Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
Development. 2021 Sep 15;148(18). doi: 10.1242/dev.196121. Epub 2021 Apr 15.
The Hunchback (Hb) transcription factor is crucial for anterior-posterior patterning of the Drosophila embryo. The maternal hb mRNA acts as a paradigm for translational regulation due to its repression in the posterior of the embryo. However, little is known about the translatability of zygotically transcribed hb mRNAs. Here, we adapt the SunTag system, developed for imaging translation at single-mRNA resolution in tissue culture cells, to the Drosophila embryo to study the translation dynamics of zygotic hb mRNAs. Using single-molecule imaging in fixed and live embryos, we provide evidence for translational repression of zygotic SunTag-hb mRNAs. Whereas the proportion of SunTag-hb mRNAs translated is initially uniform, translation declines from the anterior over time until it becomes restricted to a posterior band in the expression domain. We discuss how regulated hb mRNA translation may help establish the sharp Hb expression boundary, which is a model for precision and noise during developmental patterning. Overall, our data show how use of the SunTag method on fixed and live embryos is a powerful combination for elucidating spatiotemporal regulation of mRNA translation in Drosophila.
驼峰（Hb）转录因子对于果蝇胚胎的前后模式形成至关重要。母体 hb mRNA 因其在胚胎后部受到抑制而成为翻译调控的典范。然而，关于合子转录的 hb mRNA 的可翻译性知之甚少。在这里，我们适应了 SunTag 系统，该系统专为在组织培养细胞中单 mRNA 分辨率下的翻译成像而开发，用于研究合子 hb mRNA 的翻译动力学。通过固定和活体胚胎中的单分子成像，我们为合子 SunTag-hb mRNA 的翻译抑制提供了证据。虽然翻译的 SunTag-hb mRNA 的比例最初是均匀的，但随着时间的推移，翻译从前端下降，直到它仅限于表达域中的后端带。我们讨论了受调控的 hb mRNA 翻译如何有助于建立尖锐的 Hb 表达边界，这是发育模式形成过程中精度和噪声的模型。总的来说，我们的数据表明，在固定和活体胚胎上使用 SunTag 方法是阐明果蝇中 mRNA 翻译时空调控的强大组合。
