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Poole RJ, Flames N, Cochella L. Neurogenesis in Caenorhabditis elegans. Genetics 2024:iyae116. [PMID: 39167071 DOI: 10.1093/genetics/iyae116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Accepted: 06/24/2024] [Indexed: 08/23/2024] Open
Abstract
Animals rely on their nervous systems to process sensory inputs, integrate these with internal signals, and produce behavioral outputs. This is enabled by the highly specialized morphologies and functions of neurons. Neuronal cells share multiple structural and physiological features, but they also come in a large diversity of types or classes that give the nervous system its broad range of functions and plasticity. This diversity, first recognized over a century ago, spurred classification efforts based on morphology, function, and molecular criteria. Caenorhabditis elegans, with its precisely mapped nervous system at the anatomical level, an extensive molecular description of most of its neurons, and its genetic amenability, has been a prime model for understanding how neurons develop and diversify at a mechanistic level. Here, we review the gene regulatory mechanisms driving neurogenesis and the diversification of neuron classes and subclasses in C. elegans. We discuss our current understanding of the specification of neuronal progenitors and their differentiation in terms of the transcription factors involved and ensuing changes in gene expression and chromatin landscape. The central theme that has emerged is that the identity of a neuron is defined by modules of gene batteries that are under control of parallel yet interconnected regulatory mechanisms. We focus on how, to achieve these terminal identities, cells integrate information along their developmental lineages. Moreover, we discuss how neurons are diversified postembryonically in a time-, genetic sex-, and activity-dependent manner. Finally, we discuss how the understanding of neuronal development can provide insights into the evolution of neuronal diversity.
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Affiliation(s)
- Richard J Poole
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Nuria Flames
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia 46012, Spain
| | - Luisa Cochella
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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2
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Correa E, Mialon M, Cizeron M, Bessereau JL, Pinan-Lucarre B, Kratsios P. UNC-30/PITX coordinates neurotransmitter identity with postsynaptic GABA receptor clustering. Development 2024; 151:dev202733. [PMID: 39190555 PMCID: PMC11385328 DOI: 10.1242/dev.202733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 07/10/2024] [Indexed: 08/29/2024]
Abstract
Terminal selectors are transcription factors that control neuronal identity by regulating expression of key effector molecules, such as neurotransmitter biosynthesis proteins and ion channels. Whether and how terminal selectors control neuronal connectivity is poorly understood. Here, we report that UNC-30 (PITX2/3), the terminal selector of GABA nerve cord motor neurons in Caenorhabditis elegans, is required for neurotransmitter receptor clustering, a hallmark of postsynaptic differentiation. Animals lacking unc-30 or madd-4B, the short isoform of the motor neuron-secreted synapse organizer madd-4 (punctin/ADAMTSL), display severe GABA receptor type A (GABAAR) clustering defects in postsynaptic muscle cells. Mechanistically, UNC-30 acts directly to induce and maintain transcription of madd-4B and GABA biosynthesis genes (e.g. unc-25/GAD, unc-47/VGAT). Hence, UNC-30 controls GABAA receptor clustering in postsynaptic muscle cells and GABA biosynthesis in presynaptic cells, transcriptionally coordinating two crucial processes for GABA neurotransmission. Further, we uncover multiple target genes and a dual role for UNC-30 as both an activator and a repressor of gene transcription. Our findings on UNC-30 function may contribute to our molecular understanding of human conditions, such as Axenfeld-Rieger syndrome, caused by PITX2 and PITX3 gene variants.
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Affiliation(s)
- Edgar Correa
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
- Committee on Cell and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Morgane Mialon
- Melis, Universite Claude Bernard Lyon 1, CNRS UMR5284, INSERM U1314, Institut NeuroMyoGene - Faculte de Medecine et de Pharmacie, 69008 Lyon, France
| | - Mélissa Cizeron
- Melis, Universite Claude Bernard Lyon 1, CNRS UMR5284, INSERM U1314, Institut NeuroMyoGene - Faculte de Medecine et de Pharmacie, 69008 Lyon, France
| | - Jean-Louis Bessereau
- Melis, Universite Claude Bernard Lyon 1, CNRS UMR5284, INSERM U1314, Institut NeuroMyoGene - Faculte de Medecine et de Pharmacie, 69008 Lyon, France
| | - Berangere Pinan-Lucarre
- Melis, Universite Claude Bernard Lyon 1, CNRS UMR5284, INSERM U1314, Institut NeuroMyoGene - Faculte de Medecine et de Pharmacie, 69008 Lyon, France
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
- Committee on Cell and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
- University of Chicago Neuroscience Institute, Chicago, IL 60637, USA
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3
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Rathor L, Curry S, Park Y, McElroy T, Robles B, Sheng Y, Chen WW, Min K, Xiao R, Lee MH, Han SM. Mitochondrial stress in GABAergic neurons non-cell autonomously regulates organismal health and aging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.20.585932. [PMID: 38585797 PMCID: PMC10996468 DOI: 10.1101/2024.03.20.585932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Mitochondrial stress within the nervous system can trigger non-cell autonomous responses in peripheral tissues. However, the specific neurons involved and their impact on organismal aging and health have remained incompletely understood. Here, we demonstrate that mitochondrial stress in γ-aminobutyric acid-producing (GABAergic) neurons in Caenorhabditis elegans ( C. elegans ) is sufficient to significantly alter organismal lifespan, stress tolerance, and reproductive capabilities. This mitochondrial stress also leads to significant changes in mitochondrial mass, energy production, and levels of reactive oxygen species (ROS). DAF-16/FoxO activity is enhanced by GABAergic neuronal mitochondrial stress and mediates the induction of these non-cell-autonomous effects. Moreover, our findings indicate that GABA signaling operates within the same pathway as mitochondrial stress in GABAergic neurons, resulting in non-cell-autonomous alterations in organismal stress tolerance and longevity. In summary, these data suggest the crucial role of GABAergic neurons in detecting mitochondrial stress and orchestrating non-cell-autonomous changes throughout the organism.
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Correa E, Mialon M, Cizeron M, Bessereau JL, Pinan-Lucarre B, Kratsios P. UNC-30/PITX coordinates neurotransmitter identity with postsynaptic GABA receptor clustering. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580278. [PMID: 38405977 PMCID: PMC10888783 DOI: 10.1101/2024.02.14.580278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Terminal selectors are transcription factors that control neuronal identity by regulating the expression of key effector molecules, such as neurotransmitter (NT) biosynthesis proteins, ion channels and neuropeptides. Whether and how terminal selectors control neuronal connectivity is poorly understood. Here, we report that UNC-30 (PITX2/3), the terminal selector of GABA motor neuron identity in C. elegans , is required for NT receptor clustering, a hallmark of postsynaptic differentiation. Animals lacking unc-30 or madd-4B, the short isoform of the MN-secreted synapse organizer madd-4 ( Punctin/ADAMTSL ), display severe GABA receptor type A (GABA A R) clustering defects in postsynaptic muscle cells. Mechanistically, UNC-30 acts directly to induce and maintain transcription of madd-4B and GABA biosynthesis genes (e.g., unc-25/GAD , unc-47/VGAT ). Hence, UNC-30 controls GABA A R clustering on postsynaptic muscle cells and GABA biosynthesis in presynaptic cells, transcriptionally coordinating two critical processes for GABA neurotransmission. Further, we uncover multiple target genes and a dual role for UNC-30 both as an activator and repressor of gene transcription. Our findings on UNC-30 function may contribute to our molecular understanding of human conditions, such as Axenfeld-Rieger syndrome, caused by PITX2 and PITX3 gene mutations.
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Alexander KD, Ramachandran S, Biswas K, Lambert CM, Russell J, Oliver DB, Armstrong W, Rettler M, Liu S, Doitsidou M, Bénard C, Walker AK, Francis MM. The homeodomain transcriptional regulator DVE-1 directs a program for synapse elimination during circuit remodeling. Nat Commun 2023; 14:7520. [PMID: 37980357 PMCID: PMC10657367 DOI: 10.1038/s41467-023-43281-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 11/02/2023] [Indexed: 11/20/2023] Open
Abstract
The elimination of synapses during circuit remodeling is critical for brain maturation; however, the molecular mechanisms directing synapse elimination and its timing remain elusive. We show that the transcriptional regulator DVE-1, which shares homology with special AT-rich sequence-binding (SATB) family members previously implicated in human neurodevelopmental disorders, directs the elimination of juvenile synaptic inputs onto remodeling C. elegans GABAergic neurons. Juvenile acetylcholine receptor clusters and apposing presynaptic sites are eliminated during the maturation of wild-type GABAergic neurons but persist into adulthood in dve-1 mutants, producing heightened motor connectivity. DVE-1 localization to GABAergic nuclei is required for synapse elimination, consistent with DVE-1 regulation of transcription. Pathway analysis of putative DVE-1 target genes, proteasome inhibitor, and genetic experiments implicate the ubiquitin-proteasome system in synapse elimination. Together, our findings define a previously unappreciated role for a SATB family member in directing synapse elimination during circuit remodeling, likely through transcriptional regulation of protein degradation processes.
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Affiliation(s)
- Kellianne D Alexander
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Shankar Ramachandran
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Kasturi Biswas
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Christopher M Lambert
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Julia Russell
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Devyn B Oliver
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - William Armstrong
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Monika Rettler
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Samuel Liu
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Maria Doitsidou
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
| | - Claire Bénard
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Department of Biological Sciences, Université du Québec à Montréal, Quebec, Canada
| | - Amy K Walker
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Michael M Francis
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
- Program in Neuroscience, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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Mizumoto K, Jin Y, Bessereau JL. Synaptogenesis: unmasking molecular mechanisms using Caenorhabditis elegans. Genetics 2023; 223:iyac176. [PMID: 36630525 PMCID: PMC9910414 DOI: 10.1093/genetics/iyac176] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/22/2022] [Indexed: 01/13/2023] Open
Abstract
The nematode Caenorhabditis elegans is a research model organism particularly suited to the mechanistic understanding of synapse genesis in the nervous system. Armed with powerful genetics, knowledge of complete connectomics, and modern genomics, studies using C. elegans have unveiled multiple key regulators in the formation of a functional synapse. Importantly, many signaling networks display remarkable conservation throughout animals, underscoring the contributions of C. elegans research to advance the understanding of our brain. In this chapter, we will review up-to-date information of the contribution of C. elegans to the understanding of chemical synapses, from structure to molecules and to synaptic remodeling.
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Affiliation(s)
- Kota Mizumoto
- Department of Zoology, University of British Columbia, Vancouver V6T 1Z3, Canada
| | - Yishi Jin
- Department of Neurobiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Jean-Louis Bessereau
- Univ Lyon, University Claude Bernard Lyon 1, CNRS UMR 5284, INSERM U 1314, Melis, 69008 Lyon, France
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7
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Kurashina M, Wang J, Lin J, Lee KK, Johal A, Mizumoto K. Sustained expression of unc-4 homeobox gene and unc-37/Groucho in postmitotic neurons specifies the spatial organization of the cholinergic synapses in C. elegans. eLife 2021; 10:66011. [PMID: 34388088 PMCID: PMC8363302 DOI: 10.7554/elife.66011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 08/07/2021] [Indexed: 11/13/2022] Open
Abstract
Neuronal cell fate determinants establish the identities of neurons by controlling gene expression to regulate neuronal morphology and synaptic connectivity. However, it is not understood if neuronal cell fate determinants have postmitotic functions in synapse pattern formation. Here we identify a novel role for UNC-4 homeobox protein and its corepressor UNC-37/Groucho, in tiled synaptic patterning of the cholinergic motor neurons in Caenorhabditis elegans. We show that unc-4 is not required during neurogenesis but is required in the postmitotic neurons for proper synapse patterning. In contrast, unc-37 is required in both developing and postmitotic neurons. The synaptic tiling defects of unc-4 mutants are suppressed by bar-1/β-catenin mutation, which positively regulates the expression of ceh-12/HB9. Ectopic ceh-12 expression partly underlies the synaptic tiling defects of unc-4 and unc-37 mutants. Our results reveal a novel postmitotic role of neuronal cell fate determinants in synapse pattern formation through inhibiting the canonical Wnt signaling pathway.
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Affiliation(s)
- Mizuki Kurashina
- Department of Zoology, University of British Columbia, Vancouver, Canada.,Graduate Program in Cell and Developmental Biology, University of British Columbia, Vancouver, Canada
| | - Jane Wang
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Jeffrey Lin
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Kathy Kyungeun Lee
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Arpun Johal
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Kota Mizumoto
- Department of Zoology, University of British Columbia, Vancouver, Canada.,Graduate Program in Cell and Developmental Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
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8
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Miller-Fleming TW, Cuentas-Condori A, Manning L, Palumbos S, Richmond JE, Miller DM. Transcriptional Control of Parallel-Acting Pathways That Remove Specific Presynaptic Proteins in Remodeling Neurons. J Neurosci 2021; 41:5849-5866. [PMID: 34045310 PMCID: PMC8265810 DOI: 10.1523/jneurosci.0893-20.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 04/29/2021] [Accepted: 05/20/2021] [Indexed: 11/21/2022] Open
Abstract
Synapses are actively dismantled to mediate circuit refinement, but the developmental pathways that regulate synaptic disassembly are largely unknown. We have previously shown that the epithelial sodium channel ENaC/UNC-8 triggers an activity-dependent mechanism that drives the removal of presynaptic proteins liprin-α/SYD-2, Synaptobrevin/SNB-1, RAB-3, and Endophilin/UNC-57 in remodeling GABAergic neurons in Caenorhabditis elegans (Miller-Fleming et al., 2016). Here, we report that the conserved transcription factor Iroquois/IRX-1 regulates UNC-8 expression as well as an additional pathway, independent of UNC-8, that functions in parallel to dismantle functional presynaptic terminals. We show that the additional IRX-1-regulated pathway is selectively required for the removal of the presynaptic proteins, Munc13/UNC-13 and ELKS, which normally mediate synaptic vesicle (SV) fusion and neurotransmitter release. Our findings are notable because they highlight the key role of transcriptional regulation in synapse elimination during development and reveal parallel-acting pathways that coordinate synaptic disassembly by removing specific active zone proteins.SIGNIFICANCE STATEMENT Synaptic pruning is a conserved feature of developing neural circuits but the mechanisms that dismantle the presynaptic apparatus are largely unknown. We have determined that synaptic disassembly is orchestrated by parallel-acting mechanisms that target distinct components of the active zone. Thus, our finding suggests that synaptic disassembly is not accomplished by en masse destruction but depends on mechanisms that dismantle the structure in an organized process.
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Affiliation(s)
| | - Andrea Cuentas-Condori
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37212
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Sierra Palumbos
- Neuroscience Program, Vanderbilt University, Nashville, Tennessee 37212
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
| | - David M Miller
- Neuroscience Program, Vanderbilt University, Nashville, Tennessee 37212
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37212
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9
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Taylor SR, Santpere G, Weinreb A, Barrett A, Reilly MB, Xu C, Varol E, Oikonomou P, Glenwinkel L, McWhirter R, Poff A, Basavaraju M, Rafi I, Yemini E, Cook SJ, Abrams A, Vidal B, Cros C, Tavazoie S, Sestan N, Hammarlund M, Hobert O, Miller DM. Molecular topography of an entire nervous system. Cell 2021; 184:4329-4347.e23. [PMID: 34237253 DOI: 10.1016/j.cell.2021.06.023] [Citation(s) in RCA: 304] [Impact Index Per Article: 101.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/09/2021] [Accepted: 06/14/2021] [Indexed: 02/08/2023]
Abstract
We have produced gene expression profiles of all 302 neurons of the C. elegans nervous system that match the single-cell resolution of its anatomy and wiring diagram. Our results suggest that individual neuron classes can be solely identified by combinatorial expression of specific gene families. For example, each neuron class expresses distinct codes of ∼23 neuropeptide genes and ∼36 neuropeptide receptors, delineating a complex and expansive "wireless" signaling network. To demonstrate the utility of this comprehensive gene expression catalog, we used computational approaches to (1) identify cis-regulatory elements for neuron-specific gene expression and (2) reveal adhesion proteins with potential roles in process placement and synaptic specificity. Our expression data are available at https://cengen.org and can be interrogated at the web application CengenApp. We expect that this neuron-specific directory of gene expression will spur investigations of underlying mechanisms that define anatomy, connectivity, and function throughout the C. elegans nervous system.
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Affiliation(s)
- Seth R Taylor
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Gabriel Santpere
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Neurogenomics Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM), DCEXS, Universitat Pompeu Fabra, 08003 Barcelona, Catalonia, Spain
| | - Alexis Weinreb
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Alec Barrett
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Molly B Reilly
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Chuan Xu
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Erdem Varol
- Department of Statistics, Columbia University, New York, NY, USA
| | - Panos Oikonomou
- Department of Biological Sciences, Columbia University, New York, NY, USA; Department of Systems Biology, Columbia University Medical Center, New York, NY, USA
| | - Lori Glenwinkel
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Rebecca McWhirter
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Abigail Poff
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Manasa Basavaraju
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Ibnul Rafi
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Eviatar Yemini
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Steven J Cook
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Alexander Abrams
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Berta Vidal
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Cyril Cros
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Saeed Tavazoie
- Department of Biological Sciences, Columbia University, New York, NY, USA; Department of Systems Biology, Columbia University Medical Center, New York, NY, USA
| | - Nenad Sestan
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Marc Hammarlund
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Genetics, Yale University School of Medicine, New Haven, CT, USA.
| | - Oliver Hobert
- Department of Biological Sciences, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, Columbia University, New York, NY, USA.
| | - David M Miller
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA; Program in Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA.
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10
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Berghoff EG, Glenwinkel L, Bhattacharya A, Sun H, Varol E, Mohammadi N, Antone A, Feng Y, Nguyen K, Cook SJ, Wood JF, Masoudi N, Cros CC, Ramadan YH, Ferkey DM, Hall DH, Hobert O. The Prop1-like homeobox gene unc-42 specifies the identity of synaptically connected neurons. eLife 2021; 10:e64903. [PMID: 34165428 PMCID: PMC8225392 DOI: 10.7554/elife.64903] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 05/17/2021] [Indexed: 12/13/2022] Open
Abstract
Many neuronal identity regulators are expressed in distinct populations of cells in the nervous system, but their function is often analyzed only in specific isolated cellular contexts, thereby potentially leaving overarching themes in gene function undiscovered. We show here that the Caenorhabditis elegans Prop1-like homeobox gene unc-42 is expressed in 15 distinct sensory, inter- and motor neuron classes throughout the entire C. elegans nervous system. Strikingly, all 15 neuron classes expressing unc-42 are synaptically interconnected, prompting us to investigate whether unc-42 controls the functional properties of this circuit and perhaps also the assembly of these neurons into functional circuitry. We found that unc-42 defines the routes of communication between these interconnected neurons by controlling the expression of neurotransmitter pathway genes, neurotransmitter receptors, neuropeptides, and neuropeptide receptors. Anatomical analysis of unc-42 mutant animals reveals defects in axon pathfinding and synaptic connectivity, paralleled by expression defects of molecules involved in axon pathfinding, cell-cell recognition, and synaptic connectivity. We conclude that unc-42 establishes functional circuitry by acting as a terminal selector of functionally connected neuron types. We identify a number of additional transcription factors that are also expressed in synaptically connected neurons and propose that terminal selectors may also function as 'circuit organizer transcription factors' to control the assembly of functional circuitry throughout the nervous system. We hypothesize that such organizational properties of transcription factors may be reflective of not only ontogenetic, but perhaps also phylogenetic trajectories of neuronal circuit establishment.
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Affiliation(s)
- Emily G Berghoff
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Lori Glenwinkel
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Abhishek Bhattacharya
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - HaoSheng Sun
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Erdem Varol
- Department of Statistics, Zuckerman Institute, Columbia UniversityNew YorkUnited States
| | - Nicki Mohammadi
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Amelia Antone
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Yi Feng
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Ken Nguyen
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Steven J Cook
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Jordan F Wood
- Department of Biological Sciences, University at Buffalo, The State University of New YorkBuffaloUnited States
| | - Neda Masoudi
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Cyril C Cros
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Yasmin H Ramadan
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
| | - Denise M Ferkey
- Department of Biological Sciences, University at Buffalo, The State University of New YorkBuffaloUnited States
| | - David H Hall
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Oliver Hobert
- Department of Biological Sciences, Columbia University, Howard Hughes Medical InstituteNew YorkUnited States
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11
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Chen C, Fu H, He P, Yang P, Tu H. Extracellular Matrix Muscle Arm Development Defective Protein Cooperates with the One Immunoglobulin Domain Protein To Suppress Precocious Synaptic Remodeling. ACS Chem Neurosci 2021; 12:2045-2056. [PMID: 34019371 DOI: 10.1021/acschemneuro.1c00194] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Synaptic remodeling plays important roles in health and neural disorders. Although previous studies revealed that several transcriptional programs control synaptic remodeling in the nematode Caenorhabditis elegans, the molecular mechanisms of the dorsal D-type (DD) synaptic remodeling are poorly understood. Here we show that extracellular matrix molecule muscle arm development defective protein-4 (MADD-4) cooperates with the one immunoglobulin domain protein-1 (OIG-1) to defer precocious DD synaptic remodeling. Specifically, loss of MADD-4 exhibited the precocious DD synaptic remodeling. The long isoform MADD-4L is dynamically expressed while the short isoform MADD-4B is persistently expressed in DD neurons of L1 stage. In the unc-30 mutant lacking the Pitx-type homeodomain transcription factor UNC-30, the expression levels of both MADD-4B and -L isoforms were dramatically downregulated in DD neurons of the L1 stage. Our further data showed that MADD-4B and -L isoforms physically interact with OIG-1 and madd-4 acts in the oig-1 genetic pathway to modulate the DD synaptic remodeling. Our findings demonstrated that the extracellular matrix plays a novel role in synaptic plasticity.
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Affiliation(s)
- Chunhong Chen
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Neuroscience, College of Biology, Hunan University, 410082 Changsha, Hunan, China
| | - Huiyuan Fu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Neuroscience, College of Biology, Hunan University, 410082 Changsha, Hunan, China
| | - Ping He
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Neuroscience, College of Biology, Hunan University, 410082 Changsha, Hunan, China
| | - Peng Yang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Neuroscience, College of Biology, Hunan University, 410082 Changsha, Hunan, China
| | - Haijun Tu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Neuroscience, College of Biology, Hunan University, 410082 Changsha, Hunan, China
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12
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Cuentas-Condori A, Miller Rd DM. Synaptic remodeling, lessons from C. elegans. J Neurogenet 2020; 34:307-322. [PMID: 32808848 PMCID: PMC7855814 DOI: 10.1080/01677063.2020.1802725] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 07/07/2020] [Indexed: 02/08/2023]
Abstract
Sydney Brenner's choice of Caenorhabditis elegans as a model organism for understanding the nervous system has accelerated discoveries of gene function in neural circuit development and behavior. In this review, we discuss a striking example of synaptic remodeling in the C. elegans motor circuit in which DD class motor neurons effectively reverse polarity as presynaptic and postsynaptic domains at opposite ends of the DD neurite switch locations. Originally revealed by EM reconstruction conducted over 40 years ago, DD remodeling has since been investigated by live cell imaging methods that exploit the power of C. elegans genetics to reveal key effectors of synaptic plasticity. Although synapses are also extensively rewired in developing mammalian circuits, the underlying remodeling mechanisms are largely unknown. Here, we highlight the possibility that studies in C. elegans can reveal pathways that orchestrate synaptic remodeling in more complex organisms. Specifically, we describe (1) transcription factors that regulate DD remodeling, (2) the cellular and molecular cascades that drive synaptic remodeling and (3) examples of circuit modifications in vertebrate neurons that share some similarities with synaptic remodeling in C. elegans DD neurons.
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13
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Feng W, Li Y, Dao P, Aburas J, Islam P, Elbaz B, Kolarzyk A, Brown AE, Kratsios P. A terminal selector prevents a Hox transcriptional switch to safeguard motor neuron identity throughout life. eLife 2020; 9:50065. [PMID: 31902393 PMCID: PMC6944445 DOI: 10.7554/elife.50065] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 12/08/2019] [Indexed: 01/01/2023] Open
Abstract
To become and remain functional, individual neuron types must select during development and maintain throughout life their distinct terminal identity features, such as expression of specific neurotransmitter receptors, ion channels and neuropeptides. Here, we report a molecular mechanism that enables cholinergic motor neurons (MNs) in the C. elegans ventral nerve cord to select and maintain their unique terminal identity. This mechanism relies on the dual function of the conserved terminal selector UNC-3 (Collier/Ebf). UNC-3 synergizes with LIN-39 (Scr/Dfd/Hox4-5) to directly co-activate multiple terminal identity traits specific to cholinergic MNs, but also antagonizes LIN-39’s ability to activate terminal features of alternative neuronal identities. Loss of unc-3 causes a switch in the transcriptional targets of LIN-39, thereby alternative, not cholinergic MN-specific, terminal features become activated and locomotion defects occur. The strategy of a terminal selector preventing a transcriptional switch may constitute a general principle for safeguarding neuronal identity throughout life.
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Affiliation(s)
- Weidong Feng
- Department of Neurobiology, University of Chicago, Chicago, United States.,Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, United States
| | - Yinan Li
- Department of Neurobiology, University of Chicago, Chicago, United States.,Committee on Neurobiology, University of Chicago, Chicago, United States
| | - Pauline Dao
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Jihad Aburas
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Priota Islam
- MRC London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Benayahu Elbaz
- Department of Neurology, Center for Peripheral Neuropathy, University of Chicago, Chicago, United States
| | - Anna Kolarzyk
- Department of Neurology, Center for Peripheral Neuropathy, University of Chicago, Chicago, United States
| | - André Ex Brown
- MRC London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, United States.,Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, United States.,Committee on Neurobiology, University of Chicago, Chicago, United States.,The Grossman Institute for Neuroscience, Quantitative Biology, and Human Behavior, University of Chicago, Chicago, United States
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14
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Catela C, Kratsios P. Transcriptional mechanisms of motor neuron development in vertebrates and invertebrates. Dev Biol 2019; 475:193-204. [PMID: 31479648 DOI: 10.1016/j.ydbio.2019.08.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 07/08/2019] [Accepted: 08/29/2019] [Indexed: 02/04/2023]
Abstract
Across phylogeny, motor neurons (MNs) represent a single but often remarkably diverse neuronal class composed of a multitude of subtypes required for vital behaviors, such as eating and locomotion. Over the past decades, seminal studies in multiple model organisms have advanced our molecular understanding of the early steps of MN development, such as progenitor specification and acquisition of MN subtype identity, by revealing key roles for several evolutionarily conserved transcription factors. However, very little is known about the molecular strategies that allow distinct MN subtypes to maintain their identity- and function-defining features during the late steps of development and postnatal life. Here, we provide an overview of invertebrate and vertebrate studies on transcription factor-based strategies that control early and late steps of MN development, aiming to highlight evolutionarily conserved gene regulatory principles necessary for establishment and maintenance of neuronal identity.
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Affiliation(s)
- Catarina Catela
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA; The Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA; The Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA.
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15
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Wei S, Chen H, Dzakah EE, Yu B, Wang X, Fu T, Li J, Liu L, Fang S, Liu W, Shan G. Systematic evaluation of C. elegans lincRNAs with CRISPR knockout mutants. Genome Biol 2019; 20:7. [PMID: 30621757 PMCID: PMC6325887 DOI: 10.1186/s13059-018-1619-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 12/27/2018] [Indexed: 12/04/2022] Open
Abstract
Background Long intergenic RNAs (lincRNAs) play critical roles in eukaryotic cells, but systematic analyses of the lincRNAs of an animal for phenotypes are lacking. We generate CRISPR knockout strains for Caenorhabditis elegans lincRNAs and evaluate their phenotypes. Results C. elegans lincRNAs demonstrate global features such as shorter length and fewer exons than mRNAs. For the systematic evaluation of C. elegans lincRNAs, we produce CRISPR knockout strains for 155 of the total 170 C. elegans lincRNAs. Mutants of 23 lincRNAs show phenotypes in 6 analyzed traits. We investigate these lincRNAs by phenotype for their gene expression patterns and potential functional mechanisms. Some C. elegans lincRNAs play cis roles to modulate the expression of their neighboring genes, and several lincRNAs play trans roles as ceRNAs against microRNAs. We also examine the regulation of lincRNA expression by transcription factors, and we dissect the pathway by which two transcription factors, UNC-30 and UNC-55, together control the expression of linc-73. Furthermore, linc-73 possesses a cis function to modulate the expression of its neighboring kinesin gene unc-104 and thus plays roles in C. elegans locomotion. Conclusions By using CRISPR/cas9 technology, we generate knockout strains of 155 C. elegans lincRNAs as valuable resources for studies in noncoding RNAs, and we provide biological insights for 23 lincRNAs with the phenotypes identified in this study. Electronic supplementary material The online version of this article (10.1186/s13059-018-1619-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shuai Wei
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - He Chen
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Emmanuel Enoch Dzakah
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China.,Department of Molecular Biology and Biotechnology, School of Biological Sciences, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Bin Yu
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China.,Present address: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Xiaolin Wang
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Tao Fu
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Jingxin Li
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Lei Liu
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Shucheng Fang
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Weihong Liu
- MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.,Present address: Hanwang Technology Co., Ltd., Haidian District, Beijing, 100193, China
| | - Ge Shan
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China. .,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, CAS, Shanghai, 200031, China.
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16
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Yu B, Wang X, Wei S, Fu T, Dzakah EE, Waqas A, Walthall WW, Shan G. Convergent Transcriptional Programs Regulate cAMP Levels in C. elegans GABAergic Motor Neurons. Dev Cell 2017; 43:212-226.e7. [PMID: 29033363 DOI: 10.1016/j.devcel.2017.09.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 06/26/2017] [Accepted: 09/15/2017] [Indexed: 02/07/2023]
Abstract
Both transcriptional regulation and signaling pathways play crucial roles in neuronal differentiation and plasticity. Caenorhabditis elegans possesses 19 GABAergic motor neurons (MNs) called D MNs, which are divided into two subgroups: DD and VD. DD, but not VD, MNs reverse their cellular polarity in a developmental process called respecification. UNC-30 and UNC-55 are two critical transcription factors in D MNs. By using chromatin immunoprecipitation with CRISPR/Cas9 knockin of GFP fusion, we uncovered the global targets of UNC-30 and UNC-55. UNC-30 and UNC-55 are largely converged to regulate over 1,300 noncoding and coding genes, and genes in multiple biological processes, including cAMP metabolism, are co-regulated. Increase in cAMP levels may serve as a timing signal for respecification, whereas UNC-55 regulates genes such as pde-4 to keep the cAMP levels low in VD. Other genes modulating DD respecification such as lin-14, irx-1, and oig-1 are also found to affect cAMP levels.
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Affiliation(s)
- Bin Yu
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Xiaolin Wang
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Shuai Wei
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Tao Fu
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Emmanuel Enoch Dzakah
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Ahmed Waqas
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Walter W Walthall
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Ge Shan
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China.
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17
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Diversification of C. elegans Motor Neuron Identity via Selective Effector Gene Repression. Neuron 2017; 93:80-98. [PMID: 28056346 DOI: 10.1016/j.neuron.2016.11.036] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/11/2016] [Accepted: 11/11/2016] [Indexed: 12/20/2022]
Abstract
A common organizational feature of nervous systems is the existence of groups of neurons that share common traits but can be divided into individual subtypes based on anatomical or molecular features. We elucidate the mechanistic basis of neuronal diversification processes in the context of C.elegans ventral cord motor neurons that share common traits that are directly activated by the terminal selector UNC-3. Diversification of motor neurons into different classes, each characterized by unique patterns of effector gene expression, is controlled by distinct combinations of phylogenetically conserved, class-specific transcriptional repressors. These repressors are continuously required in postmitotic neurons to prevent UNC-3, which is active in all neuron classes, from activating class-specific effector genes in specific motor neuron subsets via discrete cis-regulatory elements. The strategy of antagonizing the activity of broadly acting terminal selectors of neuron identity in a subtype-specific fashion may constitute a general principle of neuron subtype diversification.
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18
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Campbell RF, Walthall WW. Meis/UNC-62 isoform dependent regulation of CoupTF-II/UNC-55 and GABAergic motor neuron subtype differentiation. Dev Biol 2016; 419:250-261. [PMID: 27634571 DOI: 10.1016/j.ydbio.2016.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/24/2016] [Accepted: 09/09/2016] [Indexed: 11/28/2022]
Abstract
Gene regulatory networks orchestrate the assembly of functionally related cells within a cellular network. Subtle differences often exist among functionally related cells within such networks. How differences are created among cells with similar functions has been difficult to determine due to the complexity of both the gene and the cellular networks. In Caenorhabditis elegans, the DD and VD motor neurons compose a cross-inhibitory, GABAergic network that coordinates dorsal and ventral muscle contractions during locomotion. The Pitx2 homologue, UNC-30, acts as a terminal selector gene to create similarities and the Coup-TFII homologue, UNC-55, is necessary for creating differences between the two motor neuron classes. What is the organizing gene regulatory network responsible for initiating the expression of UNC-55 and thus creating differences between the DD and VD motor neurons? We show that the unc-55 promoter has modules that contain Meis/UNC-62 binding sites. These sites can be subdivided into regions that are capable of activating or repressing UNC-55 expression in different motor neurons. Interestingly, different isoforms of UNC-62 are responsible for the activation and the stabilization of unc-55 transcription. Furthermore, specific isoforms of UNC-62 are required for proper synaptic patterning of the VD motor neurons. Isoform specific regulation of differentiating neurons is a relatively unexplored area of research and presents a mechanism for creating differences among functionally related cells within a network.
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MESH Headings
- Animals
- Animals, Genetically Modified
- CRISPR-Cas Systems
- Caenorhabditis elegans/genetics
- Caenorhabditis elegans/physiology
- Caenorhabditis elegans Proteins/biosynthesis
- Caenorhabditis elegans Proteins/physiology
- GABAergic Neurons/cytology
- Gene Expression Regulation, Developmental
- Gene Regulatory Networks/genetics
- Genes, Reporter
- Homeodomain Proteins/physiology
- Motor Neurons/classification
- Motor Neurons/cytology
- Neurogenesis/genetics
- Promoter Regions, Genetic/genetics
- Protein Isoforms/physiology
- RNA, Helminth/biosynthesis
- RNA, Helminth/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/physiology
- Receptors, Cytoplasmic and Nuclear/biosynthesis
- Receptors, Cytoplasmic and Nuclear/physiology
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Transcription Factors
- Transcription, Genetic/genetics
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Richard F Campbell
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States
| | - Walter W Walthall
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States.
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19
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Nath RD, Chow ES, Wang H, Schwarz EM, Sternberg PW. C. elegans Stress-Induced Sleep Emerges from the Collective Action of Multiple Neuropeptides. Curr Biol 2016; 26:2446-2455. [PMID: 27546573 DOI: 10.1016/j.cub.2016.07.048] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/15/2016] [Accepted: 07/19/2016] [Indexed: 01/03/2023]
Abstract
The genetic basis of sleep regulation remains poorly understood. In C. elegans, cellular stress induces sleep through epidermal growth factor (EGF)-dependent activation of the EGF receptor in the ALA neuron. The downstream mechanism by which this neuron promotes sleep is unknown. Single-cell RNA sequencing of ALA reveals that the most highly expressed, ALA-enriched genes encode neuropeptides. Here we have systematically investigated the four most highly enriched neuropeptides: flp-7, nlp-8, flp-24, and flp-13. When individually removed by null mutation, these peptides had little or no effect on stress-induced sleep. However, stress-induced sleep was abolished in nlp-8; flp-24; flp-13 triple-mutant animals, indicating that these neuropeptides work collectively in controlling stress-induced sleep. We tested the effect of overexpression of these neuropeptide genes on five behaviors modulated during sleep-pharyngeal pumping, defecation, locomotion, head movement, and avoidance response to an aversive stimulus-and we found that, if individually overexpressed, each of three neuropeptides (nlp-8, flp-24, or flp-13) induced a different suite of sleep-associated behaviors. These overexpression results raise the possibility that individual components of sleep might be specified by individual neuropeptides or combinations of neuropeptides.
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Affiliation(s)
- Ravi D Nath
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, Cornell University, Ithaca, NY 14853-2703, USA
| | - Elly S Chow
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, Cornell University, Ithaca, NY 14853-2703, USA
| | - Han Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, Cornell University, Ithaca, NY 14853-2703, USA
| | - Erich M Schwarz
- Department of Molecular Biology and Genetics, Biotechnology 351, Cornell University, Ithaca, NY 14853-2703, USA
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, Cornell University, Ithaca, NY 14853-2703, USA.
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20
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Miller-Fleming TW, Petersen SC, Manning L, Matthewman C, Gornet M, Beers A, Hori S, Mitani S, Bianchi L, Richmond J, Miller DM. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons. eLife 2016; 5. [PMID: 27403890 PMCID: PMC4980115 DOI: 10.7554/elife.14599] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 07/11/2016] [Indexed: 12/30/2022] Open
Abstract
Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. DOI:http://dx.doi.org/10.7554/eLife.14599.001 The brain contains billions of nerve cells, or neurons, that communicate with one another through connections called synapses. As the brain develops, these circuits are extensively modified as new synapses are created and others are removed. Neurological disorders may emerge if these processes are not regulated correctly. Identifying the biological pathways that control the addition and removal of synapses could therefore provide new insights into how to treat human brain diseases. To communicate across a synapse, the signaling neuron releases chemicals called neurotransmitters that alter the activity of the receiving neuron. Some neurotransmitters, such as GABA, inhibit the activity of the receiving neuron. The activity of a neuron – and hence how often it releases neurotransmitters – depends on different ions moving into and out of the neuron through proteins called ion channels that are embedded in the cell membrane. For example, the movement of calcium ions into the neuron can trigger the release of neurotransmitters. The roundworm Caenorhabditis elegans is often used as a model organism to study how the brain develops. During development, the worm nervous system eliminates synapses that release GABA and reassembles them at new locations. However, the nervous system does not eliminate these synapses at random. Miller-Fleming, Petersen et al. now show that a C. elegans protein called UNC-8 is responsible for this effect. UNC-8 forms part of an ion channel that allows sodium ions to enter the neuron and is selectively produced in GABA neurons that are destined for remodeling. Miller-Fleming, Petersen et al. found that inside GABA-releasing neurons, calcium ions stimulate an enzyme called calcineurin that may in turn activate UNC-8. Sodium ions then enter the neuron through UNC-8 channels. This boosts the activity of the calcium ion channels, which further increases how many calcium ions enter the cell. Ultimately, the amount of calcium inside the neuron becomes high enough to activate an additional pathway that eliminates the synapse. This downstream pathway involves components of a cell-killing (or “apoptotic”) mechanism that is repurposed in this case to remove the GABA release apparatus at the synapse. Other proteins are likely to help UNC-8 sense the activity of neurons and destroy synapses in response. Further work is required to investigate these additional components and to determine how they work with UNC-8 to remove synapses in the nervous system during development. DOI:http://dx.doi.org/10.7554/eLife.14599.002
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Affiliation(s)
| | - Sarah C Petersen
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, United States
| | - Cristina Matthewman
- Department of Physiology and Biophysics, University of Miami, Miami, United States
| | - Megan Gornet
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Allison Beers
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Sayaka Hori
- Department of Physiology, Tokyo Women's Medical University, Tokyo, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University, Tokyo, Japan
| | - Laura Bianchi
- Department of Physiology and Biophysics, University of Miami, Miami, United States
| | - Janet Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, United States
| | - David M Miller
- Neuroscience Program, Vanderbilt University, Nashville, United States.,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
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21
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Kurup N, Jin Y. Neural circuit rewiring: insights from DD synapse remodeling. WORM 2015; 5:e1129486. [PMID: 27073734 DOI: 10.1080/21624054.2015.1129486] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 11/24/2015] [Accepted: 12/04/2015] [Indexed: 01/27/2023]
Abstract
Nervous systems exhibit many forms of neuronal plasticity during growth, learning and memory consolidation, as well as in response to injury. Such plasticity can occur across entire nervous systems as with the case of insect metamorphosis, in individual classes of neurons, or even at the level of a single neuron. A striking example of neuronal plasticity in C. elegans is the synaptic rewiring of the GABAergic Dorsal D-type motor neurons during larval development, termed DD remodeling. DD remodeling entails multi-step coordination to concurrently eliminate pre-existing synapses and form new synapses on different neurites, without changing the overall morphology of the neuron. This mini-review focuses on recent advances in understanding the cellular and molecular mechanisms driving DD remodeling.
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Affiliation(s)
- Naina Kurup
- Neurobiology Section, Division of Biological Sciences, University of California , San Diego, La Jolla, CA, USA
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, USA
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22
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He S, Philbrook A, McWhirter R, Gabel CV, Taub DG, Carter MH, Hanna IM, Francis MM, Miller DM. Transcriptional Control of Synaptic Remodeling through Regulated Expression of an Immunoglobulin Superfamily Protein. Curr Biol 2015; 25:2541-8. [PMID: 26387713 DOI: 10.1016/j.cub.2015.08.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/04/2015] [Accepted: 08/10/2015] [Indexed: 11/24/2022]
Abstract
Neural circuits are actively remodeled during brain development, but the molecular mechanisms that trigger circuit refinement are poorly understood. Here, we describe a transcriptional program in C. elegans that regulates expression of an Ig domain protein, OIG-1, to control the timing of synaptic remodeling. DD GABAergic neurons reverse polarity during larval development by exchanging the locations of pre- and postsynaptic components. In newly born larvae, DDs receive cholinergic inputs in the dorsal nerve cord. These inputs are switched to the ventral side by the end of the first larval (L1) stage. VD class GABAergic neurons are generated in the late L1 and are postsynaptic to cholinergic neurons in the dorsal nerve cord but do not remodel. We investigated remodeling of the postsynaptic apparatus in DD and VD neurons using targeted expression of the acetylcholine receptor (AChR) subunit, ACR-12::GFP. We determined that OIG-1 antagonizes the relocation of ACR-12 from the dorsal side in L1 DD neurons. During the L1/L2 transition, OIG-1 is downregulated in DD neurons by the transcription factor IRX-1/Iroquois, allowing the repositioning of synaptic inputs to the ventral side. In VD class neurons, which normally do not remodel, the transcription factor UNC-55/COUP-TF turns off IRX-1, thus maintaining high levels of OIG-1 to block the removal of dorsally located ACR-12 receptors. OIG-1 is secreted from GABA neurons, but its anti-plasticity function is cell autonomous and may not require secretion. Our study provides a novel mechanism by which synaptic remodeling is set in motion through regulated expression of an Ig domain protein.
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Affiliation(s)
- Siwei He
- Neuroscience Graduate Program, Vanderbilt International Scholar Program, Vanderbilt University, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Alison Philbrook
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Rebecca McWhirter
- Department of Cell and Developmental Biology, Vanderbilt University, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Christopher V Gabel
- Department of Physiology and Biophysics, Boston University Medical Campus, 700 Albany Street, Boston, MA 02118, USA
| | - Daniel G Taub
- Department of Physiology and Biophysics, Boston University Medical Campus, 700 Albany Street, Boston, MA 02118, USA
| | - Maximilian H Carter
- Department of Cell and Developmental Biology, Vanderbilt University, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Isabella M Hanna
- Department of Cell and Developmental Biology, Vanderbilt University, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Michael M Francis
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
| | - David M Miller
- Neuroscience Graduate Program, Vanderbilt International Scholar Program, Vanderbilt University, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA; Department of Cell and Developmental Biology, Vanderbilt University, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA.
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23
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Howell K, White JG, Hobert O. Spatiotemporal control of a novel synaptic organizer molecule. Nature 2015; 523:83-7. [PMID: 26083757 PMCID: PMC9134992 DOI: 10.1038/nature14545] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 05/12/2015] [Indexed: 12/13/2022]
Abstract
Synapse formation is a process tightly controlled in space and time. How gene regulatory mechanisms specify spatial and temporal aspects of synapse formation is not well understood. In the nematode C.elegans, two subtypes of the D-type inhibitory motor neuron (MN) classes, the dorsal D (DD) and ventral D (VD) neurons, extend axons along both the dorsal and ventral nerve cords 1. The embryonically generated DD MNs initially innervate ventral muscles in the first (L1) larval stage and receive their synaptic input from cholinergic MNs in the dorsal cord. They rewire by the end of the L1 molt to innervate dorsal muscles and to be innervated by newly formed ventral cholinergic MNs 1. VD MNs develop after the L1 molt; they take over the innervation of ventral muscles and receive their synaptic input from dorsal cholinergic MNs. We show here that the spatiotemporal control of synaptic wiring of the D-type neurons is controlled by an intersectional transcriptional strategy in which the UNC-30 Pitx-type homeodomain transcription factor acts together in embryonic and early larval stages with the temporally controlled LIN-14 transcription factor to prevent premature synapse rewiring of the DD MNs and, together with the UNC-55 nuclear hormone receptor, to prevent aberrant VD synaptic wiring in later larval and adult stages. A key effector of this intersectional transcription factor combination is a novel synaptic organizer molecule, the single immunoglobulin domain protein OIG-1. OIG-1 is perisynaptically localized along the synaptic outputs of the D-type MNs in a temporally controlled manner and is required for appropriate selection of both pre- and post-synaptic partners.
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Nuclear receptors in nematode development: Natural experiments made by a phylum. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:224-37. [PMID: 24984201 DOI: 10.1016/j.bbagrm.2014.06.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 06/21/2014] [Accepted: 06/23/2014] [Indexed: 11/21/2022]
Abstract
The development of complex multicellular organisms is dependent on regulatory decisions that are necessary for the establishment of specific differentiation and metabolic cellular states. Nuclear receptors (NRs) form a large family of transcription factors that play critical roles in the regulation of development and metabolism of Metazoa. Based on their DNA binding and ligand binding domains, NRs are divided into eight NR subfamilies from which representatives of six subfamilies are present in both deuterostomes and protostomes indicating their early evolutionary origin. In some nematode species, especially in Caenorhabditis, the family of NRs expanded to a large number of genes strikingly exceeding the number of NR genes in vertebrates or insects. Nematode NRs, including the multiplied Caenorhabditis genes, show clear relation to vertebrate and insect homologues belonging to six of the eight main NR subfamilies. This review summarizes advances in research of nematode NRs and their developmental functions. Nematode NRs can reveal evolutionarily conserved mechanisms that regulate specific developmental and metabolic processes as well as new regulatory adaptations. They represent the results of a large number of natural experiments with structural and functional potential of NRs for the evolution of the phylum. The conserved and divergent character of nematode NRs adds a new dimension to our understanding of the general biology of regulation by NRs. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
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25
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The Function of Snodprot in the Cerato-Platanin Family fromDactylellina cionopagain Nematophagous Fungi. Biosci Biotechnol Biochem 2014; 76:1835-42. [DOI: 10.1271/bbb.120173] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Stout Jr RF, Grubišić V, Parpura V. A Caenorhabditis elegans locomotion phenotype caused by transgenic repeats of the hlh-17 promoter sequence. PLoS One 2013; 8:e81771. [PMID: 24312354 PMCID: PMC3842965 DOI: 10.1371/journal.pone.0081771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 10/16/2013] [Indexed: 01/17/2023] Open
Abstract
Transgene technology is one of the most heavily relied upon tools in modern biological research. Expression of an exogenous gene within cells, for research and therapeutic applications, nearly always includes promoters and other regulatory sequences. We found that repeats of a non-protein coding transgenic sequence produced profound changes to the behavior of the nematode Caenorhabditis elegans. These changes were produced by a glial promoter sequence but, unexpectedly, major deficits were observed specifically in backward locomotion, a neuron-driven behavior. We also present evidence that this behavioral phenotype is transpromoter copy number-dependent and manifests early in development and is maintained into adulthood of the worm.
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Affiliation(s)
- Randy F. Stout Jr
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy & Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, Alabama, United States of America
| | - Vladimir Grubišić
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy & Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, Alabama, United States of America
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy & Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, Alabama, United States of America
- Department of Biotechnology, University of Rijeka, Rijeka, Croatia
- * E-mail:
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27
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Xie X, Tang K, Yu CT, Tsai SY, Tsai MJ. Regulatory potential of COUP-TFs in development: stem/progenitor cells. Semin Cell Dev Biol 2013; 24:687-93. [PMID: 23978678 DOI: 10.1016/j.semcdb.2013.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 08/14/2013] [Accepted: 08/16/2013] [Indexed: 12/25/2022]
Abstract
The formation of complex organisms is highly dependent on the differentiation of specialized mature cells from common stem/progenitor cells. The orphan nuclear receptors chicken ovalbumin upstream promoter transcription factors (COUP-TFs) are broadly, but not ubiquitously, expressed in multiple tissues throughout embryonic development and COUP-TFs are indispensible for proper organogenesis. Recently, growing evidence suggests a critical role of COUP-TFs in multiple aspects of stem/progenitor cell biology. In this review, we highlight the progress of COUP-TFs function and its underlying mechanism in driving stem/progenitor cell self-renewal, lineage specification, differentiation, maintenance, and cell identity in diverse tissue types. These studies provide novel insights into future clinical utilities of COUP-TFs in stem cell based therapies and in the management of diseases.
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Affiliation(s)
- Xin Xie
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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28
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Meng L, Chen L, Li Z, Wu ZX, Shan G. Roles of microRNAs in the Caenorhabditis elegans nervous system. J Genet Genomics 2013; 40:445-52. [PMID: 24053946 DOI: 10.1016/j.jgg.2013.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 07/05/2013] [Accepted: 07/08/2013] [Indexed: 12/11/2022]
Abstract
The first microRNA was discovered in Caenorhabditis elegans in 1993, and since then, thousands of microRNAs have been identified from almost all eukaryotic organisms examined. MicroRNAs function in many biological events such as cell fate determination, metabolism, apoptosis, and carcinogenesis. So far, more than 250 microRNAs have been identified in C. elegans; however, functions for most of these microRNAs are still unknown. A small number of C. elegans microRNAs are associated with known physiological roles such as developmental timing, cell differentiation, stress response, and longevity. In this review, we summarize known roles of microRNAs in neuronal differentiation and function of C. elegans, and discuss interesting perspectives for future studies.
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Affiliation(s)
- Lingfeng Meng
- School of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
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29
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Thompson-Peer K, Bai J, Hu Z, Kaplan JM. HBL-1 patterns synaptic remodeling in C. elegans. Neuron 2012; 73:453-65. [PMID: 22325199 PMCID: PMC3278716 DOI: 10.1016/j.neuron.2011.11.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2011] [Indexed: 11/27/2022]
Abstract
During development, circuits are refined by the dynamic addition and removal of synapses; however, little is known about the molecular mechanisms that dictate where and when synaptic refinement occurs. Here we describe transcriptional mechanisms that pattern remodeling of C. elegans neuromuscular junctions (NMJs). The embryonic GABAergic DD motor neurons remodel their synapses, whereas the later born VD neurons do not. This specificity is mediated by differential expression of a transcription factor (HBL-1), which is expressed in DD neurons but is repressed in VDs by UNC-55/COUP-TF. DD remodeling is delayed in hbl-1 mutants whereas precocious remodeling is observed in mutants lacking the microRNA mir-84, which inhibits hbl-1 expression. Mutations increasing and decreasing circuit activity cause corresponding changes in hbl-1 expression, and corresponding shifts in the timing of DD plasticity. Thus, convergent regulation of hbl-1 expression defines a genetic mechanism that patterns activity-dependent synaptic remodeling across cell types and across developmental time.
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Affiliation(s)
- Katherine Thompson-Peer
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114; Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Jihong Bai
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114; Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Zhitao Hu
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114; Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Joshua M. Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114; Department of Neurobiology, Harvard Medical School, Boston, MA 02115
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30
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A transcriptional program promotes remodeling of GABAergic synapses in Caenorhabditis elegans. J Neurosci 2011; 31:15362-75. [PMID: 22031882 DOI: 10.1523/jneurosci.3181-11.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although transcription factors are known to regulate synaptic plasticity, downstream genes that contribute to neural circuit remodeling are largely undefined. In Caenorhabditis elegans, GABAergic Dorsal D (DD) motor neuron synapses are relocated to new sites during larval development. This remodeling program is blocked in Ventral D (VD) GABAergic motor neurons by the COUP-TF (chicken ovalbumin upstream promoter transcription factor) homolog, UNC-55. We exploited this UNC-55 function to identify downstream synaptic remodeling genes that encode a diverse array of protein types including ion channels, cytoskeletal components, and transcription factors. We show that one of these targets, the Iroquois-like homeodomain protein, IRX-1, functions as a key regulator of remodeling in DD neurons. Our discovery of irx-1 as an unc-55-regulated target defines a transcriptional pathway that orchestrates an intricate synaptic remodeling program. Moreover, the well established roles of these conserved transcription factors in mammalian neural development suggest that a similar cascade may also control synaptic plasticity in more complex nervous systems.
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31
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Jacobs FMJ, van Erp S, van der Linden AJA, von Oerthel L, Burbach JPH, Smidt MP. Pitx3 potentiates Nurr1 in dopamine neuron terminal differentiation through release of SMRT-mediated repression. Development 2009; 136:531-40. [PMID: 19144721 DOI: 10.1242/dev.029769] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In recent years, the meso-diencephalic dopaminergic (mdDA) neurons have been extensively studied for their association with Parkinson's disease. Thus far, specification of the dopaminergic phenotype of mdDA neurons is largely attributed to the orphan nuclear receptor Nurr1. In this study, we provide evidence for extensive interplay between Nurr1 and the homeobox transcription factor Pitx3 in vivo. Both Nurr1 and Pitx3 interact with the co-repressor PSF and occupy the promoters of Nurr1 target genes in concert. Moreover, in vivo expression analysis reveals that Nurr1 alone is not sufficient to drive the dopaminergic phenotype in mdDA neurons but requires Pitx3 for full activation of target gene expression. In the absence of Pitx3, Nurr1 is kept in a repressed state through interaction with the co-repressor SMRT. Highly resembling the effect of ligand activation of nuclear receptors, recruitment of Pitx3 modulates the Nurr1 transcriptional complex by decreasing the interaction with SMRT, which acts through HDACs to keep promoters in a repressed deacetylated state. Indeed, interference with HDAC-mediated repression in Pitx3(-/-) embryos efficiently reactivates the expression of Nurr1 target genes, bypassing the necessity for Pitx3. These data position Pitx3 as an essential potentiator of Nurr1 in specifying the dopaminergic phenotype, providing novel insights into mechanisms underlying development of mdDA neurons in vivo, and the programming of stem cells as a future cell replacement therapy for Parkinson's disease.
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Affiliation(s)
- Frank M J Jacobs
- Department of Neuroscience & Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
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32
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Copulation in C. elegans males requires a nuclear hormone receptor. Dev Biol 2008; 322:11-20. [DOI: 10.1016/j.ydbio.2008.06.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 06/20/2008] [Accepted: 06/27/2008] [Indexed: 11/20/2022]
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33
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Schuske K, Palfreyman MT, Watanabe S, Jorgensen EM. UNC-46 is required for trafficking of the vesicular GABA transporter. Nat Neurosci 2007; 10:846-53. [PMID: 17558401 DOI: 10.1038/nn1920] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 05/09/2007] [Indexed: 12/11/2022]
Abstract
Mutations in unc-46 in Caenorhabditis elegans cause defects in all behaviors that are mediated by GABA. Here we show that UNC-46 is a sorting factor that localizes the vesicular GABA transporter to synaptic vesicles. The UNC-46 protein is related to the LAMP (lysosomal associated membrane protein) family of proteins and is localized at synapses. In unc-46 mutants, the vesicular transporter is not found specifically in synaptic vesicles but rather is diffusely spread along the axon. Mislocalization of the transporter severely reduces the frequency of miniature currents, but the remaining currents are normal in amplitude. Because the number of synaptic vesicles is not depleted, it is likely that only a fraction of vesicles harbor the transporter in unc-46 mutants. Our data indicate that the transporter and UNC-46 have mutual roles in sorting. The vesicular GABA transporter recruits UNC-46 to synaptic vesicle precursors in the cell body, and UNC-46 sorts the transporter at the cell body and during endocytosis at the synapse.
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Affiliation(s)
- Kim Schuske
- Howard Hughes Medical Institute and the Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112-0840, USA
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34
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Melkman T, Sengupta P. Regulation of chemosensory and GABAergic motor neuron development by the C. elegans Aristaless/Arx homolog alr-1. Development 2005; 132:1935-49. [PMID: 15790968 DOI: 10.1242/dev.01788] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in the highly conserved Aristaless-related homeodomain protein ARX have been shown to underlie multiple forms of X-linked mental retardation. Arx knockout mice exhibit thinner cerebral cortices because of decreased neural precursor proliferation, and also exhibit defects in the differentiation and migration of GABAergic interneurons. However, the role of ARX in the observed behavioral and developmental abnormalities is unclear. The regulatory functions of individual homeodomain proteins and the networks in which they act are frequently highly conserved across species, although these networks may be deployed in different developmental contexts. In Drosophila, aristaless mutants exhibit defects in the development of terminal appendages, and Aristaless has been shown to function with the LIM-homeodomain protein LIM1 to regulate leg development. Here, we describe the role of the Aristaless/Arx homolog alr-1 in C. elegans. We show that alr-1 acts in a pathway with the LIM1 ortholog lin-11 to regulate the development of a subset of chemosensory neurons. Moreover, we demonstrate that the differentiation of a GABAergic motoneuron subtype is affected in alr-1 mutants, suggesting parallels with ARX functions in vertebrates. Investigating ALR-1 functions in C. elegans may yield insights into the role of this important protein in neuronal development and the etiology of mental retardation.
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Affiliation(s)
- Tali Melkman
- Department of Biology, Brandeis University, 415 South Street, Brandeis, MA 02454, USA
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35
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Abstract
Caenorhabditis elegans motor neurons control a range of activities including locomotion, foraging, defecation, and gender-specific functions. In this chapter,we focus primarily on motor neurons that regulate body movement, with particular emphasis on those in the ventral nerve cord (VNC). We describe the basic architecture and development of the motor circuit, genes that specify motor neuron fates, and models of how the motor circuit controls locomotion. We identify surprising similarities between the structure and development of the nematode and vertebrate axial nerve cords and speculate about the potential roles of conserved families of transcription factors in the evolution of these motor circuits.
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Affiliation(s)
- Stephen E Von Stetina
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
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