Kluba Malgorzata, Engelborghs Yves, Hofkens Johan, Mizuno Hideaki
Laboratory of Biomolecular Network Dynamics, Biochemistry, Molecular and Structural Biology Section, Department of Chemistry, KU Leuven, Celestijnenlaan 200G box 2403, 3001, Heverlee, Belgium.
Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Heverlee, Belgium.
PLoS One. 2015 Oct 14;10(10):e0139971. doi: 10.1371/journal.pone.0139971. eCollection 2015.
Dimerization of the epidermal growth factor receptor (EGFR) is crucial for initiating signal transduction. We employed raster image correlation spectroscopy to continuously monitor the EGFR monomer-dimer equilibrium in living cells. EGFR dimer formation upon addition of EGF showed oscillatory behavior with a periodicity of about 2.5 min, suggesting the presence of a negative feedback loop to monomerize the receptor. We demonstrated that monomerization of EGFR relies on phospholipase Cγ, protein kinase C, and protein kinase D (PKD), while being independent of Ca2+ signaling and endocytosis. Phosphorylation of the juxtamembrane threonine residues of EGFR (T654/T669) by PKD was identified as the factor that shifts the monomer-dimer equilibrium of ligand bound EGFR towards the monomeric state. The dimerization state of the receptor correlated with the activity of an extracellular signal-regulated kinase, downstream of the EGFR. Based on these observations, we propose a novel, negative feedback mechanism that regulates EGFR signaling via receptor monomerization.
表皮生长因子受体（EGFR）的二聚化对于启动信号转导至关重要。我们采用光栅图像相关光谱法持续监测活细胞中EGFR单体 - 二聚体的平衡。添加表皮生长因子（EGF）后EGFR二聚体的形成呈现出约2.5分钟周期的振荡行为，这表明存在一个使受体单体化的负反馈环。我们证明，EGFR的单体化依赖于磷脂酶Cγ、蛋白激酶C和蛋白激酶D（PKD），而与Ca2+信号传导和内吞作用无关。PKD对EGFR近膜区苏氨酸残基（T654/T669）的磷酸化被确定为使配体结合的EGFR单体 - 二聚体平衡向单体状态转变的因素。受体的二聚化状态与EGFR下游的细胞外信号调节激酶的活性相关。基于这些观察结果，我们提出了一种通过受体单体化调节EGFR信号传导的新型负反馈机制。
