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Vossen C, Schmidt P, Wunderlich CM, Mittenbühler MJ, Tapken C, Wienand P, Mirabella PN, Cabot L, Schumacher AL, Folz-Donahue K, Kukat C, Voigt I, Brüning JC, Fenselau H, Wunderlich FT. An Approach to Intersectionally Target Mature Enteroendocrine Cells in the Small Intestine of Mice. Cells 2024; 13:102. [PMID: 38201306 PMCID: PMC10778503 DOI: 10.3390/cells13010102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/18/2023] [Accepted: 01/02/2024] [Indexed: 01/12/2024] Open
Abstract
Enteroendocrine cells (EECs) constitute only a small proportion of Villin-1 (Vil1)-expressing intestinal epithelial cells (IECs) of the gastrointestinal tract; yet, in sum, they build the largest endocrine organ of the body, with each of them storing and releasing a distinct set of peptides for the control of feeding behavior, glucose metabolism, and gastrointestinal motility. Like all IEC types, EECs are continuously renewed from intestinal stem cells in the crypt base and terminally differentiate into mature subtypes while moving up the crypt-villus axis. Interestingly, EECs adjust their hormonal secretion according to their migration state as EECs receive altering differentiation signals along the crypt-villus axis and thus undergo functional readaptation. Cell-specific targeting of mature EEC subtypes by specific promoters is challenging because the expression of EEC-derived peptides and their precursors is not limited to EECs but are also found in other organs, such as the brain (e.g., Cck and Sst) as well as in the pancreas (e.g., Sst and Gcg). Here, we describe an intersectional genetic approach that enables cell type-specific targeting of functionally distinct EEC subtypes by combining a newly generated Dre-recombinase expressing mouse line (Vil1-2A-DD-Dre) with multiple existing Cre-recombinase mice and mouse strains with rox and loxP sites flanked stop cassettes for transgene expression. We found that transgene expression in triple-transgenic mice is highly specific in I but not D and L cells in the terminal villi of the small intestine. The targeting of EECs only in terminal villi is due to the integration of a defective 2A separating peptide that, combined with low EEC intrinsic Vil1 expression, restricts our Vil1-2A-DD-Dre mouse line and the intersectional genetic approach described here only applicable for the investigation of mature EEC subpopulations.
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Affiliation(s)
- Christian Vossen
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Patricia Schmidt
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Claudia Maria Wunderlich
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Melanie Joyce Mittenbühler
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Claas Tapken
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Peter Wienand
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Paul Nicolas Mirabella
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Research Group Synaptic Transmission in Energy Homeostasis, Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
| | - Leonie Cabot
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Research Group Synaptic Transmission in Energy Homeostasis, Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
| | - Anna-Lena Schumacher
- FACS & Imaging Core Facility, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany; (A.-L.S.)
| | - Kat Folz-Donahue
- FACS & Imaging Core Facility, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany; (A.-L.S.)
| | - Christian Kukat
- FACS & Imaging Core Facility, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany; (A.-L.S.)
| | - Ingo Voigt
- Transgenic Core Facility, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany;
| | - Jens C. Brüning
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
- Department of neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
| | - Henning Fenselau
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Research Group Synaptic Transmission in Energy Homeostasis, Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
| | - F. Thomas Wunderlich
- Obesity and Cancer Research Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes, and Preventive Medicine (PEDP), University Hospital Cologne, 50924 Cologne, Germany; (P.N.M.); (J.C.B.); (H.F.)
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
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2
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Morales EA, Arnaiz C, Krystofiak ES, Zanic M, Tyska MJ. Mitotic Spindle Positioning (MISP) is an actin bundler that selectively stabilizes the rootlets of epithelial microvilli. Cell Rep 2022; 39:110692. [PMID: 35443169 PMCID: PMC9097542 DOI: 10.1016/j.celrep.2022.110692] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 01/20/2022] [Accepted: 03/24/2022] [Indexed: 11/11/2022] Open
Abstract
Microvilli are conserved actin-based surface protrusions that have been repurposed throughout evolution to fulfill diverse cell functions. In the case of transporting epithelia, microvilli are supported by a core of actin filaments bundled in parallel by villin, fimbrin, and espin. Remarkably, microvilli biogenesis persists in mice lacking all three of these factors, suggesting the existence of unknown bundlers. We identified Mitotic Spindle Positioning (MISP) as an actin-binding factor that localizes specifically to the rootlet end of the microvillus. MISP promotes rootlet elongation in cells, and purified MISP exhibits potent filament bundling activity in vitro. MISP-bundled filaments also recruit fimbrin, which further elongates and stabilizes bundles. MISP confinement to the rootlet is enforced by ezrin, which prevents decoration of the membrane-wrapped distal end of the core bundle. These discoveries reveal how epithelial cells optimize apical membrane surface area and offer insight on the remarkable robustness of microvilli biogenesis. Morales et al. identify Mitotic Spindle Positioning (MISP) as an actin bundler in the rootlets of epithelial microvilli. MISP cooperates with other bundlers, and its rootlet-specific localization is enforced by membrane-actin linker ezrin. These findings illuminate mechanisms that drive the assembly and compartmentalization of actin bundle-supported protrusions.
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Affiliation(s)
- E Angelo Morales
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Cayetana Arnaiz
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Evan S Krystofiak
- Cell Imaging Shared Resource, Vanderbilt University, Nashville, TN 37232, USA
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.
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3
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Chen L, Luo S, Dupre A, Vasoya RP, Parthasarathy A, Aita R, Malhotra R, Hur J, Toke NH, Chiles E, Yang M, Cao W, Flores J, Ellison CE, Gao N, Sahota A, Su X, Bonder EM, Verzi MP. The nuclear receptor HNF4 drives a brush border gene program conserved across murine intestine, kidney, and embryonic yolk sac. Nat Commun 2021; 12:2886. [PMID: 34001900 PMCID: PMC8129143 DOI: 10.1038/s41467-021-22761-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 03/24/2021] [Indexed: 12/12/2022] Open
Abstract
The brush border is comprised of microvilli surface protrusions on the apical surface of epithelia. This specialized structure greatly increases absorptive surface area and plays crucial roles in human health. However, transcriptional regulatory networks controlling brush border genes are not fully understood. Here, we identify that hepatocyte nuclear factor 4 (HNF4) transcription factor is a conserved and important regulator of brush border gene program in multiple organs, such as intestine, kidney and yolk sac. Compromised brush border gene signatures and impaired transport were observed in these tissues upon HNF4 loss. By ChIP-seq, we find HNF4 binds and activates brush border genes in the intestine and kidney. H3K4me3 HiChIP-seq identifies that HNF4 loss results in impaired chromatin looping between enhancers and promoters at gene loci of brush border genes, and instead enhanced chromatin looping at gene loci of stress fiber genes in the intestine. This study provides comprehensive transcriptional regulatory mechanisms and a functional demonstration of a critical role for HNF4 in brush border gene regulation across multiple murine epithelial tissues.
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Affiliation(s)
- Lei Chen
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA.
- Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ, USA.
| | - Shirley Luo
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Abigail Dupre
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Roshan P Vasoya
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Aditya Parthasarathy
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Rohit Aita
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Raj Malhotra
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Joseph Hur
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Natalie H Toke
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Eric Chiles
- Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ, USA
| | - Min Yang
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Weihuan Cao
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Juan Flores
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Christopher E Ellison
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Nan Gao
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Amrik Sahota
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Xiaoyang Su
- Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ, USA
- Department of Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - Edward M Bonder
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Michael P Verzi
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA.
- Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ, USA.
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition & Health, Rutgers University, New Brunswick, NJ, USA.
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4
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Pintér R, Huber T, Bukovics P, Gaszler P, Vig AT, Tóth MÁ, Gazsó-Gerhát G, Farkas D, Migh E, Mihály J, Bugyi B. The Activities of the Gelsolin Homology Domains of Flightless-I in Actin Dynamics. Front Mol Biosci 2020; 7:575077. [PMID: 33033719 PMCID: PMC7509490 DOI: 10.3389/fmolb.2020.575077] [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: 06/22/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022] Open
Abstract
Flightless-I is a unique member of the gelsolin superfamily alloying six gelsolin homology domains and leucine-rich repeats. Flightless-I is an established regulator of the actin cytoskeleton, however, its biochemical activities in actin dynamics are still largely elusive. To better understand the biological functioning of Flightless-I we studied the actin activities of Drosophila Flightless-I by in vitro bulk fluorescence spectroscopy and single filament fluorescence microscopy, as well as in vivo genetic approaches. Flightless-I was found to interact with actin and affects actin dynamics in a calcium-independent fashion in vitro. Our work identifies the first three gelsolin homology domains (1–3) of Flightless-I as the main actin-binding site; neither the other three gelsolin homology domains (4–6) nor the leucine-rich repeats bind actin. Flightless-I inhibits polymerization by high-affinity (∼nM) filament barbed end capping, moderately facilitates nucleation by low-affinity (∼μM) monomer binding, and does not sever actin filaments. Our work reveals that in the presence of profilin Flightless-I is only able to cap actin filament barbed ends but fails to promote actin assembly. In line with the in vitro data, while gelsolin homology domains 4–6 have no effect on in vivo actin polymerization, overexpression of gelsolin homology domains 1–3 prevents the formation of various types of actin cables in the developing Drosophila egg chambers. We also show that the gelsolin homology domains 4–6 of Flightless-I interact with the C-terminus of Drosophila Disheveled-associated activator of morphogenesis formin and negatively regulates its actin assembly activity.
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Affiliation(s)
- Réka Pintér
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Tamás Huber
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Bukovics
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Gaszler
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Andrea Teréz Vig
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Mónika Ágnes Tóth
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Gabriella Gazsó-Gerhát
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary.,Faculty of Science and Informatics, Doctoral School in Biology, University of Szeged, Szeged, Hungary
| | - Dávid Farkas
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary
| | - Ede Migh
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary
| | - József Mihály
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary
| | - Beáta Bugyi
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Center, Pécs, Hungary
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George SP, Esmaeilniakooshkghazi A, Roy S, Khurana S. F-actin-bundling sites are conserved in proteins with villin-type headpiece domains. Mol Biol Cell 2020; 31:1857-1866. [PMID: 32520642 PMCID: PMC7525818 DOI: 10.1091/mbc.e20-02-0158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/15/2020] [Accepted: 06/04/2020] [Indexed: 11/17/2022] Open
Abstract
Villin is a major actin-bundling protein that assembles the brush border of intestinal and renal epithelial cells. The villin "headpiece" domain and the actin-binding residues within it regulate its actin-bundling function. Substantial experimental and theoretical information about the three-dimensional structure of the isolated villin headpiece, including a description of the actin-binding residues within the headpiece, is available. Despite that, the actin-bundling site in the full-length (FL) villin protein remains unidentified. We used this existing villin headpiece nuclear magnetic resonance data and performed mutational analysis and functional assays to identify the actin-bundling site in FL human villin protein. By careful evaluation of these conserved actin-binding residues in human advillin protein, we demonstrate their functional significance in the over 30 proteins that contain a villin-type headpiece domain. Our study is the first that combines the available structural data on villin headpiece with functional assays to identify the actin-binding residues in FL villin that regulate its filament-bundling activity. Our findings could have wider implications for other actin-bundling proteins that contain a villin-type headpiece domain.
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Affiliation(s)
- Sudeep P. George
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77044
| | | | - Swati Roy
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77044
| | - Seema Khurana
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77044
- Department of Allied Health, Baylor College of Medicine, Houston, TX 77030
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6
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Mouse intestinal tuft cells express advillin but not villin. Sci Rep 2020; 10:8877. [PMID: 32483224 PMCID: PMC7264147 DOI: 10.1038/s41598-020-65469-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 03/06/2020] [Indexed: 12/26/2022] Open
Abstract
Tuft (or brush) cells are solitary chemosensory cells scattered throughout the epithelia of the respiratory and alimentary tract. The actin-binding protein villin (Vil1) is used as a marker of tuft cells and the villin promoter is frequently used to drive expression of the Cre recombinase in tuft cells. While there is widespread agreement about the expression of villin in tuft cells there are several disagreements related to tuft cell lineage commitment and function. We now show that many of these inconsistencies could be resolved by our surprising finding that intestinal tuft cells, in fact, do not express villin protein. Furthermore, we show that a related actin-binding protein, advillin which shares 75% homology with villin, has a tuft cell restricted expression in the gastrointestinal epithelium. Our study identifies advillin as a marker of tuft cells and provides a mechanism for driving gene expression in tuft cells but not in other epithelial cells of the gastrointestinal tract. Our findings fundamentally change the way we identify and study intestinal tuft cells.
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7
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Başak K, Demir MG, Altıntoprak N, Aydın S. The Effect of Antioxidant Agents on Cisplatin-Induced Laryngeal Histological Alterations in Rats. J Med Food 2020; 24:197-204. [PMID: 32423279 DOI: 10.1089/jmf.2019.0235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The larynx-related adverse effects that depend on cisplatin decrease patient comfort and many antioxidants have been used to eliminate these side effects. We aimed to identify the laryngeal mucosal changes imposed by cisplatin and investigated whether antioxidants, and their healing effects on these changes, may help reduce laryngeal complications in patients resulting from adverse effects in the larynx. A rat model was designed to evaluate the effects of cisplatin on the larynx and the protective role of antioxidants. Single-dose cisplatin was given both intraperitoneally alone and additionally administered with p-coumaric acid, melatonin, resveratrol, vitamin D, and oleic acid over 5 days. Whole larynges were dissected and evaluated histologically, histochemically, and immunohistochemically. Varying degrees of mucosal changes cisplatin group, but neither erosion nor an ulcer was observed. Numerous variable histological effects of antioxidants were observed on cisplatin exposed laryngeal mucosa. The most obvious effects of cisplatin were edema. The results of the study showed that resveratrol was the most preventive antioxidant agent against cisplatin-dependent mucosal changes. The highest increase in the Ki67 index was in the oleic acid group. Vitamin D increased stromal cyclooxygenase-2 expression that may have an effect on increasing mucosal damage.
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Affiliation(s)
- Kayhan Başak
- Department of Pathology, University of Health Science, Kartal Dr. Lütfi Kırdar Research Hospital, İstanbul, Turkey
| | - Mehmet Gökhan Demir
- Department of Oral and Maxillofacial Surgery, İstanbul Faculty of Medicine, İstanbul University, İstanbul, Turkey
| | | | - Sedat Aydın
- Department of Oral and Maxillofacial Surgery, İstanbul Faculty of Medicine, İstanbul University, İstanbul, Turkey
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8
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Transcriptional control of lung alveolar type 1 cell development and maintenance by NK homeobox 2-1. Proc Natl Acad Sci U S A 2019; 116:20545-20555. [PMID: 31548395 DOI: 10.1073/pnas.1906663116] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The extraordinarily thin alveolar type 1 (AT1) cell constitutes nearly the entire gas exchange surface and allows passive diffusion of oxygen into the blood stream. Despite such an essential role, the transcriptional network controlling AT1 cells remains unclear. Using cell-specific knockout mouse models, genomic profiling, and 3D imaging, we found that NK homeobox 2-1 (Nkx2-1) is expressed in AT1 cells and is required for the development and maintenance of AT1 cells. Without Nkx2-1, developing AT1 cells lose 3 defining features-molecular markers, expansive morphology, and cellular quiescence-leading to alveolar simplification and lethality. NKX2-1 is also cell-autonomously required for the same 3 defining features in mature AT1 cells. Intriguingly, Nkx2-1 mutant AT1 cells activate gastrointestinal (GI) genes and form dense microvilli-like structures apically. Single-cell RNA-seq supports a linear transformation of Nkx2-1 mutant AT1 cells toward a GI fate. Whole lung ChIP-seq shows NKX2-1 binding to 68% of genes that are down-regulated upon Nkx2-1 deletion, including 93% of known AT1 genes, but near-background binding to up-regulated genes. Our results place NKX2-1 at the top of the AT1 cell transcriptional hierarchy and demonstrate remarkable plasticity of an otherwise terminally differentiated cell type.
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9
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Apodaca G. Role of Polarity Proteins in the Generation and Organization of Apical Surface Protrusions. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a027813. [PMID: 28264821 DOI: 10.1101/cshperspect.a027813] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protruding from the apical surfaces of epithelial cells are specialized structures, including cilia, microplicae, microvilli, and stereocilia. These contribute to epithelial function by cushioning the apical surface, by amplifying its surface area to facilitate nutrient absorption, and by promoting sensory transduction and barrier function. Despite these important roles, and the diseases that result when their formation is perturbed, there remain significant gaps in our understanding of the biogenesis of apical protrusions, or the pathways that promote their organization and orientation once at the apical surface. Here, I review some general aspects of these apical structures, and then discuss our current understanding of their formation and organization with respect to proteins that specify apicobasolateral polarity and planar cell polarity.
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Affiliation(s)
- Gerard Apodaca
- Department of Medicine Renal-Electrolyte Division and the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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10
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Klunder LJ, Faber KN, Dijkstra G, van IJzendoorn SCD. Mechanisms of Cell Polarity-Controlled Epithelial Homeostasis and Immunity in the Intestine. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a027888. [PMID: 28213466 DOI: 10.1101/cshperspect.a027888] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Intestinal epithelial cell polarity is instrumental to maintain epithelial homeostasis and balance communications between the gut lumen and bodily tissue, thereby controlling the defense against gastrointestinal pathogens and maintenance of immune tolerance to commensal bacteria. In this review, we highlight recent advances with regard to the molecular mechanisms of cell polarity-controlled epithelial homeostasis and immunity in the human intestine.
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Affiliation(s)
- Leon J Klunder
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, the Netherlands
| | - Klaas Nico Faber
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, the Netherlands
| | - Gerard Dijkstra
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, the Netherlands
| | - Sven C D van IJzendoorn
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, the Netherlands
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11
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Abstract
The vertebrate small intestine requires an enormous surface area to effectively absorb nutrients from food. Morphological adaptations required to establish this extensive surface include generation of an extremely long tube and convolution of the absorptive surface of the tube into villi and microvilli. In this Review, we discuss recent findings regarding the morphogenetic and molecular processes required for intestinal tube elongation and surface convolution, examine shared and unique aspects of these processes in different species, relate these processes to known human maladies that compromise absorptive function and highlight important questions for future research.
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Affiliation(s)
- Katherine D Walton
- Cell and Developmental Biology Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Andrew M Freddo
- Cell and Developmental Biology Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Sha Wang
- Cell and Developmental Biology Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Deborah L Gumucio
- Cell and Developmental Biology Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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12
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Abstract
The brush border on the apical surface of enterocytes is a highly specialized structure well-adapted for efficient digestion and nutrient transport, whilst at the same time providing a protective barrier for the intestinal mucosa. The brush border is constituted of a densely ordered array of microvilli, protrusions of the plasma membrane, which are supported by actin-based microfilaments and interacting proteins and anchored in an apical network of actomyosin and intermediate filaments, the so-called terminal web. The highly dynamic, specialized apical domain is both an essential partner for the gut microbiota and an efficient signalling platform that enables adaptation to physiological stimuli from the external and internal milieu. Nevertheless, genetic alterations or various pathological stresses, such as infection, inflammation, and mechanical or nutritional alterations, can jeopardize this equilibrium and compromise intestinal functions. Long-time neglected, the intestinal brush-border shall be enlightening again as the central actor of the complex but essential intestinal homeostasis. Here, we review the processes and components involved in brush border organization and discuss pathological mechanisms that can induce brush border defects and their physiological consequences.
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14
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Actin reorganization as the molecular basis for the regulation of apoptosis in gastrointestinal epithelial cells. Cell Death Differ 2012; 19:1514-24. [PMID: 22421965 DOI: 10.1038/cdd.2012.28] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The gastrointestinal (GI) epithelium is a rapidly renewing tissue in which apoptosis represents part of the overall homeostatic process. Regulation of apoptosis in the GI epithelium is complex with a precise relationship between cell position and apoptosis. Apoptosis occurs spontaneously and in response to radiation and cytotoxic drugs at the base of the crypts. By contrast, the villus epithelial cells are extremely resistant to apoptosis. The molecular mechanism underlying this loss of function of villus epithelial cells to undergo apoptosis shortly after their exit from the crypt is unknown. In this study we demonstrate for the first time, that deletion of two homologous actin-binding proteins, villin and gelsolin renders villus epithelial cells extremely sensitive to apoptosis. Ultrastructural analysis of the villin-gelsolin(-/-) double-knockout mice shows an abnormal accumulation of damaged mitochondria demonstrating that villin and gelsolin function on an early step in the apoptotic signaling at the level of the mitochondria. A characterization of functional and ligand-binding mutants demonstrate that regulated changes in actin dynamics determined by the actin severing activities of villin and gelsolin are required to maintain cellular homeostasis. Our study provides a molecular basis for the regulation of apoptosis in the GI epithelium and identifies cell biological mechanisms that couple changes in actin dynamics to apoptotic cell death.
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15
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Soplop NH, Cheng YS, Kramer SG. Roundabout is required in the visceral mesoderm for proper microvillus length in the hindgut epithelium. Dev Dyn 2012; 241:759-69. [PMID: 22334475 DOI: 10.1002/dvdy.23749] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2012] [Indexed: 11/11/2022] Open
Abstract
INTRODUCTION In this study we examined Roundabout signaling in the Drosophila embryonic hindgut. RESULTS Slit and its receptors Roundabout (Robo) and Roundabout 2 (Robo2) localize to discrete regions in the hindgut epithelium and surrounding visceral mesoderm. Loss of robo, robo2 or slit did not disrupt overall hindgut patterning. However, slit and robo mutants showed a decrease in microvillus length on the boundary cells of the hindgut epithelium. Rescue and overexpression analysis revealed that robo is specifically required in the visceral mesoderm for correct microvillus length in the underlying hindgut epithelium. Expression of robo in the visceral mesoderm of robo mutant embryos restored normal microvillus length, while overexpression of robo resulted in an increase in microvillus length. Microvillus length was also increased in robo2 mutants suggesting that robo2 may antagonize robo function in the hindgut. CONCLUSION Together, these results establish a novel, dose-dependent role for Robo in regulating microvilli growth and provide in vivo evidence for the role of the visceral mesoderm in controlling morphological changes in the underlying intestinal epithelium.
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Affiliation(s)
- Nadine H Soplop
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854-8020, USA
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16
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Revenu C, Ubelmann F, Hurbain I, El-Marjou F, Dingli F, Loew D, Delacour D, Gilet J, Brot-Laroche E, Rivero F, Louvard D, Robine S. A new role for the architecture of microvillar actin bundles in apical retention of membrane proteins. Mol Biol Cell 2011; 23:324-36. [PMID: 22114352 PMCID: PMC3258176 DOI: 10.1091/mbc.e11-09-0765] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The bundled architecture of actin filaments is not needed for intestinal microvillar morphogenesis, as shown in knockout mice devoid of microvillar actin-bundling proteins. This architecture is essential for the apical anchorage of digestive proteins, probably via the recruitment of key players in apical retention, such as myosin-1a, and, as a result, for intestinal physiology. Actin-bundling proteins are identified as key players in the morphogenesis of thin membrane protrusions. Until now, functional redundancy among the actin-bundling proteins villin, espin, and plastin-1 has prevented definitive conclusions regarding their role in intestinal microvilli. We report that triple knockout mice lacking these microvillar actin-bundling proteins suffer from growth delay but surprisingly still develop microvilli. However, the microvillar actin filaments are sparse and lack the characteristic organization of bundles. This correlates with a highly inefficient apical retention of enzymes and transporters that accumulate in subapical endocytic compartments. Myosin-1a, a motor involved in the anchorage of membrane proteins in microvilli, is also mislocalized. These findings illustrate, in vivo, a precise role for local actin filament architecture in the stabilization of apical cargoes into microvilli. Hence, the function of actin-bundling proteins is not to enable microvillar protrusion, as has been assumed, but to confer the appropriate actin organization for the apical retention of proteins essential for normal intestinal physiology.
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Affiliation(s)
- Céline Revenu
- Unité Mixte de Recherche 144, Centre National de la Recherche Scientifique, Institut Curie, 75248 Paris, Cedex 05, France.
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17
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Cheung R, Kelly J, Macleod RJ. Regulation of villin by wnt5a/ror2 signaling in human intestinal cells. Front Physiol 2011; 2:58. [PMID: 21949508 PMCID: PMC3171703 DOI: 10.3389/fphys.2011.00058] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 08/19/2011] [Indexed: 11/13/2022] Open
Abstract
Regulation of expression of the intestinal epithelial actin-binding protein, villin, is poorly understood. The aim of this study was to determine whether Wnt5a stimulates Ror2 in intestinal epithelia caused transient increases in phospho-ERK1/2 (pERK1/2) and subsequently increased expression of villin transcript and protein. To demonstrate Wnt5a-Ror2 regulation of villin expression, we overexpressed wild-type, truncated, or mutant Ror2 constructs in HT29 adenocarcinoma cells and non-transformed fetally derived human intestinal epithelial cells, added conditioned media containing Wnt5a and measured changes in ERK1/2 phosphorylation, villin amplicons, and protein expression by RT-PCR and Western blot techniques. Wnt5a addition caused a transient increase in pERK1/2, which was maximal at 10 min but extinguished by 30 min. Transient transfection with a siRNA duplex against Ror2 diminished Ror2 amplicons and protein and reduced the extent of pERK1/2 activation. Structure-function analysis revealed that the deletion of the cysteine-rich, kringle, or tyrosine kinase domain or substitution mutations of tyrosine residues in the intracellular Ser/Thr-1 region of Ror2 prevented the Wnt5a stimulation of pERK1/2. Deletion of the intracellular proline and serine/threonine-rich regions of Ror2 had no effect on Wnt5a stimulation of pERK1/2. The increase in villin expression was blocked by pharmacological inhibition of MEK-1 and casein kinase 1, but not by PKC and p38 inhibitors. Neither Wnt3a nor epidermal growth factor addition caused increases in villin protein. Our findings suggest that Wnt5a/Ror2 signaling can regulate villin expression in the intestine.
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Affiliation(s)
- Rebecca Cheung
- Department of Physiology, Queen's University Kingston, ON, Canada
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18
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Shi Z, Dragin N, Gálvez-Peralta M, Jorge-Nebert LF, Miller ML, Wang B, Nebert DW. Organ-specific roles of CYP1A1 during detoxication of dietary benzo[a]pyrene. Mol Pharmacol 2010; 78:46-57. [PMID: 20371670 DOI: 10.1124/mol.110.063438] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are widely distributed environmental toxicants derived from sources that include cigarette smoke, petroleum distillation, gas- and diesel-engine exhaust, and charcoal-grilled food. The gastrointestinal tract is the principal route of PAH exposures, even when inhaled. The most thoroughly studied prototype of PAHs is benzo[a]pyrene (BaP), well known to be toxic, mutagenic, and carcinogenic in various tissues and cell types. This lab has previously shown that Cyp1a1(-/-) global knockout mice treated by oral administration of BaP die at 28 to 32 days with immunosuppression, whereas wild-type mice remain healthy for 1 year on high BaP doses (125 mg/kg/day). Thus, for oral BaP, CYP1A1 is more important in detoxication than in metabolic activation. After several days of oral BaP, we found surprisingly low CYP1A1 levels in liver, compared with that in small intestine; we postulated that this finding might reflect efficient detoxication of oral BaP in proximal small intestine such that significant amounts of the inducer BaP no longer reach the liver. In the present study, many parameters were therefore compared in wild-type, Cyp1a1(-/-) global knockout, intestinal epithelial cell-specific Cyp1a1 knockout, and hepatocyte-specific Cyp1a1 knockout mice as a function of long-term oral exposure to BaP. The peak of CYP1A1 (mRNA, protein) expression in liver occurred at 12 h, whereas highly induced CYP1A1 in small intestine persisted throughout the 30-day experiment. Hepatocyte-specific Cyp1a1 knockout mice remained as healthy as wild-type mice; intestinal epithelial cell-specific Cyp1a1 knockout mice behaved like Cyp1a1(-/-) mice, dying with immunosuppression approximately 30 days on oral BaP. We conclude that small intestine CYP1A1, and not liver CYP1A1, is critically important in oral BaP detoxication.
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Affiliation(s)
- Zhanquan Shi
- Department of Environmental Health, University of Cincinnati Medical Center, P.O. Box 670056, Cincinnati, OH 45267-0056, USA
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19
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Brown JW, McKnight CJ. Molecular model of the microvillar cytoskeleton and organization of the brush border. PLoS One 2010; 5:e9406. [PMID: 20195380 PMCID: PMC2827561 DOI: 10.1371/journal.pone.0009406] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 02/01/2010] [Indexed: 01/22/2023] Open
Abstract
Background Brush border microvilli are ∼1-µm long finger-like projections emanating from the apical surfaces of certain, specialized absorptive epithelial cells. A highly symmetric hexagonal array of thousands of these uniformly sized structures form the brush border, which in addition to aiding in nutrient absorption also defends the large surface area against pathogens. Here, we present a molecular model of the protein cytoskeleton responsible for this dramatic cellular morphology. Methodology/Principal Findings The model is constructed from published crystallographic and microscopic structures reported by several groups over the last 30+ years. Our efforts resulted in a single, unique, self-consistent arrangement of actin, fimbrin, villin, brush border myosin (Myo1A), calmodulin, and brush border spectrin. The central actin core bundle that supports the microvillus is nearly saturated with fimbrin and villin cross-linkers and has a density similar to that found in protein crystals. The proposed model accounts for all major proteinaceous components, reproduces the experimentally determined stoichiometry, and is consistent with the size and morphology of the biological brush border membrane. Conclusions/Significance The model presented here will serve as a structural framework to explain many of the dynamic cellular processes occurring over several time scales, such as protein diffusion, association, and turnover, lipid raft sorting, membrane deformation, cytoskeletal-membrane interactions, and even effacement of the brush border by invading pathogens. In addition, this model provides a structural basis for evaluating the equilibrium processes that result in the uniform size and structure of the highly dynamic microvilli.
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Affiliation(s)
- Jeffrey W. Brown
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - C. James McKnight
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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20
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Grimm-Günter EMS, Revenu C, Ramos S, Hurbain I, Smyth N, Ferrary E, Louvard D, Robine S, Rivero F. Plastin 1 binds to keratin and is required for terminal web assembly in the intestinal epithelium. Mol Biol Cell 2009; 20:2549-62. [PMID: 19321664 DOI: 10.1091/mbc.e08-10-1030] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Plastin 1 (I-plastin, fimbrin) along with villin and espin is a prominent actin-bundling protein of the intestinal brush border microvilli. We demonstrate here that plastin 1 accumulates in the terminal web and interacts with keratin 19, possibly contributing to anchoring the rootlets to the keratin network. This prompted us to investigate the importance of plastin 1 in brush border assembly. Although in vivo neither villin nor espin is required for brush border structure, plastin 1-deficient mice have conspicuous ultrastructural alterations: microvilli are shorter and constricted at their base, and, strikingly, their core actin bundles lack true rootlets. The composition of the microvilli themselves is apparently normal, whereas that of the terminal web is profoundly altered. Although the plastin 1 knockout mice do not show any overt gross phenotype and present a normal intestinal microanatomy, the alterations result in increased fragility of the epithelium. This is seen as an increased sensitivity of the brush border to biochemical manipulations, decreased transepithelial resistance, and increased sensitivity to dextran sodium sulfate-induced colitis. Plastin 1 thus emerges as an important regulator of brush border morphology and stability through a novel role in the organization of the terminal web, possibly by connecting actin filaments to the underlying intermediate filament network.
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21
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Downs KM, Inman KE, Jin DX, Enders AC. The Allantoic Core Domain: new insights into development of the murine allantois and its relation to the primitive streak. Dev Dyn 2009; 238:532-53. [PMID: 19191225 PMCID: PMC2966891 DOI: 10.1002/dvdy.21862] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The whereabouts and properties of the posterior end of the primitive streak have not been identified in any species. In the mouse, the streak's posterior terminus is assumed to be confined to the embryonic compartment, and to give rise to the allantois, which links the embryo to its mother during pregnancy. In this study, we have refined our understanding of the biology of the murine posterior primitive streak and its relation to the allantois. Through a combination of immunostaining and morphology, we demonstrate that the primitive streak spans the posterior extraembryonic and embryonic regions at the onset of the neural plate stage ( approximately 7.0 days postcoitum, dpc). Several hours later, the allantoic bud emerges from the extraembryonic component of the primitive streak (XPS). Then, possibly in collaboration with overlying allantois-associated extraembryonic visceral endoderm, the XPS establishes a germinal center within the allantois, named here the Allantoic Core Domain (ACD). Microsurgical removal of the ACD beyond headfold (HF) stages resulted in the formation of allantoic regenerates that lacked the ACD and failed to elongate; nevertheless, vasculogenesis and vascular patterning proceeded. In situ and transplantation fate mapping demonstrated that, from HF stages onward, the ACD's progenitor pool contributed to the allantois exclusive of the proximal flanks. By contrast, the posterior intraembryonic primitive streak (IPS) provided the flanks. Grafting the ACD into T(C)/T(C) hosts, whose allantoises are significantly foreshortened, restored allantoic elongation. These results revealed that the ACD is essential for allantoic elongation, but the cues required for vascularization lie outside of it. On the basis of these and previous findings, we conclude that the posterior primitive streak of the mouse conceptus is far more complex than was previously believed. Our results provide new directives for addressing the origin and development of the umbilical cord, and establish a novel paradigm for investigating the fetal/placental relationship.
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Affiliation(s)
- Karen M Downs
- Department of Anatomy, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
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22
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The 3D structure of villin as an unusual F-Actin crosslinker. Structure 2009; 16:1882-91. [PMID: 19081064 DOI: 10.1016/j.str.2008.09.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 09/13/2008] [Accepted: 09/30/2008] [Indexed: 11/23/2022]
Abstract
Villin is an F-actin nucleating, crosslinking, severing, and capping protein within the gelsolin superfamily. We have used electron tomography of 2D arrays of villin-crosslinked F-actin to generate 3D images revealing villin's crosslinking structure. In these polar arrays, neighboring filaments are spaced 125.9 +/- 7.1 A apart, offset axially by 17 A, with one villin crosslink per actin crossover. More than 6500 subvolumes containing a single villin crosslink and the neighboring actin filaments were aligned and classified to produce 3D subvolume averages. Placement of a complete villin homology model into the average density reveals that full-length villin binds to different sites on F-actin from those used by other actin-binding proteins and villin's close homolog gelsolin.
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23
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Yamamichi N, Inada KI, Furukawa C, Sakurai K, Tando T, Ishizaka A, Haraguchi T, Mizutani T, Fujishiro M, Shimomura R, Oka M, Ichinose M, Tsutsumi Y, Omata M, Iba H. Cdx2 and the Brm-type SWI/SNF complex cooperatively regulate villin expression in gastrointestinal cells. Exp Cell Res 2009; 315:1779-89. [PMID: 19371634 DOI: 10.1016/j.yexcr.2009.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 01/14/2009] [Accepted: 01/14/2009] [Indexed: 01/07/2023]
Abstract
In our recent study showing a correlation between Brm-deficiency and undifferentiated status of gastric cancer, we found that the Brm-type SWI/SNF complex is required for villin expression. To elucidate intestinal villin regulation more precisely, we here analyzed structure and function of the promoter of human villin. About 1.1 kb upstream of the determined major transcription start site, we identified a highly conserved region (HCR-Cdx) among mammals, which contains two binding sites for Cdx. Expression analyses of 30 human gastrointestinal cell lines suggested that villin is regulated by Cdx2. Introduction of Cdx family genes into colorectal SW480 cells revealed that villin is strongly induced strongly by Cdx2, moderately by Cdx1, and marginally by Cdx4. Knockdown of Cdx2 in SW480 cells caused a clear downregulation of villin, and reporter assays showed that HCR-Cdx is crucial for Cdx2-dependent and Brm-dependent villin expression. Immunohistochemical analyses of gastric intestinal metaplasia and cancer revealed that villin and Cdx2 expression are tightly coupled. GST pull-down assays demonstrated a direct interaction between Cdx2 and several SWI/SNF subunits. Chromatin immunoprecipitation analyses showed the recruitment of Cdx2 and Brm around HCR-Cdx. From these results, we concluded that Cdx2 regulates intestinal villin expression through recruiting Brm-type SWI/SNF complex to the villin promoter.
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Affiliation(s)
- Nobutake Yamamichi
- Department of Microbiology and Immunology, Division of Host-Parasite Interaction, Institute of Medical Science, University of Tokyo, Shirokanedai Minato-ku, Tokyo Japan
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Khurana S, George SP. Regulation of cell structure and function by actin-binding proteins: villin's perspective. FEBS Lett 2008; 582:2128-39. [PMID: 18307996 PMCID: PMC2680319 DOI: 10.1016/j.febslet.2008.02.040] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Accepted: 02/19/2008] [Indexed: 12/23/2022]
Abstract
Villin is a tissue-specific actin modifying protein that is associated with actin filaments in the microvilli and terminal web of epithelial cells. It belongs to a large family of actin-binding proteins which includes actin-capping, -nucleating and/or -severing proteins such as gelsolin, severin, fragmin, adseverin/scinderin and actin crosslinking proteins such as dematin and supervillin. Studies done in epithelial cell lines and villin knock-out mice have demonstrated the function of villin in regulating actin dynamics, cell morphology, epithelial-to-mesenchymal transition, cell migration and cell survival. In addition, the ligand-binding properties of villin (F-actin, G-actin, calcium, phospholipids and phospholipase C-gamma1) are mechanistically important for the crosstalk between signaling pathways and actin reorganization in epithelial cells.
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Affiliation(s)
- Seema Khurana
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Nash 402, Memphis, TN 38163, United States.
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25
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Li J, Yin HL, Yuan J. Flightless-I regulates proinflammatory caspases by selectively modulating intracellular localization and caspase activity. ACTA ACUST UNITED AC 2008; 181:321-33. [PMID: 18411310 PMCID: PMC2315678 DOI: 10.1083/jcb.200711082] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Caspase-1 and caspase-11 are proinflammatory caspases that regulate cytokine production and leukocyte migration during pathogen infection. In an attempt to identify new intracellular regulators of caspase-11, we found that Flightless-I, a member of the gelsolin superfamily of actin-remodeling proteins, interacts and regulates both caspase-11 and caspase-1. Flightless-I targets caspase-11 to the Triton X-100–insoluble cytoskeleton fraction and the cell leading edge. In addition, Flightless-I inhibits caspase-1 activation and caspase-1–mediated interleukine-1β (IL-1β) maturation. The physiological relevance of these findings is supported by the opposing effects of Flightless-I overexpression and knockdown on caspase-1 activity and IL-1β maturation. Our results suggest that Flightless-I may be a bona fide caspase-1 inhibitor that acts through a mechanism similar to that of cytokine response modifier A, a potent caspase-1 inhibitor from the cowpox virus. Our study provides a new mechanism controlling the localization and activation of proinflammatory caspases.
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Affiliation(s)
- Juying Li
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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26
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Ki MR, Lee HR, Goo MJ, Hong IH, Do SH, Jeong DH, Yang HJ, Yuan DW, Park JK, Jeong KS. Differential regulation of ERK1/2 and p38 MAP kinases in VacA-induced apoptosis of gastric epithelial cells. Am J Physiol Gastrointest Liver Physiol 2008; 294:G635-47. [PMID: 18096609 DOI: 10.1152/ajpgi.00281.2007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Helicobacter pylori vacuolating cytotoxin A (VacA) has been considered as an apoptosis-inducing factor. Here, we investigated the mechanism of VacA-induced apoptosis in relation to the defense mechanism and MAP kinases pathway in gastric epithelial cells. AGS cells exposed to enriched VacA extracts affected the level of SOD-1 and villin. We further investigated the role of VacA in those inductions using a functional recombinant VacA (rVacA). Activation of p38 MAPK and Bax dimerization by rVacA were increased in a dose-dependent manner. rVacA-induced ERK1/2 MAPK activation was maximal at 30 min and 4 h and 1-4 microg/ml of rVacA. rVacA-induced SOD-1 expression was considerably diminished by inhibiting ERK1/2 MAPK and it was slightly increased by inhibiting p38 MAPK. rVacA increased or decreased villin expression depending on dose and exposure time and its expression was mainly appeared in the contractile actin ring of the dividing cells. Despite its cytoprotective effect, SB-203580, a p38 inhibitor, was unlikely to reduce VacA-induced Bax dimerization and rather inhibited villin and Bcl2 expression, indicating that p38 may also play a role in cell proliferation or differentiation for survival after VacA intoxication. Furthermore, p38 inhibitor accelerated rVacA-induced cell death after exposure of AGS cells to H(2)O(2) but ERK1/2 inhibitor protected cells from H(2)O(2) insult. These results suggest that SOD-1 and villin are expressed differentially upon VacA insult depending on dose and exposure time via ERK and p38 MAP kinases; decrease in SOD-1 and villin expression coupled with Bax dimerization leads to apoptosis of gastric epithelial cells.
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Affiliation(s)
- Mi-Ran Ki
- Department of Pathology, College of Veterinary Medicine, Kyungpook National University, Buk-ku, Daegu City, Republic of Korea
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Abstract
Peripheral sensory neurons detect diverse physical stimuli and transmit the information into the CNS. At present, the genetic tools for specifically studying the development, plasticity, and regeneration of the sensory axon projections are limited. We found that the gene encoding Advillin, an actin binding protein that belongs to the gelsolin superfamily, is expressed almost exclusively in peripheral sensory neurons. We next generated a line of knock-in mice in which the start codon of the Advillin is replaced by the gene encoding human placenta alkaline phosphatase (Avil-hPLAP mice). In heterozygous Avil-hPLAP mice, sensory axons, the exquisite sensory endings, as well as the fine central axonal collaterals can be clearly visualized with a simple alkaline phosphatase staining. Using this mouse line, we found that the development of peripheral target innervation and sensory ending formation is an ordered process with specific timing depending on sensory modalities. This is also true for the in-growth of central axonal collaterals into the brainstem and the spinal cord. Our results demonstrate that Avil-hPLAP mouse is a valuable tool for specifically studying peripheral sensory neurons. Functionally, we found that the regenerative axon growth of Advillin-null sensory neurons is significantly shortened and that deletion of Advillin reduces the plasticity of whisker-related barrelettes patterns in the hindbrain.
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Wang Y, Srinivasan K, Siddiqui MR, George SP, Tomar A, Khurana S. A novel role for villin in intestinal epithelial cell survival and homeostasis. J Biol Chem 2008; 283:9454-64. [PMID: 18198174 DOI: 10.1074/jbc.m707962200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Apoptosis is a key regulator for the normal turnover of the intestinal mucosa, and abnormalities associated with this function have been linked to inflammatory bowel disease and colorectal cancer. Despite this, little is known about the mechanism(s) mediating intestinal epithelial cell apoptosis. Villin is an actin regulatory protein that is expressed in every cell of the intestinal epithelium as well as in exocrine glands associated with the gastrointestinal tract. In this study we demonstrate for the first time that villin is an epithelial cell-specific anti-apoptotic protein. Absence of villin predisposes mice to dextran sodium sulfate-induced colitis by promoting apoptosis. To better understand the cellular and molecular mechanisms of the anti-apoptotic function of villin, we overexpressed villin in the Madin-Darby canine kidney Tet-Off epithelial cell line to demonstrate that expression of villin protects cells from apoptosis by maintaining mitochondrial integrity thus inhibiting the activation of caspase-9 and caspase-3. Furthermore, we report that the anti-apoptotic response of villin depends on activation of the pro-survival proteins, phosphatidylinositol 3-kinase and phosphorylated Akt. The results of our studies shed new light on the previously unrecognized function of villin in the regulation of apoptosis in the gastrointestinal epithelium.
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Affiliation(s)
- Yaohong Wang
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis, TN 38163, USA
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29
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Qiao XT, Ziel JW, McKimpson W, Madison BB, Todisco A, Merchant JL, Samuelson LC, Gumucio DL. Prospective identification of a multilineage progenitor in murine stomach epithelium. Gastroenterology 2007; 133:1989-98. [PMID: 18054570 PMCID: PMC2329573 DOI: 10.1053/j.gastro.2007.09.031] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 08/16/2007] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Epithelial stem cells in the stomach are responsible for constant renewal of the epithelium through generation of multiple gastric cell lineages that populate the gastric glands. However, gastric stem or progenitor cells have not been well-characterized because of the lack of specific markers that permit their prospective recognition. We identified an intestinal promoter that is active in a rare subpopulation of gastric epithelial cells and investigated whether these cells possess multilineage potential. METHODS A marked allele of the endogenous mouse villin locus was used to visualize single beta-galactosidase-positive cells located in the lower third of antral glands. A 12.4-kb villin promoter/enhancer fragment drives several transgenes (EGFP, beta-galactosidase, and Cre recombinase) in these cells in a pattern similar to that of the marked villin allele. Reporter gene activity was used to track these cells during development and to examine cell number in the context of inflammatory challenge while Cre activity allowed lineage tracing in vivo. RESULTS We show that these rare epithelial cells are normally quiescent, but multiply in response to interferon gamma. Lineage tracing studies confirm that these cells give rise to all gastric lineages of the antral glands. In the embryo, these cells are located basally in the stomach epithelium before completion of gastric gland morphogenesis. CONCLUSIONS We have identified a rare subpopulation of gastric progenitors with multilineage potential. The ability to prospectively identify and manipulate such progenitors in situ represents a major step forward in gastric stem cell biology and has potential implications for gastric cancer.
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Affiliation(s)
- Xiaotan T. Qiao
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-2200
| | - Joshua W. Ziel
- Department of Biology, Duke University, Durham, NC, 27701
| | - Wendy McKimpson
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-2200
| | - Blair B. Madison
- Department of Genetics, University of Pennsylvania, Philadelphia, PA, 19104
| | - Andrea Todisco
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109-2200
| | - Juanita L. Merchant
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109-2200, Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, 48109-2200
| | - Linda C. Samuelson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, 48109-2200
| | - Deborah L. Gumucio
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-2200,*Address Correspondence to: Deborah L. Gumucio, Ph.D., 109 Zina Pitcher Place, 2045 BSRB, Ann Arbor, MI 48109-2200, Telephone: 734-647-0172, Fax: 734-647-9559, E-mail:
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30
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George SP, Wang Y, Mathew S, Srinivasan K, Khurana S. Dimerization and actin-bundling properties of villin and its role in the assembly of epithelial cell brush borders. J Biol Chem 2007; 282:26528-41. [PMID: 17606613 DOI: 10.1074/jbc.m703617200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Villin is a major actin-bundling protein in the brush border of epithelial cells. In this study we demonstrate for the first time that villin can bundle actin filaments using a single F-actin binding site, because it has the ability to self-associate. Using fluorescence resonance energy transfer, we demonstrate villin self-association in living cells in microvilli and in growth factor-stimulated cells in membrane ruffles and lamellipodia. Using sucrose density gradient, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight, the majority of villin was identified as a monomer or dimer. Villin dimers were also identified in Caco-2 cells, which endogenously express villin and Madin-Darby canine kidney cells that ectopically express villin. Using truncation mutants of villin, site-directed mutagenesis, and fluorescence resonance energy transfer, an amino-terminal dimerization site was identified that regulated villin self-association in parallel conformation as well as actin bundling by villin. This detailed analysis describes for the first time microvillus assembly by villin, redefines the actin-bundling function of villin, and provides a molecular mechanism for actin bundling by villin, which could have wider implications for other actin cross-linking proteins that share a villin-like headpiece domain. Our study also provides a molecular basis to separate the morphologically distinct actin-severing and actin-bundling properties of villin.
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Affiliation(s)
- Sudeep P George
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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31
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Chiba H, Sakai N, Murata M, Osanai M, Ninomiya T, Kojima T, Sawada N. The nuclear receptor hepatocyte nuclear factor 4alpha acts as a morphogen to induce the formation of microvilli. ACTA ACUST UNITED AC 2007; 175:971-80. [PMID: 17178913 PMCID: PMC2064706 DOI: 10.1083/jcb.200608012] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Microvilli are actin-based organelles found on apical plasma membranes that are involved in nutrient uptake and signal transduction. Numerous components, including ezrin/radixin/moesin (ERM) proteins, have been identified that link filamentous actins to transmembrane proteins, but the signals driving microvillus biogenesis are not known. In this study, we show that the conditional and/or ectopic expression of a nuclear receptor, hepatocyte nuclear factor 4α (HNF4α), triggers microvillus morphogenesis. We also demonstrate that HNF4α expression induces ERM-binding phosphoprotein 50 (EBP50) expression and that attenuation of EBP50 using RNA interference inhibits microvillus development. We conclude that HNF4α acts as a morphogen to trigger microvillus formation.
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Affiliation(s)
- Hideki Chiba
- Department of Pathology, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.
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32
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Ono S. Mechanism of depolymerization and severing of actin filaments and its significance in cytoskeletal dynamics. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 258:1-82. [PMID: 17338919 DOI: 10.1016/s0074-7696(07)58001-0] [Citation(s) in RCA: 212] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The actin cytoskeleton is one of the major structural components of the cell. It often undergoes rapid reorganization and plays crucial roles in a number of dynamic cellular processes, including cell migration, cytokinesis, membrane trafficking, and morphogenesis. Actin monomers are polymerized into filaments under physiological conditions, but spontaneous depolymerization is too slow to maintain the fast actin filament dynamics observed in vivo. Gelsolin, actin-depolymerizing factor (ADF)/cofilin, and several other actin-severing/depolymerizing proteins can enhance disassembly of actin filaments and promote reorganization of the actin cytoskeleton. This review presents advances as well as a historical overview of studies on the biochemical activities and cellular functions of actin-severing/depolymerizing proteins.
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Affiliation(s)
- Shoichiro Ono
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
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33
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Schlichting K, Wilsch-Bräuninger M, Demontis F, Dahmann C. Cadherin Cad99C is required for normal microvilli morphology in Drosophila follicle cells. J Cell Sci 2006; 119:1184-95. [PMID: 16507588 DOI: 10.1242/jcs.02831] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Microvilli are actin-filled membranous extensions common to epithelial cells. Several proteins have been identified that localize to microvilli. However, most of these proteins are dispensable for the normal morphogenesis of microvilli. Here, we show by immunoelectron microscopy that the non-classical cadherin Cad99C localizes to microvilli of Drosophila ovarian follicle cells. Loss of Cad99C function leads to disorganized and abnormal follicle cell microvilli. Conversely, overexpression of Cad99C in follicle cells results in large bundles of microvilli. Furthermore, altered microvilli morphology correlates with defects in the assembly of the vitelline membrane, an extracellular layer secreted by follicle cells that is part of the eggshell. Finally, we provide evidence that Cad99C is the homolog of vertebrate protocadherin 15. Mutations in the gene encoding protocadherin 15 lead to the disorganization of stereocilia, which are microvilli-derived extensions of cochlear hair cells, and deafness (Usher syndrome type 1F). Our data suggest an essential role for Cad99C in microvilli morphogenesis that is important for follicle cell function. Furthermore, these results indicate that insects and vertebrates use related cadherins to organize microvilli-like cellular extensions.
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Affiliation(s)
- Karin Schlichting
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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34
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Mijalski T, Harder A, Halder T, Kersten M, Horsch M, Strom TM, Liebscher HV, Lottspeich F, de Angelis MH, Beckers J. Identification of coexpressed gene clusters in a comparative analysis of transcriptome and proteome in mouse tissues. Proc Natl Acad Sci U S A 2005; 102:8621-6. [PMID: 15939889 PMCID: PMC1143582 DOI: 10.1073/pnas.0407672102] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A major advantage of the mouse model lies in the increasing information on its genome, transcriptome, and proteome, as well as in the availability of a fast growing number of targeted and induced mutant alleles. However, data from comparative transcriptome and proteome analyses in this model organism are very limited. We use DNA chip-based RNA expression profiling and 2D gel electrophoresis, combined with peptide mass fingerprinting of liver and kidney, to explore the feasibility of such comprehensive gene expression analyses. Although protein analyses mostly identify known metabolic enzymes and structural proteins, transcriptome analyses reveal the differential expression of functionally diverse and not yet described genes. The comparative analysis suggests correlation between transcriptional and translational expression for the majority of genes. Significant exceptions from this correlation confirm the complementarities of both approaches. Based on RNA expression data from the 200 most differentially expressed genes, we identify chromosomal colocalization of known, as well as not yet described, gene clusters. The determination of 29 such clusters may suggest that coexpression of colocalizing genes is probably rather common.
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Affiliation(s)
- T Mijalski
- Institute of Experimental Genetics, GSF-National Research Center GmbH, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
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35
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Rieder G, Tessier AJ, Qiao XT, Madison B, Gumucio DL, Merchant JL. Helicobacter-induced intestinal metaplasia in the stomach correlates with Elk-1 and serum response factor induction of villin. J Biol Chem 2004; 280:4906-12. [PMID: 15576363 DOI: 10.1074/jbc.m413399200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Chronic Helicobacter pylori infection results in serious sequelae, including atrophy, intestinal metaplasia, and gastric cancer. Intestinal metaplasia in the stomach is defined by the presence of intestine-like cells expressing enterocyte-specific markers, such as villin. In this study, we demonstrate that villin is expressed in intestine-like cells that develop after chronic infection with H. pylori in both human stomach and in a mouse model. Transfection studies were used to identify specific regions of the villin promoter that are inducible by exposure of the cells to H. pylori. We demonstrated that induction of the villin promoter by H. pylori in a human gastric adenocarcinoma cell line (AGS) required activation of the Erk pathway. Elk-1 and the serum response factor (SRF) are downstream transcriptional targets of the Erk pathway. We observed inducible binding of Elk-1 and the SRF after 3 and 24 h of treatment with H. pylori, suggesting that the bacteria alone are sufficient to initiate a cascade of signaling events responsible for villin expression. Thus, H. pylori induction of villin in the stomach correlates with activation and cooperative binding of Elk-1 and the SRF to the proximal promoter of villin.
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Affiliation(s)
- Gabriele Rieder
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109-0682, USA
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36
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Archer SK, Behm CA, Claudianos C, Campbell HD. The Flightless I protein and the gelsolin family in nuclear hormone receptor-mediated signalling. Biochem Soc Trans 2004; 32:940-2. [PMID: 15506930 DOI: 10.1042/bst0320940] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Drosophila melanogaster flightless I protein and its homologues in higher eukaryotes (FliI) are conserved members of the gelsolin family of actin-binding proteins. Members of the gelsolin family generally contain three or six copies of a 125-amino-acid residue gelsolin-related repeating unit, and may contain additional domains including the C-terminal villin-related ‘headpiece’ or N-terminal extensions such as the leucine-rich repeat of the FliI protein. Numerous studies including work done with mouse knockouts for gelsolin, villin and CapG support a role for the family in cytoskeletal actin dynamics. In both fruitfly and mouse, the FliI protein is also essential for early development. Recent studies indicate that supervillin, gelsolin and FliI are involved in intracellular signalling via nuclear hormone receptors including the androgen, oestrogen and thyroid hormone receptors. This unexpected role in signalling has opened a new area in research on the gelsolin family and is providing important new insights into the mechanisms of gene regulation via nuclear receptors.
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Affiliation(s)
- S K Archer
- Molecular Genetics and Evolution Group and Centre for the Molecular Genetics of Development, Research School of Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia
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37
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Tomar A, Wang Y, Kumar N, George S, Ceacareanu B, Hassid A, Chapman KE, Aryal AM, Waters CM, Khurana S. Regulation of cell motility by tyrosine phosphorylated villin. Mol Biol Cell 2004; 15:4807-17. [PMID: 15342783 PMCID: PMC524729 DOI: 10.1091/mbc.e04-05-0431] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Temporal and spatial regulation of the actin cytoskeleton is vital for cell migration. Here, we show that an epithelial cell actin-binding protein, villin, plays a crucial role in this process. Overexpression of villin in doxycyline-regulated HeLa cells enhanced cell migration. Villin-induced cell migration was modestly augmented by growth factors. In contrast, tyrosine phosphorylation of villin and villin-induced cell migration was significantly inhibited by the src kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) as well as by overexpression of a dominant negative mutant of c-src. These data suggest that phosphorylation of villin by c-src is involved in the actin cytoskeleton remodeling necessary for cell migration. We have previously shown that villin is tyrosine phosphorylated at four major sites. To further investigate the role of tyrosine phosphorylated villin in cell migration, we used phosphorylation site mutants (tyrosine to phenylalanine or tyrosine to glutamic acid) in HeLa cells. We determined that tyrosine phosphorylation at residues 60, 81, and 256 of human villin played an essential role in cell migration as well as in the reorganization of the actin cytoskeleton. Collectively, these studies define how biophysical events such as cell migration are actuated by biochemical signaling pathways involving tyrosine phosphorylation of actin binding proteins, in this case villin.
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Affiliation(s)
- Alok Tomar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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38
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Gregorevic P, Blankinship MJ, Allen JM, Crawford RW, Meuse L, Miller DG, Russell DW, Chamberlain JS. Systemic delivery of genes to striated muscles using adeno-associated viral vectors. Nat Med 2004; 10:828-34. [PMID: 15273747 PMCID: PMC1365046 DOI: 10.1038/nm1085] [Citation(s) in RCA: 488] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Accepted: 06/29/2004] [Indexed: 12/12/2022]
Abstract
A major obstacle limiting gene therapy for diseases of the heart and skeletal muscles is an inability to deliver genes systemically to muscles of an adult organism. Systemic gene transfer to striated muscles is hampered by the vascular endothelium, which represents a barrier to distribution of vectors via the circulation. Here we show the first evidence of widespread transduction of both cardiac and skeletal muscles in an adult mammal, after a single intravenous administration of recombinant adeno-associated virus pseudotype 6 vectors. The inclusion of vascular endothelium growth factor/vascular permeability factor, to achieve acute permeabilization of the peripheral microvasculature, enhanced tissue transduction at lower vector doses. This technique enabled widespread muscle-specific expression of a functional micro-dystrophin in the skeletal muscles of dystrophin-deficient mdx mice, which model Duchenne muscular dystrophy. We propose that these methods may be applicable for systemic delivery of a wide variety of genes to the striated muscles of adult mammals.
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Affiliation(s)
| | | | | | | | | | | | - David W Russell
- Medicine and
- Biochemistry, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, The University of Washington, Seattle, Washington 98195, USA
| | - Jeffrey S Chamberlain
- Departments of Neurology
- Medicine and
- Biochemistry, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, The University of Washington, Seattle, Washington 98195, USA
- Correspondence should be addressed to J.S.C. ()
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39
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Zelhof AC, Hardy RW. WASp is required for the correct temporal morphogenesis of rhabdomere microvilli. J Cell Biol 2004; 164:417-26. [PMID: 14744998 PMCID: PMC2172231 DOI: 10.1083/jcb.200307048] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2003] [Accepted: 12/02/2003] [Indexed: 12/04/2022] Open
Abstract
Microvilli are actin-based fingerlike membrane projections that form the basis of the brush border of enterocytes and the Drosophila melanogaster photoreceptor rhabdomere. Although many microvillar cytoskeletal components have been identified, the molecular basis of microvillus formation is largely undefined. Here, we report that the Wiskott-Aldrich syndrome protein (WASp) is necessary for rhabdomere microvillus morphogenesis. We show that WASp accumulates on the photoreceptor apical surface before microvillus formation, and at the time of microvillus initiation WASp colocalizes with amphiphysin and moesin. The loss of WASp delays the enrichment of F-actin on the apical photoreceptor surface, delays the appearance of the primordial microvillar projections, and subsequently leads to malformed rhabdomeres.
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Affiliation(s)
- Andrew C Zelhof
- Division of Biology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0649, USA.
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40
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Athman R, Louvard D, Robine S. Villin enhances hepatocyte growth factor-induced actin cytoskeleton remodeling in epithelial cells. Mol Biol Cell 2003; 14:4641-53. [PMID: 12937273 PMCID: PMC266779 DOI: 10.1091/mbc.e03-02-0091] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Villin is an actin-binding protein localized to intestinal and kidney brush borders. In vitro, villin has been demonstrated to bundle and sever F-actin in a calcium-dependent manner. Although villin is not necessary for the bundling of F-actin in vivo, it is important for the reorganization of the actin cytoskeleton elicited by stress during both physiological and pathological conditions (Ferrary et al., 1999). These data suggest that villin may be involved in actin cytoskeleton remodeling necessary for many processes requiring cellular plasticity. Here, we study the role of villin in hepatocyte growth factor (HGF)-induced epithelial cell motility and morphogenesis. For this purpose, we used primary cultures of enterocytes derived from wild-type and villin knock-out mice and Madin-Darby canine kidney cells, expressing villin in an inducible manner. In vitro, we show that epithelial cell lysates from villin-expressing cells induced dramatic, calcium-dependent severing of actin filaments. In cell culture, we found that villin-expressing cells exhibit enhanced cell motility and morphogenesis upon HGF stimulation. In addition, we show that the ability of villin to potentiate HGF-induced actin reorganization occurs through the HGF-activated phospholipase Cgamma signaling pathway. Collectively, these data demonstrate that villin acts as a regulator of HGF-induced actin dynamics.
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Affiliation(s)
- Rafika Athman
- Laboratoire de Morphogenèse et Signalisation Cellulaires, Institut Curie Unité Mixte Recherche 144, 75248 Paris, France
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41
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Jansen PLM, Sturm E. Paediatric cholestasis: is villin the villain? Lancet 2003; 362:1090-1. [PMID: 14550691 DOI: 10.1016/s0140-6736(03)14498-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Peter L M Jansen
- Department of Pediatrics, University Hospital Groningen, 9713 GZ, Groningen, Netherlands.
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42
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Phillips MJ, Azuma T, Meredith SLM, Squire JA, Ackerley CA, Pluthero FG, Roberts EA, Superina RA, Levy GA, Marsden PA. Abnormalities in villin gene expression and canalicular microvillus structure in progressive cholestatic liver disease of childhood. Lancet 2003; 362:1112-9. [PMID: 14550699 DOI: 10.1016/s0140-6736(03)14467-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND The molecular basis of clinical cholestasis is a subject of intense investigation. Villin is an actin binding, bundling, and severing protein needed for maintenance of structural integrity of canalicular microvilli, in which membrane transporters required for bile secretion are located. We aimed to investigate the role of canalicular cytoskeletal proteins in three genetically unrelated children with a biliary atresia-like clinical disorder, each of whom developed liver failure requiring liver transplantation. METHODS Explanted livers from the three patients were examined by standard pathological methods followed by transmission and cryoimmunoelectron microscopy. With archival tissue samples, a panel of cytoskeletal proteins was investigated by immunohistochemistry and western blotting, with purified canalicular membrane preparations. Villin mRNA analyses were undertaken on liver homogenates, with primers from coding regions of the human villin gene. Classic biliary atresia, other types of cholestasis, and normal livers served as controls. FINDINGS In patients, pronounced ultrastructural deformities of canaliculi and especially of their microvilli were noted, which correlated with absence of villin protein by immunostaining of liver tissue sections and by western blot analysis. Additionally, villin mRNA was strikingly reduced or absent. These results differed greatly from those in controls. INTERPRETATION These results suggest that the disorder described mimics biliary atresia, but structural and molecular pathological findings differ. We propose that a functional abnormality in villin gene expression is key to the mechanism of cholestasis in patients with progressive cholestasis and hepatic failure.
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Affiliation(s)
- M James Phillips
- Department of Multi-organ Transplantation Research, Toronto General Hospital, University Health Network, ON, Toronto, Canada.
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43
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Potter DA, Srirangam A, Fiacco KA, Brocks D, Hawes J, Herndon C, Maki M, Acheson D, Herman IM. Calpain regulates enterocyte brush border actin assembly and pathogenic Escherichia coli-mediated effacement. J Biol Chem 2003; 278:30403-12. [PMID: 12764139 PMCID: PMC2727654 DOI: 10.1074/jbc.m304616200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study identifies calpain as being instrumental for brush border (BB) microvillus assembly during differentiation and effacement during bacterial pathogenesis. Calpain activity is decreased by 25-80% in Caco 2 lines stably overexpressing calpastatin, the physiological inhibitor of calpain, and the effect is proportional to the calpastatin/calpain ratio. These lines exhibit a 2.5-fold reduction in the rate of microvillus extension. Apical microvillus assembly is reduced by up to 50%, as measured by quantitative fluorometric microscopy (QFM) of ezrin, indicating that calpain recruits ezrin to BB microvilli. Calpain inhibitors ZLLYCHN2, MDL 28170, and PD 150606 block BB assembly and ezrin recruitment to the BB. The HIV protease inhibitor ritonavir, which inhibits calpain at clinically relevant concentrations, also blocks BB assembly, whereas cathepsin and proteasome inhibitors do not. Microvillus effacement is inhibited after exposure of calpastatin-overexpressing cells to enteropathogenic Escherichia coli. These results suggest that calpain regulates BB assembly as well as pathological effacement, and indicate that it is an important regulator involved in HIV protease inhibitor toxicity and host-microbial pathogen interactions.
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Affiliation(s)
- David A. Potter
- Division of Hematology/Oncology, Walther Oncology Center and Veterans Affairs Medical Center, Indiana University, Indianapolis, Indiana 46202
- Department of Biochemistry and Molecular Biology, Indiana University, Indianapolis, Indiana 46202
- To whom correspondence may be addressed: Dept. of Medicine, Indiana University School of Medicine, 1044 W. Walnut St., Indianapolis, IN 46202-5254. Tel.: 317-274-2221; Fax: 317-274-0396; E-mail:
| | - Anjaiah Srirangam
- Division of Hematology/Oncology, Walther Oncology Center and Veterans Affairs Medical Center, Indiana University, Indianapolis, Indiana 46202
| | - Kerry A. Fiacco
- Division of Hematology/Oncology, Walther Oncology Center and Veterans Affairs Medical Center, Indiana University, Indianapolis, Indiana 46202
| | - Daniel Brocks
- Division of Hematology/Oncology, Walther Oncology Center and Veterans Affairs Medical Center, Indiana University, Indianapolis, Indiana 46202
| | - John Hawes
- Department of Biochemistry and Molecular Biology, Indiana University, Indianapolis, Indiana 46202
| | - Carter Herndon
- Department of Biochemistry and Molecular Biology, Indiana University, Indianapolis, Indiana 46202
| | - Masatoshi Maki
- Department of Molecular Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan 464-01
| | - David Acheson
- Department of Public Health, University of Maryland, Baltimore, Maryland 21201
| | - Ira M. Herman
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111
- To whom correspondence may be addressed: Dept. of Physiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111. Tel.: 617-636-2991; Fax: 617-636-0445; E-mail:
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44
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Madison BB, Dunbar L, Qiao XT, Braunstein K, Braunstein E, Gumucio DL. Cis elements of the villin gene control expression in restricted domains of the vertical (crypt) and horizontal (duodenum, cecum) axes of the intestine. J Biol Chem 2002; 277:33275-83. [PMID: 12065599 DOI: 10.1074/jbc.m204935200] [Citation(s) in RCA: 625] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Villin, an actin bundling protein found in the apical brush border of absorptive tissues, is one of the first structural genes to be transcriptionally activated in the embryonic intestinal endoderm. In the adult, villin is broadly expressed in every cell of the intestinal epithelium on both the vertical axis (crypt to villus tip) and the horizontal axis (duodenum through colon) of the intestine. Here, we document that a 12.4-kilobase region of the mouse villin gene drives high level expression of two different reporter genes (LacZ and Cre recombinase) within the entire intestinal epithelium of transgenic mice. Deletion of a portion of this transgene results in reduction of beta-galactosidase activity in restricted domains of the small intestine (duodenum) and large intestine (cecum). In addition, expression is reduced in the crypt compartment throughout the intestine. Thus, the global expression pattern of villin in the intestine is apparently the consequence of an amalgam of distinct and individual domain-specific control processes. That is, expression of villin in the duodenum and cecum requires different regulatory sequences than the rest of the intestine, and the expression of villin in crypts is regulated by different circuitry than expression of villin on villus tips.
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Affiliation(s)
- Blair B Madison
- Department of Cell and Developmental Biology, The University of Michigan Medical School, Ann Arbor, Michigan 48109-0616, USA
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Athman R, Louvard D, Robine S. The epithelial cell cytoskeleton and intracellular trafficking. III. How is villin involved in the actin cytoskeleton dynamics in intestinal cells? Am J Physiol Gastrointest Liver Physiol 2002; 283:G496-502. [PMID: 12181160 DOI: 10.1152/ajpgi.00207.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Villin plays a key role in the maintenance of the brush border organization by bundling F-actin into a network of parallel filaments. Our previous in vivo data on villin knockout mice showed that, although this protein is not necessary for the bundling of F-actin, it is important for the reorganization of the actin cytoskeleton elicited by stress conditions. We further investigated villin property to initiate actin remodeling in cellular processes such as hepatocyte growth factor-induced motility, morphogenesis, and bacterial infection. Our data suggest that villin is involved in actin remodeling necessary for many cellular processes requiring the actin cytoskeleton plasticity.
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Affiliation(s)
- Rafika Athman
- Laboratoire de morphogénèse et signalisation cellulaires, Institut Curie UMR 144, 75248 Paris cedex 05, France
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Khanna R, Chang SH, Andrabi S, Azam M, Kim A, Rivera A, Brugnara C, Low PS, Liu SC, Chishti AH. Headpiece domain of dematin is required for the stability of the erythrocyte membrane. Proc Natl Acad Sci U S A 2002; 99:6637-42. [PMID: 12011427 PMCID: PMC124455 DOI: 10.1073/pnas.052155999] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dematin is an actin-binding and bundling protein of the erythrocyte membrane skeleton. Dematin is localized to the spectrin-actin junctions, and its actin-bundling activity is regulated by phosphorylation of cAMP-dependent protein kinase. The carboxyl terminus of dematin is homologous to the "headpiece" domain of villin, an actin-bundling protein of the microvillus cytoskeleton. The headpiece domain contains an actin-binding site, a cAMP-kinase phosphorylation site, plays an essential role in dematin self-assembly, and bundles F-actin in vitro. By using homologous recombination in mouse embryonic stem cells, the headpiece domain of dematin was deleted to evaluate its function in vivo. Dematin headpiece null mice were viable and born at the expected Mendelian ratio. Hematological evaluation revealed evidence of compensated anemia and spherocytosis in the dematin headpiece null mice. The headpiece null erythrocytes were osmotically fragile, and ektacytometry/micropore filtration measurements demonstrated reduced deformability and filterability. In vitro membrane stability measurements indicated significantly greater membrane fragmentation of the dematin headpiece null erythrocytes. Finally, biochemical characterization, including the vesicle/cytoskeleton dissociation, spectrin self-association, and chemical crosslinking measurements, revealed a weakened membrane skeleton evidenced by reduced association of spectrin and actin to the plasma membrane. Together, these results provide evidence for the physiological significance of dematin and demonstrate a role for the headpiece domain in the maintenance of structural integrity and mechanical properties of erythrocytes in vivo.
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Affiliation(s)
- Richie Khanna
- Department of Medicine, St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA
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Campbell HD, Fountain S, McLennan IS, Berven LA, Crouch MF, Davy DA, Hooper JA, Waterford K, Chen KS, Lupski JR, Ledermann B, Young IG, Matthaei KI. Fliih, a gelsolin-related cytoskeletal regulator essential for early mammalian embryonic development. Mol Cell Biol 2002; 22:3518-26. [PMID: 11971982 PMCID: PMC133791 DOI: 10.1128/mcb.22.10.3518-3526.2002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Drosophila melanogaster flightless I gene is required for normal cellularization of the syncytial blastoderm. Highly conserved homologues of flightless I are present in Caenorhabditis elegans, mouse, and human. We have disrupted the mouse homologue Fliih by homologous recombination in embryonic stem cells. Heterozygous Fliih mutant mice develop normally, although the level of Fliih protein is reduced. Cultured homozygous Fliih mutant blastocysts hatch, attach, and form an outgrowing trophoblast cell layer, but egg cylinder formation fails and the embryos degenerate. Similarly, Fliih mutant embryos initiate implantation in vivo but then rapidly degenerate. We have constructed a transgenic mouse carrying the complete human FLII gene and shown that the FLII transgene is capable of rescuing the embryonic lethality of the homozygous targeted Fliih mutation. These results confirm the specific inactivation of the Fliih gene and establish that the human FLII gene and its gene product are functional in the mouse. The Fliih mouse mutant phenotype is much more severe than in the case of the related gelsolin family members gelsolin, villin, and CapG, where the homozygous mutant mice are viable and fertile but display alterations in cytoskeletal actin regulation.
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Affiliation(s)
- Hugh D Campbell
- Molecular Genetics and Evolution Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia.
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Braunstein EM, Qiao XT, Madison B, Pinson K, Dunbar L, Gumucio DL. Villin: A marker for development of the epithelial pyloric border. Dev Dyn 2002; 224:90-102. [PMID: 11984877 DOI: 10.1002/dvdy.10091] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In the adult gastrointestinal tract, the morphologic borders between esophagus and stomach and between stomach and small intestine are literally one cell thick. The patterning mechanisms that underlie the development of these sharp regional divisions from a once continuous endodermal tube are still obscure. In the embryonic endoderm of the developing gut, region-specific expression of certain genes (e.g., intestine-specific expression of the actin bundling protein villin) can be detected as early as 9.0 days post coitum, although the morphologic differentiation of the gut epithelium proper does not begin until 4 to 5 days later. By using a mouse model in which a beta-galactosidase marker has been inserted into the endogenous villin locus, we examined the development of the stomach/intestinal (pyloric) border during gut organogenesis. The data indicate that the border is not sharp from the outset. Rather, the initial border region is characterized by a decreasing gradient of villin/beta-galactosidase expression that extends into the distal stomach. A sharp epithelial border of villin/beta-galactosidase expression appears abruptly at day 16 and is further refined over the next 3 weeks to form the distinct one-cell-thick border characteristic of the adult. These results indicate that an important previously unrecognized patterning event occurs in the gut epithelium at 16 days; this event may define an epithelial compartment boundary between the stomach and the intestine. The villin/beta-galactosidase mouse model characterized here provides an excellent substrate with which to further dissect the mechanisms involved in this patterning process.
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Affiliation(s)
- Evan M Braunstein
- Department of Cell and Developmental Biology, University of Michigan, 5704 Medical Science II, Ann Arbor, MI 48019-0616, USA
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Ravenall SJ, Gavazzi I, Wood JN, Akopian AN. A peripheral nervous system actin-binding protein regulates neurite outgrowth. Eur J Neurosci 2002; 15:281-90. [PMID: 11849295 DOI: 10.1046/j.0953-816x.2001.01862.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Difference cloning has identified a Villin-like mRNA transcript expressed selectively in peripheral sensory and sympathetic neurons. Pervin, the encoded 820-amino acid protein, has 60% identity with Villin and is the rat homologue of Advillin. Coimmunoprecipitation studies demonstrate that Pervin and actin interact in vivo. Transfection of COS-7 epithelial cell lines demonstrates colocalization of epitope-tagged Pervin with green fluorescent protein-actin and results in an increase in process formation. This effect is abolished when the putative actin-bundling headpiece of Pervin is deleted. Biolistic transfection of primary cultures of rat dorsal root ganglion sensory neurons also results in increased neurite outgrowth with FLAG-tagged Pervin. Deletion of the actin-bundling headpiece inhibits normal neurite growth. These data suggest that Pervin may play a significant role in regulating process outgrowth in peripheral neurons through a mechanism that involves the activity of an actin-bundling domain.
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Affiliation(s)
- Samantha J Ravenall
- Department of Biology, University College, Gower Street, London WC1E 6BT, UK
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Lutchman M, Kim AC, Cheng L, Whitehead IP, Oh SS, Hanspal M, Boukharov AA, Hanada T, Chishti AH. Dematin interacts with the Ras-guanine nucleotide exchange factor Ras-GRF2 and modulates mitogen-activated protein kinase pathways. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:638-49. [PMID: 11856323 DOI: 10.1046/j.0014-2956.2001.02694.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Erythroid dematin is a major component of red blood cell junctional complexes that link the spectrin-actin cytoskeleton to the overlying plasma membrane. Transcripts of dematin are widely distributed including human brain, heart, lung, skeletal muscle, and kidney. In vitro, dematin binds and bundles actin filaments in a phosphorylation-dependent manner. The primary structure of dematin consists of a C-terminal domain homologous to the 'headpiece' domain of villin, an actin-binding protein of the brush border cytoskeleton. Except filamentous actin, no other binding partners of dematin have been identified. To investigate the physiological function of dematin, we employed the yeast two-hybrid assay to identify dematin-interacting proteins in the adult human brain. Here, we show that dematin interacts with the guanine nucleotide exchange factor Ras-GRF2 by yeast two-hybrid assay, and this interaction is further confirmed by blot overlay, surface plasmon resonance, co-transfection, and co-immunoprecipitation assays. Human Ras-GRF2 is expressed in a variety of tissues and, similar to other guanine nucleotide exchange factors (GEFs), displays anchorage independent growth in soft agar. Co-transfection and immunoblotting experiments revealed that dematin blocks transcriptional activation of Jun by Ras-GRF2 and activates ERK1 via a Ras-GRF2 independent pathway. Because much of the present evidence has centered on the identification of the Rho family of GTPases as key regulators of the actin cytoskeleton, the direct association between dematin and Ras-GRF2 may provide an alternate mechanism for regulating the activation of Rac and Ras GTPases via the actin cytoskeleton.
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Affiliation(s)
- Mohini Lutchman
- Section of Hematology-Oncology Research, Department of Medicine, St Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA
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