The molecular basis of planarian regeneration

描述(由申请人提供)：我们的目标是识别和功能表征支持后生动物再生的基因和遗传途径。我们建议使用海洋浮游生物Schmidtea Mediterranea作为一个模型系统来解决这个问题，因为它是最简单的头化双侧动物之一，具有复杂的器官系统，显示出广泛的再生能力：被斩首的动物将在不到一周的时间内再生并将新的头部功能整合到先前存在的组织中。此外，如此显著的发育可塑性是由大量的、实验上可获得的全能干细胞群所驱动的，这种全能干细胞被称为新生母细胞。在上一次资助期间，在询问基因功能和测量再生反应方面取得的进展，加上地中海链霉菌基因组的测序和最近的注释，创造了一个前所未有的机会，从分子和功能基因组的角度来阐述动物再生的问题。我们建议充分利用行星动物提供的吞吐能力和生物可塑性来建立一个详细的再生分子图景。我们建议：1)使用高密度DNA阵列进行全基因组、高时间分辨率的再生分析；2)在组织内稳态和再生的成人背景下测试关键的、进化上保守的胚胎信号通路的功能，为解释微阵列实验提供功能基础；3)进行器官特异性再生的筛选，以确定普遍存在的再生事件中存在的分子专门化的调节程度和程度。总而言之，这些研究应该为我们提供到目前为止进行的最全面的再生机制研究，并作为正式测试动物之间再生的进化分歧或趋同的平台，这是阻碍在哺乳动物等再生不良者中实施合理的再生疗法的一个中心未解决的方面。公共卫生相关性：该项目的首要目标是为动物再生过程确定一个机械基础。该项目利用已测序的稻纵卷蛾基因组，以及在上一次资助期间获得的方法学进展和发现：1)确定高时间分辨率、全基因组范围的再生表达谱；2)在成体组织再生和动态平衡的背景下询问已知胚胎信号通路的功能；以及3)发现参与成年器官截肢后再生的基因。所有这三条研究路线相互协同，它们的整合应该为我们提供一套高分辨率的分子过程来调节再生和再生能力。事实上，我们的项目已经开始发现已知基因在成人环境中的新功能，并定义许多保守的动物基因的功能，这些基因的功能尚不清楚。鉴于浮游生物和脊椎动物之间存在着高度的进化保守，对浮游生物基因功能的表征将推动研究人类干细胞功能、再生和伤口愈合的努力，有效地促进这些人类健康的前沿。

DESCRIPTION (provided by applicant): Our objective is to identify and functionally characterize the genes and genetic pathways underpinning metazoan regeneration. We propose to use the planarian Schmidtea mediterranea as a model system to address this problem because it is among the simplest cephalized bilaterians with complex organ systems that display extensive regenerative capacities: a decapitated animal will regenerate and functionally integrate a new head to the pre-existing tissues in under a week. In addition, such remarkable developmental plasticity is driven by an abundant and experimentally accessible population of totipotent stem cells known as neoblasts. The advances made during the last period of funding to interrogate gene function and measure regenerative responses, combined with the sequencing and recent annotation of the S. mediterranea genome create an unprecedented opportunity to frame the problem of animal regeneration in molecular and functional genomic terms. We propose to take full advantage of the throughput capacity and biological plasticity afforded by planarians to establish a detailed molecular landscape of regeneration. We propose to: 1) carry out genome- wide, high temporal resolution analyses of regeneration using high density DNA arrays; 2) test the functions of key, evolutionarily conserved embryonic signaling pathways in the adult contexts of tissue homeostasis and regeneration to provide a functional basis for interpreting the microarray experiments; and 3) to carry out screens of organ-specific regeneration to determine the regulatory extent and degree of molecular specialization that exists in general regenerative events. Combined, these studies should provide us with the most comprehensive mechanistic study of regeneration performed to date, and should serve as a platform to formally test the evolutionary divergence or convergence of regeneration among animals, a central unresolved aspect hindering the implementation of rational regenerative therapeutics in poor regenerators such as mammals. PUBLIC HEALTH RELEVANCE: The overarching goal of this project is to define a mechanistic basis for the process of animal regeneration. This project takes advantage of the sequenced genome of the planarian Schmidtea mediterranea, and of the methodological advances and findings obtained during the last funding period to: 1) define a high temporal resolution, genome- wide, expression profile of regeneration; 2) interrogate the functions of known embryonic signaling pathways in the adult contexts of tissue regeneration and homeostasis; and 3) uncover genes involved in the regeneration of adult organs after amputation. All three lines of investigation synergize with each other and their integration should provide us with a high resolution set of molecular processes regulating regeneration and regenerative capacities. In fact, our project has begun to uncover novel functions in adult contexts of known genes, and to define functions for the many conserved animal genes for which functions are still unknown. Given the high degree of evolutionary conservation that exists between planarians and vertebrates, the characterization of gene functions in planarians will advance efforts to study human stem-cell function, regeneration and wound healing, effectively advancing these frontiers of human health.