Huynh J R, Shulman J M, Benton R, St Johnston D
The Wellcome/CRC Institute, University of Cambridge, Tennis Court Rd, Cambridge CB2 1QR, UK.
Development. 2001 Apr;128(7):1201-9. doi: 10.1242/dev.128.7.1201.
The PAR-1 kinase is required for the posterior localisation of the germline determinants in C. elegans and Drosophila, and localises to the posterior of the zygote and the oocyte in each case. We show that Drosophila PAR-1 is also required much earlier in oogenesis for the selection of one cell in a germline cyst to become the oocyte. Although the initial steps in oocyte determination are delayed, three markers for oocyte identity, the synaptonemal complex, the centrosomes and Orb protein, still become restricted to one cell in mutant clones. However, the centrosomes and Orb protein fail to translocate from the anterior to the posterior cortex of the presumptive oocyte in region 3 of the germarium, and the cell exits meiosis and becomes a nurse cell. Furthermore, markers for the minus ends of the microtubules also fail to move from the anterior to the posterior of the oocyte in mutant clones. Thus, PAR-1 is required for the maintenance of oocyte identity, and plays a role in microtubule-dependent localisation within the oocyte at two stages of oogenesis. Finally, we show that PAR-1 localises on the fusome, and provides a link between the asymmetry of the fusome and the selection of the oocyte.
PAR-1激酶对于秀丽隐杆线虫和果蝇中生殖系决定因子的后定位是必需的，并且在每种情况下都定位于合子和卵母细胞的后部。我们发现，果蝇PAR-1在卵子发生过程中更早阶段对于生殖系囊肿中一个细胞被选择成为卵母细胞也是必需的。尽管卵母细胞决定的初始步骤被延迟，但卵母细胞身份的三个标志物，即联会复合体、中心体和Orb蛋白，在突变克隆中仍然局限于一个细胞。然而，在卵巢管第3区推定卵母细胞中，中心体和Orb蛋白未能从前端转运到后端皮质，该细胞退出减数分裂并成为滋养细胞。此外，在突变克隆中，微管负端的标志物也未能从卵母细胞的前端移动到后端。因此，PAR-1对于维持卵母细胞身份是必需的，并且在卵子发生的两个阶段在卵母细胞内依赖微管的定位中发挥作用。最后，我们发现PAR-1定位于纺锤体上，并在纺锤体不对称性与卵母细胞选择之间建立了联系。
