1
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Moore SL, Adamini FC, Coopes ES, Godoy D, Northington SJ, Stewart JM, Tillett RL, Bieser KL, Kagey JD. Patched and Costal-2 mutations lead to differences in tissue overgrowth autonomy. Fly (Austin) 2022; 16:176-189. [PMID: 35468034 PMCID: PMC9045829 DOI: 10.1080/19336934.2022.2062991] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 03/31/2022] [Accepted: 04/02/2022] [Indexed: 02/03/2023] Open
Abstract
Genetic screens are used in Drosophila melanogaster to identify genes key in the regulation of organismal development and growth. These screens have defined signalling pathways necessary for tissue and organismal development, which are evolutionarily conserved across species, including Drosophila. Here, we have used an FLP/FRT mosaic system to screen for conditional regulators of cell growth and cell division in the Drosophila eye. The conditional nature of this screen utilizes a block in the apoptotic pathway to prohibit the mosaic mutant cells from dying via apoptosis. From this screen, we identified two different mutants that mapped to the Hedgehog signalling pathway. Previously, we described a novel Ptc mutation and here we add to the understanding of disrupting the Hh pathway with a novel allele of Cos2. Both of these Hh components are negative regulators of the pathway, yet they depict mutant differences in the type of overgrowth created. Ptc mutations lead to overgrowth consisting of almost entirely wild-type tissue (non-autonomous overgrowth), while the Cos2 mutation results in tissue that is overgrown in both the mutant and wild-type clones (both autonomous and non-autonomous). These differences in tissue overgrowth are consistent in the Drosophila eye and wing. The observed difference is correlated with different deregulation patterns of pMad, the downstream effector of DPP signalling. This finding provides insight into pathway-specific differences that help to better understand intricacies of developmental processes and human diseases that result from deregulated Hedgehog signalling, such as basal cell carcinoma.
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Affiliation(s)
- Shannon L. Moore
- Biology Department, University of Detroit Mercy, Detroit, Michigan, USA
| | - Frank C. Adamini
- Biology Department, University of Detroit Mercy, Detroit, Michigan, USA
| | - Erik S. Coopes
- Biology Department, University of Detroit Mercy, Detroit, Michigan, USA
| | - Dustin Godoy
- Department of Physical and Life Sciences, Nevada State College, Henderson, Nevada, USA
| | - Shyra J. Northington
- Biology Department, University of Detroit Mercy, Detroit, Michigan, USA
- ReBUILDetroit, University of Detroit Mercy, Detroit, Michigan, USA
| | - Jordan M. Stewart
- Biology Department, University of Detroit Mercy, Detroit, Michigan, USA
| | - Richard L Tillett
- Nevada Institute of Personalized Medicine, University of Nevada, Las Vegas, Nevada, USA
| | - Kayla L. Bieser
- Department of Physical and Life Sciences, Nevada State College, Henderson, Nevada, USA
| | - Jacob D. Kagey
- Biology Department, University of Detroit Mercy, Detroit, Michigan, USA
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2
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Abstract
Drosophila melanogaster remains a foremost genetic model to study basic cell biological processes in the context of multi-cellular development. In such context, the behavior of one cell can influence another. Non-autonomous signaling among cells occurs throughout metazoan development and disease, and is too vast to be covered by a single review. I will focus here on non-autonomous signaling events that occur in response to cell death in the larval epithelia and affect the life-death decision of surviving cells. I will summarize the use of Drosophila to study cell death-induced proliferation, apoptosis-induced apoptosis, and apoptosis-induced survival signaling. Key insights from Drosophila will be discussed in the context of analogous processes in mammalian development and cancer biology.
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Affiliation(s)
- Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309-0347, USA
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3
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Estella C, Baonza A. Cell proliferation control by Notch signalling during imaginal discs development in Drosophila. AIMS GENETICS 2021. [DOI: 10.3934/genet.2015.1.70] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
AbstractThe Notch signalling pathway is evolutionary conserved and participates in numerous developmental processes, including the control of cell proliferation. However, Notch signalling can promote or restrain cell division depending on the developmental context, as has been observed in human cancer where Notch can function as a tumor suppressor or an oncogene. Thus, the outcome of Notch signalling can be influenced by the cross-talk between Notch and other signalling pathways. The use of model organisms such as Drosophila has been proven to be very valuable to understand the developmental role of the Notch pathway in different tissues and its relationship with other signalling pathways during cell proliferation control. Here we review recent studies in Drosophila that shed light in the developmental control of cell proliferation by the Notch pathway in different contexts such as the eye, wing and leg imaginal discs. We also discuss the autonomous and non-autonomous effects of the Notch pathway on cell proliferation and its interactions with different signalling pathways.
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Affiliation(s)
- Carlos Estella
- Departamento de Biología Molecular and Centro de Biología Molecular SeveroOchoa, Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Antonio Baonza
- Centro de Biología Molecular Severo Ochoa (CSIC/UAM) c/Nicolás Cabrera 1, 28049, Madrid, Spain
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4
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Su TT. Non-autonomous consequences of cell death and other perks of being metazoan. AIMS GENETICS 2021. [DOI: 10.3934/genet.2015.1.54] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abstract
Drosophila melanogaster remains a foremost genetic model to study basic cell biological processes in the context of multi-cellular development. In such context, the behavior of one cell can influence another. Non-autonomous signaling among cells occurs throughout metazoan development and disease, and is too vast to be covered by a single review. I will focus here on non-autonomous signaling events that occur in response to cell death in the larval epithelia and affect the life-death decision of surviving cells. I will summarize the use of Drosophila to study cell death-induced proliferation, apoptosis-induced apoptosis, and apoptosis-induced survival signaling. Key insights from Drosophila will be discussed in the context of analogous processes in mammalian development and cancer biology.
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Affiliation(s)
- Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309-0347, USA
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5
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Emmons-Bell M, Hariharan IK. Membrane potential regulates Hedgehog signalling in the Drosophila wing imaginal disc. EMBO Rep 2021; 22:e51861. [PMID: 33629503 PMCID: PMC8024891 DOI: 10.15252/embr.202051861] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/29/2020] [Accepted: 01/15/2021] [Indexed: 01/02/2023] Open
Abstract
While the membrane potential of cells has been shown to be patterned in some tissues, specific roles for membrane potential in regulating signalling pathways that function during development are still being established. In the Drosophila wing imaginal disc, Hedgehog (Hh) from posterior cells activates a signalling pathway in anterior cells near the boundary which is necessary for boundary maintenance. Here, we show that membrane potential is patterned in the wing disc. Anterior cells near the boundary, where Hh signalling is most active, are more depolarized than posterior cells across the boundary. Elevated expression of the ENaC channel Ripped Pocket (Rpk), observed in these anterior cells, requires Hh. Antagonizing Rpk reduces depolarization and Hh signal transduction. Using genetic and optogenetic manipulations, in both the wing disc and the salivary gland, we show that membrane depolarization promotes membrane localization of Smoothened and augments Hh signalling, independently of Patched. Thus, membrane depolarization and Hh‐dependent signalling mutually reinforce each other in cells immediately anterior to the compartment boundary.
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Affiliation(s)
- Maya Emmons-Bell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Iswar K Hariharan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
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6
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Kumar T, Blondel L, Extavour CG. Topology-driven protein-protein interaction network analysis detects genetic sub-networks regulating reproductive capacity. eLife 2020; 9:54082. [PMID: 32901612 PMCID: PMC7550192 DOI: 10.7554/elife.54082] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 09/01/2020] [Indexed: 12/23/2022] Open
Abstract
Understanding the genetic regulation of organ structure is a fundamental problem in developmental biology. Here, we use egg-producing structures of insect ovaries, called ovarioles, to deduce systems-level gene regulatory relationships from quantitative functional genetic analysis. We previously showed that Hippo signalling, a conserved regulator of animal organ size, regulates ovariole number in Drosophila melanogaster. To comprehensively determine how Hippo signalling interacts with other pathways in this regulation, we screened all known signalling pathway genes, and identified Hpo-dependent and Hpo-independent signalling requirements. Network analysis of known protein-protein interactions among screen results identified independent gene regulatory sub-networks regulating one or both of ovariole number and egg laying. These sub-networks predict involvement of previously uncharacterised genes with higher accuracy than the original candidate screen. This shows that network analysis combining functional genetic and large-scale interaction data can predict function of novel genes regulating development.
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Affiliation(s)
- Tarun Kumar
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
| | - Leo Blondel
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
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7
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Zhang X, Feng L, Qiao N, Liu Y, Zhang DC, Yin H. Cloning, expression pattern and functional characterization of fused, an important kinase of the Hedgehog signalling pathway from Locusta migratoria(Orthoptera: Acridoidea). BIOTECHNOL BIOTEC EQ 2019. [DOI: 10.1080/13102818.2019.1637781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- Xiaohong Zhang
- College of Life Sciences and the Key Laboratory of Zoological Systematics and Application, Hebei University, Baoding, Hebei, P. R. China
| | - Li Feng
- College of Life Sciences and the Key Laboratory of Zoological Systematics and Application, Hebei University, Baoding, Hebei, P. R. China
| | - Ning Qiao
- College of Life Sciences and the Key Laboratory of Zoological Systematics and Application, Hebei University, Baoding, Hebei, P. R. China
| | - Yachao Liu
- College of Life Sciences and the Key Laboratory of Zoological Systematics and Application, Hebei University, Baoding, Hebei, P. R. China
| | - Dao Chuan Zhang
- College of Life Sciences and the Key Laboratory of Zoological Systematics and Application, Hebei University, Baoding, Hebei, P. R. China
| | - Hong Yin
- College of Life Sciences and the Key Laboratory of Zoological Systematics and Application, Hebei University, Baoding, Hebei, P. R. China
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8
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Modelling Cooperative Tumorigenesis in Drosophila. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4258387. [PMID: 29693007 PMCID: PMC5859872 DOI: 10.1155/2018/4258387] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 01/21/2018] [Indexed: 12/13/2022]
Abstract
The development of human metastatic cancer is a multistep process, involving the acquisition of several genetic mutations, tumour heterogeneity, and interactions with the surrounding microenvironment. Due to the complexity of cancer development in mammals, simpler model organisms, such as the vinegar fly, Drosophila melanogaster, are being utilized to provide novel insights into the molecular mechanisms involved. In this review, we highlight recent advances in modelling tumorigenesis using the Drosophila model, focusing on the cooperation of oncogenes or tumour suppressors, and the interaction of mutant cells with the surrounding tissue in epithelial tumour initiation and progression.
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9
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Lu J, Wang D, Shen J. Hedgehog signalling is required for cell survival in Drosophila wing pouch cells. Sci Rep 2017; 7:11317. [PMID: 28900135 PMCID: PMC5595820 DOI: 10.1038/s41598-017-10550-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/10/2017] [Indexed: 11/09/2022] Open
Abstract
An appropriate balance between cell survival and cell death is essential for correct pattern formation in the animal tissues and organs. Previous studies have shown that the short-range signalling molecule Hedgehog (Hh) is required for cell proliferation and pattern formation in the Drosophila central wing discs. Signal transduction by one of the Hh targets, the morphogen Decapentaplegic (Dpp), is required for not only cell proliferation, but also cell survival in the pouch cells. However, Hh function in cell survival and cell death has not been revealed. Here, we found that loss of Hh signal activity induces considerable Caspase-dependent cell death in the wing pouch cells, and this process was independent of both Dpp signalling and Jun-N-terminal kinase (JNK) signalling. Loss of Hh induced activation of the pro-apoptotic gene hid and inhibition of diap1. Therefore, we identified an important role of Hh signalling in cell survival during Drosophila wing development.
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Affiliation(s)
- Juan Lu
- Department of Entomology, MOA Key Laboratory for monitoring and green management of crop pests, China Agricultural University, 100193, Beijing, China
| | - Dan Wang
- Department of Entomology, MOA Key Laboratory for monitoring and green management of crop pests, China Agricultural University, 100193, Beijing, China
| | - Jie Shen
- Department of Entomology, MOA Key Laboratory for monitoring and green management of crop pests, China Agricultural University, 100193, Beijing, China.
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10
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Zhou H, Neelakantan D, Ford HL. Clonal cooperativity in heterogenous cancers. Semin Cell Dev Biol 2017; 64:79-89. [PMID: 27582427 PMCID: PMC5330947 DOI: 10.1016/j.semcdb.2016.08.028] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 12/21/2022]
Abstract
Tumor heterogeneity is a major obstacle to the development of effective therapies and is thus an important focus of cancer research. Genetic and epigenetic alterations, as well as altered tumor microenvironments, result in tumors made up of diverse subclones with different genetic and phenotypic characteristics. Intratumor heterogeneity enables competition, but also supports clonal cooperation via cell-cell contact or secretion of factors, resulting in enhanced tumor progression. Here, we summarize recent findings related to interclonal interactions within a tumor and the therapeutic implications of such interactions, with an emphasis on how different subclones collaborate with each other to promote proliferation, metastasis and therapy-resistance. Furthermore, we propose that disruption of clonal cooperation by targeting key factors (such as Wnt and Hedgehog, amongst others) can be an alternative approach to improving clinical outcomes.
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Affiliation(s)
- Hengbo Zhou
- Program in Cancer Biology, University of Colorado School of Medicine, 12800 East 19th Avenue, Aurora, CO 80045, United States
| | - Deepika Neelakantan
- Program in Molecular Biology, University of Colorado School of Medicine, 12800 East 19th Avenue, Aurora, CO 80045, United States
| | - Heide L Ford
- Program in Cancer Biology, University of Colorado School of Medicine, 12800 East 19th Avenue, Aurora, CO 80045, United States; Program in Molecular Biology, University of Colorado School of Medicine, 12800 East 19th Avenue, Aurora, CO 80045, United States; Department of Pharmacology, University of Colorado School of Medicine, 12800 East 19th Avenue, Aurora, CO 80045, United States.
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11
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Chassaing N, Davis EE, McKnight KL, Niederriter AR, Causse A, David V, Desmaison A, Lamarre S, Vincent-Delorme C, Pasquier L, Coubes C, Lacombe D, Rossi M, Dufier JL, Dollfus H, Kaplan J, Katsanis N, Etchevers HC, Faguer S, Calvas P. Targeted resequencing identifies PTCH1 as a major contributor to ocular developmental anomalies and extends the SOX2 regulatory network. Genome Res 2016; 26:474-85. [PMID: 26893459 PMCID: PMC4817771 DOI: 10.1101/gr.196048.115] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 02/04/2016] [Indexed: 12/17/2022]
Abstract
Ocular developmental anomalies (ODA) such as anophthalmia/microphthalmia (AM) or anterior segment dysgenesis (ASD) have an estimated combined prevalence of 3.7 in 10,000 births. Mutations in SOX2 are the most frequent contributors to severe ODA, yet account for a minority of the genetic drivers. To identify novel ODA loci, we conducted targeted high-throughput sequencing of 407 candidate genes in an initial cohort of 22 sporadic ODA patients. Patched 1 (PTCH1), an inhibitor of sonic hedgehog (SHH) signaling, harbored an enrichment of rare heterozygous variants in comparison to either controls, or to the other candidate genes (four missense and one frameshift); targeted resequencing of PTCH1 in a second cohort of 48 ODA patients identified two additional rare nonsynonymous changes. Using multiple transient models and a CRISPR/Cas9-generated mutant, we show physiologically relevant phenotypes altering SHH signaling and eye development upon abrogation of ptch1 in zebrafish for which in vivo complementation assays using these models showed that all six patient missense mutations affect SHH signaling. Finally, through transcriptomic and ChIP analyses, we show that SOX2 binds to an intronic domain of the PTCH1 locus to regulate PTCH1 expression, findings that were validated both in vitro and in vivo. Together, these results demonstrate that PTCH1 mutations contribute to as much as 10% of ODA, identify the SHH signaling pathway as a novel effector of SOX2 activity during human ocular development, and indicate that ODA is likely the result of overactive SHH signaling in humans harboring mutations in either PTCH1 or SOX2.
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Affiliation(s)
- Nicolas Chassaing
- CHU Toulouse, Service de Génétique Médicale, Hôpital Purpan, 31059 Toulouse, France; Université Paul-Sabatier Toulouse III, EA-4555, 31000 Toulouse, France; Inserm U1056, 31000 Toulouse, France
| | - Erica E Davis
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina 27701, USA; Department of Pediatrics and Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27701, USA
| | - Kelly L McKnight
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina 27701, USA
| | - Adrienne R Niederriter
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina 27701, USA
| | - Alexandre Causse
- Université Paul-Sabatier Toulouse III, EA-4555, 31000 Toulouse, France; CHU Toulouse, Service d'Ophtalmologie, Hôpital Purpan, 31059 Toulouse, France
| | - Véronique David
- Institut de Génétique et Développement, CNRS UMR6290, Université de Rennes 1, IFR140 GFAS, Faculté de Médecine, 35043 Rennes, France; Laboratoire de Génétique Moléculaire, CHU Pontchaillou, 35043 Rennes Cedex, France
| | - Annaïck Desmaison
- Université Paul-Sabatier Toulouse III, EA-4555, 31000 Toulouse, France
| | - Sophie Lamarre
- Université de Toulouse; INSA, UPS, INP, LISBP, F-31077 Toulouse, France; INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France; CNRS, UMR5504, F-31400 Toulouse, France; Plateforme Biopuces de la Génopole de Toulouse Midi Pyrénées, INSA/DGBA 135, 31077 Toulouse, France
| | | | - Laurent Pasquier
- Service de Génétique Clinique, Hôpital Sud, 35200 Rennes, France
| | - Christine Coubes
- Service de Génétique Médicale, Hôpital Arnaud de Villeneuve, 34295 Montpellier, France
| | - Didier Lacombe
- Service de Génétique Médicale, Hôpital Pellegrin, 33076 Bordeaux Cedex, France; Université Bordeaux Segalen, Laboratoire MRGM, 33076 Bordeaux, France
| | - Massimiliano Rossi
- Service de Génétique, Hospices Civils de Lyon, Groupement Hospitalier Est, 69677 Bron, France; INSERM U1028 UMR CNRS 5292, UCBL, CRNL TIGER Team, 69677 Bron Cedex, France
| | - Jean-Louis Dufier
- Service d'Ophtalmologie, Hôpital Necker Enfants Malades, 75015 Paris, France
| | - Helene Dollfus
- Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, 67091 Strasbourg, France
| | - Josseline Kaplan
- INSERM U781 & Department of Genetics, Paris Descartes University, 75015 Paris, France
| | - Nicholas Katsanis
- Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina 27701, USA; Department of Pediatrics and Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27701, USA
| | - Heather C Etchevers
- Université Paul-Sabatier Toulouse III, EA-4555, 31000 Toulouse, France; INSERM, UMR_S910, Aix-Marseille University, Faculté de Médecine, 13385 Marseille, France
| | | | - Patrick Calvas
- CHU Toulouse, Service de Génétique Médicale, Hôpital Purpan, 31059 Toulouse, France; Université Paul-Sabatier Toulouse III, EA-4555, 31000 Toulouse, France; Inserm U1056, 31000 Toulouse, France
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12
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Saldanha SN, Tollefsbol TO. Pathway modulations and epigenetic alterations in ovarian tumorbiogenesis. J Cell Physiol 2014; 229:393-406. [PMID: 24105793 DOI: 10.1002/jcp.24466] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 09/06/2013] [Indexed: 12/23/2022]
Abstract
Cellular pathways are numerous and are highly integrated in function in the control of cellular systems. They collectively regulate cell division, proliferation, survival and apoptosis of cells and mutagenesis of key genes that control these pathways can initiate neoplastic transformations. Understanding these pathways is crucial to future therapeutic and preventive strategies of the disease. Ovarian cancers are of three major types; epithelial, germ-cell, and stromal. However, ovarian cancers of epithelial origin, arising from the mesothelium, are the predominant form. Of the subtypes of ovarian cancer, the high-grade serous tumors are fatal, with low survival rate due to late detection and poor response to treatments. Close examination of preserved ovarian tissues and in vitro studies have provided insights into the mechanistic changes occurring in cells mediated by a few key genes. This review will focus on pathways and key genes of the pathways that are mutated or have aberrant functions in the pathology of ovarian cancer. Non-genetic mechanisms that are gaining prominence in the pathology of ovarian cancer, miRNAs and epigenetics, will also be discussed in the review.
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Affiliation(s)
- Sabita N Saldanha
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama; Department of Biological Sciences, Alabama State University, Montgomery, Alabama
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13
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Abstract
Cell competition is the short-range elimination of slow-dividing cells through apoptosis when confronted with a faster growing population. It is based on the comparison of relative cell fitness between neighboring cells and is a striking example of tissue adaptability that could play a central role in developmental error correction and cancer progression in both Drosophila melanogaster and mammals. Cell competition has led to the discovery of multiple pathways that affect cell fitness and drive cell elimination. The diversity of these pathways could reflect unrelated phenomena, yet recent evidence suggests some common wiring and the existence of a bona fide fitness comparison pathway.
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Affiliation(s)
- Romain Levayer
- Institut für Zellbiologie, University of Bern, CH-3012 Bern, Switzerland
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14
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Da Ros VG, Gutierrez-Perez I, Ferres-Marco D, Dominguez M. Dampening the signals transduced through hedgehog via microRNA miR-7 facilitates notch-induced tumourigenesis. PLoS Biol 2013; 11:e1001554. [PMID: 23667323 PMCID: PMC3646720 DOI: 10.1371/journal.pbio.1001554] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 03/25/2013] [Indexed: 02/06/2023] Open
Abstract
Analysis of tumorigenesis in Drosophila reveals a tumor-suppressor role for Hedgehog signaling in the context of oncogenic Notch signaling. Fine-tuned Notch and Hedgehog signalling pathways via attenuators and dampers have long been recognized as important mechanisms to ensure the proper size and differentiation of many organs and tissues. This notion is further supported by identification of mutations in these pathways in human cancer cells. However, although it is common that the Notch and Hedgehog pathways influence growth and patterning within the same organ through the establishment of organizing regions, the cross-talk between these two pathways and how the distinct organizing activities are integrated during growth is poorly understood. Here, in an unbiased genetic screen in the Drosophila melanogaster eye, we found that tumour-like growth was provoked by cooperation between the microRNA miR-7 and the Notch pathway. Surprisingly, the molecular basis of this cooperation between miR-7 and Notch converged on the silencing of Hedgehog signalling. In mechanistic terms, miR-7 silenced the interference hedgehog (ihog) Hedgehog receptor, while Notch repressed expression of the brother of ihog (boi) Hedgehog receptor. Tumourigenesis was induced co-operatively following Notch activation and reduced Hedgehog signalling, either via overexpression of the microRNA or through specific down-regulation of ihog, hedgehog, smoothened, or cubitus interruptus or via overexpression of the cubitus interruptus repressor form. Conversely, increasing Hedgehog signalling prevented eye overgrowth induced by the microRNA and Notch pathway. Further, we show that blocking Hh signal transduction in clones of cells mutant for smoothened also enhance the organizing activity and growth by Delta-Notch signalling in the wing primordium. Together, these findings uncover a hitherto unsuspected tumour suppressor role for the Hedgehog signalling and reveal an unanticipated cooperative antagonism between two pathways extensively used in growth control and cancer. Growth control mechanisms ensure that organs attain the correct final size, generally averting tumour growth. This control is often linked to spatially confined domains known as organizers (conserved signalling centres), established along the dorsal-ventral and anterior-posterior axes of the organ by the Notch and Hedgehog pathways, respectively. The organizers emit signals that dictate growth, cell fate specification, and differentiation. However, how the distinct organizing signals received are integrated by cells within a growing organ remains a mystery. By studying how Delta-Notch signalling drives tumorigenesis, we identified the conserved microRNA miR-7 as a co-operative element in tumorigenesis mediated by Delta. We found that the cooperation between the microRNA and Delta-Notch pathway converged on the silencing of two obligatory and functionally redundant Hedgehog receptors, interference hedgehog and brother of ihog. Downregulation of other hedgehog pathway genes via RNA interference or genetic mosaics revealed a tumour suppressor role for Hedgehog signalling in the context of the oncogenic Notch pathway. Given the conservation of miR-7, as well as of the Notch and Hedgehog pathways, the conclusions we have drawn from these studies on Drosophila may be applicable to some human cancers.
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Affiliation(s)
| | | | | | - Maria Dominguez
- Instituto de Neurociencias, CSIC-UMH, Alicante, Spain
- * E-mail:
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15
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Non-cell autonomous control of apoptosis by ligand-independent Hedgehog signaling in Drosophila. Cell Death Differ 2012; 20:302-11. [PMID: 23018595 DOI: 10.1038/cdd.2012.126] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hedgehog (Hh) signaling is important for development and homeostasis in vertebrates and invertebrates. Ligand-independent, deregulated Hh signaling caused by loss of negative regulators such as Patched causes excessive cell proliferation, leading to overgrowth in Drosophila and tumors in humans, including basal-cell carcinoma and medulloblastoma. We show that in Drosophila deregulated Hh signaling also promotes cell survival by increasing the resistance to apoptosis. Surprisingly, cells with deregulated Hh activity do not protect themselves from apoptosis; instead, they promote cell survival of neighboring wild-type cells. This non-cell autonomous effect is mediated by Hh-induced Notch signaling, which elevates the protein levels of Drosophila inhibitor of apoptosis protein-1 (Diap-1), conferring resistance to apoptosis. In summary, we demonstrate that deregulated Hh signaling not only promotes proliferation but also cell survival of neighboring cells. This non-cell autonomous control of apoptosis highlights an underappreciated function of deregulated Hh signaling, which may help to generate a supportive micro-environment for tumor development.
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