Stem cell and regeneration regulatory genes in planarians

描述(由研究人员提供)：项目摘要：行星类扁虫以其能从原始动物的1/300大小的碎片中迅速再生新的头部甚至整个生物体的能力而闻名。脊椎动物的再生涉及干细胞(新生母细胞)，这些干细胞可以产生动物的每一个细胞。尽管几个世纪以来人们一直痴迷于再生，但机械论的解释仍有待阐明。这项提议的广泛、长期的目标是使用有轨生物作为一个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。其具体目标是：1)鉴定新生细胞调节蛋白SMEDWI-2的作用方式；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来确定控制新生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。一种新开发的用于研究行星动物分子遗传学的工具库现已存在。例如，利用RNA干扰(RNAi)进行系统的基因干扰(RNAi)现在是可能的，而脊椎动物的基因组正在进行测序。超过一半的脊椎动物基因在人类基因组中有对应的基因；因此，脊椎动物研究应该识别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。哺乳动物的Piwi类基因调节生殖系干细胞，并可能在癌症中过度表达。目的研究SMEDWI-2(RNAi)动物的新胚子代细胞分化和存活情况，并确定SMEDWI-2的作用部位。AIM#2的实验将确定10个基因在三个过程之一中的作用，这些基因已经被确定为对再生很重要：创伤后的新胚细胞激活、新胚子代细胞分化和/或新胚细胞维持。采用的方法包括RNAi和已建立的新生细胞标记方法。这些基因在再生过程中的表达时间和位置将通过原位杂交和RT-PCR来确定。有了完善的工具和第一次掌握的脊椎动物基因组资源，Aim#3将使用RNAi来识别关键的脊椎动物再生基因。 项目简介：干细胞对公共健康很重要，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，许多再生医学策略建议利用干细胞来取代缺失或不受欢迎的细胞。行星动物提出了一种新的强大的系统来识别现有的调节干细胞再生的分子机制。

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.