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，更好地了解有助于调节维持干细胞祖细胞群的分子事件，以及确定决定干细胞进入谱系特异性分化的信号通路，将仍然是生物医学研究中的重要问题。神经嵴细胞是一种多能干细胞，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一直受到阻碍。淀粉原蛋白除了是牙釉质形成过程中不可缺少的结构蛋白外，在细胞分化过程中也起着信号分子的作用。在体内和体外实验中，变原蛋白剪接产物已被证明能够发挥特定的信号传导作用，并诱导细胞分化的变化。我们提出，淀粉原蛋白是一种信号分子，能够调节胚胎干细胞分化到神经嵴细胞的命运，并随后沿着成骨谱系。使用胚胎干细胞，我们将通过执行以下具体目标来验证这一假设：1)使用功能丧失和功能获得实验来确定淀粉原蛋白在指导胚胎干细胞（ES）细胞分化为颅神经嵴（CNC）样多能祖细胞中的生物学功能；II)利用组织重组策略研究胚胎干细胞衍生的颅神经嵴样多能祖细胞向牙源性谱系分化的潜力。胚胎干细胞成功衍生颅神经嵴样多能祖细胞，将为体外神经嵴细胞谱系分析提供新的工具。这些特定目标的结果将用于优化维持干细胞群的策略，同时提高我们刺激修复和再生颅面和骨骼组织中组织和器官缺陷所需的细胞特异性谱系的能力。

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.