Structural Studies of Growth Factor Receptor Function

描述（由申请人提供）：受体酪氨酸激酶（RTKs）在许多动物组织中介导细胞生长和分化。在人类中发现了20种不同类型的rtk，包括胰岛素、表皮生长因子（EGF）和血管内皮生长因子（VEGF）的受体。RTKs由细胞外配体结合区、单一跨膜区和细胞质酪氨酸激酶组成。配体与细胞外区域的结合触发激酶活性的激活，从而导致下游靶标的磷酸化和信号级联的启动。RTKs的不适当激活可导致细胞生长失控，58个人类RTKs中有28个的改变与某种形式的癌症有关。例如，EGF受体同源物ErbB2/HER2在20-25%的人类乳腺癌中被发现过表达，并且与更具侵袭性的肿瘤和较差的预后相关。抑制RTKs已被证明是一种有效的抗癌策略，针对EGF受体（Erbitux）和ErbB2/HER2 （Herceptin）的单克隆抗体已分别被批准用于治疗结直肠癌和乳腺癌。我的实验室最近开发了简化富半胱氨酸糖蛋白表达的方法，其中包括大多数RTK细胞外区域，用于x射线结构研究。这些方法使我们能够确定人类EGF受体（EGFR）家族的所有四个成员以及ErbB2/HER2与Herceptin和另一种治疗性抗体Omnitarg的fab复合物的细胞外区域的晶体结构。结合其他实验室的结果，这些结构导致了EGFR家族的新信号模型，并为靶向该家族的抗癌药物的机制提供了新的见解。我们的第一个目标是扩展这些研究，并确定具有结合配体的特定EGFR家族成员对的细胞外区域的晶体结构，以更好地了解该家族内信号传导的性质和特异性。我们的第二个目标是对EGFR家族成员信号传导的两个下游效应物进行生化和结构研究，以更好地了解EGFR产生的信号是如何在细胞内传递和调节的。我们的第三个目标是启动两类相关rtk的结构研究，包括巨噬细胞集落刺激因子（MCSF）、干细胞因子（SCF）、Flt3配体和VEGF受体，以更好地了解它们在正常和疾病状态下的功能。

DESCRIPTION (provided by applicant): Receptor tyrosine kinases (RTKs) mediate cell growth and differentiation in many animal tissues. Twenty different classes of RTKs are found in humans and include receptors for insulin, epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF). RTKs consist of an extracellular ligand-binding region, a single membrane-spanning region, and a cytoplasmic tyrosine kinase. Ligand binding to the extracellular region triggers activation of the kinase activity, which leads to phosphorylation of downstream targets and initiation of a signaling cascade. Inappropriate activation of RTKs can lead to uncontrolled cell growth, and alterations in 28 of the 58 human RTKs have been associated with some form of cancer. For example, overexpression of the EGF receptor homologue ErbB2/HER2 is found in 20-25% of human breast cancers and is associated with more aggressive tumors and a poorer prognosis. Inhibiting RTKs has proven an effective anticancer strategy, and monoclonal antibodies against the EGF receptor (Erbitux) and ErbB2/HER2 (Herceptin) have been approved for the treatment of colorectal and breast cancer, respectively. My laboratory has recently developed methods that simplify expression of cysteine-rich glycoproteins, which includes most RTK extracellular regions, for X-ray structural studies. These methods have enabled us to determine crystal structures of the extracellular regions of all four members of the human EGF receptor (EGFR) family as well as ErbB2/HER2 complexed with the Fabs of Herceptin and another therapeutic antibody, Omnitarg. Combined with results from other labs, these structures have led to new models of signaling for the EGFR family and provided insight into the mechanism of anticancer agents targeting this family. Our first aim is to extend these studies and determine crystal structures of the extracellular regions of specific pairs of EGFR family members with bound ligand to better understand the nature of signaling and specificity within this family. Our second aim is to perform biochemical and structural studies of two downstream effectors of signaling by EGFR family members to better understand how EGFR generated signals are transmitted and regulated within the cell. Our third aim is to initiate structural studies of two related classes of RTKs, which include the receptors for macrophage colony-stimulating factor (MCSF), stem cell factor (SCF), Flt3 Ligand, and VEGF, to better understand their function in normal and disease states.