Institute of Experimental Cancer Research, Comprehensive Cancer Center Ulm, University Hospital Ulm, Ulm, Germany.
Stem Cells. 2012 Dec;30(12):2603-11. doi: 10.1002/stem.1237.
Piwi proteins and their associated piRNAs are essential for preserving the self-renewal property of mammalian germ stem cells. Their highly conserved role in CpG island DNA methylation and chromatin modifications in germ stem cells has long been associated with transposon silencing but recent reports hint at protein coding regions being targets for Piwi-mediated epigenetic changes as well. Interestingly, the expression of PIWI family members is not restricted to the germline, and certain members have also been implicated in tumorigenesis in cases of adenocarcinomas, gliomas, and sarcomas. The following review discusses our knowledge of the function of Piwi proteins and piRNAs in suppressing transposable elements while maintaining the self-renewing population of germ stem cells. We also highlight the somatic function of Piwi as an epigenetic modifier. Furthermore, we summarize the recently uncovered involvement of Piwi proteins and piRNAs in various cancers.
Piwi 蛋白及其相关的 piRNA 对于维持哺乳动物生殖干细胞的自我更新特性至关重要。它们在生殖干细胞中 CpG 岛 DNA 甲基化和染色质修饰中的高度保守作用长期以来一直与转座子沉默有关，但最近的报告暗示蛋白质编码区域也是 Piwi 介导的表观遗传变化的靶点。有趣的是，PIWI 家族成员的表达不仅局限于生殖系，某些成员在腺癌、神经胶质瘤和肉瘤的肿瘤发生中也被牵连。以下综述讨论了我们对 Piwi 蛋白和 piRNA 在抑制转座元件的同时维持生殖干细胞自我更新群体的功能的认识。我们还强调了 Piwi 作为表观遗传修饰物的体细胞功能。此外，我们总结了最近发现的 Piwi 蛋白和 piRNA 在各种癌症中的参与。
