Cellular responses to genotoxic agents: DNA repair, activation of transcription, cell cycle arrest and apoptosis

1994 ◽  
Vol 91 ◽  
pp. 1005-1010 ◽  
Author(s):  
M Bouvrette ◽  
B Gowans ◽  
L Yu ◽  
J Stankova ◽  
D Hunting
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Cellular Responses ◽  
Cycle Arrest ◽  
Activation Of Transcription ◽  
Genotoxic Agents

scholarly journals Role of Mis Localization of DNA Repair Factors in Cell Cycle Arrest

2019 ◽  
Vol 116 (3) ◽  
pp. 76a
Author(s):  
Manasvita Vashisth ◽  
Sangkyun Cho ◽  
Dennis Discher
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Cycle Arrest

scholarly journals HIV-1 Vpr activates host CRL4-DCAF1 E3 ligase to degrade histone deacetylase SIRT7

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Xiaohong Zhou ◽  
Christina Monnie ◽  
Maria DeLucia ◽  
Jinwoo Ahn
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Histone Deacetylase ◽  
E3 Ligase ◽  
Cycle Arrest ◽  
Wide Range ◽  
In Vitro Reconstitution ◽  
Hiv 1

Abstract Background Vpr is a virion-associated protein that is encoded by lentiviruses and serves to counteract intrinsic immunity factors that restrict infection. HIV-1 Vpr mediates proteasome-dependent degradation of several DNA repair/modification proteins. Mechanistically, Vpr directly recruits cellular targets onto DCAF1, a substrate receptor of Cullin 4 RING E3 ubiquitin ligase (CRL4) for poly-ubiquitination. Further, Vpr can mediate poly-ubiquitination of DCAF1-interacting proteins by the CRL4. Because Vpr-mediated degradation of its known targets can not explain the primary cell-cycle arrest phenotype that Vpr expression induces, we surveyed the literature for DNA-repair-associated proteins that interact with the CRL4-DCAF1. One such protein is SIRT7, a deacetylase of histone 3 that belongs to the Sirtuin family and regulates a wide range of cellular processes. We wondered whether Vpr can mediate degradation of SIRT7 via the CRL4-DCAF1. Methods HEK293T cells were transfected with cocktails of plasmids expressing DCAF1, DDB1, SIRT7 and Vpr. Ectopic and endogeneous levels of SIRT7 were monitered by immunoblotting and protein–protein interactions were assessed by immunoprecipitation. For in vitro reconstitution assays, recombinant CRL4-DCAF1-Vpr complexes and SIRT7 were prepared and poly-ubiqutination of SIRT7 was monitored with immunoblotting. Results We demonstrate SIRT7 polyubiquitination and degradation upon Vpr expression. Specifically, SIRT7 is shown to interact with the CRL4-DCAF1 complex, and expression of Vpr in HEK293T cells results in SIRT7 degradation, which is partially rescued by CRL inhibitor MNL4924 and proteasome inhibitor MG132. Further, in vitro reconstitution assays show that Vpr induces poly-ubiquitination of SIRT7 by the CRL4-DCAF1. Importantly, we find that Vpr from several different HIV-1 strains, but not HIV-2 strains, mediates SIRT7 poly-ubiquitination in the reconstitution assay and degradation in cells. Finally, we show that SIRT7 degradation by Vpr is independent of the known, distinctive phenotype of Vpr-induced cell cycle arrest at the G2 phase, Conclusions Targeting histone deacetylase SIRT7 for degradation is a conserved feature of HIV-1 Vpr. Altogether, our findings reveal that HIV-1 Vpr mediates down-regulation of SIRT7 by a mechanism that does not involve novel target recruitment to the CRL4-DCAF1 but instead involves regulation of the E3 ligase activity.

scholarly journals High-intensity Raf signal causes cell cycle arrest mediated by p21Cip1.

1997 ◽  
Vol 17 (9) ◽  
pp. 5588-5597 ◽  
Author(s):  
A Sewing ◽  
B Wiseman ◽  
A C Lloyd ◽  
H Land
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Arrest ◽  
Expression Patterns ◽  
Cellular Responses ◽  
Specific Cell ◽  
Cyclin D ◽  
Inhibition Of Proliferation ◽  
Cycle Arrest ◽  
Signal Specificity

Activated Raf has been linked to such opposing cellular responses as the induction of DNA synthesis and the inhibition of proliferation. However, it remains unclear how such a switch in signal specificity is regulated. We have addressed this question with a regulatable Raf-androgen receptor fusion protein in murine fibroblasts. We show that Raf can cause a G1-specific cell cycle arrest through induction of p21Cip1. This in turn leads to inhibition of cyclin D- and cyclin E-dependent kinases and an accumulation of hypophosphorylated Rb. Importantly, this behavior can be observed only in response to a strong Raf signal. In contrast, moderate Raf activity induces DNA synthesis and is sufficient to induce cyclin D expression. Therefore, Raf signal specificity can be determined by modulation of signal strength presumably through the induction of distinct protein expression patterns. Similar to induction of Raf, a strong induction of activated Ras via a tetracycline-dependent promoter also causes inhibition of proliferation and p21Cip1 induction at high expression levels. Thus, p21Cip1 plays a key role in determining cellular responses to Ras and Raf signalling. As predicted by this finding we show that Ras and loss of p21 cooperate to confer a proliferative advantage to mouse embryo fibroblasts.

scholarly journals XRRA1 Targets ATM/CHK1/2-Mediated DNA Repair in Colorectal Cancer

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Wenjun Wang ◽  
Minzhang Guo ◽  
Xiaojun Xia ◽  
Chao Zhang ◽  
Yuan Zeng ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Human Tumor ◽  
Repair Pathway ◽  
X Ray ◽  
Cycle Arrest ◽  
Damage Response ◽  
P21 Proteins

X-ray radiation resistance associated 1 (XRRA1) has been found to regulate the response of human tumor and normal cells to X-radiation (XR). Although XRRA1 overexpression is known to be involved in cancer cell response to XR, there are no reports about whether the expression of XRRA1 in tumors can adjust radioresistance. It is widely known that cell cycle arrest could cause radioresistance. We found that blocked XRRA1 expression could lead to cell cycle G2/M arrest by the regulation of cyclin A, cyclin E, and p21 proteins in colorectal cancer (CRC) and expression of XRRA1 reduced cell cycle arrest and increased cell proliferation in CRC. However, whether regulation of the cell cycle by XRRA1 can influence radioresistance is poorly characterized. Correspondingly, DNA repair can effectively lead to radioresistance. In our study, when cancer cells were exposed to drugs and ionizing radiation, low expression of XRRA1 could increase the phosphorylation of DNA repair pathway factors CHK1, CHK2, and ATM and reduce the expression of γ-H2AX, which is believed to participate in DNA repair in the nucleus. Crucially, our results identify a novel link between XRRA1 and the ATM/CHK1/2 pathway and suggest that XRRA1 is involved in a DNA damage response that drives radio- and chemoresistance by regulating the ATM/CHK1/2 pathway.

Light-mediated DNA Repair Prevents UVB-induced Cell Cycle Arrest in Embryos of the CrustaceanMacrobrachium olfersi

2015 ◽  
Vol 91 (4) ◽  
pp. 869-878 ◽  
Author(s):  
Eliane Cristina Zeni ◽  
Dib Ammar ◽  
Mayana Lacerda Leal ◽  
Heloisa Schramm da Silva ◽  
Silvana Allodi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Cycle Arrest

scholarly journals HIV-1 Vpr activates host CRL4-DCAF1 E3 ligase to degrade histone deacetylase SIRT7

2020 ◽  
Author(s):  
Xiaohong Zhou ◽  
Christina Monnie ◽  
maria Delucia ◽  
jinwoo ahn
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Histone Deacetylase ◽  
E3 Ligase ◽  
Cycle Arrest ◽  
Wide Range ◽  
In Vitro Reconstitution ◽  
Hiv 1

Abstract Background: Vpr is a virion-associated protein that is encoded by lentiviruses and serves to counteract intrinsic immunity factors that restrict infection. HIV-1 Vpr mediates proteasome-dependent degradation of several DNA repair/modification proteins. Mechanistically, Vpr directly recruits cellular targets onto DCAF1, a substrate receptor of Cullin 4 RING E3 ubiquitin ligase (CRL4) for poly-ubiquitination. Further, Vpr can mediate poly-ubiquitination of DCAF1-interacting proteins by the CRL4. Because Vpr-mediated degradation of its known targets can not explain the primary cell-cycle arrest phenotype that Vpr expression induces, we surveyed the literature for DNA-repair-associated proteins that interact with the CRL4-DCAF1. One such protein is SIRT7, a deacetylase of histone 3 that belongs to the Sirtuin family and regulates a wide range of cellular processes. We wondered whether Vpr can mediate degradation of SIRT7 via the CRL4-DCAF1. Methods: HEK293T cells were transfected with cocktails of plasmids expressing DCAF1, DDB1, SIRT7 and Vpr. Ectopic and endogeneous levels of SIRT7 were monitered by immunoblotting and protein-protein interactions were assessed by immunoprecipitation. For in vitro reconstitution assays, recombinant CRL4-DCAF1-Vpr complexes and SIRT7 were prepared and poly-ubiqutination of SIRT7 was monitored with immunoblotting. Results: We demonstrate SIRT7 polyubiquitination and degradation upon Vpr expression. Specifically, SIRT7 is shown to interact with the CRL4-DCAF1 complex, and expression of Vpr in HEK293T cells results in SIRT7 degradation, which is partially rescued by CRL inhibitor MNL4924 and proteasome inhibitor MG132. Further, in vitro reconstitution assays show that Vpr induces poly-ubiquitination of SIRT7 by the CRL4-DCAF1. Importantly, we find that Vpr from several different HIV-1 strains, but not HIV-2 strains, mediates SIRT7 poly-ubiquitination in the reconstitution assay and degradation in cells. Finally, we show that SIRT7 degradation by Vpr is independent of the known, distinctive phenotype of Vpr-induced cell cycle arrest at the G2 phase, Conclusions: Targeting histone deacetylase SIRT7 for degradation is a conserved feature of HIV-1 Vpr. Altogether , our findings reveal that HIV-1 Vpr mediates down-regulation of SIRT7 by a mechanism that does not involve novel target recruitment to the CRL4-DCAF1 but instead involves regulation of the E3 ligase activity.

Bone Marrow Mesenchymal Stem Cells Affect The Cell Cycle Arrest Effect Of Genotoxic Agents On Acute Lymphocytic Leukemia Cells Via p21 Down-Regulation

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4988-4988
Author(s):  
Yiran Zhang ◽  
Kaimin Hu ◽  
Yongxian Hu ◽  
Binsheng Wang ◽  
He Huang
Keyword(s):  
Cell Cycle ◽  
Bone Marrow ◽  
Cell Cycle Arrest ◽  
Acute Lymphocytic Leukemia ◽  
Lymphocytic Leukemia ◽  
Phase Ratio ◽  
Down Regulation ◽  
Cycle Arrest ◽  
Genotoxic Agents ◽  
Reh Cells

Abstract The recurrence rate of acute lymphocytic leukemia (ALL) in adult is high, and the five-year survival rate of recurrent patients is as low as 7%. Increasing evidence indicates that bone marrow mesenchymal stem cell (BMSC), which is a pivotal component of the bone marrow microenvironment, can enhance the survival and drug resistance of ALL cells, which is a reason for the high recurrence rate of ALL in adult. However, whether BMSCs promote or block the cell-cycle and proliferation of leukemia is indefinite, and whether BMSCs affects the the cell cycle arrest effect of genotoxic agents on ALL cells is unclear. In this study, human BMSCs was obtained from normal bone marrow donors, and ALL cell line Reh was cultured with or without BMSCs in the presence or absence of etoposide (VP16) or idarubicin (IDA). MLN4924, the inhibitor of SCF complex, was used to induce the high expression of cell-cycle inhibitor p21. The proliferation of ALL cells was detected by CCK-8 kit and cell cycle was analyzed by flow cytometry with PI staining. The protein expression of ALL cells was determined by western blot and the mRNA expression was detected by qRT-PCR. The results indicated that BMSCs affected the cell cycle arrest effect of genotoxic agents on ALL cells. In the absence of drugs, BMSCs had no significant effect on the cell-cycle of Reh cells. Under the treatment of VP16, the S phase ratio of Reh cultured with BMSCs was higher than Reh cultured alone (10.893±1.077% and 6.842±0.652% respectively, p<0.05), the G2/M phase ratio of Reh cultured with BMSCs was lower than Reh cultured alone (25.812±1.720% and 38.818±3.508% respectively, p<0.05). Under the treatment of IDA, the S phase ratio of Reh cultured with BMSCs was higher than Reh cultured alone (58.720±5.765% and 45.519±7.886% respectively, p<0.05), the G2/M phase ratio of Reh cultured with BMSCs was lower than Reh cultured alone (1.888±0.809% and 6.449±0.325% respectively, p<0.05). At both protein and mRNA level, treatment of VP16 or IDA induced the expression of p21 in Reh cells, while BMSCs down-regulated its expression. MLN4924-induced p21 high expression in Reh cells eliminated the cell-cycle promotion effect of BMSCs on Reh cells under the treatment of genotoxic agents, which confirmed that BMSCs affect the cell cycle arrest effect of genotoxic agents on ALL cells via p21 down-regulation. Moreover, in the presence of VP16 or IDA, BMSCs reduced the p53 mRNA expression and increase the c-myc mRNA expression in Reh cells, and BMSCs also up-regulated the protein expression of p-Erk and β-catenin in Reh cells. Since p53 is the major transcription factor of p21 and c-myc is the transcription inhibitor of p21, our results suggested that the BMSCs induced down-regulation of p21 in ALL cells might be through down-regulation of p53 and activation of Wnt/β-catenin/c-myc and erk/c-myc pathways. In conclusion, the present study indicates that BMSCs affect the cell cycle arrest effect of genotoxic agents on acute lymphocytic leukemia cells via p21 down-regulation. This finding suggests that targeting the effect of microenvironment on leukemia might be a novel approach for ALL therapy. Disclosures: No relevant conflicts of interest to declare.

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