UMass Chan Medical School Faculty Publications


piRNA-independent transposon silencing by the Drosophila THO complex

UMMS Affiliation

Program in Molecular Medicine; Program in Bioinformatics and Integrative Biology; Graduate School of Biomedical Sciences

Publication Date


Document Type



Amino Acids, Peptides, and Proteins | Cell and Developmental Biology | Nucleic Acids, Nucleotides, and Nucleosides


piRNAs guide Piwi/Panoramix-dependent H3K9me3 chromatin modification and transposon silencing during Drosophila germline development. The THO RNA export complex is composed of Hpr1, Tho2, and Thoc5-7. Null thoc7 mutations, which displace Thoc5 and Thoc6 from a Tho2-Hpr1 subcomplex, reduce expression of a subset of germline piRNAs and increase transposon expression, suggesting that THO silences transposons by promoting piRNA biogenesis. Here, we show that the thoc7-null mutant combination increases transposon transcription but does not reduce anti-sense piRNAs targeting half of the transcriptionally activated transposon families. These mutations also fail to reduce piRNA-guided H3K9me3 chromatin modification or block Panoramix-dependent silencing of a reporter transgene, and unspliced transposon transcripts co-precipitate with THO through a Piwi- and Panoramix-independent mechanism. Mutations in piwi also dominantly enhance germline defects associated with thoc7-null alleles. THO thus functions in a piRNA-independent transposon-silencing pathway, which acts cooperatively with Piwi to support germline development.


H3K4me2, H3K9me3, Piwi, THO, Thoc7, germline development, piRNA, transcriptional silencing, transposon silencing

DOI of Published Version



Zhang G, Yu T, Parhad SS, Ho S, Weng Z, Theurkauf WE. piRNA-independent transposon silencing by the Drosophila THO complex. Dev Cell. 2021 Sep 27;56(18):2623-2635.e5. doi: 10.1016/j.devcel.2021.08.021. Epub 2021 Sep 20. PMID: 34547226; PMCID: PMC8567991. Link to article on publisher's site

Related Resources

Link to Article in PubMed

Journal/Book/Conference Title

Developmental cell

PubMed ID