Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
Department of Bioscience and Biotechnology, Indian Institute of Technology, Kharagpur, India.
Nat Cell Biol. 2024 Nov;26(11):1934-1942. doi: 10.1038/s41556-024-01519-3. Epub 2024 Oct 1.
Ribonucleoprotein (RNP) granules are membraneless condensates that organize the intracellular space by compartmentalization of specific RNAs and proteins. Studies have shown that RNA tunes the phase behaviour of RNA-binding proteins, but the role of intermolecular RNA-RNA interactions in RNP granules in vivo remains less explored. Here we determine the role of a sequence-specific RNA-RNA kissing-loop interaction in assembly of mesoscale oskar RNP granules in the female Drosophila germline. We show that a two-nucleotide mutation that disrupts kissing-loop-mediated oskar messenger RNA dimerization impairs condensate formation in vitro and oskar granule assembly in the developing oocyte, leading to defective posterior localization of the RNA and abrogation of oskar-associated processing bodies upon nutritional stress. This specific trans RNA-RNA interaction acts synergistically with the scaffold RNA-binding protein, Bruno, in driving condensate assembly. Our study highlights the architectural contribution of an mRNA and its specific secondary structure and tertiary interactions to the formation of an RNP granule that is essential for embryonic development.
核糖核蛋白 (RNP) 颗粒是无膜的凝聚物，通过将特定的 RNA 和蛋白质分隔在不同的区域来组织细胞内空间。研究表明，RNA 可以调节 RNA 结合蛋白的相行为，但在体内 RNP 颗粒中，分子间的 RNA-RNA 相互作用的作用仍较少被探索。在这里，我们确定了一种序列特异性的 RNA-RNA 亲吻环相互作用在雌性果蝇生殖细胞中线粒体中组装中尺度 Oskar RNP 颗粒中的作用。我们表明，破坏亲吻环介导的 Oskar 信使 RNA 二聚化的两个核苷酸突变会损害体外凝聚物的形成和发育中的卵母细胞中 Oskar 颗粒的组装，导致 RNA 的后定位缺陷，并在营养胁迫时消除 Oskar 相关的加工体。这种特定的反式 RNA-RNA 相互作用与支架 RNA 结合蛋白 Bruno 协同作用，驱动凝聚物的组装。我们的研究强调了 mRNA 及其特定的二级结构和三级相互作用对形成对胚胎发育至关重要的 RNP 颗粒的结构贡献。
