title: piRNA pathway targets active LINE1 elements to establish the repressive H3K9me3 mark in germ cells.
abstract: Transposable elements (TEs) occupy a large fraction of metazoan genomes and pose a constant threat to genomic integrity. This threat is particularly critical in germ cells, as changes in the genome that are induced by TEs will be transmitted to the next generation. Small noncoding piwi-interacting RNAs (piRNAs) recognize and silence a diverse set of TEs in germ cells. In mice, piRNA-guided transposon repression correlates with establishment of CpG DNA methylation on their sequences, yet the mechanism and the spectrum of genomic targets of piRNA silencing are unknown. Here we show that in addition to DNA methylation, the piRNA pathway is required to maintain a high level of the repressive H3K9me3 histone modification on long interspersed nuclear elements (LINEs) in germ cells. piRNA-dependent chromatin repression targets exclusively full-length elements of actively transposing LINE families, demonstrating the remarkable ability of the piRNA pathway to recognize active elements among the large number of genomic transposon fragments.
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA;
authors.forename: Dubravka
authors.initials: D
authors.lastname: Pezic
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA;
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Manakov
authors.affiliation: Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Sachidanandam
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA;
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Aravin
mesh_terms: D000818:Animals; D002843:Chromatin / Q000378:metabolism; D018899:CpG Islands; D019175:DNA Methylation; D005786:Gene Expression Regulation; D020868:Gene Silencing; D016678:Genome / Q000235:genetics; D005854:Germ Cells / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D009154:Mutation; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*
chemical_list: D002843:Chromatin; D006657:Histones; D034741:RNA, Small Interfering
keywords: H3K9me3; piRNA; transposon