Hof1 plays a checkpoint-related role in MMS-induced DNA damage response in  Candida albicans

Fifty-six strains from the GRACE collection were found to be sensitive to MMS upon repression. Deletion of the HOF1 gene renders sensitivity to genotoxic stress. Hof1 is genetically linked to the Rad53 pathway and is down-regulated in a Rad53-dependent manner. The importance of Hof1 in MMS response is reduced in a Rad23 or Rad4 mutant strain.

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Genetic interaction between Ptc2 and protein phosphatase 4 (PP4) in the regulation of DNA damage response and virulence in Candida albicans

FEMS Yeast Research ◽

10.1093/femsyr/foz075 ◽

2019 ◽

Vol 19 (8) ◽

Cited By ~ 2

Author(s):

Jia Feng ◽

Aidi Shan ◽

Jing Hu ◽

Zhenyu Cao ◽

Rui Lv ◽

...

Keyword(s):

Dna Damage ◽

Candida Albicans ◽

Dna Damage Response ◽

Protein Phosphatase ◽

Genetic Interaction ◽

Pathogenic Fungus ◽

Single Gene ◽

Critical Role ◽

Genotoxic Stress ◽

Damage Response

ABSTRACT In the pathogenic fungus Candida albicans, phosphoregulation of the checkpoint kinase Rad53 plays a crucial role in the filamentous growth response to genotoxic stresses. The protein phosphatase 4 (PP4) complex, containing Pph3 and either Psy2 or Psy4, is proved to play a critical role in Rad53 dephosphorylation. In previous studies, we characterized CaPtc2 (the ortholog of both Ptc2 and Ptc3 in Saccharomyces cerevisiae) as a potential DNA-damage-related protein phosphatase. In this study, we checked the genetic interaction of PTC2 with the PP4 complex in the DNA damage response pathway. The results suggest that Ptc2 shows a negative genetic interaction with Pph3, but positive genetic interaction with either Psy2 or Psy4 in response to genotoxic stress. Deletion of PTC2 alone resulted in no significant change in cell virulence, but double deletion of PTC2 PPH3 significantly decreased virulence, while double deletions of either PTC2 PSY2 or PTC2 PSY4 caused virulence levels similar to that shown by PSY2 or PSY4 single-gene deletion cells. Taken together, we propose that Ptc2 in C. albicans plays a compensatory role for Pph3 but is dependent on Psy2 and Psy4 in regulation of DNA damage and cell virulence.

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Functional Roles of Homologous Recombination and Non-Homologous End Joining in DNA Damage Response and Microevolution in Cryptococcus neoformans

Journal of Fungi ◽

10.3390/jof7070566 ◽

2021 ◽

Vol 7 (7) ◽

pp. 566

Author(s):

Kwang-Woo Jung ◽

Jong-Hyun Jung ◽

Ha-Young Park

Keyword(s):

Dna Damage ◽

Homologous Recombination ◽

Cryptococcus Neoformans ◽

Dna Damage Response ◽

Genotoxic Stress ◽

Dna Lesions ◽

Dependent Manner ◽

End Joining ◽

Damage Response ◽

Non Homologous End Joining

DNA double-strand breaks (DSBs) are the most deleterious type of DNA lesions because they cause loss of genetic information if not properly repaired. In eukaryotes, homologous recombination (HR) and non-homologous end joining (NHEJ) are required for DSB repair. However, the relationship of HR and NHEJ in DNA damage stress is unknown in the radiation-resistant fungus Cryptococcus neoformans. In this study, we found that the expression levels of HR- and NHEJ-related genes were highly induced in a Rad53–Bdr1 pathway-dependent manner under genotoxic stress. Deletion of RAD51, which is one of the main components in the HR, resulted in growth under diverse types of DNA damage stress, whereas perturbations of KU70 and KU80, which belong to the NHEJ system, did not affect the genotoxic stresses except when bleomycin was used for treatment. Furthermore, deletion of both RAD51 and KU70/80 renders cells susceptible to oxidative stress. Notably, we found that deletion of RAD51 induced a hypermutator phenotype in the fluctuation assay. In contrast to the fluctuation assay, perturbation of KU70 or KU80 induced rapid microevolution similar to that induced by the deletion of RAD51. Collectively, Rad51-mediated HR and Ku70/Ku80-mediated NHEJ regulate the DNA damage response and maintain genome stability.

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Nucleotide Excision Repair Protein Rad23 Regulates Cell Virulence Independent of Rad4 in Candida albicans

mSphere ◽

10.1128/msphere.00062-20 ◽

2020 ◽

Vol 5 (1) ◽

Cited By ~ 1

Author(s):

Jia Feng ◽

Shuangyan Yao ◽

Yansong Dong ◽

Jing Hu ◽

Malcolm Whiteway ◽

...

Keyword(s):

Dna Damage ◽

Candida Albicans ◽

Nucleotide Excision Repair ◽

Dna Damage Response ◽

Excision Repair ◽

Content Type ◽

Virulence Regulation ◽

Nucleotide Excision ◽

Damage Response

ABSTRACT In the pathogenic yeast Candida albicans, the DNA damage response contributes to pathogenicity by regulating cell morphology transitions and maintaining survival in response to DNA damage induced by reactive oxygen species (ROS) in host cells. However, the function of nucleotide excision repair (NER) in C. albicans has not been extensively investigated. To better understand the DNA damage response and its role in virulence, we studied the function of the Rad23 nucleotide excision repair protein in detail. The RAD23 deletion strain and overexpression strain both exhibit UV sensitivity, confirming the critical role of RAD23 in the nucleotide excision repair pathway. Genetic interaction assays revealed that the role of RAD23 in the UV response relies on RAD4 but is independent of RAD53, MMS22, and RAD18. RAD4 and RAD23 have similar roles in regulating cell morphogenesis and biofilm formation; however, only RAD23, but not RAD4, plays a negative role in virulence regulation in a mouse model. We found that the RAD23 deletion strain showed decreased survival in a Candida-macrophage interaction assay. Transcriptome sequencing (RNA-seq) and quantitative real-time PCR (qRT-PCR) data further revealed that RAD23, but not RAD4, regulates the transcription of a virulence factor, SUN41, suggesting a unique role of RAD23 in virulence regulation. Taking these observations together, our work reveals that the RAD23-related nucleotide excision pathway plays a critical role in the UV response but may not play a direct role in virulence. The virulence-related role of RAD23 may rely on the regulation of several virulence factors, which may give us further understanding about the linkage between DNA damage repair and virulence regulation in C. albicans. IMPORTANCE Candida albicans remains a significant threat to the lives of immunocompromised people. An understanding of the virulence and infection ability of C. albicans cells in the mammalian host may help with clinical treatment and drug discovery. The DNA damage response pathway is closely related to morphology regulation and virulence, as well as the ability to survive in host cells. In this study, we checked the role of the nucleotide excision repair (NER) pathway, the key repair system that functions to remove a large variety of DNA lesions such as those caused by UV light, but whose function has not been well studied in C. albicans. We found that Rad23, but not Rad4, plays a role in virulence that appears independent of the function of the NER pathway. Our research revealed that the NER pathway represented by Rad4/Rad23 may not play a direct role in virulence but that Rad23 may play a unique role in regulating the transcription of virulence genes that may contribute to the virulence of C. albicans.

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ATF4-Mediated Upregulation of REDD1 and Sestrin2 Suppresses mTORC1 Activity during Prolonged Leucine Deprivation

Journal of Nutrition ◽

10.1093/jn/nxz309 ◽

2019 ◽

Vol 150 (5) ◽

pp. 1022-1030 ◽

Cited By ~ 5

Author(s):

Dandan Xu ◽

Weiwei Dai ◽

Lydia Kutzler ◽

Holly A Lacko ◽

Leonard S Jefferson ◽

...

Keyword(s):

Amino Acids ◽

Dna Damage ◽

Amino Acid ◽

Protein Kinase ◽

Dna Damage Response ◽

Dependent Manner ◽

Mouse Embryo Fibroblasts ◽

Damage Response ◽

Mtorc1 Activation ◽

In Cells

ABSTRACT Background The protein kinase target of rapamycin (mTOR) in complex 1 (mTORC1) is activated by amino acids and in turn upregulates anabolic processes. Under nutrient-deficient conditions, e.g., amino acid insufficiency, mTORC1 activity is suppressed and autophagy is activated. Intralysosomal amino acids generated by autophagy reactivate mTORC1. However, sustained mTORC1 activation during periods of nutrient insufficiency would likely be detrimental to cellular homeostasis. Thus, mechanisms must exist to prevent amino acids released by autophagy from reactivating the kinase. Objective The objective of the present study was to test whether mTORC1 activity is inhibited during prolonged leucine deprivation through ATF4-dependent upregulation of the mTORC1 suppressors regulated in development and DNA damage response 1 (REDD1) and Sestrin2. Methods Mice (8 wk old; C57Bl/6 × 129SvEV) were food deprived (FD) overnight and one-half were refed the next morning. Mouse embryo fibroblasts (MEFs) deficient in ATF4, REDD1, and/or Sestrin2 were deprived of leucine for 0–16 h. mTORC1 activity and ATF4, REDD1, and Sestrin2 expression were assessed in liver and cell lysates. Results Refeeding FD mice resulted in activation of mTORC1 in association with suppressed expression of both REDD1 and Sestrin2 in the liver. In cells in culture, mTORC1 exhibited a triphasic response to leucine deprivation, with an initial suppression followed by a transient reactivation from 2 to 4 h and a subsequent resuppression after 8 h. Resuppression occurred concomitantly with upregulated expression of ATF4, REDD1, and Sestrin2. However, in cells lacking ATF4, neither REDD1 nor Sestrin2 expression was upregulated by leucine deprivation, and resuppression of mTORC1 was absent. Moreover, in cells lacking either REDD1 or Sestrin2, mTORC1 resuppression was attenuated, and in cells lacking both proteins resuppression was further blunted. Conclusions The results suggest that leucine deprivation upregulates expression of both REDD1 and Sestrin2 in an ATF4-dependent manner, and that upregulated expression of both proteins is involved in resuppression of mTORC1 during prolonged leucine deprivation.

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MORC2 regulates DNA damage response through a PARP1-dependent pathway

Nucleic Acids Research ◽

10.1093/nar/gkz545 ◽

2019 ◽

Vol 47 (16) ◽

pp. 8502-8520 ◽

Cited By ~ 4

Author(s):

Lin Zhang ◽

Da-Qiang Li

Keyword(s):

Dna Damage ◽

Zinc Finger ◽

Chromatin Remodeling ◽

Dna Damage Response ◽

Mammalian Cells ◽

Cellular Response ◽

Genotoxic Stress ◽

Underlying Mechanism ◽

Dna Lesions ◽

Damage Response

Abstract Microrchidia family CW-type zinc finger 2 (MORC2) is a newly identified chromatin remodeling enzyme with an emerging role in DNA damage response (DDR), but the underlying mechanism remains largely unknown. Here, we show that poly(ADP-ribose) polymerase 1 (PARP1), a key chromatin-associated enzyme responsible for the synthesis of poly(ADP-ribose) (PAR) polymers in mammalian cells, interacts with and PARylates MORC2 at two residues within its conserved CW-type zinc finger domain. Following DNA damage, PARP1 recruits MORC2 to DNA damage sites and catalyzes MORC2 PARylation, which stimulates its ATPase and chromatin remodeling activities. Mutation of PARylation residues in MORC2 results in reduced cell survival after DNA damage. MORC2, in turn, stabilizes PARP1 through enhancing acetyltransferase NAT10-mediated acetylation of PARP1 at lysine 949, which blocks its ubiquitination at the same residue and subsequent degradation by E3 ubiquitin ligase CHFR. Consequently, depletion of MORC2 or expression of an acetylation-defective PARP1 mutant impairs DNA damage-induced PAR production and PAR-dependent recruitment of DNA repair proteins to DNA lesions, leading to enhanced sensitivity to genotoxic stress. Collectively, these findings uncover a previously unrecognized mechanistic link between MORC2 and PARP1 in the regulation of cellular response to DNA damage.

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Ribosomal protein L6 (RPL6) is recruited to DNA damage sites in a poly(ADP-ribose) polymerase–dependent manner and regulates the DNA damage response

Journal of Biological Chemistry ◽

10.1074/jbc.ra118.007009 ◽

2018 ◽

Vol 294 (8) ◽

pp. 2827-2838 ◽

Cited By ~ 10

Author(s):

Chuanzhen Yang ◽

Weicheng Zang ◽

Yapeng Ji ◽

Tingting Li ◽

Yongfeng Yang ◽

...

Keyword(s):

Dna Damage ◽

Ribosomal Protein ◽

Dna Damage Response ◽

Dependent Manner ◽

Damage Response

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Coordinated Chromatin-Association of Fanconi Anemia Network Proteins Requires Replication-Coupled DNA Damage Recognition.

Blood ◽

10.1182/blood.v104.11.723.723 ◽

2004 ◽

Vol 104 (11) ◽

pp. 723-723

Author(s):

Alexandra Sobeck ◽

Stacie Stone ◽

Bendert deGraaf ◽

Vincenzo Costanzo ◽

Johan deWinter ◽

...

Keyword(s):

Dna Damage ◽

Dna Replication ◽

Dna Damage Response ◽

Fanconi Anemia ◽

Bone Marrow Failure ◽

S Phase ◽

Dependent Manner ◽

Core Complex ◽

Damage Response ◽

Crosslinking Agents

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.

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Sensitivity of tumor cells deficient in the fanconi anemia pathway to inhibition of ataxia telangiectasia mutated (ATM)

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.10509 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 10509-10509

Author(s):

R. D. Kennedy ◽

P. Stuckert ◽

E. Archila ◽

M. De LaVega ◽

C. Chen ◽

...

Keyword(s):

Dna Damage ◽

Cell Lines ◽

Dna Damage Response ◽

Fanconi Anemia ◽

Ataxia Telangiectasia ◽

Pancreatic Head ◽

Genotoxic Stress ◽

Ataxia Telangiectasia Mutated ◽

Chromosomal Breakage ◽

Damage Response

10509 Loss of the fanconi anemia (FA) pathway function has been described in a number of sporadic tumor types including breast, ovarian, pancreatic, head and neck and hematological malignancies. Functionally, the FA pathway responds to stalled DNA replication following DNA damage. Given the importance of the FA pathway in the response to DNA damage, we hypothesized that cells deficient in this pathway may become hyper-dependent on alternative DNA damage response pathways in order to respond to endogenous genotoxic stress such as occurs during metabolism. Therefore, targeting these alternative pathways could offer therapeutic strategies in FA pathway deficient tumors. To identify new therapeutic targets we treated FA pathway competent and deficient cells with a DNA damage response siRNA library, that individually knocked out 230 genes. We identified a number of gene targets that were specifically toxic to FA pathway deficient cells, amongst which was the DNA damage response kinase Ataxia Telangiectasia Mutated (ATM). To test the requirement for ATM in FA pathway deficient cells, we interbred Fancg ± Atm± mice. Consistent with the siRNA screen result, Fancg-/- Atm-/- mice were non viable and Fancg± Atm-/- and Fancg-/- Atm ± progeny were less frequent that would have been expected. Several human cell lines with FA gene mutations were observed to have constitutive activation of ATM which was markedly reduced on correction with the appropriate wild-type FA gene. Interestingly, FA pathway deficient cells, including the FANCC mutant and FANCG mutant pancreatic cancer cell lines, were selectively sensitive to monotherapy with the ATM inhibitor KU55933, as measured by dose inhibition and colony count assays. FA pathway deficient cells also demonstrated an increased level of chromosomal breakage, cell cycle arrest and apoptosis following KU55933 treatment when compared to FA pathway corrected cells. We conclude that FA pathway deficient cells have an increased requirement for ATM activation in order to respond to sporadic DNA damage. This offers the possibility that monotherapy with ATM inhibitors could be a therapeutic strategy for tumors that are deficient for the FA pathway. No significant financial relationships to disclose.

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ATM regulates a DNA damage response posttranscriptional RNA operon in lymphocytes

Blood ◽

10.1182/blood-2010-09-310987 ◽

2011 ◽

Vol 117 (8) ◽

pp. 2441-2450 ◽

Cited By ~ 27

Author(s):

Krystyna Mazan-Mamczarz ◽

Patrick R. Hagner ◽

Yongqing Zhang ◽

Bojie Dai ◽

Elin Lehrmann ◽

...

Keyword(s):

Gene Expression ◽

Dna Damage ◽

Dna Damage Response ◽

Ataxia Telangiectasia ◽

Rna Binding ◽

Critical Role ◽

Cell Cycle Checkpoints ◽

Dependent Manner ◽

Damage Response ◽

Multiple Cell

Abstract Maintenance of genomic stability depends on the DNA damage response, a biologic barrier in early stages of cancer development. Failure of this response results in genomic instability and high predisposition toward lymphoma, as seen in patients with ataxia-telangiectasia mutated (ATM) dysfunction. ATM activates multiple cell-cycle checkpoints and DNA repair after DNA damage, but its influence on posttranscriptional gene expression has not been examined on a global level. We show that ionizing radiation modulates the dynamic association of the RNA-binding protein HuR with target mRNAs in an ATM-dependent manner, potentially coordinating the genotoxic response as an RNA operon. Pharmacologic ATM inhibition and use of ATM-null cells revealed a critical role for ATM in this process. Numerous mRNAs encoding cancer-related proteins were differentially associated with HuR depending on the functional state of ATM, in turn affecting expression of encoded proteins. The findings presented here reveal a previously unidentified role of ATM in controlling gene expression posttranscriptionally. Dysregulation of this DNA damage response RNA operon is probably relevant to lymphoma development in ataxia-telangiectasia persons. These novel RNA regulatory modules and genetic networks provide critical insight into the function of ATM in oncogenesis.

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