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Zhou X, Lv M, Duan Z, Liu W, Yan F, Liu J, Cui Y. CHTOP Promotes Microglia-Mediated Inflammation by Regulating Cell Metabolism and Inflammatory Gene Expression. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 212:677-688. [PMID: 38117276 DOI: 10.4049/jimmunol.2300572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 12/01/2023] [Indexed: 12/21/2023]
Abstract
During the initiation of the inflammatory response of microglia, the expression of many inflammation- and cell metabolism-related genes alters. However, how the transcription of inflammation- and metabolism-related genes are coordinately regulated during inflammation initiation is poorly understood. In this study, we found that LPS stimulation induced the expression of the chromatin target of PRMT1 (protein arginine methyltransferase 1) (CHTOP) in microglia. Knocking down CHTOP in microglia decreased proinflammatory cytokine expression. In addition, CHTOP knockdown altered cell metabolism, as both the upregulated genes were enriched in cell metabolism-related pathways and the metabolites profile was greatly altered based on untargeted metabolomics analysis. Mechanistically, CHTOP could directly bind the regulatory elements of inflammation and cell metabolism-related genes to regulate their transcription. In addition, knocking down CHTOP increased neuronal viability in vitro and alleviated microglia-mediated neuroinflammation in a systemic LPS treatment mouse model. Collectively, these data revealed CHTOP as a novel regulator to promote microglia-mediated neuroinflammation by coordinately regulating the transcription of inflammation and cell metabolism-related genes.
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Affiliation(s)
- Xin Zhou
- Institute of Neuroregeneration and Neurorehabilitation, Qingdao University, Qingdao, China
- Qingdao Medical College, Qingdao University, Qingdao, China
| | - Mengfei Lv
- Institute of Neuroregeneration and Neurorehabilitation, Qingdao University, Qingdao, China
- Qingdao Medical College, Qingdao University, Qingdao, China
| | - Zhongying Duan
- Institute of Neuroregeneration and Neurorehabilitation, Qingdao University, Qingdao, China
- Qingdao Medical College, Qingdao University, Qingdao, China
| | - Wenhao Liu
- Department of Interventional Radiology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Feng Yan
- Department of Emergency Medicine, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Jiake Liu
- Qingdao Medical College, Qingdao University, Qingdao, China
| | - Yu Cui
- Institute of Neuroregeneration and Neurorehabilitation, Qingdao University, Qingdao, China
- Qingdao Medical College, Qingdao University, Qingdao, China
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2
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Roth JF, Braunschweig U, Wu M, Li JD, Lin ZY, Larsen B, Weatheritt RJ, Gingras AC, Blencowe BJ. Systematic analysis of alternative exon-dependent interactome remodeling reveals multitasking functions of gene regulatory factors. Mol Cell 2023; 83:4222-4238.e10. [PMID: 38065061 DOI: 10.1016/j.molcel.2023.10.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 08/09/2023] [Accepted: 10/24/2023] [Indexed: 12/18/2023]
Abstract
Alternative splicing significantly expands biological complexity, particularly in the vertebrate nervous system. Increasing evidence indicates that developmental and tissue-dependent alternative exons often control protein-protein interactions; yet, only a minor fraction of these events have been characterized. Using affinity purification-mass spectrometry (AP-MS), we show that approximately 60% of analyzed neural-differential exons in proteins previously implicated in transcriptional regulation result in the gain or loss of interaction partners, which in some cases form unexpected links with coupled processes. Notably, a neural exon in Chtop regulates its interaction with the Prmt1 methyltransferase and DExD-Box helicases Ddx39b/a, affecting its methylation and activity in promoting RNA export. Additionally, a neural exon in Sap30bp affects interactions with RNA processing factors, modulating a critical function of Sap30bp in promoting the splicing of <100 nt "mini-introns" that control nuclear RNA levels. AP-MS is thus a powerful approach for elucidating the multifaceted functions of proteins imparted by context-dependent alternative exons.
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Affiliation(s)
- Jonathan F Roth
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | | | - Mingkun Wu
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jack Daiyang Li
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Zhen-Yuan Lin
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada
| | - Brett Larsen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada
| | - Robert J Weatheritt
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada; EMBL Australia, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Benjamin J Blencowe
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Hasenson SE, Shav‐Tal Y. Speculating on the Roles of Nuclear Speckles: How RNA‐Protein Nuclear Assemblies Affect Gene Expression. Bioessays 2020; 42:e2000104. [DOI: 10.1002/bies.202000104] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/17/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Sarah E. Hasenson
- The Mina & Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials Bar‐Ilan University Ramat Gan 4481400 Israel
| | - Yaron Shav‐Tal
- The Mina & Everard Goodman Faculty of Life Sciences and the Institute of Nanotechnology and Advanced Materials Bar‐Ilan University Ramat Gan 4481400 Israel
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Bartkowska K, Tepper B, Turlejski K, Djavadian RL. Roles of the exon junction complex components in the central nervous system: a mini review. Rev Neurosci 2019; 29:817-824. [PMID: 29791316 DOI: 10.1515/revneuro-2017-0113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 03/22/2018] [Indexed: 01/02/2023]
Abstract
The exon junction complex (EJC) consists of four core proteins: Magoh, RNA-binding motif 8A (Rbm8a, also known as Y14), eukaryotic initiation factor 4A3 (eIF4A3, also known as DDX48), and metastatic lymph node 51 (MLN51, also known as Casc3 or Barentsz), which are involved in the regulation of many processes occurring between gene transcription and protein translation. Its main role is to assemble into spliceosomes at the exon-exon junction of mRNA during splicing. It is, therefore, a range of functions concerning post-splicing events such as mRNA translocation, translation, and nonsense-mediated mRNA decay (NMD). Apart from this, proteins of the EJC control the splicing of specific pre-mRNAs, for example, splicing of the mapk transcript. Recent studies support essential functions of EJC proteins in oocytes and, after fertilization, in all stages of zygote development, as well as the growth of the embryo, including the development of the nervous system. During the development of the central nervous system (CNS), the EJC controls mitosis, regulating both symmetric and asymmetric cell divisions. Reduced levels of EJC components cause microcephaly. In the adult brain, Y14 and eIF4A3 appear to be involved in synaptic plasticity and in learning and memory. In this review, we focus on the involvement of EJC components in brain development and its functioning under normal conditions.
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Affiliation(s)
- Katarzyna Bartkowska
- Department of Molecular and Cellular Biology, Nencki Institute of Experimental Biology Polish Academy of Sciences, Warsaw, Poland
| | - Beata Tepper
- Department of Molecular and Cellular Biology, Nencki Institute of Experimental Biology Polish Academy of Sciences, Warsaw, Poland
| | - Kris Turlejski
- Faculty of Biology and Environmental Sciences, Cardinal Stefan Wyszynski University, Warsaw, Poland
| | - Ruzanna L Djavadian
- Department of Molecular and Cellular Biology, Nencki Institute of Experimental Biology Polish Academy of Sciences, Warsaw 02-093, Poland
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Feng X, Bai X, Ni J, Wasinger VC, Beretov J, Zhu Y, Graham P, Li Y. CHTOP in Chemoresistant Epithelial Ovarian Cancer: A Novel and Potential Therapeutic Target. Front Oncol 2019; 9:557. [PMID: 31380263 PMCID: PMC6660285 DOI: 10.3389/fonc.2019.00557] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/07/2019] [Indexed: 01/14/2023] Open
Abstract
Objective: Chemoresistance is a major challenge in epithelial ovarian cancer (EOC) treatment. Chromatin target of protein arginine methyltransferase (CHTOP) was identified as a potential biomarker in chemoresistant EOC cell lines using label-free LC-MS/MS quantitative proteomics. Thus, the aim of this study is to investigate the role of CHTOP in chemoresistant EOC and the underlying mechanism. Methods: The expression of CHTOP in human ovarian cancer cells and tissues was detected using immunofluorescence (IF), western blot (WB), and immunohistochemistry (IHC), respectively. Flow cytometry and TUNEL assay were employed to detect the effect of CHTOP knockdown (KD) in chemoresistant EOC cell apoptosis, while colony and sphere formation assays were used to evaluate its effect on cell stemness. The association of CHTOP with cell metastasis was determined using Matrigel invasion and wound-healing assays. Results: The higher level expression of CHTOP protein was found in chemoresistant EOC cells as compared to their sensitive parental cells or normal epithelial ovarian cells. Results from IHC and bioinformatic analysis showed CHTOP was highly expressed in human ovarian cancer tissues and associated with a poor progression-free survival in patients. In addition, CHTOP KD significantly enhanced cisplatin-induced apoptosis, reduced the stemness of chemoresistant EOC cells, and decreased their metastatic potential. Conclusion: Our findings suggest that CHTOP is associated with apoptosis, stemness, and metastasis in chemoresistant EOC cells and might be a promising target to overcome chemoresistance in EOC treatment.
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Affiliation(s)
- Xiaojie Feng
- Department of Gynaecological Oncology, Henan Cancer Hospital, Zhengzhou, China.,Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Xupeng Bai
- Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Jie Ni
- Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Valerie C Wasinger
- Bioanalytical Mass Spectrometry Facility, Mark Wainwright Analytical Centre, University of New South Wales Sydney, Sydney, NSW, Australia.,School of Medical Science, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Julia Beretov
- Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia.,Anatomical Pathology, NSW Health Pathology, St. George Hospital, Kogarah, NSW, Australia
| | - Ying Zhu
- Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Peter Graham
- Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Yong Li
- Cancer Care Centre, St. George Hospital, Kogarah, NSW, Australia.,St. George and Sutherland Clinical School, University of New South Wales Sydney, Sydney, NSW, Australia.,School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
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6
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Chromatin target of protein arginine methyltransferase regulates invasion, chemoresistance, and stemness in epithelial ovarian cancer. Biosci Rep 2019; 39:BSR20190016. [PMID: 30910850 PMCID: PMC6465198 DOI: 10.1042/bsr20190016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/08/2019] [Accepted: 03/23/2019] [Indexed: 12/21/2022] Open
Abstract
Ovarian cancer is one of the most common gynecological cancers with a high mortality rate in females. Chromatin target of protein arginine methyltransferase (CHTOP) is an important intracellular protein that regulates the transcriptional activation of several oncogenic genes in glioblastomagenesis and controls mature mRNA export as a component of TRanscription-Export complex. However, the role of CHTOP in ovarian cancer is unclear. In the present study, we investigated the correlation between tumor-derived CHTOP expression and prognosis and explored its role in the malignant behaviors of epithelial ovarian cancer cells. We found that higher expression of CHTOP was associated with a lower disease-free survival (DFS) rate in ovarian cancer patients. Also, CHTOP was highly expressed in human ovarian cancer tissues compared with normal and adjacent tissues. Moreover, compared with IGROV-1 cell line, higher expression of CHTOP was also confirmed in the malignant ovarian cancer cell lines (OV-90 and SK-OV-3). Further results from wound-healing and Matrigel assay showed that CHTOP knockdown significantly reduced the migration and invasion ability of OV-90 and SK-OV-3 cells, while colony formation assay and apoptosis detection showed that CHTOP knockdown markedly sensitized OV-90 and SK-OV-3 cells to cisplatin treatment by inducing apoptosis. Additionally, CHTOP silence also remarkably weakened the stemness of OV-90 and SK-OV-3 through inhibiting the protein expressions of several transcriptional or surface markers of cancer stem cells. These findings first suggest that CHTOP, as a highly expressed protein in ovarian cancer, is closely associated with the malignant phenotypes of epithelial ovarian cancer cells, including metastasis, chemoresistance, and stemness, which highlights a promising role of CHTOP in ovarian cancer targeted therapy.
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7
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Izumikawa K, Ishikawa H, Simpson RJ, Takahashi N. Modulating the expression of Chtop, a versatile regulator of gene-specific transcription and mRNA export. RNA Biol 2018; 15:849-855. [PMID: 29683372 DOI: 10.1080/15476286.2018.1465795] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
Chtop binds competitively to the arginine methyltransferases PRMT1 and PRMT5, thereby promoting the asymmetric or symmetric methylation of arginine residues, respectively. In cooperation with PRMT1, Chtop activates transcription of certain gene groups, such as the estrogen-inducible genes in breast cancer cells, the 5-hydroxymethylcytosine-modified genes involved in glioblastomagenesis, or the Zbp-89-dependent genes in erythroleukemia cells. Chtop also represses expression of the fetal γ-globin gene. In addition, Chtop is a component of the TREX complex that links transcription elongation to mRNA export. The regulation of Chtop expression is, therefore, a key process during the expression of certain gene groups and pathogenesis of certain diseases. Our recent study revealed that cellular levels of Chtop are strictly autoregulated by a mechanism involving intron retention and nonsense-mediated mRNA decay. Here, we summarize roles of Chtop in gene-specific expression and highlight our recent findings concerning the autoregulation of Chtop.
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Affiliation(s)
- Keiichi Izumikawa
- a Department of Applied Biological Science , United Graduate School of Agriculture, Tokyo University of Agriculture and Technology , Fuchu , Tokyo , Japan
| | - Hideaki Ishikawa
- a Department of Applied Biological Science , United Graduate School of Agriculture, Tokyo University of Agriculture and Technology , Fuchu , Tokyo , Japan
| | - Richard J Simpson
- b Global Innovation Research Organizations, Tokyo University of Agriculture and Technology , Fuchu , Tokyo , Japan.,c La Trobe Institute for Molecular Science (LIMS) LIMS Building 1, Room 412 La Trobe University , Bundoora Victoria , Australia
| | - Nobuhiro Takahashi
- a Department of Applied Biological Science , United Graduate School of Agriculture, Tokyo University of Agriculture and Technology , Fuchu , Tokyo , Japan.,b Global Innovation Research Organizations, Tokyo University of Agriculture and Technology , Fuchu , Tokyo , Japan
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8
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Wegener M, Müller-McNicoll M. Nuclear retention of mRNAs - quality control, gene regulation and human disease. Semin Cell Dev Biol 2017; 79:131-142. [PMID: 29102717 DOI: 10.1016/j.semcdb.2017.11.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/30/2017] [Accepted: 11/01/2017] [Indexed: 12/21/2022]
Abstract
Nuclear retention of incompletely spliced or mature mRNAs emerges as a novel, previously underappreciated layer of gene regulation, which enables the cell to rapidly respond to stress, viral infection, differentiation cues or changing environmental conditions. Focusing on mammalian cells, we discuss recent insights into the mechanisms and functions of nuclear retention, describe retention-promoting features in protein-coding transcripts and propose mechanisms for their regulated release into the cytoplasm. Moreover, we discuss examples of how aberrant nuclear retention of mRNAs may lead to human diseases.
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Affiliation(s)
- Marius Wegener
- RNA Regulation Group, Cluster of Excellence 'Macromolecular Complexes', Goethe University Frankfurt, Institute of Cell Biology and Neuroscience, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Michaela Müller-McNicoll
- RNA Regulation Group, Cluster of Excellence 'Macromolecular Complexes', Goethe University Frankfurt, Institute of Cell Biology and Neuroscience, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany.
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9
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Abstract
TRanscription and EXport (TREX) is a conserved multisubunit complex essential for embryogenesis, organogenesis and cellular differentiation throughout life. By linking transcription, mRNA processing and export together, it exerts a physiologically vital role in the gene expression pathway. In addition, this complex prevents DNA damage and regulates the cell cycle by ensuring optimal gene expression. As the extent of TREX activity in viral infections, amyotrophic lateral sclerosis and cancer emerges, the need for a greater understanding of TREX function becomes evident. A complete elucidation of the composition, function and interactions of the complex will provide the framework for understanding the molecular basis for a variety of diseases. This review details the known composition of TREX, how it is regulated and its cellular functions with an emphasis on mammalian systems.
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10
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Björk P, Wieslander L. Integration of mRNP formation and export. Cell Mol Life Sci 2017; 74:2875-2897. [PMID: 28314893 PMCID: PMC5501912 DOI: 10.1007/s00018-017-2503-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/06/2017] [Accepted: 03/07/2017] [Indexed: 12/13/2022]
Abstract
Expression of protein-coding genes in eukaryotes relies on the coordinated action of many sophisticated molecular machineries. Transcription produces precursor mRNAs (pre-mRNAs) and the active gene provides an environment in which the pre-mRNAs are processed, folded, and assembled into RNA–protein (RNP) complexes. The dynamic pre-mRNPs incorporate the growing transcript, proteins, and the processing machineries, as well as the specific protein marks left after processing that are essential for export and the cytoplasmic fate of the mRNPs. After release from the gene, the mRNPs move by diffusion within the interchromatin compartment, making up pools of mRNPs. Here, splicing and polyadenylation can be completed and the mRNPs recruit the major export receptor NXF1. Export competent mRNPs interact with the nuclear pore complex, leading to export, concomitant with compositional and conformational changes of the mRNPs. We summarize the integrated nuclear processes involved in the formation and export of mRNPs.
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Affiliation(s)
- Petra Björk
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
| | - Lars Wieslander
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
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11
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Izumikawa K, Yoshikawa H, Ishikawa H, Nobe Y, Yamauchi Y, Philipsen S, Simpson RJ, Isobe T, Takahashi N. Chtop (Chromatin target of Prmt1) auto-regulates its expression level via intron retention and nonsense-mediated decay of its own mRNA. Nucleic Acids Res 2016; 44:9847-9859. [PMID: 27683223 PMCID: PMC5175361 DOI: 10.1093/nar/gkw831] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 12/25/2022] Open
Abstract
Chtop (chromatin target of Prmt1) regulates various aspects of gene expression including transcription and mRNA export. Despite these important functions, the regulatory mechanism underlying Chtop expression remains undetermined. Using Chtop-expressing human cell lines, we demonstrate that Chtop expression is controlled via an autoregulatory negative feedback loop whereby Chtop binds its own mRNA to retain intron 2 during splicing; a premature termination codon present at the 5′ end of intron 2 leads to nonsense-mediated decay of the mRNA. We also show that Chtop interacts with exon 2 of Chtop mRNA via its arginine-glycine-rich (RG) domain, and with intron 2 via its N-terminal (N1) domain; both are required for retention of intron 2. In addition, we show that hnRNP H accelerates intron 2 splicing of Chtop mRNA in a manner dependent on Chtop expression level, suggesting that Chtop and hnRNP H regulate intron 2 retention of Chtop mRNA antagonistically. Thus, the present study provides a novel molecular mechanism by which mRNA and protein levels are constitutively regulated by intron retention.
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Affiliation(s)
- Keiichi Izumikawa
- Department of Applied Biological Science, United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.,Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan.,Global Innovation Research Organizations, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
| | - Harunori Yoshikawa
- Centre for Gene Regulation & Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Hideaki Ishikawa
- Department of Applied Biological Science, United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.,Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Yuko Nobe
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan.,Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Yoshio Yamauchi
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan.,Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Sjaak Philipsen
- Department of Cell Biology, Erasmus MC, 3015 GE Rotterdam, The Netherlands
| | - Richard J Simpson
- Global Innovation Research Organizations, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.,La Trobe Institute for Molecular Science (LIMS) LIMS Building 1, Room 412 La Trobe University, Bundoora, Victoria 3086, Australia
| | - Toshiaki Isobe
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan.,Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Nobuhiro Takahashi
- Department of Applied Biological Science, United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan .,Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan.,Global Innovation Research Organizations, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
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12
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Palazzo AF, Truong M. Single particle imaging of mRNAs crossing the nuclear pore: Surfing on the edge. Bioessays 2016; 38:744-50. [DOI: 10.1002/bies.201600038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
| | - Mathew Truong
- Department of Biochemistry; University of Toronto; Toronto ON Canada
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13
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Björk P, Persson JO, Wieslander L. Intranuclear binding in space and time of exon junction complex and NXF1 to premRNPs/mRNPs in vivo. J Cell Biol 2016; 211:63-75. [PMID: 26459599 PMCID: PMC4602041 DOI: 10.1083/jcb.201412017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The exon junction core complex associates with Balbiani ring (BR) premRNPs during transcription and in relation to splicing, whereas the export factor NXF1 is recruited in the interchromatin, and BR mRNPs become export competent only after passage through the interchromatin. Eukaryotic gene expression requires the ordered association of numerous factors with precursor messenger RNAs (premRNAs)/messenger RNAs (mRNAs) to achieve efficiency and regulation. Here, we use the Balbiani ring (BR) genes to demonstrate the temporal and spatial association of the exon junction complex (EJC) core with gene-specific endogenous premRNAs and mRNAs. The EJC core components bind cotranscriptionally to BR premRNAs during or very rapidly after splicing. The EJC core does not recruit the nonsense-mediated decay mediaters UPF2 and UPF3 until the BR messenger RNA protein complexes (mRNPs) enter the interchromatin. Even though several known adapters for the export factor NXF1 become part of BR mRNPs already at the gene, NXF1 binds to BR mRNPs only in the interchromatin. In steady state, a subset of the BR mRNPs in the interchromatin binds NXF1, UPF2, and UPF3. This binding appears to occur stochastically, and the efficiency approximately equals synthesis and export of the BR mRNPs. Our data provide unique in vivo information on how export competent eukaryotic mRNPs are formed.
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Affiliation(s)
- Petra Björk
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Jan-Olov Persson
- Department of Mathematics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Lars Wieslander
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
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14
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Sumoylation is Required for the Cytoplasmic Accumulation of a Subset of mRNAs. Genes (Basel) 2014; 5:982-1000. [PMID: 25333844 PMCID: PMC4276922 DOI: 10.3390/genes5040982] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 09/26/2014] [Accepted: 10/04/2014] [Indexed: 12/17/2022] Open
Abstract
In order to discover novel proteins that promote the nuclear export of newly synthesized mRNAs in mammalian cells, we carried out a limited RNAi screen for proteins required for the proper cytoplasmic distribution of a model intronless mRNA. From this screen we obtained two hits, Ubc9 (SUMO-conjugating E2 enzyme) and GANP (germinal center-associated nuclear protein). Depletion of Ubc9 inhibited the proper cytoplasmic distribution of certain overexpressed intronless mRNAs, while depletion of GANP affected all tested mRNAs. Depletion of Sae1, which is also required for sumoylation, partially inhibited the cytoplasmic distribution of our model mRNA. Interestingly, the block in cytoplasmic accumulation in Ubc9-depleted cells could be overcome if an intron was incorporated into the mRNA. Surprisingly, Ubc9-depleted cells had normal nuclear export of newly synthesized intronless mRNAs, indicating that the observed accumulation of the model mRNA in the nuclei of transfected cells was likely due to some more general perturbation. Indeed, depletion of Ubc9, coupled with the overexpression of the intronless mRNAs, caused the redistribution of the nuclear speckle protein SC35 to cytoplasmic foci. Our results suggest that sumoylation may play a role in the proper assembly of mRNPs and/or the distribution of key RNA binding proteins, and may thus contribute to general protein expression patterns.
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Björk P, Wieslander L. Mechanisms of mRNA export. Semin Cell Dev Biol 2014; 32:47-54. [PMID: 24813364 DOI: 10.1016/j.semcdb.2014.04.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 04/17/2014] [Indexed: 02/02/2023]
Abstract
Release of properly processed and assembled mRNPs from the actively transcribing genes, movement of the mRNPs through the interchromatin and interaction with the Nuclear Pore Complexes, leading to cytoplasmic export, are essential steps of eukaryotic gene expression. Here, we review these intranuclear gene expression steps.
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Affiliation(s)
- Petra Björk
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
| | - Lars Wieslander
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
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Akef A, Zhang H, Masuda S, Palazzo AF. Trafficking of mRNAs containing ALREX-promoting elements through nuclear speckles. Nucleus 2013; 4:326-40. [PMID: 23934081 PMCID: PMC3810340 DOI: 10.4161/nucl.26052] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
In vertebrates, the majority of mRNAs that encode secreted, membrane-bound or mitochondrial proteins contain RNA elements that activate an alternative mRNA nuclear export (ALREX) pathway. Here we demonstrate that mRNAs containing ALREX-promoting elements are trafficked through nuclear speckles. Although ALREX-promoting elements enhance nuclear speckle localization, additional features within the mRNA largely drive this process. Depletion of two TREX-associated RNA helicases, UAP56 and its paralog URH49, or inhibition of the TREX-associated nuclear transport factor, TAP, not only inhibits ALREX, but also appears to trap these mRNAs in nuclear speckles. mRNAs that contain ALREX-promoting elements associate with UAP56 in vivo. Finally, we demonstrate that mRNAs lacking a poly(A)-tail are not efficiently exported by the ALREX pathway and show enhanced association with nuclear speckles. Our data suggest that within the speckle, ALREX-promoting elements, in conjunction with the poly(A)-tail, likely stimulate UAP56/URH49 and TAP dependent steps that lead to the eventual egress of the export-competent mRNP from these structures.
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Affiliation(s)
- Abdalla Akef
- Department of Biochemistry; University of Toronto; Toronto, ON Canada; Division of Integrated Life Science; Graduate School of Biostudies; Kyoto University; Kyoto, Japan
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