EGF RECEPTOR SYNTHESIS: STRUCTURE & ROLE IN LIVER GROWTH

EGF受体广泛分布于上皮细胞和 表皮组织 在EGF的刺激下，受体转导一种 有丝分裂信号 因此，EGF-EGF R组织如皮肤，结肠， 呼吸道上皮和肝脏。 EGF的生理功能研究 由于发现了几个新的信号系统， EGF样蛋白可能通过结合EGF R发挥作用。 我们有 研究了EGF R的结构和合成， 转化的肝细胞 EGF R的变化 在这些不同的状态下进行合成，并发现了一种截短形式的 EGF R肝 以下三个目标源于我们先前的 工作 I. 了解EGF R合成的调控。 EGF增加 静止期肝上皮细胞EGF受体的合成 特别地，循环肝细胞减少其EGF R合成。 上皮癌，大多数人类恶性肿瘤，可以表现出 EGF R mRNA异常过度表达或EGF R完全消失 合成. 目的1详细研究大鼠EGF R的转录调控 在一系列实验模型中进行合成， 负调节 二. 为了了解一个 EGF R的合成 我们从一个2.7 kB的cDNA中分离出一个 EGF受体mRNA在大鼠肝脏中的表达 该cDNA编码EGF R细胞外 结构域被截短，使其分泌，但在 表皮生长因子受体（EGF receptor），它保留了结合的能力。 125I-EGF。 目的2将测试这种蛋白质是否调节EGF受体 通过结合EGF样肽或通过与全长 受体。 这些研究将使用表达载体、纯化的蛋白质和 转基因小鼠来阐明这种蛋白质的功能。 三. 以确定 EGF R是否参与肝再生 EGF的功效 肝细胞和其他肝细胞的生长。 转TGF α基因 老鼠的肝脏极度增生。 Aim 3将在现场使用 杂交研究EGF R和EGF样蛋白的定位表达 肽，并将表达与特定的细胞类型或局部 DNA合成的模式 在目标4中，我们将使抗大鼠EGF R 单克隆抗体和选择阻断EGF和TGF α与EGF结合的MoAb R. 然后将测试抗体阻断配体的能力- 在体外和体内定向EGF R信号传导和有丝分裂。 MoAbs 符合这些标准的信息将有助于理解 EGF R在肝再生等生理生长过程中的作用

The EGF receptor is broadly distributed on cells of epithelial and epidermal tissues. Upon stimulation by EGF, the receptor transduces a potent mitogenic signal. Thus, the EGF-EGF R tissues such as skin, colon, respiratory epithelia and liver. Studies of the physiology of the EGF signalling system have been complicated due to the discovery of several new EGF-like proteins which may act by binding to the EGF R. We have investigated the structure and synthesis of the EGF R in quiescent, growing and transformed liver cells. We have noted substantial changes in EGF R synthesis in these various states and have uncovered a truncated form of the EGF R from liver. The following three objectives stem from our prior work. I. To understand the regulation of EGF R synthesis. EGF increases EGF receptor synthesis in quiescent hepatic epithelial cells. Paradoxically, cycling hepatic cells decrease their EGF R synthesis. Epithelial cancers, the majority of human malignancies, can exhibit either extraordinary overexpression of EGF R mRNA or total abolition of EGF R synthesis. Aim 1 details studies of transcriptional control of rat EGF R synthesis in a series of experimental models that exhibit positive or negative regulation. II. To understand the regulation and function of a truncated form of the EGF R. We have isolated a cDNA derived from a 2.7 kB EGF receptor mRNA in rat liver. This cDNA encodes an EGF R extracellular domain that is truncated so that it is secreted, yet is similar enough in structure to the normal EGF receptor that it retains the ability to bind 125I-EGF. Aim 2 will test whether this protein modulates EGF receptor signalling by binding EGF-like peptides or by interacting with full length receptors. These studies will use expression vectors, purified protein and transgenic mice to elucidate this protein's function. III. To determine whether the EGF R is involved in liver regeneration. EGF stimulates the growth of hepatocyte and other liver cells. TGFalpha-bearing transgenic mice have extremely hyperplastic livers. Aim 3 will use in situ hybridization to study the localized expression of EGF R and EGF-like peptides and to correlate expression with specific cell types or localized patterns of DNA synthesis. In Aim 4, we will make anti-rat EGF R monoclonals and select MoAbs that block EGF and TGFalpha binding to the EGF R. Antibodies will then be tested for their ability to block ligand- directed EGF R signalling and mitogenesis in vitro and then in vivo. MoAbs that meet these criteria will be useful in understanding the role of the EGF R in physiologic growth processes such as liver regeneration.