Trébuchet, Guillaume; Cattenoz, Pierre B; Zsámboki, János; Mazaud, David; Siekhaus, Daria EIST Austria ; Fanto, Manolis; Giangrande, Angela
Despite their different origins, Drosophila glia and hemocytes are related cell populations that provide an immune function. Drosophila hemocytes patrol the body cavity and act as macrophages outside the nervous system whereas glia originate from the neuroepithelium and provide the scavenger population of the nervous system. Drosophila glia are hence the functional orthologs of vertebrate microglia, even though the latter are cells of immune origin that subsequently move into the brain during development. Interestingly, the Drosophila immune cells within (glia) and outside the nervous system (hemocytes) require the same transcription factor Glide/Gcm for their development. This raises the issue of how do glia specifically differentiate in the nervous system and hemocytes in the procephalic mesoderm. The Repo homeodomain transcription factor and pan-glial direct target of Glide/Gcm is known to ensure glial terminal differentiation. Here we show that Repo also takes center stage in the process that discriminates between glia and hemocytes. First, Repo expression is repressed in the hemocyte anlagen by mesoderm-specific factors. Second, Repo ectopic activation in the procephalic mesoderm is sufficient to repress the expression of hemocyte-specific genes. Third, the lack of Repo triggers the expression of hemocyte markers in glia. Thus, a complex network of tissue-specific cues biases the potential of Glide/Gcm. These data allow us to revise the concept of fate determinants and help us understand the bases of cell specification. Both sexes were analyzed.SIGNIFICANCE STATEMENTDistinct cell types often require the same pioneer transcription factor, raising the issue of how does one factor trigger different fates. In Drosophila, glia and hemocytes provide a scavenger activity within and outside the nervous system, respectively. While they both require the Glide/Gcm transcription factor, glia originate from the ectoderm, hemocytes from the mesoderm. Here we show that tissue-specific factors inhibit the gliogenic potential of Glide/Gcm in the mesoderm by repressing the expression of the homeodomain protein Repo, a major glial-specific target of Glide/Gcm. Repo expression in turn inhibits the expression of hemocyte-specific genes in the nervous system. These cell-specific networks secure the establishment of the glial fate only in the nervous system and allow cell diversification.
Journal of Neuroscience
This work was supported by INSERM, CNRS, UDS, Ligue Régionale contre le Cancer, Hôpital de Strasbourg, Association pour la Recherche sur le Cancer (ARC) and Agence Nationale de la Recherche (ANR) grants. P.B.C. was funded by the ANR and by the ARSEP (Fondation pour l'Aide à la Recherche sur la Sclérose en Plaques), and G.T. by governmental and ARC fellowships. This work was also supported by grants from the Ataxia UK (2491) and the NC3R (NC/L000199/1) awarded to M.F. The Institut de Génétique et de Biologie Moléculaire et Cellulaire was also supported by a French state fund through the ANR labex. D.E.S. was funded by Marie Curie Grant CIG 334077/IRTIM. We thank B. Altenhein, K. Brückner, M. Crozatier, L. Waltzer, M. Logan, E. Kurant, R. Reuter, E. Kurucz, J.L Dimarcq, J. Hoffmann, C. Goodman, the DHSB, and the BDSC for reagents and flies. We also thank all of the laboratory members for comments on the manuscript; C. Diebold, C. Delaporte, M. Pezze, the fly, and imaging and antibody facilities for technical assistance; and D. Dembele for help with statistics. In addition, we thank Alison Brewer for help with Luciferase assays.
Trébuchet G, Cattenoz PB, Zsámboki J, et al. The Repo homeodomain transcription factor suppresses hematopoiesis in Drosophila and preserves the glial fate. Journal of Neuroscience. 2019;39(2):238-255. doi:10.1523/JNEUROSCI.1059-18.2018
Trébuchet, G., Cattenoz, P. B., Zsámboki, J., Mazaud, D., Siekhaus, D. E., Fanto, M., & Giangrande, A. (2019). The Repo homeodomain transcription factor suppresses hematopoiesis in Drosophila and preserves the glial fate. Journal of Neuroscience. Society for Neuroscience. https://doi.org/10.1523/JNEUROSCI.1059-18.2018
Trébuchet, Guillaume, Pierre B Cattenoz, János Zsámboki, David Mazaud, Daria E Siekhaus, Manolis Fanto, and Angela Giangrande. “The Repo Homeodomain Transcription Factor Suppresses Hematopoiesis in Drosophila and Preserves the Glial Fate.” Journal of Neuroscience. Society for Neuroscience, 2019. https://doi.org/10.1523/JNEUROSCI.1059-18.2018.
G. Trébuchet et al., “The Repo homeodomain transcription factor suppresses hematopoiesis in Drosophila and preserves the glial fate,” Journal of Neuroscience, vol. 39, no. 2. Society for Neuroscience, pp. 238–255, 2019.
Trébuchet G, Cattenoz PB, Zsámboki J, Mazaud D, Siekhaus DE, Fanto M, Giangrande A. 2019. The Repo homeodomain transcription factor suppresses hematopoiesis in Drosophila and preserves the glial fate. Journal of Neuroscience. 39(2), 238–255.
Trébuchet, Guillaume, et al. “The Repo Homeodomain Transcription Factor Suppresses Hematopoiesis in Drosophila and Preserves the Glial Fate.” Journal of Neuroscience, vol. 39, no. 2, Society for Neuroscience, 2019, pp. 238–55, doi:10.1523/JNEUROSCI.1059-18.2018.
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