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Xu W, Liu J, Qi H, Si R, Zhao Z, Tao Z, Bai Y, Hu S, Sun X, Cong Y, Zhang H, Fan D, Xiao L, Wang Y, Li Y, Du Z. A lineage-resolved cartography of microRNA promoter activity in C. elegans empowers multidimensional developmental analysis. Nat Commun 2024; 15:2783. [PMID: 38555276 PMCID: PMC10981687 DOI: 10.1038/s41467-024-47055-4] [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: 01/08/2024] [Accepted: 03/13/2024] [Indexed: 04/02/2024] Open
Abstract
Elucidating the expression of microRNAs in developing single cells is critical for functional discovery. Here, we construct scCAMERA (single-cell cartography of microRNA expression based on reporter assay), utilizing promoter-driven fluorescent reporters in conjunction with imaging and lineage tracing. The cartography delineates the transcriptional activity of 54 conserved microRNAs in lineage-resolved single cells throughout C. elegans embryogenesis. The combinatorial expression of microRNAs partitions cells into fine clusters reflecting their function and anatomy. Notably, the expression of individual microRNAs exhibits high cell specificity and divergence among family members. Guided by cellular expression patterns, we identify developmental functions of specific microRNAs, including miR-1 in pharynx development and physiology, miR-232 in excretory canal morphogenesis by repressing NHR-25/NR5A, and a functional synergy between miR-232 and miR-234 in canal development, demonstrating the broad utility of scCAMERA. Furthermore, integrative analysis reveals that tissue-specific fate determinants activate microRNAs to repress protein production from leaky transcripts associated with alternative, especially neuronal, fates, thereby enhancing the fidelity of developmental fate differentiation. Collectively, our study offers rich opportunities for multidimensional expression-informed analysis of microRNA biology in metazoans.
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Affiliation(s)
- Weina Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jinyi Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Huan Qi
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Ruolin Si
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Zhiguang Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhiju Tao
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Yuchuan Bai
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Shipeng Hu
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Xiaohan Sun
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yulin Cong
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Haoye Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Duchangjiang Fan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Long Xiao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yangyang Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yongbin Li
- College of Life Sciences, Capital Normal University, Beijing, China.
| | - Zhuo Du
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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Destain H, Prahlad M, Kratsios P. Maintenance of neuronal identity in C. elegans and beyond: Lessons from transcription and chromatin factors. Semin Cell Dev Biol 2024; 154:35-47. [PMID: 37438210 PMCID: PMC10592372 DOI: 10.1016/j.semcdb.2023.07.001] [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: 04/26/2023] [Revised: 06/30/2023] [Accepted: 07/01/2023] [Indexed: 07/14/2023]
Abstract
Neurons are remarkably long-lived, non-dividing cells that must maintain their functional features (e.g., electrical properties, chemical signaling) for extended periods of time - decades in humans. How neurons accomplish this incredible feat is poorly understood. Here, we review recent advances, primarily in the nematode C. elegans, that have enhanced our understanding of the molecular mechanisms that enable post-mitotic neurons to maintain their functionality across different life stages. We begin with "terminal selectors" - transcription factors necessary for the establishment and maintenance of neuronal identity. We highlight new findings on five terminal selectors (CHE-1 [Glass], UNC-3 [Collier/Ebf1-4], LIN-39 [Scr/Dfd/Hox4-5], UNC-86 [Acj6/Brn3a-c], AST-1 [Etv1/ER81]) from different transcription factor families (ZNF, COE, HOX, POU, ETS). We compare the functions of these factors in specific neuron types of C. elegans with the actions of their orthologs in other invertebrate (D. melanogaster) and vertebrate (M. musculus) systems, highlighting remarkable functional conservation. Finally, we reflect on recent findings implicating chromatin-modifying proteins, such as histone methyltransferases and Polycomb proteins, in the control of neuronal terminal identity. Altogether, these new studies on transcription factors and chromatin modifiers not only shed light on the fundamental problem of neuronal identity maintenance, but also outline mechanistic principles of gene regulation that may operate in other long-lived, post-mitotic cell types.
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Affiliation(s)
- Honorine Destain
- Department of Neurobiology, University of Chicago, Chicago, IL, USA; Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, IL, USA; University of Chicago Neuroscience Institute, Chicago, IL, USA
| | - Manasa Prahlad
- Department of Neurobiology, University of Chicago, Chicago, IL, USA; Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL, USA; University of Chicago Neuroscience Institute, Chicago, IL, USA
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, IL, USA; Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, IL, USA; Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL, USA; University of Chicago Neuroscience Institute, Chicago, IL, USA.
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3
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Liu J, Murray JI. Mechanisms of lineage specification in Caenorhabditis elegans. Genetics 2023; 225:iyad174. [PMID: 37847877 DOI: 10.1093/genetics/iyad174] [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: 08/26/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The studies of cell fate and lineage specification are fundamental to our understanding of the development of multicellular organisms. Caenorhabditis elegans has been one of the premiere systems for studying cell fate specification mechanisms at single cell resolution, due to its transparent nature, the invariant cell lineage, and fixed number of somatic cells. We discuss the general themes and regulatory mechanisms that have emerged from these studies, with a focus on somatic lineages and cell fates. We next review the key factors and pathways that regulate the specification of discrete cells and lineages during embryogenesis and postembryonic development; we focus on transcription factors and include numerous lineage diagrams that depict the expression of key factors that specify embryonic founder cells and postembryonic blast cells, and the diverse somatic cell fates they generate. We end by discussing some future perspectives in cell and lineage specification.
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Affiliation(s)
- Jun Liu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - John Isaac Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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4
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Widespread employment of conserved C. elegans homeobox genes in neuronal identity specification. PLoS Genet 2022; 18:e1010372. [PMID: 36178933 PMCID: PMC9524666 DOI: 10.1371/journal.pgen.1010372] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/03/2022] [Indexed: 11/20/2022] Open
Abstract
Homeobox genes are prominent regulators of neuronal identity, but the extent to which their function has been probed in animal nervous systems remains limited. In the nematode Caenorhabditis elegans, each individual neuron class is defined by the expression of unique combinations of homeobox genes, prompting the question of whether each neuron class indeed requires a homeobox gene for its proper identity specification. We present here progress in addressing this question by extending previous mutant analysis of homeobox gene family members and describing multiple examples of homeobox gene function in different parts of the C. elegans nervous system. To probe homeobox function, we make use of a number of reporter gene tools, including a novel multicolor reporter transgene, NeuroPAL, which permits simultaneous monitoring of the execution of multiple differentiation programs throughout the entire nervous system. Using these tools, we add to the previous characterization of homeobox gene function by identifying neuronal differentiation defects for 14 homeobox genes in 24 distinct neuron classes that are mostly unrelated by location, function and lineage history. 12 of these 24 neuron classes had no homeobox gene function ascribed to them before, while in the other 12 neuron classes, we extend the combinatorial code of transcription factors required for specifying terminal differentiation programs. Furthermore, we demonstrate that in a particular lineage, homeotic identity transformations occur upon loss of a homeobox gene and we show that these transformations are the result of changes in homeobox codes. Combining the present with past analyses, 113 of the 118 neuron classes of C. elegans are now known to require a homeobox gene for proper execution of terminal differentiation programs. Such broad deployment indicates that homeobox function in neuronal identity specification may be an ancestral feature of animal nervous systems.
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Traets JJ, van der Burght SN, Rademakers S, Jansen G, van Zon JS. Mechanism of life-long maintenance of neuron identity despite molecular fluctuations. eLife 2021; 10:66955. [PMID: 34908528 PMCID: PMC8735970 DOI: 10.7554/elife.66955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 12/14/2021] [Indexed: 11/13/2022] Open
Abstract
Cell fate is maintained over long timescales, yet molecular fluctuations can lead to spontaneous loss of this differentiated state. Our simulations identified a possible mechanism that explains life-long maintenance of ASE neuron fate in Caenorhabditis elegans by the terminal selector transcription factor CHE-1. Here, fluctuations in CHE-1 level are buffered by the reservoir of CHE-1 bound at its target promoters, which ensures continued che-1 expression by preferentially binding the che-1 promoter. We provide experimental evidence for this mechanism by showing that che-1 expression was resilient to induced transient CHE-1 depletion, while both expression of CHE-1 targets and ASE function were lost. We identified a 130 bp che-1 promoter fragment responsible for this resilience, with deletion of a homeodomain binding site in this fragment causing stochastic loss of ASE identity long after its determination. Because network architectures that support this mechanism are highly conserved in cell differentiation, it may explain stable cell fate maintenance in many systems.
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Affiliation(s)
| | | | | | - Gert Jansen
- Department of Cell Biology, Erasmus MC, Rotterdam, Netherlands
| | - Jeroen S van Zon
- Quantitative Developmental Biology, AMOLF, Amsterdam, Netherlands
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6
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Rapti G. A perspective on C. elegans neurodevelopment: from early visionaries to a booming neuroscience research. J Neurogenet 2021; 34:259-272. [PMID: 33446023 DOI: 10.1080/01677063.2020.1837799] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The formation of the nervous system and its striking complexity is a remarkable feat of development. C. elegans served as a unique model to dissect the molecular events in neurodevelopment, from its early visionaries to the current booming neuroscience community. Soon after being introduced as a model, C. elegans was mapped at the level of genes, cells, and synapses, providing the first metazoan with a complete cell lineage, sequenced genome, and connectome. Here, I summarize mechanisms underlying C. elegans neurodevelopment, from the generation and diversification of neural components to their navigation and connectivity. I point out recent noteworthy findings in the fields of glia biology, sex dimorphism and plasticity in neurodevelopment, highlighting how current research connects back to the pioneering studies by Brenner, Sulston and colleagues. Multifaceted investigations in model organisms, connecting genes to cell function and behavior, expand our mechanistic understanding of neurodevelopment while allowing us to formulate emerging questions for future discoveries.
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Affiliation(s)
- Georgia Rapti
- European Molecular Biology Laboratory, Unit of Developmental Biology, Heidelberg, Germany
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7
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A 4D single-cell protein atlas of transcription factors delineates spatiotemporal patterning during embryogenesis. Nat Methods 2021; 18:893-902. [PMID: 34312566 DOI: 10.1038/s41592-021-01216-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 06/17/2021] [Indexed: 12/27/2022]
Abstract
Complex biological processes such as embryogenesis require precise coordination of cell differentiation programs across both space and time. Using protein-fusion fluorescent reporters and four-dimensional live imaging, we present a protein expression atlas of transcription factors (TFs) mapped onto developmental cell lineages during Caenorhabditis elegans embryogenesis, at single-cell resolution. This atlas reveals a spatiotemporal combinatorial code of TF expression, and a cascade of lineage-specific, tissue-specific and time-specific TFs that specify developmental states. The atlas uncovers regulators of embryogenesis, including an unexpected role of a skin specifier in neurogenesis and the critical function of an uncharacterized TF in convergent muscle differentiation. At the systems level, the atlas provides an opportunity to model cell state-fate relationships, revealing a lineage-dependent state diversity within functionally related cells and a winding trajectory of developmental state progression. Collectively, this single-cell protein atlas represents a valuable resource for elucidating metazoan embryogenesis at the molecular and systems levels.
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Lu K, Li Y, Cheng Y, Li W, Song Y, Zeng R, Sun Z. Activation of the NR2E nuclear receptor HR83 leads to metabolic detoxification-mediated chlorpyrifos resistance in Nilaparvata lugens. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 173:104800. [PMID: 33771269 DOI: 10.1016/j.pestbp.2021.104800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/27/2021] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
Increased production of detoxification enzymes appears to be the primary route for insecticide resistance in many crop pests. However, the mechanisms employed by resistant insects for overexpression of detoxification genes involved in insecticide resistance remain obscure. We report here that the NR2E nuclear receptor HR83 plays a critical role in chlorpyrifos resistance by regulating the expression of detoxification genes in the brown planthopper (BPH), Nilaparvata lugens. HR83 was highly expressed in the fat body and ovary of adult females in chlorpyrifos-resistant BPHs. Knockdown of HR83 by RNA interference showed no effect on female fecundity, whereas caused a decrease of resistance to chlorpyrifos. This treatment also led to a dramatic reduction in the expression of multiple detoxification genes, including four UDP-glycosyltransferases (UGTs), three cytochrome P450 monooxygenases (P450s) and four carboxylesterases (CarEs). Among these HR83-regulated genes, UGT-1-3, UGT-2B10, CYP6CW1, CYP4CE1, CarE and Esterase E4-1 were over-expressed both in the fat body and ovary of the resistant BPHs. Functional analyses revealed that UGT-2B10, CYP4CE1, CarE and Esterase E4-1 are essential for the resistance of BPH to chlorpyrifos. Generally, this study implicates HR83 in the metabolic detoxification-mediated chlorpyrifos resistance and suggests that the regulation of detoxification genes may be an ancestral function of the NR2E nuclear receptor subfamily.
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Affiliation(s)
- Kai Lu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yimin Li
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yibei Cheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wenru Li
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yuanyuan Song
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Rensen Zeng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zhongxiang Sun
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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9
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Charest J, Daniele T, Wang J, Bykov A, Mandlbauer A, Asparuhova M, Röhsner J, Gutiérrez-Pérez P, Cochella L. Combinatorial Action of Temporally Segregated Transcription Factors. Dev Cell 2020; 55:483-499.e7. [PMID: 33002421 PMCID: PMC7704111 DOI: 10.1016/j.devcel.2020.09.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/30/2020] [Accepted: 09/01/2020] [Indexed: 01/05/2023]
Abstract
Combinatorial action of transcription factors (TFs) with partially overlapping expression is a widespread strategy to generate novel gene-expression patterns and, thus, cellular diversity. Known mechanisms underlying combinatorial activity require co-expression of TFs within the same cell. Here, we describe the mechanism by which two TFs that are never co-expressed generate a new, intersectional expression pattern in C. elegans embryos: lineage-specific priming of a gene by a transiently expressed TF generates a unique intersection with a second TF acting on the same gene four cell divisions later; the second TF is expressed in multiple cells but only activates transcription in those where priming occurred. Early induction of active transcription is necessary and sufficient to establish a competent state, maintained by broadly expressed regulators in the absence of the initial trigger. We uncover additional cells diversified through this mechanism. Our findings define a mechanism for combinatorial TF activity with important implications for generation of cell-type diversity. Lineage-specific priming enables asymmetric gene expression in L/R neuron pairs Transient, lineage-specific TFs prime a locus for later activation by a bilateral TF An early active transcriptional state is necessary and sufficient for priming Maintenance of asymmetric primed state occurs in a symmetric regulatory environment
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Affiliation(s)
- Julien Charest
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Thomas Daniele
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Jingkui Wang
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Aleksandr Bykov
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Ariane Mandlbauer
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Mila Asparuhova
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Josef Röhsner
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Paula Gutiérrez-Pérez
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Luisa Cochella
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria.
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10
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Modular Organization of Cis-regulatory Control Information of Neurotransmitter Pathway Genes in Caenorhabditis elegans. Genetics 2020; 215:665-681. [PMID: 32444379 DOI: 10.1534/genetics.120.303206] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 05/20/2020] [Indexed: 11/18/2022] Open
Abstract
We explore here the cis-regulatory logic that dictates gene expression in specific cell types in the nervous system. We focus on a set of eight genes involved in the synthesis, transport, and breakdown of three neurotransmitter systems: acetylcholine (unc-17 /VAChT, cha-1 /ChAT, cho-1 /ChT, and ace-2 /AChE), glutamate (eat-4 /VGluT), and γ-aminobutyric acid (unc-25 /GAD, unc-46 /LAMP, and unc-47 /VGAT). These genes are specifically expressed in defined subsets of cells in the nervous system. Through transgenic reporter gene assays, we find that the cellular specificity of expression of all of these genes is controlled in a modular manner through distinct cis-regulatory elements, corroborating the previously inferred piecemeal nature of specification of neurotransmitter identity. This modularity provides the mechanistic basis for the phenomenon of "phenotypic convergence," in which distinct regulatory pathways can generate similar phenotypic outcomes (i.e., the acquisition of a specific neurotransmitter identity) in different neuron classes. We also identify cases of enhancer pleiotropy, in which the same cis-regulatory element is utilized to control gene expression in distinct neuron types. We engineered a cis-regulatory allele of the vesicular acetylcholine transporter, unc-17 /VAChT, to assess the functional contribution of a "shadowed" enhancer. We observed a selective loss of unc-17 /VAChT expression in one cholinergic pharyngeal pacemaker motor neuron class and a behavioral phenotype that matches microsurgical removal of this neuron. Our analysis illustrates the value of understanding cis-regulatory information to manipulate gene expression and control animal behavior.
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Leyva-Díaz E, Hobert O. Transcription factor autoregulation is required for acquisition and maintenance of neuronal identity. Development 2019; 146:146/13/dev177378. [PMID: 31227642 DOI: 10.1242/dev.177378] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/13/2019] [Indexed: 01/02/2023]
Abstract
The expression of transcription factors that initiate the specification of a unique cellular identity in multicellular organisms is often maintained throughout the life of the respective cell type via an autoregulatory mechanism. It is generally assumed that such autoregulation serves to maintain the differentiated state of a cell. To experimentally test this assumption, we used CRISPR/Cas9-mediated genome engineering to delete a transcriptional autoregulatory, cis-acting motif in the che-1 zinc-finger transcription factor locus, a terminal selector required to specify the identity of the ASE neuron pair during embryonic development of the nematode Caenorhabditis elegans. We show that che-1 autoregulation is indeed required to maintain the differentiated state of the ASE neurons but that it is also required to amplify che-1 expression during embryonic development to reach an apparent minimal threshold to initiate the ASE differentiation program. We conclude that transcriptional autoregulation fulfills two intrinsically linked purposes: one in proper initiation, the other in proper maintenance of terminal differentiation programs.This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Eduardo Leyva-Díaz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
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12
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Park EC, Rongo C. RPM-1 and DLK-1 regulate pioneer axon outgrowth by controlling Wnt signaling. Development 2018; 145:dev.164897. [PMID: 30093552 DOI: 10.1242/dev.164897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/27/2018] [Indexed: 11/20/2022]
Abstract
Axons must correctly reach their targets for proper nervous system function, although we do not fully understand the underlying mechanism, particularly for the first 'pioneer' axons. In C. elegans, AVG is the first neuron to extend an axon along the ventral midline, and this pioneer axon facilitates the proper extension and guidance of follower axons that comprise the ventral nerve cord. Here, we show that the ubiquitin ligase RPM-1 prevents the overgrowth of the AVG axon by repressing the activity of the DLK-1/p38 MAPK pathway. Unlike in damaged neurons, where this pathway activates CEBP-1, we find that RPM-1 and the DLK-1 pathway instead regulate the response to extracellular Wnt cues in developing AVG axons. The Wnt LIN-44 promotes the posterior growth of the AVG axon. In the absence of RPM-1 activity, AVG becomes responsive to a different Wnt, EGL-20, through a mechanism that appears to be independent of canonical Fz-type receptors. Our results suggest that RPM-1 and the DLK-1 pathway regulate axon guidance and growth by preventing Wnt signaling crosstalk.
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Affiliation(s)
- Eun Chan Park
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Christopher Rongo
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ 08854, USA
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13
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Bodofsky S, Koitz F, Wightman B. CONSERVED AND EXAPTED FUNCTIONS OF NUCLEAR RECEPTORS IN ANIMAL DEVELOPMENT. NUCLEAR RECEPTOR RESEARCH 2017; 4:101305. [PMID: 29333434 PMCID: PMC5761748 DOI: 10.11131/2017/101305] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The nuclear receptor gene family includes 18 members that are broadly conserved among multiple disparate animal phyla, indicating that they trace their evolutionary origins to the time at which animal life arose. Typical nuclear receptors contain two major domains: a DNA-binding domain and a C-terminal domain that may bind a lipophilic hormone. Many of these nuclear receptors play varied roles in animal development, including coordination of life cycle events and cellular differentiation. The well-studied genetic model systems of Drosophila, C. elegans, and mouse permit an evaluation of the extent to which nuclear receptor function in development is conserved or exapted (repurposed) over animal evolution. While there are some specific examples of conserved functions and pathways, there are many clear examples of exaptation. Overall, the evolutionary theme of exaptation appears to be favored over strict functional conservation. Despite strong conservation of DNA-binding domain sequences and activity, the nuclear receptors prove to be highly-flexible regulators of animal development.
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Affiliation(s)
- Shari Bodofsky
- Biology Department, Muhlenberg College, 2400 Chew St., Allentown, PA 18104
| | - Francine Koitz
- Biology Department, Muhlenberg College, 2400 Chew St., Allentown, PA 18104
| | - Bruce Wightman
- Biology Department, Muhlenberg College, 2400 Chew St., Allentown, PA 18104
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14
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Gendrel M, Atlas EG, Hobert O. A cellular and regulatory map of the GABAergic nervous system of C. elegans. eLife 2016; 5. [PMID: 27740909 PMCID: PMC5065314 DOI: 10.7554/elife.17686] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 08/22/2016] [Indexed: 12/16/2022] Open
Abstract
Neurotransmitter maps are important complements to anatomical maps and represent an invaluable resource to understand nervous system function and development. We report here a comprehensive map of neurons in the C. elegans nervous system that contain the neurotransmitter GABA, revealing twice as many GABA-positive neuron classes as previously reported. We define previously unknown glia-like cells that take up GABA, as well as 'GABA uptake neurons' which do not synthesize GABA but take it up from the extracellular environment, and we map the expression of previously uncharacterized ionotropic GABA receptors. We use the map of GABA-positive neurons for a comprehensive analysis of transcriptional regulators that define the GABA phenotype. We synthesize our findings of specification of GABAergic neurons with previous reports on the specification of glutamatergic and cholinergic neurons into a nervous system-wide regulatory map which defines neurotransmitter specification mechanisms for more than half of all neuron classes in C. elegans. DOI:http://dx.doi.org/10.7554/eLife.17686.001
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Affiliation(s)
- Marie Gendrel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Emily G Atlas
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
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15
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Hobert O. A map of terminal regulators of neuronal identity in Caenorhabditis elegans. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2016; 5:474-98. [PMID: 27136279 PMCID: PMC4911249 DOI: 10.1002/wdev.233] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 02/07/2016] [Accepted: 02/21/2016] [Indexed: 12/31/2022]
Abstract
Our present day understanding of nervous system development is an amalgam of insights gained from studying different aspects and stages of nervous system development in a variety of invertebrate and vertebrate model systems, with each model system making its own distinctive set of contributions. One aspect of nervous system development that has been among the most extensively studied in the nematode Caenorhabditis elegans is the nature of the gene regulatory programs that specify hardwired, terminal cellular identities. I first summarize a number of maps (anatomical, functional, and molecular) that describe the terminal identity of individual neurons in the C. elegans nervous system. I then provide a comprehensive summary of regulatory factors that specify terminal identities in the nervous system, synthesizing these past studies into a regulatory map of cellular identities in the C. elegans nervous system. This map shows that for three quarters of all neurons in the C. elegans nervous system, regulatory factors that control terminal identity features are known. In-depth studies of specific neuron types have revealed that regulatory factors rarely act alone, but rather act cooperatively in neuron-type specific combinations. In most cases examined so far, distinct, biochemically unlinked terminal identity features are coregulated via cooperatively acting transcription factors, termed terminal selectors, but there are also cases in which distinct identity features are controlled in a piecemeal fashion by independent regulatory inputs. The regulatory map also illustrates that identity-defining transcription factors are reemployed in distinct combinations in different neuron types. However, the same transcription factor can drive terminal differentiation in neurons that are unrelated by lineage, unrelated by function, connectivity and neurotransmitter deployment. Lastly, the regulatory map illustrates the preponderance of homeodomain transcription factors in the control of terminal identities, suggesting that these factors have ancient, phylogenetically conserved roles in controlling terminal neuronal differentiation in the nervous system. WIREs Dev Biol 2016, 5:474-498. doi: 10.1002/wdev.233 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA
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16
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Matus DQ, Lohmer LL, Kelley LC, Schindler AJ, Kohrman AQ, Barkoulas M, Zhang W, Chi Q, Sherwood DR. Invasive Cell Fate Requires G1 Cell-Cycle Arrest and Histone Deacetylase-Mediated Changes in Gene Expression. Dev Cell 2016; 35:162-74. [PMID: 26506306 DOI: 10.1016/j.devcel.2015.10.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/01/2015] [Accepted: 10/02/2015] [Indexed: 12/19/2022]
Abstract
Despite critical roles in development and cancer, the mechanisms that specify invasive cellular behavior are poorly understood. Through a screen of transcription factors in Caenorhabditis elegans, we identified G1 cell-cycle arrest as a precisely regulated requirement of the anchor cell (AC) invasion program. We show that the nuclear receptor nhr-67/tlx directs the AC into G1 arrest in part through regulation of the cyclin-dependent kinase inhibitor cki-1. Loss of nhr-67 resulted in non-invasive, mitotic ACs that failed to express matrix metalloproteinases or actin regulators and lack invadopodia, F-actin-rich membrane protrusions that facilitate invasion. We further show that G1 arrest is necessary for the histone deacetylase HDA-1, a key regulator of differentiation, to promote pro-invasive gene expression and invadopodia formation. Together, these results suggest that invasive cell fate requires G1 arrest and that strategies targeting both G1-arrested and actively cycling cells may be needed to halt metastatic cancer.
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Affiliation(s)
- David Q Matus
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA; Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
| | - Lauren L Lohmer
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
| | - Laura C Kelley
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
| | - Adam J Schindler
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
| | - Abraham Q Kohrman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Michalis Barkoulas
- Department of Life Sciences, Imperial College London, Imperial College Road SAF Building, London SW7 2AZ, UK
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Qiuyi Chi
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
| | - David R Sherwood
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA.
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Davis GM, Haas MA, Pocock R. MicroRNAs: Not "Fine-Tuners" but Key Regulators of Neuronal Development and Function. Front Neurol 2015; 6:245. [PMID: 26635721 PMCID: PMC4656843 DOI: 10.3389/fneur.2015.00245] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 11/09/2015] [Indexed: 12/21/2022] Open
Abstract
MicroRNAs (miRNAs) are a class of short non-coding RNAs that operate as prominent post-transcriptional regulators of eukaryotic gene expression. miRNAs are abundantly expressed in the brain of most animals and exert diverse roles. The anatomical and functional complexity of the brain requires the precise coordination of multilayered gene regulatory networks. The flexibility, speed, and reversibility of miRNA function provide precise temporal and spatial gene regulatory capabilities that are crucial for the correct functioning of the brain. Studies have shown that the underlying molecular mechanisms controlled by miRNAs in the nervous systems of invertebrate and vertebrate models are remarkably conserved in humans. We endeavor to provide insight into the roles of miRNAs in the nervous systems of these model organisms and discuss how such information may be used to inform regarding diseases of the human brain.
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Affiliation(s)
- Gregory M. Davis
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Matilda A. Haas
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Roger Pocock
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
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Thomas AL, Davis SM, Dierick HA. Of Fighting Flies, Mice, and Men: Are Some of the Molecular and Neuronal Mechanisms of Aggression Universal in the Animal Kingdom? PLoS Genet 2015; 11:e1005416. [PMID: 26312756 PMCID: PMC4551476 DOI: 10.1371/journal.pgen.1005416] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Aggressive behavior is widespread in the animal kingdom, but the degree of molecular conservation between distantly related species is still unclear. Recent reports suggest that at least some of the molecular mechanisms underlying this complex behavior in flies show remarkable similarities with such mechanisms in mice and even humans. Surprisingly, some aspects of neuronal control of aggression also show remarkable similarity between these distantly related species. We will review these recent findings, address the evolutionary implications, and discuss the potential impact for our understanding of human diseases characterized by excessive aggression.
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Affiliation(s)
- Amanda L. Thomas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shaun M. Davis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Herman A. Dierick
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Kim J, Yeon J, Choi SK, Huh YH, Fang Z, Park SJ, Kim MO, Ryoo ZY, Kang K, Kweon HS, Jeon WB, Li C, Kim K. The Evolutionarily Conserved LIM Homeodomain Protein LIM-4/LHX6 Specifies the Terminal Identity of a Cholinergic and Peptidergic C. elegans Sensory/Inter/Motor Neuron-Type. PLoS Genet 2015; 11:e1005480. [PMID: 26305787 PMCID: PMC4549117 DOI: 10.1371/journal.pgen.1005480] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 07/31/2015] [Indexed: 02/01/2023] Open
Abstract
The expression of specific transcription factors determines the differentiated features of postmitotic neurons. However, the mechanism by which specific molecules determine neuronal cell fate and the extent to which the functions of transcription factors are conserved in evolution are not fully understood. In C. elegans, the cholinergic and peptidergic SMB sensory/inter/motor neurons innervate muscle quadrants in the head and control the amplitude of sinusoidal movement. Here we show that the LIM homeobox protein LIM-4 determines neuronal characteristics of the SMB neurons. In lim-4 mutant animals, expression of terminal differentiation genes, such as the cholinergic gene battery and the flp-12 neuropeptide gene, is completely abolished and thus the function of the SMB neurons is compromised. LIM-4 activity promotes SMB identity by directly regulating the expression of the SMB marker genes via a distinct cis-regulatory motif. Two human LIM-4 orthologs, LHX6 and LHX8, functionally substitute for LIM-4 in C. elegans. Furthermore, C. elegans LIM-4 or human LHX6 can induce cholinergic and peptidergic characteristics in the human neuronal cell lines. Our results indicate that the evolutionarily conserved LIM-4/LHX6 homeodomain proteins function in generation of precise neuronal subtypes.
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Affiliation(s)
- Jinmahn Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Jihye Yeon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Seong-Kyoon Choi
- Laboratory of Biochemistry and Cellular Engineering, Division of NanoBio Technology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Yang Hoon Huh
- Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute, Daejeon, Korea
| | - Zi Fang
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Seo Jin Park
- School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), School of Animal BT Science, College of Natural Sciences, Kyungpook National University, Daegu, Korea
| | - Myoung Ok Kim
- School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), School of Animal BT Science, College of Natural Sciences, Kyungpook National University, Daegu, Korea
| | - Zae Young Ryoo
- School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), School of Animal BT Science, College of Natural Sciences, Kyungpook National University, Daegu, Korea
| | - Kyeongjin Kang
- Department of Anatomy and Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan School of Medicine, Gyeonggi-Do, Korea
| | - Hee-Seok Kweon
- Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute, Daejeon, Korea
| | - Won Bae Jeon
- Laboratory of Biochemistry and Cellular Engineering, Division of NanoBio Technology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Chris Li
- Department of Biology, City College of the City University of New York, New York, New York, United States of America
| | - Kyuhyung Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
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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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Hobert O. Development of left/right asymmetry in the Caenorhabditis elegans nervous system: From zygote to postmitotic neuron. Genesis 2014; 52:528-43. [DOI: 10.1002/dvg.22747] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/23/2014] [Accepted: 01/28/2014] [Indexed: 01/23/2023]
Affiliation(s)
- Oliver Hobert
- Department of Biochemistry and Molecular Biophysics; Howard Hughes Medical Institute, Columbia University Medical Center; New York New York
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22
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Cochella L, Tursun B, Hsieh YW, Galindo S, Johnston RJ, Chuang CF, Hobert O. Two distinct types of neuronal asymmetries are controlled by the Caenorhabditis elegans zinc finger transcription factor die-1. Genes Dev 2013; 28:34-43. [PMID: 24361693 PMCID: PMC3894411 DOI: 10.1101/gad.233643.113] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Left/right asymmetric features of the body are either randomly distributed on either the left or right side within a population (antisymmetries) or found on one particular side (directional asymmetries). Nervous systems display both types of asymmetries, but it is unknown whether shared regulators establish them. Here, Cochella et al. show that the transcription factor die-1 controls both antisymmetry and directional asymmetry in distinct sensory systems in C. elegans. This study uncovers the first molecular link between two different kinds of body plan asymmetries. Left/right asymmetric features of animals are either randomly distributed on either the left or right side within a population (“antisymmetries”) or found stereotypically on one particular side of an animal (“directional asymmetries”). Both types of asymmetries can be found in nervous systems, but whether the regulatory programs that establish these asymmetries share any mechanistic features is not known. We describe here an unprecedented molecular link between these two types of asymmetries in Caenorhabditis elegans. The zinc finger transcription factor die-1 is expressed in a directionally asymmetric manner in the gustatory neuron pair ASE left (ASEL) and ASE right (ASER), while it is expressed in an antisymmetric manner in the olfactory neuron pair AWC left (AWCL) and AWC right (AWCR). Asymmetric die-1 expression is controlled in a fundamentally distinct manner in these two neuron pairs. Importantly, asymmetric die-1 expression controls the directionally asymmetric expression of gustatory receptor proteins in the ASE neurons and the antisymmetric expression of olfactory receptor proteins in the AWC neurons. These asymmetries serve to increase the ability of the animal to discriminate distinct chemosensory inputs.
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Affiliation(s)
- Luisa Cochella
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York 10032, USA
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23
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Cochella L, Hobert O. Embryonic priming of a miRNA locus predetermines postmitotic neuronal left/right asymmetry in C. elegans. Cell 2012. [PMID: 23201143 DOI: 10.1016/j.cell.2012.10.049] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The mechanisms by which functional left/right asymmetry arises in morphologically symmetric nervous systems are poorly understood. Here, we provide a mechanistic framework for how functional asymmetry in a postmitotic neuron pair is specified in C. elegans. A key feature of this mechanism is a temporally separated, two-step activation of the lsy-6 miRNA locus. The lsy-6 locus is first "primed" by chromatin decompaction in the precursor for the left neuron, but not the right neuron, several divisions before the neurons are born. lsy-6 expression is then "boosted" to functionally relevant levels several divisions later in the mother of the left neuron, through the activity of a bilaterally expressed transcription factor that can only activate lsy-6 in the primed neuron. This study shows how cells can become committed during early developmental stages to execute a specific fate much later in development and provides a conceptual framework for understanding the generation of neuronal diversity.
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Affiliation(s)
- Luisa Cochella
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, NY 10032, USA.
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24
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Weber KP, Alvaro CG, Baer GM, Reinert K, Cheng G, Clever S, Wightman B. Analysis of C. elegans NR2E nuclear receptors defines three conserved clades and ligand-independent functions. BMC Evol Biol 2012; 12:81. [PMID: 22690911 PMCID: PMC3517510 DOI: 10.1186/1471-2148-12-81] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 05/31/2012] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The nuclear receptors (NRs) are an important class of transcription factors that are conserved across animal phyla. Canonical NRs consist of a DNA-binding domain (DBD) and ligand-binding domain (LBD). While most animals have 20-40 NRs, nematodes of the genus Caenorhabditis have experienced a spectacular proliferation and divergence of NR genes. The LBDs of evolutionarily-conserved Caenorhabditis NRs have diverged sharply from their Drosophila and vertebrate orthologs, while the DBDs have been strongly conserved. The NR2E family of NRs play critical roles in development, especially in the nervous system. In this study, we explore the phylogenetics and function of the NR2E family of Caenorhabditis elegans, using an in vivo assay to test LBD function. RESULTS Phylogenetic analysis reveals that the NR2E family of NRs consists of three broadly-conserved clades of orthologous NRs. In C. elegans, these clades are defined by nhr-67, fax-1 and nhr-239. The vertebrate orthologs of nhr-67 and fax-1 are Tlx and PNR, respectively. While the nhr-239 clade includes orthologs in insects (Hr83), an echinoderm, and a hemichordate, the gene appears to have been lost from vertebrate lineages. The C. elegans and C. briggsae nhr-239 genes have an apparently-truncated and highly-diverged LBD region. An additional C. elegans NR2E gene, nhr-111, appears to be a recently-evolved paralog of fax-1; it is present in C. elegans, but not C. briggsae or other animals with completely-sequenced genomes. Analysis of the relatively unstudied nhr-111 and nhr-239 genes demonstrates that they are both expressed--nhr-111 very broadly and nhr-239 in a small subset of neurons. Analysis of the FAX-1 LBD in an in vivo assay revealed that it is not required for at least some developmental functions. CONCLUSIONS Our analysis supports three conserved clades of NR2E receptors, only two of which are represented in vertebrates, indicating three ancestral NR2E genes in the urbilateria. The lack of a requirement for a FAX-1 LBD suggests that the relatively high level of sequence divergence for Caenorhabditis LBDs reflects relaxed selection on the primary sequence as opposed to divergent positive selection. This observation is consistent with a model in which divergence of some Caenorhabditis LBDs is allowed, at least in part, by the absence of a ligand requirement.
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Affiliation(s)
| | | | - G Michael Baer
- Biology Department, Muhlenberg College, Allentown, PA, 18104, USA
| | - Kristy Reinert
- Biology Department, Muhlenberg College, Allentown, PA, 18104, USA
| | - Genevieve Cheng
- Biology Department, Muhlenberg College, Allentown, PA, 18104, USA
| | - Sheila Clever
- Biology Department, Muhlenberg College, Allentown, PA, 18104, USA
| | - Bruce Wightman
- Biology Department, Muhlenberg College, Allentown, PA, 18104, USA
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25
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Murray JI, Boyle TJ, Preston E, Vafeados D, Mericle B, Weisdepp P, Zhao Z, Bao Z, Boeck M, Waterston RH. Multidimensional regulation of gene expression in the C. elegans embryo. Genome Res 2012; 22:1282-94. [PMID: 22508763 PMCID: PMC3396369 DOI: 10.1101/gr.131920.111] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
How cells adopt different expression patterns is a fundamental question of developmental biology. We quantitatively measured reporter expression of 127 genes, primarily transcription factors, in every cell and with high temporal resolution in C. elegans embryos. Embryonic cells are highly distinct in their gene expression; expression of the 127 genes studied here can distinguish nearly all pairs of cells, even between cells of the same tissue type. We observed recurrent lineage-regulated expression patterns for many genes in diverse contexts. These patterns are regulated in part by the TCF-LEF transcription factor POP-1. Other genes' reporters exhibited patterns correlated with tissue, position, and left–right asymmetry. Sequential patterns both within tissues and series of sublineages suggest regulatory pathways. Expression patterns often differ between embryonic and larval stages for the same genes, emphasizing the importance of profiling expression in different stages. This work greatly expands the number of genes in each of these categories and provides the first large-scale, digitally based, cellular resolution compendium of gene expression dynamics in live animals. The resulting data sets will be a useful resource for future research.
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Affiliation(s)
- John Isaac Murray
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA 98195, USA
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26
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Verghese E, Schocken J, Jacob S, Wimer AM, Royce R, Nesmith JE, Baer GM, Clever S, McCain E, Lakowski B, Wightman B. The tailless ortholog nhr-67 functions in the development of the C. elegans ventral uterus. Dev Biol 2011; 356:516-28. [DOI: 10.1016/j.ydbio.2011.06.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 05/13/2011] [Accepted: 06/04/2011] [Indexed: 12/14/2022]
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27
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Schindler AJ, Sherwood DR. The transcription factor HLH-2/E/Daughterless regulates anchor cell invasion across basement membrane in C. elegans. Dev Biol 2011; 357:380-91. [PMID: 21784067 DOI: 10.1016/j.ydbio.2011.07.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 06/17/2011] [Accepted: 07/07/2011] [Indexed: 10/18/2022]
Abstract
Cell invasion through basement membrane is a specialized cellular behavior critical for many developmental processes and leukocyte trafficking. Invasive cellular behavior is also inappropriately co-opted during cancer progression. Acquisition of an invasive phenotype is accompanied by changes in gene expression that are thought to coordinate the steps of invasion. The transcription factors responsible for these changes in gene expression, however, are largely unknown. C. elegans anchor cell (AC) invasion is a genetically tractable in vivo model of invasion through basement membrane. AC invasion requires the conserved transcription factor FOS-1A, but other transcription factors are thought to act in parallel to FOS-1A to control invasion. Here we identify the transcription factor HLH-2, the C. elegans ortholog of Drosophila Daughterless and vertebrate E proteins, as a regulator of AC invasion. Reduction of HLH-2 function by RNAi or with a hypomorphic allele causes defects in AC invasion. Genetic analysis indicates that HLH-2 has functions outside of the FOS-1A pathway. Using expression analysis, we identify three genes that are transcriptionally regulated by HLH-2: the protocadherin cdh-3, and two genes encoding secreted extracellular matrix proteins, mig-6/papilin and him-4/hemicentin. Further, we show that reduction of HLH-2 function causes defects in polarization of F-actin to the invasive cell membrane, a process required for the AC to generate protrusions that breach the basement membrane. This work identifies HLH-2 as a regulator of the invasive phenotype in the AC, adding to our understanding of the transcriptional networks that control cell invasion.
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28
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A left/right asymmetric neuronal differentiation program is controlled by the Caenorhabditis elegans lsy-27 zinc-finger transcription factor. Genetics 2011; 188:753-9. [PMID: 21555395 PMCID: PMC3176537 DOI: 10.1534/genetics.111.129064] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Functional diversification across the left/right axis is a common feature of many nervous systems. The genetic programs that control left/right asymmetric neuron function and gene expression in the nervous system are, however, poorly understood. We describe here the molecular characterization of two phenotypically similar mutant Caenorhabditis elegans strains in which left/right asymmetric gene expression programs of two gustatory neurons, called ASEL and ASER, are disrupted such that the differentiation program of the ASER neuron is derepressed in the ASEL neuron. We show that in one mutant strain the LIM homeobox gene lim-6 is defective whereas in another strain a novel member of a nematode-specific, fast-evolving family of C2H2 zinc-finger transcription factors, lsy-27, is mutated, as revealed by whole-genome sequencing. lsy-27 is broadly and exclusively expressed in the embryo and acts during the initiation, but not during the maintenance phase of ASE asymmetry control to assist in the initiation of lim-6 expression.
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Strome S. Neuroscience. Toward reprogramming gonads to brains. Science 2011; 331:292-3. [PMID: 21252336 DOI: 10.1126/science.1201288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Susan Strome
- Department of Molecular Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA.
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Nokes EB, Van Der Linden AM, Winslow C, Mukhopadhyay S, Ma K, Sengupta P. Cis-regulatory mechanisms of gene expression in an olfactory neuron type in Caenorhabditis elegans. Dev Dyn 2010; 238:3080-92. [PMID: 19924784 DOI: 10.1002/dvdy.22147] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The generation of cellular diversity is dependent on the precise spatiotemporal regulation of gene expression by both cis- and trans-acting mechanisms. The developmental principles regulating expression of specific gene subsets in individual cell types are not fully understood. Here we define the cis-regulatory mechanisms driving expression of cell-selective and broadly expressed genes in vivo in the AWB olfactory neuron subtype in C. elegans. We identify an element that is necessary to drive expression of neuron-selective chemoreceptor genes in the AWB neurons, and show that this element functions in a context-dependent manner. We find that the expression of broadly expressed sensory neuronal genes in the AWB neurons is regulated by diverse cis- and trans-regulatory mechanisms that act partly in parallel to the pathways governing expression of AWB-selective genes. We further demonstrate that cis-acting mechanisms driving gene expression in the AWB neurons appear to have diverged in related nematode species. Our results provide insights into the cis-regulatory logic driving cell-specific gene expression, and suggest that variations in this logic contribute to the generation of functional diversity.
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Affiliation(s)
- Eva B Nokes
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
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31
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Taylor RW, Hsieh YW, Gamse JT, Chuang CF. Making a difference together: reciprocal interactions in C. elegans and zebrafish asymmetric neural development. Development 2010; 137:681-91. [PMID: 20147373 DOI: 10.1242/dev.038695] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Brain asymmetries are thought to increase neural processing capacity and to prevent interhemispheric conflict. In order to develop asymmetrically, neurons must be specified along the left-right axis, assigned left-side versus right-side identities and differentiate appropriately. In C. elegans and zebrafish, the cellular and molecular mechanisms that lead to neural asymmetries have recently come to light. Here, we consider recent insights into the mechanisms involved in asymmetrical neural development in these two species. Although the molecular details are divergent, both organisms use iterative cell-cell communication to establish left-right neuronal identity.
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Affiliation(s)
- Robert W Taylor
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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Kim K, Kim R, Sengupta P. The HMX/NKX homeodomain protein MLS-2 specifies the identity of the AWC sensory neuron type via regulation of the ceh-36 Otx gene in C. elegans. Development 2010; 137:963-74. [PMID: 20150279 DOI: 10.1242/dev.044719] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The differentiated features of postmitotic neurons are dictated by the expression of specific transcription factors. The mechanisms by which the precise spatiotemporal expression patterns of these factors are regulated are poorly understood. In C. elegans, the ceh-36 Otx homeobox gene is expressed in the AWC sensory neurons throughout postembryonic development, and regulates terminal differentiation of this neuronal subtype. Here, we show that the HMX/NKX homeodomain protein MLS-2 regulates ceh-36 expression specifically in the AWC neurons. Consequently, the AWC neurons fail to express neuron type-specific characteristics in mls-2 mutants. mls-2 is expressed transiently in postmitotic AWC neurons, and directly initiates ceh-36 expression. CEH-36 subsequently interacts with a distinct site in its cis-regulatory sequences to maintain its own expression, and also directly regulates the expression of AWC-specific terminal differentiation genes. We also show that MLS-2 acts in additional neuron types to regulate their development and differentiation. Our analysis describes a transcription factor cascade that defines the unique postmitotic characteristics of a sensory neuron subtype, and provides insights into the spatiotemporal regulatory mechanisms that generate functional diversity in the sensory nervous system.
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Affiliation(s)
- Kyuhyung Kim
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
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Didiano D, Cochella L, Tursun B, Hobert O. Neuron-type specific regulation of a 3'UTR through redundant and combinatorially acting cis-regulatory elements. RNA (NEW YORK, N.Y.) 2010; 16:349-363. [PMID: 20040592 PMCID: PMC2811664 DOI: 10.1261/rna.1931510] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 10/29/2009] [Indexed: 05/28/2023]
Abstract
3' Untranslated region (UTR)-dependent post-transcriptional regulation has emerged as a critical mechanism of controlling gene expression in various physiological contexts, including cellular differentiation events. Here, we examine the regulation of the 3'UTR of the die-1 transcription factor in a single neuron of the nematode C. elegans. This 3'UTR shows the intriguing feature of being differentially regulated across the animal's left/right axis. In the left gustatory neuron, ASEL, in which DIE-1 protein is normally expressed in adult animals, the 3'UTR confers no regulatory information, while in the right gustatory neuron, ASER, where DIE-1 is normally not expressed, this 3'UTR confers negative regulatory information. Here, we systematically analyze the cis-regulatory architecture of the die-1 3'UTR using a transgenic, in vivo assay system. Through extensive mutagenesis and sequence insertions into heterologous 3'UTR contexts, we describe three 25-base-pair (bp) sequence elements that are both required and sufficient to mediate the ASER-specific down-regulation of the die-1 3'UTR. These three 25-bp sequence elements operate in both a redundant and combinatorial manner. Moreover, there are not only redundant elements within the die-1 3'UTR regulating its left/right asymmetric activity but asymmetric 3'UTR regulation is itself redundant with other regulatory mechanisms to achieve asymmetric DIE-1 protein expression and function in ASEL versus ASER. The features of 3'UTR regulation we describe here may apply to some of the vast number of genes in animal genomes whose expression is predicted to be regulated through their 3'UTR.
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Affiliation(s)
- Dominic Didiano
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York,NY 10032, USA
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Kato M, Sternberg PW. The C. elegans tailless/Tlx homolog nhr-67 regulates a stage-specific program of linker cell migration in male gonadogenesis. Development 2009; 136:3907-15. [PMID: 19906858 DOI: 10.1242/dev.035477] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell migration is a common event during organogenesis, yet little is known about how migration is temporally coordinated with organ development. We are investigating stage-specific programs of cell migration using the linker cell (LC), a migratory cell crucial for male gonadogenesis of C. elegans. During the L3 and L4 larval stages of wild-type males, the LC undergoes changes in its position along the migratory route, in transcriptional regulation of the unc-5 netrin receptor and zmp-1 zinc matrix metalloprotease, and in cell morphology. We have identified the tailless homolog nhr-67 as a cell-autonomous, stage-specific regulator of timing in LC migration programs. In nhr-67-deficient animals, each of the L3 and L4 stage changes is either severely delayed or never occurs, yet LC development before the early L3 stage or after the mid-L4 stage occurs with normal timing. We propose that there is a basal migration program utilized throughout LC migration that is modified by stage-specific regulators such as nhr-67.
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Affiliation(s)
- Mihoko Kato
- HHMI and Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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