Developmental reprogramming and transorganogenesis

 描述（由申请人提供）：拟议研究的主要目标是阐明控制体内发育和分化细胞可塑性的细胞和分子机制，并研究有丝分裂后分化细胞如何转分化和重塑为新的细胞类型。C.内胚层发育的成熟途径。elegans将被应用于转分化和“transorganogenesis”（一个器官转化为另一个器官）的分子解剖。该途径中的一种组分，ELT-7 GATA型转录因子，能够超越胚胎多能性定型转换（“MCT”），其通常将细胞锁定在其分化状态并防止它们被重编程。ELT-7可以使成人中分化的咽细胞重塑为具有肠细胞的超微结构特征和基因表达模式的细胞，而不需要去分化中间体或细胞分裂的干预。ELT-7还可以将发育中的子宫和输精管转化为“迷你肠”，其显示出典型的精细结构肠形态，并且可以物理分离。有了这些初步的发现，我们将通过三个特定的目标来探讨转分化的机制。在目标1中，我们将评估ELT-7靶向子宫的特异性，并将通过分析转分化器官和分离的“小肠”转录谱来检验子宫肠transorganogenesis涉及性腺基因阻遏的叠加和正常肠发育的重演的假设。“我们将研究转分化过程中细胞重塑的机制，包括蛋白质降解的要求，并将测试ELT-7的离散结构域允许其促进转分化的能力的假设。在目标2中，我们将研究细胞自主调节因子的作用，包括PHA-4/FoxA，内胚层级联中的基因，和iPS促进基因，以及细胞-细胞信号传导过程，包括Notch，EGF/ras和细胞融合，在调节转分化的易感性。在目标3中，我们将通过经典和功能基因组学（基于RNA干扰）筛选和直接遗传选择对调节重编程的分子成分进行全面分析，并与我们的合作者一起测试C的一般性。在斑马鱼脊椎动物模型和人类成纤维细胞重编程为iPS细胞中的线虫转分化机制。这些研究可能会促进我们对消化道癌前化生机制的理解。它们还可能导致产生患者特异性替代器官的方法和其他推进再生医学的策略，并将提供对出生缺陷器官畸形机制的见解。

 DESCRIPTION (provided by applicant): The major objectives of the proposed research are to illuminate the cellular and molecular mechanisms that control plasticity of developing and differentiated cells in vivo and to investigate how post-mitotic differentiated cells can be transdifferentiated and remodeled into new cell types. The well-elucidated pathway for endoderm development in C. elegans will be applied to the molecular dissection of transdifferentiation and "transorganogenesis" (conversion of one organ into another). One component in this pathway, the ELT-7 GATA-type transcription factor, is capable of overriding the embryonic multipotency commitment transition ("MCT"), which normally locks cells into their differentiated states and prevents them from being reprogrammed. ELT-7 can cause differentiated pharynx cells in adults to be remodeled into cells with ultrastructural characteristics, and gene expression patterns, of intestinal cells, without intercession of a dedifferentiated intermediate or cell division. ELT-7 can also convert the developing uterus and vas deferens into "mini-guts," which show typical fine-structure gut morphology and that can be physically isolated. With these preliminary findings in hand, we will probe the mechanisms of transdifferentiation through three Specific Aims. In Aim 1, we will evaluate the specificity of targeting ELT-7 to the uterus and will test the hypothesis that uterus gut transorganogenesis involves superimposition of gonadal gene repression and recapitulation of normal gut development through analysis of transdifferentiated organs and transcriptional profiling of isolated "mini-guts." We will investigate the mechanisms of cellular remodeling during transdifferentiation, including the requirement for protein degradation, and will test the hypothesis that a discrete domain of ELT-7 allows for its ability to promote transdifferentiation. In Aim 2, we will investigate the role of cell-autonomous regulators, including PHA-4/FoxA, genes in the endoderm cascade, and iPS-promoting genes, as well cell-cell signaling processes, including Notch, EGF/ras and cell fusion, in modulating susceptibility to transdifferentiation. In Aim 3, we will undertake a comprehensive analysis of molecular components that regulate reprogramming by classical and functional genomics (RNAi-based) screens and direct genetic selections and, with our collaborators, will test the generality of the C. elegans transdifferentiation mechanisms in the zebrafish vertebrate model and in reprogramming of human fibroblasts to iPS cells. These studies may advance our understanding of the mechanisms involved in pre-cancerous metaplasias of the digestive tract. They could also lead to methods for generating patient-specific replacement organs and other strategies that advance regenerative medicine, and will provide insights into the mechanisms of organ malformation in birth defects.