The conserved RNA helicase Vasa is required for germ cell development in many organisms. In Drosophila melanogaster loss of PIWI-interacting RNA pathway components, including Vasa, causes Chk2-dependent oogenesis arrest. However, whether the arrest is due to Chk2 signaling at a specific stage and whether continuous Chk2 signaling is required for the arrest is unknown. Here, we show that absence of Vasa during the germarial stages causes Chk2-dependent oogenesis arrest. Additionally, we report the age-dependent decline of the ovariole number both in flies lacking Vasa expression only in the germarium and in loss-of-function vasa mutant flies. We show that Chk2 activation exclusively in the germarium is sufficient to interrupt oogenesis and to reduce ovariole number in aging flies. Once induced in the germarium, Chk2-mediated arrest of germ cell development cannot be overcome by restoration of Vasa or by downregulation of Chk2 in the arrested egg chambers. These findings, together with the identity of Vasa-associated proteins identified in this study, demonstrate an essential role of the helicase in the germ cell lineage maintenance and indicate a function of Vasa in germline stem cell homeostasis.

中文翻译：

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果蝇生殖细胞谱系稳态需要 Vasa RNA 解旋酶。


许多生物体的生殖细胞发育都需要保守的 RNA 解旋酶 Vasa。在果蝇中，PIWI 相互作用的 RNA 通路成分（包括 Vasa）的丢失会导致 Chk2 依赖性卵子发生停滞。然而，逮捕是否是由于特定阶段的 Chk2 信号传导以及逮捕是否需要连续的 Chk2 信号传导尚不清楚。在这里，我们发现在胚芽阶段 Vasa 的缺失会导致 Chk2 依赖性卵子发生停滞。此外，我们报告了仅在生殖细胞中缺乏 Vasa 表达的果蝇和功能丧失的 vasa 突变果蝇中卵巢数量的年龄依赖性下降。我们发现，仅在生殖细胞中的 Chk2 激活足以中断卵子发生并减少衰老果蝇的卵巢数量。一旦在生殖细胞中被诱导，Chk2 介导的生殖细胞发育停滞就不能通过 Vasa 的恢复或停滞的卵室中 Chk2 的下调来克服。这些发现以及本研究中鉴定的 Vasa 相关蛋白的身份，证明了解旋酶在生殖细胞谱系维持中的重要作用，并表明 Vasa 在生殖系干细胞稳态中的功能。