Abstract
THOC5, a member of the THO complex, is essential for the 3′processing of some inducible genes, the export of a subset of mRNAs and stem cell survival. Here we show that THOC5 depletion results in altered 3′cleavage of >50% of mRNAs and changes in RNA polymerase II binding across genes. THOC5 is recruited close to high-density polymerase II sites, suggesting that THOC5 is involved in transcriptional elongation. Indeed, measurement of elongation rates in vivo demonstrated decreased rates in THOC5-depleted cells. Furthermore, THOC5 is preferentially recruited to its target genes in slow polymerase II cells compared with fast polymerase II cells. Importantly chromatin-associated THOC5 interacts with CDK12 (a modulator of transcription elongation) and RNA helicases DDX5, DDX17, and THOC6 only in slow polymerase II cells. The CDK12/THOC5 interaction promotes CDK12 recruitment to R-loops in a THOC6-dependent manner. These data demonstrate a novel function of THOC5 in transcription elongation.
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•THOC5 depletion decreased transcription elongation rates globally•3′ end cleavage of more than 50% of genes was altered in THOC5-depleted cells•The rate of transcription elongation determines polyA site usage•THOC5/THOC6 recruit CDK12 and DDX5/17 to regulate R loop structures and elongation rate
Molecular biology; Cell biology