Anterior-Posterior Axis Specification in Drosophila Oocytes: Identification of Novel bicoid and oskar mRNA Localization Factors
Anterior-Posterior Axis Specification in Drosophila Oocytes: Identification of Novel bicoid and oskar mRNA Localization Factors
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DOI：
10.1534/genetics.111.129312
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发表时间：
2011-08-01
期刊：
影响因子：
3.3
通讯作者：
Johnston, Daniel St
中科院分区：
文献类型：
--
作者：
Chang, Chin-Wen;Nashchekin, Dmitry;Johnston, Daniel St
黑腹果蝇的前后轴是在卵子发生过程中通过bicoid和oskar mRNA定位于卵母细胞的前极和后极而建立的。虽然遗传筛选已经确定了这些转录本的定位所需的一些反式作用因子，但其他因子可能被遗漏，因为它们也在卵子发生的其他阶段起作用。为了避免这个问题，我们进行了一个屏幕上的回复突变体和显性抑制剂的二尾表型所造成的表达Miranda-GFP的女性生殖系。米兰达通过将oskar mRNA/Staufen复合物与bicoid定位途径偶联，将其错误定位于卵母细胞前部，导致形成前腹部而不是头部。在一类回复突变体中，米兰达仍然结合Staufen/oskar mRNA复合物，但不定位于前部，在米兰达的N末端鉴定了前部靶向结构域。这与脊椎动物RHAMM的N末端具有几乎相同的序列，RHAMM也是一种大卷曲螺旋蛋白，这表明它可能是一种不同的米兰达直系同源物。此外，我们恢复了30个显性抑制因子，包括多个等位基因的spectroplakin，短停止，一个致命的互补组，防止奥斯卡mRNA锚定，和雌性不育互补组，破坏了前定位的bicoid mRNA在卵子发生后期。其中一个等位基因抑制因子被证明是肌动蛋白成核因子Cappuccino的突变，揭示了Cappuccino在极浆锚定和长奥斯卡蛋白诱导肌动蛋白丝中的先前未被认识的功能。
The Drosophila melanogaster anterior-posterior axis is established during oogenesis by the localization of bicoid and oskar mRNAs to the anterior and posterior poles of the oocyte. Although genetic screens have identified some trans-acting factors required for the localization of these transcripts, other factors may have been missed because they also function at other stages of oogenesis. To circumvent this problem, we performed a screen for revertants and dominant suppressors of the bicaudal phenotype caused by expressing Miranda-GFP in the female germline. Miranda mislocalizes oskar mRNA/Staufen complexes to the oocyte anterior by coupling them to the bicoid localization pathway, resulting in the formation of an anterior abdomen in place of the head. In one class of revertants, Miranda still binds Staufen/oskar mRNA complexes, but does not localize to the anterior, identifying an anterior targeting domain at the N terminus of Miranda. This has an almost identical sequence to the N terminus of vertebrate RHAMM, which is also a large coiled-coil protein, suggesting that it may be a divergent Miranda ortholog. In addition, we recovered 30 dominant suppressors, including multiple alleles of the spectroplakin, short stop, a lethal complementation group that prevents oskar mRNA anchoring, and a female sterile complementation group that disrupts the anterior localization of bicoid mRNA in late oogenesis. One of the single allele suppressors proved to be a mutation in the actin nucleator, Cappuccino, revealing a previously unrecognized function of Cappuccino in pole plasm anchoring and the induction of actin filaments by Long Oskar protein.