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Campanale JP, Mondo JA, Montell DJ. A Scribble/Cdep/Rac pathway controls follower-cell crawling and cluster cohesion during collective border-cell migration. Dev Cell 2022; 57:2483-2496.e4. [PMID: 36347240 PMCID: PMC9725179 DOI: 10.1016/j.devcel.2022.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/10/2022] [Accepted: 10/12/2022] [Indexed: 11/09/2022]
Abstract
Collective cell movements drive normal development and metastasis. Drosophila border cells move as a cluster of 6-10 cells, where the role of the Rac GTPase in migration was first established. In border cells, as in most migratory cells, Rac stimulates leading-edge protrusion. Upstream Rac regulators in leaders have been identified; however, the regulation and function of Rac in follower border cells is unknown. Here, we show that all border cells require Rac, which promotes follower-cell motility and is important for cluster compactness and movement. We identify a Rac guanine nucleotide exchange factor, Cdep, which also regulates follower-cell movement and cluster cohesion. Scribble, Discs large, and Lethal giant larvae localize Cdep basolaterally and share phenotypes with Cdep. Relocalization of Cdep::GFP partially rescues Scribble knockdown, suggesting that Cdep is a major downstream effector of basolateral proteins. Thus, a Scrib/Cdep/Rac pathway promotes cell crawling and coordinated, collective migration in vivo.
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Affiliation(s)
- Joseph P Campanale
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - James A Mondo
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Denise J Montell
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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2
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Chatterjee D, Costa CAM, Wang XF, Jevitt A, Huang YC, Deng WM. Single-cell transcriptomics identifies Keap1-Nrf2 regulated collective invasion in a Drosophila tumor model. eLife 2022; 11:80956. [PMID: 36321803 PMCID: PMC9708074 DOI: 10.7554/elife.80956] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 11/01/2022] [Indexed: 11/30/2022] Open
Abstract
Apicobasal cell polarity loss is a founding event in epithelial-mesenchymal transition and epithelial tumorigenesis, yet how pathological polarity loss links to plasticity remains largely unknown. To understand the mechanisms and mediators regulating plasticity upon polarity loss, we performed single-cell RNA sequencing of Drosophila ovaries, where inducing polarity-gene l(2)gl-knockdown (Lgl-KD) causes invasive multilayering of the follicular epithelia. Analyzing the integrated Lgl-KD and wildtype transcriptomes, we discovered the cells specific to the various discernible phenotypes and characterized the underlying gene expression. A genetic requirement of Keap1-Nrf2 signaling in promoting multilayer formation of Lgl-KD cells was further identified. Ectopic expression of Keap1 increased the volume of delaminated follicle cells that showed enhanced invasive behavior with significant changes to the cytoskeleton. Overall, our findings describe the comprehensive transcriptome of cells within the follicle cell tumor model at the single-cell resolution and identify a previously unappreciated link between Keap1-Nrf2 signaling and cell plasticity at early tumorigenesis.
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Affiliation(s)
- Deeptiman Chatterjee
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, United States
| | - Caique Almeida Machado Costa
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, United States
| | - Xian-Feng Wang
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, United States
| | - Allison Jevitt
- Department of Biological Science, Florida State University, Tallahassee, United States
| | - Yi-Chun Huang
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, United States
| | - Wu-Min Deng
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, United States.,Department of Biological Science, Florida State University, Tallahassee, United States
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3
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Luo J, Zhou P, Guo X, Wang D, Chen J. The polarity protein Dlg5 regulates collective cell migration during Drosophila oogenesis. PLoS One 2019; 14:e0226061. [PMID: 31856229 PMCID: PMC6922378 DOI: 10.1371/journal.pone.0226061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 11/19/2019] [Indexed: 01/17/2023] Open
Abstract
Collective migration plays critical roles in animal development, physiological events, and cancer metastasis. However, the molecular mechanisms of collective cell migration are not well understood. Drosophila border cells represent an excellent in vivo genetic model to study collective cell migration and identify novel regulatory genes for cell migration. Using the Mosaic Analysis with a Repressible Cell Marker (MARCM) system, we screened 240 P-element insertion lines to identify essential genes for border cell migration. Two genes were uncovered, including dlg5 (discs large 5) and CG31689. Further analysis showed that Dlg5 regulates the apical-basal polarity and cluster integrity in border cell clusters. Dlg5 is enriched in lateral surfaces between border cells and central polar cells but also shows punctate localization between border cells. We found that the distribution of Dlg5 in border cell clusters is regulated by Armadillo. Structure-function analysis revealed that the N-terminal Coiled-coil domain and the C-terminal PDZ3-PDZ4-SH3-GUK domains but not the PDZ1-PDZ2 domains of Dlg5 are required for BC migration. The Coiled-coil domain and the PDZ4-SH3-GUK domains are critical for Dlg5’s cell surface localization in border cell clusters.
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Affiliation(s)
- Jun Luo
- College of Life Science, Shangrao Normal University, Shangrao, China
- * E-mail: (JL); (JC)
| | - Ping Zhou
- College of Life Science, Shangrao Normal University, Shangrao, China
| | - Xuan Guo
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Dou Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Jiong Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, Nanjing, China
- * E-mail: (JL); (JC)
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Duhart JC, Parsons TT, Raftery LA. The repertoire of epithelial morphogenesis on display: Progressive elaboration of Drosophila egg structure. Mech Dev 2017; 148:18-39. [PMID: 28433748 DOI: 10.1016/j.mod.2017.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/07/2017] [Accepted: 04/12/2017] [Indexed: 12/26/2022]
Abstract
Epithelial structures are foundational for tissue organization in all metazoans. Sheets of epithelial cells form lateral adhesive junctions and acquire apico-basal polarity perpendicular to the surface of the sheet. Genetic analyses in the insect model, Drosophila melanogaster, have greatly advanced our understanding of how epithelial organization is established, and how it is modulated during tissue morphogenesis. Major insights into collective cell migrations have come from analyses of morphogenetic movements within the adult follicular epithelium that cooperates with female germ cells to build a mature egg. Epithelial follicle cells progress through tightly choreographed phases of proliferation, patterning, reorganization and migrations, before they differentiate to form the elaborate structures of the eggshell. Distinct structural domains are organized by differential adhesion, within which lateral junctions are remodeled to further shape the organized epithelia. During collective cell migrations, adhesive interactions mediate supracellular organization of planar polarized macromolecules, and facilitate crawling over the basement membrane or traction against adjacent cell surfaces. Comparative studies with other insects are revealing the diversification of morphogenetic movements for elaboration of epithelial structures. This review surveys the repertoire of follicle cell morphogenesis, to highlight the coordination of epithelial plasticity with progressive differentiation of a secretory epithelium. Technological advances will keep this tissue at the leading edge for interrogating the precise spatiotemporal regulation of normal epithelial reorganization events, and provide a framework for understanding pathological tissue dysplasia.
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Affiliation(s)
- Juan Carlos Duhart
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States
| | - Travis T Parsons
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States
| | - Laurel A Raftery
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States.
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Saadin A, Starz-Gaiano M. Circuitous Genetic Regulation Governs a Straightforward Cell Migration. Trends Genet 2016; 32:660-673. [PMID: 27600524 DOI: 10.1016/j.tig.2016.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/01/2016] [Accepted: 08/02/2016] [Indexed: 12/19/2022]
Abstract
Drosophila border cells undergo a straightforward and stereotypical collective migration during egg development. However, a complex genetic program underlies this process. A variety of approaches, including biochemical, genetic, and imaging strategies have identified many regulatory components, revealing layers of control. This complexity suggests that the active processes of evaluating the environment, remodeling the cytoskeleton, and coordinating movements among cells, demand rapid systems for modulating cell behaviors. Multiple signaling inputs, nodes of integration, and feedback loops act as molecular rheostats to fine-tune gene expression levels and physical responses. Since key genetic regulators of border cell migration have been shown to be required in other types of cell migration, this model system continues to provide an important avenue for genetic discovery.
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Affiliation(s)
- Afsoon Saadin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Michelle Starz-Gaiano
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
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Abstract
Programmed cell death (PCD) is essential for health and development. Generally, the last step of PCD is clearance, or engulfment, by phagocytes. Engulfment can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification of the engulfed material. The Drosophila melanogaster ovary serves as an excellent model to study diverse types of PCD and engulfment by epithelial cells. Here, we describe several methods to detect and analyze multiple steps of engulfment in the Drosophila ovary: recognition, vesicle uptake, phagosome maturation, and acidification. Annexin V detects phosphatidylserine, which is flipped to the outer leaflet of the plasma membrane of apoptotic cells, serving as an "eat me" signal. Several germline markers including tral-GFP, Orb, and cleaved Dcp-1 can all be used to label the germline and visualize its uptake into engulfing follicle cells. Drosophila strains expressing GFP and mCherry protein fusions can enable a detailed analysis of phagosome maturation. LysoTracker labels highly acidified compartments, marking phagolysosomes. Together these labels can be used to mark the progression of engulfment in Drosophila follicle cells.
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7
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Group choreography: mechanisms orchestrating the collective movement of border cells. Nat Rev Mol Cell Biol 2012; 13:631-45. [PMID: 23000794 DOI: 10.1038/nrm3433] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell movements are essential for animal development and homeostasis but also contribute to disease. Moving cells typically extend protrusions towards a chemoattractant, adhere to the substrate, contract and detach at the rear. It is less clear how cells that migrate in interconnected groups in vivo coordinate their behaviour and navigate through natural environments. The border cells of the Drosophila melanogaster ovary have emerged as an excellent model for the study of collective cell movement, aided by innovative genetic, live imaging, and photomanipulation techniques. Here we provide an overview of the molecular choreography of border cells and its more general implications.
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Gandille P, Narbonne-Reveau K, Boissonneau E, Randsholt N, Busson D, Pret AM. Mutations in the polycomb group gene polyhomeotic lead to epithelial instability in both the ovary and wing imaginal disc in Drosophila. PLoS One 2010; 5:e13946. [PMID: 21085656 PMCID: PMC2978711 DOI: 10.1371/journal.pone.0013946] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 10/08/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Most human cancers originate from epithelial tissues and cell polarity and adhesion defects can lead to metastasis. The Polycomb-Group of chromatin factors were first characterized in Drosophila as repressors of homeotic genes during development, while studies in mammals indicate a conserved role in body plan organization, as well as an implication in other processes such as stem cell maintenance, cell proliferation, and tumorigenesis. We have analyzed the function of the Drosophila Polycomb-Group gene polyhomeotic in epithelial cells of two different organs, the ovary and the wing imaginal disc. RESULTS Clonal analysis of loss and gain of function of polyhomeotic resulted in segregation between mutant and wild-type cells in both the follicular and wing imaginal disc epithelia, without excessive cell proliferation. Both basal and apical expulsion of mutant cells was observed, the former characterized by specific reorganization of cell adhesion and polarity proteins, the latter by complete cytoplasmic diffusion of these proteins. Among several candidate target genes tested, only the homeotic gene Abdominal-B was a target of PH in both ovarian and wing disc cells. Although overexpression of Abdominal-B was sufficient to cause cell segregation in the wing disc, epistatic analysis indicated that the presence of Abdominal-B is not necessary for expulsion of polyhomeotic mutant epithelial cells suggesting that additional polyhomeotic targets are implicated in this phenomenon. CONCLUSION Our results indicate that polyhomeotic mutations have a direct effect on epithelial integrity that can be uncoupled from overproliferation. We show that cells in an epithelium expressing different levels of polyhomeotic sort out indicating differential adhesive properties between the cell populations. Interestingly, we found distinct modalities between apical and basal expulsion of ph mutant cells and further studies of this phenomenon should allow parallels to be made with the modified adhesive and polarity properties of different types of epithelial tumors.
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Affiliation(s)
- Pierre Gandille
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Karine Narbonne-Reveau
- Institut de Biologie du Développement de Marseille-Luminy (UMR 6216), Centre National de la Recherche Scientifique/Université de la Méditérannée Aix-Marseille II, Marseille, France
- Institut Jacques Monod (UMR7592), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Université Denis Diderot-Paris VII, Paris, France
| | - Elisabeth Boissonneau
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Neel Randsholt
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
- Laboratoire de Biologie du Développement (UMR7622), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Paris, France
| | - Denise Busson
- Institut Jacques Monod (UMR7592), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Université Denis Diderot-Paris VII, Paris, France
- Systematique Adaptation Evolution (UMR7138), Université Pierre et Marie Curie Paris VI, Paris, France
| | - Anne-Marie Pret
- Centre de Génétique Moléculaire (FRE 3144), Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
- Institut Jacques Monod (UMR7592), Centre National de la Recherche Scientifique/Université Pierre et Marie Curie-Paris VI, Université Denis Diderot-Paris VII, Paris, France
- Université de Versailles-St Quentin, Versailles, France
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Franz A, Riechmann V. Stepwise polarisation of the Drosophila follicular epithelium. Dev Biol 2010; 338:136-47. [DOI: 10.1016/j.ydbio.2009.11.027] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 10/13/2009] [Accepted: 11/20/2009] [Indexed: 01/17/2023]
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10
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Li Q, Shen L, Xin T, Xiang W, Chen W, Gao Y, Zhu M, Yu L, Li M. Role of Scrib and Dlg in anterior-posterior patterning of the follicular epithelium during Drosophila oogenesis. BMC DEVELOPMENTAL BIOLOGY 2009; 9:60. [PMID: 19948068 PMCID: PMC2810132 DOI: 10.1186/1471-213x-9-60] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 12/01/2009] [Indexed: 11/25/2022]
Abstract
Background Proper patterning of the follicle cell epithelium over the egg chamber is essential for the Drosophila egg development. Differentiation of the epithelium into several distinct cell types along the anterior-posterior axis requires coordinated activities of multiple signaling pathways. Previously, we reported that lethal(2)giant larvae (lgl), a Drosophila tumor suppressor gene, is required in the follicle cells for the posterior follicle cell (PFC) fate induction at mid-oogenesis. Here we explore the role of another two tumor suppressor genes, scribble (scrib) and discs large (dlg), in the epithelial patterning. Results We found that removal of scrib or dlg function from the follicle cells at posterior terminal of the egg chamber causes a complete loss of the PFC fate. Aberrant specification and differentiation of the PFCs in the mosaic clones can be ascribed to defects in coordinated activation of the EGFR, JAK and Notch signaling pathways in the multilayered cells. Meanwhile, the clonal analysis revealed that loss-of-function mutations in scrib/dlg at the anterior domains result in a partially penetrant phenotype of defective induction of the stretched and centripetal cell fate, whereas specification of the border cell fate can still occur in the most anterior region of the mutant clones. Further, we showed that scrib genetically interacts with dlg in regulating posterior patterning of the epithelium. Conclusion In this study we provide evidence that scrib and dlg function differentially in anterior and posterior patterning of the follicular epithelium at oogenesis. Further genetic analysis indicates that scrib and dlg act in a common pathway to regulate PFC fate induction. This study may open another window for elucidating role of scrib/dlg in controlling epithelial polarity and cell proliferation during development.
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Affiliation(s)
- Qi Li
- MoE Key Laboratory of Developmental Genetics and Neuropsychiatric Diseases, Bio-X Center, School of Life Science and Biotechnology, Shanghai Jiao Tong University, 200240 Shanghai, PR
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Abstract
The neoplastic tumour suppressors, Scribble, Dlg and Lgl, originally discovered in the vinegar fly Drosophila melanogaster, are currently being actively studied for their potential role in mammalian tumourigenesis. In Drosophila, these tumour suppressors function in a common genetic pathway to regulate apicobasal cell polarity and also play important roles in the control of cell proliferation, survival, differentiation and in cell migration/invasion. The precise mechanism by which Scribble, Dlg and Lgl function is not clear; however, they have been implicated in the regulation of signalling pathways, vesicle trafficking and in the Myosin II-actin cytoskeleton. We review the evidence for the involvement of Scribble, Dlg, and Lgl in cancer, and how the various functions ascribed to these tumour suppressors in Drosophila and mammalian systems may impact on the process of tumourigenesis.
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12
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Basolateral junctions utilize warts signaling to control epithelial-mesenchymal transition and proliferation crucial for migration and invasion of Drosophila ovarian epithelial cells. Genetics 2008; 178:1947-71. [PMID: 18430928 DOI: 10.1534/genetics.108.086983] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fasciclin2 (Fas2) and Discslarge (Dlg) localize to the basolateral junction (BLJ) of Drosophila follicle epithelial cells and inhibit their proliferation and invasion. To identify a BLJ signaling pathway we completed a genomewide screen for mutants that enhance dlg tumorigenesis. We identified two genes that encode known BLJ scaffolding proteins, lethal giant larvae (lgl) and scribble (scrib), and several not previously associated with BLJ function, including warts (wts) and roughened eye (roe), which encode a serine-threonine kinase and a transcription factor, respectively. Like scrib, wts and roe also enhance Fas2 and lgl tumorigenesis. Further, scrib, wts, and roe block border cell migration, and cause noninvasive tumors that resemble dlg partial loss of function, suggesting that the BLJ utilizes Wts signaling to repress EMT and proliferation, but not motility. Apicolateral junction proteins Fat (Ft), Expanded (Ex), and Merlin (Mer) either are not involved in these processes, or have highly spatio-temporally restricted roles, diminishing their significance as upstream inputs to Wts in follicle cells. This is further indicated in that Wts targets, CyclinE and DIAP1, are elevated in Fas2, dlg, lgl, wts, and roe cells, but not Fat, ex, or mer cells. Thus, the BLJ appears to regulate epithelial polarity and dynamics not only as a localized scaffold, but also by communicating signals to the nucleus. Wts may be regulated by distinct junction inputs depending on developmental context.
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Denef N, Chen Y, Weeks SD, Barcelo G, Schüpbach T. Crag regulates epithelial architecture and polarized deposition of basement membrane proteins in Drosophila. Dev Cell 2008; 14:354-64. [PMID: 18331716 DOI: 10.1016/j.devcel.2007.12.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 09/13/2007] [Accepted: 12/18/2007] [Indexed: 01/19/2023]
Abstract
The polarized architecture of epithelia relies on an interplay between the cytoskeleton, the trafficking machinery, and cell-cell and cell-matrix adhesion. Specifically, contact with the basement membrane (BM), an extracellular matrix underlying the basal side of epithelia, is important for cell polarity. However, little is known about how BM proteins themselves achieve a polarized distribution. In a genetic screen in the Drosophila follicular epithelium, we identified mutations in Crag, which encodes a conserved protein with domains implicated in membrane trafficking. Follicle cells mutant for Crag lose epithelial integrity and frequently become invasive. The loss of Crag leads to the anomalous accumulation of BM components on both sides of epithelial cells without directly affecting the distribution of apical or basolateral membrane proteins. This defect is not generally observed in mutants affecting epithelial integrity. We propose that Crag plays a unique role in organizing epithelial architecture by regulating the polarized secretion of BM proteins.
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Affiliation(s)
- Natalie Denef
- Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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14
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Drosophila follicle cells: morphogenesis in an eggshell. Semin Cell Dev Biol 2008; 19:271-82. [PMID: 18304845 DOI: 10.1016/j.semcdb.2008.01.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 01/16/2008] [Indexed: 01/15/2023]
Abstract
Epithelial morphogenesis is important for organogenesis and pivotal for carcinogenesis, but mechanisms that control it are poorly understood. The Drosophila follicular epithelium is a genetically tractable model to understand these mechanisms in vivo. This epithelium of follicle cells encases germline cells to create an egg. In this review, we summarize progress toward understanding mechanisms that maintain the epithelium or permit migrations essential for oogenesis. Cell-cell communication is important, but the same signals are used repeatedly to control distinct events. Understanding intrinsic mechanisms that alter responses to developmental signals will be important to understand regulation of cell shape and organization.
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15
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Poulton JS, Deng WM. Cell-cell communication and axis specification in the Drosophila oocyte. Dev Biol 2007; 311:1-10. [PMID: 17884037 PMCID: PMC2174919 DOI: 10.1016/j.ydbio.2007.08.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 07/13/2007] [Accepted: 08/08/2007] [Indexed: 01/23/2023]
Abstract
Intercellular communication between the somatic and germline cells is vital to development of the Drosophila egg chamber. One critical outcome of this communication is the polarization of the oocyte along the anterior-posterior axis, a process induced by an unknown signal from the somatic follicle cells to the oocyte. The existence of this signal has been inferred from several reports demonstrating that the differentiation and patterning of the follicle cells by the spatially restricted activation of certain cell-signaling pathways is necessary for axis formation in the oocyte. These reports have also provided a framework for understanding how these signaling pathways are integrated to generate the follicle-cell pattern, but the precise role of the follicle cells in anterior-posterior axis formation remains enigmatic. Research has identified several genes that appear to be involved in the polarizing communication from the follicle cells to the oocyte. Interestingly the proteins encoded by most of these genes are associated with the extracellular matrix, suggesting a pivotal role for this complex biological component in the polarizing communication between the follicle cells and the oocyte. This review summarizes the findings in this area, and uses the experimental analyses of these genes to evaluate various models describing the possible nature of the polarizing signal, and the role of these genes in it.
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Affiliation(s)
| | - Wu-Min Deng
- *Corresponding author. E-mail address: (Wu-Min Deng)
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16
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Conder R, Yu H, Zahedi B, Harden N. The serine/threonine kinase dPak is required for polarized assembly of F-actin bundles and apical–basal polarity in the Drosophila follicular epithelium. Dev Biol 2007; 305:470-82. [PMID: 17383630 DOI: 10.1016/j.ydbio.2007.02.034] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 01/29/2007] [Accepted: 02/23/2007] [Indexed: 01/24/2023]
Abstract
During epithelial development cells become polarized along their apical-basal axis and some epithelia also exhibit polarity in the plane of the tissue. Mutations in the gene encoding a Drosophila Pak family serine/threonine kinase, dPak, disrupt the follicular epithelium that covers developing egg chambers during oogenesis. The follicular epithelium normally exhibits planar polarized organization of basal F-actin bundles such that they lie perpendicular to the anterior-posterior axis of the egg chamber, and requires contact with the basement membrane for apical-basal polarization. During oogenesis, dPak becomes localized to the basal end of follicle cells and is required for polarized organization of the basal actin cytoskeleton and for epithelial integrity and apical-basal polarity. The receptor protein tyrosine phosphatase Dlar and integrins, all receptors for extracellular matrix proteins, are required for polarization of the basal F-actin bundles, and for correct dPak localization in follicle cells. dpak mutant follicle cells show increased beta(Heavy)-spectrin levels, and we speculate that dPak regulation of beta(Heavy)-spectrin, a known participant in the maintenance of membrane domains, is required for correct apical-basal polarization of the membrane. We propose that dPak mediates communication between the basement membrane and intracellular proteins required for polarization of the basal F-actin and for apical-basal polarity.
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Affiliation(s)
- Ryan Conder
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
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17
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Levine B, Jean-Francois M, Bernardi F, Gargiulo G, Dobens L. Notch signaling links interactions between the C/EBP homolog slow border cells and the GILZ homolog bunched during cell migration. Dev Biol 2007; 305:217-31. [PMID: 17383627 DOI: 10.1016/j.ydbio.2007.02.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 01/11/2007] [Accepted: 02/09/2007] [Indexed: 10/23/2022]
Abstract
In the follicle cell (FC) epithelium that surrounds the Drosophila egg, a complex set of cell signals specifies two cell fates that pattern the eggshell: the anterior centripetal FC that produce the operculum and the posterior columnar FC that produce the main body eggshell structure. We have previously shown that the long-range morphogen DPP represses the expression of the bunched (bun) gene in the anterior-most centripetal FC. bun, which encodes a homolog of vertebrate TSC-22/GILZ, in turn represses anterior gene expression and antagonizes Notch signaling to restrict centripetal FC fates in posterior cells. From a screen for novel targets of bun repression we have identified the C/EBP homolog slow border cells (slbo). At stage 10A, slbo expression overlaps bun in anterior FC; by stage 10B they repress each other's expression to establish a sharp slbo/bun expression boundary. The precise position of the slbo/bun expression boundary is sensitive to Notch signaling, which is required for both slbo activation and bun repression. As centripetal migration proceeds from stages 10B-14, slbo represses its own expression and both slbo loss-of-function mutations and overexpression approaches reveal that slbo is required to coordinate centripetal migration with nurse cell dumping. We propose that in anterior FC exposed to a Dpp morphogen gradient, high and low levels of slbo and bun, respectively, are established by modulation of Notch signaling to direct threshold cell fates. Interactions among Notch, slbo and bun resemble a conserved signaling cassette that regulates mammalian adipocyte differentiation.
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Affiliation(s)
- Benjamin Levine
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
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Mirouse V, Swick LL, Kazgan N, St Johnston D, Brenman JE. LKB1 and AMPK maintain epithelial cell polarity under energetic stress. ACTA ACUST UNITED AC 2007; 177:387-92. [PMID: 17470638 PMCID: PMC2064817 DOI: 10.1083/jcb.200702053] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
LKB1 is mutated in both familial and spontaneous tumors, and acts as a master kinase that activates the PAR-1 polarity kinase and the adenosine 5′monophosphate–activated kinase (AMPK). This has led to the hypothesis that LKB1 acts as a tumor suppressor because it is required to maintain cell polarity and growth control through PAR-1 and AMPK, respectively. However, the genetic analysis of LKB1–AMPK signaling in vertebrates has been complicated by the existence of multiple redundant AMPK subunits. We describe the identification of mutations in the single Drosophila melanogaster AMPK catalytic subunit AMPKα. Surprisingly, ampkα mutant epithelial cells lose their polarity and overproliferate under energetic stress. LKB1 is required in vivo for AMPK activation, and lkb1 mutations cause similar energetic stress–dependent phenotypes to ampkα mutations. Furthermore, lkb1 phenotypes are rescued by a phosphomimetic version of AMPKα. Thus, LKB1 signals through AMPK to coordinate epithelial polarity and proliferation with cellular energy status, and this might underlie the tumor suppressor function of LKB1.
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Affiliation(s)
- Vincent Mirouse
- The Gurdon Institute, Department of Genetics, University of Cambridge, Cambridge, England, UK
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19
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Szafranski P, Goode S. Basolateral junctions are sufficient to suppress epithelial invasion duringDrosophilaoogenesis. Dev Dyn 2007; 236:364-73. [PMID: 17103414 DOI: 10.1002/dvdy.21020] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Epithelial junctions play crucial roles during metazoan evolution and development by facilitating tissue formation, maintenance, and function. Little is known about the role of distinct types of junctions in controlling epithelial transformations leading to invasion of neighboring tissues. Discovering the key junction complexes that control these processes and how they function may also provide mechanistic insight into carcinoma cell invasion. Here, using the Drosophila ovary as a model, we show that four proteins of the basolateral junction (BLJ), Fasciclin-2, Neuroglian, Discs-large, and Lethal-giant-larvae, but not proteins of other epithelial junctions, directly suppress epithelial tumorigenesis and invasion. Remarkably, the expression pattern of Fasciclin-2 predicts which cells will invade. We compared the apicobasal polarity of BLJ tumor cells to border cells (BCs), an epithelium-derived cluster that normally migrates during mid-oogenesis. Both tumor cells and BCs differentiate a lateralized membrane pattern that is necessary but not sufficient for invasion. Independent of lateralization, derepression of motility pathways is also necessary, as indicated by a strong linear correlation between faster BC migration and an increased incidence of tumor invasion. However, without membrane lateralization, derepression of motility pathways is also not sufficient for invasion. Our results demonstrate that spatiotemporal patterns of basolateral junction activity directly suppress epithelial invasion by organizing the cooperative activity of distinct polarity and motility pathways.
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Dow LE, Humbert PO. Polarity Regulators and the Control of Epithelial Architecture, Cell Migration, and Tumorigenesis. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 262:253-302. [PMID: 17631191 DOI: 10.1016/s0074-7696(07)62006-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A large body of work on Drosophila melanogaster has identified and characterized a number of key polarity regulators, many of which are required for the regulation of multiple other processes including proliferation, migration, invasion, and tumorigenesis. Humans possess either single or multiple homologues of each of the Drosophila polarity proteins, and in most cases, these are highly conserved between species, implying an important and conserved function for each of the polarity complexes. Recent studies in cultured mammalian epithelial cells have shed some light on the requirement for the polarity complexes in the regulation of epithelial cell function, including an unexpected link to the regulation of directed cell migration. However, many questions still remain regarding the molecular mechanisms of polarity regulation and whether disruption of polarity protein function is an important step in the development of human cancers. Here we will review what is currently understood about the regulation of cell polarity, migration, and invasion and the level of functional conservation between Drosophila and mammalian tissues. Particular reference will be made as to how the Scribble and Par polarity complexes may be involved in the regulation of apical-basal polarity, migration, and tumorigenesis.
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Affiliation(s)
- Lukas E Dow
- Cell Cycle and Cancer Genetics Laboratory, Peter MacCallum Cancer Center, Melbourne, Australia
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21
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Beaucher M, Goodliffe J, Hersperger E, Trunova S, Frydman H, Shearn A. Drosophila brain tumor metastases express both neuronal and glial cell type markers. Dev Biol 2006; 301:287-97. [PMID: 17055475 PMCID: PMC1859848 DOI: 10.1016/j.ydbio.2006.09.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 08/29/2006] [Accepted: 09/08/2006] [Indexed: 12/23/2022]
Abstract
Loss of either lgl or brat gene activity in Drosophila larvae causes neoplastic brain tumors. Fragments of tumorous brains from either mutant transplanted into adult hosts over-proliferate, and kill their hosts within 2 weeks. We developed an in vivo assay for the metastatic potential of tumor cells by quantifying micrometastasis formation within the ovarioles of adult hosts after transplantation and determined that specific metastatic properties of lgl and brat tumor cells are different. We detected micrometastases in 15.8% of ovarioles from wild type host females 12 days after transplanting lgl tumor cells into their abdominal cavities. This frequency increased significantly with increased proliferation time. We detected micrometastases in 15% of ovarioles from wild type host females 10 days after transplanting brat tumor cells into their abdominal cavities. By contrast, this frequency did not change significantly with increased proliferation time. We found that nearly all lgl micrometastases co-express the neuronal cell marker, ELAV, and the glial cell marker, REPO. These markers are not co-expressed in normal brain cells nor in tumorous brain cells. This indicates deregulated gene expression in these metastatic cells. By contrast, most of the brat micrometastases expressed neither marker. While mutations in both lgl and brat cause neoplastic brain tumors, our results reveal that metastatic cells arising from these tumors have quite different properties. These data may have important implications for the treatment of tumor metastasis.
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Affiliation(s)
- Michelle Beaucher
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
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