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Jiang Y, Sun S, Liu X, Su K, Zhang C, Zhang P, Zhao Z, Su Y, Wang C, Du X. U3 snoRNA inter-regulates with DDX21 in the perichromosomal region to control mitosis. Cell Death Dis 2024; 15:342. [PMID: 38760378 PMCID: PMC11101645 DOI: 10.1038/s41419-024-06725-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 04/29/2024] [Accepted: 05/07/2024] [Indexed: 05/19/2024]
Abstract
U3 snoRNA is essential for ribosome biogenesis during interphase. Upon mitotic onset, the nucleolus disassembles and U3 snoRNA relocates to the perichromosomal region (PR) to be considered as a chromosome passenger. Whether U3 controls mitosis remains unknown. Here, we demonstrate that U3 snoRNA is required for mitotic progression. We identified DDX21 as the predominant U3-binding protein during mitosis and confirmed that U3 snoRNA colocalizes with DDX21 in the PR. DDX21 knockdown induces mitotic catastrophe and similar mitotic defects caused by U3 snoRNA depletion. Interestingly, the uniform PR distribution of U3 snoRNA and DDX21 is interdependent. DDX21 functions in mitosis depending on its PR localization. Mechanistically, U3 snoRNA regulates DDX21 PR localization through maintaining its mobility. Moreover, Cy5-U3 snoRNA downsizes the fibrous condensates of His-DDX21 at proper molecular ratios in vitro. This work highlights the importance of the equilibrium between U3 snoRNA and DDX21 in PR formation and reveals the potential relationship between the PR assembly and mitotic regulation.
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Affiliation(s)
- Yang Jiang
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Shiqi Sun
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Xiaofeng Liu
- Hepatopancreatobiliary Surgery Department I, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Cancer Hospital & Institute, Peking University, Beijing, 100142, China
| | - Kunqi Su
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Chunfeng Zhang
- Department of Medical Genetics, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Peipei Zhang
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Zhuochen Zhao
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Ya Su
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Chang Wang
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China
| | - Xiaojuan Du
- Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing, 100083, China.
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2
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Viera T, Abfalterer Q, Neal A, Trujillo R, Patidar PL. Molecular Basis of XRN2-Deficient Cancer Cell Sensitivity to Poly(ADP-ribose) Polymerase Inhibition. Cancers (Basel) 2024; 16:595. [PMID: 38339346 PMCID: PMC10854503 DOI: 10.3390/cancers16030595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/12/2024] Open
Abstract
R-loops (RNA-DNA hybrids with displaced single-stranded DNA) have emerged as a potent source of DNA damage and genomic instability. The termination of defective RNA polymerase II (RNAPII) is one of the major sources of R-loop formation. 5'-3'-exoribonuclease 2 (XRN2) promotes genome-wide efficient RNAPII termination, and XRN2-deficient cells exhibit increased DNA damage emanating from elevated R-loops. Recently, we showed that DNA damage instigated by XRN2 depletion in human fibroblast cells resulted in enhanced poly(ADP-ribose) polymerase 1 (PARP1) activity. Additionally, we established a synthetic lethal relationship between XRN2 and PARP1. However, the underlying cellular stress response promoting this synthetic lethality remains elusive. Here, we delineate the molecular consequences leading to the synthetic lethality of XRN2-deficient cancer cells induced by PARP inhibition. We found that XRN2-deficient lung and breast cancer cells display sensitivity to two clinically relevant PARP inhibitors, Rucaparib and Olaparib. At a mechanistic level, PARP inhibition combined with XRN2 deficiency exacerbates R-loop and DNA double-strand break formation in cancer cells. Consistent with our previous findings using several different siRNAs, we also show that XRN2 deficiency in cancer cells hyperactivates PARP1. Furthermore, we observed enhanced replication stress in XRN2-deficient cancer cells treated with PARP inhibitors. Finally, the enhanced stress response instigated by compromised PARP1 catalytic function in XRN2-deficient cells activates caspase-3 to initiate cell death. Collectively, these findings provide mechanistic insights into the sensitivity of XRN2-deficient cancer cells to PARP inhibition and strengthen the underlying translational implications for targeted therapy.
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Affiliation(s)
| | | | | | | | - Praveen L. Patidar
- Department of Chemistry, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
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3
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Cortázar MA, Fong N, Bentley DL. Genome-wide Mapping of 5'-monophosphorylated Ends of Mammalian Nascent RNA Transcripts. Bio Protoc 2023; 13:e4828. [PMID: 37753464 PMCID: PMC10518774 DOI: 10.21769/bioprotoc.4828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/08/2023] [Accepted: 05/15/2023] [Indexed: 09/28/2023] Open
Abstract
In eukaryotic cells, RNA biogenesis generally requires processing of the nascent transcript as it is being synthesized by RNA polymerase. These processing events include endonucleolytic cleavage, exonucleolytic trimming, and splicing of the growing nascent transcript. Endonucleolytic cleavage events that generate an exposed 5'-monophosphorylated (5'-PO4) end on the growing nascent transcript occur in the maturation of rRNAs, tRNAs, and mRNAs. These 5'-PO4 ends can be a target of further processing or be subjected to 5'-3' exonucleolytic digestion that may result in termination of transcription. Here, we describe how to identify 5'-PO4 ends of intermediates in nascent RNA metabolism. We capture these species via metabolic labeling with bromouridine followed by immunoprecipitation and specific ligation of 5'-PO4 RNA ends with the 3'-hydroxyl group of a 5' adaptor (5'-PO4 Bru-Seq) using RNA ligase I. These ligation events are localized at single nucleotide resolution via highthroughput sequencing, which identifies the position of 5'-PO4 groups precisely. This protocol successfully detects the 5'monophosphorylated ends of RNA processing intermediates during production of mature ribosomal, transfer, and micro RNAs. When combined with inhibition of the nuclear 5'-3' exonuclease Xrn2, 5'-PO4 Bru-Seq maps the 5' splice sites of debranched introns and mRNA and tRNA 3' end processing sites cleaved by CPSF73 and RNaseZ, respectively. Key features • Metabolic labeling for brief periods with bromouridine focuses the analysis of 5'-PO4 RNA ends on the population of nascent transcripts that are actively transcribed. • Detects 5'-PO4 RNA ends on nascent transcripts produced by all RNA polymerases. • Detects 5'-PO4 RNA ends at single nucleotide resolution.
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Affiliation(s)
- Michael A. Cortázar
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, USA
| | - Nova Fong
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, USA
| | - David L. Bentley
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, USA
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4
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Gonzales S, Zhao JZ, Choi NY, Acharya P, Jeong S, Lee MY. SOX7: Novel Autistic Gene Identified by Analysis of Multi-Omics Data. RESEARCH SQUARE 2023:rs.3.rs-3346245. [PMID: 37790478 PMCID: PMC10543249 DOI: 10.21203/rs.3.rs-3346245/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Background Despite thousands of variants identified by genome-wide association studies (GWAS) to be associated with autism spectrum disorder (ASD), it is unclear which mutations are causal because most are noncoding. Consequently, reliable diagnostic biomarkers are lacking. RNA-seq analysis captures biomolecular complexity that GWAS cannot by considering transcriptomic patterns. Therefore, integrating DNA and RNA testing may reveal causal genes and useful biomarkers for ASD. Methods We performed gene-based association studies using an adaptive test method with GWAS summary statistics from two large Psychiatric Genomics Consortium (PGC) datasets (ASD2019: 18,382 cases and 27,969 controls; ASD2017: 6,197 cases and 7,377 controls). We also investigated differential expression for genes identified with the adaptive test using an RNA-seq dataset (GSE30573: 3 cases and 3 controls) and DESeq2. Results We identified 5 genes significantly associated with ASD in ASD2019 (KIZ-AS1, p = 8.67×10- 10; KIZ, p = 1.16×10- 9; XRN2, p = 7.73×10- 9; SOX7, p = 2.22×10- 7; LOC101929229 (also known as PINX1-DT), p = 2.14×10- 6). Two of the five genes were replicated in ASD2017: SOX7 (p = 0.00087) and LOC101929229 (p = 0.009), and KIZ was close to the replication boundary of replication (p = 0.06). We identified significant expression differences for SOX7 (p = 0.0017, adjusted p = 0.0085), LOC101929229 (p = 5.83×10- 7, adjusted p = 1.18×10- 5), and KIZ (p = 0.00099, adjusted p = 0.0055). SOX7 encodes a transcription factor that regulates developmental pathways, alterations in which may contribute to ASD. Limitations The limitation of the gene-based analysis is the reliance on a reference population for estimating linkage disequilibrium between variants. The similarity of this reference population to the population of study is crucial to the accuracy of many gene-based analyses, including those performed in this study. As a result, the extent of our findings is limited to European populations, as this was our reference of choice. Future work includes a tighter integration of DNA and RNA information as well as extensions to non-European populations that have been under-researched. Conclusions These findings suggest that SOX7 and its related SOX family genes encode transcription factors that are critical to the downregulation of the canonical Wnt/β-catenin signaling pathway, an important developmental signaling pathway, providing credence to the biologic plausibility of the association between gene SOX7 and autism spectrum disorder.
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Affiliation(s)
| | - Jane Zizhen Zhao
- Miami Dade College Kendall Campus and School for Advanced Studies
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Gonzales S, Zhao JZ, Choi NY, Acharya P, Jeong S, Lee MY. SOX7: Novel Autistic Gene Identified by Analysis of Multi-Omics Data. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.26.542456. [PMID: 37292933 PMCID: PMC10245991 DOI: 10.1101/2023.05.26.542456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Background Genome-wide association studies and next generation sequencing data analyses based on DNA information have identified thousands of mutations associated with autism spectrum disorder (ASD). However, more than 99% of identified mutations are non-coding. Thus, it is unclear which of these mutations might be functional and thus potentially causal variants. Transcriptomic profiling using total RNA-sequencing has been one of the most utilized approaches to link protein levels to genetic information at the molecular level. The transcriptome captures molecular genomic complexity that the DNA sequence solely does not. Some mutations alter a gene's DNA sequence but do not necessarily change expression and/or protein function. To date, few common variants reliably associated with the diagnosis status of ASD despite consistently high estimates of heritability. In addition, reliable biomarkers used to diagnose ASD or molecular mechanisms to define the severity of ASD do not exist. Objectives It is necessary to integrate DNA and RNA testing together to identify true causal genes and propose useful biomarkers for ASD. Methods We performed gene-based association studies with adaptive test using genome-wide association studies (GWAS) summary statistics with two large GWAS datasets (ASD 2019 data: 18,382 ASD cases and 27,969 controls [discovery data]; ASD 2017 data: 6,197 ASD cases and 7,377 controls [replication data]) which were obtained from the Psychiatric Genomics Consortium (PGC). In addition, we investigated differential expression for genes identified in gene-based GWAS with a RNA-seq dataset (GSE30573: 3 cases and 3 controls) using the DESeq2 package. Results We identified 5 genes significantly associated with ASD in ASD 2019 data (KIZ-AS1, p=8.67×10-10; KIZ, p=1.16×10-9; XRN2, p=7.73×10-9; SOX7, p=2.22×10-7; PINX1-DT, p=2.14×10-6). Among these 5 genes, gene SOX7 (p=0.00087), LOC101929229 (p=0.009), and KIZ-AS1 (p=0.059) were replicated in ASD 2017 data. KIZ (p=0.06) was close to the boundary of replication in ASD 2017 data. Genes SOX7 (p=0.0017, adjusted p=0.0085), LOC101929229 (also known as PINX1-DT, p=5.83×10-7, adjusted p=1.18×10-5), and KIZ (p=0.00099, adjusted p=0.0055) indicated significant expression differences between cases and controls in the RNA-seq data. SOX7 encodes a member of the SOX (SRY-related HMG-box) family of transcription factors pivotally contributing to determining of the cell fate and identity in many lineages. The encoded protein may act as a transcriptional regulator after forming a protein complex with other proteins leading to autism. Conclusion Gene SOX7 in the transcription factor family could be associated with ASD. This finding may provide new diagnostic and therapeutic strategies for ASD.
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Affiliation(s)
- Samantha Gonzales
- Department of Biostatistics, Florida International University, Miami, FL 33199
| | - Jane Zizhen Zhao
- Miami Dade College Kendall Campus and School for Advanced Studies, Miami, FL 33176
| | - Na Young Choi
- Department of Biomedical Engineering, University of North Texas, Denton, TX 76207
| | - Prabha Acharya
- Department of Biomedical Engineering, University of North Texas, Denton, TX 76207
| | - Sehoon Jeong
- Department of Healthcare Information Technology Inje University, Gimhae, South Korea, 50834
| | - Moo-Yeal Lee
- Department of Biomedical Engineering, University of North Texas, Denton, TX 76207
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6
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Aygün I, Rzepczak A, Miki TS. A germline-targeted genetic screen for xrn-2 suppressors identifies a novel gene C34C12.2 in Caenorhabditis elegans. Genet Mol Biol 2023; 46:e20220328. [PMID: 37216322 DOI: 10.1590/1678-4685-gmb-2022-0328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/22/2023] [Indexed: 05/24/2023] Open
Abstract
XRN2 is an evolutionarily conserved 5'-to-3' exoribonuclease, which degrades or trims various types of RNA in the nucleus. Although XRN-2 is essential for embryogenesis, larval development and reproduction in Caenorhabditis elegans, relevant molecular pathways remain unidentified. Here we create a germline-specific xrn-2 conditional mutant and perform a mutagenesis screen for suppressors of sterility. Loss-of-function alleles of dpy-10, osr-1, ptr-6 and C34C12.2 genes are identified. Depletion of DPY-10, OSR-1 or PTR-6 increases expression of gpdh-1 that encodes a glycerol-3-phosphate dehydrogenase, thereby elevates glycerol accumulation to suppress sterility of the mutant. The C34C12.2 protein is predominantly localized in the nucleolus of germ cells and shows a similarity to Saccharomyces cerevisiae Net1, which is involved in rDNA silencing. Depletion of NRDE-2, a putative interacting partner of C34C12.2 and a component of the nuclear RNAi machinery, restores fertility to the xrn-2 conditional mutant. These results may help to identify an essential role of XRN-2 in germline development.
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Affiliation(s)
- Ilkin Aygün
- Polish Academy of Sciences, Institute of Bioorganic Chemistry, Department of Developmental Biology, Poznań, Poland
| | - Alicja Rzepczak
- Polish Academy of Sciences, Institute of Bioorganic Chemistry, Department of Developmental Biology, Poznań, Poland
| | - Takashi S Miki
- Polish Academy of Sciences, Institute of Bioorganic Chemistry, Department of Developmental Biology, Poznań, Poland
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7
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Casado P, Rio-Machin A, Miettinen JJ, Bewicke-Copley F, Rouault-Pierre K, Krizsan S, Parsons A, Rajeeve V, Miraki-Moud F, Taussig DC, Bödör C, Gribben J, Heckman C, Fitzgibbon J, Cutillas PR. Integrative phosphoproteomics defines two biologically distinct groups of KMT2A rearranged acute myeloid leukaemia with different drug response phenotypes. Signal Transduct Target Ther 2023; 8:80. [PMID: 36843114 PMCID: PMC9968719 DOI: 10.1038/s41392-022-01288-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 11/18/2022] [Accepted: 12/03/2022] [Indexed: 02/28/2023] Open
Abstract
Acute myeloid leukaemia (AML) patients harbouring certain chromosome abnormalities have particularly adverse prognosis. For these patients, targeted therapies have not yet made a significant clinical impact. To understand the molecular landscape of poor prognosis AML we profiled 74 patients from two different centres (in UK and Finland) at the proteomic, phosphoproteomic and drug response phenotypic levels. These data were complemented with transcriptomics analysis for 39 cases. Data integration highlighted a phosphoproteomics signature that define two biologically distinct groups of KMT2A rearranged leukaemia, which we term MLLGA and MLLGB. MLLGA presented increased DOT1L phosphorylation, HOXA gene expression, CDK1 activity and phosphorylation of proteins involved in RNA metabolism, replication and DNA damage when compared to MLLGB and no KMT2A rearranged samples. MLLGA was particularly sensitive to 15 compounds including genotoxic drugs and inhibitors of mitotic kinases and inosine-5-monosphosphate dehydrogenase (IMPDH) relative to other cases. Intermediate-risk KMT2A-MLLT3 cases were mainly represented in a third group closer to MLLGA than to MLLGB. The expression of IMPDH2 and multiple nucleolar proteins was higher in MLLGA and correlated with the response to IMPDH inhibition in KMT2A rearranged leukaemia, suggesting a role of the nucleolar activity in sensitivity to treatment. In summary, our multilayer molecular profiling of AML with poor prognosis and KMT2A-MLLT3 karyotypes identified a phosphoproteomics signature that defines two biologically and phenotypically distinct groups of KMT2A rearranged leukaemia. These data provide a rationale for the potential development of specific therapies for AML patients characterised by the MLLGA phosphoproteomics signature identified in this study.
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Affiliation(s)
- Pedro Casado
- Cell Signalling and Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Ana Rio-Machin
- Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Juho J Miettinen
- Institute for Molecular Medicine Finland - FIMM, HiLIFE - Helsinki Institute of Life Science, iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Findlay Bewicke-Copley
- Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Kevin Rouault-Pierre
- Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Szilvia Krizsan
- HCEMM-SU Molecular Oncohematology Research Group, 1st Department of Pathology and Experimental Cancer Research, Semmelweis University Budapest, Budapest, Hungary
| | - Alun Parsons
- Institute for Molecular Medicine Finland - FIMM, HiLIFE - Helsinki Institute of Life Science, iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Vinothini Rajeeve
- Cell Signalling and Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Farideh Miraki-Moud
- Cancer Research UK Cancer Therapeutics Unit, Division of Cancer Therapeutics, The Institute of Cancer Research, Sutton, UK
| | - David C Taussig
- Cancer Research UK Cancer Therapeutics Unit, Division of Cancer Therapeutics, The Institute of Cancer Research, Sutton, UK
| | - Csaba Bödör
- HCEMM-SU Molecular Oncohematology Research Group, 1st Department of Pathology and Experimental Cancer Research, Semmelweis University Budapest, Budapest, Hungary
| | - John Gribben
- Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Caroline Heckman
- Institute for Molecular Medicine Finland - FIMM, HiLIFE - Helsinki Institute of Life Science, iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Jude Fitzgibbon
- Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK
| | - Pedro R Cutillas
- Cell Signalling and Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, EC1M6BQ, UK.
- The Alan Turing Institute, The British Library, 2QR, 96 Euston Rd, London, NW1 2DB, UK.
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Cortazar MA, Erickson B, Fong N, Pradhan SJ, Ntini E, Bentley DL. Xrn2 substrate mapping identifies torpedo loading sites and extensive premature termination of RNA pol II transcription. Genes Dev 2022; 36:1062-1078. [PMID: 36396340 PMCID: PMC9744234 DOI: 10.1101/gad.350004.122] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/31/2022] [Indexed: 11/19/2022]
Abstract
The exonuclease torpedo Xrn2 loads onto nascent RNA 5'-PO4 ends and chases down pol II to promote termination downstream from polyA sites. We report that Xrn2 is recruited to preinitiation complexes and "travels" to 3' ends of genes. Mapping of 5'-PO4 ends in nascent RNA identified Xrn2 loading sites stabilized by an active site mutant, Xrn2(D235A). Xrn2 loading sites are approximately two to 20 bases downstream from where CPSF73 cleaves at polyA sites and histone 3' ends. We propose that processing of all mRNA 3' ends comprises cleavage and limited 5'-3' trimming by CPSF73, followed by handoff to Xrn2. A similar handoff occurs at tRNA 3' ends, where cotranscriptional RNase Z cleavage generates novel Xrn2 substrates. Exonuclease-dead Xrn2 increased transcription in 3' flanking regions by inhibiting polyA site-dependent termination. Surprisingly, the mutant Xrn2 also rescued transcription in promoter-proximal regions to the same extent as in 3' flanking regions. eNET-seq revealed Xrn2-mediated degradation of sense and antisense nascent RNA within a few bases of the TSS, where 5'-PO4 ends may be generated by decapping or endonucleolytic cleavage. These results suggest that a major fraction of pol II complexes terminates prematurely close to the start site under normal conditions by an Xrn2-mediated torpedo mechanism.
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Affiliation(s)
- Michael A. Cortazar
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Benjamin Erickson
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Nova Fong
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Sarala J. Pradhan
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Evgenia Ntini
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology–Hellas (FORTH), Heraklion GR-70013, Greece
| | - David L. Bentley
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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9
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Observation of conformational changes that underlie the catalytic cycle of Xrn2. Nat Chem Biol 2022; 18:1152-1160. [PMID: 36008487 PMCID: PMC9512700 DOI: 10.1038/s41589-022-01111-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/07/2022] [Indexed: 12/19/2022]
Abstract
Nuclear magnetic resonance (NMR) methods that quantitatively probe motions on molecular and atomic levels have propelled the understanding of biomolecular processes for which static structures cannot provide a satisfactory description. In this work, we studied the structure and dynamics of the essential 100-kDa eukaryotic 5′→3′ exoribonuclease Xrn2. A combination of complementary fluorine and methyl-TROSY NMR spectroscopy reveals that the apo enzyme is highly dynamic around the catalytic center. These observed dynamics are in agreement with a transition of the enzyme from the ground state into a catalytically competent state. We show that the conformational equilibrium in Xrn2 shifts substantially toward the active state in the presence of substrate and magnesium. Finally, our data reveal that the dynamics in Xrn2 correlate with the RNA degradation rate, as a mutation that attenuates motions also affects catalytic activity. In that light, our results stress the importance of studies that go beyond static structural information. ![]()
Using methyl group and fluorine NMR spectroscopic methods, Overbeck et al revealed that the dynamics of the eukaryotic 5′→3′ exoribonuclease Xrn2 in the region around the active site are correlated with its catalytic activity.
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10
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Bohnsack KE, Kanwal N, Bohnsack MT. Prp43/DHX15 exemplify RNA helicase multifunctionality in the gene expression network. Nucleic Acids Res 2022; 50:9012-9022. [PMID: 35993807 PMCID: PMC9458436 DOI: 10.1093/nar/gkac687] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/10/2022] [Accepted: 08/01/2022] [Indexed: 12/24/2022] Open
Abstract
Dynamic regulation of RNA folding and structure is critical for the biogenesis and function of RNAs and ribonucleoprotein (RNP) complexes. Through their nucleotide triphosphate-dependent remodelling functions, RNA helicases are key modulators of RNA/RNP structure. While some RNA helicases are dedicated to a specific target RNA, others are multifunctional and engage numerous substrate RNAs in different aspects of RNA metabolism. The discovery of such multitasking RNA helicases raises the intriguing question of how these enzymes can act on diverse RNAs but also maintain specificity for their particular targets within the RNA-dense cellular environment. Furthermore, the identification of RNA helicases that sit at the nexus between different aspects of RNA metabolism raises the possibility that they mediate cross-regulation of different cellular processes. Prominent and extensively characterized multifunctional DEAH/RHA-box RNA helicases are DHX15 and its Saccharomyces cerevisiae (yeast) homologue Prp43. Due to their central roles in key cellular processes, these enzymes have also served as prototypes for mechanistic studies elucidating the mode of action of this type of enzyme. Here, we summarize the current knowledge on the structure, regulation and cellular functions of Prp43/DHX15, and discuss the general concept and implications of RNA helicase multifunctionality.
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Affiliation(s)
- Katherine E Bohnsack
- Correspondence may also be addressed to Katherine E. Bohnsack. Tel: +49 551 3969305; Fax: +49 551 395960;
| | - Nidhi Kanwal
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Markus T Bohnsack
- To whom correspondence should be addressed. Tel: +49 551 395968; Fax: +49 551 395960;
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11
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TAUPELET F, DONNIO LM, MAGNANI C, MARI PO, GIGLIA-MARI G. A stable XPG protein is required for proper ribosome biogenesis: Insights on the phenotype of combinate Xeroderma Pigmentosum/Cockayne Syndrome patients. PLoS One 2022; 17:e0271246. [PMID: 35802638 PMCID: PMC9269744 DOI: 10.1371/journal.pone.0271246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/24/2022] [Indexed: 11/18/2022] Open
Abstract
Nucleotide Excision Repair is one of the five DNA repair systems. More than 30 proteins are involved in this process, including the seven XP proteins. When mutated, the genes coding for these proteins are provoking the rare disease Xeroderma Pigmentosum, which causes cutaneous defects and a high prevalence of skin cancers in patients. The CSA and CSB proteins are also involved in Nucleotide Excision Repair, and their mutation leads to Cockayne Syndrome, another rare disease, causing dwarfism, neurodegeneration, and ultimately early death, but without high skin cancer incidence. Some mutations of ERCC5, the gene coding for XPG, may give rise to a combined Xeroderma Pigmentosum and Cockayne Syndrome. A defect in Nucleotide Excision Repair alone cannot explain all these phenotypes. XPG has been located in the nucleolus, where ribosome biogenesis happens. This energy-consuming process starts with the transcription of the ribosomal DNA in a long ribosomal RNA, the pre-rRNA 47S, by RNA Polymerase 1. 47S pre-rRNA undergoes several cleavages and modifications to form three mature products: the ribosomal RNAs 18S, 5.8S and 28S. In the cytoplasm, these three products will enter the ribosomes’ composition, the producers of protein in our cells. Our work aimed to observe ribosome biogenesis in presence of an unstable XPG protein. By working on Xeroderma Pigmentosum/Cockayne Syndrome cell lines, meaning in the absence of XPG, we uncovered that the binding of UBF, as well as the number of unresolved R-loops, is increased along the ribosomal DNA gene body and flanking regions. Furthermore, ribosomal RNA maturation is impaired, with increased use of alternative pathways of maturation as well as an increase of immature precursors. These defective processes may explain the neurodegeneration observed when the XPG protein is heavily truncated, as ribosomal homeostasis and R-loops resolution are critical for proper neuronal development.
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Affiliation(s)
- Florent TAUPELET
- Institut NeuroMyoGène–Physiopathologie et Génétique du Neurone et du Muscle, CNRS UMR 5261, INSERM U1315, Faculté de Médecine et de Pharmacie Rockefeller, Université Claude Bernard Lyon 1, Lyon, France
| | - Lise-Marie DONNIO
- Institut NeuroMyoGène–Physiopathologie et Génétique du Neurone et du Muscle, CNRS UMR 5261, INSERM U1315, Faculté de Médecine et de Pharmacie Rockefeller, Université Claude Bernard Lyon 1, Lyon, France
| | - Charlène MAGNANI
- Institut NeuroMyoGène–Physiopathologie et Génétique du Neurone et du Muscle, CNRS UMR 5261, INSERM U1315, Faculté de Médecine et de Pharmacie Rockefeller, Université Claude Bernard Lyon 1, Lyon, France
| | - Pierre-Olivier MARI
- Institut NeuroMyoGène–Physiopathologie et Génétique du Neurone et du Muscle, CNRS UMR 5261, INSERM U1315, Faculté de Médecine et de Pharmacie Rockefeller, Université Claude Bernard Lyon 1, Lyon, France
| | - Giuseppina GIGLIA-MARI
- Institut NeuroMyoGène–Physiopathologie et Génétique du Neurone et du Muscle, CNRS UMR 5261, INSERM U1315, Faculté de Médecine et de Pharmacie Rockefeller, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail:
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Transcriptomic analysis of ribosome biogenesis and pre-rRNA processing during growth stress in Entamoeba histolytica. Exp Parasitol 2022; 239:108308. [PMID: 35718007 DOI: 10.1016/j.exppara.2022.108308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 05/27/2022] [Accepted: 06/14/2022] [Indexed: 11/24/2022]
Abstract
Ribosome biogenesis, a multi-step process involving transcription, modification, folding and processing of rRNA, is the major consumer of cellular energy. It involves sequential assembly of ribosomal proteins (RP)s via more than 200 ribogenesis factors. Unlike model organisms where transcription of rRNA and RP genes slows down during stress, in Entamoeba histolytica, pre-rRNA synthesis continues, and unprocessed pre-rRNA accumulates. Northern hybridization from different spacer regions depicted the accumulation of unprocessed intermediates during stress. To gain insight into the vast repertoire of ribosome biogenesis factors and understand the major components playing role during stress we computationally identified ribosome biogenesis factors in E. histolytica. Of the ∼279 Saccharomyces cerevisiae proteins, we could only find 188 proteins in E. histolytica. Some of the proteins missing in E. histolytica were also missing in humans. A number of proteins represented by multiple genes in S. cerevisiae had a single copy in E. histolytica. Interestingly E. histolytica lacked mitochondrial ribosome biogenesis factors and had far less RNase components compared to S. cerevisiae. Transcriptomic studies revealed the differential regulation of ribosomal factors both in serum starved and RRP6 down-regulation conditions. These included the NEP1 and TSR3 proteins that chemically modify 18S-rRNA. Pre-rRNA precursors accumulate upon downregulation of the latter proteins in S. cerevisiae and humans. These data reveal the major factors that regulate pre-rRNA processing during stress in E. histolytica and provide the first complete repertoire of ribosome biogenesis factors in this early-branching protist.
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9-Aminoacridine Inhibits Ribosome Biogenesis by Targeting Both Transcription and Processing of Ribosomal RNA. Int J Mol Sci 2022; 23:ijms23031260. [PMID: 35163183 PMCID: PMC8836032 DOI: 10.3390/ijms23031260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 12/13/2022] Open
Abstract
Aminoacridines, used for decades as antiseptic and antiparasitic agents, are prospective candidates for therapeutic repurposing and new drug development. Although the mechanisms behind their biological effects are not fully elucidated, they are most often attributed to the acridines’ ability to intercalate into DNA. Here, we characterized the effects of 9-aminoacridine (9AA) on pre-rRNA metabolism in cultured mammalian cells. Our results demonstrate that 9AA inhibits both transcription of the ribosomal RNA precursors (pre-rRNA) and processing of the already synthesized pre-rRNAs, thereby rapidly abolishing ribosome biogenesis. Using a fluorescent intercalator displacement assay, we further show that 9AA can bind to RNA in vitro, which likely contributes to its ability to inhibit post-transcriptional steps in pre-rRNA maturation. These findings extend the arsenal of small-molecule compounds that can be used to block ribosome biogenesis in mammalian cells and have implications for the pharmacological development of new ribosome biogenesis inhibitors.
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Moraleva AA, Deryabin AS, Rubtsov YP, Rubtsova MP, Dontsova OA. Eukaryotic Ribosome Biogenesis: The 40S Subunit. Acta Naturae 2022; 14:14-30. [PMID: 35441050 PMCID: PMC9013438 DOI: 10.32607/actanaturae.11540] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 02/02/2022] [Indexed: 11/29/2022] Open
Abstract
The formation of eukaryotic ribosomes is a sequential process of ribosomal
precursors maturation in the nucleolus, nucleoplasm, and cytoplasm. Hundreds of
ribosomal biogenesis factors ensure the accurate processing and formation of
the ribosomal RNAs’ tertiary structure, and they interact with ribosomal
proteins. Most of what we know about the ribosome assembly has been derived
from yeast cell studies, and the mechanisms of ribosome biogenesis in
eukaryotes are considered quite conservative. Although the main stages of
ribosome biogenesis are similar across different groups of eukaryotes, this
process in humans is much more complicated owing to the larger size of the
ribosomes and pre-ribosomes and the emergence of regulatory pathways that
affect their assembly and function. Many of the factors involved in the
biogenesis of human ribosomes have been identified using genome-wide screening
based on RNA interference. This review addresses the key aspects of yeast and
human ribosome biogenesis, using the 40S subunit as an example. The mechanisms
underlying these differences are still not well understood, because, unlike
yeast, there are no effective methods for characterizing pre-ribosomal
complexes in humans. Understanding the mechanisms of human ribosome assembly
would have an incidence on a growing number of genetic diseases
(ribosomopathies) caused by mutations in the genes encoding ribosomal proteins
and ribosome biogenesis factors. In addition, there is evidence that ribosome
assembly is regulated by oncogenic signaling pathways, and that defects in the
ribosome biogenesis are linked to the activation of tumor suppressors.
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Affiliation(s)
- A. A. Moraleva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - A. S. Deryabin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - Yu. P. Rubtsov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - M. P. Rubtsova
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991 Russia
| | - O. A. Dontsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991 Russia
- Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
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15
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Venturi G, Zacchini F, Vaccari CL, Trerè D, Montanaro L. Primer extension coupled with fragment analysis for rapid and quantitative evaluation of 5.8S rRNA isoforms. PLoS One 2021; 16:e0261476. [PMID: 34932578 PMCID: PMC8691633 DOI: 10.1371/journal.pone.0261476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/02/2021] [Indexed: 11/30/2022] Open
Abstract
The ribosomal RNA 5.8S is one of the four rRNAs that constitute ribosomes. In human cells, like in all eukaryotes, it derives from the extensive processing of a long precursor containing the sequence of 18S, 5.8S and 28S rRNAs. It has been confirmed also in human cells the presence of three isoforms of 5.8S rRNA: one more abundant called 5.8S short, one called 5.8S long bearing 5 extra-nucleotides at its 5’ end and one 10 nucleotide shorter called 5.8S cropped. So far, little is known about 5.8S long specific role in cell biology and its function in human pathology. The lack of studies on the three 5.8S isoforms could be due to the techniques usually applied to study ribosome biogenesis, such as Northern blot with radioactively labelled probes, that require strict protective measures, and abundant and high-quality samples. To overcome this issue, we optimized a method that combines primer extension with a fluorescently labeled reverse primer designed on the 3’ of 5.8S rRNA sequence and fragment analysis. The resulting electropherogram shows the peaks corresponding to the three isoforms of 5.8S rRNA. The estimation of the area underneath the peaks allows to directly quantify the isoforms and to express their relative abundance. The relative abundance of 5.8S long and 5.8S short remains constant using scalar dilution of RNA and in samples subjected to partial degradation. 5.8S cropped abundance varies significantly in lower concentrate RNA samples. This method allows to analyze rapidly and safely the abundance of 5.8S rRNA isoforms in samples that have been so far considered not suitable such as poorly concentrated samples, RNA derived from frozen tissue or unique samples.
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Affiliation(s)
- Giulia Venturi
- Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES), Alma Mater Studiorum—Università di Bologna, Bologna, Italia
- Centro di Ricerca Biomedica Applicata–CRBA, Università̀ di Bologna, Policlinico di Sant’Orsola, Bologna, Italia
| | - Federico Zacchini
- Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES), Alma Mater Studiorum—Università di Bologna, Bologna, Italia
- Centro di Ricerca Biomedica Applicata–CRBA, Università̀ di Bologna, Policlinico di Sant’Orsola, Bologna, Italia
| | - Cinzia Lucia Vaccari
- Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES), Alma Mater Studiorum—Università di Bologna, Bologna, Italia
- Centro di Ricerca Biomedica Applicata–CRBA, Università̀ di Bologna, Policlinico di Sant’Orsola, Bologna, Italia
| | - Davide Trerè
- Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES), Alma Mater Studiorum—Università di Bologna, Bologna, Italia
- Programma Dipartimentale di Medicina di Laboratorio, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italia
| | - Lorenzo Montanaro
- Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES), Alma Mater Studiorum—Università di Bologna, Bologna, Italia
- Centro di Ricerca Biomedica Applicata–CRBA, Università̀ di Bologna, Policlinico di Sant’Orsola, Bologna, Italia
- Programma Dipartimentale di Medicina di Laboratorio, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italia
- * E-mail:
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Hojka-Osinska A, Chlebowski A, Grochowska J, Owczarek EP, Affek K, Kłosowska-Kosicka K, Szczesny RJ, Dziembowski A. Landscape of functional interactions of human processive ribonucleases revealed by high-throughput siRNA screenings. iScience 2021; 24:103036. [PMID: 34541468 PMCID: PMC8437785 DOI: 10.1016/j.isci.2021.103036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 06/09/2021] [Accepted: 08/23/2021] [Indexed: 11/24/2022] Open
Abstract
Processive exoribonucleases are executors of RNA decay. In humans, their physical but not functional interactions were thoughtfully investigated. Here we have screened cells deficient in DIS3, XRN2, EXOSC10, DIS3L, and DIS3L2 with a custom siRNA library and determined their genetic interactions (GIs) with diverse pathways of RNA metabolism. We uncovered a complex network of positive interactions that buffer alterations in RNA degradation and reveal reciprocal cooperation with genes involved in transcription, RNA export, and splicing. Further, we evaluated the functional distinctness of nuclear DIS3 and cytoplasmic DIS3L using a library of all known genes associated with RNA metabolism. Our analysis revealed that DIS3 mutation suppresses RNA splicing deficiency, while DIS3L GIs disclose the interplay of cytoplasmic RNA degradation with nuclear RNA processing. Finally, genome-wide DIS3 GI map uncovered relations with genes not directly involved in RNA metabolism, like microtubule organization or regulation of telomerase activity.
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Affiliation(s)
- Anna Hojka-Osinska
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Aleksander Chlebowski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Joanna Grochowska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Ewelina P. Owczarek
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Kamila Affek
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | | | - Roman J. Szczesny
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Andrzej Dziembowski
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
- Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland
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Loss of SNORA73 reprograms cellular metabolism and protects against steatohepatitis. Nat Commun 2021; 12:5214. [PMID: 34471131 PMCID: PMC8410784 DOI: 10.1038/s41467-021-25457-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 08/06/2021] [Indexed: 02/07/2023] Open
Abstract
Dyslipidemia and resulting lipotoxicity are pathologic signatures of metabolic syndrome and type 2 diabetes. Excess lipid causes cell dysfunction and induces cell death through pleiotropic mechanisms that link to oxidative stress. However, pathways that regulate the response to metabolic stress are not well understood. Herein, we show that disruption of the box H/ACA SNORA73 small nucleolar RNAs encoded within the small nucleolar RNA hosting gene 3 (Snhg3) causes resistance to lipid-induced cell death and general oxidative stress in cultured cells. This protection from metabolic stress is associated with broad reprogramming of oxidative metabolism that is dependent on the mammalian target of rapamycin signaling axis. Furthermore, we show that knockdown of SNORA73 in vivo protects against hepatic steatosis and lipid-induced oxidative stress and inflammation. Our findings demonstrate a role for SNORA73 in the regulation of metabolism and lipotoxicity.
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18
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MicroRNAs and long non-coding RNAs as novel regulators of ribosome biogenesis. Biochem Soc Trans 2021; 48:595-612. [PMID: 32267487 PMCID: PMC7200637 DOI: 10.1042/bst20190854] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/12/2020] [Accepted: 03/16/2020] [Indexed: 12/14/2022]
Abstract
Ribosome biogenesis is the fine-tuned, essential process that generates mature ribosomal subunits and ultimately enables all protein synthesis within a cell. Novel regulators of ribosome biogenesis continue to be discovered in higher eukaryotes. While many known regulatory factors are proteins or small nucleolar ribonucleoproteins, microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) are emerging as a novel modulatory layer controlling ribosome production. Here, we summarize work uncovering non-coding RNAs (ncRNAs) as novel regulators of ribosome biogenesis and highlight their links to diseases of defective ribosome biogenesis. It is still unclear how many miRNAs or lncRNAs are involved in phenotypic or pathological disease outcomes caused by impaired ribosome production, as in the ribosomopathies, or by increased ribosome production, as in cancer. In time, we hypothesize that many more ncRNA regulators of ribosome biogenesis will be discovered, which will be followed by an effort to establish connections between disease pathologies and the molecular mechanisms of this additional layer of ribosome biogenesis control.
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19
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Kaliatsi EG, Giarimoglou N, Stathopoulos C, Stamatopoulou V. Non-Coding RNA-Driven Regulation of rRNA Biogenesis. Int J Mol Sci 2020; 21:E9738. [PMID: 33419375 PMCID: PMC7766524 DOI: 10.3390/ijms21249738] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/30/2022] Open
Abstract
Ribosomal RNA (rRNA) biogenesis takes place in the nucleolus, the most prominent condensate of the eukaryotic nucleus. The proper assembly and integrity of the nucleolus reflects the accurate synthesis and processing of rRNAs which in turn, as major components of ribosomes, ensure the uninterrupted flow of the genetic information during translation. Therefore, the abundant production of rRNAs in a precisely functional nucleolus is of outmost importance for the cell viability and requires the concerted action of essential enzymes, associated factors and epigenetic marks. The coordination and regulation of such an elaborate process depends on not only protein factors, but also on numerous regulatory non-coding RNAs (ncRNAs). Herein, we focus on RNA-mediated mechanisms that control the synthesis, processing and modification of rRNAs in mammals. We highlight the significance of regulatory ncRNAs in rRNA biogenesis and the maintenance of the nucleolar morphology, as well as their role in human diseases and as novel druggable molecular targets.
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Affiliation(s)
| | | | - Constantinos Stathopoulos
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece; (E.G.K.); (N.G.)
| | - Vassiliki Stamatopoulou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece; (E.G.K.); (N.G.)
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20
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XRN2 interactome reveals its synthetic lethal relationship with PARP1 inhibition. Sci Rep 2020; 10:14253. [PMID: 32859985 PMCID: PMC7455564 DOI: 10.1038/s41598-020-71203-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 08/11/2020] [Indexed: 12/17/2022] Open
Abstract
Persistent R-loops (RNA-DNA hybrids with a displaced single-stranded DNA) create DNA damage and lead to genomic instability. The 5'-3'-exoribonuclease 2 (XRN2) degrades RNA to resolve R-loops and promotes transcription termination. Previously, XRN2 was implicated in DNA double strand break (DSB) repair and in resolving replication stress. Here, using tandem affinity purification-mass spectrometry, bioinformatics, and biochemical approaches, we found that XRN2 associates with proteins involved in DNA repair/replication (Ku70-Ku80, DNA-PKcs, PARP1, MCM2-7, PCNA, RPA1) and RNA metabolism (RNA helicases, PRP19, p54(nrb), splicing factors). Novel major pathways linked to XRN2 include cell cycle control of chromosomal replication and DSB repair by non-homologous end joining. Investigating the biological implications of these interactions led us to discover that XRN2 depletion compromised cell survival after additional knockdown of specific DNA repair proteins, including PARP1. XRN2-deficient cells also showed enhanced PARP1 activity. Consistent with concurrent depletion of XRN2 and PARP1 promoting cell death, XRN2-deficient fibroblast and lung cancer cells also demonstrated sensitivity to PARP1 inhibition. XRN2 alterations (mutations, copy number/expression changes) are frequent in cancers. Thus, PARP1 inhibition could target cancers exhibiting XRN2 functional loss. Collectively, our data suggest XRN2's association with novel protein partners and unravel synthetic lethality between XRN2 depletion and PARP1 inhibition.
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21
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22
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Shao Z, Flynn RA, Crowe JL, Zhu Y, Liang J, Jiang W, Aryan F, Aoude P, Bertozzi CR, Estes VM, Lee BJ, Bhagat G, Zha S, Calo E. DNA-PKcs has KU-dependent function in rRNA processing and haematopoiesis. Nature 2020; 579:291-296. [PMID: 32103174 PMCID: PMC10919329 DOI: 10.1038/s41586-020-2041-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 01/28/2020] [Indexed: 11/09/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK), which comprises the KU heterodimer and a catalytic subunit (DNA-PKcs), is a classical non-homologous end-joining (cNHEJ) factor1. KU binds to DNA ends, initiates cNHEJ, and recruits and activates DNA-PKcs. KU also binds to RNA, but the relevance of this interaction in mammals is unclear. Here we use mouse models to show that DNA-PK has an unexpected role in the biogenesis of ribosomal RNA (rRNA) and in haematopoiesis. The expression of kinase-dead DNA-PKcs abrogates cNHEJ2. However, most mice that both expressed kinase-dead DNA-PKcs and lacked the tumour suppressor TP53 developed myeloid disease, whereas all other previously characterized mice deficient in both cNHEJ and TP53 expression succumbed to pro-B cell lymphoma3. DNA-PK autophosphorylates DNA-PKcs, which is its best characterized substrate. Blocking the phosphorylation of DNA-PKcs at the T2609 cluster, but not the S2056 cluster, led to KU-dependent defects in 18S rRNA processing, compromised global protein synthesis in haematopoietic cells and caused bone marrow failure in mice. KU drives the assembly of DNA-PKcs on a wide range of cellular RNAs, including the U3 small nucleolar RNA, which is essential for processing of 18S rRNA4. U3 activates purified DNA-PK and triggers phosphorylation of DNA-PKcs at T2609. DNA-PK, but not other cNHEJ factors, resides in nucleoli in an rRNA-dependent manner and is co-purified with the small subunit processome. Together our data show that DNA-PK has RNA-dependent, cNHEJ-independent functions during ribosome biogenesis that require the kinase activity of DNA-PKcs and its phosphorylation at the T2609 cluster.
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Affiliation(s)
- Zhengping Shao
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Ryan A Flynn
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Jennifer L Crowe
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Graduate Program of Pathobiology and Molecular Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yimeng Zhu
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Jialiang Liang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Wenxia Jiang
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Fardin Aryan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Patrick Aoude
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Carolyn R Bertozzi
- Department of Chemistry, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Verna M Estes
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Brian J Lee
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Govind Bhagat
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Immunology and Microbiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Shan Zha
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Department of Immunology and Microbiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Eliezer Calo
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Stolyarenko AD. Nuclear Argonaute Piwi Gene Mutation Affects rRNA by Inducing rRNA Fragment Accumulation, Antisense Expression, and Defective Processing in Drosophila Ovaries. Int J Mol Sci 2020; 21:ijms21031119. [PMID: 32046213 PMCID: PMC7037970 DOI: 10.3390/ijms21031119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/27/2020] [Accepted: 02/04/2020] [Indexed: 12/26/2022] Open
Abstract
Drosophila key nuclear piRNA silencing pathway protein Piwi of the Argonaute family has been classically studied as a factor controlling transposable elements and fertility. Piwi has been shown to concentrate in the nucleolus for reasons largely unknown. Ribosomal RNA is the main component of the nucleolus. In this work the effect of a piwi mutation on rRNA is described. This work led to three important conclusions: A mutation in piwi induces antisense 5S rRNA expression, a processing defect of 2S rRNA orthologous to the 3′-end of eukaryotic 5.8S rRNA, and accumulation of fragments of all five rRNAs in Drosophilamelanogaster ovaries. Hypotheses to explain these phenomena are proposed, possibly involving the interaction of the components of the piRNA pathway with the RNA surveillance machinery.
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Affiliation(s)
- Anastasia D Stolyarenko
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., Moscow 123182, Russia
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24
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Pillon MC, Lo YH, Stanley RE. IT'S 2 for the price of 1: Multifaceted ITS2 processing machines in RNA and DNA maintenance. DNA Repair (Amst) 2019; 81:102653. [PMID: 31324529 PMCID: PMC6764878 DOI: 10.1016/j.dnarep.2019.102653] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cells utilize sophisticated RNA processing machines to ensure the quality of RNA. Many RNA processing machines have been further implicated in regulating the DNA damage response signifying a strong link between RNA processing and genome maintenance. One of the most intricate and highly regulated RNA processing pathways is the processing of the precursor ribosomal RNA (pre-rRNA), which is paramount for the production of ribosomes. Removal of the Internal Transcribed Spacer 2 (ITS2), located between the 5.8S and 25S rRNA, is one of the most complex steps of ribosome assembly. Processing of the ITS2 is initiated by the newly discovered endoribonuclease Las1, which cleaves at the C2 site within the ITS2, generating products that are further processed by the polynucleotide kinase Grc3, the 5'→3' exonuclease Rat1, and the 3'→5' RNA exosome complex. In addition to their defined roles in ITS2 processing, these critical cellular machines participate in other stages of ribosome assembly, turnover of numerous cellular RNAs, and genome maintenance. Here we summarize recent work defining the molecular mechanisms of ITS2 processing by these essential RNA processing machines and highlight their emerging roles in transcription termination, heterochromatin function, telomere maintenance, and DNA repair.
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Affiliation(s)
- Monica C Pillon
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Yu-Hua Lo
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Robin E Stanley
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA.
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25
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Bohnsack KE, Bohnsack MT. Uncovering the assembly pathway of human ribosomes and its emerging links to disease. EMBO J 2019; 38:e100278. [PMID: 31268599 PMCID: PMC6600647 DOI: 10.15252/embj.2018100278] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/18/2019] [Accepted: 04/26/2019] [Indexed: 12/12/2022] Open
Abstract
The essential cellular process of ribosome biogenesis is at the nexus of various signalling pathways that coordinate protein synthesis with cellular growth and proliferation. The fact that numerous diseases are caused by defects in ribosome assembly underscores the importance of obtaining a detailed understanding of this pathway. Studies in yeast have provided a wealth of information about the fundamental principles of ribosome assembly, and although many features are conserved throughout eukaryotes, the larger size of human (pre-)ribosomes, as well as the evolution of additional regulatory networks that can modulate ribosome assembly and function, have resulted in a more complex assembly pathway in humans. Notably, many ribosome biogenesis factors conserved from yeast appear to have subtly different or additional functions in humans. In addition, recent genome-wide, RNAi-based screens have identified a plethora of novel factors required for human ribosome biogenesis. In this review, we discuss key aspects of human ribosome production, highlighting differences to yeast, links to disease, as well as emerging concepts such as extra-ribosomal functions of ribosomal proteins and ribosome heterogeneity.
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Affiliation(s)
- Katherine E Bohnsack
- Department of Molecular BiologyUniversity Medical Center GöttingenGöttingenGermany
| | - Markus T Bohnsack
- Department of Molecular BiologyUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Center for Molecular BiosciencesGeorg‐August UniversityGöttingenGermany
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26
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Zhang Z, Tang J, Di R, Liu Q, Wang X, Gan S, Zhang X, Zhang J, Chen W, Hu W, Chu M. Identification of Prolificacy-Related Differentially Expressed Proteins from Sheep (Ovis aries) Hypothalamus by Comparative Proteomics. Proteomics 2019; 19:e1900118. [PMID: 31136077 DOI: 10.1002/pmic.201900118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/13/2019] [Indexed: 12/12/2022]
Abstract
Reproduction, as a physiologically complex process, can significantly affect the development of the sheep industry. However, a lack of overall understanding to sheep fecundity has long blocked the progress in sheep breeding and husbandry. In the present study, the aim is to identify differentially expressed proteins (DEPs) from hypothalamus in sheep without FecB mutation in two comparison groups: polytocous (PF) versus monotocous (MF) sheep at follicular phase and polytocous (PL) versus monotocous (ML) sheep at luteal phase. Totally 5058 proteins are identified in sheep hypothalamus, where 22 in PF versus MF, and 39 proteins in PL versus ML are differentially expressed, respectively. A functional analysis is then conducted including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis to reveal the potential roles of these DEPs. The proteins ENSOARP00000020097, ENSOARP00000006714, growth hormone (GH), histone deacetylase 4 (HDAC4), and 5'-3' exoribonuclease 2 (XRN2) in PF versus MF, and bcl-2-associated athanogene 4 (BAG4), insulin-like growth factor-1 receptor (IGF1R), hydroxysteroid 11-beta dehydrogenase 1 (HSD11B1), and transthyretin (TTR) in PL versus ML appear to modulate reproduction, presumably by influencing the activities of gonadotropin-releasing hormone (GnRH). This study provides an alternative method to identify DEPs associated with sheep prolificacy from the hypothalamus. The mass spectrometry data are available via ProteomeXchange with identifier PXD013822.
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Affiliation(s)
- Zhuangbiao Zhang
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Jishun Tang
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.,Institute of Animal Husbandry and Veterinary Medicine, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Ran Di
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Qiuyue Liu
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xiangyu Wang
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Shangquan Gan
- State Key Laboratory of Sheep Genetic Improvement and Healthy Production, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi, 832000, China
| | - Xiaosheng Zhang
- Tianjin Institute of Animal Sciences, Tianjin, 300381, China
| | - Jinlong Zhang
- Tianjin Institute of Animal Sciences, Tianjin, 300381, China
| | - Wei Chen
- Shanghai Applied Protein Technology Co., Ltd., Shanghai, 200233, China
| | - Wenping Hu
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Mingxing Chu
- Key Laboratory of Animal Genetics and Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
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27
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Choudhury P, Hackert P, Memet I, Sloan KE, Bohnsack MT. The human RNA helicase DHX37 is required for release of the U3 snoRNP from pre-ribosomal particles. RNA Biol 2018; 16:54-68. [PMID: 30582406 PMCID: PMC6380342 DOI: 10.1080/15476286.2018.1556149] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Ribosome synthesis is an essential cellular process, and perturbation of human ribosome production is linked to cancer and genetic diseases termed ribosomopathies. During their assembly, pre-ribosomal particles undergo numerous structural rearrangements, which establish the architecture present in mature complexes and serve as key checkpoints, ensuring the fidelity of ribosome biogenesis. RNA helicases are essential mediators of such remodelling events and here, we demonstrate that the DEAH-box RNA helicase DHX37 is required for maturation of the small ribosomal subunit in human cells. Our data reveal that the presence of DHX37 in early pre-ribosomal particles is monitored by a quality control pathway and that failure to recruit DHX37 leads to pre-rRNA degradation. Using an in vivo crosslinking approach, we show that DHX37 binds directly to the U3 small nucleolar RNA (snoRNA) and demonstrate that the catalytic activity of the helicase is required for dissociation of the U3 snoRNA from pre-ribosomal complexes. This is an important event during ribosome assembly as it enables formation of the central pseudoknot structure of the small ribosomal subunit. We identify UTP14A as a direct interaction partner of DHX37 and our data suggest that UTP14A can act as a cofactor that stimulates the activity of the helicase in the context of U3 snoRNA release.
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Affiliation(s)
- Priyanka Choudhury
- a Department of Molecular Biology , University Medical Centre Göttingen , Göttingen , Germany
| | - Philipp Hackert
- a Department of Molecular Biology , University Medical Centre Göttingen , Göttingen , Germany
| | - Indira Memet
- a Department of Molecular Biology , University Medical Centre Göttingen , Göttingen , Germany
| | - Katherine E Sloan
- a Department of Molecular Biology , University Medical Centre Göttingen , Göttingen , Germany
| | - Markus T Bohnsack
- a Department of Molecular Biology , University Medical Centre Göttingen , Göttingen , Germany.,b Göttingen Center for Molecular Biosciences , Georg-August University , Göttingen , Germany
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28
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Kobyłecki K, Drążkowska K, Kuliński TM, Dziembowski A, Tomecki R. Elimination of 01/A'-A0 pre-rRNA processing by-product in human cells involves cooperative action of two nuclear exosome-associated nucleases: RRP6 and DIS3. RNA (NEW YORK, N.Y.) 2018; 24:1677-1692. [PMID: 30266864 PMCID: PMC6239190 DOI: 10.1261/rna.066589.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 09/17/2018] [Indexed: 05/10/2023]
Abstract
Pre-rRNA processing generates mature 18S, 5.8S, and 28S/25S rRNAs through multistage removal of surrounding 5'-ETS/3'-ETS and intervening ITS1/ITS2 segments. Endonucleolytic activities release by-products, which need to be eliminated. Here, we investigated the interplay of exosome-associated 3'-5' exonucleases DIS3 and RRP6 in rRNA processing and by-product elimination in human cells. In agreement with previous reports, we observed accumulation of 5.8S and 18S precursors upon dysfunction of these enzymes. However, none of these phenotypes was so pronounced as previously overlooked accumulation of short RNA species derived from 5'-ETS (01/A'-A0), in cells with nonfunctional DIS3. We demonstrate that removal of 01/A'-A0 is independent of the XRN2 5'-3' exonucleolytic activity. Instead, it proceeds rapidly after A0 cleavage and occurs exclusively in the 3'-5' direction in several phases-following initiation by an unknown nuclease, the decay is executed by RRP6 with some contribution of DIS3, whereas the ultimate phase involves predominantly DIS3. Our data shed new light onto the role of human exosome in 5'-ETS removal. Furthermore, although 01/A'-A0 degradation involves the action of two nucleases associated with the exosome ring, similarly to 5.8S 3'-end maturation, it is likely that contrary to the latter process, RRP6 acts prior to or redundantly with DIS3.
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Affiliation(s)
- Kamil Kobyłecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
- Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Karolina Drążkowska
- Department of RNA Metabolism, Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
| | - Tomasz M Kuliński
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
- Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Andrzej Dziembowski
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
- Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Rafał Tomecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
- Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
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29
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SAMMSON fosters cancer cell fitness by concertedly enhancing mitochondrial and cytosolic translation. Nat Struct Mol Biol 2018; 25:1035-1046. [PMID: 30374086 PMCID: PMC6223542 DOI: 10.1038/s41594-018-0143-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 09/12/2018] [Indexed: 01/09/2023]
Abstract
Synchronization of mitochondrial and cytoplasmic translation rates is critical for the maintenance of cellular fitness, with cancer cells being especially vulnerable to translational uncoupling. Although alterations of cytosolic protein synthesis are common in human cancer, compensating mechanisms in mitochondrial translation remain elusive. Here we show that the malignant long non-coding RNA (lncRNA) SAMMSON promotes a balanced increase in ribosomal RNA (rRNA) maturation and protein synthesis in the cytosol and mitochondria by modulating the localization of CARF, an RNA-binding protein that sequesters the exo-ribonuclease XRN2 in the nucleoplasm, which under normal circumstances limits nucleolar rRNA maturation. SAMMSON interferes with XRN2 binding to CARF in the nucleus by favoring the formation of an aberrant cytoplasmic RNA-protein complex containing CARF and p32, a mitochondrial protein required for the processing of the mitochondrial rRNAs. These data highlight how a single oncogenic lncRNA can simultaneously modulate RNA-protein complex formation in two distinct cellular compartments to promote cell growth.
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30
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Aubert M, O'Donohue MF, Lebaron S, Gleizes PE. Pre-Ribosomal RNA Processing in Human Cells: From Mechanisms to Congenital Diseases. Biomolecules 2018; 8:biom8040123. [PMID: 30356013 PMCID: PMC6315592 DOI: 10.3390/biom8040123] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022] Open
Abstract
Ribosomal RNAs, the most abundant cellular RNA species, have evolved as the structural scaffold and the catalytic center of protein synthesis in every living organism. In eukaryotes, they are produced from a long primary transcript through an intricate sequence of processing steps that include RNA cleavage and folding and nucleotide modification. The mechanisms underlying this process in human cells have long been investigated, but technological advances have accelerated their study in the past decade. In addition, the association of congenital diseases to defects in ribosome synthesis has highlighted the central place of ribosomal RNA maturation in cell physiology regulation and broadened the interest in these mechanisms. Here, we give an overview of the current knowledge of pre-ribosomal RNA processing in human cells in light of recent progress and discuss how dysfunction of this pathway may contribute to the physiopathology of congenital diseases.
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Affiliation(s)
- Maxime Aubert
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France.
| | - Marie-Françoise O'Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France.
| | - Simon Lebaron
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France.
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France.
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31
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Singh SS, Naiyer S, Bharadwaj R, Kumar A, Singh YP, Ray AK, Subbarao N, Bhattacharya A, Bhattacharya S. Stress-induced nuclear depletion of Entamoeba histolytica 3'-5' exoribonuclease EhRrp6 and its role in growth and erythrophagocytosis. J Biol Chem 2018; 293:16242-16260. [PMID: 30171071 DOI: 10.1074/jbc.ra118.004632] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/10/2018] [Indexed: 01/24/2023] Open
Abstract
The 3'-5' exoribonuclease Rrp6 is a key enzyme in RNA homeostasis involved in processing and degradation of many stable RNA precursors, aberrant transcripts, and noncoding RNAs. We previously have shown that in the protozoan parasite Entamoeba histolytica, the 5'-external transcribed spacer fragment of pre-rRNA accumulates under serum starvation-induced growth stress. This fragment is a known target of degradation by Rrp6. Here, we computationally and biochemically characterized EhRrp6 and found that it contains the catalytically important EXO and HRDC domains and exhibits exoribonuclease activity with both unstructured and structured RNA substrates, which required the conserved DEDD-Y catalytic-site residues. It lacked the N-terminal PMC2NT domain for binding of the cofactor Rrp47, but could functionally complement the growth defect of a yeast rrp6 mutant. Of note, no Rrp47 homologue was detected in E. histolytica Immunolocalization studies revealed that EhRrp6 is present both in the nucleus and cytosol of normal E. histolytica cells. However, growth stress induced its complete loss from the nuclei, reversed by proteasome inhibitors. EhRrp6-depleted E. histolytica cells were severely growth restricted, and EhRrp6 overexpression protected the cells against stress, suggesting that EhRrp6 functions as a stress sensor. Importantly EhRrp6 depletion reduced erythrophagocytosis, an important virulence determinant of E. histolytica This reduction was due to a specific decrease in transcript levels of some phagocytosis-related genes (Ehcabp3 and Ehrho1), whereas expression of other genes (Ehcabp1, Ehcabp6, Ehc2pk, and Eharp2/3) was unaffected. This is the first report of the role of Rrp6 in cell growth and stress responses in a protozoan parasite.
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Affiliation(s)
| | | | - Ravi Bharadwaj
- the School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Amarjeet Kumar
- the School of Computational and Integrative Sciences, and
| | | | | | - Naidu Subbarao
- the School of Computational and Integrative Sciences, and
| | - Alok Bhattacharya
- the School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
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32
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Montellese C, Montel-Lehry N, Henras AK, Kutay U, Gleizes PE, O'Donohue MF. Poly(A)-specific ribonuclease is a nuclear ribosome biogenesis factor involved in human 18S rRNA maturation. Nucleic Acids Res 2017; 45:6822-6836. [PMID: 28402503 PMCID: PMC5499762 DOI: 10.1093/nar/gkx253] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/03/2017] [Indexed: 01/28/2023] Open
Abstract
The poly-A specific ribonuclease (PARN), initially characterized for its role in mRNA catabolism, supports the processing of different types of non-coding RNAs including telomerase RNA. Mutations in PARN are linked to dyskeratosis congenita and pulmonary fibrosis. Here, we show that PARN is part of the enzymatic machinery that matures the human 18S ribosomal RNA (rRNA). Consistent with its nucleolar steady-state localization, PARN is required for 40S ribosomal subunit production and co-purifies with 40S subunit precursors. Depletion of PARN or expression of a catalytically-compromised PARN mutant results in accumulation of 3΄ extended 18S rRNA precursors. Analysis of these processing intermediates reveals a defect in 3΄ to 5΄ trimming of the internal transcribed spacer 1 (ITS1) region, subsequent to endonucleolytic cleavage at site E. Consistent with a function of PARN in exonucleolytic trimming of 18S-E pre-rRNA, recombinant PARN can process the corresponding ITS1 RNA fragment in vitro. Trimming of 18S-E pre-rRNA by PARN occurs in the nucleus, upstream of the final endonucleolytic cleavage by the endonuclease NOB1 in the cytoplasm. These results identify PARN as a new component of the ribosome biogenesis machinery in human cells. Defects in ribosome biogenesis could therefore underlie the pathologies linked to mutations in PARN.
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Affiliation(s)
| | - Nathalie Montel-Lehry
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Ulrike Kutay
- Institut für Biochemie, ETH Zurich, Zurich CH-8093, Switzerland
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Marie-Françoise O'Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
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33
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Abstract
Numerous surveillance pathways sculpt eukaryotic transcriptomes by degrading unneeded, defective, and potentially harmful noncoding RNAs (ncRNAs). Because aberrant and excess ncRNAs are largely degraded by exoribonucleases, a key characteristic of these RNAs is an accessible, protein-free 5' or 3' end. Most exoribonucleases function with cofactors that recognize ncRNAs with accessible 5' or 3' ends and/or increase the availability of these ends. Noncoding RNA surveillance pathways were first described in budding yeast, and there are now high-resolution structures of many components of the yeast pathways and significant mechanistic understanding as to how they function. Studies in human cells are revealing the ways in which these pathways both resemble and differ from their yeast counterparts, and are also uncovering numerous pathways that lack equivalents in budding yeast. In this review, we describe both the well-studied pathways uncovered in yeast and the new concepts that are emerging from studies in mammalian cells. We also discuss the ways in which surveillance pathways compete with chaperone proteins that transiently protect nascent ncRNA ends from exoribonucleases, with partner proteins that sequester these ends within RNPs, and with end modification pathways that protect the ends of some ncRNAs from nucleases.
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Affiliation(s)
- Cedric Belair
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Frederick , Maryland 21702 , United States
| | - Soyeong Sim
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Frederick , Maryland 21702 , United States
| | - Sandra L Wolin
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Frederick , Maryland 21702 , United States
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34
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Ikeda Y, Okada Y, Sato A, Kanai T, Tomita M, Atomi H, Kanai A. An archaeal RNA binding protein, FAU-1, is a novel ribonuclease related to rRNA stability in Pyrococcus and Thermococcus. Sci Rep 2017; 7:12674. [PMID: 28978920 PMCID: PMC5627344 DOI: 10.1038/s41598-017-13062-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 09/12/2017] [Indexed: 12/28/2022] Open
Abstract
Ribosome biogenesis and turnover are processes necessary for cell viability and proliferation, and many kinds of proteins are known to regulate these processes. However, many questions still remain, especially in the Archaea. Generally, several ribonucleases are required to process precursor rRNAs to their mature forms, and to degrade rRNAs for quality control. Here, we found that FAU-1, which is known to be an RNA binding protein, possesses an RNase activity against precursor 5S rRNA derived from P. furiosus and T. kodakarensis in the order Thermococcales in vitro. An in vitro analysis revealed that UA sequences in the upstream of 5S rRNA were preferentially degraded by addition of FAU-1. Moreover, a fau-1 gene deletion mutant of T. kodakarensis showed a delay of exponential phase, reduction of maximum cell number and significant changes in the nucleotide sequence lengths of its 5S, 16S, and 23S rRNAs in early exponential phase. Our results suggest that FAU-1 is a potential RNase involved in rRNA stability through maturation and/or degradation processes.
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Affiliation(s)
- Yoshiki Ikeda
- Institute for Advanced Biosciences, Keio University, Tsuruoka, 997-0017, Japan.
| | - Yasuhiro Okada
- Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Asako Sato
- Institute for Advanced Biosciences, Keio University, Tsuruoka, 997-0017, Japan
| | - Tamotsu Kanai
- Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Masaru Tomita
- Institute for Advanced Biosciences, Keio University, Tsuruoka, 997-0017, Japan
| | - Haruyuki Atomi
- Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Akio Kanai
- Institute for Advanced Biosciences, Keio University, Tsuruoka, 997-0017, Japan
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35
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Memet I, Doebele C, Sloan KE, Bohnsack MT. The G-patch protein NF-κB-repressing factor mediates the recruitment of the exonuclease XRN2 and activation of the RNA helicase DHX15 in human ribosome biogenesis. Nucleic Acids Res 2017; 45:5359-5374. [PMID: 28115624 PMCID: PMC5435916 DOI: 10.1093/nar/gkx013] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/04/2017] [Indexed: 01/05/2023] Open
Abstract
In eukaryotes, the synthesis of ribosomal subunits, which involves the maturation of the ribosomal (r)RNAs and assembly of ribosomal proteins, requires the co-ordinated action of a plethora of ribosome biogenesis factors. Many of these cofactors remain to be characterized in human cells. Here, we demonstrate that the human G-patch protein NF-κB-repressing factor (NKRF) forms a pre-ribosomal subcomplex with the DEAH-box RNA helicase DHX15 and the 5΄-3΄ exonuclease XRN2. Using UV crosslinking and analysis of cDNA (CRAC), we reveal that NKRF binds to the transcribed spacer regions of the pre-rRNA transcript. Consistent with this, we find that depletion of NKRF, XRN2 or DHX15 impairs an early pre-rRNA cleavage step (A’). The catalytic activity of DHX15, which we demonstrate is stimulated by NKRF functioning as a cofactor, is required for efficient A’ cleavage, suggesting that a structural remodelling event may facilitate processing at this site. In addition, we show that depletion of NKRF or XRN2 also leads to the accumulation of excised pre-rRNA spacer fragments and that NKRF is essential for recruitment of the exonuclease to nucleolar pre-ribosomal complexes. Our findings therefore reveal a novel pre-ribosomal subcomplex that plays distinct roles in the processing of pre-rRNAs and the turnover of excised spacer fragments.
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Affiliation(s)
- Indira Memet
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany
| | - Carmen Doebele
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany
| | - Katherine E Sloan
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany
| | - Markus T Bohnsack
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany.,Göttingen Centre for Molecular Biosciences, Georg-August-University, 37073 Göttingen, Germany
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36
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Tomecki R, Sikorski PJ, Zakrzewska-Placzek M. Comparison of preribosomal RNA processing pathways in yeast, plant and human cells - focus on coordinated action of endo- and exoribonucleases. FEBS Lett 2017; 591:1801-1850. [PMID: 28524231 DOI: 10.1002/1873-3468.12682] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/14/2017] [Accepted: 05/15/2017] [Indexed: 12/17/2022]
Abstract
Proper regulation of ribosome biosynthesis is mandatory for cellular adaptation, growth and proliferation. Ribosome biogenesis is the most energetically demanding cellular process, which requires tight control. Abnormalities in ribosome production have severe consequences, including developmental defects in plants and genetic diseases (ribosomopathies) in humans. One of the processes occurring during eukaryotic ribosome biogenesis is processing of the ribosomal RNA precursor molecule (pre-rRNA), synthesized by RNA polymerase I, into mature rRNAs. It must not only be accurate but must also be precisely coordinated with other phenomena leading to the synthesis of functional ribosomes: RNA modification, RNA folding, assembly with ribosomal proteins and nucleocytoplasmic RNP export. A multitude of ribosome biogenesis factors ensure that these events take place in a correct temporal order. Among them are endo- and exoribonucleases involved in pre-rRNA processing. Here, we thoroughly present a wide spectrum of ribonucleases participating in rRNA maturation, focusing on their biochemical properties, regulatory mechanisms and substrate specificity. We also discuss cooperation between various ribonucleolytic activities in particular stages of pre-rRNA processing, delineating major similarities and differences between three representative groups of eukaryotes: yeast, plants and humans.
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Affiliation(s)
- Rafal Tomecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.,Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Poland
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37
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XRN2 promotes EMT and metastasis through regulating maturation of miR-10a. Oncogene 2017; 36:3925-3933. [PMID: 28319071 DOI: 10.1038/onc.2017.39] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 01/05/2017] [Accepted: 01/31/2017] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRNAs) have been proposed as critical regulatory molecules in the epithelial-mesenchymal transition (EMT) program. However, the roles of mature miRNA biogenesis during EMT process needs to be defined. Here we determined that increased expression of XRN2 induced EMT and promoted metastasis in vitro and in vivo. Furthermore, we uncovered that XRN2 functions as pro-metastatic gene, which accelerates miR-10a maturation by binding pre-miR-10a in a DICER-independent manner. These findings suggest that XRN2 is a novel regulator of EMT that contributes to the metastatic processes in lung cancer through a novel miRNA regulatory mechanism.
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38
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Human NF-κB repressing factor acts as a stress-regulated switch for ribosomal RNA processing and nucleolar homeostasis surveillance. Proc Natl Acad Sci U S A 2017; 114:1045-1050. [PMID: 28096332 DOI: 10.1073/pnas.1616112114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The nucleolus, a dynamic nuclear compartment long regarded as the cell ribosome factory, is emerging as an important player in the regulation of cell survival and recovery from stress. In larger eukaryotes, the stress-induced transcriptional response is mediated by a family of heat-shock transcription factors. Among these, HSF1, considered the master regulator of stress-induced transcriptional responses, controls the expression of cytoprotective heat shock proteins (HSPs), molecular chaperones/cochaperones constituting a major component of the cell protein quality control machinery essential to circumvent stress-induced degradation and aggregation of misfolded proteins. Herein we identify human NF-κB repressing factor (NKRF) as a nucleolar HSP essential for nucleolus homeostasis and cell survival under proteotoxic stress. NKRF acts as a thermosensor translocating from the nucleolus to the nucleoplasm during heat stress; nucleolar pools are replenished during recovery upon HSF1-mediated NKRF resynthesis. Silencing experiments demonstrate that NKRF is an unconventional HSP crucial for correct ribosomal RNA (rRNA) processing and preventing aberrant rRNA precursors and discarded fragment accumulation. These effects are mediated by NKRF interaction with the 5'-to-3' exoribonuclease XRN2, a key coordinator of multiple pre-rRNA cleavages, driving mature rRNA formation and discarded rRNA decay. Under stress conditions, NKRF directs XRN2 nucleolus/nucleoplasm trafficking, controlling 5'-to-3' exoribonuclease nucleolar levels and regulating rRNA processing. Our study reveals a different aspect of rRNA biogenesis control in human cells and sheds light on a sophisticated mechanism of nucleolar homeostasis surveillance during stress.
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39
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Tomecki R, Labno A, Drazkowska K, Cysewski D, Dziembowski A. hUTP24 is essential for processing of the human rRNA precursor at site A1, but not at site A0. RNA Biol 2016; 12:1010-29. [PMID: 26237581 DOI: 10.1080/15476286.2015.1073437] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Production of ribosomes relies on more than 200 accessory factors to ensure the proper sequence of steps and faultless assembly of ribonucleoprotein machinery. Among trans-acting factors are numerous enzymes, including ribonucleases responsible for processing the large rRNA precursor synthesized by RNA polymerase I that encompasses sequences corresponding to mature 18S, 5.8S, and 25/28S rRNA. In humans, the identity of most enzymes responsible for individual processing steps, including endoribonucleases that cleave pre-rRNA at specific sites within regions flanking and separating mature rRNA, remains largely unknown. Here, we investigated the role of hUTP24 in rRNA maturation in human cells. hUTP24 is a human homolog of the Saccharomyces cerevisiae putative PIN domain-containing endoribonuclease Utp24 (yUtp24), which was suggested to participate in the U3 snoRNA-dependent processing of yeast pre-rRNA at sites A0, A1, and A2. We demonstrate that hUTP24 interacts to some extent with proteins homologous to the components of the yeast small subunit (SSU) processome. Moreover, mutation in the putative catalytic site of hUTP24 results in slowed growth of cells and reduced metabolic activity. These effects are associated with a defect in biogenesis of the 40S ribosomal subunit, which results from decreased amounts of 18S rRNA as a consequence of inaccurate pre-rRNA processing at the 5'-end of the 18S rRNA segment (site A1). Interestingly, and in contrast to yeast, site A0 located upstream of A1 is efficiently processed upon UTP24 dysfunction. Finally, hUTP24 inactivation leads to aberrant processing of 18S rRNA 2 nucleotides downstream of the normal A1 cleavage site.
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Affiliation(s)
- Rafal Tomecki
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Anna Labno
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Karolina Drazkowska
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Dominik Cysewski
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Andrzej Dziembowski
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
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40
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Wells GR, Weichmann F, Colvin D, Sloan KE, Kudla G, Tollervey D, Watkins NJ, Schneider C. The PIN domain endonuclease Utp24 cleaves pre-ribosomal RNA at two coupled sites in yeast and humans. Nucleic Acids Res 2016; 44:5399-409. [PMID: 27034467 PMCID: PMC4914098 DOI: 10.1093/nar/gkw213] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/18/2016] [Indexed: 11/12/2022] Open
Abstract
During ribosomal RNA (rRNA) maturation, cleavages at defined sites separate the mature rRNAs from spacer regions, but the identities of several enzymes required for 18S rRNA release remain unknown. PilT N-terminus (PIN) domain proteins are frequently endonucleases and the PIN domain protein Utp24 is essential for early cleavages at three pre-rRNA sites in yeast (A0, A1 and A2) and humans (A0, 1 and 2a). In yeast, A1 is cleaved prior to A2 and both cleavages require base-pairing by the U3 snoRNA to the central pseudoknot elements of the 18S rRNA. We found that yeast Utp24 UV-crosslinked in vivo to U3 and the pseudoknot, placing Utp24 close to cleavage at site A1. Yeast and human Utp24 proteins exhibited in vitro endonuclease activity on an RNA substrate containing yeast site A2. Moreover, an intact PIN domain in human UTP24 was required for accurate cleavages at sites 1 and 2a in vivo, whereas mutation of another potential site 2a endonuclease, RCL1, did not affect 18S production. We propose that Utp24 cleaves sites A1/1 and A2/2a in yeast and human cells.
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Affiliation(s)
- Graeme R Wells
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Franziska Weichmann
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - David Colvin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Katherine E Sloan
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Grzegorz Kudla
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Nicholas J Watkins
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Claudia Schneider
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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41
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Structural basis and function of XRN2 binding by XTB domains. Nat Struct Mol Biol 2016; 23:164-71. [PMID: 26779609 PMCID: PMC4888950 DOI: 10.1038/nsmb.3155] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/04/2015] [Indexed: 12/28/2022]
Abstract
The ribonuclease XRN2 is an essential player in RNA metabolism. In Caenorhabditis elegans, XRN2 functions with PAXT-1, which shares a putative XRN2-binding domain (XTBD) with otherwise unrelated mammalian proteins. Here, we characterize structure and function of an XTBD – XRN2 complex. Although XTBD stably interconnects two XRN2 domains through numerous interacting residues, mutation of a single critical residue suffices to disrupt XTBD – XRN2 complexes in vitro, and recapitulates paxt-1 null mutant phenotypes in vivo. Demonstrating conservation of function, vertebrate XTBD-containing proteins bind XRN2 in vitro, and human CDKN2AIPNL (C2AIL) can substitute for PAXT-1 in vivo. In vertebrates, where three distinct XTBD-containing proteins exist, XRN2 may partition to distinct stable heterodimeric complexes, likely differing in subcellular localization or function. In C. elegans, complex formation with the unique PAXT-1 serves to preserve the stability of XRN2 in the absence of substrate.
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42
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Pan WA, Tsai HY, Wang SC, Hsiao M, Wu PY, Tsai MD. The RNA recognition motif of NIFK is required for rRNA maturation during cell cycle progression. RNA Biol 2015; 12:255-67. [PMID: 25826659 PMCID: PMC4615200 DOI: 10.1080/15476286.2015.1017221] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ribosome biogenesis governs protein synthesis. NIFK is transactivated by c-Myc, the key regulator of ribosome biogenesis. The biological function of human NIFK is not well established, except that it has been shown to interact with Ki67 and NPM1. Here we report that NIFK is required for cell cycle progression and participates in the ribosome biogenesis via its RNA recognition motif (RRM). We show that silencing of NIFK inhibits cell proliferation through a reversible p53-dependent G1 arrest, possibly by induction of the RPL5/RPL11-mediated nucleolar stress. Mechanistically it is the consequence of impaired maturation of 28S and 5.8S rRNA resulting from inefficient cleavage of internal transcribed spacer (ITS) 1, a critical step in the separation of pre-ribosome to small and large subunits. Complementation of NIFK silencing by mutants shows that RNA-binding ability of RRM is essential for the pre-rRNA processing and G1 progression. More specifically, we validate that the RRM of NIFK preferentially binds to the 5′-region of ITS2 rRNA likely in both sequence specific and secondary structure dependent manners. Our results show how NIFK is involved in cell cycle progression through RRM-dependent pre-rRNA maturation, which could enhance our understanding of the function of NIFK in cell proliferation, and potentially also cancer and ribosomopathies.
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Key Words
- 5S RNP, 5S ribonucleoprotein particle
- CDK1, cyclin dependent kinase 1
- DFC, dense fibrillar component
- ETS/ITS, external/internal transcribed spacers
- GSK3, glycogen synthase kinase 3
- Ki67
- Ki67FHAID, Ki67-FHA interaction domain
- LSU, large subunit
- MDM2, murine double minute 2
- NIFK, Nucleolar protein Interacting with the FHA domain of pKi-67
- NPM1/B23, nucleophosmin
- Noprecipitation
- PAR-CLIP, Photo-Activatable-Ribonucleoside-Enhanced Crosslinking and Immu-pre-rRNAs, rRNA precursors
- REMSA, RNA electrophoresis mobility shift assay
- RNA recognition motif
- RNP1 and 2, ribonucleoprotein motif 1 and 2
- RPL5 and RPL11, large ribosomal protein 5 and 11
- RRM, RNA recognition motif
- cell cycle
- nucleolar stress
- rNIFK, recombinant NIFK
- ribosome biogenesis
- snoRNP, small nucleolar ribonucleoprotein
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Affiliation(s)
- Wen-An Pan
- a Institute of Biological Chemistry; Academia Sinica ; Taipei , Taiwan
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43
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Sato S, Ishikawa H, Yoshikawa H, Izumikawa K, Simpson RJ, Takahashi N. Collaborator of alternative reading frame protein (CARF) regulates early processing of pre-ribosomal RNA by retaining XRN2 (5'-3' exoribonuclease) in the nucleoplasm. Nucleic Acids Res 2015; 43:10397-410. [PMID: 26531822 PMCID: PMC4666357 DOI: 10.1093/nar/gkv1069] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/05/2015] [Indexed: 11/17/2022] Open
Abstract
Collaborator of alternative reading frame protein (CARF) associates directly with ARF, p53, and/or human double minute 2 protein (HDM2), a ubiquitin-protein ligase, without cofactors and regulates cell proliferation by forming a negative feedback loop. Although ARF, p53, and HDM2 also participate in the regulation of ribosome biogenesis, the involvement of CARF in this process remains unexplored. In this study, we demonstrate that CARF associates with 5′-3′ exoribonuclease 2 (XRN2), which plays a major role in both the maturation of rRNA and the degradation of a variety of discarded pre-rRNA species. We show that overexpression of CARF increases the localization of XRN2 in the nucleoplasm and a concomitant suppression of pre-rRNA processing that leads to accumulation of the 5′ extended from of 45S/47S pre-rRNA and 5′-01, A0-1 and E-2 fragments of pre-rRNA transcript in the nucleolus. This was also observed upon XRN2 knockdown. Knockdown of CARF increased the amount of XRN2 in the nucleolar fraction as determined by cell fractionation and by immnocytochemical analysis. These observations suggest that CARF regulates early steps of pre-rRNA processing during ribosome biogenesis by controlling spatial distribution of XRN2 between the nucleoplasm and nucleolus.
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Affiliation(s)
- Shigeko Sato
- Department of Applied Biological Science, United-graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Hideaki Ishikawa
- Department of Applied Biological Science, United-graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan The Genome Science human resource development program, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
| | - Harunori Yoshikawa
- Department of Applied Biological Science, United-graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan Centre for Gene Regulation & Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Keiichi Izumikawa
- Department of Applied Biological Science, United-graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan The Genome Science human resource development program, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
| | - Richard J Simpson
- La Trobe Institute for Molecular Science (LIMS) LIMS Building 1, Room 412 La Trobe University, Bundoora Victoria 3086, Australia
| | - Nobuhiro Takahashi
- Department of Applied Biological Science, United-graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan The Genome Science human resource development program, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
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44
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Wang M, Parshin AV, Shcherbik N, Pestov DG. Reduced expression of the mouse ribosomal protein Rpl17 alters the diversity of mature ribosomes by enhancing production of shortened 5.8S rRNA. RNA (NEW YORK, N.Y.) 2015; 21:1240-1248. [PMID: 25995445 PMCID: PMC4478343 DOI: 10.1261/rna.051169.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 04/10/2015] [Indexed: 06/04/2023]
Abstract
Processing of rRNA during ribosome assembly can proceed through alternative pathways but it is unclear whether this could affect the structure of the ribosome. Here, we demonstrate that shortage of a ribosomal protein can change pre-rRNA processing in a way that over time alters ribosome diversity in the cell. Reducing the amount of Rpl17 in mouse cells led to stalled 60S subunit maturation, causing degradation of most of the synthesized precursors. A fraction of pre-60S subunits, however, were able to complete maturation, but with a 5'-truncated 5.8S rRNA, which we named 5.8SC. The 5' exoribonuclease Xrn2 is involved in the generation of both 5.8S(C) and the canonical long form of 5.8S rRNA. Ribosomes containing 5.8S(C) rRNA are present in various mouse and human cells and engage in translation. These findings uncover a previously undescribed form of mammalian 5.8S rRNA and demonstrate that perturbations in ribosome assembly can be a source of heterogeneity in mature ribosomes.
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Affiliation(s)
- Minshi Wang
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, USA
| | - Andrey V Parshin
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, USA
| | - Natalia Shcherbik
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, USA
| | - Dimitri G Pestov
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, USA
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45
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Yoshikawa H, Ishikawa H, Izumikawa K, Miura Y, Hayano T, Isobe T, Simpson RJ, Takahashi N. Human nucleolar protein Nop52 (RRP1/NNP-1) is involved in site 2 cleavage in internal transcribed spacer 1 of pre-rRNAs at early stages of ribosome biogenesis. Nucleic Acids Res 2015; 43:5524-36. [PMID: 25969445 PMCID: PMC4477673 DOI: 10.1093/nar/gkv470] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/29/2015] [Indexed: 01/02/2023] Open
Abstract
During the early steps of ribosome biogenesis in mammals, the two ribosomal subunits 40S and 60S are produced via splitting of the large 90S pre-ribosomal particle (90S) into pre-40S and pre-60S pre-ribosomal particles (pre-40S and pre-60S). We previously proposed that replacement of fibrillarin by Nop52 (RRP1/NNP-1) for the binding to p32 (C1QBP) is a key event that drives this splitting process. However, how the replacement by RRP1 is coupled with the endo- and/or exo-ribonucleolytic cleavage of pre-rRNA remains unknown. In this study, we demonstrate that RRP1 deficiency suppressed site 2 cleavage on ITS1 of 47S/45S, 41S and 36S pre-rRNAs in human cells. RRP1 was also present in 90S and was localized in the dense fibrillar component of the nucleolus dependently on active RNA polymerase I transcription. In addition, double knockdown of XRN2 and RRP1 revealed that RRP1 accelerated the site 2 cleavage of 47S, 45S and 41S pre-rRNAs. These data suggest that RRP1 is involved not only in competitive binding with fibrillarin to C1QBP on 90S but also in site 2 cleavage in ITS1 of pre-rRNAs at early stages of human ribosome biogenesis; thus, it is likely that RRP1 integrates the cleavage of site 2 with the physical split of 90S into pre-40S and pre-60S.
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Affiliation(s)
- Harunori Yoshikawa
- Department of Applied Life Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan Centre for Gene Regulation & Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Hideaki Ishikawa
- Department of Applied Life Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo, 102-0075, Japan
| | - Keiichi Izumikawa
- Department of Applied Life Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo, 102-0075, Japan
| | - Yutaka Miura
- Department of Applied Life Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan
| | - Toshiya Hayano
- Department of Applied Life Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan
| | - Toshiaki Isobe
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo, 102-0075, Japan Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Richard J Simpson
- La Trobe Institute for Molecular Science (LIMS), LIMS Building 1, Room 412 La Trobe University, Bundoora Victoria 3086, Australia
| | - Nobuhiro Takahashi
- Department of Applied Life Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo, 102-0075, Japan
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46
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Weis BL, Palm D, Missbach S, Bohnsack MT, Schleiff E. atBRX1-1 and atBRX1-2 are involved in an alternative rRNA processing pathway in Arabidopsis thaliana. RNA (NEW YORK, N.Y.) 2015; 21:415-25. [PMID: 25605960 PMCID: PMC4338337 DOI: 10.1261/rna.047563.114] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 12/08/2014] [Indexed: 05/19/2023]
Abstract
Ribosome biogenesis is an essential process in all organisms. In eukaryotes, multiple ribosome biogenesis factors (RBFs) act in the processing of ribosomal (r)RNAs, assembly of ribosomal subunits and their export to the cytoplasm. We characterized two genes in Arabidopsis thaliana coding for orthologs of yeast BRX1, a protein involved in maturation of the large ribosomal subunit. Both atBRX1 proteins, encoded by AT3G15460 and AT1G52930, respectively, are mainly localized in the nucleolus and are ubiquitously expressed throughout plant development and in various tissues. Mutant plant lines for both factors show a delay in development and pointed leaves can be observed in the brx1-2 mutant, implying a link between ribosome biogenesis and plant development. In addition, the pre-rRNA processing is affected in both mutants. Analysis of the pre-rRNA intermediates revealed that early processing steps can occur either in the 5' external transcribed spacer (ETS) or internal transcribed spacer 1 (ITS1). Interestingly, we also find that in xrn2 mutants, early processing events can be bypassed and removal of the 5' ETS is initiated by cleavage at the P' processing site. While the pathways of pre-rRNA processing are comparable to those of yeast and mammalian cells, the balance between the two processing pathways is different in plants. Furthermore, plant-specific steps such as an additional processing site in the 5' ETS, likely post-transcriptional processing of the early cleavage sites and accumulation of a 5' extended 5.8S rRNA not observed in other eukaryotes can be detected.
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Affiliation(s)
- Benjamin L Weis
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany
| | - Denise Palm
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany
| | - Sandra Missbach
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany
| | - Markus T Bohnsack
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany Institute for Molecular Biology, Georg-August University, 37073 Göttingen, Germany
| | - Enrico Schleiff
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany Cluster of Excellence Frankfurt, Goethe University, 60438 Frankfurt/Main, Germany Center of Membrane Proteomics, Goethe University, 60438 Frankfurt/Main, Germany
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47
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Burroughs AM, Aravind L. Analysis of two domains with novel RNA-processing activities throws light on the complex evolution of ribosomal RNA biogenesis. Front Genet 2014; 5:424. [PMID: 25566315 PMCID: PMC4275035 DOI: 10.3389/fgene.2014.00424] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 11/19/2014] [Indexed: 11/13/2022] Open
Abstract
Ribosomal biogenesis has been extensively investigated, especially to identify the elusive nucleases and cofactors involved in the complex rRNA processing events in eukaryotes. Large-scale screens in yeast identified two biochemically uncharacterized proteins, TSR3 and TSR4, as being key players required for rRNA maturation. Using multiple computational approaches we identify the conserved domains comprising these proteins and establish sequence and structural features providing novel insights regarding their roles. TSR3 is unified with the DTW domain into a novel superfamily of predicted enzymatic domains, with the balance of the available evidence pointing toward an RNase role with the archaeo-eukaryotic TSR3 proteins processing rRNA and the bacterial versions potentially processing tRNA. TSR4, its other eukaryotic homologs PDCD2/rp-8, PDCD2L, Zfrp8, and trus, the predominantly bacterial DUF1963 proteins, and other uncharacterized proteins are unified into a new domain superfamily, which arose from an ancient duplication event of a strand-swapped, dimer-forming all-beta unit. We identify conserved features mediating protein-protein interactions (PPIs) and propose a potential chaperone-like function. While contextual evidence supports a conserved role in ribosome biogenesis for the eukaryotic TSR4-related proteins, there is no evidence for such a role for the bacterial versions. Whereas TSR3-related proteins can be traced to the last universal common ancestor (LUCA) with a well-supported archaeo-eukaryotic branch, TSR4-related proteins of eukaryotes are derived from within the bacterial radiation of this superfamily, with archaea entirely lacking them. This provides evidence for “systems admixture,” which followed the early endosymbiotic event, playing a key role in the emergence of the uniquely eukaryotic ribosome biogenesis process.
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Affiliation(s)
- A Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health Bethesda, MD, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health Bethesda, MD, USA
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48
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Henras AK, Plisson-Chastang C, O'Donohue MF, Chakraborty A, Gleizes PE. An overview of pre-ribosomal RNA processing in eukaryotes. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:225-42. [PMID: 25346433 PMCID: PMC4361047 DOI: 10.1002/wrna.1269] [Citation(s) in RCA: 385] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/04/2014] [Accepted: 08/29/2014] [Indexed: 12/23/2022]
Abstract
Ribosomal RNAs are the most abundant and universal noncoding RNAs in living organisms. In eukaryotes, three of the four ribosomal RNAs forming the 40S and 60S subunits are borne by a long polycistronic pre-ribosomal RNA. A complex sequence of processing steps is required to gradually release the mature RNAs from this precursor, concomitant with the assembly of the 79 ribosomal proteins. A large set of trans-acting factors chaperone this process, including small nucleolar ribonucleoparticles. While yeast has been the gold standard for studying the molecular basis of this process, recent technical advances have allowed to further define the mechanisms of ribosome biogenesis in animals and plants. This renewed interest for a long-lasting question has been fueled by the association of several genetic diseases with mutations in genes encoding both ribosomal proteins and ribosome biogenesis factors, and by the perspective of new anticancer treatments targeting the mechanisms of ribosome synthesis. A consensus scheme of pre-ribosomal RNA maturation is emerging from studies in various kinds of eukaryotic organisms. However, major differences between mammalian and yeast pre-ribosomal RNA processing have recently come to light. WIREs RNA 2015, 6:225–242. doi: 10.1002/wrna.1269
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Affiliation(s)
- Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Université de Toulouse-Paul Sabatier CNRS, UMR 5099, Toulouse, France
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49
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Wang M, Anikin L, Pestov DG. Two orthogonal cleavages separate subunit RNAs in mouse ribosome biogenesis. Nucleic Acids Res 2014; 42:11180-91. [PMID: 25190460 PMCID: PMC4176171 DOI: 10.1093/nar/gku787] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Ribosome biogenesis is a dynamic multistep process, many features of which are still incompletely documented. Here, we show that changes in this pathway can be captured and annotated by means of a graphic set of pre-rRNA ratios, a technique we call Ratio Analysis of Multiple Precursors (RAMP). We find that knocking down a ribosome synthesis factor produces a characteristic RAMP profile that exhibits consistency across a range of depletion levels. This facilitates the inference of affected steps and simplifies comparative analysis. We applied RAMP to examine how endonucleolytic cleavages of the mouse pre-rRNA transcript in the internal transcribed spacer 1 (ITS1) are affected by depletion of factors required for maturation of the small ribosomal subunit (Rcl1, Fcf1/Utp24, Utp23) and the large subunit (Pes1, Nog1). The data suggest that completion of early maturation in a subunit triggers its release from the common pre-rRNA transcript by stimulating cleavage at the proximal site in ITS1. We also find that splitting of pre-rRNA in the 3' region of ITS1 is prevalent in adult mouse tissues and quiescent cells, as it is in human cells. We propose a model for subunit separation during mammalian ribosome synthesis and discuss its implications for understanding pre-rRNA processing pathways.
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Affiliation(s)
- Minshi Wang
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Leonid Anikin
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Dimitri G Pestov
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA
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50
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mTOR regulates the nucleoplasmic diffusion of Xrn2 under conditions of heat stress. FEBS Lett 2014; 588:3454-60. [PMID: 25128458 DOI: 10.1016/j.febslet.2014.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/04/2014] [Accepted: 08/04/2014] [Indexed: 12/26/2022]
Abstract
Stress induces various responses, including translational suppression and tRNA degradation in mammals. Previously, we showed that heat stress induces degradation of initiator tRNA(Met) (iMet) through 5'-3' exoribonuclease Xrn1 and Xrn2, respectively. In addition, we found that rapamycin inhibits the degradation of iMet under heat stress conditions. Here, we report that the mammalian target of rapamycin (mTOR) regulates the diffusion of Xrn2 from the nucleolus to the nucleoplasm, facilitating the degradation of iMet under conditions of heat stress. Our results suggest a mechanism of translational suppression through mTOR-regulated iMet degradation in mammalian cells.
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