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3.
Development ; 139(16): 2978-87, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22764046

RESUMEN

During central nervous system development, neural progenitors are patterned to form discrete neurogenic and non-neurogenic zones. In the zebrafish hindbrain, neurogenesis is organised by Fgf20a emanating from neurons located at each segment centre that inhibits neuronal differentiation in adjacent progenitors. Here, we have identified a molecular mechanism that clusters fgf20a-expressing neurons in segment centres and uncovered a requirement for this positioning in the regulation of neurogenesis. Disruption of hindbrain boundary cell formation alters the organisation of fgf20a-expressing neurons, consistent with a role of chemorepulsion from boundaries. The semaphorins Sema3fb and Sema3gb, which are expressed by boundary cells, and their receptor Nrp2a are required for clustering of fgf20a-expressing neurons at segment centres. The dispersal of fgf20a-expressing neurons that occurs following the disruption of boundaries or of Sema3fb/Sema3gb signalling leads to reduced FGF target gene expression in progenitors and an increased number of differentiating neurons. Sema3 signalling from boundaries thus links hindbrain segmentation to the positioning of fgf20a-expressing neurons that regulates neurogenesis.


Asunto(s)
Neurogénesis/fisiología , Rombencéfalo/embriología , Pez Cebra/embriología , Animales , Secuencia de Bases , Tipificación del Cuerpo/genética , Tipificación del Cuerpo/fisiología , Cartilla de ADN/genética , Factores de Crecimiento de Fibroblastos/genética , Factores de Crecimiento de Fibroblastos/metabolismo , Regulación del Desarrollo de la Expresión Génica , Técnicas de Silenciamiento del Gen , Modelos Neurológicos , Neurogénesis/genética , Neuronas/citología , Neuronas/metabolismo , Neuropilina-2/antagonistas & inhibidores , Neuropilina-2/genética , Neuropilina-2/metabolismo , Rombencéfalo/metabolismo , Semaforinas/antagonistas & inhibidores , Semaforinas/genética , Semaforinas/metabolismo , Transducción de Señal , Pez Cebra/genética , Pez Cebra/metabolismo , Proteínas de Pez Cebra/antagonistas & inhibidores , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismo
4.
Front Med (Lausanne) ; 11: 1408636, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38846141

RESUMEN

Patient experience data (PED), provided by patients/their carers without interpretation by clinicians, directly capture what matters more to patients on their medical condition, treatment and impact of healthcare. PED can be collected through different methodologies and these need to be robust and validated for its intended use. Medicine regulators are increasingly encouraging stakeholders to generate, collect and submit PED to support both scientific advice in development programs and regulatory decisions on the approval and use of these medicines. This article reviews the existing definitions and types of PED and demonstrate the potential for use in different settings of medicines' life cycle, focusing on Patient-Reported Outcomes (PRO) and Patient Preferences (PP). Furthermore, it addresses some challenges and opportunities, alluding to important regulatory guidance that has been published, methodological aspects and digitalization, highlighting the lack of guidance as a key hurdle to achieve more systematic inclusion of PED in regulatory submissions. In addition, the article discusses opportunities at European and global level that could be implemented to leverage PED use. New digital tools that allow patients to collect PED in real time could also contribute to these advances, but it is equally important not to overlook the challenges they entail. The numerous and relevant initiatives being developed by various stakeholders in this field, including regulators, show their confidence in PED's value and create an ideal moment to address challenges and consolidate PED use across medicines' life cycle.

5.
Vaccines (Basel) ; 11(10)2023 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-37897018

RESUMEN

The COVID-19 pandemic posed challenges to communicating accurate information about vaccines because of the spread of misinformation. The European Medicines Agency (EMA) tried to reassure the public by communicating early on about the development and approval of COVID-19 vaccines. The EMA surveyed patients/consumers, healthcare professional organizations, and individual stakeholders, both at the EU level and in an Italian regional context. The objectives of the study were to see if the EMA's core information materials were informative and well-understood and which communication channels were preferred by the public. The main findings showed that individual patients/consumers generally prefer to obtain information about COVID-19 vaccines from the internet or mass media, while organizations and individual healthcare professionals prefer to obtain information from national and international health authorities. Both at EU and local levels, participants had a good understanding of the key messages from regulators and found the materials useful and relevant. However, some improvements were recommended to the visual, text, and dissemination formats, including publishing more information on safety and using a more public-friendly language. Also, it was recommended to maintain the EMA's approach of using media, stakeholder engagement, and web-based formats to communicate about COVID-19 vaccines. In conclusion, user-testing of proactive communication materials aimed to prebunk misinformation during a public health crisis helps to ensure that users understand the development and safety of novel vaccine technologies. This information can then be used as a basis for further evidence-based communication activities by regulators and public health bodies in an emergency context.

6.
Lancet Reg Health Eur ; 9: 100192, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34661185

RESUMEN

The EU Medicines Regulatory Network (EMRN), comprised of the European Medicines Agency (EMA), the medicines regulatory authorities of the Member States and the European Commission (EC), is operating amid a complex crisis that has positioned regulators centre stage due to their key role in the development, approval and safety monitoring of vaccines and treatments for COVID-19. Here we consider the EMA's and EMRN's response to the pandemic and some of the early learnings that will help reshape medicines regulation in the post COVID-19 era. We also reflect on how some of these learnings will be formally followed up under revised EU legislation to extend EMA's mandate, reinforcing its role in crisis preparedness and response.

7.
J Cell Biol ; 168(3): 453-63, 2005 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-15684034

RESUMEN

During development, dynamic remodeling of the actin cytoskeleton allows the precise placement and morphology of tissues. Morphogens such as Sonic hedgehog (Shh) and local cues such as receptor protein tyrosine phosphatases (RPTPs) mediate this process, but how they regulate the cytoskeleton is poorly understood. We previously identified Basal cell carcinoma-enriched gene 4 (BEG4)/Missing in Metastasis (MIM), a Shh-inducible, Wiskott-Aldrich homology 2 domain-containing protein that potentiates Gli transcription (Callahan, C.A., T. Ofstad, L. Horng, J.K. Wang, H.H. Zhen, P.A. Coulombe, and A.E. Oro. 2004. Genes Dev. 18:2724-2729). Here, we show that endogenous MIM is induced in a patched1-dependent manner and regulates the actin cytoskeleton. MIM functions by bundling F-actin, a process that requires self-association but is independent of G-actin binding. Cytoskeletal remodeling requires an activation domain distinct from sequences required for bundling in vitro. This domain associates with RPTPdelta and, in turn, enhances RPTPdelta membrane localization. MIM-dependent cytoskeletal changes can be inhibited using a soluble RPTPdelta-D2 domain. Our data suggest that the hedgehog-responsive gene MIM cooperates with RPTP to induce cytoskeletal changes.


Asunto(s)
Citoesqueleto/metabolismo , Proteínas de Microfilamentos/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Fosfatasas/metabolismo , Actinas/análisis , Actinas/metabolismo , Animales , Sitios de Unión/genética , Línea Celular , Línea Celular Tumoral , Extensiones de la Superficie Celular/efectos de los fármacos , Extensiones de la Superficie Celular/fisiología , Citoesqueleto/efectos de los fármacos , Células Epiteliales/química , Fibroblastos/química , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Adhesiones Focales/química , Proteína GAP-43/genética , Expresión Génica , Proteínas de Homeodominio/análisis , Inmunohistoquímica , Péptidos y Proteínas de Señalización Intracelular , Proteínas con Homeodominio LIM , Proteínas de la Membrana , Ratones , Proteínas de Microfilamentos/genética , Microscopía Fluorescente , Mutación , Proteínas de Neoplasias/genética , Proteínas del Tejido Nervioso/análisis , Células PC12 , Receptores Patched , Receptor Patched-1 , Fosfatidilinositol 4,5-Difosfato/farmacología , Unión Proteica , Transporte de Proteínas/fisiología , Proteínas Tirosina Fosfatasas/genética , Proteínas/genética , Proteínas/metabolismo , Ratas , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores , Receptores de Superficie Celular , Médula Espinal/citología , Médula Espinal/embriología , Médula Espinal/metabolismo , Fibras de Estrés/efectos de los fármacos , Fibras de Estrés/metabolismo , Fibras de Estrés/ultraestructura , Factores de Transcripción , Transfección , Técnicas del Sistema de Dos Híbridos , Vanadatos/farmacología
8.
Front Med (Lausanne) ; 7: 508, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33072771

RESUMEN

The pace of innovation is accelerating, and so medicines regulators need to actively innovate regulatory science to protect human and animal health. This requires consideration and consultation across all stakeholder groups. To this end, the European Medicines Agency worked with stakeholders to draft its Regulatory Science Strategy to 2025 and launched it for public consultation. The responses to this consultation were analyzed qualitatively, using framework analysis and quantitatively, to derive stakeholders' aggregate scores for the proposed recommendations. This paper provides a comprehensive resource of stakeholder positions on key regulatory science topics of the coming 5 years. These stakeholder positions have implications for the development and regulatory approval of both human and veterinary medicines.

9.
ESMO Open ; 3(6): e000420, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30245864

RESUMEN

With the imminent arrival of oncology biosimilars in the therapeutic paradigm, stakeholders including a clinician, specialist nurse, patient advocate, regulator and economist provide their perspective on optimising the uptake of these new agents in the treatment of cancer. A number of key messages emerge, based on the discussion that took place during a session of the European Society for Medical Oncology's Annual Congress, ESMO Madrid 2017. First, for successful integration of biosimilars into the global healthcare paradigm, informing and educating the full scope of stakeholders, including clinicians, nurses, pharmacists and patients, is primordial. Success is dependent on providing solid evidence and ensuring all voices are heard. Second, for oncology medicines, much can be learnt from the growing experience of approved biosimilars in other disease indications, with success stories for patients, their healthcare providers and healthcare budgets alike. Finally, effective sustainability of the impact on healthcare budgets and the redirection of these savings require education and transparency.

10.
Cancer Res ; 62(13): 3855-60, 2002 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-12097300

RESUMEN

Colorectal cancers from the mutator phenotype pathway display distinctive pathological features and confer a lesser aggressiveness than colorectal adenocarcinomas originated by the suppressor pathway. The goal of this work was to test whether tumors developed through the mutator pathway could show a decrease in matrix metalloproteinase (MMP) activity. We evaluated levels and activity of gelatinase A (MMP-2) and gelatinase B (MMP-9), as well as stromelysin-1 (MMP-3) expression in 101 sporadic colorectal tumors in consideration of the microsatellite instability (MSI) status of the groups. Gelatinases were analyzed by ELISA and zymography. The MMP-3 study was performed by real-time quantitative PCR. MMP-9 total levels were significantly higher in MSI-H tumors. However, levels of the active MMP-9 form were significantly much lower in this group of tumors. Data from real-time quantitative PCR indicated that levels of MMP-3 for MSI-L/MSS tumors were much higher as compared with those observed in MSI-H cancers (P = 0.033). Moreover, all MSI-H tumors showed nucleotide insertions and/or deletions in MMP-3 promoter. These mutations were not observed in the group of MSI-L/MSS tumors. Our data indicate that the MMP-3 promoter constitutes a novel target of the defective mismatch repair machinery in sporadic colorectal tumors, resulting in a dramatic decrease in the levels of the active MMP-9 form, which may result in a lessened capacity for invasion.


Asunto(s)
Adenocarcinoma/genética , Neoplasias Colorrectales/genética , Metaloproteinasa 3 de la Matriz/genética , Metaloproteinasa 9 de la Matriz/metabolismo , Repeticiones de Microsatélite/genética , Mutación , Adenocarcinoma/enzimología , Adenocarcinoma/patología , Secuencia de Bases , Neoplasias Colorrectales/enzimología , Neoplasias Colorrectales/patología , ADN de Neoplasias/genética , Activación Enzimática/genética , Humanos , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 3 de la Matriz/biosíntesis , Datos de Secuencia Molecular , Estadificación de Neoplasias , Regiones Promotoras Genéticas
12.
Oncogene ; 21(19): 3089-94, 2002 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-12082541

RESUMEN

We report the genomic organization of a novel human gene mapped to chromosome 6p21, encoding a putative glycosylphosphatidylinositol (GPI) anchored protein containing a MAM (meprin, A5 antigen, protein tyrosine phosphatase mu) domain, that we have termed as GPIM (GPI and MAM) protein. GPIM gene consists of an 8.9 kb transcript composed of 17 coding exons spanning about 65.5 kb of genomic DNA. The deduced polypeptide consists of 955 amino acids and exhibits structural features found in different types of cell adhesion molecules (CAMs), such as the presence of immunoglobulin domains, the presence of a MAM domain or the capacity to anchor to the cell membrane by a GPI motif. Expression analysis in normal human tissues revealed that this gene is expressed as a 5 kb and 9.5 kb mRNA. Furthermore, the smaller transcript is highly expressed in some human cancer cell lines, as well as in different primary tumors (lung, colon, uterus, stomach and breast). Interestingly, the gene was higher expressed in several tumor tissues analysed as compared to their corresponding normal tissues. Thus, GPIM is a novel gene codifying a protein with structural features characteristics of some CAMs, which might be involved in the tumor progression.


Asunto(s)
Moléculas de Adhesión Celular/genética , Cromosomas Humanos Par 6/genética , Genes , Proteínas de Neoplasias/genética , Neoplasias/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Bovinos , Moléculas de Adhesión Celular/biosíntesis , Moléculas de Adhesión Celular/química , ADN de Neoplasias/genética , Progresión de la Enfermedad , Etiquetas de Secuencia Expresada , Femenino , Proteínas Ligadas a GPI , Expresión Génica , Glicosilfosfatidilinositoles/metabolismo , Humanos , Masculino , Ratones , Datos de Secuencia Molecular , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/química , Neoplasias/metabolismo , Neoplasias/patología , Moléculas de Adhesión de Célula Nerviosa , Especificidad de Órganos , Estructura Terciaria de Proteína , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Homología de Secuencia de Ácido Nucleico , Células Tumorales Cultivadas/metabolismo
13.
J Clin Oncol ; 20(1): 254-62, 2002 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-11773177

RESUMEN

PURPOSE: Telomerase activity and p16 expression can be considered two of the most important molecular markers implicated in tumorigenesis. Our main aim was to study the cooperative role of both molecular alterations in the prognosis of patients surgically resected for non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: We have determined telomerase activity and p16 expression in a series of 98 prospectively collected NSCLC specimens obtained from patients who had undergone surgery without other treatment. Telomerase activity was investigated by a telomeric repeat amplification protocol enzyme-linked immunosorbent assay-based procedure, and p16 expression was examined by Western blot. Associations with survival were evaluated. RESULTS: Positive results for telomerase activity were found in 82% of the cases, and this variable correlated with poor differentiation and recurrence of tumors. Lack of p16 expression was observed in 61% of tumors, and a significant association with tumor recurrence was also observed. By univariate analysis, both negative telomerase activity and p16-positive expression were significantly correlated with a better prognosis. Moreover, statistics for equality of survival distributions for telomerase, adjusted for p16, indicated a positive interaction between both parameters. For telomerase-positive tumors, p16 expression emerged as a significant independent protective variable, as indicated by Cox multivariate analysis (relative risk [RR], 0.214; P =.014). This protective effect was maintained only for stage I and II tumors (RR, 0.108; P =.046). CONCLUSION: These results suggest that the combined telomerase activity and p16 expression analyses may be of prognostic importance in NSCLC, especially for patients affected by stage I and II tumors.


Asunto(s)
Biomarcadores de Tumor/biosíntesis , Carcinoma de Pulmón de Células no Pequeñas/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/biosíntesis , Neoplasias Pulmonares/genética , Telomerasa/biosíntesis , Anciano , Análisis de Varianza , Carcinoma de Pulmón de Células no Pequeñas/diagnóstico , Carcinoma de Pulmón de Células no Pequeñas/cirugía , Supervivencia sin Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/cirugía , Masculino , Persona de Mediana Edad , Pronóstico , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Riesgo , España , Tasa de Supervivencia
14.
BMC Complement Altern Med ; 5: 19, 2005 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-16225693

RESUMEN

BACKGROUND: Although the painful shoulder is one of the most common dysfunctions of the locomotor apparatus, and is frequently treated both at primary healthcare centres and by specialists, little evidence has been reported to support or refute the effectiveness of the treatments most commonly applied. According to the bibliography reviewed, physiotherapy, which is the most common action taken to alleviate this problem, has not yet been proven to be effective, because of the small size of sample groups and the lack of methodological rigor in the papers published on the subject. No reviews have been made to assess the effectiveness of acupuncture in treating this complaint, but in recent years controlled randomised studies have been made and these demonstrate an increasing use of acupuncture to treat pathologies of the soft tissues of the shoulder. In this study, we seek to evaluate the effectiveness of physiotherapy applied jointly with acupuncture, compared with physiotherapy applied with a TENS-placebo, in the treatment of painful shoulder caused by subacromial syndrome (rotator cuff tendinitis and subacromial bursitis). METHODS/DESIGN: Randomised controlled multicentre study with blind evaluation by an independent observer and blind, independent analysis. A study will be made of 465 patients referred to the rehabilitation services at participating healthcare centres, belonging to the regional public health systems of Andalusia and Murcia, these patients presenting symptoms of painful shoulder and a diagnosis of subacromial syndrome (rotator cuff tendinitis and subacromial bursitis). The patients will be randomised into two groups: 1) experimental (acupuncture + physiotherapy); 2) control (TENS-placebo + physiotherapy); the administration of rescue medication will also be allowed. The treatment period will have a duration of three weeks. The main result variable will be the change produced on Constant's Shoulder Function Assessment (SFA) Scale; as secondary variables, we will record the changes in diurnal pain intensity on a visual analogue scale (VAS), nocturnal pain intensity on the VAS, doses of non-steroid anti-inflammatory drugs (NSAIDs) taken during the study period, credibility scale for the treatment, degree of improvement perceived by the patient and degree of improvement perceived by the evaluator. A follow up examination will be made at 3, 6 and 12 months after the study period has ended. Two types of population will be considered for analysis: per protocol and per intention to treat. DISCUSSION: The discussion will take into account the limitations of the study, together with considerations such as the choice of a simple, safe method to treat this shoulder complaint, the choice of the control group, and the blinding of the patients, evaluators and those responsible for carrying out the final analysis.


Asunto(s)
Analgesia por Acupuntura/métodos , Artralgia/terapia , Estudios Multicéntricos como Asunto/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Proyectos de Investigación , Síndrome de Abducción Dolorosa del Hombro/terapia , Artralgia/etiología , Artralgia/rehabilitación , Enfermedad Crónica , Crioterapia , Estudios de Seguimiento , Humanos , Dimensión del Dolor , Selección de Paciente , Modalidades de Fisioterapia , Síndrome de Abducción Dolorosa del Hombro/complicaciones , Síndrome de Abducción Dolorosa del Hombro/rehabilitación , Estimulación Eléctrica Transcutánea del Nervio
16.
Int J Oncol ; 24(2): 349-55, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-14719111

RESUMEN

Inactivation of p16 has been reported as one of the more frequent events in human carcinogenesis. In order to contribute to the knowledge of the impact of p16 silencing by promoter methylation, we have investigated p16 expression and inactivation of p16 by methylation in two of the major types of human cancer, non-small cell lung cancer (NSCLC) and colorectal cancer (CRC). p16 expression was evaluated by Western blot, and p16 promoter methylation by a methylation-specific PCR procedure (MSP). Clinical correlations were established using the chi-square test, and distributions of disease-free survival (DFS) were estimated with the Kaplan-Meier method. Analyses for p16 revealed that 61.22% (60 of 98) of NSCLCs, and 32.9% (26 of 79) of CRCs here considered, lacked p16 expression. Moreover, 36.7% (22/60) of the non-small cell lung tumours without p16 expression showed p16 promoter methylation, detecting a significant correlation between p16 methylation and the histological subtype of squamous cell carcinomas (SCC) (P=0.04). With respect to CRCs, p16 promoter methylation was observed in 26.9% of tumours that lacked p16 expression (7/26), all tumours studied showing partial methylation. Survival studies demonstrated a clear correlation between p16 negative expression and poor prognosis in NSCLC patients. Moreover, we found a trend toward poor clinical evolution in the group of patients with tumours showing total p16 methylation, in NSCLC, without statistically significant differences in CRC. In conclusion, our results indicate that p16 alterations constitute a major molecular abnormality in NSCLC with a considerable prognosis impact, promoter methylation being an important mechanism involved in p16 silencing. In CRC, however, p16 promoter methylation could be considered as a less definitive molecular factor without prognostic implication, since partial methylation constitutes a prevalent mechanism.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/genética , Neoplasias Colorrectales/genética , Silenciador del Gen , Genes p16 , Neoplasias Pulmonares/genética , Regiones Promotoras Genéticas , Anciano , Western Blotting , Metilación de ADN , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Pronóstico , Factores de Tiempo
17.
Curr Biol ; 23(5): 412-8, 2013 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-23416099

RESUMEN

Cell diversity and organization in the neural tube depend on the integration of extrinsic signals acting along orthogonal axes. These are believed to specify distinct cellular identities by triggering all-or-none changes in expression of combinations of transcription factors. Under the influence of a common dorsoventral signal, sonic hedgehog, and distinct anterior-posterior (A-P) inductive signals, two topographically related progenitor pools that share a common transcriptional code produce serotonergic and V3 neurons in the hindbrain and spinal cord, respectively. These neurons have different physiological properties, functions, and connectivity. Serotonergic involvement in neuropsychiatric diseases has prompted greater characterization of their postmitotic repertoire of fate determinants, which include Gata2, Lmx1b, and Pet1, whereas V3 neurons express Sim1. How distinct serotonergic and V3 neuronal identities emerge from progenitors that share a common transcriptional code is not understood. Here, we show that changes in retinoid activity in these two progenitor pools determine their fates. Retinoids, via Notch signaling, control the expression level in progenitors of the transcription factor Ascl1, which selects serotonergic and V3 neuronal identities in a dose-dependent manner. Therefore, quantitative differences in the expression of a single component of a transcriptional code can select distinct cell fates.


Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Tubo Neural/metabolismo , Neurogénesis , Retinoides/metabolismo , Animales , Embrión de Pollo , Ratones , Ratones Transgénicos , Tubo Neural/citología , Tubo Neural/embriología , Receptores Notch/metabolismo , Neuronas Serotoninérgicas/citología , Transducción de Señal
18.
Dev Cell ; 18(1): 136-47, 2010 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-20152184

RESUMEN

Precise regulation of neurogenesis is achieved in specific regions of the vertebrate nervous system by formation of distinct neurogenic and nonneurogenic zones. We have investigated how neurogenesis becomes confined to zones adjacent to rhombomere boundaries in the zebrafish hindbrain. The nonneurogenic zone at segment centers comprises a distinct progenitor population that expresses fibroblast growth factor (fgfr) 2, erm, sox9b, and the retinoic acid degrading enzyme, cyp26b1. FGF receptor activation upregulates expression of these genes and inhibits neurogenesis in segment centers. Cyp26 activity is a key effector inhibiting neuronal differentiation, suggesting antagonistic interactions with retinoid signaling. We identify the critical FGF ligand, fgf20a, which is expressed by specific neurons located in the mantle region at the center of segments, adjacent to the nonneurogenic zone. Fgf20a mutants have ectopic neurogenesis and lack the segment center progenitor population. Our findings reveal how signaling from neurons induces formation of a nonneurogenic zone of neural progenitors.


Asunto(s)
Tipificación del Cuerpo/fisiología , Neurogénesis/fisiología , Neuronas/metabolismo , Rombencéfalo/embriología , Rombencéfalo/metabolismo , Células Madre/metabolismo , Animales , Comunicación Celular/fisiología , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Factores de Crecimiento de Fibroblastos/genética , Factores de Crecimiento de Fibroblastos/metabolismo , Regulación del Desarrollo de la Expresión Génica/fisiología , Neuronas/citología , Ácido Retinoico 4-Hidroxilasa , Rombencéfalo/citología , Factor de Transcripción SOX9/genética , Factor de Transcripción SOX9/metabolismo , Transducción de Señal/fisiología , Células Madre/citología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Pez Cebra , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismo
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