RESUMEN
Myelination is essential for neuronal function and health. In peripheral nerves, >100 causative mutations have been identified that cause Charcot-Marie-Tooth disease, a disorder that can affect myelin sheaths. Among these, a number of mutations are related to essential targets of the posttranslational modification neddylation, although how these lead to myelin defects is unclear. Here, we demonstrate that inhibiting neddylation leads to a notable absence of peripheral myelin and axonal loss both in developing and regenerating mouse nerves. Our data indicate that neddylation exerts a global influence on the complex transcriptional and posttranscriptional program by simultaneously regulating the expression and function of multiple essential myelination signals, including the master transcription factor EGR2 and the negative regulators c-Jun and Sox2, and inducing global secondary changes in downstream pathways, including the mTOR and YAP/TAZ signaling pathways. This places neddylation as a critical regulator of myelination and delineates the potential pathogenic mechanisms involved in CMT mutations related to neddylation.
Asunto(s)
Enfermedad de Charcot-Marie-Tooth , Células de Schwann , Animales , Ratones , Vaina de Mielina/genética , Enfermedad de Charcot-Marie-Tooth/genética , Mutación , Procesamiento Proteico-PostraduccionalRESUMEN
Understanding how chromatin organisation is duplicated on the two daughter strands is a central question in epigenetics. In mammals, following the passage of the replisome, nucleosomes lose their defined positioning and transcription contributes to their re-organisation. However, whether transcription plays a greater role in the organization of chromatin following DNA replication remains unclear. Here we analysed protein re-association with newly replicated DNA upon inhibition of transcription using iPOND coupled to quantitative mass spectrometry. We show that nucleosome assembly and the re-establishment of most histone modifications are uncoupled from transcription. However, RNAPII acts to promote the re-association of hundreds of proteins with newly replicated chromatin via pathways that are not observed in steady-state chromatin. These include ATP-dependent remodellers, transcription factors and histone methyltransferases. We also identify a set of DNA repair factors that may handle transcription-replication conflicts during normal transcription in human non-transformed cells. Our study reveals that transcription plays a greater role in the organization of chromatin post-replication than previously anticipated.
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Cromatina , ARN Polimerasa II , Animales , Humanos , ARN Polimerasa II/metabolismo , Replicación del ADN , Nucleosomas , Factores de Transcripción/metabolismo , Ensamble y Desensamble de Cromatina , Mamíferos/genética , Mamíferos/metabolismoRESUMEN
DONSON is one of 13 genes mutated in a form of primordial microcephalic dwarfism known as Meier-Gorlin syndrome. The other 12 encode components of the CDC45-MCM-GINS helicase, around which the eukaryotic replisome forms, or are factors required for helicase assembly during DNA replication initiation. A role for DONSON in CDC45-MCM-GINS assembly was unanticipated, since DNA replication initiation can be reconstituted in vitro with purified proteins from budding yeast, which lacks DONSON. Using mouse embryonic stem cells as a model for the mammalian helicase, we show that DONSON binds directly but transiently to CDC45-MCM-GINS during S-phase and is essential for chromosome duplication. Rapid depletion of DONSON leads to the disappearance of the CDC45-MCM-GINS helicase from S-phase cells and our data indicate that DONSON is dispensable for loading of the MCM2-7 helicase core onto chromatin during G1-phase, but instead is essential for CDC45-MCM-GINS assembly during S-phase. These data identify DONSON as a missing link in our understanding of mammalian chromosome duplication and provide a molecular explanation for why mutations in human DONSON are associated with Meier-Gorlin syndrome.
Asunto(s)
Proteínas de Ciclo Celular , Duplicación Cromosómica , Ratones , Animales , Humanos , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Ciclo Celular , Replicación del ADN , Proteínas de Mantenimiento de Minicromosoma/metabolismo , Mamíferos/metabolismoRESUMEN
FAM111A is a replisome-associated protein and dominant mutations within its trypsin-like peptidase domain are linked to severe human developmental syndrome, the Kenny-Caffey syndrome. However, FAM111A functions remain unclear. Here, we show that FAM111A facilitates efficient activation of DNA replication origins. Upon hydroxyurea treatment, FAM111A-depleted cells exhibit reduced single-stranded DNA formation and a better survival rate. Unrestrained expression of FAM111A WT and patient mutants causes accumulation of DNA damage and cell death, only when the peptidase domain remains intact. Unrestrained expression of FAM111A WT also causes increased single-stranded DNA formation that relies on S phase entry, FAM111A peptidase activity but not its binding to proliferating cell nuclear antigen. Altogether, these data unveil how FAM111A promotes DNA replication under normal conditions and becomes harmful in a disease context.
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ADN de Cadena Simple , Origen de Réplica , Humanos , Origen de Réplica/genética , Replicación del ADN/genética , Fase S , Péptido Hidrolasas/genética , Péptido Hidrolasas/metabolismo , Receptores Virales/metabolismoRESUMEN
Chromatin organization must be maintained during cell proliferation to preserve cellular identity and genome integrity. However, DNA replication results in transient displacement of DNA-bound proteins, and it is unclear how they regain access to newly replicated DNA. Using quantitative proteomics coupled to Nascent Chromatin Capture or isolation of Proteins on Nascent DNA, we provide time-resolved binding kinetics for thousands of proteins behind replisomes within euchromatin and heterochromatin in human cells. This shows that most proteins regain access within minutes to newly replicated DNA. In contrast, 25% of the identified proteins do not, and this delay cannot be inferred from their known function or nuclear abundance. Instead, chromatin organization and G1 phase entry affect their reassociation. Finally, DNA replication not only disrupts but also promotes recruitment of transcription factors and chromatin remodelers, providing a significant advance in understanding how DNA replication could contribute to programmed changes of cell memory.
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Cromatina , Proteómica , Humanos , Replicación del ADN , Eucromatina , Heterocromatina , ADNRESUMEN
DNA damage tolerance plays a key role in protecting cell viability through translesion synthesis and template switching-mediated bypass of genotoxic polymerase-blocking base lesions. Both tolerance pathways critically rely on ubiquitylation of the proliferating-cell nuclear antigen (PCNA) on lysine 164 and have been proposed to operate uncoupled from replication. We report that Ubp10 and Ubp12 ubiquitin proteases differentially cooperate in PCNA deubiquitylation, owing to distinct activities on PCNA-linked ubiquitin chains. Ubp10 and Ubp12 associate with replication forks in a fashion determined by Ubp10 dependency on lagging-strand PCNA residence, and they downregulate translesion polymerase recruitment and template switch events engaging nascent strands. These findings reveal PCNAK164 deubiquitylation as a key mechanism for the modulation of lesion bypass during replication, which might set a framework for establishing strand-differential pathway choices. We propose that damage tolerance is tempered at replication forks to limit the extension of bypass events and sustain chromosome replication rates.
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Daño del ADN , Replicación del ADN , Antígeno Nuclear de Célula en Proliferación/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Ubiquitina Tiolesterasa/metabolismo , Ubiquitinación , ADN de Hongos/biosíntesis , ADN Polimerasa Dirigida por ADN/metabolismo , Mutación/genética , Fase S , Moldes GenéticosRESUMEN
PURPOSE: The aim of this study was to describe the experience of using a peripherally inserted central catheter (PICC) in cancer sufferers receiving outpatient treatment. METHODS: A qualitative, phenomenological study was performed. Purposeful sampling methods were used. Data collection methods included semi-structured interviews and researcher field notes. Thematic analysis was used to analyze data. The study was conducted following the Consolidated Criteria for Reporting Qualitative Research guidelines. RESULTS: Eighteen patients (61% women, mean age 58 years) participated. They spent a mean duration of 155 days with the line in place. Two themes were identified with different subgroups. The theme "Living with a PICC line," including the subthemes "Benefits" and "Disadvantages," displays how the implantation is experienced by patients in a dichotomous manner. This highlighted both the beneficial and negative aspects of the implantation. The second theme was "Adapting to life with the catheter" and comprised three subthemes: "Advantages," "Lifestyle modifications," and "Overall assessment of the peripherally inserted central catheter," which shows how patients gradually accept the catheter by adapting their lifestyle. CONCLUSIONS: Over time, most patients considered having a PICC line to be a positive experience that they would recommend to other patients, as they found that it did not alter their quality of life. These results can be applied in Oncology Units for developing specific protocols for patients.
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Antineoplásicos/administración & dosificación , Cateterismo Venoso Central/psicología , Cateterismo Periférico/psicología , Neoplasias/tratamiento farmacológico , Calidad de Vida/psicología , Administración Intravenosa/métodos , Adulto , Anciano , Atención Ambulatoria/métodos , Antineoplásicos/uso terapéutico , Femenino , Humanos , Estilo de Vida , Masculino , Oncología Médica/métodos , Persona de Mediana Edad , Pacientes Ambulatorios , Investigación Cualitativa , Encuestas y CuestionariosRESUMEN
BACKGROUND AND AIM: The use of venous catheters is a widespread practice, especially in oncological and oncohematological units. The objective of this study was to evaluate the complications associated with peripherally inserted central catheters (PICCs) in a cohort of patients. MATERIALS AND METHODS: In this retrospective cohort study, we included all patient carrying PICCs (n = 603) inserted at our institute between October 2010 and December 2013. The main variables collected were medical diagnosis, catheter care, location, duration of catheterization, reasons for catheter removal, complications, and nursing care. Complications were classified as infection, thrombosis, phlebitis, migration, edema, and/or ecchymosis. RESULTS: All patients were treated according to the same "nursing care" protocol. The incidence rate of complications was two cases per 1000 days of catheter duration. The most relevant complications were infection and thrombosis, both with an incidence of 0.17 cases per 1000 days of the total catheterization period. The total average duration of catheterization was 170 days [SD 6.06]. Additionally to "end of treatment" (48.42%) and "exitus", (22.53%) the most frequent cause of removal was migration (displacement towards the exterior) of the catheter (5.80%). CONCLUSIONS: PICCs are safe devices that allow the administration of long-term treatment and preserve the integrity of the venous system of the patient. Proper care of the catheter is very important to improve the quality life of patients with oncologic and hematologic conditions. Therefore, correct training of professionals and patients as well as following the latest scientific recommendations are particularly relevant.
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Infecciones Relacionadas con Catéteres/epidemiología , Cateterismo Periférico/efectos adversos , Catéteres Venosos Centrales/efectos adversos , Edema/epidemiología , Trombosis/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Infecciones Relacionadas con Catéteres/etiología , Edema/etiología , Femenino , Humanos , Incidencia , Persona de Mediana Edad , Flebitis/epidemiología , Flebitis/etiología , Estudios Retrospectivos , Trombosis/etiología , Adulto JovenRESUMEN
Proliferating-cell nuclear antigen (PCNA) is a DNA sliding clamp with an essential function in DNA replication and a key role in tolerance to DNA damage by ensuring the bypass of lesions. In eukaryotes, DNA damage tolerance is regulated by ubiquitylation of lysine 164 of PCNA through a well-known control mechanism; however, the regulation of PCNA deubiquitylation remains poorly understood. Our work is a systematic and functional study on PCNA deubiquitylating enzymes (DUBs) in Schizosaccharomyces pombe. Our study reveals that the deubiquitylation of PCNA in fission yeast cells is a complex process that requires several ubiquitin proteases dedicated to the deubiquitylation of a specific subnuclear fraction of mono- and di-ubiquitylated PCNA or a particular type of poly-ubiquitylated PCNA and that there is little redundancy among these enzymes. To understand how DUB activity regulates the oscillatory pattern of ubiquitylated PCNA in fission yeast, we assembled multiple DUB mutants and found that a quadruple mutation of ubp2(+), ubp12(+), ubp15(+), and ubp16(+) leads to the stable accumulation of mono-, di-, and poly-ubiquitylated forms of PCNA, increases S-phase duration, and sensitizes cells to DNA damage. Our data suggest that the dynamic ubiquitylation and deubiquitylation of PCNA occurs during S-phase to ensure processive DNA replication.