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Nuclear RNA export factor variant initiates piRNA‐guided co‐transcriptional silencing
Author(s) -
Murano Kensaku,
Iwasaki Yuka W,
Ishizu Hirotsugu,
Mashiko Akane,
Shibuya Aoi,
Kondo Shu,
Adachi Shungo,
Suzuki Saori,
Saito Kuniaki,
Natsume Tohru,
Siomi Mikiko C,
Siomi Haruhiko
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2019102870
Subject(s) - piwi interacting rna , biology , rasirna , psychological repression , gene silencing , heterochromatin , argonaute , genetics , small rna , rna , transposable element , microbiology and biotechnology , rna interference , gene , gene expression , mutant , chromatin
The PIWI‐interacting RNA (piRNA) pathway preserves genomic integrity by repressing transposable elements (TEs) in animal germ cells. Among PIWI‐clade proteins in Drosophila, Piwi transcriptionally silences its targets through interactions with cofactors, including Panoramix (Panx) and forms heterochromatin characterized by H3K9me3 and H1. Here, we identified Nxf2, a nuclear RNA export factor (NXF) variant, as a protein that forms complexes with Piwi, Panx, and p15. Panx–Nxf2–P15 complex formation is necessary in the silencing by stabilizing protein levels of Nxf2 and Panx. Notably, ectopic targeting of Nxf2 initiates co‐transcriptional repression of the target reporter in a manner independent of H3K9me3 marks or H1. However, continuous silencing requires HP1a and H1. In addition, Nxf2 directly interacts with target TE transcripts in a Piwi‐dependent manner. These findings suggest a model in which the Panx–Nxf2–P15 complex enforces the association of Piwi with target transcripts to trigger co‐transcriptional repression, prior to heterochromatin formation in the nuclear piRNA pathway. Our results provide an unexpected connection between an NXF variant and small RNA‐mediated co‐transcriptional silencing.