Control of Cell Proliferation and Differentiation in the Developing Retina

描述（由申请人提供）：该基金的长期目标是阐明细胞内在转录因子和发育信号通路在视网膜发育过程中控制细胞命运特化、细胞增殖和分化的机制。这项调查将使用果蝇作为模型系统进行，因为高功能的保守性的基因和途径控制视网膜发育之间的果蝇和哺乳动物系统，因为容易结合生化，遗传，细胞和发育的方法在飞系统进行体内研究。在果蝇视网膜发育过程中，前神经基因Atonal（ato）的表达对于视网膜祖细胞启动神经元分化至关重要。Ato表达最初由Ato 3'增强子上调，并由Ato 5'增强子细化。对Ato 3'增强子的解剖显示，Ato直接受视网膜决定（RD）网络蛋白Eyeless（Ey）、Eyes absent（Eya）和Sine oculis（So）调节。我们的初步研究表明，Ato 3'增强子也受到bHLH蛋白的正调控和负调控。在形态发生沟（MF）之后，Notch信号通过抑制Ato表达来负调节感光细胞分化，同时促进第二有丝分裂波（SMW）中的S期。我们表明，DA也需要在SMW的S期，并通过CycEdisc增强子，DA和Notch信号调节CycE在SMW的表达。基于我们的初步结果，我们假设不同的bHLH二聚体基于它们与RD蛋白的相互作用参与Ato 3'增强子的激活或抑制。类似地，特异性Da二聚体也基于其与Notch信号传导的相互作用参与SMW中CycEdisc增强子的活化。此外，Ato 3'增强子的激活也为研究RD因子的功能和调控提供了一个良好的体内系统。为了验证这些假设，并使用果蝇系统来表征RD网络蛋白，我们有三个具体的目的：1。描述Da调控Ato 3'增强子的机制。2.使用果蝇模型表征Ey/Pax 6的功能和调节。3.确定Da和Notch信号传导协调SMW中细胞增殖和感光细胞分化控制的机制。从果蝇的这项研究中获得的知识可以应用于哺乳动物系统，并将提供新的机制的见解控制细胞增殖和分化在正常的视网膜发育。了解正常视网膜发育的控制对于最终开发用于预防、诊断和治疗视网膜疾病以及涉及细胞增殖或分化缺陷的其他人类疾病的新方法至关重要。 公共卫生相关性：这项研究将为正常视网膜发育过程中细胞命运的调控、细胞增殖和分化提供新的机制见解。了解正常视网膜发育的控制对于最终开发用于预防、诊断和治疗视网膜疾病的新方法至关重要。

DESCRIPTION (provided by applicant): The long term objective of this grant is to elucidate the mechanisms by which cell intrinsic transcription factors and developmental signaling pathways interact in the control of cell fate specification, cell proliferation, and differentiation during retinal development. This investigation will be carried out using Drosophila as a model system because of the high functional conservations of the genes and pathways controlling retinal development between the Drosophila and the mammalian systems and because of the ease of combining biochemical, genetic, cellular, and developmental approaches in the fly system to carry out in vivo studies. During Drosophila retinal development, expression of the proneural gene Atonal (ato) is critical for retinal progenitor cells to initiate neuronal differentiation. Ato expression is initially upregulated by the Ato 3' enhancer and is refined by the Ato 5' enhancer. Dissection of the Ato 3' enhancer revealed that Ato is directly regulated by retinal determination (RD) network proteins Eyeless (Ey), Eyes absent (Eya), and Sine oculis (So). Our preliminary studies revealed that Ato 3' enhancer is also regulated by bHLH proteins both positively and negatively. Posterior to the morphogenetic furrow (MF), Notch signaling negatively regulates photoreceptor differentiation by inhibiting Ato expression and simultaneously promotes S phase in the second mitotic wave (SMW). We show that Da is also required for S phase in the SMW and that both Da and Notch signaling regulate CycE expression in the SMW through the CycEdisc enhancer. We hypothesize based on our preliminary results that different bHLH dimers are involved in the activation or inhibition of the Ato 3' enhancer based on their interactions with the RD proteins. Similarly specific Da dimers are also involved in the activation of the CycEdisc enhancer in the SMW based on their interactions with the Notch signaling. In addition, the activation of Ato 3' enhancer also provides a nice in vivo system to investigate the function and regulation of RD factors. To test these hypotheses and to use the Drosophila system to characterize the RD network proteins, we have three Specific Aims: 1. Characterize the mechanisms by which Da regulates Ato 3' enhancer. 2. Characterize the function and regulation of Ey/Pax6 using the Drosophila model. 3. Determine the mechanisms by which Da and Notch signaling coordinate the control of cell proliferation and photoreceptor differentiation in the SMW. Knowledge obtained from this study in Drosophila can be applied to the mammalian systems and will provide new mechanistic insights into the control of cell proliferation and differentiation during normal retinal development. Understanding the control of normal retinal development is critical for the eventual development of new approaches for the prevention, diagnosis, and treatment of retinal diseases as well as other human diseases involving cell proliferation or differentiation defect. PUBLIC HEALTH RELEVANCE: This research will provide new mechanistic insights into the control of cell fate specification, cell proliferation and differentiation during normal retinal development. Understanding the control of normal retinal development is critical for the eventual development of new approaches for the prevention, diagnosis, and treatment of retinal diseases.