Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Tumori ; : 3008916241257099, 2024 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-38825833

RESUMEN

BACKGROUND: Induction chemotherapy has been described as an option in locally advanced oral cavity squamous cell carcinoma when the surgical morbidity is expected to be high. This work aimed to evaluate the outcome and safety of induction chemotherapy in this setting. METHODS: We performed a retrospective and observational study including patients with oral cavity squamous cell carcinoma, treated with induction chemotherapy between January 2010 and December 2018. Outcomes included induction chemotherapy toxicity, treatment response, disease-free survival and overall survival. RESULTS: A total of 108 oral cavity squamous cell carcinoma patients were included. Ninety-six (88.9%) had stage IV disease, while 12 (11.1%) had stage III. Eighty-four patients (80.8%) achieved at least a partial response to induction chemotherapy at clinical evaluation, and 75 (72.1%) at radiological evaluation. Seventy-eight patients have been proposed for subsequent definitive treatments, with no differences obtained in prognosis, when comparing surgical to non-surgical approaches. In patients treated with definitive treatments, improved five-year disease-free survival was obtained if at least a clinical (56.3%; p=0.001) or radiological (52.9%; p=0.001) partial response was achieved after induction chemotherapy. Similarly, superior five-year overall survival was verified for those achieving at least clinical (51.1%; p<0.0001) or radiological (52.6%; p=0.001) partial response. Also, accomplishing a pathologic complete response (n=22.6%) significantly improved disease-free survival (p=0.039) and overall survival (p=0.005). Grade 3 and 4 toxicities were observed in 52 patients (41.8%). CONCLUSION: Responses to induction chemotherapy predicted prognosis in our population, however important toxicities were observed. Further studies are necessary to identify induction chemotherapy response predictors and subgroups who may benefit from this approach.

2.
Front Psychol ; 13: 855531, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35936254

RESUMEN

There is a need for educational support structures to empower parents in sustaining talented athletes pursuing academic and sports careers (e. g., dual career). The present work describes the participatory design used to develop a series of educational resources and the subsequent iterations used to evaluate the content of the EMPATIA online education programme for parents of dual-career athletes. Following an ethnographic approach, the project team (18 dual-career experts) engaged in four iterations (i.e., rounds) planned to develop (rounds 1 and 2) educational material from preliminary evidence (systematic literature review) and eminence (focus groups and concept mapping) knowledge and to evaluate the educational programme (round 3 and 4) engaging end users (n = 76) and other stakeholders (9 dual-career experts). The EMPATIA programme was developed and organized in four modules labeled after macro-aspects, parents could ask about dual career: "Why" (the definition and challenges of dual career for athletes and their parents), "What" (insights, guidelines, and suggestions on the parental role in support of student-athletes), "How" (practical advice on planning dual career at sports and academic levels, and post-sports careers), and "Where" (finding legal information or counseling on dual career). Despite overall positive evaluations of the programme, parents of dual-career athletes attributed higher scores with respect to those of dual-career experts. The participatory approach presented in this work enables developers to apply a systematic and multidisciplinary approach toward the creation of educational programmes for parents. The cooperation among dual-career researchers, experts from high-performance centers, Olympic bodies, sports clubs, and parents of elite student-athletes of different sports and nationalities created an educational programme suitable for end users to support parenting athletes in combining their sports and academic careers.

3.
Elife ; 112022 04 11.
Artículo en Inglés | MEDLINE | ID: mdl-35404236

RESUMEN

The morphogenic process of convergent thickening (CT) was originally described as the mediolateral convergence and radial thickening of the explanted ventral involuting marginal zone (IMZ) of Xenopus gastrulae (Keller and Danilchik, 1988). Here, we show that CT is expressed in all sectors of the pre-involution IMZ, which transitions to expressing convergent extension (CE) after involution. CT occurs without CE and drives symmetric blastopore closure in ventralized embryos. Assays of tissue affinity and tissue surface tension measurements suggest CT is driven by increased interfacial tension between the deep IMZ and the overlying epithelium. The resulting minimization of deep IMZ surface area drives a tendency to shorten the mediolateral (circumblastoporal) aspect of the IMZ, thereby generating tensile force contributing to blastopore closure (Shook et al., 2018). These results establish CT as an independent force-generating process of evolutionary significance and provide the first clear example of an oriented, tensile force generated by an isotropic, Holtfreterian/Steinbergian tissue affinity change.


Asunto(s)
Evolución Biológica , Gástrula , Animales , Movimiento Celular , Morfogénesis , Xenopus laevis
4.
PLoS One ; 16(9): e0257719, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34551023

RESUMEN

BACKGROUND: This study aimed to use a concept mapping methodology to develop a European framework of the needs of parents/guardians (P/G) for supporting athletes combining sport and education (dual career, DC). METHODS: By means of a concept mapping methodology, 337 French, Irish, Italian, Portuguese, and Slovenian parents sorted and rated 80 potential statements associated to parenting DC athletes. RESULTS: Five distinct clusters emerged: 1. P/G' roles, needs and awareness to support athletes, including 22 statements (mean:3.7; range: 3.2-4.2 pt); 2. Requirements for effective planning of DC pathway, including 19 statements (mean:3.7; range: 3.2-4.5 pt); 3. Educational opportunity, including 13 statements (mean:3.5; range: 3.1-4.0 pt); 4. Policy and provision for DC, including 19 statements (mean:3.7; range: 3.1-4.2 pt); and 5. Athletes' lifestyle & self-management, including 7 statements (mean:4.0; range: 3.5-4.5 pt). Estimates of effect size (Partial eta-squared) were calculated for ANOVAs to assess the degree of variability on the statement importance ranking as the dependent variable accounted for by the demographic data. The concept mapping showed good validity (stress value: 0.11) and high reliability (rSHT: 0.99, rSHM: 0.98; rRR:0.98). One-third of the statements indicated differences (p<0.05) in relation to the P/Gs' gender and the athletes' education level, competition level and sport typology. CONCLUSION: In synthesizing the opinions, experience and needs of P/Gs of DC athletes the present framework provided sound theoretical underpinnings to inform the development of an online educational programme for empowering parenting DC athletes (https://edu.empatiasport.eu/eng/), as well as be a foundation for future Pan-European DC research on how these statements interact with each other, in different European contexts.


Asunto(s)
Atletas , Formación de Concepto , Adulto , Humanos , Ocupaciones , Reproducibilidad de los Resultados
5.
Cureus ; 13(6): e16025, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34336513

RESUMEN

Gastric duplication cyst (GDC) is a rare congenital abnormality and the development of malignant transformation in these lesions is even rarer, with only few reported cases worldwide to date. We hereby report an additional case of cancer arising from a GDC in a 54-year-old male. The patient's chief complaints were abdominal pain and significant weight loss. Computed tomography and endoscopy ultrasonography (EUS) revealed a nodular formation with a cystic component, localized in the great gastric curvature and invading the spleen and left adrenal gland. The biopsy from EUS was inconclusive. After exploratory laparotomy, the patient was submitted to an en-bloc resection with partial gastrectomy, splenectomy and left adrenalectomy. Histopathologic examination revealed a cystic mass non-communicating with the gastric wall. Immunohistochemistry staining showed a moderately differentiated pancreatobiliary adenocarcinoma within a duplication cyst with lymphovascular and perineural invasion. The patient was proposed to adjuvant systemic treatment, however, after few months he developed metachronous metastasis. To our knowledge, this is the first case of adenocarcinoma with pancreatobiliary differentiation arising from a gastric duplication cyst.

6.
PLoS One ; 16(1): e0243354, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33471807

RESUMEN

BACKGROUND: Despite the fact that an educational programme for parents of youth tennis players has been launched recently, there is a need to empower parents of athletes in sustaining the combination of education and sport careers (i.e., dual career) of their talented and elite athletes across sports. The aim of this study was to explore the parents' view of their role as dual career supporters and their need for educational support in this area. METHODS: In total, 115 parents (F = 49, M = 66) of athletes (14-23 yrs) engaged in full time academic education (high school/university) and competitive (e.g., National, International) sports (individual = 12, team = 9) in five European Member States (e.g., France, Ireland, Italy, Portugal, Slovenia) took part in national workshops. The workshops involved discussing five themes and agreeing statements relevant to assist parents supporting their children as dual career athletes: 1) the athletes' needs; 2) the sports environment; 3) the academic environment; 4) dual career-related policies and services; 5) The educational methods for parenting dual career athletes. RESULTS: A final list of 80 agreed statements were identified: 25 statements mainly related to the sports entourage; 23 to information on dual career-related policies and services; 22 to the athletes' needs; 17 to the academic entourage, and 8 to the relevant educational resources to parenting dual career athletes, respectively. CONCLUSIONS: This cross-national qualitative research synthesized the parents' perspectives about their needs and the most relevant content of an educational programme for parenting dual career athletes. The findings of this research will help influence the formulation of effective education strategies on parenting dual career athletes to ensure an optimal supportive environment for the successful combination of high-level sport and education careers.


Asunto(s)
Atletas , Escolaridad , Responsabilidad Parental , Deportes , Adolescente , Femenino , Humanos , Masculino , Modelos Educacionales , Adulto Joven
7.
Dev Cell ; 52(3): 321-334.e6, 2020 02 10.
Artículo en Inglés | MEDLINE | ID: mdl-32049039

RESUMEN

Epithelial fusion is a key process of morphogenesis by which tissue connectivity is established between adjacent epithelial sheets. A striking and poorly understood feature of this process is "zippering," whereby a fusion point moves directionally along an organ rudiment. Here, we uncover the molecular mechanism underlying zippering during mouse spinal neural tube closure. Fusion is initiated via local activation of integrin ß1 and focal anchorage of surface ectoderm cells to a shared point of fibronectin-rich basement membrane, where the neural folds first contact each other. Surface ectoderm cells undergo proximal junction shortening, establishing a transitory semi-rosette-like structure at the zippering point that promotes juxtaposition of cells across the midline enabling fusion propagation. Tissue-specific ablation of integrin ß1 abolishes the semi-rosette formation, preventing zippering and causing spina bifida. We propose integrin-mediated anchorage as an evolutionarily conserved mechanism of general relevance for zippering closure of epithelial gaps whose disturbance can produce clinically important birth defects.


Asunto(s)
Embrión de Mamíferos/fisiología , Células Epiteliales/fisiología , Adhesiones Focales , Integrina beta1/fisiología , Cresta Neural/embriología , Tubo Neural/embriología , Neurulación , Actomiosina/metabolismo , Animales , Fusión Celular , Embrión de Mamíferos/citología , Embrión de Mamíferos/metabolismo , Células Epiteliales/citología , Células Epiteliales/metabolismo , Femenino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Morfogénesis , Cresta Neural/metabolismo , Cresta Neural/fisiología , Tubo Neural/metabolismo , Tubo Neural/fisiología
8.
Dis Model Mech ; 12(11)2019 11 14.
Artículo en Inglés | MEDLINE | ID: mdl-31628096

RESUMEN

Encephalocele is a clinically important birth defect that can lead to severe disability in childhood and beyond. The embryonic and early fetal pathogenesis of encephalocele is poorly understood and, although usually classified as a 'neural tube defect', there is conflicting evidence on whether encephalocele results from defective neural tube closure or is a post-neurulation defect. It is also unclear whether encephalocele can result from the same causative factors as anencephaly and open spina bifida, or whether it is aetiologically distinct. This lack of information results largely from the scarce availability of animal models of encephalocele, particularly ones that resemble the commonest, nonsyndromic human defects. Here, we report a novel mouse model of occipito-parietal encephalocele, in which the small GTPase Rac1 is conditionally ablated in the (non-neural) surface ectoderm. Most mutant fetuses have open spina bifida, and some also exhibit exencephaly/anencephaly. However, a proportion of mutant fetuses exhibit brain herniation, affecting the occipito-parietal region and closely resembling encephalocele. The encephalocele phenotype does not result from defective neural tube closure, but rather from a later disruption of the surface ectoderm covering the already closed neural tube, allowing the brain to herniate. The neuroepithelium itself shows no downregulation of Rac1 and appears morphologically normal until late gestation. A large skull defect overlies the region of brain herniation. Our work provides a new genetic model of occipito-parietal encephalocele, particularly resembling nonsyndromic human cases. Although encephalocele has a different, later-arising pathogenesis than open neural tube defects, both can share the same genetic causation.


Asunto(s)
Modelos Animales de Enfermedad , Encefalocele/etiología , Defectos del Tubo Neural/etiología , Neurulación/fisiología , Animales , Proteínas de Unión al ADN/fisiología , Ectodermo/fisiología , Humanos , Ratones , Ratones Endogámicos C57BL , Neuropéptidos/fisiología , Factores de Transcripción/fisiología , Proteína de Unión al GTP rac1/fisiología
9.
Nat Commun ; 10(1): 2487, 2019 06 06.
Artículo en Inglés | MEDLINE | ID: mdl-31171776

RESUMEN

Lack or excess expression of the surface ectoderm-expressed transcription factor Grainyhead-like2 (Grhl2), each prevent spinal neural tube closure. Here we investigate the causative mechanisms and find reciprocal dysregulation of epithelial genes, cell junction components and actomyosin properties in Grhl2 null and over-expressing embryos. Grhl2 null surface ectoderm shows a shift from epithelial to neuroepithelial identity (with ectopic expression of N-cadherin and Sox2), actomyosin disorganisation, cell shape changes and diminished resistance to neural fold recoil upon ablation of the closure point. In contrast, excessive abundance of Grhl2 generates a super-epithelial surface ectoderm, in which up-regulation of cell-cell junction proteins is associated with an actomyosin-dependent increase in local mechanical stress. This is compatible with apposition of the neural folds but not with progression of closure, unless myosin activity is inhibited. Overall, our findings suggest that Grhl2 plays a crucial role in regulating biomechanical properties of the surface ectoderm that are essential for spinal neurulation.


Asunto(s)
Embrión de Mamíferos/metabolismo , Regulación del Desarrollo de la Expresión Génica , Tubo Neural/embriología , Células Neuroepiteliales/metabolismo , Neurulación/genética , Factores de Transcripción/genética , Actomiosina/genética , Actomiosina/metabolismo , Animales , Fenómenos Biomecánicos , Cadherinas/metabolismo , Ectodermo/citología , Ectodermo/embriología , Ectodermo/metabolismo , Células Epiteliales/metabolismo , Uniones Intercelulares/genética , Uniones Intercelulares/metabolismo , Ratones , Tubo Neural/metabolismo , Factores de Transcripción SOXB1/metabolismo , Estrés Mecánico , Factores de Transcripción/metabolismo
10.
Hum Mol Genet ; 27(24): 4218-4230, 2018 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-30189017

RESUMEN

The genetic basis of human neural tube defects (NTDs), such as anencephaly and spina bifida (SB), is complex and heterogeneous. Grainyhead-like genes represent candidates for involvement in NTDs based on the presence of SB and exencephaly in mice carrying loss-of-function alleles of Grhl2 or Grhl3. We found that reinstatement of Grhl3 expression, by bacterial artificial chromosome (BAC)-mediated transgenesis, prevents SB in Grhl3-null embryos, as in the Grhl3 hypomorphic curly tail strain. Notably, however, further increase in expression of Grhl3 causes highly penetrant SB. Grhl3 overexpression recapitulates the spinal NTD phenotype of loss-of-function embryos, although the underlying mechanism differs. However, it does not phenocopy other defects of Grhl3-null embryos such as abnormal axial curvature, cranial NTDs (exencephaly) or skin barrier defects, the latter being rescued by the Grhl3-transgene. Grhl2 and Grhl3 can form homodimers and heterodimers, suggesting a possible model in which defects arising from overexpression of Grhl3 result from sequestration of Grhl2 in heterodimers, mimicking Grhl2 loss of function. This hypothesis predicts that increased abundance of Grhl2 would have an ameliorating effect in Grhl3 overexpressing embryo. Instead, we observed a striking additive genetic interaction between Grhl2 and Grhl3 gain-of-function alleles. Severe SB arose in embryos in which both genes were expressed at moderately elevated levels that individually do not cause NTDs. Furthermore, moderate Grhl3 overexpression also interacted with the Vangl2Lp allele to cause SB, demonstrating genetic interaction with the planar cell polarity signalling pathway that is implicated in mouse and human NTDs.


Asunto(s)
Proteínas de Unión al ADN/genética , Proteínas del Tejido Nervioso/genética , Defectos del Tubo Neural/genética , Disrafia Espinal/genética , Factores de Transcripción/genética , Alelos , Animales , Animales Modificados Genéticamente/genética , Modelos Animales de Enfermedad , Desarrollo Embrionario/genética , Regulación del Desarrollo de la Expresión Génica/genética , Humanos , Mutación con Pérdida de Función , Ratones , Defectos del Tubo Neural/patología , Multimerización de Proteína/genética , Disrafia Espinal/patología
11.
Dev Biol ; 435(2): 130-137, 2018 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-29397878

RESUMEN

Failure of neural tube closure leads to neural tube defects (NTDs), common congenital abnormalities in humans. Among the genes whose loss of function causes NTDs in mice, Grainyhead-like3 (Grhl3) is essential for spinal neural tube closure, with null mutants exhibiting fully penetrant spina bifida. During spinal neurulation Grhl3 is initially expressed in the surface (non-neural) ectoderm, subsequently in the neuroepithelial component of the neural folds and at the node-streak border, and finally in the hindgut endoderm. Here, we show that endoderm-specific knockout of Grhl3 causes late-arising spinal NTDs, preceded by increased ventral curvature of the caudal region which was shown previously to suppress closure of the spinal neural folds. This finding supports the hypothesis that diminished Grhl3 expression in the hindgut is the cause of spinal NTDs in the curly tail, carrying a hypomorphic Grhl3 allele. Complete loss of Grhl3 function produces a more severe phenotype in which closure fails earlier in neurulation, before the stage of onset of expression in the hindgut of wild-type embryos. This implicates additional tissues and NTD mechanisms in Grhl3 null embryos. Conditional knockout of Grhl3 in the neural plate and node-streak border has minimal effect on closure, suggesting that abnormal function of surface ectoderm, where Grhl3 transcripts are first detected, is primarily responsible for early failure of spinal neurulation in Grhl3 null embryos.


Asunto(s)
Proteínas de Unión al ADN/fisiología , Defectos del Tubo Neural/genética , Tubo Neural/fisiología , Neurulación/genética , Factores de Transcripción/fisiología , Animales , Proteínas de Unión al ADN/deficiencia , Proteínas de Unión al ADN/genética , Desarrollo Embrionario , Regulación del Desarrollo de la Expresión Génica , Genes Reporteros , Estratos Germinativos/metabolismo , Ratones , Ratones Noqueados , Ratones Transgénicos , Placa Neural/metabolismo , Defectos del Tubo Neural/embriología , Defectos del Tubo Neural/patología , Especificidad de Órganos , ARN Mensajero/biosíntesis , Disrafia Espinal/embriología , Disrafia Espinal/genética , Factores de Transcripción/deficiencia , Factores de Transcripción/genética
12.
Small GTPases ; 9(4): 283-289, 2018 07 04.
Artículo en Inglés | MEDLINE | ID: mdl-27768516

RESUMEN

Neural tube closure is an important morphogenetic event that involves dramatic reshaping of both neural and non-neural tissues. Rho GTPases are key cytoskeletal regulators involved in cell motility and in several developmental processes, and are thus expected to play pivotal roles in neurulation. Here, we discuss 2 recent studies that shed light on the roles of distinct Rho GTPases in different tissues during neurulation. RhoA plays an essential role in regulating actomyosin dynamics in the neural epithelium of the elevating neural folds, while Rac1 is required for the formation of cell protrusions in the non-neural surface ectoderm during neural fold fusion.


Asunto(s)
Tubo Neural/metabolismo , Médula Espinal/embriología , Proteínas de Unión al GTP rho/metabolismo , Animales , Membrana Celular/metabolismo , Humanos , Tubo Neural/citología , Tubo Neural/enzimología
13.
Proc Natl Acad Sci U S A ; 114(26): E5177-E5186, 2017 06 27.
Artículo en Inglés | MEDLINE | ID: mdl-28607062

RESUMEN

Neural tube (NT) formation in the spinal region of the mammalian embryo involves a wave of "zippering" that passes down the elongating spinal axis, uniting the neural fold tips in the dorsal midline. Failure of this closure process leads to open spina bifida, a common cause of severe neurologic disability in humans. Here, we combined a tissue-level strain-mapping workflow with laser ablation of live-imaged mouse embryos to investigate the biomechanics of mammalian spinal closure. Ablation of the zippering point at the embryonic dorsal midline causes far-reaching, rapid separation of the elevating neural folds. Strain analysis revealed tissue expansion around the zippering point after ablation, but predominant tissue constriction in the caudal and ventral neural plate zone. This zone is biomechanically coupled to the zippering point by a supracellular F-actin network, which includes an actin cable running along the neural fold tips. Pharmacologic inhibition of F-actin or laser ablation of the cable causes neural fold separation. At the most advanced somite stages, when completion of spinal closure is imminent, the cable forms a continuous ring around the neuropore, and simultaneously, a new caudal-to-rostral zippering point arises. Laser ablation of this new closure initiation point causes neural fold separation, demonstrating its biomechanical activity. Failure of spinal closure in pre-spina bifida Zic2Ku mutant embryos is associated with altered tissue biomechanics, as indicated by greater neuropore widening after ablation. Thus, this study identifies biomechanical coupling of the entire region of active spinal neurulation in the mouse embryo as a prerequisite for successful NT closure.


Asunto(s)
Embrión de Mamíferos/metabolismo , Modelos Biológicos , Tubo Neural/embriología , Actinas , Animales , Embrión de Mamíferos/citología , Humanos , Ratones , Ratones Mutantes , Tubo Neural/citología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
14.
Development ; 144(4): 552-566, 2017 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-28196803

RESUMEN

Neural tube closure has been studied for many decades, across a range of vertebrates, as a paradigm of embryonic morphogenesis. Neurulation is of particular interest in view of the severe congenital malformations - 'neural tube defects' - that result when closure fails. The process of neural tube closure is complex and involves cellular events such as convergent extension, apical constriction and interkinetic nuclear migration, as well as precise molecular control via the non-canonical Wnt/planar cell polarity pathway, Shh/BMP signalling, and the transcription factors Grhl2/3, Pax3, Cdx2 and Zic2. More recently, biomechanical inputs into neural tube morphogenesis have also been identified. Here, we review these cellular, molecular and biomechanical mechanisms involved in neural tube closure, based on studies of various vertebrate species, focusing on the most recent advances in the field.


Asunto(s)
Defectos del Tubo Neural/embriología , Tubo Neural/embriología , Neurulación , Animales , Tipificación del Cuerpo , Movimiento Celular , Polaridad Celular , Desarrollo Embrionario , Fibronectinas/metabolismo , Humanos , Laminina/metabolismo , Morfogénesis , Proteoglicanos/metabolismo , Factores de Riesgo , Transducción de Señal , Estrés Mecánico , Factores de Transcripción/metabolismo
15.
Elife ; 5: e13273, 2016 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-27114066

RESUMEN

Epithelial fusion is a crucial process in embryonic development, and its failure underlies several clinically important birth defects. For example, failure of neural fold fusion during neurulation leads to open neural tube defects including spina bifida. Using mouse embryos, we show that cell protrusions emanating from the apposed neural fold tips, at the interface between the neuroepithelium and the surface ectoderm, are required for completion of neural tube closure. By genetically ablating the cytoskeletal regulators Rac1 or Cdc42 in the dorsal neuroepithelium, or in the surface ectoderm, we show that these protrusions originate from surface ectodermal cells and that Rac1 is necessary for the formation of membrane ruffles which typify late closure stages, whereas Cdc42 is required for the predominance of filopodia in early neurulation. This study provides evidence for the essential role and molecular regulation of membrane protrusions prior to fusion of a key organ primordium in mammalian development.


Asunto(s)
Extensiones de la Superficie Celular/metabolismo , Ectodermo/citología , Ectodermo/enzimología , Cresta Neural/embriología , Tubo Neural/embriología , Neuropéptidos/metabolismo , Proteína de Unión al GTP cdc42/metabolismo , Proteína de Unión al GTP rac1/metabolismo , Animales , Ratones , Neurulación
16.
Birth Defects Res A Clin Mol Teratol ; 94(10): 817-23, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22945349

RESUMEN

Adhesion and fusion of epithelial sheets marks the completion of many morphogenetic events during embryogenesis. Neural tube closure involves an epithelial fusion sequence in which the apposing neural folds adhere initially via cellular protrusions, proceed to a more stable union, and subsequently undergo remodeling of the epithelial structures to yield a separate neural tube roof plate and overlying nonneural ectoderm. Cellular protrusions comprise lamellipodia and filopodia, and studies in several different systems emphasize the critical role of RhoGTPases in their regulation. How epithelia establish initial adhesion is poorly understood but, in neurulation, may involve interactions between EphA receptors and their ephrinA ligands. Epithelial remodeling is spatially and temporally correlated with apoptosis in the dorsal neural tube midline, but experimental inhibition of this cell death does not prevent fusion and remodeling. A variety of molecular signaling systems have been implicated in the late events of morphogenesis, but genetic redundancy, for example among the integrins and laminins, makes identification of the critical players challenging. An improved understanding of epithelial fusion can provide insights into normal developmental processes and may also indicate the mode of origin of clinically important birth defects.


Asunto(s)
Células Epiteliales/fisiología , Morfogénesis/fisiología , Cresta Neural/embriología , Tubo Neural/embriología , Animales , Apoptosis/genética , Apoptosis/fisiología , Adhesión Celular/genética , Adhesión Celular/fisiología , Fusión Celular , Células Epiteliales/citología , Células Epiteliales/metabolismo , Humanos , Modelos Biológicos , Morfogénesis/genética , Cresta Neural/citología , Cresta Neural/metabolismo , Tubo Neural/metabolismo , Tubo Neural/fisiología , Neurulación/genética , Neurulación/fisiología
17.
Dev Biol ; 327(2): 327-38, 2009 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-19121300

RESUMEN

Vertebrate neural tube formation involves two distinct morphogenetic events--convergent extension (CE) driven by mediolateral cell intercalation, and bending of the neural plate driven largely by cellular apical constriction. However, the cellular and molecular biomechanics of these processes are not understood. Here, using tissue-targeting techniques, we show that the myosin IIB motor protein complex is essential for both these processes, as well as for conferring resistance to deformation to the neural plate tissue. We show that myosin IIB is required for actin-cytoskeletal organization in both superficial and deep layers of the Xenopus neural plate. In the superficial layer, myosin IIB is needed for apical actin accumulation, which underlies constriction of the neuroepithelial cells, and that ultimately drive neural plate bending, whereas in the deep neural cells myosin IIB organizes a cortical actin cytoskeleton, which we describe for the first time, and that is necessary for both normal neural cell cortical tension and shape and for autonomous CE of the neural tissue. We also show that myosin IIB is required for resistance to deformation ("stiffness") in the neural plate, indicating that the cytoskeleton-organizing roles of this protein translate in regulation of the biomechanical properties of the neural plate at the tissue-level.


Asunto(s)
Morfogénesis/fisiología , Tubo Neural/fisiología , Neurulación/fisiología , Miosina Tipo IIB no Muscular/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus laevis , Actinas/metabolismo , Animales , Movimiento Celular , Forma de la Célula , Citoesqueleto/metabolismo , Tubo Neural/anatomía & histología , Miosina Tipo IIB no Muscular/genética , Oligonucleótidos Antisentido/genética , Oligonucleótidos Antisentido/metabolismo , Proteínas de Xenopus/genética , Xenopus laevis/anatomía & histología , Xenopus laevis/embriología
18.
Development ; 135(14): 2435-44, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18550716

RESUMEN

Force-producing convergence (narrowing) and extension (lengthening) of tissues by active intercalation of cells along the axis of convergence play a major role in axial morphogenesis during embryo development in both vertebrates and invertebrates, and failure of these processes in human embryos leads to defects including spina bifida and anencephaly. Here we use Xenopus laevis, a system in which the polarized cell motility that drives this active cell intercalation has been related to the development of forces that close the blastopore and elongate the body axis, to examine the role of myosin IIB in convergence and extension. We find that myosin IIB is localized in the cortex of intercalating cells, and show by morpholino knockdown that this myosin isoform is essential for the maintenance of a stereotypical, cortical actin cytoskeleton as visualized with time-lapse fluorescent confocal microscopy. We show that this actin network consists of foci or nodes connected by cables and is polarized relative to the embryonic axis, preferentially cyclically shortening and lengthening parallel to the axis of cell polarization, elongation and intercalation, and also parallel to the axis of convergence forces during gastrulation. Depletion of MHC-B results in disruption of this polarized cytoskeleton, loss of the polarized protrusive activity characteristic of intercalating cells, eventual loss of cell-cell and cell-matrix adhesion, and dose-dependent failure of blastopore closure, arguably because of failure to develop convergence forces parallel to the myosin IIB-dependent dynamics of the actin cytoskeleton. These findings bridge the gap between a molecular-scale motor protein and tissue-scale embryonic morphogenesis.


Asunto(s)
Actinas/fisiología , Gastrulación/fisiología , Miosina Tipo IIB no Muscular/fisiología , Animales , Cadherinas/metabolismo , Adhesión Celular , Movimiento Celular , Citoesqueleto/fisiología , Relación Dosis-Respuesta a Droga , Embrión no Mamífero/citología , Embrión no Mamífero/fisiología , Femenino , Gástrula/efectos de los fármacos , Integrina alfa5/metabolismo , Proteínas de la Membrana/fisiología , Morfogénesis , Miosina Tipo IIB no Muscular/metabolismo , Notocorda/citología , Notocorda/fisiología , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/fisiología , Xenopus/embriología , Proteínas de Xenopus/metabolismo
19.
Mech Dev ; 125(5-6): 421-31, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18359614

RESUMEN

Neural induction is widely believed to be a direct consequence of inhibition of BMP pathways. Because of conflicting results and interpretations, we have re-examined this issue in Xenopus and chick embryos using the powerful and general TGFbeta inhibitor, Smad7, which inhibits both Smad1- (BMP) and Smad2- (Nodal/Activin) mediated pathways. We confirm that Smad7 efficiently inhibits phosphorylation of Smad1 and Smad2. Surprisingly, however, over-expression of Smad7 in Xenopus ventral epidermis induces expression of the dorsal mesodermal markers Chordin and Brachyury. Neural markers are induced, but in a non-cell-autonomous manner and only when Chordin and Brachyury are also induced. Simultaneous inhibition of Smad1 and Smad2 by different approaches does not account for all Smad7 effects, indicating that Smad7 has activities other than inhibition of the TGFbeta pathway. We provide evidence that these effects are independent of Wnt, FGF, Hedgehog and retinoid signalling. We also show that these effects are due to elements outside of the MH2 domain of Smad7. Together, these results indicate that BMP inhibition is not sufficient for neural induction even when Nodal/Activin is also blocked, and that Smad7 activity is considerably more complex than had previously been assumed. We suggest that experiments relying on Smad7 as an inhibitor of TGFbeta-pathways should be interpreted with considerable caution.


Asunto(s)
Mesodermo/metabolismo , Neuronas/metabolismo , Proteína smad7/fisiología , Proteínas de Xenopus/fisiología , Xenopus laevis/metabolismo , Animales , Embrión de Pollo/metabolismo , Biología Evolutiva , Modelos Biológicos , Oocitos/metabolismo , Estructura Terciaria de Proteína , Transducción de Señal , Proteína smad6/metabolismo , Proteína smad7/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Tretinoina/metabolismo , Proteínas de Xenopus/metabolismo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...