scholarly journals Cell cycle repression and DNA repair defects follow constricted migration

2017 ◽  
Author(s):  
Charlotte R. Pfeifer ◽  
Yuntao Xia ◽  
Kuangzheng Zhu ◽  
Dazhen Liu ◽  
Jerome Irianto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Nuclear Lamina ◽  
Contact Inhibition ◽  
Dna Breaks ◽  
Lamin B1 ◽  
Cell Cycle Dependence ◽  
Repair Factor ◽  
Cycle Dependence

AbstractCancer cell invasion into tissue or narrow capillaries often elongates the nucleus and sometimes damages it, but cell cycle effects are unknown and highly relevant to tumorigenesis. Here, nuclear rupture and DNA breaks caused by constricted migration are quantified in different phases of cell cycle - which is effectively repressed. Cancer lines with varying levels of contact inhibition and lamina proteins exhibit diverse frequencies of nuclear lamina rupture after migration, with prerupture dilation of gene-edited RFP-Lamin-B1 preceding DNA repair factor leakage in pressure-controlled distension. Post-migration rupture indeed associates with mis-localized DNA repair factors and increased DNA breaks as quantified by pan-nucleoplasmic foci of γH2AX, with foci counts always suppressed in late cell cycle. When contact-inhibited cells migrate through large pores into sparse microenvironments, cells re-enter cell cycle consistent with release from contact inhibition. In contrast, constricting pores effectively delay re-entry, but the excess DNA damage nonetheless exceeds any cell cycle dependence. Partial depletion of topoisomerase does not strongly affect cell cycle or the excess DNA damage, consistent with weak dependencies on replication stress. Constricted migration thus impacts cell cycle as well as DNA damage.

scholarly journals Lamin B1 acetylation slows the G1 to S cell cycle transition through inhibition of DNA repair

2021 ◽  
Author(s):  
Laura A Murray-Nerger ◽  
Joshua L Justice ◽  
Pranav Rekapalli ◽  
Josiah E Hutton ◽  
Ileana M Cristea
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Posttranslational Modifications ◽  
Cell Cycle Progression ◽  
Nuclear Periphery ◽  
Virus Production ◽  
Nuclear Lamina ◽  
Regulatory Function ◽  
Herpesvirus Type ◽  
Lamin B1

Abstract The integrity and regulation of the nuclear lamina is essential for nuclear organization and chromatin stability, with its dysregulation being linked to laminopathy diseases and cancer. Although numerous posttranslational modifications have been identified on lamins, few have been ascribed a regulatory function. Here, we establish that lamin B1 (LMNB1) acetylation at K134 is a molecular toggle that controls nuclear periphery stability, cell cycle progression, and DNA repair. LMNB1 acetylation prevents lamina disruption during herpesvirus type 1 (HSV-1) infection, thereby inhibiting virus production. We also demonstrate the broad impact of this site on laminar processes in uninfected cells. LMNB1 acetylation negatively regulates canonical nonhomologous end joining by impairing the recruitment of 53BP1 to damaged DNA. This defect causes a delay in DNA damage resolution and a persistent activation of the G1/S checkpoint. Altogether, we reveal LMNB1 acetylation as a mechanism for controlling DNA repair pathway choice and stabilizing the nuclear periphery.

scholarly journals Constricted migration increases DNA damage and independently represses cell cycle

2018 ◽  
Vol 29 (16) ◽  
pp. 1948-1962 ◽  
Author(s):  
Charlotte R. Pfeifer ◽  
Yuntao Xia ◽  
Kuangzheng Zhu ◽  
Dazhen Liu ◽  
Jerome Irianto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Cell Fate ◽  
Nuclear Lamina ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Cell Cycle Reentry ◽  
Γh2ax Foci ◽  
And Migration

Cell migration through dense tissues or small capillaries can elongate the nucleus and even damage it, and any impact on cell cycle has the potential to affect various processes including carcinogenesis. Here, nuclear rupture and DNA damage increase with constricted migration in different phases of cell cycle—which we show is partially repressed. We study several cancer lines that are contact inhibited or not and that exhibit diverse frequencies of nuclear lamina rupture after migration through small pores. DNA repair factors invariably mislocalize after migration, and an excess of DNA damage is evident as pan-­nucleoplasmic foci of phosphoactivated ATM and γH2AX. Foci counts are suppressed in late cell cycle as expected of mitotic checkpoints, and migration of contact-inhibited cells through large pores into sparse microenvironments leads also as expected to cell-cycle reentry and no effect on a basal level of damage foci. Constricting pores delay such reentry while excess foci occur independent of cell-cycle phase. Knockdown of repair factors increases DNA damage independent of cell cycle, consistent with effects of constricted migration. Because such migration causes DNA damage and impedes proliferation, it illustrates a cancer cell fate choice of “go or grow.”

scholarly journals ZGRF1 promotes end resection of DNA homologous recombination via forming complex with BRCA1/EXO1

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Shuang Yan ◽  
Man Song ◽  
Jie Ping ◽  
Shu-ting Lai ◽  
Xiao-yu Cao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Mammalian Cells ◽  
Cell Cycle Checkpoint ◽  
Dependent Manner ◽  
Dna Breaks ◽  
M Cell ◽  
End Resection

AbstractTo maintain genomic stability, the mammalian cells has evolved a coordinated response to DNA damage, including activation of DNA repair and cell cycle checkpoint processes. Exonuclease 1 (EXO1)-dependent excision of DNA ends is important for the initiation of homologous recombination (HR) repair of DNA breaks, which is thought to play a key role in activating the ATR-CHK1 pathway to induce G2/M cell cycle arrest. But the mechanism is still not fully understood. Here, we report that ZGRF1 forms complexes with EXO1 as well as other repair proteins and promotes DNA repair through HR. ZGRF1 is recruited to DNA damage sites in a MDC1-RNF8-BRCA1 dependent manner. Furthermore, ZGRF1 is important for the recruitment of RPA2 to DNA damage sites and the following ATR-CHK1 mediated G2/M checkpoint in response to irradiation. ZGRF1 null cells show increased sensitivity to many DNA-damaging agents, especially PARPi and irradiation. Collectively,our findings identify ZGRF1 as a novel regulator of DNA end resection and G2/M checkpoint. ZGRF1 is a potential target of radiation and PARPi cancer therapy.

scholarly journals Formation of higher-order nuclear Rad51 structures is functionally linked to p21 expression and protection from DNA damage-induced apoptosis

2002 ◽  
Vol 115 (1) ◽  
pp. 153-164 ◽  
Author(s):  
Elke Raderschall ◽  
Alex Bazarov ◽  
Jiangping Cao ◽  
Rudi Lurz ◽  
Avril Smith ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Mammalian Cells ◽  
Higher Order ◽  
Dna Breaks ◽  
Functional Link ◽  
Rad51 Protein ◽  
Induced Apoptosis ◽  
Recombinational Dna Repair

After exposure of mammalian cells to DNA damage, the endogenous Rad51 recombination protein is concentrated in multiple discrete foci, which are thought to represent nuclear domains for recombinational DNA repair. Overexpressed Rad51 protein forms foci and higher-order nuclear structures, even in the absence of DNA damage, in cells that do not undergo DNA replication synthesis. This correlates with increased expression of the cyclin-dependent kinase (Cdk) inhibitor p21. Following DNA damage, constitutively Rad51-overexpressing cells show reduced numbers of DNA breaks and chromatid-type chromosome aberrations and a greater resistance to apoptosis. In contrast, Rad51 antisense inhibition reduces p21 protein levels and sensitizes cells to etoposide treatment. Downregulation of p21 inhibits Rad51 foci formation in both normal and Rad51-overexpressing cells. Collectively, our results show that Rad51 expression, Rad51 foci formation and p21 expression are interrelated, suggesting a functional link between mammalian Rad51 protein and p21-mediated cell cycle regulation. This mechanism may contribute to a highly effective recombinational DNA repair in cell cycle-arrested cells and protection against DNA damage-induced apoptosis.

Inhibition of Poly ADP Ribose Polymerase (PARP) Activity Exerts Cytotoxic Effects on Chromosomal Instability Syndrome and Leukaemic Cell Lines: Potential for Anti-Leukaemia Therapy.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2647-2647
Author(s):  
Terry J. Gaymes ◽  
S. Shall ◽  
Farzin Farzaneh ◽  
Ghulam J. Mufti
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Cell Survival ◽  
Cell Lines ◽  
Chromosomal Instability ◽  
Parp Inhibitors ◽  
Dna Breaks ◽  
Leukaemic Cells ◽  
Parp Activity

Abstract Recent reports suggest that BrCA1−/− and BrCA2−/− cells can be selectively targeted for cell death through abrogation of their PARP activity. It is postulated that as a result of PARP inhibition, accumulation of single strand DNA breaks (SSB) leads to the replication fork collapse and conversion of SSB to double strand DNA breaks (DSB). The inability of repair defective cells such as BrCA2−/− to repair the DSB would lead to cell death. Exploitation of DNA repair defects using PARP inhibitors (PI) thus represents a more specific and less toxic form of therapy for a number of haematological malignancies. Chromosomal instability (CI) syndromes that have inherent defects in double strand DNA repair also have a uniformly high incidence of transformation to acute leukaemia or lymphoma. In order to test the efficacy of PI therapy we analysed CI cell lines, myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML) cell lines and the potential for combination therapy with inhibitors of DNA methyltransferase (DNMTi) or histone deacetylase inhibitors (HDACi). We report that cells from CI syndromes; Blooms syndrome, Fanconi Anaemia (FancD2 and FancA), Ataxia telancgectasia and Nijmegen break syndrome display abnormal cell cycle profiles and excessive apoptosis in response to the PI’s PJ34 (3μM) and EB47 (45μM). In contrast, normal control cells displayed standard cell cycle profiles and no apoptosis in response to PI at equivalent concentrations. Clonogenic cytotoxicity assays showed that CI syndrome cells exhibit between 30–75% cell survival compared with 100% cell survival in control cells (p<0.05) in response to PI. The homologous recombination (HR) DNA repair component, rad51 forms foci in response to DNA damage. In HR compromised cells, rad51 foci fail to form. In response to PI, immunofluorescent studies show that CI syndrome cells demonstrate severely reduced rad51 foci formation (<5%) compared to control cells (15%). This confirms that PI targets the HR deficiencies in CI syndrome cells. Histone γH2AX, phosphorylated in response to DSB had greatly increased foci formation in CI syndrome cells compared to control cells as a result of unrepaired DNA damage (25.3 vs 9.3%)(p<0.05). CI syndromes have increased transformation potential to the MDS and AML. Addition of 3μM PJ34 to the myelomonocytoid leukaemic/myelodysplastic cell line, P39 exhibited significant apoptosis, with a cell survival fraction of 65% compared to 100% in control cells (p<0.01). Immunofluorescent studies revealed reduced rad51 foci formation (6.3 vs 15%) and increased γH2AX foci formation (17.6 vs 9.3%)(p<0.01). Strikingly, we were also able to reproduce similar PI responses in the Jurkat T-cell leukaemic cell line. We next explored the use of PI in combination with DNMTi or HDACi. Whilst 3μM PJ34 offered only additive effects on decitabine cytotoxicity, a sub-optimal concentration (1μM) of PJ34 behaved synergistically with HDACi potentiating the cytotoxic effect of 200nM MS275 by 55% compared to MS275 alone (p<0.05) in P39 cells. In conclusion, we have shown that in a panel of CI syndrome and leukaemic cells, PI demonstrates significant cytotoxic responses. We also show that PI acts synergistically in combination with HDACi. Parp inhibitors can potentially exploit DSB repair defects in leukaemic cells paving the way for a targeted therapy for MDS and leukaemia.

scholarly journals HPF1 remodels the active site of PARP1 to enable the serine ADP-ribosylation of histones

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fa-Hui Sun ◽  
Peng Zhao ◽  
Nan Zhang ◽  
Lu-Lu Kong ◽  
Catherine C. L. Wong ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Active Site ◽  
Negative Charge ◽  
Structural Data ◽  
Dna Breaks ◽  
Adp Ribosylation ◽  
Local Conformation ◽  
Key Residues ◽  
Structural Insights

AbstractUpon binding to DNA breaks, poly(ADP-ribose) polymerase 1 (PARP1) ADP-ribosylates itself and other factors to initiate DNA repair. Serine is the major residue for ADP-ribosylation upon DNA damage, which strictly depends on HPF1. Here, we report the crystal structures of human HPF1/PARP1-CAT ΔHD complex at 1.98 Å resolution, and mouse and human HPF1 at 1.71 Å and 1.57 Å resolution, respectively. Our structures and mutagenesis data confirm that the structural insights obtained in a recent HPF1/PARP2 study by Suskiewicz et al. apply to PARP1. Moreover, we quantitatively characterize the key residues necessary for HPF1/PARP1 binding. Our data show that through salt-bridging to Glu284/Asp286, Arg239 positions Glu284 to catalyze serine ADP-ribosylation, maintains the local conformation of HPF1 to limit PARP1 automodification, and facilitates HPF1/PARP1 binding by neutralizing the negative charge of Glu284. These findings, along with the high-resolution structural data, may facilitate drug discovery targeting PARP1.

scholarly journals The Interactions of DNA Repair, Telomere Homeostasis, and p53 Mutational Status in Solid Cancers: Risk, Prognosis, and Prediction

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 479
Author(s):  
Pavel Vodicka ◽  
Ladislav Andera ◽  
Alena Opattova ◽  
Ludmila Vodickova
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Dna Lesions ◽  
Cell Cycle Checkpoint ◽  
Solid Cancer ◽  
Genomic Integrity ◽  
Repair Capacity ◽  
Mutational Status ◽  
Telomere Homeostasis

The disruption of genomic integrity due to the accumulation of various kinds of DNA damage, deficient DNA repair capacity, and telomere shortening constitute the hallmarks of malignant diseases. DNA damage response (DDR) is a signaling network to process DNA damage with importance for both cancer development and chemotherapy outcome. DDR represents the complex events that detect DNA lesions and activate signaling networks (cell cycle checkpoint induction, DNA repair, and induction of cell death). TP53, the guardian of the genome, governs the cell response, resulting in cell cycle arrest, DNA damage repair, apoptosis, and senescence. The mutational status of TP53 has an impact on DDR, and somatic mutations in this gene represent one of the critical events in human carcinogenesis. Telomere dysfunction in cells that lack p53-mediated surveillance of genomic integrity along with the involvement of DNA repair in telomeric DNA regions leads to genomic instability. While the role of individual players (DDR, telomere homeostasis, and TP53) in human cancers has attracted attention for some time, there is insufficient understanding of the interactions between these pathways. Since solid cancer is a complex and multifactorial disease with considerable inter- and intra-tumor heterogeneity, we mainly dedicated this review to the interactions of DNA repair, telomere homeostasis, and TP53 mutational status, in relation to (a) cancer risk, (b) cancer progression, and (c) cancer therapy.

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