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Alexander KA, Yu R, Skuli N, Coffey NJ, Nguyen S, Faunce C, Huang H, Dardani IP, Good AL, Lim J, Li C, Biddle N, Joyce EF, Raj A, Lee D, Keith B, Simon MC, Berger SL. Nuclear speckles regulate HIF-2α programs and correlate with patient survival in kidney cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.14.557228. [PMID: 37745397 PMCID: PMC10515914 DOI: 10.1101/2023.09.14.557228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Nuclear speckles are membrane-less bodies within the cell nucleus enriched in RNA biogenesis, processing, and export factors. In this study we investigated speckle phenotype variation in human cancer, finding a reproducible speckle signature, based on RNA expression of speckle-resident proteins, across >20 cancer types. Of these, clear cell renal cell carcinoma (ccRCC) exhibited a clear correlation between the presence of this speckle expression signature, imaging-based speckle phenotype, and clinical outcomes. ccRCC is typified by hyperactivation of the HIF-2α transcription factor, and we demonstrate here that HIF-2α drives physical association of a select subset of its target genes with nuclear speckles. Disruption of HIF-2α-driven speckle association via deletion of its speckle targeting motifs (STMs)-defined in this study-led to defective induction of speckle-associating HIF-2α target genes without impacting non-speckle-associating HIF-2α target genes. We further identify the RNA export complex, TREX, as being specifically altered in speckle signature, and knockdown of key TREX component, ALYREF, also compromises speckle-associated gene expression. By integrating tissue culture functional studies with tumor genomic and imaging analysis, we show that HIF-2α gene regulatory programs are impacted by specific manipulation of speckle phenotype and by abrogation of speckle targeting abilities of HIF-2α. These findings suggest that, in ccRCC, a key biological function of nuclear speckles is to modulate expression of a specific subset of HIF-2α-regulated target genes that, in turn, influence patient outcomes. We also identify STMs in other transcription factors, suggesting that DNA-speckle targeting may be a general mechanism of gene regulation.
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Affiliation(s)
- Katherine A. Alexander
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ruofan Yu
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Nicolas Skuli
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
- Stem Cell and Xenograft Core, Department of Medicine – Division of Hematology and Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nathan J. Coffey
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Son Nguyen
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine Faunce
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Hua Huang
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ian P. Dardani
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Austin L. Good
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Joan Lim
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Catherine Li
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Nicholas Biddle
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Eric F. Joyce
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Arjun Raj
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel Lee
- Division of Urology, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA 19104, USA
| | - Brian Keith
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - M. Celeste Simon
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shelley L. Berger
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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Enders L, Siklos M, Borggräfe J, Gaussmann S, Koren A, Malik M, Tomek T, Schuster M, Reiniš J, Hahn E, Rukavina A, Reicher A, Casteels T, Bock C, Winter GE, Hannich JT, Sattler M, Kubicek S. Pharmacological perturbation of the phase-separating protein SMNDC1. Nat Commun 2023; 14:4504. [PMID: 37587144 PMCID: PMC10432564 DOI: 10.1038/s41467-023-40124-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 07/13/2023] [Indexed: 08/18/2023] Open
Abstract
SMNDC1 is a Tudor domain protein that recognizes di-methylated arginines and controls gene expression as an essential splicing factor. Here, we study the specific contributions of the SMNDC1 Tudor domain to protein-protein interactions, subcellular localization, and molecular function. To perturb the protein function in cells, we develop small molecule inhibitors targeting the dimethylarginine binding pocket of the SMNDC1 Tudor domain. We find that SMNDC1 localizes to phase-separated membraneless organelles that partially overlap with nuclear speckles. This condensation behavior is driven by the unstructured C-terminal region of SMNDC1, depends on RNA interaction and can be recapitulated in vitro. Inhibitors of the protein's Tudor domain drastically alter protein-protein interactions and subcellular localization, causing splicing changes for SMNDC1-dependent genes. These compounds will enable further pharmacological studies on the role of SMNDC1 in the regulation of nuclear condensates, gene regulation and cell identity.
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Affiliation(s)
- Lennart Enders
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Marton Siklos
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Jan Borggräfe
- Helmholtz Munich, Molecular Targets and Therapeutics Center, Institute of Structural Biology, Neuherberg, 85764, München, Germany
- Technical University of Munich, TUM School of Natural Sciences, Department of Bioscience, Bavarian NMR Center, Garching, 85748, München, Germany
| | - Stefan Gaussmann
- Helmholtz Munich, Molecular Targets and Therapeutics Center, Institute of Structural Biology, Neuherberg, 85764, München, Germany
- Technical University of Munich, TUM School of Natural Sciences, Department of Bioscience, Bavarian NMR Center, Garching, 85748, München, Germany
| | - Anna Koren
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Monika Malik
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Tatjana Tomek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Michael Schuster
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Jiří Reiniš
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Elisa Hahn
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Andrea Rukavina
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Andreas Reicher
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Tamara Casteels
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
- Sloan Kettering Institute, 1275 York Avenue, New York, NY, 10065, USA
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
- Medical University of Vienna, Institute of Artificial Intelligence, Center for Medical Data Science, Währinger Straße 25a, 1090, Vienna, Austria
| | - Georg E Winter
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - J Thomas Hannich
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - Michael Sattler
- Helmholtz Munich, Molecular Targets and Therapeutics Center, Institute of Structural Biology, Neuherberg, 85764, München, Germany
- Technical University of Munich, TUM School of Natural Sciences, Department of Bioscience, Bavarian NMR Center, Garching, 85748, München, Germany
| | - Stefan Kubicek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria.
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Zhang T, Xu L, Zhu H, Ying Y, Ding J, Ding H, Shi X, He Y, Jin X, Xia G. Familial and genetic association with neurodevelopmental disorders caused by a heterozygous variant in the SRRM2 gene. Front Endocrinol (Lausanne) 2023; 14:1240168. [PMID: 37621647 PMCID: PMC10445754 DOI: 10.3389/fendo.2023.1240168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 07/13/2023] [Indexed: 08/26/2023] Open
Abstract
Background Neurodevelopmental disorders (NDDs) are a class of disorders affecting brain development and function, characterized by an inability to reach cognitive, emotional, and motor developmental milestones. The pathology of NDDs is complex. A recent study found that variants in the SRRM2 gene cause NDDs. However, genetic conditions play the most important role in the etiology of NDD. The genetic causes of NDD are extremely heterogeneous, leading to certain challenges in clinical diagnosis. Methods A pregnant woman with congenital intelligence disorder came to our hospital for genetic diagnosis to predict the status of her fetus. Her mother and a brother also suffer from congenital intelligence disorder. She has a daughter with speech delay. Whole exome sequencing was used to identify a mutation (c.1415C>G) in the SRRM2 gene of this family that resulted in a change in the 472nd amino acid residue of the SRRM2 protein from serine to terminated. Conclusion We report a family with an autosomal dominant genetic disorder caused by variants in the SRRM2 gene causing NDDs. Prenatal diagnosis can help patients with this genetic disorder to have healthy offspring.
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Affiliation(s)
- Tao Zhang
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Lei Xu
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
- Shaoxing University, Shaoxing, Zhejiang, China
| | - Hongdan Zhu
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Yuyi Ying
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Jinlong Ding
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Haigang Ding
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Xiaoliang Shi
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Yao He
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
| | - Xin Jin
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
- Shaoxing University, Shaoxing, Zhejiang, China
| | - Guiyu Xia
- Shaoxing Maternity and Child Health Care Hospital, Shaoxing, Zhejiang, China
- Obstetrics and Gynecology Hospital of Shaoxing University, Shaoxing, Zhejiang, China
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Rochín-Hernández LJ, Jiménez-Acosta MA, Ramírez-Reyes L, Figueroa-Corona MDP, Sánchez-González VJ, Orozco-Barajas M, Meraz-Ríos MA. The Proteome Profile of Olfactory Ecto-Mesenchymal Stem Cells-Derived from Patients with Familial Alzheimer's Disease Reveals New Insights for AD Study. Int J Mol Sci 2023; 24:12606. [PMID: 37628788 PMCID: PMC10454072 DOI: 10.3390/ijms241612606] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Alzheimer's disease (AD), the most common neurodegenerative disease and the first cause of dementia worldwide, has no effective treatment, and its pathological mechanisms are not yet fully understood. We conducted this study to explore the proteomic differences associated with Familial Alzheimer's Disease (FAD) in olfactory ecto-mesenchymal stem cells (MSCs) derived from PSEN1 (A431E) mutation carriers compared with healthy donors paired by age and gender through two label-free liquid chromatography-mass spectrometry approaches. The first analysis compared carrier 1 (patient with symptoms, P1) and its control (healthy donor, C1), and the second compared carrier 2 (patient with pre-symptoms, P2) with its respective control cells (C2) to evaluate whether the protein alterations presented in the symptomatic carrier were also present in the pre-symptom stages. Finally, we analyzed the differentially expressed proteins (DEPs) for biological and functional enrichment. These proteins showed impaired expression in a stage-dependent manner and are involved in energy metabolism, vesicle transport, actin cytoskeleton, cell proliferation, and proteostasis pathways, in line with previous AD reports. Our study is the first to conduct a proteomic analysis of MSCs from the Jalisco FAD patients in two stages of the disease (symptomatic and presymptomatic), showing these cells as a new and excellent in vitro model for future AD studies.
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Affiliation(s)
- Lory J. Rochín-Hernández
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Instituto Politécnico Nacional 2508, Ciudad de México 07360, Mexico; (L.J.R.-H.); (M.A.J.-A.); (M.d.P.F.-C.)
| | - Miguel A. Jiménez-Acosta
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Instituto Politécnico Nacional 2508, Ciudad de México 07360, Mexico; (L.J.R.-H.); (M.A.J.-A.); (M.d.P.F.-C.)
| | - Lorena Ramírez-Reyes
- Unidad de Genómica, Proteómica y Metabolómica, Laboratorio Nacional de Servicios Experimentales (LaNSE), Centro de Investigación y de Estudios Avanzados, Ciudad de México 07360, Mexico;
| | - María del Pilar Figueroa-Corona
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Instituto Politécnico Nacional 2508, Ciudad de México 07360, Mexico; (L.J.R.-H.); (M.A.J.-A.); (M.d.P.F.-C.)
| | - Víctor J. Sánchez-González
- Centro Universitario de Los Altos, Universidad de Guadalajara, Tepatitlán de Morelos 47620, Mexico; (V.J.S.-G.); (M.O.-B.)
| | - Maribel Orozco-Barajas
- Centro Universitario de Los Altos, Universidad de Guadalajara, Tepatitlán de Morelos 47620, Mexico; (V.J.S.-G.); (M.O.-B.)
| | - Marco A. Meraz-Ríos
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Instituto Politécnico Nacional 2508, Ciudad de México 07360, Mexico; (L.J.R.-H.); (M.A.J.-A.); (M.d.P.F.-C.)
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55
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Farsi Z, Sheng M. Molecular mechanisms of schizophrenia: Insights from human genetics. Curr Opin Neurobiol 2023; 81:102731. [PMID: 37245257 DOI: 10.1016/j.conb.2023.102731] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/28/2023] [Accepted: 05/01/2023] [Indexed: 05/30/2023]
Abstract
Schizophrenia is a debilitating psychiatric disorder that affects millions of people worldwide; however, its etiology is poorly understood at the molecular and neurobiological levels. A particularly important advance in recent years is the discovery of rare genetic variants associated with a greatly increased risk of developing schizophrenia. These primarily loss-of-function variants are found in genes that overlap with those implicated by common variants and are involved in the regulation of glutamate signaling, synaptic function, DNA transcription, and chromatin remodeling. Animal models harboring mutations in these large-effect schizophrenia risk genes show promise in providing additional insights into the molecular mechanisms of the disease.
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Affiliation(s)
- Zohreh Farsi
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Morgan Sheng
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
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56
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Kases K, Schubert E, Hajikhezri Z, Larsson M, Devi P, Darweesh M, Andersson L, Akusjärvi G, Punga T, Younis S. The RNA-binding protein ZC3H11A interacts with the nuclear poly(A)-binding protein PABPN1 and alters polyadenylation of viral transcripts. J Biol Chem 2023; 299:104959. [PMID: 37356722 PMCID: PMC10371797 DOI: 10.1016/j.jbc.2023.104959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 06/09/2023] [Accepted: 06/14/2023] [Indexed: 06/27/2023] Open
Abstract
Nuclear mRNA metabolism is regulated by multiple proteins, which either directly bind to RNA or form multiprotein complexes. The RNA-binding protein ZC3H11A is involved in nuclear mRNA export, NF-κB signaling, and is essential during mouse embryo development. Furthermore, previous studies have shown that ZC3H11A is important for nuclear-replicating viruses. However, detailed biochemical characterization of the ZC3H11A protein has been lacking. In this study, we established the ZC3H11A protein interactome in human and mouse cells. We demonstrate that the nuclear poly(A)-binding protein PABPN1 interacts specifically with the ZC3H11A protein and controls ZC3H11A localization into nuclear speckles. We report that ZC3H11A specifically interacts with the human adenovirus type 5 (HAdV-5) capsid mRNA in a PABPN1-dependent manner. Notably, ZC3H11A uses the same zinc finger motifs to interact with PABPN1 and viral mRNA. Further, we demonstrate that the lack of ZC3H11A alters the polyadenylation of HAdV-5 capsid mRNA. Taken together, our results suggest that the ZC3H11A protein may act as a novel regulator of polyadenylation of nuclear mRNA.
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Affiliation(s)
- Katharina Kases
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Erik Schubert
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Zamaneh Hajikhezri
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Mårten Larsson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Priya Devi
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Mahmoud Darweesh
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden; Department of Microbiology and Immunology, Al-Azhr University, Assiut, Egypt
| | - Leif Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Göran Akusjärvi
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Tanel Punga
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Shady Younis
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden; Division of Immunology and Rheumatology, Stanford University, Stanford, California, USA.
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57
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Hoboth P, Sztacho M, Quaas A, Akgül B, Hozák P. Quantitative super-resolution microscopy reveals the differences in the nanoscale distribution of nuclear phosphatidylinositol 4,5-bisphosphate in human healthy skin and skin warts. Front Cell Dev Biol 2023; 11:1217637. [PMID: 37484912 PMCID: PMC10361526 DOI: 10.3389/fcell.2023.1217637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/22/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction: Imaging of human clinical formalin-fixed paraffin-embedded (FFPE) tissue sections provides insights into healthy and diseased states and therefore represents a valuable resource for basic research, as well as for diagnostic and clinical purposes. However, conventional light microscopy does not allow to observe the molecular details of tissue and cell architecture due to the diffraction limit of light. Super-resolution microscopy overcomes this limitation and provides access to the nanoscale details of tissue and cell organization. Methods: Here, we used quantitative multicolor stimulated emission depletion (STED) nanoscopy to study the nanoscale distribution of the nuclear phosphatidylinositol 4,5-bisphosphate (nPI(4,5)P2) with respect to the nuclear speckles (NS) marker SON. Results: Increased nPI(4,5)P2 signals were previously linked to human papillomavirus (HPV)-mediated carcinogenesis, while NS-associated PI(4,5)P2 represents the largest pool of nPI(4,5)P2 visualized by staining and microscopy. The implementation of multicolor STED nanoscopy in human clinical FFPE skin and wart sections allowed us to provide here the quantitative evidence for higher levels of NS-associated PI(4,5)P2 in HPV-induced warts compared to control skin. Discussion: These data expand the previous reports of HPV-induced increase of nPI(4,5)P2 levels and reveal for the first time the functional, tissue-specific localization of nPI(4,5)P2 within NS in clinically relevant samples. Moreover, our approach is widely applicable to other human clinical FFPE tissues as an informative addition to the classical histochemistry.
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Affiliation(s)
- Peter Hoboth
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Martin Sztacho
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Alexander Quaas
- Institute of Pathology, Medical Faculty and University Hospital Cologne, Cologne, Germany
| | - Baki Akgül
- Institute of Virology, University of Cologne, Medical Faculty and University Hospital Cologne, Cologne, Germany
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
- Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
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58
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Kow RL, Black AH, Henderson BP, Kraemer BC. Sut-6/NIPP1 modulates tau toxicity. Hum Mol Genet 2023; 32:2292-2306. [PMID: 37000013 PMCID: PMC10321383 DOI: 10.1093/hmg/ddad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/04/2023] [Accepted: 03/27/2023] [Indexed: 04/01/2023] Open
Abstract
Neurodegenerative diseases exhibiting the pathological accumulation of tau such as Alzheimer's disease and related disorders still have no disease-modifying treatments and the molecular mechanisms of neurodegeneration remain unclear. To discover additional suppressor of tauopathy (sut) genes that mediate or modulate the toxicity of pathological tau, we performed a classical genetic screen using a tau transgenic Caenorhabditis elegans model. From this screen, we identified the suppressing mutation W292X in sut-6, the C. elegans homolog of human NIPP1, which truncates the C-terminal RNA-binding domain. Using CRISPR-based genome editing approaches, we generated null and additional C-terminally truncated alleles in sut-6 and found that loss of sut-6 or sut-6(W292X) suppresses tau-induced behavioral locomotor deficits, tau protein accumulation and neuron loss. The sut-6(W292X) mutation showed stronger and semi-dominant suppression of tau toxicity while sut-6 deletion acted recessively. Neuronal overexpression of SUT-6 protein did not significantly alter tau toxicity, but neuronal overexpression of SUT-6 W292X mutant protein reduced tau-mediated deficits. Epistasis studies showed tauopathy suppression by sut-6 occurs independent of other known nuclear speckle-localized suppressors of tau such as sut-2, aly-1/aly-3 and spop-1. In summary, we have shown that sut-6/NIPP1 modulates tau toxicity and found a dominant mutation in the RNA-binding domain of sut-6 which strongly suppresses tau toxicity. This suggests that altering RNA-related functions of SUT-6/NIPP1 instead of complete loss of SUT-6/NIPP1 will provide the strongest suppression of tau.
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Affiliation(s)
- R L Kow
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA 98104, USA
| | - A H Black
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
| | - B P Henderson
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
| | - B C Kraemer
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA 98104, USA
- Department of Psychiatry and Behavioral Sciences
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
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59
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Wakao S, Saitoh N, Awazu A. Mathematical model of structural changes in nuclear speckle. Biophys Physicobiol 2023; 20:e200020. [PMID: 38496241 PMCID: PMC10941963 DOI: 10.2142/biophysico.bppb-v20.0020] [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: 01/23/2023] [Accepted: 04/26/2023] [Indexed: 03/19/2024] Open
Abstract
Nuclear speckles are nuclear bodies consisting of populations of small and irregularly shaped droplet-like molecular condensates that contain various splicing factors. Recent experiments have revealed the following structural features of nuclear speckles: (I) Each molecular condensate contains SON and SRRM2 proteins, and MALAT1 non-coding RNA surrounds these condensates; (II) During normal interphase of the cell cycle in multicellular organisms, these condensates are broadly distributed throughout the nucleus. In contrast, when cell transcription is suppressed, the condensates fuse and form strongly condensed spherical droplets; (III) SON is dispersed spatially in MALAT1 knocked-down cells and MALAT1 is dispersed in SON knocked-down cells because of the collapse of the nuclear speckles. However, the detailed interactions among the molecules that are mechanistically responsible for the structural variation remain unknown. In this study, a coarse-grained molecular dynamics model of the nuclear speckle was developed by considering the dynamics of SON, SRRM2, MALAT1, and pre-mRNA as representative components of the condensates. The simulations reproduced the structural changes, which were used to predict the interaction network among the representative components of the condensates.
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Affiliation(s)
- Shingo Wakao
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
| | - Noriko Saitoh
- Division of Cancer Biology, The Cancer Institute of Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
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60
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Di Nunzio F, Uversky VN, Mouland AJ. Biomolecular condensates: insights into early and late steps of the HIV-1 replication cycle. Retrovirology 2023; 20:4. [PMID: 37029379 PMCID: PMC10081342 DOI: 10.1186/s12977-023-00619-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/16/2023] [Indexed: 04/09/2023] Open
Abstract
A rapidly evolving understanding of phase separation in the biological and physical sciences has led to the redefining of virus-engineered replication compartments in many viruses with RNA genomes. Condensation of viral, host and genomic and subgenomic RNAs can take place to evade the innate immunity response and to help viral replication. Divergent viruses prompt liquid-liquid phase separation (LLPS) to invade the host cell. During HIV replication there are several steps involving LLPS. In this review, we characterize the ability of individual viral and host partners that assemble into biomolecular condensates (BMCs). Of note, bioinformatic analyses predict models of phase separation in line with several published observations. Importantly, viral BMCs contribute to function in key steps retroviral replication. For example, reverse transcription takes place within nuclear BMCs, called HIV-MLOs while during late replication steps, retroviral nucleocapsid acts as a driver or scaffold to recruit client viral components to aid the assembly of progeny virions. Overall, LLPS during viral infections represents a newly described biological event now appreciated in the virology field, that can also be considered as an alternative pharmacological target to current drug therapies especially when viruses become resistant to antiviral treatment.
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Affiliation(s)
- Francesca Di Nunzio
- Advanced Molecular Virology Unit, Department of Virology, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Andrew J Mouland
- Lady Davis Institute at the Jewish General Hospital, Montréal, QC, H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal, QC, H3A 2B4, Canada.
- Department of Medicine, McGill University, Montréal, QC, H4A 3J1, Canada.
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61
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Hirose T, Ninomiya K, Nakagawa S, Yamazaki T. A guide to membraneless organelles and their various roles in gene regulation. Nat Rev Mol Cell Biol 2023; 24:288-304. [PMID: 36424481 DOI: 10.1038/s41580-022-00558-8] [Citation(s) in RCA: 129] [Impact Index Per Article: 129.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2022] [Indexed: 11/25/2022]
Abstract
Membraneless organelles (MLOs) are detected in cells as dots of mesoscopic size. By undergoing phase separation into a liquid-like or gel-like phase, MLOs contribute to intracellular compartmentalization of specific biological functions. In eukaryotes, dozens of MLOs have been identified, including the nucleolus, Cajal bodies, nuclear speckles, paraspeckles, promyelocytic leukaemia protein (PML) nuclear bodies, nuclear stress bodies, processing bodies (P bodies) and stress granules. MLOs contain specific proteins, of which many possess intrinsically disordered regions (IDRs), and nucleic acids, mainly RNA. Many MLOs contribute to gene regulation by different mechanisms. Through sequestration of specific factors, MLOs promote biochemical reactions by simultaneously concentrating substrates and enzymes, and/or suppressing the activity of the sequestered factors elsewhere in the cell. Other MLOs construct inter-chromosomal hubs by associating with multiple loci, thereby contributing to the biogenesis of macromolecular machineries essential for gene expression, such as ribosomes and spliceosomes. The organization of many MLOs includes layers, which might have different biophysical properties and functions. MLOs are functionally interconnected and are involved in various diseases, prompting the emergence of therapeutics targeting them. In this Review, we introduce MLOs that are relevant to gene regulation and discuss their assembly, internal structure, gene-regulatory roles in transcription, RNA processing and translation, particularly in stress conditions, and their disease relevance.
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Affiliation(s)
- Tetsuro Hirose
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.
- Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Japan.
| | - Kensuke Ninomiya
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Shinichi Nakagawa
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Tomohiro Yamazaki
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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62
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Rogalska ME, Vivori C, Valcárcel J. Regulation of pre-mRNA splicing: roles in physiology and disease, and therapeutic prospects. Nat Rev Genet 2023; 24:251-269. [PMID: 36526860 DOI: 10.1038/s41576-022-00556-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2022] [Indexed: 12/23/2022]
Abstract
The removal of introns from mRNA precursors and its regulation by alternative splicing are key for eukaryotic gene expression and cellular function, as evidenced by the numerous pathologies induced or modified by splicing alterations. Major recent advances have been made in understanding the structures and functions of the splicing machinery, in the description and classification of physiological and pathological isoforms and in the development of the first therapies for genetic diseases based on modulation of splicing. Here, we review this progress and discuss important remaining challenges, including predicting splice sites from genomic sequences, understanding the variety of molecular mechanisms and logic of splicing regulation, and harnessing this knowledge for probing gene function and disease aetiology and for the design of novel therapeutic approaches.
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Affiliation(s)
- Malgorzata Ewa Rogalska
- Genome Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Claudia Vivori
- Genome Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain
- The Francis Crick Institute, London, UK
| | - Juan Valcárcel
- Genome Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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63
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Cui H, Diedrich JK, Wu DC, Lim JJ, Nottingham RM, Moresco JJ, Yates JR, Blencowe BJ, Lambowitz AM, Schimmel P. Arg-tRNA synthetase links inflammatory metabolism to RNA splicing and nuclear trafficking via SRRM2. Nat Cell Biol 2023; 25:592-603. [PMID: 37059883 DOI: 10.1038/s41556-023-01118-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 02/27/2023] [Indexed: 04/16/2023]
Abstract
Cells respond to perturbations such as inflammation by sensing changes in metabolite levels. Especially prominent is arginine, which has known connections to the inflammatory response. Aminoacyl-tRNA synthetases, enzymes that catalyse the first step of protein synthesis, can also mediate cell signalling. Here we show that depletion of arginine during inflammation decreased levels of nuclear-localized arginyl-tRNA synthetase (ArgRS). Surprisingly, we found that nuclear ArgRS interacts and co-localizes with serine/arginine repetitive matrix protein 2 (SRRM2), a spliceosomal and nuclear speckle protein, and that decreased levels of nuclear ArgRS correlated with changes in condensate-like nuclear trafficking of SRRM2 and splice-site usage in certain genes. These splice-site usage changes cumulated in the synthesis of different protein isoforms that altered cellular metabolism and peptide presentation to immune cells. Our findings uncover a mechanism whereby an aminoacyl-tRNA synthetase cognate to a key amino acid that is metabolically controlled during inflammation modulates the splicing machinery.
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Affiliation(s)
- Haissi Cui
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Jolene K Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Douglas C Wu
- Institute for Cellular and Molecular Biology and Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX, USA
| | - Justin J Lim
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Ryan M Nottingham
- Institute for Cellular and Molecular Biology and Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX, USA
| | - James J Moresco
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
- Center for the Genetics of Host Defense, UT Southwestern Medical Center, Dallas, TX, USA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Benjamin J Blencowe
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Alan M Lambowitz
- Institute for Cellular and Molecular Biology and Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX, USA.
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA.
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64
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Fargason T, De Silva NIU, Powell E, Zhang Z, Paul T, Shariq J, Zaharias S, Zhang J. Peptides that Mimic RS repeats modulate phase separation of SRSF1, revealing a reliance on combined stacking and electrostatic interactions. eLife 2023; 12:e84412. [PMID: 36862748 PMCID: PMC10023157 DOI: 10.7554/elife.84412] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 03/01/2023] [Indexed: 03/03/2023] Open
Abstract
Phase separation plays crucial roles in both sustaining cellular function and perpetuating disease states. Despite extensive studies, our understanding of this process is hindered by low solubility of phase-separating proteins. One example of this is found in SR and SR-related proteins. These proteins are characterized by domains rich in arginine and serine (RS domains), which are essential to alternative splicing and in vivo phase separation. However, they are also responsible for a low solubility that has made these proteins difficult to study for decades. Here, we solubilize the founding member of the SR family, SRSF1, by introducing a peptide mimicking RS repeats as a co-solute. We find that this RS-mimic peptide forms interactions similar to those of the protein's RS domain. Both interact with a combination of surface-exposed aromatic residues and acidic residues on SRSF1's RNA Recognition Motifs (RRMs) through electrostatic and cation-pi interactions. Analysis of RRM domains from human SR proteins indicates that these sites are conserved across the protein family. In addition to opening an avenue to previously unavailable proteins, our work provides insight into how SR proteins phase separate and participate in nuclear speckles.
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Affiliation(s)
- Talia Fargason
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
| | | | - Erin Powell
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
| | - Zihan Zhang
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
| | - Trenton Paul
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
| | - Jamal Shariq
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
| | - Steve Zaharias
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
| | - Jun Zhang
- Department of Chemistry, University of Alabama at BirminghamBirminghamUnited States
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65
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Asher G, Zhu B. Beyond circadian rhythms: emerging roles of ultradian rhythms in control of liver functions. Hepatology 2023; 77:1022-1035. [PMID: 35591797 PMCID: PMC9674798 DOI: 10.1002/hep.32580] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 12/08/2022]
Abstract
The mammalian liver must cope with various metabolic and physiological changes that normally recur every day and primarily stem from daily cycles of rest-activity and fasting-feeding. Although a large body of evidence supports the reciprocal regulation of circadian rhythms and liver function, the research on the hepatic ultradian rhythms have largely been lagging behind. However, with the advent of more cost-effective high-throughput omics technologies, high-resolution time-lapse imaging, and more robust and powerful mathematical tools, several recent studies have shed new light on the presence and functions of hepatic ultradian rhythms. In this review, we will first very briefly discuss the basic principles of circadian rhythms, and then cover in greater details the recent literature related to ultradian rhythms. Specifically, we will highlight the prevalence and mechanisms of hepatic 12-h rhythms, and 8-h rhythms, which cycle at the second and third harmonics of circadian frequency. Finally, we also refer to ultradian rhythms with other frequencies and examine the limitations of the current approaches as well as the challenges related to identifying ultradian rhythm and addressing their molecular underpinnings.
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Affiliation(s)
- Gad Asher
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001, Rehovot, Israel
| | - Bokai Zhu
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pennsylvania, USA
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
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66
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Li X, An Z, Zhang W, Li F. Phase Separation: Direct and Indirect Driving Force for High-Order Chromatin Organization. Genes (Basel) 2023; 14:499. [PMID: 36833426 PMCID: PMC9956262 DOI: 10.3390/genes14020499] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/09/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023] Open
Abstract
The multi-level spatial chromatin organization in the nucleus is closely related to chromatin activity. The mechanism of chromatin organization and remodeling attract much attention. Phase separation describes the biomolecular condensation which is the basis for membraneless compartments in cells. Recent research shows that phase separation is a key aspect to drive high-order chromatin structure and remodeling. In addition, chromatin functional compartmentalization in the nucleus which is formed by phase separation also plays an important role in overall chromatin structure. In this review, we summarized the latest work about the role of phase separation in spatial chromatin organization, focusing on direct and indirect effects of phase separation on 3D chromatin organization and its impact on transcription regulation.
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Affiliation(s)
- Xiaoli Li
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
- Department of Cell Biology and Genetics, Core Facility of Developmental Biology, Chongqing Medical University, Chongqing 400016, China
| | - Ziyang An
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Wenqing Zhang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Feifei Li
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
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67
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Kumar A, Schrader AW, Boroojeny AE, Asadian M, Lee J, Song YJ, Zhao SD, Han HS, Sinha S. Intracellular Spatial Transcriptomic Analysis Toolkit (InSTAnT). RESEARCH SQUARE 2023:rs.3.rs-2481749. [PMID: 36747718 PMCID: PMC9901031 DOI: 10.21203/rs.3.rs-2481749/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Imaging-based spatial transcriptomics technologies such as MERFISH offer snapshots of cellular processes in unprecedented detail, but new analytic tools are needed to realize their full potential. We present InSTAnT, a computational toolkit for extracting molecular relationships from spatial transcriptomics data at the intra-cellular resolution. InSTAnT detects gene pairs and modules with interesting patterns of mutual co-localization within and across cells, using specialized statistical tests and graph mining. We showcase the toolkit on datasets profiling a human cancer cell line and hypothalamic preoptic region of mouse brain. We performed rigorous statistical assessment of discovered co-localization patterns, found supporting evidence from databases and RNA interactions, and identified subcellular domains associated with RNA-colocalization. We identified several novel cell type-specific gene co-localizations in the brain. Intra-cellular spatial patterns discovered by InSTAnT mirror diverse molecular relationships, including RNA interactions and shared sub-cellular localization or function, providing a rich compendium of testable hypotheses regarding molecular functions.
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Affiliation(s)
- Anurendra Kumar
- College of Computing, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Alex W. Schrader
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | | | - Marisa Asadian
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Juyeon Lee
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - You Jin Song
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Sihai Dave Zhao
- Department of Statistics, University of Illinois Urbana-Champaign, Urbana, IL, 61820, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Hee-Sun Han
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Saurabh Sinha
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- H. Milton Stewart School of Industrial & Systems Engineering, Georgia Institute of Technology, Atlanta, GA, 30318, USA
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68
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Lester E, Van Alstyne M, McCann KL, Reddy S, Cheng LY, Kuo J, Pratt J, Parker R. Cytosolic condensates rich in polyserine define subcellular sites of tau aggregation. Proc Natl Acad Sci U S A 2023; 120:e2217759120. [PMID: 36626563 PMCID: PMC9934293 DOI: 10.1073/pnas.2217759120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/06/2022] [Indexed: 01/11/2023] Open
Abstract
Tau aggregates are a hallmark of multiple neurodegenerative diseases and can contain RNAs and RNA-binding proteins, including serine/arginine repetitive matrix protein 2 (SRRM2) and pinin (PNN). However, how these nuclear proteins mislocalize and their influence on the prion-like propagation of tau aggregates is unknown. We demonstrate that polyserine repeats in SRRM2 and PNN are necessary and sufficient for recruitment to tau aggregates. Moreover, we show tau aggregates preferentially grow in association with endogenous cytoplasmic assemblies-mitotic interchromatin granules and cytoplasmic speckles (CSs)-which contain SRRM2 and PNN. Polyserine overexpression in cells nucleates assemblies that are sites of tau aggregate growth. Further, modulating the levels of polyserine-containing proteins results in a corresponding change in tau aggregation. These findings define a specific protein motif, and cellular condensates, that promote tau aggregate propagation. As CSs form in induced pluripotent stem cell (iPSC) derived neurons under inflammatory or hyperosmolar stress, they may affect tau aggregate propagation in neurodegenerative disease.
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Affiliation(s)
- Evan Lester
- Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, CO80045
- Department of Biochemistry, University of Colorado, Boulder, CO80303
| | - Meaghan Van Alstyne
- Department of Biochemistry, University of Colorado, Boulder, CO80303
- HHMI, University of Colorado, Boulder, CO80303
| | - Kathleen L. McCann
- Department of Biochemistry, University of Colorado, Boulder, CO80303
- HHMI, University of Colorado, Boulder, CO80303
| | - Spoorthy Reddy
- Department of Biochemistry, University of Colorado, Boulder, CO80303
| | - Li Yi Cheng
- Department of Biochemistry, University of Colorado, Boulder, CO80303
| | - Jeff Kuo
- Department of Biochemistry, University of Colorado, Boulder, CO80303
| | - James Pratt
- Department of Biochemistry, University of Colorado, Boulder, CO80303
| | - Roy Parker
- Department of Biochemistry, University of Colorado, Boulder, CO80303
- HHMI, University of Colorado, Boulder, CO80303
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69
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de Oliveira Freitas Machado C, Schafranek M, Brüggemann M, Hernández Cañás M, Keller M, Di Liddo A, Brezski A, Blümel N, Arnold B, Bremm A, Wittig I, Jaé N, McNicoll F, Dimmeler S, Zarnack K, Müller-McNicoll M. Poison cassette exon splicing of SRSF6 regulates nuclear speckle dispersal and the response to hypoxia. Nucleic Acids Res 2023; 51:870-890. [PMID: 36620874 PMCID: PMC9881134 DOI: 10.1093/nar/gkac1225] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 12/06/2022] [Accepted: 12/10/2022] [Indexed: 01/10/2023] Open
Abstract
Hypoxia induces massive changes in alternative splicing (AS) to adapt cells to the lack of oxygen. Here, we identify the splicing factor SRSF6 as a key factor in the AS response to hypoxia. The SRSF6 level is strongly reduced in acute hypoxia, which serves a dual purpose: it allows for exon skipping and triggers the dispersal of nuclear speckles. Our data suggest that cells use dispersal of nuclear speckles to reprogram their gene expression during hypoxic adaptation and that SRSF6 plays an important role in cohesion of nuclear speckles. Down-regulation of SRSF6 is achieved through inclusion of a poison cassette exon (PCE) promoted by SRSF4. Removing the PCE 3' splice site using CRISPR/Cas9 abolishes SRSF6 reduction in hypoxia. Aberrantly high SRSF6 levels in hypoxia attenuate hypoxia-mediated AS and impair dispersal of nuclear speckles. As a consequence, proliferation and genomic instability are increased, while the stress response is suppressed. The SRSF4-PCE-SRSF6 hypoxia axis is active in different cancer types, and high SRSF6 expression in hypoxic tumors correlates with a poor prognosis. We propose that the ultra-conserved PCE of SRSF6 acts as a tumor suppressor and that its inclusion in hypoxia is crucial to reduce SRSF6 levels. This may prevent tumor cells from entering the metastatic route of hypoxia adaptation.
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Affiliation(s)
- Camila de Oliveira Freitas Machado
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany,Institute of Cardiovascular Regeneration, Goethe University, Frankfurt am Main, Germany
| | - Michal Schafranek
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Mirko Brüggemann
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany,Buchmann Institute for Molecular Life Sciences (BMLS), Frankfurt am Main, Germany
| | | | - Mario Keller
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany,Buchmann Institute for Molecular Life Sciences (BMLS), Frankfurt am Main, Germany
| | - Antonella Di Liddo
- Buchmann Institute for Molecular Life Sciences (BMLS), Frankfurt am Main, Germany
| | - Andre Brezski
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany,Buchmann Institute for Molecular Life Sciences (BMLS), Frankfurt am Main, Germany
| | - Nicole Blümel
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Benjamin Arnold
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Anja Bremm
- Institute of Biochemistry II, Goethe University, Frankfurt am Main, Germany
| | - Ilka Wittig
- Functional Proteomics, Institute of Cardiovascular Physiology, Goethe University, Frankfurt am Main, Germany
| | - Nicolas Jaé
- Institute of Cardiovascular Regeneration, Goethe University, Frankfurt am Main, Germany
| | - François McNicoll
- Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Stefanie Dimmeler
- Institute of Cardiovascular Regeneration, Goethe University, Frankfurt am Main, Germany
| | - Kathi Zarnack
- Correspondence may also be addressed to Kathi Zarnack.
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70
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Eck RJ, Kow RL, Black AH, Liachko NF, Kraemer BC. SPOP loss of function protects against tauopathy. Proc Natl Acad Sci U S A 2023; 120:e2207250120. [PMID: 36574656 PMCID: PMC9910588 DOI: 10.1073/pnas.2207250120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 11/21/2022] [Indexed: 12/28/2022] Open
Abstract
The pathological accumulation of the microtubule binding protein tau drives age-related neurodegeneration in a variety of disorders, collectively called tauopathies. In the most common tauopathy, Alzheimer's disease (AD), the accumulation of pathological tau strongly correlates with cognitive decline. The underlying molecular mechanisms that drive neurodegeneration in tauopathies remain incompletely understood and no effective disease modifying pharmacological interventions currently exist. Here, we show that tau toxicity depends on the highly conserved nuclear E3 ubiquitin ligase adaptor protein SPOP in a Caenorhabditis elegans model of tauopathy. Loss of function mutations in the C. elegans spop-1 gene significantly improves behavioral deficits in tau transgenic animals, while neuronal overexpression of SPOP-1 protein significantly worsens behavioral deficits. In addition, loss of spop-1 rescues a variety of tau-related phenotypes including the accumulation of total and phosphorylated tau protein, neurodegeneration, and shortened lifespan. Knockdown of SPOP-1's E3 ubiquitin ligase cul-3/Cullin3 does not improve tauopathy suggesting a non-degradative mechanism of action for SPOP-1. Suppression of disease-related phenotypes occurs independently of the nuclear speckle resident poly(A)-binding protein SUT-2/MSUT2. MSUT2 modifies tauopathy in mammalian neurons and in AD. Our work identifies SPOP as a novel modifier of tauopathy and a conceptual pathway for therapeutic intervention.
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Affiliation(s)
- Randall J. Eck
- Graduate Program in Neuroscience, University of Washington, Seattle, WA98195
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA98104
| | - Rebecca L. Kow
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA98104
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA98108
| | - Aristide H. Black
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA98108
| | - Nicole F. Liachko
- Graduate Program in Neuroscience, University of Washington, Seattle, WA98195
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA98104
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA98108
| | - Brian C. Kraemer
- Graduate Program in Neuroscience, University of Washington, Seattle, WA98195
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA98104
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA98108
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington98195
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington98195
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71
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Lee DSW, Choi CH, Sanders DW, Beckers L, Riback JA, Brangwynne CP, Wingreen NS. Size distributions of intracellular condensates reflect competition between coalescence and nucleation. NATURE PHYSICS 2023; 19:586-596. [PMID: 37073403 PMCID: PMC10104779 DOI: 10.1038/s41567-022-01917-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 12/12/2022] [Indexed: 05/03/2023]
Abstract
Phase separation of biomolecules into condensates has emerged as a mechanism for intracellular organization and affects many intracellular processes, including reaction pathways through the clustering of enzymes and pathway intermediates. Precise and rapid spatiotemporal control of reactions by condensates requires tuning of their sizes. However, the physical processes that govern the distribution of condensate sizes remain unclear. Here we show that both native and synthetic condensates display an exponential size distribution, which is captured by Monte Carlo simulations of fast nucleation followed by coalescence. In contrast, pathological aggregates exhibit a power-law size distribution. These distinct behaviours reflect the relative importance of nucleation and coalescence kinetics. We demonstrate this by utilizing a combination of synthetic and native condensates to probe the underlying physical mechanisms determining condensate size. The appearance of exponential distributions for abrupt nucleation versus power-law distributions under continuous nucleation may reflect a general principle that determines condensate size distributions.
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Affiliation(s)
- Daniel S. W. Lee
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ USA
- Present Address: Department of Bioengineering, University of California, Berkeley, CA USA
| | - Chang-Hyun Choi
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
| | - David W. Sanders
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
| | - Lien Beckers
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
- Howard Hughes Medical Institute, Princeton, NJ USA
| | - Joshua A. Riback
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
- Present Address: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX USA
| | - Clifford P. Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
- Howard Hughes Medical Institute, Princeton, NJ USA
| | - Ned S. Wingreen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ USA
- Department of Molecular Biology, Princeton University, Princeton, NJ USA
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72
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Latham AP, Zhang B. Molecular Determinants for the Layering and Coarsening of Biological Condensates. AGGREGATE (HOBOKEN, N.J.) 2022; 3:e306. [PMID: 37065433 PMCID: PMC10101022 DOI: 10.1002/agt2.306] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Many membraneless organelles, or biological condensates, form through phase separation, and play key roles in signal sensing and transcriptional regulation. While the functional importance of these condensates has inspired many studies to characterize their stability and spatial organization, the underlying principles that dictate these emergent properties are still being uncovered. In this review, we examine recent work on biological condensates, especially multicomponent systems. We focus on connecting molecular factors such as binding energy, valency, and stoichiometry with the interfacial tension, explaining the nontrivial interior organization in many condensates. We further discuss mechanisms that arrest condensate coalescence by lowering the surface tension or introducing kinetic barriers to stabilize the multidroplet state.
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Affiliation(s)
- Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139
- Department of Bioengineering and Therapeutic Sciences, University of California at San Francisco, San Francisco, CA 94143
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139
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73
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Ilık İA, Aktaş T. Nuclear speckles: dynamic hubs of gene expression regulation. FEBS J 2022; 289:7234-7245. [PMID: 34245118 DOI: 10.1111/febs.16117] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/13/2021] [Accepted: 07/08/2021] [Indexed: 01/13/2023]
Abstract
Complex, multistep biochemical reactions that routinely take place in our cells require high concentrations of enzymes, substrates, and other structural components to proceed efficiently and typically require chemical environments that can inhibit other reactions in their immediate vicinity. Eukaryotic cells solve these problems by restricting such reactions into diffusion-restricted compartments within the cell called organelles that can be separated from their environment by a lipid membrane, or into membrane-less compartments that form through liquid-liquid phase separation (LLPS). One of the most easily noticeable and the earliest discovered organelle is the nucleus, which harbors the genetic material in cells where transcription by RNA polymerases produces most of the messenger RNAs and a plethora of noncoding RNAs, which in turn are required for translation of mRNAs in the cytoplasm. The interior of the nucleus is not a uniform soup of biomolecules and rather consists of a variety of membrane-less bodies, such as the nucleolus, nuclear speckles (NS), paraspeckles, Cajal bodies, histone locus bodies, and more. In this review, we will focus on NS with an emphasis on recent developments including our own findings about the formation of NS by two large IDR-rich proteins SON and SRRM2.
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Affiliation(s)
| | - Tuğçe Aktaş
- Max Planck Institute for Molecular Genetics, Berlin, Germany
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74
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Cascarina SM, Ross ED. Expansion and functional analysis of the SR-related protein family across the domains of life. RNA (NEW YORK, N.Y.) 2022; 28:1298-1314. [PMID: 35863866 PMCID: PMC9479744 DOI: 10.1261/rna.079170.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Serine/arginine-rich (SR) proteins comprise a family of proteins that is predominantly found in eukaryotes and plays a prominent role in RNA splicing. A characteristic feature of SR proteins is the presence of an S/R-rich low-complexity domain (RS domain), often in conjunction with spatially distinct RNA recognition motifs (RRMs). To date, 52 human proteins have been classified as SR or SR-related proteins. Here, using an unbiased series of composition criteria together with enrichment for known RNA binding activity, we identified >100 putative SR-related proteins in the human proteome. This method recovers known SR and SR-related proteins with high sensitivity (∼94%), yet identifies a number of additional proteins with many of the hallmark features of true SR-related proteins. Newly identified SR-related proteins display slightly different amino acid compositions yet similar levels of post-translational modification, suggesting that these new SR-related candidates are regulated in vivo and functionally important. Furthermore, candidate SR-related proteins with known RNA-binding activity (but not currently recognized as SR-related proteins) are nevertheless strongly associated with a variety of functions related to mRNA splicing and nuclear speckles. Finally, we applied our SR search method to all available reference proteomes, and provide maps of RS domains and Pfam annotations for all putative SR-related proteins as a resource. Together, these results expand the set of SR-related proteins in humans, and identify the most common functions associated with SR-related proteins across all domains of life.
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Affiliation(s)
- Sean M Cascarina
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Eric D Ross
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA
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75
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Zhang Y, Ye G, Yang Q, Zheng B, Zhang G, Hu Y, Yu J, Li G. Landscape of exitrons in gastric cancer. EBioMedicine 2022; 84:104272. [PMID: 36137412 PMCID: PMC9494173 DOI: 10.1016/j.ebiom.2022.104272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 09/05/2022] [Accepted: 09/05/2022] [Indexed: 11/17/2022] Open
Abstract
Background Exitron is a new type of non-canonical alternative splicing. Accumulating evidence implies exitron may have pathological function and contribute to another source of anti-tumor immunogenicity in various cancers. Its role in gastric cancer remains poorly understood. Large-scale, multi-omics analysis could comprehensively characterize the landscape of exitrons in gastric cancer, reveal undiscovered mechanism and hopefully identify molecular biomarkers for predicting immunotherapy response. Methods We collected datasets from five studies for analysis. RNA sequencing was used for exitron identification. Somatic mutations were detected by whole exome sequencing. Neopeptides were confirmed by proteome mass spectrometry. Findings 42174 gastric cancer-specific exitrons (GCSEs) were identified in 632 patients. GCSEs were clinically relevant to gender, age, Lauren type, tumor stage and prognosis. Tissue specificity test and pathogenic exitron prediction revealed their unique functional impact. GCSEs were mutually exclusive with mutations and demonstrated both unique and complementary function against TP53 mutation in gastric cancer. We further established splicing regulatory network to reveal upstream regulation of exitron splicing. We also evaluated the immunogenicity and diagnostic potential of GCSEs. Evidence of GCSEs-derived neopeptide expression was validated by whole proteome mass spectrometry. PD-1 and Siglecs were significantly increased in high neoantigen load patients. But exitron-related biomarkers failed to predict immunotherapy response, possibly due to small sample size and insufficient sequencing depth. Interpretation The present study provided a comprehensive multidimensional landscape of gastric cancer exitrons and underscores insights into underexplored mechanism in gastric cancer pathology. Funding The Guangdong Provincial Key Laboratory of Precision Medicine for Gastroinstestinal Cancer (2020B121201004), the Guangdong Provincial Major Talents Project (No. 2019JC05Y361) and National Natural Science Foundation of China (grant number:82172960 and 81872013).
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Affiliation(s)
- Yihao Zhang
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Gengtai Ye
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Qingbin Yang
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Boyang Zheng
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Guofan Zhang
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Yanfeng Hu
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Jiang Yu
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China
| | - Guoxin Li
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Precision Medicine for Gastrointestinal Tumor, Guangzhou, Guangdong 510515, China.
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76
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Lacroix E, Audas TE. Keeping up with the condensates: The retention, gain, and loss of nuclear membrane-less organelles. Front Mol Biosci 2022; 9:998363. [PMID: 36203874 PMCID: PMC9530788 DOI: 10.3389/fmolb.2022.998363] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/19/2022] [Indexed: 12/04/2022] Open
Abstract
In recent decades, a growing number of biomolecular condensates have been identified in eukaryotic cells. These structures form through phase separation and have been linked to a diverse array of cellular processes. While a checklist of established membrane-bound organelles is present across the eukaryotic domain, less is known about the conservation of membrane-less subcellular structures. Many of these structures can be seen throughout eukaryotes, while others are only thought to be present in metazoans or a limited subset of species. In particular, the nucleus is a hub of biomolecular condensates. Some of these subnuclear domains have been found in a broad range of organisms, which is a characteristic often attributed to essential functionality. However, this does not always appear to be the case. For example, the nucleolus is critical for ribosomal biogenesis and is present throughout the eukaryotic domain, while the Cajal bodies are believed to be similarly conserved, yet these structures are dispensable for organismal survival. Likewise, depletion of the Drosophila melanogaster omega speckles reduces viability, despite the apparent absence of this domain in higher eukaryotes. By reviewing primary research that has analyzed the presence of specific condensates (nucleoli, Cajal bodies, amyloid bodies, nucleolar aggresomes, nuclear speckles, nuclear paraspeckles, nuclear stress bodies, PML bodies, omega speckles, NUN bodies, mei2 dots) in a cross-section of organisms (e.g., human, mouse, D. melanogaster, Caenorhabditis elegans, yeast), we adopt a human-centric view to explore the emergence, retention, and absence of a subset of nuclear biomolecular condensates. This overview is particularly important as numerous biomolecular condensates have been linked to human disease, and their presence in additional species could unlock new and well characterized model systems for health research.
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Affiliation(s)
- Emma Lacroix
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
- Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC, Canada
| | - Timothy E. Audas
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
- Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC, Canada
- *Correspondence: Timothy E. Audas,
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77
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Lee B, Jaberi-Lashkari N, Calo E. A unified view of low complexity regions (LCRs) across species. eLife 2022; 11:e77058. [PMID: 36098382 PMCID: PMC9470157 DOI: 10.7554/elife.77058] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
Low complexity regions (LCRs) play a role in a variety of important biological processes, yet we lack a unified view of their sequences, features, relationships, and functions. Here, we use dotplots and dimensionality reduction to systematically define LCR type/copy relationships and create a map of LCR sequence space capable of integrating LCR features and functions. By defining LCR relationships across the proteome, we provide insight into how LCR type and copy number contribute to higher order assemblies, such as the importance of K-rich LCR copy number for assembly of the nucleolar protein RPA43 in vivo and in vitro. With LCR maps, we reveal the underlying structure of LCR sequence space, and relate differential occupancy in this space to the conservation and emergence of higher order assemblies, including the metazoan extracellular matrix and plant cell wall. Together, LCR relationships and maps uncover and identify scaffold-client relationships among E-rich LCR-containing proteins in the nucleolus, and revealed previously undescribed regions of LCR sequence space with signatures of higher order assemblies, including a teleost-specific T/H-rich sequence space. Thus, this unified view of LCRs enables discovery of how LCRs encode higher order assemblies of organisms.
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Affiliation(s)
- Byron Lee
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Nima Jaberi-Lashkari
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Eliezer Calo
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of TechnologyCambridgeUnited States
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78
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Zhu B. Logic of the Temporal Compartmentalization of the Hepatic Metabolic Cycle. Physiology (Bethesda) 2022; 37:0. [PMID: 35658626 PMCID: PMC9394779 DOI: 10.1152/physiol.00003.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 05/05/2022] [Accepted: 05/28/2022] [Indexed: 12/25/2022] Open
Abstract
The mammalian liver must cope with various metabolic and physiological changes that normally recur every day and result primarily from rest-activity and fasting-feeding cycles. In this article, I present evidence supporting a temporal compartmentalization of rhythmic hepatic metabolic processes into four main clusters: regulation of energy homeostasis, maintenance of information integrity, immune response, and genetic information flow. I further review literatures and discuss how both the circadian and the newly discovered 12-h ultradian clock work together to regulate these four temporally separated processes in mouse liver, which, interestingly, is largely uncoupled from the liver zonation regulation.
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Affiliation(s)
- Bokai Zhu
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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79
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Substrate spectrum of PPM1D in the cellular response to DNA double-strand breaks. iScience 2022; 25:104892. [PMID: 36060052 PMCID: PMC9436757 DOI: 10.1016/j.isci.2022.104892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 07/03/2022] [Accepted: 08/02/2022] [Indexed: 12/03/2022] Open
Abstract
PPM1D is a p53-regulated protein phosphatase that modulates the DNA damage response (DDR) and is frequently altered in cancer. Here, we employed chemical inhibition of PPM1D and quantitative mass spectrometry-based phosphoproteomics to identify the substrates of PPM1D upon induction of DNA double-strand breaks (DSBs) by etoposide. We identified 73 putative PPM1D substrates that are involved in DNA repair, regulation of transcription, and RNA processing. One-third of DSB-induced S/TQ phosphorylation sites are dephosphorylated by PPM1D, demonstrating that PPM1D only partially counteracts ATM/ATR/DNA-PK signaling. PPM1D-targeted phosphorylation sites are found in a specific amino acid sequence motif that is characterized by glutamic acid residues, high intrinsic disorder, and poor evolutionary conservation. We identified a functionally uncharacterized protein Kanadaptin as ATM and PPM1D substrate upon DSB induction. We propose that PPM1D plays a role during the response to DSBs by regulating the phosphorylation of DNA- and RNA-binding proteins in intrinsically disordered regions. MS-based phosphoproteomic profiling of PPM1D substrates in U2OS and HCT116 cells PPM1D counteracts ATM in the cellular response to DNA double-strand breaks PPM1D target sites localize to glutamic acid-rich regions with high intrinsic disorder Kanadaptin is a putative DNA damage response factor regulated by ATM and PPM1D
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80
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Kanekura K, Kuroda M. How can we interpret the relationship between liquid-liquid phase separation and amyotrophic lateral sclerosis? J Transl Med 2022; 102:912-918. [PMID: 36775420 DOI: 10.1038/s41374-022-00791-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/12/2022] [Indexed: 01/08/2023] Open
Abstract
One of the critical definitions of neurodegenerative diseases is the formation of insoluble intracellular inclusion body. These inclusions are found in various neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis (ALS), Huntington's disease, Parkinson's disease, and frontotemporal dementia (FTD). Each inclusion body contains disease-specific proteins and is also resistant to common detergent treatments. These aggregates are generally ubiquitinated and thus recognized as misfolded by the organism. They are observed in residual neurons at the affected sites in each disease, suggesting a contribution to disease pathogenesis. The molecular mechanisms for the formation of these inclusion bodies remain unclear. Some proteins, such as superoxide dismutase 1 (SOD1) mutant that causes familial ALS, are highly aggregative due to altered folding caused by point mutations. Still, the aggregates observed in neurodegenerative diseases contain wild-type proteins. In recent years, it has been reported that the proteins responsible for neurodegenerative diseases undergo liquid-liquid phase separation (LLPS). In particular, the ALS/FTD causative proteins such as TAR DNA-binding protein 43 kDa (TDP-43) and fused-in-sarcoma (FUS) undergo LLPS. LLPS increases the local concentration of these proteins, and these proteins eventually change their phase from liquid to solid (liquid-solid phase transition) due to abnormal folding during repetitive separation cycles into two phases and recovery to one phase. In addition to the inclusion body formation, sequestration of essential proteins into the LLPS droplets or changes in the LLPS status can directly impair neural functions and cause diseases. In this review, we will discuss the relationship between the LLPS observed in ALS causative proteins and the pathogenesis of the disease and outline potential therapeutic approaches.
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Affiliation(s)
- Kohsuke Kanekura
- Department of Molecular Pathology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan.
| | - Masahiko Kuroda
- Department of Molecular Pathology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan
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81
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Cytoplasmic forces functionally reorganize nuclear condensates in oocytes. Nat Commun 2022; 13:5070. [PMID: 36038550 PMCID: PMC9424315 DOI: 10.1038/s41467-022-32675-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/05/2022] [Indexed: 12/21/2022] Open
Abstract
Cells remodel their cytoplasm with force-generating cytoskeletal motors. Their activity generates random forces that stir the cytoplasm, agitating and displacing membrane-bound organelles like the nucleus in somatic and germ cells. These forces are transmitted inside the nucleus, yet their consequences on liquid-like biomolecular condensates residing in the nucleus remain unexplored. Here, we probe experimentally and computationally diverse nuclear condensates, that include nuclear speckles, Cajal bodies, and nucleoli, during cytoplasmic remodeling of female germ cells named oocytes. We discover that growing mammalian oocytes deploy cytoplasmic forces to timely impose multiscale reorganization of nuclear condensates for the success of meiotic divisions. These cytoplasmic forces accelerate nuclear condensate collision-coalescence and molecular kinetics within condensates. Disrupting the forces decelerates nuclear condensate reorganization on both scales, which correlates with compromised condensate-associated mRNA processing and hindered oocyte divisions that drive female fertility. We establish that cytoplasmic forces can reorganize nuclear condensates in an evolutionary conserved fashion in insects. Our work implies that cells evolved a mechanism, based on cytoplasmic force tuning, to functionally regulate a broad range of nuclear condensates across scales. This finding opens new perspectives when studying condensate-associated pathologies like cancer, neurodegeneration and viral infections. Cytoskeletal activity generates mechanical forces known to agitate and displace membrane-bound organelles in the cytoplasm. In oocytes, Al Jord et al. discover that these cytoplasmic forces functionally remodel nuclear RNA-processing condensates across scales for developmental success.
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82
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Xu S, Lai SK, Sim DY, Ang W, Li HY, Roca X. SRRM2 organizes splicing condensates to regulate alternative splicing. Nucleic Acids Res 2022; 50:8599-8614. [PMID: 35929045 PMCID: PMC9410892 DOI: 10.1093/nar/gkac669] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/29/2022] [Accepted: 08/04/2022] [Indexed: 12/27/2022] Open
Abstract
SRRM2 is a nuclear-speckle marker containing multiple disordered domains, whose dysfunction is associated with several human diseases. Using mainly EGFP-SRRM2 knock-in HEK293T cells, we show that SRRM2 forms biomolecular condensates satisfying most hallmarks of liquid-liquid phase separation, including spherical shape, dynamic rearrangement, coalescence and concentration dependence supported by in vitro experiments. Live-cell imaging shows that SRRM2 organizes nuclear speckles along the cell cycle. As bona-fide splicing factor present in spliceosome structures, SRRM2 deficiency induces skipping of cassette exons with short introns and weak splice sites, tending to change large protein domains. In THP-1 myeloid-like cells, SRRM2 depletion compromises cell viability, upregulates differentiation markers, and sensitizes cells to anti-leukemia drugs. SRRM2 induces a FES splice isoform that attenuates innate inflammatory responses, and MUC1 isoforms that undergo shedding with oncogenic properties. We conclude that SRRM2 acts as a scaffold to organize nuclear speckles, regulating alternative splicing in innate immunity and cell homeostasis.
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Affiliation(s)
- Shaohai Xu
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Soak-Kuan Lai
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Donald Yuhui Sim
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | | | - Hoi Yeung Li
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Xavier Roca
- To whom correspondence should be addressed. Tel: +65 65927561;
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83
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Cuinat S, Nizon M, Isidor B, Stegmann A, van Jaarsveld RH, van Gassen KL, van der Smagt JJ, Volker-Touw CML, Holwerda SJB, Terhal PA, Schuhmann S, Vasileiou G, Khalifa M, Nugud AA, Yasaei H, Ousager LB, Brasch-Andersen C, Deb W, Besnard T, Simon MEH, Amsterdam KHV, Verbeek NE, Matalon D, Dykzeul N, White S, Spiteri E, Devriendt K, Boogaerts A, Willemsen M, Brunner HG, Sinnema M, De Vries BBA, Gerkes EH, Pfundt R, Izumi K, Krantz ID, Xu ZL, Murrell JR, Valenzuela I, Cusco I, Rovira-Moreno E, Yang Y, Bizaoui V, Patat O, Faivre L, Tran-Mau-Them F, Vitobello A, Denommé-Pichon AS, Philippe C, Bezieau S, Cogné B. Loss-of-function variants in SRRM2 cause a neurodevelopmental disorder. Genet Med 2022; 24:1774-1780. [PMID: 35567594 DOI: 10.1016/j.gim.2022.04.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/06/2022] [Accepted: 04/06/2022] [Indexed: 10/18/2022] Open
Abstract
PURPOSE SRRM2 encodes the SRm300 protein, a splicing factor of the SR-related protein family characterized by its serine- and arginine-enriched domains. It promotes interactions between messenger RNA and the spliceosome catalytic machinery. This gene, predicted to be highly intolerant to loss of function (LoF) and very conserved through evolution, has not been previously reported in constitutive human disease. METHODS Among the 1000 probands studied with developmental delay and intellectual disability in our database, we found 2 patients with de novo LoF variants in SRRM2. Additional families were identified through GeneMatcher. RESULTS Here, we report on 22 patients with LoF variants in SRRM2 and provide a description of the phenotype. Molecular analysis identified 12 frameshift variants, 8 nonsense variants, and 2 microdeletions of 66 kb and 270 kb. The patients presented with a mild developmental delay, predominant speech delay, autistic or attention-deficit/hyperactivity disorder features, overfriendliness, generalized hypotonia, overweight, and dysmorphic facial features. Intellectual disability was variable and mild when present. CONCLUSION We established SRRM2 as a gene responsible for a rare neurodevelopmental disease.
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Affiliation(s)
- Silvestre Cuinat
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France.
| | - Mathilde Nizon
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France; Université de Nantes, Inserm UMR 1087 / CNRS UMR 6291, Institut du thorax, Nantes, France
| | - Bertrand Isidor
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France; Université de Nantes, Inserm UMR 1087 / CNRS UMR 6291, Institut du thorax, Nantes, France
| | - Alexander Stegmann
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Koen L van Gassen
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | - Sjoerd J B Holwerda
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Paulien A Terhal
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Sarah Schuhmann
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Georgia Vasileiou
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Mohamed Khalifa
- Genetic Department, Dubai Health Authority, Latifa Women and Children Hospital, Dubai, United Arab Emirates
| | - Alaa A Nugud
- Genetic Department, Dubai Health Authority, Latifa Women and Children Hospital, Dubai, United Arab Emirates
| | - Hemad Yasaei
- Dubai Genetics Center, Pathology and Genetics Department, Dubai Health Authority, Dubai, United Arab Emirates
| | - Lilian Bomme Ousager
- Department of Clinical Genetics & Human Genetics, Odense University Hospital, University of Southern Denmark, Odense, Denmark; Department of Clinical Research, Odense University Hospital, University of Southern Denmark, Odense, Denmark
| | - Charlotte Brasch-Andersen
- Department of Clinical Genetics & Human Genetics, Odense University Hospital, University of Southern Denmark, Odense, Denmark; Department of Clinical Research, Odense University Hospital, University of Southern Denmark, Odense, Denmark
| | - Wallid Deb
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France; Université de Nantes, Inserm UMR 1087 / CNRS UMR 6291, Institut du thorax, Nantes, France
| | - Thomas Besnard
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France; Université de Nantes, Inserm UMR 1087 / CNRS UMR 6291, Institut du thorax, Nantes, France
| | - Marleen E H Simon
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Nienke E Verbeek
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dena Matalon
- Department of Pediatric, Division of Medical Genetics, Stanford University and Health Care, Palo Alto, CA
| | - Natalie Dykzeul
- Department of Pediatric, Division of Medical Genetics, Stanford University and Health Care, Palo Alto, CA
| | - Shana White
- Department of Pediatric, Division of Medical Genetics, Stanford University and Health Care, Palo Alto, CA
| | - Elizabeth Spiteri
- Department of Pediatric, Division of Medical Genetics, Stanford University and Health Care, Palo Alto, CA
| | - Koen Devriendt
- Center for Human Genetics, University Hospital Leuven, KU Leuven, O&N I Herestraat 49, Leuven, Belgium
| | - Anneleen Boogaerts
- Center for Human Genetics, University Hospital Leuven, KU Leuven, O&N I Herestraat 49, Leuven, Belgium
| | - Marjolein Willemsen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Han G Brunner
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Margje Sinnema
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Bert B A De Vries
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Erica H Gerkes
- University Medical Center Groningen, Department of Genetics, University of Groningen, Groningen, The Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kosuke Izumi
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Ian D Krantz
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Zhou L Xu
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Jill R Murrell
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Irene Valenzuela
- Department of Clinical and Molecular Genetics, Hospital Vall d'Hebron, Barcelona, Spain
| | - Ivon Cusco
- Department of Clinical and Molecular Genetics, Hospital Vall d'Hebron, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Eulàlia Rovira-Moreno
- Department of Clinical and Molecular Genetics, Hospital Vall d'Hebron, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | | | - Varoona Bizaoui
- Clinical Genetics and Neurodevelopmental Disorders, Centre Hospitalier de l'Estran, Pontorson, France
| | - Olivier Patat
- Department of Medical Genetics, Toulouse University Hospital, Toulouse, France
| | - Laurence Faivre
- Centre de référence Anomalies du Développement et Syndromes malformatifs, FHU-TRANSLAD, GAD, CHU Dijon et Université de Bourgogne, Dijon, France; Inserm UMR1231, GAD, Université de Bourgogne, Dijon, France
| | - Frederic Tran-Mau-Them
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France; Inserm UMR1231, GAD, Université de Bourgogne, Dijon, France
| | - Antonio Vitobello
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France; Inserm UMR1231, GAD, Université de Bourgogne, Dijon, France
| | - Anne-Sophie Denommé-Pichon
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France; Inserm UMR1231, GAD, Université de Bourgogne, Dijon, France
| | - Christophe Philippe
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France; Inserm UMR1231, GAD, Université de Bourgogne, Dijon, France
| | - Stéphane Bezieau
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France; Université de Nantes, Inserm UMR 1087 / CNRS UMR 6291, Institut du thorax, Nantes, France
| | - Benjamin Cogné
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France; Université de Nantes, Inserm UMR 1087 / CNRS UMR 6291, Institut du thorax, Nantes, France.
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84
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Fujiwara N, Shigemoto M, Hirayama M, Fujita KI, Seno S, Matsuda H, Nagahama M, Masuda S. MPP6 stimulates both RRP6 and DIS3 to degrade a specified subset of MTR4-sensitive substrates in the human nucleus. Nucleic Acids Res 2022; 50:8779-8806. [PMID: 35902094 PMCID: PMC9410898 DOI: 10.1093/nar/gkac559] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 06/10/2022] [Accepted: 07/20/2022] [Indexed: 11/13/2022] Open
Abstract
Recent in vitro reconstitution analyses have proven that the physical interaction between the exosome core and MTR4 helicase, which promotes the exosome activity, is maintained by either MPP6 or RRP6. However, knowledge regarding the function of MPP6 with respect to in vivo exosome activity remains scarce. Here, we demonstrate a facilitative function of MPP6 that composes a specific part of MTR4-dependent substrate decay by the human exosome. Using RNA polymerase II-transcribed poly(A)+ substrate accumulation as an indicator of a perturbed exosome, we found functional redundancy between RRP6 and MPP6 in the decay of these poly(A)+ transcripts. MTR4 binding to the exosome core via MPP6 was essential for MPP6 to exert its redundancy with RRP6. However, at least for the decay of our identified exosome substrates, MTR4 recruitment by MPP6 was not functionally equivalent to recruitment by RRP6. Genome-wide classification of substrates based on their sensitivity to each exosome component revealed that MPP6 deals with a specific range of substrates and highlights the importance of MTR4 for their decay. Considering recent findings of competitive binding to the exosome between auxiliary complexes, our results suggest that the MPP6-incorporated MTR4-exosome complex is one of the multiple alternative complexes rather than the prevailing one.
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Affiliation(s)
- Naoko Fujiwara
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8502, Japan
| | - Maki Shigemoto
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8502, Japan
| | - Mizuki Hirayama
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8502, Japan
| | - Ken-Ichi Fujita
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8502, Japan.,Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Shigeto Seno
- Graduate School of Information Science and Technology, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hideo Matsuda
- Graduate School of Information Science and Technology, Osaka University, Suita, Osaka 565-0871, Japan
| | - Masami Nagahama
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan
| | - Seiji Masuda
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto 606-8502, Japan.,Department of Food Science and Nutrition, Faculty of Agriculture Kindai University, Nara, Nara 631-8505, Japan.,Agricultural Technology and Innovation Research Institute, Kindai University, Nara, Nara 631-8505, Japan.,Antiaging center, Kindai University, Higashiosaka, Osaka 577-8502, Japan
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85
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The Patterning and Proportion of Charged Residues in the Arginine-Rich Mixed-Charge Domain Determine the Membrane-Less Organelle Targeted by the Protein. Int J Mol Sci 2022; 23:ijms23147658. [PMID: 35887012 PMCID: PMC9324279 DOI: 10.3390/ijms23147658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/08/2022] [Accepted: 07/08/2022] [Indexed: 11/17/2022] Open
Abstract
Membrane-less organelles (MLOs) are formed by biomolecular liquid–liquid phase separation (LLPS). Proteins with charged low-complexity domains (LCDs) are prone to phase separation and localize to MLOs, but the mechanism underlying the distributions of such proteins to specific MLOs remains poorly understood. Recently, proteins with Arg-enriched mixed-charge domains (R-MCDs), primarily composed of R and Asp (D), were found to accumulate in nuclear speckles via LLPS. However, the process by which R-MCDs selectively incorporate into nuclear speckles is unknown. Here, we demonstrate that the patterning of charged amino acids and net charge determines the targeting of specific MLOs, including nuclear speckles and the nucleolus, by proteins. The redistribution of R and D residues from an alternately sequenced pattern to uneven blocky sequences caused a shift in R-MCD distribution from nuclear speckles to the nucleolus. In addition, the incorporation of basic residues in the R-MCDs promoted their localization to the MLOs and their apparent accumulation in the nucleolus. The R-MCD peptide with alternating amino acids did not undergo LLPS, whereas the blocky R-MCD peptide underwent LLPS with affinity to RNA, acidic poly-Glu, and the acidic nucleolar protein nucleophosmin, suggesting that the clustering of R residues helps avoid their neutralization by D residues and eventually induces R-MCD migration to the nucleolus. Therefore, the distribution of proteins to nuclear speckles requires the proximal positioning of D and R for the mutual neutralization of their charges.
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86
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Faber GP, Nadav-Eliyahu S, Shav-Tal Y. Nuclear speckles - a driving force in gene expression. J Cell Sci 2022; 135:275909. [PMID: 35788677 DOI: 10.1242/jcs.259594] [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] [Indexed: 12/20/2022] Open
Abstract
Nuclear speckles are dynamic membraneless bodies located in the cell nucleus. They harbor RNAs and proteins, many of which are splicing factors, that together display complex biophysical properties dictating nuclear speckle formation and maintenance. Although these nuclear bodies were discovered decades ago, only recently has in-depth genomic analysis begun to unravel their essential functions in modulation of gene activity. Major advancements in genomic mapping techniques combined with microscopy approaches have enabled insights into the roles nuclear speckles may play in enhancing gene expression, and how gene positioning to specific nuclear landmarks can regulate gene expression and RNA processing. Some studies have drawn a link between nuclear speckles and disease. Certain maladies either involve nuclear speckles directly or dictate the localization and reorganization of many nuclear speckle factors. This is most striking during viral infection, as viruses alter the entire nuclear architecture and highjack host machinery. As discussed in this Review, nuclear speckles represent a fascinating target of study not only to reveal the links between gene positioning, genome subcompartments and gene activity, but also as a potential target for therapeutics.
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Affiliation(s)
- Gabriel P Faber
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Shani Nadav-Eliyahu
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
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87
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Belmont AS. Nuclear Compartments: An Incomplete Primer to Nuclear Compartments, Bodies, and Genome Organization Relative to Nuclear Architecture. Cold Spring Harb Perspect Biol 2022; 14:a041268. [PMID: 34400557 PMCID: PMC9248822 DOI: 10.1101/cshperspect.a041268] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This work reviews nuclear compartments, defined broadly to include distinct nuclear structures, bodies, and chromosome domains. It first summarizes original cytological observations before comparing concepts of nuclear compartments emerging from microscopy versus genomic approaches and then introducing new multiplexed imaging approaches that promise in the future to meld both approaches. I discuss how previous models of radial distribution of chromosomes or the binary division of the genome into A and B compartments are now being refined by the recognition of more complex nuclear compartmentalization. The poorly understood question of how these nuclear compartments are established and maintained is then discussed, including through the modern perspective of phase separation, before moving on to address possible functions of nuclear compartments, using the possible role of nuclear speckles in modulating gene expression as an example. Finally, the review concludes with a discussion of future questions for this field.
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Affiliation(s)
- Andrew S Belmont
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
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88
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Gao S, Esparza M, Dehghan I, Aksenova V, Zhang K, Batten K, Ferretti MB, Begg BE, Cagatay T, Shay JW, García-Sastre A, Goldsmith EJ, Chen ZJ, Dasso M, Lynch KW, Cobb MH, Fontoura BMA. Nuclear speckle integrity and function require TAO2 kinase. Proc Natl Acad Sci U S A 2022; 119:e2206046119. [PMID: 35704758 PMCID: PMC9231605 DOI: 10.1073/pnas.2206046119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/16/2022] [Indexed: 11/18/2022] Open
Abstract
Nuclear speckles are non-membrane-bound organelles known as storage sites for messenger RNA (mRNA) processing and splicing factors. More recently, nuclear speckles have also been implicated in splicing and export of a subset of mRNAs, including the influenza virus M mRNA that encodes proteins required for viral entry, trafficking, and budding. However, little is known about how nuclear speckles are assembled or regulated. Here, we uncovered a role for the cellular protein kinase TAO2 as a constituent of nuclear speckles and as a factor required for the integrity of these nuclear bodies and for their functions in pre-mRNA splicing and trafficking. We found that a nuclear pool of TAO2 is localized at nuclear speckles and interacts with nuclear speckle factors involved in RNA splicing and nuclear export, including SRSF1 and Aly/Ref. Depletion of TAO2 or inhibition of its kinase activity disrupts nuclear speckle structure, decreasing the levels of several proteins involved in nuclear speckle assembly and splicing, including SC35 and SON. Consequently, splicing and nuclear export of influenza virus M mRNA were severely compromised and caused a disruption in the virus life cycle. In fact, low levels of TAO2 led to a decrease in viral protein levels and inhibited viral replication. Additionally, depletion or inhibition of TAO2 resulted in abnormal expression of a subset of mRNAs with key roles in viral replication and immunity. Together, these findings uncovered a function of TAO2 in nuclear speckle formation and function and revealed host requirements and vulnerabilities for influenza infection.
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Affiliation(s)
- Shengyan Gao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Matthew Esparza
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Ishmael Dehghan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Vasilisa Aksenova
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892
| | - Ke Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kimberly Batten
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Max B. Ferretti
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Bridget E. Begg
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Tolga Cagatay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jerry W. Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Elizabeth J. Goldsmith
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Zhijian J. Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892
| | - Kristen W. Lynch
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Melanie H. Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Beatriz M. A. Fontoura
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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89
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Hasenson SE, Alkalay E, Atrash MK, Boocholez A, Gershbaum J, Hochberg-Laufer H, Shav-Tal Y. The Association of MEG3 lncRNA with Nuclear Speckles in Living Cells. Cells 2022; 11:1942. [PMID: 35741072 PMCID: PMC9221825 DOI: 10.3390/cells11121942] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/12/2022] [Accepted: 06/13/2022] [Indexed: 02/04/2023] Open
Abstract
Nuclear speckles are nuclear bodies containing RNA-binding proteins as well as RNAs including long non-coding RNAs (lncRNAs). Maternally expressed gene 3 (MEG3) is a nuclear retained lncRNA found to associate with nuclear speckles. To understand the association dynamics of MEG3 lncRNA with nuclear speckles in living cells, we generated a fluorescently tagged MEG3 transcript that could be detected in real time. Under regular conditions, transient association of MEG3 with nuclear speckles was observed, including a nucleoplasmic fraction. Transcription or splicing inactivation conditions, known to affect nuclear speckle structure, showed prominent and increased association of MEG3 lncRNA with the nuclear speckles, specifically forming a ring-like structure around the nuclear speckles. This contrasted with metastasis-associated lung adenocarcinoma (MALAT1) lncRNA that is normally highly associated with nuclear speckles, which was released and dispersed in the nucleoplasm. Under normal conditions, MEG3 dynamically associated with the periphery of the nuclear speckles, but under transcription or splicing inhibition, MEG3 could also enter the center of the nuclear speckle. Altogether, using live-cell imaging approaches, we find that MEG3 lncRNA is a transient resident of nuclear speckles and that its association with this nuclear body is modulated by the levels of transcription and splicing activities in the cell.
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Affiliation(s)
| | | | | | | | | | | | - Yaron Shav-Tal
- The Mina & Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel; (S.E.H.); (E.A.); (M.K.A.); (A.B.); (J.G.); (H.H.-L.)
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90
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Decker CJ, Burke JM, Mulvaney PK, Parker R. RNA is required for the integrity of multiple nuclear and cytoplasmic membrane-less RNP granules. EMBO J 2022; 41:e110137. [PMID: 35355287 PMCID: PMC9058542 DOI: 10.15252/embj.2021110137] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 03/03/2022] [Accepted: 03/14/2022] [Indexed: 12/22/2022] Open
Abstract
Numerous membrane‐less organelles, composed of a combination of RNA and proteins, are observed in the nucleus and cytoplasm of eukaryotic cells. These RNP granules include stress granules (SGs), processing bodies (PBs), Cajal bodies, and nuclear speckles. An unresolved question is how frequently RNA molecules are required for the integrity of RNP granules in either the nucleus or cytosol. To address this issue, we degraded intracellular RNA in either the cytosol or the nucleus by the activation of RNase L and examined the impact of RNA loss on several RNP granules. We find the majority of RNP granules, including SGs, Cajal bodies, nuclear speckles, and the nucleolus, are altered by the degradation of their RNA components. In contrast, PBs and super‐enhancer complexes were largely not affected by RNA degradation in their respective compartments. RNA degradation overall led to the apparent dissolution of some membrane‐less organelles, whereas others reorganized into structures with altered morphology. These findings highlight a critical and widespread role of RNA in the organization of several RNP granules.
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Affiliation(s)
- Carolyn J Decker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA
| | - James M Burke
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Patrick K Mulvaney
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA.,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA
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91
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Abstract
The 14-3-3 family proteins are vital scaffold proteins that ubiquitously expressed in various tissues. They interact with numerous protein targets and mediate many cellular signaling pathways. The 14-3-3 binding motifs are often embedded in intrinsically disordered regions which are closely associated with liquid-liquid phase separation (LLPS). In the past ten years, LLPS has been observed for a variety of proteins and biological processes, indicating that LLPS plays a fundamental role in the formation of membraneless organelles and cellular condensates. While extensive investigations have been performed on 14-3-3 proteins, its involvement in LLPS is overlooked. To date, 14-3-3 proteins have not been reported to undergo LLPS alone or regulate LLPS of their binding partners. To reveal the potential involvement of 14-3-3 proteins in LLPS, in this review, we summarized the LLPS propensity of 14-3-3 binding partners and found that about one half of them may undergo LLPS spontaneously. We further analyzed the phase separation behavior of representative 14-3-3 binders and discussed how 14-3-3 proteins may be involved. By modulating the conformation and valence of interactions and recruiting other molecules, we speculate that 14-3-3 proteins can efficiently regulate the functions of their targets in the context of LLPS. Considering the critical roles of 14-3-3 proteins, there is an urgent need for investigating the involvement of 14-3-3 proteins in the phase separation process of their targets and the underling mechanisms.
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92
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Systematic mapping of nuclear domain-associated transcripts reveals speckles and lamina as hubs of functionally distinct retained introns. Mol Cell 2022; 82:1035-1052.e9. [PMID: 35182477 DOI: 10.1016/j.molcel.2021.12.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 12/10/2021] [Accepted: 12/11/2021] [Indexed: 12/22/2022]
Abstract
The nucleus is highly compartmentalized through the formation of distinct classes of membraneless domains. However, the composition and function of many of these structures are not well understood. Using APEX2-mediated proximity labeling and RNA sequencing, we surveyed human transcripts associated with nuclear speckles, several additional domains, and the lamina. Remarkably, speckles and lamina are associated with distinct classes of retained introns enriched in genes that function in RNA processing, translation, and the cell cycle, among other processes. In contrast to the lamina-proximal introns, retained introns associated with speckles are relatively short, GC-rich, and enriched for functional sites of RNA-binding proteins that are concentrated in these domains. They are also highly differentially regulated across diverse cellular contexts, including the cell cycle. Thus, our study provides a resource of nuclear domain-associated transcripts and further reveals speckles and lamina as hubs of distinct populations of retained introns linked to gene regulation and cell cycle progression.
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93
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Palacio M, Taatjes DJ. Merging Established Mechanisms with New Insights: Condensates, Hubs, and the Regulation of RNA Polymerase II Transcription. J Mol Biol 2022; 434:167216. [PMID: 34474085 PMCID: PMC8748285 DOI: 10.1016/j.jmb.2021.167216] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/16/2021] [Accepted: 08/19/2021] [Indexed: 01/17/2023]
Abstract
The regulation of RNA polymerase II (pol II) transcription requires a complex and context-specific array of proteins and protein complexes, as well as nucleic acids and metabolites. Every major physiological process requires coordinated transcription of specific sets of genes at the appropriate time, and a breakdown in this regulation is a hallmark of human disease. A proliferation of recent studies has revealed that many general transcription components, including sequence-specific, DNA-binding transcription factors, Mediator, and pol II itself, are capable of liquid-liquid phase separation, to form condensates that partition these factors away from the bulk aqueous phase. These findings hold great promise for next-level understanding of pol II transcription; however, many mechanistic aspects align with more conventional models, and whether phase separation per se regulates pol II activity in cells remains controversial. In this review, we describe the conventional and condensate-dependent models, and why their similarities and differences are important. We also compare and contrast these models in the context of genome organization and pol II transcription (initiation, elongation, and termination), and highlight the central role of RNA in these processes. Finally, we discuss mutations that disrupt normal partitioning of transcription factors, and how this may contribute to disease.
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Affiliation(s)
- Megan Palacio
- Dept. of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Dylan J. Taatjes
- Dept. of Biochemistry, University of Colorado, Boulder, CO, USA,corresponding author;
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94
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Maron MI, Casill AD, Gupta V, Roth JS, Sidoli S, Query CC, Gamble MJ, Shechter D. Type I and II PRMTs inversely regulate post-transcriptional intron detention through Sm and CHTOP methylation. eLife 2022; 11:e72867. [PMID: 34984976 PMCID: PMC8765754 DOI: 10.7554/elife.72867] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 01/03/2022] [Indexed: 12/26/2022] Open
Abstract
Protein arginine methyltransferases (PRMTs) are required for the regulation of RNA processing factors. Type I PRMT enzymes catalyze mono- and asymmetric dimethylation; Type II enzymes catalyze mono- and symmetric dimethylation. To understand the specific mechanisms of PRMT activity in splicing regulation, we inhibited Type I and II PRMTs and probed their transcriptomic consequences. Using the newly developed Splicing Kinetics and Transcript Elongation Rates by Sequencing (SKaTER-seq) method, analysis of co-transcriptional splicing demonstrated that PRMT inhibition resulted in altered splicing rates. Surprisingly, co-transcriptional splicing kinetics did not correlate with final changes in splicing of polyadenylated RNA. This was particularly true for retained introns (RI). By using actinomycin D to inhibit ongoing transcription, we determined that PRMTs post-transcriptionally regulate RI. Subsequent proteomic analysis of both PRMT-inhibited chromatin and chromatin-associated polyadenylated RNA identified altered binding of many proteins, including the Type I substrate, CHTOP, and the Type II substrate, SmB. Targeted mutagenesis of all methylarginine sites in SmD3, SmB, and SmD1 recapitulated splicing changes seen with Type II PRMT inhibition, without disrupting snRNP assembly. Similarly, mutagenesis of all methylarginine sites in CHTOP recapitulated the splicing changes seen with Type I PRMT inhibition. Examination of subcellular fractions further revealed that RI were enriched in the nucleoplasm and chromatin. Taken together, these data demonstrate that, through Sm and CHTOP arginine methylation, PRMTs regulate the post-transcriptional processing of nuclear, detained introns.
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Affiliation(s)
- Maxim I Maron
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
| | - Alyssa D Casill
- Department of Molecular Pharmacology, Albert Einstein College of MedicineBronxUnited States
| | - Varun Gupta
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - Jacob S Roth
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
| | - Charles C Query
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - Matthew J Gamble
- Department of Molecular Pharmacology, Albert Einstein College of MedicineBronxUnited States
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
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95
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Measuring Cytological Proximity of Chromosomal Loci to Defined Nuclear Compartments with TSA-seq. Methods Mol Biol 2022; 2532:145-186. [PMID: 35867249 DOI: 10.1007/978-1-0716-2497-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Distinct nuclear structures and bodies are involved in genome intranuclear positioning. Measuring proximity and relative distances of genomic loci to these nuclear compartments, and correlating this chromosome intranuclear positioning with epigenetic marks and functional readouts genome-wide, will be required to appreciate the true extent to which this nuclear compartmentalization contributes to regulation of genome functions. Here we present detailed protocols for TSA-seq, the first sequencing-based method for estimation of cytological proximity of chromosomal loci to spatially discrete nuclear structures, such as nuclear bodies or the nuclear lamina. TSA-seq uses Tyramide Signal Amplification (TSA) of immunostained cells to create a concentration gradient of tyramide-biotin free radicals which decays exponentially as a function of distance from a point-source target. Reaction of these free radicals with DNA deposits tyramide-biotin onto DNA as a function of distance from the point source. The relative enrichment of this tyramide-labeled DNA versus input DNA, revealed by DNA sequencing, can then be used as a "cytological ruler" to infer relative, or even absolute, mean chromosomal distances from immunostained nuclear compartments. TSA-seq mapping is highly reproducible and largely independent of the target protein or antibody choice for labeling a particular nuclear compartment. Our protocols include variations in TSA labeling conditions to provide varying spatial resolution as well as enhanced sensitivity. Our most streamlined protocol produces TSA-seq spatial mapping over a distance range of ~1 micron from major nuclear compartments using ~10-20 million cells.
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96
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Miyake S, Masuda S. Inhibition of mitochondrial complex III or dihydroorotate dehydrogenase (DHODH) triggers formation of poly(A) + RNA foci adjacent to nuclear speckles following activation of ATM (ataxia telangiectasia mutated). RNA Biol 2022; 19:1244-1255. [PMID: 36412986 PMCID: PMC9683070 DOI: 10.1080/15476286.2022.2146919] [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] [Indexed: 11/23/2022] Open
Abstract
Intracellular and intercellular signalling networks play an essential role in optimizing cellular homoeostasis and are thought to be partly reflected in nuclear mRNA dynamics. However, the regulation of nuclear mRNA dynamics by intracellular and intercellular signals remains largely unexplored, and research tools are lacking. Through an original screening based on the mRNA metabolic mechanism, we discovered that eight well-known inhibitors cause significant nuclear poly(A)+ RNA accumulation. Among these inhibitors, we discovered a new mRNA metabolic response in which the addition of antimycin A, an inhibitor of mitochondrial respiratory-chain complex III (complex III), resulted in a marked accumulation of poly(A)+ RNA near the nuclear speckles. Furthermore, dihydroorotate dehydrogenase (DHODH) inhibitors, a rate-limiting enzyme in the intracellular de novo pyrimidine synthesis reaction that specifically exchanges electrons with complex III, also caused a remarkable accumulation of nuclear poly(A)+ RNA adjacent to the nuclear speckles, which was abolished by extracellular uridine supply, indicating that the depletion of intracellular pyrimidine affects poly(A)+ RNA metabolism. Further analysis revealed that ataxia telangiectasia mutated (ATM), a serine and threonine kinase and a master regulator of DNA double-strand break (DSB) and nucleolar stress, is required for this poly(A)+ RNA nuclear accumulation phenomenon. This study reports new insights into novel aspects of nuclear poly(A)+ RNA metabolism, especially the relationship between mitochondrial respiratory-chain functions, pyrimidine metabolism, and nuclear RNA metabolism.
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Affiliation(s)
- Shuntaro Miyake
- Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Seiji Masuda
- Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto, Japan,Department of Food Science and Nutrition, Faculty of Agriculture, Kindai University, Nara, Japan,Agricultural Technology and Innovation Research Institute, Kindai University, Nara, Japan,Antiaging Center, Kindai University, Higashiosaka, Japan,CONTACT Seiji Masuda Department of Food Science and Nutrition, Faculty of Agriculture, Kindai University, Nara631-8505, Japan
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97
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Pinin Induces Epithelial-to-Mesenchymal Transition in Hepatocellular Carcinoma by Regulating m6A Modification. JOURNAL OF ONCOLOGY 2021; 2021:7529164. [PMID: 34917148 PMCID: PMC8670902 DOI: 10.1155/2021/7529164] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/20/2021] [Indexed: 12/12/2022]
Abstract
Pinin is a moonlighting protein localized in desmosomes and nucleus. It could promote the growth of hepatocellular carcinoma. Whether this protein can induce epithelial-to-mesenchymal transition (EMT) and malignant progression in HCC is unknown. This work found that Pinin prompts EMT in vitro and in vivo. Further mechanism study found that Pinin increases the level of N6-methyladenosine (m6A) modification of RNA by interacting with METTL3, which in turn induces snail1 expression. These findings suggest that Pinin induces EMT by regulating m6A modification and, thus, could be a potential anticancer target for HCC therapy.
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98
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Rivera C, Verbel-Vergara D, Arancibia D, Lappala A, González M, Guzmán F, Merello G, Lee JT, Andrés ME. Revealing RCOR2 as a regulatory component of nuclear speckles. Epigenetics Chromatin 2021; 14:51. [PMID: 34819154 PMCID: PMC8611983 DOI: 10.1186/s13072-021-00425-4] [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: 10/20/2021] [Accepted: 10/31/2021] [Indexed: 12/26/2022] Open
Abstract
Background Nuclear processes such as transcription and RNA maturation can be impacted by subnuclear compartmentalization in condensates and nuclear bodies. Here, we characterize the nature of nuclear granules formed by REST corepressor 2 (RCOR2), a nuclear protein essential for pluripotency maintenance and central nervous system development. Results Using biochemical approaches and high-resolution microscopy, we reveal that RCOR2 is localized in nuclear speckles across multiple cell types, including neurons in the brain. RCOR2 forms complexes with nuclear speckle components such as SON, SRSF7, and SRRM2. When cells are exposed to chemical stress, RCOR2 behaves as a core component of the nuclear speckle and is stabilized by RNA. In turn, nuclear speckle morphology appears to depend on RCOR2. Specifically, RCOR2 knockdown results larger nuclear speckles, whereas overexpressing RCOR2 leads to smaller and rounder nuclear speckles. Conclusion Our study suggests that RCOR2 is a regulatory component of the nuclear speckle bodies, setting this co-repressor protein as a factor that controls nuclear speckles behavior. Supplementary Information The online version contains supplementary material available at 10.1186/s13072-021-00425-4.
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Affiliation(s)
- Carlos Rivera
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile.,Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 6624, Boston, MA, 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, 02114, USA
| | - Daniel Verbel-Vergara
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile
| | - Duxan Arancibia
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile
| | - Anna Lappala
- Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 6624, Boston, MA, 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, 02114, USA
| | - Marcela González
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile
| | - Fabián Guzmán
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile
| | - Gianluca Merello
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 6624, Boston, MA, 02114, USA. .,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, 02114, USA.
| | - María Estela Andrés
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Avenida Del Libertador Bernardo O'Higgins 340, 8320000, Santiago, Chile.
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99
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Stemm-Wolf AJ, O’Toole ET, Sheridan RM, Morgan JT, Pearson CG. The SON RNA splicing factor is required for intracellular trafficking structures that promote centriole assembly and ciliogenesis. Mol Biol Cell 2021; 32:ar4. [PMID: 34406792 PMCID: PMC8684746 DOI: 10.1091/mbc.e21-06-0305] [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: 06/11/2021] [Revised: 07/16/2021] [Accepted: 07/23/2021] [Indexed: 11/11/2022] Open
Abstract
Control of centrosome assembly is critical for cell division, intracellular trafficking, and cilia. Regulation of centrosome number occurs through the precise duplication of centrioles that reside in centrosomes. Here we explored transcriptional control of centriole assembly and find that the RNA splicing factor SON is specifically required for completing procentriole assembly. Whole genome mRNA sequencing identified genes whose splicing and expression are affected by the reduction of SON, with an enrichment in genes involved in the microtubule (MT) cytoskeleton, centrosome, and centriolar satellites. SON is required for the proper splicing and expression of CEP131, which encodes a major centriolar satellite protein and is required to organize the trafficking and MT network around the centrosomes. This study highlights the importance of the distinct MT trafficking network that is intimately associated with nascent centrioles and is responsible for procentriole development and efficient ciliogenesis.
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Affiliation(s)
- Alexander J. Stemm-Wolf
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | | | - Ryan M. Sheridan
- RNA Biosciences Initiative (RBI), University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Jacob T. Morgan
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Chad G. Pearson
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
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100
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Williams LK, Mackay DR, Whitney MA, Couldwell GC, Sundquist WI, Ullman KS. Identification of abscission checkpoint bodies as structures that regulate ESCRT factors to control abscission timing. eLife 2021; 10:63743. [PMID: 34346309 PMCID: PMC8437436 DOI: 10.7554/elife.63743] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 08/03/2021] [Indexed: 11/21/2022] Open
Abstract
The abscission checkpoint regulates the ESCRT membrane fission machinery and thereby delays cytokinetic abscission to protect genomic integrity in response to residual mitotic errors. The checkpoint is maintained by Aurora B kinase, which phosphorylates multiple targets, including CHMP4C, a regulatory ESCRT-III subunit necessary for this checkpoint. We now report the discovery that cytoplasmic abscission checkpoint bodies (ACBs) containing phospho-Aurora B and tri-phospho-CHMP4C develop during an active checkpoint. ACBs are derived from mitotic interchromatin granules, transient mitotic structures whose components are housed in splicing-related nuclear speckles during interphase. ACB formation requires CHMP4C, and the ESCRT factor ALIX also contributes. ACB formation is conserved across cell types and under multiple circumstances that activate the checkpoint. Finally, ACBs retain a population of ALIX, and their presence correlates with delayed abscission and delayed recruitment of ALIX to the midbody where it would normally promote abscission. Thus, a cytoplasmic mechanism helps regulate midbody machinery to delay abscission. When a cell divides, it must first carefully duplicate its genetic information and package these copies into compartments housed in the two new cells. Errors in this process lead to genetic mistakes that trigger cancer or other harmful biological events. Quality control checks exist to catch errors before it is too late. This includes a final ‘abscission’ checkpoint right before the end of division, when the two new cells are still connected by a thin membrane bridge. If cells fail to pass this ‘no cut’ checkpoint, they delay severing their connection until the mistake is fixed. A group of proteins called ESCRTs is responsible for splitting the two cells apart if nothing is amiss. The abscission checkpoint blocks this process by altering certain proteins in the ESCRT complex, but exactly how this works is not yet clear. To find out more, Strohacker et al. imaged ESCRT factors in a new experimental system in which the abscission checkpoint is active in many cells. This showed that, in this context, certain ESCRT components were rerouted from the thread of membrane between the daughter cells to previously unknown structures, which Strohacker et al. named abscission checkpoint bodies. These entities also sequestered other factors that participate in the abscission checkpoint and factors that contribute to gene expression. These results are key to better understand how cells regulate their division; in particular, they provide a new framework to explore when this process goes wrong and contributes to cancer.
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Affiliation(s)
- Lauren K Williams
- Biochemistry and Oncological Sciences, University of Utah, Salt Lake City, United States
| | - Douglas R Mackay
- Oncological Sciences, University of Utah, Salt Lake City, United States
| | | | | | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
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