Control of cell number in developing retina

视网膜发育中细胞数量的控制

• 批准号: 8509133
• 负责人: DUOJIA PAN
• 金额: $ 9.18万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8509133
• 关键词: Animals; Apical; Apoptosis; Atrophic; Biochemical; Biological; Cell Count; Cell Cycle; Cell Death; Cell Differentiation process; Cell Nucleus; Cell Proliferation; Cell Surface Receptors; Cells; Complex; Cyclin E; DNA Binding; DNA-Protein Interaction; Development; Drosophila genus; Epithelial Cells; Event; Exclusion; Experimental Models; Eye; Eye Development; Family; Fatty acid glycerol esters; Gene Expression; Gene Targeting; Genetic; Genetic Screening; Genetic Transcription; Goals; Grant; Growth; Homologous Gene; Laboratories; Lead; Link; Mediating; Molecular; Molecular Genetics; Neurofibromin 2; Nuclear; Organ; Organ Size; Output; Pathway interactions; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Play; Process; Proteins; RNA Interference; Regulation; Research; Retina; Retinal Diseases; Role; Scallop; Signal Pathway; Signal Transduction; Specific qualifier value; Tertiary Protein Structure; Testing; Therapeutic Intervention; Tissues; Transcription Coactivator; Transcriptional Regulation; Tumor Suppressor Genes; Tumor Suppressor Proteins; Work; apical membrane; base; cell type; compound eye; design; extracellular; genome-wide; human disease; imaginal disc; inhibitor/antagonist; insight; novel; overexpression; programs; protein complex; public health relevance; response; tool; transcription factor; tumorigenesis

DESCRIPTION (provided by applicant): The long-term scientific goal of my laboratory is to understand the molecular mechanisms that specify retina cell number. Using the compound eye of Drosophila as an experimental model, my laboratory has discovered a novel signaling pathway, the Hippo pathway, which controls retina cell number by coordinately regulating cell proliferation and cell death. Work from my laboratory in the last project period has allowed us to delineate a Hippo kinase cascade comprised of the Ste20-like kinase Hippo (Hpo), the NDR family kinase Warts (Wts), and the transcriptional co activator Yorkie (Yki). Hpo phosphorylates and activates Wts, which in turn, inactivates Yki by phosphorylating the latter at a critical residue (S168) and excluding it from the nucleus, where it normally functions as a co activator for the TEAD/TEF family transcription factor Scalloped (Sd). The Hippo pathway promotes cell death and restricts cell proliferation through the transcriptional regulation of target genes such as the cell cycle regulator cyclin E and the cell death inhibitor diap1. The mammalian homologues of Hpo, Sav, Wts and Yki constitute an analogous kinase cascade and that the mammalian Hippo pathway plays a conserved role in organ size control. Most recently, we have discovered Kibra (Kbr) as a novel tumor suppressor that functions together with Merlin (Mer) and the related FERM domain protein Expanded (Ex) to regulate the Hippo kinase cascade. Since signaling events upstream of Hpo still remain poorly defined, our identification of this novel protein complex provides new opportunities to investigate this less understood aspect of the Hippo signaling pathway. In the coming project period, we propose to build on these findings to further elucidate the composition, function and regulation of the Hippo pathway, through the following lines of research. First, we aim to define a complete Hippo signaling pathway that relays information from the extracellular milieu to Yki phosphorylation by conducting a genome-wide RNAi screens and genetic screens for additional components of the Hippo pathway. Second, we will identify the missing DNA-binding transcription factor(s) that regulates Hippo target gene transcription, since our previous characterization of Sd and Yki suggests that Yki may partner with additional DNA-binding transcription factors to regulate the expression of Hippo target genes. We will test this hypothesis by conducting systematic protein-protein and protein-DNA interaction screens. Lastly, we will investigate the molecular and cellular mechanisms by which the Kbr-Ex-Mer complex functions within the Hippo pathway. Besides revealing fundamental mechanisms of eye development, the proposed studies will have general implications for the development of other tissues. PUBLIC HEALTH RELEVANCE: The proposed studies will not only allow us to elucidate the basic molecular mechanism that regulates retina cell number, but also provide general insights into how cell number is determined in other organs during animal development and how aberrant regulation of this process could lead to tissue atrophy or tumorigenesis. Such insights may facilitate the therapeutic interventions of relevant human diseases, including diseases of the retina.

描述（由申请人提供）：我实验室的长期科学目标是了解指定视网膜细胞数量的分子机制。利用果蝇复眼作为实验模型，我的实验室发现了一种新的信号通路，即Hippo通路，它通过协调调节细胞增殖和细胞死亡来控制视网膜细胞数量。在上一个项目期间，我的实验室的工作使我们能够描绘出一个由Ste 20样激酶Hippo（Hpo），NDR家族激酶Warts（Wts）和转录共激活因子Yorkie（Yki）组成的Hippo激酶级联。Hpo磷酸化并激活Wts，Wts又通过在关键残基（S168）磷酸化Wts并将其从细胞核中排除而使Yki失活，在细胞核中它通常作为TEAD/TEF家族转录因子Scalloped（Sd）的共激活剂发挥作用。Hippo通路通过转录调节靶基因如细胞周期调节因子细胞周期蛋白E和细胞死亡抑制因子diap 1促进细胞死亡并限制细胞增殖。Hpo、Sav、Wts和Yki的哺乳动物同源物构成类似的激酶级联，并且哺乳动物Hippo途径在器官大小控制中起保守作用。最近，我们发现Kibra（Kbr）是一种新型的肿瘤抑制因子，它与Merlin（Mer）和相关的FERM结构域蛋白Expanded（Ex）一起调节Hippo激酶级联反应。由于Hpo上游的信号传导事件仍然定义不清，我们对这种新型蛋白复合物的鉴定为研究Hippo信号传导途径的这一鲜为人知的方面提供了新的机会。在接下来的项目期间，我们建议在这些发现的基础上，通过以下研究路线进一步阐明Hippo通路的组成，功能和调控。首先，我们的目标是定义一个完整的Hippo信号通路，通过进行全基因组RNAi筛选和Hippo通路其他组分的遗传筛选，将细胞外环境的信息传递到Yki磷酸化。其次，我们将确定缺失的DNA结合转录因子，调节Hippo靶基因的转录，因为我们以前的Sd和Yki的表征表明，Yki可能与其他DNA结合转录因子合作，以调节Hippo靶基因的表达。我们将通过进行系统的蛋白质-蛋白质和蛋白质-DNA相互作用筛选来验证这一假设。最后，我们将研究Kbr-Ex-Mer复合物在Hippo通路中发挥作用的分子和细胞机制。除了揭示眼睛发育的基本机制外，拟议的研究将对其他组织的发育产生普遍影响。 公共卫生关系：拟议的研究将不仅使我们能够阐明调节视网膜细胞数量的基本分子机制，而且还提供了在动物发育过程中细胞数量如何在其他器官中确定以及该过程的异常调节如何导致组织萎缩或肿瘤发生的一般见解。这样的见解可以促进相关人类疾病（包括视网膜疾病）的治疗干预。