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Spitzer DC, Sun WY, Rodríguez-Vargas A, Hariharan IK. The cell adhesion molecule Echinoid promotes tissue survival and separately restricts tissue overgrowth in Drosophila imaginal discs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.552072. [PMID: 37577631 PMCID: PMC10418178 DOI: 10.1101/2023.08.04.552072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The interactions that cells in Drosophila imaginal discs have with their neighbors are known to regulate their ability to survive. In a screen of genes encoding cell surface proteins for gene knockdowns that affect the size or shape of mutant clones, we found that clones of cells with reduced levels of echinoid (ed) are fewer, smaller, and can be eliminated during development. In contrast, discs composed mostly of ed mutant tissue are overgrown. We find that ed mutant tissue has lower levels of the anti-apoptotic protein Diap1 and has increased levels of apoptosis which is consistent with the observed underrepresentation of ed mutant clones and the slow growth of ed mutant tissue. The eventual overgrowth of ed mutant tissue results not from accelerated growth, but from prolonged growth resulting from a failure to arrest growth at the appropriate final size. Ed has previously been shown to physically interact with multiple Hippo-pathway components and it has been proposed to promote Hippo pathway signaling, to exclude Yorkie (Yki) from the nucleus, and restrain the expression of Yki-target genes. We did not observe changes in Yki localization in ed mutant tissue and found decreased levels of expression of several Yorkie-target genes, findings inconsistent with the proposed effect of Ed on Yki. We did, however, observe increased expression of several Yki-target genes in wild-type cells neighboring ed mutant cells, which may contribute to elimination of ed mutant clones. Thus, ed has two distinct functions: an anti-apoptotic function by maintaining Diap1 levels, and a function to arrest growth at the appropriate final size. Both of these are unlikely to be explained by a simple effect on the Hippo pathway.
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Affiliation(s)
- Danielle C. Spitzer
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley CA 94720-3200
| | - William Y. Sun
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley CA 94720-3200
| | - Anthony Rodríguez-Vargas
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley CA 94720-3200
| | - Iswar K. Hariharan
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley CA 94720-3200
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2
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Valencia-Expósito A, Gómez-Lamarca MJ, Widmann TJ, Martín-Bermudo MD. Integrins Cooperate With the EGFR/Ras Pathway to Preserve Epithelia Survival and Architecture in Development and Oncogenesis. Front Cell Dev Biol 2022; 10:892691. [PMID: 35769262 PMCID: PMC9234701 DOI: 10.3389/fcell.2022.892691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
Adhesion to the extracellular matrix (ECM) is required for normal epithelial cell survival. Disruption of this interaction leads to a specific type of apoptosis known as anoikis. Yet, there are physiological and pathological situations in which cells not connected to the ECM are protected from anoikis, such as during cell migration or metastasis. The main receptors transmitting signals from the ECM are members of the integrin family. However, although integrin-mediated cell-ECM anchorage has been long recognized as crucial for epithelial cell survival, the in vivo significance of this interaction remains to be weighed. In this work, we have used the Drosophila wing imaginal disc epithelium to analyze the importance of integrins as survival factors during epithelia morphogenesis. We show that reducing integrin expression in the wing disc induces caspase-dependent cell death and basal extrusion of the dead cells. In this case, anoikis is mediated by the activation of the JNK pathway, which in turn triggers expression of the proapoptotic protein Hid. In addition, our results strongly suggest that, during wing disc morphogenesis, the EGFR pathway protects cells undergoing cell shape changes upon ECM detachment from anoikis. Furthermore, we show that oncogenic activation of the EGFR/Ras pathway in integrin mutant cells rescues them from apoptosis while promoting their extrusion from the epithelium. Altogether, our results support the idea that integrins promote cell survival during normal tissue morphogenesis and prevent the extrusion of transformed cells.
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Affiliation(s)
| | - M. Jesús Gómez-Lamarca
- Centro Andaluz de Biología del Desarrollo CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- Departamento de Biología Celular, Universidad de Sevilla, Sevilla, Spain
| | | | - María D. Martín-Bermudo
- Centro Andaluz de Biología del Desarrollo CSIC-Universidad Pablo de Olavide, Sevilla, Spain
- *Correspondence: María D. Martín-Bermudo,
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3
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Mongelli V, Lequime S, Kousathanas A, Gausson V, Blanc H, Nigg J, Quintana-Murci L, Elena SF, Saleh MC. Innate immune pathways act synergistically to constrain RNA virus evolution in Drosophila melanogaster. Nat Ecol Evol 2022; 6:565-578. [PMID: 35273366 PMCID: PMC7612704 DOI: 10.1038/s41559-022-01697-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 12/14/2021] [Indexed: 02/05/2023]
Abstract
Host-pathogen interactions impose recurrent selective pressures that lead to constant adaptation and counter-adaptation in both competing species. Here, we sought to study this evolutionary arms-race and assessed the impact of the innate immune system on viral population diversity and evolution, using Drosophila melanogaster as model host and its natural pathogen Drosophila C virus (DCV). We isogenized eight fly genotypes generating animals defective for RNAi, Imd and Toll innate immune pathways as well as pathogen-sensing and gut renewal pathways. Wild-type or mutant flies were then orally infected with DCV and the virus was serially passaged ten times via reinfection in naive flies. Viral population diversity was studied after each viral passage by high-throughput sequencing and infection phenotypes were assessed at the beginning and at the end of the evolution experiment. We found that the absence of any of the various immune pathways studied increased viral genetic diversity while attenuating virulence. Strikingly, these effects were observed in a range of host factors described as having mainly antiviral or antibacterial functions. Together, our results indicate that the innate immune system as a whole and not specific antiviral defence pathways in isolation, generally constrains viral diversity and evolution.
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Affiliation(s)
- Vanesa Mongelli
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS, Paris, France
| | - Sebastian Lequime
- Cluster of Microbial Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | | | - Valérie Gausson
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS, Paris, France
| | - Hervé Blanc
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS, Paris, France
| | - Jared Nigg
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS, Paris, France
| | - Lluis Quintana-Murci
- Human Evolutionary Genetic Unit, Institut Pasteur, CNRS, Paris, France
- Human Genomics and Evolution, Collège de France, Paris, France
| | - Santiago F Elena
- Instituto de Biología Integrativa de Sistemas (CSIC-Universitat de València), València, Spain.
- The Santa Fe Institute, Santa Fe, NM, USA.
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS, Paris, France.
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4
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Soler Beatty J, Molnar C, Luque CM, de Celis JF, Martín-Bermudo MD. EGFRAP encodes a new negative regulator of the EGFR acting in both normal and oncogenic EGFR/Ras-driven tissue morphogenesis. PLoS Genet 2021; 17:e1009738. [PMID: 34411095 PMCID: PMC8407591 DOI: 10.1371/journal.pgen.1009738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 08/31/2021] [Accepted: 07/23/2021] [Indexed: 12/27/2022] Open
Abstract
Activation of Ras signaling occurs in ~30% of human cancers. However, activated Ras alone is insufficient to produce malignancy. Thus, it is imperative to identify those genes cooperating with activated Ras in driving tumoral growth. In this work, we have identified a novel EGFR inhibitor, which we have named EGFRAP, for EGFR adaptor protein. Elimination of EGFRAP potentiates activated Ras-induced overgrowth in the Drosophila wing imaginal disc. We show that EGFRAP interacts physically with the phosphorylated form of EGFR via its SH2 domain. EGFRAP is expressed at high levels in regions of maximal EGFR/Ras pathway activity, such as at the presumptive wing margin. In addition, EGFRAP expression is up-regulated in conditions of oncogenic EGFR/Ras activation. Normal and oncogenic EGFR/Ras-mediated upregulation of EGRAP levels depend on the Notch pathway. We also find that elimination of EGFRAP does not affect overall organogenesis or viability. However, simultaneous downregulation of EGFRAP and its ortholog PVRAP results in defects associated with increased EGFR function. Based on these results, we propose that EGFRAP is a new negative regulator of the EGFR/Ras pathway, which, while being required redundantly for normal morphogenesis, behaves as an important modulator of EGFR/Ras-driven tissue hyperplasia. We suggest that the ability of EGFRAP to functionally inhibit the EGFR pathway in oncogenic cells results from the activation of a feedback loop leading to increase EGFRAP expression. This could act as a surveillance mechanism to prevent excessive EGFR activity and uncontrolled cell growth. Activation of Ras signalling occurs in ~30% of human cancers. However, activated Ras alone is insufficient to produce malignancy. Thus, the discovery of genes cooperating with Ras in cancer is imperative to understand tumoral growth driven by Ras activating mutations. A key output of over-activated EGFR/Ras signalling is the induction of a complex and dynamic set of transcriptional networks leading to changes in gene expression. As a result of these changes, the normal function of some genes can become adjusted in a tumorigenic context. In this work, using the Drosophila wing imaginal disc as model system, we have identified a new EGFR inhibitor, EGFRAP, which function is redundant for proper morphogenesis, yet becomes an important limiter of the overgrowth driven by oncogenic EGFR/Ras activity. We show that the specificity of EGFRAP in cells with high levels of EGFR activity arises from activation of a negative feedback loop resulting in increased EGFRAP levels. This could act to prevent excessive EGFR activity and uncontrolled cell growth. We believe the identification of other factors behaving like EGFRAP, will help in our fight against cancer, as it might lead to the identification of new therapeutic drugs affecting cancer but not normal cells, a top priority in cancer research.
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Affiliation(s)
- Jennifer Soler Beatty
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/JA, Sevilla, Spain
| | - Cristina Molnar
- Centro de Biología Molecular Severo Ochoa (UAM/CSIC), Univ. Autónoma de Madrid, Madrid, Spain
| | - Carlos M. Luque
- Centro de Biología Molecular Severo Ochoa (UAM/CSIC), Univ. Autónoma de Madrid, Madrid, Spain
| | - Jose F. de Celis
- Centro de Biología Molecular Severo Ochoa (UAM/CSIC), Univ. Autónoma de Madrid, Madrid, Spain
| | - María D. Martín-Bermudo
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/JA, Sevilla, Spain
- * E-mail:
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Kushnir T, Bar-Cohen S, Mooshayef N, Lange R, Bar-Sinai A, Rozen H, Salzberg A, Engelberg D, Paroush Z. An Activating Mutation in ERK Causes Hyperplastic Tumors in a scribble Mutant Tissue in Drosophila. Genetics 2020; 214:109-120. [PMID: 31740452 PMCID: PMC6944410 DOI: 10.1534/genetics.119.302794] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 10/23/2019] [Indexed: 12/19/2022] Open
Abstract
Receptor tyrosine kinase signaling plays prominent roles in tumorigenesis, and activating oncogenic point mutations in the core pathway components Ras, Raf, or MEK are prevalent in many types of cancer. Intriguingly, however, analogous oncogenic mutations in the downstream effector kinase ERK have not been described or validated in vivo To determine if a point mutation could render ERK intrinsically active and oncogenic, we have assayed in Drosophila the effects of a mutation that confers constitutive activity upon a yeast ERK ortholog and has also been identified in a few human tumors. Our analyses indicate that a fly ERK ortholog harboring this mutation alone (RolledR80S), and more so in conjunction with the known sevenmaker mutation (RolledR80S+D334N), suppresses multiple phenotypes caused by loss of Ras-Raf-MEK pathway activity, consistent with an intrinsic activity that is independent of upstream signaling. Moreover, expression of RolledR80S and RolledR80S+D334N induces tissue overgrowth in an established Drosophila cancer model. Our findings thus demonstrate that activating mutations can bestow ERK with pro-proliferative, tumorigenic capabilities and suggest that Drosophila represents an effective experimental system for determining the oncogenicity of ERK mutants and their response to therapy.
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Affiliation(s)
- Tatyana Kushnir
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Shaked Bar-Cohen
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Navit Mooshayef
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
- Singapore-Hebrew University of Jerusalem Alliance for Research and Enterprise, Molecular Mechanisms of Inflammatory Diseases Interdisciplinary Research Group, Campus for Research Excellence and Technological Enterprise, 138602, Singapore
| | - Rotem Lange
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Allan Bar-Sinai
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Helit Rozen
- Faculty of Medicine in the Galilee, Bar-Ilan University, Safed 1311502, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - David Engelberg
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
- Singapore-Hebrew University of Jerusalem Alliance for Research and Enterprise, Molecular Mechanisms of Inflammatory Diseases Interdisciplinary Research Group, Campus for Research Excellence and Technological Enterprise, 138602, Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore
| | - Ze'ev Paroush
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
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6
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A fat-tissue sensor couples growth to oxygen availability by remotely controlling insulin secretion. Nat Commun 2019; 10:1955. [PMID: 31028268 PMCID: PMC6486587 DOI: 10.1038/s41467-019-09943-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 04/10/2019] [Indexed: 12/22/2022] Open
Abstract
Organisms adapt their metabolism and growth to the availability of nutrients and oxygen, which are essential for development, yet the mechanisms by which this adaptation occurs are not fully understood. Here we describe an RNAi-based body-size screen in Drosophila to identify such mechanisms. Among the strongest hits is the fibroblast growth factor receptor homolog breathless necessary for proper development of the tracheal airway system. Breathless deficiency results in tissue hypoxia, sensed primarily in this context by the fat tissue through HIF-1a prolyl hydroxylase (Hph). The fat relays its hypoxic status through release of one or more HIF-1a-dependent humoral factors that inhibit insulin secretion from the brain, thereby restricting systemic growth. Independently of HIF-1a, Hph is also required for nutrient-dependent Target-of-rapamycin (Tor) activation. Our findings show that the fat tissue acts as the primary sensor of nutrient and oxygen levels, directing adaptation of organismal metabolism and growth to environmental conditions. The mechanisms by which organisms adapt their growth according to the availability of oxygen are incompletely understood. Here the authors identify the Drosophila fat body as a tissue regulating growth in response to oxygen sensing via a mechanism involving Hph inhibition, HIF1-a activation and insulin secretion.
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7
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Campbell K, Lebreton G, Franch-Marro X, Casanova J. Differential roles of the Drosophila EMT-inducing transcription factors Snail and Serpent in driving primary tumour growth. PLoS Genet 2018; 14:e1007167. [PMID: 29420531 PMCID: PMC5821384 DOI: 10.1371/journal.pgen.1007167] [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: 06/12/2017] [Revised: 02/21/2018] [Accepted: 12/25/2017] [Indexed: 02/06/2023] Open
Abstract
Several transcription factors have been identified that activate an epithelial-to-mesenchymal transition (EMT), which endows cells with the capacity to break through basement membranes and migrate away from their site of origin. A key program in development, in recent years it has been shown to be a crucial driver of tumour invasion and metastasis. However, several of these EMT-inducing transcription factors are often expressed long before the initiation of the invasion-metastasis cascade as well as in non-invasive tumours. Increasing evidence suggests that they may promote primary tumour growth, but their precise role in this process remains to be elucidated. To investigate this issue we have focused our studies on two Drosophila transcription factors, the classic EMT inducer Snail and the Drosophila orthologue of hGATAs4/6, Serpent, which drives an alternative mechanism of EMT; both Snail and GATA are specifically expressed in a number of human cancers, particularly at the invasive front and in metastasis. Thus, we recreated conditions of Snail and of Serpent high expression in the fly imaginal wing disc and analysed their effect. While either Snail or Serpent induced a profound loss of epithelial polarity and tissue organisation, Serpent but not Snail also induced an increase in the size of wing discs. Furthermore, the Serpent-induced tumour-like tissues were able to grow extensively when transplanted into the abdomen of adult hosts. We found the differences between Snail and Serpent to correlate with the genetic program they elicit; while activation of either results in an increase in the expression of Yorki target genes, Serpent additionally activates the Ras signalling pathway. These results provide insight into how transcription factors that induce EMT can also promote primary tumour growth, and how in some cases such as GATA factors a ‘multi hit’ effect may be achieved through the aberrant activation of just a single gene. Many cancer cells acquire abnormal motility behaviour leading to metastasis, the main cause of cancer related deaths. In many cancers, transcription factors capable of inducing motile migratory cell behaviours, so-called EMT transcription factors, are found highly expressed. However, the expression of these genes is not restricted to metastatic invasive cancers; they are often found in benign tumours, or in tumours long before they show any sign of metastasis. This observation motivated us to ask if they may play a role in driving primary tumour growth. Our results show that the Drosophila EMT-inducers Snail and Serpent are both capable of driving overproliferation. However, Snail overproliferation is accompanied by a decrease in cell size as well as cell death, and consequently the tissue does not increase in size. Serpent also drives cell proliferation but this occurs together with an increase in cell size, but not cell death, thus having a profound effect on the overall size of the tissue. We show that both Snail and Serpent trigger activation of the Yorki pathway and in addition Serpent, but not Snail, also triggers activation of the Ras pathway. These results provide insight into how activation of some EMT-inducing genes can also promote primary tumour growth.
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Affiliation(s)
- Kyra Campbell
- Institut de Biologia Molecular de Barcelona (CSIC), Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
- * E-mail: (KC); (JC)
| | - Gaëlle Lebreton
- Institut de Biologia Molecular de Barcelona (CSIC), Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Xavier Franch-Marro
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Functional Genomics and Evolution, Department Passeig Marítim de la Barceloneta, Barcelona, Spain
| | - Jordi Casanova
- Institut de Biologia Molecular de Barcelona (CSIC), Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
- * E-mail: (KC); (JC)
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8
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Bala Tannan N, Collu G, Humphries AC, Serysheva E, Weber U, Mlodzik M. AKAP200 promotes Notch stability by protecting it from Cbl/lysosome-mediated degradation in Drosophila melanogaster. PLoS Genet 2018; 14:e1007153. [PMID: 29309414 PMCID: PMC5785023 DOI: 10.1371/journal.pgen.1007153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 01/25/2018] [Accepted: 12/13/2017] [Indexed: 12/30/2022] Open
Abstract
AKAP200 is a Drosophila melanogaster member of the “A Kinase Associated Protein” family of scaffolding proteins, known for their role in the spatial and temporal regulation of Protein Kinase A (PKA) in multiple signaling contexts. Here, we demonstrate an unexpected function of AKAP200 in promoting Notch protein stability. In Drosophila, AKAP200 loss-of-function (LOF) mutants show phenotypes that resemble Notch LOF defects, including eye patterning and sensory organ specification defects. Through genetic interactions, we demonstrate that AKAP200 interacts positively with Notch in both the eye and the thorax. We further show that AKAP200 is part of a physical complex with Notch. Biochemical studies reveal that AKAP200 stabilizes endogenous Notch protein, and that it limits ubiquitination of Notch. Specifically, our genetic and biochemical evidence indicates that AKAP200 protects Notch from the E3-ubiquitin ligase Cbl, which targets Notch to the lysosomal pathway. Indeed, we demonstrate that the effect of AKAP200 on Notch levels depends on the lysosome. Interestingly, this function of AKAP200 is fully independent of its role in PKA signaling and independent of its ability to bind PKA. Taken together, our data indicate that AKAP200 is a novel tissue specific posttranslational regulator of Notch, maintaining high Notch protein levels and thus promoting Notch signaling. AKAP200 belongs to a family of scaffolding proteins best known for their regulation of PKA localization. In this study, we have identified a novel role of AKAP200 in Notch protein stability and signaling. In Drosophila melanogaster, AKAP200’s loss and gain-of-function (LOF/GOF) phenotypes are characteristic of Notch signaling defects. Furthermore, we demonstrated genetic interactions between AKAP200 and Notch. Consistent with this, AKAP200 stabilizes the endogenous Notch protein and limits its ubiquitination. AKAP200 exerts its effects on Notch by antagonizing Cbl-mediated ubiquitination and thus lysosome targeting of Notch. Based on these data, we postulate a novel PKA independent mechanism of AKAP200 to achieve optimal Notch protein levels, with AKAP200 preventing Cbl-mediated lysosomal degradation of Notch.
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Affiliation(s)
- Neeta Bala Tannan
- Dept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Giovanna Collu
- Dept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Ashley C. Humphries
- Dept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Ekatherina Serysheva
- Dept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Ursula Weber
- Dept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Marek Mlodzik
- Dept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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9
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Klebanow LR, Peshel EC, Schuster AT, De K, Sarvepalli K, Lemieux ME, Lenoir JJ, Moore AW, McDonald JA, Longworth MS. Drosophila Condensin II subunit Chromosome-associated protein D3 regulates cell fate determination through non-cell-autonomous signaling. Development 2016; 143:2791-802. [PMID: 27317808 PMCID: PMC5004906 DOI: 10.1242/dev.133686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 06/03/2016] [Indexed: 12/19/2022]
Abstract
The pattern of the Drosophila melanogaster adult wing is heavily influenced by the expression of proteins that dictate cell fate decisions between intervein and vein during development. dSRF (Blistered) expression in specific regions of the larval wing disc promotes intervein cell fate, whereas EGFR activity promotes vein cell fate. Here, we report that the chromatin-organizing protein CAP-D3 acts to dampen dSRF levels at the anterior/posterior boundary in the larval wing disc, promoting differentiation of cells into the anterior crossvein. CAP-D3 represses KNOT expression in cells immediately adjacent to the anterior/posterior boundary, thus blocking KNOT-mediated repression of EGFR activity and preventing cell death. Maintenance of EGFR activity in these cells depresses dSRF levels in the neighboring anterior crossvein progenitor cells, allowing them to differentiate into vein cells. These findings uncover a novel transcriptional regulatory network influencing Drosophila wing vein development, and are the first to identify a Condensin II subunit as an important regulator of EGFR activity and cell fate determination in vivo.
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Affiliation(s)
- Lindsey R Klebanow
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Emanuela C Peshel
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Andrew T Schuster
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Kuntal De
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Kavitha Sarvepalli
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | | | - Jessica J Lenoir
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA Department of Molecular Biosciences, Northwestern University, Evanston, IL 60201, USA
| | - Adrian W Moore
- Disease Mechanism Research Core, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | | | - Michelle S Longworth
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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10
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Housden BE, Perrimon N. Spatial and temporal organization of signaling pathways. Trends Biochem Sci 2014; 39:457-64. [PMID: 25155749 DOI: 10.1016/j.tibs.2014.07.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 12/14/2022]
Abstract
The development and maintenance of the many different cell types in metazoan organisms requires robust and diverse intercellular communication mechanisms. Relatively few such signaling pathways have been identified, leading to the question of how such a broad diversity of output is generated from relatively simple signals. Recent studies have revealed complex mechanisms integrating temporal and spatial information to generate diversity in signaling pathway output. We review some general principles of signaling pathways, focusing on transcriptional outputs in Drosophila. We consider the role of spatial and temporal aspects of different transduction pathways and then discuss how recently developed tools and approaches are helping to dissect the complex mechanisms linking pathway stimulation to output.
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Affiliation(s)
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
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11
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Valentine M, Hogan J, Collier S. The Drosophila Chmp1 protein determines wing cell fate through regulation of epidermal growth factor receptor signaling. Dev Dyn 2014; 243:977-87. [PMID: 24753138 DOI: 10.1002/dvdy.24140] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Receptor down-regulation by the multivesicular body (MVB) pathway is critical for many cellular signaling events. MVB generation is mediated by the highly conserved ESCRT (0, I, II, and III) protein complexes. Chmp1 is an ESCRT-III component and a putative tumor suppressor in humans. However, published data on Chmp1 activity are conflicting and its role during tissue development is not well defined. RESULTS We investigated the function of Drosophila Chmp1 and found that it is an essential gene. In the wing, loss of Chmp1 activity causes a cell fate change from intervein to vein, and interactions between Chmp1 and Drosophila Epidermal Growth Factor Receptor (DER) regulators suggest that Chmp1 negatively regulates DER signaling. Chmp1 knockdown also decreases Blistered expression, which is repressed by DER signaling. We find that Chmp1 protein localizes to the late endosome in Drosophila embryos, which is consistent with its effects on DER signaling resulting from its function in the ESCRT-III complex. CONCLUSIONS Drosophila Chmp1 negatively regulates DER signaling, likely through its role in MVB formation. Loss of Chmp1 activity in the Drosophila wing induces a cell fate change from intervein to vein that should provide a useful tool for future studies of ESCRT protein activity.
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Affiliation(s)
- Meagan Valentine
- Department of Biomedical Sciences, Marshall University, Huntington, West Virginia
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12
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Molnar C, de Celis JF. Tay bridge is a negative regulator of EGFR signalling and interacts with Erk and Mkp3 in the Drosophila melanogaster wing. PLoS Genet 2013; 9:e1003982. [PMID: 24348264 PMCID: PMC3861119 DOI: 10.1371/journal.pgen.1003982] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 10/14/2013] [Indexed: 11/18/2022] Open
Abstract
The regulation of Extracellular regulated kinase (Erk) activity is a key aspect of signalling by pathways activated by extracellular ligands acting through tyrosine kinase transmembrane receptors. In this process, participate proteins with kinase activity that phosphorylate and activate Erk, as well as different phosphatases that inactivate Erk by de-phosphorylation. The state of Erk phosphorylation affects not only its activity, but also its subcellular localization, defining the repertoire of Erk target proteins, and consequently, the cellular response to Erk. In this work, we characterise Tay bridge as a novel component of the EGFR/Erk signalling pathway. Tay bridge is a large nuclear protein with a domain of homology with human AUTS2, and was previously identified due to the neuronal phenotypes displayed by loss-of-function mutations. We show that Tay bridge antagonizes EGFR signalling in the Drosophila melanogaster wing disc and other tissues, and that the protein interacts with both Erk and Mkp3. We suggest that Tay bridge constitutes a novel element involved in the regulation of Erk activity, acting as a nuclear docking for Erk that retains this protein in an inactive form in the nucleus. Extracellular regulated kinases (Erk) mediate signalling by pathways activated by tyrosine kinase transmembrane receptors. The level of activated Erk depends on a highly regulated balance between cytoplasmic kinases and nuclear/cytoplasmic phosphatases, which determine the state of Erk phosphorylation. This affects Erk activity and its subcellular localization, defining the repertoire of Erk targets, and consequently, the cellular response to Erk. In this work, we use a genetic approach to characterise the gene tay bridge as a novel component of the EGFR/Erk signalling pathway. Tay bridge has a domain of homology with human AUTS2, and was previously identified due to the neuronal phenotypes displayed by loss-of-function mutations. We show that Tay bridge antagonizes EGFR signalling in the Drosophila melanogaster wing disc and other tissues, and that the protein interacts with both Erk and Mkp3. We suggest that Tay bridge constitutes a novel element involved in the regulation of Erk activity, acting as a nuclear docking for Erk that retains this protein in an inactive form in the nucleus. These results could provide important insights into the clinical consequences of AUTS2 mutations in humans, which are related to behavioural perturbations including autism, mental retardation, Attention Deficit Hyperactivity Disorder and alcohol drinking behaviour.
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Affiliation(s)
- Cristina Molnar
- Centro de Biología Molecular “Severo Ochoa,” CSIC and Universidad Autónoma de Madrid, Madrid, Spain
| | - Jose F. de Celis
- Centro de Biología Molecular “Severo Ochoa,” CSIC and Universidad Autónoma de Madrid, Madrid, Spain
- * E-mail:
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13
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An unexpected link between notch signaling and ROS in restricting the differentiation of hematopoietic progenitors in Drosophila. Genetics 2013; 197:471-83. [PMID: 24318532 DOI: 10.1534/genetics.113.159210] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A fundamental question in hematopoietic development is how multipotent progenitors achieve precise identities, while the progenitors themselves maintain quiescence. In Drosophila melanogaster larvae, multipotent hematopoietic progenitors support the production of three lineages, exhibit quiescence in response to cues from a niche, and from their differentiated progeny. Infection by parasitic wasps alters the course of hematopoiesis. Here we address the role of Notch (N) signaling in lamellocyte differentiation in response to wasp infection. We show that Notch activity is moderately high and ubiquitous in all cells of the lymph gland lobes, with crystal cells exhibiting the highest levels. Wasp infection reduces Notch activity, which results in fewer crystal cells and more lamellocytes. Robust lamellocyte differentiation is induced even in N mutants. Using RNA interference knockdown of N, Serrate, and neuralized (neur), and twin clone analysis of a N null allele, we show that all three genes inhibit lamellocyte differentiation. However, unlike its cell-autonomous function in crystal cell development, Notch's inhibitory influence on lamellocyte differentiation is not cell autonomous. High levels of reactive oxygen species in the lymph gland lobes, but not in the niche, accompany N(RNAi)-induced lamellocyte differentiation and lobe dispersal. Our results define a novel dual role for Notch signaling in maintaining competence for basal hematopoiesis: while crystal cell development is encouraged, lamellocytic fate remains repressed. Repression of Notch signaling in fly hematopoiesis is important for host defense against natural parasitic wasp infections. These findings can serve as a model to understand how reactive oxygen species and Notch signals are integrated and interpreted in vivo.
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14
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Dutriaux A, Godart A, Brachet A, Silber J. The insulin receptor is required for the development of the Drosophila peripheral nervous system. PLoS One 2013; 8:e71857. [PMID: 24069139 PMCID: PMC3772016 DOI: 10.1371/journal.pone.0071857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 07/09/2013] [Indexed: 01/12/2023] Open
Abstract
The Insulin Receptor (InR) in Drosophila presents features conserved in its mammalian counterparts. InR is required for growth; it is expressed in the central and embryonic nervous system and modulates the time of differentiation of the eye photoreceptor without altering cell fate. We show that the InR is required for the formation of the peripheral nervous system during larval development and more particularly for the formation of sensory organ precursors (SOPs) on the fly notum and scutellum. SOPs arise in the proneural cluster that expresses high levels of the proneural proteins Achaete (Ac) and Scute (Sc). The other cells will become epidermis due to lateral inhibition induced by the Notch (N) receptor signal that prevents its neighbors from adopting a neural fate. In addition, misexpression of the InR or of other components of the pathway (PTEN, Akt, FOXO) induces the development of an abnormal number of macrochaetes that are Drosophila mechanoreceptors. Our data suggest that InR regulates the neural genes ac, sc and sens. The FOXO transcription factor which is localized in the cytoplasm upon insulin uptake, displays strong genetic interaction with the InR and is involved in Ac regulation. The genetic interactions between the epidermal growth factor receptor (EGFR), Ras and InR/FOXO suggest that these proteins cooperate to induce neural gene expression. Moreover, InR/FOXO is probably involved in the lateral inhibition process, since genetic interactions with N are highly significant. These results show that the InR can alter cell fate, independently of its function in cell growth and proliferation.
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Affiliation(s)
- Annie Dutriaux
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
| | - Aurélie Godart
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
| | - Anna Brachet
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
| | - Joël Silber
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
- * E-mail:
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15
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Garcia M, Nahmad M, Reeves GT, Stathopoulos A. Size-dependent regulation of dorsal-ventral patterning in the early Drosophila embryo. Dev Biol 2013; 381:286-99. [PMID: 23800450 DOI: 10.1016/j.ydbio.2013.06.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/12/2013] [Accepted: 06/14/2013] [Indexed: 01/18/2023]
Abstract
How natural variation in embryo size affects patterning of the Drosophila embryo dorsal-ventral (DV) axis is not known. Here we examined quantitatively the relationship between nuclear distribution of the Dorsal transcription factor, boundary positions for several target genes, and DV axis length. Data were obtained from embryos of a wild-type background as well as from mutant lines inbred to size select embryos of smaller or larger sizes. Our data show that the width of the nuclear Dorsal gradient correlates with DV axis length. In turn, for some genes expressed along the DV axis, the boundary positions correlate closely with nuclear Dorsal levels and with DV axis length; while the expression pattern of others is relatively constant and independent of the width of the Dorsal gradient. In particular, the patterns of snail (sna) and ventral nervous system defective (vnd) correlate with nuclear Dorsal levels and exhibit scaling to DV length; while the pattern of intermediate neuroblasts defective (ind) remains relatively constant with respect to changes in Dorsal and DV length. However, in mutants that exhibit an abnormal expansion of the Dorsal gradient which fails to scale to DV length, only sna follows the Dorsal distribution and exhibits overexpansion; in contrast, vnd and ind do not overexpand suggesting some additional mechanism acts to refine the dorsal boundaries of these two genes. Thus, our results argue against the idea that the Dorsal gradient works as a global system of relative coordinates along the DV axis and suggest that individual targets respond to changes in embryo size in a gene-specific manner.
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Affiliation(s)
- Mayra Garcia
- Division of Biology, California Institute of Technology, Pasadena, CA, USA
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16
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Mutual repression by bantam miRNA and Capicua links the EGFR/MAPK and Hippo pathways in growth control. Curr Biol 2012; 22:651-7. [PMID: 22445297 DOI: 10.1016/j.cub.2012.02.050] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/07/2012] [Accepted: 02/17/2012] [Indexed: 01/01/2023]
Abstract
BACKGROUND The epidermal growth factor receptor (EGFR) and Hippo signaling pathways control cell proliferation and apoptosis to promote tissue growth during development. Misregulation of these pathways is implicated in cancer. Our understanding of the mechanisms that integrate the activity of these pathways remains fragmentary. This study identifies bantam microRNA as a common target of these pathways and suggests a mechanistic link between them. RESULTS The EGFR pathway acts through bantam to control tissue growth. bantam expression is regulated by the EGFR pathway, acting via repression of the transcriptional repressor Capicua. Thus EGFR signaling induces bantam expression by alleviating the effects of a repressor. bantam in turn acts in a negative feedback loop to limit Capicua expression. CONCLUSIONS bantam appears to be a transcriptional target of both the EGFR and Hippo growth control pathways. Feedback regulation by bantam on Capicua provides a means to link signal propagation by the EGFR pathway to activity of the Hippo pathway and may play an important role in integration of these two pathways in growth control.
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17
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Li S. Identification of iron-loaded ferritin as an essential mitogen for cell proliferation and postembryonic development in Drosophila. Cell Res 2010; 20:1148-57. [DOI: 10.1038/cr.2010.102] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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18
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Ogura T, Tan A, Tsubota T, Nakakura T, Shiotsuki T. Identification and expression analysis of ras gene in silkworm, Bombyx mori. PLoS One 2009; 4:e8030. [PMID: 19946625 PMCID: PMC2777509 DOI: 10.1371/journal.pone.0008030] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 10/24/2009] [Indexed: 12/15/2022] Open
Abstract
Ras proteins play important roles in development especially for cell proliferation and differentiation in various organisms. However, their functions in the most insect species are still not clear. We identified three ras cDNAs from the silk worm, Bombyx mori. These sequences corresponded to three Ras of Drosophila melanogaster, but not to three mammalian Ras (H-Ras, K-Ras, N-Ras). Subsequently, the expression profiles of ras were investigated by quantitative real-time PCR using whole body of individuals from the embryonic to adult stages, and various tissues of 4th and 5th instar larvae. Each of three Bombyx ras showed different expression patterns. We also showed membrane localization of their products. These results indicate that the three Bombyx Ras are functional and have different roles.
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Affiliation(s)
- Takehiko Ogura
- Department of Applied Life Sciences, Kyoto University, Kyoto, Japan
| | - Anjiang Tan
- Invertebrate Gene Function Research Unit, National Institute of Agrobiological Science, Tsukuba, Ibaraki, Japan
| | - Takuya Tsubota
- Invertebrate Gene Function Research Unit, National Institute of Agrobiological Science, Tsukuba, Ibaraki, Japan
| | - Takayo Nakakura
- Invertebrate Gene Function Research Unit, National Institute of Agrobiological Science, Tsukuba, Ibaraki, Japan
| | - Takahiro Shiotsuki
- Invertebrate Gene Function Research Unit, National Institute of Agrobiological Science, Tsukuba, Ibaraki, Japan
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19
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Terriente-Félix A, de Celis JF. Osa, a subunit of the BAP chromatin-remodelling complex, participates in the regulation of gene expression in response to EGFR signalling in the Drosophila wing. Dev Biol 2009; 329:350-61. [PMID: 19306864 DOI: 10.1016/j.ydbio.2009.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 03/05/2009] [Accepted: 03/12/2009] [Indexed: 01/27/2023]
Abstract
Gene expression is regulated in part by protein complexes containing ATP-dependent chromatin-remodelling factors of the SWI/SNF family. In Drosophila there is only one SWI/SNF protein, named Brahma, which forms the catalytic subunit of two complexes composed of different proteins. The protein Osa defines the BAP complex, and the proteins Polybromo and Bap170 are only present in the complex named PBAP. In this work we have analysed the functional requirements of Osa during Drosophila wing development, and found that osa is needed for cell growth and survival in the wing imaginal disc, and for the correct patterning of sensory organs, veins and the wing margin. Other members of the BAP complex, such as Snr1, Bap55, Mor and Brm, also share these functions of Osa. We focused on the requirement of Osa during the formation of the wing veins. Genetic interactions between osa alleles and mutations affecting the activity of the EGFR pathway suggest that one aspect of Osa is intimately related to the response to EGFR activity. Thus, loss of osa and EGFR signalling results in similar wing vein phenotypes, and osa alleles enhance the loss of veins caused by reduced EGFR activity. In addition, Osa is required for the expression of several targets of EGFR signalling, such as Delta, rhomboid and argos. We suggest that one role of Osa and Brm in the wing is to establish a chromatin environment in the regulatory regions of EGFR target genes, making them available for both activators and repressors and facilitating transcription in response to EGFR signalling.
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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 28049, Spain
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20
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Lyulcheva E, Taylor E, Michael M, Vehlow A, Tan S, Fletcher A, Krause M, Bennett D. Drosophila pico and its mammalian ortholog lamellipodin activate serum response factor and promote cell proliferation. Dev Cell 2009; 15:680-90. [PMID: 19000833 PMCID: PMC2691947 DOI: 10.1016/j.devcel.2008.09.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 08/06/2008] [Accepted: 09/30/2008] [Indexed: 12/19/2022]
Abstract
MIG-10/RIAM/lamellipodin (MRL) proteins link activated Ras-GTPases with actin regulatory Ena/VASP proteins to induce local changes in cytoskeletal dynamics and cell motility. MRL proteins alter monomeric (G):filamentous (F) actin ratios, but the impact of these changes had not been fully appreciated. We report here that the Drosophila MRL ortholog, pico, is required for tissue and organismal growth. Reduction in pico levels resulted in reduced cell division rates, growth retardation, increased G:F actin ratios and lethality. Conversely, pico overexpression reduced G:F actin ratios and promoted tissue overgrowth in an epidermal growth factor (EGF) receptor (EGFR)-dependent manner. Consistently, in HeLa cells, lamellipodin was required for EGF-induced proliferation. We show that pico and lamellipodin share the ability to activate serum response factor (SRF), a transcription factor that responds to reduced G:F-actin ratios via its co-factor Mal. Genetics data indicate that mal/SRF levels are important for pico-mediated tissue growth. We propose that MRL proteins link EGFR activation to mitogenic SRF signaling via changes in actin dynamics.
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Affiliation(s)
- Ekaterina Lyulcheva
- Department of Zoology, Oxford University, South Parks Road, Oxford OX1 3PS, UK
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21
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Abstract
Metazoans use a handful of highly conserved signaling pathways to create a signaling backbone that governs development. How these few signals have such a versatile action likely depends upon the larger-scale network they form through integration, as exemplified by cross-talk between the Notch and receptor tyrosine kinase (RTK) pathways. We examined the transcriptional output of Notch-RTK cross-talk during Drosophila development and present in vivo data supporting a role for selected mutually regulated genes in signal integration. Interestingly, Notch-RTK integration did not lead to general antagonism of either pathway, as is commonly believed. Instead, integration had a combinatorial effect on specific cross-regulated targets, which unexpectedly included numerous core components of the RTK and other major signaling pathways (TGF-beta, Hh, Jak/Stat, nuclear receptor and Wnt). We find the majority of Ras-responsive genes are also Notch-responsive, suggesting Notch may function to specify the response to Ras activation.
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22
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Parks AL, Shalaby NA, Muskavitch MAT. Notch and suppressor of Hairless regulate levels but not patterns of Delta expression in Drosophila. Genesis 2008; 46:265-75. [PMID: 18442047 DOI: 10.1002/dvg.20391] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Notch signal transduction pathway is highly conserved and governs many developmental decisions in metazoans. The ligand Delta, and its receptor Notch, are often expressed in complementary patterns during Drosophila postembryonic development. Notch signaling is thought to play a role in generation of these complementary patterns through feedback mechanisms that regulate Delta and Notch expression. We have examined Delta expression during postembryonic development, following global alteration of Notch-dependent or Su(H)-dependent transcriptional regulation. We find that Notch and Su(H) regulate Delta expression in a manner that varies by context. Surprisingly, we find that wild type Delta expression levels are influenced by Su(H)-dependent mechanisms only in regions of high Delta/low Notch expression. In contrast, Delta expression levels in regions of low Delta/high Notch expression appear to be unaffected by Su(H)-mediated regulation. We conclude that Notch pathway feedback regulation is unlikely to contribute to the generation of complementary patterns in the contexts examined.
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Affiliation(s)
- Annette L Parks
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA
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23
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Abstract
The positioning and elaboration of ectodermal veins in the wing of Drosophila melanogaster rely on widely utilized developmental signals, including those mediated by EGF, BMP, Hedgehog, Notch, and Wnt. Analysis of vein patterning mutants, using the molecular and genetic mosaic techniques available in Drosophila, has provided important insights into how a combination of short-range and long-range signaling can pattern a simple epidermal tissue. Moreover, venation has become a powerful system for isolating and analyzing novel components in these signaling pathways. I here review the basic events of vein patterning and give examples of how changes in venation have been used to identify important features of cell signaling pathways.
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Affiliation(s)
- Seth S Blair
- Department of Zoology, University of Wisconsin, Madison, WI 53706, USA.
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24
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Doroquez DB, Rebay I. Signal integration during development: mechanisms of EGFR and Notch pathway function and cross-talk. Crit Rev Biochem Mol Biol 2007; 41:339-85. [PMID: 17092823 DOI: 10.1080/10409230600914344] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metazoan development relies on a highly regulated network of interactions between conserved signal transduction pathways to coordinate all aspects of cell fate specification, differentiation, and growth. In this review, we discuss the intricate interplay between the epidermal growth factor receptor (EGFR; Drosophila EGFR/DER) and the Notch signaling pathways as a paradigm for signal integration during development. First, we describe the current state of understanding of the molecular architecture of the EGFR and Notch signaling pathways that has resulted from synergistic studies in vertebrate, invertebrate, and cultured cell model systems. Then, focusing specifically on the Drosophila eye, we discuss how cooperative, sequential, and antagonistic relationships between these pathways mediate the spatially and temporally regulated processes that generate this sensory organ. The common themes underlying the coordination of the EGFR and Notch pathways appear to be broadly conserved and should, therefore, be directly applicable to elucidating mechanisms of information integration and signaling specificity in vertebrate systems.
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Affiliation(s)
- David B Doroquez
- Department of Biology, Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, USA
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25
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Galindo MI, Bishop SA, Couso JP. Dynamic EGFR-Ras signalling in Drosophila leg development. Dev Dyn 2005; 233:1496-508. [PMID: 15965980 DOI: 10.1002/dvdy.20452] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
In Drosophila, as in many other animals, EGFR-Ras signalling has multiple developmental roles from oogenesis to differentiation. In leg development, in particular, it has been described to be responsible for the establishment of distal leg fates in a graded manner. Here, we investigate the patterns of expression of activators of EGFR-Ras signalling, as well as some of the effectors, in order to better understand the patterning of the distal leg, and to investigate further roles of this signalling pathway. These patterns, together with genetic data obtained by different mutant conditions for EGFR-Ras members and transgene expression, suggest two rounds of signalling in leg development. Early, the EGFR ligand Vein is the main player in distal leg patterning, possibly supported later by another ligand activated by Rhomboid. Later, in a second wave of signalling when all the proximal-distal leg fates have been specified, domains of EGFR/Ras activation appear inside each leg segment to regulate Notch-mediated joint development, and also some organs such as tendons and sensory organs. This second wave relies on a ligand activated by Rhomboid.
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Affiliation(s)
- M I Galindo
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
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26
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Werz C, Lee TV, Lee PL, Lackey M, Bolduc C, Stein DS, Bergmann A. Mis-specified cells die by an active gene-directed process, and inhibition of this death results in cell fate transformation in Drosophila. Development 2005; 132:5343-52. [PMID: 16280349 PMCID: PMC2760325 DOI: 10.1242/dev.02150] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Incorrectly specified or mis-specified cells often undergo cell death or are transformed to adopt a different cell fate during development. The underlying cause for this distinction is largely unknown. In many developmental mutants in Drosophila, large numbers of mis-specified cells die synchronously, providing a convenient model for analysis of this phenomenon. The maternal mutant bicoid is particularly useful model with which to address this issue because its mutant phenotype is a combination of both transformation of tissue (acron to telson) and cell death in the presumptive head and thorax regions. We show that a subset of these mis-specified cells die through an active gene-directed process involving transcriptional upregulation of the cell death inducer hid. Upregulation of hid also occurs in oskar mutants and other segmentation mutants. In hid bicoid double mutants, mis-specified cells in the presumptive head and thorax survive and continue to develop, but they are transformed to adopt a different cell fate. We provide evidence that the terminal torso signaling pathway protects the mis-specified telson tissue in bicoid mutants from hid-induced cell death, whereas mis-specified cells in the head and thorax die, presumably because equivalent survival signals are lacking. These data support a model whereby mis-specification can be tolerated if a survival pathway is provided, resulting in cellular transformation.
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Affiliation(s)
- Christian Werz
- The University of Texas M.D. Anderson Cancer Center, Department of Biochemistry and Molecular Biology, 1515 Holcombe Boulevard, Unit 1000, Houston, TX 77030, USA
| | - Tom V. Lee
- The University of Texas M.D. Anderson Cancer Center, Department of Biochemistry and Molecular Biology, 1515 Holcombe Boulevard, Unit 1000, Houston, TX 77030, USA
- The Genes and Development Graduate Program (http://www.mdanderson.org/genedev)
| | - Peter L. Lee
- The University of Texas M.D. Anderson Cancer Center, Department of Biochemistry and Molecular Biology, 1515 Holcombe Boulevard, Unit 1000, Houston, TX 77030, USA
| | - Melinda Lackey
- The University of Texas M.D. Anderson Cancer Center, Department of Biochemistry and Molecular Biology, 1515 Holcombe Boulevard, Unit 1000, Houston, TX 77030, USA
| | - Clare Bolduc
- The University of Texas M.D. Anderson Cancer Center, Department of Biochemistry and Molecular Biology, 1515 Holcombe Boulevard, Unit 1000, Houston, TX 77030, USA
| | - David S. Stein
- The University of Texas at Austin, Patterson labs 532, Section of Molecular Cell and Developmental Biology, Institute for Cellular and Molecular Biology, 2401 W24th and Speedway, Austin, TX 78712, USA
| | - Andreas Bergmann
- The University of Texas M.D. Anderson Cancer Center, Department of Biochemistry and Molecular Biology, 1515 Holcombe Boulevard, Unit 1000, Houston, TX 77030, USA
- The Genes and Development Graduate Program (http://www.mdanderson.org/genedev)
- Author for correspondence (e-mail: )
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27
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Palsson A, Dodgson J, Dworkin I, Gibson G. Tests for the replication of an association between Egfr and natural variation in Drosophila melanogaster wing morphology. BMC Genet 2005; 6:44. [PMID: 16102176 PMCID: PMC1208880 DOI: 10.1186/1471-2156-6-44] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Accepted: 08/15/2005] [Indexed: 11/25/2022] Open
Abstract
Background Quantitative differences between individuals stem from a combination of genetic and environmental factors, with the heritable variation being shaped by evolutionary forces. Drosophila wing shape has emerged as an attractive system for genetic dissection of multi-dimensional traits. We utilize several experimental genetic methods to validation of the contribution of several polymorphisms in the Epidermal growth factor receptor (Egfr) gene to wing shape and size, that were previously mapped in populations of Drosophila melanogaster from North Carolina (NC) and California (CA). This re-evaluation utilized different genetic testcrosses to generate heterozygous individuals with a variety of genetic backgrounds as well as sampling of new alleles from Kenyan stocks. Results Only one variant, in the Egfr promoter, had replicable effects in all new experiments. However, expanded genotyping of the initial sample of inbred lines rendered the association non-significant in the CA population, while it persisted in the NC sample, suggesting population specific modification of the quantitative trait nucleotide QTN effect. Conclusion Dissection of quantitative trait variation to the nucleotide level can identify sites with replicable effects as small as one percent of the segregating genetic variation. However, the testcross approach to validate QTNs is both labor intensive and time-consuming, and is probably less useful than resampling of large independent sets of outbred individuals.
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Affiliation(s)
- Arnar Palsson
- Department of Genetics' North Carolina State University, Raleigh, NC 27695, USA
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
| | - James Dodgson
- Department of Genetics' North Carolina State University, Raleigh, NC 27695, USA
- The Department of Biochemistry, University of Sussex, Brighton, BN1 9QG, UK
| | - Ian Dworkin
- Department of Genetics' North Carolina State University, Raleigh, NC 27695, USA
| | - Greg Gibson
- Department of Genetics' North Carolina State University, Raleigh, NC 27695, USA
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28
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Garoia F, Grifoni D, Trotta V, Guerra D, Pezzoli MC, Cavicchi S. The tumor suppressor gene fat modulates the EGFR-mediated proliferation control in the imaginal tissues of Drosophila melanogaster. Mech Dev 2005; 122:175-87. [PMID: 15652705 DOI: 10.1016/j.mod.2004.10.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Accepted: 10/11/2004] [Indexed: 11/24/2022]
Abstract
Molecules involved in cell adhesion can regulate both early signal transduction events, triggered by soluble factors, and downstream events involved in cell cycle progression. Correct integration of these signals allows appropriate cellular growth, differentiation and ultimately tissue morphogenesis, but incorrect interpretation contributes to pathologies such as tumor growth. The Fat cadherin is a tumor suppressor protein required in Drosophila for epithelial morphogenesis, proliferation control and epithelial planar polarization, and its loss results in a hyperplastic growth of imaginal tissues. While several molecular events have been characterized through which fat participates in the establishment of the epithelial planar polarity, little is known about mechanisms underlying fat-mediated control of cell proliferation. Here we provide evidence that fat specifically cooperates with the epidermal growth factor receptor (EGFR) pathway in controlling cell proliferation in developing imaginal epithelia. Hyperplastic larval and adult fat structures indeed undergo an amazing, synergistic enlargement following to EGFR oversignalling. We further show that such a strong functional interaction occurs downstream of MAPK activation through the transcriptional regulation of genes involved in the EGFR nuclear signalling. Considering that fat mutation shows di per se a hyperplastic phenotype, we suggest a model in which fat acts in parallel to EGFR pathway in transducing different cell communication signals; furthermore its function is requested downstream of MAPK for a correct rendering of the growth signals converging to the epidermal growth factor receptor.
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Affiliation(s)
- Flavio Garoia
- Alma Mater Studiorum, Università di Bologna, CIRSA-GenMAP Lab, via S.Alberto 163, 48100 Ravenna, Italy.
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29
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Shimmi O, Ralston A, Blair SS, O'Connor MB. The crossveinless gene encodes a new member of the Twisted gastrulation family of BMP-binding proteins which, with Short gastrulation, promotes BMP signaling in the crossveins of the Drosophila wing. Dev Biol 2005; 282:70-83. [PMID: 15936330 DOI: 10.1016/j.ydbio.2005.02.029] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 02/26/2005] [Accepted: 02/28/2005] [Indexed: 10/25/2022]
Abstract
In the early Drosophila embryo, Bone morphogenetic protein (BMP) activity is positively and negatively regulated by the BMP-binding proteins Short gastrulation (Sog) and Twisted gastrulation (Tsg). We show here that a similar mechanism operates during crossvein formation, utilizing Sog and a new member of the tsg gene family, encoded by the crossveinless (cv) locus. The initial specification of crossvein fate in the Drosophila wing requires signaling mediated by Dpp and Gbb, two members of the BMP family. cv is required for the promotion of BMP signaling in the crossveins. Large sog clones disrupt posterior crossvein formation, suggesting that Sog and Cv act together in this context. We demonstrate that sog and cv can have both positive and negative effects on BMP signaling in the wing. Moreover, Cv is functionally equivalent to Tsg, since Tsg and Cv can substitute for each other's activity. We also confirm that Tsg and Cv have similar biochemical activities: Sog/Cv complex binds a Dpp/Gbb heterodimer with high affinity. Taken together, these studies suggest that Sog and Cv promote BMP signaling by transporting a BMP heterodimer from the longitudinal veins into the crossvein regions.
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Affiliation(s)
- Osamu Shimmi
- Department of Genetics Cell Biology and Development, Howard Hughes Medical Institute, University of Minnesota, 6-160 Jackson Hall, Minneapolis, MN 55455, USA
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30
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Ralston A, Blair SS. Long-range Dpp signaling is regulated to restrict BMP signaling to a crossvein competent zone. Dev Biol 2005; 280:187-200. [PMID: 15766758 DOI: 10.1016/j.ydbio.2005.01.018] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 01/08/2005] [Accepted: 01/11/2005] [Indexed: 11/19/2022]
Abstract
The sensitivity of the crossveins of the Drosophila wing to reductions in BMP signaling provides a valuable system for characterizing members of this signaling pathway. We demonstrate here two reasons for that sensitivity. First, the initial stage of posterior crossvein development depends on BMP signaling but is independent of EGF signaling. This is the opposite of the longitudinal veins, which rely of EGF signaling for their initial specification. Second, BMP signaling in the posterior crossvein depends on Decapentaplegic (Dpp) at a stage when it is being produced in the longitudinal veins. Thus, the posterior crossvein will be especially vulnerable to reductions in the levels or range of Dpp signaling. We investigated the roles of the BMP receptor Thickveins (Tkv) and the BMP inhibitor Short gastrulation (Sog) in allowing this long-range signaling. Expression of both is downregulated in the developing posterior crossvein. The Tkv downregulation depends on BMP signaling and may provide a positive feedback by allowing the spread of Dpp. The Sog downregulation is independent of BMP signaling; Sog misexpression experiments indicate that this prepattern is essential for posterior crossvein development. However, this requirement can be overridden by co-misexpression of the BMP agonist Cv-2, indicating the presence of as yet unknown cues; we discuss possible candidates.
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Affiliation(s)
- Amy Ralston
- Department of Zoology, 250 N. Mills Street, University of Wisconsin, Madison, WI 53706, USA
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31
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Yoshida H, Kwon E, Hirose F, Otsuki K, Yamada M, Yamaguchi M. DREF is required for EGFR signalling during Drosophila wing vein development. Genes Cells 2005; 9:935-44. [PMID: 15461664 DOI: 10.1111/j.1365-2443.2004.00775.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The DNA replication-related element binding factor (DREF) has been suggested as being involved in regulation of DNA replication- and proliferation-related genes in Drosophila. Recently, by searching the Drosophila genome database, we also found DRE-like sequences in the 5'-flanking regions of many genes with other functions. In addition, immunostaining of polytene chromosomes with an anti-DREF monoclonal antibody revealed that DREF can bind to a hundred regions of polytene chromosomes, suggesting regulation of multiple genes and multiple roles in vivo. When we over-expressed DREF protein or inverted repeat RNA of the DREF gene in wing imaginal discs using the GAL4-UAS targeted expression system in Drosophila, the results were veins of increased width and a loss of veins, respectively. With DREF over-expression, Rolled, a Drosophila MAPK homologue, was ectopically activated. Furthermore, half reduction of the D-raf gene dose suppressed this DREF-induced vein of increased width phenotype. In addition, when DREF transcripts were reduced by introducing double-stranded RNA of the DREF gene into S2 cells, the D-raf gene promoter activity was diminished to 4%. These data indicate that DREF is involved in regulation of vein formation through the activation of EGFR signalling in the Drosophila wing imaginal discs.
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Affiliation(s)
- Hideki Yoshida
- Venture Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto, Japan
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32
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Gorfinkiel N, Sierra J, Callejo A, Ibañez C, Guerrero I. The Drosophila ortholog of the human Wnt inhibitor factor Shifted controls the diffusion of lipid-modified Hedgehog. Dev Cell 2005; 8:241-53. [PMID: 15691765 DOI: 10.1016/j.devcel.2004.12.018] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 12/19/2004] [Accepted: 12/29/2004] [Indexed: 10/25/2022]
Abstract
The Hedgehog (Hh) family of morphogenetic proteins has important instructional roles in metazoan development and human diseases. Lipid modified Hh is able to migrate to and program cells far away from its site of production despite being associated with membranes. To investigate the Hh spreading mechanism, we characterized Shifted (Shf) as a component in the Drosophila Hh pathway. We show that Shf is the ortholog of the human Wnt inhibitory factor (WIF), a secreted antagonist of the Wingless pathway. In contrast, Shf is required for Hh stability and for lipid-modified Hh diffusion. Shf colocalizes with Hh in the extracellular matrix and interacts with the heparan sulfate proteoglycans (HSPG), leading us to suggest that Shf could provide HSPG specificity for Hh. We also show that human WIF inhibits Wg signaling in Drosophila without affecting the Hh pathway, indicating that different WIF family members might have divergent functions in each pathway.
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Affiliation(s)
- Nicole Gorfinkiel
- Centro de Biología Molecular, Severo Ochoa, C.S.I.C, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
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33
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Alvarado D, Rice AH, Duffy JB. Bipartite inhibition of Drosophila epidermal growth factor receptor by the extracellular and transmembrane domains of Kekkon1. Genetics 2005; 167:187-202. [PMID: 15166146 PMCID: PMC1470870 DOI: 10.1534/genetics.167.1.187] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Drosophila, signaling by the epidermal growth factor receptor (EGFR) is required for a diverse array of developmental decisions. Essential to these decisions is the precise regulation of the receptor's activity by both stimulatory and inhibitory molecules. To better understand the regulation of EGFR activity we investigated inhibition of EGFR by the transmembrane protein Kekkon1 (Kek1). Kek1 encodes a molecule containing leucine-rich repeats (LRR) and an immunoglobulin (Ig) domain and is the founding member of the Drosophila Kekkon family. Here we demonstrate with a series of Kek1-Kek2 chimeras that while the LRRs suffice for EGFR binding, inhibition in vivo requires the Kek1 juxta/transmembrane region. We demonstrate directly, and using a series of Kek1-EGFR chimeras, that Kek1 is not a phosphorylation substrate for the receptor in vivo. In addition, we show that EGFR inhibition is unique to Kek1 among Kek family members and that this function is not ligand or tissue specific. Finally, we have identified a unique class of EGFR alleles that specifically disrupt Kek1 binding and inhibition, but preserve receptor activation. Interestingly, these alleles map to domain V of the Drosophila EGFR, a region absent from the vertebrate receptors. Together, our results support a model in which the LRRs of Kek1 in conjunction with its juxta/transmembrane region direct association and inhibition of the Drosophila EGFR through interactions with receptor domain V.
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Affiliation(s)
- Diego Alvarado
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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34
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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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35
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MacDougall LK, Gagou ME, Leevers SJ, Hafen E, Waterfield MD. Targeted expression of the class II phosphoinositide 3-kinase in Drosophila melanogaster reveals lipid kinase-dependent effects on patterning and interactions with receptor signaling pathways. Mol Cell Biol 2004; 24:796-808. [PMID: 14701751 PMCID: PMC343800 DOI: 10.1128/mcb.24.2.796-808.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphoinositide 3-kinases (PI3Ks) can be divided into three distinct classes (I, II, and III) on the basis of their domain structures and the lipid signals that they generate. Functions have been assigned to the class I and class III enzymes but have not been established for the class II PI3Ks. We have obtained the first evidence for a biological function for a class II PI3K by expressing this enzyme during Drosophila melanogaster development and by using deficiencies that remove the endogenous gene. Wild-type and catalytically inactive PI3K_68D transgenes have opposite effects on the number of sensory bristles and on wing venation phenotypes induced by modified epidermal growth factor (EGF) receptor signaling. These results indicate that the endogenous PI3K_68D may act antagonistically to the EGF receptor-stimulated Ras-mitogen-activated protein kinase pathway and downstream of, or parallel to, the Notch receptor. A class II polyproline motif in PI3K_68D can bind the Drk adaptor protein in vitro, primarily via the N-terminal SH3 domain of Drk. Drk may thus be important for the localization of PI3K_68D, allowing it to modify signaling pathways downstream of cell surface receptors. The phenotypes obtained are markedly distinct from those generated by expression of the Drosophila class I PI3K, which affects growth but not pattern formation.
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Affiliation(s)
- Lindsay K MacDougall
- Biomolecular Sciences, University of Manchester Institute of Science and Technology, PO Box 88, Manchester M60 1QD, UK.
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36
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Abstract
The veins are cuticular structures that differentiate in precise patterns in insect wings. The genetic and molecular basis of vein pattern formation in Drosophila melanogaster is beginning to be unravelled with the identification and characterisation of the gene products that position the veins and direct their differentiation. Genes affecting the veins fall into two groups: transcriptional regulators that specify individual veins, and members of signalling pathways involved in patterning and differentiation of the veins. The elaboration of the vein pattern is progressive in time and requires the coordinated activities of these signalling pathways and the transcription factors regulated by them. Although the network of genetic interactions that determine vein cell fate is well understood, very little is known about the cellular biology underlying the acquisition of vein histotype.
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Affiliation(s)
- Jose F De Celis
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain.
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37
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Chandra S, Ahmed A, Vaessin H. The Drosophila IgC2 domain protein Friend-of-Echinoid, a paralogue of Echinoid, limits the number of sensory organ precursors in the wing disc and interacts with the Notch signaling pathway. Dev Biol 2003; 256:302-16. [PMID: 12679104 DOI: 10.1016/s0012-1606(03)00038-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Notch signaling pathway is critical in cell fate specification throughout development. In the developing wing disc, single sensory organ precursors (SOPs) are selected from proneural clusters via a process of lateral inhibition mediated by the Notch signaling pathway. The epidermal growth factor receptor (EGFR) pathway has also been implicated in SOP formation. Here, we describe the Drosophila melanogaster gene friend of echinoid (fred), a paralogue of echinoid (ed), a gene recently identified as a negative regulator of the EGFR pathway. fred function was examined in transgenic flies by using inducible RNA interference (RNAi). Suppression of fred in developing wing discs results in specification of ectopic SOPs, additional microchaeta, and cell death. In eye-antennal discs, fred suppression causes a rough eye phenotype. These phenotypes are suppressed by overexpression of Notch, Suppressor of Hairless [Su(H)], and Enhancer of split m7. In contrast, overexpression of Hairless, a negative regulator of the Notch pathway, and decreased Su(H) activity enhance these phenotypes. Thus, fred acts in close concert with the Notch signaling pathway. Dosage-sensitive genetic interaction also suggests a close relationship between fred and ed.
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Affiliation(s)
- Shweta Chandra
- Molecular, Cellular and Developmental Biology Program, The Ohio State University, Columbus, OH 43210, USA
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38
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Baker SE, Lorenzen JA, Miller SW, Bunch TA, Jannuzi AL, Ginsberg MH, Perkins LA, Brower DL. Genetic Interaction Between Integrins and moleskin, a Gene Encoding a Drosophila Homolog of Importin-7. Genetics 2002; 162:285-96. [PMID: 12242240 PMCID: PMC1462259 DOI: 10.1093/genetics/162.1.285] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
The Drosophila PS1 and PS2 integrins are required to maintain the connection between the dorsal and ventral wing epithelia. If αPS subunits are inappropriately expressed during early pupariation, the epithelia separate, causing a wing blister. Two lines of evidence indicate that this apparent loss-of-function phenotype is not a dominant negative effect, but is due to inappropriate expression of functional integrins: wing blisters are not generated efficiently by misexpression of loss-of-function αPS2 subunits with mutations that inhibit ligand binding, and gain-of-function, hyperactivated mutant αPS2 proteins cause blistering at expression levels well below those required by wild-type proteins. A genetic screen for dominant suppressors of wing blisters generated null alleles of a gene named moleskin, which encodes the protein DIM-7. DIM-7, a Drosophila homolog of vertebrate importin-7, has recently been shown to bind the SHP-2 tyrosine phosphatase homolog Corkscrew and to be important in the nuclear translocation of activated D-ERK. Consistent with this latter finding, homozygous mutant clones of moleskin fail to grow in the wing. Genetic tests suggest that the moleskin suppression of wing blisters is not directly related to inhibition of D-ERK nuclear import. These data are discussed with respect to the possible regulation of integrin function by cytoplasmic ERK.
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Affiliation(s)
- Scott E Baker
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA
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39
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Abstract
During development of multicellular organisms, cells are often eliminated by apoptosis if they fail to receive appropriate signals from their surroundings. Here, we report on short-range cell interactions that support cell survival in the Drosophila wing imaginal disc. We present evidence showing that cells incorrectly specified for their position undergo apoptosis because they fail to express specific proteins that are found on surrounding cells, including the LRR transmembrane proteins Capricious and Tartan. Interestingly, only the extracellular domains of Capricious and Tartan are required, suggesting that a bidirectional process of cell communication is involved in triggering apoptosis. We also present evidence showing that activation of the Notch signal transduction pathway is involved in triggering apoptosis of cells misspecified for their dorsal-ventral position.
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Affiliation(s)
- Marco Milán
- European Molecular Biology Laboratory, Meyerhofstr 1, 69117 Heidelberg, Germany
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40
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Guichard A, Srinivasan S, Zimm G, Bier E. A screen for dominant mutations applied to components in the Drosophila EGF-R pathway. Proc Natl Acad Sci U S A 2002; 99:3752-7. [PMID: 11904431 PMCID: PMC122596 DOI: 10.1073/pnas.052028699] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Drosophila epidermal growth factor receptor (EGF-R) controls many critical cell fate choices throughout development. Several proteins collaborate to promote localized EGF-R activation, such as Star and Rhomboid (Rho), which act sequentially to ensure the maturation and processing of inactive membrane-bound EGF ligands. To gain insights into the mechanisms underlying Rho and Star function, we developed a mutagenesis scheme to isolate novel overexpression activity (NOVA) alleles. In the case of rho, we isolated a dominant neomorphic allele, which interferes with Notch signaling, as well as a dominant-negative allele, which produces RNA interference-like flip-back transcripts that reduce endogenous rho expression. We also obtained dominant-negative and neomorphic Star mutations, which have phenotypes similar to those of rho NOVA alleles, as well as dominant-negative Egf-r alleles. The isolation of dominant alleles in several different genes suggests that NOVA mutagenesis should be widely applicable and emerge as an effective tool for generating dominant mutations in genes of unknown function.
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Affiliation(s)
- Annabel Guichard
- Section of Cell and Developmental Biology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA
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41
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Morey M, Serras F, Baguñà J, Hafen E, Corominas M. Modulation of the Ras/MAPK signalling pathway by the redox function of selenoproteins in Drosophila melanogaster. Dev Biol 2001; 238:145-56. [PMID: 11784000 DOI: 10.1006/dbio.2001.0389] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Modulation of reactive oxygen species (ROS) plays a key role in signal transduction pathways. Selenoproteins act controlling the redox balance of the cell. We have studied how the alteration of the redox balance caused by patufet (selD(ptuf)), a null mutation in the Drosophila melanogaster selenophosphate synthetase 1 (sps1) gene, which codes for the SelD enzyme of the selenoprotein biosynthesis, affects the Ras/MAPK signalling pathway. The selD(ptuf) mutation dominantly suppresses the phenotypes in the eye and the wing caused by hyperactivation of the Ras/MAPK cassette and the activated forms of the Drosophila EGF receptor (DER) and Sevenless (Sev) receptor tyrosine kinases (RTKs), which signal in the eye and wing, respectively. No dominant interaction is observed with sensitized conditions in the Wnt, Notch, Insulin-Pi3K, and DPP signalling pathways. Our current hypothesis is that selenoproteins selectively modulate the Ras/MAPK signalling pathway through their antioxidant function. This is further supported by the fact that a selenoprotein-independent increase in ROS caused by the catalase amorphic Cat(n1) allele also reduces Ras/MAPK signalling. Here, we present the first evidence for the role of intracellular redox environment in signalling pathways in Drosophila as a whole organism.
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Affiliation(s)
- M Morey
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, Barcelona, 08028, Spain
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42
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Culí J, Martín-Blanco E, Modolell J. The EGF receptor and N signalling pathways act antagonistically in Drosophila mesothorax bristle patterning. Development 2001; 128:299-308. [PMID: 11124124 DOI: 10.1242/dev.128.2.299] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An early step in the development of the large mesothoracic bristles (macrochaetae) of Drosophila is the expression of the proneural genes of the achaete-scute complex (AS-C) in small groups of cells (proneural clusters) of the wing imaginal disc. This is followed by a much increased accumulation of AS-C proneural proteins in the cell that will give rise to the sensory organ, the SMC (sensory organ mother cell). This accumulation is driven by cis-regulatory sequences, SMC-specific enhancers, that permit self-stimulation of the achaete, scute and asense proneural genes. Negative interactions among the cells of the cluster, triggered by the proneural proteins and mediated by the Notch receptor (lateral inhibition), block this accumulation in most cluster cells, thereby limiting the number of SMCs. Here we show that the proneural proteins trigger, in addition, positive interactions among cells of the cluster that are mediated by the Epidermal growth factor receptor (EGFR) and the Ras/Raf pathway. These interactions, which we denominate ‘lateral co-operation’, are essential for macrochaetae SMC emergence. Activation of the EGFR/Ras pathway appears to promote proneural gene self-stimulation mediated by the SMC-specific enhancers. Excess EGFR signalling can overrule lateral inhibition and allow adjacent cells to become SMCs and sensory organs. Thus, the EGFR and Notch pathways act antagonistically in notum macrochaetae determination.
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Affiliation(s)
- J Culí
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Cantoblanco, Madrid, Spain
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43
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Serras F, Morey M, Alsina B, Baguñà J, Corominas M. The Drosophila selenophosphate synthetase (selD) gene is required for development and cell proliferation. Biofactors 2001; 14:143-9. [PMID: 11568451 DOI: 10.1002/biof.5520140119] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
To study the function of selenoproteins in development and growth we have used a lethal mutation (selD(ptuf)) of the Drosophila homologous selenophosphate synthetase (selD) gene. This enzyme is involved in the selenoprotein biosynthesis. The selD(ptuf) loss-of-function mutation causes aberrant cell proliferation and differentiation patterns in the brain and imaginal discs, as deduced from genetic mosaics, patterns of gene expression and analysis of cell cycle markers. In addition to that, selenium metabolism is also necessary for the ras/MAPKinase signal tansduction pathway. Therefore, the use of Drosophila imaginal discs and brain and in particular the selD(ptuf) mutation, provide an excellent model to investigate the role of selenoproteins in the regulation of cell proliferation, growth and differentiation.
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Affiliation(s)
- F Serras
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
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44
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Sotillos S, Campuzano S. DRacGAP, a novel Drosophila gene, inhibits EGFR/Ras signalling in the developing imaginal wing disc. Development 2000; 127:5427-38. [PMID: 11076763 DOI: 10.1242/dev.127.24.5427] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We have identified a novel Drosophila gene, DRacGAP, which behaves as a negative regulator of Ρ-family GTPases DRac1 and DCdc42. Reduced function of DRacGAP or increased expression of DRac1 in the wing imaginal disc cause similar effects on vein and sensory organ development and cell proliferation. These effects result from enhanced activity of the EGFR/Ras signalling pathway. We find that in the wing disc, DRac1 enhances EGFR/Ras-dependent activation of MAP Kinase in the prospective veins. Interestingly, DRacGAP expression is negatively regulated by the EGFR/Ras pathway in these regions. During vein formation, local DRacGAP repression would ensure maximal activity of Rac and, in turn, of Ras pathways in vein territories. Additionally, maximal expression of DRacGAP at the vein/intervein boundaries would help to refine the width of the veins. Hence, control of DRacGAP expression by the EGFR/Ras pathway is a previously undescribed feedback mechanism modulating the intensity and/or duration of its signalling during Drosophila development.
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Affiliation(s)
- S Sotillos
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM Cantoblanco, Spain
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45
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Brentrup D, Lerch H, Jäckle H, Noll M. Regulation of Drosophila wing vein patterning: net encodes a bHLH protein repressing rhomboid and is repressed by rhomboid-dependent Egfr signalling. Development 2000; 127:4729-41. [PMID: 11023875 DOI: 10.1242/dev.127.21.4729] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The stereotyped pattern of veins in the Drosophila wing is generated in response to local EGF signalling. Mutations in the rhomboid (rho) gene, which encodes a sevenpass membrane protein required to enhance signalling transmitted by the EGF receptor (Egfr), inhibit vein development and disrupt the vein pattern. By contrast, net mutations produce ectopic veins in intervein regions. We have cloned the net gene and show that it encodes a basic HLH protein that probably acts as a transcriptional repressor. net and rho are expressed in mutually exclusive patterns during the development of the wing imaginal disc. Lack of net activity causes rho expression to expand, and vice versa. Furthermore, ectopic expression of net or rho results in their mutual repression and thus suppresses vein formation or generates tube-like wings composed of vein-like tissue. Egfr signalling and net exert mutually antagonising activities during the specification of vein versus intervein fate. While Egfr signalling represses net transcription, net exhibits a two-tiered control by repressing rho transcription and interfering with Egfr signalling downstream of Rho. Our results further suggest that net is required to maintain intervein development by restricting Egfr signalling, which promotes vein development, to the Net-free vein regions of the wing disc.
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Affiliation(s)
- D Brentrup
- Institut für Molekularbiologie, Universität Zürich, CH-8057 Zürich, Switzerland
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46
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González-Gaitán M, Jäckle H. Tip cell-derived RTK signaling initiates cell movements in the Drosophila stomatogastric nervous system anlage. EMBO Rep 2000; 1:366-71. [PMID: 11269504 PMCID: PMC1083741 DOI: 10.1093/embo-reports/kvd064] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The stomatogastric nervous system (SNS) of Drosophila is a simply organized neural circuitry that innervates the anterior enteric system. Unlike the central and the peripheral nervous systems, the SNS derives from a compact epithelial anlage in which three invagination centers, each giving rise to an invagination fold headed by a tip cell, are generated. Tip cell selection involves lateral inhibition, a process in which Wingless (Wg) activity adjusts the range of Notch signaling. Here we show that RTK signaling mediated by the Drosophila homolog of the epidermal growth factor receptor, DER, plays a key role in two consecutive steps during early SNS development. Like Wg, DER signaling participates in adjusting the range of Notch-dependent lateral inhibition during tip cell selection. Subsequently, tip cells secrete the DER ligand Spitz and trigger local RTK signaling, which initiates morphogenetic movements resulting in the tip cell-directed invaginations within the SNS anlage.
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Affiliation(s)
- M González-Gaitán
- MPI für biophysikalische Chemie, Abt. Molekulare Entwicklungsbiologie, Göttingen, Germany.
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47
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Abstract
It has been proposed that wing veins in Drosophila form at boundaries between discrete sectors of cells that subdivide the anterior-posterior axis of the developing wing primordium. Recently, analysis of events underlying initiation of vein formation suggests that there is a general developmental mechanism for drawing lines between adjacent domains of cells, which is referred to as 'for-export-only-signaling'. In this model, cells in one domain produce a short range signal to which they cannot respond. As a consequence of this constraint, cells lying in a narrow line immediately outside the signal-producing domain are the only cells that can respond to the signal by activating expression of vein-promoting genes.
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Affiliation(s)
- E Bier
- Division of Biology, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla 92093-0349, USA.
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48
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Oldham S, Böhni R, Stocker H, Brogiolo W, Hafen E. Genetic control of size in Drosophila. Philos Trans R Soc Lond B Biol Sci 2000; 355:945-52. [PMID: 11128988 PMCID: PMC1692799 DOI: 10.1098/rstb.2000.0630] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
During the past ten years, significant progress has been made in understanding the basic mechanisms of the development of multicellular organisms. Genetic analysis of the development of Caenorhabditis elegans and Drosophila has unearthed a fruitful number of genes involved in establishing the basic body plan, patterning of limbs, specification of cell fate and regulation of programmed cell death. The genes involved in these developmental processes have been conserved throughout evolution and homologous genes are involved in the patterning of insect and human limbs. Despite these important discoveries, we have learned astonishingly little about one of the most obvious distinctions between animals: their difference in body size. The mass of the smallest mammal, the bumble-bee bat, is 2 g while that of the largest mammal, the blue whale, is 150 t or 150 million grams. Remarkably, even though they are in the same class, body size can vary up to 75-million-fold. Furthermore, this body growth can be finite in the case of most vertebrates or it can occur continuously throughout life, as for trees, molluscs and large crustaceans. Currently, we know comparatively little about the genetic control of body size. In this article we will review recent evidence from vertebrates and particularly from Drosophila that implicates insulin/insulin-like growth factor-I and other growth pathways in the control of cell, organ and body size.
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Affiliation(s)
- S Oldham
- Zoological Institute, University of Zurich, Switzerland
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49
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Robertson H, Hime GR, Lada H, Bowtell DD. A Drosophila analogue of v-Cbl is a dominant-negative oncoprotein in vivo. Oncogene 2000; 19:3299-308. [PMID: 10918586 DOI: 10.1038/sj.onc.1203624] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cells rely on the ability to receive and interpret external signals to regulate growth, differentiation, and death. Positive transduction of these signals to the cytoplasm and nucleus has been extensively characterized, and genetic studies in Drosophila have made major contributions to the understanding of these pathways. Less well understood, but equally important, are the mechanisms underlying signal down-regulation. Here we report biochemical and genetic characterization of the Drosophila homologue of c-Cbl, a negative regulator of signal transduction with ubiquitin-protein ligase activity. A new isoform of D-Cbl, D-CblL, has been identified that contains SH3-binding and UBA domains previously reported to be absent. Genetic analysis demonstrates that Dv-cbl, analogous to the mammalian v-cbl oncogene, is a dominant negative mutation able to enhance signalling from the Drosophila Egfr and cooperate with activating mutations in the sevenless pathway to produce melanotic tumours. In addition, our data show genetic and biochemical links between D-Cbl and proteins involved in endocytosis and ubiquitination, suggesting that v-Cbl may exert its oncogenic effect by enhancing receptor signalling as a consequence of suppressing receptor endocytosis.
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Affiliation(s)
- H Robertson
- Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, Melbourne, VIC, Australia
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50
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Garoia F, Guerra D, Pezzoli MC, López-Varea A, Cavicchi S, García-Bellido A. Cell behaviour of Drosophila fat cadherin mutations in wing development. Mech Dev 2000; 94:95-109. [PMID: 10842062 DOI: 10.1016/s0925-4773(00)00306-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have studied several cell behaviour parameters of mutant alleles of fat (ft) in Drosophila imaginal wing disc development. Mutant imaginal discs continue growing in larvae delayed in pupariation and can reach sizes of several times those of wild-type. Their growth is, however, basically allometric. Homozygous ft cells grow faster than their twin cells in clones and generate larger territories, albeit delimited by normal clonal restrictions. Moreover, ft cells in clones tend to grow towards wing proximal regions. These behaviours can be related with failures in cell adhesiveness and cell recognition. Double mutant combinations with alleles of other genes, e.g. of the Epidermal growth factor receptor (DER) pathway, modify ft clonal phenotypes, indicating that adhesiveness is modulated by intercellular signalling. Mutant ft cells show, in addition, smaller cell sizes during proliferation and abnormal cuticular differentiation, which reflect cell membrane and cytoskeleton anomalies, which are not modulated by the DER pathway.
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Affiliation(s)
- F Garoia
- Dipartimento di Biologia Evoluzionistica Sperimentale, Universitá di Bologna, Italy
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