Yasuda Tsuyoshi, Takaine Masak, Numata Osamu, Nakano Kentaro
Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.
Genes Cells. 2016 Jun;21(6):594-607. doi: 10.1111/gtc.12368. Epub 2016 Apr 5.
In the fission yeast Schizosaccharomyces pombe (Sp), Mid1/Dmf1 plays an important role in positioning the division site by inducing formation of the contractile ring (CR). Mid1, emanating from the nucleus located in the cell center, forms a dozen of nodes in the middle cell cortex ahead of mitosis, and actin filaments and myosin II accumulated at each node interact and assemble the CR in metaphase. Curiously, in another fission yeast S. japonicus (Sj), CR formation begins after nuclear segregation in late anaphase. Here, we investigated the role of S. japonicus Mid1 during mitosis to compare the molecular mechanisms that determine the cell division site in Schizosaccharomyces. Similar to Sp Mid1, Sj Mid1 often accumulated in the nucleus of interphase cells. Moreover, Sj Mid1 localized to cortical dots with myosin II in the future division site and formed a medial ring in mitotic cells. However, S. japonicus cells without Mid1 function still carried out symmetrical binary division. Therefore, the Mid1 dependency for positional control of the cell division site is possibly different between the two species. Meanwhile, we found that Sj Mid1 enhanced CR formation, in a manner possibly similar to that by Sp Mid1.
在裂殖酵母粟酒裂殖酵母（Sp）中，Mid1/Dmf1通过诱导收缩环（CR）的形成在确定分裂位点方面发挥重要作用。Mid1从位于细胞中心的细胞核发出，在有丝分裂前在细胞中部皮层形成十几个节点，每个节点处积累的肌动蛋白丝和肌球蛋白II相互作用并在中期组装CR。奇怪的是，在另一种裂殖酵母日本裂殖酵母（Sj）中，CR的形成在后期核分离后开始。在这里，我们研究了日本裂殖酵母Mid1在有丝分裂过程中的作用，以比较裂殖酵母中决定细胞分裂位点的分子机制。与Sp Mid1类似，Sj Mid1经常在间期细胞的细胞核中积累。此外，Sj Mid1与肌球蛋白II一起定位于未来分裂位点的皮层点，并在有丝分裂细胞中形成中间环。然而，没有Mid1功能的日本裂殖酵母细胞仍然进行对称的二分分裂。因此，这两个物种在细胞分裂位点位置控制对Mid1的依赖性可能不同。同时，我们发现Sj Mid1以可能类似于Sp Mid1的方式增强了CR的形成。
