Dual functions of Macpiwi1 in transposon silencing and stem cell maintenance in the flatworm Macrostomum lignano.
Dual functions of Macpiwi1 in transposon silencing and stem cell maintenance in the flatworm Macrostomum lignano.
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DOI：
10.1261/rna.052456.115
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发表时间：
2015-11
期刊：
影响因子：
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通讯作者：
Wasik KA
中科院分区：
文献类型：
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作者：
Zhou X;Battistoni G;El Demerdash O;Gurtowski J;Wunderer J;Falciatori I;Ladurner P;Schatz MC;Hannon GJ;Wasik KA
在动物种系发育过程中，PIWI蛋白和piRNA通路对转座子沉默和某些方面的基因调控至关重要。与大多数动物物种相比，一些扁形虫也在体细胞干细胞中表达piwi和pirna，这是组织更新和再生所必需的。在这里，我们已经鉴定和表征了新兴模式扁形虫Macrostomum lignano的pirna和PIWI蛋白。我们发现M. lignano至少编码三种PIWI蛋白。其中之一，Macpiwi1，在种系细胞和体细胞干细胞中作为典型piRNA通路的关键组成部分。敲低Macpiwi1显著降低piRNA水平，抑制转座子，并严重影响干细胞的维持。piRNA生物发生因子Macvasa的敲低导致piRNA水平进一步降低，相应的转座子增加。然而，在Macvasa敲低的动物中，我们没有发现对干细胞自我更新的重大影响。这些结果可能表明，扁虫中PIWI蛋白的干细胞维持功能与它们对转座子的影响不同，并且可能独立于被认为是典型的piRNA群体。
PIWI proteins and piRNA pathways are essential for transposon silencing and some aspects of gene regulation during animal germline development. In contrast to most animal species, some flatworms also express PIWIs and piRNAs in somatic stem cells, where they are required for tissue renewal and regeneration. Here, we have identified and characterized piRNAs and PIWI proteins in the emerging model flatworm Macrostomum lignano. We found that M. lignano encodes at least three PIWI proteins. One of these, Macpiwi1, acts as a key component of the canonical piRNA pathway in the germline and in somatic stem cells. Knockdown of Macpiwi1 dramatically reduces piRNA levels, derepresses transposons, and severely impacts stem cell maintenance. Knockdown of the piRNA biogenesis factor Macvasa caused an even greater reduction in piRNA levels with a corresponding increase in transposons. Yet, in Macvasa knockdown animals, we detected no major impact on stem cell self-renewal. These results may suggest stem cell maintenance functions of PIWI proteins in flatworms that are distinguishable from their impact on transposons and that might function independently of what are considered canonical piRNA populations.