Zavortink Michael, Contreras Nelida, Addy Tracie, Bejsovec Amy, Saint Robert
ARC Special Research Centre for the Molecular Genetics of Development and Molecular Genetics and Evolution Group, Research School of Biological Sciences, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.
J Cell Sci. 2005 Nov 15;118(Pt 22):5381-92. doi: 10.1242/jcs.02652.
A central question in understanding cytokinesis is how the cleavage plane is positioned. Although the positioning signal is likely to be transmitted via the anaphase microtubule array to the cell cortex, exactly how the microtubule array determines the site of contractile ring formation remains unresolved. By analysing tum/RacGAP50C mutant Drosophila embryos we show that cells lacking Tum do not form furrows and fail to localise the key cytokinetic components Pebble (a RhoGEF), Aurora B kinase, Diaphanous, Pav-KLP and Anillin. The GAP activity of Tum is required for cytokinesis: in its absence cytokinesis fails early even though Tum is present on microtubules at the cell equator where the furrow should form. Disruption of the Pebble-interacting domain leaves Tum localised to the cell equator on cortically associated microtubules, again with no evidence of furrowing. These data support a model in which Tum/RacGAP, via its interaction with Pbl, provides a critical link between the anaphase microtubule spindle and cytokinetic furrow formation in Drosophila cells.
理解胞质分裂过程中的一个核心问题是分裂平面如何定位。尽管定位信号可能通过后期微管阵列传递到细胞皮层，但微管阵列究竟如何确定收缩环形成的位点仍未得到解决。通过分析tum/RacGAP50C突变型果蝇胚胎，我们发现缺乏Tum的细胞不会形成沟，并且无法定位关键的胞质分裂成分：Pebble（一种RhoGEF）、极光B激酶、Diaphanous、Pav-KLP和Anillin。Tum的GAP活性是胞质分裂所必需的：即使Tum存在于应该形成沟的细胞赤道处的微管上，但在其缺失时，胞质分裂仍会早期失败。Pebble相互作用结构域的破坏使Tum定位在皮层相关微管上的细胞赤道处，同样没有沟形成的迹象。这些数据支持了一个模型，即Tum/RacGAP通过与Pbl的相互作用，在果蝇细胞后期微管纺锤体和胞质分裂沟形成之间提供了关键联系。
