Stem cell proliferation and differentiation in planaria

描述(申请人提供)：人类多潜能干细胞系的建立重新引起了人们对干细胞生物学的兴趣。这种兴趣在很大程度上是由于干细胞在修复退行性疾病和损伤方面的治疗潜力。在人类干细胞研究的最新突破能够有效和安全地应用于临床之前，需要解决许多关于干细胞生物学的基本问题。这些问题包括：如何在体内调节干细胞增殖，以在不形成肿瘤的情况下产生适当数量的子代干细胞和分化后代？干细胞的发展潜力是如何受到特定命运的限制的？多潜能是如何维持的，哪些步骤会导致多潜能的丧失？这里提出的工作将解决这些基本问题，使用淡水浮游动物施密特地中海作为研究干细胞调节的模式生物。行星动物--再生实验的经典模型可以从动物身体的一小块碎片再生出整个动物。这种非凡的可塑性是基于成虫体内存在的干细胞群。这些干细胞既被用来取代细胞周转过程中丢失的细胞，也被用来在动物被横切时再生缺失的结构。最近的进展使这一经典系统能够在细胞和分子水平上进行详细的重新检查。因此，环境对干细胞增殖的影响将通过分析完整和再生的浮游生物的细胞周期动力学来研究。这些实验将确定创伤是否调节了脊椎动物干细胞的细胞周期。如果是这样的话，这些实验还将定义细胞周期的调控阶段，这是理解从损伤到增殖的信号通路的一个重要考虑因素。自动化原位杂交技术的发展和4000多个独特的脊椎动物cDNA的可获得性为定义干细胞特异性基因和提高单抗以识别和研究干细胞提供了起点材料。最后，将使用双链RNA介导的遗传干扰进行功能分析，以确定在STRY细胞调节中发挥关键作用的基因。

DESCRIPTION (provided by applicant): The establishment of human pluripotential stem cell lines has led to a resurgence of interest in stem cell biology. This interest is largely due to the therapeutic potential of stem cells for repairing degenerative diseases and injuries. Before recent breakthroughs in studies of human stem cells can be effectively and safely applied in the clinic, many basic questions about the biology of stem cells need to be addressed. These include: how is stem cell proliferation regulated in vivo to generate the appropriate number of daughter stem cells and differentiating progeny without forming tumors? How is the developmental potential of a stem cell restricted to a particular fate? How is pluripotentiality maintained and what steps lead to loss of pluripotentiality? The work proposed here will address these fundamental questions using the freshwater planarian, Schmidt Mediterranean, as a model organism for studying stem cell regulation. Planarians- classic models of regeneration experiments can regenerate entire animals from small fragments of their bodies. This remarkable plasticity is based upon a stem cell population present in the adult worm. These stem cells are used both to replace cells lost during the course of cell turnover and to regenerate missing structures when the animal is transected. Recent advances permit this classic system to be re-examined in detail at both cellular and molecular levels. Thus, environmental influences on stem cell proliferation will be studied by analyzing cell cycle kinetics in intact and regenerating planarians. These experiments will determine if wounding regulates the cell cycle of planarian stem cells. If it does, these experiments will also define the phases of the cell cycle that are regulated, an important consideration for understanding the signaling pathways that lead from wounding to proliferation. The development of automated in situ hybridization techniques and the availability of over 4000 unique planarian cDNAs provide starting material for defining stem cell-specific genes and raising monoclonal antibodies to identify and study stem cells. Finally, functional analysis using double-stranded RNA-mediated genetic interference will be used to identify genes that play critical roles in stern cell regulation.