School of Biochemistry, Faculty of Health and Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, BS8 1TD, Bristol, UK.
School of Physiology, Pharmacology and Neuroscience, Faculty of Health and Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, BS8 1TD, Bristol, UK.
Nat Commun. 2024 Jul 16;15(1):5967. doi: 10.1038/s41467-024-50424-8.
Crosstalk between the actin and microtubule cytoskeletons is important for many cellular processes. Recent studies have shown that microtubules and F-actin can assemble to form a composite structure where F-actin occupies the microtubule lumen. Whether these cytoskeletal hybrids exist in physiological settings and how they are formed is unclear. Here, we show that the short-crossover Class I actin filament previously identified inside microtubules in human HAP1 cells is cofilin-bound F-actin. Lumenal F-actin can be reconstituted in vitro, but cofilin is not essential. Moreover, actin filaments with both cofilin-bound and canonical morphologies reside within human platelet microtubules under physiological conditions. We propose that stress placed upon the microtubule network during motor-driven microtubule looping and sliding may facilitate the incorporation of actin into microtubules.
细胞骨架之间的串扰对于许多细胞过程都很重要。最近的研究表明，微管和 F-肌动蛋白可以组装形成一种复合结构，其中 F-肌动蛋白占据微管腔。这些细胞骨架杂种是否存在于生理环境中以及它们是如何形成的尚不清楚。在这里，我们表明，先前在人类 HAP1 细胞中的微管内鉴定出的短交叉 Class I 肌动蛋白丝是与 cofilin 结合的 F-肌动蛋白。腔室内的 F-肌动蛋白可以在体外重新构成，但 cofilin 不是必需的。此外，在生理条件下，具有 cofilin 结合和经典形态的肌动蛋白丝存在于人血小板微管内。我们提出，在马达驱动的微管环和滑动过程中，微管网络所承受的压力可能有助于肌动蛋白掺入微管。
