FGF-1 SECRETION PATHWAY

肝素结合蛋白，成纤维细胞生长因子-1，是一种 一个相关基因大家族的原型成员，它缺乏 通过内质引导其分泌的结构特征 网状高尔基复合体。因为成纤维细胞生长因子-1是一种强有力的血管生成因子 被认为是血管病理生理学的中介， 成纤维细胞生长因子-1的分泌机制可能是一个重要的调节因素 控制这种蛋白质的生物活性的功能。因此，长的 本申请的术语目标是定义负责 分泌成纤维细胞生长因子-1。我们之前已经证明，温度会导致 分泌成纤维细胞生长因子-1作为一种生物上没有活性的蛋白质 与高亲和力的肝素结合。然而，(NH4)2S04和更多 最近的还原剂能够激活肝素结合和 潜伏期成纤维细胞生长因子-1的生物学活性。事实上，最近的诱变研究 用成纤维细胞生长因子-1证实后一种观察结果，因为不含半胱氨酸的成纤维细胞生长因子-1 突变体不会对温度做出反应而分泌。此外，我们还有 鉴定成纤维细胞生长因子-1为磷脂酰丝氨酸(Pls)结合蛋白 涉及pls结合蛋白突触素(Stg)的功能 参与胞吐的交通，作为一个潜在的候选人调解 分泌成纤维细胞生长因子-1。最后，我们已经获得了初步证据， 氧化型低密度脂蛋白和低氧均可诱导 释放成纤维细胞生长因子-1作为肝素结合生长因子。这些数据支持 我们的近期目标包括：(一)界定 成纤维细胞生长因子-1半胱氨酸残基及stg在成纤维细胞生长因子-1中的潜在作用 分泌途径，(Ii)鉴定和鉴定 参与成纤维细胞生长因子-1分泌途径的细胞内因子 (三)确定低氧等替代生物应激是否 和深度缺氧能够利用这一非常规途径 分泌成纤维细胞生长因子-1。预计这些结果最终将在 不仅有助于我们理解成纤维细胞生长因子-1是如何调控 体内血管生成，但对成纤维细胞生长因子-1分泌途径的定义可能 也为了解成纤维细胞生长因子-1的分泌机制提供了新的见解 途径可能被抑制。事实上，最近已经有可能联合 用新的电泳法从培养液中定位成纤维细胞生长因子-1和STG 热休克和NIH3T3对成纤维细胞生长因子-1基因表达的影响 共转染成纤维细胞生长因子-1和反义STG的细胞不能释放成纤维细胞生长因子-1 对温度应激的反应。

The heparin-binding protein, fibroblast growth factor (FGF)- 1, is a prototype member of a large family of related genes and it lacks the structural feature to direct its secretion through the endoplasmic reticulum-Golgi complex. Because FGF-1 is a potent angiogenesis factor and has been implicated as a mediator of vascular pathophysiology, the mechanism by which FGF-1 is secreted may be an important regulatory feature to control the biological activity of this protein. Thus the long term goal of this application is to define the mechanism responsible for FGF-1 secretion. We have previously shown that temperature results in the secretion of FGF-1 as a protein which is biologically inactive and fails to associate with heparin with high affinity. However, (NH4)2S04 and more recently reducing agents are able to activate the heparin-binding and biological activity of latent FGF-1. Indeed, recent mutagenesis studies with FGF-1 confirm the latter observation since a cysteine-free FGF-1 mutant is not secreted in response to temperature . In addition, we have characterized FGF-1 as a phosphatydylserine (pLS)binding protein and have implicated the function of synaptotagnin (stg), a pLS-binding protein involved in exocytotic traffic, as a potential candidate for mediating the secretion of FGF-1. Lastly, we have obtained preliminary evidence that oxidized low density lipoprotein and hypoxia are able to induce the release of FGF-1 as a heparin-binding growth factor. These data support our immediate goals and these include (i) the definition of the role of FGF-1 cysteine residues and the potential function of stg in the FGF-1 secretion pathway, (ii) the identification and characterization of intracellular factors that participate in the FGF-1 secretion pathway and (iii) determine whether alternative biological stresses such as hypoxia and profound hypoxia are able to utilize this non-conventional pathway for FGF-1 secretion. It is anticipated that these results will in ultimately contribute not only to our understanding of how FGF-1 is able to regulate angiogenesis in vivo but definition of the FGF-1 secretion pathway may also yield new insight into mechanisms by which the FGF-1 secretion pathway may be inhibited. Indeed, it has recently been possible to co- localize FGF-1 and stg using novel electrophoretic methods from the medium of FGF-1-transfected NIH 3T3 cells conditioned by heat shock and NIH 3T3 cells co-transfected with FGF-1 and antisense stg fail to release FGF-1 in response to temperature stress.