Proper stem cell activity in tissues ensures the correct balance between proliferation and differentiation, thus allowing tissue homeostasis and repair. The Drosophila ovary develops well-defined niches that contain on average 2-4 germline stem cells (GSCs), whose maintenance depends on systemic signals and local factors. A known player in the decline of tissue homeostasis is ageing, which correlates with the waning of resident stem cell populations. In Drosophila, ovaries from old females contain fewer GSCs than those from young flies. We isolated niche cells of aged ovaries, performed a transcriptomic analysis and identified mastermind (mam) as a factor for Drosophila ovarian niche functionality during ageing. We show that mam is upregulated in aged niche cells and that we can induce premature GSC loss by overexpressing mam in otherwise young niche cells. High mam levels in niche cells induce reduced Hedgehog amounts, a decrease in cadherin levels and a likely increase in reactive oxygen species, three scenarios known to provoke GSC loss. Mam is a canonical co-activator of the Notch pathway in many Drosophila tissues. However, we present evidence to support a Notch-independent role for mam in the ovarian germline niche.

中文翻译：

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策划者独立于果蝇卵巢中的Notch途径调节生态位衰老。

组织中适当的干细胞活性可确保增殖与分化之间的正确平衡，从而实现组织的稳态和修复。果蝇卵巢发育良好，发育良好，平均含有2-4个种系干细胞（GSC），其维持取决于系统性信号和局部因素。组织稳态下降的一个已知因素是衰老，这与驻留干细胞数量的减少有关。在果蝇中，老年雌性卵巢中的GSC含量低于年轻蝇中的卵巢。我们分离了老年卵巢的利基细胞，进行了转录组学分析，并确定了策划者（妈妈）是衰老过程中果蝇卵巢利基功能的一个因素。我们表明，在老年的利基细胞中，mam上调，并​​且我们可以通过在其他年轻的利基细胞中过表达mam来诱导过早的GSC丧失。利基细胞中高的mam含量会导致刺猬数量减少，cadherin含量降低以及活性氧的可能增加，这是已知的引起GSC丧失的三种情况。在许多果蝇组织中，Mam是Notch途径的典型共激活因子。但是，我们目前的证据支持在卵巢种系生态位中，哺乳动物的Notch独立作用。