A small predicted stem-loop structure mediates oocyte localization of Drosophila K10 mRNA.
A small predicted stem-loop structure mediates oocyte localization of Drosophila K10 mRNA.
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发表时间：
1995-11
期刊：
影响因子：
4.6
通讯作者：
T. L. Serano;R. Cohen
中科院分区：
文献类型：
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作者：
T. L. Serano;R. Cohen
果蝇卵母细胞和未来胚胎背腹极性的建立依赖于 K10 mRNA 从护士细胞到卵母细胞的有效转运。为了研究 K10 mRNA 运输的顺式要求，我们使用转基因果蝇测定来分析一系列 K10 缺失变体的表达模式。此类研究鉴定了 K10 3' 非翻译区内的 44 个核苷酸序列，该序列对于 K10 mRNA 运输和随后定位到卵母细胞前皮质是必需的且足够的。对 44 个核苷酸转运/定位序列 (TLS) 的检查揭示了形成茎环二级结构的强大潜力。干扰 TLS 预测碱基配对的核苷酸取代会阻断 mRNA 运输和前部定位。相反，改变 TLS 碱基组成同时维持预测碱基配对的突变不会阻止 mRNA 转运或前定位。我们得出结论，K10 mRNA 转运和前部定位是由 44 个核苷酸的茎环结构介导的。在果蝇 orb mRNA 的 3' 非翻译区中发现了类似的推定茎环结构，表明相同的因子介导 K10 和 orb mRNA 的运输和前部定位。除了 orb 之外，K10 TLS 在任何其他定位的 mRNA 中都没有发现，这增加了其他 mRNA（例如 bicoid、oskar 和 gurken）的运输和定位是由一组新的顺式和反式作用因子介导的可能性。此外，我们发现 K10 TLS 超越了 oskar 顺式调节元件的活性，该元件介导 mRNA 向后极的后期运动。我们提出存在介导 mRNA 转运到卵母细胞的顺式调节元件家族，其中只有一些与介导后期运动的元件兼容。
The establishment of dorsoventral polarity in the Drosophila oocyte and future embryo is dependent on the efficient transport of K10 mRNA from nurse cells into the oocyte. To investigate the cis-requirements of K10 mRNA transport, we used a transgenic fly assay to analyze the expression patterns of a series of K10 deletion variants. Such studies identify a 44 nucleotide sequence within the K10 3' untranslated region that is required and sufficient for K10 mRNA transport and subsequent localization to the oocyte's anterior cortex. An inspection of the 44 nucleotide transport/localization sequence (TLS) reveals a strong potential for the formation of a stem-loop secondary structure. Nucleotide substitutions that interfere with the predicted base-pairing of the TLS block mRNA transport and anterior localization. Conversely, mutations that alter the base composition of the TLS while maintaining predicted base-pairing do not block mRNA transport or anterior localization. We conclude that K10 mRNA transport and anterior localization is mediated by a 44 nucleotide stem-loop structure. A similar putative stem-loop structure is found in the 3' untranslated region of the Drosophila orb mRNA, suggesting that the same factors mediate the transport and anterior localization of both K10 and orb mRNAs. Apart from orb, the K10 TLS is not found in any other localized mRNA, raising the possibility that the transport and localization of other mRNAs, e.g., bicoid, oskar and gurken, are mediated by novel sets of cis- and trans-acting factors. Moreover, we find that the K10 TLS overrides the activity of oskar cis-regulatory elements that mediate the late stage movement of the mRNA to the posterior pole. We propose the existence of a family of cis-regulatory elements that mediate mRNA transport into the oocyte, only some of which are compatible with the elements that mediate late stage movements.