Regulation of EGFR-mediated cell signaling and EGFR endocytosis during mitosis and other phases of cell cycle

表皮生长因子受体（EGFR）与其他受体酪氨酸激酶（rtk）一样，调节细胞生长、分化、存活和迁移的关键事件。来自EGFR的异常信号与许多疾病有关。EGFR激活刺激调节多种细胞功能的各种信号通路。EGF与EGFR的结合也刺激了EGFR的快速内化。EGFR内吞作用和EGFR介导的细胞信号是相互调节的。EGF通过驱动细胞周期刺激细胞增殖，细胞周期由四个阶段组成：G1， S， G2和m ******尽管我们对EGFR信号传导和运输的理解取得了重大进展，但仍然缺乏一些关键的知识。迄今为止，受体信号传导和内吞作用的研究主要是在假设细胞同质性的情况下进行的。受体信号和内吞作用的异质性很少被研究。在我们之前的研究中，我们研究了EGFR信号在不同亚细胞位置沿其内吞运输途径的异质性。在本提案中，我们试图探索EGFR信号在细胞周期不同阶段的异质性。******我们目前对EGFR信号传导和EGFR内吞作用的了解主要来自细胞周期G1期的细胞研究。关于egfr介导的信号和S期、G2期和M期的内吞作用，我们所知甚少。*最近，我们研究了有丝分裂过程中egf诱导的EGFR信号传导和内吞作用，并获得了一些有趣的结果。与教条相反，我们已经证明，在有丝分裂中，EGF确实激活EGFR并选择性地激活一些下游信号蛋白（如Akt2， Cbl和PLC-γ1），同时避免其他信号蛋白（如Akt1和ERK）。此外，我们发现在有丝分裂中，egf诱导的EGFR内吞作用并不停止，而是受到与间期不同的调节。我们的初步数据还表明，EGFR信号可能在细胞周期的S期和G2期受到不同的调节。因此，我们提出EGFR内吞作用和EGFR介导的细胞信号在细胞周期的每个阶段受到不同的调节，以提供细胞异质性，并特异性地服务于细胞在每个细胞周期阶段的特殊需求。我们计划用以下目标来检验我们的假设：*******目标1。研究EGFR信号在有丝分裂中的调控作用****目的2。研究EGFR内吞作用及其对有丝分裂中EGFR介导的细胞信号传导的影响****目的3。绘制EGFR介导的细胞信号在S、G2和有丝分裂亚期的调控*******我们研究计划的长期目标是使用EGFR作为模型系统来探索RTK信号的细胞异质性调控及其细胞异质性的生物学意义。我们关于EGFR的研究结果可能适用于不同细胞类型的其他rtk，这将显著推进我们关于细胞调控的基础知识。******

The epidermal growth factor receptor (EGFR), like other receptor tyrosine kinases (RTKs), regulates key events in cell growth, differentiation, survival and migration. Aberrant signaling from EGFR has been implicated in many diseases. EGFR activation stimulates various signaling pathways that regulate multiple cell functions. The binding of EGF to EGFR also stimulates the rapid internalization of EGFR. EGFR endocytosis and EGFR-mediated cell signaling are mutually regulated. EGF stimulates cell proliferation by driving the cell cycle, which is comprised of four phases: G1, S, G2 and M. ******In spite of significant advances in our understanding of EGFR signaling and trafficking, some critical knowledge is still lacking. To date, the study of receptor signaling and endocytosis has largely been done assuming cellular homogeneity. The heterogeneity of receptor signaling and endocytosis has been rarely explored. In our previous research, we studied the heterogeneity of EGFR signaling from different subcellular locations along its endocytic trafficking pathway. In this proposal, we seek to explore the heterogeneity of EGFR signaling among various phases of cell cycle. ******Our current knowledge of EGFR signaling and EGFR endocytosis comes mostly from the studies of cells in G1 phase of the cell cycle. Very little is known regarding EGFR-mediated signaling and endocytosis in S, G2 and M phases.*Recently, we have studied EGF-induced EGFR signaling and endocytosis during mitosis and have obtained some interesting results. Contrary to dogma, we have shown that in mitosis, EGF does activate EGFR and selectively activates some downstream signaling proteins (such as Akt2, Cbl and PLC-γ1), while avoiding others (such as Akt1 and ERK). In addition, we have found that in mitosis, EGF-induced EGFR endocytosis does not cease, but is regulated differently from interphase. Our preliminary data also suggest that EGFR signaling may be regulated differently during S and G2 phases of the cell cycle. Therefore, we propose that EGFR endocytosis and EGFR-mediated cell signaling are regulated differently in each phase of cell cycle to provide cellular heterogeneity and specifically serve the special needs of the cell in each cell cycle phase. We plan to test our hypothesis with the following aims:*******Aim 1. To study the regulation of EGFR signaling in mitosis****Aim 2. To study EGFR endocytosis and its effect on EGFR-mediated cell signaling in mitosis****Aim 3. Map the regulation of EGFR-mediated cell signaling in S, G2 and mitotic subphases*******The long-term goal of our research program is to use EGFR as a model system to explore the regulation of cellular heterogeneity of RTK signaling and the biological significance of this cellular heterogeneity. Our findings with EGFR may well apply to other RTKs in diverse cell types, which will significantly advance our fundamental knowledge regarding cell regulation.******