scholarly journals Chromatin Trapping of Factors Involved in DNA Replication and Repair Underlies Heat-Induced Radio- and Chemosensitization

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1423
Author(s):  
Artem V. Luzhin ◽  
Bogdan Avanesyan ◽  
Artem K. Velichko ◽  
Victoria O. Shender ◽  
Natalia Ovsyannikova ◽  
...  
Keyword(s):  
Dna Repair ◽  
Elevated Temperatures ◽  
Proteomics Data ◽  
Damage Response ◽  
Dna Replication And Repair ◽  
Repair Systems ◽  
Adjuvant Effects ◽  
Cancer Tissues ◽  
Functional Analyses ◽  
First Time

Hyperthermia has been used as an adjuvant treatment for radio- and chemotherapy for decades. In addition to its effects on perfusion and oxygenation of cancer tissues, hyperthermia can enhance the efficacy of DNA-damaging treatments such as radiotherapy and chemotherapy. Although it is believed that the adjuvant effects are based on hyperthermia-induced dysfunction of DNA repair systems, the mechanisms of these dysfunctions remain elusive. Here, we propose that elevated temperatures can induce chromatin trapping (c-trapping) of essential factors, particularly those involved in DNA repair, and thus enhance the sensitization of cancer cells to DNA-damaging therapeutics. Using mass spectrometry-based proteomics, we identified proteins that could potentially undergo c-trapping in response to hyperthermia. Functional analyses of several identified factors involved in DNA repair demonstrated that c-trapping could indeed be a mechanism of hyperthermia-induced transient deficiency of DNA repair systems. Based on our proteomics data, we showed for the first time that hyperthermia could inhibit maturation of Okazaki fragments and activate a corresponding poly(ADP-ribose) polymerase-dependent DNA damage response. Together, our data suggest that chromatin trapping of factors involved in DNA repair and replication contributes to heat-induced radio- and chemosensitization.

scholarly journals Crosstalk between Different DNA Repair Pathways Contributes to Neurodegenerative Diseases

Biology ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 163
Author(s):  
Swapnil Gupta ◽  
Panpan You ◽  
Tanima SenGupta ◽  
Hilde Nilsen ◽  
Kulbhushan Sharma
Keyword(s):  
Dna Repair ◽  
Neurodegenerative Diseases ◽  
3D Models ◽  
Model Systems ◽  
Spinocerebellar Ataxias ◽  
C Elegans ◽  
Cellular Processes ◽  
Age Related ◽  
Damage Response ◽  
Lateral Sclerosis

Genomic integrity is maintained by DNA repair and the DNA damage response (DDR). Defects in certain DNA repair genes give rise to many rare progressive neurodegenerative diseases (NDDs), such as ocular motor ataxia, Huntington disease (HD), and spinocerebellar ataxias (SCA). Dysregulation or dysfunction of DDR is also proposed to contribute to more common NDDs, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and Amyotrophic Lateral Sclerosis (ALS). Here, we present mechanisms that link DDR with neurodegeneration in rare NDDs caused by defects in the DDR and discuss the relevance for more common age-related neurodegenerative diseases. Moreover, we highlight recent insight into the crosstalk between the DDR and other cellular processes known to be disturbed during NDDs. We compare the strengths and limitations of established model systems to model human NDDs, ranging from C. elegans and mouse models towards advanced stem cell-based 3D models.

scholarly journals DNA Damage Response in Multiple Myeloma: The Role of the Tumor Microenvironment

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 504
Author(s):  
Takayuki Saitoh ◽  
Tsukasa Oda
Keyword(s):  
Multiple Myeloma ◽  
Dna Damage ◽  
Dna Repair ◽  
Tumor Microenvironment ◽  
Dna Damage Response ◽  
Genetic Instability ◽  
Dna Repair Mechanisms ◽  
Damage Response ◽  
Repair Mechanisms

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by genomic instability. MM cells present various forms of genetic instability, including chromosomal instability, microsatellite instability, and base-pair alterations, as well as changes in chromosome number. The tumor microenvironment and an abnormal DNA repair function affect genetic instability in this disease. In addition, states of the tumor microenvironment itself, such as inflammation and hypoxia, influence the DNA damage response, which includes DNA repair mechanisms, cell cycle checkpoints, and apoptotic pathways. Unrepaired DNA damage in tumor cells has been shown to exacerbate genomic instability and aberrant features that enable MM progression and drug resistance. This review provides an overview of the DNA repair pathways, with a special focus on their function in MM, and discusses the role of the tumor microenvironment in governing DNA repair mechanisms.

scholarly journals Harnessing the Nucleolar DNA Damage Response in Cancer Therapy

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1156
Author(s):  
Jiachen Xuan ◽  
Kezia Gitareja ◽  
Natalie Brajanovski ◽  
Elaine Sanij
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Cancer Therapy ◽  
Dna Damage Response ◽  
Rrna Genes ◽  
Rrna Synthesis ◽  
Pol I ◽  
Clinical Investigations ◽  
Damage Response ◽  
Synthesis And Processing

The nucleoli are subdomains of the nucleus that form around actively transcribed ribosomal RNA (rRNA) genes. They serve as the site of rRNA synthesis and processing, and ribosome assembly. There are 400–600 copies of rRNA genes (rDNA) in human cells and their highly repetitive and transcribed nature poses a challenge for DNA repair and replication machineries. It is only in the last 7 years that the DNA damage response and processes of DNA repair at the rDNA repeats have been recognized to be unique and distinct from the classic response to DNA damage in the nucleoplasm. In the last decade, the nucleolus has also emerged as a central hub for coordinating responses to stress via sequestering tumor suppressors, DNA repair and cell cycle factors until they are required for their functional role in the nucleoplasm. In this review, we focus on features of the rDNA repeats that make them highly vulnerable to DNA damage and the mechanisms by which rDNA damage is repaired. We highlight the molecular consequences of rDNA damage including activation of the nucleolar DNA damage response, which is emerging as a unique response that can be exploited in anti-cancer therapy. In this review, we focus on CX-5461, a novel inhibitor of Pol I transcription that induces the nucleolar DNA damage response and is showing increasing promise in clinical investigations.

scholarly journals Female ageing affects the DNA repair capacity of oocytes in IVF using a controlled model of sperm DNA damage in mice

2020 ◽  
Vol 35 (3) ◽  
pp. 529-544 ◽  
Author(s):  
F Horta ◽  
S Catt ◽  
P Ramachandran ◽  
B Vollenhoven ◽  
P Temple-Smith
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Dna Repair ◽  
Age Groups ◽  
Oocyte Quality ◽  
Repair Capacity ◽  
Sperm Dna Damage ◽  
Dna Repair Capacity ◽  
Sperm Dna ◽  
Damage Response

Abstract STUDY QUESTION Does female ageing have a negative effect on the DNA repair capacity of oocytes fertilised by spermatozoa with controlled levels of DNA damage? SUMMARY ANSWER Compared to oocytes from younger females, oocytes from older females have a reduced capacity to repair damaged DNA introduced by spermatozoa. WHAT IS KNOWN ALREADY The reproductive lifespan in women declines with age predominantly due to poor oocyte quality. This leads to decreased reproductive outcomes for older women undergoing assisted reproductive technology (ART) treatments, compared to young women. Ageing and oocyte quality have been clearly associated with aneuploidy, but the range of factors that influence this change in oocyte quality with age remains unclear. The DNA repair activity prior to embryonic genomic activation is considered to be of maternal origin, with maternal transcripts and proteins controlling DNA integrity. With increasing maternal age, the number of mRNAs stored in oocytes decreases. This could result in diminished efficiency of DNA repair and/or negative effects on embryo development, especially in the presence of DNA damage. STUDY DESIGN, SIZE, DURATION Oocytes from two age groups of 30 super-ovulated female mice (young: 5–8 weeks old, n = 15; old: 42–45 weeks old, n = 15) were inseminated with sperm from five males with three different controlled DNA damage levels; control: ≤10%, 1 Gray (Gy): 11–30%, and 30 Gy: >30%. Inseminated oocytes (young: 125, old: 78) were assessed for the formation of zygotes (per oocyte) and blastocysts (per zygote). Five replicates of five germinal vesicles (GVs) and five MII oocytes from each age group were analysed for gene expression. The DNA damage response (DDR) was assessed in a minimum of three IVF replicates in control and 1 Gy zygotes and two-cell embryos using γH2AX labelling. PARTICIPANTS/MATERIALS, SETTING, METHODS Swim-up sperm samples from the cauda epididymidis of C57BL6 mice were divided into control (no irradiation) and 1- and 30-Gy groups. Treated spermatozoa were irradiated at 1 and 30 Gy, respectively, using a linear accelerator Varian 21iX. Following irradiation, samples were used for DNA damage assessment (Halomax) and for insemination. Presumed zygotes were cultured in a time-lapse incubator (MIRI, ESCO). Gene expression of 91 DNA repair genes was assessed using the Fluidigm Biomark HD system. The DNA damage response in zygotes (6–8 h post-fertilisation) and two-cell embryos (22–24 h post-fertilisation) was assessed by immunocytochemical analysis of γH2AX using confocal microscopy (Olympus FV1200) and 3D volumetric analysis using IMARIS software. MAIN RESULTS AND THE ROLE OF CHANCE The average sperm DNA damage for the three groups was statistically different (control: 6.1%, 1 Gy: 16.1%, 30 Gy: 53.1%, P < 0.0001), but there were no significant differences in fertilisation rates after IVF within or between the two age groups [(young; control: 86.79%, 1 Gy: 82.75%, 30 Gy: 76.74%) (old; control: 93.1%, 1 Gy: 70.37%, 30 Gy: 68.18%) Fisher’s exact]. However, blastocyst rates were significantly different (P < 0.0001) among the groups [(young; control: 86.95%, 1 Gy: 33.33%, 30 Gy: 0.0%) (old; control: 70.37%, 1 Gy: 0.0%, 30 Gy: 0.0%)]. Between the age groups, 1-Gy samples showed a significant decrease in the blastocyst rate in old females compared to young females (P = 0.0166). Gene expression analysis revealed a decrease in relative expression of 21 DNA repair genes in old GV oocytes compared to young GV oocytes (P < 0.05), and similarly, old MII oocytes showed 23 genes with reduced expression compared to young MII oocytes (P < 0.05). The number of genes with decreased expression in older GV and MII oocytes significantly affected pathways such as double strand break (GV: 5; MII: 6), nucleotide excision repair (GV: 8; MII: 5) and DNA damage response (GV: 4; MII: 8). There was a decreased DDR in zygotes and in two-cell embryos from old females compared to young regardless of sperm treatment (P < 0.05). The decrease in DNA repair gene expression of oocytes and decreased DDR in embryos derived from older females suggests that ageing results in a diminished DNA repair capacity. LARGE-SCALE DATA N/A LIMITATIONS, REASONS FOR CAUTION Ionising radiation was used only for experimental purposes, aiming at controlled levels of sperm DNA damage; however, it can also damage spermatozoa proteins. The female age groups selected in mice were intended to model effects in young and old women, but clinical studies are required to demonstrate a similar effect. WIDER IMPLICATIONS OF THE FINDINGS Fertilisation can occur with sperm populations with medium and high DNA damage, but subsequent embryo growth is affected to a greater extent with aging females, supporting the theory that oocyte DNA repair capacity decreases with age. Assessment of the oocyte DNA repair capacity may be a useful diagnostic tool for infertile couples. STUDY FUNDING/COMPETING INTEREST(S) Funded by the Education Program in Reproduction and Development, Department of Obstetrics and Gynaecology, Monash University. None of the authors has any conflict of interest to report.

scholarly journals Profilin-1; a novel regulator of DNA damage response and repair machinery in keratinocytes

2021 ◽  
Author(s):  
Chang-Jin Lee ◽  
Min-Ji Yoon ◽  
Dong Hyun Kim ◽  
Tae Uk Kim ◽  
Youn-Jung Kang
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Recovery Time ◽  
Actin Polymerization ◽  
Loss Of Function ◽  
Dna Double Strand Breaks ◽  
Pten Loss ◽  
Damage Response ◽  
Specific Regulation

AbstractProfilin-1 (PFN1) regulates actin polymerization and cytoskeletal growth. Despite the essential roles of PFN1 in cell integration, its subcellular function in keratinocyte has not been elucidated yet. Here we characterize the specific regulation of PFN1 in DNA damage response and repair machinery. PFN1 depletion accelerated DNA damage-mediated apoptosis exhibiting PTEN loss of function instigated by increased phosphorylated inactivation followed by high levels of AKT activation. PFN1 changed its predominant cytoplasmic localization to the nucleus upon DNA damage and subsequently restored the cytoplasmic compartment during the recovery time. Even though γH2AX was recruited at the sites of DNA double strand breaks in response to DNA damage, PFN1-deficient cells failed to recruit DNA repair factors, whereas control cells exhibited significant increases of these genes. Additionally, PFN1 depletion resulted in disruption of PTEN-AKT cascade upon DNA damage and CHK1-mediated cell cycle arrest was not recovered even after the recovery time exhibiting γH2AX accumulation. This might suggest PFN1 roles in regulating DNA damage response and repair machinery to protect cells from DNA damage. Future studies addressing the crosstalk and regulation of PTEN-related DNA damage sensing and repair pathway choice by PFN1 may further aid to identify new mechanistic insights for various DNA repair disorders.

scholarly journals Temperature and UV light affect the activity of marine cell-free enzymes

2017 ◽  
Vol 14 (17) ◽  
pp. 3971-3977 ◽  
Author(s):  
Blair Thomson ◽  
Christopher David Hepburn ◽  
Miles Lamare ◽  
Federico Baltar
Keyword(s):  
Organic Matter ◽  
Extracellular Enzymes ◽  
Elevated Temperatures ◽  
Uv Light ◽  
Control Mechanisms ◽  
Potential Control ◽  
Control Factors ◽  
Rate Limiting Step ◽  
Ocean Environment ◽  
First Time

Abstract. Microbial extracellular enzymatic activity (EEA) is the rate-limiting step in the degradation of organic matter in the oceans. These extracellular enzymes exist in two forms: cell-bound, which are attached to the microbial cell wall, and cell-free, which are completely free of the cell. Contrary to previous understanding, cell-free extracellular enzymes make up a substantial proportion of the total marine EEA. Little is known about these abundant cell-free enzymes, including what factors control their activity once they are away from their sites (cells). Experiments were run to assess how cell-free enzymes (excluding microbes) respond to ultraviolet radiation (UVR) and temperature manipulations, previously suggested as potential control factors for these enzymes. The experiments were done with New Zealand coastal waters and the enzymes studied were alkaline phosphatase (APase), β-glucosidase, (BGase), and leucine aminopeptidase (LAPase). Environmentally relevant UVR (i.e. in situ UVR levels measured at our site) reduced cell-free enzyme activities by up to 87 % when compared to controls, likely a consequence of photodegradation. This effect of UVR on cell-free enzymes differed depending on the UVR fraction. Ambient levels of UV radiation were shown to reduce the activity of cell-free enzymes for the first time. Elevated temperatures (15 °C) increased the activity of cell-free enzymes by up to 53 % when compared to controls (10 °C), likely by enhancing the catalytic activity of the enzymes. Our results suggest the importance of both UVR and temperature as control mechanisms for cell-free enzymes. Given the projected warming ocean environment and the variable UVR light regime, it is possible that there could be major changes in the cell-free EEA and in the enzymes contribution to organic matter remineralization in the future.

scholarly journals Mass bleaching of soft coral, Sarcophyton spp. in Thailand and the role of temperature and salinity stress

2009 ◽  
Vol 66 (7) ◽  
pp. 1515-1519 ◽  
Author(s):  
Suchana Chavanich ◽  
Voranop Viyakarn ◽  
Thepsuda Loyjiw ◽  
Priyapat Pattaratamrong ◽  
Anchalee Chankong
Keyword(s):  
Salinity Stress ◽  
Soft Coral ◽  
Elevated Temperatures ◽  
Gulf Of Thailand ◽  
Field Observations ◽  
Experimental Trial ◽  
First Time ◽  
Upper Gulf Of Thailand ◽  
Mass Bleaching

Abstract Chavanich, S., Viyakarn, V., Loyjiw, T., Pattaratamrong, P., and Chankong, A. 2009. Mass bleaching of soft coral, Sarcophyton spp. in Thailand and the role of temperature and salinity stress. – ICES Journal of Marine Science, 66: 1515–1519. From June to October 2006 and 2007, mass bleaching of the soft coral, Sarcophyton spp., occurred for the first time in the upper Gulf of Thailand. Approximately 90% of the populations experienced extensive bleaching, and almost 95% of colonies were affected. Field observations also revealed that fragmentation of Sarcophyton spp. set in 1 month after the onset of bleaching. Some colonies started to recover to some extent by the end of July, with 95% of the population of Sarcophyton spp. recovering by October. Both acute and chronic trials were conducted to determine whether temperature and/or salinity triggered bleaching. In the acute tests, Sarcophyton spp. at 40°C and salinity 20 psu were completely bleached, and death occurred after 57 and 204 h, respectively. However, the colonies at 40 psu could survive through the experimental trial. In the chronic tests, Sarcophyton spp. died when exposed to 34°C, whereas complete bleaching and mortality of Sarcophyton spp. occurred at salinities of 10 and 49 psu. We conclude that elevated temperatures had a greater effect on the bleaching of Sarcophyton spp. than did salinity.

scholarly journals 900 Depleting non-canonical, cell-intrinsic PD-L1 signals induces synthetic lethality to small molecule DNA damage response inhibitors in an immune independent and dependent manner

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A944-A944
Author(s):  
Anand Kornepati ◽  
Clare Murray ◽  
Barbara Avalos ◽  
Cody Rogers ◽  
Kavya Ramkumar ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Damage ◽  
Dna Repair ◽  
Cell Lines ◽  
Dna Damage Response ◽  
Small Molecule ◽  
Treatment Resistance ◽  
Programmed Death ◽  
Damage Response ◽  
Response Biomarker

BackgroundTumor surface-expressed programmed death-ligand 1 (PD-L1) suppresses immunity when it engages programmed death-1 (PD-1) on anti-tumor immune cells in canonical PD-L1/PD-1.1 Non-canonical, tumour-intrinsic PD-L1 signals can mediate treatment resistance2–6 but mechanisms remain incompletely understood. Targeting non-canonical, cell-intrinsic PD-L1 signals, especially modulation of the DNA damage response (DDR), remains largely untapped.MethodsWe made PD-L1 knockout (PD-L1 KO) murine transplantable and human cell lines representing melanoma, bladder, and breast histologies. We used biochemical, genetic, and cell-biology techniques for mechanistic insights into tumor-intrinsic PD-L1 control of specific DDR and DNA repair pathways. We generated a novel inducible melanoma GEMM lacking PD-L1 only in melanocytes to corroborate DDR alterations observed in PD-L1 KO of established tumors.ResultsGenetic tumor PD-L1 depletion destabilized Chk2 and impaired ATM/Chk2, but not ATR/Chk1 DDR. PD-L1KO increased DNA damage (γH2AX) and impaired homologous recombination DNA repair (p-RPA32, BRCA1, RAD51 nuclear foci) and function (DR-GFP reporter). PD-L1 KO cells were significantly more sensitive versus controls to DDR inhibitors (DDRi) against ATR, Chk1, and PARP but not ATM in multiple human and mouse tumor models in vitro and in vivo in NSG mice. PD-1 independent, intracellular, not surface PD-L1 stabilized Chk2 protein with minimal Chek2 mRNA effect. Mechanistically, PD-L1 could directly complex with Chk2, protecting it from PIRH2-mediated polyubiquitination. PD-L1 N-terminal domains Ig-V and Ig-C but not the PD-L1 C-terminal tail co-IP’d with Chk2 and restored Chk1 inhibitor (Chk1i) treatment resistance. Tumor PD-L1 expression correlated with Chk1i sensitivity in 44 primary human small cell lung cancer cell lines, implicating tumor-intrinsic PD-L1 as a DDRi response biomarker. In WT mice, genetic PD-L1 depletion but not surface PD-L1 blockade with αPD-L1, sensitized immunotherapy-resistant, BRCA1-WT 4T1 tumors to PARP inhibitor (PARPi). PARPi effects were reduced on PD-L1 KO tumors in RAG2KO mice indicating immune-dependent DDRi efficacy. Tumor PD-L1 depletion, likely due to impaired DDR, enhanced PARPi induced tumor-intrinsic STING activation (e.g., p-TBK1, CCL5) suggesting potential to augment immunotherapies.ConclusionsWe challenge the prevailing surface PD-L1 paradigm and establish a novel mechanism for cell-intrinsic PD-L1 control of the DDR and gene product expression. We identify therapeutic vulnerabilities from tumor PD-L1 depletion utilizing small molecule DDRi currently being tested in clinical trials. Data could explain αPD-L1/DDRi treatment resistance. Intracellular PD-L1 could be a pharmacologically targetable treatment target and/or response biomarker for selective DDRi alone plus other immunotherapies.ReferencesTopalian SL, Taube JM, Anders RA, Pardoll DM. Mechanism-driven biomarkers to guide immune checkpoint blockade in cancer therapy. Nat Rev Cancer 16:275–287, doi:10.1038/nrc.2016.36 (2016).Clark CA, et al. Tumor-intrinsic PD-L1 signals regulate cell growth, pathogenesis and autophagy in ovarian cancer and melanoma. Canres 0258.2016 (2016).Gupta HB et al. Tumor cell-intrinsic PD-L1 promotes tumor-initiating cell generation and functions in melanoma and ovarian cancer. 1, 16030 (2016).Zhu H, et al. BET bromodomain inhibition promotes anti-tumor immunity by suppressing PD-L1 expression. Cell Rep 16:2829–2837, doi:10.1016/j.celrep.2016.08.032 (2016)Wu B, et al. Adipose PD-L1 modulates PD-1/PD-L1 checkpoint blockade immunotherapy efficacy in breast cancer. Oncoimmunology 7:e1500107, doi:10.1080/2162402X.2018.1500107 (2018)Liang J, et al. Verteporfin inhibits PD-L1 through autophagy and the STAT1-IRF1-TRIM28 signaling axis, exerting antitumor efficacy. Cancer Immunol Res 8:952–965, doi:10.1158/2326-6066.CIR-19-0159 (2020)

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.

Sign in / Sign up

Export Citation Format

Share Document