The RNA exosome is fundamental for the degradation of RNA in eukaryotic nuclei. Substrate targeting is facilitated by its co-factor Mtr4p/hMTR4, which links to RNA-binding protein adaptors. One such activity is the human Nuclear EXosome Targeting (NEXT) complex, composed of hMTR4, the Zn-finger protein ZCCHC8 and the RNA-binding factor RBM7. NEXT primarily targets early and unprocessed transcripts, demanding a rationale for how the nuclear exosome recognizes processed RNAs. Here, we describe the PolyA tail eXosome Targeting (PAXT) connection, comprising the hitherto uncharacterized ZFC3H1 Zn-knuckle protein as a central link between hMTR4 and the nuclear polyA binding protein PABPN1. Individual depletion of ZFC3H1 and PABPN1 results in the accumulation of common transcripts, that are generally both longer and more 3'polyadenylated than NEXT substrates. Importantly, ZFC3H1/PABPN1 and ZCCHC8/RBM7 contact hMTR4 in a mutually exclusive manner, revealing that the exosome targets nuclear transcripts of different maturation status by substituting its hMTR4-associating adaptors. Overall design: RNA from HeLa cells was analysed by next generation sequencing upon depletion of EGFP(control), RRP40, RBM7, ZCCHC8, PABPN1 and ZFC3H1. Both total and BrU RNA (one hour labeling) were collected for each condition in triplicates. The spike-in sequences used in the samples can be provided upon request.
Characterizing ZC3H18, a Multi-domain Protein at the Interface of RNA Production and Destruction Decisions.
Specimen part, Subject
View SamplesTermination of transcription is important for establishing gene punctuation marks. It is also critical for suppressing many of the pervasive transcription events occurring throughout eukaryotic genomes and coupling their RNA products to efficient decay. In human cells, the ARS2 protein has been implicated in such function as its depletion causes transcriptional read-through of selected gene terminators and because it physically interacts with the ribonucleolytic nuclear RNA exosome. Here, we study the role of ARS2 on transcription and RNA metabolism genome-wide. We show that ARS2 depletion negatively impacts levels of promoter-proximal RNA polymerase II (RNAPII) at protein-coding (pc) genes, Moreover, our results reveal a general role of ARS2 in transcription termination-coupled RNA turnover at short transcription units like snRNA-, replication dependent histone (RDH)-, promoter upstream transcript (PROMPT)- and enhancer RNA (eRNA)-loci. Depletion of the ARS2 interaction partner ZC3H18 mimics the ARS2 depletion, although to a milder extent, whereas depletion of the exosome core subunit RRP40 only impacts RNA abundance post-transcriptionally. Interestingly, ARS2 is also involved in transcription termination events within first introns of pc genes. Our work therefore establishes ARS2 as a general suppressor of pervasive transcription with the potential to regulate protein-coding gene expression. Overall design: RNA from HeLa cells was analysed by next generation sequencing upon depletion of EGFP(control), ARS2(SRRT), ZC3H18 and CBP80. Total RNA was collected for each condition in triplicates.
Characterizing ZC3H18, a Multi-domain Protein at the Interface of RNA Production and Destruction Decisions.
Specimen part, Subject
View Samples