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Nguyen PK, Cheng LY. Drosophila medulla neuroblast termination via apoptosis, differentiation, and gliogenic switch is scheduled by the depletion of the neuroepithelial stem cell pool. eLife 2024; 13:e96876. [PMID: 38905123 PMCID: PMC11262793 DOI: 10.7554/elife.96876] [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: 02/22/2024] [Accepted: 06/20/2024] [Indexed: 06/23/2024] Open
Abstract
The brain is consisted of diverse neurons arising from a limited number of neural stem cells. Drosophila neural stem cells called neuroblasts (NBs) produces specific neural lineages of various lineage sizes depending on their location in the brain. In the Drosophila visual processing centre - the optic lobes (OLs), medulla NBs derived from the neuroepithelium (NE) give rise to neurons and glia cells of the medulla cortex. The timing and the mechanisms responsible for the cessation of medulla NBs are so far not known. In this study, we show that the termination of medulla NBs during early pupal development is determined by the exhaustion of the NE stem cell pool. Hence, altering NE-NB transition during larval neurogenesis disrupts the timely termination of medulla NBs. Medulla NBs terminate neurogenesis via a combination of apoptosis, terminal symmetric division via Prospero, and a switch to gliogenesis via Glial Cell Missing (Gcm); however, these processes occur independently of each other. We also show that temporal progression of the medulla NBs is mostly not required for their termination. As the Drosophila OL shares a similar mode of division with mammalian neurogenesis, understanding when and how these progenitors cease proliferation during development can have important implications for mammalian brain size determination and regulation of its overall function.
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Affiliation(s)
- Phuong-Khanh Nguyen
- Peter MacCallum Cancer CentreMelbourneAustralia
- Department of Anatomy and Physiology, The University of MelbourneMelbourneAustralia
| | - Louise Y Cheng
- Peter MacCallum Cancer CentreMelbourneAustralia
- Department of Anatomy and Physiology, The University of MelbourneMelbourneAustralia
- Sir Peter MacCallum Department of Oncology, The University of MelbourneMelbourneAustralia
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Zhu H, Zhao SD, Ray A, Zhang Y, Li X. A comprehensive temporal patterning gene network in Drosophila medulla neuroblasts revealed by single-cell RNA sequencing. Nat Commun 2022; 13:1247. [PMID: 35273186 PMCID: PMC8913700 DOI: 10.1038/s41467-022-28915-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 02/12/2022] [Indexed: 12/24/2022] Open
Abstract
During development, neural progenitors are temporally patterned to sequentially generate a variety of neural types. In Drosophila neural progenitors called neuroblasts, temporal patterning is regulated by cascades of Temporal Transcription Factors (TTFs). However, known TTFs were mostly identified through candidate approaches and may not be complete. In addition, many fundamental questions remain concerning the TTF cascade initiation, progression, and termination. In this work, we use single-cell RNA sequencing of Drosophila medulla neuroblasts of all ages to identify a list of previously unknown TTFs, and experimentally characterize their roles in temporal patterning and neuronal specification. Our study reveals a comprehensive temporal gene network that patterns medulla neuroblasts from start to end. Furthermore, the speed of the cascade progression is regulated by Lola transcription factors expressed in all medulla neuroblasts. Our comprehensive study of the medulla neuroblast temporal cascade illustrates mechanisms that may be conserved in the temporal patterning of neural progenitors. During development, neural progenitors generate a variety of neural types sequentially. Here the authors examine gene expression patterns in Drosophila neural progenitors at single-cell level, and identify a gene regulatory network controlling the sequential generation of different neural types.
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Affiliation(s)
- Hailun Zhu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Sihai Dave Zhao
- Department of Statistics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Alokananda Ray
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yu Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Xin Li
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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Saul J, Hirose T, Horvitz HR. The transcriptional corepressor CTBP-1 acts with the SOX family transcription factor EGL-13 to maintain AIA interneuron cell identity in Caenorhabditis elegans. eLife 2022; 11:74557. [PMID: 35119366 PMCID: PMC8816384 DOI: 10.7554/elife.74557] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 01/10/2022] [Indexed: 11/17/2022] Open
Abstract
Cell identity is characterized by a distinct combination of gene expression, cell morphology, and cellular function established as progenitor cells divide and differentiate. Following establishment, cell identities can be unstable and require active and continuous maintenance throughout the remaining life of a cell. Mechanisms underlying the maintenance of cell identities are incompletely understood. Here, we show that the gene ctbp-1, which encodes the transcriptional corepressor C-terminal binding protein-1 (CTBP-1), is essential for the maintenance of the identities of the two AIA interneurons in the nematode Caenorhabditis elegans. ctbp-1 is not required for the establishment of the AIA cell fate but rather functions cell-autonomously and can act in later larval stage and adult worms to maintain proper AIA gene expression, morphology and function. From a screen for suppressors of the ctbp-1 mutant phenotype, we identified the gene egl-13, which encodes a SOX family transcription factor. We found that egl-13 regulates AIA function and aspects of AIA gene expression, but not AIA morphology. We conclude that the CTBP-1 protein maintains AIA cell identity in part by utilizing EGL-13 to repress transcriptional activity in the AIAs. More generally, we propose that transcriptional corepressors like CTBP-1 might be critical factors in the maintenance of cell identities, harnessing the DNA-binding specificity of transcription factors like EGL-13 to selectively regulate gene expression in a cell-specific manner.
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Affiliation(s)
- Josh Saul
- Department of Biology, Massachusetts Institute of Technology, Howard Hughes Medical Institute, Cambridge, United States
| | - Takashi Hirose
- Department of Biology, Massachusetts Institute of Technology, Howard Hughes Medical Institute, Cambridge, United States
| | - H Robert Horvitz
- Department of Biology, Massachusetts Institute of Technology, Howard Hughes Medical Institute, Cambridge, United States
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Neuronal diversity and convergence in a visual system developmental atlas. Nature 2020; 589:88-95. [PMID: 33149298 PMCID: PMC7790857 DOI: 10.1038/s41586-020-2879-3] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 08/27/2020] [Indexed: 01/01/2023]
Abstract
Deciphering how neuronal diversity is established and maintained requires a detailed knowledge of neuronal gene expression throughout development. In contrast to mammalian brains1,2, the large neuronal diversity of the Drosophila optic lobes3 and its connectome4–6 are almost completely characterized. However, a molecular characterization of this diversity, particularly during development, has been lacking. We present novel insights into brain development through a nearly exhaustive description of the transcriptomic diversity of the optic lobes. We acquired the transcriptome of 275,000 single-cells at adult and five pupal stages, and developed a machine learning framework to assign them to almost 200 cell-types at all timepoints. We discovered two large neuronal populations that wrap neuropils during development but die just before adulthood, as well as neuronal subtypes that partition dorsal and ventral visual circuits by differential Wnt signaling throughout development. Moreover, we showed that neurons of the same type but produced days apart synchronize their transcriptomes shortly after being produced. We also resolved during synaptogenesis neuronal subtypes that converge to indistinguishable transcriptomic profiles in adults while greatly differing in morphology and connectivity. Our datasets almost completely account for the known neuronal diversity of the optic lobes and serve as a paradigm to understand brain development across species.
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The Integrator Complex Prevents Dedifferentiation of Intermediate Neural Progenitors back into Neural Stem Cells. Cell Rep 2020; 27:987-996.e3. [PMID: 31018143 DOI: 10.1016/j.celrep.2019.03.089] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/31/2019] [Accepted: 03/24/2019] [Indexed: 01/08/2023] Open
Abstract
Mutations of the Integrator subunits are associated with neurodevelopmental disorders and cancers. However, their role during neural development is poorly understood. Here, we demonstrate that the Drosophila Integrator complex prevents dedifferentiation of intermediate neural progenitors (INPs) during neural stem cell (neuroblast) lineage development. Loss of intS5, intS8, and intS1 generated ectopic type II neuroblasts. INP-specific knockdown of intS8, intS1, and intS2 resulted in the formation of excess type II neuroblasts, indicating that Integrator prevents INP dedifferentiation. Cell-type-specific DamID analysis identified 1413 IntS5-binding sites in INPs, including zinc-finger transcription factor earmuff (erm). Furthermore, erm expression is lost in intS5 and intS8 mutant neuroblast lineages, and intS8 genetically interacts with erm to suppress the formation of ectopic neuroblasts. Taken together, our data demonstrate that the Drosophila Integrator complex plays a critical role in preventing INP dedifferentiation primarily by regulating a key transcription factor Erm that also suppresses INP dedifferentiation.
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Wang L, Liu T, Liang R, Wang G, Liu Y, Zou J, Liu N, Zhang B, Liu Y, Ding X, Cai X, Wang Z, Xu X, Ricordi C, Wang S, Shen Z. Mesenchymal stem cells ameliorate β cell dysfunction of human type 2 diabetic islets by reversing β cell dedifferentiation. EBioMedicine 2020; 51:102615. [PMID: 31918404 PMCID: PMC7000334 DOI: 10.1016/j.ebiom.2019.102615] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/05/2019] [Accepted: 12/17/2019] [Indexed: 02/07/2023] Open
Abstract
Background A physiological hallmark of patients with type 2 diabetes mellitus (T2DM) is β cell dysfunction. Despite adequate treatment, it is an irreversible process that follows disease progression. Therefore, the development of novel therapies that restore β cell function is of utmost importance. Methods This study aims to unveil the mechanistic action of mesenchymal stem cells (MSCs) by investigating its impact on isolated human T2DM islets ex vivo and in vivo. Findings We propose that MSCs can attenuate β cell dysfunction by reversing β cell dedifferentiation in an IL-1Ra-mediated manner. In response to the elevated expression of proinflammatory cytokines in human T2DM islet cells, we observed that MSCs was activated to secret IL-1R antagonist (IL-1Ra) which acted on the inflammed islets and reversed β cell dedifferentiation, suggesting a crosstalk between MSCs and human T2DM islets. The co-transplantation of MSCs with human T2DM islets in diabetic SCID mice and intravenous infusion of MSCs in db/db mice revealed the reversal of β cell dedifferentiation and improved glycaemic control in the latter. Interpretation This evidence highlights the potential of MSCs in future cell-based therapies regarding the amelioration of β cell dysfunction.
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Affiliation(s)
- Le Wang
- Organ Transplant Centre, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China; NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China
| | - Tengli Liu
- NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China; Diabetes Research Institute Federation, Hollywood, FL 33021, USA
| | - Rui Liang
- NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China; Diabetes Research Institute Federation, Hollywood, FL 33021, USA
| | - Guanqiao Wang
- Key Laboratory of Transplant Medicine, Chinese Academy of Medical Sciences, Tianjin 300192, China
| | - Yaojuan Liu
- NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China
| | - Jiaqi Zou
- NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China
| | - Na Liu
- NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China
| | - Boya Zhang
- Organ Transplant Centre, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China
| | - Yan Liu
- Key Laboratory of Transplant Medicine, Chinese Academy of Medical Sciences, Tianjin 300192, China
| | - Xuejie Ding
- Organ Transplant Centre, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China
| | - Xiangheng Cai
- The First Central Clinical College, Tianjin Medical University, Tianjin, 300192, China
| | - Zhiping Wang
- Organ Transplant Centre, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China
| | - Xiumin Xu
- Diabetes Research Institute, Cell Transplant Centre; Department of Surgery; Department Medicine; Miller School of Medicine, University of Miami, Miami, FL 33136, USA; The Cure Alliance, Miami, FL 33137, USA; Diabetes Research Institute Federation, Hollywood, FL 33021, USA
| | - Camillo Ricordi
- Diabetes Research Institute, Cell Transplant Centre; Department of Surgery; Department Medicine; Miller School of Medicine, University of Miami, Miami, FL 33136, USA; The Cure Alliance, Miami, FL 33137, USA; Diabetes Research Institute Federation, Hollywood, FL 33021, USA
| | - Shusen Wang
- Organ Transplant Centre, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China; NHC Key Laboratory for Critical Care Medicine, Tianjin 300384, China; Diabetes Research Institute Federation, Hollywood, FL 33021, USA.
| | - Zhongyang Shen
- Organ Transplant Centre, Tianjin First Central Hospital, Nankai University, Tianjin 300192, China; Key Laboratory of Transplant Medicine, Chinese Academy of Medical Sciences, Tianjin 300192, China.
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7
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Froldi F, Pachnis P, Szuperák M, Costas O, Fernando T, Gould AP, Cheng LY. Histidine is selectively required for the growth of Myc-dependent dedifferentiation tumours in the Drosophila CNS. EMBO J 2019; 38:embj.201899895. [PMID: 30804004 PMCID: PMC6443203 DOI: 10.15252/embj.201899895] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 01/09/2019] [Accepted: 01/16/2019] [Indexed: 12/31/2022] Open
Abstract
Rewired metabolism of glutamine in cancer has been well documented, but less is known about other amino acids such as histidine. Here, we use Drosophila cancer models to show that decreasing the concentration of histidine in the diet strongly inhibits the growth of mutant clones induced by loss of Nerfin‐1 or gain of Notch activity. In contrast, changes in dietary histidine have much less effect on the growth of wildtype neural stem cells and Prospero neural tumours. The reliance of tumours on dietary histidine and also on histidine decarboxylase (Hdc) depends upon their growth requirement for Myc. We demonstrate that Myc overexpression in nerfin‐1 tumours is sufficient to switch their mode of growth from histidine/Hdc sensitive to resistant. This study suggests that perturbations in histidine metabolism selectively target neural tumours that grow via a dedifferentiation process involving large cell size increases driven by Myc.
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Affiliation(s)
- Francesca Froldi
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Vic., Australia
| | | | - Milán Szuperák
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia.,Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Olivia Costas
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Vic., Australia
| | | | | | - Louise Y Cheng
- Peter MacCallum Cancer Centre, Parkville, Vic., Australia .,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Vic., Australia.,The Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic., Australia
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8
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The Scalloped and Nerfin-1 Transcription Factors Cooperate to Maintain Neuronal Cell Fate. Cell Rep 2018; 25:1561-1576.e7. [DOI: 10.1016/j.celrep.2018.10.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/14/2018] [Accepted: 10/09/2018] [Indexed: 02/08/2023] Open
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9
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Lin X, Wang F, Li Y, Zhai C, Wang G, Zhang X, Gao Y, Yi T, Sun D, Wu S. The SCF ubiquitin ligase Slimb controls Nerfin-1 turnover in Drosophila. Biochem Biophys Res Commun 2018; 495:629-633. [DOI: 10.1016/j.bbrc.2017.11.090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 11/13/2017] [Indexed: 12/14/2022]
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