scholarly journals Cockayne syndrome proteins CSA and CSB maintain mitochondrial homeostasis through NAD+ signaling

2020 ◽  
Author(s):  
Mustafa N. Okur ◽  
Evandro F. Fang ◽  
Elayne M. Fivenson ◽  
Vinod Tiwari ◽  
Deborah L. Croteau ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Excision Repair ◽  
Mitochondrial Dynamics ◽  
Accelerated Aging ◽  
Cockayne Syndrome ◽  
Premature Aging ◽  
Postmortem Brain ◽  
Average Life Expectancy ◽  
Postmortem Brain Tissue ◽  
Genes Encoding

AbstractBackgroundCockayne 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.ResultsOur 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.ConclusionsOur 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.

scholarly journals Oxygen-Dependent Accumulation of Purine DNA Lesions in Cockayne Syndrome Cells

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1671 ◽  
Author(s):  
Marios G. Krokidis ◽  
Mariarosaria D’Errico ◽  
Barbara Pascucci ◽  
Eleonora Parlanti ◽  
Annalisa Masi ◽  
...  
Keyword(s):  
Dna Damage ◽  
Oxidative Dna Damage ◽  
Excision Repair ◽  
Enzymatic Digestion ◽  
Cockayne Syndrome ◽  
Dna Lesions ◽  
Premature Aging ◽  
Neurological Features ◽  
Oxygen Tensions ◽  
Base Excision

Cockayne Syndrome (CS) is an autosomal recessive neurodegenerative premature aging disorder associated with defects in nucleotide excision repair (NER). Cells from CS patients, with mutations in CSA or CSB genes, present elevated levels of reactive oxygen species (ROS) and are defective in the repair of a variety of oxidatively generated DNA lesions. In this study, six purine lesions were ascertained in wild type (wt) CSA, defective CSA, wtCSB and defective CSB-transformed fibroblasts under different oxygen tensions (hyperoxic 21%, physioxic 5% and hypoxic 1%). In particular, the four 5′,8-cyclopurine (cPu) and the two 8-oxo-purine (8-oxo-Pu) lesions were accurately quantified by LC-MS/MS analysis using isotopomeric internal standards after an enzymatic digestion procedure. cPu levels were found comparable to 8-oxo-Pu in all cases (3–6 lesions/106 nucleotides), slightly increasing on going from hyperoxia to physioxia to hypoxia. Moreover, higher levels of four cPu were observed under hypoxia in both CSA and CSB-defective cells as compared to normal counterparts, along with a significant enhancement of 8-oxo-Pu. These findings revealed that exposure to different oxygen tensions induced oxidative DNA damage in CS cells, repairable by NER or base excision repair (BER) pathways. In NER-defective CS patients, these results support the hypothesis that the clinical neurological features might be connected to the accumulation of cPu. Moreover, the elimination of dysfunctional mitochondria in CS cells is associated with a reduction in the oxidative DNA damage.

scholarly journals The ATPase Domain but Not the Acidic Region of Cockayne Syndrome Group B Gene Product Is Essential for DNA Repair

1999 ◽  
Vol 10 (11) ◽  
pp. 3583-3594 ◽  
Author(s):  
Robert M. Brosh ◽  
Adayabalam S. Balajee ◽  
Rebecca R. Selzer ◽  
Morten Sunesen ◽  
Luca Proietti De Santis ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Excision Repair ◽  
Uv Light ◽  
Genetic Disorder ◽  
Cockayne Syndrome ◽  
Premature Aging ◽  
Atpase Domain ◽  
Acidic Region

Cockayne syndrome (CS) is a human genetic disorder characterized by UV sensitivity, developmental abnormalities, and premature aging. Two of the genes involved, CSA andCSB, are required for transcription-coupled repair (TCR), a subpathway of nucleotide excision repair that removes certain lesions rapidly and efficiently from the transcribed strand of active genes. CS proteins have also been implicated in the recovery of transcription after certain types of DNA damage such as those lesions induced by UV light. In this study, site-directed mutations have been introduced to the human CSB gene to investigate the functional significance of the conserved ATPase domain and of a highly acidic region of the protein. The CSB mutant alleles were tested for genetic complementation of UV-sensitive phenotypes in the human CS-B homologue of hamster UV61. In addition, theCSB mutant alleles were tested for their ability to complement the sensitivity of UV61 cells to the carcinogen 4-nitroquinoline-1-oxide (4-NQO), which introduces bulky DNA adducts repaired by global genome repair. Point mutation of a highly conserved glutamic acid residue in ATPase motif II abolished the ability of CSB protein to complement the UV-sensitive phenotypes of survival, RNA synthesis recovery, and gene-specific repair. These data indicate that the integrity of the ATPase domain is critical for CSB function in vivo. Likewise, the CSB ATPase point mutant failed to confer cellular resistance to 4-NQO, suggesting that ATP hydrolysis is required for CSB function in a TCR-independent pathway. On the contrary, a large deletion of the acidic region of CSB protein did not impair the genetic function in the processing of either UV- or 4-NQO-induced DNA damage. Thus the acidic region of CSB is likely to be dispensable for DNA repair, whereas the ATPase domain is essential for CSB function in both TCR-dependent and -independent pathways.

scholarly journals Amyloid-Beta Interaction with Mitochondria

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Lucia Pagani ◽  
Anne Eckert
Keyword(s):  
Mitochondrial Dysfunction ◽  
Amyloid Beta ◽  
Mitochondrial Membrane ◽  
Current Knowledge ◽  
Mitochondrial Dynamics ◽  
Intracellular Localization ◽  
Protein A ◽  
Postmortem Brain ◽  
Intermembrane Space ◽  
Inner Mitochondrial Membrane

Mitochondrial dysfunction is a hallmark of amyloid-beta(Aβ)-induced neuronal toxicity in Alzheimer's disease (AD). The recent emphasis on the intracellular biology of Aβand its precursor protein (AβPP) has led researchers to consider the possibility that mitochondria-associated and/or intramitochondrial Aβmay directly cause neurotoxicity. In this paper, we will outline current knowledge of the intracellular localization of both Aβand AβPP addressing the question of how Aβcan access mitochondria. Moreover, we summarize evidence from AD postmortem brain as well as cellular and animal AD models showing that Aβtriggers mitochondrial dysfunction through a number of pathways such as impairment of oxidative phosphorylation, elevation of reactive oxygen species (ROS) production, alteration of mitochondrial dynamics, and interaction with mitochondrial proteins. In particular, we focus on Aβinteraction with different mitochondrial targets including the outer mitochondrial membrane, intermembrane space, inner mitochondrial membrane, and the matrix. Thus, this paper establishes a modified model of the Alzheimer cascade mitochondrial hypothesis.

scholarly journals Cockayne syndrome group B deficiency reduces H3K9me3 chromatin remodeler SETDB1 and exacerbates cellular aging

2019 ◽  
Vol 47 (16) ◽  
pp. 8548-8562 ◽  
Author(s):  
Jong-Hyuk Lee ◽  
Tyler G Demarest ◽  
Mansi Babbar ◽  
Edward W Kim ◽  
Mustafa N Okur ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mitochondrial Dysfunction ◽  
Nicotinamide Adenine Dinucleotide ◽  
Affinity Purification ◽  
Accelerated Aging ◽  
Cockayne Syndrome ◽  
Cellular Aging ◽  
Transcription Start ◽  
Transcription Start Sites ◽  
Group B

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.

scholarly journals Two heterozygous mutations in the ERCC6 gene associated with Cockayne syndrome in a Chinese patient

2019 ◽  
Vol 48 (2) ◽  
pp. 030006051987799
Author(s):  
Qin Zhang ◽  
Minjuan Liu ◽  
Yinghua Liu ◽  
Hui Tang ◽  
Ting Wang ◽  
...  
Keyword(s):  
Sanger Sequencing ◽  
Excision Repair ◽  
Gene Mutations ◽  
Chinese Patient ◽  
Cockayne Syndrome ◽  
Premature Aging ◽  
Compound Heterozygous ◽  
Type I ◽  
Insertion And Deletion ◽  
Prenatal Diagnostic

Objective To confirm diagnosis and explore the genetic aetiology in a Chinese patient suspected to have Cockayne syndrome (CS). Methods The patient was clinically examined, and the patient and her biological parents underwent genetic analysis using whole exome sequencing (WES) and Sanger sequencing. The foetus of the patient’s mother underwent prenatal diagnostic Sanger sequencing using amniotic fluid obtained at 19 weeks’ gestation. Results Clinical examination of the patient showed developmental delay, progressive neurologic dysfunction and premature aging. Two compound, heterozygous ERCC excision repair 6, chromatin remodelling factor ( ERCC6) gene mutations were detected in the proband by WES and confirmed by Sanger sequencing, comprising a known paternal nonsense mutation (c.643G > T, p.E215X) and a novel maternal short insertion and deletion mutation (c.1614_c.1616delGACinsAAACGTCTT, p.K538_T539delinsKNVF). The patient was consequently diagnosed with CS type I. The foetus of the patient’s mother was found to carry only the maternally-derived c.1614_c.1616delGACinsAAACGTCTT variant. Conclusion This study emphasized the value of WES in clinical diagnosis, and enriched the known spectrum of ERCC6 gene mutations.

scholarly journals Cockayne syndrome group A and B proteins converge on transcription-linked resolution of non-B DNA

2016 ◽  
Vol 113 (44) ◽  
pp. 12502-12507 ◽  
Author(s):  
Morten Scheibye-Knudsen ◽  
Anne Tseng ◽  
Martin Borch Jensen ◽  
Karsten Scheibye-Alsing ◽  
Evandro Fei Fang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mitochondrial Dysfunction ◽  
Ribosomal Dna ◽  
Neuroblastoma Cell ◽  
Accelerated Aging ◽  
Neuroblastoma Cell Line ◽  
Cockayne Syndrome ◽  
Rdna Transcription ◽  
Dna Transcription ◽  
G Quadruplex

Cockayne syndrome is a neurodegenerative accelerated aging disorder caused by mutations in the CSA or CSB genes. Although the pathogenesis of Cockayne syndrome has remained elusive, recent work implicates mitochondrial dysfunction in the disease progression. Here, we present evidence that loss of CSA or CSB in a neuroblastoma cell line converges on mitochondrial dysfunction caused by defects in ribosomal DNA transcription and activation of the DNA damage sensor poly-ADP ribose polymerase 1 (PARP1). Indeed, inhibition of ribosomal DNA transcription leads to mitochondrial dysfunction in a number of cell lines. Furthermore, machine-learning algorithms predict that diseases with defects in ribosomal DNA (rDNA) transcription have mitochondrial dysfunction, and, accordingly, this is found when factors involved in rDNA transcription are knocked down. Mechanistically, loss of CSA or CSB leads to polymerase stalling at non-B DNA in a neuroblastoma cell line, in particular at G-quadruplex structures, and recombinant CSB can melt G-quadruplex structures. Indeed, stabilization of G-quadruplex structures activates PARP1 and leads to accelerated aging in Caenorhabditis elegans. In conclusion, this work supports a role for impaired ribosomal DNA transcription in Cockayne syndrome and suggests that transcription-coupled resolution of secondary structures may be a mechanism to repress spurious activation of a DNA damage response.

scholarly journals Current and emerging roles of Cockayne syndrome group B (CSB) protein

2021 ◽  
Author(s):  
Vinod Tiwari ◽  
Beverly A Baptiste ◽  
Mustafa N Okur ◽  
Vilhelm A Bohr
Keyword(s):  
Genome Stability ◽  
Excision Repair ◽  
Redox Homeostasis ◽  
Cockayne Syndrome ◽  
Cellular Systems ◽  
Premature Aging ◽  
Rdna Transcription ◽  
Molecular Features ◽  
Base Excision ◽  
Group B

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.

scholarly journals Immunofluorescence studies to dissect the impact of Cockayne syndrome A alterations on the protein interaction and cellular localization

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Amr Ghit
Keyword(s):  
Cellular Localization ◽  
Excision Repair ◽  
Growth Failure ◽  
Autosomal Recessive Disorder ◽  
Cockayne Syndrome ◽  
Dna Lesions ◽  
Premature Aging ◽  
Neurological Dysfunction ◽  
C Terminus ◽  
The Impact

Abstract Background Cockayne syndrome (CS), which was discovered by Alfred Cockayne nearly 75 years ago, is a rare autosomal recessive disorder characterized by growth failure, neurological dysfunction, premature aging, and other clinical features including microcephaly, ophthalmologic abnormalities, dental caries, and cutaneous photosensitivity. These alterations are caused by mutations in the CSA or CSB genes, both of which are involved in transcription-coupled nucleotide excision repair (TC-NER), the sub-pathway of NER that rapidly removes UV-induced DNA lesions which block the progression of the transcription machinery in the transcribed strand of active genes. Several studies assumed that CSA and CSB genes can play additional roles outside TC-NER, due to the wide variations in type and severity of the CS phenotype and the lack of a clear relationship between genotype and phenotype. To address this issue, our lab generated isogenic cell lines expressing wild type as well as different versions of mutated CSA proteins, fused at the C-terminus with the Flag and HA epitope tags (CSAFlag-HA). In unpublished data, the identity of the CSA-interacting proteins was determined by mass spectrometry. Among which three subunits (namely, CCT3, CCT8, and TCP1) of the TRiC/CCT complex appeared as novel interactors. TRiC is a chaperonin involved in the folding of newly synthesized or unfolded proteins. The aim of this study is directed to investigate by immunofluorescence analysis the impact of the selected CSA mutations on the subcellular localization of the CSA protein itself as well as on its novel interactors CCT3, CCT8, and TCP1. Results We showed that specific CSA mutations impair the proper cellular localization of the protein, but have no impact on the cellular distribution of the TRiC subunits or CSA/TRiC co-localization. Conclusion We suggested that the activity of the TRiC complex does not rely on the functionality of CSA.

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