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

Blood ◽  
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.

scholarly journals Identification of S-phase DNA damage-response targets in fission yeast reveals conservation of damage-response networks

2016 ◽  
Vol 113 (26) ◽  
pp. E3676-E3685 ◽  
Author(s):  
Nicholas A. Willis ◽  
Chunshui Zhou ◽  
Andrew E. H. Elia ◽  
Johanne M. Murray ◽  
Antony M. Carr ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Dna Replication ◽  
Fission Yeast ◽  
Dna Damage Response ◽  
Cellular Response ◽  
Genome Stability ◽  
Biological Significance ◽  
S Phase ◽  
Damage Response

The cellular response to DNA damage during S-phase regulates a complicated network of processes, including cell-cycle progression, gene expression, DNA replication kinetics, and DNA repair. In fission yeast, this S-phase DNA damage response (DDR) is coordinated by two protein kinases: Rad3, the ortholog of mammalian ATR, and Cds1, the ortholog of mammalian Chk2. Although several critical downstream targets of Rad3 and Cds1 have been identified, most of their presumed targets are unknown, including the targets responsible for regulating replication kinetics and coordinating replication and repair. To characterize targets of the S-phase DDR, we identified proteins phosphorylated in response to methyl methanesulfonate (MMS)-induced S-phase DNA damage in wild-type, rad3∆, and cds1∆ cells by proteome-wide mass spectrometry. We found a broad range of S-phase–specific DDR targets involved in gene expression, stress response, regulation of mitosis and cytokinesis, and DNA replication and repair. These targets are highly enriched for proteins required for viability in response to MMS, indicating their biological significance. Furthermore, the regulation of these proteins is similar in fission and budding yeast, across 300 My of evolution, demonstrating a deep conservation of S-phase DDR targets and suggesting that these targets may be critical for maintaining genome stability in response to S-phase DNA damage across eukaryotes.

scholarly journals Replication fork dynamics and the DNA damage response

2012 ◽  
Vol 443 (1) ◽  
pp. 13-26 ◽  
Author(s):  
Rebecca M. Jones ◽  
Eva Petermann
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Response ◽  
Replication Fork ◽  
Molecular Mechanisms ◽  
S Phase ◽  
Replication Initiation ◽  
Developmental Defects ◽  
Replication Fork Progression ◽  
Damage Response

Prevention and repair of DNA damage is essential for maintenance of genomic stability and cell survival. DNA replication during S-phase can be a source of DNA damage if endogenous or exogenous stresses impair the progression of replication forks. It has become increasingly clear that DNA-damage-response pathways do not only respond to the presence of damaged DNA, but also modulate DNA replication dynamics to prevent DNA damage formation during S-phase. Such observations may help explain the developmental defects or cancer predisposition caused by mutations in DNA-damage-response genes. The present review focuses on molecular mechanisms by which DNA-damage-response pathways control and promote replication dynamics in vertebrate cells. In particular, DNA damage pathways contribute to proper replication by regulating replication initiation, stabilizing transiently stalled forks, promoting replication restart and facilitating fork movement on difficult-to-replicate templates. If replication fork progression fails to be rescued, this may lead to DNA damage and genomic instability via nuclease processing of aberrant fork structures or incomplete sister chromatid separation during mitosis.

scholarly journals ATR-dependent phosphorylation of FANCA on serine 1449 after DNA damage is important for FA pathway function

Blood ◽  
2009 ◽  
Vol 113 (10) ◽  
pp. 2181-2190 ◽  
Author(s):  
Natalie B. Collins ◽  
James B. Wilson ◽  
Thomas Bush ◽  
Andrei Thomashevski ◽  
Kate J. Roberts ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Fanconi Anemia ◽  
Posttranslational Modifications ◽  
S Phase ◽  
Damage Response ◽  
Pathway Function

Abstract Previous work has shown several proteins defective in Fanconi anemia (FA) are phosphorylated in a functionally critical manner. FANCA is phosphorylated after DNA damage and localized to chromatin, but the site and significance of this phosphorylation are unknown. Mass spectrometry of FANCA revealed one phosphopeptide, phosphorylated on serine 1449. Serine 1449 phosphorylation was induced after DNA damage but not during S phase, in contrast to other posttranslational modifications of FA proteins. Furthermore, the S1449A mutant failed to completely correct a variety of FA-associated phenotypes. The DNA damage response is coordinated by phosphorylation events initiated by apical kinases ATM (ataxia telangectasia mutated) and ATR (ATM and Rad3-related), and ATR is essential for proper FA pathway function. Serine 1449 is in a consensus ATM/ATR site, phosphorylation in vivo is dependent on ATR, and ATR phosphorylated FANCA on serine 1449 in vitro. Phosphorylation of FANCA on serine 1449 is a DNA damage–specific event that is downstream of ATR and is functionally important in the FA pathway.

scholarly journals Lack of CCAAT Enhancer Binding Protein Beta (C/EBPβ) in Uterine Epithelial Cells Impairs Estrogen-Induced DNA Replication, Induces DNA Damage Response Pathways, and Promotes Apoptosis

2010 ◽  
Vol 30 (7) ◽  
pp. 1607-1619 ◽  
Author(s):  
Cyril Ramathal ◽  
Indrani C. Bagchi ◽  
Milan K. Bagchi
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Epithelial Cells ◽  
Cell Cycle Arrest ◽  
Dna Damage Response ◽  
S Phase ◽  
Uterine Epithelial Cells ◽  
Cycle Arrest ◽  
Damage Response

ABSTRACT Female mice lacking the transcription factor C/EBPβ are infertile and display markedly reduced estrogen (E)-induced proliferation of the uterine epithelial lining during the reproductive cycle. The present study showed that E-stimulated luminal epithelial cells of a C/EBPβ-null uterus are able to proceed through the G1 phase of the cell cycle before getting arrested in the S phase. This cell cycle arrest was accompanied by markedly reduced levels of expression of E2F3, an E2F family member, and a lack of nuclear localization of cyclin E, a critical regulator of cdk2. An increased nuclear accumulation of p27, an inhibitor of the cyclin E-cdk2 complex, was also observed for the mutant epithelium. Gene expression profiling of C/EBPβ-null uterine epithelial cells revealed that the blockade of E-induced DNA replication triggers the activation of several well-known components of the DNA damage response pathway, such as ATM, ATR, histone H2AX, checkpoint kinase 1, and tumor suppressor p53. The activation of p53 by ATM/ATR kinase led to increased levels of expression of p21, an inhibitor of G1-S-phase progression, which helps maintain cell cycle arrest. Additionally, p53-dependent mechanisms contributed to an increased apoptosis of replication-defective cells in the C/EBPβ-null epithelium. C/EBPβ, therefore, is an essential mediator of E-induced growth and survival of uterine epithelial cells of cycling mice.

Differential Phosphorylation of FANCA and FANCG Determines Response of Fanconi Anemia Core Complex to DNA Damage and S Phase.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 726-726
Author(s):  
Jun Mi ◽  
Andrei Tomashevski ◽  
Gary M. Kupfer
Keyword(s):  
Dna Damage ◽  
Fanconi Anemia ◽  
Bone Marrow Failure ◽  
Cellular Responses ◽  
S Phase ◽  
Congenital Defects ◽  
Core Complex ◽  
Downstream Target ◽  
Chk1 Kinase ◽  
Differential Phosphorylation

Abstract Fanconi anemia (FA) is a genetic disease marked by bone marrow failure, congenital defects, and cancer. In spite of the identification of at least 8 genes, the biochemistry of the disease and its normal pathway in the cell remains elusive. The FA core complex is composed of at least 5 proteins, 2 of which, FANCA and FANCG, we have shown to be phosphorylated. In these studies, we show that both FANCA and FANCG are phosphorylated in response to DNA damage. In the case of FANCG, we have mapped the site of this phosphorylation to serine 7, using a phosphoserine 7 FANCG antiserum. Because of the link of FA function and the FA core complex-dependent monoubiquitination that occurs both as a result of DNA damage as well as at S phase, we also examined if phosphorylation occurred at S phase as well. While FANCG serine 7 phosphorylation occurs both at S phase and after DNA damage (similar to FANCD2 monoubiquitination), FANCA phosphorylation occurs only after DNA damage. Recent data have implicated the kinase ATR as important in the pathway. In order to assess whether a downstream target of ATR is differentially phosphorylated in FA cells, we tested the phosphorylation status of chk1 in FA-A mutant and corrected cells. Chk1 kinase is phosphorylated at serine 318 in response to DNA damage only in corrected cells but not mutant FA cells, while signaling through chk2 kinase is unaffected. These data suggest the importance of phosphorylation in the FA pathway in the regulation of both cellular responses to DNA damage as well as engagement of the cell cycle.

Identification and Partial Characterization of a Novel Partner Protein for Fanconi Anemia Protein FANCM

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3104-3104
Author(s):  
Stacie Stone ◽  
Alexandra Sobeck ◽  
Igor Landais ◽  
Weidong Wang ◽  
Maureen Hoatlin
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Protein Complexes ◽  
S Phase ◽  
Chromatin Binding ◽  
Core Complex ◽  
Dna Structures ◽  
Partner Protein ◽  
Damage Response ◽  
Egg Extracts

Abstract Fanconi anemia (FA) is an inherited hematological disorder characterized by bone marrow failure, birth defects, and cancer susceptibility, typically leading to squamous cell carcinomas and acute myelogenous leukemia. Twelve FA genes have been described, eight of which function together in a multiprotein, upstream “FA core complex” to mediate the S-phase and DNA damage-induced monoubiquitylation of two downstream proteins, FANCD2 and FANCI. Despite this knowledge the precise function of the FA proteins is not well understood because they function as part of a network of proteins that have not been completely defined. Recently we developed a new animal model for FA research using extracts from the eggs of Xenopus laevis. Xenopus extracts are cell cycle synchronized and contain nuclear proteins that are stockpiled for DNA replication. We showed that FA gene orthologs (xFA), like their human counterparts, form complexes that are required for the monoubiquitylation of xFANCD2 in response to DNA damage. Xenopus laevis extracts are thus a powerful system to analyze the endogenous state of xFA protein complexes and their components in an S phase, replication-competent context. The objective of this study was to isolate protein complexes containing the xFA core complex protein, xFANCM and xFANCM-interacting proteins. Using a co-immunoprecipitation approach followed by mass spectrometry, we identified a novel protein-binding partner of xFANCM (termed xMIP-1, for xFANCM Interacting Protein 1). The interaction was confirmed by reciprocal coimmunoprecipitation in both Xenopus extracts and human cells. Surprisingly, co-fractionation demonstrated that xFANCM was present in two protein complexes during S phase; one containing FA core complex members (<900 kDa) as expected, and another previously undescribed complex (>900 kDa) containing xMIP-1. Because xMIP-1 is a partner protein of xFANCM we wanted to determine if xMIP-1, like xFANCM, was required for the monoubiquitylation of xFANCD2. This was done using a DNA stimulation assay, where upon immunodepletion of xMIP-1 from egg extracts, we were able to observe the monoubiquitylation of xFANCD2 in response to DNA structures as a size shift via immunoblot. The absence of xMIP-1 had no detectable effect on the monoubiquitylation of xFANCD2 suggesting that xMIP-1, unlike xFANCM, was not required for xFANCD2 monoubiquitylation. To explore a functional link between xFANCM and xMIP-1 we used egg extracts to show that xMIP-1, like xFANCM, was recruited to replicating chromatin and exhibited a size shift during the replication process. Furthermore immunodepletion of xFANCM from egg extracts reduced recruitment of xMIP-1 to replicating chromatin, suggesting that xMIP-1 chromatin binding was dependent on xFANCM. In contrast, xMIP-1 recruitment to replicating chromatin was not affected by the immunodepletion of other FA core complex proteins tested, suggesting that xMIP-1 chromatin binding is independent of the FA core complex. To further characterize the observed DNA binding activity of xMIP-1 we used the DNA stimulation assay and several defined DNA structures. Surprisingly xMIP-1 showed a double-stranded DNA stimulated mobility shift similar to those reported previously for xFANCD2 (Sobeck et al., 2007) and xMRE11 (Costanzo et al., 2001) suggesting xMIP-1 may play a role in the DNA damage response. Our data suggests xFANCM is a member of an S phase complex that has not been previously described with a “non-FA” partner protein that may function with xFANCM during the DNA damage response to maintain genomic stability.

scholarly journals Histone Ubiquitination by the DNA Damage Response Is Required for Efficient DNA Replication in Unperturbed S Phase

2018 ◽  
Vol 71 (6) ◽  
pp. 897-910.e8 ◽  
Author(s):  
Jonas Andreas Schmid ◽  
Matteo Berti ◽  
Franziska Walser ◽  
Maria Chiara Raso ◽  
Fabian Schmid ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Response ◽  
S Phase ◽  
Damage Response

HSC Exit From Dormancy Provokes De Novo DNA Damage, Leading To Bone Marrow Failure If Unresolved By The Fanconi Anemia Pathway

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 799-799
Author(s):  
Dagmar Walter ◽  
Amelie Lier ◽  
Anja Geiselhart ◽  
Sina Huntscha ◽  
David Brocks ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Dna Damage ◽  
Aplastic Anemia ◽  
Dna Damage Response ◽  
Fanconi Anemia ◽  
De Novo ◽  
Bone Marrow Failure ◽  
Damage Response ◽  
Fold Induction

Abstract Long-term quiescence has been proposed to preserve the genomic stability of hematopoietic stem cells (HSCs) during aging. The current models of HSC aging are limited in their ability to observe both DNA damage in vivo and the consequences of this damage upon hematopoiesis. Fanconi Anemia (FA) is a hereditary multisystem disorder, characterized by defective DNA damage response and progressive bone marrow failure in most patients. However, the existing genetic models of FA do not develop aplastic anemia, suggesting that cell-extrinsic factors may play a causal role. We sought to identify whether physiologic mediators of HSC activation could be used as agonists to provoke DNA damage and HSC attrition in vivo. Mice were treated with a range of agonists that promote the in vivo exit of HSC from a dormant state into active cycling (polyI:polyC; Interferon-α; G-CSF; TPO; and serial bleeding). Highly purified HSC demonstrated a rapid 3-5-fold induction of DNA damage after treatment with all agonists (p<0.01), as assessed by both enumerating γ-H2AX foci and by alkaline comet assay. Mechanistically, stress-induced exit from quiescence correlated with increased mitochondrial metabolism in HSC, as evaluated by elevated mitochondrial membrane potential (2-fold increased, p<0.01) and superoxide levels (1.5-fold increased, p<0.05). Critically, we could directly implicate these reactive oxygen species in DNA damage as we observed a 1.4-fold increase in 8-Oxo-dG lesions in HSC that had been activated into cycle in vivo(p<0.05). At 48 h post-treatment, γ-H2AX levels began to decrease and this repair was concomitant with an induction of the FA signaling pathway in HSC, as demonstrated by both increased levels of FA gene expression and elevated FANCD2 foci (4-fold induction, p<0.01). Treatment of Fanca-/- mice with polyI:polyC led to a HSC proliferative response comparable to wild type (WT) mice but resulted in a 2-fold higher level of activation-induced DNA damage (p<0.05), demonstrating that this repair pathway is involved in resolving activation-induced DNA damage. Four rounds of serial in vivo activation led to a permanent depletion of the most primitive label-retaining Fanca-/- HSC and this correlated with a 4-fold depletion of functional HSC (p<0.01) as defined by competitive repopulation assays. Subsequent rounds of HSC activation with polyI:polyC resulted in the onset of a severe aplastic anemia (SAA) in 33% of treated Fanca-/- mice but not in any of the WT controls. SSA was characterized by a dramatic reduction in bone marrow (BM) cellularity, profound thrombocytopenia (21-246x106 platelets/ml), leukocytopenia (0.4-0.5x106 WBC/ml), neutropenia (0.03-0.1x106/ml) and anemia (1.5-2.3 g/dL Hb). Examination of BM HSC/progenitors demonstrated nearly complete loss of HSC, MPP, CMP and CLP (depletion of ≥33x, 8x, 4x and 12x respectively compared to PBS-treated Fanca-/-controls). Taken together, these data demonstrates that enforced exit from dormancy in vivo leads to de novo DNA damage in HSC, which is repaired by activation of a FA-dependent DNA damage response. Furthermore, the highly penetrant bone marrow failure observed in Fanconi anemia patients can be recapitulated by the serial application of a physiologic HSC activating signal to Fanca-/- mice. This suggests that the BM failure in FA may be caused by an aberrant response to HSC activation, most likely during exposure to infection or other physiologic stressors. These data provides a novel link between pro-inflammatory cytokines, DNA damage and HSC dysfunction and may have important clinical implications relevant to both prevention of BM failure in FA and in the study of age-related hematopoietic defects in non-FA patients. Moreover, these data provide the first evidence that FA knockout mouse models accurately recapitulate and provide novel insights into the etiology of BM failure in patients with FA. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Adenovirus E1B 55-Kilodalton Protein Targets SMARCAL1 for Degradation during Infection and Modulates Cellular DNA Replication

2019 ◽  
Vol 93 (13) ◽  
Author(s):  
Reshma Nazeer ◽  
Fadi S. I. Qashqari ◽  
Abeer S. Albalawi ◽  
Ann Liza Piberger ◽  
Maria Teresa Tilotta ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Viral Replication ◽  
Signaling Pathways ◽  
Dna Damage Response ◽  
Replication Fork ◽  
Dependent Manner ◽  
Damage Response ◽  
Adenovirus E1b ◽  
Cellular Dna

ABSTRACT Here, we show that the cellular DNA replication protein and ATR substrate SMARCAL1 is recruited to viral replication centers early during adenovirus infection and is then targeted in an E1B-55K/E4orf6- and cullin RING ligase-dependent manner for proteasomal degradation. In this regard, we have determined that SMARCAL1 is phosphorylated at S123, S129, and S173 early during infection in an ATR- and CDK-dependent manner, and that pharmacological inhibition of ATR and CDK activities attenuates SMARCAL1 degradation. SMARCAL1 recruitment to viral replication centers was shown to be largely dependent upon SMARCAL1 association with the RPA complex, while Ad-induced SMARCAL1 phosphorylation also contributed to SMARCAL1 recruitment to viral replication centers, albeit to a limited extent. SMARCAL1 was found associated with E1B-55K in adenovirus E1-transformed cells. Consistent with its ability to target SMARCAL1, we determined that E1B-55K modulates cellular DNA replication. As such, E1B-55K expression initially enhances cellular DNA replication fork speed but ultimately leads to increased replication fork stalling and the attenuation of cellular DNA replication. Therefore, we propose that adenovirus targets SMARCAL1 for degradation during infection to inhibit cellular DNA replication and promote viral replication. IMPORTANCE Viruses have evolved to inhibit cellular DNA damage response pathways that possess antiviral activities and utilize DNA damage response pathways that possess proviral activities. Adenovirus has evolved, primarily, to inhibit DNA damage response pathways by engaging with the ubiquitin-proteasome system and promoting the degradation of key cellular proteins. Adenovirus differentially regulates ATR DNA damage response signaling pathways during infection. The cellular adenovirus E1B-55K binding protein E1B-AP5 participates in ATR signaling pathways activated during infection, while adenovirus 12 E4orf6 negates Chk1 activation by promoting the proteasome-dependent degradation of the ATR activator TOPBP1. The studies detailed here indicate that adenovirus utilizes ATR kinase and CDKs during infection to promote the degradation of SMARCAL1 to attenuate normal cellular DNA replication. These studies further our understanding of the relationship between adenovirus and DNA damage and cell cycle signaling pathways during infection and establish new roles for E1B-55K in the modulation of cellular DNA replication.

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