Kloc M, Etkin L D
Department of Molecular Genetics, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
Development. 1995 Feb;121(2):287-97. doi: 10.1242/dev.121.2.287.
We found that there are two major pathways by which RNAs are localized at the vegetal cortex during oogenesis of Xenopus laevis. One of these, through which Xlsirts, Xcat2 and Xwnt11 are localized, involves transport during stages 1 and 2 of oogenesis via a region of the mitochondrial cloud that we call the message transport organizer or METRO. This pathway involved three steps, transport of RNA from the GV to the mitochondrial cloud, sorting of the RNAs to specific regions of the METRO, and translocation to and anchoring at the vegetal cortex. These three RNAs exhibit a distinct pattern of spatial localization within the METRO when they approach the vegetal cortex. The other pathway is used by Vg1. We detected Vg1 throughout the oocyte cytoplasm during stages 1 and 2. During stage 3 it was translocated to the vegetal cortex and associated with the cortex overlapping the region at which the Xlsirt, Xcat2, and Xwnt11 RNAs are anchored. Our results also showed that anchoring of these RNAs was dependent in part on actin microfilaments, but was independent of microtubules. These results demonstrate a novel mechanism of translocation and RNA sorting used by RNAs several of which may be involved in the establishment of the embryonic body axis.
我们发现，在非洲爪蟾卵子发生过程中，RNA定位于植物性皮层有两条主要途径。其中一条途径涉及Xlsirts、Xcat2和Xwnt11的定位，在卵子发生的第1和第2阶段，通过线粒体云的一个区域进行运输，我们将该区域称为信息运输组织者或METRO。这条途径包括三个步骤，RNA从生发泡运输到线粒体云，RNA在METRO的特定区域进行分选，然后转运并锚定在植物性皮层。当这三种RNA接近植物性皮层时，它们在METRO内呈现出独特的空间定位模式。另一条途径由Vg1使用。在第1和第2阶段，我们在整个卵母细胞胞质中检测到Vg1。在第3阶段，它被转运到植物性皮层，并与皮层相关联，该皮层与Xlsirt、Xcat2和Xwnt11 RNA锚定的区域重叠。我们的结果还表明，这些RNA的锚定部分依赖于肌动蛋白微丝，但不依赖于微管。这些结果证明了RNA使用的一种新的转运和RNA分选机制，其中几种RNA可能参与胚胎体轴的建立。
