Genetic study of heparan sulfate function in development

描述（由申请人提供）：遗传学研究表明，硫酸乙酰肝素蛋白聚糖（HSPG）对于细胞表面生长因子的接收、形态发生梯度的形成和轴突导向至关重要。HSPGs在许多不同的生物学背景下发挥作用，但对其活性的分子基础知之甚少。我们正在使用果蝇的遗传工具来研究蛋白多糖生物学中的几个突出问题，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功能对不同配体蛋白的特异性是如何产生的。HS链具有明显的异质性结构，通过调节引入N-、2-O-、6-O-和3-O-硫酸酯基团而产生。有证据表明，HS的这些“精细结构”控制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精细结构是如何产生的，并在体内发育过程中发挥作用。我们研究的另一个目标是识别和探索HSPGs在发育中的新作用。我们以前发现，HSPGs调节梯度形成的形态发生在发育领域。我们现在提出了一个新的模型，即HSPGs也参与了干细胞龛的形成，这是另一个发育过程，细胞以严格控制的方式接受位置线索。我们的初步研究强烈表明，HSPGs是必需的生殖干细胞（GSC）的小生境在发展中的卵巢通过不同的模式，从他们的活动在发展中的翅膀。我们建议阐明HSPGs调节果蝇GSC生态位形成的分子机制。我们的研究还旨在识别新的HS依赖性信号。我们的初步数据表明，果蝇HSPGs参与卵巢Janus激酶/信号转导和转录激活因子（JAK/STAT）途径。迄今为止，HSPG参与该途径从未在任何模型系统中得到证实，尽管果蝇JAK/STAT途径的已知配体Unpaired是肝素结合蛋白。我们将以果蝇卵子发生为模型研究HSPGs在这一通路中的作用。我们的具体目标的拟议研究是：目标1。探索果蝇发育过程中HS修饰酶在信号转导中的分子功能。目标2.探讨HSPGs在果蝇生殖系干细胞生态位中的作用。目标3：确定HSPG在JAK/STAT通路中的作用。公共卫生相关性：硫酸乙酰肝素蛋白聚糖（HSPG）参与多种生物过程，如生长因子信号传导、形态发生梯度形成和轴突导向。正常HSPG生物合成的破坏导致许多人类遗传疾病以及癌症形成。本研究的长期目标是了解HSPGs在发育过程中的功能和生物合成的分子基础，使用遗传上易处理的模式生物，果蝇。

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.