RESUMEN
Spirituality has been a part of nursing for many centuries and represents an essential value for people, including nurses and patients. Cumulative evidence points to the positive contribution of spiritually on health and wellbeing. However, there is little clarity about what spirituality means. The literature reveals that nurses have ascribed a diversity of interpretations to spirituality. However, no studies have investigated how registered nurses construct their understanding of spirituality using a critical discourse analysis approach. Therefore, the aim of this study was to uncover how registered nurses construct their understanding of spirituality using a critical discourse analysis approach. Twenty registered nurses from a non-denominational public hospital and a faith-based private hospital were interviewed about their understanding of spirituality and practice of spiritual care. A critical discourse analysis approach was used in the examination of the interview texts to uncover underlying social and power features. Links were made between the linguistic features the registered nurses used in their interviews and the broader social context of the study. Three discourses emerged from the interview texts. These include constructing spirituality through personal religious beliefs discourse, holistic discourse and empathetic care discourse. The findings of this study have implications for nurse education and policy makers.
Asunto(s)
Actitud del Personal de Salud , Enfermeras y Enfermeros/psicología , Terapias Espirituales/psicología , Humanos , Enfermeras y Enfermeros/estadística & datos numéricos , Religión , Terapias Espirituales/métodosRESUMEN
PURPOSE: Emergency department nurses work in rapidly changing environments, which can contribute to occupational stress. Emergency department nurses utilise diverse strategies to mediate the impact of stress on their daily lives. There is a paucity of qualitative research which explores emergency department nurses' experiences and perspectives of burnout. This study aimed to explore emergency department nurses' experiences of burnout. Further, the study considered how emergency nurses conceptualised burnout and the strategies they used to manage the professional and personal effects of burnout. PROCEDURES: The COREQ research guidelines were used throughout the study from the design stage through to dissemination. Narrative inquiry was used as the underpinning theoretical framework. The researcher met individually with eight emergency department nurses from NSW hospitals to undertake a face-to-face semi-structured interview. An inductive approach was used to establish major themes within the narrative. FINDINGS: Two major themes were established: experiencing conflicting emotions and trying to establish a personal sense of control. Emergency nurses felt passionate about their professional roles, yet encountered difficulties due to management structures, time constraints and a sense of underappreciation. The misalignment between their expectations and the reality of emergency department nursing, resulted in experiences of burnout such as dissatisfaction and frustrations at work. Consequently, these nurses adopted diverse strategies within both their professional and personal domains. PRINCIPAL CONCLUSIONS: The conclusions of this study are transferable to a variety of acute health services. Health service management have a role to promote a positive workplace culture for nurses, which advocates for home life balance. This will support nurses to construct clear boundaries between professional identity and their personal lives.
Asunto(s)
Agotamiento Profesional , Enfermería de Urgencia , Servicio de Urgencia en Hospital , Humanos , Agotamiento Profesional/psicología , Investigación Cualitativa , Femenino , Nueva Gales del Sur , Narración , Adulto , Satisfacción en el Trabajo , Rol de la Enfermera/psicología , Entrevistas como Asunto , Personal de Enfermería en Hospital/psicología , Masculino , Enfermeras y Enfermeros/psicologíaRESUMEN
The aim of this study was to uncover and critically examine hidden assumptions that underpin the findings of nurses' unethical conduct arising from inquiries conducted by the Nurses Tribunal in New South Wales. This was a qualitative study located within a post-structural theoretical framework. Transcripts of five inquiries conducted between 1998 and 2003 were analysed using critical discourse analysis. The findings revealed two dominant discourses that were drawn upon in the inquiries to construct nurses' conduct as unethical. These were discourses of trust and accountability. The way the nurses were spoken about during the inquiries was shaped by normalising judgements that were used to discursively position the nurse through narrative.
Asunto(s)
Toma de Decisiones , Disciplina Laboral , Análisis Ético , Ética en Enfermería , Mala Conducta Profesional/legislación & jurisprudencia , Competencia Clínica/normas , Teoría Ética , Testimonio de Experto , Conocimientos, Actitudes y Práctica en Salud , Humanos , Comunicación Interdisciplinaria , Nueva Gales del Sur , Evaluación en Enfermería/ética , Estudios de Casos Organizacionales , Poder Psicológico , Investigación Cualitativa , Encuestas y Cuestionarios , ConfianzaRESUMEN
Research Objective: The aim of this article is to report a study that explores how spirituality is understood to be represented in the current Australian Nursing and Midwifery Board of Australia (NMBA) Registered Nurse (RN) standards for practice. Research Design: Fairclough's approach to critical discourse analysis was applied in the examination of participant interview texts for the language used in relation to spirituality as well as power mechanisms which influenced the way the participants viewed spirituality's representation in the RN Standards for Practice. Participants: Three members of the RN Standards for Practice research and development team. Results: Findings indicate three discourses shaped the way participants viewed how spirituality is presently represented in the RN Standards for Practice. Discourses are (1) spirituality as part of holistic care, (2) spirituality as part of person-centered care, and (3) the professionalization of nursing. Conclusions: Participant interviews revealed these discourses exerted power over how spirituality was represented within the RN Standards for Practice. This has implications for the inclusion of spirituality in the practice standards and the practice of spiritual care.
Asunto(s)
Terapias Espirituales , Espiritualidad , Australia , HumanosRESUMEN
BACKGROUND: In Australia the majority of homebirths are attended by privately practising midwives (PPMs). In recent years PPMs have been increasingly reported to the Australian Health Practitioner Regulation Agency (AHPRA) mostly by other health professionals. PURPOSE: to explore the experiences of PPMs in Australia who have been reported to the AHPRA. METHODS: A qualitative interpretive approach, employing in-depth interviews with eight PPMs was undertaken and analysed using thematic analysis. A feminist theoretical framework was used to underpin the research. RESULTS: The majority of reports made to AHPRA occurred when midwives supported women who chose care considered outside the recommended Australian College of Midwives (ACM) Consultation and Referral Guidelines. During data analysis an overarching theme emerged, "Caught between women and the system", which described the participants' feelings of working as a PPM in Australia. There were six themes and several sub-themes: The suppression of midwifery, A flawed system, Lack of support, Devastation on so many levels, Making changes in the aftermath and Walking a tight rope forever. The findings from this study reveal that midwives who are under investigation suffer from emotional and psychological distress. Understanding the effects of the process of investigation is important to improve the quality of professional and personal support available to PPMs who are reported to AHPRA and to streamline processes. CONCLUSION: It is becoming increasingly difficult for PPMs to support the wishes and needs of individual women and also meet the requirements of the regulators, as well as the increasingly risk averse health service.
Asunto(s)
Parto Domiciliario , Partería/normas , Enfermeras Obstetrices/psicología , Pautas de la Práctica en Enfermería/normas , Práctica Privada/normas , Adulto , Australia , Femenino , Derechos Humanos , Humanos , Entrevistas como Asunto , Embarazo , Investigación Cualitativa , Riesgo , Derechos de la MujerRESUMEN
Aims: To discover how nurses understand spirituality and spiritual care and what affects nurses' understanding of these terms. Method: A literature search was conducted in CINAHL Plus, MEDLINE, and Google Scholar for research articles dated between 2010 and 2018 that were published in English. Using the Critical Appraisal Skills Program checklist for systematic reviews, nine articles met the inclusion criteria for this review. Most of these articles reported quantitative studies. Results: Although nurses recognize the importance of spirituality and spiritual care in nursing and have ascribed a diversity of meanings, there remains some confusion about what these terms mean. Several influences have been identified as shaping nurses understanding of spirituality and spiritual care, including education, nurses' own spirituality or religious beliefs, age, years of clinical experience, and place of employment. Conclusions: This review identifies the need for further studies using qualitative approaches to investigate how nurses' construct their understanding of spirituality and spiritual care and the dominant discourses nurses draw from to inform their understanding using qualitative approaches. Relevance to Clinical Practice: The insights gained by this review may be of value to nurse educators, managers, and policy makers in nursing education and the development of policies and practice guidelines.
Asunto(s)
Comprensión , Enfermeras y Enfermeros/psicología , Terapias Espirituales/métodos , Espiritualidad , Humanos , Enfermeras y Enfermeros/normas , Enfermeras y Enfermeros/tendencias , Terapias Espirituales/psicologíaRESUMEN
Ataxia telangiectasia mutated (ATM) is a PI3-kinase-like kinase (PIKK) associated with DNA double-strand break (DSB) repair and cell cycle control. We have previously reported comparable efficiencies of DSB repair in nuclear extracts from both ATM deficient (A-T) and control (ATM+) cells; however, the repair products from the A-T nuclear extracts contained deletions encompassing longer stretches of DNA compared to controls. These deletions appeared to result from end-joining at sites of microhomology. These data suggest that ATM hinders error-prone repair pathways that depend on degradation of DNA ends at a break. Such degradation may account for the longer deletions we formerly observed in A-T cell extracts. To address this possibility we assessed the degradation of DNA duplex substrates in A-T and control nuclear extracts under DSB repair conditions. We observed a marked shift in signal intensity from full-length products to shorter products in A-T nuclear extracts, and addition of purified ATM to A-T nuclear extracts restored full-length product detection. This repression of degradation by ATM was both ATP-dependent and inhibited by the PIKK inhibitors wortmannin and caffeine. Addition of pre-phosphorylated ATM to an A-T nuclear extract in the presence of PIKK inhibitors was insufficient in repressing degradation, indicating that kinase activities are required. These results demonstrate a role for ATM in preventing the degradation of DNA ends possibly through repressing nucleases implicated in microhomology-mediated end-joining.
Asunto(s)
Adenosina Trifosfato/farmacología , Ataxia Telangiectasia/genética , Proteínas de Ciclo Celular/fisiología , Núcleo Celular/metabolismo , Daño del ADN , Proteínas de Unión al ADN/fisiología , Proteínas Serina-Treonina Quinasas/fisiología , Proteínas Supresoras de Tumor/fisiología , Androstadienos/farmacología , Ataxia Telangiectasia/patología , Proteínas de la Ataxia Telangiectasia Mutada , Western Blotting , Cafeína/farmacología , Células Cultivadas , Fibroblastos/citología , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Humanos , Immunoblotting , Pulmón/citología , Pulmón/efectos de los fármacos , Pulmón/metabolismo , Fosforilación , WortmaninaRESUMEN
BACKGROUND: Regional and remote areas are often disadvantaged in terms of access to palliative care services. The impact of reduced access to services on people living in regional or remote areas of Australia is poorly understood. OBJECTIVE: Identify and examine current literature relating to the palliative care experiences of adults living in regional and remote areas of Australia. METHODS: CINAHL, Medline, PubMed, Cochrane Review Library and grey literature were searched using a combination of keywords. A thematic analysis was applied. RESULTS: Thirteen articles were included in the final review. Poor access, relocation and hardship were identified as issues affecting participants. CONCLUSION: Limited literature was available addressing the palliative care experiences of adults living in regional and remote areas of Australia. To identify and address any inequities in palliative care provision and access, the experiences of palliative care patients living outside major cities need to be examined.
Asunto(s)
Accesibilidad a los Servicios de Salud/organización & administración , Cuidados Paliativos/organización & administración , Servicios de Salud Rural/organización & administración , Adulto , Anciano , Anciano de 80 o más Años , Australia , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Experiments with the supF20 mutagenesis system demonstrate that extracts from Bloom's syndrome (BS) cells are unable to use microhomology elements within the supF20 gene to restore supF function after the induction of a double-strand break (DSB). Additional experiments with the pUC18 mutagenesis system demonstrate that although the efficiency and fidelity of DSB repair by BS extracts are comparable with those of normal extracts when ligatable ends are present, a significant 5-fold increase in mutation rate with BS extracts is observed when terminal phosphates are removed from the DNA substrate that needs repair. Mutant plasmids recovered after DSB repair by BS extracts contain smaller deletions within the lacZalpha gene not commonly recovered from normal extracts. This work demonstrates that BS cells, lacking the BLM helicase, process DSBs differently than normal cells and strongly suggests a role for the BLM helicase in aligning microhomology elements during recombinational events in DSB repair.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , ADN Helicasas/metabolismo , Reparación del ADN/fisiología , Adenosina Trifosfatasas/genética , Secuencia de Bases , Síndrome de Bloom/enzimología , Línea Celular Transformada , Sistema Libre de Células , ADN Helicasas/genética , Reparación del ADN/genética , Femenino , Eliminación de Gen , Genes Supresores , Humanos , Datos de Secuencia Molecular , Mutagénesis , Plásmidos/genética , ARN de Transferencia/genética , RecQ HelicasasRESUMEN
The Src family kinases Lck and Fyn play an important role in T cell development and function. We have synthesized a novel small molecule, A-420983, which inhibits Lck and Fyn, as well as other Src family kinases, but has selectivity with respect to non-Src family kinases. A-420983 completely inhibited antigen-stimulated production of IFN-gamma and IL-4 by mouse Th1 and Th2 cells, respectively. Antigen-induced T cell proliferation was also blocked by treatment with A-420983. In contrast, IL-15-induced proliferation was unaffected by A-420983, suggesting that TCR-independent pathways of T cell activation were not impaired. When mice were dosed orally, A-420983 inhibited TCR-mediated c-jun and ZAP-70 phosphorylation in CD4+ T cells and suppressed the disease course of established EAE. Treatment with A-420983 for 7 days resulted in a block in thymocyte development at the CD4- CD8- stage, consistent with inhibition of Lck and Fyn in vivo. These results demonstrate that a small molecule inhibitor of Lck and Fyn can block TCR-induced T cell activation in vitro and in vivo. Furthermore, CNS demyelination mediated by activated encephalitogenic CD4+ T cells is dependent upon the kinase activity of these Src family members. We conclude that inhibition of Src family kinases may represent a promising strategy for the treatment of T cell-mediated disorders.
Asunto(s)
Linfocitos T CD4-Positivos/efectos de los fármacos , Activación de Linfocitos/efectos de los fármacos , Pirazoles/farmacología , Pirimidinas/farmacología , Familia-src Quinasas/antagonistas & inhibidores , Animales , Línea Celular , Proliferación Celular/efectos de los fármacos , Femenino , Ratones , Ratones Endogámicos , Timo/citología , Timo/efectos de los fármacosRESUMEN
Although tobacco use is the leading contributor to death and disability in the United States, allied health professionals often lack knowledge of smoking cessation techniques. The objective of this study was to identify the extent to which undergraduate dietetics programs (referred to as didactic programs in dietetics [DPD]) teach about tobacco and smoking cessation interventions and also DPD directors' opinions regarding tobacco and smoking cessation in dietetics education. All DPD directors in the United States (n=231) were sent a questionnaire to assess programs' and directors' demographics, courses that included tobacco and smoking cessation education, and directors' opinions pertaining to tobacco and smoking cessation education. The response rate was 49% (n=113). On average, DPD directors did not agree that tobacco and smoking cessation education should be a formal part of undergraduate dietetics programs and that it is not as important as other content areas required of dietetics students. Just 37% of directors believed that a dietitian's job responsibility included educating patients on smoking cessation. Only 7% of DPD directors had formal education on smoking cessation and tobacco use, but 53% had formal education on behavior modification. More than half of DPD programs (56%) did not offer any courses that provided tobacco and smoking cessation education. These results indicate that most undergraduate dietetics programs do not incorporate tobacco and smoking cessation education in their curricula. Dietetics and other allied health educators could consider including smoking cessation education in their curricula to ensure that future health professionals can contribute to Healthy People 2010 objectives related to smoking cessation.
Asunto(s)
Dietética/educación , Educación Profesional/organización & administración , Cese del Hábito de Fumar , Tabaquismo/terapia , Terapia Conductista , HumanosRESUMEN
BACKGROUND: Worldwide, there is a growing reliance on sessional teachers in universities. This trend is reflected in an undergraduate nursing program in a large Australian metropolitan university where a significant proportion of contact hours is staffed by sessional teachers, yet little is known about what type of support is needed for sessional teachers to optimise their capacity to contribute to the academic program. OBJECTIVES: To describe the experiences of sessional teachers in a Bachelor of Nursing program in an Australian university. DESIGN: This is an exploratory qualitative study; fifteen sessional teachers were interviewed using semi-structured questions to explore their experiences of teaching. SETTING: This study was conducted in a large metropolitan school of nursing located on three sites. PARTICIPANTS: A purposive sample of 15 sessional teachers was interviewed for this study. METHODS: Semi-structured interviews were conducted face to face. Thematic analysis was used to identify major themes in the interview data and collaborative analysis was undertaken to ensure rigour. RESULTS: Findings revealed that sessional teachers enjoyed teaching, were committed to their role and viewed their clinical currency as a valuable asset for teaching. However, participants also spoke about wanting a sense of belonging to the School, with most feeling they were "outsiders". Areas identified for improvement included system and process issues, micro teaching and assessment skills, classroom management and timely access to resources. CONCLUSION: There is a need to improve sessional teachers' sense of belonging and to provide an inclusive structure and culture to optimise their capacity to contribute to the academic program.
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Docentes de Enfermería/provisión & distribución , Competencia Profesional , Actitud del Personal de Salud , Australia , Bachillerato en Enfermería , Femenino , Humanos , Entrevistas como Asunto , Investigación Cualitativa , Desarrollo de PersonalRESUMEN
BACKGROUND: Nursing students with English as an additional language (EAL) may underperform academically. The post-enrolment English language assessment (PELA) is used in literacy support, but its predictive validity in identifying those at risk of underperformance remains unknown. OBJECTIVES: To validate a PELA, as a predictor of academic performance. DESIGN: Prospective survey design. SETTING: The study was conducted at a university located in culturally and linguistically diverse areas of western Sydney, Australia. PARTICIPANTS: Commencing undergraduate nursing students who were Australian-born (n=1323, 49.6%) and born outside of Australia (n=1346, 50.4%) were recruited for this study. The 2669 (67% of 3957) participants provided consent and completed a first year nursing unit that focussed on developing literacy skills. METHOD: Between 2010 and 2013, commencing students completed the PELA and English language acculturation scale (ELAS), a previously validated instrument. The grading levels of the PELA tool were: Level 1 (proficient), Level 2 (borderline), and Level 3 (poor, and requiring additional support). RESULTS: Participants with a PELA Level 2 or 3 were more likely to be: a) non-Australian-born (χ(2): 520.6, df: 2, p<0.001); b) spoke a language other than English at home (χ(2): 490.2, df: 2, p<0.001); and c) an international student (χ(2): 225.6, df: 2, p<0.001). There was an inverse relationship between participants' ELAS scores and PELA levels (r=-0.52, p<0.001), and those graded as 'proficient' with a PELA Level 1 were more likely to obtain higher scores in their: i) unit essay assessment (χ(2): 40.2, df: 2, p<0.001); ii) final unit mark (χ(2): 218.6, df: 2, p<0.001), and attain a higher GPA (χ(2): 100.8, df: 2, p<0.001). CONCLUSION: The PELA is a useful screening tool in identifying commencing nursing students who are at risk of academic underachievement.
Asunto(s)
Bachillerato en Enfermería , Alfabetización , Multilingüismo , Estudiantes de Enfermería , Aculturación , Adolescente , Adulto , Anciano , Australia , Evaluación Educacional , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Adulto JovenRESUMEN
Nuclear substructures associated with apoptosis in HeLa cells have been examined using light-microscopic morphometry, trichrome staining, spectral imaging and transmission electron microscopy. This detailed analysis reveals several sites where alterations in the normal cellular ultrastructure occur during apoptotic progression. To correlate these ultrastructural changes with the underlying molecular processes, we have characterized and quantified apoptotic cell morphology with and without inhibition of two caspases, which are key effectors of the apoptotic program. Using this analysis, early apoptotic events included: (a) the segregation of nucleolar components, a diminished granular component, and a reduction in number but increase in size of fibrillar centers, (b) an increase in the number of cytoplasmic ribosomes and (c) a very minimal increase in the amount of peripherally condensed DNA. Apoptosis progressed with: (a) an increase in the number of perichromatin granules and perichromatin fibrils, (b) a reduction in number of interchromatin granule centers concomitant with an increase in their size, (c) partial digestion and circumferential condensation of the DNA at the nuclear membrane and (d) rounding of the cytoplasm with an increase in organellar density and shrinkage in cell size. Endstage apoptotic cells showed: (a) one (or two) very large pools of incompletely digested DNA, (b) one (or two) very large interchromatin granule centers, (c) an increased number of perichromatin granules which were distanced from DNA and often closely apposed to the nucleolus, (d) formation of unusually condensed, highly coiled perinucleolar bodies and (e) blebbing of highly dense cytoplasm. In HeLa cells treated with UV and inhibitors of caspase 1 and 3, the length of time from early apoptosis to the formation of apoptotic bodies was greatly extended. Inhibiting caspase activity: (a) prevented the pooling of DNA, (b) retarded the formation of large interchromatin granule centers, (c) increased the number of perichromatin granules, (d) produced disassembly of the nucleolus, (e) prevented the formation of highly coiled perinucleolar bodies, and (f) caused vacuolization in the cell center and a unipolar blebbing of the cytoplasm. Spectral imaging in conjunction with serial section electron microscopy confirmed the staining specificities of the condensed DNA, of the large condensed interchromatin granule centers, and of the nucleoli. The results indicate that the interface between the components of the chromatin domain and the interchromatin space is a critical site of caspase activity in apoptosis, and precedes other events such as internucleosomal DNA degradation.
Asunto(s)
Apoptosis/efectos de la radiación , Compuestos Azo/metabolismo , Eosina Amarillenta-(YS)/metabolismo , Células HeLa/efectos de la radiación , Células HeLa/ultraestructura , Verde de Metilo/metabolismo , Rayos Ultravioleta , Humanos , Microscopía Electrónica/métodos , Análisis Espectral/métodosRESUMEN
The tumor suppressor breast cancer susceptibility protein 1 (BRCA1) protects our cells from genomic instability in part by facilitating the efficient repair of DNA double-strand breaks (DSBs). BRCA1 promotes the error-free repair of DSBs through homologous recombination and is also implicated in the regulation of nonhomologous end joining (NHEJ) repair fidelity. Here, we investigate the role of BRCA1 in NHEJ repair mutagenesis following a DSB. We examined the frequency of microhomology-mediated end joining (MMEJ) and the fidelity of DSB repair relative to BRCA1 protein levels in both control and tumorigenic breast epithelial cells. In addition to altered BRCA1 protein levels, we tested the effects of cellular exposure to mirin, an inhibitor of meiotic recombination enzyme 11 (Mre11) 3'-5'-exonuclease activity. Knockdown or loss of BRCA1 protein resulted in an increased frequency of overall plasmid DNA mutagenesis and MMEJ following a DSB. Inhibition of Mre11-exonuclease activity with mirin significantly decreased the occurrence of MMEJ, but did not considerably affect the overall mutagenic frequency of plasmid DSB repair. The results suggest that BRCA1 protects DNA from mutagenesis during nonhomologous DSB repair in plasmid-based assays. The increased frequency of DSB mutagenesis and MMEJ repair in the absence of BRCA1 suggests a potential mechanism for carcinogenesis.
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Proteína BRCA1/metabolismo , Mama/citología , Roturas del ADN de Doble Cadena , Reparación del ADN/fisiología , ADN/genética , Células Epiteliales/metabolismo , Plásmidos/genética , Proteína BRCA1/genética , Línea Celular , Reparación del ADN/genética , Femenino , Humanos , ImmunoblottingAsunto(s)
Accesibilidad a los Servicios de Salud/organización & administración , Cuidados Paliativos/organización & administración , Enfermería Rural/organización & administración , Adulto , Anciano , Anciano de 80 o más Años , Investigación en Enfermería Clínica , Humanos , Persona de Mediana Edad , Nueva Gales del Sur , Población RuralRESUMEN
The human disorder ataxia telangiectasia (AT), which is characterized by genetic instability and neurodegeneration, results from mutation of the ataxia telangiectasia mutated (ATM) kinase. The loss of ATM leads to cell cycle checkpoint deficiencies and other DNA damage signaling defects that do not fully explain all pathologies associated with A-T including neuronal loss. In addressing this enigma, we find here that ATM suppresses DNA double-strand break (DSB) repair by microhomology-mediated end joining (MMEJ). We show that ATM repression of DNA end-degradation is dependent on its kinase activities and that Mre11 is the major nuclease behind increased DNA end-degradation and MMEJ repair in A-T. Assessment of MMEJ by an in vivo reporter assay system reveals decreased levels of MMEJ repair in Mre11-knockdown cells and in cells treated with Mre11-nuclease inhibitor mirin. Structure-based modeling of Mre11 dimer engaging DNA ends suggests the 5' ends of a bridged DSB are juxtaposed such that DNA unwinding and 3'-5' exonuclease activities may collaborate to facilitate simultaneous pairing of extended 5' termini and exonucleolytic degradation of the 3' ends in MMEJ. Together our results provide an integrated understanding of ATM and Mre11 in MMEJ: ATM has a critical regulatory function in controlling DNA end-stability and error-prone DSB repair and Mre11 nuclease plays a major role in initiating MMEJ in mammalian cells. These functions of ATM and Mre11 could be particularly important in neuronal cells, which are post-mitotic and therefore depend on mechanisms other than homologous recombination between sister chromatids to repair DSBs.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Roturas del ADN de Doble Cadena , Reparación del ADN , Proteínas de Unión al ADN/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Proteínas de la Ataxia Telangiectasia Mutada , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/genética , Humanos , Proteína Homóloga de MRE11 , Pirimidinonas/farmacología , Interferencia de ARN , Tionas/farmacologíaAsunto(s)
Dietética/métodos , Evaluación Nutricional , Fotograbar/métodos , Adulto , Dietética/instrumentación , Humanos , MasculinoRESUMEN
In response to DNA damage, cells activate a complex protein network designed to sustain genomic integrity. Many of the proteins involved in the network form discrete repair foci, the composition of which is determined by the specific type of damage. Replication protein A (RPA) and the Mre11/Rad50/Nbs1 (MRN) complex both participate in foci and co-localize at certain types of lesions. Following etoposide (ETOP) treatment, cells form foci containing either RPA or the MRN complex, but not both. To investigate this preferential foci formation, we used cell cycle synchronization experimentation. We demonstrate that cells in S phase contain RPA foci but lack phospho-Nbs1 foci. This is consistent with RPA's role in homologous recombination repair of DNA double-strand breaks (DSBs), the predominant form of repair during S phase. Cells synchronized at G0/G1 phase contain phospho-Nbs1 foci, consistent with the MRN complex involvement in non-homologous end joining, the predominant form of repair in G1 phase. Treatment of cells with the proteasome inhibitor MG132 dramatically reduced the percentage of cells forming phospho-Nbs1 foci but did not alter the percentage of cells containing RPA or phospho-RPA foci. ETOP induced similar amounts of damage in all phases of the cell cycle as measured by the comet assay. These data suggest that in response to DNA DSBs, cell cycle-preferred repair pathways differentially engage RPA and the MRN complex in repair foci.