Stem cell and regeneration regulatory genes in planarians

描述（由研究者提供）：项目概述涡虫以其快速再生新头部甚至整个生物体的能力而闻名，它们的碎片只有原动物大小的1/300。涡虫再生涉及产生动物所有细胞的干细胞（新生细胞）。尽管几个世纪以来人们一直对再生着迷，但机械的解释仍有待阐明。本研究的长远目标是利用涡虫作为一个模型系统来识别和理解调节干细胞促进再生的分子机制。具体目的是1)表征新母细胞调控蛋白SMEDWI-2的作用模式，2)确定先前确定的再生所需基因的功能，3)利用RNAi筛选策略和基因组资源鉴定控制新母细胞再生的关键基因。干细胞和再生生物学是近年来再生医学研究的热点。此外，干细胞的失调可能是许多类型癌症的核心。现在存在一种新开发的用于涡虫分子遗传学研究的工具库。例如，用RNA干扰（RNAi）进行系统的基因扰动现在是可能的，涡虫基因组正在测序。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，在新生细胞中表达，是再生所必需的。哺乳动物piwi样基因调控生殖系干细胞，可在癌症中过度表达。目的1将检测smedwi-2（RNAi）动物中新母细胞后代细胞的分化和存活，并表征smedwi-2的作用部位。Aim #2的实验将确定10个基因的作用，这些基因已经被确定为再生的重要基因，在三个过程中的一个：损伤后的新母细胞激活，新母细胞后代细胞分化和/或新母细胞维持。采用的方法包括RNAi和已建立的新母细胞标记方法。这些基因在再生中的表达时间和位置将通过原位杂交和RT-PCR来确定。有了发达的工具和首次掌握的涡虫基因组资源，Aim #3将使用RNAi来鉴定关键的涡虫再生基因。

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.