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1.
bioRxiv ; 2023 Dec 20.
Artículo en Inglés | MEDLINE | ID: mdl-37503055

RESUMEN

Asymmetric cell division (ACD) allows daughter cells of a polarized mother to acquire different developmental fates. In C. elegans , the Wnt/ß-catenin Asymmetry (WßA) pathway oversees many embryonic and larval ACDs; here, a Wnt gradient induces an asymmetric distribution of Wnt signaling components within the dividing mother cell. One terminal nuclear effector of the WßA pathway is the transcriptional activator SYS-1/ß-catenin. SYS-1 is sequentially negatively regulated during ACD; first by centrosomal regulation and subsequent proteasomal degradation and second by asymmetric activity of the ß-catenin "destruction complex" in one of the two daughter cells, which decreases SYS-1 levels in the absence of WßA signaling. However, the extent to which mother cell SYS-1 influences cell fate decisions of the daughters is unknown. Here, we quantify inherited SYS-1 in the differentiating daughter cells and the role of SYS-1 inheritance in Wnt-directed ACD. Photobleaching experiments demonstrate the GFP::SYS-1 present in daughter cell nuclei is comprised of inherited and de novo translated SYS-1 pools. We used a photoconvertible DENDRA2::SYS-1, to directly observe the dynamics of inherited SYS-1. Photoconversion during mitosis reveals that SYS-1 clearance at the centrosome preferentially degrades older SYS-1, and this accumulation is regulated via dynein trafficking. Photoconversion of the EMS cell during Wnt-driven ACD shows daughter cell inheritance of mother cell SYS-1. Additionally, loss of centrosomal SYS-1 increased inherited SYS-1 and, surprisingly, loss of centrosomal SYS-1 also resulted in increased levels of de novo SYS-1 in both EMS daughter cells. Lastly, we show that daughter cell negative regulation of SYS-1 via the destruction complex member APR-1/APC is key to limit both the de novo and the inherited SYS-1 pools in both the E and the MS cells. We conclude that regulation of both inherited and newly translated SYS-1 via centrosomal processing in the mother cell and daughter cell regulation via Wnt signaling are critical to maintain sister SYS-1 asymmetry during ACD.

2.
PLoS One ; 18(2): e0279230, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36848352

RESUMEN

BACKGROUND: Community-based health interventions are increasingly viewed as models of care that can bridge healthcare gaps experienced by underserved communities in the United States (US). With this study, we sought to assess the impact of such interventions, as implemented through the US HealthRise program, on hypertension and diabetes among underserved communities in Hennepin, Ramsey, and Rice Counties, Minnesota. METHODS AND FINDINGS: HealthRise patient data from June 2016 to October 2018 were assessed relative to comparison patients in a difference-in-difference analysis, quantifying program impact on reducing systolic blood pressure (SBP) and hemoglobin A1c, as well as meeting clinical targets (< 140 mmHg for hypertension, < 8% Al1c for diabetes), beyond routine care. For hypertension, HealthRise participation was associated with SBP reductions in Rice (6.9 mmHg [95% confidence interval: 0.9-12.9]) and higher clinical target achievement in Hennepin (27.3 percentage-points [9.8-44.9]) and Rice (17.1 percentage-points [0.9 to 33.3]). For diabetes, HealthRise was associated with A1c decreases in Ramsey (1.3 [0.4-2.2]). Qualitative data showed the value of home visits alongside clinic-based services; however, challenges remained, including community health worker retention and program sustainability. CONCLUSIONS: HealthRise participation had positive effects on improving hypertension and diabetes outcomes at some sites. While community-based health programs can help bridge healthcare gaps, they alone cannot fully address structural inequalities experienced by many underserved communities.


Asunto(s)
Diabetes Mellitus , Hipertensión , Hipotensión , Humanos , Agentes Comunitarios de Salud , Diabetes Mellitus/terapia , Hemoglobina Glucada , Hipertensión/terapia , Minnesota/epidemiología , Servicios de Salud Comunitaria
3.
Mol Biol Cell ; 33(5): ar42, 2022 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-35196020

RESUMEN

The Caenorhabditis elegans Wnt/ß-catenin asymmetry (WßA) pathway utilizes asymmetric regulation of SYS-1/ß-catenin and POP-1/TCF coactivators. WßA differentially regulates gene expression during cell fate decisions, specifically by asymmetric localization of determinants in mother cells to produce daughters biased toward their appropriate cell fate. Despite the induction of asymmetry, ß-catenin localizes symmetrically to mitotic centrosomes in both mammals and C. elegans. Owing to the mitosis-specific localization of SYS-1 to centrosomes and enrichment of SYS-1 at kinetochore microtubules when SYS-1 centrosomal loading is disrupted, we investigated active trafficking in SYS-1 centrosomal localization. Here, we demonstrate that trafficking by microtubule motor dynein is required to maintain SYS-1 centrosomal enrichment, by dynein RNA interference (RNAi)-mediated decreases in SYS-1 centrosomal enrichment and by temperature-sensitive allele of the dynein heavy chain. Conversely, we observe depletion of microtubules by nocodazole treatment or RNAi of dynein-proteasome adapter ECPS-1 exhibits increased centrosomal enrichment of SYS-1. Moreover, disruptions to SYS-1 or negative regulator microtubule trafficking are sufficient to significantly exacerbate SYS-1 dependent cell fate misspecifications. We propose a model whereby retrograde microtubule-mediated trafficking enables SYS-1 enrichment at centrosomes, enhancing its eventual proteasomal degradation. These studies support the link between centrosomal localization and enhancement of proteasomal degradation, particularly for proteins not generally considered "centrosomal."


Asunto(s)
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Animales , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Centrosoma/metabolismo , Dineínas/metabolismo , Mamíferos/metabolismo , Microtúbulos/metabolismo , Factores de Transcripción/metabolismo , beta Catenina/metabolismo
4.
J Mol Biol ; 433(21): 167215, 2021 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-34450138

RESUMEN

Protein aggregation is a feature of numerous neurodegenerative diseases. However, regulated, often reversible, formation of protein aggregates, also known as condensates, helps control a wide range of cellular activities including stress response, gene expression, memory, cell development and differentiation. This review presents examples of aggregates found in biological systems, how they are used, and cellular strategies that control aggregation and disaggregation. We include features of the aggregating proteins themselves, environmental factors, co-aggregates, post-translational modifications and well-known aggregation-directed activities that influence their formation, material state, stability and dissolution. We highlight the emerging roles of biomolecular condensates in early animal development, and disaggregation processing proteins that have recently been shown to play key roles in gametogenesis and embryogenesis.


Asunto(s)
Desarrollo Embrionario/genética , Gametogénesis/genética , Enfermedades Neurodegenerativas/genética , Agregado de Proteínas/genética , Agregación Patológica de Proteínas/genética , Procesamiento Proteico-Postraduccional , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Animales , Diferenciación Celular , Proliferación Celular , Células Eucariotas/citología , Células Eucariotas/metabolismo , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Humanos , Memoria/fisiología , Enfermedades Neurodegenerativas/metabolismo , Enfermedades Neurodegenerativas/patología , Proteínas de Complejo Poro Nuclear/genética , Proteínas de Complejo Poro Nuclear/metabolismo , Agregación Patológica de Proteínas/metabolismo , Agregación Patológica de Proteínas/patología , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Transducción de Señal
6.
Mol Biol Cell ; 31(17): 1951-1961, 2020 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-32583737

RESUMEN

The Wnt/ß-catenin signaling pathway is central to metazoan development and routinely dysregulated in cancer. Wnt/ß-catenin signaling initiates transcriptional reprogramming upon stabilization of the transcription factor ß-catenin, which is otherwise posttranslationally processed by a destruction complex and degraded by the proteasome. Since various Wnt signaling components are enriched at centrosomes, we examined the functional contribution of centrosomes to Wnt signaling, ß-catenin regulation, and posttranslational modifications. In HEK293 cells depleted of centrosomes we find that ß-catenin synthesis and degradation rates are unaffected but that the normal accumulation of ß-catenin in response to Wnt signaling is attenuated. This is due to accumulation of a novel high-molecular-weight form of phosphorylated ß-catenin that is constitutively degraded in the absence of Wnt. Wnt signaling operates by inhibiting the destruction complex and thereby reducing destruction complex-phosphorylated ß-catenin, but high-molecular-weight ß-catenin is unexpectedly increased by Wnt signaling. Therefore these studies have identified a pool of ß-catenin effectively shielded from regulation by Wnt. We present a model whereby centrosomes prevent inappropriate ß-catenin modifications that antagonize normal stabilization by Wnt signals.


Asunto(s)
Centrosoma/metabolismo , Proteínas Wnt/metabolismo , beta Catenina/metabolismo , Línea Celular Tumoral , Células HEK293 , Células HeLa , Humanos , Fosforilación , Complejo de la Endopetidasa Proteasomal/metabolismo , Procesamiento Proteico-Postraduccional , Factores de Transcripción/metabolismo , Vía de Señalización Wnt
7.
BMJ Glob Health ; 5(6)2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-32503887

RESUMEN

INTRODUCTION: As non-communicable disease (NCD) burden rises worldwide, community-based programmes are a promising strategy to bridge gaps in NCD care. The HealthRise programme sought to improve hypertension and diabetes management for underserved communities in nine sites across Brazil, India, South Africa and the USA between 2016 and 2018. This study presents findings from the programme's endline evaluation. METHODS: The evaluation utilises a mixed-methods quasi-experimental design. Process indicators assess programme implementation; quantitative data examine patients' biometric measures and qualitative data characterise programme successes and challenges. Programme impact was assessed using the percentage of patients meeting blood pressure and A1c treatment targets and tracking changes in these measures over time. RESULTS: Almost 60 000 screenings, most of them in India, resulted in 1464 new hypertension and 295 new diabetes cases across sites. In Brazil, patients exhibited statistically significant reductions in blood pressure and A1c. In Shimla, India, and in South Africa, country with the shortest implementation period, there were no differences between patients served by facilities in HealthRise areas relative to comparison areas. Among participating patients with diabetes in Hennepin and Ramsey counties and hypertension patients in Hennepin County, the percentage of HealthRise patients meeting treatment targets at endline was significantly higher relative to comparison group patients. Qualitative analysis identified linking different providers, services, communities and information systems as positive HealthRise attributes. Gaps in health system capacities and sociodemographic factors, including poverty, low levels of health education and limited access to nutritious food, are remaining challenges. CONCLUSIONS: Findings from Brazil and the USA indicate that the HealthRise model has the potential to improve patient outcomes. Short implementation periods and strong emphasis on screening may have contributed to the lack of detectable differences in other sites. Community-based care cannot deliver its full potential if sociodemographic and health system barriers are not addressed in tandem.


Asunto(s)
Diabetes Mellitus , Hipertensión , Brasil/epidemiología , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/epidemiología , Diabetes Mellitus/terapia , Humanos , Hipertensión/diagnóstico , Hipertensión/epidemiología , Hipertensión/terapia , India/epidemiología , Sudáfrica/epidemiología
8.
Mol Biol Cell ; 31(13): 1324-1345, 2020 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-32320318

RESUMEN

Protein aggregation, once believed to be a harbinger and/or consequence of stress, age, and pathological conditions, is emerging as a novel concept in cellular regulation. Normal versus pathological aggregation may be distinguished by the capacity of cells to regulate the formation, modification, and dissolution of aggregates. We find that Caenorhabditis elegans aggregates are observed in large cells/blastomeres (oocytes, embryos) and in smaller, further differentiated cells (primordial germ cells), and their analysis using cell biological and genetic tools is straightforward. These observations are consistent with the hypothesis that aggregates are involved in normal development. Using cross-platform analysis in Saccharomyces cerevisiae, C. elegans, and Xenopus laevis, we present studies identifying a novel disaggregase family encoded by animal genomes and expressed embryonically. Our initial analysis of yeast Arb1/Abcf2 in disaggregation and animal ABCF proteins in embryogenesis is consistent with the possibility that members of the ABCF gene family may encode disaggregases needed for aggregate processing during the earliest stages of animal development.


Asunto(s)
Transportadoras de Casetes de Unión a ATP/metabolismo , Desarrollo Embrionario , Agregación Patológica de Proteínas , Transportadoras de Casetes de Unión a ATP/fisiología , Animales , Humanos
9.
PLoS One ; 13(3): e0192603, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29538420

RESUMEN

BACKGROUND: The HealthRise initiative seeks to implement and evaluate innovative community-based strategies for diabetes, hypertension and hypercholesterolemia along the entire continuum of care (CoC)-from awareness and diagnosis, through treatment and control. In this study, we present baseline findings from HealthRise South Africa, identifying gaps in the CoC, as well as key barriers to care for non-communicable diseases (NCDs). METHODS: This mixed-methods needs assessment utilized national household data, health facility surveys, focus group discussions, and key informant interviews in Umgungundlovu and Pixley ka Seme districts. Risk factor and disease prevalence were estimated from the South Africa National Health and Nutrition Examination Survey. Health facility surveys were conducted at 86 facilities, focusing on essential intervention, medications and standard treatment guidelines. Quantitative results are presented descriptively, and qualitative data was analyzed using a framework approach. RESULTS: 46.8% of the population in Umgungundlovu and 51.0% in Pixley ka Seme were hypertensive. Diabetes was present in 11.0% and 9.7% of the population in Umgungundlovu and Pixley ka Seme. Hypercholesterolemia was more common in Pixley ka Seme (17.3% vs. 11.1%). Women and those of Indian descent were more likely to have diabetes. More than half of the population was found to be overweight, and binge drinking, inactivity and smoking were all common. More than half of patients with hypertension were unaware of their disease status (51.6% in Pixley ka Seme and 51.3% in Umgungundlovu), while the largest gap in the diabetes CoC occurred between initiation of treatment and achieving disease control. Demand-side barriers included lack of transportation, concerns about confidentiality, perceived discrimination and long wait times. Supply-side barriers included limited availability of testing equipment, inadequate staffing, and pharmaceutical stock outs. CONCLUSION: In this baseline assessment of two South African health districts we found high rates of undiagnosed hypercholesterolemia and hypertension, and poor control of hypercholesterolemia, hypertension, and diabetes. The HealthRise Initiative will need to address key supply- and demand-side barriers in an effort to improve important NCD outcomes.


Asunto(s)
Enfermedades Cardiovasculares/terapia , Atención a la Salud , Diabetes Mellitus/terapia , Adhesión a Directriz , Enfermedades Cardiovasculares/epidemiología , Servicios de Salud Comunitaria , Diabetes Mellitus/epidemiología , Femenino , Humanos , Masculino , Guías de Práctica Clínica como Asunto , Sudáfrica/epidemiología
10.
Heart ; 104(1): 67-72, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-28663360

RESUMEN

OBJECTIVE: To inform interventions targeted towards reducing mortality from acute myocardial infarction (AMI) and sudden cardiac arrest in three megacities in China and India, a baseline assessment of public knowledge, attitudes and practices was performed. METHODS: A household survey, supplemented by focus group and individual interviews, was used to assess public understanding of cardiovascular disease (CVD) risk factors, AMI symptoms, cardiopulmonary resuscitation (CPR) and automated external defibrillators (AEDs). Additionally, information was collected on emergency service utilisation and associated barriers to care. RESULTS: 5456 household surveys were completed. Hypertension was most commonly recognised among CVD risk factors in Beijing and Shanghai (68% and 67%, respectively), while behavioural risk factors were most commonly identified in Bangalore (smoking 91%; excessive alcohol consumption 64%). Chest pain/discomfort was reported by at least 60% of respondents in all cities as a symptom of AMI, but 21% of individuals in Bangalore could not name a single symptom. In Beijing, Shanghai and Bangalore, 26%, 15% and 3% of respondents were trained in CPR, respectively. Less than one-quarter of participants in all cities recognised an AED. Finally, emergency service utilisation rates were low, and many individuals expressed concern about the quality of prehospital care. CONCLUSIONS: Overall, we found low to modest knowledge of CVD risk factors and AMI symptoms, infrequent CPR training and little understanding of AEDs. Interventions will need to focus on basic principles of CVD and its complications in order for patients to receive timely and appropriate care for acute cardiac events.


Asunto(s)
Reanimación Cardiopulmonar/métodos , Conocimientos, Actitudes y Práctica en Salud , Paro Cardíaco Extrahospitalario/terapia , Vigilancia de la Población , Sistema de Registros , Población Urbana , Adolescente , Adulto , Anciano , Reanimación Cardiopulmonar/educación , China/epidemiología , Servicios Médicos de Urgencia , Femenino , Humanos , Incidencia , India/epidemiología , Masculino , Persona de Mediana Edad , Paro Cardíaco Extrahospitalario/epidemiología , Tasa de Supervivencia/tendencias , Adulto Joven
11.
BMC Health Serv Res ; 17(1): 846, 2017 12 27.
Artículo en Inglés | MEDLINE | ID: mdl-29282052

RESUMEN

BACKGROUND: Non-communicable diseases (NCDs) represent the largest, and fastest growing, burden of disease in India. This study aimed to quantify levels of diagnosis, treatment, and control among hypertensive and diabetic patients, and to describe demand- and supply-side barriers to hypertension and diabetes diagnosis and care in two Indian districts, Shimla and Udaipur. METHODS: We conducted household and health facility surveys, as well as qualitative focus group discussions and interviews. The household survey randomly sampled individuals aged 15 and above in rural and urban areas in both districts. The survey included questions on NCD knowledge, history, and risk factors. Blood pressure, weight, height, and blood glucose measurements were obtained. The health facility survey was administered in 48 health care facilities, focusing on NCD diagnosis and treatment capacity, including staffing, equipment, and pharmaceuticals. Qualitative data was collected through semi-structured key informant interviews with health professionals and public health officials, as well as focus groups with patients and community members. RESULTS: Among 7181 individuals, 32% either reported a history of hypertension or were found to have a systolic blood pressure ≥ 140 mmHg and/or diastolic ≥90 mmHg. Only 26% of those found to have elevated blood pressure reported a prior diagnosis, and just 42% of individuals with a prior diagnosis of hypertension were found to be normotensive. A history of diabetes or an elevated blood sugar (Random blood glucose (RBG) ≥200 mg/dl or fasting blood glucose (FBG) ≥126 mg/dl) was noted in 7% of the population. Among those with an elevated RBG/FBG, 59% had previously received a diagnosis of diabetes. Only 60% of diabetics on treatment were measured with a RBG <200 mg/dl. Lower-level health facilities were noted to have limited capacity to measure blood glucose as well as significant gaps in the availability of first-line pharmaceuticals for both hypertension and diabetes. CONCLUSIONS: We found high rates of uncontrolled diabetes and undiagnosed and uncontrolled hypertension. Lower level health facilities were constrained by capacity to test, monitor and treat diabetes and hypertension. Interventions aimed at improving patient outcomes will need to focus on the expanding access to quality care in order to accommodate the growing demand for NCD services.


Asunto(s)
Continuidad de la Atención al Paciente/organización & administración , Diabetes Mellitus/tratamiento farmacológico , Hipertensión/tratamiento farmacológico , Garantía de la Calidad de Atención de Salud , Adolescente , Adulto , Pueblo Asiatico , Femenino , Grupos Focales , Encuestas de Atención de la Salud , Humanos , India , Entrevistas como Asunto , Masculino , Persona de Mediana Edad , Investigación Cualitativa , Adulto Joven
12.
Results Probl Cell Differ ; 61: 83-114, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28409301

RESUMEN

Asymmetric cell division is a common mode of cell differentiation during the invariant lineage of the nematode, C. elegans. Beginning at the four-cell stage, and continuing throughout embryogenesis and larval development, mother cells are polarized by Wnt ligands, causing an asymmetric inheritance of key members of a Wnt/ß-catenin signal transduction pathway termed the Wnt/ß-catenin asymmetry pathway. The resulting daughter cells are distinct at birth with one daughter cell activating Wnt target gene expression via ß-catenin activation of TCF, while the other daughter displays transcriptional repression of these target genes. Here, we seek to review the body of evidence underlying a unified model for Wnt-driven asymmetric cell division in C. elegans, identify global themes that occur during asymmetric cell division, as well as highlight tissue-specific variations. We also discuss outstanding questions that remain unanswered regarding this intriguing mode of asymmetric cell division.


Asunto(s)
División Celular Asimétrica/fisiología , Caenorhabditis elegans/fisiología , Vía de Señalización Wnt/fisiología , Animales , Proteínas de Caenorhabditis elegans/metabolismo
13.
Cell Cycle ; 15(16): 2124-2134, 2016 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-27294844

RESUMEN

The centrosome is the major microtubule-organizing center in animal cells but is dispensable for proper microtubule spindle formation in many biological contexts and is thus thought to fulfill additional functions. Recent observations suggest that the centrosome acts as a scaffold for proteasomal degradation in the cell to regulate a variety of biological processes including cell fate acquisition, cell cycle control, stress response, and cell morphogenesis. Here, we review the body of studies indicating a role for the centrosome in promoting proteasomal degradation of ubiquitin-proteasome substrates and explore the functional relevance of this system in different biological contexts. We discuss a potential role for the centrosome in coordinating local degradation of proteasomal substrates, allowing cells to achieve stringent spatiotemporal control over various signaling processes.


Asunto(s)
Centrosoma/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Ubiquitina/metabolismo , Animales , Ciclo Celular , Humanos , Modelos Biológicos
14.
J Cell Sci ; 129(5): 983-93, 2016 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-26795562

RESUMEN

The Wnt/ß-catenin signaling pathway is utilized across metazoans. However, the mechanism of signal transduction, especially dissociation of the ß-catenin destruction complex by Dishevelled proteins, remains controversial. Here, we describe the function of the Dishevelled paralogs DSH-2 and MIG-5 in the Wnt/ß-catenin asymmetry (WßA) pathway in Caenorhabditis elegans, where WßA drives asymmetric cell divisions throughout development. We find that DSH-2 and MIG-5 redundantly regulate cell fate in hypodermal seam cells. Similarly, both DSH-2 and MIG-5 are required for positive regulation of SYS-1 (a C. elegans ß-catenin), but MIG-5 has a stronger effect on the polarity of SYS-1 localization. We show that MIG-5 controls cortical APR-1 (the C. elegans APC) localization. DSH-2 and MIG-5 both regulate the localization of WRM-1 (another C. elegans ß-catenin), acting together as negative regulators of WRM-1 nuclear localization. Finally, we demonstrate that overexpression of DSH-2 or MIG-5 in seam cells leads to stabilization of SYS-1 in the anterior seam daughter, solidifying the Dishevelled proteins as positive regulators of SYS-1. Overall, we have further defined the role of Dishevelled in the WßA signaling pathway, and demonstrated that DSH-2 and MIG-5 regulate cell fate, ß-catenin nuclear levels and the polarity of ß-catenin regulation.


Asunto(s)
Proteínas de Caenorhabditis elegans/fisiología , Caenorhabditis elegans/metabolismo , Proteínas de Ciclo Celular/fisiología , Proteínas Dishevelled/fisiología , beta Catenina/metabolismo , Animales , División Celular Asimétrica , Caenorhabditis elegans/citología , Proteínas de Caenorhabditis elegans/metabolismo , Diferenciación Celular , Proteínas del Citoesqueleto/metabolismo , Estabilidad Proteica , Transporte de Proteínas , Factores de Transcripción/metabolismo , Vía de Señalización Wnt
15.
Genetics ; 201(3): 1047-60, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26358719

RESUMEN

Asymmetric cell division is critical during development, as it influences processes such as cell fate specification and cell migration. We have characterized FRK-1, a homolog of the mammalian Fer nonreceptor tyrosine kinase, and found it to be required for differentiation and maintenance of epithelial cell types, including the stem cell-like seam cells of the hypodermis. A genomic knockout of frk-1, allele ok760, results in severely uncoordinated larvae that arrest at the L1 stage and have an excess number of lateral hypodermal cells that appear to have lost asymmetry in the stem cell-like divisions of the seam cell lineage. frk-1(ok760) mutants show that there are excess lateral hypodermal cells that are abnormally shaped and smaller in size compared to wild type, a defect that could be rescued only in a manner dependent on the kinase activity of FRK-1. Additionally, we observed a significant change in the expression of heterochronic regulators in frk-1(ok760) mutants. However, frk-1(ok760) mutants do not express late, nonseam hypodermal GFP markers, suggesting the seam cells do not precociously differentiate as adult-hyp7 cells. Finally, our data also demonstrate a clear role for FRK-1 in seam cell proliferation, as eliminating FRK-1 during the L3-L4 transition results in supernumerary seam cell nuclei that are dependent on asymmetric Wnt signaling. Specifically, we observe aberrant POP-1 and WRM-1 localization that is dependent on the presence of FRK-1 and APR-1. Overall, our data suggest a requirement for FRK-1 in maintaining the identity and proliferation of seam cells primarily through an interaction with the asymmetric Wnt pathway.


Asunto(s)
División Celular Asimétrica , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Vía de Señalización Wnt , Animales , Caenorhabditis elegans/citología , Caenorhabditis elegans/embriología , Desarrollo Embrionario , Células Madre Embrionarias/citología , Técnicas de Inactivación de Genes
16.
Curr Biol ; 25(8): 1005-16, 2015 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-25819561

RESUMEN

Caenorhabditis elegans embryos rapidly diversify cell fate using a modified Wnt/ß-catenin signaling strategy to carry out serial asymmetric cell divisions (ACDs). Wnt-dependent ACDs rely on nuclear asymmetry of the transcriptional coactivator SYS-1/ß-catenin between daughter cells to differentially activate Wnt-responsive target genes. Here, we investigate how dynamic localization of SYS-1 to mitotic centrosomes influences SYS-1 inheritance in daughter cells and cell-fate outcomes after ACD. Through yeast two-hybrid screening, we identify the centrosomal protein RSA-2 as a SYS-1 binding partner and show that localization of SYS-1 to mitotic centrosomes is dependent on RSA-2. Uncoupling SYS-1 from the centrosome by RSA-2 depletion increases SYS-1 inheritance after ACD and promotes Wnt-dependent cell fate. Photobleaching experiments reveal that centrosome-bound SYS-1 turns over rapidly. Interestingly, disruption of the proteasome leads to an increased accumulation of SYS-1 at the centrosome but disrupts its dynamic turnover. We conclude that centrosomal targeting of SYS-1 promotes its degradation during asymmetric cell division. We propose a model whereby centrosome-associated SYS-1 degradation couples negative regulation with cell-division timing to facilitate SYS-1 clearance from the mother cell at the time of asymmetric division. Based on our observations of centrosomal SYS-1 dynamics, we discuss the possibility that the centrosome may coordinate various cell-cycle-dependent processes by synchronizing mitosis and protein regulation.


Asunto(s)
División Celular Asimétrica/fisiología , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/citología , Centrosoma/metabolismo , Factores de Transcripción/metabolismo , beta Catenina/metabolismo , Animales , División Celular Asimétrica/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Transducción de Señal/genética , Proteínas Wnt/metabolismo
17.
Lancet ; 384(9947): 1005-70, 2014 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-25059949

RESUMEN

BACKGROUND: The Millennium Declaration in 2000 brought special global attention to HIV, tuberculosis, and malaria through the formulation of Millennium Development Goal (MDG) 6. The Global Burden of Disease 2013 study provides a consistent and comprehensive approach to disease estimation for between 1990 and 2013, and an opportunity to assess whether accelerated progress has occured since the Millennium Declaration. METHODS: To estimate incidence and mortality for HIV, we used the UNAIDS Spectrum model appropriately modified based on a systematic review of available studies of mortality with and without antiretroviral therapy (ART). For concentrated epidemics, we calibrated Spectrum models to fit vital registration data corrected for misclassification of HIV deaths. In generalised epidemics, we minimised a loss function to select epidemic curves most consistent with prevalence data and demographic data for all-cause mortality. We analysed counterfactual scenarios for HIV to assess years of life saved through prevention of mother-to-child transmission (PMTCT) and ART. For tuberculosis, we analysed vital registration and verbal autopsy data to estimate mortality using cause of death ensemble modelling. We analysed data for corrected case-notifications, expert opinions on the case-detection rate, prevalence surveys, and estimated cause-specific mortality using Bayesian meta-regression to generate consistent trends in all parameters. We analysed malaria mortality and incidence using an updated cause of death database, a systematic analysis of verbal autopsy validation studies for malaria, and recent studies (2010-13) of incidence, drug resistance, and coverage of insecticide-treated bednets. FINDINGS: Globally in 2013, there were 1·8 million new HIV infections (95% uncertainty interval 1·7 million to 2·1 million), 29·2 million prevalent HIV cases (28·1 to 31·7), and 1·3 million HIV deaths (1·3 to 1·5). At the peak of the epidemic in 2005, HIV caused 1·7 million deaths (1·6 million to 1·9 million). Concentrated epidemics in Latin America and eastern Europe are substantially smaller than previously estimated. Through interventions including PMTCT and ART, 19·1 million life-years (16·6 million to 21·5 million) have been saved, 70·3% (65·4 to 76·1) in developing countries. From 2000 to 2011, the ratio of development assistance for health for HIV to years of life saved through intervention was US$4498 in developing countries. Including in HIV-positive individuals, all-form tuberculosis incidence was 7·5 million (7·4 million to 7·7 million), prevalence was 11·9 million (11·6 million to 12·2 million), and number of deaths was 1·4 million (1·3 million to 1·5 million) in 2013. In the same year and in only individuals who were HIV-negative, all-form tuberculosis incidence was 7·1 million (6·9 million to 7·3 million), prevalence was 11·2 million (10·8 million to 11·6 million), and number of deaths was 1·3 million (1·2 million to 1·4 million). Annualised rates of change (ARC) for incidence, prevalence, and death became negative after 2000. Tuberculosis in HIV-negative individuals disproportionately occurs in men and boys (versus women and girls); 64·0% of cases (63·6 to 64·3) and 64·7% of deaths (60·8 to 70·3). Globally, malaria cases and deaths grew rapidly from 1990 reaching a peak of 232 million cases (143 million to 387 million) in 2003 and 1·2 million deaths (1·1 million to 1·4 million) in 2004. Since 2004, child deaths from malaria in sub-Saharan Africa have decreased by 31·5% (15·7 to 44·1). Outside of Africa, malaria mortality has been steadily decreasing since 1990. INTERPRETATION: Our estimates of the number of people living with HIV are 18·7% smaller than UNAIDS's estimates in 2012. The number of people living with malaria is larger than estimated by WHO. The number of people living with HIV, tuberculosis, or malaria have all decreased since 2000. At the global level, upward trends for malaria and HIV deaths have been reversed and declines in tuberculosis deaths have accelerated. 101 countries (74 of which are developing) still have increasing HIV incidence. Substantial progress since the Millennium Declaration is an encouraging sign of the effect of global action. FUNDING: Bill & Melinda Gates Foundation.


Asunto(s)
Salud Global/tendencias , Infecciones por VIH/epidemiología , Malaria/epidemiología , Tuberculosis/epidemiología , Distribución por Edad , Epidemias/estadística & datos numéricos , Femenino , Humanos , Incidencia , Masculino , Mortalidad/tendencias , Objetivos Organizacionales , Distribución por Sexo
18.
Lancet ; 384(9947): 957-79, 2014 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-24797572

RESUMEN

BACKGROUND: Remarkable financial and political efforts have been focused on the reduction of child mortality during the past few decades. Timely measurements of levels and trends in under-5 mortality are important to assess progress towards the Millennium Development Goal 4 (MDG 4) target of reduction of child mortality by two thirds from 1990 to 2015, and to identify models of success. METHODS: We generated updated estimates of child mortality in early neonatal (age 0-6 days), late neonatal (7-28 days), postneonatal (29-364 days), childhood (1-4 years), and under-5 (0-4 years) age groups for 188 countries from 1970 to 2013, with more than 29,000 survey, census, vital registration, and sample registration datapoints. We used Gaussian process regression with adjustments for bias and non-sampling error to synthesise the data for under-5 mortality for each country, and a separate model to estimate mortality for more detailed age groups. We used explanatory mixed effects regression models to assess the association between under-5 mortality and income per person, maternal education, HIV child death rates, secular shifts, and other factors. To quantify the contribution of these different factors and birth numbers to the change in numbers of deaths in under-5 age groups from 1990 to 2013, we used Shapley decomposition. We used estimated rates of change between 2000 and 2013 to construct under-5 mortality rate scenarios out to 2030. FINDINGS: We estimated that 6·3 million (95% UI 6·0-6·6) children under-5 died in 2013, a 64% reduction from 17·6 million (17·1-18·1) in 1970. In 2013, child mortality rates ranged from 152·5 per 1000 livebirths (130·6-177·4) in Guinea-Bissau to 2·3 (1·8-2·9) per 1000 in Singapore. The annualised rates of change from 1990 to 2013 ranged from -6·8% to 0·1%. 99 of 188 countries, including 43 of 48 countries in sub-Saharan Africa, had faster decreases in child mortality during 2000-13 than during 1990-2000. In 2013, neonatal deaths accounted for 41·6% of under-5 deaths compared with 37·4% in 1990. Compared with 1990, in 2013, rising numbers of births, especially in sub-Saharan Africa, led to 1·4 million more child deaths, and rising income per person and maternal education led to 0·9 million and 2·2 million fewer deaths, respectively. Changes in secular trends led to 4·2 million fewer deaths. Unexplained factors accounted for only -1% of the change in child deaths. In 30 developing countries, decreases since 2000 have been faster than predicted attributable to income, education, and secular shift alone. INTERPRETATION: Only 27 developing countries are expected to achieve MDG 4. Decreases since 2000 in under-5 mortality rates are accelerating in many developing countries, especially in sub-Saharan Africa. The Millennium Declaration and increased development assistance for health might have been a factor in faster decreases in some developing countries. Without further accelerated progress, many countries in west and central Africa will still have high levels of under-5 mortality in 2030. FUNDING: Bill & Melinda Gates Foundation, US Agency for International Development.


Asunto(s)
Mortalidad del Niño/tendencias , Salud Global/tendencias , Mortalidad Infantil/tendencias , Preescolar , Salud Global/estadística & datos numéricos , Humanos , Lactante , Recién Nacido , Objetivos Organizacionales , Factores de Riesgo , Factores Socioeconómicos
19.
J Cell Sci ; 127(Pt 12): 2771-81, 2014 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-24762815

RESUMEN

The APC tumor suppressor regulates diverse stem cell processes including gene regulation through Wnt-ß-catenin signaling and chromosome stability through microtubule interactions, but how the disparate functions of APC are controlled is not well understood. Acting as part of a Wnt-ß-catenin pathway that controls asymmetric cell division, Caenorhabditis elegans APC, APR-1, promotes asymmetric nuclear export of the ß-catenin WRM-1 by asymmetrically stabilizing microtubules. Wnt function also depends on a second ß-catenin, SYS-1, which binds to the C. elegans TCF POP-1 to activate gene expression. Here, we show that APR-1 regulates SYS-1 levels in asymmetric stem cell division, in addition to its known role in lowering nuclear levels of WRM-1. We demonstrate that SYS-1 is also negatively regulated by the C. elegans homolog of casein kinase 1α (CKIα), KIN-19. We show that KIN-19 restricts APR-1 localization, thereby regulating nuclear WRM-1. Finally, the polarity of APR-1 cortical localization is controlled by PRY-1 (C. elegans Axin), such that PRY-1 controls the polarity of both SYS-1 and WRM-1 asymmetries. We propose a model whereby Wnt signaling, through CKIα, regulates the function of two distinct pools of APC - one APC pool negatively regulates SYS-1, whereas the second pool stabilizes microtubules and promotes WRM-1 nuclear export.


Asunto(s)
Proteína de la Poliposis Adenomatosa del Colon/fisiología , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/fisiología , Caenorhabditis elegans/citología , Proteínas del Citoesqueleto/metabolismo , Proteínas Quinasas/metabolismo , Factores de Transcripción/metabolismo , Transporte Activo de Núcleo Celular , Animales , División Celular Asimétrica , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Núcleo Celular/fisiología , Polaridad Celular , Proteínas del Citoesqueleto/genética , Microtúbulos/metabolismo , Transporte de Proteínas , Células Madre/fisiología , Factores de Transcripción/genética , Vía de Señalización Wnt
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