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Jia JJ, Lahr RM, Solgaard MT, Moraes BJ, Pointet R, Yang AD, Celucci G, Graber TE, Hoang HD, Niklaus M, Pena IA, Hollensen AK, Smith EM, Chaker-Margot M, Anton L, Dajadian C, Livingstone M, Hearnden J, Wang XD, Yu Y, Maier T, Damgaard CK, Berman AJ, Alain T, Fonseca BD. mTORC1 promotes TOP mRNA translation through site-specific phosphorylation of LARP1. Nucleic Acids Res 2021; 49:3461-3489. [PMID: 33398329 PMCID: PMC8034618 DOI: 10.1093/nar/gkaa1239] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 11/29/2020] [Accepted: 12/15/2020] [Indexed: 02/06/2023] Open
Abstract
LARP1 is a key repressor of TOP mRNA translation. It binds the m7Gppp cap moiety and the adjacent 5'TOP motif of TOP mRNAs, thus impeding the assembly of the eIF4F complex on these transcripts. mTORC1 controls TOP mRNA translation via LARP1, but the details of the mechanism are unclear. Herein we elucidate the mechanism by which mTORC1 controls LARP1's translation repression activity. We demonstrate that mTORC1 phosphorylates LARP1 in vitro and in vivo, activities that are efficiently inhibited by rapamycin and torin1. We uncover 26 rapamycin-sensitive phospho-serine and -threonine residues on LARP1 that are distributed in 7 clusters. Our data show that phosphorylation of a cluster of residues located proximally to the m7Gppp cap-binding DM15 region is particularly sensitive to rapamycin and regulates both the RNA-binding and the translation inhibitory activities of LARP1. Our results unravel a new model of translation control in which the La module (LaMod) and DM15 region of LARP1, both of which can directly interact with TOP mRNA, are differentially regulated: the LaMod remains constitutively bound to PABP (irrespective of the activation status of mTORC1), while the C-terminal DM15 'pendular hook' engages the TOP mRNA 5'-end to repress translation, but only in conditions of mTORC1 inhibition.
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Affiliation(s)
- Jian-Jun Jia
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Roni M Lahr
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael T Solgaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Bruno J Moraes
- GABBA PhD Program, Abel Salazar Biomedical Sciences Institute, University of Porto, Porto, Portugal
- PrimerGen Ltd, Viseu, Portugal
| | - Roberta Pointet
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - An-Dao Yang
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Giovanna Celucci
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Tyson E Graber
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Huy-Dung Hoang
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Marius R Niklaus
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Izabella A Pena
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Anne K Hollensen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Ewan M Smith
- Cancer Research UK Beatson Institute, Glasgow, UK
| | | | - Leonie Anton
- Biozentrum, University of Basel, Basel, Switzerland
| | - Christopher Dajadian
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montréal, Canada
| | - Mark Livingstone
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montréal, Canada
| | - Jaclyn Hearnden
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montréal, Canada
| | - Xu-Dong Wang
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Yonghao Yu
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Timm Maier
- Biozentrum, University of Basel, Basel, Switzerland
| | - Christian K Damgaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Andrea J Berman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tommy Alain
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Bruno D Fonseca
- Children's Hospital of Eastern Ontario (CHEO) Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- PrimerGen Ltd, Viseu, Portugal
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