The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Vilhelm A Bohr - One of the best experts on this subject based on the ideXlab platform.

  • current and emerging roles of Cockayne Syndrome group b csb protein
    Nucleic Acids Research, 2021
    Co-Authors: Vinod Tiwari, Mustafa Nazir Okur, Beverly A Baptiste, Vilhelm A Bohr
    Abstract:

    Cockayne Syndrome (CS) is a segmental premature aging Syndrome caused primarily by defects in the CSA or CSB genes. In addition to premature aging, CS patients typically exhibit microcephaly, progressive mental and sensorial retardation and cutaneous photosensitivity. Defects in the CSB gene were initially thought to primarily impair transcription-coupled nucleotide excision repair (TC-NER), predicting a relatively consistent phenotype among CS patients. In contrast, the phenotypes of CS patients are pleiotropic and variable. The latter is consistent with recent work that implicates CSB in multiple cellular systems and pathways, including DNA base excision repair, interstrand cross-link repair, transcription, chromatin remodeling, RNAPII processing, nucleolin regulation, rDNA transcription, redox homeostasis, and mitochondrial function. The discovery of additional functions for CSB could potentially explain the many clinical phenotypes of CSB patients. This review focuses on the diverse roles played by CSB in cellular pathways that enhance genome stability, providing insight into the molecular features of this complex premature aging disease.

  • Cockayne Syndrome proteins csa and csb maintain mitochondrial homeostasis through nad signaling
    Aging Cell, 2020
    Co-Authors: Mustafa Nazir Okur, Deborah L Croteau, Vilhelm A Bohr, Evandro Fei Fang, Elayne M Fivenson, Vinod Tiwari
    Abstract:

    Cockayne Syndrome (CS) is a rare premature aging disease, most commonly caused by mutations of the genes encoding the CSA or CSB proteins. CS patients display cachectic dwarfism and severe neurological manifestations and have an average life expectancy of 12 years. The CS proteins are involved in transcription and DNA repair, with the latter including transcription-coupled nucleotide excision repair (TC-NER). However, there is also evidence for mitochondrial dysfunction in CS, which likely contributes to the severe premature aging phenotype of this disease. While damaged mitochondria and impaired mitophagy were characterized in mice with CSB deficiency, such changes in the CS nematode model and CS patients are not fully known. Our cross-species transcriptomic analysis in CS postmortem brain tissue, CS mouse, and nematode models shows that mitochondrial dysfunction is indeed a common feature in CS. Restoration of mitochondrial dysfunction through NAD+ supplementation significantly improved lifespan and healthspan in the CS nematodes, highlighting mitochondrial dysfunction as a major driver of the aging features of CS. In cerebellar samples from CS patients, we found molecular signatures of dysfunctional mitochondrial dynamics and impaired mitophagy/autophagy. In primary cells depleted for CSA or CSB, this dysfunction can be corrected with supplementation of NAD+ precursors. Our study provides support for the interconnection between major causative aging theories, DNA damage accumulation, mitochondrial dysfunction, and compromised mitophagy/autophagy. Together, these three agents contribute to an accelerated aging program that can be averted by cellular NAD+ restoration.

  • Cockayne Syndrome group a and b proteins function in rrna transcription through nucleolin regulation
    Nucleic Acids Research, 2020
    Co-Authors: Mustafa N. Okur, Tyler G Demarest, Deborah L Croteau, Vilhelm A Bohr, Jong Hyuk Lee, Wasif Osmani, Risako Kimura
    Abstract:

    Cockayne Syndrome (CS) is a rare neurodegenerative disease characterized by short stature, accelerated aging and short lifespan. Mutations in two human genes, ERCC8/CSA and ERCC6/CSB, are causative for CS and their protein products, CSA and CSB, while structurally unrelated, play roles in DNA repair and other aspects of DNA metabolism in human cells. Many clinical and molecular features of CS remain poorly understood, and it was observed that CSA and CSB regulate transcription of ribosomal DNA (rDNA) genes and ribosome biogenesis. Here, we investigate the dysregulation of rRNA synthesis in CS. We report that Nucleolin (Ncl), a nucleolar protein that regulates rRNA synthesis and ribosome biogenesis, interacts with CSA and CSB. In addition, CSA induces ubiquitination of Ncl, enhances binding of CSB to Ncl, and CSA and CSB both stimulate the binding of Ncl to rDNA and subsequent rRNA synthesis. CSB and CSA also increase RNA Polymerase I loading to the coding region of the rDNA and this is Ncl dependent. These findings suggest that CSA and CSB are positive regulators of rRNA synthesis via Ncl regulation. Most CS patients carry mutations in CSA and CSB and present with similar clinical features, thus our findings provide novel insights into disease mechanism.

  • Cockayne Syndrome proteins csa and csb maintain mitochondrial homeostasis through nad signaling
    bioRxiv, 2020
    Co-Authors: Mustafa Nazir Okur, Deborah L Croteau, Vilhelm A Bohr, Evandro Fei Fang, Elayne M Fivenson, Vinod Tiwari
    Abstract:

    Background: Cockayne Syndrome (CS) is a rare premature aging disease, most commonly caused by mutations of the genes encoding the CSA or CSB proteins. CS patients display cachectic dwarfism and severe neurological manifestations and have an average life expectancy of 12 years. The CS proteins are involved in transcription and DNA repair, with the latter including transcription-coupled nucleotide excision repair (TC-NER). However, there is also evidence for mitochondrial dysfunction in CS, which likely contributes to the severe premature aging phenotype of this disease. While damaged mitochondria and impaired mitophagy were characterized in mice with CSB deficiency, such changes in the CS nematodes and CS patients are not fully known. Results: Our cross-species transcriptomic analysis in CS postmortem brain tissue, CS mouse and nematode models show that mitochondrial dysfunction is indeed a common feature in CS. Restoration of mitochondrial dysfunction through NAD+ supplementation significantly improved lifespan and healthspan in the CS nematodes, highlighting mitochondrial dysfunction as a major driver of the aging features of CS. In cerebellar samples from CS patients, we found molecular signatures of dysfunctional mitochondrial dynamics and impaired mitophagy/autophagy. In primary cells depleted for CSA or CSB, this dysfunction can be corrected with NAD+ supplementation. Conclusions: Our study provides support for the interconnection between major causative aging theories, DNA damage accumulation, mitochondrial dysfunction, and compromised mitophagy/autophagy. Together these three agents contribute to an accelerated aging program that can be averted by NAD+ supplementation.

  • Cockayne Syndrome group b deficiency reduces h3k9me3 chromatin remodeler setdb1 and exacerbates cellular aging
    Nucleic Acids Research, 2019
    Co-Authors: Tyler G Demarest, Mansi Babbar, Mustafa Nazir Okur, Supriyo De, Deborah L Croteau, Vilhelm A Bohr
    Abstract:

    : Cockayne Syndrome is an accelerated aging disorder, caused by mutations in the CSA or CSB genes. In CSB-deficient cells, poly (ADP ribose) polymerase (PARP) is persistently activated by unrepaired DNA damage and consumes and depletes cellular nicotinamide adenine dinucleotide, which leads to mitochondrial dysfunction. Here, the distribution of poly (ADP ribose) (PAR) was determined in CSB-deficient cells using ADPr-ChAP (ADP ribose-chromatin affinity purification), and the results show striking enrichment of PAR at transcription start sites, depletion of heterochromatin and downregulation of H3K9me3-specific methyltransferases SUV39H1 and SETDB1. Induced-expression of SETDB1 in CSB-deficient cells downregulated PAR and normalized mitochondrial function. The results suggest that defects in CSB are strongly associated with loss of heterochromatin, downregulation of SETDB1, increased PAR in highly-transcribed regions, and mitochondrial dysfunction.

Jean-marc Egly - One of the best experts on this subject based on the ideXlab platform.

  • regulatory interplay of Cockayne Syndrome b atpase and stress response gene atf3 following genotoxic stress
    Proceedings of the National Academy of Sciences of the United States of America, 2013
    Co-Authors: Ulrik Kristensen, Tinna Stevnsner, Vilhelm A Bohr, Vincent Laugel, Alexey Epanchintsev, Marcalexander Rauschendorf, Frederic Coin, Jean-marc Egly
    Abstract:

    Cockayne Syndrome type B ATPase (CSB) belongs to the SwItch/Sucrose nonfermentable family. Its mutations are linked to Cockayne Syndrome phenotypes and classically are thought to be caused by defects in transcription-coupled repair, a subtype of DNA repair. Here we show that after UV-C irradiation, immediate early genes such as activating transcription factor 3 (ATF3) are overexpressed. Although the ATF3 target genes, including dihydrofolate reductase (DHFR), were unable to recover RNA synthesis in CSB-deficient cells, transcription was restored rapidly in normal cells. There the synthesis of DHFR mRNA restarts on the arrival of RNA polymerase II and CSB and the subsequent release of ATF3 from its cAMP response element/ATF target site. In CSB-deficient cells ATF3 remains bound to the promoter, thereby preventing the arrival of polymerase II and the restart of transcription. Silencing of ATF3, as well as stable introduction of wild-type CSB, restores RNA synthesis in UV-irradiated CSB cells, suggesting that, in addition to its role in DNA repair, CSB activity likely is involved in the reversal of inhibitory properties on a gene-promoter region. We present strong experimental data supporting our view that the transcriptional defects observed in UV-irradiated CSB cells are largely the result of a permanent transcriptional repression of a certain set of genes in addition to some defect in DNA repair.

  • Cockayne Syndrome group b csb protein at the crossroads of transcriptional networks
    Mechanisms of Ageing and Development, 2013
    Co-Authors: Renier Velezcruz, Jean-marc Egly
    Abstract:

    Cockayne Syndrome (CS) is a rare genetic disorder characterized by a variety of growth and developmental defects, photosensitivity, cachectic dwarfism, hearing loss, skeletal abnormalities, progressive neurological degeneration, and premature aging. CS arises due to mutations in the CSA and CSB genes. Both gene products are required for the transcription-coupled (TC) branch of the nucleotide excision repair (NER) pathway, however, the severe phenotype of CS patients is hard to reconcile with a sole defect in TC-NER. Studies using cells from patients and mouse models have shown that the CSB protein is involved in a variety of cellular pathways and plays a major role in the cellular response to stress. CSB has been shown to regulate processes such as the transcriptional recovery after DNA damage, the p53 transcriptional response, the response to hypoxia, the response to insulin-like growth factor-1 (IGF-1), transactivation of nuclear receptors, transcription of housekeeping genes and the transcription of rDNA. Some of these processes are also affected in combined XP/CS patients. These new advances in the function(s) of CSB shed light onto the etiology of the clinical features observed in CS patients and could potentially open therapeutic avenues for these patients in the future. Moreover, the study of CS could further our knowledge of the aging process.

  • a ubiquitin binding domain in Cockayne Syndrome b required for transcription coupled nucleotide excision repair
    Molecular Cell, 2010
    Co-Authors: Roy Anindya, Jean-marc Egly, Wim Vermeulen, Ulrik Kristensen, Pierreolivier Mari, Hanneke Kool, Giuseppina Gigliamari, Leon H F Mullenders, Maria Fousteri, Jesper Q Svejstrup
    Abstract:

    Transcription-coupled nucleotide excision repair (TC-NER) allows RNA polymerase II (RNAPII)-blocking lesions to be rapidly removed from the transcribed strand of active genes. Defective TCR in humans is associated with Cockayne Syndrome (CS), typically caused by defects in either CSA or CSB. Here, we show that CSB contains a ubiquitin-binding domain (UBD). Cells expressing UBD-less CSB (CSB(del)) have phenotypes similar to those of cells lacking CSB, but these can be suppressed by appending a heterologous UBD, so ubiquitin binding is essential for CSB function. Surprisingly, CSB(del) remains capable of assembling nucleotide excision repair factors and repair synthesis proteins around damage-stalled RNAPII, but such repair complexes fail to excise the lesion. Together, our results indicate an essential role for protein ubiquitylation and CSB's UBD in triggering damage incision during TC-NER and allow us to integrate the function of CSA and CSB in a model for the process.

  • Deletion of 5' sequences of the CSB gene provides insight into the pathophysiology of Cockayne Syndrome.
    European Journal of Human Genetics, 2008
    Co-Authors: Vincent Laugel, Cecile Dalloz, Anne Stary, Valerie Cormier-daire, Isabelle Desguerre, Michel Renouil, Alain Fourmaintraux, Renier Velez-cruz, Jean-marc Egly, Alain Sarasin
    Abstract:

    Cockayne Syndrome is an autosomal recessive neurodegenerative disorder characterized by a specific defect in the repair of UV-induced DNA lesions. Most cases of Cockayne Syndrome are caused by mutations in the CSB gene but the pathophysiological mechanisms are poorly understood. We report the clinical and molecular data of two severely affected Cockayne patients with undetectable CSB protein and mRNA. Both patients showed severe growth failure, microcephaly, mental retardation, congenital cataracts, retinal pigmentary degeneration, photosensitivity and died at the ages of 6 and 8 years. UV irradiation assays demonstrated that both patients had the classical DNA repair defect. Genomic DNA sequencing of the CSB gene showed a homozygous deletion involving non-coding exon 1 and upstream regulatory sequences, but none of the coding exons. Functional complementation using a wild-type CSB expression plasmid fully corrected the DNA repair defect in transfected fibroblasts. Horibata et al recently proposed that all type of CSB mutations result in a defect in UV damage repair that is responsible for the photosensitivity observed in the Syndrome, but that only truncated CSB polypeptides generated by nonsense mutations have some additional inhibitory functions in transcription or in oxidative damage repair, which are necessary to lead to the other features of the phenotype. Our patients do not fit the proposed paradigm and new hypotheses are required to account for the pathophysiology of Cockayne Syndrome, at the crossroads between DNA repair and transcription.

  • XPG stabilizes TFIIH, allowing transactivation of nuclear receptors: implications for Cockayne Syndrome in XP-G/CS patients.
    Molecular Cell, 2007
    Co-Authors: Shinsuke Ito, Isao Kuraoka, Frederic Coin, Pierre Chymkowitch, Emmanuel Compe, Arato Takedachi, Chie Ishigami, Jean-marc Egly
    Abstract:

    Mutations in the human XPG gene give rise to an inherited photosensitive disorder, xeroderma pigmentosum (XP) associated with Cockayne Syndrome (XP-G/CS). The clinical features of CS in XP-G/CS patients are difficult to explain on the basis of a defect in nucleotide excision repair (NER). We found that XPG forms a stable complex with TFIIH, which is active in transcription and NER. Mutations in XPG found in XP-G/CS patient cells that prevent the association with TFIIH also resulted in the dissociation of CAK and XPD from the core TFIIH. As a consequence, the phosphorylation and transactivation of nuclear receptors were disturbed in XP-G/CS as well as xpg(-/-) MEF cells and could be restored by expression of wild-type XPG. These results provide an insight into the role of XPG in the stabilization of TFIIH and the regulation of gene expression and provide an explanation of some of the clinical features of XP-G/CS.

Huaying Fan - One of the best experts on this subject based on the ideXlab platform.

  • mechanistic insights into the regulation of transcription and transcription coupled dna repair by Cockayne Syndrome protein b
    Nucleic Acids Research, 2018
    Co-Authors: Erica L Boetefuer, Robert J Lake, Huaying Fan
    Abstract:

    Cockayne Syndrome protein B (CSB) is a member of the SNF2/SWI2 ATPase family and is essential for transcription-coupled nucleotide excision DNA repair (TC-NER). CSB also plays critical roles in transcription regulation. CSB can hydrolyze ATP in a DNA-dependent manner, alter protein-DNA contacts and anneal DNA strands. How the different biochemical activities of CSB are utilized in these cellular processes have only begun to become clear in recent years. Mutations in the gene encoding CSB account for majority of the Cockayne Syndrome cases, which result in extreme sun sensitivity, premature aging features and/or abnormalities in neurology and development. Here, we summarize and integrate recent biochemical, structural, single-molecule and somatic cell genetic studies that have advanced our understanding of CSB. First, we review studies on the mechanisms that regulate the different biochemical activities of CSB. Next, we summarize how CSB is targeted to regulate transcription under different growth conditions. We then discuss recent advances in our understanding of how CSB regulates transcription mechanistically. Lastly, we summarize the various roles that CSB plays in the different steps of TC-NER, integrating the results of different studies and proposing a model as to how CSB facilitates TC-NER.

  • the sequence specific transcription factor c jun targets Cockayne Syndrome protein b to regulate transcription and chromatin structure
    PLOS Genetics, 2014
    Co-Authors: Robert J Lake, Erica L Boetefuer, Peifang Tsai, Jieun Jeong, Inchan Choi, Kyoungjae Won, Huaying Fan
    Abstract:

    Cockayne Syndrome is an inherited premature aging disease associated with numerous developmental and neurological defects, and mutations in the gene encoding the CSB protein account for the majority of Cockayne Syndrome cases. Accumulating evidence suggests that CSB functions in transcription regulation, in addition to its roles in DNA repair, and those defects in this transcriptional activity might contribute to the clinical features of Cockayne Syndrome. Transcription profiling studies have so far uncovered CSB-dependent effects on gene expression; however, the direct targets of CSB's transcriptional activity remain largely unknown. In this paper, we report the first comprehensive analysis of CSB genomic occupancy during replicative cell growth. We found that CSB occupancy sites display a high correlation to regions with epigenetic features of promoters and enhancers. Furthermore, we found that CSB occupancy is enriched at sites containing the TPA-response element. Consistent with this binding site preference, we show that CSB and the transcription factor c-Jun can be found in the same protein-DNA complex, suggesting that c-Jun can target CSB to specific genomic regions. In support of this notion, we observed decreased CSB occupancy of TPA-response elements when c-Jun levels were diminished. By modulating CSB abundance, we found that CSB can influence the expression of nearby genes and impact nucleosome positioning in the vicinity of its binding site. These results indicate that CSB can be targeted to specific genomic loci by sequence-specific transcription factors to regulate transcription and local chromatin structure. Additionally, comparison of CSB occupancy sites with the MSigDB Pathways database suggests that CSB might function in peroxisome proliferation, EGF receptor transactivation, G protein signaling and NF-κB activation, shedding new light on the possible causes and mechanisms of Cockayne Syndrome.

  • atp dependent chromatin remodeling by Cockayne Syndrome protein b and nap1 like histone chaperones is required for efficient transcription coupled dna repair
    PLOS Genetics, 2013
    Co-Authors: Iltaeg Cho, Robert J Lake, Peifang Tsai, Asjad Basheer, Huaying Fan
    Abstract:

    The Cockayne Syndrome complementation group B (CSB) protein is essential for transcription-coupled DNA repair, and mutations in CSB are associated with Cockayne Syndrome—a devastating disease with complex clinical features, including the appearance of premature aging, sun sensitivity, and numerous neurological and developmental defects. CSB belongs to the SWI2/SNF2 ATP–dependent chromatin remodeler family, but the extent to which CSB remodels chromatin and whether this activity is utilized in DNA repair is unknown. Here, we show that CSB repositions nucleosomes in an ATP–dependent manner in vitro and that this activity is greatly enhanced by the NAP1-like histone chaperones, which we identify as new CSB–binding partners. By mapping functional domains and analyzing CSB derivatives, we demonstrate that chromatin remodeling by the combined activities of CSB and the NAP1-like chaperones is required for efficient transcription-coupled DNA repair. Moreover, we show that chromatin remodeling and repair protein recruitment mediated by CSB are separable activities. The collaboration that we observed between CSB and the NAP1-like histone chaperones adds a new dimension to our understanding of the ways in which ATP–dependent chromatin remodelers and histone chaperones can regulate chromatin structure. Taken together, the results of this study offer new insights into the functions of chromatin remodeling by CSB in transcription-coupled DNA repair as well as the underlying mechanisms of Cockayne Syndrome.

  • reciprocally regulated chromatin association of Cockayne Syndrome protein b and p53 protein
    Journal of Biological Chemistry, 2011
    Co-Authors: Robert J Lake, Asjad Basheer, Huaying Fan
    Abstract:

    The Cockayne Syndrome complementation group B (CSB) protein is an ATP-dependent chromatin remodeler with an essential function in transcription-coupled DNA repair, and mutations in the CSB gene are associated with Cockayne Syndrome. The p53 tumor suppressor has been known to interact with CSB, and both proteins have been implicated in overlapping biological processes, such as DNA repair and aging. The significance of the interaction between CSB and p53 has remained unclear, however. Here, we show that the chromatin association of CSB and p53 is inversely related. Using in vitro binding and chromatin immunoprecipitation approaches, we demonstrate that CSB facilitates the sequence-independent association of p53 with chromatin when p53 concentrations are low and that this is achieved by the interaction of CSB with the C-terminal region of p53. Remarkably, p53 prevents CSB from binding to nucleosomes when p53 concentrations are elevated. Examining the enzymatic properties of CSB revealed that p53 excludes CSB from nucleosomes by occluding a nucleosome interaction surface on CSB. Together, our results suggest that the reciprocal regulation of chromatin access by CSB and p53 could be part of a mechanism by which these two proteins coordinate their activities to regulate DNA repair, cell survival, and aging.

  • activation of p53 or loss of the Cockayne Syndrome group b repair protein causes metaphase fragility of human u1 u2 and 5s genes
    Molecular Cell, 2000
    Co-Authors: Huaying Fan, Daiqing Liao, Arnold D Bailey, Alan M Weiner
    Abstract:

    Infection by adenovirus 12, transfection with the Ad12 E1B 55 kDa gene, or activation of p53 cause metaphase fragility of four loci (RNU1, PSU1, RNU2, and RN5S) each containing tandemly repeated genes for an abundant small RNA (U1, U2, and 5S RNA). We now show that loss of the Cockayne Syndrome group B protein (CSB) or overexpression of the p53 carboxy-terminal domain induces fragility of the same loci; moreover, p53 interacts with CSB in vivo and in vitro. We propose that CSB functions as an elongation factor for transcription of structured RNAs, including some mRNAs. Activation of p53 would inhibit CSB, stalling transcription complexes and locally blocking chromatin condensation. Impaired transcription elongation may also explain the diverse clinical features of Cockayne Syndrome.

Wim Vermeulen - One of the best experts on this subject based on the ideXlab platform.

  • repair protein persistence at dna lesions characterizes xpf defect with Cockayne Syndrome features
    Nucleic Acids Research, 2018
    Co-Authors: Mariangela Sabatella, Arjan F Theil, Cristina Ribeirosilva, Jana Slyskova, Karen Thijssen, Chantal Voskamp, Hannes Lans, Wim Vermeulen
    Abstract:

    textabstractThe structure-specific ERCC1-XPF endonuclease plays a key role in DNA damage excision by nucleotide excision repair (NER) and interstrand crosslink repair. Mutations in this complex can either cause xeroderma pigmentosum (XP) or XP combined with Cockayne Syndrome (XPCS-complex) or Fanconi anemia. However, most patients carry compound heterozygous mutations, which confounds the dissection of the phenotypic consequences for each of the identified XPF alleles. Here, we analyzed the functional impact of individual pathogenic XPF alleles on NER. We show that XP-causing mutations diminish XPF recruitment to DNA damage and only mildly affect global genome NER. In contrast, an XPCS-complex-specific mutation causes persistent recruitment of XPF and the upstream core NER machinery to DNA damage and severely impairs both global genome and transcription-coupled NER. Remarkably, persistence of NER factors at DNA damage appears to be a common feature of XPCS-complex cells, suggesting that this could be a determining factor contributing to the development of additional developmental and/or neurodegenerative features in XP patients.

  • a ubiquitin binding domain in Cockayne Syndrome b required for transcription coupled nucleotide excision repair
    Molecular Cell, 2010
    Co-Authors: Roy Anindya, Jean-marc Egly, Wim Vermeulen, Ulrik Kristensen, Pierreolivier Mari, Hanneke Kool, Giuseppina Gigliamari, Leon H F Mullenders, Maria Fousteri, Jesper Q Svejstrup
    Abstract:

    Transcription-coupled nucleotide excision repair (TC-NER) allows RNA polymerase II (RNAPII)-blocking lesions to be rapidly removed from the transcribed strand of active genes. Defective TCR in humans is associated with Cockayne Syndrome (CS), typically caused by defects in either CSA or CSB. Here, we show that CSB contains a ubiquitin-binding domain (UBD). Cells expressing UBD-less CSB (CSB(del)) have phenotypes similar to those of cells lacking CSB, but these can be suppressed by appending a heterologous UBD, so ubiquitin binding is essential for CSB function. Surprisingly, CSB(del) remains capable of assembling nucleotide excision repair factors and repair synthesis proteins around damage-stalled RNAPII, but such repair complexes fail to excise the lesion. Together, our results indicate an essential role for protein ubiquitylation and CSB's UBD in triggering damage incision during TC-NER and allow us to integrate the function of CSA and CSB in a model for the process.

  • atp dependent chromatin remodeling by the Cockayne Syndrome b dna repair transcription coupling factor
    Molecular and Cellular Biology, 2000
    Co-Authors: Elisabetta Citterio, Vincent Van Den Boom, Gavin R Schnitzler, Roland Kanaar, Edgar Bonte, Robert E Kingston, Jan H J Hoeijmakers, Wim Vermeulen
    Abstract:

    The Cockayne Syndrome B protein (CSB) is required for coupling DNA excision repair to transcription in a process known as transcription-coupled repair (TCR). Cockayne Syndrome patients show UV sensitivity and severe neurodevelopmental abnormalities. CSB is a DNA-dependent ATPase of the SWI2/SNF2 family. SWI2/SNF2-like proteins are implicated in chromatin remodeling during transcription. Since chromatin structure also affects DNA repair efficiency, chromatin remodeling activities within repair are expected. Here we used purified recombinant CSB protein to investigate whether it can remodel chromatin in vitro. We show that binding of CSB to DNA results in an alteration of the DNA double-helix conformation. In addition, we find that CSB is able to remodel chromatin structure at the expense of ATP hydrolysis. Specifically, CSB can alter DNase I accessibility to reconstituted mononucleosome cores and disarrange an array of nucleosomes regularly spaced on plasmid DNA. In addition, we show that CSB interacts not only with double-stranded DNA but also directly with core histones. Finally, intact histone tails play an important role in CSB remodeling. CSB is the first repair protein found to play a direct role in modulating nucleosome structure. The relevance of this finding to the interplay between transcription and repair is discussed.

  • the Cockayne Syndrome b protein involved in transcription coupled dna repair resides in an rna polymerase ii containing complex
    The EMBO Journal, 1997
    Co-Authors: Alain J. Van Gool, Jean-marc Egly, Elisabetta Citterio, Wim Vermeulen, Suzanne Rademakers, Roselinde Van Os, Angelos Constantinou, D Bootsma, Jan H J Hoeijmakers
    Abstract:

    Transcription-coupled repair (TCR), a subpathway of nucleotide excision repair (NER) defective in Cockayne Syndrome A and B (CSA and CSB), is responsible for the preferential removal of DNA lesions from the transcribed strand of active genes, permitting rapid resumption of blocked transcription. Here we demonstrate by microinjection of antibodies against CSB and CSA gene products into living primary fibroblasts, that both proteins are required for TCR and for recovery of RNA synthesis after UV damage in vivo but not for basal transcription itself. Furthermore, immunodepletion showed that CSB is not required for in vitro NER or transcription. Its central role in TCR suggests that CSB interacts with other repair and transcription proteins. Gel filtration of repair- and transcription-competent whole cell extracts provided evidence that CSB and CSA are part of large complexes of different sizes. Unexpectedly, there was no detectable association of CSB with several candidate NER and transcription proteins. However, a minor but significant portion (10-15%) of RNA polymerase II was found to be tightly associated with CSB. We conclude that within cell-free extracts, CSB is not stably associated with the majority of core NER or transcription components, but is part of a distinct complex involving RNA polymerase II. These findings suggest that CSB is implicated in, but not essential for, transcription, and support the idea that Cockayne Syndrome is due to a combined repair and transcription deficiency.

Tinna Stevnsner - One of the best experts on this subject based on the ideXlab platform.

  • two Cockayne Syndrome patients with a novel splice site mutation clinical and metabolic analyses
    Mechanisms of Ageing and Development, 2018
    Co-Authors: Ines Sanchezroman, Sofie Lautrup, Maria D Aamann, Edward G Neilan, John R Østergaard, Tinna Stevnsner
    Abstract:

    Abstract Cockayne Syndrome (CS) is a rare autosomal recessive disorder, which leads to neurodegeneration, growth failure and premature aging. Most of the cases are due to mutations in the ERCC6 gene, which encodes the protein CSB. CSB is involved in several functions including DNA repair and transcription. Here we describe two Danish brothers with CS. Both patients carried a novel splice site mutation (c.2382+2T>G), and a previously described nonsense mutation (c.3259C>T, p.Arg1087X) in a biallelic state. Both patients presented the cardinal features of the disease including microcephaly, congenital cataract and postnatal growth failure. In addition, their fibroblasts were hypersensitive to UV irradiation and exhibited increased superoxide levels in comparison to fibroblasts from healthy age and gender matched individuals. Metabolomic analysis revealed a distinctive metabolic profile in cells from the CS patients compared to control cells. Among others, α-ketoglutarate, hydroxyglutarate and certain amino acids (ornithine, proline and glycine) were reduced in the CS patient fibroblasts, whereas glycolytic intermediates (glucose-6-phosphate and pyruvic acid) and fatty acids (palmitic, stearic and myristic acid) were increased. Our data not only provide additional information to the database of CS mutations, but also point towards targets for potential treatment of this devastating disease.

  • regulatory interplay of Cockayne Syndrome b atpase and stress response gene atf3 following genotoxic stress
    Proceedings of the National Academy of Sciences of the United States of America, 2013
    Co-Authors: Ulrik Kristensen, Tinna Stevnsner, Vilhelm A Bohr, Vincent Laugel, Alexey Epanchintsev, Marcalexander Rauschendorf, Frederic Coin, Jean-marc Egly
    Abstract:

    Cockayne Syndrome type B ATPase (CSB) belongs to the SwItch/Sucrose nonfermentable family. Its mutations are linked to Cockayne Syndrome phenotypes and classically are thought to be caused by defects in transcription-coupled repair, a subtype of DNA repair. Here we show that after UV-C irradiation, immediate early genes such as activating transcription factor 3 (ATF3) are overexpressed. Although the ATF3 target genes, including dihydrofolate reductase (DHFR), were unable to recover RNA synthesis in CSB-deficient cells, transcription was restored rapidly in normal cells. There the synthesis of DHFR mRNA restarts on the arrival of RNA polymerase II and CSB and the subsequent release of ATF3 from its cAMP response element/ATF target site. In CSB-deficient cells ATF3 remains bound to the promoter, thereby preventing the arrival of polymerase II and the restart of transcription. Silencing of ATF3, as well as stable introduction of wild-type CSB, restores RNA synthesis in UV-irradiated CSB cells, suggesting that, in addition to its role in DNA repair, CSB activity likely is involved in the reversal of inhibitory properties on a gene-promoter region. We present strong experimental data supporting our view that the transcriptional defects observed in UV-irradiated CSB cells are largely the result of a permanent transcriptional repression of a certain set of genes in addition to some defect in DNA repair.

  • multiple interaction partners for Cockayne Syndrome proteins implications for genome and transcriptome maintenance
    Mechanisms of Ageing and Development, 2013
    Co-Authors: Maria D Aamann, Vilhelm A Bohr, Meltem Muftuoglu, Tinna Stevnsner
    Abstract:

    Cockayne Syndrome (CS) is characterized by progressive multisystem degeneration and is classified as a segmental premature aging Syndrome. The majority of CS cases are caused by defects in the CS complementation group B (CSB) protein and the rest are mainly caused by defects in the CS complementation group A (CSA) protein. Cells from CS patients are sensitive to UV light and a number of other DNA damaging agents including various types of oxidative stress. The cells also display transcription deficiencies, abnormal apoptotic response to DNA damage, and DNA repair deficiencies. Herein we have critically reviewed the current knowledge about known protein interactions of the CS proteins. The review focuses on the participation of the CSB and CSA proteins in many different protein interactions and complexes, and how these interactions inform us about pathways that are defective in the disease.

  • Cockayne Syndrome group b protein promotes mitochondrial dna stability by supporting the dna repair association with the mitochondrial membrane
    The FASEB Journal, 2010
    Co-Authors: Maria D Aamann, Meltem Muftuoglu, Morten Scheibyeknudsen, Brian R Berquist, David M Wilson, Christina Hvitby, Martin M Sorensen, Jingyan Tian, Nadja C De Souzapinto, Tinna Stevnsner
    Abstract:

    Cockayne Syndrome (CS) is a human premature aging disorder associated with severe developmental deficiencies and neurodegeneration, and phenotypically it resembles some mitochondrial DNA (mtDNA) diseases. Most patients belong to complementation group B, and the CS group B (CSB) protein plays a role in genomic maintenance and transcriptome regulation. By immunocytochemistry, mitochondrial fractionation, and Western blotting, we demonstrate that CSB localizes to mitochondria in different types of cells, with increased mitochondrial distribution following menadione-induced oxidative stress. Moreover, our results suggest that CSB plays a significant role in mitochondrial base excision repair (BER) regulation. In particular, we find reduced 8-oxo-guanine, uracil, and 5-hydroxy-uracil BER incision activities in CSB-deficient cells compared to wild-type cells. This deficiency correlates with deficient association of the BER activities with the mitochondrial inner membrane, suggesting that CSB may participate in ...

  • Cockayne Syndrome Group B Protein Stimulates Repair of Formamidopyrimidines by NEIL1 DNA Glycosylase
    The Journal of biological chemistry, 2009
    Co-Authors: Meltem Muftuoglu, Maria D Aamann, Tinna Stevnsner, Miral Dizdaroglu, Güldal Kirkali, Nadja C. De Souza-pinto, Arin Dogan, Ivana Rybanska, Vilhelm A Bohr
    Abstract:

    Abstract Cockayne Syndrome (CS) is a premature aging condition characterized by sensitivity to UV radiation. However, this phenotype does not explain the progressive neurodegeneration in CS patients. It could be due to the hypersensitivity of CSB-deficient cells to oxidative stress. So far most studies on the role of CSB in repair of oxidatively induced DNA lesions have focused on 7,8-dihydro-8-oxoguanine. This study examines the role of CSB in the repair of formamidopyrimidines 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine (FapyAde), which are substrates for endonuclease VIII-like (NEIL1) DNA glycosylase. Results presented here show that csb-/- mice have a higher level of endogenous FapyAde and FapyGua in DNA from brain and kidney than wild type mice as well as higher levels of endogenous FapyAde in genomic DNA and mtDNA from liver. In addition, CSB stimulates NEIL1 incision activity in vitro, and CSB and NEIL1 co-immunoprecipitate and co-localize in HeLa cells. When CSB and NEIL1 are depleted from HeLa cells by short hairpin RNA knockdown, repair of induced FapyGua is strongly inhibited. These results suggest that CSB plays a role in repair of formamidopyrimidines, possibly by interacting with and stimulating NEIL1, and that accumulation of such modifications may have a causal role in the pathogenesis of CS.