Quantitative imaging of single live cells reveals spatiotemporal dynamics of multistep signaling events of chemoattractant gradient sensing in Dictyostelium.
Quantitative imaging of single live cells reveals spatiotemporal dynamics of multistep signaling events of chemoattractant gradient sensing in Dictyostelium.
复制标题
单个活细胞的定量成像揭示了盘基网柄菌趋化剂梯度传感的多步信号传导事件的时空动态。
DOI：
10.1091/mbc.e04-07-0544
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发表时间：
2005
影响因子：
3.3
通讯作者：
Jin,Tian
中科院分区：
文献类型：
--
作者：
Xu,Xuehua;Meier-Schellersheim,Martin;Jiao,Xuanmao;Nelson,LaurenE;Jin,Tian
Activation of G-protein-coupled chemoattractant receptors triggers dissociation of Gα and Gβγ subunits. These subunits induce intracellular responses that can be highly polarized when a cell experiences a gradient of chemoattractant. Exactly how a cell achieves this amplified signal polarization is still not well understood. Here, we quantitatively measure temporal and spatial changes of receptor occupancy, G-protein activation by FRET imaging, and PIP3levels by monitoring the dynamics of PHCrac-GFP translocation in single living cells in response to different chemoattractant fields. Our results provided the first direct evidence that G-proteins are activated to different extents on the cell surface in response to asymmetrical stimulations. A stronger, uniformly applied stimulation triggers not only a stronger G-protein activation but also a faster adaptation of downstream responses. When naïve cells (which have not experienced chemoattractant) were abruptly exposed to stable cAMP gradients, G-proteins were persistently activated throughout the entire cell surface, whereas the response of PHCrac-GFP translocation surprisingly consisted of two phases, an initial transient and asymmetrical translocation around the cell membrane, followed by a second phase producing a highly polarized distribution of PHCrac-GFP. We propose a revised model of gradient sensing, suggesting an important role for locally controlled components that inhibit PI3Kinase activity.
