RESUMEN
p63, a member of the p53 family, is essential for skin morphogenesis and epithelial stem cell maintenance. Here, we report an unexpected role of TAp63 in cardiogenesis. p63 null mice exhibit severe defects in embryonic cardiac development, including dilation of both ventricles, a defect in trabeculation and abnormal septation. This was accompanied by myofibrillar disarray, mitochondrial disorganization, and reduction in spontaneous calcium spikes. By the use of embryonic stem cells (ESCs), we show that TAp63 deficiency prevents expression of pivotal cardiac genes and production of cardiomyocytes. TAp63 is expressed by endodermal cells. Coculture of p63-knockdown ESCs with wild-type ESCs, supplementation with Activin A, or overexpression of GATA-6 rescue cardiogenesis. Therefore, TAp63 acts in a non-cell-autonomous manner by modulating expression of endodermal factors. Our findings uncover a critical role for p63 in cardiogenesis that could be related to human heart disease.
Asunto(s)
Diferenciación Celular/fisiología , Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Corazón/embriología , Fosfoproteínas/metabolismo , Transactivadores/metabolismo , Animales , Diferenciación Celular/genética , Línea Celular , Células Madre Embrionarias/ultraestructura , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Factor de Transcripción GATA6/genética , Factor de Transcripción GATA6/metabolismo , Proteínas HMGB/genética , Proteínas HMGB/metabolismo , Corazón/crecimiento & desarrollo , Immunoblotting , Ratones , Ratones Noqueados , Microscopía Electrónica de Transmisión , Fosfoproteínas/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Transcripción SOXF/genética , Factores de Transcripción SOXF/metabolismo , Transactivadores/genéticaRESUMEN
In the adult, the heart rate is driven by spontaneous and repetitive depolarizations of pacemaker cells to generate a firing of action potentials propagating along the conduction system and spreading into the ventricles. In the early embryo before E9.5, the pacemaker ionic channel responsible for the spontaneous depolarization of cells is not yet functional. Thus the mechanisms that initiate early heart rhythm during cardiogenesis are puzzling. In the absence of a functional pacemaker ionic channel, the oscillatory nature of inositol 1,4,5-trisphosphate (InsP3)-induced intracellular Ca2+ signaling could provide an alternative pacemaking mechanism. To test this hypothesis, we have engineered pacemaker cells from embryonic stem (ES) cells, a model that faithfully recapitulates early stages of heart development. We show that InsP3-dependent shuttle of free Ca2+ in and out of the endoplasmic reticulum is essential for a proper generation of pacemaker activity during early cardiogenesis and fetal life.