Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA.
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA.
Nat Commun. 2024 Nov 1;15(1):9434. doi: 10.1038/s41467-024-53656-w.
Microtubules are dynamic filaments that assemble spindles for eukaryotic cell division. As the concentration profiles of soluble tubulin and regulatory proteins are non-uniform during spindle assembly, we asked if diffusiophoresis - motion of particles under solute gradients - can act as a motorless transport mechanism for microtubules. We identify the migration of stable microtubules along cytoplasmic and higher concentration gradients of soluble tubulin, MgCl, Mg-ATP, Mg-GTP, and RanGTP at speeds O(100) nm/s, validating the diffusiophoresis hypothesis. Using two buffers (BRB80 and CSF-XB), microtubule behavior under MgCl gradients is compared with negatively charged particles and analyzed with a multi-ion diffusiophoresis and diffusioosmosis model. Microtubule diffusiophoresis under gradients of tubulin and RanGTP is also compared with the charged particles and analyzed with a non-electrolyte diffusiophoresis model. Further, we find that tubulin and RanGTP display concentration dependent cross-diffusion that influences microtubule diffusiophoresis. Finally, using Xenopus laevis egg extract, we show that diffusiophoretic transport occurs in an active cytoplasmic environment.
微管是动态的细丝，组装纺锤体用于真核细胞分裂。由于在纺锤体组装过程中可溶性微管蛋白和调节蛋白的浓度分布不均匀，我们想知道扩散泳——在溶质梯度下颗粒的运动——是否可以作为微管的无动力运输机制。我们发现稳定的微管沿着细胞质和可溶性微管蛋白、MgCl、Mg-ATP、Mg-GTP 和 RanGTP 的较高浓度梯度以 O(100)nm/s 的速度迁移，验证了扩散泳假说。使用两种缓冲液（BRB80 和 CSF-XB），比较了 MgCl 梯度下微管的行为与带负电荷的颗粒，并使用多离子扩散泳和扩散渗透模型进行了分析。还比较了微管在微管蛋白和 RanGTP 梯度下的扩散泳与带电颗粒的行为，并使用非电解质扩散泳模型进行了分析。此外，我们发现微管蛋白和 RanGTP 显示出浓度依赖性的交叉扩散，这影响了微管的扩散泳。最后，使用非洲爪蟾卵提取物，我们证明了扩散泳运输发生在活性细胞质环境中。
