Abstract PIWI-interacting RNAs (piRNAs) are small regulatory RNAs that associate with members of the PIWI clade of the Argonaute superfamily of proteins. piRNAs are predominantly found in animal gonads. There they silence transposable elements (TEs), regulate gene expression and participate in DNA methylation, thus orchestrating proper germline development. Furthermore, PIWI proteins are also indispensable for the maintenance and differentiation capabilities of pluripotent stem cells in free-living invertebrate species with regenerative potential. Thus, PIWI proteins and piRNAs seem to constitute an essential molecular feature of somatic pluripotent stem cells and the germline. In keeping with this hypothesis, both PIWI proteins and piRNAs are enriched in neoblasts, the adult stem cells of planarian flatworms, and their presence is a prerequisite for the proper regeneration and perpetual tissue homeostasis of these animals. The piRNA pathway is required to maintain the unique biology of planarians because, in analogy to the animal germline, planarian piRNAs silence TEs and ensure stable genome inheritance. Moreover, planarian piRNAs also contribute to the degradation of numerous protein-coding transcripts, a function that may be critical for neoblast differentiation. This review gives an overview of the planarian piRNA pathway and of its crucial function in neoblast biology.

中文翻译：

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涡虫扁虫中的 piRNA 通路：新模型，新见解

摘要 PIWI 相互作用 RNA (piRNA) 是与 Argonaute 蛋白质超家族的 PIWI 进化枝成员相关的小调节 RNA。piRNA 主要存在于动物性腺中。在那里，它们使转座因子 (TE) 沉默，调节基因表达并参与 DNA 甲基化，从而协调适当的生殖系发育。此外，PIWI 蛋白对于具有再生潜力的自由生活无脊椎动物物种的多能干细胞的维持和分化能力也是必不可少的。因此，PIWI 蛋白和 piRNA 似乎构成了体细胞多能干细胞和生殖系的基本分子特征。与这一假设一致，PIWI 蛋白和 piRNA 都富含新母细胞，涡虫扁虫的成体干细胞，它们的存在是这些动物适当再生和永久组织稳态的先决条件。piRNA 通路是维持涡虫独特生物学所必需的，因为与动物生殖系类似，涡虫 piRNA 使 TE 沉默并确保稳定的基因组遗传。此外，涡虫 piRNA 还有助于许多蛋白质编码转录物的降解，这一功能可能对新生细胞分化至关重要。本综述概述了涡虫 piRNA 通路及其在新生细胞生物学中的关键功能。涡虫 piRNA 也有助于许多蛋白质编码转录物的降解，这一功能可能对新生细胞分化至关重要。本综述概述了涡虫 piRNA 通路及其在新生细胞生物学中的关键功能。涡虫 piRNA 也有助于许多蛋白质编码转录物的降解，这一功能可能对新生细胞分化至关重要。本综述概述了涡虫 piRNA 通路及其在新生细胞生物学中的关键功能。