Membraneless RNA-protein granules play important roles in many different cell types and organisms. In particular, granules found in germ cells have been used as a paradigm to study large and dynamic granules. These germ granules contain RNA and proteins required for germline development. Here, we unexpectedly identify large granules in specific subtypes of glial cells (“glial granules”) of the adult Drosophila brain which contain polypeptides with previously characterized roles in germ cells including scaffold Tudor, Vasa, Polar granule component and Piwi family proteins. Interestingly, our super-resolution microscopy analysis shows that in the glial granules, these proteins form distinct partially overlapping clusters. Furthermore, we show that glial granule scaffold protein Tudor functions in silencing of transposable elements and in small regulatory piRNA biogenesis. Remarkably, our data indicate that the adult brain contains a small population of cells, which express both neuroblast and germ cell proteins. These distinct cells are evolutionarily conserved and expand during aging suggesting the existence of age-dependent signaling. Our work uncovers previously unknown glial granules and indicates the involvement of their components in the regulation of brain transcriptome.

无膜RNA蛋白质颗粒在许多不同的细胞类型和生物中起着重要作用。特别地，在生殖细胞中发现的颗粒已被用作研究大型动态颗粒的范例。这些胚芽颗粒包含种系发育所需的RNA和蛋白质。在这里，我们意外地发现了果蝇成年胶质细胞的特定亚型中的大颗粒（“胶质颗粒”）大脑含有在生殖细胞中具有先前特征的多肽，包括脚手架Tudor，Vasa，Polar颗粒成分和Piwi家族蛋白。有趣的是，我们的超分辨率显微镜分析表明，在神经胶质颗粒中，这些蛋白质形成了截然不同的部分重叠的簇。此外，我们表明，神经胶质颗粒支架蛋白Tudor在转座因子沉默和小的调控piRNA生物发生中起作用。值得注意的是，我们的数据表明，成年大脑中有一小部分细胞表达神经母细胞和生殖细胞蛋白。这些不同的细胞在进化上是保守的，并且在衰老过程中会扩张，这表明存在依赖年龄的信号传导。