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Crawford BI, Talley MJ, Russman J, Riddle J, Torres S, Williams T, Longworth MS. Condensin-mediated restriction of retrotransposable elements facilitates brain development in Drosophila melanogaster. Nat Commun 2024; 15:2716. [PMID: 38548759 PMCID: PMC10978865 DOI: 10.1038/s41467-024-47042-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/18/2024] [Indexed: 04/01/2024] Open
Abstract
Neural stem and progenitor cell (NSPC) maintenance is essential for ensuring that organisms are born with proper brain volumes and head sizes. Microcephaly is a disorder in which babies are born with significantly smaller head sizes and cortical volumes. Mutations in subunits of the DNA organizing complex condensin have been identified in microcephaly patients. However, the molecular mechanisms by which condensin insufficiency causes microcephaly remain elusive. We previously identified conserved roles for condensins in repression of retrotransposable elements (RTEs). Here, we show that condensin subunit knockdown in NSPCs of the Drosophila larval central brain increases RTE expression and mobility which causes cell death, and significantly decreases adult head sizes and brain volumes. These findings suggest that unrestricted RTE expression and activity may lead to improper brain development in condensin insufficient organisms, and lay the foundation for future exploration of causative roles for RTEs in other microcephaly models.
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Affiliation(s)
- Bert I Crawford
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Mary Jo Talley
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Joshua Russman
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - James Riddle
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Sabrina Torres
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Troy Williams
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Michelle S Longworth
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, 44195, USA.
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2
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Lim Y. Transcription factors in microcephaly. Front Neurosci 2023; 17:1302033. [PMID: 38094004 PMCID: PMC10716367 DOI: 10.3389/fnins.2023.1302033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/06/2023] [Indexed: 02/01/2024] Open
Abstract
Higher cognition in humans, compared to other primates, is often attributed to an increased brain size, especially forebrain cortical surface area. Brain size is determined through highly orchestrated developmental processes, including neural stem cell proliferation, differentiation, migration, lamination, arborization, and apoptosis. Disruption in these processes often results in either a small (microcephaly) or large (megalencephaly) brain. One of the key mechanisms controlling these developmental processes is the spatial and temporal transcriptional regulation of critical genes. In humans, microcephaly is defined as a condition with a significantly smaller head circumference compared to the average head size of a given age and sex group. A growing number of genes are identified as associated with microcephaly, and among them are those involved in transcriptional regulation. In this review, a subset of genes encoding transcription factors (e.g., homeobox-, basic helix-loop-helix-, forkhead box-, high mobility group box-, and zinc finger domain-containing transcription factors), whose functions are important for cortical development and implicated in microcephaly, are discussed.
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Affiliation(s)
- Youngshin Lim
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Biomedical Science Education, Charles R. Drew University of Medicine and Science, Los Angeles, CA, United States
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3
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Mannino MC, Bartels Cassidy M, Florez S, Rusan Z, Chakraborty S, Schoborg T. The neurodevelopmental transcriptome of the Drosophila melanogaster microcephaly gene abnormal spindle reveals a role for temporal transcription factors and the immune system in regulating brain size. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523369. [PMID: 36711768 PMCID: PMC9882087 DOI: 10.1101/2023.01.09.523369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The coordination of cellular behaviors during neurodevelopment is critical for determining the form, function, and size of the central nervous system. Mutations in the vertebrate Abnormal Spindle-Like, Microcephaly Associated (ASPM) gene and its Drosophila melanogaster ortholog abnormal spindle (asp) lead to microcephaly, a reduction in overall brain size whose etiology remains poorly defined. Here we provide the neurodevelopmental transcriptional landscape for a Drosophila model for autosomal recessive primary microcephaly (MCPH) and extend our findings into the functional realm in an attempt to identify the key cellular mechanisms responsible for Asp-dependent brain growth and development. We identify multiple transcriptomic signatures, including new patterns of co-expressed genes in the developing CNS. Defects in optic lobe neurogenesis were detected in larval brains through downregulation of temporal transcription factors (tTFs) and Notch signaling targets, which correlated with a significant reduction in brain size and total cell numbers during the neurogenic window of development. We also found inflammation as a hallmark of asp MCPH brains, detectable throughout every stage of CNS development, which also contributes to the brain size phenotype. Finally, we show that apoptosis is not a primary driver of the asp MCPH phenotype, further highlighting an intrinsic Asp-dependent neurogenesis promotion mechanism that is independent of cell death. Collectively, our results suggest that the etiology of asp MCPH is complex and that a comprehensive view of the cellular basis of the disorder requires an understanding of how multiple pathway inputs collectively determine the microcephaly phenotype.
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Affiliation(s)
- Maria C. Mannino
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Steven Florez
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Shalini Chakraborty
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Todd Schoborg
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
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4
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Davis ES, Voss G, Miesfeld JB, Zarate-Sanchez J, Voss SR, Glaser T. The rax homeobox gene is mutated in the eyeless axolotl, Ambystoma mexicanum. Dev Dyn 2021; 250:807-821. [PMID: 32864847 PMCID: PMC8907009 DOI: 10.1002/dvdy.246] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 08/11/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Vertebrate eye formation requires coordinated inductive interactions between different embryonic tissue layers, first described in amphibians. A network of transcription factors and signaling molecules controls these steps, with mutations causing severe ocular, neuronal, and craniofacial defects. In eyeless mutant axolotls, eye morphogenesis arrests at the optic vesicle stage, before lens induction, and development of ventral forebrain structures is disrupted. RESULTS We identified a 5-bp deletion in the rax (retina and anterior neural fold homeobox) gene, which was tightly linked to the recessive eyeless (e) axolotl locus in an F2 cross. This frameshift mutation, in exon 2, truncates RAX protein within the homeodomain (P154fs35X). Quantitative RNA analysis shows that mutant and wild-type rax transcripts are equally abundant in E/e embryos. Translation appears to initiate from dual start codons, via leaky ribosome scanning, a conserved feature among gnathostome RAX proteins. Previous data show rax is expressed in the optic vesicle and diencephalon, deeply conserved among metazoans, and required for eye formation in other species. CONCLUSION The eyeless axolotl mutation is a null allele in the rax homeobox gene, with primary defects in neural ectoderm, including the retinal and hypothalamic primordia.
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Affiliation(s)
- Erik S. Davis
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
| | - Gareth Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
| | - Joel B. Miesfeld
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
| | - Juan Zarate-Sanchez
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
- Davis Senior High School, Davis, California
| | - S. Randal Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
| | - Tom Glaser
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
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5
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Trivedi D, CM V, Bisht K, Janardan V, Pandit A, Basak B, H S, Ramesh N, Raghu P. A genome engineering resource to uncover principles of cellular organization and tissue architecture by lipid signaling. eLife 2020; 9:e55793. [PMID: 33320085 PMCID: PMC7771963 DOI: 10.7554/elife.55793] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 12/14/2020] [Indexed: 12/14/2022] Open
Abstract
Phosphoinositides (PI) are key regulators of cellular organization in eukaryotes and genes that tune PI signaling are implicated in human disease mechanisms. Biochemical analyses and studies in cultured cells have identified a large number of proteins that can mediate PI signaling. However, the role of such proteins in regulating cellular processes in vivo and development in metazoans remains to be understood. Here, we describe a set of CRISPR-based genome engineering tools that allow the manipulation of each of these proteins with spatial and temporal control during metazoan development. We demonstrate the use of these reagents to deplete a set of 103 proteins individually in the Drosophila eye and identify several new molecules that control eye development. Our work demonstrates the power of this resource in uncovering the molecular basis of tissue homeostasis during normal development and in human disease biology.
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Affiliation(s)
- Deepti Trivedi
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Vinitha CM
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Karishma Bisht
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Vishnu Janardan
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Awadhesh Pandit
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Bishal Basak
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Shwetha H
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Navyashree Ramesh
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
| | - Padinjat Raghu
- National Centre for Biological Sciences-TIFR, GKVK CampusBangaloreIndia
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6
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Gallot A, Sauzet S, Desouhant E. Kin recognition: Neurogenomic response to mate choice and sib mating avoidance in a parasitic wasp. PLoS One 2020; 15:e0241128. [PMID: 33104752 PMCID: PMC7588116 DOI: 10.1371/journal.pone.0241128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 10/08/2020] [Indexed: 12/01/2022] Open
Abstract
Sib mating increases homozygosity, which therefore increases the risk of inbreeding depression. Selective pressures have favoured the evolution of kin recognition and avoidance of sib mating in numerous species, including the parasitoid wasp Venturia canescens. We studied the female neurogenomic response associated with sib mating avoidance after females were exposed to courtship displays by i) unrelated males or ii) related males or iii) no courtship (controls). First, by comparing the transcriptional responses of females exposed to courtship displays to those exposed to controls, we saw a rapid and extensive transcriptional shift consistent with social environment. Second, by comparing the transcriptional responses of females exposed to courtship by related to those exposed to unrelated males, we characterized distinct and repeatable transcriptomic patterns that correlated with the relatedness of the courting male. Network analysis revealed 3 modules of specific ‘sib-responsive’ genes that were distinct from other ‘courtship-responsive’ modules. Therefore, specific neurogenomic states with characteristic brain transcriptomes associated with different behavioural responses affect sib mating avoidance behaviour.
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Affiliation(s)
- Aurore Gallot
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, Université Lyon 1, Université de Lyon, UMR 5558, Villeurbanne, France
- * E-mail:
| | - Sandrine Sauzet
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, Université Lyon 1, Université de Lyon, UMR 5558, Villeurbanne, France
- Institut de Génétique Humaine, CNRS–Université de Montpellier, UMR 9002, Biology of Repetitive Sequences, Montpellier, France
| | - Emmanuel Desouhant
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, Université Lyon 1, Université de Lyon, UMR 5558, Villeurbanne, France
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7
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Li G, Hidalgo A. Adult Neurogenesis in the Drosophila Brain: The Evidence and the Void. Int J Mol Sci 2020; 21:ijms21186653. [PMID: 32932867 PMCID: PMC7554932 DOI: 10.3390/ijms21186653] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/03/2020] [Accepted: 09/08/2020] [Indexed: 01/05/2023] Open
Abstract
Establishing the existence and extent of neurogenesis in the adult brain throughout the animals including humans, would transform our understanding of how the brain works, and how to tackle brain damage and disease. Obtaining convincing, indisputable experimental evidence has generally been challenging. Here, we revise the state of this question in the fruit-fly Drosophila. The developmental neuroblasts that make the central nervous system and brain are eliminated, either through apoptosis or cell cycle exit, before the adult fly ecloses. Despite this, there is growing evidence that cell proliferation can take place in the adult brain. This occurs preferentially at, but not restricted to, a critical period. Adult proliferating cells can give rise to both glial cells and neurons. Neuronal activity, injury and genetic manipulation in the adult can increase the incidence of both gliogenesis and neurogenesis, and cell number. Most likely, adult glio- and neuro-genesis promote structural brain plasticity and homeostasis. However, a definitive visualisation of mitosis in the adult brain is still lacking, and the elusive adult progenitor cells are yet to be identified. Resolving these voids is important for the fundamental understanding of any brain. Given its powerful genetics, Drosophila can expedite discovery into mammalian adult neurogenesis in the healthy and diseased brain.
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8
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Maccallini P, Bavasso F, Scatolini L, Bucciarelli E, Noviello G, Lisi V, Palumbo V, D'Angeli S, Cacchione S, Cenci G, Ciapponi L, Wakefield JG, Gatti M, Raffa GD. Intimate functional interactions between TGS1 and the Smn complex revealed by an analysis of the Drosophila eye development. PLoS Genet 2020; 16:e1008815. [PMID: 32453722 PMCID: PMC7289441 DOI: 10.1371/journal.pgen.1008815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/11/2020] [Accepted: 04/30/2020] [Indexed: 11/27/2022] Open
Abstract
Trimethylguanosine synthase 1 (TGS1) is a conserved enzyme that mediates formation of the trimethylguanosine cap on several RNAs, including snRNAs and telomerase RNA. Previous studies have shown that TGS1 binds the Survival Motor Neuron (SMN) protein, whose deficiency causes spinal muscular atrophy (SMA). Here, we analyzed the roles of the Drosophila orthologs of the human TGS1 and SMN genes. We show that the Drosophila TGS1 protein (dTgs1) physically interacts with all subunits of the Drosophila Smn complex (Smn, Gem2, Gem3, Gem4 and Gem5), and that a human TGS1 transgene rescues the mutant phenotype caused by dTgs1 loss. We demonstrate that both dTgs1 and Smn are required for viability of retinal progenitor cells and that downregulation of these genes leads to a reduced eye size. Importantly, overexpression of dTgs1 partially rescues the eye defects caused by Smn depletion, and vice versa. These results suggest that the Drosophila eye model can be exploited for screens aimed at the identification of genes and drugs that modify the phenotypes elicited by Tgs1 and Smn deficiency. These modifiers could help to understand the molecular mechanisms underlying SMA pathogenesis and devise new therapies for this genetic disease. We explored the functional relationships between TGS1 and SMN using Drosophila as model organism. TGS1 is an enzyme that modifies the structure of the 5’-end of several RNAs, including telomerase RNA and the small nuclear RNAs (snRNAs) that are required for messenger RNA maturation. The SMN protein regulates snRNAs biogenesis and mutations in human SMN cause Spinal Muscular Atrophy (SMA), a devastating disorder characterized by neurodegeneration, progressive paralysis and death. We show that mutations in the Drosophila TGS1 (dTgs1) gene cause lethality, which is rescued by a human TGS1 transgene. We also show that the dTgs1 protein physically interacts with all subunits of the Smn complex, and that downregulation of either dTgs1 or Smn leads to a reduced Drosophila eye size. Notably, overexpression of dTgs1 partially rescues the eye defects caused by Smn knockdown, and vice versa, indicating that these genes cooperate in eye development. These results suggest that the eye model can be exploited for screens aimed at detection of chemical and genetic modifiers of the eye mutant phenotype elicited by dTgs1 and Smn deficiency, providing new clues about SMA pathogenesis and potential therapies.
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Affiliation(s)
- Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | | | - Gemma Noviello
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Veronica Lisi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Simone D'Angeli
- Dipartimento di Biologia Ambientale, Sapienza University of Rome, Rome, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Fondazione Cenci Bolognetti, Istituto Pasteur, Rome, Italy
| | - Laura Ciapponi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - James G. Wakefield
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, United Kingdom
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
- * E-mail: (MG); (GDR)
| | - Grazia Daniela Raffa
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- * E-mail: (MG); (GDR)
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9
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Li G, Forero MG, Wentzell JS, Durmus I, Wolf R, Anthoney NC, Parker M, Jiang R, Hasenauer J, Strausfeld NJ, Heisenberg M, Hidalgo A. A Toll-receptor map underlies structural brain plasticity. eLife 2020; 9:52743. [PMID: 32066523 PMCID: PMC7077983 DOI: 10.7554/elife.52743] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 02/12/2020] [Indexed: 12/28/2022] Open
Abstract
Experience alters brain structure, but the underlying mechanism remained unknown. Structural plasticity reveals that brain function is encoded in generative changes to cells that compete with destructive processes driving neurodegeneration. At an adult critical period, experience increases fiber number and brain size in Drosophila. Here, we asked if Toll receptors are involved. Tolls demarcate a map of brain anatomical domains. Focusing on Toll-2, loss of function caused apoptosis, neurite atrophy and impaired behaviour. Toll-2 gain of function and neuronal activity at the critical period increased cell number. Toll-2 induced cycling of adult progenitor cells via a novel pathway, that antagonized MyD88-dependent quiescence, and engaged Weckle and Yorkie downstream. Constant knock-down of multiple Tolls synergistically reduced brain size. Conditional over-expression of Toll-2 and wek at the adult critical period increased brain size. Through their topographic distribution, Toll receptors regulate neuronal number and brain size, modulating structural plasticity in the adult brain. Everything that you experience leaves its mark on your brain. When you learn something new, the neurons involved in the learning episode grow new projections and form new connections. Your brain may even produce new neurons. Physical exercise can induce similar changes, as can taking antidepressants. By contrast, stress, depression, ageing and disease can have the opposite effect, triggering neurons to break down and even die. The ability of the brain to change in response to experience is known as structural plasticity, and it is in a tug-of-war with processes that drive neurodegeneration. Structural plasticity occurs in other species too: for example, it was described in the fruit fly more than a quarter of a century ago. Yet, the molecular mechanisms underlying structural plasticity remain unclear. Li et al. now show that, in fruit flies, this plasticity involves Toll receptors, a family of proteins present in the brain but best known for their role in the immune system. Fruit flies have nine different Toll receptors, the most abundant being Toll-2. When activated, these proteins can trigger a series of molecular events in a cell. Li et al. show that increasing the amount of Toll-2 in the fly brain makes the brain produce new neurons. Activating neurons in a brain region has the same effect, and this increase in neuron number also depends on Toll-2. By contrast, reducing the amount of Toll-2 causes neurons to lose their projections and connections, and to die, and impairs fly behaviour. Li et al. also show that each Toll receptor has a unique distribution across the fly brain. Different types of experiences activate different brain regions, and therefore different Toll receptors. These go on to trigger a common molecular cascade, but they modulate it such as to result in distinct outcomes. By working together in different combinations, Toll receptors can promote either the death or survival of neurons, and they can also drive specific brain cells to remain dormant or to produce new neurons. By revealing how experience changes the brain, Li et al. provide clues to the way neurons work and form; these findings may also help to find new treatments for disorders that change brain structure, such as certain psychiatric conditions. Toll-like receptors in humans could thus represent a promising new target for drug discovery.
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Affiliation(s)
- Guiyi Li
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Manuel G Forero
- Facultad de Ingeniería, Universidad de Ibagué, Ibagué, Colombia
| | - Jill S Wentzell
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Ilgim Durmus
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Reinhard Wolf
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Niki C Anthoney
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Mieczyslaw Parker
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Ruiying Jiang
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Jacob Hasenauer
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Nicholas James Strausfeld
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Neuroscience, University of Arizona College of Science, Tucson, United States
| | - Martin Heisenberg
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Alicia Hidalgo
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
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10
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Maier D, Nagel AC, Preiss A. Genetic interactions between Protein Kinase D and Lobe mutants during eye development of Drosophila melanogaster. Hereditas 2019; 156:37. [PMID: 31889943 PMCID: PMC6924039 DOI: 10.1186/s41065-019-0113-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 12/10/2019] [Indexed: 12/11/2022] Open
Abstract
Background In Drosophila, the development of the fly eye involves the activity of several, interconnected pathways that first define the presumptive eye field within the eye anlagen, followed by establishment of the dorso-ventral boundary, and the regulation of growth and apoptosis. In Lobe (L) mutant flies, parts of the eye or even the complete eye are absent because the eye field has not been properly defined. Manifold genetic interactions indicate that L influences the activity of several signalling pathways, resulting in a conversion of eye tissue into epidermis, and in the induction of apoptosis. As information on the molecular nature of the L mutation is lacking, the underlying molecular mechanisms are still an enigma. Results We have identified Protein Kinase D (PKD) as a strong modifier of the L mutant phenotype. PKD belongs to the PKC/CAMK class of Ser/Thr kinases that have been involved in diverse cellular processes including stress resistance and growth. Despite the many roles of PKD, Drosophila PKD null mutants are without apparent phenotype apart from sensitivity to oxidative stress. Here we report an involvement of PKD in eye development in the sensitized genetic background of Lobe. Absence of PKD strongly enhanced the dominant eye defects of heterozygous L2 flies, and decreased their viability. Moreover, eye-specific overexpression of an activated isoform of PKD considerably ameliorated the dominant L2 phenotype. This genetic interaction was not allele specific but similarly seen with three additional, weaker L alleles (L1, L5, LG), demonstrating its specificity. Conclusions We propose that PKD-mediated phosphorylation is involved in underlying processes causing the L phenotype, i.e. in the regulation of growth, the epidermal transformation of eye tissue and apoptosis, respectively.
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Affiliation(s)
- Dieter Maier
- Universität Hohenheim, Institut für Genetik (240A), Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anja C Nagel
- Universität Hohenheim, Institut für Genetik (240A), Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anette Preiss
- Universität Hohenheim, Institut für Genetik (240A), Garbenstr. 30, 70599 Stuttgart, Germany
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11
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Klann M, Seaver EC. Functional role of pax6 during eye and nervous system development in the annelid Capitella teleta. Dev Biol 2019; 456:86-103. [PMID: 31445008 DOI: 10.1016/j.ydbio.2019.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 08/16/2019] [Accepted: 08/16/2019] [Indexed: 12/18/2022]
Abstract
The transcription factor Pax6 is an important regulator of early animal development. Loss of function mutations of pax6 in a range of animals result in a reduction or complete loss of the eye, a reduction of a subset of neurons, and defects in axon growth. There are no studies focusing on the role of pax6 during development of any lophotrochozoan representative, however, expression of pax6 in the developing eye and nervous system in a number of species suggest that pax6 plays a highly conserved role in eye and nervous system formation. We investigated the functional role of pax6 during development of the marine annelid Capitella teleta. Expression of pax6 transcripts in C. teleta larvae is similar to patterns found in other animals, with distinct subdomains in the brain and ventral nerve cord as well as in the larval and juvenile eye. To perturb pax6 function, two different splice-blocking morpholinos and a translation-blocking morpholino were used. Larvae resulting from microinjections with either splice-blocking morpholino show a reduction of the pax6 transcript. Development of both the larval eyes and the central nervous system architecture are highly disrupted following microinjection of each of the three morpholinos. The less severe phenotype observed when only the homeodomain is disrupted suggests that presence of the paired domain is sufficient for partial function of the Pax6 protein. Preliminary downstream target analysis confirms disruption in expression of some components of the retinal gene regulatory network, as well as disruption of genes involved in nervous system development. Results from this study, taken together with studies from other species, reveal an evolutionarily conserved role for pax6 in eye and neural specification and development.
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Affiliation(s)
- Marleen Klann
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St. Augustine, Fl, 32080, USA
| | - Elaine C Seaver
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St. Augustine, Fl, 32080, USA.
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12
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Abdusselamoglu MD, Eroglu E, Burkard TR, Knoblich JA. The transcription factor odd-paired regulates temporal identity in transit-amplifying neural progenitors via an incoherent feed-forward loop. eLife 2019; 8:46566. [PMID: 31329099 PMCID: PMC6645715 DOI: 10.7554/elife.46566] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 06/12/2019] [Indexed: 11/13/2022] Open
Abstract
Neural progenitors undergo temporal patterning to generate diverse neurons in a chronological order. This process is well-studied in the developing Drosophila brain and conserved in mammals. During larval stages, intermediate neural progenitors (INPs) serially express Dichaete (D), grainyhead (Grh) and eyeless (Ey/Pax6), but how the transitions are regulated is not precisely understood. Here, we developed a method to isolate transcriptomes of INPs in their distinct temporal states to identify a complete set of temporal patterning factors. Our analysis identifies odd-paired (opa), as a key regulator of temporal patterning. Temporal patterning is initiated when the SWI/SNF complex component Osa induces D and its repressor Opa at the same time but with distinct kinetics. Then, high Opa levels repress D to allow Grh transcription and progress to the next temporal state. We propose that Osa and its target genes opa and D form an incoherent feedforward loop (FFL) and a new mechanism allowing the successive expression of temporal identities. The brain consists of billions of neurons that come in a range of shapes and sizes, with different types of neurons specialized to perform different tasks. Despite their diversity, all of these neurons originate from a single population known as neural stem cells. As the brain develops, each neural stem cell divides to produce two daughter cells: one remains a stem cell, which can then divide again, and the other becomes a neuron. A longstanding question in developmental biology is how a limited pool of neural stem cells can generate so many different types of neurons. The answer seems to lie in a process known as temporal identity, whereby neural stem cells of different ages give rise to different types of neurons. This requires neural stem cells to keep track of their own age, but it is still unclear how they can do so. Abdusselamoglu et al. have now uncovered part of the underlying mechanism behind temporal identity by studying fruit flies, an insect in which the early stages of brain development are similar to the ones in mammals. A method was developed to sort fly neural stem cells into groups based on their age. Comparing these groups revealed that a protein called Opa make neural stem cells switch from being 'young' to being 'middle-aged'. Another protein, Osa activates Opa, which in turn represses a protein called Dichaete. As Dichaete is mainly active in young neural stem cells, the actions of Osa and Opa push neural stem cells into middle age. Fruit flies are therefore a valuable system with which to study the mechanisms that regulate neural stem cell aging. Revealing how the brain generates different types of neurons could help us study the way these cells organize themselves into complex circuits. This knowledge could then be harnessed to understand how these processes go wrong and disrupt development.
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Affiliation(s)
- Merve Deniz Abdusselamoglu
- IMBA - Institute of Molecular Biotechnology of the Austrian Academy of Science, Vienna Biocenter (VBC), Vienna, Austria
| | - Elif Eroglu
- IMBA - Institute of Molecular Biotechnology of the Austrian Academy of Science, Vienna Biocenter (VBC), Vienna, Austria
| | - Thomas R Burkard
- IMBA - Institute of Molecular Biotechnology of the Austrian Academy of Science, Vienna Biocenter (VBC), Vienna, Austria
| | - Jürgen A Knoblich
- IMBA - Institute of Molecular Biotechnology of the Austrian Academy of Science, Vienna Biocenter (VBC), Vienna, Austria
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13
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Bridi JC, Ludlow ZN, Hirth F. Lineage-specific determination of ring neuron circuitry in the central complex of Drosophila. Biol Open 2019; 8:bio.045062. [PMID: 31285267 PMCID: PMC6679397 DOI: 10.1242/bio.045062] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The ellipsoid body (EB) of the Drosophila central complex mediates sensorimotor integration and action selection for adaptive behaviours. Insights into its physiological function are steadily accumulating, however the developmental origin and genetic specification have remained largely elusive. Here we identify two stem cells in the embryonic neuroectoderm as precursor cells of neuronal progeny that establish EB circuits in the adult brain. Genetic tracing of embryonic neuroblasts ppd5 and mosaic analysis with a repressible cell marker identified lineage-related progeny as Pox neuro (Poxn)-expressing EB ring neurons, R1-R4. During embryonic brain development, engrailed function is required for the initial formation of Poxn-expressing ppd5-derived progeny. Postembryonic determination of R1-R4 identity depends on lineage-specific Poxn function that separates neuronal subtypes of ppd5-derived progeny into hemi-lineages with projections either terminating in the EB ring neuropil or the superior protocerebrum (SP). Poxn knockdown in ppd5-derived progeny results in identity transformation of engrailed-expressing hemi-lineages from SP to EB-specific circuits. In contrast, lineage-specific knockdown of engrailed leads to reduced numbers of Poxn-expressing ring neurons. These findings establish neuroblasts ppd5-derived ring neurons as lineage-related sister cells that require engrailed and Poxn function for the proper formation of EB circuitry in the adult central complex of Drosophila.
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Affiliation(s)
- Jessika C Bridi
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RX, United Kingdom
| | - Zoe N Ludlow
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RX, United Kingdom
| | - Frank Hirth
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RX, United Kingdom
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14
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Rosen H, Sharf R, Pechkovsky A, Salzberg A, Kleinberger T. Selective elimination of cancer cells by the adenovirus E4orf4 protein in a Drosophila cancer model: a new paradigm for cancer therapy. Cell Death Dis 2019; 10:455. [PMID: 31186403 PMCID: PMC6560070 DOI: 10.1038/s41419-019-1680-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 05/08/2019] [Accepted: 05/16/2019] [Indexed: 01/16/2023]
Abstract
The adenovirus (Ad) E4orf4 protein contributes to efficient progression of virus infection. When expressed alone E4orf4 induces p53- and caspase-independent cell-death, which is more effective in cancer cells than in normal cells in tissue culture. Cancer selectivity of E4orf4-induced cell-death may result from interference with various regulatory pathways that cancer cells are more dependent on, including DNA damage signaling and proliferation control. E4orf4 signaling is conserved in several organisms, including yeast, Drosophila, and mammalian cells, indicating that E4orf4-induced cell-death can be investigated in these model organisms. The Drosophila genetic model system has contributed significantly to the study of cancer and to identification of novel cancer therapeutics. Here, we used the fly model to investigate the ability of E4orf4 to eliminate cancer tissues in a whole organism with minimal damage to normal tissues. We show that E4orf4 dramatically inhibited tumorigenesis and rescued survival of flies carrying a variety of tumors, including highly aggressive and metastatic tumors in the fly brain and eye discs. Moreover, E4orf4 rescued the morphology of adult eyes containing scrib- cancer clones even when expressed at a much later stage than scrib elimination. The E4orf4 partner protein phosphatase 2A (PP2A) was required for inhibition of tumorigenesis by E4orf4 in the system described here, whereas another E4orf4 partner, Src kinase, provided only minimal contribution to this process. Our results suggest that E4orf4 is an effective anticancer agent and reveal a promising potential for E4orf4-based cancer treatments.
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Affiliation(s)
- Helit Rosen
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Rakefet Sharf
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Antonina Pechkovsky
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel.,Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Tamar Kleinberger
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel.
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15
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Tian K, Henderson RE, Parker R, Brown A, Johnson JE, Bateman JR. Two modes of transvection at the eyes absent gene of Drosophila demonstrate plasticity in transcriptional regulatory interactions in cis and in trans. PLoS Genet 2019; 15:e1008152. [PMID: 31075100 PMCID: PMC6530868 DOI: 10.1371/journal.pgen.1008152] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/22/2019] [Accepted: 04/23/2019] [Indexed: 01/10/2023] Open
Abstract
For many genes, proper gene expression requires coordinated and dynamic interactions between multiple regulatory elements, each of which can either promote or silence transcription. In Drosophila, the complexity of the regulatory landscape is further complicated by the tight physical pairing of homologous chromosomes, which can permit regulatory elements to interact in trans, a phenomenon known as transvection. To better understand how gene expression can be programmed through cis- and trans-regulatory interactions, we analyzed transvection effects for a collection of alleles of the eyes absent (eya) gene. We find that trans-activation of a promoter by the eya eye-specific enhancers is broadly supported in many allelic backgrounds, and that the availability of an enhancer to act in trans can be predicted based on the molecular lesion of an eya allele. Furthermore, by manipulating promoter availability in cis and in trans, we demonstrate that the eye-specific enhancers of eya show plasticity in their promoter preference between two different transcriptional start sites, which depends on promoter competition between the two potential targets. Finally, we show that certain alleles of eya demonstrate pairing-sensitive silencing resulting from trans-interactions between Polycomb Response Elements (PREs), and genetic and genomic data support a general role for PcG proteins in mediating transcriptional silencing at eya. Overall, our data highlight how eya gene regulation relies upon a complex but plastic interplay between multiple enhancers, promoters, and PREs. Gene regulation requires interactions between regions of DNA known as regulatory elements, which, in combination, determine where and when a gene will be active or silenced. Some genes use just a few regulatory elements, whereas others rely on highly complex interactions between many different elements that are poorly understood. While we typically imagine regulatory elements interacting with one another along the length of a single chromosome, in a curious phenomenon called transvection, elements can communicate between two different chromosomes that are held in close proximity. Here, we use the study of transvection to better understand how different regulatory elements contribute to the expression of eyes absent (eya), a gene required for proper eye development in Drosophila. Our data show that a class of elements that initiate eya gene expression, called promoters, will compete with one another for activation by eya’s enhancers, a second class of regulatory element, with the promoter that is closest to the enhancers being the favored target for activation. Furthermore, our study of transvection uncovers an important role for a silencing element, called a PRE, in opposing eya gene expression. Overall, our study sheds new light on how different elements combine to produce patterned expression of eya.
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Affiliation(s)
- Katherine Tian
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Rachel E. Henderson
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Reyna Parker
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Alexia Brown
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Justine E. Johnson
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Jack R. Bateman
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
- * E-mail:
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16
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E93 Integrates Neuroblast Intrinsic State with Developmental Time to Terminate MB Neurogenesis via Autophagy. Curr Biol 2019; 29:750-762.e3. [PMID: 30773368 DOI: 10.1016/j.cub.2019.01.039] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/05/2018] [Accepted: 01/14/2019] [Indexed: 12/17/2022]
Abstract
Most neurogenesis occurs during development, driven by the cell divisions of neural stem cells (NSCs). We use Drosophila to understand how neurogenesis terminates once development is complete, a process critical for neural circuit formation. We identified E93, a steroid-hormone-induced transcription factor that downregulates phosphatidylinositol 3-kinase (PI3K) levels to activate autophagy for elimination of mushroom body (MB) neuroblasts. MB neuroblasts are a subset of Drosophila NSCs that generate neurons important for memory and learning. MB neurogenesis extends into adulthood when E93 is reduced and terminates prematurely when E93 is overexpressed. E93 is expressed in MB neuroblasts during later stages of pupal development only, which includes the time when MB neuroblasts normally terminate their divisions. Cell intrinsic Imp and Syp temporal factors regulate timing of E93 expression in MB neuroblasts, and extrinsic steroid hormone receptor (EcR) activation boosts E93 levels high for termination. Imp inhibits premature expression of E93 in a Syp-dependent manner, and Syp positively regulates E93 to promote neurogenesis termination. Imp and Syp together with E93 form a temporal cassette, which consequently links early developmental neurogenesis with termination. Altogether, E93 functions as a late-acting temporal factor integrating extrinsic hormonal cues linked to developmental timing with neuroblast intrinsic temporal cues to precisely time neurogenesis ending during development.
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17
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Scalloped a member of the Hippo tumor suppressor pathway controls mushroom body size in Drosophila brain by non-canonical regulation of neuroblast proliferation. Dev Biol 2017; 432:203-214. [DOI: 10.1016/j.ydbio.2017.10.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 10/16/2017] [Accepted: 10/20/2017] [Indexed: 01/18/2023]
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18
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RNAi-Mediated Reverse Genetic Screen Identified Drosophila Chaperones Regulating Eye and Neuromuscular Junction Morphology. G3-GENES GENOMES GENETICS 2017; 7:2023-2038. [PMID: 28500055 PMCID: PMC5499113 DOI: 10.1534/g3.117.041632] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Accumulation of toxic proteins in neurons has been linked with the onset of neurodegenerative diseases, which in many cases are characterized by altered neuronal function and synapse loss. Molecular chaperones help protein folding and the resolubilization of unfolded proteins, thereby reducing the protein aggregation stress. While most of the chaperones are expressed in neurons, their functional relevance remains largely unknown. Here, using bioinformatics analysis, we identified 95 Drosophila chaperones and classified them into seven different classes. Ubiquitous actin5C-Gal4-mediated RNAi knockdown revealed that ∼50% of the chaperones are essential in Drosophila Knocking down these genes in eyes revealed that ∼30% of the essential chaperones are crucial for eye development. Using neuron-specific knockdown, immunocytochemistry, and robust behavioral assays, we identified a new set of chaperones that play critical roles in the regulation of Drosophila NMJ structural organization. Together, our data present the first classification and comprehensive analysis of Drosophila chaperones. Our screen identified a new set of chaperones that regulate eye and NMJ morphogenesis. The outcome of the screen reported here provides a useful resource for further elucidating the role of individual chaperones in Drosophila eye morphogenesis and synaptic development.
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19
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Kraft KF, Massey EM, Kolb D, Walldorf U, Urbach R. Retinal homeobox promotes cell growth, proliferation and survival of mushroom body neuroblasts in the Drosophila brain. Mech Dev 2016; 142:50-61. [PMID: 27455861 DOI: 10.1016/j.mod.2016.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/14/2016] [Accepted: 07/18/2016] [Indexed: 12/29/2022]
Abstract
The Drosophila mushroom bodies, centers of olfactory learning and memory in the fly 'forebrain', develop from a set of neural stem cells (neuroblasts) that generate a large number of Kenyon cells (KCs) during sustained cell divisions from embryonic to late pupal stage. We show that retinal homeobox (rx), encoding for an evolutionarily conserved transcription factor, is required for proper development of the mushroom bodies. Throughout development rx is expressed in mushroom body neuroblasts (MBNBs), their ganglion mother cells (MB-GMCs) and young KCs. In the absence of rx function, MBNBs form correctly but exhibit a reduction in cell size and mitotic activity, whereas overexpression of rx increases growth of MBNBs. These data suggest that Rx is involved in the control of MBNB growth and proliferation. Rx also promotes cell cycling of MB-GMCs. Moreover, we show that Rx is important for the survival of MBNBs and Kenyon cells which undergo premature cell death in the absence of rx function. Simultaneous blocking of cell death restores the normal set of MBNBs and part of the KCs, demonstrating that both, impaired proliferation and premature cell death (of MBNBs and KCs) account for the observed defects in mushroom body development. We then show that Rx controls proliferation within the MBNB clones independently of Tailless (Tll) and Prospero (Pros), and does not regulate the expression of other key regulators of MB development, Eyeless (Ey) and Dachshund (Dac). Our data support that the role of Rx in forebrain development is conserved between vertebrates and fly.
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Affiliation(s)
- Karoline F Kraft
- Institute of Genetics, University of Mainz, D-55099 Mainz, Germany
| | - Eva M Massey
- Institute of Genetics, University of Mainz, D-55099 Mainz, Germany
| | - Dieter Kolb
- Institute of Developmental Biology, Saarland University, D-66421 Homburg/Saar, Germany
| | - Uwe Walldorf
- Institute of Developmental Biology, Saarland University, D-66421 Homburg/Saar, Germany
| | - Rolf Urbach
- Institute of Genetics, University of Mainz, D-55099 Mainz, Germany.
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20
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Cattenoz PB, Giangrande A. Revisiting the role of the Gcm transcription factor, from master regulator to Swiss army knife. Fly (Austin) 2016; 10:210-8. [PMID: 27434165 DOI: 10.1080/19336934.2016.1212793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Master genes are known to induce the differentiation of a multipotent cell into a specific cell type. These molecules are often transcription factors that switch on the regulatory cascade that triggers cell specification. Gcm was first described as the master gene of the glial fate in Drosophila as it induces the differentiation of neuroblasts into glia in the developing nervous system. Later on, Gcm was also shown to regulate the differentiation of blood, tendon and peritracheal cells as well as that of neuronal subsets. Thus, the glial master gene is used in at least 4 additional systems to promote differentiation. To understand the numerous roles of Gcm, we recently reported a genome-wide screen of Gcm direct targets in the Drosophila embryo. This screen provided new insight into the role and mode of action of this powerful transcription factor, notably on the interactions between Gcm and major differentiation pathways such as the Hedgehog, Notch and JAK/STAT. Here, we discuss the mode of action of Gcm in the different systems, we present new tissues that require Gcm and we revise the concept of 'master gene'.
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Affiliation(s)
- Pierre B Cattenoz
- a Department of Functional Genomics and Cancer , Institut de Génétique et de Biologie Moléculaire et Cellulaire , Illkirch , France
| | - Angela Giangrande
- a Department of Functional Genomics and Cancer , Institut de Génétique et de Biologie Moléculaire et Cellulaire , Illkirch , France
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21
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Boyan G, Williams L, Liu Y. Conserved patterns of axogenesis in the panarthropod brain. ARTHROPOD STRUCTURE & DEVELOPMENT 2015; 44:101-112. [PMID: 25483803 DOI: 10.1016/j.asd.2014.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 10/11/2014] [Accepted: 11/24/2014] [Indexed: 06/04/2023]
Abstract
Neuropils in the cerebral midline of Panarthropoda exhibit a wide spectrum of neuroarchitectures--from rudimentary to highly elaborated--and which at first sight defy a unifying neuroarchitectural principle. Developmental approaches have shown that in model arthropods such as insects, conserved cellular and molecular mechanisms first establish a simple axon scaffold in the brain. However, to be adapted for adult life, this immature ground plan is transformed by a developmental process--known in the grasshopper as "fascicle switching"--in which subsets of neurons systematically redirect their growth cones at stereotypic locations across the brain midline. A topographic system of choice points along the transverse brain axis where axons decussate features in all panarthropods studied even though different modes of neurogenesis and varying degrees of neuropilar elaboration are involved. This suggests that the molecular mechanisms regulating choice point selection may be conserved. In combination with recent cladistic interpretations of arthropod phylogeny based on nuclear protein-coding sequences the data argue for this topographic decussation as having evolved early and being a conserved feature of the Panarthropoda. Differences in elaboration likely reflect both the extent to which neuropilar reorganization has progressed during development and the lifestyle of the individual organism.
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Affiliation(s)
- George Boyan
- Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
| | - Leslie Williams
- Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Yu Liu
- Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
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22
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Luan Q, Chen Q, Friedrich M. The Pax6 genes eyeless and twin of eyeless are required for global patterning of the ocular segment in the Tribolium embryo. Dev Biol 2014; 394:367-81. [PMID: 25149513 DOI: 10.1016/j.ydbio.2014.08.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 06/23/2014] [Accepted: 08/06/2014] [Indexed: 01/08/2023]
Abstract
The transcription factor gene Pax6 is widely considered a master regulator of eye development in bilaterian animals. However, the existence of visual organs that develop without Pax6 input and the considerable pleiotropy of Pax6 outside the visual system dictate further studies into defining ancestral functions of this important regulator. Previous work has shown that the combinatorial knockdown of the insect Pax6 orthologs eyeless (ey) and twin of eyeless (toy) perturbs the development of the visual system but also other areas of the larval head in the red flour beetle Tribolium castaneum. To elucidate the role of Pax6 during Tribolium head development in more detail, we studied head cuticle morphology, brain anatomy, embryonic head morphogenesis, and developmental marker gene expression in combinatorial ey and toy knockdown animals. Our experiments reveal that Pax6 is broadly required for patterning the anterior embryonic head. One of the earliest detectable roles is the formation of the embryonic head lobes, which originate from within the ocular segment and give rise to large parts of the supraesophageal brain including the mushroom body, a part of the posterior head capsule cuticle, and the visual system. We present further evidence that toy continues to be required for the development of the larval eyes after formation of the embryonic head lobes in cooperation with the eye developmental transcription factor dachshund (dac). The sum of our findings suggests that Pax6 functions as a competence factor throughout the development of the insect ocular segment. Comparative evidence identifies this function as an ancestral aspect of bilaterian head development.
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Affiliation(s)
- Qing Luan
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA; Institute of Molecular Biology and Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403, USA
| | - Qing Chen
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA
| | - Markus Friedrich
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA; Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA.
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23
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Glossop NRJ, Gummadova JO, Ghangrekar I, Hardin PE, Coutts GA. Effects of TWIN-OF-EYELESS on Clock Gene Expression and Central-Pacemaker Neuron Development in Drosophila. J Biol Rhythms 2014; 29:151-166. [PMID: 24916389 PMCID: PMC4262727 DOI: 10.1177/0748730414534819] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Circadian oscillators are autonomous molecular rhythms that reside in cells to align whole-organism physiology and behavior to the 24-h day. In flies, as in mammals, the oscillator operates in cells that coexpress CLOCK (CLK) and CYCLE (CYC). Recent work in Drosophila has shown that CLK is unique in its ability to generate heterologous oscillators, indicating that Clk gene expression defines the circadian cell fate. Here, using standard in vitro and in vivo techniques, we show that TWIN-OF-EYELESS (TOY; dPax6) regulates Clk expression in small ventrolateral neurons (s-LNvs) that coordinate sleep-wake cycles. Crucially, toy binds multiple sites at the Clk locus, is expressed independent of CLK-CYC in LNvs, regulates CLK protein levels under optimal photoperiodic conditions, and sets clock-speed during endogenous free-run. Furthermore, TOY is necessary for the onset of Clk expression in LNvs during embryogenesis. We propose that TOY contributes to a transcription complex that functions upstream of the oscillator to promote Clk expression in s-LNvs.
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Affiliation(s)
| | | | - Indrayani Ghangrekar
- Faculty of Life Sciences, University of Manchester, Manchester, UK Cancer Research UK, London, UK
| | | | - Graham A Coutts
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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24
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unfulfilled interacting genes display branch-specific roles in the development of mushroom body axons in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2014; 4:693-706. [PMID: 24558265 PMCID: PMC4577660 DOI: 10.1534/g3.113.009829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The mushroom body (MB) of Drosophila melanogaster is an organized collection of interneurons that is required for learning and memory. Each of the three subtypes of MB neurons, γ, α´/β´, and α/β, branch at some point during their development, providing an excellent model in which to study the genetic regulation of axon branching. Given the sequential birth order and the unique patterning of MB neurons, it is likely that specific gene cascades are required for the different guidance events that form the characteristic lobes of the MB. The nuclear receptor UNFULFILLED (UNF), a transcription factor, is required for the differentiation of all MB neurons. We have developed and used a classical genetic suppressor screen that takes advantage of the fact that ectopic expression of unf causes lethality to identify candidate genes that act downstream of UNF. We hypothesized that reducing the copy number of unf-interacting genes will suppress the unf-induced lethality. We have identified 19 candidate genes that when mutated suppress the unf-induced lethality. To test whether candidate genes impact MB development, we performed a secondary phenotypic screen in which the morphologies of the MBs in animals heterozygous for unf and a specific candidate gene were analyzed. Medial MB lobes were thin, missing, or misguided dorsally in five double heterozygote combinations (;unf/+;axin/+, unf/+;Fps85D/+, ;unf/+;Tsc1/+, ;unf/+;Rheb/+, ;unf/+;msn/+). Dorsal MB lobes were missing in ;unf/+;DopR2/+ or misprojecting beyond the termination point in ;unf/+;Sytβ double heterozygotes. These data suggest that unf and unf-interacting genes play specific roles in axon development in a branch-specific manner.
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Combinatorial temporal patterning in progenitors expands neural diversity. Nature 2013; 498:449-55. [PMID: 23783519 PMCID: PMC3941985 DOI: 10.1038/nature12266] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 05/01/2013] [Indexed: 12/11/2022]
Abstract
Human outer subventricular zone (OSVZ) neural progenitors and Drosophila type II neuroblasts both generate intermediate neural progenitors (INPs) that populate the adult cerebral cortex or central complex, respectively. It is unknown whether INPs simply expand or also diversify neural cell types. Here we show that Drosophila INPs sequentially generate distinct neural subtypes; that INPs sequentially express Dichaete>Grainyhead>Eyeless transcription factors; and that these transcription factors are required for the production of distinct neural subtypes. Moreover, parental type II neuroblasts also sequentially express transcription factors and generate different neuronal/glial progeny over time, providing a second temporal identity axis. We conclude that neuroblast and INP temporal patterning axes act combinatorially to generate increased neural diversity within adult central complex; OSVZ progenitors may use similar mechanisms to increase neural diversity in the human brain.
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Strausfeld NJ, Hirth F. Deep homology of arthropod central complex and vertebrate basal ganglia. Science 2013; 340:157-61. [PMID: 23580521 DOI: 10.1126/science.1231828] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The arthropod central complex and vertebrate basal ganglia derive from embryonic basal forebrain lineages that are specified by an evolutionarily conserved genetic program leading to interconnected neuropils and nuclei that populate the midline of the forebrain-midbrain boundary region. In the substructures of both the central complex and basal ganglia, network connectivity and neuronal activity mediate control mechanisms in which inhibitory (GABAergic) and modulatory (dopaminergic) circuits facilitate the regulation and release of adaptive behaviors. Both basal ganglia and central complex dysfunction result in behavioral defects including motor abnormalities, impaired memory formation, attention deficits, affective disorders, and sleep disturbances. The observed multitude of similarities suggests deep homology of arthropod central complex and vertebrate basal ganglia circuitries underlying the selection and maintenance of behavioral actions.
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Affiliation(s)
- Nicholas J Strausfeld
- Department of Neuroscience, School of Mind, Brain and Behavior, University of Arizona, Tucson, AZ 85721, USA.
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Nfonsam LE, Cano C, Mudge J, Schilkey FD, Curtiss J. Analysis of the transcriptomes downstream of Eyeless and the Hedgehog, Decapentaplegic and Notch signaling pathways in Drosophila melanogaster. PLoS One 2012; 7:e44583. [PMID: 22952997 PMCID: PMC3432130 DOI: 10.1371/journal.pone.0044583] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 08/09/2012] [Indexed: 01/22/2023] Open
Abstract
Tissue-specific transcription factors are thought to cooperate with signaling pathways to promote patterned tissue specification, in part by co-regulating transcription. The Drosophila melanogaster Pax6 homolog Eyeless forms a complex, incompletely understood regulatory network with the Hedgehog, Decapentaplegic and Notch signaling pathways to control eye-specific gene expression. We report a combinatorial approach, including mRNAseq and microarray analyses, to identify targets co-regulated by Eyeless and Hedgehog, Decapentaplegic or Notch. Multiple analyses suggest that the transcriptomes resulting from co-misexpression of Eyeless+signaling factors provide a more complete picture of eye development compared to previous efforts involving Eyeless alone: (1) Principal components analysis and two-way hierarchical clustering revealed that the Eyeless+signaling factor transcriptomes are closer to the eye control transcriptome than when Eyeless is misexpressed alone; (2) more genes are upregulated at least three-fold in response to Eyeless+signaling factors compared to Eyeless alone; (3) based on gene ontology analysis, the genes upregulated in response to Eyeless+signaling factors had a greater diversity of functions compared to Eyeless alone. Through a secondary screen that utilized RNA interference, we show that the predicted gene CG4721 has a role in eye development. CG4721 encodes a neprilysin family metalloprotease that is highly up-regulated in response to Eyeless+Notch, confirming the validity of our approach. Given the similarity between D. melanogaster and vertebrate eye development, the large number of novel genes identified as potential targets of Ey+signaling factors will provide novel insights to our understanding of eye development in D. melanogaster and humans.
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Affiliation(s)
- Landry E. Nfonsam
- Department of Biology, New Mexico State University, Las Cruces, New Mexico, United States of America
| | - Carlos Cano
- Department of Biology, New Mexico State University, Las Cruces, New Mexico, United States of America
| | - Joann Mudge
- National Center for Genome Resources, Santa Fe, New Mexico, United States of America
| | - Faye D. Schilkey
- National Center for Genome Resources, Santa Fe, New Mexico, United States of America
| | - Jennifer Curtiss
- Department of Biology, New Mexico State University, Las Cruces, New Mexico, United States of America
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Colomb J, Reiter L, Blaszkiewicz J, Wessnitzer J, Brembs B. Open source tracking and analysis of adult Drosophila locomotion in Buridan's paradigm with and without visual targets. PLoS One 2012; 7:e42247. [PMID: 22912692 PMCID: PMC3415391 DOI: 10.1371/journal.pone.0042247] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 07/04/2012] [Indexed: 11/30/2022] Open
Abstract
Background Insects have been among the most widely used model systems for studying the control of locomotion by nervous systems. In Drosophila, we implemented a simple test for locomotion: in Buridan's paradigm, flies walk back and forth between two inaccessible visual targets [1]. Until today, the lack of easily accessible tools for tracking the fly position and analyzing its trajectory has probably contributed to the slow acceptance of Buridan's paradigm. Methodology/Principal Findings We present here a package of open source software designed to track a single animal walking in a homogenous environment (Buritrack) and to analyze its trajectory. The Centroid Trajectory Analysis (CeTrAn) software is coded in the open source statistics project R. It extracts eleven metrics and includes correlation analyses and a Principal Components Analysis (PCA). It was designed to be easily customized to personal requirements. In combination with inexpensive hardware, these tools can readily be used for teaching and research purposes. We demonstrate the capabilities of our package by measuring the locomotor behavior of adult Drosophila melanogaster (whose wings were clipped), either in the presence or in the absence of visual targets, and comparing the latter to different computer-generated data. The analysis of the trajectories confirms that flies are centrophobic and shows that inaccessible visual targets can alter the orientation of the flies without changing their overall patterns of activity. Conclusions/Significance Using computer generated data, the analysis software was tested, and chance values for some metrics (as well as chance value for their correlation) were set. Our results prompt the hypothesis that fixation behavior is observed only if negative phototaxis can overcome the propensity of the flies to avoid the center of the platform. Together with our companion paper, we provide new tools to promote Open Science as well as the collection and analysis of digital behavioral data.
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Affiliation(s)
- Julien Colomb
- FB Biologie, Chemie, Pharmazie, Institut für Biologie-Neurobiologie, Freie Universität Berlin, Berlin, Germany. J.C
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Henry GL, Davis FP, Picard S, Eddy SR. Cell type-specific genomics of Drosophila neurons. Nucleic Acids Res 2012; 40:9691-704. [PMID: 22855560 PMCID: PMC3479168 DOI: 10.1093/nar/gks671] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Many tools are available to analyse genomes but are often challenging to use in a cell type–specific context. We have developed a method similar to the isolation of nuclei tagged in a specific cell type (INTACT) technique [Deal,R.B. and Henikoff,S. (2010) A simple method for gene expression and chromatin profiling of individual cell types within a tissue. Dev. Cell, 18, 1030–1040; Steiner,F.A., Talbert,P.B., Kasinathan,S., Deal,R.B. and Henikoff,S. (2012) Cell-type-specific nuclei purification from whole animals for genome-wide expression and chromatin profiling. Genome Res., doi:10.1101/gr.131748.111], first developed in plants, for use in Drosophila neurons. We profile gene expression and histone modifications in Kenyon cells and octopaminergic neurons in the adult brain. In addition to recovering known gene expression differences, we also observe significant cell type–specific chromatin modifications. In particular, a small subset of differentially expressed genes exhibits a striking anti-correlation between repressive and activating histone modifications. These genes are enriched for transcription factors, recovering those known to regulate mushroom body identity and predicting analogous regulators of octopaminergic neurons. Our results suggest that applying INTACT to specific neuronal populations can illuminate the transcriptional regulatory networks that underlie neuronal cell identity.
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Affiliation(s)
- Gilbert L Henry
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
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30
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Morillo SA, Braid LR, Verheyen EM, Rebay I. Nemo phosphorylates Eyes absent and enhances output from the Eya-Sine oculis transcriptional complex during Drosophila retinal determination. Dev Biol 2012; 365:267-76. [PMID: 22394486 DOI: 10.1016/j.ydbio.2012.02.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 02/07/2012] [Accepted: 02/21/2012] [Indexed: 02/02/2023]
Abstract
The retinal determination gene network comprises a collection of transcription factors that respond to multiple signaling inputs to direct Drosophila eye development. Previous genetic studies have shown that nemo (nmo), a gene encoding a proline-directed serine/threonine kinase, can promote retinal specification through interactions with the retinal determination gene network, although the molecular point of cross-talk was not defined. Here, we report that the Nemo kinase positively and directly regulates Eyes absent (Eya). Genetic assays show that Nmo catalytic activity enhances Eya-mediated ectopic eye formation and potentiates induction of the Eya-Sine oculis (So) transcriptional targets dachshund and lozenge. Biochemical analyses demonstrate that Nmo forms a complex with and phosphorylates Eya at two consensus mitogen-activated protein kinase (MAPK) phosphorylation sites. These same sites appear crucial for Nmo-mediated activation of Eya function in vivo. Thus, we propose that Nmo phosphorylation of Eya potentiates its transactivation function to enhance transcription of Eya-So target genes during eye specification and development.
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Affiliation(s)
- Santiago A Morillo
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
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31
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Homeobox gene distal-less is required for neuronal differentiation and neurite outgrowth in the Drosophila olfactory system. Proc Natl Acad Sci U S A 2012; 109:1578-83. [PMID: 22307614 DOI: 10.1073/pnas.1016741109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vertebrate Dlx genes have been implicated in the differentiation of multiple neuronal subtypes, including cortical GABAergic interneurons, and mutations in Dlx genes have been linked to clinical conditions such as epilepsy and autism. Here we show that the single Drosophila Dlx homolog, distal-less, is required both to specify chemosensory neurons and to regulate the morphologies of their axons and dendrites. We establish that distal-less is necessary for development of the mushroom body, a brain region that processes olfactory information. These are important examples of distal-less function in an invertebrate nervous system and demonstrate that the Drosophila larval olfactory system is a powerful model in which to understand distal-less functions during neurogenesis.
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32
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Automated protein-DNA interaction screening of Drosophila regulatory elements. Nat Methods 2011; 8:1065-70. [PMID: 22037703 DOI: 10.1038/nmeth.1763] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 08/23/2011] [Indexed: 01/19/2023]
Abstract
Drosophila melanogaster has one of the best characterized metazoan genomes in terms of functionally annotated regulatory elements. To explore how these elements contribute to gene regulation, we need convenient tools to identify the proteins that bind to them. Here we describe the development and validation of a high-throughput yeast one-hybrid platform, which enables screening of DNA elements versus an array of full-length, sequence-verified clones containing over 85% of predicted Drosophila transcription factors. Using six well-characterized regulatory elements, we identified 33 transcription factor-DNA interactions of which 27 were previously unidentified. To simultaneously validate these interactions and locate the binding sites of involved transcription factors, we implemented a powerful microfluidics-based approach that enabled us to retrieve DNA-occupancy data for each transcription factor throughout the respective target DNA elements. Finally, we biologically validated several interactions and identified two new regulators of sine oculis gene expression and hence eye development.
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Datta RR, Cruickshank T, Kumar JP. Differential selection within the Drosophila retinal determination network and evidence for functional divergence between paralog pairs. Evol Dev 2011; 13:58-71. [PMID: 21210943 DOI: 10.1111/j.1525-142x.2010.00456.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The retinal determination (RD) network in Drosophila comprises 14 known nuclear proteins that include DNA-binding proteins, transcriptional coactivators, kinases, and phosphatases. The composition of the network varies considerably throughout the animal kingdom, with the network in several basal insects having fewer members and with vertebrates having potentially significantly higher numbers of RD genes. One important contributing factor for the variation in gene number within the network is gene duplication. For example, 10 members of the RD network in Drosophila are derived from duplication events. Here we present an analysis of the coding regions of the five pairs of duplicate genes from within the RD network of several different Drosophila species. We demonstrate that there is differential selection across the coding regions of all RD genes. Additionally, some of the most significant differences in ratios of non-silent-to-silent site substitutions (d(N)/d(S)) between paralog pairs are found within regions that have no ascribed function. Previous structure/function analyses of several duplicate genes have identified areas within one gene that contain novel activities when compared with its paralog. The evolutionary analysis presented here identifies these same areas in the paralogs as being under high levels of relaxed selection. We suggest that sequence divergence between paralogs and selection signatures can be used as a reasonable predictor of functional changes in rapidly evolving motifs.
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Affiliation(s)
- Rhea R Datta
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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34
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Hoang CQ, Burnett ME, Curtiss J. Drosophila CtBP regulates proliferation and differentiation of eye precursors and complexes with Eyeless, Dachshund, Dan, and Danr during eye and antennal development. Dev Dyn 2011; 239:2367-85. [PMID: 20730908 DOI: 10.1002/dvdy.22380] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Specification factors regulate cell fate in part by interacting with transcriptional co-regulators like CtBP to regulate gene expression. Here, we demonstrate that CtBP forms a complex or complexes with the Drosophila melanogaster Pax6 homolog Eyeless (Ey), and with Distal antenna (Dan), Distal antenna related (Danr), and Dachshund to promote eye and antennal specification. Phenotypic analysis together with molecular data indicate that CtBP interacts with Ey to prevent overproliferation of eye precursors. In contrast, CtBP,dan,danr triple mutant adult eyes have significantly fewer ommatidia than CtBP single or dan,danr double mutants, suggesting that the CtBP/Dan/Danr complex functions to recruit ommatidia from the eye precursor pool. Furthermore, CtBP single and to a greater extent CtBP,dan,danr triple mutants affect the establishment and maintenance of the R8 precursor, which is the founding ommatidial cell. Thus, CtBP interacts with different eye specification factors to regulate gene expression appropriate for proliferative vs. differentiative stages of eye development.
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Affiliation(s)
- Chinh Q Hoang
- Department of Biology, New Mexico State University, Las Cruces, New Mexico, USA
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35
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Abstract
Selector proteins are transcription factors that coordinate the formation and identity of organs and appendages. The proper formation of these tissues requires the selector proteins to regulate the expression of a large set of genes. Many selector proteins are involved in regulating multiple developmental processes, yet it is not completely clear how they are able to activate different sets of genes in a tissue-specific manner. An association with cofactors is thought to be one method by which enhancer selectivity is achieved. During wing development the selector protein Scalloped (SD) interacts with the cofactor Vestigial (VG). This interaction leads to the activation of a specific set of downstream wing genes. Herein, data are presented indicating that the switch in binding selectivity is likely achieved by VG altering the general affinity that the SD protein has for DNA. The decreased affinity for DNA is compensated for by the fact that the VG protein forms a complex containing two SD proteins. These two properties ensure that the SD–VG complex is able to bind only to enhancers that have two consecutive binding sites. Furthermore, data are presented that indicate that the function of the two terminal domains of the VG protein is not restricted to activating transcription and promoting the recruitment of two SD proteins.
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Affiliation(s)
- A. Garg
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - J. Bell
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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Visual Targeting of Motor Actions in Climbing Drosophila. Curr Biol 2010; 20:663-8. [DOI: 10.1016/j.cub.2010.02.055] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 02/04/2010] [Accepted: 02/05/2010] [Indexed: 11/24/2022]
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Gummadova JO, Coutts GA, Glossop NRJ. Analysis of the Drosophila Clock Promoter Reveals Heterogeneity in Expression between Subgroups of Central Oscillator Cells and Identifies a Novel Enhancer Region. J Biol Rhythms 2009; 24:353-67. [DOI: 10.1177/0748730409343890] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The CLOCK-CYCLE (CLK-CYC) heterodimer lies at the heart of the circadian oscillator mechanism in Drosophila, yet little is known about the identity of transcription factors that regulate the expression of Clk and/or cyc. Here, the authors have used a transgenic approach to isolate regions of the Clk locus that are necessary for expression in central oscillator neurons in the adult fly brain. This analysis shows that central clock cells can be subdivided into 2 distinct groups based on Clk gene regulation. Expression in the lateral neuron (LN), dorsal neuron 1 anterior (DN1a) and 2 (DN2) clusters requires cis-elements located in a 122 base-pair (bp) region (–206 to –84) of the Clk promoter. Expression in the remaining dorsal neurons, 1 posterior (DN1p) and 3 (DN3) and the lateral posterior neurons (LPN), requires regulatory elements located in the –856 to –206 region. In addition, expression in photoreceptors of the compound eye is enhanced by cis-elements located in a 3rd region of the Clk locus (–1982 to –856). This region also enhances expression in nonoscillator cells in the brain including the Kenyon cells, but expression in these neurons is suppressed by regulatory sites located further upstream of –1982. The authors’ analysis reveals clear heterogeneity in Clk gene expression in the adult brain and provides a necessary focus to isolate novel transcription factors that bind at the Clk locus to regulate expression in different oscillator neuron subgroups. These results also suggest that the DN1a/DN2 neurons may have more molecular commonality with the LNs than they do with the DN1p/DN3/LPN neurons. Finally, this analysis has generated new transgenic lines that will enable genes to be misexpressed in subgroups of central oscillator cells that have previously been resistant to discrete genetic manipulation. Hence, these lines provide important new tools to facilitate a more complete dissection of the neural network that regulates output rhythms in physiology and behavior.
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Mutational analysis of the eyeless gene and phenotypic rescue reveal that an intact Eyeless protein is necessary for normal eye and brain development in Drosophila. Dev Biol 2009; 334:503-12. [PMID: 19666017 DOI: 10.1016/j.ydbio.2009.08.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 07/28/2009] [Accepted: 08/03/2009] [Indexed: 11/20/2022]
Abstract
Pax6 genes encode evolutionarily highly conserved transcription factors that are required for eye and brain development. Despite the characterization of mutations in Pax6 homologs in a range of organisms, and despite functional studies, it remains unclear what the relative importance is of the various parts of the Pax6 protein. To address this, we have studied the Drosophila Pax6 homolog eyeless. Specifically, we have generated new eyeless alleles, each with single missense mutations in one of the four domains of the protein. We show that these alleles result in abnormal eye and brain development while maintaining the OK107 eyeless GAL4 activity from which they were derived. We performed in vivo functional rescue experiments by expressing in an eyeless-specific pattern Eyeless proteins in which either the paired domain, the homeodomain, or the C-terminal domain was deleted. Rescue of the eye and brain phenotypes was only observed when full-length Eyeless was expressed, while all deletion constructs failed to rescue. These data, along with the phenotypes observed in the four newly characterized eyeless alleles, demonstrate the requirement for an intact Eyeless protein for normal Drosophila eye and brain development. They also suggest that some endogenous functions may be obscured in ectopic expression experiments.
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Suter DM, Tirefort D, Julien S, Krause KH. A Sox1 to Pax6 switch drives neuroectoderm to radial glia progression during differentiation of mouse embryonic stem cells. Stem Cells 2009; 27:49-58. [PMID: 18832594 DOI: 10.1634/stemcells.2008-0319] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The transcription factors Sox1 and Pax6 are expressed sequentially during early mouse embryonic neurogenesis. Sox1 expression starts upon formation of neuroectoderm, whereas Pax6 is subsequently expressed in radial glial cells, the latter giving rise to most neurons of the cerebral cortex. Here we used mouse embryonic stem (ES) cells to study the role of Sox1 and Pax6 in regulating differentiation of neural progenitors. For this purpose, we investigated the effect of overexpression and knockdown of Sox1 and Pax6, using three differentiation protocols. We show that (a) expression of Sox1 or Pax6 in uncommitted ES cells favored neuroectodermal lineage choice; (b) continuous Sox1 expression maintained cells at the neuroepithelial stage and prevented expression of Pax6 and other radial glial cell markers; (c) Sox1 knockdown facilitated exit from the progenitor stage, whereas Pax6 knockdown decreased formation of radial glia; (d) forced Pax6 expression in neuroepithelial cells triggered their differentiation into radial glia and neurons; and (e) Pax6 expression induced cell migration, a feature typical of radial glia-derived early neurons. We conclude that Sox1 enhances neuroectodermal commitment and maintenance but blocks further differentiation. In contrast, Pax6 is involved in the progression of neuroectoderm toward radial glia.
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Affiliation(s)
- David M Suter
- Department of Pathology and Immunology, University of Geneva Medical School, Switzerland
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Kurusu M, Maruyama Y, Adachi Y, Okabe M, Suzuki E, Furukubo-Tokunaga K. A conserved nuclear receptor, Tailless, is required for efficient proliferation and prolonged maintenance of mushroom body progenitors in the Drosophila brain. Dev Biol 2008; 326:224-36. [PMID: 19084514 DOI: 10.1016/j.ydbio.2008.11.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 10/25/2008] [Accepted: 11/17/2008] [Indexed: 12/25/2022]
Abstract
The intrinsic neurons of mushroom bodies (MBs), centers of olfactory learning in the Drosophila brain, are generated by a specific set of neuroblasts (Nbs) that are born in the embryonic stage and exhibit uninterrupted proliferation till the end of the pupal stage. Whereas MB provides a unique model to study proliferation of neural progenitors, the underlying mechanism that controls persistent activity of MB-Nbs is poorly understood. Here we show that Tailless (TLL), a conserved orphan nuclear receptor, is required for optimum proliferation activity and prolonged maintenance of MB-Nbs and ganglion mother cells (GMCs). Mutations of tll progressively impair cell cycle in MB-Nbs and cause premature loss of MB-Nbs in the early pupal stage. TLL is also expressed in MB-GMCs to prevent apoptosis and promote cell cycling. In addition, we show that ectopic expression of tll leads to brain tumors, in which Prospero, a key regulator of progenitor proliferation and differentiation, is suppressed whereas localization of molecular components involved in asymmetric Nb division is unaffected. These results as a whole uncover a distinct regulatory mechanism of self-renewal and differentiation of the MB progenitors that is different from the mechanisms found in other progenitors.
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Affiliation(s)
- Mitsuhiko Kurusu
- Structural Biology Center, National Institute of Genetics, and Department of Genetics, The Graduate University for Advanced Studies, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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42
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Salzer CL, Kumar JP. Position dependent responses to discontinuities in the retinal determination network. Dev Biol 2008; 326:121-30. [PMID: 19061881 DOI: 10.1016/j.ydbio.2008.10.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 10/05/2008] [Accepted: 10/28/2008] [Indexed: 11/17/2022]
Abstract
The development of any cell and/or tissue is dependent upon interconnections between several signaling pathways and myriad transcription factors. It is becoming more apparent that these inputs are best studied, not as individual components, but rather as elements of a gene regulatory network. Over the last decade several networks governing the specification of single cells, individual organs and entire stages of development have been described. The current incarnations of these networks are the products of the continual addition of newly discovered genetic, molecular and biochemical interactions. However, as currently envisaged, network diagrams may not sufficiently describe the spatial and temporal dynamics that underlie developmental processes. We have conducted a developmental analysis of a sub circuit of the Drosophila retinal determination network. This sub circuit is comprised of three genes, two (sine oculis and dachshund) of which code for DNA binding proteins and one (eyes absent) that encodes a transcriptional co-activator. We demonstrate here that the nature of the regulatory relationships that exist between these three genes changes as retinal development progresses. We also demonstrate that the response of the tissue to the loss of any of these three RD genes is dependent upon the position of the mutant cells within the eye field. Depending upon its location, mutant tissue will either overproliferate itself or will signal to surrounding cells instructing them to propagate and compensate for the eventual loss through apoptosis of the mutant clone. Taken together these results suggest that the complexities of development are best appreciated when spatial and temporal information is incorporated when describing gene regulatory networks.
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Affiliation(s)
- Claire L Salzer
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Conserved role for the Drosophila Pax6 homolog Eyeless in differentiation and function of insulin-producing neurons. Proc Natl Acad Sci U S A 2008; 105:16183-8. [PMID: 18852455 DOI: 10.1073/pnas.0708330105] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insulin/insulin-like growth factor (IGF) signaling constitutes an evolutionarily conserved pathway that controls growth, energy homeostasis, and longevity. In Drosophila melanogaster, key components of this pathway are the insulin-like peptides (Dilps). The major source of Dilps is a cluster of large neurons in the brain, the insulin-producing cells (IPCs). The genetic control of IPC development and function is poorly understood. Here, we demonstrate that the Pax6 homolog Eyeless is required in the IPCs to control their differentiation and function. Loss of eyeless results in phenotypes associated with loss of insulin signaling, including decreased animal size and increased carbohydrate levels in larval hemolymph. We show that mutations in eyeless lead to defective differentiation and morphologically abnormal IPCs. We also demonstrate that Eyeless controls IPC function by the direct transcriptional control of one of the major Dilps, dilp5. We propose that Eyeless has an evolutionarily conserved role in IPCs with remarkable similarities to the role of vertebrate Pax6 in beta cells of the pancreas.
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44
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Homberg U. Evolution of the central complex in the arthropod brain with respect to the visual system. ARTHROPOD STRUCTURE & DEVELOPMENT 2008; 37:347-362. [PMID: 18502176 DOI: 10.1016/j.asd.2008.01.008] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 12/19/2007] [Accepted: 01/03/2008] [Indexed: 05/26/2023]
Abstract
Modular midline neuropils, termed arcuate body (Chelicerata, Onychophora) or central body (Myriapoda, Crustacea, Insecta), are a prominent feature of the arthropod brain. In insects and crayfish, the central body is connected to a second midline-spanning neuropil, the protocerebral bridge. Both structures are collectively termed central complex. While some investigators have assumed that central and arcuate bodies are homologous, others have questioned this view. Stimulated by recent evidence for a role of the central complex in polarization vision and object recognition, the architectures of midline neuropils and their associations with the visual system were compared across panarthropods. In chelicerates and onychophorans, second-order neuropils subserving the median eyes are associated with the arcuate body. The central complex of decapods and insects, instead, receives indirect input from the lateral (compound) eye visual system, and connections with median eye (ocellar) projections are present. Together with other characters these data are consistent with a common origin of arcuate bodies and central complexes from an ancestral modular midline neuropil but, depending on the choice of characters, the protocerebral bridge or the central body shows closer affinity with the arcuate body. A possible common role of midline neuropils in azimuth-dependent sensory and motor tasks is discussed.
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Affiliation(s)
- Uwe Homberg
- Fachbereich Biologie, Tierphysiologie, Philipps-Universität Marburg, Karl-von-Frisch-Strass8, D-35032 Marburg, Germany.
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Kleinjan DA, Bancewicz RM, Gautier P, Dahm R, Schonthaler HB, Damante G, Seawright A, Hever AM, Yeyati PL, van Heyningen V, Coutinho P. Subfunctionalization of duplicated zebrafish pax6 genes by cis-regulatory divergence. PLoS Genet 2008; 4:e29. [PMID: 18282108 PMCID: PMC2242813 DOI: 10.1371/journal.pgen.0040029] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 12/21/2007] [Indexed: 01/22/2023] Open
Abstract
Gene duplication is a major driver of evolutionary divergence. In most vertebrates a single PAX6 gene encodes a transcription factor required for eye, brain, olfactory system, and pancreas development. In zebrafish, following a postulated whole-genome duplication event in an ancestral teleost, duplicates pax6a and pax6b jointly fulfill these roles. Mapping of the homozygously viable eye mutant sunrise identified a homeodomain missense change in pax6b, leading to loss of target binding. The mild phenotype emphasizes role-sharing between the co-orthologues. Meticulous mapping of isolated BACs identified perturbed synteny relationships around the duplicates. This highlights the functional conservation of pax6 downstream (3') control sequences, which in most vertebrates reside within the introns of a ubiquitously expressed neighbour gene, ELP4, whose pax6a-linked exons have been lost in zebrafish. Reporter transgenic studies in both mouse and zebrafish, combined with analysis of vertebrate sequence conservation, reveal loss and retention of specific cis-regulatory elements, correlating strongly with the diverged expression of co-orthologues, and providing clear evidence for evolution by subfunctionalization.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Base Sequence
- Chromosomes, Artificial, Bacterial/genetics
- Computational Biology
- DNA Primers/genetics
- Enhancer Elements, Genetic
- Evolution, Molecular
- Eye Abnormalities/embryology
- Eye Abnormalities/genetics
- Eye Proteins/genetics
- Gene Duplication
- Gene Expression Regulation, Developmental
- Genes, Homeobox
- Genes, Reporter
- Genetic Complementation Test
- Genetic Linkage
- Homeodomain Proteins/genetics
- Mice
- Mice, Transgenic
- Models, Genetic
- Molecular Sequence Data
- Mutation, Missense
- PAX6 Transcription Factor
- Paired Box Transcription Factors/genetics
- Phenotype
- Repressor Proteins/genetics
- Sequence Homology, Nucleic Acid
- Zebrafish/abnormalities
- Zebrafish/embryology
- Zebrafish/genetics
- Zebrafish Proteins/genetics
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Affiliation(s)
- Dirk A Kleinjan
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Ruth M Bancewicz
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Philippe Gautier
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Ralf Dahm
- Department of Genetics, Max-Planck Institute for Developmental Biology, Tübingen, Germany
| | - Helia B Schonthaler
- Department of Genetics, Max-Planck Institute for Developmental Biology, Tübingen, Germany
| | - Giuseppe Damante
- Department of Science and Biomedical Technology, University of Udine, Udine, Italy
| | - Anne Seawright
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Ann M Hever
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Patricia L Yeyati
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Veronica van Heyningen
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| | - Pedro Coutinho
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
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46
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Jordan KW, Carbone MA, Yamamoto A, Morgan TJ, Mackay TFC. Quantitative genomics of locomotor behavior in Drosophila melanogaster. Genome Biol 2008; 8:R172. [PMID: 17708775 PMCID: PMC2375002 DOI: 10.1186/gb-2007-8-8-r172] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 03/26/2007] [Accepted: 08/21/2007] [Indexed: 11/21/2022] Open
Abstract
The locomotor behavior of Drosophila melanogaster was quantified in a large population of inbred lines derived from a single natural population, showing that many pleiotropic genes show correlated transcriptional responses to multiple behaviors. Background Locomotion is an integral component of most animal behaviors, and many human health problems are associated with locomotor deficits. Locomotor behavior is a complex trait, with population variation attributable to many interacting loci with small effects that are sensitive to environmental conditions. However, the genetic basis of this complex behavior is largely uncharacterized. Results We quantified locomotor behavior of Drosophila melanogaster in a large population of inbred lines derived from a single natural population, and derived replicated selection lines with different levels of locomotion. Estimates of broad-sense and narrow-sense heritabilities were 0.52 and 0.16, respectively, indicating substantial non-additive genetic variance for locomotor behavior. We used whole genome expression analysis to identify 1,790 probe sets with different expression levels between the selection lines when pooled across replicates, at a false discovery rate of 0.001. The transcriptional responses to selection for locomotor, aggressive and mating behavior from the same base population were highly overlapping, but the magnitude of the expression differences between selection lines for increased and decreased levels of behavior was uncorrelated. We assessed the locomotor behavior of ten mutations in candidate genes with altered transcript abundance between selection lines, and identified seven novel genes affecting this trait. Conclusion Expression profiling of genetically divergent lines is an effective strategy for identifying genes affecting complex behaviors, and reveals that a large number of pleiotropic genes exhibit correlated transcriptional responses to multiple behaviors.
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Affiliation(s)
- Katherine W Jordan
- Department of Genetics and WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695-7614, USA
| | - Mary Anna Carbone
- Department of Genetics and WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695-7614, USA
| | - Akihiko Yamamoto
- Department of Genetics and WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695-7614, USA
| | - Theodore J Morgan
- Division of Biology, Kansas State University, Ackert Hall, Manhattan, KS 66506, USA
| | - Trudy FC Mackay
- Department of Genetics and WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695-7614, USA
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47
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Poeck B, Triphan T, Neuser K, Strauss R. Locomotor control by the central complex inDrosophila—An analysis of thetay bridge mutant. Dev Neurobiol 2008; 68:1046-58. [DOI: 10.1002/dneu.20643] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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48
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Quigley IK, Xie X, Shankland M. Hau-Pax6A expression in the central nervous system of the leech embryo. Dev Genes Evol 2007; 217:459-68. [PMID: 17508218 DOI: 10.1007/s00427-007-0156-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 04/09/2007] [Indexed: 10/23/2022]
Abstract
The leech Helobdella sp. (Austin) has two genes of the Pax6 subfamily, one of which is characterized in detail. Hau-Pax6A was expressed during embryonic development in a pattern similar to other bilaterian animals. RNA was detected in cellular precursors of the central nervous system (CNS) and in peripheral cells including a population associated with the developing eye. The CNS of the mature leech is a ventral nerve cord composed of segmental ganglia, and embryonic Hau-Pax6A expression was primarily localized to the N teloblast lineage that generates the majority of ganglionic neurons. Expression began when the ganglion primordia were four cells in length and was initially restricted to a single cell, n(s).a, whose descendants will form the ganglion's anterior edge. At later stages, the Hau-Pax6A expression pattern expanded to include additional CNS precursors, including some descendants of the O teloblast. Expression persisted through the early stages of ganglion morphogenesis but disappeared from the segmented body trunk at the time of neuronal differentiation. The timing and iterated pattern of Hau-Pax6A expression in the leech embryo suggests that this gene may play a role in the segmental patterning of CNS morphogenesis.
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Affiliation(s)
- Ian K Quigley
- Section of Molecular Cell and Developmental Biology, University of Texas at Austin, Austin, TX 78712, USA
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49
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Lichtneckert R, Bello B, Reichert H. Cell lineage-specific expression and function of the empty spiracles gene in adult brain development of Drosophila melanogaster. Development 2007; 134:1291-300. [PMID: 17314131 DOI: 10.1242/dev.02814] [Citation(s) in RCA: 13] [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
The empty spiracles (ems) gene, encoding a homeodomain transcription factor, is a member of the cephalic gap gene family that acts in early specification of the anterior neuroectoderm in the embryonic brain of Drosophila. Here we show that ems is also expressed in the mature adult brain in the lineage-restricted clonal progeny of a single neuroblast in each brain hemisphere. These ems-expressing neuronal cells are located ventral to the antennal lobes and project a fascicle to the superior medial protocerebrum. All adult-specific secondary neurons in this lineage persistently express ems during postembryonic larval development and continue to do so throughout metamorphosis and into the adult. Mosaic-based MARCM mutant analysis and genetic rescue experiments demonstrate that ems function is autonomously required for the correct number of cells in the persistently expressing adult-specific lineage. Moreover, they indicate that ems is also required cell autonomously for the formation of the correct projections in this specific lineage. This analysis of ems expression and function reveals novel and unexpected roles of a cephalic gap gene in translating lineage information into cell number control and projection specificity in an individual clonal unit of the adult brain.
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Affiliation(s)
- Robert Lichtneckert
- Biozentrum, University of Basel, Klingelbergstrasse 50, CH-4056 Basel, Switzerland.
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50
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Gabut M, Dejardin J, Tazi J, Soret J. The SR family proteins B52 and dASF/SF2 modulate development of the Drosophila visual system by regulating specific RNA targets. Mol Cell Biol 2007; 27:3087-97. [PMID: 17283056 PMCID: PMC1899935 DOI: 10.1128/mcb.01876-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deciphering the role of alternative splicing in developmental processes relies on the identification of key genes whose expression is controlled by splicing regulators throughout the growth of a whole organism. Modulating the expression levels of five SR proteins in the developing eye of Drosophila melanogaster revealed that these splicing factors induce various phenotypic alterations in eye organogenesis and also affect viability. Although the SR proteins dASF/SF2 and B52 caused defects in ommatidia structure, only B52 impaired normal axonal projections of photoreceptors and neurogenesis in visual ganglia. Microarray analyses revealed that many transcripts involved in brain organogenesis have altered splicing profiles upon both loss and gain of B52 function. Conversely, a large proportion of transcripts regulated by dASF/SF2 are involved in eye development. These differential and specific effects of SR proteins indicate that they function to confer accuracy to developmental gene expression programs by facilitating the cell lineage decisions that underline the generation of tissue identities.
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Affiliation(s)
- Mathieu Gabut
- CNRS, UMR 5535, Institut de Génétique Moléculaire de Montpellier, Montpellier F-34293, France
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