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Fasken MB, Leung SW, Cureton LA, Al-Awadi M, Al-Kindy A, van Hoof A, Khoshnevis S, Ghalei H, Al-Maawali A, Corbett AH. A Biallelic Variant of the RNA Exosome Gene, EXOSC4, Associated with Neurodevelopmental Defects Impairs RNA Exosome Function and Translation. J Biol Chem 2024:107571. [PMID: 39009343 DOI: 10.1016/j.jbc.2024.107571] [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: 12/21/2023] [Revised: 06/15/2024] [Accepted: 07/01/2024] [Indexed: 07/17/2024] Open
Abstract
The RNA exosome is an evolutionarily conserved complex required for both precise RNA processing and decay. Pathogenic variants in EXOSC genes, which encode structural subunits of this complex, are linked to several autosomal recessive disorders. Here, we describe a missense allele of the EXOSC4 gene that causes a collection of clinical features in two affected siblings. This missense variant (NM_019037.3: exon3:c.560T>C), changes a leucine residue within a conserved region of EXOSC4 to proline (p.Leu187Pro). The two affected individuals show prenatal growth restriction, failure to thrive, global developmental delay, intracerebral and basal ganglia calcifications, and kidney failure. Homozygosity for the damaging variant was identified by exome sequencing with Sanger sequencing to confirm segregation. To explore the functional consequences of this amino acid change, we modeled EXOSC4-L187P in the corresponding budding yeast protein, Rrp41 (Rrp41-L187P). Cells that express Rrp41-L187P as the sole copy of the essential Rrp41 protein show growth defects. Steady-state levels of both Rrp41-L187P and EXOSC4-L187P are decreased compared to controls and EXOSC4-L187P shows decreased co-purification with other RNA exosome subunits. RNA exosome target transcripts accumulate in rrp41-L187P cells, including the 7S precursor of 5.8S rRNA. Polysome profiles show a decrease in actively translating ribosomes in rrp41-L187P cells as compared to control cells with incorporation of 7S pre-rRNA into polysomes. This work adds EXOSC4 to the structural subunits of the RNA exosome that have been linked to human disease and defines foundational molecular defects that could contribute to the adverse phenotypes caused by EXOSC pathogenic variants.
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Affiliation(s)
- Milo B Fasken
- Department of Biology, Emory College of Arts and Sciences, Atlanta, GA USA 30322;.
| | - Sara W Leung
- Department of Biology, Emory College of Arts and Sciences, Atlanta, GA USA 30322
| | - Lauryn A Cureton
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA USA 30322;; Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322
| | - Maha Al-Awadi
- Sultan Qaboos Hospital, Ministry of Health, Salalah, Oman
| | - Adila Al-Kindy
- Department of Genetics, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA 77030
| | - Sohail Khoshnevis
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA USA 30322
| | - Homa Ghalei
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA USA 30322;.
| | - Almundher Al-Maawali
- Department of Genetics, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman;; Sultan Qaboos University Hospital, Sultan Qaboos University, Muscat, Oman.
| | - Anita H Corbett
- Department of Biology, Emory College of Arts and Sciences, Atlanta, GA USA 30322;.
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2
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Contreras X, Depierre D, Akkawi C, Srbic M, Helsmoortel M, Nogaret M, LeHars M, Salifou K, Heurteau A, Cuvier O, Kiernan R. PAPγ associates with PAXT nuclear exosome to control the abundance of PROMPT ncRNAs. Nat Commun 2023; 14:6745. [PMID: 37875486 PMCID: PMC10598014 DOI: 10.1038/s41467-023-42620-9] [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: 05/06/2022] [Accepted: 10/17/2023] [Indexed: 10/26/2023] Open
Abstract
Pervasive transcription of the human genome generates an abundance of RNAs that must be processed and degraded. The nuclear RNA exosome is the main RNA degradation machinery in the nucleus. However, nuclear exosome must be recruited to its substrates by targeting complexes, such as NEXT or PAXT. By proteomic analysis, we identify additional subunits of PAXT, including many orthologs of MTREC found in S. pombe. In particular, we show that polyA polymerase gamma (PAPγ) associates with PAXT. Genome-wide mapping of the binding sites of ZFC3H1, RBM27 and PAPγ shows that PAXT is recruited to the TSS of hundreds of genes. Loss of ZFC3H1 abolishes recruitment of PAXT subunits including PAPγ to TSSs and concomitantly increases the abundance of PROMPTs at the same sites. Moreover, PAPγ, as well as MTR4 and ZFC3H1, is implicated in the polyadenylation of PROMPTs. Our results thus provide key insights into the direct targeting of PROMPT ncRNAs by PAXT at their genomic sites.
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Affiliation(s)
- Xavier Contreras
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - David Depierre
- Center of Integrative Biology (CBI-CNRS), Molecular, Cellular and Developmental Biology (MCD Unit), University of Toulouse, 31000, Toulouse, France
| | - Charbel Akkawi
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Marina Srbic
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Marion Helsmoortel
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Maguelone Nogaret
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Matthieu LeHars
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Kader Salifou
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France
| | - Alexandre Heurteau
- Center of Integrative Biology (CBI-CNRS), Molecular, Cellular and Developmental Biology (MCD Unit), University of Toulouse, 31000, Toulouse, France
| | - Olivier Cuvier
- Center of Integrative Biology (CBI-CNRS), Molecular, Cellular and Developmental Biology (MCD Unit), University of Toulouse, 31000, Toulouse, France
| | - Rosemary Kiernan
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, Montpellier, France.
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3
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Sterrett MC, Cureton LA, Cohen LN, van Hoof A, Khoshnevis S, Fasken MB, Corbett AH, Ghalei H. Comparative analyses of disease-linked missense mutations in the RNA exosome modeled in budding yeast reveal distinct functional consequences in translation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.18.562946. [PMID: 37904946 PMCID: PMC10614903 DOI: 10.1101/2023.10.18.562946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
The RNA exosome is an evolutionarily conserved exoribonuclease complex that consists of a 3-subunit cap, a 6-subunit barrel-shaped core, and a catalytic base subunit. Missense mutations in genes encoding structural subunits of the RNA exosome cause a growing family of diseases with diverse pathologies, collectively termed RNA exosomopathies. The disease symptoms vary and can manifest as neurological defects or developmental disorders. The diversity of the RNA exosomopathy pathologies suggests that the different missense mutations in structural genes result in distinct in vivo consequences. To investigate these functional consequences and distinguish whether they are unique to each RNA exosomopathy mutation, we generated a collection of in vivo models using budding yeast by introducing pathogenic missense mutations in orthologous S. cerevisiae genes. We then performed a comparative RNA-seq analysis to assess broad transcriptomic changes in each mutant model. Three of the mutant models rrp4-G226D, rrp40-W195R and rrp46-L191H, which model mutations in the genes encoding structural subunits of the RNA exosome, EXOSC2, EXOSC3 and EXOSC5 showed the largest transcriptomic differences. Further analyses revealed shared increased transcripts enriched in translation or ribosomal RNA modification/processing pathways across the three mutant models. Studies of the impact of the mutations on translation revealed shared defects in ribosome biogenesis but distinct impacts on translation. Collectively, our results provide the first comparative analysis of several RNA exosomopathy mutant models and suggest that different RNA exosomopathy mutations result in in vivo consequences that are both unique and shared across each variant, providing more insight into the biology underlying each distinct pathology.
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Affiliation(s)
- Maria C. Sterrett
- Department of Biology, Emory University, Atlanta, Georgia, USA
- Biochemistry, Cell and Developmental Biology Graduate Program, Emory University, Atlanta, Georgia, USA
| | - Lauryn A. Cureton
- Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, Georgia, USA
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Lauren N. Cohen
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Sohail Khoshnevis
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Milo B. Fasken
- Department of Biology, Emory University, Atlanta, Georgia, USA
| | | | - Homa Ghalei
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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4
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Sterrett MC, Farchi D, Strassler SE, Boise LH, Fasken MB, Corbett AH. In vivo characterization of the critical interaction between the RNA exosome and the essential RNA helicase Mtr4 in Saccharomyces cerevisiae. G3 (BETHESDA, MD.) 2023; 13:jkad049. [PMID: 36861343 PMCID: PMC10411580 DOI: 10.1093/g3journal/jkad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/05/2023] [Accepted: 02/10/2023] [Indexed: 03/03/2023]
Abstract
The RNA exosome is a conserved molecular machine that processes/degrades numerous coding and non-coding RNAs. The 10-subunit complex is composed of three S1/KH cap subunits (human EXOSC2/3/1; yeast Rrp4/40/Csl4), a lower ring of six PH-like subunits (human EXOSC4/7/8/9/5/6; yeast Rrp41/42/43/45/46/Mtr3), and a singular 3'-5' exo/endonuclease DIS3/Rrp44. Recently, several disease-linked missense mutations have been identified in structural cap and core RNA exosome genes. In this study, we characterize a rare multiple myeloma patient missense mutation that was identified in the cap subunit gene EXOSC2. This missense mutation results in a single amino acid substitution, p.Met40Thr, in a highly conserved domain of EXOSC2. Structural studies suggest that this Met40 residue makes direct contact with the essential RNA helicase, MTR4, and may help stabilize the critical interaction between the RNA exosome complex and this cofactor. To assess this interaction in vivo, we utilized the Saccharomyces cerevisiae system and modeled the EXOSC2 patient mutation into the orthologous yeast gene RRP4, generating the variant rrp4-M68T. The rrp4-M68T cells show accumulation of certain RNA exosome target RNAs and show sensitivity to drugs that impact RNA processing. We also identified robust negative genetic interactions between rrp4-M68T and specific mtr4 mutants. A complementary biochemical approach revealed that Rrp4 M68T shows decreased interaction with Mtr4, consistent with these genetic results. This study suggests that the EXOSC2 mutation identified in a multiple myeloma patient impacts the function of the RNA exosome and provides functional insight into a critical interface between the RNA exosome and Mtr4.
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Affiliation(s)
- Maria C Sterrett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
- Biochemistry, Cell, and Developmental Biology Graduate Program, Emory University, Atlanta, GA 30322, USA
| | - Daniela Farchi
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Sarah E Strassler
- Biochemistry, Cell, and Developmental Biology Graduate Program, Emory University, Atlanta, GA 30322, USA
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | - Lawrence H Boise
- Department of Hematology and Medical Oncology, School of Medicine, Emory University, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Milo B Fasken
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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5
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Ibrahim I, Scriver T, Basalom SA. No, it is not mutually exclusive! A case report of a girl with two genetic diagnoses: Craniofrontonasal dysplasia and pontocerebellar hypoplasia type 1B. Clin Case Rep 2023; 11:e7332. [PMID: 37180334 PMCID: PMC10172455 DOI: 10.1002/ccr3.7332] [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: 03/05/2023] [Revised: 04/15/2023] [Accepted: 04/23/2023] [Indexed: 05/16/2023] Open
Abstract
Key Clinical Message Multiple genetic disorders can coexist in one patient. When the phenotype is not fully explained with one diagnosis, it is recommended to perform further genetic investigations in search for coexisting second diagnosis. Abstract Craniofrontonasal dysplasia (CFND) (MIM: 304110) is an X-linked dominant disorder that shows paradoxically greater severity in heterozygous females than in hemizygous males. It is caused by a pathogenic variant in EFNB1. Pontocerebellar hypoplasia type 1B (PCH1B) (MIM: 614678) is an extremely rare condition with over 100 individuals reported to date. It is caused by biallelic pathogenic variants in EXOSC3. This report presents the case of a girl who was diagnosed prenatally with CFND based on the findings on the prenatal imaging and the known diagnosis of CFND in her mother. She has severe global development delay that cannot be explained solely by the CFND diagnosis. Around the age of 2 years, she was diagnosed with PCH1B following whole exome sequencing (WES) testing. The objective of this study is to highlight the importance of pursuing genetic investigation if the available genetic diagnosis cannot fully explain the clinical picture. This is a case report of one patient and review of the literature. Informed consent was obtained from the parents. WES was performed by a private lab using next-generation sequencing (NGS), DNA was sequenced on the NovaSeq 6000 using 2 × 150 bp paired-end read. WES identified the following: homozygous pathogenic variant in EXOSC3: C.395A>C, p.ASp132Ala, maternally inherited, likely pathogenic duplication at Xq13.1 (includes EFNB1) and paternally inherited 16p11.2 duplication that is classified as a variant of uncertain significance. Perusing more extensive genetic testing like: WES is indicated if the current genetic diagnosis cannot fully explain the phenotype in a patient.
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Affiliation(s)
- Iman Ibrahim
- School of Health Studies, Elborn CollegeWestern UniversityLondonOntarioCanada
| | - Tara Scriver
- Division of Medical Genetics, Department of Pediatrics, Royal University HospitalUniversity of SaskatchewanSaskatoonSaskatchewanCanada
| | - Shuaa A. Basalom
- Division of Medical Genetics, Department of Pediatrics, Royal University HospitalUniversity of SaskatchewanSaskatoonSaskatchewanCanada
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6
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Bilge S, Mert GG, Hergüner Ö, Özcanyüz D, Bozdoğan ST, Kaya Ö, Havalı C. Clinical, radiological, and genetic variation in pontocerebellar hypoplasia disorder and our clinical experience. Ital J Pediatr 2022; 48:169. [PMID: 36076253 PMCID: PMC9461104 DOI: 10.1186/s13052-022-01349-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/16/2022] [Indexed: 11/16/2022] Open
Abstract
Pontocerebellar hypoplasia (PCH) constitutes a heterogeneous neurodegenerative/neurodevelopmental disorder of the pons and cerebellum with onset in the prenatal period. Our study aimed to present different clinical and radiological manifestations of our genetically diagnosed PCH patients. Method: Six patients were enrolled in this study from September 2018 to March 2021. All the clinical radiological and genetic investigations were done at Cukurova University Medical School. Results: Five children were diagnosed genetically and categorized under one of the types of PCH (type 10,7,11). Homozygous mutations in CLP1 In PCH type 10, TOE1 in PCH type 7, and TBC1D23 in PCH type 11 were respectively detected. Pateint with PCH type 11 and female patient with PCH type 7 could walk and speak few words. Male patient with PCH type 7 had disorder of sex development. Conclusion: According to our study, PCH is a rare neurodegenerative disease, although some types are static as PCH11 male gender and PCH7 female gender. Some clinical features are specific to a definite type. PCH7 express disorders of sex development most apparent in 46 XY. Some ethnic groups could express distinct subtypes. PCH10 is seen in the Turkish population. Radiological imaging is beneficial in pre-diagnosis; all the patients had different pons and cerebellar hypoplasia degrees. Genetic testing like whole exome sequencing -next-generation sequencing is essential in setting the definite diagnosis and determining the type/subtype of PCH.
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Affiliation(s)
- Serap Bilge
- Department of Pediatric Neurology, College of Medicine, Çukurova University, Adana, Turkey.
| | - Gülen Gül Mert
- Department of Pediatric Neurology, College of Medicine, Çukurova University, Adana, Turkey
| | - Özlem Hergüner
- Department of Pediatric Neurology, College of Medicine, Çukurova University, Adana, Turkey
| | - Duygu Özcanyüz
- Department of Pediatric Neurology, College of Medicine, Çukurova University, Adana, Turkey
| | - Sevcan Tuğ Bozdoğan
- Department of Medical Genetics, College of Medicine, Çukurova University, Adana, Turkey
| | - Ömer Kaya
- Department of Radiology, College of Medicine, Çukurova University, Adana, Turkey
| | - Cengiz Havalı
- Department of Pediatric Neurology, Health Sciences University Bursa High Specialization Training and Research Hospital, Bursa, Turkey
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7
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Sterrett MC, Enyenihi L, Leung SW, Hess L, Strassler SE, Farchi D, Lee RS, Withers ES, Kremsky I, Baker RE, Basrai MA, van Hoof A, Fasken MB, Corbett AH. A budding yeast model for human disease mutations in the EXOSC2 cap subunit of the RNA exosome complex. RNA (NEW YORK, N.Y.) 2021; 27:1046-1067. [PMID: 34162742 PMCID: PMC8370739 DOI: 10.1261/rna.078618.120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
RNA exosomopathies, a growing family of diseases, are linked to missense mutations in genes encoding structural subunits of the evolutionarily conserved, 10-subunit exoribonuclease complex, the RNA exosome. This complex consists of a three-subunit cap, a six-subunit, barrel-shaped core, and a catalytic base subunit. While a number of mutations in RNA exosome genes cause pontocerebellar hypoplasia, mutations in the cap subunit gene EXOSC2 cause an apparently distinct clinical presentation that has been defined as a novel syndrome SHRF (short stature, hearing loss, retinitis pigmentosa, and distinctive facies). We generated the first in vivo model of the SHRF pathogenic amino acid substitutions using budding yeast by modeling pathogenic EXOSC2 missense mutations (p.Gly30Val and p.Gly198Asp) in the orthologous S. cerevisiae gene RRP4 The resulting rrp4 mutant cells show defects in cell growth and RNA exosome function. Consistent with altered RNA exosome function, we detect significant transcriptomic changes in both coding and noncoding RNAs in rrp4-G226D cells that model EXOSC2 p.Gly198Asp, suggesting defects in nuclear surveillance. Biochemical and genetic analyses suggest that the Rrp4 G226D variant subunit shows impaired interactions with key RNA exosome cofactors that modulate the function of the complex. These results provide the first in vivo evidence that pathogenic missense mutations present in EXOSC2 impair the function of the RNA exosome. This study also sets the stage to compare exosomopathy models to understand how defects in RNA exosome function underlie distinct pathologies.
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Affiliation(s)
- Maria C Sterrett
- Biochemistry, Cell and Developmental Biology Graduate Program, Emory University, Atlanta, Georgia 30322, USA
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Liz Enyenihi
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Sara W Leung
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Laurie Hess
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Sarah E Strassler
- Biochemistry, Cell and Developmental Biology Graduate Program, Emory University, Atlanta, Georgia 30322, USA
- Department of Biochemistry, Emory University, Atlanta, Georgia 30322, USA
| | - Daniela Farchi
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Richard S Lee
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Elise S Withers
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Isaac Kremsky
- Loma Linda University School of Medicine, Loma Linda, California 92350, USA
| | - Richard E Baker
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Munira A Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Milo B Fasken
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
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8
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Slavotinek A, Misceo D, Htun S, Mathisen L, Frengen E, Foreman M, Hurtig JE, Enyenihi L, Sterrett MC, Leung SW, Schneidman-Duhovny D, Estrada-Veras J, Duncan JL, Haaxma CA, Kamsteeg EJ, Xia V, Beleford D, Si Y, Douglas G, Treidene HE, van Hoof A, Fasken MB, Corbett AH. Biallelic variants in the RNA exosome gene EXOSC5 are associated with developmental delays, short stature, cerebellar hypoplasia and motor weakness. Hum Mol Genet 2021; 29:2218-2239. [PMID: 32504085 DOI: 10.1093/hmg/ddaa108] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/10/2020] [Accepted: 05/28/2020] [Indexed: 12/15/2022] Open
Abstract
The RNA exosome is an essential ribonuclease complex required for processing and/or degradation of both coding and non-coding RNAs. We identified five patients with biallelic variants in EXOSC5, which encodes a structural subunit of the RNA exosome. The clinical features of these patients include failure to thrive, short stature, feeding difficulties, developmental delays that affect motor skills, hypotonia and esotropia. Brain MRI revealed cerebellar hypoplasia and ventriculomegaly. While we ascertained five patients, three patients with distinct variants of EXOSC5 were studied in detail. The first patient had a deletion involving exons 5-6 of EXOSC5 and a missense variant, p.Thr114Ile, that were inherited in trans, the second patient was homozygous for p.Leu206His and the third patient had paternal isodisomy for chromosome 19 and was homozygous for p.Met148Thr. The additional two patients ascertained are siblings who had an early frameshift mutation in EXOSC5 and the p.Thr114Ile missense variant that were inherited in trans. We employed three complementary approaches to explore the requirement for EXOSC5 in brain development and assess consequences of pathogenic EXOSC5 variants. Loss of function for exosc5 in zebrafish results in shortened and curved tails/bodies, reduced eye/head size and edema. We modeled pathogenic EXOSC5 variants in both budding yeast and mammalian cells. Some of these variants cause defects in RNA exosome function as well as altered interactions with other RNA exosome subunits. These findings expand the number of genes encoding RNA exosome subunits linked to human disease while also suggesting that disease mechanism varies depending on the specific pathogenic variant.
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Affiliation(s)
- Anne Slavotinek
- Department of Pediatrics, University of California, San Francisco, CA 94143, USA
| | - Doriana Misceo
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Oslo 0450, Norway
| | - Stephanie Htun
- Department of Pediatrics, University of California, San Francisco, CA 94143, USA
| | - Linda Mathisen
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Oslo 0450, Norway
| | - Eirik Frengen
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Oslo 0450, Norway
| | - Michelle Foreman
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, Houston, TX 77030, USA
| | - Jennifer E Hurtig
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, Houston, TX 77030, USA
| | - Liz Enyenihi
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | | | - Sara W Leung
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Dina Schneidman-Duhovny
- School of Computer Science and Engineering and the Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Juvianee Estrada-Veras
- Department of Pediatrics-Medical Genetics and Metabolism, Uniformed Services University/Walter Reed NMMC Bethesda, MD 20889, USA
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, CA 94143, USA
| | - Charlotte A Haaxma
- Department of Pediatric Neurology, Amalia Children's Hospital and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands
| | - Vivian Xia
- Department of Pediatrics, University of California, San Francisco, CA 94143, USA
| | - Daniah Beleford
- Department of Pediatrics, University of California, San Francisco, CA 94143, USA
| | - Yue Si
- GeneDx Inc., MD 20877, USA
| | | | - Hans Einar Treidene
- Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo 0450, Norway
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, Houston, TX 77030, USA
| | - Milo B Fasken
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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9
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Wang C, Liu Y, DeMario SM, Mandric I, Gonzalez-Figueroa C, Chanfreau GF. Rrp6 Moonlights in an RNA Exosome-Independent Manner to Promote Cell Survival and Gene Expression during Stress. Cell Rep 2021; 31:107754. [PMID: 32521279 PMCID: PMC7587046 DOI: 10.1016/j.celrep.2020.107754] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 11/21/2019] [Accepted: 05/19/2020] [Indexed: 12/13/2022] Open
Abstract
The nuclear RNA exosome is essential for RNA processing and degradation. Here, we show that the exosome nuclear-specific subunit Rrp6p promotes cell survival during heat stress through the cell wall integrity (CWI) pathway, independently of its catalytic activity or association with the core exosome. Rrp6p exhibits negative genetic interactions with the Slt2/Mpk1p or Paf1p elongation factors required for expression of CWI genes during stress. Overexpression of Rrp6p or of its catalytically inactive or exosome-independent mutants can partially rescue the growth defect of the mpk1Δ mutant and stimulates expression of the Mpk1 p target gene FKS2. The rrp6Δ and mpk1Δ mutants show similarities in deficient expression of CWI genes during heat shock, and overexpression of the CWI gene HSP150 can rescue the stress-induced lethality of the mpk1Δrp6Δ mutant. These results demonstrate that Rrp6p moonlights independently from the exosome to ensure proper expression of CWI genes and to promote cell survival during stress. Wang et al. show that Rrp6 functions with the Slt2/Mpk1 and Paf1 elongation factors for the proper expression of CWI genes during heat stress. The role of Rrp6p in promoting heat-stress-induced gene expression does not require Rrp6 catalytic activity or interaction with the nuclear RNA exosome.
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Affiliation(s)
- Charles Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yanru Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Samuel M DeMario
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Igor Mandric
- Department of Computer Science, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Carlos Gonzalez-Figueroa
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Guillaume F Chanfreau
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Wu G, Schmid M, Rib L, Polak P, Meola N, Sandelin A, Jensen TH. A Two-Layered Targeting Mechanism Underlies Nuclear RNA Sorting by the Human Exosome. Cell Rep 2021; 30:2387-2401.e5. [PMID: 32075771 DOI: 10.1016/j.celrep.2020.01.068] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/09/2019] [Accepted: 01/22/2020] [Indexed: 12/14/2022] Open
Abstract
Degradation of transcripts in human nuclei is primarily facilitated by the RNA exosome. To obtain substrate specificity, the exosome is aided by adaptors; in the nucleoplasm, those adaptors are the nuclear exosome-targeting (NEXT) complex and the poly(A) (pA) exosome-targeting (PAXT) connection. How these adaptors guide exosome targeting remains enigmatic. Employing high-resolution 3' end sequencing, we demonstrate that NEXT substrates arise from heterogenous and predominantly pA- 3' ends often covering kilobase-wide genomic regions. In contrast, PAXT targets harbor well-defined pA+ 3' ends defined by canonical pA site use. Irrespective of this clear division, NEXT and PAXT act redundantly in two ways: (1) regional redundancy, where the majority of exosome-targeted transcription units produce NEXT- and PAXT-sensitive RNA isoforms, and (2) isoform redundancy, where the PAXT connection ensures fail-safe decay of post-transcriptionally polyadenylated NEXT targets. In conjunction, this provides a two-layered targeting mechanism for efficient nuclear sorting of the human transcriptome.
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Affiliation(s)
- Guifen Wu
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark
| | - Manfred Schmid
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark
| | - Leonor Rib
- The Bioinformatics Centre, Department of Biology and Biotech Research and Innovation Centre, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
| | - Patrik Polak
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark
| | - Nicola Meola
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark
| | - Albin Sandelin
- The Bioinformatics Centre, Department of Biology and Biotech Research and Innovation Centre, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
| | - Torben Heick Jensen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark.
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11
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Fraga de Andrade I, Mehta C, Bresnick EH. Post-transcriptional control of cellular differentiation by the RNA exosome complex. Nucleic Acids Res 2020; 48:11913-11928. [PMID: 33119769 PMCID: PMC7708067 DOI: 10.1093/nar/gkaa883] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/21/2020] [Accepted: 09/30/2020] [Indexed: 12/12/2022] Open
Abstract
Given the complexity of intracellular RNA ensembles and vast phenotypic remodeling intrinsic to cellular differentiation, it is instructive to consider the role of RNA regulatory machinery in controlling differentiation. Dynamic post-transcriptional regulation of protein-coding and non-coding transcripts is vital for establishing and maintaining proteomes that enable or oppose differentiation. By contrast to extensively studied transcriptional mechanisms governing differentiation, many questions remain unanswered regarding the involvement of post-transcriptional mechanisms. Through its catalytic activity to selectively process or degrade RNAs, the RNA exosome complex dictates the levels of RNAs comprising multiple RNA classes, thereby regulating chromatin structure, gene expression and differentiation. Although the RNA exosome would be expected to control diverse biological processes, studies to elucidate its biological functions and how it integrates into, or functions in parallel with, cell type-specific transcriptional mechanisms are in their infancy. Mechanistic analyses have demonstrated that the RNA exosome confers expression of a differentiation regulatory receptor tyrosine kinase, downregulates the telomerase RNA component TERC, confers genomic stability and promotes DNA repair, which have considerable physiological and pathological implications. In this review, we address how a broadly operational RNA regulatory complex interfaces with cell type-specific machinery to control cellular differentiation.
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Affiliation(s)
- Isabela Fraga de Andrade
- Wisconsin Blood Cancer Research Institute, Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, 4009 WIMR, Madison, WI 53705, USA
| | - Charu Mehta
- Wisconsin Blood Cancer Research Institute, Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, 4009 WIMR, Madison, WI 53705, USA
| | - Emery H Bresnick
- Wisconsin Blood Cancer Research Institute, Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, 4009 WIMR, Madison, WI 53705, USA
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12
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Morton DJ, Jalloh B, Kim L, Kremsky I, Nair RJ, Nguyen KB, Rounds JC, Sterrett MC, Brown B, Le T, Karkare MC, McGaughey KD, Sheng S, Leung SW, Fasken MB, Moberg KH, Corbett AH. A Drosophila model of Pontocerebellar Hypoplasia reveals a critical role for the RNA exosome in neurons. PLoS Genet 2020; 16:e1008901. [PMID: 32645003 PMCID: PMC7373318 DOI: 10.1371/journal.pgen.1008901] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 07/21/2020] [Accepted: 06/01/2020] [Indexed: 12/27/2022] Open
Abstract
The RNA exosome is an evolutionarily-conserved ribonuclease complex critically important for precise processing and/or complete degradation of a variety of cellular RNAs. The recent discovery that mutations in genes encoding structural RNA exosome subunits cause tissue-specific diseases makes defining the role of this complex within specific tissues critically important. Mutations in the RNA exosome component 3 (EXOSC3) gene cause Pontocerebellar Hypoplasia Type 1b (PCH1b), an autosomal recessive neurologic disorder. The majority of disease-linked mutations are missense mutations that alter evolutionarily-conserved regions of EXOSC3. The tissue-specific defects caused by these amino acid changes in EXOSC3 are challenging to understand based on current models of RNA exosome function with only limited analysis of the complex in any multicellular model in vivo. The goal of this study is to provide insight into how mutations in EXOSC3 impact the function of the RNA exosome. To assess the tissue-specific roles and requirements for the Drosophila ortholog of EXOSC3 termed Rrp40, we utilized tissue-specific RNAi drivers. Depletion of Rrp40 in different tissues reveals a general requirement for Rrp40 in the development of many tissues including the brain, but also highlight an age-dependent requirement for Rrp40 in neurons. To assess the functional consequences of the specific amino acid substitutions in EXOSC3 that cause PCH1b, we used CRISPR/Cas9 gene editing technology to generate flies that model this RNA exosome-linked disease. These flies show reduced viability; however, the surviving animals exhibit a spectrum of behavioral and morphological phenotypes. RNA-seq analysis of these Drosophila Rrp40 mutants reveals increases in the steady-state levels of specific mRNAs and ncRNAs, some of which are central to neuronal function. In particular, Arc1 mRNA, which encodes a key regulator of synaptic plasticity, is increased in the Drosophila Rrp40 mutants. Taken together, this study defines a requirement for the RNA exosome in specific tissues/cell types and provides insight into how defects in RNA exosome function caused by specific amino acid substitutions that occur in PCH1b can contribute to neuronal dysfunction.
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Affiliation(s)
- Derrick J. Morton
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Binta Jalloh
- Genetics and Molecular Biology Graduate Program, Emory University, NE, Atlanta, Georgia, United States of America
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Lily Kim
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Isaac Kremsky
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Rishi J. Nair
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Khuong B. Nguyen
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - J. Christopher Rounds
- Genetics and Molecular Biology Graduate Program, Emory University, NE, Atlanta, Georgia, United States of America
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Maria C. Sterrett
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
- Biochemistry, Cell and Developmental Biology Graduate Program, Emory University, NE, Atlanta, Georgia, United States of America
| | - Brianna Brown
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Thalia Le
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Maya C. Karkare
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Kathryn D. McGaughey
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Shaoyi Sheng
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Sara W. Leung
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Milo B. Fasken
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Anita H. Corbett
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
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13
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de Amorim J, Slavotinek A, Fasken MB, Corbett AH, Morton DJ. Modeling Pathogenic Variants in the RNA Exosome. RNA & DISEASE 2020; 7:e1166. [PMID: 34676290 PMCID: PMC8528344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023] Open
Abstract
Exosomopathies are a collection of rare diseases caused by mutations in genes that encode structural subunits of the RNA exosome complex (EXOSC). The RNA exosome is critical for both processing and degrading many RNA targets. Mutations in individual RNA exosome subunit genes (termed EXOSC genes) are linked to a variety of distinct diseases. These exosomopathies do not arise from homozygous loss-of-function or large deletions in the EXOSC genes likely because some level of RNA exosome activity is essential for viability. Thus, all patients described so far have at least one allele with a missense mutation encoding an RNA exosome subunit with a single pathogenic amino acid change linked to disease. Understanding how these changes lead to the disparate clinical presentations that have been reported for this class of diseases necessitates investigation of how individual pathogenic missense variants alter RNA exosome function. Such studies will require access to patient samples, a challenge for these very rare diseases, coupled with modeling the patient variants. Here, we highlight five recent studies that model pathogenic variants in EXOSC3, EXOSC2, and EXOSC5.
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Affiliation(s)
- Julia de Amorim
- Department of Biology, Emory University,1510 Clifton Rd., NE RRC 1021, Atlanta, GA 30322, United States
- Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University,1510 Clifton Rd., NE RRC 1021, Atlanta, GA 30322, United States
| | - Anne Slavotinek
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA 94143, United States
| | - Milo B. Fasken
- Department of Biology, Emory University,1510 Clifton Rd., NE RRC 1021, Atlanta, GA 30322, United States
| | - Anita H. Corbett
- Department of Biology, Emory University,1510 Clifton Rd., NE RRC 1021, Atlanta, GA 30322, United States
| | - Derrick J. Morton
- The Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, United States
- Department of Biomedical Science, Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, CA 91101, United States
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14
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Bizzari S, Hamzeh AR, Mohamed M, Al-Ali MT, Bastaki F. Expanded PCH1D phenotype linked to EXOSC9 mutation. Eur J Med Genet 2020; 63:103622. [DOI: 10.1016/j.ejmg.2019.01.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/13/2019] [Accepted: 01/20/2019] [Indexed: 12/11/2022]
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15
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Abstract
The evolutionarily conserved RNA exosome is a multisubunit ribonuclease complex that processes and/or degrades numerous RNAs. Recently, mutations in genes encoding both structural and catalytic subunits of the RNA exosome have been linked to human disease. Mutations in the structural exosome gene EXOSC2 cause a distinct syndrome that includes retinitis pigmentosa, hearing loss, and mild intellectual disability. In contrast, mutations in the structural exosome genes EXOSC3 and EXOSC8 cause pontocerebellar hypoplasia type 1b (PCH1b) and type 1c (PCH1c), respectively, which are related autosomal recessive, neurodegenerative diseases. In addition, mutations in the structural exosome gene EXOSC9 cause a PCH-like disease with cerebellar atrophy and spinal motor neuronopathy. Finally, mutations in the catalytic exosome gene DIS3 have been linked to multiple myeloma, a neoplasm of plasma B cells. How mutations in these RNA exosome genes lead to distinct, tissue-specific diseases is not currently well understood. In this chapter, we examine the role of the RNA exosome complex in human disease and discuss the mechanisms by which mutations in different exosome subunit genes could impair RNA exosome function and give rise to diverse diseases.
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Affiliation(s)
- Milo B Fasken
- Department of Biology, RRC 1021, Emory University, Atlanta, GA, USA.
| | - Derrick J Morton
- Department of Biology, RRC 1021, Emory University, Atlanta, GA, USA
| | - Emily G Kuiper
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Stephanie K Jones
- Department of Biology, RRC 1021, Emory University, Atlanta, GA, USA
- Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA, USA
| | - Sara W Leung
- Department of Biology, RRC 1021, Emory University, Atlanta, GA, USA
| | - Anita H Corbett
- Department of Biology, RRC 1021, Emory University, Atlanta, GA, USA.
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16
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Le Duc D, Horn S, Jamra RA, Schaper J, Wieczorek D, Redler S. Novel EXOSC3 pathogenic variant results in a mild course of neurologic disease with cerebellum involvement. Eur J Med Genet 2019; 63:103649. [PMID: 30986545 DOI: 10.1016/j.ejmg.2019.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/21/2019] [Accepted: 04/04/2019] [Indexed: 10/27/2022]
Abstract
EXOSC3-related autosomal recessive neurodevelopmental disorders are rare entities with variable clinical course and prognosis. They are characterized by hypoplasia of cerebellar structures and pons, degeneration of the anterior horn cells and motor as well as neurocognitive impairment. Phenotypic expression is variable with an overall poor outcome. Current research suggests clear genotype-phenotype correlations among EXOSC3-pathogenic-variants carriers. Homozygosity for the EXOSC3 variant c.395A > C, p.(Asp132Ala) is proposed to lead to a rather mild phenotype compared to compound-heterozygous EXOSC3-pathogenic-variants carriers with lethal neurological disease in very early childhood. In this study, we report two siblings (21- and 8-year-old) affected by PCH1B with an unusual presentation. We identified compound heterozygosity for the well-established EXOSC3 variant c.395A > C, p.(Asp132Ala) and the novel variant c.572G > A, p.(Gly191Asp), expanding the genetic spectrum. Phenotypic presentation of the siblings was strikingly different from that of literature reports with a surprisingly mild disease manifestation and an unexpected intrafamilial variability. This study demonstrates the extensive clinical heterogeneity and the broad phenotypic spectrum associated with EXOSC3-associated disorders. Enlargement of sample sizes and reports of novel cases will be essential for the delineation of associated phenotypes.
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Affiliation(s)
- Diana Le Duc
- Institute of Human Genetics, University of Leipzig, Leipzig, Germany
| | - Susanne Horn
- Institute of Human Genetics, University of Leipzig, Leipzig, Germany
| | - Rami Abou Jamra
- Institute of Human Genetics, University of Leipzig, Leipzig, Germany
| | - Jörg Schaper
- Heinrich-Heine-University, Medical Faculty, Department of Diagnostic and Interventional Radiology, Düsseldorf, Germany
| | - Dagmar Wieczorek
- Heinrich-Heine-University, Medical Faculty, Institute of Human Genetics, Düsseldorf, Germany
| | - Silke Redler
- Heinrich-Heine-University, Medical Faculty, Institute of Human Genetics, Düsseldorf, Germany; Heinrich-Heine-University, Medical Faculty, Center of Rare Disorders, Düsseldorf, Germany.
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17
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François-Moutal L, Jahanbakhsh S, Nelson ADL, Ray D, Scott DD, Hennefarth MR, Moutal A, Perez-Miller S, Ambrose AJ, Al-Shamari A, Coursodon P, Meechoovet B, Reiman R, Lyons E, Beilstein M, Chapman E, Morris QD, Van Keuren-Jensen K, Hughes TR, Khanna R, Koehler C, Jen J, Gokhale V, Khanna M. A Chemical Biology Approach to Model Pontocerebellar Hypoplasia Type 1B (PCH1B). ACS Chem Biol 2018; 13:3000-3010. [PMID: 30141626 DOI: 10.1021/acschembio.8b00745] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Mutations of EXOSC3 have been linked to the rare neurological disorder known as Pontocerebellar Hypoplasia type 1B (PCH1B). EXOSC3 is one of three putative RNA-binding structural cap proteins that guide RNA into the RNA exosome, the cellular machinery that degrades RNA. Using RNAcompete, we identified a G-rich RNA motif binding to EXOSC3. Surface plasmon resonance (SPR) and microscale thermophoresis (MST) indicated an affinity in the low micromolar range of EXOSC3 for long and short G-rich RNA sequences. Although several PCH1B-causing mutations in EXOSC3 did not engage a specific RNA motif as shown by RNAcompete, they exhibited lower binding affinity to G-rich RNA as demonstrated by MST. To test the hypothesis that modification of the RNA-protein interface in EXOSC3 mutants may be phenocopied by small molecules, we performed an in-silico screen of 50 000 small molecules and used enzyme-linked immunosorbant assays (ELISAs) and MST to assess the ability of the molecules to inhibit RNA-binding by EXOSC3. We identified a small molecule, EXOSC3-RNA disrupting (ERD) compound 3 (ERD03), which ( i) bound specifically to EXOSC3 in saturation transfer difference nuclear magnetic resonance (STD-NMR), ( ii) disrupted the EXOSC3-RNA interaction in a concentration-dependent manner, and ( iii) produced a PCH1B-like phenotype with a 50% reduction in the cerebellum and an abnormally curved spine in zebrafish embryos. This compound also induced modification of zebrafish RNA expression levels similar to that observed with a morpholino against EXOSC3. To our knowledge, this is the first example of a small molecule obtained by rational design that models the abnormal developmental effects of a neurodegenerative disease in a whole organism.
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Affiliation(s)
- Liberty François-Moutal
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
- Center for Innovation in Brain Science, Tucson, Arizona 85721, United States
| | - Shahriyar Jahanbakhsh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Andrew D. L. Nelson
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721, United States
| | - Debashish Ray
- Donnelly Centre, University of Toronto, Toronto, Canada M5S 3E1
| | - David D. Scott
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
- Center for Innovation in Brain Science, Tucson, Arizona 85721, United States
| | - Matthew R. Hennefarth
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Aubin Moutal
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Samantha Perez-Miller
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
- Center for Innovation in Brain Science, Tucson, Arizona 85721, United States
| | - Andrew J. Ambrose
- Pharmacology and Toxicology, School of Pharmacy, University of Arizona, Tucson, Arizona 85724, United States
| | - Ahmed Al-Shamari
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Philippe Coursodon
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | | | - Rebecca Reiman
- Neurogenomics Division, TGen, Phoenix, Arizona 85004, United States
| | - Eric Lyons
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721, United States
| | - Mark Beilstein
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721, United States
| | - Eli Chapman
- Pharmacology and Toxicology, School of Pharmacy, University of Arizona, Tucson, Arizona 85724, United States
| | - Quaid D. Morris
- Donnelly Centre, University of Toronto, Toronto, Canada M5S 3E1
- Department of Molecular Genetics, University of Toronto, Toronto, Canada M5S 1A8
- Department of Computer Science, University of Toronto, Toronto, Canada M5S 2E4
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Canada M5S3G4
| | | | - Timothy R. Hughes
- Donnelly Centre, University of Toronto, Toronto, Canada M5S 3E1
- Department of Molecular Genetics, University of Toronto, Toronto, Canada M5S 1A8
| | - Rajesh Khanna
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
- Center for Innovation in Brain Science, Tucson, Arizona 85721, United States
| | - Carla Koehler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Joanna Jen
- Mount Sinai, New York, New York 10029, United States
| | - Vijay Gokhale
- Bio5 Institute, University of Arizona, Tucson, Arizona, United States
| | - May Khanna
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
- Center for Innovation in Brain Science, Tucson, Arizona 85721, United States
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18
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van Dijk T, Baas F, Barth PG, Poll-The BT. What's new in pontocerebellar hypoplasia? An update on genes and subtypes. Orphanet J Rare Dis 2018; 13:92. [PMID: 29903031 PMCID: PMC6003036 DOI: 10.1186/s13023-018-0826-2] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 05/16/2018] [Indexed: 12/25/2022] Open
Abstract
Background Pontocerebellar hypoplasia (PCH) describes a rare, heterogeneous group of neurodegenerative disorders mainly with a prenatal onset. Patients have severe hypoplasia or atrophy of cerebellum and pons, with variable involvement of supratentorial structures, motor and cognitive impairments. Based on distinct clinical features and genetic causes, current classification comprises 11 types of PCH. Main text In this review we describe the clinical, neuroradiological and genetic characteristics of the different PCH subtypes, summarize the differential diagnosis and reflect on potential disease mechanisms in PCH. Seventeen PCH-related genes are now listed in the OMIM database, most of them have a function in RNA processing or translation. It is unknown why defects in these apparently ubiquitous processes result in a brain-specific phenotype. Conclusions Many new PCH related genes and phenotypes have been described due to the appliance of next generation sequencing techniques. By including such a broad range of phenotypes, including non-degenerative and postnatal onset disorders, the current classification gives rise to confusion. Despite the discovery of new pathways involved in PCH, treatment is still symptomatic. However, correct diagnosis of PCH is important to provide suitable care and counseling regarding prognosis, and offer appropriate (prenatal) genetic testing to families.
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Affiliation(s)
- Tessa van Dijk
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands.,Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Frank Baas
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter G Barth
- Department of Pediatric Neurology, Academic Medical Center, Amsterdam, The Netherlands
| | - Bwee Tien Poll-The
- Department of Pediatric Neurology, Academic Medical Center, Amsterdam, The Netherlands.
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19
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Mpp6 Incorporation in the Nuclear Exosome Contributes to RNA Channeling through the Mtr4 Helicase. Cell Rep 2018; 20:2279-2286. [PMID: 28877463 PMCID: PMC5603729 DOI: 10.1016/j.celrep.2017.08.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/27/2017] [Accepted: 08/11/2017] [Indexed: 12/24/2022] Open
Abstract
The RNA-degrading exosome mediates the processing and decay of many cellular transcripts. In the yeast nucleus, the ubiquitous 10-subunit exosome core complex (Exo-9–Rrp44) functions with four conserved cofactors (Rrp6, Rrp47, Mtr4, and Mpp6). Biochemical and structural studies to date have shed insights into the mechanisms of the exosome core and its nuclear cofactors, with the exception of Mpp6. We report the 3.2-Å resolution crystal structure of a S. cerevisiae Exo-9–Mpp6 complex, revealing how linear motifs in the Mpp6 middle domain bind Rrp40 via evolutionary conserved residues. In particular, Mpp6 binds near a tryptophan residue of Rrp40 that is mutated in human patients suffering from pontocerebellar hypoplasia. Using biochemical assays, we show that Mpp6 is required for the ability of Mtr4 to extend the trajectory of an RNA entering the exosome core, suggesting that it promotes the channeling of substrates from the nuclear helicase to the processive RNase. Yeast Mpp6 is stably bound to the nuclear exosome core both in vivo and in vitro The Mpp6 middle domain binds the Rrp40 exosome subunit with conserved interactions Mpp6 enhances the ability of the Mtr4 helicase to channel RNA into the exosome core The pontocerebellar W238R mutation in human EXOSC3 affects the hMPP6-binding site
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Singh P, Saha U, Paira S, Das B. Nuclear mRNA Surveillance Mechanisms: Function and Links to Human Disease. J Mol Biol 2018; 430:1993-2013. [PMID: 29758258 DOI: 10.1016/j.jmb.2018.05.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/30/2018] [Accepted: 05/07/2018] [Indexed: 01/05/2023]
Abstract
Production of export-competent mRNAs involves transcription and a series of dynamic processing and modification events of pre-messenger RNAs in the nucleus. Mutations in the genes encoding the transcription and mRNP processing machinery and the complexities involved in the biogenesis events lead to the formation of aberrant messages. These faulty transcripts are promptly eliminated by the nuclear RNA exosome and its cofactors to safeguard the cells and organisms from genetic catastrophe. Mutations in the components of the core nuclear exosome and its cofactors lead to the tissue-specific dysfunction of exosomal activities, which are linked to diverse human diseases and disorders. In this article, we examine the structure and function of both the yeast and human RNA exosome complex and its cofactors, discuss the nature of the various altered amino acid residues implicated in these diseases with the speculative mechanisms of the mutation-induced disorders and project the frontier and prospective avenues of the future research in this field.
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Affiliation(s)
- Pragyan Singh
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Upasana Saha
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Sunirmal Paira
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Biswadip Das
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India.
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Burns DT, Donkervoort S, Müller JS, Knierim E, Bharucha-Goebel D, Faqeih EA, Bell SK, AlFaifi AY, Monies D, Millan F, Retterer K, Dyack S, MacKay S, Morales-Gonzalez S, Giunta M, Munro B, Hudson G, Scavina M, Baker L, Massini TC, Lek M, Hu Y, Ezzo D, AlKuraya FS, Kang PB, Griffin H, Foley AR, Schuelke M, Horvath R, Bönnemann CG. Variants in EXOSC9 Disrupt the RNA Exosome and Result in Cerebellar Atrophy with Spinal Motor Neuronopathy. Am J Hum Genet 2018; 102:858-873. [PMID: 29727687 PMCID: PMC5986733 DOI: 10.1016/j.ajhg.2018.03.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/06/2018] [Indexed: 12/30/2022] Open
Abstract
The exosome is a conserved multi-protein complex that is essential for correct RNA processing. Recessive variants in exosome components EXOSC3, EXOSC8, and RBM7 cause various constellations of pontocerebellar hypoplasia (PCH), spinal muscular atrophy (SMA), and central nervous system demyelination. Here, we report on four unrelated affected individuals with recessive variants in EXOSC9 and the effect of the variants on the function of the RNA exosome in vitro in affected individuals' fibroblasts and skeletal muscle and in vivo in zebrafish. The clinical presentation was severe, early-onset, progressive SMA-like motor neuronopathy, cerebellar atrophy, and in one affected individual, congenital fractures of the long bones. Three affected individuals of different ethnicity carried the homozygous c.41T>C (p.Leu14Pro) variant, whereas one affected individual was compound heterozygous for c.41T>C (p.Leu14Pro) and c.481C>T (p.Arg161∗). We detected reduced EXOSC9 in fibroblasts and skeletal muscle and observed a reduction of the whole multi-subunit exosome complex on blue-native polyacrylamide gel electrophoresis. RNA sequencing of fibroblasts and skeletal muscle detected significant >2-fold changes in genes involved in neuronal development and cerebellar and motor neuron degeneration, demonstrating the widespread effect of the variants. Morpholino oligonucleotide knockdown and CRISPR/Cas9-mediated mutagenesis of exosc9 in zebrafish recapitulated aspects of the human phenotype, as they have in other zebrafish models of exosomal disease. Specifically, portions of the cerebellum and hindbrain were absent, and motor neurons failed to develop and migrate properly. In summary, we show that variants in EXOSC9 result in a neurological syndrome combining cerebellar atrophy and spinal motoneuronopathy, thus expanding the list of human exosomopathies.
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Morton DJ, Kuiper EG, Jones SK, Leung SW, Corbett AH, Fasken MB. The RNA exosome and RNA exosome-linked disease. RNA (NEW YORK, N.Y.) 2018; 24:127-142. [PMID: 29093021 PMCID: PMC5769741 DOI: 10.1261/rna.064626.117] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The RNA exosome is an evolutionarily conserved, ribonuclease complex that is critical for both processing and degradation of a variety of RNAs. Cofactors that associate with the RNA exosome likely dictate substrate specificity for this complex. Recently, mutations in genes encoding both structural subunits of the RNA exosome and its cofactors have been linked to human disease. Mutations in the RNA exosome genes EXOSC3 and EXOSC8 cause pontocerebellar hypoplasia type 1b (PCH1b) and type 1c (PCH1c), respectively, which are similar autosomal-recessive, neurodegenerative diseases. Mutations in the RNA exosome gene EXOSC2 cause a distinct syndrome with various tissue-specific phenotypes including retinitis pigmentosa and mild intellectual disability. Mutations in genes that encode RNA exosome cofactors also cause tissue-specific diseases with complex phenotypes. How mutations in these genes give rise to distinct, tissue-specific diseases is not clear. In this review, we discuss the role of the RNA exosome complex and its cofactors in human disease, consider the amino acid changes that have been implicated in disease, and speculate on the mechanisms by which exosome gene mutations could underlie dysfunction and disease.
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Affiliation(s)
- Derrick J Morton
- Department of Biology, Emory University, NE, Atlanta, Georgia 30322, USA
| | - Emily G Kuiper
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Stephanie K Jones
- Department of Biology, Emory University, NE, Atlanta, Georgia 30322, USA
- Genetics and Molecular Biology Graduate Program, Emory University, NE, Atlanta, Georgia 30322, USA
| | - Sara W Leung
- Department of Biology, Emory University, NE, Atlanta, Georgia 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, NE, Atlanta, Georgia 30322, USA
| | - Milo B Fasken
- Department of Biology, Emory University, NE, Atlanta, Georgia 30322, USA
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Wasmuth EV, Zinder JC, Zattas D, Das M, Lima CD. Structure and reconstitution of yeast Mpp6-nuclear exosome complexes reveals that Mpp6 stimulates RNA decay and recruits the Mtr4 helicase. eLife 2017; 6. [PMID: 28742025 PMCID: PMC5553935 DOI: 10.7554/elife.29062] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 07/21/2017] [Indexed: 11/20/2022] Open
Abstract
Nuclear RNA exosomes catalyze a range of RNA processing and decay activities that are coordinated in part by cofactors, including Mpp6, Rrp47, and the Mtr4 RNA helicase. Mpp6 interacts with the nine-subunit exosome core, while Rrp47 stabilizes the exoribonuclease Rrp6 and recruits Mtr4, but it is less clear if these cofactors work together. Using biochemistry with Saccharomyces cerevisiae proteins, we show that Rrp47 and Mpp6 stimulate exosome-mediated RNA decay, albeit with unique dependencies on elements within the nuclear exosome. Mpp6-exosomes can recruit Mtr4, while Mpp6 and Rrp47 each contribute to Mtr4-dependent RNA decay, with maximal Mtr4-dependent decay observed with both cofactors. The 3.3 Å structure of a twelve-subunit nuclear Mpp6 exosome bound to RNA shows the central region of Mpp6 bound to the exosome core, positioning its Mtr4 recruitment domain next to Rrp6 and the exosome central channel. Genetic analysis reveals interactions that are largely consistent with our model. DOI:http://dx.doi.org/10.7554/eLife.29062.001
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Affiliation(s)
- Elizabeth V Wasmuth
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - John C Zinder
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States.,Tri-Institutional Training Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Dimitrios Zattas
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Mom Das
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Christopher D Lima
- Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States.,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, United States
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Gillespie A, Gabunilas J, Jen JC, Chanfreau GF. Mutations of EXOSC3/Rrp40p associated with neurological diseases impact ribosomal RNA processing functions of the exosome in S. cerevisiae. RNA (NEW YORK, N.Y.) 2017; 23:466-472. [PMID: 28053271 PMCID: PMC5340910 DOI: 10.1261/rna.060004.116] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 12/22/2016] [Indexed: 05/29/2023]
Abstract
The RNA exosome is a conserved multiprotein complex that achieves a large number of processive and degradative functions in eukaryotic cells. Recently, mutations have been mapped to the gene encoding one of the subunits of the exosome, EXOSC3 (yeast Rrp40p), which results in pontocerebellar hypoplasia with motor neuron degeneration in human patients. However, the molecular impact of these mutations in the pathology of these diseases is not well understood. To investigate the molecular consequences of mutations in EXOSC3 that lead to neurological diseases, we analyzed the effect of three of the mutations that affect conserved residues of EXOSC3/Rrp40p (G31A, G191C, and W238R; G8A, G148C, and W195R, respectively, in human and yeast) in S. cerevisiae We show that the severity of the phenotypes of these mutations in yeast correlate with that of the disease in human patients, with the W195R mutant showing the strongest growth and RNA processing phenotypes. Furthermore, we show that these mutations affect more severely pre-ribosomal RNA processing functions of the exosome rather than other nuclear processing or surveillance functions. These results suggest that delayed or defective pre-rRNA processing might be the primary defect responsible for the pathologies detected in patients with mutations affecting EXOSC3 function in residues conserved throughout eukaryotes.
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Affiliation(s)
- Abby Gillespie
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, California 90095-1569, USA
| | - Jason Gabunilas
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, California 90095-1569, USA
| | - Joanna C Jen
- Department of Neurology, University of California, Los Angeles, California 90095-1763, USA
- Department of Neurobiology, University of California, Los Angeles, California 90095-1763, USA
| | - Guillaume F Chanfreau
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, California 90095-1569, USA
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