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Balakrishnan K, Munusami P, Mohareer K, Priyakumar UD, Banerjee A, Luedde T, Mande SC, Münk C, Banerjee S. Staufen‐2 functions as a cofactor for enhanced Rev‐mediated nucleocytoplasmic trafficking of
HIV
‐1 genomic
RNA
via the
CRM1
pathway. FEBS J 2022; 289:6731-6751. [DOI: 10.1111/febs.16546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 04/21/2022] [Accepted: 06/01/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Kannan Balakrishnan
- Department of Biochemistry, School of Life Sciences University of Hyderabad India
- Clinic for Gastroenterology, Hepatology, and Infectiology Medical Faculty, Heinrich Heine University Düsseldorf Germany
| | - Punnagai Munusami
- Center for Computational Natural Sciences and Bioinformatics International Institute of Information Technology Hyderabad India
- Department of Chemistry Arignar Anna Government Arts & Science College Karaikal Puducherry India
| | - Krishnaveni Mohareer
- Department of Biochemistry, School of Life Sciences University of Hyderabad India
| | - U. Deva Priyakumar
- Center for Computational Natural Sciences and Bioinformatics International Institute of Information Technology Hyderabad India
| | - Atoshi Banerjee
- Nevada Institute of Personalized Medicine University of Nevada Las Vegas NV USA
| | - Tom Luedde
- Clinic for Gastroenterology, Hepatology, and Infectiology Medical Faculty, Heinrich Heine University Düsseldorf Germany
| | - Shekhar C. Mande
- National Centre for Cell Science Pune India
- Council of Scientific and Industrial Research New Delhi India
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology, and Infectiology Medical Faculty, Heinrich Heine University Düsseldorf Germany
| | - Sharmistha Banerjee
- Department of Biochemistry, School of Life Sciences University of Hyderabad India
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Bonnet-Magnaval F, Diallo LH, Brunchault V, Laugero N, Morfoisse F, David F, Roussel E, Nougue M, Zamora A, Marchaud E, Tatin F, Prats AC, Garmy-Susini B, DesGroseillers L, Lacazette E. High Level of Staufen1 Expression Confers Longer Recurrence Free Survival to Non-Small Cell Lung Cancer Patients by Promoting THBS1 mRNA Degradation. Int J Mol Sci 2021; 23:215. [PMID: 35008641 PMCID: PMC8745428 DOI: 10.3390/ijms23010215] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 12/12/2022] Open
Abstract
Stau1 is a pluripotent RNA-binding protein that is responsible for the post-transcriptional regulation of a multitude of transcripts. Here, we observed that lung cancer patients with a high Stau1 expression have a longer recurrence free survival. Strikingly, Stau1 did not impair cell proliferation in vitro, but rather cell migration and cell adhesion. In vivo, Stau1 depletion favored tumor progression and metastases development. In addition, Stau1 depletion strongly impaired vessel maturation. Among a panel of candidate genes, we specifically identified the mRNA encoding the cell adhesion molecule Thrombospondin 1 (THBS1) as a new target for Staufen-mediated mRNA decay. Altogether, our results suggest that regulation of THBS1 expression by Stau1 may be a key process involved in lung cancer progression.
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Affiliation(s)
- Florence Bonnet-Magnaval
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
- Département de Biochimie Et Médecine Moléculaire, Faculté de Médecine, Université de Montréal, 2900 Édouard Montpetit Montréal, Montreal, QC H3T 1J4, Canada;
| | - Leïla Halidou Diallo
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Valérie Brunchault
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Nathalie Laugero
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Florent Morfoisse
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Florian David
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Emilie Roussel
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Manon Nougue
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Audrey Zamora
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Emmanuelle Marchaud
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Florence Tatin
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Anne-Catherine Prats
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Barbara Garmy-Susini
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
| | - Luc DesGroseillers
- Département de Biochimie Et Médecine Moléculaire, Faculté de Médecine, Université de Montréal, 2900 Édouard Montpetit Montréal, Montreal, QC H3T 1J4, Canada;
| | - Eric Lacazette
- U1297-Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Toulouse, F-31432 Toulouse, France; (F.B.-M.); (L.H.D.); (V.B.); (N.L.); (F.M.); (F.D.); (E.R.); (M.N.); (A.Z.); (E.M.); (F.T.); (B.G.-S.)
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Bonnet-Magnaval F, DesGroseillers L. The Staufen1-dependent cell cycle regulon or how a misregulated RNA-binding protein leads to cancer. Biol Rev Camb Philos Soc 2021; 96:2192-2208. [PMID: 34018319 DOI: 10.1111/brv.12749] [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: 09/12/2020] [Revised: 05/11/2021] [Accepted: 05/13/2021] [Indexed: 12/12/2022]
Abstract
In recent years, an increasing number of reports have linked the RNA-binding protein Staufen1 (STAU1) to the control of cell decision making. In non-transformed cells, STAU1 balances the expression of messenger RNA (mRNA) regulons that regulate differentiation and well-ordered cell division. Misregulation of STAU1 expression and/or functions changes the fragile balance in the expression of pro- and anti-proliferative and apoptotic genes and favours a novel equilibrium that supports cell proliferation and cancer development. The misregulation of STAU1 functions causes multiple coordinated modest effects in the post-transcriptional regulation of many RNA targets that code for cell cycle regulators, leading to dramatic consequences at the cellular level. The new tumorigenic equilibrium in STAU1-mediated gene regulation observed in cancer cells can be further altered by a slight increase in STAU1 expression that favours expression of pro-apoptotic genes and cell death. The STAU1-dependent cell cycle regulon is a good model to study how abnormal expression of an RNA-binding protein promotes cell growth and provides an advantageous selection of malignant cells in the first step of cancer development.
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Affiliation(s)
- Florence Bonnet-Magnaval
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Luc DesGroseillers
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC, H3T 1J4, Canada
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Schieweck R, Ninkovic J, Kiebler MA. RNA-binding proteins balance brain function in health and disease. Physiol Rev 2020; 101:1309-1370. [PMID: 33000986 DOI: 10.1152/physrev.00047.2019] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Posttranscriptional gene expression including splicing, RNA transport, translation, and RNA decay provides an important regulatory layer in many if not all molecular pathways. Research in the last decades has positioned RNA-binding proteins (RBPs) right in the center of posttranscriptional gene regulation. Here, we propose interdependent networks of RBPs to regulate complex pathways within the central nervous system (CNS). These are involved in multiple aspects of neuronal development and functioning, including higher cognition. Therefore, it is not sufficient to unravel the individual contribution of a single RBP and its consequences but rather to study and understand the tight interplay between different RBPs. In this review, we summarize recent findings in the field of RBP biology and discuss the complex interplay between different RBPs. Second, we emphasize the underlying dynamics within an RBP network and how this might regulate key processes such as neurogenesis, synaptic transmission, and synaptic plasticity. Importantly, we envision that dysfunction of specific RBPs could lead to perturbation within the RBP network. This would have direct and indirect (compensatory) effects in mRNA binding and translational control leading to global changes in cellular expression programs in general and in synaptic plasticity in particular. Therefore, we focus on RBP dysfunction and how this might cause neuropsychiatric and neurodegenerative disorders. Based on recent findings, we propose that alterations in the entire regulatory RBP network might account for phenotypic dysfunctions observed in complex diseases including neurodegeneration, epilepsy, and autism spectrum disorders.
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Affiliation(s)
- Rico Schieweck
- Biomedical Center (BMC), Department for Cell Biology and Anatomy, Medical Faculty, Ludwig-Maximilians-University, Planegg-Martinsried, Germany
| | - Jovica Ninkovic
- Biomedical Center (BMC), Department for Cell Biology and Anatomy, Medical Faculty, Ludwig-Maximilians-University, Planegg-Martinsried, Germany
| | - Michael A Kiebler
- Biomedical Center (BMC), Department for Cell Biology and Anatomy, Medical Faculty, Ludwig-Maximilians-University, Planegg-Martinsried, Germany
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Yadav DK, Zigáčková D, Zlobina M, Klumpler T, Beaumont C, Kubíčková M, Vaňáčová Š, Lukavsky PJ. Staufen1 reads out structure and sequence features in ARF1 dsRNA for target recognition. Nucleic Acids Res 2020; 48:2091-2106. [PMID: 31875226 PMCID: PMC7038937 DOI: 10.1093/nar/gkz1163] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 11/22/2019] [Accepted: 12/05/2019] [Indexed: 12/13/2022] Open
Abstract
Staufen1 (STAU1) is a dsRNA binding protein mediating mRNA transport and localization, translational control and STAU1-mediated mRNA decay (SMD). The STAU1 binding site (SBS) within human ADP-ribosylation factor1 (ARF1) 3′UTR binds STAU1 and this downregulates ARF1 cytoplasmic mRNA levels by SMD. However, how STAU1 recognizes specific mRNA targets is still under debate. Our structure of the ARF1 SBS–STAU1 complex uncovers target recognition by STAU1. STAU1 dsRNA binding domain (dsRBD) 4 interacts with two pyrimidines and one purine from the minor groove side via helix α1, the β1–β2 loop anchors the dsRBD at the end of the dsRNA and lysines in helix α2 bind to the phosphodiester backbone from the major groove side. STAU1 dsRBD3 displays the same binding mode with specific recognition of one guanine base. Mutants disrupting minor groove recognition of ARF1 SBS affect in vitro binding and reduce SMD in vivo. Our data thus reveal how STAU1 recognizes minor groove features in dsRNA relevant for target selection.
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Affiliation(s)
- Deepak Kumar Yadav
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Dagmar Zigáčková
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Maria Zlobina
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Tomáš Klumpler
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Christelle Beaumont
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Monika Kubíčková
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Štěpánka Vaňáčová
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Peter J Lukavsky
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
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Heber S, Gáspár I, Tants JN, Günther J, Moya SMF, Janowski R, Ephrussi A, Sattler M, Niessing D. Staufen2-mediated RNA recognition and localization requires combinatorial action of multiple domains. Nat Commun 2019; 10:1659. [PMID: 30971701 PMCID: PMC6477676 DOI: 10.1038/s41467-019-09655-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 03/20/2019] [Indexed: 11/08/2022] Open
Abstract
Throughout metazoans, Staufen (Stau) proteins are core factors of mRNA localization particles. They consist of three to four double-stranded RNA binding domains (dsRBDs) and a C-terminal dsRBD-like domain. Mouse Staufen2 (mStau2)-like Drosophila Stau (dmStau) contains four dsRBDs. Existing data suggest that only dsRBDs 3-4 are necessary and sufficient for mRNA binding. Here, we show that dsRBDs 1 and 2 of mStau2 bind RNA with similar affinities and kinetics as dsRBDs 3 and 4. While RNA binding by these tandem domains is transient, all four dsRBDs recognize their target RNAs with high stability. Rescue experiments in Drosophila oocytes demonstrate that mStau2 partially rescues dmStau-dependent mRNA localization. In contrast, a rescue with mStau2 bearing RNA-binding mutations in dsRBD1-2 fails, confirming the physiological relevance of our findings. In summary, our data show that the dsRBDs 1-2 play essential roles in the mRNA recognition and function of Stau-family proteins of different species.
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Affiliation(s)
- Simone Heber
- Institute of Pharmaceutical Biotechnology, 89081 Ulm University, Ulm, Germany
- Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Imre Gáspár
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117, Heidelberg, Germany
- Institute of Molecular Biotechnology, 1030, Vienna, Austria
| | - Jan-Niklas Tants
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemistry, Technische Universität München, 85747, Garching, Germany
| | - Johannes Günther
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemistry, Technische Universität München, 85747, Garching, Germany
| | - Sandra M Fernandez Moya
- Biomedical Center Munich, Department of Cell Biology, Ludwig-Maximilians-Universität München, 82152, Planegg-Martinsried, Germany
| | - Robert Janowski
- Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Anne Ephrussi
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117, Heidelberg, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemistry, Technische Universität München, 85747, Garching, Germany
| | - Dierk Niessing
- Institute of Pharmaceutical Biotechnology, 89081 Ulm University, Ulm, Germany.
- Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
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7
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Berger SM, Fernández-Lamo I, Schönig K, Fernández Moya SM, Ehses J, Schieweck R, Clementi S, Enkel T, Grothe S, von Bohlen Und Halbach O, Segura I, Delgado-García JM, Gruart A, Kiebler MA, Bartsch D. Forebrain-specific, conditional silencing of Staufen2 alters synaptic plasticity, learning, and memory in rats. Genome Biol 2017; 18:222. [PMID: 29149906 PMCID: PMC5693596 DOI: 10.1186/s13059-017-1350-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/26/2017] [Indexed: 12/16/2022] Open
Abstract
Background Dendritic messenger RNA (mRNA) localization and subsequent local translation in dendrites critically contributes to synaptic plasticity and learning and memory. Little is known, however, about the contribution of RNA-binding proteins (RBPs) to these processes in vivo. Results To delineate the role of the double-stranded RBP Staufen2 (Stau2), we generate a transgenic rat model, in which Stau2 expression is conditionally silenced by Cre-inducible expression of a microRNA (miRNA) targeting Stau2 mRNA in adult forebrain neurons. Known physiological mRNA targets for Stau2, such as RhoA, Complexin 1, and Rgs4 mRNAs, are found to be dysregulated in brains of Stau2-deficient rats. In vivo electrophysiological recordings reveal synaptic strengthening upon stimulation, showing a shift in the frequency-response function of hippocampal synaptic plasticity to favor long-term potentiation and impair long-term depression in Stau2-deficient rats. These observations are accompanied by deficits in hippocampal spatial working memory, spatial novelty detection, and in tasks investigating associative learning and memory. Conclusions Together, these experiments reveal a critical contribution of Stau2 to various forms of synaptic plasticity including spatial working memory and cognitive management of new environmental information. These findings might contribute to the development of treatments for conditions associated with learning and memory deficits. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1350-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stefan M Berger
- Department of Molecular Biology, CIMH and Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany
| | - Iván Fernández-Lamo
- Division of Neurosciences, Pablo de Olavide University, 41013, Seville, Spain.,Present Address: Institute Cajal (CSIC), 28002, Madrid, Spain
| | - Kai Schönig
- Department of Molecular Biology, CIMH and Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany
| | - Sandra M Fernández Moya
- BioMedical Center, Medical Faculty, Ludwig Maximilians University, 82152, Planegg-Martinsried, Germany
| | - Janina Ehses
- BioMedical Center, Medical Faculty, Ludwig Maximilians University, 82152, Planegg-Martinsried, Germany
| | - Rico Schieweck
- BioMedical Center, Medical Faculty, Ludwig Maximilians University, 82152, Planegg-Martinsried, Germany
| | - Stefano Clementi
- Department of Molecular Biology, CIMH and Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany
| | - Thomas Enkel
- Department of Molecular Biology, CIMH and Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany
| | - Sascha Grothe
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, 17487, Greifswald, Germany
| | | | - Inmaculada Segura
- BioMedical Center, Medical Faculty, Ludwig Maximilians University, 82152, Planegg-Martinsried, Germany.
| | | | - Agnès Gruart
- Division of Neurosciences, Pablo de Olavide University, 41013, Seville, Spain
| | - Michael A Kiebler
- BioMedical Center, Medical Faculty, Ludwig Maximilians University, 82152, Planegg-Martinsried, Germany.
| | - Dusan Bartsch
- Department of Molecular Biology, CIMH and Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany.
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8
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Heraud-Farlow JE, Kiebler MA. The multifunctional Staufen proteins: conserved roles from neurogenesis to synaptic plasticity. Trends Neurosci 2014; 37:470-9. [PMID: 25012293 PMCID: PMC4156307 DOI: 10.1016/j.tins.2014.05.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/22/2014] [Accepted: 05/27/2014] [Indexed: 12/11/2022]
Abstract
Staufen (Stau) proteins have evolutionarily conserved functions in the brain. Stau proteins asymmetrically segregate mRNAs during mouse and fly neurogenesis. Stau proteins regulate synaptic plasticity and memory formation in flies and mammals. Stau proteins have roles in translation, localisation, and ribonucleoprotein formation. New data indicate that mammalian Stau1 and Stau2 can both stabilise and destabilise target mRNAs.
Staufen (Stau) proteins belong to a family of RNA-binding proteins (RBPs) that are important for RNA localisation in many organisms. In this review we discuss recent findings on the conserved role played by Stau during both the early differentiation of neurons and in the synaptic plasticity of mature neurons. Recent molecular data suggest mechanisms for how Stau2 regulates mRNA localisation, mRNA stability, translation, and ribonucleoprotein (RNP) assembly. We offer a perspective on how this multifunctional RBP has been adopted to regulate mRNA localisation under several different cellular and developmental conditions.
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Affiliation(s)
- Jacki E Heraud-Farlow
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Michael A Kiebler
- Department of Anatomy and Cell Biology, Ludwig-Maximilians-University, 80336 Munich, Germany.
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9
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Gleghorn ML, Maquat LE. 'Black sheep' that don't leave the double-stranded RNA-binding domain fold. Trends Biochem Sci 2014; 39:328-40. [PMID: 24954387 DOI: 10.1016/j.tibs.2014.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/19/2014] [Accepted: 05/19/2014] [Indexed: 12/28/2022]
Abstract
The canonical double-stranded RNA (dsRNA)-binding domain (dsRBD) is composed of an α1-β1-β2-β3-α2 secondary structure that folds in three dimensions to recognize dsRNA. Recently, structural and functional studies of divergent dsRBDs revealed adaptations that include intra- and/or intermolecular protein interactions, sometimes in the absence of detectable dsRNA-binding ability. We describe here how discrete dsRBD components can accommodate pronounced amino-acid sequence changes while maintaining the core fold. We exemplify the growing importance of divergent dsRBDs in mRNA decay by discussing Dicer, Staufen (STAU)1 and 2, trans-activation responsive RNA-binding protein (TARBP)2, protein activator of protein kinase RNA-activated (PKR) (PACT), DiGeorge syndrome critical region (DGCR)8, DEAH box helicase proteins (DHX) 9 and 30, and dsRBD-like fold-containing proteins that have ribosome-related functions. We also elaborate on the computational limitations to discovering yet-to-be-identified divergent dsRBDs.
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Affiliation(s)
- Michael L Gleghorn
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Center for RNA Biology, University of Rochester, Rochester, NY 14642, USA
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Center for RNA Biology, University of Rochester, Rochester, NY 14642, USA.
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10
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Balasanyan V, Arnold DB. Actin and myosin-dependent localization of mRNA to dendrites. PLoS One 2014; 9:e92349. [PMID: 24637809 PMCID: PMC3956895 DOI: 10.1371/journal.pone.0092349] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 02/19/2014] [Indexed: 12/04/2022] Open
Abstract
The localization of mRNAs within axons and dendrites allows neurons to manipulate protein levels in a time and location dependent manner and is essential for processes such as synaptic plasticity and axon guidance. However, an essential step in the process of mRNA localization, the decision to traffic to dendrites and/or axons, remains poorly understood. Here we show that Myosin Va and actin filaments are necessary for the dendritic localization of the mRNA binding protein Staufen 1 and of mRNA encoding the microtubule binding protein Map2. Blocking the function or expression of Myosin Va or depolymerizing actin filaments leads to localization of Staufen 1 and of Map2 mRNA in both axons and dendrites. Furthermore, interaction with Myosin Va plays an instructive role in the dendritic localization of Hermes 1, an RNA binding protein. Wild-type Hermes 1 localizes to both axons and dendrites, whereas Hermes 1 fused with a Myosin Va binding peptide, localizes specifically to dendrites. Thus, our results suggest that targeting of mRNAs to the dendrites is mediated by a mechanism that is dependent on actin and Myosin Va.
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Affiliation(s)
- Varuzhan Balasanyan
- Department of Biology, Program in Molecular and Computational Biology, University of Southern California, Los Angeles, California, United States of America
| | - Don B. Arnold
- Department of Biology, Program in Molecular and Computational Biology, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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11
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Staufen1 senses overall transcript secondary structure to regulate translation. Nat Struct Mol Biol 2013; 21:26-35. [PMID: 24336223 PMCID: PMC4605437 DOI: 10.1038/nsmb.2739] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 11/19/2013] [Indexed: 12/31/2022]
Abstract
Human Staufen1 (Stau1) is a double-stranded RNA (dsRNA)-binding protein implicated in multiple post-transcriptional gene-regulatory processes. Here we combined RNA immunoprecipitation in tandem (RIPiT) with RNase footprinting, formaldehyde cross-linking, sonication-mediated RNA fragmentation and deep sequencing to map Staufen1-binding sites transcriptome wide. We find that Stau1 binds complex secondary structures containing multiple short helices, many of which are formed by inverted Alu elements in annotated 3' untranslated regions (UTRs) or in 'strongly distal' 3' UTRs. Stau1 also interacts with actively translating ribosomes and with mRNA coding sequences (CDSs) and 3' UTRs in proportion to their GC content and propensity to form internal secondary structure. On mRNAs with high CDS GC content, higher Stau1 levels lead to greater ribosome densities, thus suggesting a general role for Stau1 in modulating translation elongation through structured CDS regions. Our results also indicate that Stau1 regulates translation of transcription-regulatory proteins.
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12
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Zivraj KH, Rehbein M, Ölschläger-Schütt J, Schob C, Falley K, Buck F, Schweizer M, Schepis A, Kremmer E, Richter D, Kreienkamp HJ, Kindler S. The RNA-binding protein MARTA2 regulates dendritic targeting of MAP2 mRNAs in rat neurons. J Neurochem 2013; 124:670-84. [PMID: 23121659 DOI: 10.1111/jnc.12079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/08/2012] [Accepted: 10/13/2012] [Indexed: 11/30/2022]
Abstract
Dendritic targeting of mRNAs encoding the microtubule-associated protein 2 (MAP2) in neurons involves a cis-acting dendritic targeting element. Two rat brain proteins, MAP2-RNA trans-acting protein (MARTA)1 and MARTA2, bind to the cis-element with both high affinity and specificity. In this study, affinity-purified MARTA2 was identified as orthologue of human far-upstream element binding protein 3. In neurons, it resides in somatodendritic granules and dendritic spines and associates with MAP2 mRNAs. Expression of a dominant-negative variant of MARTA2 disrupts dendritic targeting of endogenous MAP2 mRNAs, while not noticeably altering the level and subcellular distribution of polyadenylated mRNAs as a whole. Finally, MAP2 transcripts associate with the microtubule-based motor KIF5 and inhibition of KIF5, but not cytoplasmic dynein function disrupts extrasomatic trafficking of MAP2 mRNA granules. Thus, in neurons MARTA2 appears to represent a key trans-acting factor involved in KIF5-mediated dendritic targeting of MAP2 mRNAs.
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Affiliation(s)
- Krishna H Zivraj
- Institute for Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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13
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Martin F. Fifteen years of the yeast three-hybrid system: RNA-protein interactions under investigation. Methods 2012; 58:367-75. [PMID: 22841566 DOI: 10.1016/j.ymeth.2012.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 05/04/2012] [Accepted: 07/13/2012] [Indexed: 01/14/2023] Open
Abstract
In 1996, the Wickens and the Kuhl labs developed the yeast three-hybrid system independently. By expressing two chimeric proteins and one chimeric RNA molecule in Saccharomyces cerevisiae, this method allows in vivo monitoring of RNA-protein interactions by measuring the expression levels of HIS3 and LacZ reporter genes. Specific RNA targets have been used to characterize unknown RNA binding proteins. Previously described RNA binding proteins have also been used as bait to select new RNA targets. Finally, this method has been widely used to investigate or confirm previously suspected RNA-protein interactions. However, this method falls short in some aspects, such as RNA display and selection of false positive molecules. This review will summarize the results obtained with this method from the past 15years, as well as on recent efforts to improve its specificity.
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Affiliation(s)
- Franck Martin
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg CEDEX, France.
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14
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Synthesis of two SAPAP3 isoforms from a single mRNA is mediated via alternative translational initiation. Sci Rep 2012; 2:484. [PMID: 22761992 PMCID: PMC3387777 DOI: 10.1038/srep00484] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 05/31/2012] [Indexed: 01/01/2023] Open
Abstract
In mammalian neurons, targeting and translation of specific mRNAs in dendrites contribute to synaptic plasticity. After nuclear export, mRNAs designated for dendritic transport are generally assumed to be translationally dormant and activity of individual synapses may locally trigger their extrasomatic translation. We show that the long, GC-rich 5′-untranslated region of dendritic SAPAP3 mRNA restricts translation initiation via a mechanism that involves an upstream open reading frame (uORF). In addition, the uORF enables the use of an alternative translation start site, permitting synthesis of two SAPAP3 isoforms from a single mRNA. While both isoforms progressively accumulate at postsynaptic densities during early rat brain development, their levels relative to each other vary in different adult rat brain areas. Thus, alternative translation initiation events appear to regulate relative expression of distinct SAPAP3 isoforms in different brain regions, which may function to influence synaptic plasticity.
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15
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Zipcode binding protein 1 regulates the development of dendritic arbors in hippocampal neurons. J Neurosci 2011; 31:5271-85. [PMID: 21471362 DOI: 10.1523/jneurosci.2387-10.2011] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The pattern of dendritic branching, together with the density of synapses and receptor composition, defines the electrical properties of a neuron. The development of the dendritic arbor and its additional stabilization are highly orchestrated at the molecular level and are guided by intrinsic mechanisms and extracellular information. Although protein translation is known to contribute to these processes, the role of its local component has not been fully explored. For local translation, mRNAs are transported to dendrites in their dormant form as ribonucleoparticles (RNPs). We hypothesized that disturbing spatial mRNA distribution via RNP targeting may result in severe underdevelopment of the dendritic arbor. Zipcode binding protein 1 (ZBP1) controls β-actin mRNA transport and translation in dendrites. We showed that proper cellular levels of ZBP1, its ability to engage in mRNA binding, and Src-dependent release of mRNA cargo from ZBP1 are vital for dendritic arbor development in cultured rat hippocampal neurons. Moreover, β-actin overexpression significantly alleviated the effects of ZBP1 knockdown. These results suggest that ZBP1-dependent dendritic mRNA transport contributes to proper dendritic branching.
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16
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Kishore S, Luber S, Zavolan M. Deciphering the role of RNA-binding proteins in the post-transcriptional control of gene expression. Brief Funct Genomics 2010; 9:391-404. [PMID: 21127008 DOI: 10.1093/bfgp/elq028] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Eukaryotic cells express a large variety of ribonucleic acid-(RNA)-binding proteins (RBPs) with diverse affinity and specificity towards target RNAs that play a crucial role in almost every aspect of RNA metabolism. In addition, specific domains in RBPs impart catalytic activity or mediate protein-protein interactions, making RBPs versatile regulators of gene expression. In this review, we elaborate on recent experimental and computational approaches that have increased our understanding of RNA-protein interactions and their role in cellular function. We review aspects of gene expression that are modulated post-transcriptionally by RBPs, namely the stability of polymerase II-derived mRNA transcripts and their rate of translation into proteins. We further highlight the extensive regulatory networks of RBPs that implement a combinatorial control of gene expression. Taking cues from the recent development in the field, we argue that understanding spatio-temporal RNA-protein association on a transcriptome level will provide invaluable and unexpected insights into the regulatory codes that define growth, differentiation and disease.
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17
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Martel C, Dugré-Brisson S, Boulay K, Breton B, Lapointe G, Armando S, Trépanier V, Duchaîne T, Bouvier M, Desgroseillers L. Multimerization of Staufen1 in live cells. RNA (NEW YORK, N.Y.) 2010; 16:585-97. [PMID: 20075165 PMCID: PMC2822923 DOI: 10.1261/rna.1664210] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Transport of mRNA is an efficient mechanism to target proteins to specific regions of a cell. Although it is well documented that mRNAs are transported in ribonucleoprotein (RNP) complexes, several of the mechanisms involved in complex formation and localization are poorly understood. Staufen (Stau) 1, a double-stranded RNA-binding protein, is a well accepted marker of mRNA transport complexes. In this manuscript, we provide evidence that Stau1 self-associates in live cells using immunoprecipitation and bioluminescence resonance energy transfer (BRET) assays. The double-stranded RNA-binding domains dsRBD3 and dsRBD4 contributed about half of the signal, suggesting that Stau1 RNA-binding activity is involved in Stau1 self-association. Protein-protein interaction also occurred, via dsRBD5 and dsRBD2, as shown by in vitro pull-down, yeast two-hybrid, and BRET assays in live cells. Interestingly, Stau1 self-association contributes to the formation of oligomeric complexes as evidenced by the coexpression of split Renilla luciferase halves covalently linked to Stau1 in a protein complementation assay (PCA) combined with a BRET assay with Stau1-YFP. Moreover, we showed that these higher-order Stau1-containing complexes carry RNAs when the RNA stain SYTO 14 was used as the energy acceptor in the PCA/BRET assay. The oligomeric composition of Stau1-containing complexes and the presence of specific mRNAs have been confirmed by biochemical approaches involving two successive immunoprecipitations of Stau1-tagged molecules followed by qRT-PCR amplification. Altogether, these results indicate that Stau1 self-associates in mRNPs via its multiple functional domains that can select mRNAs to be transported and establish protein-protein interaction.
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Affiliation(s)
- Catherine Martel
- Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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18
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Falley K, Schütt J, Iglauer P, Menke K, Maas C, Kneussel M, Kindler S, Wouters FS, Richter D, Kreienkamp HJ. Shank1 mRNA: dendritic transport by kinesin and translational control by the 5'untranslated region. Traffic 2009; 10:844-57. [PMID: 19416473 DOI: 10.1111/j.1600-0854.2009.00912.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Dendritic mRNA transport coupled with local regulation of translation enables neurons to selectively alter the protein composition of individual postsynaptic sites. We have analyzed dendritic localization of shank1 mRNAs; shank proteins (shank1-3) are scaffolding molecules of the postsynaptic density (PSD) of excitatory synapses, which are crucial for PSD assembly and the formation of dendritic spines. Live cell imaging demonstrates saltatory movements of shank1 mRNA containing granules along microtubules in both anterograde and retrograde directions. A population of brain messenger ribonucleoprotein particles (mRNPs) containing shank1 mRNAs associates with the cargo-binding domain of the motor protein KIF5C. Through expression of dominant negative proteins, we show that dendritic targeting of shank1 mRNA granules involves KIF5C and the KIF5-associated RNA-binding protein staufen1. While transport of shank1 mRNAs follows principles previously outlined for other dendritic transcripts, shank1 mRNAs are distinguished by their translational regulation. Translation is strongly inhibited by a GC-rich 5(')untranslated region; in addition, internal ribosomal entry sites previously detected in other dendritic transcripts are absent in the shank1 mRNA. A concept emerges from our data in which dendritic transport of different mRNAs occurs collectively via a staufen1- and KIF5-dependent pathway, whereas their local translation is controlled individually by unique cis-acting elements.
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Affiliation(s)
- Katrin Falley
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf; Martinistrasse 52; 20246 Hamburg, Germany
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19
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Gong C, Kim YK, Woeller CF, Tang Y, Maquat LE. SMD and NMD are competitive pathways that contribute to myogenesis: effects on PAX3 and myogenin mRNAs. Genes Dev 2008; 23:54-66. [PMID: 19095803 DOI: 10.1101/gad.1717309] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
UPF1 functions in both Staufen 1 (STAU1)-mediated mRNA decay (SMD) and nonsense-mediated mRNA decay (NMD), which we show here are competitive pathways. STAU1- and UPF2-binding sites within UPF1 overlap so that STAU1 and UPF2 binding to UPF1 appear to be mutually exclusive. Furthermore, down-regulating the cellular abundance of STAU1, which inhibits SMD, increases the efficiency of NMD, whereas down-regulating the cellular abundance of UPF2, which inhibits NMD, increases the efficiency of SMD. Competition under physiological conditions is exemplified during the differentiation of C2C12 myoblasts to myotubes: The efficiency of SMD increases and the efficiency of NMD decreases, consistent with our finding that more STAU1 but less UPF2 bind UPF1 in myotubes compared with myoblasts. Moreover, an increase in the cellular level of UPF3X during myogenesis results in an increase in the efficiency of an alternative NMD pathway that, unlike classical NMD, is largely insensitive to UPF2 down-regulation. We discuss the remarkable balance between SMD and the two types of NMD in view of data indicating that PAX3 mRNA is an SMD target whose decay promotes myogenesis whereas myogenin mRNA is a classical NMD target encoding a protein required for myogenesis.
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Affiliation(s)
- Chenguang Gong
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
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20
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Poon MM, Choi SH, Jamieson CAM, Geschwind DH, Martin KC. Identification of process-localized mRNAs from cultured rodent hippocampal neurons. J Neurosci 2007; 26:13390-9. [PMID: 17182790 PMCID: PMC6675000 DOI: 10.1523/jneurosci.3432-06.2006] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The regulated translation of localized mRNAs in neurons provides a mechanism for spatially restricting gene expression in a synapse-specific manner. To identify the population of mRNAs present in distal neuronal processes of rodent hippocampal neurons, we grew neurons on polycarbonate filters etched with 3 microm pores. Although the neuronal cell bodies remained on the top surface of the filters, dendrites, axons, and glial processes penetrated through the pores to grow along the bottom surface of the membrane where they could be mechanically separated from cell bodies. Quantitative PCR and immunochemical analyses of the process preparation revealed that it was remarkably free of somatic contamination. Microarray analysis of RNA isolated from the processes identified over 100 potentially localized mRNAs. In situ hybridization studies of 19 of these transcripts confirmed that all 19 were present in dendrites, validating the utility of this approach for identifying dendritically localized transcripts. Many of the identified mRNAs encoded components of the translational machinery and several were associated with the RNA-binding protein Staufen. These findings indicate that there is a rich repertoire of mRNAs whose translation can be locally regulated and support the emerging idea that local protein synthesis serves to boost the translational capacity of synapses.
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Affiliation(s)
| | | | | | - Daniel H. Geschwind
- Program in Neurogenetics, Department of Neurology
- Department of Human Genetics
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, and
| | - Kelsey C. Martin
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, and
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
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21
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22
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Vessey JP, Vaccani A, Xie Y, Dahm R, Karra D, Kiebler MA, Macchi P. Dendritic localization of the translational repressor Pumilio 2 and its contribution to dendritic stress granules. J Neurosci 2006; 26:6496-508. [PMID: 16775137 PMCID: PMC6674044 DOI: 10.1523/jneurosci.0649-06.2006] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Pumilio (Pum) protein acts as a translational inhibitor in several organisms including yeast, Drosophila, Xenopus, and mammals. Two Pumilio genes, Pum1 and Pum2, have been identified in mammals, but their function in neurons has not been identified. In this study, we found that Pum2 mRNA is expressed during neuronal development and that the protein is found in discrete particles in both the cell body and the dendritic compartment of fully polarized neurons. This finding indicates that Pum2 is a novel candidate of dendritically localized ribonucleoparticles (RNPs). During metabolic stress, Pum2 is present in stress granules (SGs), which are subsequently detected in the somatodendritic domain. It remains excluded from processing bodies under all conditions. When overexpressed in neurons and fibroblasts, Pum2 induces the formation of SGs that also contain T-cell intracellular antigen 1 (TIA-1)-related protein, eukaryotic initiation factor 4E, poly(A)-binding protein, TIA-1, and other RNA-binding proteins including Staufen1 and Barentsz. This induction of SGs is dependent on the RNA-binding domain and a glutamine-rich region in the N terminus of Pum2. This glutamine-rich region behaves in a similar manner as TIA-1 and prion protein, two molecules with known roles in protein aggregation. Pum2 downregulation in neurons via RNA interference (RNAi) interferes with the formation of SGs during metabolic stress. Cotransfection with an RNAi-resistant portion of the Pum2 mRNA restores SG formation. These results suggest a role for Pum2 in dendritic RNPs and SG formation in mammalian neurons.
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23
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Martel C, Macchi P, Furic L, Kiebler M, Desgroseillers L. Staufen1 is imported into the nucleolus via a bipartite nuclear localization signal and several modulatory determinants. Biochem J 2006; 393:245-54. [PMID: 16162096 PMCID: PMC1383683 DOI: 10.1042/bj20050694] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Mammalian Stau1 (Staufen1), a modular protein composed of several dsRBDs (double-stranded RNA-binding domains), is probably involved in mRNA localization. Although Stau1 is mostly described in association with the rough endoplasmic reticulum and ribosomes in the cytoplasm, recent studies suggest that it may transit through the nucleus/nucleolus. Using a sensitive yeast import assay, we show that Stau1 is actively imported into the nucleus through a newly identified bipartite nuclear localization signal. As in yeast, the bipartite nuclear localization signal is necessary for Stau1 nuclear import in mammalian cells. It is also required for Stau1 nucleolar trafficking. However, Stau1 nuclear transit seems to be regulated by mechanisms that involve cytoplasmic retention and/or facilitated nuclear export. Cytoplasmic retention is mainly achieved through the action of dsRBD3, with dsRBD2 playing a supporting role in this function. Similarly, dsRBD3, but not its RNA-binding activity, is critical for Stau1 nucleolar trafficking. The function of dsRBD3 is strengthened or stabilized by the presence of dsRBD4 but prevented by the interdomain between dsRBD2 and dsRBD3. Altogether, these results suggest that Stau1 nuclear trafficking is a highly regulated process involving several determinants. The presence of Stau1 in the nucleus/nucleolus suggests that it may be involved in ribonucleoprotein formation in the nucleus and/or in other nuclear functions not necessarily related to mRNA transport.
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Affiliation(s)
- Catherine Martel
- *Department of Biochemistry, University of Montreal, P.O. Box 6128, Station Centre Ville, Montreal, Canada H3C 3J7
| | - Paolo Macchi
- †Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Luc Furic
- *Department of Biochemistry, University of Montreal, P.O. Box 6128, Station Centre Ville, Montreal, Canada H3C 3J7
| | - Michael A. Kiebler
- †Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Luc Desgroseillers
- *Department of Biochemistry, University of Montreal, P.O. Box 6128, Station Centre Ville, Montreal, Canada H3C 3J7
- To whom correspondence should be addressed (email )
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Ramasamy S, Wang H, Quach HNB, Sampath K. Zebrafish Staufen1 and Staufen2 are required for the survival and migration of primordial germ cells. Dev Biol 2006; 292:393-406. [PMID: 16513105 DOI: 10.1016/j.ydbio.2006.01.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 01/11/2006] [Accepted: 01/12/2006] [Indexed: 11/15/2022]
Abstract
In sexually reproducing organisms, primordial germ cells (PGCs) give rise to the cells of the germ line, the gametes. In many animals, PGCs are set apart from somatic cells early during embryogenesis. Work in Drosophila, C. elegans, Xenopus, and zebrafish has shown that maternally provided localized cytoplasmic determinants specify the germ line in these organisms (Raz, E., 2003. Primordial germ-cell development: the zebrafish perspective. Nat. Rev., Genet. 4, 690--700; Santos, A.C., Lehmann, R., 2004. Germ cell specification and migration in Drosophila and beyond. Curr. Biol. 14, R578-R589). The Drosophila RNA-binding protein, Staufen is required for germ cell formation, and mutations in stau result in a maternal effect grandchild-less phenotype (Schupbach,T., Weischaus, E., 1989. Female sterile mutations on the second chromosome of Drosophila melanogaster:1. Maternal effect mutations. Genetics 121, 101-17). Here we describe the functions of two zebrafish Staufen-related proteins, Stau1 and Stau2. When Stau1 or Stau2 functions are compromised in embryos by injecting antisense morpholino modified oligonucleotides or dominant-negative Stau peptides, germ layer patterning is not affected. However, expression of the PGC marker vasa is not maintained. Furthermore, expression of a green fluorescent protein (GFP):nanos 3'UTR fusion protein in germ cells shows that PGC migration is aberrant, and the mis-migrating PGCs do not survive in Stau-compromised embryos. Stau2 is also required for survival of neurons in the central nervous system (CNS). These phenotypes are rescued by co-injection of Drosophila stau mRNA. Thus, staufen has an evolutionarily conserved function in germ cells. In addition, we have identified a function for Stau proteins in PGC migration.
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Affiliation(s)
- Srinivas Ramasamy
- Vertebrate Development Group, Temasek Life Sciences Laboratory, 1 Research link, National University of Singapore, 117604, Singapore
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25
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Abstract
In eukaryotes, the entwined pathways of RNA transport and local translational regulation are key determinants in the spatio-temporal articulation of gene expression. One of the main advantages of this mechanism over transcriptional control in the nucleus lies in the fact that it endows local sites with independent decision-making authority, a consideration that is of particular relevance in cells with complex cellular architecture such as neurons. Localized RNAs typically contain codes, expressed within cis-acting elements, that specify subcellular targeting. Such codes are recognized by trans-acting factors, adaptors that mediate translocation along cytoskeletal elements by molecular motors. Most transported mRNAs are assumed translationally dormant while en route. In some cell types, especially in neurons, it is considered crucial that translation remains repressed after arrival at the destination site (e.g., a postsynaptic microdomain) until an appropriate activation signal is received. Several candidate mechanisms have been suggested to participate in the local implementation of translational repression and activation, and such mechanisms may target translation at the level of initiation and/or elongation. Recent data indicate that untranslated RNAs may play important roles in the local control of translation.
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Affiliation(s)
- Stefan Kindler
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, University of Hamburg, D-20246 Hamburg, Germany.
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26
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Iijima T, Imai T, Kimura Y, Bernstein A, Okano HJ, Yuzaki M, Okano H. Hzf protein regulates dendritic localization and BDNF-induced translation of type 1 inositol 1,4,5-trisphosphate receptor mRNA. Proc Natl Acad Sci U S A 2005; 102:17190-5. [PMID: 16286649 PMCID: PMC1287977 DOI: 10.1073/pnas.0504684102] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 10/10/2005] [Indexed: 11/18/2022] Open
Abstract
The localization of certain mRNAs to dendrites and their local translation in synaptic regions are proposed to be involved in certain aspects of synaptic plasticity. A cis-acting element within the 3' untranslated region (3' UTR) of the targeted mRNAs, which is bound by a trans-acting RNA-binding protein, controls the dendritic mRNA localization. Here, we identified hematopoietic zinc finger (Hzf) as a trans-acting factor that regulates the dendritic mRNA localization of the type 1 inositol 1,4,5-trisphosphate receptor (IP(3)RI), a dendritically localized mRNA in cerebellar Purkinje cells, via binding to the 3' UTR. In Hzf-deficient mice, the dendritic localization of IP(3)RI mRNA and brain-derived neurotrophic factor-induced IP(3)RI protein synthesis in the cerebellum were impaired. These findings suggest that Hzf is an RNA-binding protein that controls the dendritic mRNA localization and activity-dependent translation of IP(3)RI, and may be involved in some aspects of synaptic plasticity.
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Affiliation(s)
- Takatoshi Iijima
- Department of Physiology, Keio University School of Medicine, Shinjuku, Tokyo 160-8582, Japan
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27
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Monshausen M, Gehring NH, Kosik KS. The mammalian RNA-binding protein Staufen2 links nuclear and cytoplasmic RNA processing pathways in neurons. Neuromolecular Med 2005; 6:127-44. [PMID: 15970630 DOI: 10.1385/nmm:6:2-3:127] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 02/21/2005] [Accepted: 03/23/2005] [Indexed: 11/11/2022]
Abstract
Members of the Staufen family of RNA-binding proteins are highly conserved cytoplasmic RNA transporters associated with RNA granules. staufen2 is specifically expressed in neurons where the delivery of RNA to dendrites is thought to have a role in plasticity. We found that Staufen2 interacts with the nuclear pore protein p62, with the RNA export protein Tap and with the exon-exon junction complex (EJC) proteins Y14-Mago. The interaction of Staufen2 with the Y14-Mago heterodimer seems to represent a highly conserved complex as the same proteins are involved in the Staufen-mediated localization of oskar mRNA in Drosophila oocytes. A pool of Staufen2 is present in neuronal nuclei and colocalizes to a large degree with p62 and partly with Tap, Y14, and Mago. We suggest a model whereby a set of conserved genes in the oskar mRNA export pathway may be recruited to direct a dendritic destination for mRNAs originating as a Staufen2 nuclear complex.
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Affiliation(s)
- Michaela Monshausen
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Abstract
Fragile X syndrome (FXS) is caused by the transcriptional silencing of the Fmr1 gene, which encodes a protein (FMRP) that can act as a translational suppressor in dendrites, and is characterized by a preponderance of abnormally long, thin and tortuous dendritic spines. According to a current theory of FXS, the loss of FMRP expression leads to an exaggeration of translation responses linked to group I metabotropic glutamate receptors. Such responses are involved in the consolidation of a form of long-term depression that is enhanced in Fmr1 knockout mice and in the elongation of dendritic spines, resembling synaptic phenotypes over-represented in fragile X brain. These observations place fragile X research at the heart of a long-standing issue in neuroscience. The consolidation of memory, and several distinct forms of synaptic plasticity considered to be substrates of memory, requires mRNA translation and is associated with changes in spine morphology. A recent convergence of research on FXS and on the involvement of translation in various forms of synaptic plasticity has been very informative on this issue and on mechanisms underlying FXS. Evidence suggests a general relationship in which the receptors that induce distinct forms of efficacy change differentially regulate translation to produce unique spine shapes involved in their consolidation. We discuss several potential mechanisms for differential translation and the notion that FXS represents an exaggeration of one 'channel' in a set of translation-dependent consolidation responses.
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Affiliation(s)
- P W Vanderklish
- Department of Neurobiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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29
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Abstract
RNA-binding proteins play a major part in the control of gene expression during early development. At this stage, the majority of regulation occurs at the levels of translation and RNA localization. These processes are, in general, mediated by RNA-binding proteins interacting with specific sequence motifs in the 3'-untranslated regions of their target RNAs. Although initial work concentrated on the analysis of these sequences and their trans-acting factors, we are now beginning to gain an understanding of the mechanisms by which some of these proteins function. In this review, we will describe a number of different families of RNA-binding proteins, grouping them together on the basis of common regulatory strategies, and emphasizing the recurrent themes that occur, both across different species and as a response to different biological problems.
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30
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Kim YK, Furic L, Desgroseillers L, Maquat LE. Mammalian Staufen1 recruits Upf1 to specific mRNA 3'UTRs so as to elicit mRNA decay. Cell 2005; 120:195-208. [PMID: 15680326 DOI: 10.1016/j.cell.2004.11.050] [Citation(s) in RCA: 399] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 11/11/2004] [Accepted: 11/24/2004] [Indexed: 10/25/2022]
Abstract
Mammalian Staufen (Stau)1 is an RNA binding protein that is thought to function in mRNA transport and translational control. Nonsense-mediated mRNA decay (NMD) degrades abnormal and natural mRNAs that terminate translation sufficiently upstream of a splicing-generated exon-exon junction. Here we describe an mRNA decay mechanism that involves Stau1, the NMD factor Upf1, and a termination codon. Unlike NMD, this mechanism does not involve pre-mRNA splicing and occurs when Upf2 or Upf3X is downregulated. Stau1 binds directly to Upf1 and elicits mRNA decay when tethered downstream of a termination codon. Stau1 also interacts with the 3'-untranslated region of ADP-ribosylation factor (Arf)1 mRNA. Accordingly, downregulating either Stau1 or Upf1 increases Arf1 mRNA stability. These findings suggest that Arf1 mRNA is a natural target for Stau1-mediated decay, and data indicate that other mRNAs are also natural targets. We discuss this pathway as a means for cells to downregulate the expression of Stau1 binding transcripts.
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Affiliation(s)
- Yoon Ki Kim
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, 601 Elmwood Avenue, Box 712, University of Rochester, Rochester, NY 14642, USA
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31
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Stamm S, Ben-Ari S, Rafalska I, Tang Y, Zhang Z, Toiber D, Thanaraj TA, Soreq H. Function of alternative splicing. Gene 2004; 344:1-20. [PMID: 15656968 DOI: 10.1016/j.gene.2004.10.022] [Citation(s) in RCA: 651] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 09/10/2004] [Accepted: 10/21/2004] [Indexed: 02/06/2023]
Abstract
Alternative splicing is one of the most important mechanisms to generate a large number of mRNA and protein isoforms from the surprisingly low number of human genes. Unlike promoter activity, which primarily regulates the amount of transcripts, alternative splicing changes the structure of transcripts and their encoded proteins. Together with nonsense-mediated decay (NMD), at least 25% of all alternative exons are predicted to regulate transcript abundance. Molecular analyses during the last decade demonstrate that alternative splicing determines the binding properties, intracellular localization, enzymatic activity, protein stability and posttranslational modifications of a large number of proteins. The magnitude of the effects range from a complete loss of function or acquisition of a new function to very subtle modulations, which are observed in the majority of cases reported. Alternative splicing factors regulate multiple pre-mRNAs and recent identification of physiological targets shows that a specific splicing factor regulates pre-mRNAs with coherent biological functions. Therefore, evidence is now accumulating that alternative splicing coordinates physiologically meaningful changes in protein isoform expression and is a key mechanism to generate the complex proteome of multicellular organisms.
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Affiliation(s)
- Stefan Stamm
- Institute for Biochemistry, University of Erlangen, Fahrstrasse 17, 91054 Erlangen, Germany.
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32
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Brendel C, Rehbein M, Kreienkamp HJ, Buck F, Richter D, Kindler S. Characterization of Staufen 1 ribonucleoprotein complexes. Biochem J 2004; 384:239-46. [PMID: 15303970 PMCID: PMC1134106 DOI: 10.1042/bj20040812] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 07/21/2004] [Accepted: 08/10/2004] [Indexed: 10/26/2022]
Abstract
In Drosophila oocytes and neuroblasts, the double-stranded RNA binding protein Staufen assembles into ribonucleoprotein particles, which mediate cytoplasmic mRNA trafficking and translation. Two different mammalian orthologues also appear to reside in distinct RNA-containing particles. To date, relatively little is known about the molecular composition of Staufen-containing ribonucleoprotein complexes. Here, we have used a novel one-step affinity purification protocol to identify components of Staufen 1-containing particles. Whereas the nucleocytoplasmic RNA-binding protein nucleolin is linked to Staufen in an RNA-dependent manner, the association of protein phosphatase 1, the microtubule-dependent motor protein kinesin and several components of the large and small ribosomal subunits with Staufen ribonucleoprotein complexes is RNA-independent. Notably, all these components do not co-purify with a second RNA-binding protein, hnRNPK (heterogeneous ribonucleoprotein K), demonstrating the high specificity of the purification protocol. Furthermore, pull-down and immunoprecipitation experiments suggest a direct interaction between Staufen 1 and the ribosomal protein P0 in vitro as well as in cells. In cell fractionation and sucrose gradient assays, Staufen co-fractionates with intact ribosomes and polysomes, but not with the isolated 40 S ribosomal subunit. Taken together, these findings imply that, in the cytoplasm of mammalian cells, an association with the ribosomal P-stalk protein P0 recruits Staufen 1 into ribosome-containing ribonucleoprotein particles, which also contain kinesin, protein phosphatase 1 and nucleolin.
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Key Words
- ribonucleoprotein particle
- ribosome
- rna sorting
- rna-binding protein
- translation
- dsrbd, double-stranded rna-binding domain
- ef1α, elongation factor 1α
- (e)gfp, (enhanced) green fluorescent protein
- fmrp, fragile x mental retardation protein 1
- gkap/sapap1, guanylate kinase-associated protein/sap90/psd-95-associated protein
- gst, glutathione s-transferase
- hek, human embryonic kidney
- hnrnp(k/u), heterogeneous ribonucleoprotein k or u respectively
- ip buffer, immunoprecipitation buffer
- pp1, protein phosphatase-1
- (m)rnp, (messenger) ribonucleoprotein particle
- nfar, nuclear factor associated with double-stranded rna
- pabp, poly(a)+-binding protein
- rha, rna helicase a
- rstau, rat staufen
- sstrip, somatostatin receptor-interacting protein
- stau1, staufen 1
- stau2, staufen 2
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Affiliation(s)
- Cornelia Brendel
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Monika Rehbein
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Hans-Jürgen Kreienkamp
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Friedrich Buck
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Dietmar Richter
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Stefan Kindler
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany
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Thomas MG, Martinez Tosar LJ, Loschi M, Pasquini JM, Correale J, Kindler S, Boccaccio GL. Staufen recruitment into stress granules does not affect early mRNA transport in oligodendrocytes. Mol Biol Cell 2004; 16:405-20. [PMID: 15525674 PMCID: PMC539183 DOI: 10.1091/mbc.e04-06-0516] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Staufen is a conserved double-stranded RNA-binding protein required for mRNA localization in Drosophila oocytes and embryos. The mammalian homologues Staufen 1 and Staufen 2 have been implicated in dendritic RNA targeting in neurons. Here we show that in rodent oligodendrocytes, these two proteins are present in two independent sets of RNA granules located at the distal myelinating processes. A third kind of RNA granules lacks Staufen and contains major myelin mRNAs. Myelin Staufen granules associate with microfilaments and microtubules, and their subcellular distribution is affected by polysome-disrupting drugs. Under oxidative stress, both Staufen 1 and Staufen 2 are recruited into stress granules (SGs), which are stress-induced organelles containing transiently silenced messengers. Staufen SGs contain the poly(A)-binding protein (PABP), the RNA-binding proteins HuR and TIAR, and small but not large ribosomal subunits. Staufen recruitment into perinuclear SGs is paralleled by a similar change in the overall localization of polyadenylated RNA. Under the same conditions, the distribution of recently transcribed and exported mRNAs is not affected. Our results indicate that Staufen 1 and Staufen 2 are novel and ubiquitous SG components and suggest that Staufen RNPs are involved in repositioning of most polysomal mRNAs, but not of recently synthesized transcripts, during the stress response.
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MESH Headings
- Actin Cytoskeleton/metabolism
- Alternative Splicing
- Animals
- Animals, Newborn
- Biological Transport
- Blotting, Western
- Brain/metabolism
- Cloning, Molecular
- Computer Simulation
- Cytoplasm/metabolism
- In Situ Hybridization, Fluorescence
- Microscopy, Confocal
- Microscopy, Fluorescence
- Microtubules/metabolism
- Models, Genetic
- Myelin Sheath/metabolism
- Oligodendroglia/metabolism
- Oxidative Stress
- Polyribosomes/metabolism
- Protein Structure, Tertiary
- RNA/metabolism
- RNA, Double-Stranded/chemistry
- RNA, Messenger/metabolism
- RNA-Binding Proteins/biosynthesis
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/physiology
- Rats
- Rats, Sprague-Dawley
- Ribonucleases/metabolism
- Ribosomes/metabolism
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Affiliation(s)
- María G Thomas
- Fundación Instituto Leloir, IIB Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, IIBBA-CONICET, Buenos Aires, Argentina
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Allison R, Czaplinski K, Git A, Adegbenro E, Stennard F, Houliston E, Standart N. Two distinct Staufen isoforms in Xenopus are vegetally localized during oogenesis. RNA (NEW YORK, N.Y.) 2004; 10:1751-63. [PMID: 15496522 PMCID: PMC1370663 DOI: 10.1261/rna.7450204] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 08/06/2004] [Indexed: 05/21/2023]
Abstract
Localization of mRNA is an important way of generating early asymmetries in the developing embryo. In Drosophila, Staufen is intimately involved in the localization of maternally inherited mRNAs critical for cell fate determination in the embryo. We show that double-stranded RNA-binding Staufen proteins are present in the oocytes of a vertebrate, Xenopus, and are localized to the vegetal cytoplasm, a region where important mRNAs including VegT and Vg1 mRNA become localized. We identified two Staufen isoforms named XStau1 and XStau2, where XStau1 was found to be the principal Staufen protein in oocytes, eggs, and embryos, the levels of both proteins peaking during mid-oogenesis. In adults, Xenopus Staufens are principally expressed in ovary and testis. XStau1 was detectable throughout the oocyte cytoplasm by immunofluorescence and was concentrated in the vegetal cortical region from stage II onward. It showed partial codistribution with subcortical endoplasmic reticulum (ER), raising the possibility that Staufen may anchor mRNAs to specific ER-rich domains. We further showed that XStau proteins are transiently phosphorylated by the MAPK pathway during meiotic maturation, a period during which RNAs such as Vg1 RNA are released from their tight localization at the vegetal cortex. These findings provide evidence that Staufen proteins are involved in targeting and/or anchoring of maternal determinants to the vegetal cortex of the oocyte in Xenopus. The Xenopus oocyte should thus provide a valuable system to dissect the role of Staufen proteins in RNA localization and vertebrate development.
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Affiliation(s)
- Rachel Allison
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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35
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Kindler S, Rehbein M, Classen B, Richter D, Böckers TM. Distinct spatiotemporal expression of SAPAP transcripts in the developing rat brain: a novel dendritically localized mRNA. ACTA ACUST UNITED AC 2004; 126:14-21. [PMID: 15207911 DOI: 10.1016/j.molbrainres.2004.03.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2004] [Indexed: 11/19/2022]
Abstract
The four members of the family of synapse-associated protein 90/postsynaptic density-95-associated proteins (SAPAP1-4) are adapter proteins of postsynaptic density (PSD). They interact with different synaptic scaffolding proteins, cytoskeletal components, and signalling components, and are therefore considered to assemble functional multiprotein units at synapses. Here, we analyzed the spatiotemporal expression of SAPAP1-SAPAP4 genes in postnatal rat brain by in situ hybridization. All four genes are expressed in many brain areas, leading to overlapping yet distinct mRNA distribution patterns. Moreover, two mRNAs encoding distinct SAPAP3 isoforms exhibit basically identical postnatal expression patterns. In the hippocampus, SAPAP1, SAPAP2, and SAPAP4 transcripts are restricted to cell body zones, whereas SAPAP3 mRNAs are also detected in molecular layers. Thus, SAPAP3 is one of the few PSD components whose local synthesis in dendrites may contribute to an input-specific adaptation of dendritic spine function.
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Affiliation(s)
- Stefan Kindler
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, Hamburg D-20246, Germany.
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36
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Böckers TM, Segger-Junius M, Iglauer P, Bockmann J, Gundelfinger ED, Kreutz MR, Richter D, Kindler S, Kreienkamp HJ. Differential expression and dendritic transcript localization of Shank family members: identification of a dendritic targeting element in the 3' untranslated region of Shank1 mRNA. Mol Cell Neurosci 2004; 26:182-90. [PMID: 15121189 DOI: 10.1016/j.mcn.2004.01.009] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2003] [Revised: 01/09/2004] [Accepted: 01/16/2004] [Indexed: 11/19/2022] Open
Abstract
Shank proteins are scaffolding proteins in the postsynaptic density of excitatory synapses in the mammalian brain. In situ hybridization revealed that Shank1/SSTRIP and Shank2/ProSAP1 mRNAs are widely expressed early in postnatal brain development whereas Shank3/ProSAP2 expression increases during postnatal development especially in the cerebellum and thalamus. Shank1 and Shank3 (but not Shank2) mRNAs are present in the molecular layers of the hippocampus, consistent with a dendritic transcript localization. Shank1 and Shank2 transcripts are detectable in the dendritic fields of Purkinje cells, whereas Shank3 mRNA is restricted to cerebellar granule cells. The appearance of dendritic Shank mRNAs in cerebellar Purkinje cells coincides with the onset of dendrite formation. Expression of reporter transcripts in hippocampal neurons identifies a 200-nucleotide dendritic targeting element (DTE) in the Shank1 mRNA. The widespread presence of Shank mRNAs in dendrites suggests a role for local synthesis of Shanks in response to stimuli that induce alterations in synaptic morphology.
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Affiliation(s)
- Tobias M Böckers
- Institut für Anatomie Westfälishe Wilhelms-Universität-Münster, Germany
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37
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Fujimoto T, Tanaka H, Kumamaru E, Okamura K, Miki N. Arc interacts with microtubules/microtubule-associated protein 2 and attenuates microtubule-associated protein 2 immunoreactivity in the dendrites. J Neurosci Res 2004; 76:51-63. [PMID: 15048929 DOI: 10.1002/jnr.20056] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Arc, activity-regulated cytoskeleton-associated gene, is an immediate early gene, and its expression is regulated by a variety of stimuli, such as electric stimulation and methamphetamine. The function of Arc, however, is unknown. To explore this function, we carried out expression experiments by transfecting green fluorescent protein (GFP)-Arc constructs or by using a protein transduction system in hippocampal cultured neurons. We found that the overexpression of Arc as well as Arc induction by seizure in vivo decreased microtubule-associated protein 2 (MAP2) staining in the dendrites by immunocytochemistry, although MAP2 content was not changed on Western blot. Furthermore, Arc interacted with newly polymerized microtubules and MAP2, leading to blocking of the epitope of MAP2. The data suggest that Arc increased by synaptic activities would trigger dendritic remodeling by interacting with cytoskeletal proteins.
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Affiliation(s)
- Takahiro Fujimoto
- Department of Pharmacology, Osaka University Medical School, Suita, Osaka, Japan
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38
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Irion U, Leptin M, Siller K, Fuerstenberg S, Cai Y, Doe CQ, Chia W, Yang X. Abstrakt, a DEAD box protein, regulates Insc levels and asymmetric division of neural and mesodermal progenitors. Curr Biol 2004; 14:138-44. [PMID: 14738736 DOI: 10.1016/j.cub.2004.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Asymmetric cell division generates cell diversity in bacteria, yeast, and higher eukaryotes. In Drosophila, both neural and muscle progenitors divide asymmetrically. In these cells the Inscuteable (Insc) protein complex coordinates cell polarity and spindle orientation. Abstrakt (Abs) is a DEAD-box protein that regulates aspects of cell polarity in oocytes and embryos. We use a conditional allele of abs to investigate its role in neural and muscle progenitor cell polarity. In neuroblasts we observe loss of apical Insc crescents, failure in basal protein targeting, and defects in spindle orientation. In the GMC4-2a cell we observe loss of apical Insc crescents, defects in basal protein targeting, and equalization of sibling neuron fates; muscle precursors show a similar equalization of sibling cell fates. These phenotypes resemble those of insc mutants; indeed, abs mutants show a striking loss of Insc protein levels but no change of insc RNA levels. Furthermore, we find that the Abs protein physically interacts with insc RNA. Our results demonstrate a novel role for Abs in the posttranscriptional regulation of insc expression, which is essential for proper cell polarity, spindle orientation, and the establishment of distinct sibling cell fates within embryonic neural and muscle progenitors.
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Affiliation(s)
- Uwe Irion
- Institut für Genetik, Universität zu Köln, Weyertal 121, D-50931, Cologne, Germany
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39
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Abstract
In 1996, a new method, termed the yeast three-hybrid system, dedicated to selection of RNA binding proteins using a hybrid RNA molecule as bait was described. In this minireview, we summarize the results that have been obtained using this method. Indeed, approximately 20 unknown proteins have been characterized so far. The three-hybrid strategy has also been used as a tool to dissect RNA-protein interactions. The example of such a study on human histone HBP interaction with its target mRNA is described. Problems that can be encountered are addressed in a troubleshooting section. Especially, our results with tRNA binding proteins are discussed.
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Affiliation(s)
- Sophie Jaeger
- Institut de Biologie Moléculaire et Cellulaire, UPR No. 9002 du CNRS, 15 rue René Descartes, 67084 Cedex, Strasbourg, France
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40
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Barentsz, a new component of the Staufen-containing ribonucleoprotein particles in mammalian cells, interacts with Staufen in an RNA-dependent manner. J Neurosci 2003. [PMID: 12843282 DOI: 10.1523/jneurosci.23-13-05778.2003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Staufen1, the mammalian homolog of Drosophila Staufen, assembles into ribonucleoprotein particles (RNPs), which are thought to transport and localize RNA into dendrites of mature hippocampal neurons. We therefore investigated whether additional components of the RNA localization complex besides Staufen are conserved. One candidate is the mammalian homolog of Drosophila Barentsz (Btz), which is essential for the localization of oskar mRNA to the posterior pole of the Drosophila oocyte and is a component of the oskar RNA localization complex along with Staufen. In this study, we report the characterization of mammalian Btz, which behaves like a nucleocytoplasmic shuttling protein. When expressed in the Drosophila egg chamber, mammalian Btz is still able to interact with Drosophila Staufen and reach the posterior pole in the wild-type oocyte, but does not rescue the btz mutant phenotype. Most interestingly, we show by immunoprecipitation assays that Btz interacts with mammalian Staufen in an RNA-dependent manner through a conserved domain, which encompasses the region of homology to the Drosophila Btz protein and contains a novel conserved motif. One candidate for an RNA that mediates this interaction is the dendritically localized brain cytoplasmic 1 transcript. In addition, Btz and Staufen1 colocalize within particles in the cell body and, to a more variable extent, in dendrites of mature hippocampal neurons. Together, our data suggest that the mRNA transport machinery is conserved during evolution, and that mammalian Btz is an additional component of the dendritic RNPs in hippocampal neurons.
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41
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Bélanger G, Stocksley MA, Vandromme M, Schaeffer L, Furic L, DesGroseillers L, Jasmin BJ. Localization of the RNA-binding proteins Staufen1 and Staufen2 at the mammalian neuromuscular junction. J Neurochem 2003; 86:669-77. [PMID: 12859680 DOI: 10.1046/j.1471-4159.2003.01883.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Staufen is an RNA-binding protein, first identified for its role in oogenesis and CNS development in Drosophila. Two mammalian homologs of Staufen have been identified and shown to bind double-stranded RNA and tubulin, and to function in the somatodendritic transport of mRNA in neurons. Here, we examined whether Staufen proteins are expressed in skeletal muscle in relation to the neuromuscular junction. Immunofluorescence experiments revealed that Staufen1 (Stau1) and Staufen2 (Stau2) accumulate preferentially within the postsynaptic sarcoplasm of muscle fibers as well as at newly formed ectopic synapses. Western blot analyses showed that the levels of Stau1 and Stau2 are greater in slow muscles than in fast-twitch muscles. Muscle denervation induced a significant increase in the expression of Stau1 and Stau2 in the extrasynaptic compartment of both fast and slow muscles. Consistent with these observations, we also demonstrated that expression of Stau1 and Stau2 is increased during myogenic differentiation and that treatment of myotubes with agrin and neuregulin induces a further increase in the expression of both Staufen proteins. We propose that Stau1 and Stau2 are key components of the postsynaptic apparatus in muscle, and that they contribute to the maturation and plasticity of the neuromuscular junction.
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MESH Headings
- Agrin/pharmacology
- Animals
- Blotting, Western
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Line
- Mice
- Mice, Inbred C57BL
- Muscle Denervation
- Muscle Fibers, Fast-Twitch/chemistry
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Slow-Twitch/chemistry
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- Myoblasts/cytology
- Myoblasts/metabolism
- Nerve Tissue Proteins/analysis
- Nerve Tissue Proteins/biosynthesis
- Neuregulins/pharmacology
- Neuromuscular Junction/metabolism
- RNA-Binding Proteins/analysis
- RNA-Binding Proteins/biosynthesis
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Affiliation(s)
- Guy Bélanger
- Department of Cellular and Molecular Medicine, and Center for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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42
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Activity-dependent trafficking and dynamic localization of zipcode binding protein 1 and beta-actin mRNA in dendrites and spines of hippocampal neurons. J Neurosci 2003. [PMID: 12716932 DOI: 10.1523/jneurosci.23-08-03251.2003] [Citation(s) in RCA: 220] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
RNA binding proteins may be important mediators of the activity-dependent transport of mRNAs to dendritic spines of activated synapses. We used fluorescence microscopy and digital imaging techniques applied to both fixed and live cultured hippocampal neurons to visualize the localization of the mRNA binding protein, zipcode binding protein 1 (ZBP1), and its dynamic movements in response to KCl-induced depolarization at high spatial and temporal resolution. With the use of immunofluorescence, image deconvolution, and three-dimensional reconstruction, ZBP1 was localized in the form of granules that were distributed in dendrites, spines, and subsynaptic sites. KCl depolarization increased the dendritic localization of ZBP1 that was not attributed to an increase in ZBP1 expression. Live cell imaging of single cells before and after perfusion of KCl revealed the rapid and directed efflux of ZBP1 granules from the cell body into dendrites in a proximo-distal gradient. High-speed imaging of enhanced green fluorescence protein-ZBP1 granules revealed rapid anterograde and retrograde movements in dendrites as well as dynamic movements in dendritic spines. A population of ZBP1 granules colocalized with beta-actin mRNA, and their spatial association in dendrites was increased by KCl depolarization. The NMDA receptor antagonist AP-5 impaired the dendritic localization of ZBP1 and beta-actin mRNA and inhibited the KCl-induced transport of ZBP1. The activity-dependent trafficking of ZBP1 and its dynamic movements within dendritic spines provide new evidence to implicate RNA binding proteins as regulators of mRNA transport to activated synapses in response to synaptic activity.
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Mohr E, Richter D. Molecular determinants and physiological relevance of extrasomatic RNA localization in neurons. Front Neuroendocrinol 2003; 24:128-39. [PMID: 12763001 DOI: 10.1016/s0091-3022(03)00011-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Specific sorting of mRNA molecules to subcellular microdomains is an evolutionarily conserved mechanism by which the polarized nature of eukayotic cells may be established and maintained. The molecular composition of the RNA localization machinery is complex. Sequence motifs within RNA molecules to be transported, called cis-acting elements, and proteins, referred to as trans-acting factors, are essential components. Transport of the resulting ribonucleoprotein complexes to distinct cytoplasmic regions occurs along the cytoskeletal network. The pathway is observed in organisms as diverse as yeast and human and it plays a critical role in development and cell differentiation. Moreover, RNA localization takes place in differentiated cell types including neurons. There is ample evidence to suggest that sorting of defined mRNA species to the neurites of nerve cells and on-site translation has an impact on various aspects of nerve cell biology.
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Affiliation(s)
- Evita Mohr
- Institute for Cell Biochemistry and Clinical Neurobiology, University Clinic Hamburg-Eppendorf, Martinistr 52, D-20246, Hamburg, Germany.
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Redistribution of syntaxin mRNA in neuronal cell bodies regulates protein expression and transport during synapse formation and long-term synaptic plasticity. J Neurosci 2003. [PMID: 12629184 DOI: 10.1523/jneurosci.23-05-01804.2003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Syntaxin has an important role in regulating vesicle docking and fusion essential for neurotransmitter release. Here, we demonstrate that the distribution of syntaxin mRNA in cell bodies of sensory neurons (SNs) of Aplysia maintained in cell culture is affected by synapse formation, synapse stabilization, and long-term facilitation (LTF) produced by 5-HT. The distribution of the mRNA in turn regulates expression and axonal transport of the protein. Syntaxin mRNA and protein accumulated at the axon hillock of SNs during the initial phase of synapse formation. Significant numbers of granules containing syntaxin were detected in the SN axon. When synaptic strength was stable, both mRNA and protein were targeted away from the axon hillock, and the number of syntaxin granules in the SN axon was reduced. Dramatic increases in mRNA and protein accumulation at the axon hillock and number of syntaxin granules in the SN axon were produced when cultures with stable connections were treated with 5-HT that evoked LTF. Anisomycin (protein synthesis inhibitor) or KT5720 (protein kinase A inhibitor) blocked LTF, accumulation of syntaxin mRNA and protein at the axon hillock, and the increase in syntaxin granules in SN axons. The results indicate that without significant effects on overall mRNA expression, both target interaction and 5-HT via activation of protein kinase A pathway regulate expression of syntaxin and its packaging for transport into axons by influencing the distribution of its mRNA in the SN cell body.
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Abstract
In neurons, the proteins derived from mRNAs localized in dendrites have been implicated in synaptic plasticity. The cytoplasmic polyadenylation element (CPE), a cis element in the 3'-UTRs of specific dendritic mRNAs, promotes cytoplasmic polyadenylation-induced translation in response to synaptic stimulation. Here, we demonstrate that the CPE and its binding protein CPEB facilitate mRNA transport to dendrites. In rat hippocampal neurons infected with recombinant viruses, the CPE is sufficient to direct a reporter RNA into dendrites. CPEB-GFP protein forms RNA-containing particles that are transported into dendrites in a microtubule-dependent fashion at an average velocity of 4-8 microm/min. Such particles also contain maskin, a CPEB-associated factor that mediates cap-dependent translational repression of CPE-containing mRNA, and the molecular motors dynein and kinesin. Overexpression of CPEB in neurons promotes the transport of CPE-containing endogenous MAP2 mRNA to dendrites, whereas overexpression of a mutant CPEB that is defective for interaction with molecular motors inhibits this transport. In neurons derived from CPEB knockout mice, the dendritic transport of a CPE-containing reporter RNA is reduced. These results suggest a mechanism whereby CPE-containing mRNAs can be transported to dendrites in a translationally dormant form, but activated at synapses in response to NMDA receptor stimulation.
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Affiliation(s)
- Yi-Shuian Huang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Mohr E, Kächele I, Mullin C, Richter D. Rat vasopressin mRNA: a model system to characterize cis-acting elements and trans-acting factors involved in dendritic mRNA sorting. PROGRESS IN BRAIN RESEARCH 2002; 139:211-24. [PMID: 12436937 DOI: 10.1016/s0079-6123(02)39018-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The genes encoding the vasopressin (VP) and oxytocin (OT) precursors are expressed in magnocellular neurons of the hypothalamo-neurohypophyseal system. The neuropeptides have a dual function: (1) they are secreted from the nerve terminals into the systemic circulation to act as hormones on various peripheral target organs; and (2) VP and OT are also released from the dendrites into the central nervous system where they presumably play a role as either neurotransmitters or as modulators of the classical transmitters. Substantial amounts of VP and OT mRNAs are sorted to both axons and dendrites. Since the latter are equipped with components of the translation machinery, the peptide hormone precursors are likely to be locally synthesized in dendrites of magnocellular neurons. Evidence for axonal precursor synthesis, on the other hand, has not been obtained. Subcellular mRNA localization is a complex pathway. It is determined by sequences (cis-acting elements) within the RNA and proteins (trans-acting factors) which interact with these elements in order to guide the molecules to their ultimate destination. We have investigated the mechanisms involved in mRNA targeting in neurons by using VP mRNA as a model system. Recombinant eukaryotic expression vectors harboring the VP cDNA have been microinjected into the cell nuclei of cultured superior cervical ganglion (SCG) neurons. The subcellular distribution of the vector-expressed mRNAs was determined by non-radioactive in situ hybridization techniques. This revealed transport of VP mRNA to the dendrites, but not to the axonal compartment of SCG neurons. A complex dendritic localizer sequence (DLS) that spans part of the coding region as well as the 3'-untranslated region was identified by microinjecting constructs encoding partial sequences of the VP mRNA. In order to characterize trans-acting factors interacting with this element, protein/RNA binding experiments with radiolabeled in vitro synthesized VP RNA probes and proteins extracted from rat brain have been carried out. A protein specifically interacts with the DLS of the VP mRNA but not with sequences that obviously lack a role in subcellular RNA transport. Biochemical purification revealed that this protein is the multifunctional poly(A)-binding protein (PABP). It is well known for its ability to bind with high affinity to poly(A) tails of mRNAs, prerequisite for mRNA stabilization and stimulation of translational initiation, respectively. With lower affinities, PABP can also associate with non-poly(A) sequences. The physiological consequences of these PABP/RNA interactions include functions such as translational silencing. The translational state of mRNAs subject to dendritic sorting is most likely influenced by external stimuli. Consequently, PABP could represent one of several components necessary to regulate local synthesis of the VP precursor and possibly of other proteins.
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Affiliation(s)
- Evita Mohr
- Universität Hamburg, Institut für Zellbiochemie und Klinische Neurobiologie, Martinistrasse 52, 20246 Hamburg, Germany.
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A receptor for activated C kinase is part of messenger ribonucleoprotein complexes associated with polyA-mRNAs in neurons. J Neurosci 2002. [PMID: 12388589 DOI: 10.1523/jneurosci.22-20-08827.2002] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Long-lasting changes in synaptic functions after an appropriate stimulus require altered protein expression at the synapse. To restrict changes in protein composition to activated synapses, proteins may be synthesized locally as a result of transmitter receptor-triggered signaling pathways. Second messenger-controlled mechanisms that affect mRNA translation are essentially unknown. Here we report that a receptor for activated C kinase, RACK1, is a component of messenger ribonucleoprotein (mRNP) complexes. RACK1 is predominantly associated with polysome-bound, polyA-mRNAs that are being actively translated. We find it to be present in a complex with beta-tubulin and at least two mRNA-binding proteins, polyA-binding protein 1 and a 130 kDa polyA-mRNA binding protein (KIAA0217). Activation of PKCbeta2 in vitro by phosphatidylserine/diacylglycerol or in hippocampal slices by metabotropic glutamate receptor stimulation increased the amount of RACK1/PKCbeta2 associated with polysome-bound polyA-mRNAs. In vitro, PKCbeta2 can phosphorylate a subset of polyA-mRNA-associated proteins that are also phosphorylated under in vivo conditions. On the basis of these findings plus the somatodendritic localization of RACK1, we hypothesize that metabotropic glutamate receptor-triggered binding of activated PKCbeta2 to mRNP complexes bound to polyA-mRNAs is involved in activity-triggered control of protein synthesis.
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Abstract
An EMBO-sponsored workshop entitled "Translational Control in Development and Neurobiology" was held recently in Mallorca, Spain. The talks covered mechanisms of translational regulation, particularly in terms of temporal and spatial regulation, over a wide range of biological systems.
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Affiliation(s)
- Robert B Darnell
- Howard Hughes Medical Institute, Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, NY 10021, USA.
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Rehbein M, Wege K, Buck F, Schweizer M, Richter D, Kindler S. Molecular characterization of MARTA1, a protein interacting with the dendritic targeting element of MAP2 mRNAs. J Neurochem 2002; 82:1039-46. [PMID: 12358751 DOI: 10.1046/j.1471-4159.2002.01058.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In neurones, the somatodendritic microtubule-associated protein 2 regulates the stability of the dendritic cytoskeleton. Its extrasomatic localization appears to be a multicausal mechanism that involves dendritic mRNA trafficking, a process that depends on a dendritic targeting element in the 3' untranslated region. Two rat MAP2-RNA trans-acting proteins, MARTA1 and MARTA2, exhibit specific high-affinity binding to the dendritic targeting element. We have now affinity-purified MARTA1 from rat brain. Analysis of proteolytic peptides revealed that rat MARTA1 is the orthologue of the human RNA-binding protein KSRP. Rat MARTA1 is a 74-kDa protein that contains four putative RNA-binding domains and is 98% identical to human KSRP. Both purified rat MARTA1 and human KSRP preferentially bind to the dendritic targeting element, but do not strongly interact with other investigated regions of mRNAs encoding microtubule-associated protein 2 and alpha-tubulin. In rat brain neurones and cultured neurones derived from superior cervical ganglia, MARTA1 is primarily intranuclear, but is also present in the somatodendritic cytoplasm. Thus, MARTA1 may play a role in nucleocytoplasmic mRNA targeting.
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Affiliation(s)
- Monika Rehbein
- Institute for Cell Biochemistry and Clinical Neurobiology, Centre for Molecular Neurobiology, University Hospital Eppendorf, University of Hamburg, Germany
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Duchaîne TF, Hemraj I, Furic L, Deitinghoff A, Kiebler MA, DesGroseillers L. Staufen2 isoforms localize to the somatodendritic domain of neurons and interact with different organelles. J Cell Sci 2002; 115:3285-95. [PMID: 12140260 DOI: 10.1242/jcs.115.16.3285] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mammalian Staufen2 (Stau2) is involved in mRNA transport in neurons. Here,we report that Stau2 is a double-stranded RNA-binding protein that is mainly expressed in the brain. We show that Stau2 is found in the somatodendritic compartment of neurons. In dendrites, Stau2 is aligned on individual tracts and colocalizes with microtubules. Stau2 is expressed as at least three splice isoforms, which can be observed in several subcellular complexes. Although a 62 kDa isoform (Stau262) fractionates in ribosome-free fractions of light density, Stau259 and Stau252 are found in high-density complexes. These complexes are resistant to EDTA and to non-ionic detergent. For the first time, we also provide evidence for an interaction of some Stau2 isoforms with ribosomes, thus pointing to an interesting new role for Stau2 in translation. EDTA treatment, which dissociates ribosome subunits,does not release Stau2 from the subunits, suggesting that Stau2-ribosome associations are not mediated mainly by mRNA intermediates. Although Stau2 has many features in common with its paralogue Stau1, it does not colocalize with Stau1-containing particles, indicating that these proteins are components of different complexes in dendrites. Our findings suggest that members of the Staufen family share evolutionarily conserved properties and highlight the complexity of Staufen-mediated RNA transport in neurons.
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Affiliation(s)
- Thomas F Duchaîne
- Department of Biochemistry, University of Montreal, Montreal, H3C 3J7, Canada
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