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Schmidt A, Finegan T, Häring M, Kong D, Fletcher AG, Alam Z, Grosshans J, Wolf F, Peifer M. Polychaetoid/ZO-1 strengthens cell junctions under tension while localizing differently than core adherens junction proteins. Mol Biol Cell 2023; 34:ar81. [PMID: 37163320 PMCID: PMC10398881 DOI: 10.1091/mbc.e23-03-0077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/11/2023] Open
Abstract
During embryonic development, dramatic cell shape changes and movements reshape the embryonic body plan. These require robust but dynamic linkage between the cell-cell adherens junctions and the force-generating actomyosin cytoskeleton. Our view of this linkage has evolved, and we now realize linkage is mediated by mechanosensitive multiprotein complexes assembled via multivalent connections. Here we combine genetic, cell biological, and modeling approaches to define the mechanism of action and functions of an important player, Drosophila polychaetoid, homologue of mammalian ZO-1. Our data reveal that Pyd reinforces cell junctions under elevated tension, and facilitates cell rearrangements. Pyd is important to maintain junctional contractility and in its absence cell rearrangements stall. We next use structured illumination microscopy to define the molecular architecture of cell-cell junctions during these events. The cadherin-catenin complex and Cno both localize to puncta along the junctional membrane, but are differentially enriched in different puncta. Pyd, in contrast, exhibits a distinct localization to strands that extend out from the region occupied by core junction proteins. We then discuss the implications for the protein network at the junction-cytoskeletal interface, suggesting different proteins localize and function in distinct ways, perhaps in distinct subcomplexes, but combine to produce robust connections.
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Affiliation(s)
- Anja Schmidt
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Tara Finegan
- Department of Biology, University of Rochester, Rochester, New York 14627-0211
| | - Matthias Häring
- Göttingen Campus Institute for Dynamics of Biological Networks, Georg August University, 37075 Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany
- Institute for Dynamics of Complex Systems, Georg August University, 37077 Göttingen, Germany
| | - Deqing Kong
- Department of Biology, Philipps University, 35043 Marburg, Germany
| | - Alexander G Fletcher
- School of Mathematics and Statistics and Bateson Centre, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Zuhayr Alam
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Jörg Grosshans
- Department of Biology, Philipps University, 35043 Marburg, Germany
| | - Fred Wolf
- Göttingen Campus Institute for Dynamics of Biological Networks, Georg August University, 37075 Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany
- Institute for Dynamics of Complex Systems, Georg August University, 37077 Göttingen, Germany
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
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Schmidt A, Finegan T, Häring M, Kong D, Fletcher AG, Alam Z, Grosshans J, Wolf F, Peifer M. Polychaetoid/ZO-1 strengthens cell junctions under tension while localizing differently than core adherens junction proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.01.530634. [PMID: 36909597 PMCID: PMC10002719 DOI: 10.1101/2023.03.01.530634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
During embryonic development dramatic cell shape changes and movements re-shape the embryonic body plan. These require robust but dynamic linkage between the cell-cell adherens junctions and the force-generating actomyosin cytoskeleton. Our view of this linkage has evolved, and we now realize linkage is mediated by a mechanosensitive multiprotein complex assembled via multivalent connections. Here we combine genetic, cell biological and modeling approaches to define the mechanism of action and functions of an important player, Drosophila Polychaetoid, homolog of mammalian ZO-1. Our data reveal that Pyd reinforces cell junctions under elevated tension, and facilitates cell rearrangements. Pyd is important to maintain junctional contractility and in its absence cell rearrangements stall. We next use structured illumination microscopy to define the molecular architecture of cell-cell junctions during these events. The cadherin-catenin complex and Cno both localize to puncta along the junctional membrane, but are differentially enriched in different puncta. Pyd, in contrast, exhibits a distinct localization to strands that extend out from the region occupied by core junction proteins. We then discuss the implications for the protein network at the junction-cytoskeletal interface, suggesting different proteins localize and function in distinct ways but combine to produce robust connections.
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Affiliation(s)
- Anja Schmidt
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
| | - Tara Finegan
- Department of Biology, University of Rochester, Rochester, New York, USA 14627-0211
| | - Matthias Häring
- Göttingen Campus Institute for Dynamics of Biological Networks, Georg August University, Hermann Rein Str. 3, 37075 Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, Hermann Rein St. 3, 37075 Göttingen, German
- Institute for Dynamics of Complex Systems, Georg August University, Friedrich Hund Pl. 1, 37077 Göttingen, Germany
| | - Deqing Kong
- Department of Biology, Philipps University, Karl-von-Frisch-Straße 8, 35043 Marburg, Germany
| | - Alexander G Fletcher
- School of Mathematics and Statistics & Bateson Centre, University of Sheffield, Sheffield, UK
| | - Zuhayr Alam
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
| | - Jörg Grosshans
- Department of Biology, Philipps University, Karl-von-Frisch-Straße 8, 35043 Marburg, Germany
| | - Fred Wolf
- Göttingen Campus Institute for Dynamics of Biological Networks, Georg August University, Hermann Rein Str. 3, 37075 Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, Hermann Rein St. 3, 37075 Göttingen, German
- Institute for Dynamics of Complex Systems, Georg August University, Friedrich Hund Pl. 1, 37077 Göttingen, Germany
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
- Corresponding author
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Perez-Vale KZ, Yow KD, Johnson RI, Byrnes AE, Finegan TM, Slep KC, Peifer M. Multivalent interactions make adherens junction-cytoskeletal linkage robust during morphogenesis. J Cell Biol 2021; 220:e202104087. [PMID: 34762121 PMCID: PMC8590279 DOI: 10.1083/jcb.202104087] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 09/15/2021] [Accepted: 10/04/2021] [Indexed: 12/15/2022] Open
Abstract
Embryogenesis requires cells to change shape and move without disrupting epithelial integrity. This requires robust, responsive linkage between adherens junctions and the actomyosin cytoskeleton. Using Drosophila morphogenesis, we define molecular mechanisms mediating junction-cytoskeletal linkage and explore the role of mechanosensing. We focus on the junction-cytoskeletal linker Canoe, a multidomain protein. We engineered the canoe locus to define how its domains mediate its mechanism of action. To our surprise, the PDZ and FAB domains, which we thought connected junctions and F-actin, are not required for viability or mechanosensitive recruitment to junctions under tension. The FAB domain stabilizes junctions experiencing elevated force, but in its absence, most cells recover, suggesting redundant interactions. In contrast, the Rap1-binding RA domains are critical for all Cno functions and enrichment at junctions under tension. This supports a model in which junctional robustness derives from a large protein network assembled via multivalent interactions, with proteins at network nodes and some node connections more critical than others.
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Affiliation(s)
- Kia Z. Perez-Vale
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Kristi D. Yow
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | | | - Amy E. Byrnes
- Program in Molecular and Cellular Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Tara M. Finegan
- Department of Physics and BioInspired Syracuse, Syracuse University, Syracuse, NY
| | - Kevin C. Slep
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Mark Peifer
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC
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Sang Q, Wang G, Morton DB, Wu H, Xie B. The ZO-1 protein Polychaetoid as an upstream regulator of the Hippo pathway in Drosophila. PLoS Genet 2021; 17:e1009894. [PMID: 34748546 PMCID: PMC8610254 DOI: 10.1371/journal.pgen.1009894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 11/23/2021] [Accepted: 10/19/2021] [Indexed: 01/15/2023] Open
Abstract
The generation of a diversity of photoreceptor (PR) subtypes with different spectral sensitivities is essential for color vision in animals. In the Drosophila eye, the Hippo pathway has been implicated in blue- and green-sensitive PR subtype fate specification. Specifically, Hippo pathway activation promotes green-sensitive PR fate at the expense of blue-sensitive PRs. Here, using a sensitized triple heterozygote-based genetic screening approach, we report the identification of the single Drosophila zonula occludens-1 (ZO-1) protein Polychaetoid (Pyd) as a new regulator of the Hippo pathway during the blue- and green-sensitive PR subtype binary fate choice. We demonstrate that Pyd acts upstream of the core components and the upstream regulator Pez in the Hippo pathway. Furthermore, We found that Pyd represses the activity of Su(dx), a E3 ligase that negatively regulates Pez and can physically interact with Pyd, during PR subtype fate specification. Together, our results identify a new mechanism underlying the Hippo signaling pathway in post-mitotic neuronal fate specification. The Hippo signaling pathway was originally discovered for its critical role in tissue growth and organ size control. Its evolutionarily conserved roles in various biological processes, including cell differentiation, stem cell regeneration and homeostasis, innate immune biology, as well as tumorigenesis, have been subsequently found in other species. During the development of the Drosophila eye, the Hippo pathway promotes green- and represses blue-sensitive photoreceptor (PR) subtype fate specification. Taking advantage of this binary PR fate choice, we screened Drosophila chromosomal deficiency lines to seek new regulators of the Hippo signaling pathway. We identified the Drosophila membrane-associated ZO-1 protein Pyd as an upstream regulator of the Hippo pathway to specify PR subtypes. Our results have demonstrated that Pyd represses Su(dx)’s activity in the Hippo pathway to specify PR subtypes. Our results demonstrate a new mechanism underlying the Hippo signaling pathway in post-mitotic neuronal fate specification.
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Affiliation(s)
- Qingliang Sang
- Integrative Biomedical and Diagnostic Sciences Department, School of Dentistry, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Gang Wang
- Integrative Biomedical and Diagnostic Sciences Department, School of Dentistry, Oregon Health and Science University, Portland, Oregon, United States of America
| | - David B. Morton
- Integrative Biomedical and Diagnostic Sciences Department, School of Dentistry, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Hui Wu
- Integrative Biomedical and Diagnostic Sciences Department, School of Dentistry, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Baotong Xie
- Integrative Biomedical and Diagnostic Sciences Department, School of Dentistry, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail:
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Rouaud F, Sluysmans S, Flinois A, Shah J, Vasileva E, Citi S. Scaffolding proteins of vertebrate apical junctions: structure, functions and biophysics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183399. [DOI: 10.1016/j.bbamem.2020.183399] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 06/05/2020] [Accepted: 06/11/2020] [Indexed: 12/11/2022]
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Overton IM, Sims AH, Owen JA, Heale BSE, Ford MJ, Lubbock ALR, Pairo-Castineira E, Essafi A. Functional Transcription Factor Target Networks Illuminate Control of Epithelial Remodelling. Cancers (Basel) 2020; 12:cancers12102823. [PMID: 33007944 PMCID: PMC7652213 DOI: 10.3390/cancers12102823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 09/16/2020] [Accepted: 09/24/2020] [Indexed: 12/15/2022] Open
Abstract
Cell identity is governed by gene expression, regulated by transcription factor (TF) binding at cis-regulatory modules. Decoding the relationship between TF binding patterns and gene regulation is nontrivial, remaining a fundamental limitation in understanding cell decision-making. We developed the NetNC software to predict functionally active regulation of TF targets; demonstrated on nine datasets for the TFs Snail, Twist, and modENCODE Highly Occupied Target (HOT) regions. Snail and Twist are canonical drivers of epithelial to mesenchymal transition (EMT), a cell programme important in development, tumour progression and fibrosis. Predicted "neutral" (non-functional) TF binding always accounted for the majority (50% to 95%) of candidate target genes from statistically significant peaks and HOT regions had higher functional binding than most of the Snail and Twist datasets examined. Our results illuminated conserved gene networks that control epithelial plasticity in development and disease. We identified new gene functions and network modules including crosstalk with notch signalling and regulation of chromatin organisation, evidencing networks that reshape Waddington's epigenetic landscape during epithelial remodelling. Expression of orthologous functional TF targets discriminated breast cancer molecular subtypes and predicted novel tumour biology, with implications for precision medicine. Predicted invasion roles were validated using a tractable cell model, supporting our approach.
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Affiliation(s)
- Ian M. Overton
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
- Department of Systems Biology, Harvard University, Boston, MA 02115, USA;
- Centre for Synthetic and Systems Biology (SynthSys), University of Edinburgh, Edinburgh EH9 3BF, UK
- Patrick G Johnston Centre for Cancer Research, Queen’s University Belfast, Belfast BT9 7AE, UK
- Correspondence:
| | - Andrew H. Sims
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Jeremy A. Owen
- Department of Systems Biology, Harvard University, Boston, MA 02115, USA;
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Bret S. E. Heale
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Matthew J. Ford
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Alexander L. R. Lubbock
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Erola Pairo-Castineira
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Abdelkader Essafi
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
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7
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Carrasco-Rando M, Prieto-Sánchez S, Culi J, Tutor AS, Ruiz-Gómez M. A specific isoform of Pyd/ZO-1 mediates junctional remodeling and formation of slit diaphragms. J Cell Biol 2019; 218:2294-2308. [PMID: 31171632 PMCID: PMC6605796 DOI: 10.1083/jcb.201810171] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 03/21/2019] [Accepted: 05/14/2019] [Indexed: 12/18/2022] Open
Abstract
Podocyte slit diaphragms are key components of the glomerular filtration barrier. Using Drosophila nephrocytes, Carrasco-Rando et al. propose a conserved role for Pyd/ZO-1 in triggering junctional remodeling leading to the formation of slit diaphragms. The podocyte slit diaphragm (SD), responsible for blood filtration in vertebrates, is a major target of injury in chronic kidney disease. The damage includes severe morphological changes with destabilization of SDs and their replacement by junctional complexes between abnormally broadened foot processes. In Drosophila melanogaster, SDs are present in nephrocytes, which filter the fly's hemolymph. Here, we show that a specific isoform of Polychaetoid/ZO-1, Pyd-P, is essential for Drosophila SDs, since, in pyd mutants devoid of Pyd-P, SDs do not form and the SD component Dumbfounded accumulates at ectopic septate-like junctions between abnormally aggregated nephrocytes. Reintroduction of Pyd-P leads to junctional remodeling and their progressive normalization toward SDs. This transition requires the coiled-coil domain of Pyd-P and implies formation of nonclathrin vesicles containing SD components and their trafficking to the nephrocyte external membrane, where SDs assemble. Analyses in zebrafish suggest a conserved role for Tjp1a/ZO-1 in promoting junctional remodeling in podocytes.
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Affiliation(s)
- Marta Carrasco-Rando
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Silvia Prieto-Sánchez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Joaquim Culi
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Antonio S Tutor
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Mar Ruiz-Gómez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
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Shimizu H, Wilkin MB, Woodcock SA, Bonfini A, Hung Y, Mazaleyrat S, Baron M. The Drosophila ZO-1 protein Polychaetoid suppresses Deltex-regulated Notch activity to modulate germline stem cell niche formation. Open Biol 2017; 7:rsob.160322. [PMID: 28424321 PMCID: PMC5413905 DOI: 10.1098/rsob.160322] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 03/13/2017] [Indexed: 11/24/2022] Open
Abstract
The developmental signalling protein Notch can be proteolytically activated following ligand-interaction at the cell surface, or can be activated independently of its ligands, following Deltex (Dx)-induced Notch endocytosis and trafficking to the lysosomal membrane. The means by which different pools of Notch are directed towards these alternative outcomes remains poorly understood. We found that the Drosophila ZO-1 protein Polychaetoid (Pyd) suppresses specifically the Dx-induced form of Notch activation both in vivo and in cell culture assays. In vivo we confirmed the physiological relevance and direction of the Pyd/Dx interaction by showing that the expanded ovary stem cell niche phenotypes of pyd mutants require the presence of functional Dx and other components that are specific to the Dx-induced Notch activation mechanism. In S2 cells we found that Pyd can form a complex with Dx and Notch at the cell surface and reduce Dx-induced Notch endocytosis. Similar to other known activities of ZO-1 family proteins, the action of Pyd on Dx-induced endocytosis and signalling was found to be cell density dependent. Thus, together, our results suggest an alternative means by which external cues can tune Notch signalling through Pyd regulation of Dx-induced Notch trafficking.
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Affiliation(s)
- Hideyuki Shimizu
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
| | - Marian B Wilkin
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
| | - Simon A Woodcock
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
| | - Alessandro Bonfini
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
| | - Yvonne Hung
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
| | - Sabine Mazaleyrat
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
| | - Martin Baron
- University of Manchester, School of Biological Sciences, Manchester Academic Health Science Centre, Michael Smith Building, Oxford Road, Manchester M13 9PL, UK
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Sturgeon M, Davis D, Albers A, Beatty D, Austin R, Ferguson M, Tounsel B, Liebl FLW. The Notch ligand E3 ligase, Mind Bomb1, regulates glutamate receptor localization in Drosophila. Mol Cell Neurosci 2015; 70:11-21. [PMID: 26596173 DOI: 10.1016/j.mcn.2015.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 11/09/2015] [Accepted: 11/16/2015] [Indexed: 12/29/2022] Open
Abstract
The postsynaptic density (PSD) is a protein-rich network important for the localization of postsynaptic glutamate receptors (GluRs) and for signaling downstream of these receptors. Although hundreds of PSD proteins have been identified, many are functionally uncharacterized. We conducted a reverse genetic screen for mutations that affected GluR localization using Drosophila genes that encode homologs of mammalian PSD proteins. 42.8% of the mutants analyzed exhibited a significant change in GluR localization at the third instar larval neuromuscular junction (NMJ), a model synapse that expresses homologs of AMPA receptors. We identified the E3 ubiquitin ligase, Mib1, which promotes Notch signaling, as a regulator of synaptic GluR localization. Mib1 positively regulates the localization of the GluR subunits GluRIIA, GluRIIB, and GluRIIC. Mutations in mib1 and ubiquitous expression of Mib1 that lacks its ubiquitin ligase activity result in the loss of synaptic GluRIIA-containing receptors. In contrast, overexpression of Mib1 in all tissues increases postsynaptic levels of GluRIIA. Cellular levels of Mib1 are also important for the structure of the presynaptic motor neuron. While deficient Mib1 signaling leads to overgrowth of the NMJ, ubiquitous overexpression of Mib1 results in a reduction in the number of presynaptic motor neuron boutons and branches. These synaptic changes may be secondary to attenuated glutamate release from the presynaptic motor neuron in mib1 mutants as mib1 mutants exhibit significant reductions in the vesicle-associated protein cysteine string protein and in the frequency of spontaneous neurotransmission.
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Affiliation(s)
- Morgan Sturgeon
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Dustin Davis
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Amanda Albers
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Derek Beatty
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Rik Austin
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Matt Ferguson
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Brittany Tounsel
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States
| | - Faith L W Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, United States.
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10
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Le Bras S, Rondanino C, Kriegel-Taki G, Dussert A, Le Borgne R. Genetic identification of intracellular trafficking regulators involved in notch dependent binary cell fate acquisition following asymmetric cell division. J Cell Sci 2012; 125:4886-901. [DOI: 10.1242/jcs.110171] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Notch signaling is involved in numerous cellular processes during development and throughout adult life. Although ligands and receptors are largely expressed in the whole organism, activation of Notch receptors only takes place in a subset of cells and/or tissues and is accurately regulated in time and space. Previous studies have demonstrated that endocytosis and recycling of both ligands and/or receptors are essential for this regulation. However, the precise endocytic routes, compartments and regulators involved in the spatio temporal regulation are largely unknown.
In order to identify Notch signaling intracellular trafficking regulators, we have undertaken a tissue-specific dsRNA genetic screen against candidates potentially involved in endocytosis and recycling within the endolysosomal pathway. dsRNA against 418 genes was induced in Drosophila melanogaster sensory organ lineage in which Notch signaling regulates binary cell fate acquisition. Gain- or loss-of Notch signaling phenotypes were observed in adult sensory organs for 113 of them. Furthermore, 26 genes presented a change in the steady state localization of Notch, Sanpodo, a Notch co-factor, and/or Delta in the pupal lineage. In particular, we identified 20 genes with previously unknown function in Drosophila melanogaster intracellular trafficking. Among them, we identified CG2747 and show that it regulates the localization of clathrin adaptor AP-1 complex, a negative regulator of Notch signaling. All together, our results further demonstrate the essential function of intracellular trafficking in regulating Notch signaling-dependent binary cell fate acquisition and constitute an additional step toward the elucidation of the routes followed by Notch receptor and ligands to signal.
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11
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Choi W, Jung KC, Nelson KS, Bhat MA, Beitel GJ, Peifer M, Fanning AS. The single Drosophila ZO-1 protein Polychaetoid regulates embryonic morphogenesis in coordination with Canoe/afadin and Enabled. Mol Biol Cell 2011; 22:2010-30. [PMID: 21508316 PMCID: PMC3113767 DOI: 10.1091/mbc.e10-12-1014] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Analysis of the function of the fly ZO-1 homologue Polychaetoid shows that it is not essential for junctional assembly or maintenance but does play an important role in embryonic morphogenesis. The data suggest that it works with Canoe/afadin and the actin regulator Enabled to regulate actin anchoring at junctions. Adherens and tight junctions play key roles in assembling epithelia and maintaining barriers. In cell culture zonula occludens (ZO)–family proteins are important for assembly/maturation of both tight and adherens junctions (AJs). Genetic studies suggest that ZO proteins are important during normal development, but interpretation of mouse and fly studies is limited by genetic redundancy and/or a lack of null alleles. We generated null alleles of the single Drosophila ZO protein Polychaetoid (Pyd). Most embryos lacking Pyd die with striking defects in morphogenesis of embryonic epithelia including the epidermis, segmental grooves, and tracheal system. Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure. However, Pyd loss does affect several cell behaviors that drive dorsal closure. The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic null mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together. Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.
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Affiliation(s)
- Wangsun Choi
- Department of Biology, University of North Carolina at Chapel Hill, USA
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12
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Djiane A, Shimizu H, Wilkin M, Mazleyrat S, Jennings MD, Avis J, Bray S, Baron M. Su(dx) E3 ubiquitin ligase-dependent and -independent functions of polychaetoid, the Drosophila ZO-1 homologue. ACTA ACUST UNITED AC 2011; 192:189-200. [PMID: 21200027 PMCID: PMC3019562 DOI: 10.1083/jcb.201007023] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Zona occludens (ZO) proteins are molecular scaffolds localized to cell junctions, which regulate epithelial integrity in mammals. Using newly generated null alleles, we demonstrate that polychaetoid (pyd), the unique Drosophila melanogaster ZO homologue, regulates accumulation of adherens junction-localized receptors, such as Notch, although it is dispensable for epithelial polarization. Pyd positively regulates Notch signaling during sensory organ development but acts negatively on Notch to restrict the ovary germline stem cell niche. In both contexts, we identify a core antagonistic interaction between Pyd and the WW domain E3 ubiquitin ligase Su(dx). Pyd binds Su(dx) directly, in part through a noncanonical WW-binding motif. Pyd also restricts epithelial wing cell numbers to control adult wing shape, a function associated with the FERM protein Expanded and independent of Su(dx). As both Su(dx) and Expanded regulate trafficking, we propose that a conserved role of ZO proteins is to coordinate receptor trafficking and signaling with junctional organization.
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Affiliation(s)
- Alexandre Djiane
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, England, UK
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13
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Zhuang S, Shao H, Guo F, Trimble R, Pearce E, Abmayr SM. Sns and Kirre, the Drosophila orthologs of Nephrin and Neph1, direct adhesion, fusion and formation of a slit diaphragm-like structure in insect nephrocytes. Development 2009; 136:2335-44. [PMID: 19515699 DOI: 10.1242/dev.031609] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Immunoglobulin superfamily (IgSF) proteins Neph1 and Nephrin are co-expressed within podocytes in the kidney glomerulus, where they localize to the slit diaphragm (SD) and contribute to filtration between blood and urine. Herein, we demonstrate that their Drosophila orthologs Kirre (Duf) and Sns are co-expressed within binucleate garland cell nephrocytes (GCNs) that contribute to detoxification of the insect hemolymph by uptake of molecules through an SD-like nephrocyte diaphragm (ND) into labyrinthine channels that are active sites of endocytosis. The functions of Kirre and Sns in the embryonic musculature, to mediate adhesion and fusion between myoblasts to form multinucleate muscle fibers, have been conserved in the GCNs, where they contribute to adhesion of GCNs in the ;garland' and to their fusion into binucleate cells. Sns and Kirre proteins localize to the ND at the entry point into the labyrinthine channels and, like their vertebrate counterparts, are essential for its formation. Knockdown of Kirre or Sns drastically reduces the number of NDs at the cell surface. These defects are associated with a decrease in uptake of large proteins, suggesting that the ND distinguishes molecules of different sizes and controls access to the channels. Moreover, mutations in the Sns fibronectin-binding or immunoglobulin domains lead to morphologically abnormal NDs and to reduced passage of proteins into the labyrinthine channels for uptake by endocytosis, suggesting a crucial and direct role for Sns in ND formation and function. These data reveal significant similarities between the insect ND and the SD in mammalian podocytes at the level of structure and function.
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Affiliation(s)
- Shufei Zhuang
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
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14
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Tight junctions and the regulation of gene expression. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:761-7. [PMID: 19121284 DOI: 10.1016/j.bbamem.2008.11.024] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 11/25/2008] [Accepted: 11/26/2008] [Indexed: 01/08/2023]
Abstract
Cell adhesion is a key regulator of cell differentiation. Cell interactions with neighboring cells and the extracellular matrix regulate gene expression, cell proliferation, polarity and apoptosis. Apical cell-cell junctions participate in these processes using different types of proteins, some of them exhibit nuclear and junctional localization and are called NACos for Nuclear Adhesion Complexes. Tight junctions are one type of such cell-cell junctions and several signaling complexes have been identified to associate with them. In general, expression of tight junction components suppresses proliferation to allow differentiation in a coordinated manner with adherens junctions and extracellular matrix adhesion. These tight junction components have been shown to affect several signaling and transcriptional pathways, and changes in the expression of tight junction proteins are associated with several disease conditions, such as cancer. Here, we will review how tight junction proteins participate in the regulation of gene expression and cell proliferation, as well as how they are regulated themselves by different mechanisms involved in gene expression and cell differentiation.
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15
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Furman DP, Bukharina TA. Genetic control of macrochaetae development in Drosophila melanogaster. Russ J Dev Biol 2008. [DOI: 10.1134/s1062360408040012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Seppa MJ, Johnson RI, Bao S, Cagan RL. Polychaetoid controls patterning by modulating adhesion in the Drosophila pupal retina. Dev Biol 2008; 318:1-16. [PMID: 18423436 DOI: 10.1016/j.ydbio.2008.02.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 01/31/2008] [Accepted: 02/02/2008] [Indexed: 11/28/2022]
Abstract
Correct cellular patterning is central to tissue morphogenesis, but the role of epithelial junctions in this process is not well-understood. The Drosophila pupal eye provides a sensitive and accessible model for testing the role of junction-associated proteins in cells that undergo dynamic and coordinated movements during development. Mutations in polychaetoid (pyd), the Drosophila homologue of Zonula Occludens-1, are characterized by two phenotypes visible in the adult fly: increased sensory bristle number and the formation of a rough eye produced by poorly arranged ommatidia. We found that Pyd was localized to the adherens junction in cells of the developing pupal retina. Reducing Pyd function in the pupal eye resulted in mis-patterning of the interommatidial cells and a failure to consistently switch cone cell contacts from an anterior-posterior to an equatorial-polar orientation. Levels of Roughest, DE-Cadherin and several other adherens junction-associated proteins were increased at the membrane when Pyd protein was reduced. Further, both over-expression and mutations in several junction-associated proteins greatly enhanced the patterning defects caused by reduction of Pyd. Our results suggest that Pyd modulates adherens junction strength and Roughest-mediated preferential cell adhesion.
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Affiliation(s)
- Midori J Seppa
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO 63110, USA
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17
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Yap AS, Crampton MS, Hardin J. Making and breaking contacts: the cellular biology of cadherin regulation. Curr Opin Cell Biol 2008; 19:508-14. [PMID: 17935963 DOI: 10.1016/j.ceb.2007.09.008] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 09/03/2007] [Accepted: 09/07/2007] [Indexed: 12/15/2022]
Abstract
Cadherin-mediated cell-cell interactions are dynamic processes, and cadherin function is tightly regulated in response to cellular context and signaling. Ultimately, cadherin regulation is likely to reflect the interplay between a range of fundamental cellular processes, including surface organization of receptors, cytoskeletal organization and cell trafficking, that are coordinated by signaling events. In this review we focus on recent advances in understanding how interplay with membrane trafficking and other cell-cell junctions can control cadherin function. The endocytosis of cadherins, and their post-internalization fate, influences surface expression and metabolic stability of these adhesion receptors. Similarly, at the surface, components of tight junctions provide a mode of cross-talk that regulates assembly of adherens junctions.
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Affiliation(s)
- Alpha S Yap
- Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
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18
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Furman D, Bukharina T. How Drosophila melanogaster Forms its Mechanoreceptors. Curr Genomics 2008; 9:312-23. [PMID: 19471605 PMCID: PMC2685642 DOI: 10.2174/138920208785133271] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 05/17/2008] [Accepted: 05/25/2008] [Indexed: 11/22/2022] Open
Abstract
A strictly determined number of external sensory organs, macrochaetes, acting as mechanoreceptors, are orderly located on drosophila head and body. Totally, they form the bristle pattern, which is a species-specific characteristic of drosophila.Each mechanoreceptor comprises four specialized cells derived from the single sensory organ precursor (SOP) cell. The conserved bristle pattern combined with a comparatively simple structure of each mechanosensory organ makes macrochaetes a convenient model for studying the formation spatial structures with a fixed number of elements at certain positions and the mechanism underlying cell differentiation.The macrochaete morphogenesis consists of three stages. At the first stage, the proneural clusters segregate from the massive of ectodermal cells of the wing imaginal disc. At the second stage, the SOP cell is determined and its position in the cluster is specified. At the third stage, the SOP cell undergoes two asymmetric divisions, and the daughter cells differentiate into the components of mechanoreceptor: shaft, socket, bipolar neuron, and sheath.The critical factor determining the neural pathway of cell development is the content of proneural proteins, products of the achaete-scute (AS-C) gene complex, reaching its maximum in the SOP cell.The experimental data on the main genes and their products involved in the control of bristle pattern formation are systematized. The roles of achaete-scute complex, EGFR and Notch signaling pathways, and selector genes in these processes are considered. An integral scheme describing the functioning of the system controlling macrochaete development in D. melanogaster is proposed based on analysis of literature data.
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Affiliation(s)
- D.P Furman
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, pr. Lavrentieva 10, Novosibirsk, 630090 Russia
- Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
| | - T.A Bukharina
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, pr. Lavrentieva 10, Novosibirsk, 630090 Russia
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Matter K, Balda MS. Epithelial tight junctions, gene expression and nucleo-junctional interplay. J Cell Sci 2007; 120:1505-11. [PMID: 17452622 DOI: 10.1242/jcs.005975] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Tight junctions are components of the junctional complex linking neighbouring epithelial cells and are important for barrier formation. Recent evidence suggests that tight junctions also participate in signal transduction mechanisms that regulate epithelial cell proliferation, gene expression, differentiation and morphogenesis. One important class of tight-junction-associated signal transduction mechanism is based on dual localisation of certain proteins both at junctions and in the nucleus. These proteins and their partners participate in various steps of gene expression, ranging from regulation of transcription and chromatin structure to mRNA processing and translation. In cancer tissues, their expression is often deregulated in a manner that suggests that tight junctions function as suppressors of proliferation and transformation.
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Affiliation(s)
- Karl Matter
- Division of Cell Biology, Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, UK.
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20
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Jung AC, Ribeiro C, Michaut L, Certa U, Affolter M. Polychaetoid/ZO-1 is required for cell specification and rearrangement during Drosophila tracheal morphogenesis. Curr Biol 2006; 16:1224-31. [PMID: 16782014 DOI: 10.1016/j.cub.2006.04.048] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 04/13/2006] [Accepted: 04/24/2006] [Indexed: 11/25/2022]
Abstract
The development of the complex network of epithelial tubes that ultimately forms the Drosophila tracheal system relies on cell migration, cell shape changes, cell rearrangements, cell differentiation, and branch fusion . Most of these events are controlled by a combination of distinct transcription factors and cell-cell signaling molecules, but few proteins that do not fall within these two functional classes have been associated with tracheal development. We show that the MAGUK protein Polychaetoid (Pyd/ZO-1), the Drosophila homolog of the junctional protein ZO-1 , plays a dual role in the formation of tracheal tubes. pyd/ZO-1 mutant embryos display branch fusion defects due to the lack of reliable determination of the fusion cell fate. In addition, pyd/ZO-1 mutant embryos show impaired cell intercalation in thin tracheal branches. Pyd/ZO-1 localizes to the adherens junctions (AJs) in tracheal cells and might thus play a direct role in the regulation of the dynamic state of the AJ during epithelial remodeling. Our study suggests that MAGUK proteins might play important roles during AJ remodeling in epithelial morphogenesis.
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Affiliation(s)
- Alain C Jung
- Abteilung Zellbiologie, Biozentrum der Universität Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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21
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Artero R, Furlong EE, Beckett K, Scott MP, Baylies M. Notch and Ras signaling pathway effector genes expressed in fusion competent and founder cells during Drosophila myogenesis. Development 2003; 130:6257-72. [PMID: 14602676 DOI: 10.1242/dev.00843] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Drosophila muscles originate from the fusion of two types of myoblasts, founder cells (FCs) and fusion-competent myoblasts (FCMs). To better understand muscle diversity and morphogenesis, we performed a large-scale gene expression analysis to identify genes differentially expressed in FCs and FCMs. We employed embryos derived from Toll10b mutants to obtain primarily muscle-forming mesoderm, and expressed activated forms of Ras or Notch to induce FC or FCM fate, respectively. The transcripts present in embryos of each genotype were compared by hybridization to cDNA microarrays. Among the 83 genes differentially expressed, we found genes known to be enriched in FCs or FCMs, such as heartless or hibris, previously characterized genes with unknown roles in muscle development, and predicted genes of unknown function. Our studies of newly identified genes revealed new patterns of gene expression restricted to one of the two types of myoblasts, and also striking muscle phenotypes. Whereas genes such as phyllopod play a crucial role during specification of particular muscles, others such as tartan are necessary for normal muscle morphogenesis.
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Affiliation(s)
- Ruben Artero
- Developmental Biology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
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22
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Carlton VEH, Harris BZ, Puffenberger EG, Batta AK, Knisely AS, Robinson DL, Strauss KA, Shneider BL, Lim WA, Salen G, Morton DH, Bull LN. Complex inheritance of familial hypercholanemia with associated mutations in TJP2 and BAAT. Nat Genet 2003; 34:91-6. [PMID: 12704386 DOI: 10.1038/ng1147] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2002] [Accepted: 03/28/2003] [Indexed: 12/12/2022]
Abstract
Familial hypercholanemia (FHC) is characterized by elevated serum bile acid concentrations, itching, and fat malabsorption. We show here that FHC in Amish individuals is associated with mutations in tight junction protein 2 (encoded by TJP2, also known as ZO-2) and bile acid Coenzyme A: amino acid N-acyltransferase (encoded by BAAT). The mutation of TJP2, which occurs in the first PDZ domain, reduces domain stability and ligand binding in vitro. We noted a morphological change in hepatic tight junctions. The mutation of BAAT, a bile acid-conjugating enzyme, abrogates enzyme activity; serum of individuals homozygous with respect to this mutation contains only unconjugated bile acids. Mutations in both TJP2 and BAAT may disrupt bile acid transport and circulation. Inheritance seems to be oligogenic, with genotype at BAAT modifying penetrance in individuals homozygous with respect to the mutation in TJP2.
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Affiliation(s)
- Victoria E H Carlton
- Liver Center Laboratory and Department of Medicine, San Francisco General Hospital, University of California San Francisco, California 94110, USA
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23
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Abstract
Tight junctions have long been regarded as simple barriers that separate compartments of different compositions, but recent research indicates that different types of signalling proteins and transduction pathways are associated with these junctions. They receive and convert signals from the cell interior to regulate junction assembly and function, and transmit signals to the cell interior to modulate gene expression and cell behaviour.
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Affiliation(s)
- Karl Matter
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
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24
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Abstract
Expression and functional analyses of Emc have demonstrated that it is a prototype for a protein required for multiple processes in development. Initially characterized as a negative regulator of sensory organ development, it was later found to regulate many other developmental processes and cell proliferation. Its ability to block the function of bHLH proteins by forming heterodimers, which are ineffective in DNA binding, accounts for the role of Emc in preventing the acquisition of several cell fates which are under the control of bHLH proteins. However, while maintaining this repressive molecular mechanism, emc also appears to act as a positive regulator of differentiation.
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Affiliation(s)
- S Campuzano
- Centro de Biología Molecular Severo Ochoa, Cantoblanco, 28049 Madrid, Spain.
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25
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Wei X, Ellis HM. Localization of the Drosophila MAGUK protein Polychaetoid is controlled by alternative splicing. Mech Dev 2001; 100:217-31. [PMID: 11165479 DOI: 10.1016/s0925-4773(00)00550-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The Drosophila membrane-associated guanylate kinase (MAGUK) protein Polychaetoid (Pyd) is required for dorsal closure of the embryo, sensory organ patterning, and cell fate specification in the developing eye. We demonstrate that pyd is alternatively spliced resulting in two isoforms that differ by the presence or absence of exon 6. To determine the role of alternative splicing in Pyd function, we generated antibodies specific for each isoform. We find that the exon 6(+) form of Pyd is localized at adherens junctions of embryonic and imaginal epithelia, while the exon 6(-) form is distributed broadly along the lateral membrane. These results suggest that localization of Pyd is controlled by alternative splicing and raise the possibility that exon 6 represents a distinct protein-protein interaction domain.
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Affiliation(s)
- X Wei
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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26
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Berezovska O, Frosch M, McLean P, Knowles R, Koo E, Kang D, Shen J, Lu FM, Lux SE, Tonegawa S, Hyman BT. The Alzheimer-related gene presenilin 1 facilitates notch 1 in primary mammalian neurons. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 69:273-80. [PMID: 10366748 DOI: 10.1016/s0169-328x(99)00119-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The normal functional neurobiology of the Alzheimer's disease (AD) related gene presenilin 1 (PS1) is unknown. One clue comes from a genetic screen of Caenorhabditis elegans, which reveals that the presenilin homologue sel-12 facilitates lin-12 function [D. Levitan, I. Greenwald, Facilitation of lin-12-mediated signalling by sel-12, a Caenorhabditis elegans S182 Alzheimer's disease gene, Nature 377 (1995) 351-355]. The mammalian homologue of lin-12, Notch1, is a transmembrane receptor that plays an important role in cell fate decisions during development, including neurogenesis, but does not have a known function in fully differentiated cells. To better understand the potential role of Notch1 in mammalian postmitotic neurons and to test the hypothesis that Notch and PS 1 interact, we studied the effect of Notch1 transfection on neurite outgrowth in primary cultures of hippocampal/cortical neurons. We demonstrate that Notch1 inhibits neurite extension, and thus has a function in postmitotic mature neurons in the mammalian CNS. Furthermore, we present evidence demonstrating that there is a functional interaction between PS1 and Notch1 in mammalian neurons, analogous to the sel-12/lin-12 interaction in vulval development in C. elegans [D. Levitan, T. Doyle, D. Brousseau, M. Lee, G. Thinakaran, H. Slunt, S. Sisodia, I. Greenwald, Assessment of normal and mutant human presenilin function in Caenorhabditis elegans, Proc. Natl. Acad. Sci. U.S.A. 93 (1996) 14940-14944; D. Levitan, I. Greenwald, Effect of Sel-12 presenilin on Lin-12 localization and function in Caenorhabditis elegans, Development, 125 (1998) 3599-3606]. The inhibitory effect of Notch1 on neurite outgrowth is markedly attenuated in neurons from PS1 knockout mice, and enhanced in neurons from transgenic mice overexpressing wild type PS1, but not mutant PS1. These data suggest that PS1 facilitates Notch1 function in mammalian neurons, and support the hypothesis that a functional interaction exists between PS1 and Notch1 in postmitotic mammalian neurons.
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Affiliation(s)
- O Berezovska
- Alzheimer Research Unit, Massachusetts General Hospital, Neurology Service, Rm. 6405, 149 13th Street, Charlestown, MA 02129, USA
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Takahashi K, Matsuo T, Katsube T, Ueda R, Yamamoto D. Direct binding between two PDZ domain proteins Canoe and ZO-1 and their roles in regulation of the jun N-terminal kinase pathway in Drosophila morphogenesis. Mech Dev 1998; 78:97-111. [PMID: 9858699 DOI: 10.1016/s0925-4773(98)00151-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
During Drosophila embryogenesis, the ventral epidermis dorsally expands and the left and right epithelial sheets meet and fuse along the dorsal midline. For this dorsal closure to occur, two PDZ domain proteins, Cno and ZO-1, are required. The dorsal epidermis remains open when the expression of ZO-1 and Cno are reduced simultaneously by hypomorphic mutations in the relevant loci. ZO-1 and Cno colocalize at adherens junctions in embryonic epithelia, and form a protein complex upon binding to each other. Genetic analysis showed that Cno is involved in the Jun N-terminal kinase (JNK) pathway for dorsal closure, as a modulator acting upstream of, or in parallel with, the small GTPase Drac1. The ZO-1-Cno complex may be involved in dynamic changes in cytoskeletal organization and cell adhesion during morphogenetic events associated with dorsal closure in the Drosophila embryo.
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Affiliation(s)
- K Takahashi
- Mitsubishi Kasei Institute of Life Sciences, Machida, Tokyo 194-8511, Japan
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