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eIF4B mRNA Translation Contributes to Cleavage Dynamics in Early Sea Urchin Embryos. BIOLOGY 2022; 11:biology11101408. [PMID: 36290313 PMCID: PMC9598784 DOI: 10.3390/biology11101408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 09/14/2022] [Accepted: 09/20/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary Cell division, also known as mitosis, relies on a complex cascade of molecular events that orchestrates the whole process and decides when cells can start dividing. A key factor in this process is protein synthesis, which is carefully regulated inside the cell to assure the timely production of all the proteins required for mitosis. The embryos of sea urchins divide rapidly after fertilization and represent an informative model to analyze the role of protein synthesis regulation during cell cycle progression. For example, the analysis in the 1980s of sea urchin embryos fostered the discovery of Cyclin B, the first representative of a family of proteins that plays a universal role in controlling cell division. This finding was awarded in 2001 with the Nobel Prize in Physiology and Medicine. However, much remains to be learned, and how protein synthesis controls the time and speed of mitosis in a developing embryo is still unclear. For instance, discovering whether the translation of other mRNAs than mitotic cyclins is required to finely regulate the rate of embryonic cleavage has never been tested. In this work, we investigated the role of the translation of an mRNA encoding a protein called eIF4B in the dynamics of embryonic cell division. We showed that newly synthesized eIF4B directly impacts cell division rates in two sea urchin species. Cell divisions are delayed when the production of eIF4B is inhibited in a fertilized egg. Conversely, increased production of eIF4B accelerates mitosis. Therefore, eIF4B mRNA translation represents a new means to regulate the pace of embryonic cleavages. Moreover, since eIF4B is a translational regulator, our findings suggest that the function of its mRNA translation is boosting the production of other proteins essential for mitosis. The cells of the sea urchin embryos seem thus equipped with a controlling device capable of modulating cell division rates, a molecular switch that could contribute to coordinating the first steps of development in other animals as well. Abstract During the first steps of sea urchin development, fertilization elicits a marked increase in protein synthesis essential for subsequent cell divisions. While the translation of mitotic cyclin mRNAs is crucial, we hypothesized that additional mRNAs must be translated to finely regulate the onset into mitosis. One of the maternal mRNAs recruited onto active polysomes at this stage codes for the initiation factor eIF4B. Here, we show that the sea urchin eIF4B orthologs present the four specific domains essential for eIF4B function and that Paracentrotus lividus eIF4B copurifies with eIF4E in a heterologous system. In addition, we investigated the role of eIF4B mRNA de novo translation during the two first embryonic divisions of two species, P. lividus and Sphaerechinus granularis. Our results show that injection of a morpholino directed against eIF4B mRNA results in a downregulation of translational activity and delays cell division in these two echinoids. Conversely, injection of an mRNA encoding for P. lividus eIF4B stimulates translation and significantly accelerates cleavage rates. Taken together, our findings suggest that eIF4B mRNA de novo translation participates in a conserved regulatory loop that contributes to orchestrating protein synthesis and modulates cell division rhythm during early sea urchin development.
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Translational Control of Canonical and Non-Canonical Translation Initiation Factors at the Sea Urchin Egg to Embryo Transition. Int J Mol Sci 2019; 20:ijms20030626. [PMID: 30717141 PMCID: PMC6387300 DOI: 10.3390/ijms20030626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/29/2019] [Accepted: 01/30/2019] [Indexed: 02/06/2023] Open
Abstract
Sea urchin early development is a powerful model to study translational regulation under physiological conditions. Fertilization triggers an activation of the translation machinery responsible for the increase of protein synthesis necessary for the completion of the first embryonic cell cycles. The cap-binding protein eIF4E, the helicase eIF4A and the large scaffolding protein eIF4G are assembled upon fertilization to form an initiation complex on mRNAs involved in cap-dependent translation initiation. The presence of these proteins in unfertilized and fertilized eggs has already been demonstrated, however data concerning the translational status of translation factors are still scarce. Using polysome fractionation, we analyzed the impact of fertilization on the recruitment of mRNAs encoding initiation factors. Strikingly, whereas the mRNAs coding eIF4E, eIF4A, and eIF4G were not recruited into polysomes at 1 h post-fertilization, mRNAs for eIF4B and for non-canonical initiation factors such as DAP5, eIF4E2, eIF4E3, or hnRNP Q, are recruited and are differentially sensitive to the activation state of the mechanistic target of rapamycin (mTOR) pathway. We discuss our results suggesting alternative translation initiation in the context of the early development of sea urchins.
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Moundoyi H, Demouy J, Le Panse S, Morales J, Sarels B, Cormier P. Toward Multiscale Modeling of Molecular and Biochemical Events Occurring at Fertilization Time in Sea Urchins. Results Probl Cell Differ 2018; 65:69-89. [DOI: 10.1007/978-3-319-92486-1_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
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Picard V, Mulner-Lorillon O, Bourdon J, Morales J, Cormier P, Siegel A, Bellé R. Model of the delayed translation of cyclin B maternal mRNA after sea urchin fertilization. Mol Reprod Dev 2016; 83:1070-1082. [PMID: 27699901 DOI: 10.1002/mrd.22746] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 10/01/2016] [Indexed: 01/24/2023]
Abstract
Sea urchin eggs exhibit a cap-dependent increase in protein synthesis within minutes after fertilization. This rise in protein synthesis occurs at a constant rate for a great number of proteins translated from the different available mRNAs. Surprisingly, we found that cyclin B, a major cell-cycle regulator, follows a synthesis pattern that is distinct from the global protein population, so we developed a mathematical model to analyze this dissimilarity in biosynthesis kinetic patterns. The model includes two pathways for cyclin B mRNA entry into the translational machinery: one from immediately available mRNA (mRNAcyclinB) and one from mRNA activated solely after fertilization (XXmRNAcyclinB). Two coefficients, α and β, were added to fit the measured scales of global protein and cyclin B synthesis, respectively. The model was simplified to identify the synthesis parameters and to allow its simulation. The calculated parameters for activation of the specific cyclin B synthesis pathway after fertilization included a kinetic constant (ka ) of 0.024 sec-1 , for the activation of XXmRNAcyclinB, and a critical time interval (t2 ) of 42 min. The proportion of XXmRNAcyclinB form was also calculated to be largely dominant over the mRNAcyclinB form. Regulation of cyclin B biosynthesis is an example of a select protein whose translation is controlled by pathways that are distinct from housekeeping proteins, even though both involve the same cap-dependent initiation pathway. Therefore, this model should help provide insight to the signaling utilized for the biosynthesis of cyclin B and other select proteins. Mol. Reprod. Dev. 83: 1070-1082, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vincent Picard
- CNRS UMR 6241, Laboratoire LINA, Université de Nantes, Nantes, France.,CNRS, IRISA-UMR 6074, Campus de Beaulieu, Rennes, France.,INRIA, Centre Rennes-Bretagne Atlantique, Symbiose, Campus de Beaulieu, Rennes, France
| | - Odile Mulner-Lorillon
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France.,CNRS, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France
| | - Jérémie Bourdon
- CNRS UMR 6241, Laboratoire LINA, Université de Nantes, Nantes, France
| | - Julia Morales
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France.,CNRS, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France
| | - Patrick Cormier
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France.,CNRS, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France
| | - Anne Siegel
- CNRS, IRISA-UMR 6074, Campus de Beaulieu, Rennes, France.,INRIA, Centre Rennes-Bretagne Atlantique, Symbiose, Campus de Beaulieu, Rennes, France
| | - Robert Bellé
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France.,CNRS, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, Roscoff Cedex, France
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Chassé H, Mulner-Lorillon O, Boulben S, Glippa V, Morales J, Cormier P. Cyclin B Translation Depends on mTOR Activity after Fertilization in Sea Urchin Embryos. PLoS One 2016; 11:e0150318. [PMID: 26962866 PMCID: PMC4786324 DOI: 10.1371/journal.pone.0150318] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/11/2016] [Indexed: 12/11/2022] Open
Abstract
The cyclin B/CDK1 complex is a key regulator of mitotic entry. Using PP242, a specific ATP-competitive inhibitor of mTOR kinase, we provide evidence that the mTOR signalling pathway controls cyclin B mRNA translation following fertilization in Sphaerechinus granularis and Paracentrotus lividus. We show that PP242 inhibits the degradation of the cap-dependent translation repressor 4E-BP (eukaryotic initiation factor 4E-Binding Protein). PP242 inhibits global protein synthesis, delays cyclin B accumulation, cyclin B/CDK1 complex activation and consequently entry into the mitotic phase of the cell cycle triggered by fertilization. PP242 inhibits cyclin B mRNA recruitment into active polysomes triggered by fertilization. An amount of cyclin B mRNA present in active polysomes appears to be insensitive to PP242 treatment. Taken together, our results suggest that, following sea urchin egg fertilization, cyclin B mRNA translation is controlled by two independent mechanisms: a PP242-sensitive and an additional PP242-insentitive mechanism.
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Affiliation(s)
- Héloïse Chassé
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
| | - Odile Mulner-Lorillon
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- * E-mail: (PC); (JM); (OML)
| | - Sandrine Boulben
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
| | - Virginie Glippa
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
| | - Julia Morales
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- * E-mail: (PC); (JM); (OML)
| | - Patrick Cormier
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Translation Cell Cycle and Development, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff cedex, France
- * E-mail: (PC); (JM); (OML)
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Affiliation(s)
- Thierry Tonon
- Sorbonne Université, UPMC Univ Paris 06, Centre National de la Recherche Scientifique, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff Roscoff, France
| | - Damien Eveillard
- LINA UMR 6241, Centre National de la Recherche Scientifique, EMN, Université de Nantes Nantes, France
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