Embryonic Stem Cells and Neural Crest Plasticity

描述（由申请人提供）：干细胞生物学将在因疾病或损伤而受损的组织和器官的修复和再生中发挥重要作用。因此，更好地理解用于调节干细胞祖细胞群体的维持的分子事件，以及确定决定干细胞向谱系特异性分化的信号传导途径将仍然是生物医学研究中的重要问题。神经嵴细胞是多能干细胞，在整个胚胎中形成多种组织。由于缺乏体外培养系统，哺乳动物神经嵴命运的确定受到阻碍。釉原蛋白除了是釉质形成不可缺少的结构蛋白外，似乎还作为细胞特化中的信号分子起作用。釉原蛋白剪接产物已被证明在体外和体内发挥特异性信号传导作用并诱导细胞分化的变化。我们认为釉原蛋白是一种信号分子，能够调节胚胎干细胞分化为神经嵴细胞的命运，并随后沿着成骨谱系。本研究以胚胎干细胞为研究对象，通过以下几个方面来验证这一假说：1）通过功能丧失和功能获得实验来确定釉原蛋白在引导胚胎干细胞分化为颅神经嵴样多能祖细胞中的生物学功能; II）使用组织重组策略来检查来源于ES细胞的颅神经嵴样多能祖细胞分化成牙源性谱系的潜力。从胚胎干细胞中成功诱导出颅神经嵴样多能祖细胞，为体外神经嵴细胞谱系分析提供了新的工具。这些特定目标的结果将用于优化维持干细胞群的策略，同时提高我们刺激颅面和骨骼组织中组织和器官缺陷修复和再生所需的细胞特异性谱系发育的能力。

DESCRIPTION (provided by applicant): Stem cell biology will play a significant role in the repair and regeneration of tissues and organs damaged by disease or injury. Therefore a better understanding for the molecular events that serve to regulate maintenance of stem cell progenitor populations, as well as identifying the signaling pathways that determine stem cells into lineage specific differentiation will remain important issues in biomedical research. Neural crest cells are multipotent stem cells that contribute to a diverse array of tissues throughout the embryo. Determination of the fate of mammalian neural crest has been hindered by the lack of an in vitro culture system. Amelogenin besides being a structural protein indispensable for enamel formation appears to also function as a signaling molecule in cell specification. Amelogenin splicing products have been shown to exert specific signaling effects and to induce changes in cell differentiation both in vitro and in vivo. We propose that amelogenin is a signaling molecule capable of modulating embryonic stem cell differentiation to neural crest cell fate and subsequently along osteogenic lineage. Using embryonic stem cells, we will test this hypothesis by executing the following specific aims: I) Using loss-of-function and gain-of-function experiments to determine the biological function of amelogenin in directing embryonic stem (ES) cell differentiation to cranial neural crest (CNC)-like multipotent progenitor cells; II) Using a tissue recombination strategy to examine the potential of cranial neural crest like multipotent progenitor cells derived from ES cells to differentiate to odontogenic lineage. The successful derivation of cranial neural crestlike multipotent progenitor cells from embryonic stem cells will provide a new tool for cell lineage analysis of neural crest in vitro. The results from these specific aims will be used to optimize strategies for maintenance of stem cell populations while improving our ability to stimulate the development of cell specific lineages needed for the repair and regeneration of tissue and organ defects in craniofacial and skeletal tissues.