Powers J, Bossinger O, Rose D, Strome S, Saxton W
Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
Curr Biol. 1998 Oct 8;8(20):1133-6. doi: 10.1016/s0960-9822(98)70470-1.
Dividing cells need to coordinate the separation of chromosomes with the formation of a cleavage plane. There is evidence that microtubule bundles in the interzone region of the anaphase spindle somehow control both the location and the assembly of the cleavage furrow [1-3]. A microtubule motor that concentrates in the interzone, MKLP1, has previously been implicated in the assembly of both the metaphase spindle and the cleavage furrow [4-6]. To gain insight into mechanisms that might underlie interdependence of the spindle and the cleavage furrow, we used RNA-mediated interference (RNAi) to study the effects of eliminating MKLP1 from Caenorhabditis elegans embryos. Surprisingly, in MKLP1(RNAi) embryos, spindle formation appears normal until late anaphase. Microtubule bundles form in the spindle interzone and the cleavage furrow assembles; anaphase and cleavage furrow ingression initially appear normal. The interzone bundles do not gather into a stable midbody, however, and furrow contraction always fails before complete closure. This sequence of relatively normal mitosis and a late failure of cytokinesis continues for many cell cycles. These and additional results suggest that the interzone microtubule bundles need MKLP1 to encourage the advance and stable closure of the cleavage furrow.
正在分裂的细胞需要协调染色体的分离与分裂平面的形成。有证据表明，后期纺锤体中间区的微管束以某种方式控制着分裂沟的位置和组装[1-3]。一种集中在中间区的微管马达蛋白MKLP1，此前已被证明与中期纺锤体和分裂沟的组装有关[4-6]。为了深入了解纺锤体和分裂沟相互依赖的潜在机制，我们使用RNA介导的干扰（RNAi）来研究从秀丽隐杆线虫胚胎中去除MKLP1的影响。令人惊讶的是，在MKLP1（RNAi）胚胎中，纺锤体形成在后期晚期之前看起来是正常的。微管束在纺锤体中间区形成，分裂沟组装；后期和分裂沟的内陷最初看起来是正常的。然而，中间区的微管束不会聚集形成稳定的中间体，并且在完全闭合之前，沟的收缩总是失败。这种相对正常的有丝分裂序列和后期胞质分裂失败会持续多个细胞周期。这些以及其他结果表明，中间区微管束需要MKLP1来促进分裂沟的推进和稳定闭合。
