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Cheng Y, Chan F, Kassis JA. The activity of engrailed imaginal disc enhancers is modulated epigenetically by chromatin and autoregulation. PLoS Genet 2023; 19:e1010826. [PMID: 37967127 PMCID: PMC10686433 DOI: 10.1371/journal.pgen.1010826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 11/29/2023] [Accepted: 10/31/2023] [Indexed: 11/17/2023] Open
Abstract
engrailed (en) encodes a homeodomain transcription factor crucial for the proper development of Drosophila embryos and adults. Like many developmental transcription factors, en expression is regulated by many enhancers, some of overlapping function, that drive expression in spatially and temporally restricted patterns. The en embryonic enhancers are located in discrete DNA fragments that can function correctly in small reporter transgenes. In contrast, the en imaginal disc enhancers (IDEs) do not function correctly in small reporter transgenes. En is expressed in the posterior compartment of wing imaginal discs; in contrast, small IDE-reporter transgenes are expressed mainly in the anterior compartment. We found that En binds to the IDEs and suggest that it may directly repress IDE function and modulate En expression levels. We identified two en IDEs, O and S. Deletion of either of these IDEs from a 79kb HA-en rescue transgene (HAen79) caused a loss-of-function en phenotype when the HAen79 transgene was the sole source of En. In contrast, flies with a deletion of the same IDEs from an endogenous en gene had no phenotype, suggesting a resiliency not seen in the HAen79 rescue transgene. Inserting a gypsy insulator in HAen79 between en regulatory DNA and flanking sequences strengthened the activity of HAen79, giving better function in both the ON and OFF transcriptional states. Altogether our data suggest that the en IDEs stimulate expression in the entire imaginal disc, and that the ON/OFF state is set by epigenetic memory set by the embryonic enhancers. This epigenetic regulation is similar to that of the Ultrabithorax IDEs and we suggest that the activity of late-acting enhancers in other genes may be similarly regulated.
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Affiliation(s)
- Yuzhong Cheng
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Fountane Chan
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Judith A. Kassis
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
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2
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Cheng Y, Chan F, Kassis JA. The activity of engrailed imaginal disc enhancers is modulated epigenetically by chromatin and autoregulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.15.545191. [PMID: 37502849 PMCID: PMC10370174 DOI: 10.1101/2023.06.15.545191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
engrailed (en) encodes a homeodomain transcription factor crucial for the proper development of Drosophila embryos and adults. Like many developmental transcription factors, en expression is regulated by many enhancers, some of overlapping function, that drive expression in spatially and temporally restricted patterns. The en embryonic enhancers are located in discrete DNA fragments that can function correctly in small reporter transgenes. In contrast, the en imaginal disc enhancers (IDEs) do not function correctly in small reporter transgenes. En is expressed in the posterior compartment of wing imaginal disks; small IDE-reporter transgenes are expressed in the anterior compartment, the opposite of what is expected. Our data show that the En protein binds to en IDEs, and we suggest that En directly represses IDE function. We identified two en IDEs, 'O' and 'S'. Deletion of either of these IDEs from a 79kb HA-en rescue transgene (HAen79) caused a loss-of-function en phenotype when the HAen79 transgene was the sole source of En. In contrast, flies with a deletion of the same IDEs from the endogenous en gene had no phenotype, suggesting a resiliency not seen in the HAen79 rescue transgene. Inserting a gypsy insulator in HAen79 between en regulatory DNA and flanking sequences strengthened the activity of HAen79, giving better function in both the ON and OFF transcriptional states. Altogether our data show that the en IDEs stimulate expression in the entire imaginal disc, and that the ON/OFF state is set by epigenetic regulators. Further, the endogenous locus imparts a stability to en function not seen even in a large transgene, reflecting the importance of both positive and negative epigenetic influences that act over relatively large distances in chromatin.
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Affiliation(s)
- Yuzhong Cheng
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Fountane Chan
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Judith A Kassis
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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3
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Tumorigenesis and cell competition in Drosophila in the absence of polyhomeotic function. Proc Natl Acad Sci U S A 2021; 118:2110062118. [PMID: 34702735 DOI: 10.1073/pnas.2110062118] [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] [Accepted: 09/21/2021] [Indexed: 12/12/2022] Open
Abstract
Cell competition is a homeostatic process that eliminates by apoptosis unfit or undesirable cells from animal tissues, including tumor cells that appear during the life of the organism. In Drosophila there is evidence that many types of oncogenic cells are eliminated by cell competition. One exception is cells mutant for polyhomeotic (ph), a member of the Polycomb family of genes; most of the isolated mutant ph clones survive and develop tumorous overgrowths in imaginal discs. To characterize the tumorigenic effect of the lack of ph, we first studied the growth of different regions of the wing disc deficient in ph activity and found that the effect is restricted to the proximal appendage. Moreover, we found that ph-deficient tissue is partially refractory to apoptosis. Second, we analyzed the behavior of clones lacking ph function and found that many suffer cell competition but are not completely eliminated. Unexpectedly, we found that nonmutant cells also undergo cell competition when surrounded by ph-deficient cells, indicating that within the same tissue cell competition may operate in opposite directions. We suggest two reasons for the incompleteness of cell competition in ph mutant cells: 1) These cells are partially refractory to apoptosis, and 2) the loss of ph function alters the identity of imaginal cells and subsequently their cell affinities. It compromises the winner/loser interaction, a prerequisite for cell competition.
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Beira JV, Torres J, Paro R. Signalling crosstalk during early tumorigenesis in the absence of Polycomb silencing. PLoS Genet 2018; 14:e1007187. [PMID: 29357360 PMCID: PMC5794193 DOI: 10.1371/journal.pgen.1007187] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/01/2018] [Accepted: 01/04/2018] [Indexed: 12/19/2022] Open
Abstract
In response to stress and injury a coordinated activation of conserved signalling modules, such as JNK and JAK/STAT, is critical to trigger regenerative tissue restoration. While these pathways rebuild homeostasis and promote faithful organ recovery, it is intriguing that they also become activated in various tumour conditions. Therefore, it is crucial to understand how similar pathways can achieve context-dependent functional outputs, likely depending on cellular states. Compromised chromatin regulation, upon removal of the Polycomb group member polyhomeotic, leads to tumour formation with ectopic activation of JNK signalling, mediated by egr/grnd, in addition to JAK/STAT and Notch. Employing quantitative analyses, we show that blocking ectopic signalling impairs ph tumour growth. Furthermore, JAK/STAT functions in parallel to JNK, while Notch relies on JNK. Here, we reveal a signalling hierarchy in ph tumours that is distinct from the regenerative processes regulated by these pathways. Absence of ph renders a permissive state for expression of target genes, but our results suggest that both loss of repression and the presence of activators may collectively regulate gene expression during tumorigenesis. Further dissecting the effect of signalling, developmental or stress-induced factors will thus elucidate the regulation of physiological responses and the contribution of context-specific cellular states.
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Affiliation(s)
- Jorge V. Beira
- ETH Zürich, Department of Biosystems Science and Engineering, MattenstrasseBasel, Switzerland
- * E-mail: (JVB); (RP)
| | - Joana Torres
- ETH Zürich, Department of Biosystems Science and Engineering, MattenstrasseBasel, Switzerland
| | - Renato Paro
- ETH Zürich, Department of Biosystems Science and Engineering, MattenstrasseBasel, Switzerland
- Faculty of Science, University of Basel, KlingelbergstrasseBasel, Switzerland
- * E-mail: (JVB); (RP)
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5
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Dutta P, Li WX. The SERTAD protein Taranis plays a role in Polycomb-mediated gene repression. PLoS One 2017; 12:e0180026. [PMID: 28665982 PMCID: PMC5493352 DOI: 10.1371/journal.pone.0180026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 06/08/2017] [Indexed: 11/19/2022] Open
Abstract
The Polycomb group (PcG) proteins have been implicated in epigenetic transcriptional repression in development, stem cell maintenance and in cancer. The chromodomain protein Polycomb (Pc) is a key member of the PcG. Pc binds to the histone mark, trimethylated histone 3 lysine 27 (H3K27me3), to initiate transcriptional repression. How PcG proteins are recruited to target loci is not fully understood. Here we show that the Drosophila SERTA domain protein Taranis (Tara) is involved in transcriptional regulation of Pc target genes. Embryos lacking Tara exhibit a partial homeotic transformation of cuticular the segments, a phenotype associated with the loss of Pc function. Moreover, Drosophila embryos homozygous for a tara hypomorphic allele also misexpress engrailed, a Pc-regulated gene, and this phenotype is associated with the loss of Pc binding to the cis response element in the engrailed enhancer. In relation to that, Pc recruitment is reduced on the salivary gland polytene chromosomes and specifically at the engrailed locus. These results suggest that Tara might be required for positioning Pc to a subset of its target genes.
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Affiliation(s)
- Pranabananda Dutta
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail:
| | - Willis X. Li
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, New York, United States of America
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Pflugfelder G, Eichinger F, Shen J. T-Box Genes in Drosophila Limb Development. Curr Top Dev Biol 2017; 122:313-354. [DOI: 10.1016/bs.ctdb.2016.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
The study of Drosophila imaginal discs has contributed to a number of discoveries in developmental and cellular biology. In addition to the elucidation of the role of tissue compartments and organ-specific master regulator genes during development, imaginal discs have also become well established as models for studying cellular interactions and complex genetic pathways. Here, we review key discoveries resulting from investigations of these epithelial precursor organs, ranging from cell fate determination and transdetermination to tissue patterning. Furthermore, the design of increasingly sophisticated genetic tools over the last decades has added value to the use of imaginal discs as model systems. As a result of tissue-specific genetic screens, several components of developmentally regulated signaling pathways were identified and epistasis revealed the levels at which they function. Discs have been widely used to assess cellular interactions in their natural tissue context, contributing to a better understanding of growth regulation, tissue regeneration, and cancer. With the continuous implementation of novel tools, imaginal discs retain significant potential as model systems to address emerging questions in biology and medicine.
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Taranis Protects Regenerating Tissue from Fate Changes Induced by the Wound Response in Drosophila. Dev Cell 2015; 34:119-28. [DOI: 10.1016/j.devcel.2015.04.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/25/2015] [Accepted: 04/23/2015] [Indexed: 12/15/2022]
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9
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O-GlcNAcylation prevents aggregation of the Polycomb group repressor polyhomeotic. Dev Cell 2014; 31:629-39. [PMID: 25468754 DOI: 10.1016/j.devcel.2014.10.020] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 09/07/2014] [Accepted: 10/27/2014] [Indexed: 12/31/2022]
Abstract
The glycosyltransferase Ogt adds O-linked N-Acetylglucosamine (O-GlcNAc) moieties to nuclear and cytosolic proteins. Drosophila embryos lacking Ogt protein arrest development with a remarkably specific Polycomb phenotype, arising from the failure to repress Polycomb target genes. The Polycomb protein Polyhomeotic (Ph), an Ogt substrate, forms large aggregates in the absence of O-GlcNAcylation both in vivo and in vitro. O-GlcNAcylation of a serine/threonine (S/T) stretch in Ph is critical to prevent nonproductive aggregation of both Drosophila and human Ph via their C-terminal sterile alpha motif (SAM) domains in vitro. Full Ph repressor activity in vivo requires both the SAM domain and O-GlcNAcylation of the S/T stretch. We demonstrate that Ph mutants lacking the S/T stretch reproduce the phenotype of ogt mutants, suggesting that the S/T stretch in Ph is the key Ogt substrate in Drosophila. We propose that O-GlcNAcylation is needed for Ph to form functional, ordered assemblies via its SAM domain.
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Schaaf CA, Misulovin Z, Gause M, Koenig A, Gohara DW, Watson A, Dorsett D. Cohesin and polycomb proteins functionally interact to control transcription at silenced and active genes. PLoS Genet 2013; 9:e1003560. [PMID: 23818863 PMCID: PMC3688520 DOI: 10.1371/journal.pgen.1003560] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 04/24/2013] [Indexed: 12/05/2022] Open
Abstract
Cohesin is crucial for proper chromosome segregation but also regulates gene transcription and organism development by poorly understood mechanisms. Using genome-wide assays in Drosophila developing wings and cultured cells, we find that cohesin functionally interacts with Polycomb group (PcG) silencing proteins at both silenced and active genes. Cohesin unexpectedly facilitates binding of Polycomb Repressive Complex 1 (PRC1) to many active genes, but their binding is mutually antagonistic at silenced genes. PRC1 depletion decreases phosphorylated RNA polymerase II and mRNA at many active genes but increases them at silenced genes. Depletion of cohesin reduces long-range interactions between Polycomb Response Elements in the invected-engrailed gene complex where it represses transcription. These studies reveal a previously unrecognized role for PRC1 in facilitating productive gene transcription and provide new insights into how cohesin and PRC1 control development.
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Affiliation(s)
- Cheri A. Schaaf
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Ziva Misulovin
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Maria Gause
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Amanda Koenig
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - David W. Gohara
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Audrey Watson
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Dale Dorsett
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
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11
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Robinson AK, Leal BZ, Chadwell LV, Wang R, Ilangovan U, Kaur Y, Junco SE, Schirf V, Osmulski PA, Gaczynska M, Hinck AP, Demeler B, McEwen DG, Kim CA. The growth-suppressive function of the polycomb group protein polyhomeotic is mediated by polymerization of its sterile alpha motif (SAM) domain. J Biol Chem 2012; 287:8702-13. [PMID: 22275371 DOI: 10.1074/jbc.m111.336115] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Polyhomeotic (Ph), a member of the Polycomb Group (PcG), is a gene silencer critical for proper development. We present a previously unrecognized way of controlling Ph function through modulation of its sterile alpha motif (SAM) polymerization leading to the identification of a novel target for tuning the activities of proteins. SAM domain containing proteins have been shown to require SAM polymerization for proper function. However, the role of the Ph SAM polymer in PcG-mediated gene silencing was uncertain. Here, we first show that Ph SAM polymerization is indeed required for its gene silencing function. Interestingly, the unstructured linker sequence N-terminal to Ph SAM can shorten the length of polymers compared with when Ph SAM is individually isolated. Substituting the native linker with a random, unstructured sequence (RLink) can still limit polymerization, but not as well as the native linker. Consequently, the increased polymeric Ph RLink exhibits better gene silencing ability. In the Drosophila wing disc, Ph RLink expression suppresses growth compared with no effect for wild-type Ph, and opposite to the overgrowth phenotype observed for polymer-deficient Ph mutants. These data provide the first demonstration that the inherent activity of a protein containing a polymeric SAM can be enhanced by increasing SAM polymerization. Because the SAM linker had not been previously considered important for the function of SAM-containing proteins, our finding opens numerous opportunities to manipulate linker sequences of hundreds of polymeric SAM proteins to regulate a diverse array of intracellular functions.
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Affiliation(s)
- Angela K Robinson
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3990, USA
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12
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Pérez L, Barrio L, Cano D, Fiuza UM, Muzzopappa M, Milán M. Enhancer-PRE communication contributes to the expansion of gene expression domains in proliferating primordia. Development 2011; 138:3125-34. [PMID: 21715425 DOI: 10.1242/dev.065599] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Trithorax-group and Polycomb-group proteins interact with chromosomal elements, termed PRE/TREs, to ensure stable heritable maintenance of the transcriptional state of nearby genes. Regulatory elements that bind both groups of proteins are termed maintenance elements (MEs). Some of these MEs maintain the initial activated transcriptional state of a nearby reporter gene through several rounds of mitosis during development. Here, we show that expression of hedgehog in the posterior compartment of the Drosophila wing results from the communication between a previously defined ME and a nearby cis-regulatory element termed the C enhancer. The C enhancer integrates the activities of the Notch and Hedgehog signalling pathways and, from the early wing primordium stage, drives expression to a thin stripe in the posterior compartment that corresponds to the dorsal-ventral compartment boundary. The ME maintains the initial activated transcriptional state conferred by the C enhancer and contributes to the expansion, by growth, of its expression domain throughout the posterior compartment. Communication between the ME and the C enhancer also contributes to repression of gene expression in anterior cells. Most interestingly, we present evidence that enhancers and MEs of different genes are interchangeable modules whose communication is involved in restricting and expanding the domains of gene expression. Our results emphasize the modular role of MEs in regulation of gene expression within growing tissues.
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Affiliation(s)
- Lidia Pérez
- Institute for Research in Biomedicine (IRB Barcelon), Baldiri Reixac, 10-12, 08028 Barcelona, Spain
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Terriente-Félix A, Molnar C, Gómez-Skarmeta JL, de Celis JF. A conserved function of the chromatin ATPase Kismet in the regulation of hedgehog expression. Dev Biol 2010; 350:382-92. [PMID: 21146514 DOI: 10.1016/j.ydbio.2010.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 11/24/2010] [Accepted: 12/01/2010] [Indexed: 12/31/2022]
Abstract
The development of the Drosophila melanogaster wing depends on its subdivision into anterior and posterior compartments, which constitute two independent cell lineages since their origin in the embryonic ectoderm. The anterior-posterior compartment boundary is the place where signaling by the Hedgehog pathway takes place, and this requires pathway activation in anterior cells by ligand expressed exclusively in posterior cells. Several mechanisms ensure the confinement of hedgehog expression to posterior cells, including repression by Cubitus interruptus, the co-repressor Groucho and Master of thick veins. In this work we identified Kismet, a chromodomain-containing protein of the SNF2-like family of ATPases, as a novel component of the hedgehog transcriptional repression mechanism in anterior compartment cells. In kismet mutants, hedgehog is ectopically expressed in a domain of anterior cells close to the anterior-posterior compartment boundary, causing inappropriate activation of the pathway and changes in the development of the central region of the wing. The contribution of Kismet to the silencing of hedgehog expression is limited to anterior cells with low levels of the repressor form of Cubitus interruptus. We also show that knockdown of CHD8, the kismet homolog in Xenopus tropicalis, is also associated with ectopic sonic hedgehog expression and up-regulation of one of its target genes in the eye, Pax2, indicating the evolutionary conservation of Kismet/CHD8 function in negatively controlling hedgehog expression.
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Affiliation(s)
- Ana Terriente-Félix
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid Cantoblanco, Madrid, Spain
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Gandille P, Narbonne-Reveau K, Boissonneau E, Randsholt N, Busson D, Pret AM. Mutations in the polycomb group gene polyhomeotic lead to epithelial instability in both the ovary and wing imaginal disc in Drosophila. PLoS One 2010; 5:e13946. [PMID: 21085656 PMCID: PMC2978711 DOI: 10.1371/journal.pone.0013946] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 10/08/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Most human cancers originate from epithelial tissues and cell polarity and adhesion defects can lead to metastasis. The Polycomb-Group of chromatin factors were first characterized in Drosophila as repressors of homeotic genes during development, while studies in mammals indicate a conserved role in body plan organization, as well as an implication in other processes such as stem cell maintenance, cell proliferation, and tumorigenesis. We have analyzed the function of the Drosophila Polycomb-Group gene polyhomeotic in epithelial cells of two different organs, the ovary and the wing imaginal disc. RESULTS Clonal analysis of loss and gain of function of polyhomeotic resulted in segregation between mutant and wild-type cells in both the follicular and wing imaginal disc epithelia, without excessive cell proliferation. Both basal and apical expulsion of mutant cells was observed, the former characterized by specific reorganization of cell adhesion and polarity proteins, the latter by complete cytoplasmic diffusion of these proteins. Among several candidate target genes tested, only the homeotic gene Abdominal-B was a target of PH in both ovarian and wing disc cells. Although overexpression of Abdominal-B was sufficient to cause cell segregation in the wing disc, epistatic analysis indicated that the presence of Abdominal-B is not necessary for expulsion of polyhomeotic mutant epithelial cells suggesting that additional polyhomeotic targets are implicated in this phenomenon. CONCLUSION Our results indicate that polyhomeotic mutations have a direct effect on epithelial integrity that can be uncoupled from overproliferation. We show that cells in an epithelium expressing different levels of polyhomeotic sort out indicating differential adhesive properties between the cell populations. Interestingly, we found distinct modalities between apical and basal expulsion of ph mutant cells and further studies of this phenomenon should allow parallels to be made with the modified adhesive and polarity properties of different types of epithelial tumors.
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Affiliation(s)
- Pierre Gandille
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Karine Narbonne-Reveau
- Institut de Biologie du Développement de Marseille-Luminy (UMR 6216), Centre National de la Recherche Scientifique/Université de la Méditérannée Aix-Marseille II, Marseille, France
- Institut Jacques Monod (UMR7592), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Université Denis Diderot-Paris VII, Paris, France
| | - Elisabeth Boissonneau
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Neel Randsholt
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
- Laboratoire de Biologie du Développement (UMR7622), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Paris, France
| | - Denise Busson
- Institut Jacques Monod (UMR7592), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Université Denis Diderot-Paris VII, Paris, France
- Systematique Adaptation Evolution (UMR7138), Université Pierre et Marie Curie Paris VI, Paris, France
| | - Anne-Marie Pret
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
- Institut Jacques Monod (UMR7592), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Université Denis Diderot-Paris VII, Paris, France
- Université de Versailles-St Quentin, Versailles, France
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Regeneration and transdetermination: the role of wingless and its regulation. Dev Biol 2010; 347:315-24. [PMID: 20816798 DOI: 10.1016/j.ydbio.2010.08.034] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 08/20/2010] [Accepted: 08/26/2010] [Indexed: 11/22/2022]
Abstract
Imaginal discs of Drosophila have the remarkable ability to regenerate. After fragmentation wound healing occurs, ectopic wg is induced and a blastema is formed. In some, but not all fragments, the blastema will replace missing structures and a few cells can become more plastic and transdetermine to structures of other discs. A series of systematic cuts through the first leg disc revealed that a cut must transect the dorsal-proximal disc area and that the fragment must also include wg-competent cells. Fragments that fail to both transdetermine and regenerate missing structures will do both when provided with exogenous Wg, demonstrating the necessity of Wg in regenerative processes. In intact leg discs ubiquitously expressed low levels of Wg also leads to blastema formation, regeneration and transdetermination. Two days after exogenous wg induction the endogenous gene is activated, leading to elevated levels of Wg in the dorsal aspect of the leg disc. We identified a wg enhancer that regulates ectopic wg expression. Deletion of this enhancer increases transdetermination, but lowers the amount of ectopic Wg. We speculate that this lessens repression of dpp dorsally, and thus creates a permissive condition under which the balance of ectopic Wg and Dpp is favorable for transdetermination.
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16
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Malik S, Bhaumik SR. Mixed lineage leukemia: histone H3 lysine 4 methyltransferases from yeast to human. FEBS J 2010; 277:1805-21. [PMID: 20236312 DOI: 10.1111/j.1742-4658.2010.07607.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fourth lysine of histone H3 is post-translationally modified by a methyl group via the action of histone methyltransferase, and such a covalent modification is associated with transcriptionally active and/or repressed chromatin states. Thus, histone H3 lysine 4 methylation has a crucial role in maintaining normal cellular functions. In fact, misregulation of this covalent modification has been implicated in various types of cancer and other diseases. Therefore, a large number of studies over recent years have been directed towards histone H3 lysine 4 methylation and the enzymes involved in this covalent modification in eukaryotes ranging from yeast to human. These studies revealed a set of histone H3 lysine 4 methyltransferases with important cellular functions in different eukaryotes, as discussed here.
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Affiliation(s)
- Shivani Malik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
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Bischoff K, Ballew AC, Simon MA, O'Reilly AM. Wing defects in Drosophila xenicid mutant clones are caused by C-terminal deletion of additional sex combs (Asx). PLoS One 2009; 4:e8106. [PMID: 19956620 PMCID: PMC2779589 DOI: 10.1371/journal.pone.0008106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 11/06/2009] [Indexed: 11/21/2022] Open
Abstract
Background The coordinated action of genes that control patterning, cell fate determination, cell size, and cell adhesion is required for proper wing formation in Drosophila. Defects in any of these basic processes can lead to wing aberrations, including blisters. The xenicid mutation was originally identified in a screen designed to uncover regulators of adhesion between wing surfaces [1]. Principal Findings Here, we demonstrate that expression of the βPS integrin or the patterning protein Engrailed are not affected in developing wing imaginal discs in xenicid mutants. Instead, expression of the homeotic protein Ultrabithorax (Ubx) is strongly increased in xenicid mutant cells. Conclusion Our results suggest that upregulation of Ubx transforms cells from a wing blade fate to a haltere fate, and that the presence of haltere cells within the wing blade is the primary defect leading to the adult wing phenotypes observed.
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Affiliation(s)
- Kara Bischoff
- Department of Biological Sciences, Stanford University, Stanford, California, United States of America
| | - Anna C. Ballew
- Department of Biological Sciences, Stanford University, Stanford, California, United States of America
| | - Michael A. Simon
- Department of Biological Sciences, Stanford University, Stanford, California, United States of America
| | - Alana M. O'Reilly
- Department of Biological Sciences, Stanford University, Stanford, California, United States of America
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Polyhomeotic has a tumor suppressor activity mediated by repression of Notch signaling. Nat Genet 2009; 41:1076-82. [DOI: 10.1038/ng.414] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 06/05/2009] [Indexed: 01/26/2023]
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Schaaf CA, Misulovin Z, Sahota G, Siddiqui AM, Schwartz YB, Kahn TG, Pirrotta V, Gause M, Dorsett D. Regulation of the Drosophila Enhancer of split and invected-engrailed gene complexes by sister chromatid cohesion proteins. PLoS One 2009; 4:e6202. [PMID: 19587787 PMCID: PMC2703808 DOI: 10.1371/journal.pone.0006202] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Accepted: 06/16/2009] [Indexed: 01/14/2023] Open
Abstract
The cohesin protein complex was first recognized for holding sister chromatids together and ensuring proper chromosome segregation. Cohesin also regulates gene expression, but the mechanisms are unknown. Cohesin associates preferentially with active genes, and is generally absent from regions in which histone H3 is methylated by the Enhancer of zeste [E(z)] Polycomb group silencing protein. Here we show that transcription is hypersensitive to cohesin levels in two exceptional cases where cohesin and the E(z)-mediated histone methylation simultaneously coat the entire Enhancer of split and invected-engrailed gene complexes in cells derived from Drosophila central nervous system. These gene complexes are modestly transcribed, and produce seven of the twelve transcripts that increase the most with cohesin knockdown genome-wide. Cohesin mutations alter eye development in the same manner as increased Enhancer of split activity, suggesting that similar regulation occurs in vivo. We propose that cohesin helps restrain transcription of these gene complexes, and that deregulation of similarly cohesin-hypersensitive genes may underlie developmental deficits in Cornelia de Lange syndrome.
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Affiliation(s)
- Cheri A. Schaaf
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Ziva Misulovin
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Gurmukh Sahota
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Akbar M. Siddiqui
- Microarray Core Facility, Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Yuri B. Schwartz
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey, United States of America
| | - Tatyana G. Kahn
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey, United States of America
| | - Vincenzo Pirrotta
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey, United States of America
| | - Maria Gause
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Dale Dorsett
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
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Chen S, Rasmuson-Lestander Å. Regulation of the Drosophila engrailed gene by Polycomb repressor complex 2. Mech Dev 2009; 126:443-8. [DOI: 10.1016/j.mod.2009.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 01/02/2009] [Accepted: 01/17/2009] [Indexed: 12/01/2022]
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22
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Genetic and epigenetic mechanisms regulating hedgehog expression in the Drosophila wing. Dev Biol 2009; 327:508-15. [PMID: 19210960 DOI: 10.1016/j.ydbio.2009.01.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 12/23/2008] [Accepted: 01/05/2009] [Indexed: 11/21/2022]
Abstract
Stable subdivision of Drosophila limbs into Anterior (A) and Posterior (P) compartments is a consequence of asymmetric signaling by Hedgehog (Hh) from P to A cells. The activity of the homeodomain protein Engrailed (En) in P cells has been reported to help to generate this asymmetry by inducing the expression of hedgehog and simultaneously repressing the expression of the essential downstream component of the Hh signaling pathway Cubitus interruptus (Ci). In A cells, Ci has a major role in the repression of hh. Here we have revised the genetic and epigenetic mechanisms involved in the regulation of hh in the P compartment. First, we present evidence that hh expression in P cells is a consequence of the repression of ci by the activity of En. Thus, in the absence of Ci and En activities, cells do express hh. We also present data supporting the maintenance of hh expression in P cells through epigenetic mechanisms, and a permissive role of Notch signaling in this process. Notch and Trithorax (TrxG) group of proteins exert their action through a previously defined hh Polycomb Responsive Element (PRE).
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Kim SN, Jung KI, Chung HM, Kim SH, Jeon SH. The pleiohomeotic gene is required for maintaining expression of genes functioning in ventral appendage formation in Drosophila melanogaster. Dev Biol 2008; 319:121-9. [PMID: 18495104 DOI: 10.1016/j.ydbio.2008.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2007] [Revised: 04/14/2008] [Accepted: 04/15/2008] [Indexed: 10/22/2022]
Abstract
Polycomb group (PcG) proteins are negative regulators that maintain the expression of homeotic genes and affect cell proliferation. Pleiohomeotic (Pho) is a unique PcG member with a DNA-binding zinc finger motif and was proposed to recruit other PcG proteins to form a complex. The pho null mutants exhibited several mutant phenotypes such as the transformation of antennae to mesothoracic legs. We examined the effects of pho on the identification of ventral appendages and proximo-distal axis formation during postembryogenesis. In the antennal disc of the pho mutant, Antennapedia (Antp), which is a selector gene in determining leg identity, was ectopically expressed. The homothorax (hth), dachshund (dac) and Distal-less (Dll) genes involved in proximo-distal axis formation were also abnormally expressed in both the antennal and leg discs of the pho mutant. The engrailed (en) gene, which affects the formation of the anterior-posterior axis, was also misexpressed in the anterior compartment of antennal and leg discs. These mutant phenotypes were enhanced in the mutant background of Posterior sex combs (Psc) and pleiohomeotic-like (phol), which are another PcG genes. These results suggest that pho functions in maintaining expression of genes involved in the formation of ventral appendages and the proximo-distal axis.
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Affiliation(s)
- Su-Na Kim
- Department of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea.
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24
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Salvaing J, Decoville M, Mouchel-Vielh E, Bussière M, Daulny A, Boldyreva L, Zhimulev I, Locker D, Peronnet F. Corto and DSP1 interact and bind to a maintenance element of the Scr Hox gene: understanding the role of Enhancers of trithorax and Polycomb. BMC Biol 2006; 4:9. [PMID: 16613610 PMCID: PMC1459216 DOI: 10.1186/1741-7007-4-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Accepted: 04/14/2006] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Polycomb-group genes (PcG) encode proteins that maintain homeotic (Hox) gene repression throughout development. Conversely, trithorax-group (trxG) genes encode positive factors required for maintenance of long term Hox gene activation. Both kinds of factors bind chromatin regions called maintenance elements (ME). Our previous work has shown that corto, which codes for a chromodomain protein, and dsp1, which codes for an HMGB protein, belong to a class of genes called the Enhancers of trithorax and Polycomb (ETP) that interact with both PcG and trxG. Moreover, dsp1 interacts with the Hox gene Scr, the DSP1 protein is present on a Scr ME in S2 cells but not in embryos. To understand better the role of ETP, we addressed genetic and molecular interactions between corto and dsp1. RESULTS We show that Corto and DSP1 proteins co-localize at 91 sites on polytene chromosomes and co-immunoprecipitate in embryos. They interact directly through the DSP1 HMG-boxes and the amino-part of Corto, which contains a chromodomain. In order to search for a common target, we performed a genetic interaction analysis. We observed that corto mutants suppressed dsp11 sex comb phenotypes and enhanced AntpScx phenotypes, suggesting that corto and dsp1 are simultaneously involved in the regulation of Scr. Using chromatin immunoprecipitation of the Scr ME, we found that Corto was present on this ME both in Drosophila S2 cells and in embryos, whereas DSP1 was present only in S2 cells. CONCLUSION Our results reveal that the proteins Corto and DSP1 are differently recruited to a Scr ME depending on whether the ME is active, as seen in S2 cells, or inactive, as in most embryonic cells. The presence of a given combination of ETPs on an ME would control the recruitment of either PcG or TrxG complexes, propagating the silenced or active state.
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Affiliation(s)
- Juliette Salvaing
- UMR 7622, CNRS, Université Pierre et Marie Curie, 9, quai Saint-Bernard, 75252 PARIS cedex 05, France
- University Maastricht, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - Martine Decoville
- UPR 4301, CNRS, Centre de Biophysique Moléculaire Rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Emmanuèle Mouchel-Vielh
- UMR 7622, CNRS, Université Pierre et Marie Curie, 9, quai Saint-Bernard, 75252 PARIS cedex 05, France
| | - Marianne Bussière
- UMR 7622, CNRS, Université Pierre et Marie Curie, 9, quai Saint-Bernard, 75252 PARIS cedex 05, France
| | - Anne Daulny
- UPR 4301, CNRS, Centre de Biophysique Moléculaire Rue Charles Sadron, 45071 Orléans cedex 2, France
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Mc Clintock Building, 11723 NY, USA
| | - Lidiya Boldyreva
- Institute of Cytology and Genetics, Siberian Division of Russian Academy of Sciences, Acad. Lavrentiev Avenue, 10, 630090 Novosibirsk, Russia
| | - Igor Zhimulev
- Institute of Cytology and Genetics, Siberian Division of Russian Academy of Sciences, Acad. Lavrentiev Avenue, 10, 630090 Novosibirsk, Russia
| | - Daniel Locker
- UPR 4301, CNRS, Centre de Biophysique Moléculaire Rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Frédérique Peronnet
- UMR 7622, CNRS, Université Pierre et Marie Curie, 9, quai Saint-Bernard, 75252 PARIS cedex 05, France
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Nybakken K, Vokes SA, Lin TY, McMahon AP, Perrimon N. A genome-wide RNA interference screen in Drosophila melanogaster cells for new components of the Hh signaling pathway. Nat Genet 2005; 37:1323-32. [PMID: 16311596 PMCID: PMC6429564 DOI: 10.1038/ng1682] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 08/06/2005] [Indexed: 01/03/2023]
Abstract
Members of the Hedgehog (Hh) family of signaling proteins are powerful regulators of developmental processes in many organisms and have been implicated in many human disease states. Here we report the results of a genome-wide RNA interference screen in Drosophila melanogaster cells for new components of the Hh signaling pathway. The screen identified hundreds of potential new regulators of Hh signaling, including many large protein complexes with pleiotropic effects, such as the coat protein complex I (COPI) complex, the ribosome and the proteasome. We identified the multimeric protein phosphatase 2A (PP2A) and two new kinases, the D. melanogaster orthologs of the vertebrate PITSLRE and cyclin-dependent kinase-9 (CDK9) kinases, as Hh regulators. We also identified a large group of constitutive and alternative splicing factors, two nucleoporins involved in mRNA export and several RNA-regulatory proteins as potent regulators of Hh signal transduction, indicating that splicing regulation and mRNA transport have a previously unrecognized role in Hh signaling. Finally, we showed that several of these genes have conserved roles in mammalian Hh signaling.
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Affiliation(s)
- Kent Nybakken
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA.
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26
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Chanas G, Maschat F. Tissue specificity of hedgehog repression by the Polycomb group during Drosophila melanogaster development. Mech Dev 2005; 122:975-87. [PMID: 16024236 DOI: 10.1016/j.mod.2005.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 04/25/2005] [Accepted: 05/02/2005] [Indexed: 10/25/2022]
Abstract
During embryogenesis and wing disc morphogenesis in Drosophila, different developmental mechanisms are used along the antero-posterior (A-P) axis. The establishment of antero-posterior polarity requires the secreted protein Hedgehog, which is only expressed in P compartments and which is a key effector of the Engrailed transcription factor. At the same time, it is essential that both engrailed and hedgehog (hh) remain in a repressed state in A compartments. In this article, we show that hh is maintained in a repressed state by the Polycomb group (PcG) chromatin proteins. We show that this process takes place during embryogenesis through two genomic elements that display genetic properties of a PRE. Interestingly, hh expression is not regulated by PcG genes in salivary glands, although at the same developmental stage PcG proteins repress hh in the A compartment of the wing disc. In addition, no PcG binding sites were found on polytene chromosomes, neither within hh transgenic constructs nor at the hh endogenous locus. Together, these results suggest that hh repression by the PcG acts in a tissue-specific manner.
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Affiliation(s)
- Grégory Chanas
- Institut de Génétique Humaine (IGH-CNRS UPR 1142) 141 rue de la Cardonille 34396 Montpellier France
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Chanas G, Lavrov S, Iral F, Cavalli G, Maschat F. Engrailed and polyhomeotic maintain posterior cell identity through cubitus-interruptus regulation. Dev Biol 2004; 272:522-35. [PMID: 15282166 DOI: 10.1016/j.ydbio.2004.05.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 05/05/2004] [Accepted: 05/17/2004] [Indexed: 11/13/2022]
Abstract
In Drosophila, the subdivision into compartments requires the expression of engrailed (en) and hedgehog (hh) in the posterior cells and of cubitus-interruptus (ci) in the anterior cells. Whereas posterior cells express hh, only anterior cells are competent to respond to the hh signal, because of the presence of ci expression in these cells. We show here that engrailed and polyhomeotic (ph), a member of the Polycomb Group (PcG) genes, act concomitantly to maintain the repression of ci in posterior compartments during development. Using chromatin immunoprecipitation (ChIP), we identified a 1 kb genomic fragment located 4 kb upstream of the ci coding region that is responsible for the regulation of ci. This genomic fragment is bound in vivo by both Polyhomeotic and Engrailed. In particular, we show that Engrailed is responsible for the establishment of ci repression early during embryonic development and is also required, along with Polyhomeotic, to maintain the repression of ci throughout development.
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Affiliation(s)
- Grégory Chanas
- Institut de Génétique Humaine, UPR1142, Montpellier, Herault, France
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Wang S, Yu X, Zhang T, Zhang X, Zhang Z, Chen Y. Chick Pcl2 regulates the left-right asymmetry by repressing Shh expression in Hensen's node. Development 2004; 131:4381-91. [PMID: 15294861 DOI: 10.1242/dev.01269] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Asymmetric expression of sonic hedgehog (Shh) in the left side of Hensen's node, a crucial step for specifying the left-right (LR) axis in the chick embryo, is established by the repression of Shhexpression in the right side of the node. The transcriptional regulator that mediates this repression has not been identified. We report the isolation and characterization of a novel chick Polycomblike 2 gene, chick Pcl2, which encodes a transcription repressor and displays an asymmetric expression, downstream from Activin-βB and Bmp4, in the right side of Hensen's node in the developing embryo. In vitro mapping studies define the transcription repression activity to the PHD finger domain of the chick Pcl2 protein. Repression of chick Pcl2expression in the early embryo results in randomized heart looping direction,which is accompanied by the ectopic expression of Shh in the right side of the node and Shh downstream genes in the right lateral plate mesoderm (LPM), while overexpression of chick Pcl2 represses Shh expression in the node. The repression of Shh by chick Pcl2 was also supported by studies in which chick Pcl2 was overexpressed in the developing chick limb bud and feather bud. Similarly,transgenic overexpression of chick Pcl2 in the developing mouse limb inhibits Shh expression in the ZPA. In vitro pull-down assays demonstrated a direct interaction of the chick Pcl2 PHD finger with EZH2, a component of the ESC/E(Z) repressive complex. Taken together with the fact that chick Pcl2 was found to directly repress Shh promoter activity in vitro, our results demonstrate a crucial role for chick Pcl2 in regulating LR axis patterning in the chick by silencing Shh in the right side of the node.
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Affiliation(s)
- Shusheng Wang
- Division of Developmental Biology, Department of Cell and Molecular Biology and Center for Bioenvironmental Research, Tulane University, New Orleans, LA 70118, USA
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Resino J, García-Bellido A. Drosophila genetic variants that change cell size and rate of proliferation affect cell communication and hence patterning. Mech Dev 2004; 121:351-64. [PMID: 15110045 DOI: 10.1016/j.mod.2004.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2003] [Revised: 02/02/2004] [Accepted: 02/25/2004] [Indexed: 12/26/2022]
Abstract
We explore in this paper the role of genetic variants that affect cell size and proliferation in the determination of organ size. We use genetic mosaics of loss or gain of function in six different loci, which promotes smaller or larger than normal cells, associated to either smaller or larger than normal territories. These variants have autonomous effects on patterning and growth in mutant territories. However, there is no correlation between cell size or rate of proliferation on the size of the mutant territory. In addition, these mosaics show non-autonomous effects on surrounding wildtype cells, consisting always in a reduction in number of non-mutant cells. In all mutant conditions the final size (and shape) of the wing is different than normal. The phenotypes of the same variants include higher density of chaetae in the notum. These autonomous and non-autonomous effects suggest that the control of size in the wing is the result of local cell communication defining canonic distances between cells in a positional-values landscape.
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Affiliation(s)
- Jaime Resino
- Centro de Biología Molecular Severo Ochoa, Bioquimica y Bioligia Molecular, Universidad Autónoma de Madrid, Cantoblanco, CX504 Fac. Ciencias, Madrid 28049, Spain
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Narbonne K, Besse F, Brissard-Zahraoui J, Pret AM, Busson D. polyhomeoticis required for somatic cell proliferation and differentiation during ovarian follicle formation inDrosophila. Development 2004; 131:1389-400. [PMID: 14993188 DOI: 10.1242/dev.01003] [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] [Indexed: 11/20/2022]
Abstract
The polyhomeotic (ph) gene of Drosophila is a member of the Polycomb group (Pc-G) genes, which are required for maintenance of a repressed state of homeotic gene transcription, which stabilizes cell identity throughout development. The ph gene was recovered in the course of a gain-of-function screen aimed at identifying genes with a role during ovarian follicle formation in Drosophila, a process that involves coordinated proliferation and differentiation of two cell lineages, somatic and germline. Subsequent analysis revealed that ph loss-of-function mutations lead to production of follicles with greater or fewer than the normal number of germ cells associated with reduced proliferation of somatic prefollicular cells, abnormal prefollicular cell encapsulation of germline cysts and an excess of both interfollicular stalk cells and polar cells. Clonal analysis showed that ph function for follicle formation resides specifically in somatic cells and not in the germline. This is thus the first time that a role has been shown for a Pc-G gene during Drosophila folliculogenesis. In addition,we tested mutations in a number of other Pc-G genes, and two of them, Sex combs extra (Sce) and Sex comb on midleg(Scm), also displayed ovarian defects similar to those observed for ph. Our results provide a new model system, the Drosophilaovary, in which the function of Pc-G genes, distinct from that of control of homeotic gene expression, can be explored.
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Affiliation(s)
- Karine Narbonne
- Institut Jacques Monod, (UMR 7592 - CNRS/Université Pierre et Marie Curie/Université Denis Diderot Génétique du Développement et Evolution, 2 place Jussieu, 75251 Paris Cedex 05, France
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31
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Maurange C, Paro R. A cellular memory module conveys epigenetic inheritance of hedgehog expression during Drosophila wing imaginal disc development. Genes Dev 2002; 16:2672-83. [PMID: 12381666 PMCID: PMC187463 DOI: 10.1101/gad.242702] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In Drosophila, the Trithorax-group (trxG) and Polycomb-group (PcG) proteins interact with chromosomal elements, termed Cellular Memory Modules (CMMs). By modifying chromatin, this ensures a stable heritable maintenance of the transcriptional state of developmental regulators, like the homeotic genes, that is defined embryonically. We asked whether such CMMs could also control expression of genes involved in patterning imaginal discs during larval development. Our results demonstrate that expression of the hedgehog gene, once activated, is maintained by a CMM. In addition, our experiments indicate that the switching of such CMMs to an active state during larval stages, in contrast to embryonic stages, may require specific trans-activators. Our results suggest that the patterning of cells in particular developmental fields in the imaginal discs does not only rely on external cues from morphogens, but also depends on the previous history of the cells, as the control by CMMs ensures a preformatted gene expression pattern.
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Affiliation(s)
- Cédric Maurange
- Zentrum für Molekulare Biologie Heidelberg (ZMBH), University of Heidelberg, D-69120 Heidelberg, Germany
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