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Fernández-Alvarez AJ, Thomas MG, Pascual ML, Habif M, Pimentel J, Corbat AA, Pessoa JP, La Spina PE, Boscaglia L, Plessis A, Carmo-Fonseca M, Grecco HE, Casado M, Boccaccio GL. Smaug1 membrane-less organelles respond to AMPK/mTOR and affect mitochondrial function‡. J Cell Sci 2021; 135:273619. [PMID: 34859817 DOI: 10.1242/jcs.253591] [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: 09/09/2020] [Accepted: 11/15/2021] [Indexed: 11/20/2022] Open
Abstract
Smaug is a conserved translational regulator that binds numerous mRNAs, including nuclear transcripts that encode mitochondrial enzymes. Smaug orthologs form cytosolic membrane-less organelles (MLOs) in several organisms and cell types. We have performed single-molecule FISH assays that revealed that SDHB and UQCRC1 mRNAs associate with Smaug1 bodies in U2OS cells. Loss of function of Smaug1 and Smaug2 affected both mitochondrial respiration and morphology of the mitochondrial network. Phenotype rescue by Smaug1 transfection depends on the presence of its RNA binding domain. Moreover, we identified specific Smaug1 domains involved in MLO formation, and found that impaired Smaug1 MLO condensation correlates with mitochondrial defects. Mitochondrial Complex I inhibition by rotenone -but not strong mitochondrial uncoupling by CCCP- rapidly induced Smaug1 MLOs dissolution. Metformin and rapamycin elicited similar effects, which were blocked by pharmacological inhibition of AMPK. Finally, we found that Smaug1 MLO dissolution weakens the interaction with target mRNAs, thus enabling their release. We propose that mitochondrial respiration and the AMPK/mTOR balance controls the condensation and dissolution of Smaug1 MLOs, thus regulating nuclear mRNAs that encode key mitochondrial proteins.
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Affiliation(s)
- Ana J Fernández-Alvarez
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - María Gabriela Thomas
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - Malena L Pascual
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - Martín Habif
- Department of Physics, Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, and IFIBA, CONICET, C1428EHA Buenos Aires, Argentina
| | - Jerónimo Pimentel
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - Agustín A Corbat
- Department of Physics, Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, and IFIBA, CONICET, C1428EHA Buenos Aires, Argentina
| | - João P Pessoa
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Pablo E La Spina
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | | | - Anne Plessis
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Hernán E Grecco
- Department of Physics, Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, and IFIBA, CONICET, C1428EHA Buenos Aires, Argentina
| | - Marta Casado
- Instituto de Biomedicina de Valencia, IBV-CSIC, Valencia 46010, Spain, and Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid 28029, Spain
| | - Graciela L Boccaccio
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina.,Department of Molecular and Cellular Biology and Physiology (FBMyC), Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, C1428EHA Buenos Aires, Argentina
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2
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Abstract
Protein-RNA interactions have crucial roles in various cellular activities, which, when dysregulated, can lead to a range of human diseases. The identification of small molecules that target the interaction between RNA-binding proteins (RBPs) and RNA is progressing rapidly and represents a novel strategy for the discovery of chemical probes that facilitate understanding of the cellular functions of RBPs and of therapeutic agents with new mechanisms of action. In this Review, I present a current overview of targeting emerging RBPs using small-molecule inhibitors and recent progress in this burgeoning field. Small-molecule inhibitors that were reported for three representative emerging classes of RBPs, the microRNA-binding protein LIN28, the single-stranded or double-stranded RNA-binding Toll-like receptors and the CRISPR-associated (Cas) proteins, are highlighted from a medicinal-chemistry and chemical-biology perspective. However, although this field is burgeoning, challenges remain in the discovery and characterization of small-molecule inhibitors of RBPs.
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3
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Bruzzone L, Argüelles C, Sanial M, Miled S, Alvisi G, Gonçalves-Antunes M, Qasrawi F, Holmgren RA, Smibert CA, Lipshitz HD, Boccaccio GL, Plessis A, Bécam I. Regulation of the RNA-binding protein Smaug by the GPCR Smoothened via the kinase Fused. EMBO Rep 2020; 21:e48425. [PMID: 32383557 DOI: 10.15252/embr.201948425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 03/17/2020] [Accepted: 04/14/2020] [Indexed: 12/13/2022] Open
Abstract
From fly to mammals, the Smaug/Samd4 family of prion-like RNA-binding proteins control gene expression by destabilizing and/or repressing the translation of numerous target transcripts. However, the regulation of its activity remains poorly understood. We show that Smaug's protein levels and mRNA repressive activity are downregulated by Hedgehog signaling in tissue culture cells. These effects rely on the interaction of Smaug with the G-protein coupled receptor Smoothened, which promotes the phosphorylation of Smaug by recruiting the kinase Fused. The activation of Fused and its binding to Smaug are sufficient to suppress its ability to form cytosolic bodies and to antagonize its negative effects on endogenous targets. Importantly, we demonstrate in vivo that HH reduces the levels of smaug mRNA and increases the level of several mRNAs downregulated by Smaug. Finally, we show that Smaug acts as a positive regulator of Hedgehog signaling during wing morphogenesis. These data constitute the first evidence for a post-translational regulation of Smaug and reveal that the fate of several mRNAs bound to Smaug is modulated by a major signaling pathway.
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Affiliation(s)
- Lucia Bruzzone
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | | | - Matthieu Sanial
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Samia Miled
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Giorgia Alvisi
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | | | - Fairouz Qasrawi
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Robert A Holmgren
- Department of Mol. Biosci., Northwestern University, Evanston, IL, USA
| | - Craig A Smibert
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Graciela L Boccaccio
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas, Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Buenos Aires, Argentina
| | - Anne Plessis
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Isabelle Bécam
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
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4
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Laver JD, Ly J, Winn JK, Karaiskakis A, Lin S, Nie K, Benic G, Jaberi-Lashkari N, Cao WX, Khademi A, Westwood JT, Sidhu SS, Morris Q, Angers S, Smibert CA, Lipshitz HD. The RNA-Binding Protein Rasputin/G3BP Enhances the Stability and Translation of Its Target mRNAs. Cell Rep 2020; 30:3353-3367.e7. [PMID: 32160542 DOI: 10.1016/j.celrep.2020.02.066] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 01/13/2020] [Accepted: 02/14/2020] [Indexed: 12/14/2022] Open
Abstract
G3BP RNA-binding proteins are important components of stress granules (SGs). Here, we analyze the role of the Drosophila G3BP Rasputin (RIN) in unstressed cells, where RIN is not SG associated. Immunoprecipitation followed by microarray analysis identifies over 550 mRNAs that copurify with RIN. The mRNAs found in SGs are long and translationally silent. In contrast, we find that RIN-bound mRNAs, which encode core components of the transcription, splicing, and translation machinery, are short, stable, and highly translated. We show that RIN is associated with polysomes and provide evidence for a direct role for RIN and its human homologs in stabilizing and upregulating the translation of their target mRNAs. We propose that when cells are stressed, the resulting incorporation of RIN/G3BPs into SGs sequesters them away from their short target mRNAs. This would downregulate the expression of these transcripts, even though they are not incorporated into stress granules.
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Affiliation(s)
- John D Laver
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Jimmy Ly
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada; Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Jamie K Winn
- Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Angelo Karaiskakis
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Sichun Lin
- Department of Pharmaceutical Sciences, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada
| | - Kun Nie
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Giulia Benic
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Nima Jaberi-Lashkari
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada; Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Wen Xi Cao
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Alireza Khademi
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - J Timothy Westwood
- Department of Biology, University of Toronto, 3359 Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Sachdev S Sidhu
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada; Donnelly Centre, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Quaid Morris
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada; Donnelly Centre, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada; Vector Institute, 661 University Ave, Toronto, Ontario, Canada, M160 College Street, Toronto, ON M5G 1M1, Canada
| | - Stephane Angers
- Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada; Department of Pharmaceutical Sciences, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada
| | - Craig A Smibert
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada; Department of Biochemistry, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada.
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada.
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5
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Na H, Laver JD, Jeon J, Singh F, Ancevicius K, Fan Y, Cao WX, Nie K, Yang Z, Luo H, Wang M, Rissland O, Westwood JT, Kim PM, Smibert CA, Lipshitz HD, Sidhu SS. A high-throughput pipeline for the production of synthetic antibodies for analysis of ribonucleoprotein complexes. RNA (NEW YORK, N.Y.) 2016; 22:636-655. [PMID: 26847261 PMCID: PMC4793217 DOI: 10.1261/rna.055186.115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 12/12/2015] [Indexed: 06/05/2023]
Abstract
Post-transcriptional regulation of mRNAs plays an essential role in the control of gene expression. mRNAs are regulated in ribonucleoprotein (RNP) complexes by RNA-binding proteins (RBPs) along with associated protein and noncoding RNA (ncRNA) cofactors. A global understanding of post-transcriptional control in any cell type requires identification of the components of all of its RNP complexes. We have previously shown that these complexes can be purified by immunoprecipitation using anti-RBP synthetic antibodies produced by phage display. To develop the large number of synthetic antibodies required for a global analysis of RNP complex composition, we have established a pipeline that combines (i) a computationally aided strategy for design of antigens located outside of annotated domains, (ii) high-throughput antigen expression and purification in Escherichia coli, and (iii) high-throughput antibody selection and screening. Using this pipeline, we have produced 279 antibodies against 61 different protein components of Drosophila melanogaster RNPs. Together with those produced in our low-throughput efforts, we have a panel of 311 antibodies for 67 RNP complex proteins. Tests of a subset of our antibodies demonstrated that 89% immunoprecipitate their endogenous target from embryo lysate. This panel of antibodies will serve as a resource for global studies of RNP complexes in Drosophila. Furthermore, our high-throughput pipeline permits efficient production of synthetic antibodies against any large set of proteins.
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Affiliation(s)
- Hong Na
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E1
| | - John D Laver
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Jouhyun Jeon
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E1
| | - Fateh Singh
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E1
| | - Kristin Ancevicius
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6 Department of Cell and Systems Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6
| | - Yujie Fan
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Wen Xi Cao
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Kun Nie
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E1 Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Zhenglin Yang
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Hua Luo
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Miranda Wang
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8 Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - Olivia Rissland
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8 Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 0A4
| | - J Timothy Westwood
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6 Department of Cell and Systems Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6
| | - Philip M Kim
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E1 Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8 Department of Computer Science, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Craig A Smibert
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8 Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Sachdev S Sidhu
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E1 Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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6
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Laver JD, Li X, Ray D, Cook KB, Hahn NA, Nabeel-Shah S, Kekis M, Luo H, Marsolais AJ, Fung KY, Hughes TR, Westwood JT, Sidhu SS, Morris Q, Lipshitz HD, Smibert CA. Brain tumor is a sequence-specific RNA-binding protein that directs maternal mRNA clearance during the Drosophila maternal-to-zygotic transition. Genome Biol 2015; 16:94. [PMID: 25962635 PMCID: PMC4460960 DOI: 10.1186/s13059-015-0659-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 04/22/2015] [Indexed: 11/30/2022] Open
Abstract
Background Brain tumor (BRAT) is a Drosophila member of the TRIM-NHL protein family. This family is conserved among metazoans and its members function as post-transcriptional regulators. BRAT was thought to be recruited to mRNAs indirectly through interaction with the RNA-binding protein Pumilio (PUM). However, it has recently been demonstrated that BRAT directly binds to RNA. The precise sequence recognized by BRAT, the extent of BRAT-mediated regulation, and the exact roles of PUM and BRAT in post-transcriptional regulation are unknown. Results Genome-wide identification of transcripts associated with BRAT or with PUM in Drosophila embryos shows that they bind largely non-overlapping sets of mRNAs. BRAT binds mRNAs that encode proteins associated with a variety of functions, many of which are distinct from those implemented by PUM-associated transcripts. Computational analysis of in vitro and in vivo data identified a novel RNA motif recognized by BRAT that confers BRAT-mediated regulation in tissue culture cells. The regulatory status of BRAT-associated mRNAs suggests a prominent role for BRAT in post-transcriptional regulation, including a previously unidentified role in transcript degradation. Transcriptomic analysis of embryos lacking functional BRAT reveals an important role in mediating the decay of hundreds of maternal mRNAs during the maternal-to-zygotic transition. Conclusions Our results represent the first genome-wide analysis of the mRNAs associated with a TRIM-NHL protein and the first identification of an RNA motif bound by this protein family. BRAT is a prominent post-transcriptional regulator in the early embryo through mechanisms that are largely independent of PUM. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0659-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- John D Laver
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Xiao Li
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada.
| | - Debashish Ray
- Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada.
| | - Kate B Cook
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada.
| | - Noah A Hahn
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Syed Nabeel-Shah
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Mariana Kekis
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada.
| | - Hua Luo
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Alexander J Marsolais
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Karen Yy Fung
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Timothy R Hughes
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada.
| | - J Timothy Westwood
- Department of Biology, University of Toronto, Mississauga, 3359 Mississauga Road, Mississauga, Ontario, L5L 1C6, Canada.
| | - Sachdev S Sidhu
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada.
| | - Quaid Morris
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada. .,Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada. .,Department of Computer Science, University of Toronto, 40 St. George Street, Toronto, Ontario, M5S 2E4, Canada.
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Craig A Smibert
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
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7
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Sutandy FXR, Hsiao FSH, Chen CS. High throughput platform to explore RNA-protein interactomes. Crit Rev Biotechnol 2014; 36:11-9. [PMID: 25025276 DOI: 10.3109/07388551.2014.922916] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
RNA binding proteins (RBPs) and RNA interaction is an emerging topic in molecular biology. Many reports showed that such interactions contribute to many cellular processes as well as disease development. Several standard in vitro and in vivo methods were developed to fulfill the needs of this RBP-RNA interaction study to explore their biological functions. However, these methods have their limitations in terms of throughput. In this review, we emphasize two important high throughput methods to studying RBP-RNA interactions, affinity purification and protein microarray. These methods have recently become robust techniques regarding their efficiency in systematically analyzing RBP-RNA interactions. Here, we provide technique overviews, strategies and applications of these methods during biological research. Although these technologies are just beginning to be explored, they will be most important methods in this study.
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Affiliation(s)
- F X Reymond Sutandy
- a Graduate Institute of Systems Biology and Bioinformatics, National Central University , Jhongli , Taiwan
| | - Felix Shih-Hsiang Hsiao
- a Graduate Institute of Systems Biology and Bioinformatics, National Central University , Jhongli , Taiwan
| | - Chien-Sheng Chen
- a Graduate Institute of Systems Biology and Bioinformatics, National Central University , Jhongli , Taiwan
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8
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Abstract
Highly functional synthetic antibody libraries can be used to generate antibodies against a multitude of antigens with affinities and specificities that rival or exceed those of natural antibodies. Current design and generation of synthetic antibody libraries are dependent on our insights from previous studies of simplified synthetic antibody libraries, in addition to our knowledge of antibody structure and function and sequence diversity of natural antibody repertoires. We describe a detailed protocol for the design and generation of phage-displayed synthetic antibody libraries built on a single framework with diversity restricted to four complementarity-determining regions by using precisely designed degenerate oligonucleotides. This general methodology could be applied to generation of large, functional synthetic antibody libraries using standard supplies, equipment, and molecular biology techniques.
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Affiliation(s)
- Gang Chen
- University of Toronto, Toronto, ON, Canada
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9
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Laver JD, Li X, Ancevicius K, Westwood JT, Smibert CA, Morris QD, Lipshitz HD. Genome-wide analysis of Staufen-associated mRNAs identifies secondary structures that confer target specificity. Nucleic Acids Res 2013; 41:9438-60. [PMID: 23945942 PMCID: PMC3814352 DOI: 10.1093/nar/gkt702] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Despite studies that have investigated the interactions of double-stranded RNA-binding proteins like Staufen with RNA in vitro, how they achieve target specificity in vivo remains uncertain. We performed RNA co-immunoprecipitations followed by microarray analysis to identify Staufen-associated mRNAs in early Drosophila embryos. Analysis of the localization and functions of these transcripts revealed a number of potentially novel roles for Staufen. Using computational methods, we identified two sequence features that distinguish Staufen’s target transcripts from non-targets. First, these Drosophila transcripts, as well as those human transcripts bound by human Staufen1 and 2, have 3′ untranslated regions (UTRs) that are 3–4-fold longer than unbound transcripts. Second, the 3′UTRs of Staufen-bound transcripts are highly enriched for three types of secondary structures. These structures map with high precision to previously identified Staufen-binding regions in Drosophila bicoid and human ARF1 3′UTRs. Our results provide the first systematic genome-wide analysis showing how a double-stranded RNA-binding protein achieves target specificity.
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Affiliation(s)
- John D Laver
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8, Department of Cell & Systems Biology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6, Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6, Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 and Banting and Best Department of Medical Research, Terrence Donnelly Centre for Cellular and Biomolecular Research, 160 College Street, Toronto, Ontario, Canada M5S 3E1
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10
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Akef A, Zhang H, Masuda S, Palazzo AF. Trafficking of mRNAs containing ALREX-promoting elements through nuclear speckles. Nucleus 2013; 4:326-40. [PMID: 23934081 PMCID: PMC3810340 DOI: 10.4161/nucl.26052] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
In vertebrates, the majority of mRNAs that encode secreted, membrane-bound or mitochondrial proteins contain RNA elements that activate an alternative mRNA nuclear export (ALREX) pathway. Here we demonstrate that mRNAs containing ALREX-promoting elements are trafficked through nuclear speckles. Although ALREX-promoting elements enhance nuclear speckle localization, additional features within the mRNA largely drive this process. Depletion of two TREX-associated RNA helicases, UAP56 and its paralog URH49, or inhibition of the TREX-associated nuclear transport factor, TAP, not only inhibits ALREX, but also appears to trap these mRNAs in nuclear speckles. mRNAs that contain ALREX-promoting elements associate with UAP56 in vivo. Finally, we demonstrate that mRNAs lacking a poly(A)-tail are not efficiently exported by the ALREX pathway and show enhanced association with nuclear speckles. Our data suggest that within the speckle, ALREX-promoting elements, in conjunction with the poly(A)-tail, likely stimulate UAP56/URH49 and TAP dependent steps that lead to the eventual egress of the export-competent mRNP from these structures.
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Affiliation(s)
- Abdalla Akef
- Department of Biochemistry; University of Toronto; Toronto, ON Canada; Division of Integrated Life Science; Graduate School of Biostudies; Kyoto University; Kyoto, Japan
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Koellhoffer JF, Chen G, Sandesara RG, Bale S, Saphire EO, Chandran K, Sidhu SS, Lai JR. Two synthetic antibodies that recognize and neutralize distinct proteolytic forms of the ebola virus envelope glycoprotein. Chembiochem 2012; 13:2549-57. [PMID: 23111988 DOI: 10.1002/cbic.201200493] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Indexed: 11/06/2022]
Abstract
Ebola virus (EBOV) is a highly pathogenic member of the Filoviridae family of viruses that causes severe hemorrhagic fever. Infection proceeds through fusion of the host cell and viral membranes, a process that is mediated by the viral envelope glycoprotein (GP). Following endosomal uptake, a key step in viral entry is the proteolytic cleavage of GP by host endosomal cysteine proteases. Cleavage exposes a binding site for the host cell receptor Niemann-Pick C1 (NPC1) and may induce conformational changes in GP leading to membrane fusion. However, the precise details of the structural changes in GP associated with proteolysis and the role of these changes in viral entry have not been established. Here, we have employed synthetic antibody technology to identify antibodies targeting EBOV GP prior to and following proteolysis (i.e. in the "uncleaved" [GP(UNCL)] and "cleaved" [GP(CL)] forms). We identified antibodies with distinct recognition profiles: Fab(CL) bound preferentially to GP(CL) (EC(50)=1.7 nM), whereas Fab(UNCL) bound specifically to GP(UNCL) (EC(50)=75 nM). Neutralization assays with GP-containing pseudotyped viruses indicated that these antibodies inhibited GP(CL)- or GP(UNCL)-mediated viral entry with specificity matching their recognition profiles (IC(50): 87 nM for IgG(CL); 1 μM for Fab(UNCL)). Competition ELISAs indicate that Fab(CL) binds an epitope distinct from that of KZ52, a well-characterized EBOV GP antibody, and from that of the luminal domain of NPC1. The binding epitope of Fab(UNCL) was also distinct from that of KZ52, suggesting that Fab(UNCL) binds a novel neutralization epitope on GP(UNCL). Furthermore, the neutralizing ability of Fab(CL) suggests that there are targets on GP(CL) available for neutralization. This work showcases the applicability of synthetic antibody technology to the study of viral membrane fusion, and provides new tools for dissecting intermediates of EBOV entry.
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Affiliation(s)
- Jayne F Koellhoffer
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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