Intercellular propagation of extracellular signal-regulated kinase activation revealed by in vivo imaging of mouse skin.
Intercellular propagation of extracellular signal-regulated kinase activation revealed by in vivo imaging of mouse skin.
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DOI：
10.7554/elife.05178
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发表时间：
2015-02-10
期刊：
影响因子：
7.7
通讯作者：
Matsuda M
中科院分区：
文献类型：
--
作者：
Hiratsuka T;Fujita Y;Naoki H;Aoki K;Kamioka Y;Matsuda M
细胞外信号调节激酶 (ERK) 是许多生长信号通路的关键效应器。在这项研究中，我们使用 ERK FRET 生物传感器可视化活体小鼠的表皮 ERK 活性。在稳态条件下，表皮偶尔会显示出 ERK 激活模式的爆发，其中 ERK 活性在细胞之间呈放射状传播。径向 ERK 活性分布 (SPREAD) 的空间传播频率与表皮细胞分裂速率相关。 12-O-十四烷酰佛波醇 13-乙酸酯 (TPA) 以依赖于 EGF 受体及其同源配体的方式刺激传播和增殖。在受伤的皮肤处，ERK 激活作为触发波平行于伤口边缘传播，表明 ERK 激活传播可以叠加。此外，通过可视化细胞周期，我们发现 SPREAD 与 G2/M 细胞周期进展相关。我们的结果为细胞增殖和瞬时 ERK 活性如何在活组织中同步提供了新的见解。 DOI：http://dx.doi.org/10.7554/eLife.05178.001 我们的皮肤是我们最大的器官；它提供了一个屏障，保护下面的组织和内部器官免受外部环境的影响，并作为我们抵御感染的第一道防线之一。这两种作用都会使皮肤受到磨损，因此必须不断产生新的皮肤细胞来替代丢失或受损的皮肤细胞。然而，如果这个更新过程出现问题，可能会导致细胞过度生长或皮肤癌。为了避免这种情况，细胞严格调节刺激皮肤更新的途径。皮肤更新涉及生长信号激活一种称为 ERK 的酶。 ERK 酶激活的时间和地点通常受到严格控制，许多种癌症都与 ERK 在错误的时间或错误的地点激活有关。尽管 ERK 在皮肤细胞中很重要，但许多技术挑战使得研究这些信号如何在细胞之间传递变得困难。平冢等人。现在，我们对基因改造的小鼠进行了检查，这些小鼠产生荧光传感器分子，从而可以观察活皮肤细胞中的 ERK 活性。在显微镜下观察麻醉小鼠的皮肤，延时视频显示偶尔会出现“烟花般”的 ERK 活性爆发。起初，ERK 酶在一小群皮肤细胞中活跃，然后在周围细胞中观察到 ERK 活性，在几分钟内似乎向外扩散，然后活动停止。平冢等人。将这种活动模式命名为“径向 ERK 活动分布的空间传播”，简称为 SPREAD。通过研究这些小鼠耳朵和背部皮肤中的传播，Hiratsuka 等人。了解到这些 ERK 活性的爆发与皮肤细胞的生长同时发生；爆发更频繁地发生在皮肤细胞分裂的区域。在小鼠皮肤上涂抹一种刺激细胞分裂的化学物质会引发更多的 ERK 活性爆发；而如果 Hiratsuka 等人观察到的爆发较少。使用其他化学物质来阻断一些在 ERK 上游起作用的信号蛋白的活性。进一步的实验表明，SPREADs 鼓励细胞在导致细胞分裂的事件周期中前进；阻止这些爆发会导致细胞在正常分裂之前的阶段暂停。平冢等人。还观察到类似的 ERK 活性模式从皮肤伤口边缘像波浪一样向外移动。使用类似方法的进一步研究将揭示生长信号如何在健康和患病组织中触发和传播，不仅在皮肤中，而且在肝脏、肠道和肌肉等其他器官中。 DOI：http://dx.doi.org/10.7554/eLife.05178.002
Extracellular signal-regulated kinase (ERK) is a key effector of many growth signalling pathways. In this study, we visualise epidermal ERK activity in living mice using an ERK FRET biosensor. Under steady-state conditions, the epidermis occasionally revealed bursts of ERK activation patterns where ERK activity radially propagated from cell to cell. The frequency of this spatial propagation of radial ERK activity distribution (SPREAD) correlated with the rate of epidermal cell division. SPREADs and proliferation were stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) in a manner dependent on EGF receptors and their cognate ligands. At the wounded skin, ERK activation propagated as trigger wave in parallel to the wound edge, suggesting that ERK activation propagation can be superimposed. Furthermore, by visualising the cell cycle, we found that SPREADs were associated with G2/M cell cycle progression. Our results provide new insights into how cell proliferation and transient ERK activity are synchronised in a living tissue. DOI: http://dx.doi.org/10.7554/eLife.05178.001 Our skin is our largest organ; it provides a barrier that protects the underlying tissues and internal organs from the external environment and acts as one of our first lines of defense against infection. Both of these roles subject the skin to wear and tear and so it must constantly create new skin cells to replace those lost or damaged. However, if this renewal process goes awry it can lead to excessive cell growth or skin cancer. To avoid this, cells tightly regulate the pathways that stimulate skin renewal. Skin renewal involves growth signals activating an enzyme called ERK. When and where the ERK enzyme is activated is normally tightly regulated, and many kinds of cancer have been linked to ERK becoming active at the wrong time or in the wrong place. Despite the importance of ERK in skin cells, a number of technical challenges have made it difficult to study how these signals are passed from cell to cell. Hiratsuka et al. have now examined genetically altered mice that produce a fluorescent sensor molecule that makes it possible to see ERK activity in living skin cells. The skin of anesthetized mice was observed under a microscope, and time-lapse videos revealed occasional ‘firework-like’ bursts of ERK activity. At first the ERK enzyme was active in a small cluster of skin cells, then ERK activity was seen in the surrounding cells—appearing to spread outwards over the course of several minutes—before the activity stopped. Hiratsuka et al. named this pattern of activity a ‘Spatial Propagation of Radial ERK Activity Distribution’, or SPREAD for short. By studying SPREADs in the skin on the ears and the back of these mice, Hiratsuka et al. learned that these bursts of ERK activity coincided with skin cell growth; the bursts happened more frequently in the areas where the skin cells were dividing. Applying a chemical that stimulates cell division to the skin of the mice triggered more bursts of ERK activity; whereas fewer bursts were observed if Hiratsuka et al. used other chemicals to block the activity of some of the signaling proteins that work upstream of ERK. Further experiments suggested that SPREADs encourage cells to progress through the cycle of events that leads a cell to divide; blocking these bursts caused the cell to pause at the stage just before it would normally divide. Hiratsuka et al. also observed similar patterns of ERK activity moving out like waves from the edges of skin wounds. Further research using similar methods will reveal how growth signals are triggered and propagated in healthy and diseased tissues, not only in the skin but also other organs such as the liver, intestine, and muscles. DOI: http://dx.doi.org/10.7554/eLife.05178.002