Krause Mirja, Rak-Raszewska Aleksandra, Naillat Florence, Saarela Ulla, Schmidt Christina, Ronkainen Veli-Pekka, Bart Geneviève, Ylä-Herttuala Seppo, Vainio Seppo J
Biocenter Oulu, Laboratory of Developmental Biology, InfoTech Oulu, Center for Cell Matrix Research, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
The Ritchie Centre, Hudson Institute of Medical Research Core, Clayton, Australia.
J Extracell Vesicles. 2018 Jan 23;7(1):1422675. doi: 10.1080/20013078.2017.1422675. eCollection 2018.
The subfraction of extracellular vesicles, called exosomes, transfers biological molecular information not only between cells but also between tissues and organs as nanolevel signals. Owing to their unique properties such that they contain several RNA species and proteins implicated in kidney development, exosomes are putative candidates to serve as developmental programming units in embryonic induction and tissue interactions. We used the mammalian metanephric kidney and its nephron-forming mesenchyme containing the nephron progenitor/stem cells as a model to investigate if secreted exosomes could serve as a novel type of inductive signal in a process defined as embryonic induction that controls organogenesis. As judged by several characteristic criteria, exosomes were enriched and purified from a cell line derived from embryonic kidney ureteric bud (UB) and from primary embryonic kidney UB cells, respectively. The cargo of the UB-derived exosomes was analysed by qPCR and proteomics. Several miRNA species that play a role in Wnt pathways and enrichment of proteins involved in pathways regulating the organization of the extracellular matrix as well as tissue homeostasis were identified. When labelled with fluorescent dyes, the uptake of the exosomes by metanephric mesenchyme (MM) cells and the transfer of their cargo to the cells can be observed. Closer inspection revealed that besides entering the cytoplasm, the exosomes were competent to also reach the nucleus. Furthermore, fluorescently labelled exosomal RNA enters into the cytoplasm of the MM cells. Exposure of the embryonic kidney-derived exosomes to the whole MM in an organ culture setting did not lead to an induction of nephrogenesis but had an impact on the overall organization of the tissue. We conclude that the exosomes provide a novel signalling system with an apparent role in secondary embryonic induction regulating organogenesis.
细胞外囊泡的亚组分，即外泌体，作为纳米级信号不仅在细胞之间传递生物分子信息，还在组织和器官之间传递。由于外泌体具有独特的性质，即它们包含几种与肾脏发育有关的RNA种类和蛋白质，因此外泌体被认为是在胚胎诱导和组织相互作用中作为发育编程单元的候选者。我们以哺乳动物的后肾及其含有肾单位祖细胞/干细胞的肾单位形成间充质为模型，研究分泌的外泌体是否能在定义为控制器官发生的胚胎诱导过程中作为一种新型的诱导信号。根据几个特征标准判断，分别从源自胚胎肾输尿管芽（UB）的细胞系和原代胚胎肾UB细胞中富集并纯化了外泌体。通过qPCR和蛋白质组学分析了UB来源外泌体的货物。鉴定出了几种在Wnt通路中起作用的miRNA种类以及参与调节细胞外基质组织和组织稳态的通路中的蛋白质富集。当用荧光染料标记时，可以观察到后肾间充质（MM）细胞对外泌体的摄取及其货物向细胞的转移。进一步检查发现，除了进入细胞质外，外泌体还能够到达细胞核。此外，荧光标记的外泌体RNA进入MM细胞的细胞质。在器官培养环境中将源自胚胎肾的外泌体暴露于整个MM中不会导致肾发生的诱导，但会对组织的整体组织产生影响。我们得出结论，外泌体提供了一种新型的信号系统，在调节器官发生的次级胚胎诱导中具有明显作用。
