenuation is frequent during tumorigenesis. Here, we show that NLRP3, a Pattern Recognition Receptor known for its role in the inflammasome complex formation, interacts with the ATM kinase to control the early phase of DDR, independently of its inflammasome activity. NLRP3 down-regulation in human bronchial epithelial cells impairs ATM pathway activation as shown by an altered ATM substrate phosphorylation profile, and due to impaired p53 activation, confers resistance to acute genomic stress. Moreover, we found that NLRP3 is down-regulated in Non-Small Cell Lung Cancer (NSCLC) tissues and NLRP3 expression is correlated with patient overall survival. NLRP3 re-expression in NSCLC cells restores appropriate ATM signaling. Our findings identify a non-immune function for NLRP3 in genome integrity surveillance and strengthen the concept of a functional link between innate immunity and DNA damage sensing pathways.

scholarly journals MicroRNAs, cancer and ionizing radiation: Where are we?

2015 ◽  
Vol 61 (3) ◽  
pp. 275-281 ◽  
Author(s):  
Gustavo Nader Marta ◽  
Bernardo Garicochea ◽  
André Lopes Carvalho ◽  
Juliana M. Real ◽  
Luiz Paulo Kowalski
Keyword(s):  
Dna Damage ◽  
Ionizing Radiation ◽  
Tumor Suppressor Genes ◽  
Cellular Response ◽  
Regulation Mechanism ◽  
Future Studies ◽  
New Class ◽  
Damage Repair ◽  
Mature Microrna ◽  
Damage Response

Summary The aim of this study is to describe the biogenesis of microRNA, its relations with carcinogenesis, and the correlation between microRNA and ionizing radiation (IR), focusing on radioresponsiveness. It is known that microRNA biogenesis is well established and involves different enzymatic cleavages, resulting in the production of mature microRNA. MicroRNAs are involved in carcinogenesis. Their interaction is related to the genetic and epigenetic changes associated with activation of proto-oncogenes or inactivation of tumor suppressor genes. Several studies have shown that the levels of expression of some microRNAs vary significantly after irradiation. There are evidences that microRNAs can influence cellular response after IR. In addition, microRNAs are related to modulation of the expression of several post-transcriptional targets in DNA damage response pathways, and to the DNA damage repair regulation mechanism. Future studies can clarify a possible clinical use of microRNAs as a new class of radiosensitive agents.

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