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Igreja C, Peter D, Weiler C, Izaurralde E. 4E-BPs require non-canonical 4E-binding motifs and a lateral surface of eIF4E to repress translation. Nat Commun 2014; 5:4790. [PMID: 25179781 PMCID: PMC4164784 DOI: 10.1038/ncomms5790] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 07/24/2014] [Indexed: 12/01/2022] Open
Abstract
eIF4E-binding proteins (4E-BPs) are a widespread class of translational regulators that share a canonical (C) eIF4E-binding motif (4E-BM) with eIF4G. Consequently, 4E-BPs compete with eIF4G for binding to the dorsal surface on eIF4E to inhibit translation initiation. Some 4E-BPs contain non-canonical 4E-BMs (NC 4E-BMs), but the contribution of these motifs to the repressive mechanism—and whether these motifs are present in all 4E-BPs—remains unknown. Here, we show that the three annotated Drosophila melanogaster 4E-BPs contain NC 4E-BMs. These motifs bind to a lateral surface on eIF4E that is not used by eIF4G. This distinct molecular recognition mode is exploited by 4E-BPs to dock onto eIF4E–eIF4G complexes and effectively displace eIF4G from the dorsal surface of eIF4E. Our data reveal a hitherto unrecognized role for the NC4E-BMs and the lateral surface of eIF4E in 4E-BP-mediated translational repression, and suggest that bipartite 4E-BP mimics might represent efficient therapeutic tools to dampen translation during oncogenic transformation. eIF4E-binding proteins (4E-BPs) are a conserved class of translational repressors that play essential roles in the regulation of protein expression. Here, Igreja et al. indentify non-canonical interactions between 4E-BPs and eIF4E that are required to effectively displace eIF4G and inhibit translation.
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Affiliation(s)
- Cátia Igreja
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Daniel Peter
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Catrin Weiler
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Elisa Izaurralde
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
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Paronetto MP, Messina V, Bianchi E, Barchi M, Vogel G, Moretti C, Palombi F, Stefanini M, Geremia R, Richard S, Sette C. Sam68 regulates translation of target mRNAs in male germ cells, necessary for mouse spermatogenesis. ACTA ACUST UNITED AC 2009; 185:235-49. [PMID: 19380878 PMCID: PMC2700383 DOI: 10.1083/jcb.200811138] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Sam68 is a KH-type RNA-binding protein involved in several steps of RNA metabolism with potential implications in cell differentiation and cancer. However, its physiological roles are still poorly understood. Herein, we show that Sam68(-/-) male mice are infertile and display several defects in spermatogenesis, demonstrating an essential role for Sam68 in male fertility. Sam68(-/-) mice produce few spermatozoa, which display dramatic motility defects and are unable to fertilize eggs. Expression of a subset of messenger mRNAs (mRNAs) is affected in the testis of knockout mice. Interestingly, Sam68 is associated with polyadenylated mRNAs in the cytoplasm during the meiotic divisions and in round spermatids, when it interacts with the translational machinery. We show that Sam68 is required for polysomal recruitment of specific mRNAs and for accumulation of the corresponding proteins in germ cells and in a heterologous system. These observations demonstrate a novel role for Sam68 in mRNA translation and highlight its essential requirement for the development of a functional male gamete.
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Affiliation(s)
- Maria Paola Paronetto
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome Tor Vergata, 00133 Rome, Italy
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Barbee SA, Estes PS, Cziko AM, Hillebrand J, Luedeman RA, Coller JM, Johnson N, Howlett IC, Geng C, Ueda R, Brand AH, Newbury SF, Wilhelm JE, Levine RB, Nakamura A, Parker R, Ramaswami M. Staufen- and FMRP-containing neuronal RNPs are structurally and functionally related to somatic P bodies. Neuron 2007; 52:997-1009. [PMID: 17178403 PMCID: PMC1955741 DOI: 10.1016/j.neuron.2006.10.028] [Citation(s) in RCA: 271] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 09/21/2006] [Accepted: 10/24/2006] [Indexed: 12/19/2022]
Abstract
Local control of mRNA translation modulates neuronal development, synaptic plasticity, and memory formation. A poorly understood aspect of this control is the role and composition of ribonucleoprotein (RNP) particles that mediate transport and translation of neuronal RNAs. Here, we show that staufen- and FMRP-containing RNPs in Drosophila neurons contain proteins also present in somatic "P bodies," including the RNA-degradative enzymes Dcp1p and Xrn1p/Pacman and crucial components of miRNA (argonaute), NMD (Upf1p), and general translational repression (Dhh1p/Me31B) pathways. Drosophila Me31B is shown to participate (1) with an FMRP-associated, P body protein (Scd6p/trailer hitch) in FMRP-driven, argonaute-dependent translational repression in developing eye imaginal discs; (2) in dendritic elaboration of larval sensory neurons; and (3) in bantam miRNA-mediated translational repression in wing imaginal discs. These results argue for a conserved mechanism of translational control critical to neuronal function and open up new experimental avenues for understanding the regulation of mRNA function within neurons.
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Affiliation(s)
- Scott A. Barbee
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
| | - Patricia S. Estes
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
| | - Anne-Marie Cziko
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
| | - Jens Hillebrand
- Smurfit Institute of Genetics and TCIN Lloyd Building, Trinity College Dublin, Dublin-2, Ireland
| | - Rene A. Luedeman
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
| | - Jeff M. Coller
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- Howard Hughes Medical Institute, University of Arizona Tucson, Arizona 85721
| | - Nick Johnson
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- Howard Hughes Medical Institute, University of Arizona Tucson, Arizona 85721
| | - Iris C. Howlett
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
| | - Cuiyun Geng
- Institute for Cellular and Molecular Biology Section of Molecular Cell and Developmental Biology, The University of Texas at Austin 1 University Station Austin, Texas 78712
| | - Ryu Ueda
- Invertebrate Genetics Lab, Genetic Strains Research Center, National Institute of Genetics (NIG) 1111 Yata Mishima, Shizuoka 411-8540, Japan
| | - Andrea H. Brand
- Wellcome/CRC Institute and Department of Genetics, University of Cambridge, Cambridge CB2 IQR, United Kingdom
| | - Sarah F. Newbury
- Institute of Cell and Molecular Biosciences, University of Newcastle, The Medical School Framlington Place, Newcastle-upon-Tyne, United Kingdom
| | - James E. Wilhelm
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego La Jolla, California 92093
| | - Richard B. Levine
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
| | - Akira Nakamura
- Laboratory for Germline Development, RIKEN Center for Developmental Biology, 2-2-3 Minatojimaminamimachi Chuo-ku, Kobe 650-0047 Japan
| | - Roy Parker
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- Howard Hughes Medical Institute, University of Arizona Tucson, Arizona 85721
- *Correspondence: (R.P.), . edu (M.R.)
| | - Mani Ramaswami
- Department of Molecular and Cellular Biology, University of Arizona Tucson, Arizona 85721
- ARL Division of Neurobiology, University of Arizona Tucson, Arizona 85721
- Smurfit Institute of Genetics and TCIN Lloyd Building, Trinity College Dublin, Dublin-2, Ireland
- *Correspondence: (R.P.), . edu (M.R.)
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