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Giraud G, Paul R, Duffraisse M, Khan S, Shashidhara LS, Merabet S. Developmental Robustness: The Haltere Case in Drosophila. Front Cell Dev Biol 2021; 9:713282. [PMID: 34368162 PMCID: PMC8343187 DOI: 10.3389/fcell.2021.713282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 06/30/2021] [Indexed: 11/24/2022] Open
Abstract
Developmental processes have to be robust but also flexible enough to respond to genetic and environmental variations. Different mechanisms have been described to explain the apparent antagonistic nature of developmental robustness and plasticity. Here, we present a “self-sufficient” molecular model to explain the development of a particular flight organ that is under the control of the Hox gene Ultrabithorax (Ubx) in the fruit fly Drosophila melanogaster. Our model is based on a candidate RNAi screen and additional genetic analyses that all converge to an autonomous and cofactor-independent mode of action for Ubx. We postulate that this self-sufficient molecular mechanism is possible due to an unusually high expression level of the Hox protein. We propose that high dosage could constitute a so far poorly investigated molecular strategy for allowing Hox proteins to both innovate and stabilize new forms during evolution.
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Affiliation(s)
| | | | | | - Soumen Khan
- Indian Institute of Science Education and Research (IISER), Pune, India
| | - L S Shashidhara
- Indian Institute of Science Education and Research (IISER), Pune, India.,Ashoka University, Sonipat, India
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2
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Tendolkar A, Pomerantz AF, Heryanto C, Shirk PD, Patel NH, Martin A. Ultrabithorax Is a Micromanager of Hindwing Identity in Butterflies and Moths. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.643661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The forewings and hindwings of butterflies and moths (Lepidoptera) are differentiated from each other, with segment-specific morphologies and color patterns that mediate a wide range of functions in flight, signaling, and protection. The Hox geneUltrabithorax(Ubx) is a master selector gene that differentiates metathoracic from mesothoracic identities across winged insects, and previous work has shown this role extends to at least some of the color patterns from the butterfly hindwing. Here we used CRISPR targeted mutagenesis to generateUbxloss-of-function somatic mutations in two nymphalid butterflies (Junonia coenia,Vanessa cardui) and a pyralid moth (Plodia interpunctella). The resulting mosaic clones yielded hindwing-to-forewing transformations, showingUbxis necessary for specifying many aspects of hindwing-specific identities, including scale morphologies, color patterns, and wing venation and structure. These homeotic phenotypes showed cell-autonomous, sharp transitions between mutant and non-mutant scales, except for clones that encroached into the border ocelli (eyespots) and resulted in composite and non-autonomous effects on eyespot ring determination. In the pyralid moth, homeotic clones converted the folding and depigmented hindwing into rigid and pigmented composites, affected the wing-coupling frenulum, and induced ectopic scent-scales in male androconia. These data confirmUbxis a master selector of lepidopteran hindwing identity and suggest it acts on many gene regulatory networks involved in wing development and patterning.
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Abstract
Abstract
Background
Organisms show an incredibly diverse array of body and organ shapes that are both unique to their taxon and important for adapting to their environment. Achieving these specific shapes involves coordinating the many processes that transform single cells into complex organs, and regulating their growth so that they can function within a fully-formed body.
Main text
Conceptually, body and organ shape can be separated in two categories, although in practice these categories need not be mutually exclusive. Body shape results from the extent to which organs, or parts of organs, grow relative to each other. The patterns of relative organ size are characterized using allometry. Organ shape, on the other hand, is defined as the geometric features of an organ’s component parts excluding its size. Characterization of organ shape is frequently described by the relative position of homologous features, known as landmarks, distributed throughout the organ. These descriptions fall into the domain of geometric morphometrics.
Conclusion
In this review, we discuss the methods of characterizing body and organ shape, the developmental programs thought to underlie each, highlight when and how the mechanisms regulating body and organ shape might overlap, and provide our perspective on future avenues of research.
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Diaz-de-la-Loza MDC, Loker R, Mann RS, Thompson BJ. Control of tissue morphogenesis by the HOX gene Ultrabithorax. Development 2020; 147:dev184564. [PMID: 32122911 PMCID: PMC7063672 DOI: 10.1242/dev.184564] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/28/2020] [Indexed: 01/02/2023]
Abstract
Mutations in the Ultrabithorax (Ubx) gene cause homeotic transformation of the normally two-winged Drosophila into a four-winged mutant fly. Ubx encodes a HOX family transcription factor that specifies segment identity, including transformation of the second set of wings into rudimentary halteres. Ubx is known to control the expression of many genes that regulate tissue growth and patterning, but how it regulates tissue morphogenesis to reshape the wing into a haltere is still unclear. Here, we show that Ubx acts by repressing the expression of two genes in the haltere, Stubble and Notopleural, both of which encode transmembrane proteases that remodel the apical extracellular matrix to promote wing morphogenesis. In addition, Ubx induces expression of the Tissue inhibitor of metalloproteases in the haltere, which prevents the basal extracellular matrix remodelling necessary for wing morphogenesis. Our results provide a long-awaited explanation for how Ubx controls morphogenetic transformation.
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Affiliation(s)
| | - Ryan Loker
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA
| | - Richard S Mann
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA
| | - Barry J Thompson
- Epithelial Biology Laboratory, The Francis Crick Institute, 1 Midland Rd, St Pancras, London NW1 1AT, United Kingdom
- EMBL Australia, The John Curtin School of Medical Research, The Australian National University, Acton, Canberra, ACT 2601, Australia
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5
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Romero-pozuelo J, Foronda D, Martín P, Hudry B, Merabet S, Graba Y, Sánchez-herrero E. Cooperation of axial and sex specific information controls Drosophila female genitalia growth by regulating the Decapentaplegic pathway. Dev Biol 2019; 454:145-55. [DOI: 10.1016/j.ydbio.2019.06.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/18/2019] [Accepted: 06/20/2019] [Indexed: 01/18/2023]
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De Las Heras JM, García-Cortés C, Foronda D, Pastor-Pareja JC, Shashidhara LS, Sánchez-Herrero E. The Drosophila Hox gene Ultrabithorax controls appendage shape by regulating extracellular matrix dynamics. Development 2018; 145:dev.161844. [PMID: 29853618 DOI: 10.1242/dev.161844] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 05/17/2018] [Indexed: 12/19/2022]
Abstract
Although the specific form of an organ is frequently important for its function, the mechanisms underlying organ shape are largely unknown. In Drosophila, the wings and halteres, homologous appendages of the second and third thoracic segments, respectively, bear different forms: wings are flat, whereas halteres are globular, and yet both characteristic shapes are essential for a normal flight. The Hox gene Ultrabithorax (Ubx) governs the difference between wing and haltere development, but how Ubx function in the appendages prevents or allows flat or globular shapes is unknown. Here, we show that Ubx downregulates Matrix metalloproteinase 1 (Mmp1) expression in the haltere pouch at early pupal stage, which in turn prevents the rapid clearance of Collagen IV compared with the wing disc. This difference is instrumental in determining cell shape changes, expansion of the disc and apposition of dorsal and ventral layers, all of these phenotypic traits being characteristic of wing pouch development. Our results suggest that Ubx regulates organ shape by controlling Mmp1 expression, and the extent and timing of extracellular matrix degradation.
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Affiliation(s)
- José M De Las Heras
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | - Celia García-Cortés
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | - David Foronda
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | | | - L S Shashidhara
- Indian Institute of Science Education and Research Pune, Dr Homi Bhabha Road, Pune, Maharashtra 411008, India
| | - Ernesto Sánchez-Herrero
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
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7
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Tomoyasu Y. Ultrabithorax and the evolution of insect forewing/hindwing differentiation. Curr Opin Insect Sci 2017; 19:8-15. [PMID: 28521947 DOI: 10.1016/j.cois.2016.10.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 10/24/2016] [Indexed: 06/07/2023]
Abstract
Decades have passed since the stunning four-winged phenotype of the Drosophila Ultrabithorax (Ubx) mutant was reported, and accumulating knowledge obtained from studies on Ubx in Drosophila has provided a framework to investigate the role of Ubx during insect wing evolution. With several new insights emerging from recent studies in non-Drosophila insects, along with the outcomes of genomic studies focused on identifying Ubx targets, it appears to be an appropriate time to revisit the Drosophila paradigm regarding insect wing development and evolution. Here, I review the recent findings related to Ubx during wing development, and discuss the impact of these findings on the current view of how Ubx came to regulate wing differentiation in the evolution of insect flight structures.
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9
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Tsubota T, Tomita S, Uchino K, Kimoto M, Takiya S, Kajiwara H, Yamazaki T, Sezutsu H. A Hox Gene, Antennapedia, Regulates Expression of Multiple Major Silk Protein Genes in the Silkworm Bombyx mori. J Biol Chem 2016; 291:7087-96. [PMID: 26814126 DOI: 10.1074/jbc.m115.699819] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Indexed: 01/31/2023] Open
Abstract
Hoxgenes play a pivotal role in the determination of anteroposterior axis specificity during bilaterian animal development. They do so by acting as a master control and regulating the expression of genes important for development. Recently, however, we showed that Hoxgenes can also function in terminally differentiated tissue of the lepidopteranBombyx mori In this species,Antennapedia(Antp) regulates expression of sericin-1, a major silk protein gene, in the silk gland. Here, we investigated whether Antpcan regulate expression of multiple genes in this tissue. By means of proteomic, RT-PCR, and in situ hybridization analyses, we demonstrate that misexpression of Antpin the posterior silk gland induced ectopic expression of major silk protein genes such assericin-3,fhxh4, and fhxh5 These genes are normally expressed specifically in the middle silk gland as is Antp Therefore, the evidence strongly suggests that Antpactivates these silk protein genes in the middle silk gland. The putativesericin-1 activator complex (middle silk gland-intermolt-specific complex) can bind to the upstream regions of these genes, suggesting that Antpdirectly activates their expression. We also found that the pattern of gene expression was well conserved between B. moriand the wild species Bombyx mandarina, indicating that the gene regulation mechanism identified here is an evolutionarily conserved mechanism and not an artifact of the domestication of B. mori We suggest that Hoxgenes have a role as a master control in terminally differentiated tissues, possibly acting as a primary regulator for a range of physiological processes.
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Affiliation(s)
- Takuya Tsubota
- From the Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan,
| | - Shuichiro Tomita
- From the Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan
| | - Keiro Uchino
- From the Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan
| | | | - Shigeharu Takiya
- Graduate School of Life Science and Division of Biological Science and Center for Genome Dynamics, Faculty of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan, and
| | - Hideyuki Kajiwara
- Biomolecular Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Toshimasa Yamazaki
- Biomolecular Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Hideki Sezutsu
- From the Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan,
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Singh S, Sánchez-herrero E, Shashidhara L. Critical role for Fat/Hippo and IIS/Akt pathways downstream of Ultrabithorax during haltere specification in Drosophila. Mech Dev 2015; 138:198-209. [DOI: 10.1016/j.mod.2015.07.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/18/2015] [Accepted: 07/20/2015] [Indexed: 11/18/2022]
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Ferreira A, Milán M. Dally Proteoglycan Mediates the Autonomous and Nonautonomous Effects on Tissue Growth Caused by Activation of the PI3K and TOR Pathways. PLoS Biol 2015; 13:e1002239. [PMID: 26313758 DOI: 10.1371/journal.pbio.1002239] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 07/31/2015] [Indexed: 11/19/2022] Open
Abstract
How cells acquiring mutations in tumor suppressor genes outcompete neighboring wild-type cells is poorly understood. The phosphatidylinositol 3-kinase (PI3K)–phosphatase with tensin homology (PTEN) and tuberous sclerosis complex (TSC)-target of rapamycin (TOR) pathways are frequently activated in human cancer, and this activation is often causative of tumorigenesis. We utilized the Gal4-UAS system in Drosophila imaginal primordia, highly proliferative and growing tissues, to analyze the impact of restricted activation of these pathways on neighboring wild-type cell populations. Activation of these pathways leads to an autonomous induction of tissue overgrowth and to a remarkable nonautonomous reduction in growth and proliferation rates of adjacent cell populations. This nonautonomous response occurs independently of where these pathways are activated, is functional all throughout development, takes place across compartments, and is distinct from cell competition. The observed autonomous and nonautonomous effects on tissue growth rely on the up-regulation of the proteoglycan Dally, a major element involved in modulating the spreading, stability, and activity of the growth promoting Decapentaplegic (Dpp)/transforming growth factor β(TGF-β) signaling molecule. Our findings indicate that a reduction in the amount of available growth factors contributes to the outcompetition of wild-type cells by overgrowing cell populations. During normal development, the PI3K/PTEN and TSC/TOR pathways play a major role in sensing nutrient availability and modulating the final size of any developing organ. We present evidence that Dally also contributes to integrating nutrient sensing and organ scaling, the fitting of pattern to size. The loss of tumor suppressor genes induces a nonautonomous reduction of growth and proliferation rates in adjacent cell populations by competing for available growth factors; the proteoglycan Dally helps to mediate this effect. The final size of a developing organ is finely modulated by nutrient conditions through the activity of nutrient sensing pathways, and deregulation of these pathways is often causative of tumorigenesis. Besides the well-known roles of these pathways in inducing tissue and cell growth, here we identify a nonautonomous effect of activation of these pathways on growth and proliferation rates and on the final size of neighboring cell populations. We reveal that the observed autonomous and nonautonomous effects on tissue growth and proliferation rates rely on the up-regulation of the proteoglycan Dally, a major factor involved in modulating the spreading, stability, and activity of the growth promoting Decapentaplegic (Dpp)/transforming growth factor β(TGF-β) signaling molecule. Our data indicate that a reduction in the amount of available growth factors contributes to the outcompetition of wild-type cells by overgrowing cell populations. Whereas nutrient-sensing pathways modulate the final size of the adult structure according to nutrient availability to the feeding animal, Dpp plays an organ-intrinsic role in the coordination of growth and patterning. We identify the proteoglycan Dally as the rate-limiting factor that contributes to the tissue-autonomous and nonautonomous effects on growth caused by targeted activation of the nutrient-sensing pathways. Thus, our results unravel a role of Dally as a molecular bridge between the organ-intrinsic and organ-extrinsic mechanisms that regulate organ size.
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12
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Simon E, Guerrero I. The transcription factor optomotor-blind antagonizes Drosophila haltere growth by repressing decapentaplegic and hedgehog targets. PLoS One 2015; 10:e0121239. [PMID: 25793870 DOI: 10.1371/journal.pone.0121239] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 01/29/2015] [Indexed: 12/23/2022] Open
Abstract
In Drosophila, decapentaplegic, which codes for a secreted signaling molecule, is activated by the Hedgehog signaling pathway at the anteroposterior compartment border of the two dorsal primordia; the wing and the haltere imaginal discs. In the wing disc, Decapentaplegic and Hedgehog signaling targets are implicated in cell proliferation and cell survival. However, most of their known targets in the wing disc are not expressed in the haltere disc due to their repression by the Hox gene Ultrabithorax. The T-box gene optomotor-blind escapes this repression in the haltere disc, and therefore is expressed in both the haltere and wing discs. Optomotor-blind is a major player during wing development and its function has been intensely investigated in this tissue, however, its role in haltere development has not been reported so far. Here we show that Optomotor-blind function in the haltere disc differs from that in the wing disc. Unlike its role in the wing, Optomotor-blind does not prevent apoptosis in the haltere but rather limits growth by repressing several Decapentaplegic and Hedgehog targets involved both in wing proliferation and in modulating the spread of morphogens similar to Ultrabithorax function but without disturbing Ultrabithorax expression.
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Hamaratoglu F, Affolter M, Pyrowolakis G. Dpp/BMP signaling in flies: from molecules to biology. Semin Cell Dev Biol 2014; 32:128-36. [PMID: 24813173 DOI: 10.1016/j.semcdb.2014.04.036] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/30/2014] [Indexed: 01/08/2023]
Abstract
Decapentaplegic (Dpp), the fly homolog of the secreted mammalian BMP2/4 signaling molecules, is involved in almost all aspects of fly development. Dpp has critical functions at all developmental stages, from patterning of the eggshell to the determination of adult intestinal stem cell identity. Here, we focus on recent findings regarding the transcriptional regulatory logic of the pathway, on a new feedback regulator, Pentagone, and on Dpp's roles in scaling and growth of the Drosophila wing.
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Affiliation(s)
- Fisun Hamaratoglu
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.
| | - Markus Affolter
- Growth & Development, Biozentrum, University of Basel, Basel, Switzerland
| | - George Pyrowolakis
- Institute for Biology I, Albert-Ludwigs-University of Freiburg, Freiburg, Germany; Centre for Biological Signaling Studies (BIOSS), Albert-Ludwigs-University of Freiburg, Freiburg, Germany
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Papagiannouli F, Schardt L, Grajcarek J, Ha N, Lohmann I. The Hox gene Abd-B controls stem cell niche function in the Drosophila testis. Dev Cell 2014; 28:189-202. [PMID: 24480643 DOI: 10.1016/j.devcel.2013.12.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 09/06/2013] [Accepted: 12/23/2013] [Indexed: 01/20/2023]
Abstract
Proper niche architecture is critical for stem cell function, yet only few upstream regulators are known. Here, we report that the Hox transcription factor Abdominal-B (Abd-B), active in premeiotic spermatocytes of Drosophila testes, is essential for positioning the niche to the testis anterior by regulating integrin in neighboring somatic cyst cells. Abd-B also non-cell-autonomously controls critical features within the niche, including centrosome orientation and division rates of germline stem cells. By using genome-wide binding studies, we find that Abd-B mediates its effects on integrin localization by directly controlling at multiple levels the signaling activity of the Sev ligand Boss via its direct targets src42A and sec63, two genes involved in protein trafficking and recycling. Our data show that Abd-B, through local signaling between adjucent cell types, provides positional cues for integrin localization, which is critical for placement of the distant stem cell niche and stem cell activity.
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Affiliation(s)
- Fani Papagiannouli
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany.
| | - Lisa Schardt
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany; Deutsches Krebsforschungszentrum (DKFZ), D-69120 Heidelberg, Germany
| | - Janin Grajcarek
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany
| | - Nati Ha
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany
| | - Ingrid Lohmann
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany.
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Abstract
Chromatin immunoprecipitation (ChIP) is a technique that reveals in vivo location of a protein bound to DNA. ChIP coupled with DNA microarrays (ChIP-chip) or next-generation sequencing (ChIP-seq) allows for identification of binding sites of transcription factors on a global scale. Here we describe a protocol for ChIP to identify binding of the Ultrabithorax (Ubx) Hox transcription factors from imaginal discs of Drosophila larvae. The protocol can be extended to other model organisms and transcription factors.
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Affiliation(s)
- Pavan Agrawal
- Janelia Farm Research Campus, HHMI, Ashburn, VA, 20147, USA,
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16
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Abstract
Hox genes are a group of genes that specify structures along the anteroposterior axis in bilaterians. Although in many cases they do so by modifying a homologous structure with a different (or no) Hox input, there are also examples of Hox genes constructing new organs with no homology in other regions of the body. Hox genes determine structures though the regulation of targets implementing cellular functions and by coordinating cell behavior. The genetic organization to construct or modify a certain organ involves both a genetic cascade through intermediate transcription factors and a direct regulation of targets carrying out cellular functions. In this review I discuss new data from genome-wide techniques, as well as previous genetic and developmental information, to describe some examples of Hox regulation of different cell functions. I also discuss the organization of genetic cascades leading to the development of new organs, mainly using Drosophila melanogaster as the model to analyze Hox function.
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Affiliation(s)
- Ernesto Sánchez-Herrero
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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17
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Abstract
The graded distribution of morphogens underlies many of the tissue patterns that form during development. How morphogens disperse from a localized source and how gradients in the target tissue form has been under debate for decades. Recent imaging studies and biophysical measurements have provided evidence for various morphogen transport models ranging from passive mechanisms, such as free or hindered extracellular diffusion, to cell-based dispersal by transcytosis or cytonemes. Here, we analyze these transport models using the morphogens Nodal, fibroblast growth factor and Decapentaplegic as case studies. We propose that most of the available data support the idea that morphogen gradients form by diffusion that is hindered by tortuosity and binding to extracellular molecules.
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Affiliation(s)
- Patrick Müller
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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Araujo H, Fontenele MR, da Fonseca RN. Position matters: variability in the spatial pattern of BMP modulators generates functional diversity. Genesis 2012; 49:698-718. [PMID: 21671348 DOI: 10.1002/dvg.20778] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bone morphogenetic proteins (BMPs) perform a variety of functions during development. Considering a single BMP, what enables its multiple roles in tissues of varied sizes and shapes? What regulates the spatial distribution and activity patterns of the BMP in these different developmental contexts? Some BMP functions require controlling spread of the BMP morphogen, while others require formation of localized, high concentration peaks of BMP activity. Here we review work in Drosophila that describes spatial regulation of the BMP encoded by decapentaplegic (dpp) in different developmental contexts. We concentrate on extracellular modulation of BMP function and discuss the mechanisms that generate concentrated peaks of Dpp activity, subdivide territories of different activity levels or regulate spread of the Dpp morphogen from a point source. We compare these findings with data from vertebrates and non-model organisms to discuss how changes in the regulation of Dpp distribution by extracellular modulators may lead to variability in dpp function in different species.
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Affiliation(s)
- Helena Araujo
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, RJ, Brazil.
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Stultz BG, Park SY, Mortin MA, Kennison JA, Hursh DA. Hox proteins coordinate peripodial decapentaplegic expression to direct adult head morphogenesis in Drosophila. Dev Biol 2012; 369:362-76. [PMID: 22824425 DOI: 10.1016/j.ydbio.2012.07.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 06/29/2012] [Accepted: 07/12/2012] [Indexed: 02/04/2023]
Abstract
The Drosophila BMP, decapentaplegic (dpp), controls morphogenesis of the ventral adult head through expression limited to the lateral peripodial epithelium of the eye-antennal disc by a 3.5 kb enhancer in the 5' end of the gene. We recovered a 15 bp deletion mutation within this enhancer that identified a homeotic (Hox) response element that is a direct target of labial and the homeotic cofactors homothorax and extradenticle. Expression of labial and homothorax are required for dpp expression in the peripodial epithelium, while the Hox gene Deformed represses labial in this location, thus limiting its expression and indirectly that of dpp to the lateral side of the disc. The expression of these homeodomain genes is in turn regulated by the dpp pathway, as dpp signalling is required for labial expression but represses homothorax. This Hox-BMP regulatory network is limited to the peripodial epithelium of the eye-antennal disc, yet is crucial to the morphogenesis of the head, which fate maps suggest arises primarily from the disc proper, not the peripodial epithelium. Thus Hox/BMP interactions in the peripodial epithelium of the eye-antennal disc contribute inductively to the shape of the external form of the adult Drosophila head.
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Affiliation(s)
- Brian G Stultz
- Division of Cell and Gene Therapy, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA
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Agrawal P, Habib F, Yelagandula R, Shashidhara LS. Genome-level identification of targets of Hox protein Ultrabithorax in Drosophila: novel mechanisms for target selection. Sci Rep 2011; 1:205. [PMID: 22355720 DOI: 10.1038/srep00205] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 12/05/2011] [Indexed: 12/25/2022] Open
Abstract
Hox proteins are transcription factors and key regulators of segmental identity along the anterior posterior axis across all bilaterian animals. Despite decades of research, the mechanisms by which Hox proteins select and regulate their targets remain elusive. We have carried out whole-genome ChIP-chip experiments to identify direct targets of Hox protein Ultrabithorax (Ubx) during haltere development in Drosophila. Direct targets identified include upstream regulators or cofactors of Ubx. Homothorax, a cofactor of Ubx during embryonic development, is one such target and is required for normal specification of haltere. Although Ubx bound sequences are conserved amongst various insect genomes, no consensus Ubx-specific motif was detected. Surprisingly, binding motifs for certain transcription factors that function either upstream or downstream to Ubx are enriched in these sequences suggesting complex regulatory loops governing Ubx function. Our data supports the hypothesis that specificity during Hox target selection is achieved by associating with other transcription factors.
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Abstract
Extracellular signaling molecules have crucial roles in development and homeostasis, and their incorrect deployment can lead to developmental defects and disease states. Signaling molecules are released from sending cells, travel to target cells, and act over length scales of several orders of magnitude, from morphogen-mediated patterning of small developmental fields to hormonal signaling throughout the organism. We discuss how signals are modified and assembled for transport, which routes they take to reach their targets, and how their range is affected by mobility and stability.
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Affiliation(s)
- Patrick Müller
- Department of Molecular and Cellular Biology, Harvard Stem Cell Institute, Broad Institute, Center for Brain Science, FAS Center for Systems Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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Choo SW, White R, Russell S. Genome-wide analysis of the binding of the Hox protein Ultrabithorax and the Hox cofactor Homothorax in Drosophila. PLoS One 2011; 6:e14778. [PMID: 21483667 PMCID: PMC3071696 DOI: 10.1371/journal.pone.0014778] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 02/15/2011] [Indexed: 12/15/2022] Open
Abstract
Hox genes encode a family of transcription factors that are key developmental regulators with a highly conserved role in specifying segmental diversity along the metazoan body axis. Although they have been shown to regulate a wide variety of downstream processes, direct transcriptional targets have been difficult to identify and this has been a major obstacle to our understanding of Hox gene function. We report the identification of genome-wide binding sites for the Hox protein Ultrabithorax (Ubx) using a YFP-tagged Drosophila protein-trap line together with chromatin immunoprecipitation and microarray analysis. We identify 1,147 genes bound by Ubx at high confidence in chromatin from the haltere imaginal disc, a prominent site of Ubx function where it specifies haltere versus wing development. The functional relevance of these genes is supported by their overlap with genes differentially expressed between wing and haltere imaginal discs. The Ubx-bound gene set is highly enriched in genes involved in developmental processes and contains both high-level regulators as well as genes involved in more basic cellular functions. Several signalling pathways are highly enriched in the Ubx target gene set and our analysis supports the view that Hox genes regulate many levels of developmental pathways and have targets distributed throughout the gene network. We also performed genome-wide analysis of the binding sites for the Hox cofactor Homothorax (Hth), revealing a striking similarity with the Ubx binding profile. We suggest that these binding profiles may be strongly influenced by chromatin accessibility and provide evidence of a link between Ubx/Hth binding and chromatin state at genes regulated by Polycomb silencing. Overall, we define a set of direct Ubx targets in the haltere imaginal disc and suggest that chromatin accessibility has important implications for Hox target selection and for transcription factor binding in general.
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Affiliation(s)
- Siew Woh Choo
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Robert White
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| | - Steven Russell
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
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Slattery M, Ma L, Négre N, White KP, Mann RS. Genome-wide tissue-specific occupancy of the Hox protein Ultrabithorax and Hox cofactor Homothorax in Drosophila. PLoS One 2011; 6:e14686. [PMID: 21483663 PMCID: PMC3071676 DOI: 10.1371/journal.pone.0014686] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 01/21/2011] [Indexed: 11/18/2022] Open
Abstract
The Hox genes are responsible for generating morphological diversity along the
anterior-posterior axis during animal development. The
Drosophila Hox gene Ultrabithorax
(Ubx), for example, is required for specifying the identity
of the third thoracic (T3) segment of the adult, which includes the dorsal
haltere, an appendage required for flight, and the ventral T3 leg.
Ubx mutants show homeotic transformations of the T3 leg
towards the identity of the T2 leg and the haltere towards the wing. All Hox
genes, including Ubx, encode homeodomain containing
transcription factors, raising the question of what target genes
Ubx regulates to generate these adult structures. To
address this question, we carried out whole genome ChIP-chip studies to identify
all of the Ubx bound regions in the haltere and T3 leg imaginal discs, which are
the precursors to these adult structures. In addition, we used ChIP-chip to
identify the sites bound by the Hox cofactor, Homothorax (Hth). In contrast to
previous ChIP-chip studies carried out in Drosophila embryos,
these binding studies reveal that there is a remarkable amount of tissue- and
transcription factor-specific binding. Analyses of the putative target genes
bound and regulated by these factors suggest that Ubx regulates many downstream
transcription factors and developmental pathways in the haltere and T3 leg.
Finally, we discovered additional DNA sequence motifs that in some cases are
specific for individual data sets, arguing that Ubx and/or Hth work together
with many regionally expressed transcription factors to execute their functions.
Together, these data provide the first whole-genome analysis of the binding
sites and target genes regulated by Ubx to specify the morphologies of the adult
T3 segment of the fly.
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Affiliation(s)
- Matthew Slattery
- Department of Biochemistry and Molecular
Biophysics, Columbia University, New York, New York, United States of
America
| | - Lijia Ma
- Department of Human Genetics, Department of
Ecology and Evolution, Institute for Genomics and Systems Biology, University of
Chicago, Chicago, Illinois, United States of America
| | - Nicolas Négre
- Department of Human Genetics, Department of
Ecology and Evolution, Institute for Genomics and Systems Biology, University of
Chicago, Chicago, Illinois, United States of America
| | - Kevin P. White
- Department of Human Genetics, Department of
Ecology and Evolution, Institute for Genomics and Systems Biology, University of
Chicago, Chicago, Illinois, United States of America
| | - Richard S. Mann
- Department of Biochemistry and Molecular
Biophysics, Columbia University, New York, New York, United States of
America
- * E-mail:
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Pavlopoulos A, Akam M. Hox gene Ultrabithorax regulates distinct sets of target genes at successive stages of Drosophila haltere morphogenesis. Proc Natl Acad Sci U S A 2011; 108:2855-60. [PMID: 21282633 DOI: 10.1073/pnas.1015077108] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hox genes encode highly conserved transcription factors that regionalize the animal body axis by controlling complex developmental processes. Although they are known to operate in multiple cell types and at different stages, we are still missing the batteries of genes targeted by any one Hox gene over the course of a single developmental process to achieve a particular cell and organ morphology. The transformation of wings into halteres by the Hox gene Ultrabithorax (Ubx) in Drosophila melanogaster presents an excellent model system to study the Hox control of transcriptional networks during successive stages of appendage morphogenesis and cell differentiation. We have used an inducible misexpression system to switch on Ubx in the wing epithelium at successive stages during metamorphosis--in the larva, prepupa, and pupa. We have then used extensive microarray expression profiling and quantitative RT-PCR to identify the primary transcriptional responses to Ubx. We find that Ubx targets range from regulatory genes like transcription factors and signaling components to terminal differentiation genes affecting a broad repertoire of cell behaviors and metabolic reactions. Ubx up- and down-regulates hundreds of downstream genes at each stage, mostly in a subtle manner. Strikingly, our analysis reveals that Ubx target genes are largely distinct at different stages of appendage morphogenesis, suggesting extensive interactions between Hox genes and hormone-controlled regulatory networks to orchestrate complex genetic programs during metamorphosis.
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Abstract
Animal shape and size is controlled with amazing precision during development. External factors such as nutrient availability and crowding can alter overall animal size, but individual body parts scale reproducibly to match the body even with challenges from a changing environment. How is such precision achieved? Here, we review selected research from the last few years in Drosophila--arguably the premier genetic model for the study of animal growth--that sheds light on how body and tissue size are regulated by forces intrinsic to individual organs. We focus on two topics currently under intense study: the influence of pattern regulators on organ and tissue growth and the role of local competitive interactions between cells in tissue homeostasis and final size.
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Affiliation(s)
- Ricardo M Neto-Silva
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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Lapraz F, Besnardeau L, Lepage T. Patterning of the dorsal-ventral axis in echinoderms: insights into the evolution of the BMP-chordin signaling network. PLoS Biol 2009; 7:e1000248. [PMID: 19956794 PMCID: PMC2772021 DOI: 10.1371/journal.pbio.1000248] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Accepted: 10/14/2009] [Indexed: 01/18/2023] Open
Abstract
Formation of the dorsal-ventral axis of the sea urchin embryo relies on cell interactions initiated by the TGFbeta Nodal. Intriguingly, although nodal expression is restricted to the ventral side of the embryo, Nodal function is required for specification of both the ventral and the dorsal territories and is able to restore both ventral and dorsal regions in nodal morpholino injected embryos. The molecular basis for the long-range organizing activity of Nodal is not understood. In this paper, we provide evidence that the long-range organizing activity of Nodal is assured by a relay molecule synthesized in the ventral ectoderm, then translocated to the opposite side of the embryo. We identified this relay molecule as BMP2/4 based on the following arguments. First, blocking BMP2/4 function eliminated the long-range organizing activity of an activated Nodal receptor in an axis rescue assay. Second, we demonstrate that BMP2/4 and the corresponding type I receptor Alk3/6 functions are both essential for specification of the dorsal region of the embryo. Third, using anti-phospho-Smad1/5/8 immunostaining, we show that, despite its ventral transcription, the BMP2/4 ligand triggers receptor mediated signaling exclusively on the dorsal side of the embryo, one of the most extreme cases of BMP translocation described so far. We further report that the pattern of pSmad1/5/8 is graded along the dorsal-ventral axis and that two BMP2/4 target genes are expressed in nested patterns centered on the region with highest levels of pSmad1/5/8, strongly suggesting that BMP2/4 is acting as a morphogen. We also describe the very unusual ventral co-expression of chordin and bmp2/4 downstream of Nodal and demonstrate that Chordin is largely responsible for the spatial restriction of BMP2/4 signaling to the dorsal side. Thus, unlike in most organisms, in the sea urchin, a single ventral signaling centre is responsible for induction of ventral and dorsal cell fates. Finally, we show that Chordin may not be required for long-range diffusion of BMP2/4, describe a striking dorsal-ventral asymmetry in the expression of Glypican 5, a heparin sulphated proteoglycan that regulates BMP mobility, and show that this asymmetry depends on BMP2/4 signaling. Our study provides new insights into the mechanisms by which positional information is established along the dorsal-ventral axis of the sea urchin embryo, and more generally on how a BMP morphogen gradient is established in a multicellular embryo. From an evolutionary point of view, it highlights that although the genes used for dorsal-ventral patterning are highly conserved in bilateria, there are considerable variations, even among deuterostomes, in the manner these genes are used to shape a BMP morphogen gradient.
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Affiliation(s)
- François Lapraz
- UPMC (University of Paris 06), CNRS, UMR7009, Biologie du Développement, Observatoire Océanologique, Villefranche-sur-Mer, France
| | - Lydia Besnardeau
- UPMC (University of Paris 06), CNRS, UMR7009, Biologie du Développement, Observatoire Océanologique, Villefranche-sur-Mer, France
| | - Thierry Lepage
- UPMC (University of Paris 06), CNRS, UMR7009, Biologie du Développement, Observatoire Océanologique, Villefranche-sur-Mer, France
- * E-mail:
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Kannan R, Berger C, Myneni S, Technau GM, Shashidhara LS. Abdominal-A mediated repression of Cyclin E expression during cell-fate specification in the Drosophila central nervous system. Mech Dev 2009; 127:137-45. [PMID: 19799999 DOI: 10.1016/j.mod.2009.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 01/17/2023]
Abstract
Homeotic/Hox genes are known to specify a given developmental pathway by regulating the expression of downstream effector genes. During embryonic CNS development of Drosophila, the Hox protein Abdominal-A (AbdA) is required for the specification of the abdominal NB6-4 lineage. It does so by down regulating the expression of the cell cycle regulator gene Dcyclin E (CycE). CycE is normally expressed in the thoracic NB6-4 lineage to give rise to mixed lineage of neurons and glia, while only glial cells are produced from the abdominal NB6-4 lineage due to the repression of CycE by AbdA. Here we investigate how AbdA represses the expression of CycE to define the abdominal fate of a single NB6-4 precursor cell. We analyze, both in vitro and in vivo, the regulation of a 1.9 kb CNS-specific CycE enhancer element in the abdominal NB6-4 lineage. We show that CycE is a direct target of AbdA and it binds to the CNS specific enhancer of CycE to specifically repress the enhancer activity in vivo. Our results suggest preferential involvement of a series of multiple AbdA binding sites to selectively enhance the repression of CycE transcription. Furthermore, our data suggest a complex network to regulate CycE expression where AbdA functions as a key regulator.
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Abstract
How size is controlled during animal development remains a fascinating problem despite decades of research. Here we review key concepts in size biology and develop our thesis that much can be learned by studying how different organ sizes are differentially scaled by homeotic selector genes. A common theme from initial studies using this approach is that morphogen pathways are modified in numerous ways by selector genes to effect size control. We integrate these results with other pathways known to regulate organ size in developing a comprehensive model for organ size control.
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Affiliation(s)
- Michael A Crickmore
- Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, NY, USA
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Baena-Lopez LA, Rodríguez I, Baonza A. The tumor suppressor genes dachsous and fat modulate different signalling pathways by regulating dally and dally-like. Proc Natl Acad Sci U S A 2008; 105:9645-50. [PMID: 18621676 DOI: 10.1073/pnas.0803747105] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The activity of different signaling pathways must be precisely regulated during development to define the final size and pattern of an organ. The Drosophila tumor suppressor genes dachsous (ds) and fat (ft) modulate organ size and pattern formation during imaginal disc development. Recent studies have proposed that Fat acts through the conserved Hippo signaling pathway to repress the expression of cycE, bantam, and diap-1. However, the combined ectopic expression of all of these target genes does not account for the hyperplasic phenotypes and patterning defects displayed by Hippo pathway mutants. Here, we identify the glypicans dally and dally-like as two target genes for both ft and ds acting via the Hippo pathway. Dally and Dally-like modulate organ growth and patterning by regulating the diffusion and efficiency of signaling of several morphogens such as Decapentaplegic, Hedgehog, and Wingless. Our findings therefore provide significant insights into the mechanisms by which mutations in the Hippo pathway genes can simultaneously alter the activity of several signaling pathways, compromising the control of growth and pattern formation.
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Lebreton G, Faucher C, Cribbs DL, Benassayag C. Timing of Wingless signalling distinguishes maxillary and antennal identities in Drosophila melanogaster. Development 2008; 135:2301-9. [DOI: 10.1242/dev.017053] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila adult head mostly derives from the composite eye-antenna imaginal disc. The antennal disc gives rise to two adult olfactory organs: the antennae and maxillary palps. Here, we have analysed the regional specification of the maxillary palp within the antennal disc. We found that a maxillary field, defined by expression of the Hox gene Deformed, is established at about the same time as the eye and antennal fields during the L2 larval stage. The genetic program leading to maxillary regionalisation and identity is very similar to the antennal one, but is distinguished primarily by delayed prepupal expression of the ventral morphogen Wingless (Wg). We find that precociously expressing Wg in the larval maxillary field suffices to transform it towards antennal identity, whereas overexpressing Wg later in prepupae does not. These results thus indicate that temporal regulation of Wg is decisive to distinguishing maxillary and antennal organs. Wg normally acts upstream of the antennal selector spineless (ss) in maxillary development. However, mis-expression of Ss can prematurely activate wg via a positive-feedback loop leading to a maxillary-to-antenna transformation. We characterised: (1) the action of Wg through ssselector function in distinguishing maxillary from antenna; and (2) its direct contribution to identity choice.
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Affiliation(s)
- Gaëlle Lebreton
- Centre de Biologie du Développement, UMR 5547 and IFR 109,Université de Toulouse and CNRS, 118 route de Narbonne, Bâtiment 4R3, 31062 Toulouse Cedex, France
| | - Christian Faucher
- Centre de Biologie du Développement, UMR 5547 and IFR 109,Université de Toulouse and CNRS, 118 route de Narbonne, Bâtiment 4R3, 31062 Toulouse Cedex, France
| | - David L. Cribbs
- Centre de Biologie du Développement, UMR 5547 and IFR 109,Université de Toulouse and CNRS, 118 route de Narbonne, Bâtiment 4R3, 31062 Toulouse Cedex, France
| | - Corinne Benassayag
- Centre de Biologie du Développement, UMR 5547 and IFR 109,Université de Toulouse and CNRS, 118 route de Narbonne, Bâtiment 4R3, 31062 Toulouse Cedex, France
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Kicheva A, González-Gaitán M. The Decapentaplegic morphogen gradient: a precise definition. Curr Opin Cell Biol 2008; 20:137-43. [PMID: 18329870 DOI: 10.1016/j.ceb.2008.01.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 01/30/2008] [Indexed: 01/11/2023]
Abstract
Two key processes are in the basis of morphogenesis: the spatial allocation of cell types in fields of naïve cells and the regulation of growth. Both are controlled by morphogens, which activate target genes in the growing tissue in a concentration-dependent manner. Thus the morphogen model is an intrinsically quantitative concept. However, quantitative studies were performed only in recent years on two morphogens: Bicoid and Decapentaplegic. This review covers quantitative aspects of the formation and precision of the Decapentaplegic morphogen gradient. The morphogen gradient concept is transitioning from a soft definition to a precise idea of what the gradient could really do.
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Affiliation(s)
- Anna Kicheva
- Department of Biochemistry, University of Geneva, Sciences II, Quai E. Ansermet 30, 1211 Geneva, Switzerland
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32
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Abstract
Animal bodies are composed of structures that vary in size and shape within and between species. Selector genes generate these differences by altering the expression of effector genes whose identities are largely unknown. Prime candidates for such effector genes are components of morphogen signaling pathways, which control growth and patterning during development. Here we show that in Drosophila the Hox selector gene Ultrabithorax (Ubx) modulates morphogen signaling in the haltere through transcriptional regulation of the glypican dally. Ubx, in combination with the posterior selector gene engrailed (en), represses dally expression in the posterior (P) compartment of the haltere. Compared with the serially homologous wing, where Ubx is not expressed, low levels of posterior dally in the haltere contribute to a reduced P compartment size and an overall smaller appendage size. We also show that one molecular consequence of dally repression in the posterior haltere is to reduce Dpp diffusion into and through the P compartment. Our results suggest that Dpp mobility is biased towards cells with higher levels of Dally and that selector genes modulate organ development by regulating glypican levels.
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Affiliation(s)
- Michael A Crickmore
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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