1
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Jung YL, Zhao W, Li I, Jain D, Epstein CB, Bernstein BE, Parangi S, Sherwood R, Robinson-Cohen C, Hsu YH, Park PJ, Mannstadt M. Epigenetic profiling reveals key genes and cis-regulatory networks specific to human parathyroids. Nat Commun 2024; 15:2106. [PMID: 38453887 PMCID: PMC10920874 DOI: 10.1038/s41467-024-46181-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 02/16/2024] [Indexed: 03/09/2024] Open
Abstract
In all terrestrial vertebrates, the parathyroid glands are critical regulators of calcium homeostasis and the sole source of parathyroid hormone (PTH). Hyperparathyroidism and hypoparathyroidism are clinically important disorders affecting multiple organs. However, our knowledge regarding regulatory mechanisms governing the parathyroids has remained limited. Here, we present the comprehensive maps of the chromatin landscape of the human parathyroid glands, identifying active regulatory elements and chromatin interactions. These data allow us to define regulatory circuits and previously unidentified genes that play crucial roles in parathyroid biology. We experimentally validate candidate parathyroid-specific enhancers and demonstrate their integration with GWAS SNPs for parathyroid-related diseases and traits. For instance, we observe reduced activity of a parathyroid-specific enhancer of the Calcium Sensing Receptor gene, which contains a risk allele associated with higher PTH levels compared to the wildtype allele. Our datasets provide a valuable resource for unraveling the mechanisms governing parathyroid gland regulation in health and disease.
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Affiliation(s)
- Youngsook Lucy Jung
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA.
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA.
| | - Wenping Zhao
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Ian Li
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Dhawal Jain
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | | | - Bradley E Bernstein
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Departments of Cell Biology and Pathology, Harvard Medical School, Boston, MA, USA
| | - Sareh Parangi
- Department of Surgery, Newton Wellesley Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Richard Sherwood
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Cambridge, MA, USA
| | - Cassianne Robinson-Cohen
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Yi-Hsiang Hsu
- Hinda and Arthur Marcus Institute for Aging Research, Hebrew Senior Life, Boston, MA, USA
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Peter J Park
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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2
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Ayoub M, David LM, Shklyar B, Hakim-Mishnaevski K, Kurant E. Drosophila FGFR/Htl signaling shapes embryonic glia to phagocytose apoptotic neurons. Cell Death Discov 2023; 9:90. [PMID: 36898998 PMCID: PMC10006210 DOI: 10.1038/s41420-023-01382-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 02/19/2023] [Accepted: 02/24/2023] [Indexed: 03/12/2023] Open
Abstract
Glial phagocytosis of apoptotic neurons is crucial for development and proper function of the central nervous system. Relying on transmembrane receptors located on their protrusions, phagocytic glia recognize and engulf apoptotic debris. Like vertebrate microglia, Drosophila phagocytic glial cells form an elaborate network in the developing brain to reach and remove apoptotic neurons. However, the mechanisms controlling creation of the branched morphology of these glial cells critical for their phagocytic ability remain unknown. Here, we demonstrate that during early embryogenesis, the Drosophila fibroblast growth factor receptor (FGFR) Heartless (Htl) and its ligand Pyramus are essential in glial cells for the formation of glial extensions, the presence of which strongly affects glial phagocytosis of apoptotic neurons during later stages of embryonic development. Reduction in Htl pathway activity results in shorter lengths and lower complexity of glial branches, thereby disrupting the glial network. Our work thus illuminates the important role Htl signaling plays in glial subcellular morphogenesis and in establishing glial phagocytic ability.
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Affiliation(s)
- Malak Ayoub
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Li-Mor David
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Boris Shklyar
- Bioimaging Unit, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Ketty Hakim-Mishnaevski
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Estee Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel.
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3
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Bazzi W, Cattenoz PB, Delaporte C, Dasari V, Sakr R, Yuasa Y, Giangrande A. Embryonic hematopoiesis modulates the inflammatory response and larval hematopoiesis in Drosophila. eLife 2018; 7:e34890. [PMID: 29992900 PMCID: PMC6040882 DOI: 10.7554/elife.34890] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 06/18/2018] [Indexed: 11/25/2022] Open
Abstract
Recent lineage tracing analyses have significantly improved our understanding of immune system development and highlighted the importance of the different hematopoietic waves. The current challenge is to understand whether these waves interact and whether this affects the function of the immune system. Here we report a molecular pathway regulating the immune response and involving the communication between embryonic and larval hematopoietic waves in Drosophila. Down-regulating the transcription factor Gcm specific to embryonic hematopoiesis enhances the larval phenotypes induced by over-expressing the pro-inflammatory Jak/Stat pathway or by wasp infestation. Gcm works by modulating the transduction of the Upd cytokines to the site of larval hematopoiesis and hence the response to chronic (Jak/Stat over-expression) and acute (wasp infestation) immune challenges. Thus, homeostatic interactions control the function of the immune system in physiology and pathology. Our data also indicate that a transiently expressed developmental pathway has a long-lasting effect on the immune response.
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Affiliation(s)
- Wael Bazzi
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
| | - Pierre B Cattenoz
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
| | - Claude Delaporte
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
| | - Vasanthi Dasari
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
| | - Rosy Sakr
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
| | - Yoshihiro Yuasa
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
| | - Angela Giangrande
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
- UMR7104Centre National de la Recherche ScientifiqueIllkirchFrance
- U1258Institut National de la Santé et de la Recherche MédicaleIllkirchFrance
- Université de StrasbourgIllkirchFrance
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4
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An evolutionary conserved interaction between the Gcm transcription factor and the SF1 nuclear receptor in the female reproductive system. Sci Rep 2016; 6:37792. [PMID: 27886257 PMCID: PMC5122895 DOI: 10.1038/srep37792] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/01/2016] [Indexed: 01/08/2023] Open
Abstract
NR5A1 is essential for the development and for the function of steroid producing glands of the reproductive system. Moreover, its misregulation is associated with endometriosis, which is the first cause of infertility in women. Hr39, the Drosophila ortholog of NR5A1, is expressed and required in the secretory cells of the spermatheca, the female exocrine gland that ensures fertility by secreting substances that attract and capacitate the spermatozoids. We here identify a direct regulator of Hr39 in the spermatheca: the Gcm transcription factor. Furthermore, lack of Gcm prevents the production of the secretory cells and leads to female sterility in Drosophila. Hr39 regulation by Gcm seems conserved in mammals and involves the modification of the DNA methylation profile of mNr5a1. This study identifies a new molecular pathway in female reproductive system development and suggests a role for hGCM in the progression of reproductive tract diseases in humans.
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5
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Functional Conservation of the Glide/Gcm Regulatory Network Controlling Glia, Hemocyte, and Tendon Cell Differentiation in Drosophila. Genetics 2015; 202:191-219. [PMID: 26567182 PMCID: PMC4701085 DOI: 10.1534/genetics.115.182154] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/03/2015] [Indexed: 12/21/2022] Open
Abstract
High-throughput screens allow us to understand how transcription factors trigger developmental processes, including cell specification. A major challenge is identification of their binding sites because feedback loops and homeostatic interactions may mask the direct impact of those factors in transcriptome analyses. Moreover, this approach dissects the downstream signaling cascades and facilitates identification of conserved transcriptional programs. Here we show the results and the validation of a DNA adenine methyltransferase identification (DamID) genome-wide screen that identifies the direct targets of Glide/Gcm, a potent transcription factor that controls glia, hemocyte, and tendon cell differentiation in Drosophila. The screen identifies many genes that had not been previously associated with Glide/Gcm and highlights three major signaling pathways interacting with Glide/Gcm: Notch, Hedgehog, and JAK/STAT, which all involve feedback loops. Furthermore, the screen identifies effector molecules that are necessary for cell-cell interactions during late developmental processes and/or in ontogeny. Typically, immunoglobulin (Ig) domain-containing proteins control cell adhesion and axonal navigation. This shows that early and transiently expressed fate determinants not only control other transcription factors that, in turn, implement a specific developmental program but also directly affect late developmental events and cell function. Finally, while the mammalian genome contains two orthologous Gcm genes, their function has been demonstrated in vertebrate-specific tissues, placenta, and parathyroid glands, begging questions on the evolutionary conservation of the Gcm cascade in higher organisms. Here we provide the first evidence for the conservation of Gcm direct targets in humans. In sum, this work uncovers novel aspects of cell specification and sets the basis for further understanding of the role of conserved Gcm gene regulatory cascades.
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6
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Altenhein B, Cattenoz PB, Giangrande A. The early life of a fly glial cell. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015. [DOI: 10.1002/wdev.200] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
| | | | - Angela Giangrande
- Department of Functional Genomics and Cancer; IGBMC; Illkirch France
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7
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Altenhein B. Glial cell progenitors in the Drosophila embryo. Glia 2015; 63:1291-302. [PMID: 25779863 DOI: 10.1002/glia.22820] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/02/2015] [Indexed: 12/31/2022]
Abstract
Development and general organization of the nervous system is comparable between insects and vertebrates. Our current knowledge on the formation of neurogenic anlagen and the generation of neural stem cells is deeply influenced by work done in invertebrate model organisms such as Drosophila and Caenorhabditis elegans. It is the aim of this review to summarize the most important steps in neurogenesis in the Drosophila embryo with a special emphasis on glial cell progenitors and the specification of glial cells. Induction of neurogenic regions during early embryogenesis and determination of neural stem cells are briefly described. Special attention is given to the formation of neural precursors called neuroblasts (NB) and their lineages. NBs divide in a stem cell mode to generate a cell clone of either neurons and/or glial cells. The latter require the activation of the transcription factor glial cells missing (gcm), thus providing a binary switch between neuronal and glial cell fates. Further aspects of glial cell specification and the resulting heterogeneity of the glial population in Drosophila are discussed.
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Affiliation(s)
- Benjamin Altenhein
- Department of Neurobiology, Neurodevelopment, Zoological Institute, University of Cologne, Cologne, Germany
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8
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Laneve P, Giangrande A. Enhanced Northern Blot detection of small RNA species in Drosophila melanogaster. J Vis Exp 2014. [PMID: 25177861 DOI: 10.3791/51814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The last decades have witnessed the explosion of scientific interest around gene expression control mechanisms at the RNA level. This branch of molecular biology has been greatly fueled by the discovery of noncoding RNAs as major players in post-transcriptional regulation. Such a revolutionary perspective has been accompanied and triggered by the development of powerful technologies for profiling short RNAs expression, both at the high-throughput level (genome-wide identification) or as single-candidate analysis (steady state accumulation of specific species). Although several state-of-art strategies are currently available for dosing or visualizing such fleeing molecules, Northern Blot assay remains the eligible approach in molecular biology for immediate and accurate evaluation of RNA expression. It represents a first step toward the application of more sophisticated, costly technologies and, in many cases, remains a preferential method to easily gain insights into RNA biology. Here we overview an efficient protocol (Enhanced Northern Blot) for detecting weakly expressed microRNAs (or other small regulatory RNA species) from Drosophila melanogaster whole embryos, manually dissected larval/adult tissues or in vitro cultured cells. A very limited amount of RNA is required and the use of material from flow cytometry-isolated cells can be also envisaged.
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Affiliation(s)
- Pietro Laneve
- Département de Génomique Fonctionnelle et Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire; Center for Life NanoScience, Istituto Italiano di Tecnologia
| | - Angela Giangrande
- Département de Génomique Fonctionnelle et Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire;
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9
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Interlocked loops trigger lineage specification and stable fates in the Drosophila nervous system. Nat Commun 2014; 5:4484. [DOI: 10.1038/ncomms5484] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 06/23/2014] [Indexed: 11/09/2022] Open
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10
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Jones BW. Characterization of missense alleles of the glial cells missing gene of Drosophila. Genesis 2014; 52:864-9. [PMID: 25044731 DOI: 10.1002/dvg.22801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 07/02/2014] [Accepted: 07/03/2014] [Indexed: 11/12/2022]
Abstract
Glial cells missing (Gcm) is the primary regulator of glial cell fate in Drosophila. Gcm belongs to a small family of transcriptional regulators involved in fundamental developmental processes found in diverse animal phyla including vertebrates. Gcm proteins contain the highly conserved DNA-binding GCM domain, which recognizes an octamer DNA sequence. To date, studies in Drosophila have primarily relied on gcm alleles caused by P-element induced DNA deletions at the gcm locus, as well as a null allele caused by a single base pair substitution in the GCM domain that completely abolishes DNA binding. Here I characterize two hypomorphic missense alleles of gcm with intermediate glial cells missing phenotypes. In embryos homozygous for either of these gcm alleles the number of glial cells in the central nervous cystem (CNS) is reduced approximately in half. Both alleles have single amino acid changes in the GCM domain. These results suggest that Gcm protein activities in these mutant alleles have been attenuated such that they are operating at threshold levels, and trigger glial cell differentiation in neural precursors in the CNS in a stochastic fashion. These hypomorphic alleles provide additional genetic resources for understanding Gcm functions and structure in Drosophila and other species.
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Affiliation(s)
- Bradley W Jones
- Department of Biology, The University of Mississippi, 122 Shoemaker Hall, University, Mississippi
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11
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Cattenoz PB, Giangrande A. Lineage specification in the fly nervous system and evolutionary implications. Cell Cycle 2013; 12:2753-9. [PMID: 23966161 DOI: 10.4161/cc.25918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Over the last decades, it has become clear that glia are multifunctional and plastic cells endowed with key regulatory roles. They control the response to developmental and/or pathological signals, thereby affecting neural proliferation, remodeling, survival, and regeneration. It is, therefore, important to understand the biology of these cells and the molecular mechanisms controlling their development/activity. The fly community has made major breakthroughs by characterizing the bases of gliogenesis and function. Here we describe the regulation and the role of the fly glial determinant. Then, we discuss the impact of the determinant in cell plasticity and differentiation. Finally, we address the conservation of this pathway across evolution.
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Affiliation(s)
- Pierre B Cattenoz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire; IGBMC/CNRS/INSERM/UDS; Strasbourg, France
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12
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Laneve P, Delaporte C, Trebuchet G, Komonyi O, Flici H, Popkova A, D'Agostino G, Taglini F, Kerekes I, Giangrande A. The Gcm/Glide molecular and cellular pathway: new actors and new lineages. Dev Biol 2012; 375:65-78. [PMID: 23276603 DOI: 10.1016/j.ydbio.2012.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/18/2012] [Accepted: 12/14/2012] [Indexed: 12/21/2022]
Abstract
In Drosophila, the transcription factor Gcm/Glide plays a key role in cell fate determination and cellular differentiation. In light of its crucial biological impact, major efforts have been put for analyzing its properties as master regulator, from both structural and functional points of view. However, the lack of efficient antibodies specific to the Gcm/Glide protein precluded thorough analyses of its regulation and activity in vivo. In order to relieve such restraints, we designed an epitope-tagging approach to "FLAG"-recognize and analyze the functional protein both in vitro (exogenous Gcm/Glide) and in vivo (endogenous protein). We here (i) reveal a tight interconnection between the small RNA and the Gcm/Glide pathways. AGO1 and miR-1 are Gcm/Glide targets whereas miR-279 negatively controls Gcm/Glide expression (ii) identify a novel cell population, peritracheal cells, expressing and requiring Gcm/Glide. Peritracheal cells are non-neuronal neurosecretory cells that are essential in ecdysis. In addition to emphasizing the importance of following the distribution and the activity of endogenous proteins in vivo, this study provides new insights and a novel frame to understand the Gcm/Glide biology.
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Affiliation(s)
- Pietro Laneve
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch 67404, France
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13
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Popkova A, Bernardoni R, Diebold C, Van de Bor V, Schuettengruber B, González I, Busturia A, Cavalli G, Giangrande A. Polycomb controls gliogenesis by regulating the transient expression of the Gcm/Glide fate determinant. PLoS Genet 2012; 8:e1003159. [PMID: 23300465 PMCID: PMC3531469 DOI: 10.1371/journal.pgen.1003159] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 10/26/2012] [Indexed: 11/19/2022] Open
Abstract
The Gcm/Glide transcription factor is transiently expressed and required in the Drosophila nervous system. Threshold Gcm/Glide levels control the glial versus neuronal fate choice, and its perdurance triggers excessive gliogenesis, showing that its tight and dynamic regulation ensures the proper balance between neurons and glia. Here, we present a genetic screen for potential gcm/glide interactors and identify genes encoding chromatin factors of the Trithorax and of the Polycomb groups. These proteins maintain the heritable epigenetic state, among others, of HOX genes throughout development, but their regulatory role on transiently expressed genes remains elusive. Here we show that Polycomb negatively affects Gcm/Glide autoregulation, a positive feedback loop that allows timely accumulation of Gcm/Glide threshold levels. Such temporal fine-tuning of gene expression tightly controls gliogenesis. This work performed at the levels of individual cells reveals an undescribed mode of Polycomb action in the modulation of transiently expressed fate determinants and hence in the acquisition of specific cell identity in the nervous system.
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Affiliation(s)
- Anna Popkova
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/UDS, Illkirch, France
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14
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Mao H, Lv Z, Ho MS. Gcm proteins function in the developing nervous system. Dev Biol 2012; 370:63-70. [PMID: 22842100 DOI: 10.1016/j.ydbio.2012.07.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 07/02/2012] [Accepted: 07/10/2012] [Indexed: 11/17/2022]
Abstract
A fundamental issue during nervous system development is how individual cells are formed from the undefined precursors. Differentiated neurons and glia, two major cell types mediating neuronal function, are acquired from immature precursors via a series of explicit controls exerted by transcription factors such as proteins in the family of Glial cells missing (Gcm). In mammals, Gcm proteins are involved in placenta and parathyroid gland development, whereas in the invertebrate organism Drosophila, Gcm proteins act as fate determinants for glial cell fate, regulate neural stem cell (NSC) induction and conversion, and promote glial proliferation. In particular, Gcm protein levels are carefully tuned for Drosophila gliogenesis and their stability is under precise control via the ubiquitin-proteasome system (UPS). Here we summarize recent advances on Gcm proteins function. In addition to describe various features of Gcm protein family, the significance of their functions in the developing nervous system is also discussed.
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Affiliation(s)
- Haian Mao
- Department of Nuclear Medicine, Shanghai Tenth Hospital, Tongji University, Shanghai 200072, China
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15
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Flici H, Giangrande A. Stem cell aging and plasticity in the Drosophila nervous system. Fly (Austin) 2012; 6:108-12. [PMID: 22634501 DOI: 10.4161/fly.19797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The majority of neural stem cells (NSCs) are considered as very plastic precursors that, in vitro, can divide indefinitely or differentiate into neurons or glia under specific conditions. However, in vivo, these cells actively proliferate during development, and later enter quiescence or apoptosis. This raises the issue as to whether stem cells keep their plastic behavior throughout their life, which may impact their therapeutic potential in regenerative medicine. Using the Gcm/Glide (for Glial cell missing/Glial cell deficient) transcription factor, which is able to trigger a complete and stable fate conversion into glia when ectopically expressed, we recently reported that the plasticity of Drosophila NSCs, commonly called neuroblasts (NBs), is age-dependent. When challenged with Gcm/Glide, newborn NBs are more easily converted into glia than old ones. Furthermore, the few old NBs that can be converted frequently generate cells with a stable (NB/glia) intermediate identity, a phenotype characteristic of cancer cells. We here discuss the concept of aging in NSC fate conversion and speculate on how our findings impact the ongoing debate concerning NSC plasticity.
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Affiliation(s)
- Hakima Flici
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/UDS, Illkirch, France
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16
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Flici H, Erkosar B, Komonyi O, Karatas OF, Laneve P, Giangrande A. Gcm/Glide-dependent conversion into glia depends on neural stem cell age, but not on division, triggering a chromatin signature that is conserved in vertebrate glia. Development 2011; 138:4167-78. [PMID: 21852399 DOI: 10.1242/dev.070391] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Neurons and glia differentiate from multipotent precursors called neural stem cells (NSCs), upon the activation of specific transcription factors. In vitro, it has been shown that NSCs display very plastic features; however, one of the major challenges is to understand the bases of lineage restriction and NSC plasticity in vivo, at the cellular level. We show here that overexpression of the Gcm transcription factor, which controls the glial versus neuronal fate choice, fully and efficiently converts Drosophila NSCs towards the glial fate via an intermediate state. Gcm acts in a dose-dependent and autonomous manner by concomitantly repressing the endogenous program and inducing the glial program in the NSC. Most NSCs divide several times to build the embryonic nervous system and eventually enter quiescence: strikingly, the gliogenic potential of Gcm decreases with time and quiescent NSCs are resistant to fate conversion. Together with the fact that Gcm is able to convert mutant NSCs that cannot divide, this indicates that plasticity depends on temporal cues rather than on the mitotic potential. Finally, NSC plasticity involves specific chromatin modifications. The endogenous glial cells, as well as those induced by Gcm overexpression display low levels of histone 3 lysine 9 acetylation (H3K9ac) and Drosophila CREB-binding protein (dCBP) Histone Acetyl-Transferase (HAT). Moreover, we show that dCBP targets the H3K9 residue and that high levels of dCBP HAT disrupt gliogenesis. Thus, glial differentiation needs low levels of histone acetylation, a feature shared by vertebrate glia, calling for an epigenetic pathway conserved in evolution.
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Affiliation(s)
- Hakima Flici
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, IGBMC/CNRS/INSERM/UDS, BP 10142, 67404 ILLKIRCH, CU de Strasbourg, France
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17
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Abstract
Glial cells missing-2 (Gcm2) is the key regulating transcription factor for parathyroid gland development. The continued expression of high levels of Gcm2 in mature parathyroid glands suggests that it is required for maintenance of parathyroid cell differentiation. The role of Gcm2 in parathyroid cell physiology, however, has not been fully studied. In this study, we examined the effects of Gcm2 silencing on cultured human parathyroid cells. Collagenase-dispersed human parathyroid cells from patients with chronic kidney disease were placed in monolayer cultures and infected with lentivirus expressing shRNA for human Gcm2. Seventy-two hours after infection, mRNA was processed and analyzed for Gcm2, PTH, vitamin D receptor (VDR), calcium-sensing receptor (CaR), 25-hydroxyvitamin D(3) 1-alpha-hydroxylase (1-OHase), and proliferating cell nuclear antigen (PCNA) by real-time PCR (qPCR). Protein expression of affected genes was analyzed by immunoblot 72 h after infection. Gcm2 mRNA and protein were decreased by 74.2 +/- 12.2% (SD; n = 3 experiments; p < 0.01) and 67.5 +/- 15.7% (n = 2; p < 0.01), respectively. CaR mRNA and protein were reduced by 47.8 +/- 21.1% (n = 3; p < 0.01) and 48.1 +/- 4.3% (n = 3; p < 0.01), respectively. However, VDR, PTH, 1-OHase, and PCNA were not significantly affected by Gcm2 silencing. Further analysis of CaR mRNA indicated that transcripts containing exon 1B, derived by transcription from CaR promoter 2, were downregulated (58.8 +/- 19.27%; n = 3; p < 0.05) by Gcm2 silencing. Exon 1A-containing transcripts from promoter 1 were expressed at very low levels in the cultures. These results indicate that one function of Gcm2 is to maintain high levels of CaR expression in parathyroid cells.
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Schubert SW, Lamoureux N, Kilian K, Klein-Hitpass L, Hashemolhosseini S. Identification of Integrin-α4, Rb1, and Syncytin A as Murine Placental Target Genes of the Transcription Factor GCMa/Gcm1. J Biol Chem 2008; 283:5460-5. [DOI: 10.1074/jbc.m710110200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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19
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Beckervordersandforth RM, Rickert C, Altenhein B, Technau GM. Subtypes of glial cells in the Drosophila embryonic ventral nerve cord as related to lineage and gene expression. Mech Dev 2008; 125:542-57. [PMID: 18296030 DOI: 10.1016/j.mod.2007.12.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 10/22/2022]
Abstract
In the Drosophila embryonic CNS several subtypes of glial cells develop, which arrange themselves at characteristic positions and presumably fulfil specific functions. The mechanisms leading to the specification and differentiation of glial subtypes are largely unknown. By DiI labelling in glia-specific Gal4 lines we have clarified the lineages of the lateral glia in the embryonic ventral nerve cord and linked each glial cell to a specific stem cell. For the lineage of the longitudinal glioblast we show that it consists of 9 cells, which acquire at least four different identities. A large collection of molecular markers (many of them representing transcription factors and potential Gcm target genes) reveals that individual glial cells express specific combinations of markers. However, cluster analysis uncovers similar combinatorial codes for cells within, and significant differences between the categories of surface-associated, cortex-associated, and longitudinal glia. Glial cells derived from the same stem cell may be homogeneous (though not identical; stem cells NB1-1, NB5-6, NB6-4, LGB) or heterogeneous (NB7-4, NB1-3) with regard to gene expression. In addition to providing a powerful tool to analyse the fate of individual glial cells in different genetic backgrounds, each of these marker genes represents a candidate factor involved in glial specification or differentiation. We demonstrate this by the analysis of a castor loss of function mutation, which affects the number and migration of specific glial cells.
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20
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Soustelle L, Giangrande A. Novel gcm-dependent lineages in the postembryonic nervous system of Drosophila melanogaster. Dev Dyn 2007; 236:2101-8. [PMID: 17654713 DOI: 10.1002/dvdy.21232] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
glial cells missing genes (gcm and gcm2) act as the glial fate determinants in the Drosophila embryo. However, their requirement in the adult central nervous system (CNS) is at present not known, except for their role in lamina glia. This is particularly important with respect to two recent sets of data. Adult glial subpopulations differentiate through embryonic glia proliferation. Also, gcm-gcm2 are required for the differentiation of specific adult neurons. We here show that gcm is expressed in precursors and postmitotic, migrating, cells of the medulla neuropile glia (mng) lineage. It is also expressed in a thoracic glial lineage and in neurons of the ventral nerve cord (VNC). Finally, while gcm is required for gliogenesis in medulla and VNC, it does not seem to be required for the generation of VNC neurons.
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Affiliation(s)
- Laurent Soustelle
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Strasbourg, France
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21
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Altenhein B, Becker A, Busold C, Beckmann B, Hoheisel JD, Technau GM. Expression profiling of glial genes during Drosophila embryogenesis. Dev Biol 2006; 296:545-60. [PMID: 16762338 DOI: 10.1016/j.ydbio.2006.04.460] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 04/19/2006] [Accepted: 04/21/2006] [Indexed: 11/22/2022]
Abstract
In the central nervous system of Drosophila, the induction of the glial cell fate is dependent on the transcription factor glial cells missing (gcm). Though a considerable number of other genes have been shown to be expressed in all or in subsets of glial cells, the course of glial cell differentiation and subtype specification is only poorly understood. This prompted us to design a whole genome microarray approach comparing gcm gain-of-function and, for the first time, gcm loss-of-function genetics to wildtype in time course experiments along embryogenesis. The microarray data were analyzed with special emphasis on the temporal profile of differential regulation. A comparison of both experiments enabled us to identify more than 300 potential gcm target genes. Validation by in situ hybridization revealed expression in glial cells, macrophages, and tendon cells (all three cell types depend on gcm) for 70 genes, of which more than 50 had been unknown to be under gcm control. Eighteen genes are exclusively expressed in glial cells, and their dependence on gcm was confirmed in situ. Initial considerations regarding the role of the newly discovered glial genes are discussed based on gene ontology and the temporal profile and subtype specificity of their expression. This collection of glial genes provides an important basis for the clarification of the genetic network controlling various aspects of glial development and function.
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22
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Chuang HC, Chang CW, Chang GD, Yao TP, Chen H. Histone deacetylase 3 binds to and regulates the GCMa transcription factor. Nucleic Acids Res 2006; 34:1459-69. [PMID: 16528103 PMCID: PMC1401512 DOI: 10.1093/nar/gkl048] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Human GCMa transcription factor regulates expression of syncytin, a placental fusogenic protein mediating trophoblastic fusion. Recently, we have demonstrated that CBP-mediated GCMa acetylation underlies the activated cAMP/PKA signaling pathway that stimulates trophoblastic fusion. Because protein acetylation is a reversible modification governed by histone acetyltransferases (HATs) and histone deacetylase (HDACs), in this study we investigated the key HDACs responsible for deacetylation of GCMa and thus the reduction in GCMa activity to avoid unwanted fusion events that may have adverse effects on placental morphogenesis. We herein demonstrate that the HDAC inhibitor, trichostatin A (TSA), increases the level of acetylated GCMa and that HDAC1, 3, 4 and 5 interact with and deacetylate GCMa. Glutathione S-transferase (GST) pull-down assays further verified direct interaction between GCMa and HDAC3 or CBP and HDAC3. HDAC3 counteracts the transcriptional coactivator activity of CBP and the enhancement effect of CBP on GCMa-mediated transcriptional activation. Correlatively, we found in placental cells that HDAC3 associates with the proximal GCMa-binding site (pGBS) in the syncytin promoter and dissociates from pGBS in the presence of forskolin, which stimulates the association of CBP and GCMa with pGBS. Our studies support that trophoblastic fusion in placental morphogenesis depends on the regulation of GCMa activity by HAT and HDAC.
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Affiliation(s)
- Hsiao-Ching Chuang
- Graduate Institute of Biochemical Sciences, National Taiwan UniversityTaipei 106, Taiwan
| | - Ching-Wen Chang
- Institute of Biological Chemistry, Academia SinicaNankang, Taipei 115, Taiwan
| | - Geen-Dong Chang
- Graduate Institute of Biochemical Sciences, National Taiwan UniversityTaipei 106, Taiwan
| | - Tso-Pang Yao
- Department of Pharmacology and Cancer Biology, Duke UniversityDurham, NC 277103, USA
| | - Hungwen Chen
- Graduate Institute of Biochemical Sciences, National Taiwan UniversityTaipei 106, Taiwan
- Institute of Biological Chemistry, Academia SinicaNankang, Taipei 115, Taiwan
- To whom correspondence should be addressed. Tel: +011 886 2 27855696, ext. 6090; Fax: +011 886 2 27889759;
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Mondal S, Ivanchuk SM, Rutka JT, Boulianne GL. Sloppy paired 1/2 regulate glial cell fates by inhibiting Gcm Function. Glia 2006; 55:282-93. [PMID: 17091489 DOI: 10.1002/glia.20456] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Organization of the central nervous system during embryonic development is an intricate process involving a host of molecular players. The Drosophila segmentation genes, sloppy paired (slp) 1/2 have been shown to be necessary for development of a neuronal precursor cell subtype, the NB4-2 cells. Here, we show that slp1/2 also have roles in regulating glial cell fates. Using slp1/2 loss-of-function mutants, we show an increase in glial cell markers, glial cells missing (gcm) and reversed polarity. In contrast, misexpression of either slp1 or slp2 causes downregulation of glial cell-specific genes and alters the fate of glial and neuronal cells. Furthermore, we demonstrate that Slp1 and its mammalian ortholog, Foxg1, inhibit Gcm transcriptional activity as well as bind Gcm. Taken together, these data show that Slp1/Foxg1 regulate glial cell fates by inhibiting Gcm function.
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Affiliation(s)
- Soma Mondal
- The Arthur and Sonia Labatt Brain Tumour Research Center, Hospital for Sick Children, Toronto, Ontario, Canada
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24
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De Iaco R, Soustelle L, Kammerer M, Sorrentino S, Jacques C, Giangrande A. Huckebein-mediated autoregulation of Glide/Gcm triggers glia specification. EMBO J 2005; 25:244-54. [PMID: 16362045 PMCID: PMC1356350 DOI: 10.1038/sj.emboj.7600907] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Accepted: 11/16/2005] [Indexed: 11/09/2022] Open
Abstract
Cell specification in the nervous system requires patterning genes dictating spatio-temporal coordinates as well as fate determinants. In the case of neurons, which are controlled by the family of proneural transcription factors, binding specificity and patterned expression trigger both differentiation and specification. In contrast, a single gene, glide cell deficient/glial cell missing (glide/gcm), is sufficient for all fly lateral glial differentiation. How can different types of cells develop in the presence of a single fate determinant, that is, how do differentiation and specification pathways integrate and produce distinct glial populations is not known. By following an identified lineage, we here show that glia specification is triggered by high glide/gcm expression levels, mediated by cell-specific protein-protein interactions. Huckebein (Hkb), a lineage-specific factor, provides a molecular link between glide/gcm and positional cues. Importantly, Hkb does not activate transcription; rather, it physically interacts with Glide/Gcm thereby triggering its autoregulation. These data emphasize the importance of fate determinant cell-specific quantitative regulation in the establishment of cell diversity.
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Affiliation(s)
- Rossana De Iaco
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch Cedex, CU de Strasbourg, France
| | - Laurent Soustelle
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch Cedex, CU de Strasbourg, France
| | - Martial Kammerer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch Cedex, CU de Strasbourg, France
| | - Sandro Sorrentino
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch Cedex, CU de Strasbourg, France
| | - Cécile Jacques
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch Cedex, CU de Strasbourg, France
| | - Angela Giangrande
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch Cedex, CU de Strasbourg, France
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 10142, 67404 Illkirch Cedex, CU de Strasbourg, France. Tel.: +33 3 88 65 33 81; Fax: +33 3 88 65 32 01; E-mail:
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25
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Jones BW. Transcriptional control of glial cell development in Drosophila. Dev Biol 2005; 278:265-73. [PMID: 15680348 DOI: 10.1016/j.ydbio.2004.11.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Revised: 11/15/2004] [Accepted: 11/16/2004] [Indexed: 10/26/2022]
Abstract
Neurons and glia are generated from multipotent neural progenitors. In Drosophila, the transcriptional regulation of glial vs. neuronal fates is controlled by the expression of the transcription factor encoded by the glial cells missing gene (gcm) in multiple neural lineages. The cis-regulatory control of gcm transcription serves as a nodal point to translate a complex array of spatially and temporally regulated transcription factors in distinct neural lineages into glial-specific expression. Gcm acts synergistically with several downstream transcription factors to initiate and maintain glial-specific gene expression. The identification of a large set of glial-specific genes through the application of computational and whole genome tools provides the opportunity to analyze the transcriptional regulation of glial cell development at the genomic level in a relatively simple genetic model system.
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Affiliation(s)
- Bradley W Jones
- Department of Biology, The University of Mississippi, 122 Shoemaker Hall, University, MS 38677, USA.
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26
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Soustelle L, Jacques C, Altenhein B, Technau GM, Volk T, Giangrande A. Terminal tendon cell differentiation requires the glide/gcm complex. Development 2004; 131:4521-32. [PMID: 15342477 DOI: 10.1242/dev.01290] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Locomotion relies on stable attachment of muscle fibres to their target sites, a process that allows for muscle contraction to generate movement. Here, we show that glide/gcm and glide2/gcm2, the fly glial cell determinants, are expressed in a subpopulation of embryonic tendon cells and required for their terminal differentiation. By using loss-of-function approaches, we show that in the absence of both genes, muscle attachment to tendon cells is altered, even though the molecular cascade induced by stripe, the tendon cell determinant, is normal. Moreover, we show that glide/gcm activates a new tendon cell gene independently of stripe. Finally, we show that segment polarity genes control the epidermal expression of glide/gcm and determine, within the segment,whether it induces glial or tendon cell-specific markers. Thus, under the control of positional cues, glide/gcm triggers a new molecular pathway involved in terminal tendon cell differentiation, which allows the establishment of functional muscle attachment sites and locomotion.
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Affiliation(s)
- Laurent Soustelle
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 10142, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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27
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Jones BW, Abeysekera M, Galinska J, Jolicoeur EM. Transcriptional control of glial and blood cell development in Drosophila: cis-regulatory elements of glial cells missing. Dev Biol 2004; 266:374-87. [PMID: 14738884 DOI: 10.1016/j.ydbio.2003.10.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In Drosophila, glial cell differentiation requires the expression of glial cells missing (gcm) in multiple neural cell lineages, where gcm acts as a binary switch for glial vs. neuronal fate. Thus, the primary event controlling gliogenesis in neural progenitors is the transcription of gcm. In addition, gcm is also required for the differentiation of macrophages, and is expressed in the hemocyte lineage. This dual role of gcm in glial cell and blood cell development underscores the need for the precise temporal and spatial regulation of gcm transcription. To understand how gcm transcription is regulated, we have undertaken an analysis of the cis-regulatory DNA elements of gcm using lacZ reporter activity in transgenic embryos, testing the activity of approximately 35 kilobases of DNA from the gcm locus. We have identified several distinct DNA regions that promote most of the elements of gcm expression. These include elements for general neural expression, gcm-independent and gcm-dependent glial-specific expression, as well as early and late hemocyte expression. We show that expression of an abdominal glial-specific element is dependent on the homeotic gene abdominal-A. Our results indicate that gcm transcription is controlled by a combination of general and lineage-specific elements, positive autoregulation, and neuronal repression.
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Affiliation(s)
- Bradley W Jones
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, and Department of Pharmacology, New York University School of Medicine, New York, NY 10016, USA.
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28
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Cohen SX, Moulin M, Hashemolhosseini S, Kilian K, Wegner M, Müller CW. Structure of the GCM domain-DNA complex: a DNA-binding domain with a novel fold and mode of target site recognition. EMBO J 2003; 22:1835-45. [PMID: 12682016 PMCID: PMC154474 DOI: 10.1093/emboj/cdg182] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glia cell missing (GCM) transcription factors form a small family of transcriptional regulators in metazoans. The prototypical Drosophila GCM protein directs the differentiation of neuron precursor cells into glia cells, whereas mammalian GCM proteins are involved in placenta and parathyroid development. GCM proteins share a highly conserved 150 amino acid residue region responsible for DNA binding, known as the GCM domain. Here we present the crystal structure of the GCM domain from murine GCMa bound to its octameric DNA target site at 2.85 A resolution. The GCM domain exhibits a novel fold consisting of two domains tethered together by one of two structural Zn ions. We observe the novel use of a beta-sheet in DNA recognition, whereby a five- stranded beta-sheet protrudes into the major groove perpendicular to the DNA axis. The structure combined with mutational analysis of the target site and of DNA-contacting residues provides insight into DNA recognition by this new type of Zn-containing DNA-binding domain.
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Affiliation(s)
- Serge X Cohen
- European Molecular Biology Laboratory, Grenoble Outstation, BP 181, 38042 Grenoble Cedex 9, France
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29
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Ragone G, Van De Bor V, Sorrentino S, Kammerer M, Galy A, Schenck A, Bernardoni R, Miller AA, Roy N, Giangrande A. Transcriptional regulation of glial cell specification. Dev Biol 2003; 255:138-50. [PMID: 12618139 DOI: 10.1016/s0012-1606(02)00081-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Neuronal differentiation relies on proneural factors that also integrate positional information and contribute to the specification of the neuronal type. The molecular pathway triggering glial specification is not understood yet. In Drosophila, all lateral glial precursors and glial-promoting activity have been identified, which provides us with a unique opportunity to dissect the regulatory pathways controlling glial differentiation and specification. Although glial lineages are very heterogeneous with respect to position, time of differentiation, and lineage tree, they all express and require two homologous genes, glial cell deficient/glial cell missing (glide/gcm) and glide2, that act in concert, with glide/gcm constituting the major glial-promoting factor. Here, we show that glial specification resides in glide/gcm transcriptional regulation. The glide/gcm promoter contains lineage-specific elements as well as quantitative and turmoil elements scattered throughout several kilobases. Interestingly, there is no correlation between a specific regulatory element and the type of glial lineage. Thus, the glial-promoting factor acts as a naive switch-on button that triggers gliogenesis in response to multiple pathways converging onto its promoter. Both negative and positive regulation are required to control glide/gcm expression, indicating that gliogenesis is actively repressed in some neural lineages.
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Affiliation(s)
- Gianluca Ragone
- Institut de Génétique et Biologie Moléculaire et Cellulaire, IGBMC/CNRS/ULP/INSERM - BP 10142 67404 Illkirch, c.u., de Strasbourg, France
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30
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Yu C, Shen K, Lin M, Chen P, Lin C, Chang GD, Chen H. GCMa regulates the syncytin-mediated trophoblastic fusion. J Biol Chem 2002; 277:50062-8. [PMID: 12397062 DOI: 10.1074/jbc.m209316200] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human placental trophoblast cell can be classified as either a cytotrophoblast or a syncytiotrophoblast. Cytotrophoblasts can function as stem cells for the development of the syncytiotrophoblast layer via cell fusion. An envelope gene of the human endogenous retrovirus family W (HERV-W) called syncytin is specifically expressed in the syncytiotrophoblast layer. Syncytin is a fusogenic membrane protein; therefore, it can mediate the fusion of cytotrophoblasts into the syncytiotrophoblast layer, which is essential for pregnancy maintenance. GCMa is a placenta-specific transcription factor and is required for placental development. To study the placenta-specific fusion mediated by syncytin, we tested whether GCMa is involved in this process by regulating syncytin gene expression. In this report, we demonstrate that GCMa was able to regulate syncytin gene expression via two GCMa-binding sites upstream of the 5'-long terminal repeat of the syncytin-harboring HERV-W family member in BeWo and JEG3 cells but not in HeLa cells. Furthermore, adenovirus-directed expression of GCMa enhanced syncytin gene expression and syncytin-mediated cell fusion in BeWo and JEG3 cells but not in HeLa cells. Therefore, the integration site of the syncytin-harboring HERV-W family member in the human genome is close to the functional GCMa-binding sites by which GCMa can specifically transactivate syncytin gene expression in trophoblast cells. Our results may help to explain the mechanism underlying the cell fusion event specific for syncytiotrophoblast formation.
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Affiliation(s)
- Chenchou Yu
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan
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31
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Cohen SX, Moulin M, Schilling O, Meyer-Klaucke W, Schreiber J, Wegner M, Müller CW. The GCM domain is a Zn-coordinating DNA-binding domain. FEBS Lett 2002; 528:95-100. [PMID: 12297286 DOI: 10.1016/s0014-5793(02)03257-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Glial cells missing (GCM) proteins form a small family of transcriptional regulators involved in different developmental processes. They contain a DNA-binding domain that is highly conserved from flies to mice and humans and consists of approximately 150 residues. The GCM domain of the mouse GCM homolog a was expressed in bacteria. Extended X-ray absorption fine structure and particle-induced X-ray emission analysis techniques showed the presence of two Zn atoms with four-fold coordination and cysteine/histidine residues as ligands. Zn atoms can be removed from the GCM domain by the Zn chelator phenanthroline only under denaturating conditions. This suggests that the Zn ions are buried in the interior of the GCM domain and that their removal abolishes DNA-binding because it impairs the structure of the GCM domain. Our results define the GCM domain as a new type of Zn-coordinating, sequence-specific DNA-binding domain.
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Affiliation(s)
- Serge X Cohen
- European Molecular Biology Laboratory, Grenoble Outstation, B.P. 181, France
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32
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Abstract
Neurons and glia are generated by multipotent precursors. Recent studies indicate that the choice between the two fates depends on the combined activity of extracellular influences and factors that respond to precise spatial and temporal cues. Drosophila provides a simple genetic model to study the cellular and molecular mechanisms controlling fate choice, mode of precursor division and generation of cell diversity. Moreover, all glial precursors and glial-promoting activities have been identified in Drosophila, which provides us with a unique opportunity to dissect regulatory pathways controlling glial differentiation and specification.
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Affiliation(s)
- Véronique Van De Bor
- Institut de Génétique et Biologie Moléculaire et Cellulaire, IGBMC/CNRS/ULP/INSERM - BP 163 67404 ILLKIRCH, c.u. de Strasbourg, France
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33
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Van De Bor V, Heitzler P, Leger S, Plessy C, Giangrande A. Precocious expression of the Glide/Gcm glial-promoting factor in Drosophila induces neurogenesis. Genetics 2002; 160:1095-106. [PMID: 11901125 PMCID: PMC1462002 DOI: 10.1093/genetics/160.3.1095] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neurons and glial cells depend on similar developmental pathways and often originate from common precursors; however, the differentiation of one or the other cell type depends on the activation of cell-specific pathways. In Drosophila, the differentiation of glial cells depends on a transcription factor, Glide/Gcm. This glial-promoting factor is both necessary and sufficient to induce the central and peripheral glial fates at the expense of the neuronal fate. In a screen for mutations affecting the adult peripheral nervous system, we have found a dominant mutation inducing supernumerary sensory organs. Surprisingly, this mutation is allelic to glide/gcm and induces precocious glide/gcm expression, which, in turn, activates the proneural genes. As a consequence, sensory organs are induced. Thus, temporal misregulation of the Glide/Gcm glial-promoting factor reveals a novel potential for this cell fate determinant. At the molecular level, this implies unpredicted features of the glide/gcm pathway. These findings also emphasize the requirement for both spatial and temporal glide/gcm regulation to achieve proper cell specification within the nervous system.
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Affiliation(s)
- Véronique Van De Bor
- Institut de Génétique et Biologie Moléculaire et Cellulaire IGBMC/CNRS/ULP/INSERM-BP 163 67404 Illkirch, c.u. de Strasbourg, France
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34
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Freeman MR, Doe CQ. Asymmetric Prospero localization is required to generate mixed neuronal/glial lineages in the Drosophila CNS. Development 2001; 128:4103-12. [PMID: 11641232 DOI: 10.1242/dev.128.20.4103] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In many organisms, single neural stem cells can generate both neurons and glia. How are these different cell types produced from a common precursor? In Drosophila, glial cells missing (gcm) is necessary and sufficient to induce glial development in the CNS. gcm mRNA has been reported to be asymmetrically localized to daughter cells during precursor cell division, allowing the daughter cell to produce glia while precursor cell generates neurons. We show that (1) gcm mRNA is uniformly distributed during precursor cell divisions; (2) the Prospero transcription factor is asymmetrically localized into the glial-producing daughter cell; (3) Prospero is required to upregulate gcm expression and induce glial development; and (4) mislocalization of Prospero to the precursor cell leads to ectopic gcm expression and the production of extra glia. We propose a novel model for the separation of glia and neuron fates in mixed lineages in which the asymmetric localization of Prospero results in upregulation of gcm expression and initiation of glial development in only precursor daughter cells.
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Affiliation(s)
- M R Freeman
- HHMI, Institute of Neuroscience, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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35
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Abstract
Glial cells play a central role in the development and function of complex nervous systems. Drosophila is an excellent model organism for the study of mechanisms underlying neural development, and recent attention has been focused on the differentiation and function of glial cells. We now have a nearly complete description of glial cell organization in the embryo, which enables a systematic genetic analysis of glial cell development. Most glia arise from neural stem cells that originate in the neurogenic ectoderm. The bifurcation of glial and neuronal fates is under the control of the glial promoting factor glial cells missing. Differentiation is propagated through the regulation of several transcription factors. Genes have been discovered affecting the terminal differentiation of glia, including the promotion glial-neuronal interactions and the formation of the blood-nerve barrier. Other roles of glia are being explored, including their requirement for axon guidance, neuronal survival, and signaling.
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Affiliation(s)
- B W Jones
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, and Department of Pharmacology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
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36
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Abstract
The fly glial cell deficient/glial cell missing (glide/gcm) gene codes for a transcription factor that induces gliogenesis. Lack of its product eliminates lateral glial cells in the embryonic nervous system. Here we identify a second gene, glide2, that is homologous to glide/gcm in the binding domain and that is also necessary and sufficient to promote glial differentiation. glide2 codes for a transcription factor that displays a weaker and delayed expression compared with glide/gcm. The two genes, which are located 27 kb apart and share cis-regulatory elements, are able to auto- and cross-regulate, indicating that they form a gene complex. Finally, we show that lack of both products eliminates all lateral glial cells, which means that the two genes contain all the fly lateral glial promoting activity.
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Affiliation(s)
| | - Angela Giangrande
- Institut de Génétique et Biologie Moléculaire et Cellulaire, IGBMC/CNRS/ULP/INSERM – BP 163, 67404 Illkirch, c.u. de Strasbourg, France
Corresponding author e-mail:
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37
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Ragone G, Bernardoni R, Giangrande A. A novel mode of asymmetric division identifies the fly neuroglioblast 6-4T. Dev Biol 2001; 235:74-85. [PMID: 11412028 DOI: 10.1006/dbio.2001.0296] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Asymmetric cell divisions and segregation of fate determinants are crucial events in the generation of cell diversity. Fly neuroblasts, the precursors that self-reproduce and generate neurons, represent a clear example of asymmetrically dividing cells. Less is known about how neurons and glial cells are generated by multipotent precursors. Flies provide the ideal model system to study this process. Indeed, neuroglioblasts (NGBs) can be specifically identified and have been shown to require the glide/gcm fate determinant to produce glial cells, which otherwise would become neurons. Here, we follow the division of a specific NGB (NGB6-4T), which produces a neuroblast (NB) and a glioblast (GB). We show that, to generate the glioblast, glide/gcm RNA becomes progressively unequally distributed during NGB division and preferentially segregates. Subsequently, a GB-specific factor is required to maintain glide/gcm expression. Both processes are necessary for gliogenesis, showing that the glial vs. neuronal fate choice is a two-step process. This feature, together with glide/gcm subcellular RNA distribution and the behavior of the NGB mitotic apparatus identify a novel type of division generating cell diversity.
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Affiliation(s)
- G Ragone
- Institut de Génétique et Biologie Moléculaire et Cellulaire, IGBMC/CNRS/ULP/INSERM, Illkirch, c.u. de Strasbourg, 67404, France
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38
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Kobayashi M, Nishikawa K, Yamamoto M. Hematopoietic regulatory domain of gata1 gene is positively regulated by GATA1 protein in zebrafish embryos. Development 2001; 128:2341-50. [PMID: 11493553 DOI: 10.1242/dev.128.12.2341] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Expression of gata1 is regulated through multiple cis-acting GATA motifs. To elucidate regulatory mechanisms of the gata1 gene, we have used zebrafish. To this end, we isolated and analyzed zebrafish gata1 genomic DNA, which resulted in the discovery of a novel intron that was unknown in previous analyses. This intron corresponds to the first intron of other vertebrate Gata1 genes. GFP reporter analyses revealed that this intron and a distal double GATA motif in the regulatory region are important for the regulation of zebrafish gata1 gene expression. To examine whether GATA1 regulates its own gene expression, we microinjected into embryos a GFP reporter gene linked successively to the gata1 gene regulatory region and to GATA1 mRNA. Surprisingly, ectopic expression of the reporter gene was induced at the site of GATA1 overexpression and was dependent on the distal double GATA motif. Functional domain analyses using transgenic fish lines that harbor the gata1-GFP reporter construct revealed that both the N- and C-terminal zinc-finger domains of GATA1, hence intact GATA1 function, are required for the ectopic GFP expression. These results provide the first in vivo evidence that gata1 gene expression undergoes positive autoregulation.
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Affiliation(s)
- M Kobayashi
- Center for Tsukuba Advanced Research Alliance and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
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39
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Abstract
In the Drosophila central nervous system (CNS) about 10% of the cells are of glial nature. A set of molecular markers has allowed unraveling a number of genes controlling glial cell fate determination as well as genes required for glial cell differentiation. Here we focus on the embryonic CNS glia and review the recent progress in the field.
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Affiliation(s)
- C Klämbt
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149, Münster, Germany.
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40
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Miller AA, Bernardoni R, Hindelang C, Kammerer M, Sorrentino S, Van de Bor V, Giangrande A. Role and mechanism of action of glial cell deficient/glial cell missing (glide/gcm), the fly glial promoting factor. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2001; 468:33-46. [PMID: 10635018 DOI: 10.1007/978-1-4615-4685-6_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- A A Miller
- Institut de Génétique et de Biologie Moléculaire et Cellulaire IGBMC/CNRS/INSERM/ULP, Strasbourg, France
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41
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Abstract
Co-conservation of sequence and function is an important principle during evolution. As a consequence, sequence-related genes often have similar functions in evolutionarily distant species. Enter the 'glial cells missing' (gcm) genes. They code for a small family of novel transcription factors that share DNA-binding properties and domain structure. However, no evolutionarily conserved function is apparent as yet. The prototypical gcm from Drosophila dominates nervous system development as a fate switch and master regulator of gliogenesis, whereas mammalian gcm genes have roles in placental morphogenesis and development of the parathyroid gland. Apparently, structure and function sometimes can go separate ways.
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Affiliation(s)
- M Wegner
- Institut für Biochemie, Universität Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany.
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42
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Akiyama-Oda Y, Hotta Y, Tsukita S, Oda H. Mechanism of glia-neuron cell-fate switch in the Drosophila thoracic neuroblast 6–4 lineage. Development 2000; 127:3513-22. [PMID: 10903176 DOI: 10.1242/dev.127.16.3513] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During development of the Drosophila central nervous system, neuroblast 6–4 in the thoracic segment (NB6-4T) divides asymmetrically into a medially located glial precursor cell and a laterally located neuronal precursor cell. In this study, to understand the molecular basis for this glia-neuron cell-fate decision, we examined the effects of some known mutations on the NB6-4T lineage. First, we found that prospero (pros) mutations led to a loss of expression of Glial cells missing, which is essential to trigger glial differentiation, in the NB6-4T lineage. In wild-type embryos, Pros protein was localized at the medial cell cortex of dividing NB6-4T and segregated to the nucleus of the glial precursor cell. miranda and inscuteable mutations altered the behavior of Pros, resulting in failure to correctly switch the glial and neuronal fates. Our results suggested that NB6-4T used the same molecular machinery in the asymmetric cell division as other neuroblasts in cell divisions producing ganglion mother cells. Furthermore, we showed that outside the NB6-4T lineage most glial cells appeared independently of Pros.
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Affiliation(s)
- Y Akiyama-Oda
- Department of Cell Biology, Faculty of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
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43
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Akiyama-Oda Y, Hotta Y, Tsukita S, Oda H. Distinct mechanisms triggering glial differentiation in Drosophila thoracic and abdominal neuroblasts 6-4. Dev Biol 2000; 222:429-39. [PMID: 10837130 DOI: 10.1006/dbio.2000.9727] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neurons and glia are produced in stereotyped patterns after neuroblast cell division during development of the Drosophila central nervous system. The first cell division of thoracic neuroblast 6-4 (NB6-4T) is asymmetric, giving rise to a glial precursor cell and a neuronal precursor cell. In contrast, abdominal NB6-4 (NB6-4A) divides symmetrically to produce two glial cells. To understand the relationship between cell division and glia-neuron cell fate determination, we examined and compared the effects of known cell division mutations on the NB6-4T and NB6-4A lineages. Based on observation of expression of glial fate determination and early glial differentiation genes, the onset of glial differentiation occurred in NB6-4A but not in NB6-4T when both cell cycle progression and cytokinesis were genetically arrested. On the other hand, glial differentiation started in both lineages when cytokinesis was blocked with intact cell cycle progression. These results showed that NB6-4T, but not NB6-4A, requires cell cycle progression for acquisition of glial fate, suggesting that distinct mechanisms trigger glial differentiation in the different lineages.
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Affiliation(s)
- Y Akiyama-Oda
- Department of Cell Biology, Faculty of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
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44
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Schreiber J, Riethmacher-Sonnenberg E, Riethmacher D, Tuerk EE, Enderich J, Bösl MR, Wegner M. Placental failure in mice lacking the mammalian homolog of glial cells missing, GCMa. Mol Cell Biol 2000; 20:2466-74. [PMID: 10713170 PMCID: PMC85439 DOI: 10.1128/mcb.20.7.2466-2474.2000] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The GCM family of transcription factors consists of Drosophila melanogaster GCM, an important regulator of gliogenesis in the fly, and its two mammalian homologs, GCMa and GCMb. To clarify the function of these mammalian homologs, we deleted GCMa in mice. Genetic ablation of murine GCMa (mGCMa) is embryonic lethal, with mice dying between 9.5 and 10 days postcoitum. At the time of death, no abnormalities were apparent in the embryo proper. Nervous system development, in particular, was not impaired, as might have been expected in analogy to Drosophila GCM. Instead, placental failure was the cause of death. In agreement with the selective expression of mGCMa in labyrinthine trophoblasts, mutant placentas did not develop a functional labyrinth layer, which is necessary for nutrient and gas exchange between maternal and fetal blood. Only a few fetal blood vessels entered the placenta, and these failed to thrive and branch normally. Labyrinthine trophoblasts did not differentiate. All other layers of the placenta, including spongiotrophoblast and giant cell layer, formed normally. Our results indicate that mGCMa plays a critical role in trophoblast differentiation and the signal transduction processes required for normal vascularization of the placenta.
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Affiliation(s)
- J Schreiber
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, D-20246 Hamburg, Germany
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45
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Granderath S, Bunse I, Klämbt C. gcm and pointed synergistically control glial transcription of the Drosophila gene loco. Mech Dev 2000; 91:197-208. [PMID: 10704844 DOI: 10.1016/s0925-4773(99)00304-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
In Drosophila lateral glial cell development is initiated by the transcription factor encoded by glial cells missing. glial cells missing activates downstream transcription factors such as repo and pointed which subsequently control terminal glial differentiation. The gene loco has been identified as a potential target gene of pointed and is involved in terminal glial differentiation. It encodes an RGS domain protein expressed specifically by the lateral glial cells in the developing embryonic CNS. Here we analyzed the loco promoter and the control of the glial-specific transcription pattern. Using promoter-reporter gene fusions we identified a 1.9 kb promoter element capable of directing the almost complete loco gene expression pattern. Sequence analysis suggested the presence of gcm and pointed DNA binding sites. Following in vitro mutagenesis of these sites we demonstrated their relevance in vivo. The expression of loco is initially dependent on gcm. During subsequent stages of embryonic development gcm and pointed appear to activate loco transcription synergistically. In addition, at least two other factors appear to repress loco expression in the ectoderm and in the CNS midline cells.
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Affiliation(s)
- S Granderath
- Institut für Neurobiologie, Universität Münster, Badestrasse 9, D-48149, Münster, Germany
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46
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Tuerk EE, Schreiber J, Wegner M. Protein stability and domain topology determine the transcriptional activity of the mammalian glial cells missing homolog, GCMb. J Biol Chem 2000; 275:4774-82. [PMID: 10671510 DOI: 10.1074/jbc.275.7.4774] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glial cells missing (GCM) family of transcription factors consists of Drosophila GCM and the mammalian proteins GCMa and GCMb. They are expressed in a highly restricted manner during development and are known or assumed to be important regulators of developmental fate decisions. As the biochemical properties of GCMb have not been studied so far, we have undertaken a detailed structure-function analysis of the mouse GCMb (mGCMb) protein. DNA-binding specificity was very similar to that of other GCM proteins. Nevertheless, mGCMb was only a weak transcriptional activator in a number of different tissue culture systems. Interestingly, this was not due to an intrinsic absence of transactivation potential. In effect, we were able to identify two separate transactivation domains within mGCMb, one carboxyl-terminally adjacent to the DNA-binding domain and the second within the extreme carboxyl terminus. Activity of both transactivation domains was, however, modulated by an inhibitory region unique to mGCMb and located between the two transactivation domains. Furthermore, pulse-chase experiments proved that the mGCMb protein has a half-life approximately four times shorter than mGCMa. Introduction of the above mentioned inhibitory domain of mGCMb into mGCMa shortened the half-life of mGCMa to a value typical of mGCMb with a concomitant reduction in transactivation potential. Given the strong correlation between protein stability and transactivation potential, functional differences between the two mammalian GCM homologs are likely due to differences in stability with a single inhibitory region in mGCMb being involved in the reduction of both.
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Affiliation(s)
- E E Tuerk
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, Martinistrasse 52, D-20246 Hamburg, Germany
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47
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Bernardoni R, Kammerer M, Vonesch JL, Giangrande A. Gliogenesis depends on glide/gcm through asymmetric division of neuroglioblasts. Dev Biol 1999; 216:265-75. [PMID: 10588877 DOI: 10.1006/dbio.1999.9511] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Some neurons and glial cells originate from neuroblasts and glioblasts, stem cells that delaminate from the ectoderm of developing fly embryos. A second class of glial cells and neurons differentiates from multipotent precursors, the neuroglioblasts. The differentiation of both glial cell types depends on glial cell deficient/glial cell missing (glide/gcm). Although it has been shown that this transcription factor promotes gliogenesis at the expense of neurogenesis, the cellular mechanisms underlying this fate choice are poorly understood. Using loss and gain of function glide/gcm mutations here we show that the cell fate choice takes place in the neuroglioblast, which divides and produces a glioblast and a neuroblast. Such choice requires the asymmetric distribution of glide/gcm RNA, which accumulates preferentially on one side of the neuroglioblast and is inherited by one cell, the presumptive glioblast. Interestingly, glial cells can differentiate from cells that delaminate as neuroglioblasts or they can arise from cells that start expressing glide/gcm several hours after delamination of a neuroblast. Altogether, these findings identify a novel type of asymmetric cell division and disclose the lineage relationships between glia and neurons. They also reveal the mode of action of the glide/gcm promoting factor.
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Affiliation(s)
- R Bernardoni
- Institut de Génétique et Biologie Moléculaire et Cellulaire, IGBMC/CNRS/INSERM/ULP, Illkirch, c.u. de Strasbourg, 67404, France
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48
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Abstract
Glial cells are pivotal players during the development and function of complex nervous systems. In Drosophila, recent genetic analyses have revealed several genes that control differentiation and function of CNS glial cells and their interactions with neurons can be studied in detail at the CNS midline, where it is essential for the correct establishment of the commissural axon pattern.
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Affiliation(s)
- S Granderath
- Institut für Neurobiologie Universität Münster Badestrasse 9, D-48149, Münster, Germany
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