ABSTRACT
Eph receptors and their ligands, ephrins, are abundantly expressed in neuroepithelial cells of the early embryonic brain. Overstimulation of Eph signaling in vivo increases apoptotic cell death of neuroepithelial cells, whereas null mutation of the Eph gene leads to the development of a larger brain during embryogenesis. Thus, it appears that Eph-ephrin signaling plays a role in regulating apoptotic cell death of neuroepithelial cells, thereby influencing brain size during embryonic development. Interestingly, Eph-ephrin signaling is bi-directional, with forward signaling from ephrin- to Eph-expressing cells and reverse signaling from Eph- to ephrin-expressing cells. However, it is not clear whether this forward or reverse signaling plays a role in regulating the size of the neuroepithelial cell population during early brain development. Also, Eph receptors and their corresponding ligands are mutually exclusive in their expression domains, and they encounter each other only at interfaces between their expression domains. This expression pattern may be a critical mechanism for preventing overstimulation of Eph-ephrin signaling. Nevertheless, Eph receptors are co-expressed with their corresponding ligands in certain brain regions. Recently, two studies demonstrated that brain region-specific apoptosis may be triggered by the overlapping expression of Eph and ephrin, a theme that will be explored in this mini-review.
Subject(s)
Female , Pregnancy , Apoptosis , Brain , Cell Death , Embryonic Development , Ephrins , Ligands , Neuroepithelial Cells , Receptor, EphA1 , Receptors, Eph FamilyABSTRACT
Today we know from studies in social sciences and developmental neurobiology that the environment in the early years of human development sets trajectories for health (physical and mental), learning, and behavior throughout life. We now understand how experience in early life regulates the function of normal genes. Gene functions set in early life are difficult to change. Some societies are beginning to appreciate the importance of early human development for the future quality of their population. Initiatives should be in place that are compatible with the recommendations in chapter 5 of the WHO Commission Report on the Social Determinants of Health. To do this, we must provide equity from the start.
En la actualidad sabemos, a partir de estudios en ciencias sociales y en neurobiología del desarrollo, que el medio ambiente en los primeros años del desarrollo humano determina el comportamiento de la salud (física y mental), el aprendizaje y el comportamiento del individuo para toda la vida. También entendemos cómo la experiencia regula, durante los primeros años de vida, la función de los genes normales. Las funciones de los genes determinadas en los primeros años de vida son muy difíciles de cambiar. Algunas sociedades están comenzando a valorar la importancia del desarrollo humano temprano para la calidad futura de su población. Las iniciativas deben ser compatibles con las recomendaciones presentes en el Capítulo 5 del Informe de la Comisión de la OMS sobre los Factores Determinantes de la Salud. Para lograrlo, debemos proveer equidad desde el principio.
Hoje em dia, nós sabemos a partir dos estudos nas ciências sociais e na neurobiologia do desenvolvimento que o ambiente dos primeiros anos de desenvolvimento humano determina as trajetórias para a saúde (física e mental), a aprendizagem e o comportamento durante toda a vida. Compreendemos agora como a experiência da infância regula a função dos genes normais. As funções dos genes determinadas na infância são muito difíceis de trocar. Algumas sociedades estão começando a apreciar a importância do desenvolvimento humano na infância na qualidade futura das populações. As iniciativas deveriam ser compatíveis com as recomendações estabelecidas no Capítulo 5 do Relatório da Comissão da OMS sobre os Determinantes Sociais da Saúde. Para fazer isto, devemos fornecer eqüidade desde o principio.