Thrombopoietin-Increased DNA-PK-Dependent DNA Repair Limits Hematopoietic STEM and Progenitor CELL Mutagenesis in Response to Irradiation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3447-3447
Author(s):  
Bérengère de Laval ◽  
Patrycja Pawlikowska ◽  
Benoit Roch ◽  
Laurence Petit-Cocault ◽  
Chrystele Bilhou-Nabera ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Dna Damage Repair ◽  
Dsb Repair ◽  
Hematopoietic Stem ◽  
Damage Repair ◽  
Damage Response ◽  
Radiation Induced

Abstract Abstract 3447 Radiation-induced double-strand breaks (DSBs) represent a serious threat to the preservation of genetic information when it reaches hematopoietic stem cells (HSCs). Residual loss of HSC functions and increased risk of developing hematopoietic malignancies are two concerning complications of anti-cancer radiotherapy. Management of acute myelosuppression following radio- or chemotherapy has been significantly improved in recent years by the use of growth factors. However, how cytokine/environmental signals integrate the DNA damage responses in HSCs and regulate the long-term residual HSC defects following radio-or chemotherapy is unknown. Notably, the contribution of cytokines regulating HSC functions to HSC intrinsic DNA damage repair processes remains to be delineated. Thrombopoietin (TPO) and its receptor, Mpl, are critical factors supporting HSC self-renewal, survival and expansion posttransplantation. In this study, we uncover an unknown and unique function for TPO/Mpl in the regulation the DNA damage response. We show that DSB repair, measured by both γH2Ax foci resolution and neutral comet assays, following γ-irradiation (IR) or topoisomerase II inhibitor treatments, is defective in Mpl−/− and Mpl+/− HS and progenitor cells (HSPCs). Similar defects were found in wild-type cells treated in the absence of TPO. This indicates that the impaired DNA repair of Mpl−/− and Mpl+/− cells results from a specific loss of TPO-mediated DNA damage response signaling at the time of IR rather than from intrinsic constitutive differences. TPO stimulates DNA repair by increasing IR-induced DNA-PK phosphorylation at Ser2056 and Thr2609 and non-homologous end joining (NHEJ) efficiency in both HSPCs and the human UT7-Mpl cell line. This is to our knowledge the first demonstration that a cytokine involved in the homeostatic maintenance of HSCs may also regulate their response to external DNA damaging insults by controlling the DSB repair machinery. Short TPO treatment in vitro or single TPO injection to TPO/Mpl proficient mice prior to sublethal total body IR reduced IR-induced HSC genomic instability and loss of long-term reconstitution ability. This may open new avenues for administration of TPO agonists before radiotherapy to minimize radiation-induced HSC injury and mutagenesis. In addition, since Mpl is haploinsufficient in the regulation of DNA damage repair, these data suggest that Mpl might also act as a tumor suppressor in response to radiotherapy. Disclosures: No relevant conflicts of interest to declare.

scholarly journals DNA damage repair: historical perspectives, mechanistic pathways and clinical translation for targeted cancer therapy

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ruixue Huang ◽  
Ping-Kun Zhou
Keyword(s):  
Dna Damage ◽  
Cancer Therapy ◽  
Cancer Treatment ◽  
Dna Damage Response ◽  
Dna Damage Repair ◽  
Therapeutic Effects ◽  
Targeted Cancer Therapy ◽  
Baseline Drift ◽  
Damage Repair ◽  
Damage Response

AbstractGenomic instability is the hallmark of various cancers with the increasing accumulation of DNA damage. The application of radiotherapy and chemotherapy in cancer treatment is typically based on this property of cancers. However, the adverse effects including normal tissues injury are also accompanied by the radiotherapy and chemotherapy. Targeted cancer therapy has the potential to suppress cancer cells’ DNA damage response through tailoring therapy to cancer patients lacking specific DNA damage response functions. Obviously, understanding the broader role of DNA damage repair in cancers has became a basic and attractive strategy for targeted cancer therapy, in particular, raising novel hypothesis or theory in this field on the basis of previous scientists’ findings would be important for future promising druggable emerging targets. In this review, we first illustrate the timeline steps for the understanding the roles of DNA damage repair in the promotion of cancer and cancer therapy developed, then we summarize the mechanisms regarding DNA damage repair associated with targeted cancer therapy, highlighting the specific proteins behind targeting DNA damage repair that initiate functioning abnormally duo to extrinsic harm by environmental DNA damage factors, also, the DNA damage baseline drift leads to the harmful intrinsic targeted cancer therapy. In addition, clinical therapeutic drugs for DNA damage and repair including therapeutic effects, as well as the strategy and scheme of relative clinical trials were intensive discussed. Based on this background, we suggest two hypotheses, namely “environmental gear selection” to describe DNA damage repair pathway evolution, and “DNA damage baseline drift”, which may play a magnified role in mediating repair during cancer treatment. This two new hypothesis would shed new light on targeted cancer therapy, provide a much better or more comprehensive holistic view and also promote the development of new research direction and new overcoming strategies for patients.

scholarly journals PAICS contributes to gastric carcinogenesis and participates in DNA damage response by interacting with histone deacetylase 1/2

2020 ◽  
Vol 11 (7) ◽  
Author(s):  
Nan Huang ◽  
Chang Xu ◽  
Liang Deng ◽  
Xue Li ◽  
Zhixuan Bian ◽  
...  
Keyword(s):  
Dna Damage ◽  
Histone Deacetylase ◽  
Dna Damage Response ◽  
De Novo ◽  
Dna Damage Repair ◽  
Histone Deacetylase 1 ◽  
Damage Repair ◽  
Damage Response

AbstractPhosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS), an essential enzyme involved in de novo purine biosynthesis, is connected with formation of various tumors. However, the specific biological roles and related mechanisms of PAICS in gastric cancer (GC) remain unclear. In the present study, we identified for the first time that PAICS was significantly upregulated in GC and high expression of PAICS was correlated with poor prognosis of patients with GC. In addition, knockdown of PAICS significantly induced cell apoptosis, and inhibited GC cell growth both in vitro and in vivo. Mechanistic studies first found that PAICS was engaged in DNA damage response, and knockdown of PAICS in GC cell lines induced DNA damage and impaired DNA damage repair efficiency. Further explorations revealed that PAICS interacted with histone deacetylase HDAC1 and HDAC2, and PAICS deficiency decreased the expression of DAD51 and inhibited its recruitment to DNA damage sites by impairing HDAC1/2 deacetylase activity, eventually preventing DNA damage repair. Consistently, PAICS deficiency enhanced the sensitivity of GC cells to DNA damage agent, cisplatin (CDDP), both in vitro and in vivo. Altogether, our findings demonstrate that PAICS plays an oncogenic role in GC, which act as a novel diagnosis and prognostic biomarker for patients with GC.

scholarly journals Mutant huntingtin impairs PNKP and ATXN3, disrupting DNA repair and transcription

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Rui Gao ◽  
Anirban Chakraborty ◽  
Charlene Geater ◽  
Subrata Pradhan ◽  
Kara L Gordon ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Rna Polymerase Ii ◽  
Dna Damage Response ◽  
Functional Decline ◽  
Transcriptional Elongation ◽  
Damage Repair ◽  
Damage Response ◽  
Cyclic Amp Response Element ◽  
Atm Signaling

How huntingtin (HTT) triggers neurotoxicity in Huntington’s disease (HD) remains unclear. We report that HTT forms a transcription-coupled DNA repair (TCR) complex with RNA polymerase II subunit A (POLR2A), ataxin-3, the DNA repair enzyme polynucleotide-kinase-3'-phosphatase (PNKP), and cyclic AMP-response element-binding (CREB) protein (CBP). This complex senses and facilitates DNA damage repair during transcriptional elongation, but its functional integrity is impaired by mutant HTT. Abrogated PNKP activity results in persistent DNA break accumulation, preferentially in actively transcribed genes, and aberrant activation of DNA damage-response ataxia telangiectasia-mutated (ATM) signaling in HD transgenic mouse and cell models. A concomitant decrease in Ataxin-3 activity facilitates CBP ubiquitination and degradation, adversely impacting transcription and DNA repair. Increasing PNKP activity in mutant cells improves genome integrity and cell survival. These findings suggest a potential molecular mechanism of how mutant HTT activates DNA damage-response pro-degenerative pathways and impairs transcription, triggering neurotoxicity and functional decline in HD.

A novel role for the HLH protein Inhibitor of Differentiation 4 (ID4) in the DNA damage response in basal-like breast cancer

2018 ◽  
Author(s):  
Laura A. Baker ◽  
Christoph Krisp ◽  
Daniel Roden ◽  
Holly Holliday ◽  
Sunny Z. Wu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Dna Damage Repair ◽  
Chemotherapy Resistance ◽  
Clinical Analysis ◽  
Damage Repair ◽  
Damage Response ◽  
Basal Like Breast Cancer ◽  
Dna Damage Signalling

AbstractBasal-like breast cancer (BLBC) is a poorly characterised, heterogeneous disease. Patients are diagnosed with aggressive, high-grade tumours and often relapse with chemotherapy resistance. Detailed understanding of the molecular underpinnings of this disease is essential to the development of personalised therapeutic strategies. Inhibitor of Differentiation 4 (ID4) is a helix-loop-helix transcriptional regulator required for mammary gland development. ID4 is overexpressed in a subset of BLBC patients, associating with a stem-like poor prognosis phenotype, and is necessary for the growth of cell line models of BLBC, through unknown mechanisms. Here, we have defined a molecular mechanism of action for ID4 in BLBC and the related disease highgrade serous ovarian cancer (HGSOV), by combining RIME proteomic analysis and ChIP-Seq mapping of genomic binding sites. Remarkably, these studies have revealed novel interactions with DNA damage response proteins, in particular, mediator of DNA damage checkpoint protein 1 (MDC1). Through MDC1, ID4 interacts with other DNA repair proteins (γH2AX and BRCA1) at fragile chromatin sites. ID4 does not affect transcription at these sites, instead binding to chromatin following DNA damage and regulating DNA damage signalling. Clinical analysis demonstrates that ID4 is amplified and overexpressed at a higher frequency in BRCA1-mutant BLBC compared with sporadic BLBC, providing genetic evidence for an interaction between ID4 and DNA damage repair pathways. These data link the interactions of ID4 with MDC1 to DNA damage repair in the aetiology of BLBC and HGSOV.

Effect of inhibition of receptor tyrosine kinase AXL by a selective small molecular inhibitor R428 (BGB321) on DNA damage repair response in ovarian cancer cells.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e15640-e15640
Author(s):  
Ruby Yun-Ju Huang ◽  
Xun Hui Yeo ◽  
Wai Leong Tam
Keyword(s):  
Dna Damage ◽  
Tyrosine Kinase ◽  
Cell Lines ◽  
Dna Damage Response ◽  
Receptor Tyrosine Kinase ◽  
Dna Damage Repair ◽  
Damage Repair ◽  
Damage Response ◽  
Dna Damage Responses

e15640 Background: AXL is a receptor tyrosine kinase that is often overexpressed in many cancers. It contributes to tumor progression, metastasis and drug resistance through activating downstream signaling cascades, making it an emerging therapeutic target. The first-in-class AXL inhibitor R428 (BGB321) was approved by the FDA for the treatment of relapsed or refractory acute myeloid leukemia. R428 (BGB321) was also reported to show selective sensitivity towards ovarian cancers (OC) with a Mesenchymal (Mes) molecular subtype. Recently, a novel role of AXL in the regulation of DNA damage responses has been described. In this study, we explored further the role of AXL in mediating DNA damage responses by using OC as a disease model. Methods: OC cell lines were treated with R428. Accumulation of γH2AX positive foci was assessed for DNA damage response. Western blotting for γH2AX, ATM and ATR levels were performed. Dose response curves of ATR inhibitors were generated by treating OC cells with the fixed dose of R428 (IC20 concentration of each cell line). Results: AXL inhibition by using R428 resulted in the increase of DNA damage foci in Mes OC cells SKOV3 and HeyA8. This occurred concurrently with the up-regulation of classic DNA damage response signaling molecules such as γH2AX, ATM and ATR. The IC50 of the ATR inhibitor significantly decreased for 2-3 folds in all OC cell lines tested. AXL inhibitor R428 sensitized both BRCA-mutated and non-BRCA-mutated OC cells to a potent and highly selective ATR inhibitor. Conclusions: Our results showed that AXL inhibition rendered cells more sensitive to the inhibition of ATR, a crucial mediator for replication stress, paving ways to the rationale for potential combinatory use of AXL and DNA damage repair inhibitors.

scholarly journals A combination of Class-I fumarases and metabolites (α-ketoglutarate and fumarate) signal the DNA damage response in Escherichia coli

2021 ◽  
Vol 118 (23) ◽  
pp. e2026595118
Author(s):  
Yardena Silas ◽  
Esti Singer ◽  
Koyeli Das ◽  
Norbert Lehming ◽  
Ophry Pines
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Dna Damage Repair ◽  
Class Ii ◽  
Class I ◽  
Repair Enzyme ◽  
E Coli ◽  
Damage Repair ◽  
Damage Response ◽  
Null Mutants

Class-II fumarases (fumarate hydratase, FH) are dual-targeted enzymes occurring in the mitochondria and cytosol of all eukaryotes. They are essential components in the DNA damage response (DDR) and, more specifically, protect cells from DNA double-strand breaks. Similarly, the gram-positive bacterium Bacillus subtilis class-II fumarase, in addition to its role in the tricarboxylic acid cycle, participates in the DDR. Escherichia coli harbors three fumarase genes: class-I fumA and fumB and class-II fumC. Notably, class-I fumarases show no sequence similarity to class-II fumarases and are of different evolutionary origin. Strikingly, here we show that E. coli fumarase functions are distributed between class-I fumarases, which participate in the DDR, and the class-II fumarase, which participates in respiration. In E. coli, we discover that the signaling molecule, alpha-ketoglutarate (α-KG), has a function, complementing DNA damage sensitivity of fum-null mutants. Excitingly, we identify the E. coli α-KG–dependent DNA repair enzyme AlkB as the target of this interplay of metabolite signaling. In addition to α-KG, fumarate (fumaric acid) is shown to affect DNA damage repair on two different levels, first by directly inhibiting the DNA damage repair enzyme AlkB demethylase activity, both in vitro and in vivo (countering α-KG). The second is a more global effect on transcription, because fum-null mutants exhibit a decrease in transcription of key DNA damage repair genes. Together, these results show evolutionary adaptable metabolic signaling of the DDR, in which fumarases and different metabolites are recruited regardless of the evolutionary enzyme class performing the function.

Long noncoding RNA SNHG12 integrates a DNA-PK–mediated DNA damage response and vascular senescence

2020 ◽  
Vol 12 (531) ◽  
pp. eaaw1868 ◽  
Author(s):  
Stefan Haemmig ◽  
Dafeng Yang ◽  
Xinghui Sun ◽  
Debapria Das ◽  
Siavash Ghaffari ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Vascular Endothelium ◽  
Vessel Wall ◽  
Noncoding Rna ◽  
Dna Damage Repair ◽  
Atherosclerotic Lesion ◽  
High Cholesterol Diet ◽  
Damage Repair ◽  
Damage Response

Long noncoding RNAs (lncRNAs) are emerging regulators of biological processes in the vessel wall; however, their role in atherosclerosis remains poorly defined. We used RNA sequencing to profile lncRNAs derived specifically from the aortic intima of Ldlr−/− mice on a high-cholesterol diet during lesion progression and regression phases. We found that the evolutionarily conserved lncRNA small nucleolar host gene-12 (SNHG12) is highly expressed in the vascular endothelium and decreases during lesion progression. SNHG12 knockdown accelerated atherosclerotic lesion formation by 2.4-fold in Ldlr−/− mice by increased DNA damage and senescence in the vascular endothelium, independent of effects on lipid profile or vessel wall inflammation. Conversely, intravenous delivery of SNHG12 protected the tunica intima from DNA damage and atherosclerosis. LncRNA pulldown in combination with liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis showed that SNHG12 interacted with DNA-dependent protein kinase (DNA-PK), an important regulator of the DNA damage response. The absence of SNHG12 reduced the DNA-PK interaction with its binding partners Ku70 and Ku80, abrogating DNA damage repair. Moreover, the anti-DNA damage agent nicotinamide riboside (NR), a clinical-grade small-molecule activator of NAD+, fully rescued the increases in lesional DNA damage, senescence, and atherosclerosis mediated by SNHG12 knockdown. SNHG12 expression was also reduced in pig and human atherosclerotic specimens and correlated inversely with DNA damage and senescent markers. These findings reveal a role for this lncRNA in regulating DNA damage repair in the vessel wall and may have implications for chronic vascular disease states and aging.

scholarly journals A Commentary on TDP-43 and DNA Damage Response in Amyotrophic Lateral Sclerosis

2019 ◽  
Vol 13 ◽  
pp. 117906951988016 ◽  
Author(s):  
Joy Mitra ◽  
Muralidhar L Hegde
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Amyotrophic Lateral Sclerosis ◽  
Dna Damage Response ◽  
Motor Neurons ◽  
Dsb Repair ◽  
Spinal Motor Neurons ◽  
Spinal Motor ◽  
Damage Response ◽  
Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating, motor neuron degenerative disease without any cure. About 95% of the ALS patients feature abnormalities in the RNA/DNA-binding protein, TDP-43, involving its nucleo-cytoplasmic mislocalization in spinal motor neurons. How TDP-43 pathology triggers neuronal apoptosis remains unclear. In a recent study, we reported for the first time that TDP-43 participates in the DNA damage response (DDR) in neurons, and its nuclear clearance in spinal motor neurons caused DNA double-strand break (DSB) repair defects in ALS. We documented that TDP-43 was a key component of the non-homologous end joining (NHEJ) pathway of DSB repair, which is likely the major pathway for repair of DSBs in post-mitotic neurons. We have also uncovered molecular insights into the role of TDP-43 in DSB repair and showed that TDP-43 acts as a scaffold in recruiting the XRCC4/DNA Ligase 4 complex at DSB damage sites and thus regulates a critical rate-limiting function in DSB repair. Significant DSB accumulation in the genomes of TDP-43-depleted, human neural stem cell-derived motor neurons as well as in ALS patient spinal cords with TDP-43 pathology, strongly supported a TDP-43 involvement in genome maintenance and toxicity-induced genome repair defects in ALS. In this commentary, we highlight our findings that have uncovered a link between TDP-43 pathology and impaired DNA repair and suggest potential possibilities for DNA repair-targeted therapies for TDP-43-ALS.

Dysfunctional DNA Double-Strand Break Repair Is Present in a Subset of Primary t-AML/t-MDS Myeloblasts

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2415-2415
Author(s):  
Meagan A Jacoby ◽  
Rigoberto de Jesus ◽  
Jin Shao ◽  
Daniel Koboldt ◽  
Matthew J. Walter
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Fold Increase ◽  
Parp Inhibition ◽  
Normal Donor ◽  
Trisomy 8 ◽  
Dsb Repair ◽  
Cd34 Cells ◽  
Damage Response

Abstract Abstract 2415 The chromosomal aberrations found in treatment-related acute myeloid leukemia/myelodysplastic syndrome (t-AML/t-MDS) cells suggest that disease initiation and progression may result from the inappropriate response to double-strand DNA breaks (DSBs) induced by prior exposure to radiation or chemotherapy. We hypothesized that dysregulation of DSB repair by homology-directed repair (HDR) or nonhomologous end joining (NHEJ) in t-AML/t-MDS may result from acquired mutations in HDR/NHEJ pathway genes. To test this possibility, we used next-generation sequencing technology to identify somatic genetic variants in 21 canonical HDR and 9 NHEJ DNA repair genes, as well as a subset of 7 DNA damage response genes using tumor DNA and paired normal DNA obtained from 25 t-AML/t-MDS patients. We identified 6 patients with somatic changes in 3 of these genes (RAD51L3, EME1, TP53). As dysfunctional DSB repair from epigenetic or post-translational modifications in DSB repair pathway genes or abnormalities in other DNA repair pathway genes would be missed using this approach, in parallel we performed functional studies of DSB repair using primary bone marrow cells from 16 of these t-AML/t-MDS patients and CD34+ cells from 5 normal donors. We evaluated DSB by measuring phosphorylated histone H2AX (pH2AX), a well established marker for DSB, in myeloblasts (CD45 dim, low side scatter) and lymphocytes (a surrogate for normal cells) in these samples. Baseline measurements of primary cells, coupled with a time course to measure pH2AX induction and decay after 2 Gy of irradiation (IR) were used to assess the basal DSB burden and response to acute damage, respectively. pH2AX levels were measured by flow cytometry and the geometric mean of the fluorescence intensity was converted to mean equivalent soluble fluorophore (MESF) through the use of standard beads included in each experiment. We found that 4 of 16 t-AML/t-MDS patients had myeloblasts that displayed baseline and post-damage pH2AX levels similar to normal CD34+ controls, while 12/16 patients had abnormal pH2AX levels which fell into one of three major patterns. 1) The first subset had myeloblasts in which baseline pH2AX levels were elevated compared to normal donor CD34+ (average MESF 23,107 vs 11,490, respectively; p<=0.002) suggesting an increased basal DSB burden in these cells. Furthermore, the myeloblasts showed impaired pH2AX induction (measured at 30 min. post IR) compared to CD34+ controls (1.53 vs 2.97 fold increase in pH2AX over baseline, p<=0.002), suggesting a defect in detecting DSB. This phenotype was unique to patients harboring trisomy 8 and was tumor specific, as their lymphocytes displayed baseline and post-induction pH2AX levels similar to lymphocytes from normal controls. No somatic (tumor) sequencing variants were present in the interrogated genes, raising the possibility that trisomy 8 could be driving an abnormal DNA damage response. 2) A second subset of patients had impaired pH2AX induction compared to normal donor CD34+ cells (1.44 vs 2.97 fold increase in pH2AX over baseline, p<=0.01), again suggesting a defect in detecting DSBs. These patients also lacked somatic changes in HDR/NHEJ pathway genes. 3) The final subset of patients had delayed resolution of pH2AX levels compared to CD34+ controls post IR either at 4 hours (average MESF 39,260 vs 25,480, p<0.05) or delayed resolution over the entire 24 hour period compared to controls (p<0.001). These data are consistent with a DSB repair defect and similar to our data showing cells lacking BRCA2, a gene central to the HDR pathway, have elevated pH2AX levels at 4–24 hours post DSB induction compared to BRCA2 sufficient cells (p=0.01). One of these patients had an acquired mutation in the HDR gene RAD51L3. We are currently determining the sensitivity of primary t-AML/t-MDS cells with abnormalities in pH2AX levels to a combination of DSB inducing chemotherapy and PARP inhibition, which is synthetically lethal in the setting of HDR defects. We show cell lines lacking RAD51L3 are more sensitive to PARP inhibition compared to isogenic controls (surviving fraction (SF)50 5 nM vs 20,000 nM). In total, this study confirms that DNA repair genes are mutated in t-AML/t-MDS, suggests that dysfunctional DSB repair is present in t-AML/t-MDS myeloblasts, and provides a rationale to test whether the abnormal DNA damage response can be exploited therapeutically using a synthetic lethal approach in this disease. Disclosures: No relevant conflicts of interest to declare.

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