Urazbaev Arshat, Serikbaeva Anara, Tvorogova Anna, Dusenbayev Azamat, Kauanova Sholpan, Vorobjev Ivan
National Laboratory Astana, Nazarbayev University, Nur-Sultan, Kazakhstan.
Laboratory of Biophotonics and Imaging, National Laboratory Astana, Nazarbayev University, Nur-Sultan, Kazakhstan.
Front Mol Biosci. 2021 Nov 8;8:745089. doi: 10.3389/fmolb.2021.745089. eCollection 2021.
Microtubules are dynamic structures undergoing rapid growth and shrinkage in living cells and . The growth of microtubules was analyzed with subpixel precision (Maurer et al., Current Biology, 2014, 24 (4), 372-384); however, to what extent these results could be applied for microtubules growing remains largely unknown. Particularly, the question is whether microtubule growth velocity in cells could be sufficiently approximated by a Gaussian distribution or its variability requires a more sophisticated description? Addressing this question, we used time-lapse microscopy and mathematical modeling, and we analyzed EB-3 comets forming on microtubules of cultured cells with subpixel precision. Parameters of comets (shape, form, and velocity) were used as topological characteristics of 3D voxel objects. Using regression analysis, we determined the real positions of the microtubule tips in time-lapse sequences. By exponential decay fitting of the restored comet intensity profile, we found that EB-3 rapidly exchanges on growing microtubule ends with a decoration time ∼ 2 s. We next developed the model showing that the best correlation between comet length and microtubule end growth velocity is at time intervals close to the decoration time. In the cells, EB comet length positively correlates with microtubule growth velocity in preceding time intervals, while demonstrating no correlation in subsequent time intervals. Correlation between comet length and instantaneous growth velocity of microtubules remains under nocodazole treatment when mean values of both parameters decrease. Our data show that the growth of microtubules in living cells is well-approximated by a constant velocity with large stochastic fluctuations.
微管是活细胞中经历快速生长和收缩的动态结构。微管的生长已通过亚像素精度进行了分析（Maurer等人，《当代生物学》，2014年，24(4)，372 - 384）；然而，这些结果在多大程度上可应用于正在生长的微管仍 largely unknown。特别是，问题在于细胞中的微管生长速度是否能通过高斯分布充分近似，或者其变异性是否需要更复杂的描述？为了解决这个问题，我们使用了延时显微镜和数学建模，并以亚像素精度分析了在培养细胞的微管上形成的EB - 3彗星。彗星的参数（形状、形态和速度）被用作三维体素对象的拓扑特征。通过回归分析，我们在延时序列中确定了微管尖端的真实位置。通过对恢复的彗星强度轮廓进行指数衰减拟合，我们发现EB - 3在生长的微管末端快速交换，装饰时间约为2秒。接下来我们开发了一个模型，表明彗星长度与微管末端生长速度之间的最佳相关性出现在接近装饰时间的时间间隔。在细胞中，EB彗星长度在前一时间间隔与微管生长速度呈正相关，而在随后的时间间隔则无相关性。当两个参数的平均值都降低时，在诺考达唑处理下彗星长度与微管瞬时生长速度之间的相关性仍然存在。我们的数据表明，活细胞中微管的生长可以通过具有大随机波动的恒定速度很好地近似。
