Promoting Receptor Protein Tyrosine Phosphatase Activity by Targeting Transmembrane Domain Interactions

项目摘要 受体蛋白酪氨酸磷酸酶（RPTPs）在发育、健康、 和疾病进展。尽管RPTPs在信号转导中的重要性很明显，但我们对它的了解很少。 结构与功能之间的关系是其活性调节的基础。据报道， 然而，RPTP同源二聚化以拮抗其催化活性提供了潜在的机会， 发展策略，以促进RPTP活性对他们的致癌受体酪氨酸激酶（RTK）底物。 我们最近发现，使用PTPRJ/EGFR作为模型RPTP/RTK对， (also称为DEP 1）由跨膜结构域相互作用调节，和（ii）破坏这些 相互作用可以拮抗PTPRJ同源二聚化，减少底物EGFR磷酸化， 拮抗EGFR驱动的细胞表型。 在这里，我们建议沿着沿着三个主题相互关联的这些新的见解， 非重叠，具体的目标，与最终目标：（1）证明RPTP TM域的相互作用， 在调节它们的活性和底物进入方面是必不可少的，以及（2）开发新的治疗方法 以促进RPTP对致癌RTK底物的活性。 在我们的第一个目标中，我们将确定调节PTPRJ异源二聚化的分子决定簇， EGFR对这些研究将通过扩展它们来补充，以了解PTPRJ TM结构域突变体 影响受体运输和最终的细胞结果。第二个目标是设计和筛选多肽 能够结合PTPRJTM结构域，并测试它们破坏PTPRJ同源二聚化、促进PTPRJ PTPRJ对EGFR和其他底物RTK的活性，并选择性靶向人肿瘤异种移植物， 小鼠在第三个目标中，我们将确定其他候选RTK底物，其通过PTPRJ的调节依赖于 在TM结构域介导的异源二聚化，并确定如何不同的细胞环境预测细胞 通过TM结构域干扰PTPRJ二聚化的信号传导和表型结果。为此，我们 将实施基于数据驱动的表型计算建模的系统生物学方法， 蛋白质磷酸化和表达的测量和整体质谱测量， 一组细胞系。这一目标的动机是理解所有RPTP都有多种底物， 细胞间这些底物表达的变化可能导致不同的结果， 二聚化被破坏。 最终，这里提出的研究将促进我们对RPTP的基本生物学理解， 生物学，这是迫切需要的，并导致新的方法来靶向信号通过致癌RTKs， 可能对RTK抑制剂获得性抗性的常见机制不太敏感。

PROJECT SUMMARY Receptor protein tyrosine phosphatases (RPTPs) play critical signaling regulatory roles in development, health, and disease progression. Despite the clear importance of RPTPs in signal transduction, very little is known about the structure-function relationships that underpin the regulation of their activity. The reported ability of RPTP homodimerization to antagonize their catalytic activity, however, presents potential opportunities to develop strategies to promote RPTP activity against their oncogenic receptor tyrosine kinase (RTK) substrates. We recently showed, using PTPRJ/EGFR as a model RPTP/RTK pair, that: (i) homodimerization of PTPRJ (also known as DEP1) is regulated by transmembrane domain interactions, and (ii) disrupting these interactions can antagonize PTPRJ homodimerization, reduce substrate EGFR phosphorylation, and antagonize EGFR-driven cell phenotypes. Here, we propose to build upon these new insights along three thematically interconnected, but non-overlapping, specific aims, with the ultimate goals of: (1) demonstrating that RPTP TM domain interactions are essential in regulating their activity and substrate access, and (2) developing a new therapeutic approach to promote RPTP activity against their oncogenic RTK substrates. In our first aim, we will determine the molecular determinants regulating the heterodimerization of PTPRJ with EGFR. These studies will be complemented by extending them to understand how PTPRJ TM domain mutants affect receptor trafficking and ultimate cell outcomes. In the second aim, we will design and select peptides capable of binding to PTPRJ TM domains and test their ability to disrupt PTPRJ homodimerization, promote PTPRJ activity against EGFR and other substrate RTKs, and selectively target human tumor xenografts in mice. In the third aim, we will identify other candidate RTK substrates whose regulation by PTPRJ depends upon TM domain-mediated heterodimerization, and determine how different cellular contexts predict the cell signaling and phenotype outcome of interfering with PTPRJ dimerization through TM domains. To do so, we will implement a systems biology approach based on data-driven computational modeling of phenotypic measurements and global mass spectrometry measurements of protein phosphorylation and expression in a panel of cell lines. This aim is motivated by an understanding that all RPTPs have multiple substrates and that variations in expression of those substrates among cells may lead to different outcomes when PTPRJ dimerization is disrupted. Ultimately, the studies proposed here stand to advance both our basic biological understanding of RPTP biology, which is critically needed, and to lead to new methods to target signaling through oncogenic RTKs that may be less susceptible to common mechanisms of acquired resistance to RTK inhibitors.