Tindell Samuel J, Rouchka Eric C, Arkov Alexey L
Department of Biological Sciences, Murray State University, Murray, KY, 42071, USA.
Computer Science and Engineering Department, University of Louisville, Louisville, KY, 40292, USA.
Commun Biol. 2020 Nov 20;3(1):699. doi: 10.1038/s42003-020-01432-z.
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体中发挥着重要作用。特别是，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。这些生殖颗粒包含生殖系发育所需的RNA和蛋白质。在这里，我们意外地在成年果蝇大脑的特定胶质细胞亚型（“胶质颗粒”）中发现了大型颗粒，这些颗粒含有在生殖细胞中具有先前已确定作用的多肽，包括支架蛋白Tudor、Vasa、极地颗粒成分和Piwi家族蛋白。有趣的是，我们的超分辨率显微镜分析表明，在胶质颗粒中，这些蛋白质形成了不同的部分重叠簇。此外，我们表明胶质颗粒支架蛋白Tudor在转座子沉默和小调节性piRNA生物合成中发挥作用。值得注意的是，我们的数据表明，成年大脑中含有一小部分同时表达神经母细胞和生殖细胞蛋白的细胞。这些独特的细胞在进化上是保守的，并且在衰老过程中会增多，这表明存在年龄依赖性信号传导。我们的工作揭示了以前未知的胶质颗粒，并表明其成分参与了大脑转录组的调控。
