scholarly journals HPF1 dynamically controls the PARP1/2 balance between initiating and elongating ADP-ribose modifications

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marie-France Langelier ◽  
Ramya Billur ◽  
Aleksandr Sverzhinsky ◽  
Ben E. Black ◽  
John M. Pascal
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Chain Elongation ◽  
Dna Breaks ◽  
Data Support ◽  
Damage Response ◽  
Hit And Run ◽  
Dna Break ◽  
Structural Insights ◽  
In Cells

AbstractPARP1 and PARP2 produce poly(ADP-ribose) in response to DNA breaks. HPF1 regulates PARP1/2 catalytic output, most notably permitting serine modification with ADP-ribose. However, PARP1 is substantially more abundant in cells than HPF1, challenging whether HPF1 can pervasively modulate PARP1. Here, we show biochemically that HPF1 efficiently regulates PARP1/2 catalytic output at sub-stoichiometric ratios matching their relative cellular abundances. HPF1 rapidly associates/dissociates from multiple PARP1 molecules, initiating serine modification before modification initiates on glutamate/aspartate, and accelerating initiation to be more comparable to elongation reactions forming poly(ADP-ribose). This “hit and run” mechanism ensures HPF1 contributions to PARP1/2 during initiation do not persist and interfere with PAR chain elongation. We provide structural insights into HPF1/PARP1 assembled on a DNA break, and assess HPF1 impact on PARP1 retention on DNA. Our data support the prevalence of serine-ADP-ribose modification in cells and the efficiency of serine-ADP-ribose modification required for an acute DNA damage response.

scholarly journals Overall Cdk activity modulates the DNA damage response in mammalian cells

2009 ◽  
Vol 187 (6) ◽  
pp. 773-780 ◽  
Author(s):  
Antonio Cerqueira ◽  
David Santamaría ◽  
Bárbara Martínez-Pastor ◽  
Miriam Cuadrado ◽  
Oscar Fernández-Capetillo ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Cyclin Dependent Kinase ◽  
Genome Maintenance ◽  
Cycle Progression ◽  
Damage Response ◽  
Dna Break ◽  
Specific Contribution

In response to DNA damage, cells activate a phosphorylation-based signaling cascade known as the DNA damage response (DDR). One of the main outcomes of DDR activation is inhibition of cyclin-dependent kinase (Cdk) activity to restrain cell cycle progression until lesions are healed. Recent studies have revealed a reverse connection by which Cdk activity modulates processing of DNA break ends and DDR activation. However, the specific contribution of individual Cdks to this process remains poorly understood. To address this issue, we have examined the DDR in murine cells carrying a defined set of Cdks. Our results reveal that genome maintenance programs of postreplicative cells, including DDR, are regulated by the overall level of Cdk activity and not by specific Cdks.

scholarly journals The Intra- and Extra-Telomeric Role of TRF2 in the DNA Damage Response

2021 ◽  
Vol 22 (18) ◽  
pp. 9900
Author(s):  
Siti A. M. Imran ◽  
Muhammad Dain Yazid ◽  
Wei Cui ◽  
Yogeswaran Lokanathan
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Response Factors ◽  
Telomere Repeat ◽  
Protection Mechanism ◽  
Dna Instability ◽  
Binding Factor ◽  
Damage Response ◽  
Dna Break

Telomere repeat binding factor 2 (TRF2) has a well-known function at the telomeres, which acts to protect the telomere end from being recognized as a DNA break or from unwanted recombination. This protection mechanism prevents DNA instability from mutation and subsequent severe diseases caused by the changes in DNA, such as cancer. Since TRF2 actively inhibits the DNA damage response factors from recognizing the telomere end as a DNA break, many more studies have also shown its interactions outside of the telomeres. However, very little has been discovered on the mechanisms involved in these interactions. This review aims to discuss the known function of TRF2 and its interaction with the DNA damage response (DDR) factors at both telomeric and non-telomeric regions. In this review, we will summarize recent progress and findings on the interactions between TRF2 and DDR factors at telomeres and outside of telomeres.

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

2019 ◽  
Vol 150 (5) ◽  
pp. 1022-1030 ◽  
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.

scholarly journals The Epstein-Barr Virus BMRF1 Protein Activates Transcription and Inhibits the DNA Damage Response by Binding NuRD

2019 ◽  
Vol 93 (22) ◽  
Author(s):  
Samuel G. Salamun ◽  
Justine Sitz ◽  
Carlos F. De La Cruz-Herrera ◽  
Jaime Yockteng-Melgar ◽  
Edyta Marcon ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nurd Complex ◽  
Dna Breaks ◽  
Nucleosome Remodeling ◽  
Barr Virus ◽  
Damage Response ◽  
Epstein Barr

ABSTRACT The BMRF1 protein of Epstein-Barr virus (EBV) has multiple roles in viral lytic infection, including serving as the DNA polymerase processivity factor, activating transcription from several EBV promoters and inhibiting the host DNA damage response to double-stranded DNA breaks (DSBs). Using affinity purification coupled to mass spectrometry, we identified the nucleosome remodeling and deacetylation (NuRD) complex as the top interactor of BMRF1. We further found that NuRD components localize with BMRF1 at viral replication compartments and that this interaction occurs through the BMRF1 C-terminal region previously shown to mediate transcriptional activation. We identified an RBBP4 binding motif within this region that can interact with both RBBP4 and MTA2 components of the NuRD complex and showed that point mutation of this motif abrogates NuRD binding as well as the ability of BMRF1 to activate transcription from the BDLF3 and BLLF1 EBV promoters. In addition to its role in transcriptional regulation, NuRD has been shown to contribute to DSB signaling in enabling recruitment of RNF168 ubiquitin ligase and subsequent ubiquitylation at the break. We showed that BMRF1 inhibited RNF168 recruitment and ubiquitylation at DSBs and that this inhibition was at least partly relieved by loss of the NuRD interaction. The results reveal a mechanism by which BMRF1 activates transcription and inhibits DSB signaling and a novel role for NuRD in transcriptional activation in EBV. IMPORTANCE The Epstein-Barr virus (EBV) BMRF1 protein is critical for EBV infection, playing key roles in viral genome replication, activation of EBV genes, and inhibition of host DNA damage responses (DDRs). Here we show that BMRF1 targets the cellular nucleosome remodeling and deacetylation (NuRD) complex, using a motif in the BMRF1 transcriptional activation sequence. Mutation of this motif disrupts the ability of BMRF1 to activate transcription and interfere with DDRs, showing the importance of the NuRD interaction for BMRF1 functions. BMRF1 was shown to act at the same step in the DDR as NuRD, suggesting that it interferes with NuRD function.

Differential effects of ambient diesel carcinogens on inflammation and DNA damage response in cells relevant for lung toxicity

2014 ◽  
Vol 229 ◽  
pp. S25
Author(s):  
Eleonora Longhin ◽  
Johan Øvrevik ◽  
Maurizio Gualtieri ◽  
Annike Totlandsdal ◽  
Steen Mollerup ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Lung Toxicity ◽  
Differential Effects ◽  
Damage Response ◽  
In Cells

DNA-damage response-umbrella study of the combination of ceralasertib and olaparib, or ceralasertib and durvalumab in advanced biliary tract cancer: A phase 2 trial-in-progress.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. TPS4166-TPS4166
Author(s):  
Jee Sun Yoon ◽  
Jin Won Kim ◽  
Ji-Won Kim ◽  
Tae-Yong Kim ◽  
Ah-Rong Nam ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Biliary Tract ◽  
Dna Damage Response ◽  
Biliary Tract Cancer ◽  
Phase 2 ◽  
Dna Breaks ◽  
Tumor Cell Death ◽  
Tract Cancer ◽  
Damage Response

TPS4166 Background: Ceralasertib (AZD6738) is a selective ATR inhibitor that causes stalled replication forks to collapse, leading to accumulation of double-strand DNA breaks, which is expected to have synergistic anti-tumor effects with immune checkpoint inhibitors (ICI) or PARP inhibitors. First, accumulation of DNA damage by ceralasertib induces tumor cell death, leads to the release of tumor-specific antigen, changing the tumor microenvironment to promote antigen presentation and enhances the anti-tumor effect of ICI. Second, by simultaneously inhibiting two DNA-damage response (DDR) pathways downstream of PARP and ATR, cancer cells are unable to repair damaged DNA, leading to cell death. Ceralasertib has demonstrated promising anti-tumor activity and manageable toxicity in combination with durvalumab or olaparib in solid tumors in a phase 1 study (NCT02264678). In preclinical studies, ceralasertib has shown potent anti-tumor effects in biliary tract cancer (BTC) as a monotherapy and in combination with chemotherapy (Nam, et al, 2019). Methods: This is an open-label, phase 2 umbrella study assessing the efficacy of ceralasertib in combination with durvalumab or olaparib in patients with advanced BTC. Eligible patients have histologically confirmed BTC (including intrahepatic or extrahepatic cholangiocarcinoma, gallbladder cancer, or ampullary cancer), have failed at least one chemotherapy and have ECOG performance status of 0-1. Patients who have received prior ICI, ATR or PARP inhibitor are excluded. Each cycle consists of 4 weeks. In ceralasertib /durvalumab cohort, 37 patients will receive durvalumab 1.5g on day 1 and ceralasertib 240mg twice daily on days 15-28. In ceralasertib /olaparib cohort, 37 patients receive ceralasertib 160mg once daily on days 1-7 and olaparib 300mg twice daily on days 1-28. The primary endpoint is disease control rate, with key secondary endpoints including overall response rate, progression-free survival, overall survival, and safety. Tissue and blood samples are being collected for translational biomarker studies. Clinical trial information: NCT04298021.

scholarly journals ATM Activation and Signaling under Hypoxic Conditions

2008 ◽  
Vol 29 (2) ◽  
pp. 526-537 ◽  
Author(s):  
Zuzana Bencokova ◽  
Muriel R. Kaufmann ◽  
Isabel M. Pires ◽  
Philip S. Lecane ◽  
Amato J. Giaccia ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Hypoxia Inducible Factor ◽  
Dna Breaks ◽  
Focus Formation ◽  
Atm Kinase ◽  
Mrn Complex ◽  
Hypoxic Conditions ◽  
Damage Response ◽  
Dependent Cell

ABSTRACT The ATM kinase has previously been shown to respond to the DNA damage induced by reoxygenation following hypoxia by initiating a Chk 2-dependent cell cycle arrest in the G2 phase. Here we show that ATM is both phosphorylated and active during exposure to hypoxia in the absence of DNA damage, detectable by either comet assay or 53BP1 focus formation. Hypoxia-induced activation of ATM correlates with oxygen concentrations low enough to cause a replication arrest and is entirely independent of hypoxia-inducible factor 1 status. In contrast to damage-activated ATM, hypoxia-activated ATM does not form nuclear foci but is instead diffuse throughout the nucleus. The hypoxia-induced activity of both ATM and the related kinase ATR is independent of NBS1 and MRE11, indicating that the MRN complex does not mediate the DNA damage response to hypoxia. However, the mediator MDC1 is required for efficient activation of Kap1 by hypoxia-induced ATM, indicating that similarly to the DNA damage response, there is a requirement for MDC1 to amplify the ATM response to hypoxia. However, under hypoxic conditions, MDC1 does not recruit BRCA1/53BP1 or RNF8 activity. Our findings clearly demonstrate that there are alternate mechanisms for activating ATM that are both stress-specific and independent of the presence of DNA breaks.

scholarly journals Acetylation of Histone H2AX at Lys 5 by the TIP60 Histone Acetyltransferase Complex Is Essential for the Dynamic Binding of NBS1 to Damaged Chromatin

2015 ◽  
Vol 35 (24) ◽  
pp. 4147-4157 ◽  
Author(s):  
Masae Ikura ◽  
Kanji Furuya ◽  
Shun Matsuda ◽  
Ryo Matsuda ◽  
Hiroki Shima ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Histone Acetyltransferase ◽  
Dynamic Binding ◽  
Histone H2ax ◽  
Damage Response ◽  
In Cells

The association and dissociation of DNA damage response (DDR) factors with damaged chromatin occurs dynamically, which is crucial for the activation of DDR signaling in a spatiotemporal manner. We previously showed that the TIP60 histone acetyltransferase complex acetylates histone H2AX, to facilitate H2AX exchange at sites of DNA damage. However, it remained unclear how the acetylation of histone H2AX by TIP60 is related to the DDR signaling. We found that the acetylation but not the phosphorylation of H2AX is essential for the turnover of NBS1 on damaged chromatin. The loss of H2AX acetylation at Lys 5 by TIP60 in cells disturbed the accumulation of NBS1 at sites of DNA damage. Although the phosphorylation of H2AX is also reportedly required for the retention of NBS1 at damage sites, our data indicated that the acetylation-dependent NBS1 turnover by TIP60 on damaged chromatin restricts the dispersal of NBS1 foci from the sites of DNA damage. These findings indicate the importance of the acetylation-dependent dynamic binding of NBS1 to damaged chromatin, created by histone H2AX exchange, for the proper accumulation of NBS1 at DNA damage sites.

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