Krapp Andrea, Collin Philippe, Cokoja Adisa, Dischinger Sandra, Cano Elena, Simanis Viesturs
Cell Cycle Control Laboratory, Swiss Institute for Experimental Cancer Research (ISREC), 1066 Epalinges, Switzerland.
J Cell Sci. 2006 Jul 15;119(Pt 14):2882-91. doi: 10.1242/jcs.03025. Epub 2006 Jun 20.
When nutrients are abundant, S. pombe cells grow as rods, dividing by fission after formation of a medially placed cell wall or division septum. Septum formation is triggered by a group of proteins, called the septation initiation network or SIN, that trigger contraction of the acto-myosin contractile ring at the end of mitosis. Ectopic activation of the SIN can uncouple septum formation from other cell-cycle events, whereas loss of SIN signalling gives rise to multinucleated cells due to the failure of cytokinesis. When starved, S. pombe cells of opposite mating types fuse to form a diploid zygote that undergoes meiosis and produces four spores. No septa or contractile rings are formed during meiosis. In this study, we have investigated the role of the SIN in meiosis. Our data show that, whereas the meiotic divisions appear normal, SIN mutants cannot form spores. Forespore membrane formation is initiated, but the nuclei are not encapsulated properly. The SIN proteins localise to the spindle pole body in meiosis. The protein kinases Sid1p and Cdc7p do not associate with the spindle pole body until meiosis II, when forespore membrane deposition begins. These data indicate a role for the SIN in regulating spore formation during meiosis.
当营养物质丰富时，粟酒裂殖酵母细胞呈杆状生长，在形成位于细胞中部的细胞壁或分裂隔膜后通过裂变进行分裂。隔膜的形成由一组称为隔膜起始网络（SIN）的蛋白质触发，这些蛋白质在有丝分裂末期触发肌动蛋白-肌球蛋白收缩环的收缩。SIN的异位激活可使隔膜形成与其他细胞周期事件解偶联，而SIN信号缺失则会由于胞质分裂失败而产生多核细胞。饥饿时，不同交配型的粟酒裂殖酵母细胞融合形成二倍体合子，合子进行减数分裂并产生四个孢子。减数分裂过程中不形成隔膜或收缩环。在本研究中，我们研究了SIN在减数分裂中的作用。我们的数据表明，虽然减数分裂过程看起来正常，但SIN突变体无法形成孢子。前孢子膜形成开始，但细胞核没有被正确包裹。SIN蛋白在减数分裂过程中定位于纺锤极体。蛋白激酶Sid1p和Cdc7p直到减数第二次分裂前孢子膜沉积开始时才与纺锤极体结合。这些数据表明SIN在减数分裂过程中调节孢子形成方面发挥作用。
