Stem cell proliferation and differentiation in planaria

描述（由申请人提供）：人类多能干细胞系的建立导致了对干细胞生物学的兴趣的复苏。这种兴趣主要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，许多关于干细胞生物学的基本问题需要解决。其中包括：如何在体内调节干细胞增殖以产生适当数量的子干细胞和分化后代而不形成肿瘤？干细胞的发育潜力是如何受到特定命运的限制的？多能性是如何维持的？哪些步骤会导致多能性的丧失？这里提出的工作将利用淡水涡虫施密特地中海作为研究干细胞调节的模式生物来解决这些基本问题。纯涡虫——再生实验的经典模型，可以用身体的小碎片再生整个动物。这种显著的可塑性是基于成虫体内存在的干细胞群。这些干细胞既可以用来替换在细胞更替过程中丢失的细胞，也可以在动物被横切时再生缺失的结构。最近的进展允许这个经典系统在细胞和分子水平上被详细地重新检查。因此，环境对干细胞增殖的影响将通过分析完整和再生涡虫的细胞周期动力学来研究。这些实验将确定伤害是否调节涡虫干细胞的细胞周期。如果确实如此，这些实验也将定义受调控的细胞周期阶段，这是理解从损伤到增殖的信号通路的重要考虑因素。自动化原位杂交技术的发展和超过4000种独特的涡虫cdna的可用性为定义干细胞特异性基因和提高单克隆抗体以鉴定和研究干细胞提供了起始材料。最后，使用双链rna介导的遗传干扰的功能分析将用于鉴定在干细胞调节中起关键作用的基因。

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.