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Ostalé CM, Azpiazu N, Peropadre A, Martín M, Ruiz-Losada M, López-Varea A, Viales RR, Girardot C, Furlong EEM, de Celis JF. A function of Spalt proteins in heterochromatin organization and maintenance of genomic DNA integrity. Development 2025; 152:dev204258. [PMID: 40326666 PMCID: PMC12091872 DOI: 10.1242/dev.204258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2024] [Accepted: 04/15/2025] [Indexed: 05/07/2025]
Abstract
The conserved Spalt proteins regulate gene expression and cell fate choices during multicellular development, generally acting as transcriptional repressors in different gene regulatory networks. In addition to their roles as DNA sequence-specific transcription factors, Spalt proteins show a consistent localization to heterochromatic regions. Vertebrate Spalt-like proteins can act through the nucleosome remodeling and deacetylase complex to promote closing of open chromatin domains, but their activities also rely on interactions with DNA methyltransferases or with the lysine-specific histone demethylase LSD1, suggesting that they participate in multiple regulatory mechanisms. Here, we describe several consequences of loss of Spalt function in Drosophila cells, including changes in chromatin accessibility, generation of DNA damage, alterations in the localization of chromosomes within the nucleus in the salivary glands and misexpression of transposable elements. We suggest that these effects are related to roles of Spalt proteins in the regulation of heterochromatin formation and chromatin organization. We propose that Drosophila Spalt proteins have two complementary functions, acting as sequence-specific transcriptional repressors on specific target genes and regulating more global gene silencing through the generation or maintenance of heterochromatic domains.
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Affiliation(s)
- Cristina M. Ostalé
- Centro de Biología Molecular ‘Severo Ochoa’, Department of Tissue and Organ Homeostasis, CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Natalia Azpiazu
- Centro de Biología Molecular ‘Severo Ochoa’, Department of Tissue and Organ Homeostasis, CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ana Peropadre
- Department of Biology, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Mercedes Martín
- Centro de Biología Molecular ‘Severo Ochoa’, Department of Tissue and Organ Homeostasis, CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Mireya Ruiz-Losada
- Centro de Biología Molecular ‘Severo Ochoa’, Department of Tissue and Organ Homeostasis, CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ana López-Varea
- Centro de Biología Molecular ‘Severo Ochoa’, Department of Tissue and Organ Homeostasis, CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Rebecca R. Viales
- European Molecular Biology Laboratory, Genome Biology Department, Heidelberg 69117, Germany
| | - Charles Girardot
- European Molecular Biology Laboratory, Genome Biology Department, Heidelberg 69117, Germany
| | - Eileen E. M. Furlong
- European Molecular Biology Laboratory, Genome Biology Department, Heidelberg 69117, Germany
| | - Jose F. de Celis
- Centro de Biología Molecular ‘Severo Ochoa’, Department of Tissue and Organ Homeostasis, CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
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Daniele T, Cury J, Morin MC, Ahier A, Isaia D, Jarriault S. Essential and dual effects of Notch activity on a natural transdifferentiation event. Nat Commun 2025; 16:75. [PMID: 39746948 PMCID: PMC11697417 DOI: 10.1038/s41467-024-55286-8] [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: 04/02/2024] [Accepted: 12/06/2024] [Indexed: 01/04/2025] Open
Abstract
Cell identity can be reprogrammed, naturally or experimentally, albeit with low frequency. Why some cells, but not their neighbours, undergo a cell identity conversion remains unclear. We find that Notch signalling plays a key role to promote natural transdifferentiation in C. elegans hermaphrodites. Endogenous Notch signalling endows a cell with the competence to transdifferentiate by promoting plasticity factors expression (hlh-16/Olig and sem-4/Sall). Strikingly, ectopic Notch can trigger additional transdifferentiation in vivo. However, Notch signalling can both promote and block transdifferentiation depending on its activation timing. Notch only promotes transdifferentiation during an early precise window of opportunity and signal duration must be tightly controlled in time. Our findings emphasise the importance of temporality and dynamics of the underlying molecular events preceding the initiation of natural cell reprogramming. Finally, our results support a model where both an extrinsic signal and the intrinsic cellular context combine to empower a cell with the competence to transdifferentiate.
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Affiliation(s)
- Thomas Daniele
- Department of Development and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U1298, Université de Strasbourg, Illkirch, France
- Vertex Pharmaceuticals (CH) GmbH, Zug, Switzerland
| | - Jeanne Cury
- Department of Development and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U1298, Université de Strasbourg, Illkirch, France
| | - Marie-Charlotte Morin
- Department of Development and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U1298, Université de Strasbourg, Illkirch, France
| | - Arnaud Ahier
- Department of Development and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U1298, Université de Strasbourg, Illkirch, France
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Davide Isaia
- Department of Development and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U1298, Université de Strasbourg, Illkirch, France
- Skyhawk Therapeutics, Basel, Switzerland
| | - Sophie Jarriault
- Department of Development and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U1298, Université de Strasbourg, Illkirch, France.
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Kong JN, Dipon Ghosh D, Savvidis A, Sando SR, Droste R, Robert Horvitz H. Transcriptional landscape of a hypoxia response identifies cell-specific pathways for adaptation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.02.601765. [PMID: 39005398 PMCID: PMC11245032 DOI: 10.1101/2024.07.02.601765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
How the HIF-1 (Hypoxia-Inducible) transcription factor drives and coordinates distinct responses to low oxygen across diverse cell types is poorly understood. We present a multi-tissue single-cell gene-expression atlas of the hypoxia response of the nematode Caenorhabditis elegans . This atlas highlights how cell-type-specific HIF-1 responses overlap and diverge among and within neuronal, intestinal, and muscle tissues. Using the atlas to guide functional analyses of candidate muscle-specific HIF-1 effectors, we discovered that HIF-1 activation drives downregulation of the tspo-1 ( TSPO, Translocator Protein) gene in vulval muscle cells to modulate a hypoxia-driven change in locomotion caused by contraction of body-wall muscle cells. We further showed that in human cardiomyocytes HIF-1 activation decreases levels of TSPO and thereby alters intracellular cholesterol transport and the mitochondrial network. We suggest that TSPO-1 is an evolutionarily conserved mediator of HIF-1-dependent modulation of muscle and conclude that our gene-expression atlas can help reveal how HIF-1 drives cell-specific adaptations to hypoxia.
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Liu J, Murray JI. Mechanisms of lineage specification in Caenorhabditis elegans. Genetics 2023; 225:iyad174. [PMID: 37847877 PMCID: PMC11491538 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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Riva C, Hajduskova M, Gally C, Suman SK, Ahier A, Jarriault S. A natural transdifferentiation event involving mitosis is empowered by integrating signaling inputs with conserved plasticity factors. Cell Rep 2022; 40:111365. [PMID: 36130499 PMCID: PMC9513805 DOI: 10.1016/j.celrep.2022.111365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 04/09/2022] [Accepted: 08/25/2022] [Indexed: 11/03/2022] Open
Abstract
Transdifferentiation, or direct cell reprogramming, is the conversion of one fully differentiated cell type into another. Whether core mechanisms are shared between natural transdifferentiation events when occurring with or without cell division is unclear. We have previously characterized the Y-to-PDA natural transdifferentiation in Caenorhabditis elegans, which occurs without cell division and requires orthologs of vertebrate reprogramming factors. Here, we identify a rectal-to-GABAergic transdifferentiation and show that cell division is required but not sufficient for conversion. We find shared mechanisms, including erasure of the initial identity, which requires the conserved reprogramming factors SEM-4/SALL, SOX-2, CEH-6/OCT, and EGL-5/HOX. We also find three additional and parallel roles of the Wnt signaling pathway: selection of a specific daughter, removal of the initial identity, and imposition of the precise final subtype identity. Our results support a model in which levels and antagonistic activities of SOX-2 and Wnt signaling provide a timer for the acquisition of final identity.
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Affiliation(s)
- Claudia Riva
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, Inserm U 1258, Université de Strasbourg, 67400 Illkirch, France
| | - Martina Hajduskova
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, Inserm U 1258, Université de Strasbourg, 67400 Illkirch, France
| | - Christelle Gally
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, Inserm U 1258, Université de Strasbourg, 67400 Illkirch, France.
| | - Shashi Kumar Suman
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, Inserm U 1258, Université de Strasbourg, 67400 Illkirch, France
| | - Arnaud Ahier
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, Inserm U 1258, Université de Strasbourg, 67400 Illkirch, France
| | - Sophie Jarriault
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, Inserm U 1258, Université de Strasbourg, 67400 Illkirch, France.
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6
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Lorente-Sorolla J, Truchado-Garcia M, Perry KJ, Henry JQ, Grande C. Molecular, phylogenetic and developmental analyses of Sall proteins in bilaterians. EvoDevo 2018; 9:9. [PMID: 29644029 PMCID: PMC5892016 DOI: 10.1186/s13227-018-0096-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 03/17/2018] [Indexed: 11/10/2022] Open
Abstract
Background Sall (Spalt-like) proteins are zinc-finger transcription factors involved in a number of biological processes. They have only been studied in a few model organisms, such as Drosophila melanogaster, Caenorhabditis elegans, Schmidtea mediterranea and some vertebrates. Further taxon sampling is critical to understand the evolution and diversification of this protein and its functional roles in animals. Results Using genome and transcriptome mining, we confirmed the presence of sall genes in a range of additional animal taxa, for which their presence had not yet been described. We show that sall genes are broadly conserved across the Bilateria, and likely appeared in the bilaterian stem lineage. Our analysis of the protein domains shows that the characteristic arrangement of the multiple zinc-finger domains is conserved in bilaterians and may represent the ancient arrangement of this family of transcription factors. We also show the existence of a previously unknown zinc-finger domain. In situ hybridization was used to describe the gene expression patterns in embryonic and larval stages in two species of snails: Crepidula fornicata and Lottia gigantea. In L. gigantea, sall presents maternal expression, although later on the expression is restricted to the A and B quadrants during gastrulation and larval stage. In C. fornicata, sall has no maternal expression and it is expressed mainly in the A, C and D quadrants during blastula stages and in an asymmetric fashion during the larval stage. Discussion Our results suggest that the bilaterian common ancestor had a Sall protein with at least six zinc-finger domains. The evolution of Sall proteins in bilaterians might have occurred mostly as a result of the loss of protein domains and gene duplications leading to diversification. The new evidence complements previous studies in highlighting an important role of Sall proteins in bilaterian development. Our results show maternal expression of sall in the snail L. gigantea, but not C. fornicata. The asymmetric expression shown in the ectoderm of the trochophore larva of snails is probably related to shell/mantle development. The observed sall expression in cephalic tissue in snails and some other bilaterians suggests a possible ancestral role of sall in neural development in bilaterians.
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Affiliation(s)
- José Lorente-Sorolla
- 1Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.,2Present Address: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Truchado-Garcia
- 1Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.,2Present Address: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Kimberly J Perry
- 3Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801 USA
| | - Jonathan Q Henry
- 3Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801 USA
| | - Cristina Grande
- 1Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.,2Present Address: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain.,4Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Darwin, 1; Cantoblanco, 28049 Madrid, Spain
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7
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Shen Q, Shi H, Tian C, Ghai V, Liu J. The C. elegans Spalt-like protein SEM-4 functions through the SoxC transcription factor SEM-2 to promote a proliferative blast cell fate in the postembryonic mesoderm. Dev Biol 2017; 429:335-342. [PMID: 28614700 DOI: 10.1016/j.ydbio.2017.06.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/09/2017] [Accepted: 06/09/2017] [Indexed: 11/29/2022]
Abstract
Proper development of a multicellular organism relies on well-coordinated regulation of cell fate specification, cell proliferation and cell differentiation. The C. elegans postembryonic mesoderm provides a useful system for uncovering factors involved in these processes and for further dissecting their regulatory relationships. The single Spalt-like zinc finger containing protein SEM-4/SALL is known to be involved in specifying the proliferative sex myoblast (SM) fate. We have found that SEM-4/SALL is sufficient to promote the SM fate and that it does so in a cell autonomous manner. We further showed that SEM-4/SALL acts through the SoxC transcription factor SEM-2 to promote the SM fate. SEM-2 is known to promote the SM fate by inhibiting the expression of two BWM-specifying transcription factors. In light of recent findings in mammals showing that Sall4, one of the mammalian homologs of SEM-4, contributes to pluripotency regulation by inhibiting differentiation, our work suggests that the function of SEM-4/SALL proteins in regulating pluripotency versus differentiation appears to be evolutionarily conserved.
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Affiliation(s)
- Qinfang Shen
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, United States
| | - Herong Shi
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, United States
| | - Chenxi Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, United States
| | - Vikas Ghai
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, United States
| | - Jun Liu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, United States.
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Hermosilla VE, Hepp MI, Escobar D, Farkas C, Riffo EN, Castro AF, Pincheira R. Developmental SALL2 transcription factor: a new player in cancer. Carcinogenesis 2017; 38:680-690. [DOI: 10.1093/carcin/bgx036] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 04/11/2017] [Indexed: 11/12/2022] Open
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Martín M, Organista MF, de Celis JF. Structure of developmental gene regulatory networks from the perspective of cell fate-determining genes. Transcription 2016; 7:32-7. [PMID: 26735242 DOI: 10.1080/21541264.2015.1130118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The core of gene regulatory networks (GRNs) is formed by transcription factors (TF) and cis-regulatory modules (CRMs) present in their downstream genes. GRNs have a modular structure in which complex circuitries link TFs to CRMs to generate specific transcriptional outputs. (1) Of particular interest are those GRNs including cell fate-determining genes, as they constitute developmental switches which activity is necessary and sufficient to promote particular cellular fates. Most of the genetic analysis of developmental processes deals with the composition and structure of GRNs acting upstream of cell fate-determining genes, as they are best suited for genetic analysis and molecular deconstruction. More recently, the application of a variety of in vivo, computational and genome-wide approaches is allowing the identification and functional analysis of GRNs acting downstream of cell fate-determining genes. In this review we discuss several examples of GRNs acting upstream and downstream of cell fate-determining genes, including other TFs which activity pervade across both regulatory networks.
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Affiliation(s)
- Mercedes Martín
- a Centro de Biología Molecular "Severo Ochoa," CSIC and Universidad Autónoma de Madrid , Madrid , Spain
| | - María F Organista
- a Centro de Biología Molecular "Severo Ochoa," CSIC and Universidad Autónoma de Madrid , Madrid , Spain
| | - Jose F de Celis
- a Centro de Biología Molecular "Severo Ochoa," CSIC and Universidad Autónoma de Madrid , Madrid , Spain
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10
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Liu WJ, Reece-Hoyes JS, Walhout AJM, Eisenmann DM. Multiple transcription factors directly regulate Hox gene lin-39 expression in ventral hypodermal cells of the C. elegans embryo and larva, including the hypodermal fate regulators LIN-26 and ELT-6. BMC DEVELOPMENTAL BIOLOGY 2014; 14:17. [PMID: 24885717 PMCID: PMC4051164 DOI: 10.1186/1471-213x-14-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 02/27/2014] [Indexed: 01/05/2023]
Abstract
Background Hox genes encode master regulators of regional fate specification during early metazoan development. Much is known about the initiation and regulation of Hox gene expression in Drosophila and vertebrates, but less is known in the non-arthropod invertebrate model system, C. elegans. The C. elegans Hox gene lin-39 is required for correct fate specification in the midbody region, including the Vulval Precursor Cells (VPCs). To better understand lin-39 regulation and function, we aimed to identify transcription factors necessary for lin-39 expression in the VPCs, and in particular sought factors that initiate lin-39 expression in the embryo. Results We used the yeast one-hybrid (Y1H) method to screen for factors that bound to 13 fragments from the lin-39 region: twelve fragments contained sequences conserved between C. elegans and two other nematode species, while one fragment was known to drive reporter gene expression in the early embryo in cells that generate the VPCs. Sixteen transcription factors that bind to eight lin-39 genomic fragments were identified in yeast, and we characterized several factors by verifying their physical interactions in vitro, and showing that reduction of their function leads to alterations in lin-39 levels and lin-39::GFP reporter expression in vivo. Three factors, the orphan nuclear hormone receptor NHR-43, the hypodermal fate regulator LIN-26, and the GATA factor ELT-6 positively regulate lin-39 expression in the embryonic precursors to the VPCs. In particular, ELT-6 interacts with an enhancer that drives GFP expression in the early embryo, and the ELT-6 site we identified is necessary for proper embryonic expression. These three factors, along with the factors ZTF-17, BED-3 and TBX-9, also positively regulate lin-39 expression in the larval VPCs. Conclusions These results significantly expand the number of factors known to directly bind and regulate lin-39 expression, identify the first factors required for lin-39 expression in the embryo, and hint at a positive feedback mechanism involving GATA factors that maintains lin-39 expression in the vulval lineage. This work indicates that, as in other organisms, the regulation of Hox gene expression in C. elegans is complicated, redundant and robust.
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Affiliation(s)
| | | | | | - David M Eisenmann
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21250, USA.
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Jovelin R. Rapid sequence evolution of transcription factors controlling neuron differentiation in Caenorhabditis. Mol Biol Evol 2009; 26:2373-86. [PMID: 19589887 DOI: 10.1093/molbev/msp142] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Whether phenotypic evolution proceeds predominantly through changes in regulatory sequences is a controversial issue in evolutionary genetics. Ample evidence indicates that the evolution of gene regulatory networks via changes in cis-regulatory sequences is an important determinant of phenotypic diversity. However, recent experimental work suggests that the role of transcription factor (TF) divergence in developmental evolution may be underestimated. In order to help understand what levels of constraints are acting on the coding sequence of developmental regulatory genes, evolutionary rates were investigated among 48 TFs required for neuronal development in Caenorhabditis elegans. Allelic variation was then sampled for 28 of these genes within a population of the related species Caenorhabditis remanei. Neuronal TFs are more divergent, both within and between species, than structural genes. TFs affecting different neuronal classes are under different levels of selective constraints. The regulatory genes controlling the differentiation of chemosensory neurons evolve particularly fast and exhibit higher levels of within- and between-species nucleotide variation than TFs required for the development of several neuronal classes and TFs required for motorneuron differentiation. The TFs affecting chemosensory neuron development are also more divergent than chemosensory genes expressed in the neurons they differentiate. These results illustrate that TFs are not as highly constrained as commonly thought and suggest that the role of divergence in developmental regulatory genes during the evolution of gene regulatory networks requires further attention.
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Affiliation(s)
- Richard Jovelin
- Center for Ecology and Evolutionary Biology, University of Oregon, Oregon, USA.
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12
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Kawakami Y, Uchiyama Y, Rodriguez Esteban C, Inenaga T, Koyano-Nakagawa N, Kawakami H, Marti M, Kmita M, Monaghan-Nichols P, Nishinakamura R, Izpisua Belmonte JC. Sall genes regulate region-specific morphogenesis in the mouse limb by modulating Hox activities. Development 2009; 136:585-94. [PMID: 19168674 DOI: 10.1242/dev.027748] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The genetic mechanisms that regulate the complex morphogenesis of generating cartilage elements in correct positions with precise shapes during organogenesis, fundamental issues in developmental biology, are still not well understood. By focusing on the developing mouse limb, we confirm the importance of transcription factors encoded by the Sall gene family in proper limb morphogenesis, and further show that they have overlapping activities in regulating regional morphogenesis in the autopod. Sall1/Sall3 double null mutants exhibit a loss of digit1 as well as a loss or fusion of digit2 and digit3, metacarpals and carpals in the autopod. We show that Sall activity affects different pathways, including the Shh signaling pathway, as well as the Hox network. Shh signaling in the mesenchyme is partially impaired in the Sall mutant limbs. Additionally, our data suggest an antagonism between Sall1-Sall3 and Hoxa13-Hoxd13. We demonstrate that expression of Epha3 and Epha4 is downregulated in the Sall1/Sall3 double null mutants, and, conversely, is upregulated in Hoxa13 and Hoxd13 mutants. Moreover, the expression of Sall1 and Sall3 is upregulated in Hoxa13 and Hoxd13 mutants. Furthermore, by using DNA-binding assays, we show that Sall and Hox compete for a target sequence in the Epha4 upstream region. In conjunction with the Shh pathway, the antagonistic interaction between Hoxa13-Hoxd13 and Sall1-Sall3 in the developing limb may contribute to the fine-tuning of local Hox activity that leads to proper morphogenesis of each cartilage element of the vertebrate autopod.
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Affiliation(s)
- Yasuhiko Kawakami
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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13
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Kuntz SG, Schwarz EM, DeModena JA, De Buysscher T, Trout D, Shizuya H, Sternberg PW, Wold BJ. Multigenome DNA sequence conservation identifies Hox cis-regulatory elements. Genome Res 2008; 18:1955-68. [PMID: 18981268 DOI: 10.1101/gr.085472.108] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To learn how well ungapped sequence comparisons of multiple species can predict cis-regulatory elements in Caenorhabditis elegans, we made such predictions across the large, complex ceh-13/lin-39 locus and tested them transgenically. We also examined how prediction quality varied with different genomes and parameters in our comparisons. Specifically, we sequenced approximately 0.5% of the C. brenneri and C. sp. 3 PS1010 genomes, and compared five Caenorhabditis genomes (C. elegans, C. briggsae, C. brenneri, C. remanei, and C. sp. 3 PS1010) to find regulatory elements in 22.8 kb of noncoding sequence from the ceh-13/lin-39 Hox subcluster. We developed the MUSSA program to find ungapped DNA sequences with N-way transitive conservation, applied it to the ceh-13/lin-39 locus, and transgenically assayed 21 regions with both high and low degrees of conservation. This identified 10 functional regulatory elements whose activities matched known ceh-13/lin-39 expression, with 100% specificity and a 77% recovery rate. One element was so well conserved that a similar mouse Hox cluster sequence recapitulated the native nematode expression pattern when tested in worms. Our findings suggest that ungapped sequence comparisons can predict regulatory elements genome-wide.
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Affiliation(s)
- Steven G Kuntz
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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A Caenorhabditis elegans model for epithelial-neuronal transdifferentiation. Proc Natl Acad Sci U S A 2008; 105:3790-5. [PMID: 18308937 DOI: 10.1073/pnas.0712159105] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding transdifferentiation-the conversion of one differentiated cell type into another-is important from both basic science and clinical perspectives. In Caenorhabditis elegans, an epithelial cell named Y is initially part of the rectum but later appears to withdraw, migrate, and then become a motor neuron named PDA. Here, we show that this represents a bona fide transdifferentiation event: Y has epithelial hallmarks without detectable neural characteristics, and PDA has no residual epithelial characteristics. Using available mutants and laser microsurgery, we found that transdifferentiation does not depend on fusion with a neighboring cell or require migration of Y away from the rectum, that other rectal epithelial cells are not competent to transdifferentiate, and that transdifferentiation requires the EGL-5 and SEM-4 transcription factors and LIN-12/Notch signaling. Our results establish Y-to-PDA transdifferentiation as a genetically tractable model for deciphering the mechanisms underlying cellular plasticity in vivo.
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15
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Abstract
Genetic studies of behavior in the nematode Caenorhabditis elegans have provided an effective approach to investigate the molecular and cellular basis of nervous system function and development. Among the best studied behaviors is egg-laying, the process by which hermaphrodites deposit developing embryos into the environment. Egg-laying involves a simple motor program involving a small network of motorneurons and specialized smooth muscle cells, which is regulated by a variety of sensory stimuli. Analysis of egg-laying-defective mutants has provided insight into a number of conserved processes in nervous system development, including neurogenesis, cell migration, and synaptic patterning, as well as aspects of excitable cell signal transduction and neuromodulation.
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Affiliation(s)
- William F Schafer
- Department of Biology, University of California at San Diego, La Jolla, California 92093-0349, USA.
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16
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Copf T, Rabet N, Averof M. Knockdown of spalt function by RNAi causes de-repression of Hox genes and homeotic transformations in the crustacean Artemia franciscana. Dev Biol 2006; 298:87-94. [PMID: 16934794 DOI: 10.1016/j.ydbio.2006.07.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 07/21/2006] [Accepted: 07/22/2006] [Indexed: 02/04/2023]
Abstract
Hox genes play a central role in the specification of distinct segmental identities in the body of arthropods. The specificity of Hox genes depends on their restricted expression domains, their interaction with specific cofactors and selectivity for particular target genes. spalt genes are associated with the function of Hox genes in diverse species, but the nature of this association varies: in some cases, spalt collaborates with Hox genes to specify segmental identities, in others, it regulates Hox gene expression or acts as their target. Here we study the role of spalt in the branchiopod crustacean Artemia franciscana. We find that Artemia spalt is expressed in the pre-segmental 'growth zone' and in stripes in each of the trunk (thoracic, genital and post-genital) segments that emerge from this zone. Using RNA interference (RNAi), we show that knocking down the expression of spalt has pleiotropic effects, which include thoracic to genital (T-->G), genital to thoracic (G-->T) and post-genital to thoracic (PG-->T) homeotic transformations. These transformations are associated with a stochastic de-repression of Hox genes in the corresponding segments of RNAi-treated animals (AbdB for T-->G and Ubx/AbdA for G-->T and PG-->T transformations). We discuss a possible role of spalt in the maintenance of Hox gene repression in Artemia and in other animals.
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Affiliation(s)
- Tijana Copf
- Institute of Molecular Biology and Biotechnology, 711 10 Iraklio Crete, Greece
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17
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Wagmaister JA, Miley GR, Morris CA, Gleason JE, Miller LM, Kornfeld K, Eisenmann DM. Identification of cis-regulatory elements from the C. elegans Hox gene lin-39 required for embryonic expression and for regulation by the transcription factors LIN-1, LIN-31 and LIN-39. Dev Biol 2006; 297:550-65. [PMID: 16782085 DOI: 10.1016/j.ydbio.2006.05.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 05/03/2006] [Accepted: 05/04/2006] [Indexed: 12/01/2022]
Abstract
Expression of the Caenorhabditis elegans Hox gene lin-39 begins in the embryo and continues in multiple larval cells, including the P cell lineages that generate ventral cord neurons (VCNs) and vulval precursor cells (VPCs). lin-39 is regulated by several factors and by Wnt and Ras signaling pathways; however, no cis-acting sites mediating lin-39 regulation have been identified. Here, we describe three elements controlling lin-39 expression: a 338-bp upstream fragment that directs embryonic expression in P5-P8 and their descendants in the larva, a 247-bp intronic region sufficient for VCN expression, and a 1.3-kb upstream cis-regulatory module that drives expression in the VPC P6.p in a Ras-dependent manner. Three trans-acting factors regulate expression via the 1.3-kb element. A single binding site for the ETS factor LIN-1 mediates repression in VPCs other than P6.p; however, loss of LIN-1 decreases expression in P6.p. Therefore, LIN-1 acts both negatively and positively on lin-39 in different VPCs. The Forkhead domain protein LIN-31 also acts positively on lin-39 in P6.p via this module. Finally, LIN-39 itself binds to this element, suggesting that LIN-39 autoregulates its expression in P6.p. Therefore, we have begun to unravel the cis-acting sites regulating lin-39 Hox gene expression and have shown that lin-39 is a direct target of the Ras pathway acting via LIN-1 and LIN-31.
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Affiliation(s)
- Javier A Wagmaister
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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18
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Photos A, Gutierrez A, Sommer RJ. sem-4/spalt and egl-17/FGF have a conserved role in sex myoblast specification and migration in P. pacificus and C. elegans. Dev Biol 2006; 293:142-53. [PMID: 16515780 DOI: 10.1016/j.ydbio.2006.01.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 01/23/2006] [Accepted: 01/26/2006] [Indexed: 10/24/2022]
Abstract
Evolutionary comparisons between Caenorhabditis elegans and the satellite organism Pristionchus pacificus revealed major differences in the regulation of nematode vulva development. For example, Wnt signaling is part of a negative signaling system that prevents vulva formation in P. pacificus, whereas it plays a positive role in C. elegans. We wondered if the genetic control of the second major part of the nematode egg-laying system, the sex muscles, has diverged similarly between P. pacificus and C. elegans. The sex muscles derive from the mesoblast M, which has an identical lineage in both species. Here, we describe a large-scale mutagenesis screen for mutations that disrupt the M lineage and the sex myoblast (SM) sublineage. We isolated and characterized mutations that result in a failure of proper SM fate specification and SM migration and showed that the corresponding genes encode Ppa-sem-4 and Ppa-egl-17, respectively. Ppa-sem-4 mutants have additional defects in the specification of the vulva precursor cells P(5, 7).p and experimental studies in the Ppa-egl-17 mutant background indicate a complex set of gonad-dependent and gonad-independent mechanisms required for SM migration. Mutations in Cel-sem-4 and Cel-egl-17 cause similar defects. Thus, the molecular mechanisms of SM cell specification and migration are conserved between P. pacificus and C. elegans.
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Affiliation(s)
- Andreas Photos
- Max Planck Institute for Developmental Biology, Department for Evolutionary Biology, Tübingen, Germany
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19
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Wagmaister JA, Gleason JE, Eisenmann DM. Transcriptional upregulation of the C. elegans Hox gene lin-39 during vulval cell fate specification. Mech Dev 2006; 123:135-50. [PMID: 16412617 DOI: 10.1016/j.mod.2005.11.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 11/16/2005] [Accepted: 11/17/2005] [Indexed: 01/22/2023]
Abstract
Extracellular signaling pathways and transcriptional regulatory networks function during development to specify metazoan cell fates. During Caenorhabditis elegans vulval development, the specification of three vulval precursor cells (VPCs) requires the activity of Wnt, Notch, and Ras signaling pathways, and function of the Hox gene lin-39. LIN-39 protein levels are regulated in the VPCs by both Wnt and Ras signaling. In particular, activation of Ras signaling leads to an increase in LIN-39 protein in P6.p at the time of VPC fate specification. We wish to understand the regulation of lin-39 by these pathways. We first show that LIN-39 is a target for MAP kinase in vitro, suggesting that the Ras-dependent LIN-39 upregulation could be mediated post-translationally. To test this idea, we created transcriptional and translational lin-39::GFP fusions that include the entire lin-39 genomic region, allowing observation of lin-39 expression in live animals. The reporters express GFP in most, if not all, sites of expression previously observed by LIN-39 antibody staining. We used these constructs to show that at the time of vulval induction both lin-39::GFP reporters are upregulated in P6.p, indicating that the accumulation of high levels of LIN-39 protein detected previously corresponds to transcriptional upregulation of lin-39 expression. This transcriptional upregulation of lin-39 is dependent on Ras signaling. We tested the requirement for several transcription factors acting downstream of Ras signaling in the VPCs, and found that P6.p upregulation requires the transcription factors LIN-1 and LIN-25, but appears to be independent of LIN-31, SEM-4, EOR-1 and EOR-2.Finally, we found that when the Wnt pathway is over activated, expression from the transcriptional lin-39::GFP increases, suggesting that the Wnt pathway also regulates lin-39 at the transcriptional level.
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Affiliation(s)
- Javier A Wagmaister
- Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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20
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Abstract
The Ras and Notch signaling pathways are used over and over again during development to control many different biological processes. Frequently, these two signaling pathways intersect to influence common processes, but sometimes they cooperate and sometimes they antagonize each other. The Caenorhabditis elegans vulva and the Drosophila eye are two classic paradigms for understanding how Ras and Notch affect cell fates, and how the two pathways work together to control biological pattern. Recent advances in these systems reveal some of the mechanisms by which Ras and Notch can interact. Similar types of interactions in mammals may be important for determining whether and how alterations in Ras or Notch lead to cancer.
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Affiliation(s)
- Meera V Sundaram
- Department of Genetics, University of Pennsylvania, Philadelphia, 19104, USA
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21
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Yang L, Sym M, Kenyon C. The roles of two C. elegans HOX co-factor orthologs in cell migration and vulva development. Development 2005; 132:1413-28. [PMID: 15750187 DOI: 10.1242/dev.01569] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anteroposterior cell migration and patterning in C. elegans are governed by multiple, interacting signaling pathways and transcription factors. In this study, we have investigated the role of ceh-20, the C. elegans ortholog of the HOX co-factor Extradenticle (Exd/Pbx), and unc-62, the C. elegans ortholog of Homothorax (Hth/Meis/Prep), in two processes that are regulated by Hox gene lin-39: cell migration and vulva formation. As in lin-39 mutants, the anterior migrations of neuroblasts in the Q lineage are truncated in Hox co-factor mutants. Surprisingly, though, our findings suggested that the roles of ceh-20 and unc-62 are different from that of lin-39; specifically, ceh-20 and unc-62 but not lin-39 are required for the transmembrane protein MIG-13 to promote anterior migration. To our knowledge, ceh-20 and unc-62 are the only genes that have been implicated in the mig-13 pathway. We find that ceh-20 and unc-62 are also required for several steps in vulva development. Surprisingly, ceh-20 and unc-62 mutants have phenotypes that are starkly different from those of lin-39 mutants. Thus, in this process, too, ceh-20 and unc-62 are likely to have functions that are independent of lin-39.
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Affiliation(s)
- Lucie Yang
- Department of Biochemistry and Biophysics, University of California, San Francisco, Mission Bay Genentech Hall, 600 16th Street, Room S312A, San Francisco, CA 94143-2200, USA
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22
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Koh K, Bernstein Y, Sundaram MV. The nT1 translocation separates vulval regulatory elements from the egl-18 and elt-6 GATA factor genes. Dev Biol 2004; 267:252-63. [PMID: 14975731 DOI: 10.1016/j.ydbio.2003.11.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Revised: 11/12/2003] [Accepted: 11/13/2003] [Indexed: 10/26/2022]
Abstract
egl-18 and elt-6 are partially redundant, adjacent genes encoding GATA factors essential for viability, seam cell development, and vulval development in Caenorhabditis elegans. The nT1 reciprocal translocation causes a strong Vulvaless phenotype, and an nT1 breakpoint was previously mapped to the left arm of LGIV, where egl-18/elt-6 are located. Here we present evidence that the nT1 vulval phenotype is due to a disruption of egl-18/elt-6 function specifically in the vulva. egl-18 mutations do not complement nT1 for vulval defects, and the nT1 breakpoint on LGIV is located within approximately 800 bp upstream of a potential transcriptional start site of egl-18. In addition, we have identified a approximately 350-bp cis-regulatory region sufficient for vulval expression just upstream of the nT1 breakpoint. By examining the fusion state and division patterns of the cells in the developing vulva of nT1 mutants, we demonstrate that egl-18/elt-6 prevent fusion and promote cell proliferation at multiple steps of vulval development.
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Affiliation(s)
- Kyunghee Koh
- Department of Genetics, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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23
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Toker AS, Teng Y, Ferreira HB, Emmons SW, Chalfie M. The Caenorhabditis elegans spalt-like gene sem-4 restricts touch cell fate by repressing the selector Hox gene egl-5 and the effector gene mec-3. Development 2003; 130:3831-40. [PMID: 12835398 DOI: 10.1242/dev.00398] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Members of the spalt (sal) gene family encode zinc-finger proteins that are putative tumor suppressors and regulate anteroposterior (AP) patterning, cellular identity, and, possibly, cell cycle progression. The mechanism through which sal genes carry out these functions is unclear. The Caenorhabditis elegans sal gene sem-4 controls the fate of several different cell types, including neurons, muscle and hypodermis. Mutation of sem-4 transforms particular tail neurons into touch-neuron-like cells. In wild-type C. elegans, six touch receptor neurons mediate the response of the worm to gentle touch. All six touch neurons normally express the LIM homeobox gene mec-3. A subset, the two PLM cells, also express the Hox gene egl-5, an Abdominal-B homolog, which we find is required for correct mec-3 expression in these cells. The abnormal touch-neuron-like-cells in sem-4 animals express mec-3; we show that a subset also express egl-5. We report: (1) that ectopic expression of sem-4 in normal touch cells represses mec-3 expression and reduces touch cell function; (2) that egl-5 expression is required for both the fate of normal PLM touch neurons in wild-type animals and the fate of a subset of abnormal touch neurons in sem-4 animals, and (3) that SEM-4 specifically binds a shared motif in the mec-3 and egl-5 promoters that mediates repression of these genes in cells in the tail. We conclude that sem-4 represses egl-5 and mec-3 through direct interaction with regulatory sequences in the promoters of these genes, that sem-4 indirectly modulates mec-3 expression through its repression of egl-5 and that this negative regulation is required for proper determination of neuronal fates. We suggest that the mechanism and targets of regulation by sem-4 are conserved throughout the sal gene family: other sal genes might regulate patterning and cellular identity through direct repression of Hox selector genes and effector genes.
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Affiliation(s)
- Anne S Toker
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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24
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Abstract
The ability of two or more cells to unite to form a new syncytial cell has been utilized in metazoans throughout evolution to form many complex organs, such as muscles, bones and placentae. This requires migration, recognition and adhesion between cells together with fusion of their plasma membranes and rearrangement of their cytoplasmic contents. Until recently, understanding of the mechanisms of cell fusion was restricted to fusion between enveloped viruses and their target cells. The identification of new factors that take part in developmental cell fusion in C. elegans opens the way to understanding how cells fuse and what the functions of this process are. In this review, we describe current knowledge on the mechanisms and putative roles of developmental cell fusion in C. elegans and how cell fusion is regulated, together with other intercellular processes to promote organogenesis.
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Affiliation(s)
- Gidi Shemer
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
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25
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Shemer G, Podbilewicz B. LIN-39/Hox triggers cell division and represses EFF-1/fusogen-dependent vulval cell fusion. Genes Dev 2002; 16:3136-41. [PMID: 12502736 PMCID: PMC187502 DOI: 10.1101/gad.251202] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
General mechanisms by which Hox genes establish cell fates are known. However, a few Hox effectors mediating cell behaviors have been identified. Here we found the first effector of LIN-39/HoxD4/Dfd in Caenorhabditis elegans. In specific vulval precursor cells (VPCs), LIN-39 represses early and late expression of EFF-1, a membrane protein essential for cell fusion. Repression of eff-1 is also achieved by the activity of CEH-20/Exd/Pbx, a known cofactor of Hox proteins. Unfused VPCs in lin-39(-);eff-1(-) double mutants fail to divide but migrate, executing vulval fates. Thus, lin-39 is essential for inhibition of EFF-1-dependent cell fusion and stimulation of cell proliferation during vulva formation. Supplemental material is available at http://www.genesdev.org.
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Affiliation(s)
- Gidi Shemer
- Department of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
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26
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Koh K, Peyrot SM, Wood CG, Wagmaister JA, Maduro MF, Eisenmann DM, Rothman JH. Cell fates and fusion in theC. elegansvulval primordium are regulated by the EGL-18 and ELT-6 GATA factors — apparent direct targets of the LIN-39 Hox protein. Development 2002; 129:5171-80. [PMID: 12399309 DOI: 10.1242/dev.129.22.5171] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Development of the vulva in C. elegans is mediated by the combinatorial action of several convergent regulatory inputs, three of which,the Ras, Wnt and Rb-related pathways, act by regulating expression of thelin-39 Hox gene. LIN-39 specifies cell fates and regulates cell fusion in the mid-body region, leading to formation of the vulva. In the lateral seam epidermis, differentiation and cell fusion have been shown to be regulated by two GATA-type transcription factors, ELT-5 and -6. We report that ELT-5 is encoded by the egl-18 gene, which was previously shown to promote formation of a functional vulva. Furthermore, we find that EGL-18(ELT-5), and its paralogue ELT-6, are redundantly required to regulate cell fates and fusion in the vulval primordium and are essential to form a vulva. Elimination of egl-18 and elt-6 activity results in arrest by the first larval stage; however, in animals rescued for this larval lethality by expression of ELT-6 in non-vulval cells, the post-embryonic cells(P3.p-P8.p) that normally become vulval precursor cells often fuse with the surrounding epidermal syncytium or undergo fewer than normal cell divisions,reminiscent of lin-39 mutants. Moreover, egl-18/elt-6reporter gene expression in the developing vulva is attenuated inlin-39(rf) mutants, and overexpression of egl-18 can partially rescue the vulval defects caused by reduced lin-39activity. LIN-39/CEH-20 heterodimers bind two consensus HOX/PBC sites in a vulval enhancer region of egl-18/elt-6, one of which is essential for vulval expression of egl-18/elt-6 reporter constructs. These findings demonstrate that the EGL-18 and ELT-6 GATA factors are essential, genetically redundant regulators of cell fates and fusion in the developing vulva and are apparent direct transcriptional targets of the LIN-39 Hox protein.
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Affiliation(s)
- Kyunghee Koh
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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27
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Chen Z, Han M. C. elegans Rb, NuRD, and Ras regulate lin-39-mediated cell fusion during vulval fate specification. Curr Biol 2001; 11:1874-9. [PMID: 11728311 DOI: 10.1016/s0960-9822(01)00596-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The tumor suppressor Rb and the NuRD (nucleosome remodeling and histone deacetylation) complex have been implicated in transcriptional repression during cell cycle progression and cell fate specification. The Rb/E2F complex physically interacts with and thus recruits the NuRD complex to actively repress transcription. Caenorhabditis elegans counterparts of Rb, E2F/DP, and some NuRD complex components appear to function in a common class B synthetic Multivulva (synMuv) pathway to antagonize RTK/Ras signaling during vulval fate specification. Therefore, it has been suggested that they function together in a single complex to repress vulva-specific gene transcription. However, little is known about the in vivo interactions between these class B synMuv genes and their relationships with other pathways in specific cellular processes during vulval development. We show that C. elegans Rb/E2F and NuRD complexes antagonize Ras activity by controlling a lin-39 Hox-mediated cell fusion event that regulates the competence of vulval cells. Interestingly, Rb/E2F and NuRD complexes exhibit very different genetic properties. While the NuRD complex negatively regulates lin-39 Hox activity, likely by downregulating its expression, RB/E2F appears to play dual roles in regulating lin-39: a negative role in controlling its activity and a previously uncharacterized positive role in regulating its expression.
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Affiliation(s)
- Z Chen
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
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28
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Rusten TE, Cantera R, Urban J, Technau G, Kafatos FC, Barrio R. Spalt modifies EGFR-mediated induction of chordotonal precursors in the embryonic PNS of Drosophila promoting the development of oenocytes. Development 2001; 128:711-22. [PMID: 11171396 DOI: 10.1242/dev.128.5.711] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Genes of the spalt family encode nuclear zinc finger proteins. In Drosophila melanogaster, they are necessary for the establishment of head/trunk identity, correct tracheal migration and patterning of the wing imaginal disc. Spalt proteins display a predominant pattern of expression in the nervous system, not only in Drosophila but also in species of fish, mouse, frog and human, suggesting an evolutionarily conserved role for these proteins in nervous system development. Here we show that Spalt works as a cell fate switch between two EGFR-induced cell types, the oenocytes and the precursors of the pentascolopodial organ in the embryonic peripheral nervous system. We show that removal of spalt increases the number of scolopodia, as a result of extra secondary recruitment of precursor cells at the expense of the oenocytes. In addition, the absence of spalt causes defects in the normal migration of the pentascolopodial organ. The dual function of spalt in the development of this organ, recruitment of precursors and migration, is reminiscent of its role in tracheal formation and of the role of a spalt homologue, sem-4, in the Caenorhabditis elegans nervous system.
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Affiliation(s)
- T E Rusten
- European Molecular Biology Laboratory, Meyerhofstrasse, D-69117 Heidelberg, Germany
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29
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Thatcher JD, Fernandez AP, Beaster-Jones L, Haun C, Okkema PG. The Caenorhabditis elegans peb-1 gene encodes a novel DNA-binding protein involved in morphogenesis of the pharynx, vulva, and hindgut. Dev Biol 2001; 229:480-93. [PMID: 11203704 DOI: 10.1006/dbio.2000.9978] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gene expression in the Caenorhabditis elegans pharynx is regulated in part by organ-specific signals, which in the myo-2 gene target a regulatory sequence called the C sub-element. C sub-element activity requires the organ specification factor PHA-4, a winged-helix transcription factor expressed in all pharyngeal cells. To identify additional factors involved in pharyngeal organogenesis, we performed a yeast one-hybrid screen for C sub-element binding proteins. Here we describe the novel factor PEB-1, which is coexpressed with PHA-4 in many pharyngeal cell types, including muscles, epithelial cells, marginal cells, and glands, but is undetectable in the pharyngeal nervous system. PEB-1 is also detected outside the pharynx in cells surrounding the rectum and vulva, as well as in the germ line. Reduction of peb-1 function using RNAi results in morphological defects in the somatic tissues in which peb-1 is expressed. We have mapped the PEB-1 DNA-binding domain to a 158-residue region, which is unrelated to known DNA-binding proteins but shares some sequence similarity to the Drosophila Mod(mdg4) proteins. PEB-1 specifically recognizes a site in the C subelement that partially overlaps the PHA-4 binding site. Both the PEB-1 and the PHA-4 binding sites are necessary for strong C sub-element enhancer activity in some cells in which these factors are coexpressed. In contrast the PEB-1 site is dispensable for C sub-element activity in pharyngeal neurons. We propose that PEB-1 functions with PHA-4 to activate target gene expression in cells in which they are coexpressed.
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Affiliation(s)
- J D Thatcher
- Department of Biological Sciences (M/C 567), University of Illinois at Chicago, 900 S. Ashland Avenue, Chicago, Illinois 60607, USA
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30
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Abstract
The induction of an appropriate cellular response to a stimulus often depends on the intricate interplay between multiple signaling pathways. Recent work utilizing Caenorhabditis elegans has enabled the identification of points of convergence between signaling pathways and permitted the elucidation of how multiple signals work in concert to ensure a proper response.
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Affiliation(s)
- W Hanna-Rose
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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