1
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Schlusser N, González A, Pandey M, Zavolan M. Current limitations in predicting mRNA translation with deep learning models. Genome Biol 2024; 25:227. [PMID: 39164757 DOI: 10.1186/s13059-024-03369-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 08/07/2024] [Indexed: 08/22/2024] Open
Abstract
BACKGROUND The design of nucleotide sequences with defined properties is a long-standing problem in bioengineering. An important application is protein expression, be it in the context of research or the production of mRNA vaccines. The rate of protein synthesis depends on the 5' untranslated region (5'UTR) of the mRNAs, and recently, deep learning models were proposed to predict the translation output of mRNAs from the 5'UTR sequence. At the same time, large data sets of endogenous and reporter mRNA translation have become available. RESULTS In this study, we use complementary data obtained in two different cell types to assess the accuracy and generality of currently available models for predicting translational output. We find that while performing well on the data sets on which they were trained, deep learning models do not generalize well to other data sets, in particular of endogenous mRNAs, which differ in many properties from reporter constructs. CONCLUSIONS These differences limit the ability of deep learning models to uncover mechanisms of translation control and to predict the impact of genetic variation. We suggest directions that combine high-throughput measurements and machine learning to unravel mechanisms of translation control and improve construct design.
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Affiliation(s)
- Niels Schlusser
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland.
| | - Asier González
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Spain
| | - Muskan Pandey
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
- Current address: Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Mihaela Zavolan
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland.
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2
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Ottesen EW, Seo J, Luo D, Singh NN, Singh RN. A super minigene with a short promoter and truncated introns recapitulates essential features of transcription and splicing regulation of the SMN1 and SMN2 genes. Nucleic Acids Res 2024; 52:3547-3571. [PMID: 38214229 DOI: 10.1093/nar/gkad1259] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 12/19/2023] [Accepted: 12/30/2023] [Indexed: 01/13/2024] Open
Abstract
Here we report a Survival Motor Neuron 2 (SMN2) super minigene, SMN2Sup, encompassing its own promoter, all exons, their flanking intronic sequences and the entire 3'-untranslated region. We confirm that the pre-mRNA generated from SMN2Sup undergoes splicing to produce a translation-competent mRNA. We demonstrate that mRNA generated from SMN2Sup produces more SMN than an identical mRNA generated from a cDNA clone. We uncover that overexpression of SMN triggers skipping of exon 3 of SMN1/SMN2. We define the minimal promoter and regulatory elements associated with the initiation and elongation of transcription of SMN2. The shortened introns within SMN2Sup preserved the ability of camptothecin, a transcription elongation inhibitor, to induce skipping of exons 3 and 7 of SMN2. We show that intron 1-retained transcripts undergo nonsense-mediated decay. We demonstrate that splicing factor SRSF3 and DNA/RNA helicase DHX9 regulate splicing of multiple exons in the context of both SMN2Sup and endogenous SMN1/SMN2. Prevention of SMN2 exon 7 skipping has implications for the treatment of spinal muscular atrophy (SMA). We validate the utility of the super minigene in monitoring SMN levels upon splicing correction. Finally, we demonstrate how the super minigene could be employed to capture the cell type-specific effects of a pathogenic SMN1 mutation.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Diou Luo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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3
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Fanara S, Schloesser M, Joris M, De Franco S, Vandevenne M, Kerff F, Hanikenne M, Motte P. The Arabidopsis SR45 splicing factor bridges the splicing machinery and the exon-exon junction complex. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2280-2298. [PMID: 38180875 DOI: 10.1093/jxb/erae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/04/2024] [Indexed: 01/07/2024]
Abstract
The Arabidopsis splicing factor serine/arginine-rich 45 (SR45) contributes to several biological processes. The sr45-1 loss-of-function mutant exhibits delayed root development, late flowering, unusual numbers of floral organs, shorter siliques with decreased seed sets, narrower leaves and petals, and altered metal distribution. SR45 bears a unique RNA recognition motif (RRM) flanked by one serine/arginine-rich (RS) domain on both sides. Here, we studied the function of each SR45 domains by examining their involvement in: (i) the spatial distribution of SR45; (ii) the establishment of a protein-protein interaction network including spliceosomal and exon-exon junction complex (EJC) components; and (iii) the RNA binding specificity. We report that the endogenous SR45 promoter is active during vegetative and reproductive growth, and that the SR45 protein localizes in the nucleus. We demonstrate that the C-terminal arginine/serine-rich domain is a determinant of nuclear localization. We show that the SR45 RRM domain specifically binds purine-rich RNA motifs via three residues (H101, H141, and Y143), and is also involved in protein-protein interactions. We further show that SR45 bridges both mRNA splicing and surveillance machineries as a partner of EJC core components and peripheral factors, which requires phosphoresidues probably phosphorylated by kinases from both the CLK and SRPK families. Our findings provide insights into the contribution of each SR45 domain to both spliceosome and EJC assemblies.
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Affiliation(s)
- Steven Fanara
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
| | - Marie Schloesser
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
| | - Marine Joris
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
| | - Simona De Franco
- InBioS-Center for Protein Engineering, Laboratory of Biological Macromolecules, University of Liège, 4000, Liège, Belgium
| | - Marylène Vandevenne
- InBioS-Center for Protein Engineering, Laboratory of Biological Macromolecules, University of Liège, 4000, Liège, Belgium
| | - Frédéric Kerff
- InBioS-Center for Protein Engineering, Laboratory of Crystallography, University of Liège, 4000, Liège, Belgium
| | - Marc Hanikenne
- InBioS-PhytoSystems, Translational Plant Biology, University of Liège, 4000, Liège, Belgium
| | - Patrick Motte
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, 4000, Liège, Belgium
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4
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Cui H, Shi Q, Macarios CM, Schimmel P. Metabolic regulation of mRNA splicing. Trends Cell Biol 2024:S0962-8924(24)00025-4. [PMID: 38431493 DOI: 10.1016/j.tcb.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 03/05/2024]
Abstract
Alternative mRNA splicing enables the diversification of the proteome from a static genome and confers plasticity and adaptiveness on cells. Although this is often explored in development, where hard-wired programs drive the differentiation and specialization, alternative mRNA splicing also offers a way for cells to react to sudden changes in outside stimuli such as small-molecule metabolites. Fluctuations in metabolite levels and availability in particular convey crucial information to which cells react and adapt. We summarize and highlight findings surrounding the metabolic regulation of mRNA splicing. We discuss the principles underlying the biochemistry and biophysical properties of mRNA splicing, and propose how these could intersect with metabolite levels. Further, we present examples in which metabolites directly influence RNA-binding proteins and splicing factors. We also discuss the interplay between alternative mRNA splicing and metabolite-responsive signaling pathways. We hope to inspire future research to obtain a holistic picture of alternative mRNA splicing in response to metabolic cues.
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Affiliation(s)
- Haissi Cui
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.
| | - Qingyu Shi
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
| | | | - Paul Schimmel
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, CA 92037, USA.
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Das R, Panigrahi GK. Messenger RNA Surveillance: Current Understanding, Regulatory Mechanisms, and Future Implications. Mol Biotechnol 2024:10.1007/s12033-024-01062-4. [PMID: 38411790 DOI: 10.1007/s12033-024-01062-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/02/2024] [Indexed: 02/28/2024]
Abstract
Nonsense-mediated mRNA decay (NMD) is an evolutionarily conserved surveillance mechanism in eukaryotes primarily deployed to ensure RNA quality control by eliminating aberrant transcripts and also involved in modulating the expression of several physiological transcripts. NMD, the mRNA surveillance pathway, is a major form of gene regulation in eukaryotes. NMD serves as one of the most significant quality control mechanisms as it primarily scans the newly synthesized transcripts and differentiates the aberrant and non-aberrant transcripts. The synthesis of truncated proteins is restricted, which would otherwise lead to cellular dysfunctions. The up-frameshift factors (UPFs) play a central role in executing the NMD event, largely by recognizing and recruiting multiple protein factors that result in the decay of non-physiological mRNAs. NMD exhibits astounding variability in its ability across eukaryotes in an array of pathological and physiological contexts. The detailed understanding of NMD and the underlying molecular mechanisms remains blurred. This review outlines our current understanding of NMD, in regulating multifaceted cellular events during development and disease. It also attempts to identify unanswered questions that deserve further investigation.
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Affiliation(s)
- Rutupurna Das
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India
| | - Gagan Kumar Panigrahi
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India.
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6
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Palazzo AF, Qiu Y, Kang YM. mRNA nuclear export: how mRNA identity features distinguish functional RNAs from junk transcripts. RNA Biol 2024; 21:1-12. [PMID: 38091265 PMCID: PMC10732640 DOI: 10.1080/15476286.2023.2293339] [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] [Accepted: 12/05/2023] [Indexed: 12/18/2023] Open
Abstract
The division of the cellular space into nucleoplasm and cytoplasm promotes quality control mechanisms that prevent misprocessed mRNAs and junk RNAs from gaining access to the translational machinery. Here, we explore how properly processed mRNAs are distinguished from both misprocessed mRNAs and junk RNAs by the presence or absence of various 'identity features'.
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Affiliation(s)
| | - Yi Qiu
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yoon Mo Kang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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7
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Chang J, Shin MK, Park J, Hwang HJ, Locker N, Ahn J, Kim D, Baek D, Park Y, Lee Y, Boo SH, Kim HI, Kim YK. An interaction between eIF4A3 and eIF3g drives the internal initiation of translation. Nucleic Acids Res 2023; 51:10950-10969. [PMID: 37811880 PMCID: PMC10639049 DOI: 10.1093/nar/gkad763] [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: 11/04/2022] [Revised: 08/30/2023] [Accepted: 09/08/2023] [Indexed: 10/10/2023] Open
Abstract
An RNA structure or modified RNA sequences can provide a platform for ribosome loading and internal translation initiation. The functional significance of internal translation has recently been highlighted by the discovery that a subset of circular RNAs (circRNAs) is internally translated. However, the molecular mechanisms underlying the internal initiation of translation in circRNAs remain unclear. Here, we identify eIF3g (a subunit of eIF3 complex) as a binding partner of eIF4A3, a core component of the exon-junction complex (EJC) that is deposited onto spliced mRNAs and plays multiple roles in the regulation of gene expression. The direct interaction between eIF4A3-eIF3g serves as a molecular linker between the eIF4A3 and eIF3 complex, thereby facilitating internal ribosomal entry. Protein synthesis from in vitro-synthesized circRNA demonstrates eIF4A3-driven internal translation, which relies on the eIF4A3-eIF3g interaction. Furthermore, our transcriptome-wide analysis shows that efficient polysomal association of endogenous circRNAs requires eIF4A3. Notably, a subset of endogenous circRNAs can express a full-length intact protein, such as β-catenin, in an eIF4A3-dependent manner. Collectively, our results expand the understanding of the protein-coding potential of the human transcriptome, including circRNAs.
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Affiliation(s)
- Jeeyoon Chang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Min-Kyung Shin
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Joori Park
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Hyun Jung Hwang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Nicolas Locker
- Department of Microbial and Cellular Sciences, University of Surrey, Guildford GU2 7HX, UK
| | - Junhak Ahn
- School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Doyeon Kim
- School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Daehyun Baek
- School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Yeonkyoung Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Yujin Lee
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Sung Ho Boo
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Hyeong-In Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Yoon Ki Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
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8
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Lin HH, Chang CY, Huang YR, Shen CH, Wu YC, Chang KL, Lee YC, Lin YC, Ting WC, Chien HJ, Zheng YF, Lai CC, Hsiao KY. Exon Junction Complex Mediates the Cap-Independent Translation of Circular RNA. Mol Cancer Res 2023; 21:1220-1233. [PMID: 37527157 DOI: 10.1158/1541-7786.mcr-22-0877] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/22/2023] [Accepted: 07/25/2023] [Indexed: 08/03/2023]
Abstract
Evidence that circular RNAs (circRNA) serve as protein template is accumulating. However, how the cap-independent translation is controlled remains largely uncharacterized. Here, we show that the presence of intron and thus splicing promote cap-independent translation. By acquiring the exon junction complex (EJC) after splicing, the interaction between circRNA and ribosomes was promoted, thereby facilitating translation. Prevention of splicing by treatment with spliceosome inhibitor or mutating splicing signal hindered cap-independent translation of circRNA. Moreover, EJC-tethering using Cas13 technology reconstituted EJC-dependent circRNA translation. Finally, the level of a coding circRNA from succinate dehydrogenase assembly factor 2 (circSDHAF2) was found to be elevated in the tumorous tissues from patients with colorectal cancer, and shown to be critical in tumorigenesis of colorectal cancer in both cell and murine models. These findings reveal that EJC-dependent control of circSDHAF2 translation is involved in the regulation of oncogenic pathways. IMPLICATIONS EJC-mediated cap-independent translation of circRNA is implicated in the tumorigenesis of colorectal cancer.
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Affiliation(s)
- Hui-Hsuan Lin
- Doctoral Program in Tissue Engineering and Regenerative Medicine, National Chung Hsing University, Taichung, Taiwan
- Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Chiu-Yuan Chang
- Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Ren Huang
- Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Che-Hung Shen
- Doctoral Program in Tissue Engineering and Regenerative Medicine, National Chung Hsing University, Taichung, Taiwan
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan
| | - Yu-Chen Wu
- Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Kai-Li Chang
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Yueh-Chun Lee
- Department of Radiation Oncology, Chung Shan Medical University Hospital, Taichung, Taiwan
- School of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Ya-Chi Lin
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan
- Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung, Taiwan
| | - Wen-Chien Ting
- Division of Colorectal Surgery, Department of Surgery, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Han-Ju Chien
- Department of Biochemical Science and Technology, National Chiayi University, Chiayi, Taiwan
| | - Yi-Feng Zheng
- Institute of Molecular Biology, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Chien-Chen Lai
- Institute of Molecular Biology, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Kuei-Yang Hsiao
- Doctoral Program in Tissue Engineering and Regenerative Medicine, National Chung Hsing University, Taichung, Taiwan
- Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
- Doctoral Program in Translational Medicine, College of Life Sciences, National Chung Hsing University, Taichung
- Rong Hsing Research Center for Translational Medicine, College of Life Sciences, National Chung Hsing University, Taichung
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9
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Marhabaie M, Wharton TH, Kim SY, Wharton RP. Widespread regulation of the maternal transcriptome by Nanos in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555109. [PMID: 37693559 PMCID: PMC10491125 DOI: 10.1101/2023.08.28.555109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The translational repressor Nanos (Nos) regulates a single target, maternal hunchback (hb) mRNA, to govern abdominal segmentation in the early Drosophila embryo. Nos is recruited specifically to sites in the 3'-UTR of hb mRNA in collaboration with the sequence-specific RNA-binding protein Pumilio (Pum); on its own, Nos has no binding specificity. Nos is expressed at other stages of development, but very few mRNA targets that might mediate its action at these stages have been described. Nor has it been clear whether Nos is targeted to other mRNAs in concert with Pum or via other mechanisms. In this report, we identify mRNAs targeted by Nos via two approaches. In the first method, we identify mRNAs depleted upon expression of a chimera bearing Nos fused to the nonsense mediated decay (NMD) factor Upf1. We find that, in addition to hb, Upf1-Nos depletes ~2600 mRNAs from the maternal transcriptome in early embryos. Virtually all of these appear to be targeted in a canonical, hb-like manner in concert with Pum. In a second, more conventional approach, we identify mRNAs that are stabilized during the maternal zygotic transition (MZT) in embryos from nos- females. Most (86%) of the 1185 mRNAs regulated by Nos are also targeted by Upf1-Nos, validating use of the chimera. Approximately 60% of mRNAs targeted by Upf1-Nos are not stabilized in the absence of Nos. However, Upf1-Nos mRNA targets are hypo-adenylated and inefficiently translated at the ovary-embryo transition, whether or not they suffer Nos-dependent degradation in the embryo. We suggest that the late ovarian burst of Nos represses a large fraction of the maternal transcriptome, priming it for later degradation by other factors during the MZT in the embryo.
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Cao VD, Luo G, Korynta S, Liu H, Liang Y, Shanklin J, Altpeter F. Intron-mediated enhancement of DIACYLGLYCEROL ACYLTRANSFERASE1 expression in energycane promotes a step change for lipid accumulation in vegetative tissues. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:153. [PMID: 37838699 PMCID: PMC10576891 DOI: 10.1186/s13068-023-02393-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 09/09/2023] [Indexed: 10/16/2023]
Abstract
BACKGROUND Metabolic engineering for hyperaccumulation of lipids in vegetative tissues is a novel strategy for enhancing energy density and biofuel production from biomass crops. Energycane is a prime feedstock for this approach due to its high biomass production and resilience under marginal conditions. DIACYLGLYCEROL ACYLTRANSFERASE (DGAT) catalyzes the last and only committed step in the biosynthesis of triacylglycerol (TAG) and can be a rate-limiting enzyme for the production of TAG. RESULTS In this study, we explored the effect of intron-mediated enhancement (IME) on the expression of DGAT1 and resulting accumulation of TAG and total fatty acid (TFA) in leaf and stem tissues of energycane. To maximize lipid accumulation these evaluations were carried out by co-expressing the lipogenic transcription factor WRINKLED1 (WRI1) and the TAG protect factor oleosin (OLE1). Including an intron in the codon-optimized TmDGAT1 elevated the accumulation of its transcript in leaves by seven times on average based on 5 transgenic lines for each construct. Plants with WRI1 (W), DGAT1 with intron (Di), and OLE1 (O) expression (WDiO) accumulated TAG up to a 3.85% of leaf dry weight (DW), a 192-fold increase compared to non-modified energycane (WT) and a 3.8-fold increase compared to the highest accumulation under the intron-less gene combination (WDO). This corresponded to TFA accumulation of up to 8.4% of leaf dry weight, a 2.8-fold or 6.1-fold increase compared to WDO or WT, respectively. Co-expression of WDiO resulted in stem accumulations of TAG up to 1.14% of DW or TFA up to 2.08% of DW that exceeded WT by 57-fold or 12-fold and WDO more than twofold, respectively. Constitutive expression of these lipogenic "push pull and protect" factors correlated with biomass reduction. CONCLUSIONS Intron-mediated enhancement (IME) of the expression of DGAT resulted in a step change in lipid accumulation of energycane and confirmed that under our experimental conditions it is rate limiting for lipid accumulation. IME should be applied to other lipogenic factors and metabolic engineering strategies. The findings from this study may be valuable in developing a high biomass feedstock for commercial production of lipids and advanced biofuels.
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Affiliation(s)
- Viet Dang Cao
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA
| | - Guangbin Luo
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA
| | - Shelby Korynta
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA
| | - Hui Liu
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Upton, NY, USA
| | - Yuanxue Liang
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Upton, NY, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA.
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Upton, NY, USA.
- Biosciences Department, Brookhaven National Laboratory, Upton, NY, USA.
| | - Fredy Altpeter
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA.
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA.
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11
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Bohnsack KE, Yi S, Venus S, Jankowsky E, Bohnsack MT. Cellular functions of eukaryotic RNA helicases and their links to human diseases. Nat Rev Mol Cell Biol 2023; 24:749-769. [PMID: 37474727 DOI: 10.1038/s41580-023-00628-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/22/2023]
Abstract
RNA helicases are highly conserved proteins that use nucleoside triphosphates to bind or remodel RNA, RNA-protein complexes or both. RNA helicases are classified into the DEAD-box, DEAH/RHA, Ski2-like, Upf1-like and RIG-I families, and are the largest class of enzymes active in eukaryotic RNA metabolism - virtually all aspects of gene expression and its regulation involve RNA helicases. Mutation and dysregulation of these enzymes have been linked to a multitude of diseases, including cancer and neurological disorders. In this Review, we discuss the regulation and functional mechanisms of RNA helicases and their roles in eukaryotic RNA metabolism, including in transcription regulation, pre-mRNA splicing, ribosome assembly, translation and RNA decay. We highlight intriguing models that link helicase structure, mechanisms of function (such as local strand unwinding, translocation, winching, RNA clamping and displacing RNA-binding proteins) and biological roles, including emerging connections between RNA helicases and cellular condensates formed through liquid-liquid phase separation. We also discuss associations of RNA helicases with human diseases and recent efforts towards the design of small-molecule inhibitors of these pivotal regulators of eukaryotic gene expression.
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Affiliation(s)
- Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
| | - Soon Yi
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Sarah Venus
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Eckhard Jankowsky
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Moderna, Cambridge, MA, USA.
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
- Göttingen Centre for Molecular Biosciences, University of Göttingen, Göttingen, Germany.
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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Muñoz O, Lore M, Jagannathan S. The long and short of EJC-independent nonsense-mediated RNA decay. Biochem Soc Trans 2023; 51:1121-1129. [PMID: 37145092 DOI: 10.1042/bst20221131] [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: 01/11/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023]
Abstract
Nonsense-mediated RNA decay (NMD) plays a dual role as an RNA surveillance mechanism against aberrant transcripts containing premature termination codons and as a gene regulatory mechanism for normal physiological transcripts. This dual function is possible because NMD recognizes its substrates based on the functional definition of a premature translation termination event. An efficient mode of NMD target recognition involves the presence of exon-junction complexes (EJCs) downstream of the terminating ribosome. A less efficient, but highly conserved, mode of NMD is triggered by long 3' untranslated regions (UTRs) that lack EJCs (termed EJC-independent NMD). While EJC-independent NMD plays an important regulatory role across organisms, our understanding of its mechanism, especially in mammalian cells, is incomplete. This review focuses on EJC-independent NMD and discusses the current state of knowledge and factors that contribute to the variability in the efficiency of this mechanism.
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Affiliation(s)
- Oscar Muñoz
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A
| | - Mlana Lore
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A
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13
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Lupan BM, Solecki RA, Musso CM, Alsina FC, Silver DL. The exon junction complex component EIF4A3 is essential for mouse and human cortical progenitor mitosis and neurogenesis. Development 2023; 150:dev201619. [PMID: 37139782 PMCID: PMC10233715 DOI: 10.1242/dev.201619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 04/24/2023] [Indexed: 05/05/2023]
Abstract
Mutations in components of the exon junction complex (EJC) are associated with neurodevelopment and disease. In particular, reduced levels of the RNA helicase EIF4A3 cause Richieri-Costa-Pereira syndrome (RCPS) and copy number variations are linked to intellectual disability. Consistent with this, Eif4a3 haploinsufficient mice are microcephalic. Altogether, this implicates EIF4A3 in cortical development; however, the underlying mechanisms are poorly understood. Here, we use mouse and human models to demonstrate that EIF4A3 promotes cortical development by controlling progenitor mitosis, cell fate and survival. Eif4a3 haploinsufficiency in mice causes extensive cell death and impairs neurogenesis. Using Eif4a3;p53 compound mice, we show that apoptosis has the most impact on early neurogenesis, while additional p53-independent mechanisms contribute to later stages. Live imaging of mouse and human neural progenitors reveals that Eif4a3 controls mitosis length, which influences progeny fate and viability. These phenotypes are conserved, as cortical organoids derived from RCPS iPSCs exhibit aberrant neurogenesis. Finally, using rescue experiments we show that EIF4A3 controls neuron generation via the EJC. Altogether, our study demonstrates that EIF4A3 mediates neurogenesis by controlling mitosis duration and cell survival, implicating new mechanisms that underlie EJC-mediated disorders.
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Affiliation(s)
- Bianca M. Lupan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Rachel A. Solecki
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Camila M. Musso
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Fernando C. Alsina
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Debra L. Silver
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
- Departments of Cell Biology and Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
- Duke Institute for Brain Sciences and Duke Regeneration Center, Duke University Medical Center, Durham, NC 27710, USA
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14
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Mitra R, Rehman A, Singh KK, Jaganathan BG. Multifaceted roles of MAGOH Proteins. Mol Biol Rep 2023; 50:1931-1941. [PMID: 36396768 DOI: 10.1007/s11033-022-07904-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 07/14/2022] [Accepted: 08/31/2022] [Indexed: 11/18/2022]
Abstract
MAGOH and MAGOHB are paralog proteins that can substitute each other in the exon junction complex (EJC). The EJC is formed of core components EIF4A3, RBM8A, and MAGOH/MAGOHB. As a part of the EJC, MAGOH proteins are required for mRNA splicing, export, translation and nonsense-mediated mRNA decay (NMD). MAGOH is also essential for embryonic development and normal cellular functioning. The haploinsufficiency of MAGOH results in disorders such as microcephaly and cancer. The present review discusses the discovery of MAGOH, its paralog MAGOHB, their roles in cellular function as part of the EJC, and other cellular roles that are not directly associated with mRNA processing. We also discuss how MAGOH haploinsufficiency in cancer cells can be exploited to develop a novel targeted cancer treatment.
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Affiliation(s)
- Rumela Mitra
- Stem Cells and Cancer Biology Research Group, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India
| | - Ayushi Rehman
- RNA-Binding Proteins (RBPs) Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India
| | - Kusum Kumari Singh
- RNA-Binding Proteins (RBPs) Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India.
| | - Bithiah Grace Jaganathan
- Stem Cells and Cancer Biology Research Group, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India.
- Jyoti and Bhupat Mehta School of Health Sciences and Technology, Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India.
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15
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Lupan BM, Solecki RA, Musso CM, Alsina FC, Silver DL. The exon junction complex component EIF4A3 is essential for mouse and human cortical progenitor mitosis and neurogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.13.524010. [PMID: 36711736 PMCID: PMC9882224 DOI: 10.1101/2023.01.13.524010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mutations in components of the exon junction complex (EJC) are associated with neurodevelopment and disease. In particular, reduced levels of the RNA helicase EIF4A3 cause Richieri-Costa-Pereira Syndrome (RCPS) and CNVs are linked to intellectual disability. Consistent with this, Eif4a3 haploinsufficient mice are microcephalic. Altogether, this implicates EIF4A3 in cortical development; however, the underlying mechanisms are poorly understood. Here, we use mouse and human models to demonstrate that EIF4A3 promotes cortical development by controlling progenitor mitosis, cell fate, and survival. Eif4a3 haploinsufficiency in mice causes extensive cell death and impairs neurogenesis. Using Eif4a3 ; p53 compound mice, we show that apoptosis is most impactful for early neurogenesis, while additional p53-independent mechanisms contribute to later stages. Live imaging of mouse and human neural progenitors reveals Eif4a3 controls mitosis length, which influences progeny fate and viability. These phenotypes are conserved as cortical organoids derived from RCPS iPSCs exhibit aberrant neurogenesis. Finally, using rescue experiments we show that EIF4A3 controls neuron generation via the EJC. Altogether, our study demonstrates that EIF4A3 mediates neurogenesis by controlling mitosis duration and cell survival, implicating new mechanisms underlying EJC-mediated disorders. Summary statement This study shows that EIF4A3 mediates neurogenesis by controlling mitosis duration in both mouse and human neural progenitors, implicating new mechanisms underlying neurodevelopmental disorders.
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16
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Assoni AF, Foijer F, Zatz M. Amyotrophic Lateral Sclerosis, FUS and Protein Synthesis Defects. Stem Cell Rev Rep 2022; 19:625-638. [PMID: 36515764 DOI: 10.1007/s12015-022-10489-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that mainly affects the motor system. It is a very heterogeneous disorder, so far more than 40 genes have been described as responsible for ALS. The cause of motor neuron degeneration is not yet fully understood, but there is consensus in the literature that it is the result of a complex interplay of several pathogenic processes, which include alterations in nucleocytoplasmic transport, defects in transcription and splicing, altered formation and/or disassembly of stress granules and impaired proteostasis. These defects result in protein aggregation, impaired DNA repair, mitochondrial dysfunction and oxidative stress, neuroinflammation, impaired axonal transport, impaired vesicular transport, excitotoxicity, as well as impaired calcium influx. We argue here that all the above functions ultimately lead to defects in protein synthesis. Fused in Sarcoma (FUS) is one of the genes associated with ALS. It causes ALS type 6 when mutated and is found mislocalized to the cytoplasm in the motor neurons of sporadic ALS patients (without FUS mutations). In addition, FUS plays a role in all cellular functions that are impaired in degenerating motor neurons. Moreover, ALS patients with FUS mutations present the first symptoms significantly earlier than in other forms of the disease. Therefore, the aim of this review is to further discuss ALS6, detail the cellular functions of FUS, and suggest that the localization of FUS, as well as protein synthesis rates, could be hallmarks of the ALS phenotype and thus good therapeutic targets.
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Affiliation(s)
- Amanda Faria Assoni
- Human Genome and Stem Cell Research Center, Institute of Biosciences, University of São Paulo, 055080-090, CidadeUniversitária, São Paulo, Brazil.,European Research Institute for the Biology of Ageing, University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Floris Foijer
- European Research Institute for the Biology of Ageing, University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Mayana Zatz
- Human Genome and Stem Cell Research Center, Institute of Biosciences, University of São Paulo, 055080-090, CidadeUniversitária, São Paulo, Brazil.
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17
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The PNUTS-PP1 complex acts as an intrinsic barrier to herpesvirus KSHV gene expression and replication. Nat Commun 2022; 13:7447. [PMID: 36460671 PMCID: PMC9718767 DOI: 10.1038/s41467-022-35268-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Control of RNA Polymerase II (pol II) elongation is a critical component of gene expression in mammalian cells. The PNUTS-PP1 complex controls elongation rates, slowing pol II after polyadenylation sites to promote termination. The Kaposi's sarcoma-associated herpesvirus (KSHV) co-opts pol II to express its genes, but little is known about its regulation of pol II elongation. We identified PNUTS as a suppressor of a KSHV reporter gene in a genome-wide CRISPR screen. PNUTS depletion enhances global KSHV gene expression and overall viral replication. Mechanistically, PNUTS requires PP1 interaction, binds viral RNAs downstream of polyadenylation sites, and restricts transcription readthrough of viral genes. Surprisingly, PNUTS also represses productive elongation at the 5´ ends of the KSHV reporter and the KSHV T1.4 RNA. From these data, we conclude that PNUTS' activity constitutes an intrinsic barrier to KSHV replication likely by suppressing pol II elongation at promoter-proximal regions.
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18
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Ganesan R, Mangkalaphiban K, Baker RE, He F, Jacobson A. Ribosome-bound Upf1 forms distinct 80S complexes and conducts mRNA surveillance. RNA (NEW YORK, N.Y.) 2022; 28:1621-1642. [PMID: 36192133 PMCID: PMC9670811 DOI: 10.1261/rna.079416.122] [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] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
Upf1, Upf2, and Upf3, the central regulators of nonsense-mediated mRNA decay (NMD), appear to exercise their NMD functions while bound to elongating ribosomes, and evidence for this conclusion is particularly compelling for Upf1. Hence, we used selective profiling of yeast Upf1:ribosome association to define that step in greater detail, understand whether the nature of the mRNA being translated influences Upf1:80S interaction, and elucidate the functions of ribosome-associated Upf1. Our approach has allowed us to clarify the timing and specificity of Upf1 association with translating ribosomes, obtain evidence for a Upf1 mRNA surveillance function that precedes the activation of NMD, identify a unique ribosome state that generates 37-43 nt ribosome footprints whose accumulation is dependent on Upf1's ATPase activity, and demonstrate that a mutated form of Upf1 can interfere with normal translation termination and ribosome release. In addition, our results strongly support the existence of at least two distinct functional Upf1 complexes in the NMD pathway.
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Affiliation(s)
- Robin Ganesan
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Kotchaphorn Mangkalaphiban
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Richard E Baker
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Feng He
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
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19
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Yang TH, Hsu CW, Wang YX, Yu CH, Rathod J, Tseng YY, Wu WS. YMLA: A comparative platform to carry out functional enrichment analysis for multiple gene lists in yeast. Comput Biol Med 2022; 151:106314. [PMID: 36455295 DOI: 10.1016/j.compbiomed.2022.106314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/23/2022] [Accepted: 11/13/2022] [Indexed: 11/16/2022]
Abstract
Comparative analysis among multiple gene lists on their functional features is now a routine task due to the advancement of high-throughput experiments. Several enrichment analysis tools were developed in the past. However, these tools mainly focus on one gene list and contain only gene ontology or interaction features. What makes it worse, comparative investigation and customized feature set reanalysis are still unavailable. Therefore, we constructed the YMLA (Yeast Multiple List Analyzer) platform in this research. YMLA includes 39 yeast features and facilitates comparative analysis among multiple gene lists via tabular views, heatmaps, and network plots. Moreover, the customized feature set reanalysis function was implemented in YMLA to help form mechanism hypotheses based on a selected enriched feature subset. We demonstrated the biological applicability of YMLA via example lists consisting of genes with top/bottom translation efficiency values. The analysis results provided by YMLA reveal novel facts consistent with previous experiments. YMLA is available at https://cosbi7.ee.ncku.edu.tw/YMLA/.
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Affiliation(s)
- Tzu-Hsien Yang
- Department of Biomedical Engineering, National Cheng Kung University, University Road, 701 Tainan, Taiwan.
| | - Chia-Wei Hsu
- Department of Electrical Engineering, National Cheng Kung University, University Road, 701 Tainan, Taiwan.
| | - Yan-Xiang Wang
- Department of Electrical Engineering, National Cheng Kung University, University Road, 701 Tainan, Taiwan.
| | - Chien-Hung Yu
- Department of Biochemistry and Molecular Biology, National Cheng Kung University, University Road, 701 Tainan, Taiwan.
| | - Jagat Rathod
- Department of Environmental Biotechnology, Gujarat Biotechnology University, Gujarat International Finance Tec (GIFT)-City, Gandhinagar 382355, Gujarat, India.
| | - Yan-Yuan Tseng
- Center for Molecular Medicine and Genetics, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
| | - Wei-Sheng Wu
- Department of Electrical Engineering, National Cheng Kung University, University Road, 701 Tainan, Taiwan.
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20
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Slobodin B, Sehrawat U, Lev A, Hayat D, Zuckerman B, Fraticelli D, Ogran A, Ben-Shmuel A, Bar-David E, Levy H, Ulitsky I, Dikstein R. Cap-independent translation and a precisely located RNA sequence enable SARS-CoV-2 to control host translation and escape anti-viral response. Nucleic Acids Res 2022; 50:8080-8092. [PMID: 35849342 PMCID: PMC9371909 DOI: 10.1093/nar/gkac615] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 06/09/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022] Open
Abstract
Translation of SARS-CoV-2-encoded mRNAs by the host ribosomes is essential for its propagation. Following infection, the early expressed viral protein NSP1 binds the ribosome, represses translation, and induces mRNA degradation, while the host elicits an anti-viral response. The mechanisms enabling viral mRNAs to escape this multifaceted repression remain obscure. Here we show that expression of NSP1 leads to destabilization of multi-exon cellular mRNAs, while intron-less transcripts, such as viral mRNAs and anti-viral interferon genes, remain relatively stable. We identified a conserved and precisely located cap-proximal RNA element devoid of guanosines that confers resistance to NSP1-mediated translation inhibition. Importantly, the primary sequence rather than the secondary structure is critical for protection. We further show that the genomic 5'UTR of SARS-CoV-2 drives cap-independent translation and promotes expression of NSP1 in an eIF4E-independent and Torin1-resistant manner. Upon expression, NSP1 further enhances cap-independent translation. However, the sub-genomic 5'UTRs are highly sensitive to eIF4E availability, rendering viral propagation partially sensitive to Torin1. We conclude that the combined NSP1-mediated degradation of spliced mRNAs and translation inhibition of single-exon genes, along with the unique features present in the viral 5'UTRs, ensure robust expression of viral mRNAs. These features can be exploited as potential therapeutic targets.
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Affiliation(s)
- Boris Slobodin
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Urmila Sehrawat
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.,Department of Cancer Biology and Genetics, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Anastasia Lev
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniel Hayat
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Binyamin Zuckerman
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.,Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA
| | - Davide Fraticelli
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ariel Ogran
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Amir Ben-Shmuel
- Department of Infectious Diseases, Israel Institute for Biological Research, Ness-Ziona 7410001 Israel
| | - Elad Bar-David
- Department of Infectious Diseases, Israel Institute for Biological Research, Ness-Ziona 7410001 Israel
| | - Haim Levy
- Department of Infectious Diseases, Israel Institute for Biological Research, Ness-Ziona 7410001 Israel
| | - Igor Ulitsky
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rivka Dikstein
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
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21
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The Physiological Roles of the Exon Junction Complex in Development and Diseases. Cells 2022; 11:cells11071192. [PMID: 35406756 PMCID: PMC8997533 DOI: 10.3390/cells11071192] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/19/2022] [Accepted: 03/24/2022] [Indexed: 01/12/2023] Open
Abstract
The exon junction complex (EJC) becomes an increasingly important regulator of early gene expression in the central nervous system (CNS) and other tissues. The EJC is comprised of three core proteins: RNA-binding motif 8A (RBM8A), Mago homolog (MAGOH), eukaryotic initiation factor 4A3 (EIF4A3), and a peripheral EJC factor, metastatic lymph node 51 (MLN51), together with various auxiliary factors. The EJC is assembled specifically at exon-exon junctions on mRNAs, hence the name of the complex. The EJC regulates multiple levels of gene expression, from splicing to translation and mRNA degradation. The functional roles of the EJC have been established as crucial to the normal progress of embryonic and neurological development, with wide ranging implications on molecular, cellular, and organism level function. Dysfunction of the EJC has been implicated in multiple developmental and neurological diseases. In this review, we discuss recent progress on the EJC’s physiological roles.
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22
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Borna S, Lee E, Sato Y, Bacchetta R. Towards gene therapy for IPEX syndrome. Eur J Immunol 2022; 52:705-716. [PMID: 35355253 PMCID: PMC9322407 DOI: 10.1002/eji.202149210] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/29/2022] [Accepted: 03/29/2022] [Indexed: 11/30/2022]
Abstract
Immune dysregulation polyendocrinopathy enteropathy X linked (IPEX) syndrome is an uncurable disease of the immune system, with immune dysregulation that is caused by mutations in FOXP3. Current treatment options, such as pharmacological immune suppression and allogeneic hematopoietic stem cell transplantation, have been beneficial but present limitations, and their life‐long consequences are ill‐defined. Other similar blood monogenic diseases have been successfully treated using gene transfer in autologous patient cells, thus providing an effective and less invasive therapeutic. Development of gene therapy for patients with IPEX is particularly challenging because successful strategies must restore the complex expression profile of the transcription factor FOXP3, ensuring it is tightly regulated and its cell subset‐specific roles are maintained. This review summarizes current efforts toward achieving gene therapy to treat immune dysregulation in IPEX patients.
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Affiliation(s)
- Simon Borna
- Department of Pediatrics, Division of Hematology, Oncology, Stem Cell Transplantation and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Esmond Lee
- Department of Pediatrics, Division of Hematology, Oncology, Stem Cell Transplantation and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Yohei Sato
- Department of Pediatrics, Division of Hematology, Oncology, Stem Cell Transplantation and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Rosa Bacchetta
- Department of Pediatrics, Division of Hematology, Oncology, Stem Cell Transplantation and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Center for Definitive and Curative Medicine, Stanford University School of Medicine, Stanford, CA, USA
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23
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Ho CH, Paolantoni C, Bawankar P, Tang Z, Brown S, Roignant J, Treisman JE. An exon junction complex-independent function of Barentsz in neuromuscular synapse growth. EMBO Rep 2022; 23:e53231. [PMID: 34726300 PMCID: PMC8728599 DOI: 10.15252/embr.202153231] [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: 05/10/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 01/07/2023] Open
Abstract
The exon junction complex controls the translation, degradation, and localization of spliced mRNAs, and three of its core subunits also play a role in splicing. Here, we show that a fourth subunit, Barentsz, has distinct functions within and separate from the exon junction complex in Drosophila neuromuscular development. The distribution of mitochondria in larval muscles requires Barentsz as well as other exon junction complex subunits and is not rescued by a Barentsz transgene in which residues required for binding to the core subunit eIF4AIII are mutated. In contrast, interactions with the exon junction complex are not required for Barentsz to promote the growth of neuromuscular synapses. We find that the Activin ligand Dawdle shows reduced expression in barentsz mutants and acts downstream of Barentsz to control synapse growth. Both barentsz and dawdle are required in motor neurons, muscles, and glia for normal synapse growth, and exogenous Dawdle can rescue synapse growth in the absence of barentsz. These results identify a biological function for Barentsz that is independent of the exon junction complex.
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Affiliation(s)
- Cheuk Hei Ho
- Skirball Institute for Biomolecular Medicine and Department of Cell BiologyNYU School of MedicineNew YorkNYUSA
| | - Chiara Paolantoni
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
| | - Praveen Bawankar
- Institute of Pharmaceutical and Biomedical SciencesJohannes Gutenberg‐University MainzMainzGermany
| | - Zuojian Tang
- Center for Health Informatics and BioinformaticsNYU Langone Medical CenterNew YorkNYUSA
- Present address:
Computational Biology at Ridgefield US, Global Computational Biology and Digital ScienceBoehringer IngelheimRidgefieldCTUSA
| | - Stuart Brown
- Center for Health Informatics and BioinformaticsNYU Langone Medical CenterNew YorkNYUSA
- Present address:
ExxonMobil Corporate Strategic ResearchAnnandaleNJUSA
| | - Jean‐Yves Roignant
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
- Institute of Pharmaceutical and Biomedical SciencesJohannes Gutenberg‐University MainzMainzGermany
| | - Jessica E Treisman
- Skirball Institute for Biomolecular Medicine and Department of Cell BiologyNYU School of MedicineNew YorkNYUSA
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24
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Inoue AH, Domingues PF, Serpeloni M, Hiraiwa PM, Vidal NM, Butterfield ER, del Pino RC, Ludwig A, Boehm C, Field MC, Ávila AR. Proteomics uncovers novel components of an interactive protein network supporting RNA export in trypanosomes. Mol Cell Proteomics 2022; 21:100208. [PMID: 35091090 PMCID: PMC8938319 DOI: 10.1016/j.mcpro.2022.100208] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 01/15/2022] [Accepted: 01/24/2022] [Indexed: 11/03/2022] Open
Abstract
In trypanosomatids, transcription is polycistronic and all mRNAs are processed by trans-splicing, with export mediated by noncanonical mechanisms. Although mRNA export is central to gene regulation and expression, few orthologs of proteins involved in mRNA export in higher eukaryotes are detectable in trypanosome genomes, necessitating direct identification of protein components. We previously described conserved mRNA export pathway components in Trypanosoma cruzi, including orthologs of Sub2, a component of the TREX complex, and eIF4AIII (previously Hel45), a core component of the exon junction complex (EJC). Here, we searched for protein interactors of both proteins using cryomilling and mass spectrometry. Significant overlap between TcSub2 and TceIF4AIII-interacting protein cohorts suggests that both proteins associate with similar machinery. We identified several interactions with conserved core components of the EJC and multiple additional complexes, together with proteins specific to trypanosomatids. Additional immunoisolations of kinetoplastid-specific proteins both validated and extended the superinteractome, which is capable of supporting RNA processing from splicing through to nuclear export and cytoplasmic events. We also suggest that only proteomics is powerful enough to uncover the high connectivity between multiple aspects of mRNA metabolism and to uncover kinetoplastid-specific components that create a unique amalgam to support trypanosome mRNA maturation. Gene expression in trypanosomes is mediated by noncanonical mechanisms. Trypanosome mRNA nuclear export system comprises unique proteins to kinetoplastids. The present work highlights an amalgam of kinetoplastid-specific and conserved components. Our data support a highly coupled mRNA maturation pathway.
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25
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Mesa-Perez M, Hamilton PT, Miranda A, Brodie N, O’Sullivan C, Christie J, Ryan B, Chow R, Goodlett D, Nelson C, Howard P. OUP accepted manuscript. Nucleic Acids Res 2022; 50:1620-1638. [PMID: 35104878 PMCID: PMC8860587 DOI: 10.1093/nar/gkac033] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/29/2021] [Accepted: 01/13/2022] [Indexed: 12/03/2022] Open
Abstract
The life of RNA polymerase II (RNAPII) transcripts is shaped by the dynamic formation of mutually exclusive ribonucleoprotein complexes (RNPs) that direct transcript biogenesis and turnover. A key regulator of RNA metabolism in the nucleus is the scaffold protein ARS2 (arsenic resistance protein 2), bound to the cap binding complex (CBC). We report here that alternative splicing of ARS2′s intron 5, generates cytoplasmic isoforms that lack 270 amino acids from the N-terminal of the protein and are functionally distinct from nuclear ARS2. Switching of ARS2 isoforms within the CBC in the cytoplasm has dramatic functional consequences, changing ARS2 from a NMD inhibitor to a NMD promoter that enhances the binding of UPF1 to NCBP1 and ERF1, favouring SURF complex formation, SMG7 recruitment and transcript degradation. ARS2 isoform exchange is also relevant during arsenic stress, where cytoplasmic ARS2 promotes a global response to arsenic in a CBC-independent manner. We propose that ARS2 isoform switching promotes the proper recruitment of RNP complexes during NMD and the cellular response to arsenic stress. The existence of non-redundant ARS2 isoforms is relevant for cell homeostasis, and stress response.
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Affiliation(s)
- Monica Mesa-Perez
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | | | - Alex Miranda
- Deeley Research Centre, BC Cancer, Victoria, BC V8R 6V5, Canada
| | - Nicholas Brodie
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
- University of Victoria Genome BC Proteomics Centre, Vancouver Island Technology Park, Victoria, BC V8Z 7X8, Canada
| | - Connor O’Sullivan
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Jennifer Christie
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Bridget C Ryan
- Department of Biology, University of Victoria, Victoria, BC V8W 3N5, Canada
| | - Robert L Chow
- Department of Biology, University of Victoria, Victoria, BC V8W 3N5, Canada
| | - David Goodlett
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
- University of Victoria Genome BC Proteomics Centre, Vancouver Island Technology Park, Victoria, BC V8Z 7X8, Canada
| | - Christopher J Nelson
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Perry L Howard
- To whom correspondence should be addressed. Tel: +1 260 721 7068; Fax: +1 260 721 8855;
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26
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Oberlin S, Rajeswaran R, Trasser M, Barragán-Borrero V, Schon MA, Plotnikova A, Loncsek L, Nodine MD, Marí-Ordóñez A, Voinnet O. Innate, translation-dependent silencing of an invasive transposon in Arabidopsis. EMBO Rep 2021; 23:e53400. [PMID: 34931432 PMCID: PMC8892269 DOI: 10.15252/embr.202153400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 11/25/2022] Open
Abstract
Co‐evolution between hosts’ and parasites’ genomes shapes diverse pathways of acquired immunity based on silencing small (s)RNAs. In plants, sRNAs cause heterochromatinization, sequence degeneration, and, ultimately, loss of autonomy of most transposable elements (TEs). Recognition of newly invasive plant TEs, by contrast, involves an innate antiviral‐like silencing response. To investigate this response’s activation, we studied the single‐copy element EVADÉ (EVD), one of few representatives of the large Ty1/Copia family able to proliferate in Arabidopsis when epigenetically reactivated. In Ty1/Copia elements, a short subgenomic mRNA (shGAG) provides the necessary excess of structural GAG protein over the catalytic components encoded by the full‐length genomic flGAG‐POL. We show here that the predominant cytosolic distribution of shGAG strongly favors its translation over mostly nuclear flGAG‐POL. During this process, an unusually intense ribosomal stalling event coincides with mRNA breakage yielding unconventional 5’OH RNA fragments that evade RNA quality control. The starting point of sRNA production by RNA‐DEPENDENT‐RNA‐POLYMERASE‐6 (RDR6), exclusively on shGAG, occurs precisely at this breakage point. This hitherto‐unrecognized “translation‐dependent silencing” (TdS) is independent of codon usage or GC content and is not observed on TE remnants populating the Arabidopsis genome, consistent with their poor association, if any, with polysomes. We propose that TdS forms a primal defense against EVD de novo invasions that underlies its associated sRNA pattern.
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Affiliation(s)
- Stefan Oberlin
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Rajendran Rajeswaran
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Marieke Trasser
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Verónica Barragán-Borrero
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Michael A Schon
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Alexandra Plotnikova
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Lukas Loncsek
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Michael D Nodine
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria.,Laboratory of Molecular Biology, Wageningen University, Wageningen, The Netherlands
| | - Arturo Marí-Ordóñez
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Olivier Voinnet
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
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27
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Schneider-Lunitz V, Ruiz-Orera J, Hubner N, van Heesch S. Multifunctional RNA-binding proteins influence mRNA abundance and translational efficiency of distinct sets of target genes. PLoS Comput Biol 2021; 17:e1009658. [PMID: 34879078 PMCID: PMC8687540 DOI: 10.1371/journal.pcbi.1009658] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 12/20/2021] [Accepted: 11/18/2021] [Indexed: 12/12/2022] Open
Abstract
RNA-binding proteins (RBPs) can regulate more than a single aspect of RNA metabolism. We searched for such previously undiscovered multifunctionality within a set of 143 RBPs, by defining the predictive value of RBP abundance for the transcription and translation levels of known RBP target genes across 80 human hearts. This led us to newly associate 27 RBPs with cardiac translational regulation in vivo. Of these, 21 impacted both RNA expression and translation, albeit for virtually independent sets of target genes. We highlight a subset of these, including G3BP1, PUM1, UCHL5, and DDX3X, where dual regulation is achieved through differential affinity for target length, by which separate biological processes are controlled. Like the RNA helicase DDX3X, the known splicing factors EFTUD2 and PRPF8—all identified as multifunctional RBPs by our analysis—selectively influence target translation rates depending on 5’ UTR structure. Our analyses identify dozens of RBPs as being multifunctional and pinpoint potential novel regulators of translation, postulating unanticipated complexity of protein-RNA interactions at consecutive stages of gene expression. The lifecycle of an RNA molecule is controlled by hundreds of proteins that can bind RNA, also known as RNA-binding proteins (RBPs). These proteins recognize landing sites within the RNA and guide the RNA’s transcription from DNA, its processing into a mature messenger RNA, its translation into protein, or its degradation once the RNA is no longer needed. Although we now mechanistically understand how certain RBPs regulate these processes, for many RBP-target interactions the consequences imposed by RNA binding are not well understood. For 143 RBPs with known RNA binding positions, the authors of the current study investigated how RNA molecules responded to fluctuations in the expression levels of these RBPs, across each of 80 human hearts. Using statistical approaches, they could show that many RBPs influenced stages of the RNA lifecycle that they were not known to be involved in. Some RBPs turned out to be true "all-rounders" of RNA metabolism: they controlled the RNA transcript levels of some genes, whereas they influenced the translation rates of others. This unexpected multifunctionality unveiled previously hidden aspects of the everyday RNA-binding protein working life.
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Affiliation(s)
- Valentin Schneider-Lunitz
- Cardiovascular and Metabolic Sciences, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Jorge Ruiz-Orera
- Cardiovascular and Metabolic Sciences, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Norbert Hubner
- Cardiovascular and Metabolic Sciences, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Charité-Universitätsmedizin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- * E-mail: (NH); (SvH)
| | - Sebastiaan van Heesch
- Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
- * E-mail: (NH); (SvH)
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28
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eIF4A3 regulates the TFEB-mediated transcriptional response via GSK3B to control autophagy. Cell Death Differ 2021; 28:3344-3356. [PMID: 34158631 PMCID: PMC8630043 DOI: 10.1038/s41418-021-00822-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 02/06/2023] Open
Abstract
During autophagy, the coordinated actions of autophagosomes and lysosomes result in the controlled removal of damaged intracellular organelles and superfluous substrates. The evolutionary conservation of this process and its requirement for maintaining cellular homeostasis emphasizes the need to better dissect the pathways governing its molecular regulation. In our previously performed high-content screen, we assessed the effect of 1530 RNA-binding proteins on autophagy. Among the top regulators, we identified the eukaryotic translation initiation factor 4A-3 (eIF4A3). Here we show that depletion of eIF4A3 leads to a potent increase in autophagosome and lysosome biogenesis and an enhanced autophagic flux. This is mediated by the key autophagy transcription factor, TFEB, which becomes dephosphorylated and translocates from the cytoplasm to the nucleus where it elicits an integrated transcriptional response. We further identified an exon-skipping event in the transcript encoding for the direct TFEB kinase, GSK3B, which leads to a reduction in GSK3B expression and activity. Through analysis of TCGA data, we found a significant upregulation of eIF4A3 expression across several cancer types and confirmed the potential relevance of this newly identified signaling axis in human tumors. Hence, our data suggest a previously unrecognized role for eIF4A3 as a gatekeeper of autophagy through the control of TFEB activation, revealing a new mechanism for autophagy regulation.
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29
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Zinshteyn B, Sinha NK, Enam SU, Koleske B, Green R. Translational repression of NMD targets by GIGYF2 and EIF4E2. PLoS Genet 2021; 17:e1009813. [PMID: 34665823 PMCID: PMC8555832 DOI: 10.1371/journal.pgen.1009813] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/29/2021] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
Translation of messenger RNAs (mRNAs) with premature termination codons produces truncated proteins with potentially deleterious effects. This is prevented by nonsense-mediated mRNA decay (NMD) of these mRNAs. NMD is triggered by ribosomes terminating upstream of a splice site marked by an exon-junction complex (EJC), but also acts on many mRNAs lacking a splice junction after their termination codon. We developed a genome-wide CRISPR flow cytometry screen to identify regulators of mRNAs with premature termination codons in K562 cells. This screen recovered essentially all core NMD factors and suggested a role for EJC factors in degradation of PTCs without downstream splicing. Among the strongest hits were the translational repressors GIGYF2 and EIF4E2. GIGYF2 and EIF4E2 mediate translational repression but not mRNA decay of a subset of NMD targets and interact with NMD factors genetically and physically. Our results suggest a model wherein recognition of a stop codon as premature can lead to its translational repression through GIGYF2 and EIF4E2.
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Affiliation(s)
- Boris Zinshteyn
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Niladri K. Sinha
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Syed Usman Enam
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Benjamin Koleske
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Rachel Green
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
- * E-mail:
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30
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Diao P, Sun H, Bao Z, Li W, Niu N, Li W, Wuriyanghan H. Expression of an Antiviral Gene GmRUN1 from Soybean Is Regulated via Intron-Mediated Enhancement (IME). Viruses 2021; 13:2032. [PMID: 34696462 PMCID: PMC8539222 DOI: 10.3390/v13102032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 12/18/2022] Open
Abstract
Most of R (resistance) genes encode the protein containing NBS-LRR (nucleotide binding site and leucine-rich repeat) domains. Here, N. benthamiana plants were used for transient expression assays at 3-4 weeks of age. We identified a TNL (TIR-NBS-LRR) encoding gene GmRUN1 that was resistant to both soybean mosaic virus (SMV) and tobacco mosaic virus (TMV). Truncation analysis indicated the importance of all three canonical domains for GmRUN1-mediated antiviral activity. Promoter-GUS analysis showed that GmRUN1 expression is inducible by both salicylic acid (SA) and a transcription factor GmDREB3 via the cis-elements as-1 and ERE (ethylene response element), which are present in its promoter region. Interestingly, GmRUN1 gDNA (genomic DNA) shows higher viral resistance than its cDNA (complementary DNA), indicating the existence of intron-mediated enhancement (IME) for GmRUN1 regulation. We provided evidence that intron2 of GmRUN1 increased the mRNA level of native gene GmRUN1, a soybean antiviral gene SRC7 and also a reporter gene Luciferase, indicating the general transcriptional enhancement of intron2 in different genes. In summary, we identified an antiviral TNL type soybean gene GmRUN1, expression of which was regulated at different layers. The investigation of GmRUN1 gene regulatory network would help to explore the mechanism underlying soybean-SMV interactions.
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Affiliation(s)
- Pengfei Diao
- Key Laboratory of Forage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; (P.D.); (H.S.); (Z.B.); (W.L.); (N.N.)
| | - Hongyu Sun
- Key Laboratory of Forage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; (P.D.); (H.S.); (Z.B.); (W.L.); (N.N.)
| | - Zhuo Bao
- Key Laboratory of Forage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; (P.D.); (H.S.); (Z.B.); (W.L.); (N.N.)
| | - Wenxia Li
- Key Laboratory of Forage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; (P.D.); (H.S.); (Z.B.); (W.L.); (N.N.)
| | - Niu Niu
- Key Laboratory of Forage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; (P.D.); (H.S.); (Z.B.); (W.L.); (N.N.)
| | - Weimin Li
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China;
| | - Hada Wuriyanghan
- Key Laboratory of Forage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; (P.D.); (H.S.); (Z.B.); (W.L.); (N.N.)
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31
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Makeyeva YV, Shirayama M, Mello CC. Cues from mRNA splicing prevent default Argonaute silencing in C. elegans. Dev Cell 2021; 56:2636-2648.e4. [PMID: 34547227 DOI: 10.1016/j.devcel.2021.08.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/28/2021] [Accepted: 08/27/2021] [Indexed: 12/12/2022]
Abstract
In animals, Argonaute small-RNA pathways scan germline transcripts to silence self-replicating genetic elements. However, little is known about how endogenous gene expression is recognized and licensed. Here, we show that the presence of introns and, by inference, the process of mRNA splicing prevents default Argonaute-mediated silencing in the C. elegans germline. The silencing of intronless genes is initiated independently of the piRNA pathway but nevertheless engages multiple components of the downstream amplification and maintenance mechanisms that mediate transgenerational silencing, including both nuclear and cytoplasmic members of the worm-specific Argonaute gene family (WAGOs). Small RNAs amplified from intronless mRNAs can trans-silence cognate intron-containing genes. Interestingly, a second, small RNA-independent cis-acting mode of silencing also acts on intronless mRNAs. Our findings suggest that cues put in place during mRNA splicing license germline gene expression and provide evidence for a splicing-dependent and dsRNA- and piRNA-independent mechanism that can program Argonaute silencing.
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Affiliation(s)
- Yekaterina V Makeyeva
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Masaki Shirayama
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, Worcester, MA 01605, USA
| | - Craig C Mello
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, Worcester, MA 01605, USA.
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32
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Wang B, Rong X, Zhou Y, Liu Y, Sun J, Zhao B, Deng B, Lu L, Lu L, Li Y, Zhou J. Eukaryotic initiation factor 4A3 inhibits Wnt/β-catenin signaling and regulates axis formation in zebrafish embryos. Development 2021; 148:261699. [PMID: 33914867 DOI: 10.1242/dev.198101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/25/2021] [Indexed: 12/31/2022]
Abstract
A key step in the activation of canonical Wnt signaling is the interaction between β-catenin and Tcf/Lefs that forms the transcription activation complex and facilitates the expression of target genes. Eukaryotic initiation factor 4A3 (EIF4A3) is an ATP-dependent DEAD box-family RNA helicase and acts as a core subunit of the exon junction complex (EJC) to control a series of RNA post-transcriptional processes. In this study, we uncover that EIF4A3 functions as a Wnt inhibitor by interfering with the formation of β-catenin/Tcf transcription activation complex. As Wnt stimulation increases, accumulated β-catenin displaces EIF4A3 from a transcriptional complex with Tcf/Lef, allowing the active complex to facilitate the expression of target genes. In zebrafish embryos, eif4a3 depletion inhibited the development of the dorsal organizer and pattern formation of the anterior neuroectoderm by increasing Wnt/β-catenin signaling. Conversely, overexpression of eif4a3 decreased Wnt/β-catenin signaling and inhibited the formation of the dorsal organizer before gastrulation. Our results reveal previously unreported roles of EIF4A3 in the inhibition of Wnt signaling and the regulation of embryonic development in zebrafish.
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Affiliation(s)
- Bo Wang
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Xiaozhi Rong
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| | - Yumei Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Yunzhang Liu
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Jiqin Sun
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Beibei Zhao
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Bei Deng
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Lei Lu
- Model Animal Research Center of Nanjing University and MOE Key Laboratory of Model Animals for Disease Study, 12 Xuefu Road, Pukou High-Tech Zone, Nanjing 210061, China
| | - Ling Lu
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Yun Li
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| | - Jianfeng Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
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33
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The exon junction complex core factor eIF4A3 is a key regulator of HPV16 gene expression. Biosci Rep 2021; 41:228142. [PMID: 33760064 PMCID: PMC8026852 DOI: 10.1042/bsr20203488] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 03/04/2021] [Accepted: 03/24/2021] [Indexed: 01/06/2023] Open
Abstract
High-risk human papillomavirus (hrHPVs), particularly HPV16 and HPV18, are the etiologic factors of ano-genital cancers and some head and neck squamous cell carcinomas (HNSCCs). Viral E6 and E7 oncoproteins, controlled at both transcriptional and post-transcriptional levels, drive hrHPVs-induced carcinogenesis. In the present study, we investigated the implication of the DEAD-box helicase eukaryotic translation initiation factor 4A3 (eIF4A3,) an Exon Junction Complex factor, in the regulation of HPV16 gene expression. Our data revealed that the depletion of the factor eIF4A3 up-regulated E7 oncoprotein levels. We also showed that the inhibition of the nonsense-mediated RNA decay (NMD) pathway, resulted in the up-regulation of E7 at both RNA and protein levels. We therefore proposed that HPV16 transcripts might present different susceptibilities to NMD and that this pathway could play a key role in the levels of expression of these viral oncoproteins during the development of HPV-related cancers.
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34
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Ghiasi SM, Rutter GA. Consequences for Pancreatic β-Cell Identity and Function of Unregulated Transcript Processing. Front Endocrinol (Lausanne) 2021; 12:625235. [PMID: 33763030 PMCID: PMC7984428 DOI: 10.3389/fendo.2021.625235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/26/2021] [Indexed: 12/25/2022] Open
Abstract
Mounting evidence suggests a role for alternative splicing (AS) of transcripts in the normal physiology and pathophysiology of the pancreatic β-cell. In the apparent absence of RNA repair systems, RNA decay pathways are likely to play an important role in controlling the stability, distribution and diversity of transcript isoforms in these cells. Around 35% of alternatively spliced transcripts in human cells contain premature termination codons (PTCs) and are targeted for degradation via nonsense-mediated decay (NMD), a vital quality control process. Inflammatory cytokines, whose levels are increased in both type 1 (T1D) and type 2 (T2D) diabetes, stimulate alternative splicing events and the expression of NMD components, and may or may not be associated with the activation of the NMD pathway. It is, however, now possible to infer that NMD plays a crucial role in regulating transcript processing in normal and stress conditions in pancreatic β-cells. In this review, we describe the possible role of Regulated Unproductive Splicing and Translation (RUST), a molecular mechanism embracing NMD activity in relationship to AS and translation of damaged transcript isoforms in these cells. This process substantially reduces the abundance of non-functional transcript isoforms, and its dysregulation may be involved in pancreatic β-cell failure in diabetes.
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Affiliation(s)
- Seyed M. Ghiasi
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Guy A. Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
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35
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Zhu Y, Ren C, Yang L. Effect of eukaryotic translation initiation factor 4A3 in malignant tumors. Oncol Lett 2021; 21:358. [PMID: 33747215 PMCID: PMC7967930 DOI: 10.3892/ol.2021.12619] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 02/19/2021] [Indexed: 01/03/2023] Open
Abstract
Eukaryotic translation initiation factor 4A3 (EIF4A3), a key component of the exon junction complex, is widely involved in RNA splicing and nonsense-mediated mRNA decay. EIF4A3 has also been reported to be involved in cell cycle regulation and apoptosis. Thus, EIF4A3 may serve as a pivotal regulatory factor involved in the occurrence and development of multiple diseases. Previous studies have demonstrated that EIF4A3 is mutated in neuromuscular degenerative lesions and is differentially expressed in several tumors, serving as a non-coding RNA binding protein to regulate its expression. In addition, studies have reported that inhibiting EIF4A3 can prevent tumor cell proliferation, thus, several researchers are trying to design and synthesize potent and selective EIF4A3 inhibitors. The present review summarizes the function of EIF4A3 in cell cycle and discusses it underlying molecular mechanisms that contribute to the occurrence of malignant diseases. In addition, EIF4A3 selective inhibitors, and bioinformatics analyses performed to analyze the expression and mutations of EIF4A3 in gynecological tumors and breast cancer, are also discussed.
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Affiliation(s)
- Yuanhang Zhu
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Chenchen Ren
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Li Yang
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
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36
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Kwon OS, Mishra R, Safieddine A, Coleno E, Alasseur Q, Faucourt M, Barbosa I, Bertrand E, Spassky N, Le Hir H. Exon junction complex dependent mRNA localization is linked to centrosome organization during ciliogenesis. Nat Commun 2021; 12:1351. [PMID: 33649372 PMCID: PMC7921557 DOI: 10.1038/s41467-021-21590-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 01/14/2021] [Indexed: 12/17/2022] Open
Abstract
Exon junction complexes (EJCs) mark untranslated spliced mRNAs and are crucial for the mRNA lifecycle. An imbalance in EJC dosage alters mouse neural stem cell (mNSC) division and is linked to human neurodevelopmental disorders. In quiescent mNSC and immortalized human retinal pigment epithelial (RPE1) cells, centrioles form a basal body for ciliogenesis. Here, we report that EJCs accumulate at basal bodies of mNSC or RPE1 cells and decline when these cells differentiate or resume growth. A high-throughput smFISH screen identifies two transcripts accumulating at centrosomes in quiescent cells, NIN and BICD2. In contrast to BICD2, the localization of NIN transcripts is EJC-dependent. NIN mRNA encodes a core component of centrosomes required for microtubule nucleation and anchoring. We find that EJC down-regulation impairs both pericentriolar material organization and ciliogenesis. An EJC-dependent mRNA trafficking towards centrosome and basal bodies might contribute to proper mNSC division and brain development. Exon junction complexes (EJCs) that mark untranslated mRNA are involved in transport, translation and nonsense-mediated mRNA decay. Here the authors show centrosomal localization of EJCs which appears to be required for both the localization of NIN mRNA around centrosomes and ciliogenesis.
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Affiliation(s)
- Oh Sung Kwon
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Rahul Mishra
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France.,Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - Adham Safieddine
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.,Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Emeline Coleno
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.,Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Quentin Alasseur
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Marion Faucourt
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Isabelle Barbosa
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.,Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Nathalie Spassky
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Hervé Le Hir
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France.
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37
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Shen Q, Wang YE, Truong M, Mahadevan K, Wu JJ, Zhang H, Li J, Smith HW, Smibert CA, Palazzo AF. RanBP2/Nup358 enhances miRNA activity by sumoylating Argonautes. PLoS Genet 2021; 17:e1009378. [PMID: 33600493 PMCID: PMC7924746 DOI: 10.1371/journal.pgen.1009378] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 03/02/2021] [Accepted: 01/25/2021] [Indexed: 02/07/2023] Open
Abstract
Mutations in RanBP2 (also known as Nup358), one of the main components of the cytoplasmic filaments of the nuclear pore complex, contribute to the overproduction of acute necrotizing encephalopathy (ANE1)-associated cytokines. Here we report that RanBP2 represses the translation of the interleukin 6 (IL6) mRNA, which encodes a cytokine that is aberrantly up-regulated in ANE1. Our data indicates that soon after its production, the IL6 messenger ribonucleoprotein (mRNP) recruits Argonautes bound to let-7 microRNA. After this mRNP is exported to the cytosol, RanBP2 sumoylates mRNP-associated Argonautes, thereby stabilizing them and enforcing mRNA silencing. Collectively, these results support a model whereby RanBP2 promotes an mRNP remodelling event that is critical for the miRNA-mediated suppression of clinically relevant mRNAs, such as IL6.
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Affiliation(s)
- Qingtang Shen
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, China
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yifan E. Wang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Mathew Truong
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Kohila Mahadevan
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jingze J. Wu
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Hui Zhang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jiawei Li
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, China
| | - Harrison W. Smith
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Craig A. Smibert
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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38
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Sun Y, Xie M, Xu Z, Chan KC, Zhong JY, Fan K, Wong-Bajracharya J, Lam HM, Lim BL. Differential RNA Editing and Intron Splicing in Soybean Mitochondria during Nodulation. Int J Mol Sci 2020; 21:E9378. [PMID: 33317061 PMCID: PMC7764374 DOI: 10.3390/ijms21249378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022] Open
Abstract
Nitrogen fixation in soybean consumes a tremendous amount of energy, leading to substantial differences in energy metabolism and mitochondrial activities between nodules and uninoculated roots. While C-to-U RNA editing and intron splicing of mitochondrial transcripts are common in plant species, their roles in relation to nodule functions are still elusive. In this study, we performed RNA-seq to compare transcript profiles and RNA editing of mitochondrial genes in soybean nodules and roots. A total of 631 RNA editing sites were identified on mitochondrial transcripts, with 12% or 74 sites differentially edited among the transcripts isolated from nodules, stripped roots, and uninoculated roots. Eight out of these 74 differentially edited sites are located on the matR transcript, of which the degrees of RNA editing were the highest in the nodule sample. The degree of mitochondrial intron splicing was also examined. The splicing efficiencies of several introns in nodules and stripped roots were higher than in uninoculated roots. These include nad1 introns 2/3/4, nad4 intron 3, nad5 introns 2/3, cox2 intron 1, and ccmFc intron 1. A greater splicing efficiency of nad4 intron 1, a higher NAD4 protein abundance, and a reduction in supercomplex I + III2 were also observed in nodules, although the causal relationship between these observations requires further investigation.
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Affiliation(s)
- Yuzhe Sun
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Min Xie
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Zhou Xu
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Koon Chuen Chan
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Jia Yi Zhong
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Kejing Fan
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Johanna Wong-Bajracharya
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Hon-Ming Lam
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Boon Leong Lim
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
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39
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Palazzo AF, Kang YM. GC-content biases in protein-coding genes act as an "mRNA identity" feature for nuclear export. Bioessays 2020; 43:e2000197. [PMID: 33165929 DOI: 10.1002/bies.202000197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 01/11/2023]
Abstract
It has long been observed that human protein-coding genes have a particular distribution of GC-content: the 5' end of these genes has high GC-content while the 3' end has low GC-content. In 2012, it was proposed that this pattern of GC-content could act as an mRNA identity feature that would lead to it being better recognized by the cellular machinery to promote its nuclear export. In contrast, junk RNA, which largely lacks this feature, would be retained in the nucleus and targeted for decay. Now two recent papers have provided evidence that GC-content does promote the nuclear export of many mRNAs in human cells.
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Affiliation(s)
- Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Yoon Mo Kang
- Department of Biochemistry, University of Toronto, Toronto, ON, M5G 1M1, Canada
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40
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The Branched Nature of the Nonsense-Mediated mRNA Decay Pathway. Trends Genet 2020; 37:143-159. [PMID: 33008628 DOI: 10.1016/j.tig.2020.08.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/11/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is a conserved translation-coupled quality control mechanism in all eukaryotes that regulates the expression of a significant fraction of both the aberrant and normal transcriptomes. In vertebrates, NMD has become an essential process owing to expansion of the diversity of NMD-regulated transcripts, particularly during various developmental processes. Surprisingly, however, some core NMD factors that are essential for NMD in simpler organisms appear to be dispensable for vertebrate NMD. At the same time, numerous NMD enhancers and suppressors have been identified in multicellular organisms including vertebrates. Collectively, the available data suggest that vertebrate NMD is a complex, branched pathway wherein individual branches regulate specific mRNA subsets to fulfill distinct physiological functions.
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41
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Echols J, Siddiqui A, Dai Y, Havasi V, Sun R, Kaczmarczyk A, Keeling KM. A regulated NMD mouse model supports NMD inhibition as a viable therapeutic option to treat genetic diseases. Dis Model Mech 2020; 13:dmm044891. [PMID: 32737261 PMCID: PMC7473645 DOI: 10.1242/dmm.044891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 07/17/2020] [Indexed: 12/22/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) targets mRNAs that contain a premature termination codon (PTC) for degradation, preventing their translation. By altering the expression of PTC-containing mRNAs, NMD modulates the inheritance pattern and severity of genetic diseases. NMD also limits the efficiency of suppressing translation termination at PTCs, an emerging therapeutic approach to treat genetic diseases caused by in-frame PTCs (nonsense mutations). Inhibiting NMD may help rescue partial levels of protein expression. However, it is unclear whether long-term, global NMD attenuation is safe. We hypothesize that a degree of NMD inhibition can be safely tolerated after completion of prenatal development. To test this hypothesis, we generated a novel transgenic mouse that expresses an inducible, dominant-negative form of human UPF1 (dnUPF1) to inhibit NMD in mouse tissues by different degrees, allowing us to examine the effects of global NMD inhibition in vivo A thorough characterization of these mice indicated that expressing dnUPF1 at levels that promote relatively moderate to strong NMD inhibition in most tissues for a 1-month period produced modest immunological and bone alterations. In contrast, 1 month of dnUPF1 expression to promote more modest NMD inhibition in most tissues did not produce any discernable defects, indicating that moderate global NMD attenuation is generally well tolerated in non-neurological somatic tissues. Importantly, a modest level of NMD inhibition that produced no overt abnormalities was able to significantly enhance in vivo PTC suppression. These results suggest that safe levels of NMD attenuation are likely achievable, and this can help rescue protein deficiencies resulting from PTCs.
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Affiliation(s)
- Josh Echols
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Amna Siddiqui
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Yanying Dai
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Viktoria Havasi
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Richard Sun
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Aneta Kaczmarczyk
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Kim M Keeling
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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42
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Obrdlik A, Lin G, Haberman N, Ule J, Ephrussi A. The Transcriptome-wide Landscape and Modalities of EJC Binding in Adult Drosophila. Cell Rep 2020; 28:1219-1236.e11. [PMID: 31365866 DOI: 10.1016/j.celrep.2019.06.088] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 04/30/2019] [Accepted: 06/24/2019] [Indexed: 12/27/2022] Open
Abstract
Exon junction complex (EJC) assembles after splicing at specific positions upstream of exon-exon junctions in mRNAs of all higher eukaryotes, affecting major regulatory events. In mammalian cell cytoplasm, EJC is essential for efficient RNA surveillance, while in Drosophila, EJC is essential for localization of oskar mRNA. Here we developed a method for isolation of protein complexes and associated RNA targets (ipaRt) to explore the EJC RNA-binding landscape in a transcriptome-wide manner in adult Drosophila. We find the EJC at canonical positions, preferably on mRNAs from genes comprising multiple splice sites and long introns. Moreover, EJC occupancy is highest at junctions adjacent to strong splice sites, CG-rich hexamers, and RNA structures. Highly occupied mRNAs tend to be maternally localized and derive from genes involved in differentiation or development. These modalities, which have not been reported in mammals, specify EJC assembly on a biologically coherent set of transcripts in Drosophila.
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Affiliation(s)
- Ales Obrdlik
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | - Gen Lin
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nejc Haberman
- Department for Neuromuscular Diseases, UCL Institute of Neurology, London WC1N 3BG, UK
| | - Jernej Ule
- Department for Neuromuscular Diseases, UCL Institute of Neurology, London WC1N 3BG, UK; The Francis Crick Institute, London NW1 1AT, UK
| | - Anne Ephrussi
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
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43
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Park HJ, You YN, Lee A, Jung H, Jo SH, Oh N, Kim HS, Lee HJ, Kim JK, Kim YS, Jung C, Cho HS. OsFKBP20-1b interacts with the splicing factor OsSR45 and participates in the environmental stress response at the post-transcriptional level in rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:992-1007. [PMID: 31925835 DOI: 10.1111/tpj.14682] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 11/28/2019] [Accepted: 12/20/2019] [Indexed: 06/10/2023]
Abstract
Sessile plants have evolved distinct mechanisms to respond and adapt to adverse environmental conditions through diverse mechanisms including RNA processing. While the role of RNA processing in the stress response is well understood for Arabidopsis thaliana, limited information is available for rice (Oryza sativa). Here, we show that OsFKBP20-1b, belonging to the immunophilin family, interacts with the splicing factor OsSR45 in both nuclear speckles and cytoplasmic foci, and plays an essential role in post-transcriptional regulation of abiotic stress response. The expression of OsFKBP20-1b was highly upregulated under various abiotic stresses. Moreover genetic analysis revealed that OsFKBP20-1b positively affected transcription and pre-mRNA splicing of stress-responsive genes under abiotic stress conditions. In osfkbp20-1b loss-of-function mutants, the expression of stress-responsive genes was downregulated, while that of their splicing variants was increased. Conversely, in plants overexpressing OsFKBP20-1b, the expression of the same stress-responsive genes was strikingly upregulated under abiotic stress. In vivo experiments demonstrated that OsFKBP20-1b directly maintains protein stability of OsSR45 splicing factor. Furthermore, we found that the plant-specific OsFKBP20-1b gene has uniquely evolved as a paralogue only in some Poaceae species. Together, our findings suggest that OsFKBP20-1b-mediated RNA processing contributes to stress adaptation in rice.
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Affiliation(s)
- Hyun J Park
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
| | - Young N You
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
| | - Areum Lee
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
- Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology, Daejeon, 34113, Korea
| | - Haemyeong Jung
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
- Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology, Daejeon, 34113, Korea
| | - Seung H Jo
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
- Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology, Daejeon, 34113, Korea
| | - Nuri Oh
- Crop Biotechnology Institute/GreenBio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Hyun-Soon Kim
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
| | - Hyo-Jun Lee
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
| | - Ju-Kon Kim
- Crop Biotechnology Institute/GreenBio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
- Graduate School of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Youn S Kim
- Crop Biotechnology Institute/GreenBio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Choonkyun Jung
- Crop Biotechnology Institute/GreenBio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
- Graduate School of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Hye S Cho
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Korea
- Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology, Daejeon, 34113, Korea
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44
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Mufarrege EF, Benizio EL, Prieto CC, Chiappini F, Rodriguez MC, Etcheverrigaray M, Kratje RB. Development of Magoh protein-overexpressing HEK cells for optimized therapeutic protein production. Biotechnol Appl Biochem 2020; 68:230-238. [PMID: 32249976 DOI: 10.1002/bab.1915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/25/2020] [Indexed: 11/07/2022]
Abstract
In the pharmaceutical industry, the need for high levels of protein expression in mammalian cells has prompted the search for new strategies, including technologies to obtain cells with improved mechanisms that enhance its transcriptional activity, folding, or protein secretion. Chinese Hamster Ovary (CHO) cells are by far the most used host cell for therapeutic protein expression. However, these cells produce specific glycans that are not present in human cells and therefore potentially immunogenic. As a result, there is an increased interest in the use of human-derived cells for therapeutic protein production. For many decades, human embryonic kidney (HEK) cells were exclusively used for research. However, two products for therapeutic indication were recently approved in the United States. It was previously shown that tethered Magoh, an Exon-junction complex core component, to specific mRNA sequences, have had significant positive effects on mRNA translational efficiency. In this study, a HEK Magoh-overexpressing cell line and clones, designated here as HEK-MAGO, were developed for the first time. These cells exhibited improved characteristics in protein expression, reaching -two- to threefold increases in rhEPO protein production in comparison with the wild-type cells. Moreover, this effect was promoter independent highlighting the versatility of this expression platform.
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Affiliation(s)
- Eduardo F Mufarrege
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Edificio FBCB - Ciudad Universitaria UNL, Santa Fe, Argentina.,Cell Culture Laboratory, Edificio FBCB, Ciudad Universitaria UNL, Santa Fe, Argentina
| | - Evangelina L Benizio
- Cell Culture Laboratory, Edificio FBCB, Ciudad Universitaria UNL, Santa Fe, Argentina
| | - Claudio C Prieto
- Cell Culture Laboratory, Edificio FBCB, Ciudad Universitaria UNL, Santa Fe, Argentina
| | - Fabricio Chiappini
- Cell Culture Laboratory, Edificio FBCB, Ciudad Universitaria UNL, Santa Fe, Argentina
| | | | - Marina Etcheverrigaray
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Edificio FBCB - Ciudad Universitaria UNL, Santa Fe, Argentina.,Cell Culture Laboratory, Edificio FBCB, Ciudad Universitaria UNL, Santa Fe, Argentina
| | - Ricardo B Kratje
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Edificio FBCB - Ciudad Universitaria UNL, Santa Fe, Argentina.,Cell Culture Laboratory, Edificio FBCB, Ciudad Universitaria UNL, Santa Fe, Argentina
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45
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Shi X, Wu J, Mensah RA, Tian N, Liu J, Liu F, Chen J, Che J, Guo Y, Wu B, Zhong G, Cheng C. Genome-Wide Identification and Characterization of UTR-Introns of Citrus sinensis. Int J Mol Sci 2020; 21:E3088. [PMID: 32349372 PMCID: PMC7247714 DOI: 10.3390/ijms21093088] [Citation(s) in RCA: 2] [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: 03/10/2020] [Revised: 04/18/2020] [Accepted: 04/23/2020] [Indexed: 11/15/2022] Open
Abstract
Introns exist not only in coding sequences (CDSs) but also in untranslated regions (UTRs) of a gene. Recent studies in animals and model plants such as Arabidopsis have revealed that the UTR-introns (UIs) are widely presented in most genomes and involved in regulation of gene expression or RNA stability. In the present study, we identified introns at both 5'UTRs (5UIs) and 3'UTRs (3UIs) of sweet orange genes, investigated their size and nucleotide distribution characteristics, and explored the distribution of cis-elements in the UI sequences. Functional category of genes with predicted UIs were further analyzed using GO, KEGG, and PageMan enrichment. In addition, the organ-dependent splicing and abundance of selected UI-containing genes in root, leaf, and stem were experimentally determined. Totally, we identified 825 UI- and 570 3UI-containing transcripts, corresponding to 617 and 469 genes, respectively. Among them, 74 genes contain both 5UI and 3UI. Nucleotide distribution analysis showed that 5UI distribution is biased at both ends of 5'UTR whiles 3UI distribution is biased close to the start site of 3'UTR. Cis- elements analysis revealed that 5UI and 3UI sequences were rich of promoter-enhancing related elements, indicating that they might function in regulating the expression through them. Function enrichment analysis revealed that genes containing 5UI are significantly enriched in the RNA transport pathway. While, genes containing 3UI are significantly enriched in splicesome. Notably, many pentatricopeptide repeat-containing protein genes and the disease resistance genes were identified to be 3UI-containing. RT-PCR result confirmed the existence of UIs in the eight selected gene transcripts whereas alternative splicing events were found in some of them. Meanwhile, qRT-PCR result showed that UIs were differentially expressed among organs, and significant correlation was found between some genes and their UIs, for example: The expression of VPS28 and its 3UI was significantly negative correlated. This is the first report about the UIs in sweet orange from genome-wide level, which could provide evidence for further understanding of the role of UIs in gene expression regulation.
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Affiliation(s)
- Xiaobao Shi
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Junwei Wu
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Raphael Anue Mensah
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Na Tian
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiapeng Liu
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Fan Liu
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jialan Chen
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jingru Che
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ye Guo
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Binghua Wu
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Guangyan Zhong
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Chunzhen Cheng
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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eIF4A3 Phosphorylation by CDKs Affects NMD during the Cell Cycle. Cell Rep 2020; 26:2126-2139.e9. [PMID: 30784594 DOI: 10.1016/j.celrep.2019.01.101] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/16/2018] [Accepted: 01/25/2019] [Indexed: 12/24/2022] Open
Abstract
Exon junction complexes (EJCs) loaded onto spliced mRNAs during splicing serve as molecular markers for various post-transcriptional gene-regulatory processes, including nonsense-mediated mRNA decay (NMD). Although the composition and structure of EJCs are well characterized, the mechanism regulating EJC deposition remains unknown. Here we find that threonine 163 (T163) within the RNA-binding motif of eIF4A3 (a core EJC component) is phosphorylated by cyclin-dependent protein kinases 1 and 2 in a cell cycle-dependent manner. T163 phosphorylation hinders binding of eIF4A3 to spliced mRNAs and other EJC components. Instead, it promotes association of eIF4A3 with CWC22, which guides eIF4A3 to an active spliceosome. These molecular events ensure the fidelity of specific deposition of the EJC ∼20-24 nt upstream of an exon-exon junction. Accordingly, NMD is affected by T163 phosphorylation. Collectively, our data provide evidence that T163 phosphorylation affects EJC formation and, consequently, NMD efficiency in a cell cycle-dependent manner.
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Mordstein C, Savisaar R, Young RS, Bazile J, Talmane L, Luft J, Liss M, Taylor MS, Hurst LD, Kudla G. Codon Usage and Splicing Jointly Influence mRNA Localization. Cell Syst 2020; 10:351-362.e8. [PMID: 32275854 PMCID: PMC7181179 DOI: 10.1016/j.cels.2020.03.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 12/19/2019] [Accepted: 03/05/2020] [Indexed: 12/11/2022]
Abstract
In the human genome, most genes undergo splicing, and patterns of codon usage are splicing dependent: guanine and cytosine (GC) content is the highest within single-exon genes and within first exons of multi-exon genes. However, the effects of codon usage on gene expression are typically characterized in unspliced model genes. Here, we measured the effects of splicing on expression in a panel of synonymous reporter genes that varied in nucleotide composition. We found that high GC content increased protein yield, mRNA yield, cytoplasmic mRNA localization, and translation of unspliced reporters. Splicing did not affect the expression of GC-rich variants. However, splicing promoted the expression of AT-rich variants by increasing their steady-state protein and mRNA levels, in part through promoting cytoplasmic localization of mRNA. We propose that splicing promotes the nuclear export of AU-rich mRNAs and that codon- and splicing-dependent effects on expression are under evolutionary pressure in the human genome.
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Affiliation(s)
- Christine Mordstein
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK; Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Rosina Savisaar
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK; Instituto de Medicina Molecular, João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Robert S Young
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK; Centre for Global Health Research, Usher Institute, The University of Edinburgh, Edinburgh, UK
| | - Jeanne Bazile
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Lana Talmane
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Juliet Luft
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Michael Liss
- Thermo Fisher Scientific, GENEART GmbH, Regensburg, Germany
| | - Martin S Taylor
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Laurence D Hurst
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Grzegorz Kudla
- MRC Human Genetics Unit, Institute for Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK.
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48
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Naddafi F, Davami F, Tabarzad M, Barkhordari F, Shirazi FH. Construction of a Mammalian IRES-based Expression Vector to Amplify a Bispecific Antibody; Blinatumomab. IRANIAN JOURNAL OF PHARMACEUTICAL RESEARCH : IJPR 2020; 18:2117-2123. [PMID: 32184875 PMCID: PMC7059065 DOI: 10.22037/ijpr.2019.14387.12351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Blinatumomab, the bispecific T cell engager antibody (BsAb), has been demonstrated as the most successful BsAb to date. Throughout the past decade, vector design has great importance for the expression of monoclonal antibody in Chinese hamster ovary (CHO) cells. It has been indicated that expression vectors based on the elongation factor-1 alpha (EF-1 alpha) gene and DHFR selection marker can be highly effective to produce populations of stably transfected cells in the selection medium. Moreover, the phiC31 integrase system is considered as an attractive and safe protein expression system in mammalian cells and it could integrate a donor plasmid of any size, as a single copy, in to the host genome with no cofactors. In this study, phiC31 integrase technology in combination with DHFR amplification system was used to have an expression vector for future expression of blinatumomab in CHO cells. The gene of interest (BsAb gene) could be joined to DHFR selection marker with the insertion of an internal ribosome entry site (IRES). By positioning the DHFR downstream of BsAb gene and IRES, the transcription of the selection marker can depend on the successful transcription of the BsAb gene, which was located upstream in the expression construct. In this study, FC550A-1 vector was used as the backbone and DHFR selection marker was successfully combined with phiC31 integrase technology to generate a high-expressing construct for BsAb expression in CHO-DG44 cells in future studies.
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Affiliation(s)
- Fatemeh Naddafi
- Pharmaceutical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Davami
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Maryam Tabarzad
- Protein Technology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Farshad H Shirazi
- Pharmaceutical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Toxicology, Shadid Beheshti University of Medical Sciences, Tehran, Iran
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49
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The Ebola Virus Nucleoprotein Recruits the Nuclear RNA Export Factor NXF1 into Inclusion Bodies to Facilitate Viral Protein Expression. Cells 2020; 9:cells9010187. [PMID: 31940815 PMCID: PMC7017048 DOI: 10.3390/cells9010187] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/07/2020] [Accepted: 01/09/2020] [Indexed: 01/12/2023] Open
Abstract
Ebola virus (EBOV) causes severe outbreaks of viral hemorrhagic fever in humans. While virus-host interactions are promising targets for antivirals, there is only limited knowledge regarding the interactions of EBOV with cellular host factors. Recently, we performed a genome-wide siRNA screen that identified the nuclear RNA export factor 1 (NXF1) as an important host factor for the EBOV life cycle. NXF1 is a major component of the nuclear mRNA export pathway that is usurped by many viruses whose life cycles include nuclear stages. However, the role of NXF1 in the life cycle of EBOV, a virus replicating in cytoplasmic inclusion bodies, remains unknown. In order to better understand the role of NXF1 in the EBOV life cycle, we performed a combination of co-immunoprecipitation and double immunofluorescence assays to characterize the interactions of NXF1 with viral proteins and RNAs. Additionally, using siRNA-mediated knockdown of NXF1 together with functional assays, we analyzed the role of NXF1 in individual aspects of the virus life cycle. With this approach we identified the EBOV nucleoprotein (NP) as a viral interaction partner of NXF1. Further studies revealed that NP interacts with the RNA-binding domain of NXF1 and competes with RNA for this interaction. Co-localization studies showed that RNA binding-deficient, but not wildtype NXF1, accumulates in NP-derived inclusion bodies, and knockdown experiments demonstrated that NXF1 is necessary for viral protein expression, but not for viral RNA synthesis. Finally, our results showed that NXF1 interacts with viral mRNAs, but not with viral genomic RNAs. Based on these results we suggest a model whereby NXF1 is recruited into inclusion bodies to promote the export of viral mRNA:NXF1 complexes from these sites. This would represent a novel function for NXF1 in the life cycle of cytoplasmically replicating viruses, and may provide a basis for new therapeutic approaches against EBOV, and possibly other emerging viruses.
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50
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Zhang Z, Guo M, Liu Y, Liu P, Cao X, Xu Y, Zhu X. RNPS1 inhibition aggravates ischemic brain injury and promotes neuronal death. Biochem Biophys Res Commun 2019; 523:39-45. [PMID: 31831174 DOI: 10.1016/j.bbrc.2019.11.185] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 11/28/2019] [Indexed: 12/13/2022]
Abstract
RNA-binding protein with serine-rich domain 1 (RNPS1) is essential for modulating mRNA metabolism, but its role in ischemic stroke is unknown. In this study, we found that RNPS1 expression was significantly up-regulated in the brains of ischemic stroke mice and primary cortical neurons after oxygen-glucose deprivation (OGD) treatment. Knockdown of RNPS1 significantly aggravated ischemic brain injury after middle cerebral artery occlusion (MCAO) and promoted neuronal death. In addition, knockdown of RNPS1 exacerbated ischemia induced neuronal apoptosis, and downregulated the expression of anti-apoptotic proteins Bcl-xL and Mcl-1. Our study suggested that RNPS1 might be a potential therapeutic target for alleviating neuronal death in ischemic stroke.
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Affiliation(s)
- Zhi Zhang
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Department of Neurology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Mengdi Guo
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Ying Liu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Pinyi Liu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Department of Neurology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Xiang Cao
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Yun Xu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Department of Neurology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Xiaolei Zhu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China.
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