scholarly journals The Atr-Chek1 pathway inhibits axon regeneration in response to Piezo-dependent mechanosensation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Feng Li ◽  
Tsz Y. Lo ◽  
Leann Miles ◽  
Qin Wang ◽  
Harun N. Noristani ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mechanical Stimulus ◽  
Cns Injury ◽  
Dna Breaks ◽  
Behavioral Recovery ◽  
Adult Mice ◽  
Cycle Arrest ◽  
Mechanosensitive Ion Channel

AbstractAtr is a serine/threonine kinase, known to sense single-stranded DNA breaks and activate the DNA damage checkpoint by phosphorylating Chek1, which inhibits Cdc25, causing cell cycle arrest. This pathway has not been implicated in neuroregeneration. We show that in Drosophila sensory neurons removing Atr or Chek1, or overexpressing Cdc25 promotes regeneration, whereas Atr or Chek1 overexpression, or Cdc25 knockdown impedes regeneration. Inhibiting the Atr-associated checkpoint complex in neurons promotes regeneration and improves synapse/behavioral recovery after CNS injury. Independent of DNA damage, Atr responds to the mechanical stimulus elicited during regeneration, via the mechanosensitive ion channel Piezo and its downstream NO signaling. Sensory neuron-specific knockout of Atr in adult mice, or pharmacological inhibition of Atr-Chek1 in mammalian neurons in vitro and in flies in vivo enhances regeneration. Our findings reveal the Piezo-Atr-Chek1-Cdc25 axis as an evolutionarily conserved inhibitory mechanism for regeneration, and identify potential therapeutic targets for treating nervous system trauma.

The Atr-Chek1 pathway inhibits axon regeneration in response to Piezo-dependent mechanosensation

2020 ◽  
Author(s):  
Feng Li ◽  
Tsz Y. Lo ◽  
Leann Miles ◽  
Qin Wang ◽  
Dan Li ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mechanical Stimulus ◽  
Cns Injury ◽  
Dna Breaks ◽  
Behavioral Recovery ◽  
Adult Mice ◽  
Cycle Arrest ◽  
Mechanosensitive Ion Channel

ABSTRACTAtr is a serine/threonine kinase, known to sense single-stranded DNA breaks and activate the DNA damage checkpoint by phosphorylating Chek1, which inhibits Cdc25, causing cell cycle arrest. This pathway has not been implicated in neuroregeneration. We show that in Drosophila sensory neurons, removing Atr or Chek1, or overexpressing Cdc25 promotes regeneration, whereas Atr or Chek1 overexpression, or Cdc25 knockdown impedes regeneration. Inhibiting the Atr-associated checkpoint complex in neurons promotes regeneration and improves synapse/behavioral recovery after CNS injury. Independent of DNA damage, Atr responds to the mechanical stimulus elicited during regeneration, via the mechanosensitive ion channel Piezo and its downstream NO signaling. Sensory neuron-specific knockout of Atr in adult mice, or pharmacological inhibition of Atr-Chek1 in mammalian neurons in vitro and in flies in vivo enhance regeneration. Our findings reveal the Piezo-Atr-Chek1-Cdc25 axis as an evolutionarily conserved inhibitory mechanism for regeneration, and identify potential therapeutic targets for treating nervous system trauma.

A Novel Camptothecin Derivative 3j Inhibits Nsclc Proliferation Via Induction of Cell Cycle Arrest By Topo I-Mediated DNA Damage

2019 ◽  
Vol 19 (3) ◽  
pp. 365-374 ◽  
Author(s):  
Yang Liu ◽  
Jingyin Zhang ◽  
Shuyun Feng ◽  
Tingli Zhao ◽  
Zhengzheng Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Dna Damage ◽  
Cyclin D ◽  
Dna Relaxation ◽  
Cycle Arrest ◽  
H460 Cell ◽  
H1975 Cell

Objective: The aim of this study is to investigate the inhibitory effect of camptothecin derivative 3j on Non-Small Cell Lung Cancer (NSCLCs) cells and the potential anti-tumor mechanisms. Background: Camptothecin compounds are considered as the third largest natural drugs which are widely investigated in the world and they suffered restriction because of serious toxicity, such as hemorrhagic cystitis and bone marrow suppression. Methods: Using cell proliferation assay and S180 tumor mice model, a series of 20(S)-O-substituted benzoyl 7- ethylcamptothecin compounds were screened and evaluated the antitumor activities in vitro and in vivo. Camptothecin derivative 3j was selected for further study using flow cytometry in NSCLCs cells. Cell cycle related protein cyclin A2, CDK2, cyclin D and cyclin E were detected by Western Blot. Then, computer molecular docking was used to confirm the interaction between 3j and Topo I. Also, DNA relaxation assay and alkaline comet assay were used to investigate the mechanism of 3j on DNA damage. Results: Our results demonstrated that camptothecin derivative 3j showed a greater antitumor effect in eleven 20(S)-O-substituted benzoyl 7-ethylcamptothecin compounds in vitro and in vivo. The IC50 of 3j was 1.54± 0.41 µM lower than irinotecan with an IC50 of 13.86±0.80 µM in NCI-H460 cell, which was reduced by 8 fold. In NCI-H1975 cell, the IC50 of 3j was 1.87±0.23 µM lower than irinotecan (IC50±SD, 5.35±0.38 µM), dropped by 1.8 fold. Flow cytometry analysis revealed that 3j induced significant accumulation in a dose-dependent manner. After 24h of 3j (10 µM) treatment, the percentage of NCI-H460 cell in S-phase significantly increased (to 93.54 ± 4.4%) compared with control cells (31.67 ± 3.4%). Similarly, the percentage of NCI-H1975 cell in Sphase significantly increased (to 83.99 ± 2.4%) compared with control cells (34.45 ± 3.9%) after treatment with 10µM of 3j. Moreover, increased levels of cyclin A2, CDK2, and decreased levels of cyclin D, cyclin E further confirmed that cell cycle arrest was induced by 3j. Furthermore, molecular docking studies suggested that 3j interacted with Topo I-DNA and DNA-relaxation assay simultaneously confirmed that 3j suppressed the activity of Topo I. Research on the mechanism showed that 3j exhibited anti-tumour activity via activating the DNA damage response pathway and suppressing the repair pathway in NSCLC cells. Conclusion: Novel camptothecin derivative 3j has been demonstrated as a promising antitumor agent and remains to be assessed in further studies.

Induction of G1 Cell Cycle Arrest in Human Glioma Cells by Salinomycin Through Triggering ROS-Mediated DNA Damage In Vitro and In Vivo

2016 ◽  
Vol 42 (4) ◽  
pp. 997-1005 ◽  
Author(s):  
Shi-Jun Zhao ◽  
Xian-Jun Wang ◽  
Qing-Jian Wu ◽  
Chao Liu ◽  
Da-Wei Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Glioma Cells ◽  
Human Glioma ◽  
Human Glioma Cells ◽  
Cycle Arrest ◽  
G1 Cell Cycle Arrest

scholarly journals A RAD9-dependent cell cycle arrest in response to unresolved recombination intermediates in Saccharomyces cerevisiae

2019 ◽  
Author(s):  
Hardeep Kaur ◽  
GN Krishnaprasad ◽  
Michael Lichten
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Damage ◽  
Cell Division ◽  
Cell Cycle Arrest ◽  
Mitotic Cell ◽  
Cycle Arrest ◽  
Associated Lesions

AbstractIn Saccharomyces cerevisiae, the conserved Sgs1-Top3-Rmi1 helicase-decatenase regulates homologous recombination by limiting accumulation of recombination intermediates that are precursors of crossovers. In vitro studies have suggested that the dissolution of double-Holliday junction joint molecules by Sgs1-driven convergent junction migration and Top3-Rmi1 mediated strand decatenation could be responsible for this. To ask if dissolution occurs in vivo, we conditionally depleted Sgs1 and/or Rmi1 during return to growth, a procedure where recombination intermediates formed during meiosis are resolved when cells resume the mitotic cell cycle. Sgs1 depletion during return to growth delayed joint molecule resolution, but ultimately most were resolved and cells divided normally. In contrast, Rmi1 depletion resulted in delayed and incomplete joint molecule resolution, and most cells did not divide. rad9Δ mutation restored cell division in Rmi1-depleted cells, indicating that the DNA damage checkpoint caused this cell cycle arrest. Restored cell division in rad9Δ, Rmi1-depleted cells frequently produced anucleate cells, consistent with the suggestion that persistent recombination intermediates prevented chromosome segregation. Our findings indicate that Sgs1-Top3-Rmi1 acts in vivo, as it does in vitro, to promote recombination intermediate resolution by dissolution. They also indicate that, in the absence of Top3-Rmi1 activity, unresolved recombination intermediates persist and activate the DNA damage response, which is usually thought to be activated by much earlier DNA damage-associated lesions.

scholarly journals In Vitro and In Vivo Activity of Fomitopsis Pinicola (Sw. Ex Fr.) Karst Chloroform (Fpkc) Extract Against S180 Tumor Cells

2017 ◽  
Vol 44 (5) ◽  
pp. 2042-2056 ◽  
Author(s):  
Ye Gao ◽  
Pan Wang ◽  
Yaqin Wang ◽  
Lijie Wu ◽  
Xiaobing Wang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Survival Time ◽  
Tumor Cells ◽  
Propidium Iodide ◽  
Cell Morphology ◽  
Fomitopsis Pinicola ◽  
Cycle Arrest

Background/Aims: Non-toxic fomitopsis is has been traditionally used in folk medicine in many countries for its anti-inflammatory and anti-vascular disease activities. The present study investigates the antitumor effect of Fomitopsis pinicola (Sw. Ex Fr.) Karst chloroform extract (FPKc) on S180 tumor cells in vitro and in vivo and we determined the underlying mechanisms. Methods: HPLC was employed to analyze the constituents of FPKc. In-vitro 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to quantify the growth inhibition of FPKc; Propidium iodide (PI) exclusion assay and scanning electron microscopy (SEM) were used to observe the damage on the cell membrane and the changes of the cell morphology; Staining with Hoechst 33342/propidium iodide (HO/PI) and the application of the Annexin V-FITC/PI analysis permitted to observe the cell death triggered by FPKc; DNA damage and cell cycle arrest were detected by flow cytometry; Rhodamine 123 (RH123) and Cytochrome C were used as dyes to investigate the alterations of the mitochondria. In-vivo tumor inhibition and mice survival time were determined. Results: The results of the HPLC assay indicated that FPKc might contain DA (dehydroeburiconic acid), PA (pachymic acid), and ES (ergosterol), at percentages of 0.25%, 17.8%, and 10.5%, respectively. Concerning the study of the biological function, the results showed that FPKc exhibited preferential and significant suppression of proliferation on specific cell lines including S180, HL-60, U937, K562, SMMC-7721, and Eca-109 cells, which induced plasma membrane and cell morphology damages, triggering S180 tumor-cells late apoptosis and leading to DNA damage and S phase arrest. Mitochondria were suspected to play a vital role in these changes. In vivo data indicated that FPKc inhibited the solid tumor growth and prolonged the survival time of tumor-bearing mice. Moreover, FPKc provoked only little damage on normal cells in vitro and also on normal tissues in vivo. Conclusion: FPKc inhibited S180 tumor cells growth and prolonged the lifespan of mice. In vitro, we found that FPKc induced S180 tumor cells apoptosis and cell cycle arrest, possibly via the mitochondrial pathway.

scholarly journals Rnf8 deficiency impairs class switch recombination, spermatogenesis, and genomic integrity and predisposes for cancer

2010 ◽  
Vol 207 (5) ◽  
pp. 983-997 ◽  
Author(s):  
Li Li ◽  
Marie-Jo Halaby ◽  
Anne Hakem ◽  
Renato Cardoso ◽  
Samah El Ghamrasni ◽  
...  
Keyword(s):  
Dna Damage ◽  
Class Switch Recombination ◽  
Dependent Manner ◽  
Dna Double Strand Breaks ◽  
Dna Breaks ◽  
Class Switch ◽  
Physiological Processes ◽  
Increased Sensitivity

Signaling and repair of DNA double-strand breaks (DSBs) are critical for preventing immunodeficiency and cancer. These DNA breaks result from exogenous and endogenous DNA insults but are also programmed to occur during physiological processes such as meiosis and immunoglobulin heavy chain (IgH) class switch recombination (CSR). Recent studies reported that the E3 ligase RNF8 plays important roles in propagating DNA DSB signals and thereby facilitating the recruitment of various DNA damage response proteins, such as 53BP1 and BRCA1, to sites of damage. Using mouse models for Rnf8 mutation, we report that Rnf8 deficiency leads to impaired spermatogenesis and increased sensitivity to ionizing radiation both in vitro and in vivo. We also demonstrate the existence of alternative Rnf8-independent mechanisms that respond to irradiation and accounts for the partial recruitment of 53bp1 to sites of DNA damage in activated Rnf8−/− B cells. Remarkably, IgH CSR is impaired in a gene dose-dependent manner in Rnf8 mutant mice, revealing that these mice are immunodeficient. In addition, Rnf8−/− mice exhibit increased genomic instability and elevated risks for tumorigenesis indicating that Rnf8 is a novel tumor suppressor. These data unravel the in vivo pleiotropic effects of Rnf8.

scholarly journals Tight regulation of ubiquitin-mediated DNA damage response by USP3 preserves the functional integrity of hematopoietic stem cells

2014 ◽  
Vol 211 (9) ◽  
pp. 1759-1777 ◽  
Author(s):  
Cesare Lancini ◽  
Paul C.M. van den Berk ◽  
Joseph H.A. Vissers ◽  
Gaetano Gargiulo ◽  
Ji-Ying Song ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Genotoxic Stress ◽  
Histone H2a ◽  
Deubiquitinating Enzymes ◽  
Dna Breaks ◽  
Hematopoietic Stem ◽  
Damage Response

Histone ubiquitination at DNA breaks is required for activation of the DNA damage response (DDR) and DNA repair. How the dynamic removal of this modification by deubiquitinating enzymes (DUBs) impacts genome maintenance in vivo is largely unknown. To address this question, we generated mice deficient for Ub-specific protease 3 (USP3; Usp3Δ/Δ), a histone H2A DUB which negatively regulates ubiquitin-dependent DDR signaling. Notably, USP3 deletion increased the levels of histone ubiquitination in adult tissues, reduced the hematopoietic stem cell (HSC) reserves over time, and shortened animal life span. Mechanistically, our data show that USP3 is important in HSC homeostasis, preserving HSC self-renewal, and repopulation potential in vivo and proliferation in vitro. A defective DDR and unresolved spontaneous DNA damage contribute to cell cycle restriction of Usp3Δ/Δ HSCs. Beyond the hematopoietic system, Usp3Δ/Δ animals spontaneously developed tumors, and primary Usp3Δ/Δ cells failed to preserve chromosomal integrity. These findings broadly support the regulation of chromatin ubiquitination as a key pathway in preserving tissue function through modulation of the response to genotoxic stress.

scholarly journals DIPG-53. CHARACTERIZING THE ROLE OF PPM1D MUTATIONS IN THE PATHOGENESIS OF DIFFUSE INTRINSIC PONTINE GLIOMAS (DIPGS)

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii297-iii297
Author(s):  
Prasidda Khadka ◽  
Zachary Reitman ◽  
Sophie Lu ◽  
Graham Buchan ◽  
Rachel Hartley ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Radiation Treatment ◽  
Ectopic Expression ◽  
Loss Of Function ◽  
In Vivo Models ◽  
Cycle Arrest ◽  
Diffuse Intrinsic Pontine Gliomas

Abstract INTRODUCTION We have previously found that up to 15% of all DIPGs harbor mutations in PPM1D, resulting in the expression of an activated and truncated PPM1D (PPM1Dtr). Here we evaluate the mechanisms through which PPM1Dtr enhances glioma formation and identify its associated therapeutic vulnerabilities. METHODS We have developed multiple in vitro and in vivo models of PPM1D-mutant DIPGs and applied quantitative proteomic and functional genomic approaches to identify pathways altered by PPM1Dtr and associated dependencies. RESULTS PPM1D mutations are clonal events that are anti-correlated to TP53 mutations. We find ectopic expression of PPM1Dtr to be sufficient to enhance glioma formation and to be necessary in PPM1D-mutant DIPG cells. In addition, endogenous truncation of PPM1D is sufficient to enhance glioma formation in the presence of mutant H3F3A and PDGFRA. PPM1Dtr overexpression attenuates g-H2AX formation and suppresses apoptosis and cell-cycle arrest in response to radiation treatment. Deep scale phosphoproteomics analyses reveal DNA-damage and cell cycle pathways to be most significantly associated with PPM1Dtr. Furthermore, preliminary analysis of genome-wide loss-of-function CRISPR/Cas9 screens in isogenic GFP and PPM1Dtr overexpressing mouse neural stem cells reveal differential dependency on DNA-damage response genes in the PPM1Dtr overexpressing cells. Consistent with PPM1D’s role in stabilizing MDM2, PPM1D-mutant DIPG models are sensitive to a panel of MDM2 inhibitors (Nutlin-3a, RG7388, and AMG232). CONCLUSION Our study shows that PPM1Dtr is both an oncogene and a dependency in PPM1D- mutant DIPG, and there are novel therapeutic vulnerabilities associated with PPM1D that may be exploited.

scholarly journals Proteolytic cleavage of human p53 by calpain: a potential regulator of protein stability.

1997 ◽  
Vol 17 (1) ◽  
pp. 460-468 ◽  
Author(s):  
M H Kubbutat ◽  
K H Vousden
Keyword(s):  
Dna Damage ◽  
P53 Protein ◽  
Calpain Inhibitor ◽  
Cycle Arrest ◽  
A Cell ◽  
P53 Tumor Suppressor Protein ◽  
E6 Protein ◽  
Protein Treatment

The p53 tumor suppressor protein is activated in cells in response to DNA damage and prevents the replication of cells sustaining genetic damage by inducing a cell cycle arrest or apoptosis. Activation of p53 is accompanied by stabilization of the protein, resulting in accumulation to high levels within the cell. p53 is normally degraded through the proteasome following ubiquitination, although the mechanisms which regulate this proteolysis in normal cells and how the p53 protein becomes stabilized following DNA damage are not well understood. We show here that p53 can also be a substrate for cleavage by the calcium-activated neutral protease, calpain, and that a preferential site for calpain cleavage exists within the N terminus of the p53 protein. Treatment of cells expressing wild-type p53 with an inhibitor of calpain resulted in the stabilization of the p53 protein. By contrast, in vitro or in vivo degradation mediated by human papillomavirus E6 protein was unaffected by the calpain inhibitor, indicating that the stabilization did not result from inhibition of the proteasome. These results suggest that calpain cleavage plays a role in regulating p53 stability.

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