scholarly journals A genetic map of the response to DNA damage in human cells

2019 ◽  
Author(s):  
Michele Olivieri ◽  
Tiffany Cho ◽  
Alejandro Álvarez-Quilón ◽  
Kejiao Li ◽  
Matthew J. Schellenberg ◽  
...  

SUMMARYThe response to DNA damage is critical for cellular homeostasis, tumor suppression, immunity and gametogenesis. In order to provide an unbiased and global view of the DNA damage response in human cells, we undertook 28 CRISPR/Cas9 screens against 25 genotoxic agents in the retinal pigment epithelium-1 (RPE1) cell line. These screens identified 840 genes whose loss causes either sensitivity or resistance to DNA damaging agents. Mining this dataset, we uncovered that ERCC6L2, which is mutated in a bone-marrow failure syndrome, codes for a canonical non-homologous end-joining pathway factor; that the RNA polymerase II component ELOF1 modulates the response to transcription-blocking agents and that the cytotoxicity of the G-quadruplex ligand pyridostatin involves trapping topoisomerase II on DNA. This map of the DNA damage response provides a rich resource to study this fundamental cellular system and has implications for the development and use of genotoxic agents in cancer therapy.

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Rui Gao ◽  
Anirban Chakraborty ◽  
Charlene Geater ◽  
Subrata Pradhan ◽  
Kara L Gordon ◽  
...  

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.


2021 ◽  
Author(s):  
Rodolfo Bortolozo Serafim ◽  
Cibele Cardoso ◽  
Vanessa Arfelli ◽  
Valeria Valente ◽  
Leticia Fröhlich Archangelo

Abstract PIMREG expression strongly correlates with cellular proliferation in both malignant and normal cells. Throughout embryo development, PIMREG expression is prominent at the central nervous system. Recent studies have described high levels of PIMREG transcripts in different types of tumors and correlated with patient survival and tumor aggressiveness. Given the emerging significance of PIMREG in carcinogenesis and its putative role in the context of the nervous system, we investigated the expression and function of PIMREG in gliomas, the most common primary brain tumors. We performed an extensive analysis of PIMREG expression in tumors samples of glioma patients, assessed the effects of PIMREG silencing and overexpression on the sensitivity of glioblastoma cell lines treated with genotoxic agents commonly used for treating patients and assessed for treatment response, proliferation and migration. We show that glioblastoma exhibits the highest levels of PIMREG expression among all cancers analyzed and that elevated PIMREG expression is a biomarker for glioma progression and patient outcome. Moreover, PIMREG is induced by genotoxic agents and its silencing renders glioblastoma cells sensitive to temozolomide treatment and affects ATR- and ATM-dependent signaling. Our data demonstrate that PIMREG plays a role in DNA damage response and temozolomide resistance of glioblastoma cells and further support the PIMREG role in tumorigenesis.


2012 ◽  
Vol 72 (8) ◽  
pp. 2006-2016 ◽  
Author(s):  
Christelle Morris ◽  
Nozomi Tomimatsu ◽  
Derek J. Richard ◽  
David Cluet ◽  
Sandeep Burma ◽  
...  

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 723-723
Author(s):  
Alexandra Sobeck ◽  
Stacie Stone ◽  
Bendert deGraaf ◽  
Vincenzo Costanzo ◽  
Johan deWinter ◽  
...  

Abstract Fanconi anemia (FA) is a genetic disorder characterized by hypersensitivity to DNA crosslinking agents and diverse clinical symptoms, including developmental anomalies, progressive bone marrow failure, and predisposition to leukemias and other cancers. FA is genetically heterogeneous, resulting from mutations in any of at least eleven different genes. The FA proteins function together in a pathway composed of a mulitprotein core complex that is required to trigger the DNA-damage dependent activation of the downstream FA protein, FANCD2. This activation is thought to be the key step in a DNA damage response that functionally links FA proteins to major breast cancer susceptibility proteins BRCA1 and BRCA2 (BRCA2 is FA gene FANCD1). The essential function of the FA proteins is unknown, but current models suggest that FA proteins function at the interface between cell cycle checkpoints, DNA repair and DNA replication, and are likely to play roles in the DNA damage response during S phase. To provide a platform for dissecting the key functional events during S-phase, we developed cell-free assays for FA proteins based on replicating extracts from Xenopus eggs. We identified the Xenopus homologs of human FANCD2 (xFANCD2) and several of the FA core complex proteins (xCCPs), and biochemically characterized these proteins in replicating cell-free extracts. We found that xCCPs and a modified isoform of xFANCD2 become associated with chromatin during normal and disrupted DNA replication. Blocking initiation of replication with geminin demonstrated that association of xCCPs and xFANCD2 with chromatin occurs in a strictly replication-dependent manner that is enhanced following DNA damage by crosslinking agents or by addition of aphidicolin, an inhibitor of replicative DNA polymerases. In addition, chromatin binding of xFANCD2, but not xBRCA2, is abrogated when xFANCA is quantitatively depleted from replicating extracts suggesting that xFANCA promotes the loading of xFANCD2 on chromatin. The chromatin-association of xFANCD2 and xCCPs is diminished in the presence of caffeine, an inhibitor of checkpoint kinases. Taken together, our data suggest a model in which the ordered loading of FA proteins on chromatin is required for processing a subset of DNA replication-blocking lesions that are resolved during late stages of replication.


2011 ◽  
Vol 4 (12) ◽  
pp. 1973-1981 ◽  
Author(s):  
Rachid Drissi ◽  
Jing Wu ◽  
Yafang Hu ◽  
Carol Bockhold ◽  
Jeffrey S. Dome

Author(s):  
Kerstin Felgentreff ◽  
Ulrich Baumann ◽  
Christian Klemann ◽  
Catharina Schuetz ◽  
Dorothee Viemann ◽  
...  

AbstractDNA damage is a constant event in every cell caused by exogenous factors such as ultraviolet and ionizing radiation (UVR/IR) and intercalating drugs, or endogenous metabolic and replicative stress. Proteins of the DNA damage response (DDR) network sense DNA lesions and induce cell cycle arrest, DNA repair, and apoptosis. Genetic defects of DDR or DNA repair proteins can be associated with immunodeficiency, bone marrow failure syndromes, and cancer susceptibility. Although various diagnostic tools are available to evaluate DNA damage, their quality to identify DNA repair deficiencies differs enormously and depends on affected pathways. In this study, we investigated the DDR biomarkers γH2AX (Ser139), p-ATM (Ser1981), and p-CHK2 (Thr68) using flow cytometry on peripheral blood cells obtained from patients with combined immunodeficiencies due to non-homologous end-joining (NHEJ) defects and ataxia telangiectasia (AT) in response to low-dose IR. Significantly reduced induction of all three markers was observed in AT patients compared to controls. However, delayed downregulation of γH2AX was found in patients with NHEJ defects. In contrast to previous reports of DDR in cellular models, these biomarkers were not sensitive enough to identify ARTEMIS deficiency with sufficient reliability. In summary, DDR biomarkers are suitable for diagnosing NHEJ defects and AT, which can be useful in neonates with abnormal TREC levels (T cell receptor excision circles) identified by newborn screening. We conclude that DDR biomarkers have benefits and some limitations depending on the underlying DNA repair deficiency.


2020 ◽  
Vol 3 (5) ◽  
pp. e201900494 ◽  
Author(s):  
Akinori Takahashi ◽  
Toru Suzuki ◽  
Shou Soeda ◽  
Shohei Takaoka ◽  
Shungo Kobori ◽  
...  

The biological significance of deadenylation in global gene expression is not fully understood. Here, we show that the CCR4–NOT deadenylase complex maintains expression of mRNAs, such as those encoding transcription factors, cell cycle regulators, DNA damage response–related proteins, and metabolic enzymes, at appropriate levels in the liver. Liver-specific disruption of Cnot1, encoding a scaffold subunit of the CCR4–NOT complex, leads to increased levels of mRNAs for transcription factors, cell cycle regulators, and DNA damage response–related proteins because of reduced deadenylation and stabilization of these mRNAs. CNOT1 suppression also results in an increase of immature, unspliced mRNAs (pre-mRNAs) for apoptosis-related and inflammation-related genes and promotes RNA polymerase II loading on their promoter regions. In contrast, mRNAs encoding metabolic enzymes become less abundant, concomitant with decreased levels of these pre-mRNAs. Lethal hepatitis develops concomitantly with abnormal mRNA expression. Mechanistically, the CCR4–NOT complex targets and destabilizes mRNAs mainly through its association with Argonaute 2 (AGO2) and butyrate response factor 1 (BRF1) in the liver. Therefore, the CCR4–NOT complex contributes to liver homeostasis by modulating the liver transcriptome through mRNA deadenylation.


Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4052-4052
Author(s):  
Travis Witt ◽  
Aloysius Klingelhutz ◽  
Erik Westin ◽  
Preeti Satyanarayana ◽  
Peter M. Lansdorp ◽  
...  

Abstract Dyskeratosis congenita (DC) is an inherited multisystem disorder of premature aging, typically characterized by bone marrow failure, mucosal leukoplakia, abnormal skin pigmentation, and nail dystrophy. The X-linked and autosomal dominant forms of DC are associated with mutations in genes that affect telomerase activity resulting in a decrease in telomere length. DC, like other bone marrow failure disorders, is associated with ineffective hematopoiesis and a cancer predisposition. Standard treatment of bone marrow failure or cancer requires cytotoxic therapy, and clinical observations suggest DC patients have an increased sensitivity to cytotoxic therapy. To explain this, we hypothesized that the short telomeres in somatic cells from DC patients could alter the activity and/or expression of several proteins involved in DNA repair or the response to cellular stress including p16, p53 and p21. Lymphocytes from five DC subjects and age-matched controls were stimulated to grow in vitro in the presence of various cytotoxic agents with different modes of action, including Taxol (antimitotic agent and microtubule inhibitor) and Etoposide (topoisomerase inhibitor and DNA damaging agent). In addition, we tested fibroblasts and keratinocyte extracted from skin biopsies from DC and control subjects that were serially passaged. Cellular proliferation and cell death were monitored by cell counts and flow cytometry. Western blotting was used to measure steady state and DNA damage- induced expression of tumor suppressor protein p53 and other proteins involved in DNA damage response signaling pathway, including p16 and p21 in relation to telomere length. Results of flow cytometry accompanied by direct visualization showed a decreased proliferation of DC lymphocytes compared to normal cells, and this growth disadvantage was further accentuated following cell exposure to cytotoxic agents. DC lymphocytes exposed to 10−6 M Taxol showed a decrease in cellular proliferation between 3 and 8 fold while normal control cells exposed to the same agents exhibited only a 3 to 4 fold decrease in cell growth. Similarly DC lymphocytes exposed to Etoposide were inhibited to a greater extent than control cells. Western blot analysis of whole cell lysates indicated a difference in DNA damage response proteins. Of note, lymphocytes from several DC subjects exposed to Taxol did not upregulate p53 expression, while inducible levels were noted in Taxol-treated control cells. In contrast, DC and control lymphocytes exposed to Etoposide upregulated p53 in a similar dose dependent manner. No differences were noted in DC versus control lymphocytes with regards to basal or chemotherapy induced p16 expression. Interestingly, late passage DC fibroblasts displayed enhanced basal expression of p16. These results support the clinical observation of increased “chemosensitivity” in DC subjects and suggest that diminished telomerase activity and premature telomere shortening may interfere with normal DNA damage and stress response pathways. These data are also consistent with our finding that DC fibroblasts, keratinocytes, and lymphocytes have a reduced cell proliferative lifespan. Further studies are needed to dissect the role of telomeres in the cellular response to various types of DNA damage.


2010 ◽  
Vol 286 (5) ◽  
pp. 3681-3692 ◽  
Author(s):  
Paul Verbruggen ◽  
Marius Ruf ◽  
Gjon Blakqori ◽  
Anna K. Överby ◽  
Martin Heidemann ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document