Genetic Study of Heparan Sulfate Function in Development

描述（由申请人提供）：硫酸乙酰肝素蛋白聚糖（HSPGs）参与多种生物过程，如生长因子信号传导。许多人类疾病已被发现与HSPG生物合成缺陷有关。硫酸肝素（HS）链具有明显的非均相结构，主要由N-、2-O-、6-O-和3- o -硫酸盐基团的调控引入产生。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，这种控制的分子基础在很大程度上是未知的。我们的目标是了解特定HS精细结构在形态发生中的作用，使用遗传易学的模式生物，果蝇。我们最近发现果蝇HS6 - o -硫代转移酶（dHS6ST）在气管系统发育过程中是FGF信号的积极调节因子。这与最近的生化数据一致，这些数据表明6- o -硫酸化是脊椎动物系统中FGF信号激活的原因。然而，生长因子信号是通过这种特定的硫酸化控制的分子机制仍有待阐明。我们还研究了HS 3- o位的硫酸化，已知这对哺乳动物的血液凝固和病毒感染至关重要。然而，人们对3- o -硫酸化在发育中的作用知之甚少。在我们的初步研究中，果蝇HS3 - o -硫转移酶b （dHS3ST-b）参与Notch信号传导和许多组织的组装，暗示3- o -硫酸化在发育过程中。

DESCRIPTION (provided by applicant): Heparan sulfate proteoglycans (HSPGs) are involved in a variety of biological processes such as growth factor signaling. Many human diseases have been found to be associated with defects in the HSPG biosynthesis. The heparan sulfate (HS) chains have markedly heterogeneous structures that are mainly 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 basis for this control, however, is largely unknown. Our goal is to understand the roles of specific HS fine structures in morphogenesis using a genetically tractable model organism, Drosophila melanogaster. We recently identified Drosophila HS 6-O-sutfotransferase (dHS6ST) as a positive regulator of FGF signaling during tracheal system development. This is consistent with recent biochemical data, which suggested that 6-O-sulfation is responsible for the activation of FGF signaling in vertebrate systems. However, the molecular mechanism by which growth factor signaling is controlled by this specific sulfation of HS remains to be elucidated. We have also investigated sulfation at the 3-O-position of HS, which is known to be critical for blood coagulation and viral infection in mammals. However, the role of 3-O-sulfation in development is poorly understood. In our preliminary studies, Drosophila HS 3-O-sulfotransferase-b (dHS3ST-b) is involved in Notch signaling and the assembly of many tissues, implicating 3-O-sulfation in development. In the proposed research, we will study the in vivo functions of three genes for Drosophila HSSTs, dHS6ST, dHS3ST-a, and -b, during development. Specific aims are: Aim 1. Explore the molecular functions of dHS6ST in growth factor signaling during Drosophila development. Aim 2. Determine the molecular functions of the dHS3ST-b gene in the Notch signaling pathway. Aim 3. Localize the ligand-specific HS in Drosophila tissues. Two recently developed techniques, transgenic RNA interference (Aim 2) and an in situ ligand binding assay (Aim 3), will be used in this study.