Hsieh Ming-yu, Yang Shujie, Raymond-Stinz Mary Ann, Edwards Jeremy S, Wilson Bridget S
Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.
BMC Syst Biol. 2010 May 6;4:57. doi: 10.1186/1752-0509-4-57.
A stochastic simulator was implemented to study EGFR signal initiation in 3D with single molecule detail. The model considers previously unexplored contributions to receptor-adaptor coupling, such as receptor clustering and diffusive properties of both receptors and binding partners. The agent-based and rule-based approach permits consideration of combinatorial complexity, a problem associated with multiple phosphorylation sites and the potential for simultaneous binding of adaptors.
The model was used to simulate recruitment of four different signaling molecules (Grb2, PLCgamma1, Stat5, Shc) to the phosphorylated EGFR tail, with rules based on coarse-grained prediction of spatial constraints. Parameters were derived in part from quantitative immunoblotting, immunoprecipitation and electron microscopy data. Results demonstrate that receptor clustering increases the efficiency of individual adaptor retainment on activated EGFR, an effect that is overridden if crowding is imposed by receptor overexpression. Simultaneous docking of multiple proteins is highly dependent on receptor-adaptor stability and independent of clustering.
Overall, we propose that receptor density, reaction kinetics and membrane spatial organization all contribute to signaling efficiency and influence the carcinogenesis process.
实施了一个随机模拟器，以单分子细节研究三维空间中的表皮生长因子受体（EGFR）信号启动。该模型考虑了之前未探索的对受体-衔接蛋白偶联的贡献，例如受体聚集以及受体和结合伴侣的扩散特性。基于主体和基于规则的方法允许考虑组合复杂性，这是一个与多个磷酸化位点以及衔接蛋白同时结合的可能性相关的问题。
该模型用于模拟四种不同信号分子（Grb2、磷脂酶Cγ1、信号转导和转录激活因子5、生长因子结合蛋白2）向磷酸化的EGFR尾部的募集，其规则基于对空间限制的粗粒度预测。参数部分源自定量免疫印迹、免疫沉淀和电子显微镜数据。结果表明，受体聚集提高了单个衔接蛋白在活化的EGFR上保留的效率，但如果受体过表达导致拥挤，这种效应就会被抵消。多种蛋白质的同时对接高度依赖于受体-衔接蛋白的稳定性，且与聚集无关。
总体而言，我们认为受体密度、反应动力学和膜空间组织均对信号传导效率有贡献，并影响致癌过程。
