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Esmangart de Bournonville T, Jaglarz MK, Durel E, Le Borgne R. ESCRT-III-dependent adhesive and mechanical changes are triggered by a mechanism detecting alteration of septate junction integrity in Drosophila epithelial cells. eLife 2024; 13:e91246. [PMID: 38305711 PMCID: PMC10959524 DOI: 10.7554/elife.91246] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 02/01/2024] [Indexed: 02/03/2024] Open
Abstract
Barrier functions of proliferative epithelia are constantly challenged by mechanical and chemical constraints. How epithelia respond to and cope with disturbances of barrier functions to allow tissue integrity maintenance is poorly characterised. Cellular junctions play an important role in this process and intracellular traffic contribute to their homeostasis. Here, we reveal that, in Drosophila pupal notum, alteration of the bi- or tricellular septate junctions (SJs) triggers a mechanism with two prominent outcomes. On one hand, there is an increase in the levels of E-cadherin, F-actin, and non-muscle myosin II in the plane of adherens junctions. On the other hand, β-integrin/Vinculin-positive cell contacts are reinforced along the lateral and basal membranes. We found that the weakening of SJ integrity, caused by the depletion of bi- or tricellular SJ components, alters ESCRT-III/Vps32/Shrub distribution, reduces degradation and instead favours recycling of SJ components, an effect that extends to other recycled transmembrane protein cargoes including Crumbs, its effector β-Heavy Spectrin Karst, and β-integrin. We propose a mechanism by which epithelial cells, upon sensing alterations of the SJ, reroute the function of Shrub to adjust the balance of degradation/recycling of junctional cargoes and thereby compensate for barrier junction defects to maintain epithelial integrity.
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Affiliation(s)
- Thomas Esmangart de Bournonville
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290RennesFrance
- Global Health Institute, School of Life Science, Ecole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Mariusz K Jaglarz
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University in KrakowKrakowPoland
| | - Emeline Durel
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290RennesFrance
| | - Roland Le Borgne
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290RennesFrance
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2
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Nguyen CT, Nguyen VM, Jeong S. Regulation of Off-track bidirectional signaling by Semaphorin-1a and Wnt signaling in the Drosophila motor axon guidance. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 150:103857. [PMID: 36244650 DOI: 10.1016/j.ibmb.2022.103857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/23/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Off-track receptor tyrosine kinase (OTK) has been shown to play an important role in the Drosophila motor axon pathfinding. The results of biochemical and genetic interactions previously suggested that OTK acts as a component of Semaphorin-1a/Plexin A (Sema-1a/PlexA) signaling during embryonic motor axon guidance and further showed that OTK binds to Wnt family members Wnt2 and Wnt4 and their common receptor Frizzled (Fz). However, the molecular mechanisms underlying the motor axon guidance function of OTK remain elusive. Here, we conclude that OTK mediates the forward and reverse signaling required for intersegmental nerve b (ISNb) motor axon pathfinding and we also demonstrate that the loss of two copies of Sema-1a synergistically enhances the bypass phenotype observed in otk mutants. Furthermore, the amorphic wnt2 mutation resulted in increased premature branching phenotypes, and the loss of fz function caused a frequent inability of ISNb motor axons to defasciculate at specific choice points. Consistent with a previous study, wnt4 mutant axons were often defective in recognizing target muscles. Interestingly, the bypass phenotype of otk mutants was robustly suppressed by loss of function mutations in wnt2, wnt4, or fz. In contrast, total ISNb defects of otk were increased by the loss-of-function alleles in wnt2 and wnt4, but not fz. These findings indicate that OTK may participate in the crosstalk between the Sema-1a/PlexA and Wnt signaling pathways, thereby contributing to ISNb motor axon pathfinding and target recognition.
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Affiliation(s)
- Chinh Thanh Nguyen
- Division of Life Sciences (Molecular Biology Major), Department of Bioactive Material Sciences, Research Center of Bioactive Materials, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Van Minh Nguyen
- Division of Life Sciences (Molecular Biology Major), Department of Bioactive Material Sciences, Research Center of Bioactive Materials, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Sangyun Jeong
- Division of Life Sciences (Molecular Biology Major), Department of Bioactive Material Sciences, Research Center of Bioactive Materials, Jeonbuk National University, Jeonju, 54896, Republic of Korea.
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3
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De O, Rice C, Zulueta-Coarasa T, Fernandez-Gonzalez R, Ward RE. Septate junction proteins are required for cell shape changes, actomyosin reorganization and cell adhesion during dorsal closure in Drosophila. Front Cell Dev Biol 2022; 10:947444. [PMID: 36238688 PMCID: PMC9553006 DOI: 10.3389/fcell.2022.947444] [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: 05/18/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Septate junctions (SJs) serve as occluding barriers in invertebrate epithelia. In Drosophila, at least 30 genes are required for the formation or maintenance of SJs. Interestingly, loss-of-function mutations in core SJ components are embryonic lethal, with defects in developmental events such as head involution and dorsal closure (DC) that occur prior to the formation of a mature SJ, indicating a role for these proteins in mid-embryogenesis independent of their occluding function. To understand this novel function in development, we examined loss-of-function mutations in three core SJ proteins during the process of DC. DC occurs during mid-embryogenesis to seal a dorsal gap in the epidermis following germ band retraction. Closure is driven by contraction of the extraembryonic amnioserosa cells that temporarily cover the dorsal surface and by cell shape changes (elongation) of lateral epidermal cells that bring the contralateral sheets together at the dorsal midline. Using live imaging and examination of fixed tissues, we show that early events in DC occur normally in SJ mutant embryos, but during later closure, coracle, Macroglobulin complement-related and Neurexin-IV mutant embryos exhibit slower rates of closure and display aberrant cells shapes in the dorsolateral epidermis, including dorsoventral length and apical surface area. SJ mutant embryos also show mild defects in actomyosin structures along the leading edge, but laser cutting experiments suggest similar tension and viscoelastic properties in SJ mutant versus wild type epidermis. In a high percentage of SJ mutant embryos, the epidermis tears free from the amnioserosa near the end of DC and live imaging and immunostaining reveal reduced levels of E-cadherin, suggesting that defective adhesion may be responsible for these tears. Supporting this notion, reducing E-cadherin by half significantly enhances the penetrance of DC defects in coracle mutant embryos.
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Affiliation(s)
- Oindrila De
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Clinton Rice
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States
| | | | | | - Robert E Ward
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States
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4
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The basement membrane controls size and integrity of the Drosophila tracheal tubes. Cell Rep 2022; 39:110734. [PMID: 35476979 DOI: 10.1016/j.celrep.2022.110734] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 01/17/2022] [Accepted: 04/04/2022] [Indexed: 11/20/2022] Open
Abstract
Biological tubes are fundamental units of most metazoan organs. Their defective morphogenesis can cause malformations and pathologies. An integral component of biological tubes is the extracellular matrix, present apically (aECM) and basally (BM). Studies using the Drosophila tracheal system established an essential function for the aECM in tubulogenesis. Here, we demonstrate that the BM also plays a critical role in this process. We find that BM components are deposited in a spatial-temporal manner in the trachea. We show that laminins, core BM components, control size and shape of tracheal tubes and their topology within the embryo. At a cellular level, laminins control cell shape changes and distribution of the cortical cytoskeleton component α-spectrin. Finally, we report that the BM and aECM act independently-yet cooperatively-to control tube elongation and together to guarantee tissue integrity. Our results unravel key roles for the BM in shaping, positioning, and maintaining biological tubes.
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5
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Scholl A, Ndoja I, Jiang L. Drosophila Trachea as a Novel Model of COPD. Int J Mol Sci 2021; 22:ijms222312730. [PMID: 34884534 PMCID: PMC8658011 DOI: 10.3390/ijms222312730] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 12/23/2022] Open
Abstract
COPD, a chronic obstructive pulmonary disease, is one of the leading causes of death worldwide. Clinical studies and research in rodent models demonstrated that failure of repair mechanisms to cope with increased ROS and inflammation in the lung leads to COPD. Despite this progress, the molecular mechanisms underlying the development of COPD remain poorly understood, resulting in a lack of effective treatments. Thus, an informative, simple model is highly valued and desired. Recently, the cigarette smoke-induced Drosophila COPD model showed a complex set of pathological phenotypes that resemble those seen in human COPD patients. The Drosophila trachea has been used as a premier model to reveal the mechanisms of tube morphogenesis. The association of these mechanisms to structural changes in COPD can be analyzed by using Drosophila trachea. Additionally, the timeline of structural damage, ROS, and inflammation can be studied in live organisms using fluorescently-tagged proteins. The related function of human COPD genes identified by GWAS can be screened using respective fly homologs. Finally, the Drosophila trachea can be used as a high-throughput drug screening platform to identify novel treatments for COPD. Therefore, Drosophila trachea is an excellent model that is complementary to rodent COPD models.
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6
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Anqueira-González A, Acevedo-Gonzalez JP, Montes-Mercado A, Irizarry-Hernández C, Fuenzalida-Uribe NL, Ghezzi A. Transcriptional Correlates of Chronic Alcohol Neuroadaptation in Drosophila Larvae. Front Behav Neurosci 2021; 15:768694. [PMID: 34803626 PMCID: PMC8599819 DOI: 10.3389/fnbeh.2021.768694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/15/2021] [Indexed: 11/24/2022] Open
Abstract
When presented with the choice, Drosophila melanogaster females will often prefer to lay eggs on food containing a significant amount of alcohol. While, in some cases, this behavioral decision can provide a survival advantage to the developing larvae, it can also lead to developmental and cognitive problems. Alcohol consumption can affect executive functions, episodic memory, and other brain function capacities. However, in the fruit fly, the initial cognitive effects of alcohol consumption have been shown to reverse upon persistent exposure to alcohol. Using an olfactory conditioning assay where an odorant is implemented as a conditioned stimulus and paired with a heat shock as an unconditioned stimulus, a previous study has shown that when exposed to a short acute dose of alcohol, Drosophila larvae can no longer learn this association. Interestingly, upon prolonged chronic alcohol exposure, larvae seem to successfully avoid the conditioned stimulus just as well as control alcohol-naive larvae, suggestive of alcohol-induced neuroadaptations. However, the mechanisms by which Drosophila adapt to the presence of alcohol remains unknown. In this study, we explore the transcriptional correlates of neuroadaptation in Drosophila larvae exposed to chronic alcohol to understand the genetic and cellular components responsible for this adaptation. For this, we employed RNA sequencing technology to evaluate differences in gene expression in the brain of larvae chronically exposed to alcohol. Our results suggest that alcohol-induced neuroadaptations are modulated by a diverse array of synaptic genes within the larval brain through a series of epigenetic modulators.
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Affiliation(s)
- Amanda Anqueira-González
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan, PR, United States
| | - Jenny P Acevedo-Gonzalez
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan, PR, United States
| | - Airined Montes-Mercado
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan, PR, United States
| | | | | | - Alfredo Ghezzi
- Department of Biology, University of Puerto Rico-Río Piedras Campus, San Juan, PR, United States
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7
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Li H, Gao J, Zhang S. Functional and Clinical Characteristics of Cell Adhesion Molecule CADM1 in Cancer. Front Cell Dev Biol 2021; 9:714298. [PMID: 34395444 PMCID: PMC8361327 DOI: 10.3389/fcell.2021.714298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/02/2021] [Indexed: 12/21/2022] Open
Abstract
The cell adhesion molecule CADM1, which participates in cell adhesion and signal transduction, has a regulatory effect on the development of tumors. CADM1 is often involved in malignant tumors of multiple organ systems, such as the respiratory and digestive systems. Upregulated CADM1 promotes tumor cell apoptosis and inhibits malignant proliferation. Along with cell cycle-related proteins, it participates in regulating signaling pathways, such as EMT, STAT3, and AKT, and plays an important role in inhibiting invasion and migration. Considering clinical characteristics, low CADM1 expression is associated with aggressive tumors and poor prognosis. In addition, some long non-coding RNAs (lncRNAs) or miRNAs directly or indirectly act on CADM1 to regulate tumor growth and motility. Interestingly, CADM1 function differs in adult T-cell leukemia/lymphoma (ATLL), and NF-κB is thought to be involved in this process. Taken together, CADM1 could be a potential biomarker for early diagnosis and a target for cancer treatment in future clinical practices.
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Affiliation(s)
- Hongxu Li
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Key Laboratory of Hepatobiliary and Pancreatic Surgery and Digestive Organ Transplantation of Henan Province, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ, Transplantation at Henan Universities, Zhengzhou, China.,Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, China
| | - Jie Gao
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Key Laboratory of Hepatobiliary and Pancreatic Surgery and Digestive Organ Transplantation of Henan Province, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ, Transplantation at Henan Universities, Zhengzhou, China.,Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, China
| | - Shuijun Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Key Laboratory of Hepatobiliary and Pancreatic Surgery and Digestive Organ Transplantation of Henan Province, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ, Transplantation at Henan Universities, Zhengzhou, China.,Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, China
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8
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Alhadyian H, Shoaib D, Ward RE. Septate junction proteins are required for egg elongation and border cell migration during oogenesis in Drosophila. G3-GENES GENOMES GENETICS 2021; 11:6237887. [PMID: 33871584 PMCID: PMC8495938 DOI: 10.1093/g3journal/jkab127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/09/2021] [Indexed: 11/16/2022]
Abstract
Protein components of the invertebrate occluding junction—known as the septate junction (SJ)—are required for morphogenetic developmental events during embryogenesis in Drosophila melanogaster. In order to determine whether SJ proteins are similarly required for morphogenesis during other developmental stages, we investigated the localization and requirement of four representative SJ proteins during oogenesis: Contactin, Macroglobulin complement-related, Neurexin IV, and Coracle. A number of morphogenetic processes occur during oogenesis, including egg elongation, formation of dorsal appendages, and border cell (BC) migration. We found that all four SJ proteins are expressed in egg chambers throughout oogenesis, with the highest and the most sustained levels in the follicular epithelium (FE). In the FE, SJ proteins localize along the lateral membrane during early and mid-oogenesis, but become enriched in an apical-lateral domain (the presumptive SJ) by stage 11. SJ protein relocalization requires the expression of other SJ proteins, as well as Rab5 and Rab11 like SJ biogenesis in the embryo. Knocking down the expression of these SJ proteins in follicle cells throughout oogenesis results in egg elongation defects and abnormal dorsal appendages. Similarly, reducing the expression of SJ genes in the BC cluster results in BC migration defects. Together, these results demonstrate an essential requirement for SJ genes in morphogenesis during oogenesis, and suggest that SJ proteins may have conserved functions in epithelial morphogenesis across developmental stages.
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Affiliation(s)
- Haifa Alhadyian
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
| | - Dania Shoaib
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
| | - Robert E Ward
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
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9
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Rice C, De O, Alhadyian H, Hall S, Ward RE. Expanding the Junction: New Insights into Non-Occluding Roles for Septate Junction Proteins during Development. J Dev Biol 2021; 9:11. [PMID: 33801162 PMCID: PMC8006247 DOI: 10.3390/jdb9010011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 12/17/2022] Open
Abstract
The septate junction (SJ) provides an occluding function for epithelial tissues in invertebrate organisms. This ability to seal the paracellular route between cells allows internal tissues to create unique compartments for organ function and endows the epidermis with a barrier function to restrict the passage of pathogens. Over the past twenty-five years, numerous investigators have identified more than 30 proteins that are required for the formation or maintenance of the SJs in Drosophila melanogaster, and have determined many of the steps involved in the biogenesis of the junction. Along the way, it has become clear that SJ proteins are also required for a number of developmental events that occur throughout the life of the organism. Many of these developmental events occur prior to the formation of the occluding junction, suggesting that SJ proteins possess non-occluding functions. In this review, we will describe the composition of SJs, taking note of which proteins are core components of the junction versus resident or accessory proteins, and the steps involved in the biogenesis of the junction. We will then elaborate on the functions that core SJ proteins likely play outside of their role in forming the occluding junction and describe studies that provide some cell biological perspectives that are beginning to provide mechanistic understanding of how these proteins function in developmental contexts.
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Affiliation(s)
- Clinton Rice
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA; (C.R.); (H.A.)
| | - Oindrila De
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA;
| | - Haifa Alhadyian
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA; (C.R.); (H.A.)
| | | | - Robert E. Ward
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA;
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10
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Khoury S, Wang QP, Parisien M, Gris P, Bortsov AV, Linnstaedt SD, McLean SA, Tungate AS, Sofer T, Lee J, Louie T, Redline S, Kaunisto MA, Kalso EA, Munter HM, Nackley AG, Slade GD, Smith SB, Zaykin DV, Fillingim RB, Ohrbach R, Greenspan JD, Maixner W, Neely GG, Diatchenko L. Multi-ethnic GWAS and meta-analysis of sleep quality identify MPP6 as a novel gene that functions in sleep center neurons. Sleep 2021; 44:zsaa211. [PMID: 33034629 PMCID: PMC7953222 DOI: 10.1093/sleep/zsaa211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 08/28/2020] [Indexed: 11/14/2022] Open
Abstract
Poor sleep quality can have harmful health consequences. Although many aspects of sleep are heritable, the understandings of genetic factors involved in its physiology remain limited. Here, we performed a genome-wide association study (GWAS) using the Pittsburgh Sleep Quality Index (PSQI) in a multi-ethnic discovery cohort (n = 2868) and found two novel genome-wide loci on chromosomes 2 and 7 associated with global sleep quality. A meta-analysis in 12 independent cohorts (100 000 individuals) replicated the association on chromosome 7 between NPY and MPP6. While NPY is an important sleep gene, we tested for an independent functional role of MPP6. Expression data showed an association of this locus with both NPY and MPP6 mRNA levels in brain tissues. Moreover, knockdown of an orthologue of MPP6 in Drosophila melanogaster sleep center neurons resulted in decreased sleep duration. With convergent evidence, we describe a new locus impacting human variability in sleep quality through known NPY and novel MPP6 sleep genes.
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Affiliation(s)
- Samar Khoury
- The Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC, Canada
| | - Qiao-Ping Wang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Marc Parisien
- The Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC, Canada
| | - Pavel Gris
- The Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC, Canada
| | - Andrey V Bortsov
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University, Durham, NC
| | - Sarah D Linnstaedt
- Institute for Trauma Recovery and Department of Anesthesiology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Samuel A McLean
- Institute for Trauma Recovery and Department of Anesthesiology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Andrew S Tungate
- Institute for Trauma Recovery and Department of Anesthesiology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Tamar Sofer
- Department of Medicine, Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Jiwon Lee
- Department of Medicine, Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Tin Louie
- Department of Biostatistics, University of Washington, Seattle, WA
| | - Susan Redline
- Department of Medicine, Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Mari Anneli Kaunisto
- Department of Diagnostics and Therapeutics, University of Helsinki, Helsinki, Finland
| | - Eija A Kalso
- Department of Diagnostics and Therapeutics, University of Helsinki, Helsinki, Finland
| | | | - Andrea G Nackley
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University, Durham, NC
| | - Gary D Slade
- School of dentistry, University of North Carolina Chapel Hill, Chapel Hill, NC
| | - Shad B Smith
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University, Durham, NC
| | - Dmitri V Zaykin
- Biostatistics and Computational Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC
| | | | - Richard Ohrbach
- Department of Oral Diagnostic Services, University at Buffalo, Buffalo, NY
| | - Joel D Greenspan
- Department of Neural and Pain Sciences, Brotman Facial Pain Clinic, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD
| | - William Maixner
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University, Durham, NC
| | - G Gregory Neely
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life & Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Luda Diatchenko
- The Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC, Canada
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11
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Rouka E, Gourgoulianni N, Lüpold S, Hatzoglou C, Gourgoulianis K, Blanckenhorn WU, Zarogiannis SG. The Drosophila septate junctions beyond barrier function: Review of the literature, prediction of human orthologs of the SJ-related proteins and identification of protein domain families. Acta Physiol (Oxf) 2021; 231:e13527. [PMID: 32603029 DOI: 10.1111/apha.13527] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 12/20/2022]
Abstract
The involvement of Septate Junctions (SJs) in critical cellular functions that extend beyond their role as diffusion barriers in the epithelia and the nervous system has made the fruit fly an ideal model for the study of human diseases associated with impaired Tight Junction (TJ) function. In this study, we summarized current knowledge of the Drosophila melanogaster SJ-related proteins, focusing on their unconventional functions. Additionally, we sought to identify human orthologs of the corresponding genes as well as protein domain families. The systematic literature search was performed in PubMed and Scopus databases using relevant key terms. Orthologs were predicted using the DIOPT tool and aligned protein regions were determined from the Pfam database. 3-D models of the smooth SJ proteins were built on the Phyre2 and DMPFold protein structure prediction servers. A total of 30 proteins were identified as relatives to the SJ cellular structure. Key roles of these proteins, mainly in the regulation of morphogenetic events and cellular signalling, were highlighted. The investigation of protein domain families revealed that the SJ-related proteins contain conserved domains that are required not only for cell-cell interactions and cell polarity but also for cellular signalling and immunity. DIOPT analysis of orthologs identified novel human genes as putative functional homologs of the fruit fly SJ genes. A gap in our knowledge was identified regarding the domains that occur in the proteins encoded by eight SJ-associated genes. Future investigation of these domains is needed to provide functional information.
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Affiliation(s)
- Erasmia Rouka
- Department of Physiology Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
| | - Natalia Gourgoulianni
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Chrissi Hatzoglou
- Department of Physiology Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
- Department of Respiratory Medicine Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
| | - Konstantinos Gourgoulianis
- Department of Respiratory Medicine Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
| | - Wolf U. Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Sotirios G. Zarogiannis
- Department of Physiology Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
- Department of Respiratory Medicine Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
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12
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Pannen H, Rapp T, Klein T. The ESCRT machinery regulates retromer-dependent transcytosis of septate junction components in Drosophila. eLife 2020; 9:61866. [PMID: 33377869 PMCID: PMC7848756 DOI: 10.7554/elife.61866] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/29/2020] [Indexed: 12/30/2022] Open
Abstract
Loss of ESCRT function in Drosophila imaginal discs is known to cause neoplastic overgrowth fueled by mis-regulation of signaling pathways. Its impact on junctional integrity, however, remains obscure. To dissect the events leading to neoplasia, we used transmission electron microscopy (TEM) on wing imaginal discs temporally depleted of the ESCRT-III core component Shrub. We find a specific requirement for Shrub in maintaining septate junction (SJ) integrity by transporting the claudin Megatrachea (Mega) to the SJ. In absence of Shrub function, Mega is lost from the SJ and becomes trapped on endosomes coated with the endosomal retrieval machinery retromer. We show that ESCRT function is required for apical localization and mobility of retromer positive carrier vesicles, which mediate the biosynthetic delivery of Mega to the SJ. Accordingly, loss of retromer function impairs the anterograde transport of several SJ core components, revealing a novel physiological role for this ancient endosomal agent. Proteins are large molecules responsible for a variety of activities that cells needs to perform to survive; from respiration to copying DNA before cells divide. To perform these roles proteins need to be transported to the correct cell compartment, or to the cell membrane. This protein trafficking depends on the endosomal system, a set of membrane compartments that can travel within the cell and act as a protein sorting hub. This system needs its own proteins to work properly. In particular, there are two sets of proteins that are crucial for the endosomal systems activity: a group of proteins known as the ESCRT (endosomal sorting complex required for transport) machinery and a complex called retromer. The retromer complex regulates recycling of receptor proteins so they can be reused, while the ESCRT machinery mediates degradation of proteins that the cell does not require anymore. In the epithelia of fruit fly larvae – the tissues that form layers of cells, usually covering an organ but also making structures like wings – defects in ESCRT activity lead to a loss of tissue integrity. This loss of tissue integrity suggests that the endosomal system might be involved in transporting proteins that form cellular junctions, the multiprotein complexes that establish contacts between cells or between a cell and the extracellular space. In arthropods such as the fruit fly, the adherens junction and the septate junction are two types of cellular junctions important for the integrity of epithelia integrity. Adherens junctions allow cells to adhere to each other, while septate junctions stop nutrient molecules, ions and water from leaking into the tissue. The role of the endosomal system in trafficking the proteins that form septate junctions remains a mystery. To better understand the role of the endosomal system in regulating cell junctions and tissue integrity, Pannen et al. blocked the activity of either the ESCRT or retromer in wing imaginal discs – the future wings – of fruit fly larvae. Pannen et al. then analyzed the effects of these endosomal defects on cellular junctions using an imaging technique called transmission electron microscopy. The results showed that both ESCRT and retromer activities are necessary for the correct delivery of septate junction components to the cell membrane. However, neither retromer nor ESCRT were required for the delivery of adherens junction proteins. These findings shed light on how retromer and the ESCRT machinery are involved in the epithelial tissue integrity of fruit fly larvae through their effects on cell junctions. Humans have their own versions of the ESCRT, retromer, and cell junction proteins, all of which are very similar to their fly counterparts. Since defects in the human versions of these proteins have been associated with a variety of diseases, from infections to cancer, these results may have implications for research into treating those diseases.
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Affiliation(s)
- Hendrik Pannen
- Institute of Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Tim Rapp
- Institute of Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Thomas Klein
- Institute of Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
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13
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Finegan TM, Bergstralh DT. Neuronal immunoglobulin superfamily cell adhesion molecules in epithelial morphogenesis: insights from Drosophila. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190553. [PMID: 32829687 PMCID: PMC7482216 DOI: 10.1098/rstb.2019.0553] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2020] [Indexed: 12/25/2022] Open
Abstract
In this review, we address the function of immunoglobulin superfamily cell adhesion molecules (IgCAMs) in epithelia. Work in the Drosophila model system in particular has revealed novel roles for calcium-independent adhesion molecules in the morphogenesis of epithelial tissues. We review the molecular composition of lateral junctions with a focus on their IgCAM components and reconsider the functional roles of epithelial lateral junctions. The epithelial IgCAMs discussed in this review have well-defined roles in the nervous system, particularly in the process of axon guidance, suggesting functional overlap and conservation in mechanism between that process and epithelial remodelling. We expand on the hypothesis that epithelial occluding junctions and synaptic junctions are compositionally equivalent and present a novel hypothesis that the mechanism of epithelial cell (re)integration and synaptic junction formation are shared. We highlight the importance of considering non-cadherin-based adhesion in our understanding of the mechanics of epithelial tissues and raise questions to direct future work. This article is part of the discussion meeting issue 'Contemporary morphogenesis'.
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14
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Königsmann T, Parfentev I, Urlaub H, Riedel D, Schuh R. The bicistronic gene würmchen encodes two essential components for epithelial development in Drosophila. Dev Biol 2020; 463:53-62. [PMID: 32361005 DOI: 10.1016/j.ydbio.2020.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/17/2020] [Accepted: 04/07/2020] [Indexed: 11/24/2022]
Abstract
Epithelial tissues are fundamental for the establishment and maintenance of different body compartments in multicellular animals. To achieve this specific task epithelial sheets secrete an apical extracellular matrix for tissue strength and protection and they organize a transepithelial barrier function, which is mediated by tight junctions in vertebrates or septate junctions in invertebrates. Here, we show that the bicistronic gene würmchen is functionally expressed in epithelial tissues. CRISPR/Cas9-mediated mutations in both coding sequences reveal two essential polypeptides, Würmchen1 and Würmchen2, which are both necessary for normal epithelial tissue development. Würmchen1 represents a genuine septate junction core component. It is required during embryogenesis for septate junction organization, the establishment of a transepithelial barrier function, distinct cellular transport processes and tracheal system morphogenesis. Würmchen2 is localized in the apical membrane region of epithelial tissues and in a central core of the tracheal lumen during embryogenesis. It is essential during the later larval development.
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Affiliation(s)
- Tatiana Königsmann
- Research Group Molecular Organogenesis, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, D-37077, Göttingen, Germany
| | - Iwan Parfentev
- Research Group Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, D-37077, Göttingen, Germany
| | - Henning Urlaub
- Research Group Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, D-37077, Göttingen, Germany; Bioanalytics, Institute for Clinical Chemistry, University Medical Center, Robert-Koch-Strasse 420, 37075 Göttingen, Germany
| | - Dietmar Riedel
- Electron Microscopy Group, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, D-37077, Göttingen, Germany
| | - Reinhard Schuh
- Research Group Molecular Organogenesis, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, D-37077, Göttingen, Germany.
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15
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Molecular organization and function of vertebrate septate-like junctions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183211. [PMID: 32032590 DOI: 10.1016/j.bbamem.2020.183211] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/22/2020] [Accepted: 01/26/2020] [Indexed: 12/21/2022]
Abstract
Septate-like junctions display characteristic ladder-like ultrastructure reminiscent of the invertebrate epithelial septate junctions and are present at the paranodes of myelinated axons. The paranodal junctions where the myelin loops attach to the axon at the borders of the node of Ranvier provide both a paracellular barrier to ion diffusion and a lateral fence along the axonal membrane. The septate-like junctions constrain the proper distribution of nodal Na+ channels and juxtaparanodal K+ channels, which are required for the safe propagation of the nerve influx and rapid saltatory conduction. The paranodal cell adhesion molecules have been identified as target antigens in peripheral demyelinating autoimmune diseases and the pathogenic mechanisms described. This review aims at presenting the recent knowledge on the molecular and structural organization of septate-like junctions, their formation and stabilization during development, and how they are involved in demyelinating diseases.
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16
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Scholl A, O'Brien MJ, Chandran RR, Jiang L. The novel gene
apnoia
regulates
Drosophila
tracheal tube size. Dev Dyn 2019; 248:477-487. [DOI: 10.1002/dvdy.29] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 03/06/2019] [Accepted: 03/09/2019] [Indexed: 12/19/2022] Open
Affiliation(s)
- Aaron Scholl
- Department of Biological SciencesOakland University Rochester Michigan
| | | | | | - Lan Jiang
- Department of Biological SciencesOakland University Rochester Michigan
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17
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Petri J, Syed MH, Rey S, Klämbt C. Non-Cell-Autonomous Function of the GPI-Anchored Protein Undicht during Septate Junction Assembly. Cell Rep 2019; 26:1641-1653.e4. [DOI: 10.1016/j.celrep.2019.01.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/12/2018] [Accepted: 01/10/2019] [Indexed: 11/26/2022] Open
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18
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Chandran RR, Scholl A, Yang Y, Jiang L. rebuff regulates apical luminal matrix to control tube size in Drosophila trachea. Biol Open 2018; 7:7/9/bio036848. [PMID: 30185423 PMCID: PMC6176944 DOI: 10.1242/bio.036848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Drosophila embryonic tracheal network is an excellent model to study tube size. The chitin-based apical luminal matrix and cell polarity are well known to regulate tube size in Drosophila trachea. Defects in luminal matrix and cell polarity lead to tube overexpansion. Here, we address the novel function of the rebuff (reb) gene, which encodes an evolutionarily conserved Smad-like protein. In reb mutants, tracheal tubes are moderately over-elongated. Despite the establishment of normal cell polarity, we observed significantly reduced apical luminal matrix in reb mutants. Among various luminal components, luminal Obstructor-A (ObstA) is drastically reduced. Interestingly, ObstA is localized in vesicle-like structures that are apically concentrated in reb mutants. To investigate the possibility that reb is involved in the endocytosis of ObstA, we analyzed the co-localization of ObstA and endocytic markers in reb mutants. We observed that ObstA is localized in late endosomes and recycling endosomes. This suggests that in reb mutant trachea, endocytosed ObstA is degraded or recycled back to the apical region. However, ObstA vesicles are retained in the apical region and are failed to be secreted to the lumen. Taken together, these results suggest one function of reb is regulating the endocytosis of luminal matrix components. Summary: Novel function of Smad-like protein Rebuff in regulating tube size of Drosophila trachea through endocytosis of luminal matrix components.
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Affiliation(s)
- Rachana R Chandran
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
| | - Aaron Scholl
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
| | - Yuyang Yang
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
| | - Lan Jiang
- Department of Biological Sciences, Oakland University, 2200 N. Squirrel Road, Rochester, MI 48309, USA
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19
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Saito Y, Desai RR, Muthuswamy SK. Reinterpreting polarity and cancer: The changing landscape from tumor suppression to tumor promotion. Biochim Biophys Acta Rev Cancer 2018; 1869:103-116. [DOI: 10.1016/j.bbcan.2017.12.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 12/21/2022]
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20
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Scholl A, Yang Y, McBride P, Irwin K, Jiang L. Tracheal expression of Osiris gene family in Drosophila. Gene Expr Patterns 2018; 28:87-94. [PMID: 29548969 DOI: 10.1016/j.gep.2018.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/25/2018] [Accepted: 03/02/2018] [Indexed: 11/25/2022]
Abstract
The Drosophila trachea is a premier genetic system to investigate the fundamental mechanisms of tubular organ formation. Development of the trachea consists of the well understood early branch specification and migration processes, and the less clear later branch maturation process including the apical membrane expansion, cytoskeleton rearrangement, luminal matrix clearance, and air-filling. We identified seven members of the Osiris (Osi) gene family with obvious tracheal expression in Drosophila. In addition, HA-tagged Osi proteins are highly concentrated in vesicle-like structures at and near the apical membrane. Osi proteins are predicted to contain endocytic signals and transmembrane domains. The localization of Osi proteins is consistent with these predictions. Interestingly, the Drosophila tracheal tube maturation process also occurs at the apical membrane. Taken together, the localization of Osi proteins suggest that these proteins are likely involved in tube maturation through vesicular trafficking or interacting with other apical membrane proteins.
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Affiliation(s)
- Aaron Scholl
- Department of Biological Sciences, Oakland University, USA
| | - Yuyang Yang
- Department of Biological Sciences, Oakland University, USA
| | | | - Kelly Irwin
- Department of Biological Sciences, Oakland University, USA
| | - Lan Jiang
- Department of Biological Sciences, Oakland University, USA.
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21
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Wu VM, Uskoković V. Population Effects of Calcium Phosphate Nanoparticles in Drosophila melanogaster: The Effects of Phase Composition, Crystallinity, and the Pathway of Formation. ACS Biomater Sci Eng 2017; 3:2348-2357. [PMID: 29862315 PMCID: PMC5978735 DOI: 10.1021/acsbiomaterials.7b00540] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Unpredictable biological response due to the finest nanostructural variations is one of the hallmarks of nanoparticles. Because of this erratic behavior of nanoparticles in living systems, thorough analyses of biosafety must precede the analyses of the pharmacotherapeutic efficacy and simple animal models are ideal for such purposes. Drosophila melanogaster, the common fruit fly, is an animal model capable of giving a fast, high-throughput response as to the safety and efficacy of drug delivery carriers and other pharmacological agents, while minimizing the suffering imposed onto animals in more complex in vivo models. Here we studied the effects on the viability and fertility of D. melanogaster due to variations in phase composition, crystallinity, and the pathway of formation of four different calcium phosphate (CP) nanopowders consumed orally. To minimize the effect of other nanostructural variables, CP nanopowders were made to possess highly similar particle sizes and morphologies. The composition of CP affected the fecundity of flies, but so did crystallinity and the pathway of formation. Both the total number of eclosed viable flies and pupae in populations challenged with hydroxyapatite (HAP) greatly exceeded those in control populations. Viability was adversely affected by the only pyrophosphate tested (CPP) and by the metastable and the most active of all CP nanopowders analyzed: the amorphous CP (ACP). The pupation peak was delayed and the viable fly to-pupa ratio increased in all the CP-challenged populations. F1 CPP population, whose viability was most adversely affected by the CP consumption, when crossed, produced the largest number of F2 progeny under regular conditions, possibly pointing to stress as a positive evolutionary drive. The positive effect of HAP on fertility of fruit flies may be due to its slow absorption and the activation of calmodulin during the transit of oocytes through the reproductive tract of fertilized females. Exerted in the prepupation stage, the effect of CP is thus traceable beyond the instar larval stage and to the oogenesis stage of the Drosophila lifecycle.
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Affiliation(s)
- Victoria M. Wu
- Advanced Materials and Nanobiotechnology Laboratory, Department of Biomedical and Pharmaceutical Sciences, Center for Targeted Drug Delivery, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, California 92618-1908, United States
- Advanced Materials and Nanobiotechnology Laboratory, Department of Bioengineering, University of Illinois, 851 South Morgan Street, Chicago, Illinois 60607-7052, United States
| | - Vuk Uskoković
- Advanced Materials and Nanobiotechnology Laboratory, Department of Biomedical and Pharmaceutical Sciences, Center for Targeted Drug Delivery, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, California 92618-1908, United States
- Advanced Materials and Nanobiotechnology Laboratory, Department of Bioengineering, University of Illinois, 851 South Morgan Street, Chicago, Illinois 60607-7052, United States
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22
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Tempesta C, Hijazi A, Moussian B, Roch F. Boudin trafficking reveals the dynamic internalisation of specific septate junction components in Drosophila. PLoS One 2017; 12:e0185897. [PMID: 28977027 PMCID: PMC5627947 DOI: 10.1371/journal.pone.0185897] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/21/2017] [Indexed: 11/18/2022] Open
Abstract
The maintenance of paracellular barriers in invertebrate epithelia depends on the integrity of specific cell adhesion structures known as septate junctions (SJ). Multiple studies in Drosophila have revealed that these junctions have a stereotyped architecture resulting from the association in the lateral membrane of a large number of components. However, little is known about the dynamic organisation adopted by these multi-protein complexes in living tissues. We have used live imaging techniques to show that the Ly6 protein Boudin is a component of these adhesion junctions and can diffuse systemically to associate with the SJ of distant cells. We also observe that this protein and the claudin Kune-kune are endocytosed in epidermal cells during embryogenesis. Our data reveal that the SJ contain a set of components exhibiting a high membrane turnover, a feature that could contribute in a tissue-specific manner to the morphogenetic plasticity of these adhesion structures.
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Affiliation(s)
- Camille Tempesta
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Assia Hijazi
- Lebanese University, Faculty of Sciences I and V—Doctorate School of Science and Technology-PRASE, Campus Rafic Hariri, Hadath-Beirut, Lebanon
| | - Bernard Moussian
- University of Tübingen, Interfaculty Institute of Cell Biology, Section Animal Genetics, Tübingen, Germany
| | - Fernando Roch
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
- * E-mail:
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23
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Varicose and cheerio collaborate with pebble to mediate semaphorin-1a reverse signaling in Drosophila. Proc Natl Acad Sci U S A 2017; 114:E8254-E8263. [PMID: 28894005 DOI: 10.1073/pnas.1713010114] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transmembrane semaphorin Sema-1a acts as both a ligand and a receptor to regulate axon-axon repulsion during neural development. Pebble (Pbl), a Rho guanine nucleotide exchange factor, mediates Sema-1a reverse signaling through association with the N-terminal region of the Sema-1a intracellular domain (ICD), resulting in cytoskeletal reorganization. Here, we uncover two additional Sema-1a interacting proteins, varicose (Vari) and cheerio (Cher), each with neuronal functions required for motor axon pathfinding. Vari is a member of the membrane-associated guanylate kinase (MAGUK) family of proteins, members of which can serve as scaffolds to organize signaling complexes. Cher is related to actin filament cross-linking proteins that regulate actin cytoskeleton dynamics. The PDZ domain binding motif found in the most C-terminal region of the Sema-1a ICD is necessary for interaction with Vari, but not Cher, indicative of distinct binding modalities. Pbl/Sema-1a-mediated repulsive guidance is potentiated by both vari and cher Genetic analyses further suggest that scaffolding functions of Vari and Cher play an important role in Pbl-mediated Sema-1a reverse signaling. These results define intracellular components critical for signal transduction from the Sema-1a receptor to the cytoskeleton and provide insight into mechanisms underlying semaphorin-induced localized changes in cytoskeletal organization.
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24
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Pinatel D, Hivert B, Saint-Martin M, Noraz N, Savvaki M, Karagogeos D, Faivre-Sarrailh C. The Kv1-associated molecules TAG-1 and Caspr2 are selectively targeted to the axon initial segment in hippocampal neurons. J Cell Sci 2017; 130:2209-2220. [PMID: 28533267 DOI: 10.1242/jcs.202267] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/18/2017] [Indexed: 12/28/2022] Open
Abstract
Caspr2 and TAG-1 (also known as CNTNAP2 and CNTN2, respectively) are cell adhesion molecules (CAMs) associated with the voltage-gated potassium channels Kv1.1 and Kv1.2 (also known as KCNA1 and KCNA2, respectively) at regions controlling axonal excitability, namely, the axon initial segment (AIS) and juxtaparanodes of myelinated axons. The distribution of Kv1 at juxtaparanodes requires axo-glial contacts mediated by Caspr2 and TAG-1. In the present study, we found that TAG-1 strongly colocalizes with Kv1.2 at the AIS of cultured hippocampal neurons, whereas Caspr2 is uniformly expressed along the axolemma. Live-cell imaging revealed that Caspr2 and TAG-1 are sorted together in axonal transport vesicles. Therefore, their differential distribution may result from diffusion and trapping mechanisms induced by selective partnerships. By using deletion constructs, we identified two molecular determinants of Caspr2 that regulate its axonal positioning. First, the LNG2-EGF1 modules in the ectodomain of Caspr2, which are involved in its axonal distribution. Deletion of these modules promotes AIS localization and association with TAG-1. Second, the cytoplasmic PDZ-binding site of Caspr2, which could elicit AIS enrichment and recruitment of the membrane-associated guanylate kinase (MAGuK) protein MPP2. Hence, the selective distribution of Caspr2 and TAG-1 may be regulated, allowing them to modulate the strategic function of the Kv1 complex along axons.
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Affiliation(s)
- Delphine Pinatel
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR7286, Marseille, France
| | - Bruno Hivert
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR7286, Marseille, France
| | - Margaux Saint-Martin
- Institut Neuromyogène, CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Nelly Noraz
- Institut Neuromyogène, CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Maria Savvaki
- Department of Basic Sciences, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, University of Crete, Heraklion, Greece
| | - Domna Karagogeos
- Department of Basic Sciences, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, University of Crete, Heraklion, Greece
| | - Catherine Faivre-Sarrailh
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR7286, Marseille, France
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25
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Septate Junction Proteins Play Essential Roles in Morphogenesis Throughout Embryonic Development in Drosophila. G3-GENES GENOMES GENETICS 2016; 6:2375-84. [PMID: 27261004 PMCID: PMC4978892 DOI: 10.1534/g3.116.031427] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The septate junction (SJ) is the occluding junction found in the ectodermal epithelia of invertebrate organisms, and is essential to maintain chemically distinct compartments in epithelial organs, to provide the blood–brain barrier in the nervous system, and to provide an important line of defense against invading pathogens. More than 20 genes have been identified to function in the establishment or maintenance of SJs in Drosophila melanogaster. Numerous studies have demonstrated the cell biological function of these proteins in establishing the occluding junction, whereas very few studies have examined further developmental roles for them. Here we examined embryos with mutations in nine different core SJ genes and found that all nine result in defects in embryonic development as early as germ band retraction, with the most penetrant defect observed in head involution. SJ genes are also required for cell shape changes and cell rearrangements that drive the elongation of the salivary gland during midembryogenesis. Interestingly, these developmental events occur at a time prior to the formation of the occluding junction, when SJ proteins localize along the lateral membrane and have not yet coalesced into the region of the SJ. Together, these observations reveal an underappreciated role for a large group of SJ genes in essential developmental events during embryogenesis, and suggest that the function of these proteins in facilitating cell shape changes and rearrangements is independent of their role in the occluding junction.
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26
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Zihni C, Mills C, Matter K, Balda MS. Tight junctions: from simple barriers to multifunctional molecular gates. Nat Rev Mol Cell Biol 2016; 17:564-80. [PMID: 27353478 DOI: 10.1038/nrm.2016.80] [Citation(s) in RCA: 994] [Impact Index Per Article: 110.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epithelia and endothelia separate different tissue compartments and protect multicellular organisms from the outside world. This requires the formation of tight junctions, selective gates that control paracellular diffusion of ions and solutes. Tight junctions also form the border between the apical and basolateral plasma-membrane domains and are linked to the machinery that controls apicobasal polarization. Additionally, signalling networks that guide diverse cell behaviours and functions are connected to tight junctions, transmitting information to and from the cytoskeleton, nucleus and different cell adhesion complexes. Recent advances have broadened our understanding of the molecular architecture and cellular functions of tight junctions.
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Affiliation(s)
- Ceniz Zihni
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
| | - Clare Mills
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
| | - Karl Matter
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
| | - Maria S Balda
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
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27
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Sollier K, Gaudé HM, Chartier FJM, Laprise P. Rac1 controls epithelial tube length through the apical secretion and polarity pathways. Biol Open 2015; 5:49-54. [PMID: 26700724 PMCID: PMC4728308 DOI: 10.1242/bio.015727] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The morphometric parameters of epithelial tubes are critical to the physiology and homeostasis of most organs. In addition, many human diseases are associated with tube-size defects. Here, we show that Rac1 limits epithelial tube elongation in the developing fly trachea by promoting Rab5-dependent endocytosis of the apical determinant Crumbs. Rac1 is also involved in a positive feedback loop with the septate junction protein Coracle. Thereby, Rac1 precludes paracellular diffusion and contributes to the septate junction-dependent secretion of the chitin-modifying enzymes Vermiform and Serpentine, which restrict epithelial tube length independently of Crumbs. Thus, Rac1 is a critical component of two important pathways controlling epithelial tube morphogenesis. Summary: Epithelial tube size regulation sustains organ physiology. Rac1 limits tube elongation in the fly trachea through restriction of apical membrane growth, and by supporting luminal secretion of chitin modifying enzymes.
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Affiliation(s)
- Kévin Sollier
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada Centre de recherche sur le cancer, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada CRCHU de Québec, axe oncologie, 9 McMahon, Québec, Québec G1R 3S3,Canada
| | - Helori-Mael Gaudé
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada Centre de recherche sur le cancer, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada CRCHU de Québec, axe oncologie, 9 McMahon, Québec, Québec G1R 3S3,Canada
| | - François J-M Chartier
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada Centre de recherche sur le cancer, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada CRCHU de Québec, axe oncologie, 9 McMahon, Québec, Québec G1R 3S3,Canada
| | - Patrick Laprise
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada Centre de recherche sur le cancer, Université Laval, 9 McMahon, Québec, Québec G1R 3S3, Canada CRCHU de Québec, axe oncologie, 9 McMahon, Québec, Québec G1R 3S3,Canada
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Deligiannaki M, Casper AL, Jung C, Gaul U. Pasiflora proteins are novel core components of the septate junction. Development 2015; 142:3046-57. [PMID: 26329602 PMCID: PMC4582180 DOI: 10.1242/dev.119412] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Epithelial sheets play essential roles as selective barriers insulating the body from the environment and establishing distinct chemical compartments within it. In invertebrate epithelia, septate junctions (SJs) consist of large multi-protein complexes that localize at the apicolateral membrane and mediate barrier function. Here, we report the identification of two novel SJ components, Pasiflora1 and Pasiflora2, through a genome-wide glial RNAi screen in Drosophila. Pasiflora mutants show permeable blood-brain and tracheal barriers, overelongated tracheal tubes and mislocalization of SJ proteins. Consistent with the observed phenotypes, the genes are co-expressed in embryonic epithelia and glia and are required cell-autonomously to exert their function. Pasiflora1 and Pasiflora2 belong to a previously uncharacterized family of tetraspan membrane proteins conserved across the protostome-deuterostome divide. Both proteins localize at SJs and their apicolateral membrane accumulation depends on other complex components. In fluorescence recovery after photobleaching experiments we demonstrate that pasiflora proteins are core SJ components as they are required for complex formation and exhibit restricted mobility within the membrane of wild-type epithelial cells, but rapid diffusion in cells with disrupted SJs. Taken together, our results show that Pasiflora1 and Pasiflora2 are novel integral components of the SJ and implicate a new family of tetraspan proteins in the function of these ancient and crucial cell junctions.
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Affiliation(s)
- Myrto Deligiannaki
- Gene Center, Department of Biochemistry, Center of Protein Science CIPSM, Ludwigs-Maximilians University, Feodor-Lynen-Str. 25, Munich 81377, Germany
| | - Abbie L Casper
- Gene Center, Department of Biochemistry, Center of Protein Science CIPSM, Ludwigs-Maximilians University, Feodor-Lynen-Str. 25, Munich 81377, Germany
| | - Christophe Jung
- Gene Center, Department of Biochemistry, Center of Protein Science CIPSM, Ludwigs-Maximilians University, Feodor-Lynen-Str. 25, Munich 81377, Germany
| | - Ulrike Gaul
- Gene Center, Department of Biochemistry, Center of Protein Science CIPSM, Ludwigs-Maximilians University, Feodor-Lynen-Str. 25, Munich 81377, Germany
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29
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Yoneshige A, Hagiyama M, Fujita M, Ito A. Pathogenic Actions of Cell Adhesion Molecule 1 in Pulmonary Emphysema and Atopic Dermatitis. Front Cell Dev Biol 2015; 3:75. [PMID: 26636084 PMCID: PMC4653308 DOI: 10.3389/fcell.2015.00075] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/09/2015] [Indexed: 12/27/2022] Open
Abstract
Cell adhesion mediated by adhesion molecules is of central importance in the maintenance of tissue homeostasis. Therefore, altered expression of adhesion molecules leads to the development of various tissue disorders involving cell activation, degeneration, and apoptosis. Nevertheless, it still remains unclear what initiates the altered expression of adhesion molecules and how the subsequent pathological cascades proceed. In this regard, cell adhesion molecule 1 (CADM1) is one of the candidates that is involved in the development of pathological lesions; it is an intercellular adhesion molecule that is expressed in various types of cells such as pulmonary cells, neurons, and mast cells. Recent studies have revealed that alterations in the transcriptional or post-transcriptional expressions of CADM1 correlate with the pathogenesis of pulmonary diseases and allergic diseases. In this review, we specifically focus on how CADM1 is involved in the development of pathological lesions in pulmonary emphysema and atopic dermatitis.
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Affiliation(s)
- Azusa Yoneshige
- Department of Pathology, Faculty of Medicine, Kinki University Osaka, Japan
| | - Man Hagiyama
- Department of Pathology, Faculty of Medicine, Kinki University Osaka, Japan
| | - Mitsugu Fujita
- Department of Microbiology, Faculty of Medicine, Kinki University Osaka, Japan
| | - Akihiko Ito
- Department of Pathology, Faculty of Medicine, Kinki University Osaka, Japan
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30
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Occluding junctions of invertebrate epithelia. J Comp Physiol B 2015; 186:17-43. [DOI: 10.1007/s00360-015-0937-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/12/2015] [Accepted: 09/22/2015] [Indexed: 01/30/2023]
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31
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Immunohistochemical study of the membrane skeletal protein, membrane protein palmitoylated 6 (MPP6), in the mouse small intestine. Histochem Cell Biol 2015; 145:81-92. [PMID: 26496923 DOI: 10.1007/s00418-015-1374-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2015] [Indexed: 12/14/2022]
Abstract
The membrane protein palmitoylated (MPP) family belongs to the membrane-associated guanylate kinase (MAGUK) family. MPP1 interacts with the protein 4.1 family member, 4.1R, as a membrane skeletal protein complex in erythrocytes. We previously described the interaction of another MPP family, MPP6, with 4.1G in the mouse peripheral nervous system. In the present study, the immunolocalization of MPP6 in the mouse small intestine was examined and compared with that of E-cadherin, zonula occludens (ZO)-1, and 4.1B, which we previously investigated in intestinal epithelial cells. The immunolocalization of MPP6 was also assessed in the small intestines of 4.1B-deficient (-/-) mice. In the small intestine, Western blotting revealed that the molecular weight of MPP6 was approximately 55-kDa, and MPP6 was immunostained under the cell membranes in the basolateral portions of almost all epithelial cells from the crypts to the villi. The immunostaining pattern of MPP6 in epithelial cells was similar to that of E-cadherin, but differed from that of ZO-1. In intestinal epithelial cells, the immunostained area of MPP6 was slightly different from that of 4.1B, which was restricted to the intestinal villi. The immunolocalization of MPP6 in small intestinal epithelial cells was similar between 4.1B(-/-) mice and 4.1B(+/+) mice. In the immunoprecipitation study, another MAGUK family protein, calcium/calmodulin-dependent serine protein kinase (CASK), was shown to molecularly interact with MPP6. Thus, we herein showed the immunolocalization and interaction proteins of MPP6 in the mouse small intestine, and also that 4.1B in epithelial cells was not essential for the sorting of MPP6.
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32
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Dong B, Hayashi S. Shaping of biological tubes by mechanical interaction of cell and extracellular matrix. Curr Opin Genet Dev 2015; 32:129-34. [DOI: 10.1016/j.gde.2015.02.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Revised: 02/14/2015] [Accepted: 02/21/2015] [Indexed: 01/19/2023]
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33
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Bark beetle controls epithelial morphogenesis by septate junction maturation in Drosophila. Dev Biol 2015; 400:237-47. [DOI: 10.1016/j.ydbio.2015.02.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/04/2015] [Accepted: 02/11/2015] [Indexed: 12/18/2022]
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34
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Dobson AJ, Chaston JM, Newell PD, Donahue L, Hermann SL, Sannino DR, Westmiller S, Wong ACN, Clark AG, Lazzaro BP, Douglas AE. Host genetic determinants of microbiota-dependent nutrition revealed by genome-wide analysis of Drosophila melanogaster. Nat Commun 2015; 6:6312. [PMID: 25692519 PMCID: PMC4333721 DOI: 10.1038/ncomms7312] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/16/2015] [Indexed: 01/03/2023] Open
Abstract
Animals bear communities of gut microorganisms with substantial effects on animal nutrition, but the host genetic basis of these effects is unknown. Here, we use Drosophila to demonstrate substantial among-genotype variation in the effects of eliminating the gut microbiota on five host nutritional indices (weight, and protein, lipid, glucose and glycogen contents); this includes variation in both the magnitude and direction of microbiota-dependent effects. Genome-wide associations to identify the genetic basis of the microbiota-dependent variation reveal polymorphisms in largely non-overlapping sets of genes associated with variation in the nutritional traits, including strong representation of conserved genes functioning in signaling. Key genes identified by the GWA study are validated by loss-of-function mutations that altered microbiota-dependent nutritional effects. We conclude that the microbiota interacts with the animal at multiple points in the signaling and regulatory networks that determine animal nutrition. These interactions with the microbiota are likely conserved across animals, including humans.
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Affiliation(s)
- Adam J Dobson
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - John M Chaston
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - Peter D Newell
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - Leanne Donahue
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - Sara L Hermann
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - David R Sannino
- Department of Microbiology, Cornell University, Ithaca, New York 14853, USA
| | | | - Adam C-N Wong
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Brian P Lazzaro
- Department of Entomology, Cornell University, Ithaca, New York 14853, USA
| | - Angela E Douglas
- 1] Department of Entomology, Cornell University, Ithaca, New York 14853, USA [2] Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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35
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Limmer S, Weiler A, Volkenhoff A, Babatz F, Klämbt C. The Drosophila blood-brain barrier: development and function of a glial endothelium. Front Neurosci 2014; 8:365. [PMID: 25452710 PMCID: PMC4231875 DOI: 10.3389/fnins.2014.00365] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/23/2014] [Indexed: 01/01/2023] Open
Abstract
The efficacy of neuronal function requires a well-balanced extracellular ion homeostasis and a steady supply with nutrients and metabolites. Therefore, all organisms equipped with a complex nervous system developed a so-called blood-brain barrier, protecting it from an uncontrolled entry of solutes, metabolites or pathogens. In higher vertebrates, this diffusion barrier is established by polarized endothelial cells that form extensive tight junctions, whereas in lower vertebrates and invertebrates the blood-brain barrier is exclusively formed by glial cells. Here, we review the development and function of the glial blood-brain barrier of Drosophila melanogaster. In the Drosophila nervous system, at least seven morphologically distinct glial cell classes can be distinguished. Two of these glial classes form the blood-brain barrier. Perineurial glial cells participate in nutrient uptake and establish a first diffusion barrier. The subperineurial glial (SPG) cells form septate junctions, which block paracellular diffusion and thus seal the nervous system from the hemolymph. We summarize the molecular basis of septate junction formation and address the different transport systems expressed by the blood-brain barrier forming glial cells.
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Affiliation(s)
- Stefanie Limmer
- Institut für Neuro- und Verhaltensbiologie, Universität Münster Münster, Germany
| | - Astrid Weiler
- Institut für Neuro- und Verhaltensbiologie, Universität Münster Münster, Germany
| | - Anne Volkenhoff
- Institut für Neuro- und Verhaltensbiologie, Universität Münster Münster, Germany
| | - Felix Babatz
- Institut für Neuro- und Verhaltensbiologie, Universität Münster Münster, Germany
| | - Christian Klämbt
- Institut für Neuro- und Verhaltensbiologie, Universität Münster Münster, Germany
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36
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Izumi Y, Furuse M. Molecular organization and function of invertebrate occluding junctions. Semin Cell Dev Biol 2014; 36:186-93. [PMID: 25239398 DOI: 10.1016/j.semcdb.2014.09.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 08/25/2014] [Accepted: 09/01/2014] [Indexed: 12/31/2022]
Abstract
Septate junctions (SJs) are specialized intercellular junctions that function as permeability barriers to restrict the free diffusion of solutes through the paracellular routes in invertebrate epithelia. SJs are subdivided into several morphological types that vary among different animal phyla. In several phyla, different types of SJ have been described in different epithelia within an individual. Arthropods have two types of SJs: pleated SJs (pSJs) and smooth SJs (sSJs), found in ectodermally and endodermally derived epithelia, respectively. Several lines of Drosophila research have identified and characterized a large number of pSJ-associated proteins. Two sSJ-specific proteins have been recently reported. Molecular dissection of SJs in Drosophila and animals in other phyla will lead to a better understanding of the functional differences among SJ types and of evolutionary aspects of these permeability barriers.
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Affiliation(s)
- Yasushi Izumi
- Division of Cell Biology, Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
| | - Mikio Furuse
- Division of Cell Biology, Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan; Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan
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37
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Hall S, Bone C, Oshima K, Zhang L, McGraw M, Lucas B, Fehon RG, Ward RE. Macroglobulin complement-related encodes a protein required for septate junction organization and paracellular barrier function in Drosophila. Development 2014; 141:889-98. [PMID: 24496625 DOI: 10.1242/dev.102152] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Polarized epithelia play crucial roles as barriers to the outside environment and enable the formation of specialized compartments for organs to carry out essential functions. Barrier functions are mediated by cellular junctions that line the lateral plasma membrane between cells, principally tight junctions in vertebrates and septate junctions (SJs) in invertebrates. Over the last two decades, more than 20 genes have been identified that function in SJ biogenesis in Drosophila, including those that encode core structural components of the junction such as Neurexin IV, Coracle and several claudins, as well as proteins that facilitate the trafficking of SJ proteins during their assembly. Here we demonstrate that Macroglobulin complement-related (Mcr), a gene previously implicated in innate immunity, plays an essential role during embryonic development in SJ organization and function. We show that Mcr colocalizes with other SJ proteins in mature ectodermally derived epithelial cells, that it shows interdependence with other SJ proteins for SJ localization, and that Mcr mutant epithelia fail to form an effective paracellular barrier. Tissue-specific RNA interference further demonstrates that Mcr is required cell-autonomously for SJ organization. Finally, we show a unique interdependence between Mcr and Nrg for SJ localization that provides new insights into the organization of the SJ. Together, these studies demonstrate that Mcr is a core component of epithelial SJs and also highlight an interesting relationship between innate immunity and epithelial barrier functions.
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Affiliation(s)
- Sonia Hall
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
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38
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Song Y, Eng M, Ghabrial AS. Focal defects in single-celled tubes mutant for Cerebral cavernous malformation 3, GCKIII, or NSF2. Dev Cell 2013; 25:507-19. [PMID: 23763949 DOI: 10.1016/j.devcel.2013.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 04/09/2013] [Accepted: 05/02/2013] [Indexed: 10/26/2022]
Abstract
Tubes of differing cellular architecture connect into networks. In the Drosophila tracheal system, two tube types connect within single cells (terminal cells); however, the genes that mediate this interconnection are unknown. Here we characterize two genes that are essential for this process: lotus, required for maintaining a connection between the tubes, and wheezy, required to prevent local tube dilation. We find that lotus encodes N-ethylmaleimide sensitive factor 2 (NSF2), whereas wheezy encodes Germinal center kinase III (GCKIII). GCKIIIs are effectors of Cerebral cavernous malformation 3 (CCM3), a protein mutated in vascular disease. Depletion of Ccm3 by RNA interference phenocopies wheezy; thus, CCM3 and GCKIII, which prevent capillary dilation in humans, prevent tube dilation in Drosophila trachea. Ectopic junctional and apical proteins are present in wheezy terminal cells, and we show that tube dilation is suppressed by reduction of NSF2, of the apical determinant Crumbs, or of septate junction protein Varicose.
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Affiliation(s)
- Yanjun Song
- Department of Cell and Developmental Biology, Perelman School of Medicine, BRBII/III Room 1214, 421 Curie Boulevard, University of Pennsylvania, Philadelphia, PA 19104, USA
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39
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Simske JS. Claudins reign: The claudin/EMP/PMP22/γ channel protein family in C. elegans. Tissue Barriers 2013; 1:e25502. [PMID: 24665403 PMCID: PMC3879130 DOI: 10.4161/tisb.25502] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 06/19/2013] [Accepted: 06/21/2013] [Indexed: 01/06/2023] Open
Abstract
The claudin family of integral membrane proteins was identified as the major protein component of the tight junctions in all vertebrates. Since their identification, claudins, and their associated pfam00822 superfamily of proteins have been implicated in a wide variety of cellular processes. Claudin homologs have been identified in invertebrates as well, including Drosophila and C. elegans. Recent studies demonstrate that the C. elegans claudins, clc-1-clc- 5, and similar proteins in the greater PMP22/EMP/claudin/voltage-gated calcium channel γ subunit family, including nsy-4, and vab-9, while highly divergent at a sequence level from each other and from the vertebrate claudins, in many cases play roles similar to those traditionally assigned to their vertebrate homologs. These include regulating cell adhesion and passage of small molecules through the paracellular space, channel activity, protein aggregation, sensitivity to pore-forming toxins, intercellular signaling, cell fate specification and dynamic changes in cell morphology. Study of claudin superfamily proteins in C. elegans should continue to provide clues as to how claudin family protein function has been adapted to perform diverse functions at specialized cell-cell contacts in metazoans.
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40
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Ile KE, Renault AD. Compartmentalizing the embryo: lipids and septate junction mediated barrier function. Fly (Austin) 2012; 7:18-22. [PMID: 23221483 PMCID: PMC3660746 DOI: 10.4161/fly.22938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Lipid phosphate phosphatases (LPPs) are a class of enzymes that can dephosphorylate a number of lysophopholipids in vitro. Analysis of knockouts of LPP family members has demonstrated striking but diverse developmental roles for these enzymes. LPP3 is required for mouse vascular development while the Drosophila LPPs Wunen (Wun) and Wunen2 (Wun2) are required during embryogenesis for germ cell migration and survival. In a recent publication we examined if these fly LPPs have further developmental roles and found that Wun is required for proper tracheal formation. In particular we highlight a role for Wun in septate junction mediated barrier function in the tracheal system. In this paper we discuss further the possible mechanisms by which LPPs may influence barrier activity.
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Affiliation(s)
- Kristina E Ile
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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41
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Hannezo E, Prost J, Joanny JF. Mechanical instabilities of biological tubes. PHYSICAL REVIEW LETTERS 2012; 109:018101. [PMID: 23031132 DOI: 10.1103/physrevlett.109.018101] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Indexed: 05/23/2023]
Abstract
We study theoretically the morphologies of biological tubes affected by various pathologies. When epithelial cells grow, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated: varicose, dilated, sinuous, or sausagelike. They are all found in pathologies of tracheal, renal tubes, or arteries. The final shape depends crucially on the mechanical parameters of the tissues: Young's modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation.
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Affiliation(s)
- Edouard Hannezo
- Physicochimie Curie, Institut Curie, Centre de Recherche, 26 rue d'Ulm F-75248 Paris Cedex 05, France
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42
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Ile KE, Tripathy R, Goldfinger V, Renault AD. Wunen, a Drosophila lipid phosphate phosphatase, is required for septate junction-mediated barrier function. Development 2012; 139:2535-46. [PMID: 22675212 DOI: 10.1242/dev.077289] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Lipid phosphate phosphatases (LPPs) are integral membrane enzymes that regulate the levels of bioactive lipids such as sphingosine 1-phosphate and lysophosphatidic acid. The Drosophila LPPs Wunen (Wun) and Wunen-2 (Wun2) have a well-established role in regulating the survival and migration of germ cells. We now show that wun has an essential tissue-autonomous role in development of the trachea: the catalytic activity of Wun is required to maintain septate junction (SJ) paracellular barrier function, loss of which causes failure to accumulate crucial luminal components, suggesting a role for phospholipids in SJ function. We find that the integrity of the blood-brain barrier is also lost in wun mutants, indicating that loss of SJ function is not restricted to the tracheal system. Furthermore, by comparing the rescue ability of different LPP homologs we show that wun function in the trachea is distinct from its role in germ cell migration.
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Affiliation(s)
- Kristina E Ile
- Max Planck Institute for Developmental Biology, Spemannstr. 35, 72076 Tübingen, Germany
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43
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Wang S, Samakovlis C. Grainy head and its target genes in epithelial morphogenesis and wound healing. Curr Top Dev Biol 2012; 98:35-63. [PMID: 22305158 DOI: 10.1016/b978-0-12-386499-4.00002-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The Grainy head (Grh) family of transcription factors is characterized by a unique DNA-binding domain that binds to a conserved consensus sequence. Nematodes and flies have a single grh gene, whereas mice and humans have evolved three genes encoding Grainy head-like (Grhl) factors. We review the biological function of Grh in different animals and the mechanisms modulating its activity. grh and grhl genes play a remarkably conserved role in epithelial organ development and extracellular barrier repair after tissue damage. Recent studies in flies and vertebrates suggest that Grh factors may be primary determinants of cell adhesion and epithelial tissue formation. Grh proteins can dimerize and act as activators or repressors in different developmental contexts. In flies, tissue-specific, alternative splicing generates different Grh isoforms with different DNA-binding specificities and functions. Grh activity is also modulated by receptor tyrosine kinases: it is phosphorylated by extracellular signal regulated kinase, and this phosphorylation is selectively required for epidermal barrier repair. Two mechanisms have been proposed to explain the repressive function of Grh on target gene transcription. First, Grh can target the Polycomb silencing complex to specific response elements. Second, it can directly compete for DNA binding with transcriptional activators. Understanding the molecular mechanisms of gene regulation by Grh factors is likely to elucidate phylogenetically conserved mechanisms of epithelial cell morphogenesis and regeneration upon tissue damage.
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Affiliation(s)
- Shenqiu Wang
- Department of Developmental Biology, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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44
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Izumi Y, Yanagihashi Y, Furuse M. A novel protein complex, mesh-ssk, is required for septate junction formation in drosophila midgut. J Cell Sci 2012; 125:4923-33. [DOI: 10.1242/jcs.112243] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Septate junctions (SJs) are specialized intercellular junctions that restrict the free diffusion of solutes through the paracellular route in invertebrate epithelia. In arthropods, two morphologically different types of SJs have been reported: pleated SJs and smooth SJs (sSJs), which are found in ectodermally and endodermally derived epithelia, respectively. However, the molecular and functional differences between these SJ types have not been elucidated. Here we report that a novel sSJ-specific component, a single-pass transmembrane protein, termed ‘Mesh’ is highly concentrated in Drosophila sSJs. Compromised mesh expression causes defects in the organization of sSJs, in the localizations of other sSJ proteins, and in the barrier function of the midgut. Ectopic expression of Mesh in cultured cells induces cell-cell adhesion. Mesh forms a complex with Ssk, another sSJ-specific protein, and these proteins are mutually interdependent for their localization. Thus, a novel protein complex comprising Mesh and Ssk plays a significant role in sSJ formation and in intestinal barrier function in Drosophila.
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45
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Yanagihashi Y, Usui T, Izumi Y, Yonemura S, Sumida M, Tsukita S, Uemura T, Furuse M. A novel smooth septate junction-associated membrane protein, Snakeskin, is required for intestinal barrier function in Drosophila. J Cell Sci 2012; 125:1980-90. [DOI: 10.1242/jcs.096800] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Septate junctions (SJs) are the membrane specializations observed between epithelial cells in invertebrates. SJs play a crucial role in epithelial barrier function by restricting free diffusion of solutes through the intercellular space. In arthropod species, two morphologically different types of SJs have been described: pleated septate junctions (pSJs) and smooth septate junctions (sSJs), which are specific to ectodermal and endodermal epithelia, respectively. In contrast to the recent understanding of pSJ-related proteins, the molecular constituents of sSJs are mostly unknown. Here we report a novel sSJ-specific membrane protein, designated ‘Snakeskin’ (Ssk). Ssk is highly concentrated in sSJs in the Drosophila midgut and Malpighian tubules. Lack of Ssk expression is embryonically lethal in Drosophila and results in defective sSJ formation accompanied by abnormal morphology of midgut epithelial cells. We also show that the barrier function of the midgut to a fluorescent tracer is impaired in Ssk-knockdown larvae. These results suggest that Ssk is required for the intestinal barrier function in Drosophila.
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Duox, Flotillin-2, and Src42A are required to activate or delimit the spread of the transcriptional response to epidermal wounds in Drosophila. PLoS Genet 2011; 7:e1002424. [PMID: 22242003 PMCID: PMC3248467 DOI: 10.1371/journal.pgen.1002424] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 10/31/2011] [Indexed: 12/24/2022] Open
Abstract
The epidermis is the largest organ of the body for most animals, and the first line of defense against invading pathogens. A breach in the epidermal cell layer triggers a variety of localized responses that in favorable circumstances result in the repair of the wound. Many cellular and genetic responses must be limited to epidermal cells that are close to wounds, but how this is regulated is still poorly understood. The order and hierarchy of epidermal wound signaling factors are also still obscure. The Drosophila embryonic epidermis provides an excellent system to study genes that regulate wound healing processes. We have developed a variety of fluorescent reporters that provide a visible readout of wound-dependent transcriptional activation near epidermal wound sites. A large screen for mutants that alter the activity of these wound reporters has identified seven new genes required to activate or delimit wound-induced transcriptional responses to a narrow zone of cells surrounding wound sites. Among the genes required to delimit the spread of wound responses are Drosophila Flotillin-2 and Src42A, both of which are transcriptionally activated around wound sites. Flotillin-2 and constitutively active Src42A are also sufficient, when overexpressed at high levels, to inhibit wound-induced transcription in epidermal cells. One gene required to activate epidermal wound reporters encodes Dual oxidase, an enzyme that produces hydrogen peroxide. We also find that four biochemical treatments (a serine protease, a Src kinase inhibitor, methyl-ß-cyclodextrin, and hydrogen peroxide) are sufficient to globally activate epidermal wound response genes in Drosophila embryos. We explore the epistatic relationships among the factors that induce or delimit the spread of epidermal wound signals. Our results define new genetic functions that interact to instruct only a limited number of cells around puncture wounds to mount a transcriptional response, mediating local repair and regeneration. An epidermal wound provides signals that initiate a variety of localized responses, some of which act to regenerate and repair the breach in the epidermal barrier. The Drosophila melanogaster embryonic epidermis provides an excellent system to discover new genes that regulate wound-healing processes. Using fluorescent epidermal “wound” reporters that are locally activated around wound sites, we have screened almost 5,000 Drosophila mutants for functions required to activate or delimit wound-induced transcriptional responses to a local zone of epidermal cells. Among the seven new genes required to delimit the spread of wound responses are Flotillin-2 and Src42A. These two genes are also sufficient, when overexpressed at high levels, to inhibit wound-induced transcription in epidermal cells. One new gene required to activate epidermal wound reporters encodes Dual oxidase, an enzyme that produces hydrogen peroxide. We also find that four biochemical treatments (a serine protease, a Src kinase inhibitor, methyl-ß-cyclodextrin, and hydrogen peroxide) are sufficient to globally activate epidermal wound response genes in Drosophila embryos. Our results define new genetic functions, and the interactions among them, which regulate the local transcriptional response to puncture wounds.
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Oshima K, Fehon RG. Analysis of protein dynamics within the septate junction reveals a highly stable core protein complex that does not include the basolateral polarity protein Discs large. J Cell Sci 2011; 124:2861-71. [PMID: 21807950 DOI: 10.1242/jcs.087700] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Barrier junctions prevent pathogen invasion and restrict paracellular leakage across epithelial sheets. To understand how one barrier junction, the septate junction (SJ), is regulated in vivo, we used fluorescence recovery after photobleaching (FRAP) to examine SJ protein dynamics in Drosophila. Most SJ-associated proteins, including Coracle, Neurexin IV and Nervana 2, displayed similar, extremely immobile kinetics. Loss of any of these components resulted in dramatically increased mobility of all others, suggesting that they form a single, highly interdependent core complex. Immobilization of SJ core components coincided with formation of the morphological SJ but occurred after their known role in maintaining epithelial polarity, suggesting that these functions are independent. In striking contrast to the core components, the tumor suppressor protein Discs large was much more mobile and its loss did not affect mobility of core SJ proteins, suggesting that it is not a member of this complex, even though it colocalizes with the SJ. Similarly, disruption of endocytosis affected localization of SJ core components, but did not affect their mobility. These results indicate that formation of a stable SJ core complex is separable from its proper subcellular localization, and provide new insights into the complex processes that regulate epithelial polarity and assembly of the SJ.
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Affiliation(s)
- Kenzi Oshima
- Department of Molecular Genetics and Cell Biology, University of Chicago, 920 E. 58th Street, CLSC 925B, Chicago, IL 60637, USA
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Maruyama R, Andrew DJ. Drosophila as a model for epithelial tube formation. Dev Dyn 2011; 241:119-35. [PMID: 22083894 DOI: 10.1002/dvdy.22775] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2011] [Indexed: 12/17/2022] Open
Abstract
Epithelial tubular organs are essential for life in higher organisms and include the pancreas and other secretory organs that function as biological factories for the synthesis and delivery of secreted enzymes, hormones, and nutrients essential for tissue homeostasis and viability. The lungs, which are necessary for gas exchange, vocalization, and maintaining blood pH, are organized as highly branched tubular epithelia. Tubular organs include arteries, veins, and lymphatics, high-speed passageways for delivery and uptake of nutrients, liquids, gases, and immune cells. The kidneys and components of the reproductive system are also epithelial tubes. Both the heart and central nervous system of many vertebrates begin as epithelial tubes. Thus, it is not surprising that defects in tube formation and maintenance underlie many human diseases. Accordingly, a thorough understanding how tubes form and are maintained is essential to developing better diagnostics and therapeutics. Among the best-characterized tubular organs are the Drosophila salivary gland and trachea, organs whose relative simplicity have allowed for in depth analysis of gene function, yielding key mechanistic insight into tube initiation, remodeling and maintenance. Here, we review our current understanding of salivary gland and trachea formation - highlighting recent discoveries into how these organs attain their final form and function.
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Affiliation(s)
- Rika Maruyama
- The Johns Hopkins University School of Medicine, Department of Cell Biology, Baltimore, Maryland 21205-2196, USA
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A Laminin G-EGF-Laminin G module in Neurexin IV is essential for the apico-lateral localization of Contactin and organization of septate junctions. PLoS One 2011; 6:e25926. [PMID: 22022470 PMCID: PMC3195077 DOI: 10.1371/journal.pone.0025926] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/13/2011] [Indexed: 01/01/2023] Open
Abstract
Septate junctions (SJs) display a unique ultrastructural morphology with ladder-like electron densities that are conserved through evolution. Genetic and molecular analyses have identified a highly conserved core complex of SJ proteins consisting of three cell adhesion molecules Neurexin IV, Contactin, and Neuroglian, which interact with the cytoskeletal FERM domain protein Coracle. How these individual proteins interact to form the septal arrays that create the paracellular barrier is poorly understood. Here, we show that point mutations that map to specific domains of neurexin IV lead to formation of fewer septae and disorganization of SJs. Consistent with these observations, our in vivo domain deletion analyses identified the first Laminin G-EGF-Laminin G module in the extracellular region of Neurexin IV as necessary for the localization of and association with Contactin. Neurexin IV protein that is devoid of its cytoplasmic region is able to create septae, but fails to form a full complement of SJs. These data provide the first in vivo evidence that specific domains in Neurexin IV are required for protein-protein interactions and organization of SJs. Given the molecular conservation of SJ proteins across species, our studies may provide insights into how vertebrate axo-glial SJs are organized in myelinated axons.
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DeSalvo MK, Mayer N, Mayer F, Bainton RJ. Physiologic and anatomic characterization of the brain surface glia barrier of Drosophila. Glia 2011; 59:1322-40. [PMID: 21351158 PMCID: PMC3130812 DOI: 10.1002/glia.21147] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 12/20/2010] [Indexed: 12/22/2022]
Abstract
Central nervous system (CNS) physiology requires special chemical, metabolic, and cellular privileges for normal function, and blood-brain barrier (BBB) structures are the anatomic and physiologic constructs that arbitrate communication between the brain and body. In the vertebrate BBB, two primary cell types create CNS exclusion biology, a polarized vascular endothelium (VE), and a tightly associated single layer of astrocytic glia (AG). Examples of direct action by the BBB in CNS disease are constantly expanding, including key pathophysiologic roles in multiple sclerosis, stroke, and cancer. In addition, its role as a pharmacologic treatment obstacle to the brain is long standing; thus, molecular model systems that can parse BBB functions and understand the complex integration of sophisticated cellular anatomy and highly polarized chemical protection physiology are desperately needed. Compound barrier structures that use two primary cell types (i.e., functional bicellularity) are common to other humoral/CNS barrier structures. For example, invertebrates use two cell layers of glia, perineurial and subperineurial, to control chemical access to the brain, and analogous glial layers, fenestrated and pseudocartridge, to maintain the blood-eye barrier. In this article, we summarize our current understanding of brain-barrier glial anatomy in Drosophila, demonstrate the power of live imaging as a screening methodology for identifying physiologic characteristics of BBB glia, and compare the physiologies of Drosophila barrier layers to the VE/AG interface of vertebrates. We conclude that many unique BBB physiologies are conserved across phyla and suggest new methods for modeling CNS physiology and disease.
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Affiliation(s)
- Michael K. DeSalvo
- University of California at San Francisco, Department of Anesthesia and Perioperative Care, Program in Biological Sciences, Mission Bay Genentech Hall, 600 16th Street, San Francisco, CA 94158-2517
| | - Nasima Mayer
- University of California at San Francisco, Department of Anesthesia and Perioperative Care, Program in Biological Sciences, Mission Bay Genentech Hall, 600 16th Street, San Francisco, CA 94158-2517
| | - Fahima Mayer
- University of California at San Francisco, Department of Anesthesia and Perioperative Care, Program in Biological Sciences, Mission Bay Genentech Hall, 600 16th Street, San Francisco, CA 94158-2517
| | - Roland J. Bainton
- University of California at San Francisco, Department of Anesthesia and Perioperative Care, Program in Biological Sciences, Mission Bay Genentech Hall, 600 16th Street, San Francisco, CA 94158-2517
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