Project description:The exosome functions in the degradation of diverse RNA species, yet how it is negatively regulated remains largely unknown. Here, we show that NRDE2 forms a 1:1 complex with MTR4, a nuclear exosome cofactor critical for exosome recruitment, via a conserved MTR4-interacting domain (MID). Unexpectedly, NRDE2 mainly localizes in nuclear speckles, where it inhibits MTR4 recruitment and RNA degradation, and thereby ensures efficient mRNA nuclear export. Structural and biochemical data revealed that NRDE2 interacts with MTR4's key residues, locks MTR4 in a closed conformation, and inhibits MTR4 interaction with the exosome as well as proteins important for MTR4 recruitment, such as the cap-binding complex (CBC) and ZFC3H1. Functionally, MID deletion results in the loss of self-renewal of mouse embryonic stem cells. Together, our data pinpoint NRDE2 as a nuclear exosome negative regulator that ensures mRNA stability and nuclear export.
Project description:We have analysed the activity of the nuclear exosome during meiosis by deletion of TRF4, which encodes a key component of the exosome targeting complex TRAMP. We find that TRAMP mutants produce high levels of CUTs during meiosis that are undetectable in wild-type cells, showing that the nuclear exosome remains functional for CUT degradation. Lack of TRAMP activity stabilises ~1600 CUTs in meiotic cells, which occupy 40% of the binding capacity of the nuclear cap binding complex (CBC). One sample each of Cbc2-associated RNA from wild-type and trf4-deleted cells at 6 hours of meiosis
Project description:Cryptic unstable transcripts (CUTs) are rapidly degraded by the nuclear exosome, however, the way they are recognized and targeted to the exosome is not fully understood. The recently identified Schizosaccharomyces pombe MTREC complex has been shown to promote degradation of meiotic mRNAs and regulatory ncRNAs. Here, we report that the MTREC complex is also the major nuclear exosome targeting complex for CUTs and unspliced mRNAs. MTREC complex specifically binds to CUTs, meiotic mRNAs and unspliced mRNA transcripts and targets these RNAs for degradation by the nuclear exosome, while the TRAMP complex has only a minor role in this process. The MTREC complex physically interacts with the nuclear exosome and with various RNA-binding and -processing complexes, coupling RNA processing to the RNA degradation machinery. Our study reveals the central role of the evolutionarily conserved MTREC complex in RNA quality control, and in the recognition and elimination of aberrant, cryptic transcripts. Genome-wide expression analysis of MTREC, Nuclear Exosome, TRAMP, Nrd complex members All experiments were performed twice in biological replicates, except that rmn1Δ and mmi1Δ mei4-P572 were perfomed once.
Project description:Cryptic unstable transcripts (CUTs) are rapidly degraded by the nuclear exosome, however, the way they are recognized and targeted to the exosome is not fully understood. The recently identified Schizosaccharomyces pombe MTREC complex has been shown to promote degradation of meiotic mRNAs and regulatory ncRNAs. Here, we report that the MTREC complex is also the major nuclear exosome targeting complex for CUTs and unspliced mRNAs. MTREC complex specifically binds to CUTs, meiotic mRNAs and unspliced mRNA transcripts and targets these RNAs for degradation by the nuclear exosome, while the TRAMP complex has only a minor role in this process. The MTREC complex physically interacts with the nuclear exosome and with various RNA-binding and -processing complexes, coupling RNA processing to the RNA degradation machinery. Our study reveals the central role of the evolutionarily conserved MTREC complex in RNA quality control, and in the recognition and elimination of aberrant, cryptic transcripts. All experiments were performed twice in biological replicates.
Project description: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.
Project description:We have analysed the activity of the nuclear exosome during meiosis by deletion of TRF4, which encodes a key component of the exosome targeting complex TRAMP. We find that TRAMP mutants produce high levels of CUTs during meiosis that are undetectable in wild-type cells, showing that the nuclear exosome remains functional for CUT degradation. Lack of TRAMP activity stabilises ~1600 CUTs in meiotic cells, which occupy 40% of the binding capacity of the nuclear cap binding complex (CBC).
Project description:Nuclear processing and quality control of eukaryotic RNA is mediated by the multi-subunit RNA exosome, which utilizes accessory factors to regulate its enzymatic activity. However, the mechanism of exosome recruitment to its ribonucleoprotein (RNP) targets remains poorly understood. Here we disclose a physical link between the human nuclear RNA exosome and the cap-binding complex (CBC). The CBC associates with the ARS2 protein to form CBC-ARS2 (CBCA), and then further connects together with the uncharacterized ZC3H18/NHN1 protein to the nuclear exosome targeting (NEXT) complex, forming CBC-NEXT (CBCN). RNA immunoprecipitation analysis using CBCN factors as baits as well as the combinatorial depletion of CBCN and exosome components underscore the functional relevance of CBC-exosome bridging at the level of target RNA. Specifically, CBCA suppresses read-through transcription of several RNA families by promoting their transcriptional termination. We suggest that the RNP 5M-bM-^@M-^Ycap links transcription termination to exosomal RNA degradation via CBCN. In total 10 samples; 4 control IP HeLa, 2 Flag- Ars2 IP, 2 Flag-CBP20 IP; and 2 GFP-RBM7 Ips. The signal intensity data was analyzed with the Affymetrix Tiling Analysis Software (v. 1.1) using parameters: one side upper, 90 bp bandwidth and perfect match only. Output txt files (i.e. result file). TASParam* files include parameter settings and input file information for the TAS analysis for each result file. The description of 'ProcessedDatas_TA.xls' file is provided in the 'README.txt'
Project description:Cryptic unstable transcripts (CUTs) are rapidly degraded by the nuclear exosome, however, the way they are recognized and targeted to the exosome is not fully understood. The recently identified Schizosaccharomyces pombe MTREC complex has been shown to promote degradation of meiotic mRNAs and regulatory ncRNAs. Here, we report that the MTREC complex is also the major nuclear exosome targeting complex for CUTs and unspliced mRNAs. MTREC complex specifically binds to CUTs, meiotic mRNAs and unspliced mRNA transcripts and targets these RNAs for degradation by the nuclear exosome, while the TRAMP complex has only a minor role in this process. The MTREC complex physically interacts with the nuclear exosome and with various RNA-binding and -processing complexes, coupling RNA processing to the RNA degradation machinery. Our study reveals the central role of the evolutionarily conserved MTREC complex in RNA quality control, and in the recognition and elimination of aberrant, cryptic transcripts. RNA sequencing of WT and mutant S.pombe strains, processed data is normalized to median non-intron containing gene-expression, no replicates