Mechanisms of invertebrate EGF receptor inhibition

描述（由申请人提供）：来自表皮生长因子受体（EGFR）家族的受体酪氨酸激酶在控制细胞过程（如增殖、运动和分化）中发挥关键作用。EGFR信号传导的空间和时间特征的精确调节在发育期间的组织图案化中也非常重要。EGFR家族成员的失调与许多人类癌症有关，并且该家族的两个成员（EGFR和ErbB 2/Her 2）是目前临床使用的治疗剂的靶标，包括赫赛汀、易瑞沙和爱必妥。 虽然在理解EGFR信号传导机制方面取得了很大进展，但关于它在细胞表面如何发挥作用的关键问题仍然没有答案。特别是，据报道在细胞表面观察到的预形成的EGFR二聚体（并且对信号传导很重要）尚未在体外描述。此外，ErbB 2的结构研究表明，它是组成型活性，但没有提供深入了解其在细胞表面的调节。在我们对无脊椎动物EGFR同源基因的研究中，我们发现C。elegans EGFR在体外形成预形成的二聚体，提供了一个独特的机会来详细研究这一关键状态。此外，D.黑腹鼠EGFR在结构上类似于人ErbB 2，但保留了直接受生长因子配体调节的能力。仔细研究这些无脊椎动物受体的生长因子激活模式有望填补我们对EGFR信号传导机制的理解中的关键空白。 我们还将阐明两种天然存在的EGFR信号传导抑制剂（Argos和Kekkon-1）的分子机制，这两种抑制剂在D.黑胃组织图案化。Argos是一种分泌性蛋白，可中和果蝇EGFR的活化配体。Kekkon-1是一种跨膜蛋白，似乎直接抑制EGFR。通过了解这些抑制剂的功能，我们希望获得设计新的癌症治疗药物，分别针对EGFR激活配体和EGFR的洞察力。 结合生物化学、生物物理学、晶体学和细胞信号传导方法，我们建议解决以下具体目标： 1.为了确定生长因子结合如何调节D. melanogaster和C. elegans EGF受体直系同源物，作为解决人类ErbB受体激活中未回答问题的模型。 2.分泌型抑制剂Argos和膜蛋白Kekkon-1对EGFR信号传导抑制的比较机制分析。

DESCRIPTION (provided by applicant): Receptor tyrosine kinases from the epidermal growth factor receptor (EGFR) family play critical roles in controlling cellular processes such as proliferation, motility and differentiation. Precise regulation of the spatial and temporal features of EGFR signaling is also very important in tissue patterning during development. Misregulation of EGFR family members is implicated in many human cancers, and two members of this family (EGFR and ErbB2/Her2) are targets of therapeutic agents in current clinical use, including Herceptin, Iressa, and Erbitux. Although much progress has been made in understanding EGFR signaling mechanisms, key questions remain unanswered about how it functions at the cell surface. In particular, pre-formed EGFR dimers, reportedly seen at the cell surface (and important for signaling), have not been described in vitro. Moreover, structural studies of ErbB2 indicate that it is constitutively active, but provide no insight into its regulation at the cell surface. In our studies of invertebrate EGFR orthologs, we have found that C. elegans EGFR forms pre-formed dimers in vitro, offering a unique opportunity to study this key state in detail. Moreover, the D. melanogaster EGFR structurally resembles human ErbB2, yet retains the ability to be regulated directly by growth factor ligands. Scrutinizing the mode of growth factor activation of these invertebrate receptors promises to fill critical gaps in our understanding of the mechanism of EGFR signaling in general. We will also elucidate the molecular mechanisms of two naturally-occurring inhibitors of EGFR signaling (Argos and Kekkon-1) that play critical roles in D. melanogaster tissue patterning. Argos is a secreted protein that neutralizes an activating ligand for Drosophila EGFR. Kekkon-1 is a transmembrane protein that appears to inhibit EGFR directly. By understanding how these inhibitors function, we hope to gain insight for designing novel cancer therapeutics that target EGFR-activating ligands and EGFR respectively. Combining biochemical, biophysical, crystallographic and cellular signaling approaches, we propose to address the following Specific Aims: 1. To determine how growth factor binding regulates the D. melanogaster and C. elegans EGF receptor orthologs, as models for addressing unanswered questions in human ErbB receptor activation. 2. A comparative mechanistic analysis of EGFR signaling inhibition by the secreted inhibitor Argos and the membrane protein Kekkon-1.