RESUMEN
The first binary cell fate decision occurs at the morula stage and gives rise to two distinct types of cells that constitute the trophectoderm (TE) and inner cell mass (ICM). The cell fate determinant, Cdx2, is induced in TE cells and plays an essential role in their differentiation and maintenance. Notch and Hippo signaling cascades are assumed to converge onto regulatory elements of Cdx2, however, the underlying molecular mechanisms are largely unknown. Here, we show involvement of Strawberry Notch1 (Sbno1), a novel chromatin factor of the helicase superfamily 2, during preimplantation development. Sbno1 knockout embryos die at the preimplantation stage without forming a blastocoel, and Cdx2 is not turned on even though both Yap and Tead4 reside normally in nuclei. Accordingly, Sbno1 acts on the trophectoderm-enhancer (TEE) of Cdx2, ensuring its robust and synergistic activation by the Yap/Tead4 and NICD/Rbpj complexes. Interestingly, this synergism is enhanced when cells are mechanically stretched, which might reflect that TE cells are continuously stretched by the expanding ICM and blastocoel cavity. In addition, the histone chaperone, FACT (FAcilitates Chromatin Transcription) physically interacts with Sbno1. Our data provide new evidence on TE specification, highlighting unexpected but essential functions of the highly conserved chromatin factor, Sbno1.
Asunto(s)
Tipificación del Cuerpo/genética , Factor de Transcripción CDX2/metabolismo , Ectodermo/embriología , Receptores Notch/metabolismo , Proteínas Represoras/metabolismo , Transducción de Señal , Trofoblastos/citología , Animales , Secuencia de Bases , Biomarcadores/metabolismo , Blastocisto/metabolismo , Factor de Transcripción CDX2/genética , Ectodermo/metabolismo , Embrión de Mamíferos/metabolismo , Desarrollo Embrionario/genética , Elementos de Facilitación Genéticos/genética , Regulación del Desarrollo de la Expresión Génica , Chaperonas de Histonas/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación/genética , Fenotipo , Unión Proteica , Transcripción Genética , Activación Transcripcional/genéticaRESUMEN
Heartbeat is required for normal development of the heart, and perturbation of intracardiac flow leads to morphological defects resembling congenital heart diseases. These observations implicate intracardiac haemodynamics in cardiogenesis, but the signalling cascades connecting physical forces, gene expression and morphogenesis are largely unknown. Here we use a zebrafish model to show that the microRNA, miR-21, is crucial for regulation of heart valve formation. Expression of miR-21 is rapidly switched on and off by blood flow. Vasoconstriction and increasing shear stress induce ectopic expression of miR-21 in the head vasculature and heart. Flow-dependent expression of mir-21 governs valvulogenesis by regulating the expression of the same targets as mouse/human miR-21 (sprouty, pdcd4, ptenb) and induces cell proliferation in the valve-forming endocardium at constrictions in the heart tube where shear stress is highest. We conclude that miR-21 is a central component of a flow-controlled mechanotransduction system in a physicogenetic regulatory loop.
Asunto(s)
Circulación Sanguínea/fisiología , Válvulas Cardíacas/embriología , Hemodinámica , MicroARNs/genética , Pez Cebra/embriología , Pez Cebra/fisiología , Regiones no Traducidas 3'/genética , Animales , Secuencia de Bases , Circulación Sanguínea/efectos de los fármacos , Butadienos/farmacología , Diacetil/análogos & derivados , Diacetil/farmacología , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Células HEK293 , Válvulas Cardíacas/metabolismo , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , MicroARNs/metabolismo , Datos de Secuencia Molecular , Morfolinos/farmacología , Nitrilos/farmacología , Fenotipo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Alineación de Secuencia , Pez Cebra/genética , Proteínas de Pez Cebra/metabolismoRESUMEN
Cardiogenesis proceeds with concomitant changes in hemodynamics to accommodate the circulatory demands of developing organs and tissues. In adults, circulatory adaptation is critical for the homeostatic regulation of blood circulation. In these hemodynamics-dependent processes of morphogenesis and adaptation, a mechanotransduction pathway, which converts mechanical stimuli into biological outputs, plays an essential role, although its molecular nature is largely unknown. Here, we report that expression of zebrafish miR-143 is dependent on heartbeat. Knocking-down miR-143 results in de-repression of retinoic acid signaling, and produces abnormalities in the outflow tracts and ventricles. Our data uncover a novel epigenetic link between heartbeat and cardiac development, with miR-143 as an essential component of the mechanotransduction cascade.
Asunto(s)
Corazón/embriología , Corazón/fisiología , MicroARNs/genética , Organogénesis/genética , Transducción de Señal/genética , Tretinoina/metabolismo , Proteínas de Pez Cebra/genética , Pez Cebra/genética , Animales , Circulación Coronaria/efectos de los fármacos , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , MicroARNs/metabolismo , Modelos Biológicos , Miocardio/metabolismo , Miocardio/patología , Oligonucleótidos Antisentido/farmacología , Organogénesis/efectos de los fármacos , Fenotipo , Retinal-Deshidrogenasa/genética , Retinal-Deshidrogenasa/metabolismo , Transducción de Señal/efectos de los fármacos , Proteínas de Pez Cebra/metabolismoRESUMEN
Synaptogenesis in the neuromuscular junction involves a nicotinic acetylcholine receptor (nAChR) switch and elimination. The microphthalmic mouse (mi/mi) with a mutation in the mitf gene cannot perform occlusal activity, because its teeth do not erupt. The present study attempted to elucidate the contribution of occlusal activity to synaptogenesis in masticatory muscles. In the masseter of the mi/mi, the nAChR elimination initiated, but did not progress normally, after 3 weeks of age, when the occlusal activity emerged in the +/+ mouse, whereas the nAChR switch progressed normally during the entire period of synaptogenesis. The mRNA expression patterns of nAChR subunits in the temporalis and digastric of the mi/mi differed from those in its masseter. These findings suggest that, in the masseter, occlusal activity is essential for the completion of nAChR elimination, but not for the nAChR switch, and that the contribution of occlusal activity to synaptogenesis varies among the masticatory muscles.
Asunto(s)
Oclusión Dental , Músculo Masetero/inervación , Neurogénesis/fisiología , Sinapsis/fisiología , Envejecimiento/patología , Envejecimiento/fisiología , Animales , Peso Corporal , Dieta , Femenino , Inmunohistoquímica , Masculino , Músculo Masetero/anatomía & histología , Ratones , Ratones Mutantes , Factor de Transcripción Asociado a Microftalmía/genética , Microftalmía/genética , Músculo Esquelético/anatomía & histología , Músculo Esquelético/inervación , Mutación/genética , Músculos del Cuello/anatomía & histología , Músculos del Cuello/inervación , Unión Neuromuscular/fisiología , Tamaño de los Órganos , Receptores Nicotínicos/análisis , Receptores Nicotínicos/fisiología , Músculo Temporal/anatomía & histología , Músculo Temporal/inervación , Erupción Dental/fisiologíaRESUMEN
Zebrafish Csrp1 is a member of the cysteine- and glycine-rich protein (CSRP) family and is expressed in the mesendoderm and its derivatives. Csrp1 interacts with Dishevelled 2 (Dvl2) and Diversin (Div), which control cell morphology and other dynamic cell behaviors via the noncanonical Wnt and JNK pathways. When csrp1 message is knocked down, abnormal convergent extension cell movement is induced, resulting in severe deformities in midline structures. In addition, cardiac bifida is induced as a consequence of defects in cardiac mesoderm cell migration. Our data highlight Csrp1 as a key molecule of the noncanonical Wnt pathway, which orchestrates cell behaviors during dynamic morphogenetic movements of tissues and organs.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/fisiología , Proteínas Portadoras/fisiología , Movimiento Celular/fisiología , Proteínas del Citoesqueleto/fisiología , Endodermo/citología , Corazón/embriología , Mesodermo/citología , Fosfoproteínas/fisiología , Proteínas de Pez Cebra/fisiología , Pez Cebra/embriología , Animales , Proteínas Portadoras/biosíntesis , Proteínas Portadoras/genética , Línea Celular , Cisteína/biosíntesis , Proteínas Dishevelled , Endodermo/química , Endodermo/metabolismo , Glicina/biosíntesis , Humanos , Mesodermo/química , Mesodermo/metabolismo , Especificidad de Órganos/genética , Transducción de Señal/genética , Proteínas Wnt/fisiología , Pez Cebra/genética , Pez Cebra/fisiología , Proteínas de Pez Cebra/biosíntesis , Proteínas de Pez Cebra/deficiencia , Proteínas de Pez Cebra/genéticaRESUMEN
Convergent extension (CE) movement of cells is one of the fundamental processes that control the organized morphogenesis of tissues and organs. The molecular events connecting the noncanonical Wnt pathway and CE movement, however, are not well understood. We show that subcellular localization of Daam1, an essential component of noncanonical Wnt signaling, changes dynamically during notochord formation. In the early phases, Daam1 complexes with EphB receptors and Disheveled 2. This complex is incorporated into endocytic vesicles in a dynamin-dependent manner, thereby resulting in the removal of EphB from the cell surface with subsequent switching of cell adhesiveness. In the next step, Daam1 colocalizes with the actin cytoskeleton to induce morphological extension of cells. We elucidate the molecular mechanism underlying the CE movement of notochord cells with Daam1 as a dynamic coordinator of endocytosis and cytoskeletal remodeling.