The role of Tudor family proteins in piRNA biogenesis and genome defense.

pirna是最近发现的一类非编码rna，可保护动物种系基因组免受转座子活性的影响。它们可以防止基因组不稳定，并确保将可靠的信息传递给下一代。最近，在体细胞中也发现了piRNA，表明其在基因表达调控中的作用，并与包括不孕症和癌症在内的多种疾病有关。然而，pirna的产生和作用机制在很大程度上仍然是不明确的，阻碍了它们在生物技术或医学上的应用。最近的基因组筛选发现，都铎结构域蛋白是piRNA通路中特别丰富的参与者。通过与piwi和解旋酶的相互作用，它们可以介导各种大分子复合物的组装并发挥中心协调作用。迄今为止，只有少数含有都铎蛋白的蛋白质被详细研究过，它们的多样性、特异性和分子功能仍然难以捉摸。在这里，我们利用综合生物化学、结构生物学和细胞生物学的方法，开始表征一个关键的含有tudor的piRNA生物发生因子，Qin/Kumo。我们的目标是了解：i)都铎如何特异性地识别几种伴侣蛋白；ii)各都铎域如何与其他域交互和通信；iii)它们如何协调piRNA因子的作用；iv)以及它们在piRNA生物发生中的确切作用。我们的结果将为仍然神秘的piRNA生物发生过程提供关键见解，并建立Tudor功能的一般原理。最终，这将使拮抗剂的合理设计能够干扰piRNA通路，为该通路的应用开辟新的途径，用于研究疾病机制，改进基于转座子的基因工程，甚至医学。

piRNAs form a recently discovered class of non-coding RNAs that protect the germline genome of animals from the activity of resident transposons. They prevent genome instability and ensure faithful information transfer to the next generation. Lately, piRNA were also found in somatic cells, suggesting their role in gene expression regulation and were implicated in various diseases including infertility and cancer. However, the mechanism of production and action of piRNAs is still largely ambiguous, preventing their applications in biotechnology or medicine. Recent genomic screens have identified Tudor domain containing proteins as particularly abundant players in the piRNA pathway. By interacting with PIWIs and helicases they could mediate the assembly of various macromolecular complexes and play a central coordinating role. Only few Tudor-containing proteins have been studied in detail to date, and their diversity, specificity and molecular function remains elusive. Here, we embark in characterizing a critical Tudor-containing piRNA biogenesis factors, Qin/Kumo, using an integrated biochemistry, structural biology, and cell biology approach. We aim to understand: i) how Tudors recognize several partner proteins specifically; ii) how various Tudor domains interact and communicate with other domains; iii) how they coordinate the action of piRNA factors; iv) and what is their exact role in piRNA biogenesis. Our results will provide key insights into the still mysterious process of piRNA biogenesis, and establish general principles of Tudor function. Ultimately, this will enable the rational design of antagonists to interfere with the piRNA pathway, opening new avenues towards applications of the pathway for studying disease mechanisms, improving transposon-based genetic engineering, and even for medicine.