Human THO coordinates transcription termination and subsequent transcript release from the HSP70 locus

Abstract

A multiprotein complex, THO/TREX, couples the transcription, 3′‐end formation and nuclear export of mRNAs. In this study, we report that crucial factors for mRNA processing, such as XRN2, DDX5/DDX17 and CstF64, are copurified with human THO (hTHO). Using chromatin immunoprecipitation, we found increased cross‐linking of XRN2 and CstF64 to the RNA polymerase II (RNAP II) pause site of the HSPA1A gene upon down‐regulation of THOC5, a metazoan‐specific component of hTHO. As observed in THOC5‐depleted cells, knockdown of XRN2 blocked HSP70 transcript release and increased the amount of CstF64 at the pause site. In addition, our data indicate that DDX5/DDX17 is also required for HSP70 transcript release. As the degradation of read‐through transcripts, but not cleavage at polyadenylation sites per se, was hindered upon THOC5 or DDX5/DDX17 down‐regulation, these factors appear to influence transcriptional termination. Interestingly, over‐expression of RNase H suppressed the accumulation of HSP70 transcripts in nuclear foci in THOC5‐ or DDX5/DDX17‐depleted cells. Thus, we propose a model in which hTHO, along with DDX5/DDX17, restricts the formation of R‐loops, thereby facilitating the XRN2‐mediated transcriptional termination and release of the mature transcript from the HSPA1A locus.

Intrapopulation adaptive variance supports selective breeding in a reef-building coral

“…MAP kinase cascades were also important for adults and larval selection, though through complementary ontologies (ERK 1/2 cascades and JUN-kinase activity), highlighting the prominence of signaling pathways in coping with bleaching stress at various life history stages. In larvae, we also documented similar strong selection in both cross and nonbleached phenotypes on the BRCA1-BARD1 complex, which is involved in DNA repair and ubiquitination, rRNA transcription, and potential interactions between JUN-kinase activity and the THO complex, which regulates HSP70 export from the nucleus 61,62 . Importantly, the selection on the two crosses is broadly different, with less than a quarter of significantly selected ontologies shared between phenotypes, which indicates differential selection between the site-wide cross and nonbleached pool is much broader than coordinated selection.…”

Nucleocytoplasmic shuttling of Gle1 impacts DDX1 at transcription termination sites

“…R-loops act as a powerful inhibitor of RNA Pol II downstream of the TTS (Skourti-Stathaki et al, 2011;Ginno et al, 2013), and proper termination and cleavage depend on the removal of these R-loops. Indeed, increased R-loop persistence results in the accumulation of CstF-64 at cleavage sites (Katahira et al, 2019). We mined the Rloop database, which uses the quantitative R-loop forming sequence (RLFS) prediction model (QmRLFS; Supplemental Table S1), to identify Gle1-SD accumulated transcripts with a propensity for 3′-UTR R-loops (Wongsurawat et al, 2012;Jenjaroenpun et al, 2015).…”

Dynamic changes in mRNA nucleocytoplasmic localization in the nitrate response of Arabidopsis roots

“…The temporal retention of mRNAs in the nucleus is a strategy for controlling the expression of transcripts synthesized during bursts of transcription (Bahar Halpern et al, 2015; Tudek et al, 2019). This can be achieved, for instance, by blocking the release of the transcripts from the gene locus and avoiding them from reaching the nuclear pore complex (Katahira et al, 2019; Singh et al, 2019). Our results are consistent with this model.…”