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Courgeon M, Desplan C. Coordination between stochastic and deterministic specification in the Drosophila visual system. Science 2019; 366:science.aay6727. [PMID: 31582524 DOI: 10.1126/science.aay6727] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 09/18/2019] [Indexed: 01/05/2023]
Abstract
Sensory systems use stochastic fate specification to increase their repertoire of neuronal types. How these stochastic decisions are coordinated with the development of their targets is unknown. In the Drosophila retina, two subtypes of ultraviolet-sensitive R7 photoreceptors are stochastically specified. In contrast, their targets in the brain are specified through a deterministic program. We identified subtypes of the main target of R7, the Dm8 neurons, each specific to the different subtypes of R7s. Dm8 subtypes are produced in excess by distinct neuronal progenitors, independently from R7. After matching with their cognate R7, supernumerary Dm8s are eliminated by apoptosis. Two interacting cell adhesion molecules, Dpr11 and DIPγ, are essential for the matching of one of the synaptic pairs. These mechanisms allow the qualitative and quantitative matching of R7 and Dm8 and thereby permit the stochastic choice made in R7 to propagate to the brain.
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Affiliation(s)
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA.
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Xu C, Theisen E, Maloney R, Peng J, Santiago I, Yapp C, Werkhoven Z, Rumbaut E, Shum B, Tarnogorska D, Borycz J, Tan L, Courgeon M, Griffin T, Levin R, Meinertzhagen IA, de Bivort B, Drugowitsch J, Pecot MY. Control of Synaptic Specificity by Establishing a Relative Preference for Synaptic Partners. Neuron 2019; 103:865-877.e7. [PMID: 31300277 PMCID: PMC6728174 DOI: 10.1016/j.neuron.2019.06.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 04/19/2019] [Accepted: 06/11/2019] [Indexed: 02/07/2023]
Abstract
The ability of neurons to identify correct synaptic partners is fundamental to the proper assembly and function of neural circuits. Relative to other steps in circuit formation such as axon guidance, our knowledge of how synaptic partner selection is regulated is severely limited. Drosophila Dpr and DIP immunoglobulin superfamily (IgSF) cell-surface proteins bind heterophilically and are expressed in a complementary manner between synaptic partners in the visual system. Here, we show that in the lamina, DIP mis-expression is sufficient to promote synapse formation with Dpr-expressing neurons and that disrupting DIP function results in ectopic synapse formation. These findings indicate that DIP proteins promote synapses to form between specific cell types and that in their absence, neurons synapse with alternative partners. We propose that neurons have the capacity to synapse with a broad range of cell types and that synaptic specificity is achieved by establishing a preference for specific partners.
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Affiliation(s)
- Chundi Xu
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA.
| | - Emma Theisen
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Ryan Maloney
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Jing Peng
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Ivan Santiago
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Clarence Yapp
- Image and Data Analysis Core, Harvard Medical School, Boston, MA 02115, USA
| | - Zachary Werkhoven
- Center for Brain Science and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Elijah Rumbaut
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Bryan Shum
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Dorota Tarnogorska
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Jolanta Borycz
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Liming Tan
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Maximilien Courgeon
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Tessa Griffin
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Raina Levin
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Benjamin de Bivort
- Center for Brain Science and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Jan Drugowitsch
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA
| | - Matthew Y Pecot
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave, Boston, MA 02115, USA.
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Sancer G, Kind E, Plazaola-Sasieta H, Balke J, Pham T, Hasan A, Münch LO, Courgeon M, Mathejczyk TF, Wernet MF. Modality-Specific Circuits for Skylight Orientation in the Fly Visual System. Curr Biol 2019; 29:2812-2825.e4. [DOI: 10.1016/j.cub.2019.07.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/02/2019] [Accepted: 07/09/2019] [Indexed: 01/17/2023]
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Courgeon M, He DQ, Liu HH, Legent K, Treisman JE. The Drosophila Epidermal Growth Factor Receptor does not act in the nucleus. J Cell Sci 2018; 131:jcs.220251. [PMID: 30158176 DOI: 10.1242/jcs.220251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/16/2018] [Indexed: 12/15/2022] Open
Abstract
Mammalian members of the ErbB family, including the epidermal growth factor receptor (EGFR), can regulate transcription, DNA replication and repair through nuclear entry of either the full-length proteins or their cleaved cytoplasmic domains. In cancer cells, these nuclear functions contribute to tumor progression and drug resistance. Here, we examined whether the single Drosophila EGFR can also localize to the nucleus. A chimeric EGFR protein fused at its cytoplasmic C-terminus to DNA-binding and transcriptional activation domains strongly activated transcriptional reporters when overexpressed in cultured cells or in vivo However, this activity was independent of cleavage and endocytosis. Without an exogenous activation domain, EGFR fused to a DNA-binding domain did not activate or repress transcription. Addition of the same DNA-binding and transcriptional activation domains to the endogenous Egfr locus through genome editing led to no detectable reporter expression in wild-type or oncogenic contexts. These results show that, when expressed at physiological levels, the cytoplasmic domain of the Drosophila EGFR does not have access to the nucleus. Therefore, nuclear EGFR functions are likely to have evolved after vertebrates and invertebrates diverged.
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Affiliation(s)
- Maximilien Courgeon
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Dan Qing He
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Hui Hua Liu
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Kevin Legent
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Jessica E Treisman
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA
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Karaz S, Courgeon M, Lepetit H, Bruno E, Pannone R, Tarallo A, Thouzé F, Kerner P, Vervoort M, Causeret F, Pierani A, D'Onofrio G. Neuronal fate specification by the Dbx1 transcription factor is linked to the evolutionary acquisition of a novel functional domain. EvoDevo 2016; 7:18. [PMID: 27525057 PMCID: PMC4983035 DOI: 10.1186/s13227-016-0055-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/27/2016] [Indexed: 12/18/2022] Open
Abstract
Background Dbx1 is a homeodomain transcription factor involved in neuronal fate specification belonging to a widely conserved family among bilaterians. In mammals, Dbx1 was proposed to act as a transcriptional repressor by interacting with the Groucho corepressors to allow the specification of neurons involved in essential biological functions such as locomotion or breathing. Results Sequence alignments of Dbx1 proteins from different species allowed us to identify two conserved domains related to the Groucho-dependent Engrailed repressor domain (RD), as well as a newly described domain composed of clusterized acidic residues at the C-terminus (Cter) which is present in tetrapods but also several invertebrates. Using a heterologous luciferase assay, we showed that the two putative repressor domains behave as such in a Groucho-dependent manner, whereas the Cter does not bear any intrinsic transcriptional activity. Consistently with in vitro data, we found that both RDs are involved in cell fate specification using in vivo electroporation experiments in the chick spinal cord. Surprisingly, we show that the Cter domain is required for Dbx1 function in vivo, acting as a modulator of its repressive activity and/or imparting specificity. Conclusion Our results strongly suggest that the presence of a Cter domain among tetrapods is essential for Dbx1 to regulate neuronal diversity and, in turn, nervous system complexity. Electronic supplementary material The online version of this article (doi:10.1186/s13227-016-0055-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sonia Karaz
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Maximilien Courgeon
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Hélène Lepetit
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Eugenia Bruno
- Dept. BEOM, Stazione Zoologica A. Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Raimondo Pannone
- Dept. BEOM, Stazione Zoologica A. Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Andrea Tarallo
- Dept. BEOM, Stazione Zoologica A. Dohrn, Villa Comunale, 80121 Naples, Italy
| | - France Thouzé
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Pierre Kerner
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Michel Vervoort
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Frédéric Causeret
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Alessandra Pierani
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
| | - Giuseppe D'Onofrio
- Dept. BEOM, Stazione Zoologica A. Dohrn, Villa Comunale, 80121 Naples, Italy
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Courgeon M, Konstantinides N, Desplan C. Cell competition: dying for communal interest. Curr Biol 2015; 25:R339-41. [PMID: 25898106 DOI: 10.1016/j.cub.2015.02.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Viable but slower growing cells are eliminated during embryonic development through the process of cell competition. Two new studies highlight a role for cell competition during adulthood as a surveillance mechanism that ensures tissue integrity during homeostasis, regeneration, and aging.
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Affiliation(s)
- Maximilien Courgeon
- Department of Biology, New York University, 1009 Silver Center, 100 Washington Square East, New York, NY 10003, USA
| | - Nikolaos Konstantinides
- Department of Biology, New York University, 1009 Silver Center, 100 Washington Square East, New York, NY 10003, USA
| | - Claude Desplan
- Department of Biology, New York University, 1009 Silver Center, 100 Washington Square East, New York, NY 10003, USA; Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi 129188, UAE.
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