scholarly journals An adaptive pre-DNA-damage-response protects genome integrity

2020 ◽  
Author(s):  
Sandrine Ragu ◽  
Gabriel Matos-Rodrigues ◽  
Nathalie Droin ◽  
Aurélia Barascu ◽  
Sylvain Caillat ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Cell Cycle Progression ◽  
Replication Stress ◽  
Nuclear Accumulation ◽  
Genome Integrity ◽  
Cycle Progression ◽  
Stress Threshold ◽  
Damage Response

AbstractThe DNA damage response (DDR) interrupts cell cycle progression to restore genome integrity. However, unchallenged proliferating cells are continually exposed to endogenous stress, raising the question of a stress-threshold for DDR activation. Here, we identified a stress threshold below which primary human fibroblasts, activate a cell-autonomous response that not activates full DDR and not arrests cell cycle progression,. We characterized this “pre-DDR” response showing that it triggers the production of reactive oxygen species (ROS) by the NADPH oxidases DUOX1 and DUOX2, under the control of NF-κB and PARP1. Then, replication stress-induced ROS (RIR) activates the FOXO1 detoxifying pathway, preventing the nuclear accumulation of the pre-mutagenic 8-oxoGuanine lesion, upon endogenous as well as exogenous pro-oxidant stress. Increasing the replication stress severity above the threshold triggers the canonical DDR, leading to cell cycle progression arrest, but also to RIR suppression. These data reveal that cells adapt their response to stress severity, unveiling a tightly regulated ”pre-DDR” adaptive response that protects genome integrity without arresting cell cycle progression.

scholarly journals The Licensing Factor Cdt1 Links Cell Cycle Progression to the DNA Damage Response

2020 ◽  
Vol 40 (5) ◽  
pp. 2449-2456
Author(s):  
ALEXANDRA KANELLOU ◽  
NICKOLAOS NIKIFOROS GIAKOUMAKIS ◽  
ANDREAS PANAGOPOULOS ◽  
SPYRIDON CHAMPERIS TSANIRAS ◽  
ZOI LYGEROU
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Damage Response ◽  
Licensing Factor

scholarly journals Cellular responses to a prolonged delay in mitosis are determined by a DNA damage response controlled by Bcl-2 family proteins

Open Biology ◽  
2015 ◽  
Vol 5 (3) ◽  
pp. 140156 ◽  
Author(s):  
Didier J. Colin ◽  
Karolina O. Hain ◽  
Lindsey A. Allan ◽  
Paul R. Clarke
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Protein Kinases ◽  
Cell Fate ◽  
Dna Damage Response ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Anti Cancer ◽  
Damage Response ◽  
Microtubule Poisons

Anti-cancer drugs that disrupt mitosis inhibit cell proliferation and induce apoptosis, although the mechanisms of these responses are poorly understood. Here, we characterize a mitotic stress response that determines cell fate in response to microtubule poisons. We show that mitotic arrest induced by these drugs produces a temporally controlled DNA damage response (DDR) characterized by the caspase-dependent formation of γH2AX foci in non-apoptotic cells. Following exit from a delayed mitosis, this initial response results in activation of DDR protein kinases, phosphorylation of the tumour suppressor p53 and a delay in subsequent cell cycle progression. We show that this response is controlled by Mcl-1, a regulator of caspase activation that becomes degraded during mitotic arrest. Chemical inhibition of Mcl-1 and the related proteins Bcl-2 and Bcl-x L by a BH3 mimetic enhances the mitotic DDR, promotes p53 activation and inhibits subsequent cell cycle progression. We also show that inhibitors of DDR protein kinases as well as BH3 mimetics promote apoptosis synergistically with taxol (paclitaxel) in a variety of cancer cell lines. Our work demonstrates the role of mitotic DNA damage responses in determining cell fate in response to microtubule poisons and BH3 mimetics, providing a rationale for anti-cancer combination chemotherapies.

scholarly journals Zfp423, a Joubert syndrome gene, is a domain-specific regulator of cell cycle progression, DNA damage response and Purkinje cell development in the cerebellar primordium

2017 ◽  
Author(s):  
Filippo Casonil ◽  
Laura Crocil ◽  
Camilla Bosonel ◽  
Roberta D’Ambrosio ◽  
Aurora Badaloni ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Neural Development ◽  
Cell Cycle Progression ◽  
Ventricular Zone ◽  
Joubert Syndrome ◽  
Cycle Progression ◽  
Domain Specific ◽  
Damage Response

ABSTRACTNeurogenesis is a tightly regulated process whose success depends on the ability to balance the expansion/maintenance of an undifferentiated neural progenitor pool with the precisely timed birth of sequential generations of neurons. The Zfp423 gene encodes a 30-Zn-finger transcription factor (TF) that acts as a scaffold in the assembly of complex transcriptional and cellular machineries regulating neural development. While null mutants for Zfp423 feature a severe cerebellar hypoplasia, the underlying mechanism is only partially characterized. Mutations of the human ortholog ZNF423 have been identified in patients carrying cerebellar vermis hypoplasia (CVH) or Joubert Syndrome (JS), associated with other signs of classical ciliopathy outside the central nervous system (CNS). ZNF423 also plays a role in the DNA damage response (DDR). To further characterize the role of ZFP423 in cerebellar neurogenesis, with a focus on Purkinje cells (PC) development, we analyzed two previously undescribed mutant mouse lines carrying allelic in-frame deletions of the corresponding gene, selectively affecting two functionally characterized protein-protein interaction domains, affecting zinc (Zn) fingers 9-20 or 28-30. Some phenotypic defects are allele specific: Zfp423Δ9-20/Δ9-20 mutants exhibit a depletion of the OLIG2+ PC progenitor pool in the cerebellar ventricular zone (VZ). In these mutants, M-phase progenitors display changes in spindle orientation indicative of a precocious switch from symmetric to asymmetric cell division. Conversely, the Zfp423Δ28-30/Δ28-30 primordium displays a sharp decrease in the expression of PC differentiation markers, including CORL2, despite an abundance of cycling PC progenitors. Moreover, and importantly, in both mutants VZ progenitor cell cycle progression is remarkably affected, and factors involved in the DDR are substantially upregulated in the VZ and in postmitotic precursors alike. Our in vivo evidence sheds light on the domain-specific roles played by ZFP423 in different aspects of PC progenitor development, and at the same time supports the emerging notion that an impaired DNA damage response may be a key factor in the pathogenesis of JS and other ciliopathies.

scholarly journals Author response: Eya2 promotes cell cycle progression by regulating DNA damage response during vertebrate limb regeneration

2020 ◽  
Author(s):  
Konstantinos Sousounis ◽  
Donald M Bryant ◽  
Jose Martinez Fernandez ◽  
Samuel S Eddy ◽  
Stephanie L Tsai ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Cell Cycle Progression ◽  
Limb Regeneration ◽  
Author Response ◽  
Cycle Progression ◽  
Vertebrate Limb ◽  
Damage Response

The Capacity of the Hypomethylating Agents Azacytidine and Decitabine to Induce Apoptosis and Cell Cycle Arrest Depends on the Activation of the DNA-Damage Response Pathway.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1655-1655
Author(s):  
Simone Boehrer ◽  
Lionel Ades ◽  
Nicolas Tajeddine ◽  
Lorenzo Galluzzi ◽  
Stephane de Botton ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Cell Lines ◽  
Dna Damage Response ◽  
Cell Cycle Progression ◽  
Hypomethylating Agents ◽  
Cycle Progression ◽  
Cycle Arrest ◽  
Damage Response

Abstract Background: The hypomethylating agents azacytidine (AZA) and decitabine (DEC) have shown clinical efficacy in patients (pts) with MDS. There is in vitro evidence that both agents, in addition to their hypomethylating effect, also function by inducing apoptosis, cell cycle arrest and/or the activation of a DNA damage response (DDR). However, the exact contributions of those mechanisms of action and their functional interdependence remain to be defined. Methods: A panel of MDS (P39, MDS-1)- and AML (HL-60, KG-1)-derived cell lines were incubated with increasing dosages of AZA (1–2μM) and DEC (1–2μM) and the drugs capacity to induce apoptosis (DiOC6(3)/PI), cell cycle arrest (PI) and/or a DDR (immunoflourescence staining of P-ATM, P-Chk-1, P-Chk-2, γ-H2AX) were assessed in absence and presence of the ATM-inhibitor KU-55933 and the Chk-1 inhibitor UCN-01. Results: We show that both drugs induced dose-dependent apoptosis in myeloid cell lines: whereas AZA increased apoptosis in KG-1 and HL-60 by about 10% (48h, 2μM) the respective incubation with DEC augmented apoptosis by about 20% (HL-60) to 30% (KG-1). P39 cells were resistant to AZA and increased apoptosis by 15% after 48h of 2μM DEC, and MDS-1 cells were resistant to both drugs. In addition, both drugs induced a G2/M-arrest in P39 (+15% after 48h with 2μM of AZA or DEC) and HL-60 (+20% after 48h with 2μM of AZA or DEC) cells, but not in KG-1 and MDS-1 cells. Noteworthy, both drugs induced a DDR in the apoptosis-sensitive KG-1 cells (but not P39 cells) as evidenced by the appearance of nuclear P-ATM and γ-H2AX foci. Surprisingly, this activation of P-ATM did not induce the nuclear translocation of P-Chk-1-Ser317 or P-Chk-2-Ser68. To more clearly define the importance of the DDR in AZA- and DEC-induced apoptosis and G2/M-arrest, experiments were recapitulated in the presence of the ATM-inhibitor KU-55933 and the Chk-1 inhibitor UCN-01. Inhibition of ATM abrogated the apoptosis-inducing activity of AZA and DEC in KG-1 cells (without influencing cell cycle progression), whereas inhibition of Chk-1 remained without effect. In contrast, in P39 and HL-60 cells, inhibition of ATM neither affected cell cycle progression, nor sensitivity towards the drugs. Nevertheless, inhibition of Chk-1 by UCN-01 completely abrogated the G2/M-arresting effect of AZA (and diminished that of DEC) in P39 and HL-60 cells. Conclusions: We provide novel evidence for the cell-type dependent capacity of the hypomethylating agents 5-azacytidine and decitabine to induce apoptosis, cell-cycle arrest and DDR in cell lines representing different subtypes of MDS and AML. Moreover, we show the crucial role of ATM and Chk-1 activation – as part of the DDR – in mediating AZA and DEC apoptosis-inducing and cell cycle-arresting effects, respectively, providing evidence that hypomethylating agents confer their beneficial effects by employing different pathways of the DDR.

Coordinate Changes In RNA Expression, Transcript Splicing, and DNA Methylation In Pediatric AML

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3761-3761
Author(s):  
Jason Farrar ◽  
Michael Ochs ◽  
David W Lee ◽  
C.C. Talbot ◽  
Jonathan Buckley ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Dna Damage ◽  
Alternative Splicing ◽  
Dna Damage Response ◽  
Cell Cycle Progression ◽  
Expression Patterns ◽  
Cycle Progression ◽  
Damage Response ◽  
Pediatric Aml

Abstract While mutations of splicing and epigenetic factors have been reported in adult AML and related myeloid disorders, relatively few such changes have been identified in pediatric AML. We previously identified a chromatin remodeling helicase, PASG (SMARCA6, HELLS, LSH), by down-regulation in AML cell lines following cytokine withdrawal and identified an alternatively spliced variant lacking a highly conserved (STRAGGLG) domain. To assess the prevalence of this splicing variant (PASGΔ75) in pediatric AML, we tested 167 diagnostic specimens from the TARGET-AML cohort for fractional PASGΔ75 expression (PASGΔ75/PASG) using a discriminatory RT-qPCR assay. These studies demonstrated a broad, continuous distribution of PASGΔ75 with right skew (mean PASGΔ75: 26%, interquartile range: 9% – 41%) that was not significantly associated with cytogenetic class (inv16, t(8;21), MLL, normal) or FAB subtype. For further comparison, specimens were quantized by PASGΔ75 quartile. Given reported associations between loss of PASG function and abnormalities of genomic methylation, we tested 48 AML specimens at the extremes of the PASGΔ75 distribution for total 5-methylcytosine (5-mC) content by liquid chromatography/tandem mass spectrometry. The mean total methylation was significantly lower in the high compared to the low PASGΔ75 groups (mean 5-mC 3.95% vs. 4.22% of cytosine, p=0.015 Mann-Whitney). To identify specific regions of altered methylation, we used high-throughput sequencing of DNA enriched by pull-down with the methyl binding domain fragment of MBD2 (MBD-Seq). Comparison of summed methylation signal across regions flanking RefSeq transcriptional start sites (TSS) showed the expected decrease in methylation just upstream of the TSS in both groups. However, methylation more distal to the TSS was proportionally lower in PASGΔ75 high than PASGΔ75 low samples (Fig 1a). To evaluate methylation at CpG islands (CGI), UCSC CGI were scaled to 500 bp and MBD-Seq data were summed across 20Kb flanking CGI. While both groups showed the anticipated increase in methylation signal on CGI, methylation in the shore regions immediately flanking CGI was proportionally lower in high PASGΔ75 compared to low PASGΔ75 samples (Fig 1b), further suggesting epigenetic differences between these sample groups. Because we were unable to identify sequence variants in PASG intron 18 or flanking exons that might explain alternative splicing, we asked whether expression of PASGΔ75 was associated with global changes in transcript splicing. We evaluated gene expression patterns on the Affymetrix HuGene array, with assessment of alternative splicing using Partek software alternative splicing (altsplice) algorithm for quartile-grouped samples. In contrast to comparison of adjacent quartile groups, which showed modest changes in expression and relatively few transcripts with significant altsplice scores, comparison of the highest and lowest quartile samples showed marked changes in gene expression and a large number of alternatively spiced transcripts as assessed by significance of the altsplice score (Fig 2). In addition to splicing changes, these analyses suggested marked differences in gene expression patterns of AML specimens grouped by PASGΔ75 quartile, with clear separation of Q1 and Q4 samples by principal components analysis. Using a conservative Wilcoxon gene sets test and limiting ourselves to small, curated Biocarta pathways, we found expression patterns associated with high deletion variant expression strongly linked to overlapping pathways involving DNA repair, replication, and cell cycle progression. Table Pathways (Biocarta) Pathway Class Benjamini Hochberg Corrected p-Value ATR/BRCA1/BRCA2 DNA Damage Response 1.3E-6 RB/DNA Damage DNA Damage Response 3.5E-3 p27 Phosphorylation Cell Cycle Progression 3.5E-3 G2/M Checkpoint Cell Cycle Progression 3.5E-3 G1/S Checkpoint Cell Cycle Progression 4.1E-3 PLK3 Cell Cycle Progression 4.1E-3 MEF2D Apoptosis 0.01 SRC/PTPa Cell Cycle Progression 0.02 Mitochondrial Acetyl-Co Shuttle Metabolism 0.02 p53 Signaling DNA Damage Response 0.04 E2F-1 Cell Cycle Progression 0.04 ATM Signaling DNA Damage Response 0.04 These data suggest the existence of a previously unrecognized AML subclass characterized by widespread and coordinated changes in RNA expression, alternative transcript splicing, and epigenetic modifications. Disclosures: No relevant conflicts of interest to declare.

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