Microtubule aging probed by microfluidics-assisted tubulin washout.
Microtubule aging probed by microfluidics-assisted tubulin washout.
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微流体辅助小管蛋白清洗探测的微管老化。
DOI：
10.1091/mbc.e16-07-0548
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发表时间：
2016-11-07
影响因子：
3.3
通讯作者：
Surrey T
中科院分区：
文献类型：
--
作者：
Duellberg C;Cade NI;Surrey T
微管老化——稳定性随年龄的增长而下降——是一个有趣的但在机制上尚未被理解的微管特性。它限制了突变诱导的可能机制，并被认为对长度调节至关重要。新的体外实验和模型拟合提供了洞察微管老化的起源。微管在生长和收缩阶段之间随机切换。导致生长阶段结束的分子机制，即所谓的“灾难”事件，至今仍不为人所知。突变发生的概率随着微管年龄的增加而增加，这就限制了突变诱导的可能分子机制。在这里，我们使用微流体辅助的微管蛋白快速冲洗实验，在生长开始后的不同时间以可控的方式诱导微管解聚。我们发现，老化也可以在这个实验中观察到，提供了有价值的新约束，对突变诱导的理论模型可以进行测试。我们发现，这些数据可以用一个简单的动力学阈值模型来定量地解释，该模型假设微管末端的保护帽随着年龄的增长而扩大，这是逐渐变细的端结构的结果；这导致了帽密度和稳定性的降低。这一分析表明，保护帽的形态变化对微管稳定性的年龄依赖性有直观的影响。
Microtubule aging—the decrease of stability with age—is an interesting but mechanistically not understood property of microtubules. It constrains possible mechanisms of catastrophe induction and is believed to be crucial for length regulation. New in vitro experiments and model fits provide insight into the origin of microtubule aging. Microtubules switch stochastically between phases of growth and shrinkage. The molecular mechanism responsible for the end of a growth phase, an event called catastrophe, is still not understood. The probability for a catastrophe to occur increases with microtubule age, putting constraints on the possible molecular mechanism of catastrophe induction. Here we used microfluidics-assisted fast tubulin washout experiments to induce microtubule depolymerization in a controlled manner at different times after the start of growth. We found that aging can also be observed in this assay, providing valuable new constraints against which theoretical models of catastrophe induction can be tested. We found that the data can be quantitatively well explained by a simple kinetic threshold model that assumes an age-dependent broadening of the protective cap at the microtubule end as a result of an evolving tapered end structure; this leads to a decrease of the cap density and its stability. This analysis suggests an intuitive picture of the role of morphological changes of the protective cap for the age dependence of microtubule stability.