Genetic study of heparan sulfate function in development

描述（由申请人提供）：遗传学研究表明，硫酸肝素蛋白多糖（HSPGs）对于细胞表面生长因子的接受、形态梯度的形成和轴突引导是必不可少的。HSPGs在许多不同的生物学环境中发挥作用，但对其活动的分子基础知之甚少。我们正在利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对不同配体蛋白的特异性功能是如何产生的。HS链具有明显的非均相结构，通过调节引入N-， 2-O-， 6-O-和3- o -硫酸盐基团。有证据表明，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hspg在发育中的新作用。我们之前发现HSPGs在发育过程中调控形态因子的梯度形成。我们现在提出了一个新的模型，即HSPGs也参与干细胞生态位的形成，干细胞生态位是细胞以严格控制的方式接收位置信号的另一个发育过程。我们的初步研究强烈表明，HSPGs在发育中的卵巢中通过不同的作用模式建立了生殖系干细胞（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）通路。迄今为止，在任何模型系统中从未证实HSPGs参与这一途径，尽管Unpaired是果蝇JAK/STAT途径的已知配体，是肝素结合蛋白。我们将以果蝇卵发生为模型，研究HSPGs在这一途径中的作用。我们提出的研究的具体目标是：目标1。探讨果蝇发育过程中HS修饰酶在信号传导中的分子功能。目标2。探讨热休克蛋白在果蝇种系干细胞生态位中的作用。目标3。确立hspg在JAK/STAT通路中的作用。公共卫生相关性：硫酸肝素蛋白聚糖（HSPGs）参与多种生物过程，如生长因子信号传导、形态梯度形成和轴突引导。正常HSPG生物合成的破坏导致许多人类遗传疾病以及癌症的形成。本研究的长期目标是利用遗传易学的模式生物——黑腹果蝇，了解HSPGs在发育过程中的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.