piRNAs： 调控胚胎发育过程中的DNA从头甲基化的调控系统

Tlexander

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啥都不说了，研究胚胎发育，及DNA甲基化的同学们，庆祝吧：! I# b, h) [8 ~( \$ v' B/ x( l
piRNAs and Piwi proteins have been implicated in transposon control and are linked to transposon methylation in mammals. Here we examined the construction of the piRNA system in the restricted developmental window in which methylation patterns are set during mammalian embryogenesis. We find robust expression of two Piwi family proteins, MIWI2 and MILI. Their associated piRNA profiles reveal differences from Drosophila wherein large piRNA clusters act as master regulators of silencing. Instead, in mammals, dispersed transposon copies initiate the pathway, producing primary piRNAs, which predominantly join MILI in the cytoplasm. MIWI2, whose nuclear localization and association with piRNAs depend upon MILI, is enriched for secondary piRNAs antisense to the elements that it controls. The Piwi pathway lies upstream of known mediators of DNA methylation, since piRNAs are still produced in dnmt3L mutants, which fail to methylate transposons. This implicates piRNAs as specificity determinants of DNA methylation in germ cells.

Xenia

piRNA ｉｎ　ｍｏｕｓｅ　？

Tlexander

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- C- t( l# B$ upiRNA很保守的，人，老鼠等都有

Tlexander

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3 A/ f, i  C  N并且可能更有意思的是，piRNA可能不仅存在于胚胎干细胞，及精子中，在cancer及正常体细胞中也广泛存在：这篇文章即是个例子：2 a1 n& ~- |) P  Z* i
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Piwi-interacting RNA (piRNA) are small RNA abundant in the germline across animal species. In fruit flies and mice, piRNA have been implicated in maintenance of genomic integrity by transposable elements silencing. Outside of the germline, piRNA have only been found in fruit fly ovarian follicle cells. Previous studies have further reported presence of multiple piRNA-like small RNA (pilRNA) in fly heads and a small number of pilRNA have been reported in mouse tissues and in human NK cells. Here, we analyze high-throughput small RNA sequencing data in more than 130 fruit fly, mouse and rhesus macaque samples. The results show widespread presence of pilRNA, displaying all known characteristics of piRNA in multiple somatic tissues of these three species. In mouse pancreas and macaque epididymis, pilRNA abundance was compatible with piRNA abundance in the germline. Using in situ hybridizations, we further demonstrate pilRNA co-localization with mRNA expression of Piwi-family genes in all macaque tissues. Further, using western blot, we have shown the expression of Miwi protein in mouse pancreas. These findings indicate that piRNA-like molecules might play important roles outside of the germline.

vegetax4132

求原文~

Tlexander

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1 Q- ?, K3 N3 W坐井观天不行，坐等楼下上传，我去给你加分

Xenia

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, ^  e% K3 k2 s4 g) m敢问你是做神马方向的。。