The function of a Drosophila glypican does not depend entirely on heparan sulfate modification
The function of a Drosophila glypican does not depend entirely on heparan sulfate modification
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DOI：
10.1016/j.ydbio.2006.09.011
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发表时间：
2006-12-15
影响因子：
2.7
通讯作者：
Selleck, Scott B.
中科院分区：
文献类型：
--
作者：
Kirkpatrick, Catherine A.;Knox, Sarah M.;Selleck, Scott B.
分裂异常延迟（Dally）是果蝇中两种糖基磷脂酰肌醇（GPI）连接的硫酸肝素蛋白聚糖之一。大量研究表明，它影响Decapentaplegic （Dpp）和无翼信号。一般认为Dally通过直接与这些生长因子相互作用来影响信号传导，主要是通过其硫酸肝素（HS）链。为了了解HS链和蛋白核心的功能贡献，我们(1)利用表面等离子体共振评估了纯化Dally的生长因子结合特性，(2)生成了一种未经HS修饰的Dally形式，并评估了其体内信号传导能力。纯化的Dally直接结合FGF2、FGF10和功能性Dpp同源物BMP4。与HS预孵育可消除FGF的结合，但BMP4的结合具有部分HS抗性，这表明Dally蛋白核心参与了结合。细胞结合和共免疫沉淀研究表明，非hs修饰的Dally保留了一些结合Dpp或BMP4的能力。hs缺陷Dally在体内的表达表明，它不像野生型Dally那样促进信号传导，但它可以挽救几种Dally突变表型。这些数据表明，Dally的所有体内活性并不需要硫酸肝素修饰，重要的功能能力存在于蛋白质核心。(c) 2006爱思唯尔公司版权所有。
Division abnormally delayed (Dally) is one of two glycosylphosphatidylinositol (GPI)-linked heparan sulfate proteoglycans in Drosophila. Numerous studies have shown that it influences Decapentaplegic (Dpp) and Wingless signaling. It has been generally assumed that Dally affects signaling by directly interacting with these growth factors, primarily through its heparan sulfate (HS) chains. To understand the functional contributions of HS chains and protein core we have (1) assessed the growth factor binding properties of purified Dally using surface plasmon resonance, (2) generated a form of Dally that is not HS modified and evaluated its signaling capacity in vivo. Purified Dally binds directly to FGF2, FGF10, and the functional Dpp homolog BMP4. FGF binding is abolished by preincubation with HS, but BMP4 association is partially HS-resistant, suggesting the Dally protein core contributes to binding. Cell binding and co-immunoprecipitation studies suggest that non-HS-modified Dally retains some ability to bind Dpp or BMP4. Expression of HS-deficient Dally in vivo showed it does not promote signaling as well as wild-type Dally, yet it can rescue several dally mutant phenotypes. These data reveal that heparan sulfate modification of Dally is not required for all in vivo activities and that significant functional capacity resides in the protein core. (c) 2006 Elsevier Inc. All rights reserved.