EGF RECEPTOR SYNTHESIS: STRUCTURE & ROLE IN LIVER GROWTH

表皮生长因子受体广泛分布于上皮细胞和上皮细胞。 表皮组织。在EGF的刺激下，受体转导a 强烈的有丝分裂信号。因此，EGF-EGF R组织，如皮肤，结肠， 呼吸道上皮和肝脏。表皮生长因子的生理学研究 由于几个新的发现，信令系统变得复杂起来 可能通过与EGF R结合而发挥作用的EGF样蛋白 研究了静止、生长状态下表皮生长因子受体的结构和合成 和转化的肝细胞。我们注意到EGF R的实质性变化 在这些不同的状态下合成，并发现了一种截断形式的 肝脏中的EGF-R。以下三个目标源于我们之前的 工作。了解EGF-R合成的调控。EGF增加 静止期肝上皮细胞的EGF受体合成 矛盾的是，循环的肝细胞减少了它们的EGF-R合成。 上皮癌是人类大多数的恶性肿瘤，可以表现为 异常过表达或完全取消EGF-R 综合。目的1详细研究大鼠表皮生长因子受体的转录调控 在一系列实验模型中进行合成，显示出阳性或 负向监管。二、了解银行的监管和职能 截短形式的表皮生长因子R。我们已经从2.7kB的片段中分离到了一个基因片段。 大鼠肝脏中EGF受体mRNA的表达。该基因编码一种EGF R胞外蛋白 被截断的域，因此它是保密的，但在 结构与正常的EGF受体保持结合能力 125I-EGF。Aim 2将测试该蛋白是否调节EGF受体 通过结合EGF样多肽或通过与全长相互作用来传递信号 感受器。这些研究将使用表达载体、纯化的蛋白和 转基因小鼠来阐明这种蛋白质的功能。三、确定 EGF-R是否参与肝脏再生。EGF刺激血管内皮细胞 肝细胞和其他肝细胞的生长。携带转化生长因子α的转基因 小鼠的肝脏极度增生。AIM 3将在现场使用 用杂交法研究EGF R和EGF样蛋白的定位表达 多肽和与特定细胞类型相关的表达或定位 DNA合成的模式。在目标4中，我们将制作抗大鼠EGF R 单克隆化并选择可阻断EGF和TGFα与EGF结合的MoAbs R.抗体随后将被测试其封闭配体的能力- 在体外和体内指导EGF-R信号和有丝分裂生成。MoAbs 符合这些标准的人将有助于理解 EGF-R参与肝脏再生等生理生长过程。

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.