Genetic study of heparan sulfate function in development

描述(由申请人提供)：遗传学研究表明，硫酸乙酰肝素蛋白多糖(HSPGs)对细胞表面生长因子的接收、形态原梯度的形成和轴突引导是必不可少的。HSPG在许多不同的生物学环境中发挥作用，但人们对其活动的分子基础知之甚少。我们正在利用果蝇中可用的遗传工具来研究蛋白多糖生物学中的几个悬而未决的问题，包括调节HSPG功能的机制和HSPG的新的发育作用。一个重要但尚未解决的问题是，HSPG对不同配体蛋白功能的特异性是如何产生的。由于N-、2-O-、6-O-和3-O-硫酸盐基团的有序引入，HS链具有明显的多相结构。证据表明，HS的这些“精细结构”控制着细胞表面的离散信号事件。然而，这种控制的分子机制在很大程度上是未知的。我们的目标之一是了解特定的HS精细结构是如何在体内发育过程中产生和发挥作用的。我们研究的另一个目标是确定和探索HSPGs在发育中的新角色。我们先前发现，HSPGs调节发育领域中形态原的梯度形成。我们现在提出了一个新的模型，HSPG也参与了干细胞生态位的形成，这是另一个细胞以严格控制的方式接收位置提示的发育过程。我们的初步研究强烈表明，HSPGs在发育中的卵巢中通过与其在发育翼中的活动不同的作用方式建立生殖系干细胞(GSC)生态位。我们建议阐明HSPGs调控果蝇GSC生态位形成的分子机制。我们的研究还旨在发现新的HS依赖信号。我们的初步数据表明，果蝇HSPGs参与了卵巢中Janus激酶/信号转导和转录激活因子(JAK/STAT)途径。到目前为止，HSPGs参与这一途径的研究从未在任何模型系统中得到证实，尽管已知的果蝇JAK/STAT途径的配基未配对是一种肝素结合蛋白。我们将以果蝇卵子发生为模型，研究HSPGs在这一途径中的作用。我们提出的研究的具体目的是：目的1.探索HS修饰酶在果蝇发育过程中信号转导的分子功能。目的2.探讨HSPGs在果蝇生殖系干细胞生态位中的作用。目的3.确定HSPGs在JAK/STAT通路中的作用。与公共健康相关：硫酸乙酰肝素蛋白多糖(HSPGs)参与多种生物学过程，如生长因子信号、形态原梯度形成和轴突引导。HSPG的正常生物合成中断会导致许多人类遗传性疾病以及癌症的形成。这项研究的长期目标是利用一种遗传上易驯化的模式生物--黑腹果蝇，了解HSPGs在发育过程中功能和生物合成的分子基础。

DESCRIPTION (provided by applicant): Genetic studies have demonstrated that heparan sulfate proteoglycans (HSPGs) are essential for reception of growth factors on the cell surface, formation of morphogen gradients, and axon guidance. HSPGs function in many different biological contexts, yet very little is known about the molecular basis for their activities. We are using the genetic tools available in Drosophila to investigate several outstanding questions in proteoglycan biology, including mechanisms regulating HSPG function and new developmental roles for HSPGs. One important yet unsolved question is how the specificity of HSPG functions for different ligand proteins is generated. HS chains have markedly heterogeneous structures produced by the regulated introduction of N-, 2-O-, 6-O-, and 3-O-sulfate groups. Evidence suggests that these "fine structures" of HS control discrete signaling events at the cell surface. The molecular mechanisms for this control, however, are largely unknown. One of our goals is to understand how specific HS fine structures are generated and function in vivo during development. Another goal of our research is to identify and explore novel roles of HSPGs in development. We previously found that HSPGs regulate the gradient formation of morphogens in the developmental field. We now propose a new model that HSPGs are also involved in the formation of the stem cell niche, another developmental process where cells receive positional cues in a strictly controlled fashion. Our preliminary study strongly suggests that HSPGs are required for the establishment of the germline stem cell (GSC) niche in the developing ovary through a different mode of action from their activity in the developing wing. We propose to elucidate the molecular mechanisms by which HSPGs regulate the formation of the Drosophila GSC niche. Our study also aims to identify novel HS-dependent signaling. Our preliminary data indicate that Drosophila HSPGs participate in the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway in the ovary. The involvement of HSPGs in this pathway has never been demonstrated in any model system to date, although Unpaired, a known ligand of the Drosophila JAK/STAT pathway, is a heparin binding protein. We will investigate the roles of HSPGs in this pathway using Drosophila oogenesis as our model. Our specific aims of the proposed research are: Aim 1. Explore the molecular functions of HS modifying enzymes in signaling during Drosophila development. Aim 2. Explore roles of HSPGs in Drosophila germline stem cell niche. Aim 3. Establish roles of HSPGs in the JAK/STAT pathway. PUBLIC HEALTH RELEVANCE: Heparan sulfate proteoglycans (HSPGs) are involved in a variety of biological processes such as growth factor signaling, morphogen gradient formation, and axon guidance. Disruption of normal HSPG biosynthesis leads to many human genetic diseases as well as cancer formation. The long term goal of this study is to understand the molecular basis for the function and biosynthesis of HSPGs during development using a genetically tractable model organism, Drosophila melanogaster.