Cheung H K, Serano T L, Cohen R S
Department of Biochemistry and Molecular Biophysics, Columbia University, College of Physicians and Surgeons, New York, NY 10032.
Development. 1992 Mar;114(3):653-61. doi: 10.1242/dev.114.3.653.
The specification of cell fates along the dorsoventral axis of the Drosophila embryo is dependent on the asymmetric distribution of proteins within the egg and within the egg's outer membranes. Such asymmetries arise during oogenesis and are dependent on multiple cell-cell interactions between the developing oocyte and its neighboring somatic follicle cells. The earliest known such interaction involves the generation of a signal in the oocyte and its reception in the follicle cells lying on the dorsal surface of the oocyte at approximately stage 10 of oogenesis. Several independent lines of investigation indicate that the fs(1)K10 (K10) gene negatively regulates the synthesis of the signal in the oocyte nucleus. Here we present data that indicate that the accumulation of K10 protein in the oocyte nucleus is a multistep process involving: (1) the synthesis of K10 RNA in nurse cells, (2) the rapid transport of K10 RNA from nurse cells into the oocyte, (3) the localization of K10 RNA to the anterior margin of the oocyte, and (4) K10 protein synthesis and localization. K10 RNA is transported into the oocyte continuously beginning at approximately stage 2. This indicates a high degree of selectivity in transport, since most RNAs synthesized in stage 2 and older nurse cells are stored there until stage 11, when nurse cells donate their entire cytoplasm to the oocyte. The sequences responsible for the early (pre-stage 11) and selective transport of K10 RNA into the oocyte map to the 3' transcribed non-translated region of the gene. None of the other identified genes involved in dorsoventral axis formation are required for K10 RNA transport.(ABSTRACT TRUNCATED AT 250 WORDS)
果蝇胚胎背腹轴上细胞命运的特化取决于卵子及其外膜内蛋白质的不对称分布。这种不对称性在卵子发生过程中出现，并依赖于发育中的卵母细胞与其相邻的体细胞滤泡细胞之间的多种细胞间相互作用。已知最早的这种相互作用涉及在卵母细胞中产生信号，并在卵子发生大约第10阶段时，由位于卵母细胞背表面的滤泡细胞接收该信号。几条独立的研究线索表明，fs(1)K10（K10）基因对卵母细胞核中信号的合成起负调控作用。在此，我们提供的数据表明，K10蛋白在卵母细胞核中的积累是一个多步骤过程，包括：（1）在滋养细胞中合成K10 RNA，（2）K10 RNA从滋养细胞快速转运到卵母细胞中，（3）K10 RNA定位于卵母细胞的前缘，以及（4）K10蛋白的合成和定位。K10 RNA大约从第2阶段开始持续转运到卵母细胞中。这表明转运具有高度的选择性，因为在第2阶段及更晚的滋养细胞中合成的大多数RNA会一直储存在那里，直到第11阶段，此时滋养细胞将其整个细胞质捐赠给卵母细胞。负责K10 RNA早期（第11阶段之前）和选择性转运到卵母细胞中的序列定位于该基因的3'转录非翻译区。背腹轴形成过程中涉及的其他已鉴定基因对K10 RNA转运均非必需。（摘要截短于250字）
