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 Analysis of DNA breaks, DNA damage response, and apoptosis produced by high NaCl

2008 ◽  
Vol 295 (6) ◽  
pp. F1678-F1688 ◽  
Author(s):  
Natalia I. Dmitrieva ◽  
Maurice B. Burg
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Hela Cells ◽  
Cell Types ◽  
Dna Breaks ◽  
Main Subject ◽  
Mrn Complex ◽  
Damage Response

We previously reported that, both in cell culture and in the renal inner medulla in vivo, elevating NaCl increased the number of DNA breaks, which persisted as long as NaCl remained high but were rapidly repaired when NaCl was lowered. Furthermore, those breaks did not induce the DNA repair protein γH2AX or cause activation of the MRN (Mre11, Rad50, Nbs1) complex. In contrast, others recently reported that high NaCl does induce γH2AX and MRN complex formation and concluded that these activities are associated with repair of the DNA (Sheen MR, Kim SW, Jung JY, Ahn JY, Rhee JG, Kwon HM, Woo SK. Am J Physiol Renal Physiol 291: F1014–F1020, 2006). The purpose of the present studies was to resolve the disparity. The important difference is that HeLa cells, which were the main subject of the later report, are much less tolerant of high NaCl than are the mIMCD3 cells, which were our main subject. mIMCD3 cells survive levels of NaCl that kill HeLa cells by apoptosis. Here we demonstrate that in both cell types raising NaCl to a level that the cells survive (higher for mIMCD3 than HeLa) increases DNA breaks without inducing γH2AX or activating the MRN complex and that the DNA breaks persist as long as NaCl remains elevated, but are rapidly repaired when it is lowered. Importantly, in both cell types, raising NaCl further to cause apoptosis activates these DNA damage response proteins and greatly fragments DNA, associated with cell death. We conclude that γH2AX induction and MRN activation in response to high NaCl are associated with apoptosis, not DNA repair.

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 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.

Heterochromatin and the DNA damage response: the need to relaxThis paper is one of a selection of papers in a Special Issue entitled 31st Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2011 ◽  
Vol 89 (1) ◽  
pp. 45-60 ◽  
Author(s):  
Kendra L. Cann ◽  
Graham Dellaire
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Chromatin Structure ◽  
Peer Review Process ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Atm Kinase ◽  
Strand Breaks ◽  
Damage Response ◽  
Chromosomal Mutations

Higher order chromatin structure has an impact on all nuclear functions, including the DNA damage response. Over the past several years, it has become increasingly clear that heterochromatin and euchromatin represent separate entities with respect to both damage sensitivity and repair. The chromatin compaction present in heterochromatin helps to protect this DNA from damage; however, when lesions do occur, the compaction restricts the ability of DNA damage response proteins to access the site, as evidenced by its ability to block the expansion of H2AX phosphorylation. As such, DNA damage in heterochromatin is refractory to repair, which requires the surrounding chromatin structure to be decondensed. In the case of DNA double-strand breaks, this relaxation is at least partially mediated by the ATM kinase phosphorylating and inhibiting the function of the transcriptional repressor KAP1. This review will focus on the functions of KAP1 and other proteins involved in the maintenance or restriction of heterochromatin, including HP1 and TIP60, in the DNA damage response. As heterochromatin is important for maintaining genomic stability, cells must maintain a delicate balance between allowing repair factors access to these regions and ensuring that these regions retain their organization to prevent increased DNA damage and chromosomal mutations.

scholarly journals Inhibition of the ATM/p53 Signal Transduction Pathway by Kaposi's Sarcoma-Associated Herpesvirus Interferon Regulatory Factor 1

2006 ◽  
Vol 80 (5) ◽  
pp. 2257-2266 ◽  
Author(s):  
Young C. Shin ◽  
Hiroyuki Nakamura ◽  
Xiaozhen Liang ◽  
Pinghui Feng ◽  
Heesoon Chang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Signal Transduction Pathway ◽  
Interferon Regulatory Factor ◽  
Transduction Pathway ◽  
Regulatory Factor ◽  
Atm Kinase ◽  
Interferon Regulatory Factor 1 ◽  
Damage Response ◽  
Infected Cells

ABSTRACT Infected cells recognize viral replication as a DNA damage stress and elicit the ataxia telangiectasia-mutated (ATM)/p53-mediated DNA damage response signal transduction pathway as part of the host surveillance mechanisms, which ultimately induces the irreversible cell cycle arrest and apoptosis. Viruses have evolved a variety of mechanisms to counteract this host intracellular innate immunity. Kaposi's sarcoma-associated herpesvirus (KSHV) viral interferon regulatory factor 1 (vIRF1) interacts with the cellular p53 tumor suppressor through its central DNA binding domain, and this interaction inhibits transcriptional activation of p53. Here, we further demonstrate that KSHV vIRF1 downregulates the total p53 protein level by facilitating its proteasome-mediated degradation. Detailed biochemical study showed that vIRF1 interacted with cellular ATM kinase through its carboxyl-terminal transactivation domain and that this interaction blocked the activation of ATM kinase activity induced by DNA damage stress. As a consequence, vIRF1 expression greatly reduced the level of serine 15 phosphorylation of p53, resulting in an increase of p53 ubiquitination and thereby a decrease of its protein stability. These results indicate that KSHV vIRF1 comprehensively compromises an ATM/p53-mediated DNA damage response checkpoint by targeting both upstream ATM kinase and downstream p53 tumor suppressor, which might circumvent host growth surveillance and facilitate viral replication in infected cells.

scholarly journals The dual role of the RETINOBLASTOMA-RELATED protein in the DNA damage response is spatio-temporally coordinated by the interaction with LXCXE-containing proteins.

2021 ◽  
Author(s):  
Jorge Zamora-Zaragoza ◽  
Katinka Klap ◽  
Renze Heidstra ◽  
Wenkun Zhou ◽  
Ben Scheres
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Dna Repair ◽  
Cell Division ◽  
Dna Damage Response ◽  
Growth Arrest ◽  
Focus Formation ◽  
Damage Response ◽  
Nuclear Foci ◽  
Lxcxe Motif

Living organisms face threats to genome integrity caused by environmental challenges or metabolic errors in proliferating cells. To avoid the spread of mutations, cell division is temporarily arrested while repair mechanisms deal with DNA lesions. Afterwards, cells either resume division or respond to unsuccessful repair by withdrawing from the cell cycle and undergoing cell death. How the success rate of DNA repair connects to the execution of cell death remains incompletely known, particularly in plants. Here we provide evidence that the Arabidopsis thaliana RETINOBLASTOMA-RELATED1 (RBR) protein, shown to play structural and transcriptional functions in the DNA damage response (DDR), coordinates these processes in time by successive interactions through its B-pocket sub-domain. Upon DNA damage induction, RBR forms nuclear foci; but the N849F substitution in the B-pocket, which specifically disrupts binding to LXCXE motif-containing proteins, abolishes RBR focus formation and leads to growth arrest. After RBR focus formation, the stress-responsive gene NAC044 arrests cell division. As RBR is released from nuclear foci, it can be bound by the conserved LXCXE motif in NAC044. RBR-mediated cell survival is inhibited by the interaction with NAC044. Disruption of NAC044-RBR interaction impairs the cell death response but is less important for NAC044 mediated growth arrest. Noteworthy, unlike many RBR interactors, NAC044 binds to RBR independent of RBR phosphorylation. Our findings suggest that the availability of the RBR B-pocket to interact with LXCXE-containing proteins couples the structural DNA repair functions and the transcriptional functions of RBR in the cell death program.

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