Stem cell and regeneration regulatory genes in planarians

Planarian扁形虫以其快速再生新头部甚至整个生物体的能力而闻名，这些能力来自原始动物大小的1/300。Planarian再生涉及产生动物每个细胞的干细胞（neoblast）。尽管几个世纪以来对再生的迷恋，机械的解释仍有待阐明。这项提议的广泛的长期目标是使用真涡虫作为模型系统来识别和理解调节干细胞以促进再生的分子机制。具体目标是1）表征新成细胞调节SMEDWI-2蛋白的作用模式，2）确定先前确定为再生所需的基因的功能，以及3）利用RNAi筛选策略和基因组资源来鉴定控制新成细胞再生的关键基因。干细胞和再生生物学是再生医学最近和强烈兴趣的主题。此外，干细胞的失调可能是许多类型癌症的核心。一个新开发的武器库的分子遗传学研究的涡虫现在存在。例如，RNA干扰（RNAi）的系统性基因干扰现在是可能的，并且Planarian基因组正在测序。超过一半的涡虫基因在人类基因组中有对应的基因，因此，涡虫研究应该确定保守的干细胞调控基因。SMEDWI-2类似于PIWI样RNA结合蛋白，在新成细胞中表达，并且是再生所需的。哺乳动物piwi样基因调节生殖系干细胞，并可在癌症中过度表达。目的#1将检查smedwi-2（RNAi）动物中的新生细胞子代细胞分化和存活，并表征SMEDWI-2作用的位点。目标#2的实验将鉴定十个基因的作用，这些基因已经被确定为在三个过程之一中对再生是重要的：创伤后的成新细胞活化、成新细胞后代细胞分化和/或成新细胞维持。所采用的方法包括RNAi和已建立的新生细胞标记方法。这些基因在再生中的表达时间和位点将通过原位杂交和RT-PCR来确定。随着先进的工具和第一次掌握的Planarian基因组资源，目标#3将使用RNAi来识别关键的Planarian再生基因。 项目叙述：干细胞对公众健康很重要，因为它们对组织的生长和维持至关重要，并且是许多癌症的核心。此外，许多再生医学策略提出利用干细胞来替代缺失或不需要的细胞。Planarians提出了一个新的和强大的系统，以确定现有的分子机制，调节干细胞再生。

DESCRIPTION (provided by investigator): Project Summary Planarian flatworms are famous for their ability to rapidly regenerate new heads or even entire organisms from a fragment 1/300th the size of the original animal. Planarian regeneration involves stem cells (neoblasts) that produce every cell of the animal. Despite centuries of fascination with regeneration, mechanistic explanations await elucidation. The broad, long-term objectives of this proposal are to use planarians as a model system to identify and understand the molecular mechanisms that regulate stem cells to promote regeneration. The specific aims are 1) to characterize the mode of action of the neoblast regulatory SMEDWI-2 protein, 2) to determine the function of genes previously determined to be needed for regeneration, and 3) to utilize RNAi screening strategies and genome resources to identify the key genes that control neoblasts for regeneration. Stem cells and regenerative biology are the subjects of recent and intense interest for regenerative medicine. In addition, the misregulation of stem cells may be central to many types of cancer. A newly developed arsenal of tools for molecular genetic study of planarians now exists. For example, systematic gene perturbation with RNA interference (RNAi) is now possible and the planarian genome is being sequenced. Greater than half of planarian genes have counterparts in the human genome; therefore, planarian studies should identify conserved stem cell regulatory genes. SMEDWI-2 is similar to PIWI-like RNA binding proteins, expressed in neoblasts, and needed for regeneration. Mammalian piwi-like genes regulate germline stem cells and can be overexpressed in cancers. Aim #1 will examine neoblast progeny cell differentiation and survival in smedwi-2(RNAi) animals and characterize the site of SMEDWI-2 action. Experiments of Aim #2 will identify roles for ten genes, which have been already determined to be important for regeneration, in one of three processes: neoblast activation following wounding, neoblast progeny cell differentiation, and/or neoblast maintenance. Methods employed include RNAi and established neoblast labeling approaches. The time and site of expression of these genes in regeneration will be determined with in situ hybridizations and RT-PCR. With well-developed tools and planarian genome resources now in hand for the first time, Aim #3 will use RNAi to identify key planarian regeneration genes. Project Narrative: Stem cells are important for public health because they are essential for the growth and maintenance of tissues and lie at the heart of many cancers. Additionally, many regenerative medicine strategies propose the utilization of stem cells to replace missing or undesirable cells. Planarians present a new and powerful system to identify existing molecular mechanisms that regulate stem cells for regeneration.