FUNCTIONAL ANALYSIS OF A PDGF-INDUCIBLE CYTOKINE

生长因子对靶细胞发挥作用，部分是通过诱导 特定基因的表达。例如，在3 T3细胞中， 血小板衍生生长因子（PDGF）诱导表达 增殖相关的原癌基因以及另外50-100个 基因，其中大多数没有已知的功能。的长期目标 这个建议是为了了解更多关于生长因子介导的有丝分裂 通过了解一些结构和功能的过程， 后一组PDGF诱导基因，特别是JE基因，第一组PDGF诱导基因， PDGF诱导基因已被分离。 在初步研究中，JE基因已被证明编码低水平的 分子量分泌的糖蛋白，与最近发现的 纯化的单核细胞趋化因子。该因子还激活单核细胞， 增强其参与抗体非依赖性肿瘤细胞裂解的能力。 因此，本申请中的研究也将与抗肿瘤相关。 疗法有三个假设，这一建议的具体目标将 试验人员： 首先，因为JE蛋白在纳摩尔浓度下发挥作用， 在高浓度下，它可能通过高亲和力受体起作用。的 第一个具体目标是鉴定、克隆和测试这些 受体。这些实验将提供深入了解的机制， 单核细胞趋化性和激活，以及提供工具， 检查其他细胞类型是否存在JE受体。 第二，因为JE蛋白的序列与那些 与其他具有不同活性的细胞因子相比， 单核细胞特异性作用通过特异性氨基酸介导。的 第二个具体目标是对JE进行结构/功能分析 通过定点诱变获得蛋白质。这项研究的结果可能 为开发特异性激动剂或拮抗剂提供信息 的行动。 最后，因为有细胞类型能够表达乙脑， 在炎症反应中没有作用，很可能JE可能有 除了单核细胞趋化性之外的功能。第三个具体目标是 构建以去调节方式表达JE的转基因小鼠。在 除了揭示乙脑新活动的潜力外， 也将提供在体内确认乙脑的影响， physiology.

Growth factors exert their effects on target cells, in part, by inducing the expression of specific genes. For example, in 3T3 cells, platelet-derived growth factor (PDGF) induces the expression of proliferation-related proto-oncogenes as well as an additional 50-100 genes, the majority of which have no known function. The long-term goal of this proposal is to learn more about growth factor-mediated mitogenic processes by understanding the structure and function of some of the the latter group of PDGF-inducible genes, in particular the JE gene, the first PDGF-indudble gene to have been isolated. In preliminary studies, the JE gene has been shown to encode a low molecular weight secreted glycoprotein that is identical to a recently purified monocyte chemotactic factor. This factor also activates monocytes, enhancing their ability to engage in antibodyindependent tumor cell lysis. Thus the studies in this application will also have relevance to anti-tumor therapy. There are three hypotheses the specific aims of this proposal will test: First, because the JE protein exerts its effects at nanomolar concentrations, it is likely to act through a high affinity receptor. The first specific aim is to identify, clone, and test the activity of these receptors. These experiments will provide insight into the mechanisms of monocyte chemotaxis and activation, as well as providing tools for the examination of other cell types for the presence of the JE receptor. Second, because the sequence of the JE protein is highly similar to those of other cytokines with different activities, it is likely that its monocyte-specific effects are mediated through specific amino acids. The second specific aim is to perform a structure/function analysis of the JE protein by site-directed mutagenesis. The results of such a study could provide information for the development of specific agonists or antagonists of JE action. Finally, because there are cell types capable of expressing JE that play no role in the inflammatory response, it is likely that JE may have functions other than monocute chemotaxis. The third specific aim is the construction of transgenic mice expressing JE in a deregulated fashion. In addition to the potential for revealing new activities for JE, this model will also provide in vivo confirmation of JE's effects on monocute physiology.