A novel model of THO/TREX loading onto target RNAs in metazoan gene expression
A novel model of THO/TREX loading onto target RNAs in metazoan gene expression
BMB Reports. 2016. Jul, 49(7): 355-356
Copyright © 2016, Korean Society for Biochemistry and Molecular Biology
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  • Received : June 14, 2016
  • Published : July 31, 2016
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Junho K., Hur
Center for Genome Engineering, Institute for Basic Science, Seoul 08826
Yun Doo, Chung
Department of Life Science, University of Seoul, Seoul 02504, Korea

The THO/TREX complex consists of several conserved subunits and is required for mRNA export. In metazoans, THO/TREX binds a subset of mRNAs during RNA splicing, and facilitates their nuclear export. How THO/TREX selects RNA targets is, however, incompletely understood. In our recent study, we reported that THO is loaded onto Piwi-interacting RNA (piRNA) precursor transcripts independent of splicing, and facilitates convergent transcription in Drosophila ovary. The precursors are later processed into mature piRNAs, small noncoding RNAs that silence transposable elements (TEs). We observed that piRNAs originating from dual-strand clusters, where precursors are transcribed from both strands, were specifically affected by THO mutation. Analysis of THO-bound RNAs showed enrichment of dual-strand cluster transcripts. Interestingly, THO loading onto piRNA precursors was dependent on Cutoff (Cuff), which comprises the Rhino-Deadlock-Cutoff (RDC) complex that is recruited to dual-strand clusters by recognizing H3K9me3 and licenses convergent transcription from he cluster. We also found that THO mutation affected transcription from dual-strand clusters. Therefore, we concluded that THO/TREX is recruited to dual-strand piRNA clusters, independent of splicing events, via multi-protein interactions with chromatin structure. Then, it facilitates transcription likely by suppressing premature termination to ensure adequate expression of piRNA precursors. [BMB Reports 2016; 49(7): 355-356]
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This work was supported by grants from the Basic Science Research Program through the National Research Foundation of Korea (NRF) (no. 2015R1A2A2A01003598) to YDC.