Auswahl der wissenschaftlichen Literatur zum Thema „Progeroid cockayne syndrome“

Cockayne syndrome (CS) is a rare progeroid disorder characterized by multisystem degeneration, including neurological dysfunction, for which deep brain stimulation (DBS) is a proposed treatment. This study represents only the third case of DBS for CS-associated movement disorder and the first in which both proposed targets had devices implanted, allowing for direct comparison. A case of DBS for CS-associated movement disorder is presented. Previous literature documents two cases with one targeting the ventral intermediate nucleus of the thalamus (VIM) and the other targeting the globus pallidus interna (GPi). Our patient underwent stimulation of GPi nuclei followed by repositioning to VIM nuclei with improved symptom control using VIM stimulation. In all cases, there was a significant clinical benefit without off-target effects. CS-associated movement disorder exhibits phenotypic variability for which DBS is a viable treatment. Target selection should be driven by clinical phenotype.

Cockayne syndrome (CS) is a rare autosomal recessive disorder that affects the DNA repair process. It is a progeroid syndrome predisposing patients to accelerated aging and to increased susceptibility to respiratory infections. Here, we studied the immune status of CS patients to determine potential biomarkers associated with pathological aging. CS patients, as well as elderly and young, healthy donors, were enrolled in this study. Complete blood counts for patients and donors were assessed, immune cell subsets were analyzed using flow cytometry, and candidate cytokines were analyzed via multi-analyte ELISArray kits. In CS patients, we noticed a high percentage of lymphocytes, an increased rate of intermediate and non-classical monocytes, and a high level of pro-inflammatory cytokine IL-8. In addition, we identified an increased rate of particular subtypes of T Lymphocyte CD8+ CD28− CD27−, which are senescent T cells. Thus, an inflammatory state was found in CS patients that is similar to that observed in the elderly donors and is associated with an immunosenescence status in both groups. This could explain the CS patients’ increased susceptibility to infections, which is partly due to an aging-associated inflammation process.

UV-sensitive syndrome (UVSS) and Cockayne syndrome (CS) are human disorders caused by CSA or CSB gene mutations; both conditions cause defective transcription-coupled repair and photosensitivity. Patients with CS also display neurological and developmental abnormalities and dramatic premature aging, and their cells are hypersensitive to oxidative stress. We report CSA/CSB-dependent depletion of the mitochondrial DNA polymerase-γ catalytic subunit (POLG1), due to HTRA3 serine protease accumulation in CS, but not in UVsS or control fibroblasts. Inhibition of serine proteases restored physiological POLG1 levels in either CS fibroblasts and in CSB-silenced cells. Moreover, patient-derived CS cells displayed greater nitroso-redox imbalance than UVSS cells. Scavengers of reactive oxygen species and peroxynitrite normalized HTRA3 and POLG1 levels in CS cells, and notably, increased mitochondrial oxidative phosphorylation, which was altered in CS cells. These data reveal critical deregulation of proteases potentially linked to progeroid phenotypes in CS, and our results suggest rescue strategies as a therapeutic option.

Defects in the DNA repair mechanism nucleotide excision repair (NER) may lead to tumors in xeroderma pigmentosum (XP) or to premature aging with loss of subcutaneous fat in Cockayne syndrome (CS). Mutations of mitochondrial (mt)DNA play a role in aging, but a link between the NER-associated CS proteins and base excision repair (BER)-associated proteins in mitochondrial aging remains enigmatic. We show functional increase of CSA and CSB inside mt and complex formation with mtDNA, mt human 8-oxoguanine glycosylase (mtOGG)-1, and mt single-stranded DNA binding protein (mtSSBP)-1 upon oxidative stress. MtDNA mutations are highly increased in cells from CS patients and in subcutaneous fat of aged Csbm/m and Csa−/− mice. Thus, the NER-proteins CSA and CSB localize to mt and directly interact with BER-associated human mitochondrial 8-oxoguanine glycosylase-1 to protect from aging- and stress-induced mtDNA mutations and apoptosis-mediated loss of subcutaneous fat, a hallmark of aging found in animal models, human progeroid syndromes like CS and in normal human aging.

Cockayne syndrome group A (CS-A) is a rare recessive progeroid disorder characterized by sun sensitivity and neurodevelopmental abnormalities. Cells derived from CS-A patients present as pathological hallmarks excessive oxidative stress, mitochondrial fragmentation and apoptosis associated with hyperactivation of the mitochondrial fission dynamin related protein 1 (DRP1). In this study, by using human cell models we further investigated the interplay between DRP1 and CSA and we determined whether pharmacological or genetic inhibition of DRP1 affects disease progression. Both reactive oxygen and nitrogen species are in excess in CS-A cells and when the mitochondrial translocation of DRP1 is inhibited a reduction of these species is observed together with a recovery of mitochondrial integrity and a significant decrease of apoptosis. This study indicates that the CSA-driven modulation of DRP1 pathway is key to control mitochondrial homeostasis and apoptosis and suggests DRP1 as a potential target in the treatment of CS patients.

ABSTRACT Patients carrying mutations in the XPB helicase subunit of the basal transcription and nucleotide excision repair (NER) factor TFIIH display the combined cancer and developmental-progeroid disorder xeroderma pigmentosum/Cockayne syndrome (XPCS). Due to the dual transcription repair role of XPB and the absence of animal models, the underlying molecular mechanisms of XPBXPCS are largely uncharacterized. Here we show that severe alterations in Xpb cause embryonic lethality and that knock-in mice closely mimicking an XPCS patient-derived XPB mutation recapitulate the UV sensitivity typical for XP but fail to show overt CS features unless the DNA repair capacity is further challenged by crossings to the NER-deficient Xpa background. Interestingly, the Xpb XPCS Xpa double mutants display a remarkable interanimal variance, which points to stochastic DNA damage accumulation as an important determinant of clinical diversity in NER syndromes. Furthermore, mice carrying the Xpb XPCS mutation together with a point mutation in the second TFIIH helicase Xpd are healthy at birth but display neonatal lethality, indicating that transcription efficiency is sufficient to permit embryonal development even when both TFIIH helicases are crippled. The double-mutant cells exhibit sensitivity to oxidative stress, suggesting a role for endogenous DNA damage in the onset of XPB-associated CS.

Cockayne syndrome is a rare autosomal recessive disorder characterized by premature ageing (progeria), facial anomalies, cachectic dwarfism, mental retardation, cutaneous photosensitivity, and retinopathy, loss of adipose tissue and muscle, and neurological abnormality which are associated with the changes in the brain parenchyma. The findings of computed tomography scan and especially magnetic resonance imaging of the brain support the clinical diagnosis of CS. There is no permanent cure of this condition and death usually occurs in the second or third decade due to functional disability and multiple infections.

ABSTRACT Mutations in the CSA and CSB genes cause Cockayne syndrome, a rare inherited disorder characterized by UV sensitivity, severe neurological abnormalities, and progeriod symptoms. Both gene products function in the transcription-coupled repair (TCR) subpathway of nucleotide excision repair (NER), providing the cell with a mechanism to remove transcription-blocking lesions from the transcribed strands of actively transcribed genes. Besides a function in TCR of NER lesions, a role of CSB in (transcription-coupled) repair of oxidative DNA damage has been suggested. In this study we used mouse models to compare the effect of a CSA or a CSB defect on oxidative DNA damage sensitivity at the levels of the cell and the intact organism. In contrast to CSB −/− mouse embryonic fibroblasts (MEFs), CSA −/− MEFs are not hypersensitive to gamma-ray or paraquat treatment. Similar results were obtained for keratinocytes. In contrast, both CSB −/− and CSA −/− embryonic stem cells show slight gamma-ray sensitivity. Finally, CSB −/− but not CSA −/− mice fed with food containing di(2-ethylhexyl)phthalate (causing elevated levels of oxidative DNA damage in the liver) show weight reduction. These findings not only uncover a clear difference in oxidative DNA damage sensitivity between CSA- and CSB-deficient cell lines and mice but also show that sensitivity to oxidative DNA damage is not a uniform characteristic of Cockayne syndrome. This difference in the DNA damage response between CSA- and CSB-deficient cells is unexpected, since until now no consistent differences between CSA and CSB patients have been reported. We suggest that the CSA and CSB proteins in part perform separate roles in different DNA damage response pathways.

The nucleolus organizes around the sites of transcription by RNA polymerase I (RNA Pol I). rDNA transcription by this enzyme is the key step of ribosome biogenesis and most of the assembly and maturation processes of the ribosome occur co-transcriptionally. Therefore, disturbances in rRNA transcription and processing translate to ribosomal malfunction. Nucleolar malfunction has recently been described in the classical progeria of childhood, Hutchinson–Gilford syndrome (HGPS), which is characterized by severe signs of premature aging, including atherosclerosis, alopecia, and osteoporosis. A deregulated ribosomal biogenesis with enlarged nucleoli is not only characteristic for HGPS patients, but it is also found in the fibroblasts of “normal” aging individuals. Cockayne syndrome (CS) is also characterized by signs of premature aging, including the loss of subcutaneous fat, alopecia, and cataracts. It has been shown that all genes in which a mutation causes CS, are involved in rDNA transcription by RNA Pol I. A disturbed ribosomal biogenesis affects mitochondria and translates into ribosomes with a reduced translational fidelity that causes endoplasmic reticulum (ER) stress and apoptosis. Therefore, it is speculated that disease-causing disturbances in the process of ribosomal biogenesis may be more common than hitherto anticipated.

La compréhension des altérations moléculaires du syndrome de Cockayne (CS), une maladie génétique rare dans laquelle le vieillissement est accéléré, est essentielle pour développer des traitements, et élucider les dysfonctionnements impliqués dans le vieillissement physiologique. Le CS présente un large spectre de sévérité clinique qui ne repose pas sur une simple corrélation génotype/phénotype. Ce projet est basé sur une altération spécifique aux cellules CS, démontrée dans le laboratoire, qui implique la déplétion de l'ADN polymérase mitochondriale POLG1 conduisant à un dysfonctionnement de l’organelle. Cette altération est due à la surexpression de la protéase HTRA3, qui est déclenchée par un stress oxydatif/nitrosatif accru. La réduction de ces espèces réactives a permis de corriger ces altérations et a ouvert la voie à un traitement pour le CS. Ce travail de thèse i) a contribué à la découverte que la voie défectueuse du CS est récapitulée au cours de la sénescence réplicative des cellules normales, un processus lié au vieillissement physiologique, ii) a identifié le mécanisme HTRA3-dépendant de dégradation de POLG1 dans les cellules CS et dans les cellules sénescentes, iii) a développé de multiples modèles cellulaires isogéniques (fibroblastes, cellules souches pluripotentes induites et organoïdes cérébraux) avec CRISPR-Cas9, permettant des études mécanistiques et de corrélation génotype/phénotype. Ces études fournissent de nouvelles informations sur les mécanismes conduisant aux altérations progeroïdes dans le CS, sur leurs liens avec le vieillissement physiologique, et établissent des modèles expérimentaux uniques pour l'étude de la pathogenèse de cette maladie
Dissecting the molecular defects in rare genetic disorders like Cockayne syndrome (CS), in which ageing is dramatically accelerated, is critical to develop treatments, which are missing to date, and elucidate dysfunctions that are possibly implicated in physiological ageing. CS also displays a large spectrum of clinical severity which does not rely on simple genotype/phenotype correlation. This project is based on a working model established in the lab that identified CS-specific depletion of the mitochondrial DNA polymerase POLG1 leading to mitochondrial dysfunction, as a possible cause of CS progeroid defects. POLG1 depletion required overexpression of the HTRA3 protease, which was trigged by increased oxidative/nitrosative stress. Scavenging both reactive species, rescued these defects and opened the path to a treatment for CS. This PhD work: i) Contributed to the discovery that the CS-defective pathway is recapitulated in replicative senescence of normal cells, a process linked to regular aging. ii) Identified the mechanism of HTRA3-dependent POLG1 degradation in CS and senescent cells with implications for POLG1 homeostasis in normal cells. iii) Developed multiple isogenic cellular models (skin fibroblasts, induced pluripotent stem cells and cerebral organoids) with CRISPR-Cas9 that are essential for mechanistic studies and to address genotype/phenotype correlations, in the absence of a reliable mouse model for CS. Taken together, these studies provide novel insights into the mechanisms leading to defects in progeroid CS and their links with physiological ageing. They also establish unique CS models for studying CS pathogenesis

Les syndromes progéroïdes regroupent un ensemble de pathologies caractérisées par un vieillissement précoce et accéléré. Le syndrome le plus connu et étudié est la progéria de Hutchinson-Gilford dont l'incidence est de 1 cas sur 8 millions ce qui en fait une maladie très rare. Nous avons étudié trois symptômes progéroïdes dont le syndrome HGPS, un syndrome HGPS-like ainsi qu'un syndrome APS. Ces pathologies ont de nombreux symptômes en commun dont une ostéolyse, une lipodystrophie, ainsi qu'une atteinte cardiovasculaire. Ces trois syndromes sont provoqués par différentes mutations du gène LMNA qui code pour les Lamines A et C. Nous avons utilisé le modèle des iPSCs afin d'étudier in vitro la physiopathologie de ces trois syndromes en les comparant à des cellules contrôles. Les cellules dérivées de la voie mésenchymateuse étant majoritairement altérées dans ces pathologies, nous avons créé des modèles in vitro d'étude de la différentiation en MSCs. De plus, ces patients présentant des altérations arterio-veineuses, nous avons analysé la différenciation en VSMCs. Le phénotype des ces cellules a été analysé et les profils transcriptomiques comparés pour les différentes lignées. Des gènes communs, impliqués dans le stress oxydatif et dans des systèmes de réparation géniques ont été retrouvés comme étant altérés. De plus, nous avons mis en évidence des altérations de voies de signalisation indispensables à la survie et à la prolifération cellulaire en comparant les cellules progéroïdes aux contrôles. Certaines de ces voies biologiques ouvrent de nouvelles perspectives dans la compréhension des symptômes observés chez ces patients
Progeroid syndromes are a group of pathologies characterized by accelerated and early aging. One of the most studied of these diseases is HGPS, with an estimated incidence of 1 in 8 millions birth making it an extremely rare disease. We focused our attention on three different progeroid syndromes including classic HGPS, a HGPS-like and an atypical progeroid syndrome. These pathologies share many symptoms, including osteolysis, lipodystrophy, and cardiovascular alterations. These 3 syndromes are caused by 3 different mutations in the LMNA gene that encodes A- and C-type lamins, inducing production of a truncated Lamin A in HGPS and HGPS-like and production of a mutated Lamin with a p.T528M substitution in APS. We produced hiPSCs to create a model of these different diseases and investigate in vitro the physiopathology of these syndromes by comparing them to control cells. Cells derived from mesenchymal stem cells being the most impaired type of tissue, we established in vitro models in order to study the differentiation of hiPSCs into MSCs. In addition given the massive cardiovascular defects in these patients, we also investigated differentiation toward the VSMCs. Cell phenotypes were carefully characterized and we compared the transcripttomic profile of the different cell types. We identified dysregulation in genes involved in oxidative stress response and in DNA repair in progeroid cells. In addition, pathways essential for cell survival and proliferation are also modified when comparing progeroid and controls cells. Altogether, these results might explain some of the symptoms observed in progeroid patients but also reveal pathways involved in ageing

Le vieillissement est un processus complexe qui peut être influencé par des facteurs environnementaux et génétiques. Le syndrome progéroïde de Hutchinson-Gilford (HGPS ou progéria) fourni une preuve irréfutable de l'implication de l'épissage dans le processus de vieillissement. La progéria est une maladie due à une mutation hétérozygote silencieuse qui renforce l'utilisation d'un site 5' d'épissage interne dans l'exon 11 de l'ARN pré-messager LMNA, ce qui entraîne la production d'une protéine tronquée appelée «progérine». Le défaut d'épissage du gène LMNA a aussi lieu dans les cellules de personnes âgées, et la correction de ce défaut permet un sauvetage partiel des anomalies qu'il provoque. Ceci fait de l'ARN pré-messager LMNA une cible très attractive pour des thérapies ayant pour but de corriger l'épissage. Mes travaux de thèse ont montré que cette mutation silencieuse active un site d'épissage 5' dans l'exon 11 en changeant la structure de l'ARN. Ce changement de structure facilite l'interaction de la snRNP U1 avec le site d'épissage et permet ainsi sa modulation par les protéines SR SRSF1 et SRSF6. J'ai aussi participé à la caractérisation d'un nouveau modèle murin qui reproduit l'altération d'épissage des patients HGPS au niveau du gène Lmna souris. De façon surprenante, ce modèle récapitule tous les phénotypes du syndrome HGPS. Les souris homozygotes, dans lesquelles la plupart de la lamine A est convertie en progérine, ne vivent pas plus de 5 mois, alors que les souris hétérozygotes vivent autour d'un an et que les contrôles sauvages vivent deux ans. Étonnamment, des souris qui n'expriment ni la lamine A ni la progérine, mais uniquement de la lamine C, vivent plus longtemps que les souris contrôle, suggérant que la lamine A et la progérine, qui sont produites à partir du même transcrit, participent à la régulation de la durée de la vie. De plus, la caractérisation initiale des souris HGPS indique que l'expression de la progérine est délétère pour le tissu adipeux, établissant ainsi un lien inattendu entre l'épuisement du tissu adipeux et le vieillissement accéléré. Ce nouveau modèle murin est actuellement en train d'être utilisé pour des approches de modulation de l'épissage aberrant du gène LMNA avec des oligonucléotides antisense et des petites molécules chimiques
Aging is a complex cellular and organismal process that can be influenced by environmental as well as genetic factors. A striking proof-of-concept that splicing regulation plays an important role in the aging process is provided by Hutchinson-Gilford progeria syndrome (HGPS), a disease caused by a heterozygous silent mutation that enhances the use of an internal 5' splice site in exon 11 of LMNA pre-mRNA and leads to the production of a truncated protein called “progerin”. The LMNA splicing defect also occurs with increased frequency in cells from healthy aged individuals and correction of this defect leads to partial reversal of age-related dysfunction. This makes LMNA pre-mRNA an attractive target for splicing-correction therapies. During my PhD thesis I have characterized the splicing mechanism responsible for progerin production and demonstrated that this process is conserved from mouse to human. I have found that HGPS mutation changes the accessibility of the exon 11 internal 5' splice site, allowing its modulation by U1 snRNP and a subset of SR proteins, namely SRSF6 and SRSF1. I have also participated to the characterization of a new mouse model reproducing human HGPS splicing alteration in the mouse Lmna gene. Strikingly, this model recapitulates all phenotypic manifestations of HGPS. The homozygous mice, where most lamin A is converted to progerin, lived no longer than 5 months, whereas heterozygous mice lived in average one year and wild type littermates up to two years. Unexpectedly, mice expressing neither lamin A nor progerin, but only lamin C, lived longer than wild type littermates mice, suggesting that lamin A and progerin which are produced from the same transcript, control critical steps of lifespan. Furthermore, initial characterization of HGPS mouse model indicated that progerin expression is deleterious for adipose tissue, establishing an unexpected link between adipose tissue depletion and accelerated aging. The new mouse model is currently being used for pharmacological modulation of LMNA aberrant splicing by antisense oligonucleotides and small molecules

Chapter 12 covers Cockayne Syndrome, De Barsy Syndrome, Hallermann-Streiff Syndrome, Hutchinson-Gilford Progeria, and Werner Syndrome. Each condition is discussed in detail, including dermatologic features, associated anomalies, histopathology, basic defect, treatment, mode of inheritance, prenatal diagnosis, and differential diagnosis.