Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK.
Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
J Cell Sci. 2021 Mar 26;134(6):jcs253021. doi: 10.1242/jcs.253021.
Movement of the cell nucleus typically involves the cytoskeleton and either polymerization-based pushing forces or motor-based pulling forces. In the fission yeast , nuclear movement and positioning are thought to depend on microtubule polymerization-based pushing forces. Here, we describe a novel, microtubule-independent, form of nuclear movement in fission yeast. Microtubule-independent nuclear movement is directed towards growing cell tips, and it is strongest when the nucleus is close to a growing cell tip, and weakest when the nucleus is far from that tip. Microtubule-independent nuclear movement requires actin cables but does not depend on actin polymerization-based pushing or myosin V-based pulling forces. The vesicle-associated membrane protein (VAMP)-associated proteins (VAPs) Scs2 and Scs22, which are critical for endoplasmic reticulum-plasma membrane contact sites in fission yeast, are also required for microtubule-independent nuclear movement. We also find that in cells in which microtubule-based pushing forces are present, disruption of actin cables leads to increased fluctuations in interphase nuclear positioning and subsequent altered septation. Our results suggest two non-exclusive mechanisms for microtubule-independent nuclear movement, which may help illuminate aspects of nuclear positioning in other cells.
细胞核的运动通常涉及细胞骨架和基于聚合的推挤力或基于马达的拉力。在裂殖酵母中，核运动和定位被认为依赖于微管聚合的推挤力。在这里，我们描述了裂殖酵母中一种新的、微管非依赖的核运动形式。微管非依赖性核运动指向生长细胞的尖端，当细胞核靠近生长细胞的尖端时，这种运动最强，当细胞核远离该尖端时，这种运动最弱。微管非依赖性核运动需要肌动蛋白电缆，但不依赖于基于肌动蛋白聚合的推挤力或肌球蛋白 V 基的拉力。在裂殖酵母中，囊泡相关膜蛋白（VAMP）相关蛋白（VAPs）Scs2 和 Scs22 对于内质网-质膜接触位点至关重要，它们也对于微管非依赖性核运动是必需的。我们还发现，在存在基于微管的推挤力的细胞中，破坏肌动蛋白电缆会导致有丝分裂期核定位的波动增加，并随后导致隔室化的改变。我们的结果表明了两种非排他性的微管非依赖性核运动机制，这可能有助于阐明其他细胞中核定位的某些方面。
