Ramirez Ivan, Gholkar Ankur A, Velasquez Erick F, Guo Xiao, Tofig Bobby, Damoiseaux Robert, Torres Jorge Z
Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA.
California NanoSystems Institute, Los Angeles, California, USA.
Cytoskeleton (Hoboken). 2021 Feb;78(2):23-35. doi: 10.1002/cm.21654. Epub 2021 Mar 8.
Myosins are ATP-dependent actin-based molecular motors critical for diverse cellular processes like intracellular trafficking, cell motility, and cell invasion. During cell division, myosin MYO10 is important for proper mitotic spindle assembly, the anchoring of the spindle to the cortex, and positioning of the spindle to the cell mid-plane. However, myosins are regulated by myosin regulatory light chains (RLCs), and whether RLCs are important for cell division has remained unexplored. Here, we have determined that the previously uncharacterized myosin RLC Myl5 associates with the mitotic spindle and is required for cell division. We show that Myl5 localizes to the leading edge and filopodia during interphase and to mitotic spindle poles and spindle microtubules during early mitosis. Importantly, depletion of Myl5 led to defects in mitotic spindle assembly, chromosome congression, and chromosome segregation and to a slower transition through mitosis. Furthermore, Myl5 bound to MYO10 in vitro and co-localized with MYO10 at the spindle poles. These results suggest that Myl5 is important for cell division and that it may be performing its function through MYO10.
肌球蛋白是依赖ATP的基于肌动蛋白的分子马达，对多种细胞过程至关重要，如细胞内运输、细胞运动和细胞侵袭。在细胞分裂过程中，肌球蛋白MYO10对有丝分裂纺锤体的正确组装、纺锤体与皮质的锚定以及纺锤体在细胞中平面的定位很重要。然而，肌球蛋白受肌球蛋白调节轻链（RLCs）调控，而RLCs对细胞分裂是否重要仍未得到探索。在此，我们确定了先前未被表征的肌球蛋白RLC Myl5与有丝分裂纺锤体相关，并且是细胞分裂所必需的。我们发现，Myl5在间期定位于前缘和丝状伪足，在有丝分裂早期定位于有丝分裂纺锤体极和纺锤体微管。重要的是，Myl5的缺失导致有丝分裂纺锤体组装、染色体汇聚和染色体分离缺陷，并导致有丝分裂过程中的过渡变慢。此外，Myl5在体外与MYO10结合，并在纺锤体极与MYO10共定位。这些结果表明，Myl5对细胞分裂很重要，并且它可能通过MYO10发挥其功能。
