1
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Ribeiro TP, Martins-de-Sa D, Macedo LLP, Lourenço-Tessutti IT, Ruffo GC, Sousa JPA, Rósario Santana JMD, Oliveira-Neto OB, Moura SM, Silva MCM, Morgante CV, Oliveira NG, Basso MF, Grossi-de-Sa MF. Cotton plants overexpressing the Bacillus thuringiensis Cry23Aa and Cry37Aa binary-like toxins exhibit high resistance to the cotton boll weevil (Anthonomus grandis). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 344:112079. [PMID: 38588981 DOI: 10.1016/j.plantsci.2024.112079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/10/2024]
Abstract
The cotton boll weevil (CBW, Anthonomus grandis) stands as one of the most significant threats to cotton crops (Gossypium hirsutum). Despite substantial efforts, the development of a commercially viable transgenic cotton event for effective open-field control of CBW has remained elusive. This study describes a detailed characterization of the insecticidal toxins Cry23Aa and Cry37Aa against CBW. Our findings reveal that CBW larvae fed on artificial diets supplemented exclusively with Cry23Aa decreased larval survival by roughly by 69%, while supplementation with Cry37Aa alone displayed no statistical difference compared to the control. However, the combined provision of both toxins in the artificial diet led to mortality rates approaching 100% among CBW larvae (LC50 equal to 0.26 PPM). Additionally, we engineered transgenic cotton plants by introducing cry23Aa and cry37Aa genes under control of the flower bud-specific pGhFS4 and pGhFS1 promoters, respectively. Seven transgenic cotton events expressing high levels of Cry23Aa and Cry37Aa toxins in flower buds were selected for greenhouse bioassays, and the mortality rate of CBW larvae feeding on their T0 and T1 generations ranged from 75% to 100%. Our in silico analyses unveiled that Cry23Aa displays all the hallmark characteristics of β-pore-forming toxins (β-PFTs) that bind to sugar moieties in glycoproteins. Intriguingly, we also discovered a distinctive zinc-binding site within Cry23Aa, which appears to be involved in protein-protein interactions. Finally, we discuss the major structural features of Cry23Aa that likely play a role in the toxin's mechanism of action. In view of the low LC50 for CBW larvae and the significant accumulation of these toxins in the flower buds of both T0 and T1 plants, we anticipate that through successive generations of these transgenic lines, cotton plants engineered to overexpress cry23Aa and cry37Aa hold promise for effectively managing CBW infestations in cotton crops.
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Affiliation(s)
- Thuanne Pires Ribeiro
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Diogo Martins-de-Sa
- Department of Cellular Biology, University of Brasília, Brasília, DF 70910-900, Brazil; Genesilico Biotech, Brasília, DF 71503-508, Brazil
| | - Leonardo Lima Pepino Macedo
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Isabela Tristan Lourenço-Tessutti
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Gustavo Caseca Ruffo
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil; Graduate Program in Genomic Science and Biotechnology, Catholic University of Brasília, Brasília, DF 71966-700, Brazil
| | - João Pedro Abreu Sousa
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil; Graduate Program in Genomic Science and Biotechnology, Catholic University of Brasília, Brasília, DF 71966-700, Brazil
| | - Julia Moura do Rósario Santana
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil; Graduate Program in Genomic Science and Biotechnology, Catholic University of Brasília, Brasília, DF 71966-700, Brazil
| | - Osmundo Brilhante Oliveira-Neto
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil; Euroamerican University Center, Unieuro, Brasília, DF 70790-160, Brazil
| | - Stéfanie Menezes Moura
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Maria Cristina Mattar Silva
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Carolina Vianna Morgante
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil; Embrapa Semi-Arid, Pretrolina, PE 56302-970, Brazil
| | - Nelson Geraldo Oliveira
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Marcos Fernando Basso
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil
| | - Maria Fatima Grossi-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, DF 70770-917, Brazil; National Institute of Science and Technology, INCT PlantStress Biotech, Embrapa, Brasília, DF 70770-917, Brazil; Graduate Program in Genomic Science and Biotechnology, Catholic University of Brasília, Brasília, DF 71966-700, Brazil; Graduate Program in Biotechnology, Catholic University Dom Bosco, Campo Grande, MS 79117-900, Brazil.
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2
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Li M, Du Y, Zhang X, Zhou W. Research advances of MAL family members in tumorigenesis and tumor progression (Review). Mol Med Rep 2024; 29:57. [PMID: 38362940 PMCID: PMC10884788 DOI: 10.3892/mmr.2024.13181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 01/05/2024] [Indexed: 02/17/2024] Open
Abstract
The myelin and lymphocyte protein (MAL) family is a novel gene family first identified and characterized in 2002. This family is comprised of seven members, including MAL, MAL2, plasmolipin, MALL, myeloid differentiation‑associated marker (MYADM), MYADML2 and CMTM8, which are located on different chromosomes. In addition to exhibiting extensive activity during transcytosis, the MAL family plays a vital role in the neurological, digestive, respiratory, genitourinary and other physiological systems. Furthermore, the intimate association between MAL and the pathogenesis, progression and metastasis of malignancies, attributable to several mechanisms such as DNA methylation has also been elucidated. In the present review, an overview of the structural and functional properties of the MAL family and the latest research findings regarding the relationship between several MAL members and various cancers is provided. Furthermore, the potential clinical and scientific significance of MAL is discussed and directions for future research are summarized.
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Affiliation(s)
- Mengyao Li
- The Second Clinical Medical College, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Yan Du
- The Second Clinical Medical College, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Xianzhuo Zhang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Wence Zhou
- The Second Clinical Medical College, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
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3
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Shetty SV, Mazzucco MR, Winokur P, Haigh SV, Rumah KR, Fischetti VA, Vartanian T, Linden JR. Clostridium perfringens Epsilon Toxin Binds to and Kills Primary Human Lymphocytes. Toxins (Basel) 2023; 15:423. [PMID: 37505692 PMCID: PMC10467094 DOI: 10.3390/toxins15070423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/30/2023] [Accepted: 06/07/2023] [Indexed: 07/29/2023] Open
Abstract
Clostridium perfringens epsilon toxin (ETX) is the third most lethal bacterial toxin and has been suggested to be an environmental trigger of multiple sclerosis, an immune-mediated disease of the human central nervous system. However, ETX cytotoxicity on primary human cells has not been investigated. In this article, we demonstrate that ETX preferentially binds to and kills human lymphocytes expressing increased levels of the myelin and lymphocyte protein MAL. Using flow cytometry, ETX binding was determined to be time and dose dependent and was highest for CD4+ cells, followed by CD8+ and then CD19+ cells. Similar results were seen with ETX-induced cytotoxicity. To determine if ETX preference for CD4+ cells was related to MAL expression, MAL gene expression was determined by RT-qPCR. CD4+ cells had the highest amount of Mal gene expression followed by CD8+ and CD19+ cells. These data indicate that primary human cells are susceptible to ETX and support the hypothesis that MAL is a main receptor for ETX. Interestingly, ETX bindings to human lymphocytes suggest that ETX may influence immune response in multiple sclerosis.
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Affiliation(s)
- Samantha V. Shetty
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA (T.V.)
| | - Michael R. Mazzucco
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA (T.V.)
| | - Paige Winokur
- Harold and Margaret Milliken Hatch Laboratory of Neuro-Endocrinology Rockefeller University, New York, NY 10065, USA
| | - Sylvia V. Haigh
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA (T.V.)
| | - Kareem Rashid Rumah
- Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, NY 10065, USA
| | - Vincent A. Fischetti
- Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, NY 10065, USA
| | - Timothy Vartanian
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA (T.V.)
| | - Jennifer R. Linden
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA (T.V.)
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4
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Tutanov OS, Glass SE, Coffey RJ. Emerging connections between GPI-anchored proteins and their extracellular carriers in colorectal cancer. EXTRACELLULAR VESICLES AND CIRCULATING NUCLEIC ACIDS 2023; 4:195-217. [PMID: 37840781 PMCID: PMC10569057 DOI: 10.20517/evcna.2023.17] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Although extracellular vesicles (EVs) were discovered over 40 years ago, there has been a resurgence of interest in secreted vesicles and their attendant cargo as novel modes of intracellular communication. In addition to vesicles, two amembranous nanoparticles, exomeres and supermeres, have been isolated and characterized recently. In this rapidly expanding field, it has been challenging to assign cargo and specific functions to a particular carrier. Refinement of isolation methods, well-controlled studies, and guidelines detailed by Minimal Information for Studies of Extracellular Vesicles (MISEV) are being employed to "bring order to chaos." In this review, we will briefly summarize three types of extracellular carriers - small EVs (sEVs), exomeres, and supermeres - in the context of colorectal cancer (CRC). We found that a number of GPI-anchored proteins (GPI-APs) are overexpressed in CRC, are enriched in exosomes (a distinct subset of sEVs), and can be detected in exomeres and supermeres. This affords the opportunity to elaborate on GPI-AP biogenesis, modifications, and trafficking using DPEP1, a GPI-AP upregulated in CRC, as a prime example. We have cataloged the GPI-anchored proteins secreted in CRC and will highlight features of select CRC-associated GPI-anchored proteins we have detected. Finally, we will discuss the remaining challenges and future opportunities in studying these secreted GPI-APs in CRC.
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Affiliation(s)
- Oleg S. Tutanov
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Sarah E. Glass
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Robert J. Coffey
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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5
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Zhang L, Tan W, Yang H, Zhang S, Dai Y. Detection of Host Cell Gene/HPV DNA Methylation Markers: A Promising Triage Approach for Cervical Cancer. Front Oncol 2022; 12:831949. [PMID: 35402283 PMCID: PMC8990922 DOI: 10.3389/fonc.2022.831949] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 02/28/2022] [Indexed: 02/05/2023] Open
Abstract
Cervical cancer is the most prevalent gynecologic malignancy, especially in women of low- and middle-income countries (LMICs). With a better understanding of the etiology and pathogenesis of cervical cancer, it has been well accepted that this type of cancer can be prevented and treated via early screening. Due to its higher sensitivity than cytology to identify precursor lesions of cervical cancer, detection of high-risk human papillomavirus (HR-HPV) DNA has been implemented as the primary screening approach. However, a high referral rate for colposcopy after HR-HPV DNA detection due to its low specificity in HR-HPV screening often leads to overtreatment and thus increases the healthcare burden. Emerging evidence has demonstrated that detection of host cell gene and/or HPV DNA methylation represents a promising approach for the early triage of cervical cancer in HR-HPV-positive women owing to its convenience and comparable performance to cytology, particularly in LMICs with limited healthcare resources. While numerous potential markers involving DNA methylation of host cell genes and the HPV genome have been identified thus far, it is crucial to define which genes or panels involving host and/or HPV are feasible and appropriate for large-scale screening and triage. An ideal approach for screening and triage of CIN/ICC requires high sensitivity and adequate specificity and is suitable for self-sampling and inexpensive to allow population-based screening, particularly in LMICs. In this review, we summarize the markers of host cell gene/HR-HPV DNA methylation and discuss their triage performance and feasibility for high-grade precancerous cervical intraepithelial neoplasia or worse (CIN2+ and CIN3+) in HR-HPV-positive women.
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Affiliation(s)
- Lingyi Zhang
- Laboratory of Cancer Precision Medicine, The First Hospital of Jilin University, Changchun, China.,Department of Gynecology and Obstetrics, The Second Hospital of Jilin University, Changchun, China
| | - Wenxi Tan
- Department of Gynecology and Obstetrics, The Second Hospital of Jilin University, Changchun, China
| | - Hongmei Yang
- Laboratory of Cancer Precision Medicine, The First Hospital of Jilin University, Changchun, China.,Department of Critical Care Medicine, The First Hospital of Jilin University, Changchun, China
| | - Songling Zhang
- Department of Obstetrics and Gynecology, The First Hospital of Jilin University, Changchun, China
| | - Yun Dai
- Laboratory of Cancer Precision Medicine, The First Hospital of Jilin University, Changchun, China
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6
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Rubio-Ramos A, Labat-de-Hoz L, Correas I, Alonso MA. The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer. Cells 2021; 10:1065. [PMID: 33946345 PMCID: PMC8145151 DOI: 10.3390/cells10051065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/12/2022] Open
Abstract
The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.
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Affiliation(s)
- Armando Rubio-Ramos
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
| | - Leticia Labat-de-Hoz
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
| | - Isabel Correas
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
- Department of Molecular Biology, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Miguel A. Alonso
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.R.-R.); (L.L.-d.-H.); (I.C.)
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7
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El Aliani A, El-Abid H, El Mallali Y, Attaleb M, Ennaji MM, El Mzibri M. Association between Gene Promoter Methylation and Cervical Cancer Development: Global Distribution and A Meta-analysis. Cancer Epidemiol Biomarkers Prev 2021; 30:450-459. [DOI: 10.1158/1055-9965.epi-20-0833] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/27/2020] [Accepted: 12/31/2020] [Indexed: 12/24/2022] Open
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8
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Song C, Yue Q, Moseley A, Al-Khalili O, Wynne BM, Ma H, Wang L, Eaton DC. Myristoylated alanine-rich C kinase substrate-like protein-1 regulates epithelial sodium channel activity in renal distal convoluted tubule cells. Am J Physiol Cell Physiol 2020; 319:C589-C604. [PMID: 32639874 DOI: 10.1152/ajpcell.00218.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The epithelial sodium channel (ENaC) regulates blood pressure by fine-tuning distal nephron sodium reabsorption. Our previous work has shown that ENaC gating is regulated by anionic phospholipid phosphates, including phosphatidylinositol 4,5-bisphosphate (PIP2). The PIP2-dependent regulation of ENaC is mediated by the myristoylated alanine-rich protein kinase C substrate-like protein-1 (MLP-1). MLP-1 binds to and is a reversible source of PIP2 at the plasma membrane. We examined MLP-1 regulation of ENaC in distal convoluted tubule clonal cell line DCT-15 cells. Wild-type MLP-1 runs at an apparent molecular mass of 52 kDa despite having a predicted molecular mass of 21 kDa. Native MLP-1 consists of several distinct structural elements: an effector domain that is highly positively charged, sequesters PIP2, contains serines that are the target of PKC, and controls MLP-1 association with the membrane; a myristoylation domain that promotes association with the membrane; and a multiple homology 2 domain of previously unknown function. To further examine MLP-1 in DCT-15 cells, we constructed several MLP-1 mutants: WT, a full-length wild-type protein; S3A, three substitutions in the effector domain to prevent phosphorylation; S3D mimicked constitutive phosphorylation by replacing three serines with aspartates; and GA replaced the myristoylation site glycine with alanine, so GA could not be myristoylated. Each mutant was tagged with either NH2-terminal 3XFLAG or COOH-terminal mCherry or V5. Transfection with MLP mutants modified ENaC activity in DCT-15 cells: activity was highest in S3A and lowest in S3D, and the activity after transfection with either construct was significantly different from WT. In Western blots, when transfected with 3XFLAG-tagged MLP-1 mutants, the expression of the full length of MLP-1 at 52 kDa increased in mutant S3A-MLP-1-transfected DCT-15 cells and decreased in S3D-MLP-1-transfected DCT-15 cells. Several lower molecular mass bands were also detected that correspond to potential presumptive calpain cleavage products. Confocal imaging shows that the different mutants localize in different subcellular compartments consistent with their preferred location in the membrane or in the cytosol. Activation of protein kinase C increases phosphorylation of endogenous MLP-1 and reduces ENaC activity. Our results suggest a complicated role for proteolytic processing in MLP-1 regulation of ENaC.
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Affiliation(s)
- Chang Song
- Department of Neurology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.,Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia.,Department of Physiology, Emory University, Atlanta, Georgia
| | - Qiang Yue
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
| | - Auriel Moseley
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
| | - Otor Al-Khalili
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
| | - Brandi M Wynne
- Division of Nephrology & Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Heping Ma
- Department of Physiology, Emory University, Atlanta, Georgia
| | - Lihua Wang
- Department of Neurology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Douglas C Eaton
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
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9
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Dorca-Arévalo J, Dorca E, Torrejón-Escribano B, Blanch M, Martín-Satué M, Blasi J. Lung endothelial cells are sensitive to epsilon toxin from Clostridium perfringens. Vet Res 2020; 51:27. [PMID: 32093740 PMCID: PMC7041264 DOI: 10.1186/s13567-020-00748-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 01/22/2020] [Indexed: 11/12/2022] Open
Abstract
The pore-forming protein epsilon toxin (Etx) from Clostridium perfringens produces acute perivascular edema affecting several organs, especially the brain and lungs. Despite the toxin evident effect on microvasculature and endothelial cells, the underlying molecular and cellular mechanisms remain obscure. Moreover, no Etx-sensitive endothelial cell model has been identified to date. Here, we characterize the mouse lung endothelial cell line 1G11 as an Etx-sensitive cell line and compare it with the well-characterized Etx-sensitive Madin-Darby canine kidney epithelial cell line. Several experimental approaches, including morphological and cytotoxic assays, clearly demonstrate that the 1G11 cell line is highly sensitive to Etx and show the specific binding, oligomerization, and pore-forming activity of the toxin in these cells. Recently, the myelin and lymphocyte (MAL) protein has been postulated as a putative receptor for Etx. Here, we show the presence of Mal mRNA in the 1G11 cell line and the presence of the MAL protein in the endothelium of some mouse lung vessels, supporting the hypothesis that this protein is a key element in the Etx intoxication pathway. The existence of an Etx-sensitive cell line of endothelial origin would help shed light on the cellular and molecular mechanisms underlying Etx-induced edema and its consequences.
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Affiliation(s)
- Jonatan Dorca-Arévalo
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, Spain. .,Biomedical Research Institute of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. .,Institute of Neurosciences, University of Barcelona, 08035, Barcelona, Spain.
| | - Eduard Dorca
- Pathology Service, Bellvitge University Hospital, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Benjamín Torrejón-Escribano
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, Spain.,Centres Científics i Tecnològics, Universitat de Barcelona, Campus Bellvitge, Barcelona, Spain
| | - Marta Blanch
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, Spain.,Biomedical Research Institute of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Institute of Neurosciences, University of Barcelona, 08035, Barcelona, Spain
| | - Mireia Martín-Satué
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, Spain.,Biomedical Research Institute of Bellvitge (IDIBELL), Oncobell Program, CIBERONC, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Juan Blasi
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, Spain.,Biomedical Research Institute of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Institute of Neurosciences, University of Barcelona, 08035, Barcelona, Spain
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10
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Abstract
Epithelial Na+ channels (ENaCs) are members of a family of cation channels that function as sensors of the extracellular environment. ENaCs are activated by specific proteases in the biosynthetic pathway and at the cell surface and remove embedded inhibitory tracts, which allows channels to transition to higher open-probability states. Resolved structures of ENaC and an acid-sensing ion channel revealed highly organized extracellular regions. Within the periphery of ENaC subunits are unique domains formed by antiparallel β-strands containing the inhibitory tracts and protease cleavage sites. ENaCs are inhibited by Na+ binding to specific extracellular site(s), which promotes channel transition to a lower open-probability state. Specific inositol phospholipids and channel modification by Cys-palmitoylation enhance channel open probability. How these regulatory factors interact in a concerted manner to influence channel open probability is an important question that has not been resolved. These various factors are reviewed, and the impact of specific factors on human disorders is discussed.
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Affiliation(s)
- Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, and Departments of Cell Biology and of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Douglas C Eaton
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
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11
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Linden JR, Flores C, Schmidt EF, Uzal FA, Michel AO, Valenzuela M, Dobrow S, Vartanian T. Clostridium perfringens epsilon toxin induces blood brain barrier permeability via caveolae-dependent transcytosis and requires expression of MAL. PLoS Pathog 2019; 15:e1008014. [PMID: 31703116 PMCID: PMC6867657 DOI: 10.1371/journal.ppat.1008014] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 11/20/2019] [Accepted: 08/01/2019] [Indexed: 12/13/2022] Open
Abstract
Clostridium perfringens epsilon toxin (ETX) is responsible for causing the economically devastating disease, enterotoxaemia, in livestock. It is well accepted that ETX causes blood brain barrier (BBB) permeability, however the mechanisms involved in this process are not well understood. Using in vivo and in vitro methods, we determined that ETX causes BBB permeability in mice by increasing caveolae-dependent transcytosis in brain endothelial cells. When mice are intravenously injected with ETX, robust ETX binding is observed in the microvasculature of the central nervous system (CNS) with limited to no binding observed in the vasculature of peripheral organs, indicating that ETX specifically targets CNS endothelial cells. ETX binding to CNS microvasculature is dependent on MAL expression, as ETX binding to CNS microvasculature of MAL-deficient mice was not detected. ETX treatment also induces extravasation of molecular tracers including 376Da fluorescein salt, 60kDA serum albumin, 70kDa dextran, and 155kDA IgG. Importantly, ETX-induced BBB permeability requires expression of both MAL and caveolin-1, as mice deficient in MAL or caveolin-1 did not exhibit ETX-induced BBB permeability. Examination of primary murine brain endothelial cells revealed an increase in caveolae in ETX-treated cells, resulting in dynamin and lipid raft-dependent vacuolation without cell death. ETX-treatment also results in a rapid loss of EEA1 positive early endosomes and accumulation of large, RAB7-positive late endosomes and multivesicular bodies. Based on these results, we hypothesize that ETX binds to MAL on the apical surface of brain endothelial cells, causing recruitment of caveolin-1, triggering caveolae formation and internalization. Internalized caveolae fuse with early endosomes which traffic to late endosomes and multivesicular bodies. We believe that these multivesicular bodies fuse basally, releasing their contents into the brain parenchyma. Clostridium perfringens epsilon toxin (ETX) is an extremely lethal bacterial toxin known to cause a devastating disease in livestock animals and may be a possible cause of multiple sclerosis in humans. ETX is well known to cause disruption of the blood-brain barrier (BBB), a critical structure necessary for proper brain function. Deterioration of this barrier allows entry of toxic blood-borne material to enter the brain. Although ETX-induced BBB dysfunction is well accepted, how this happens is unknown. Here, we demonstrate that ETX causes BBB permeability by inducing formation of cell-surface invaginations called caveolae in endothelial cells, the cells that line blood vessels. Importantly, only endothelial cells from the brain and other central nervous system organs appear to be a target of ETX, as the toxin only binds to blood vessels in these organs and not blood vessels from other organs. These ETX-induced caveolae fuse with other caveolae and specialized intracellular vesicles called endosomes. We predict that these endosomes engulf blood-borne material during their internalization, allowing material to travel from the blood, through the cell, and into brain tissue. We also show that expression of the protein MAL and caveolin-1 is necessary for ETX-induced BBB permeability.
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Affiliation(s)
- Jennifer R. Linden
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, New York, New York, United States of America
| | - Claudia Flores
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, New York, New York, United States of America
| | - Eric F. Schmidt
- Laboratory of Molecular Biology, The Rockefeller University, New York, New York, United States of America
| | - Francisco A. Uzal
- California Animal Health & Food Safety Laboratory System, San Bernardino Branch, University of California, Davis, San Bernardino, California, United States of America
| | - Adam O. Michel
- Laboratory of Comparative Pathology, Center of Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center, The Rockefeller University, Weill Cornell Medicine, New York, New York, United States of America
| | - Marissa Valenzuela
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, New York, New York, United States of America
| | - Sebastian Dobrow
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, New York, New York, United States of America
| | - Timothy Vartanian
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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12
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Lebreton S, Paladino S, Zurzolo C. Clustering in the Golgi apparatus governs sorting and function of GPI‐APs in polarized epithelial cells. FEBS Lett 2019; 593:2351-2365. [DOI: 10.1002/1873-3468.13573] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/29/2019] [Accepted: 08/05/2019] [Indexed: 01/25/2023]
Affiliation(s)
- Stéphanie Lebreton
- Unité de Trafic Membranaire et Pathogénèse Institut Pasteur Paris France
| | - Simona Paladino
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche Università degli Studi di Napoli Federico II Naples Italy
| | - Chiara Zurzolo
- Unité de Trafic Membranaire et Pathogénèse Institut Pasteur Paris France
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13
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A Serine/Threonine Kinase 16-Based Phospho-Proteomics Screen Identifies WD Repeat Protein-1 As A Regulator Of Constitutive Secretion. Sci Rep 2018; 8:13049. [PMID: 30158666 PMCID: PMC6115458 DOI: 10.1038/s41598-018-31426-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/14/2018] [Indexed: 01/03/2023] Open
Abstract
The plasma membrane of polarized hepatocytes is functionally divided into two domains: the apical and basolateral. Our focus is to define the molecular basis of polarized protein sorting of newly-synthesized membrane and secretory proteins in WIF-B cells, an excellent model system for polarized hepatocytes. We determined that MAL2 (myelin and lymphocyte protein 2) and its binding partner, serine/threonine kinase 16 (STK16) regulate basolateral constitutive secretion. Because STK16 is a constitutively active kinase, we reasoned that constitutively phosphorylated substrates must participate in constitutive secretion. To identify either STK16 substrates or other proteins that regulate constitutive secretion, we took a proteomics approach. Post-nuclear supernatants from cells expressing wild type or a kinase-dead (E202A) STK16 were separated on 2D gels and immunoblotted with antibodies against phospho-serine/threonine residues. Sixteen spots were identified from E202A-expressing cells that reproducibly displayed decreased immunoreactivity. From these spots, 28 proteins were identified as possible STK16 substrates. Out of these 28 possible substrates, 25% of them encode predicted STK16 phosphorylation consensus sites, with WD repeat containing protein-1 (WDR1) encoding two such sites. Based on this finding and on the finding that actin remodeling is required for hepatic secretion, we further confirmed that WDR1 is a phosphoprotein that regulates secretion.
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Dorca-Arévalo J, Blanch M, Pradas M, Blasi J. Epsilon toxin from Clostridium perfringens induces cytotoxicity in FRT thyroid epithelial cells. Anaerobe 2018; 53:43-49. [PMID: 29895394 DOI: 10.1016/j.anaerobe.2018.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/25/2018] [Accepted: 05/26/2018] [Indexed: 12/24/2022]
Abstract
Epsilon toxin (Etx) is produced by Clostridium perfringens and induces enterotoxemia in ruminants. Etx crosses the blood-brain barrier, binds to myelin structures, and kills oligodendrocytes, inducing central nervous system demyelination. In addition, Etx has a cytotoxic effect on distal and collecting kidney tubules. There are few cell lines sensitive to Etx. At present, the most sensitive in vitro model for Etx is the Madin-Darby canine kidney (MDCK) cell line, where Etx oligomerizes and forms a pore with consequent ion efflux and cell death. Although the Etx receptor has not yet been fully clarified, it is known that caveolin 1 and 2 potentiate Etx cytotoxicity and oligomerization, and more recently, the myelin and lymphocyte (MAL) protein has been implicated in Etx binding and activity. Here, we studied the effect of Etx on Fischer rat thyroid cells (FRT) and observed similar effects as those seen in MDCK cells. Etx incubated with FRT cells showed binding to the plasma membrane, and western blotting assays revealed oligomeric complex formation. Moreover, cytotoxic assays on FRT cells after Etx incubation indicated cell death at a similar level as in MDCK cells. In addition, a luminescent ATP detection assay revealed ATP depletion in FRT cells after Etx exposure. Previous studies have reported that FRT cells do not express caveolins and do not form caveolae but express MAL protein in glycolipid-enriched membrane microdomains. Our results indicate that caveolins are not directly implicated in Etx cytotoxicity, supporting the notion that the MAL protein is involved in Etx action. In addition, a cell line of thyroid origin is described for the first time as a good model to study Etx action.
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Affiliation(s)
- Jonatan Dorca-Arévalo
- Laboratory of Cellular and Molecular Neurobiology, Department of Pathology and Experimental Therapeutics, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, 08907, Spain; Biomedical Research Institute of Bellvitge (IDIBELL), Hospitalet de Llobregat, Barcelona, 08907, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona 08035, Spain
| | - Marta Blanch
- Laboratory of Cellular and Molecular Neurobiology, Department of Pathology and Experimental Therapeutics, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, 08907, Spain; Biomedical Research Institute of Bellvitge (IDIBELL), Hospitalet de Llobregat, Barcelona, 08907, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona 08035, Spain
| | - Marina Pradas
- Laboratory of Cellular and Molecular Neurobiology, Department of Pathology and Experimental Therapeutics, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, 08907, Spain
| | - Juan Blasi
- Laboratory of Cellular and Molecular Neurobiology, Department of Pathology and Experimental Therapeutics, Campus of Bellvitge, University of Barcelona, Hospitalet de Llobregat, Barcelona, 08907, Spain; Biomedical Research Institute of Bellvitge (IDIBELL), Hospitalet de Llobregat, Barcelona, 08907, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona 08035, Spain.
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15
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Performance of a Commercially Available MAL Antibody in the Diagnosis of Primary Mediastinal Large B-Cell Lymphoma. Am J Surg Pathol 2017; 41:189-194. [DOI: 10.1097/pas.0000000000000771] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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16
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Vukićević T, Schulz M, Faust D, Klussmann E. The Trafficking of the Water Channel Aquaporin-2 in Renal Principal Cells-a Potential Target for Pharmacological Intervention in Cardiovascular Diseases. Front Pharmacol 2016; 7:23. [PMID: 26903868 PMCID: PMC4749865 DOI: 10.3389/fphar.2016.00023] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/25/2016] [Indexed: 01/13/2023] Open
Abstract
Arginine-vasopressin (AVP) stimulates the redistribution of water channels, aquaporin-2 (AQP2) from intracellular vesicles into the plasma membrane of renal collecting duct principal cells. By this AVP directs 10% of the water reabsorption from the 170 L of primary urine that the human kidneys produce each day. This review discusses molecular mechanisms underlying the AVP-induced redistribution of AQP2; in particular, it provides an overview over the proteins participating in the control of its localization. Defects preventing the insertion of AQP2 into the plasma membrane cause diabetes insipidus. The disease can be acquired or inherited, and is characterized by polyuria and polydipsia. Vice versa, up-regulation of the system causing a predominant localization of AQP2 in the plasma membrane leads to excessive water retention and hyponatremia as in the syndrome of inappropriate antidiuretic hormone secretion (SIADH), late stage heart failure or liver cirrhosis. This article briefly summarizes the currently available pharmacotherapies for the treatment of such water balance disorders, and discusses the value of newly identified mechanisms controlling AQP2 for developing novel pharmacological strategies. Innovative concepts for the therapy of water balance disorders are required as there is a medical need due to the lack of causal treatments.
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Affiliation(s)
- Tanja Vukićević
- Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association Berlin, Germany
| | - Maike Schulz
- Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association Berlin, Germany
| | - Dörte Faust
- Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association Berlin, Germany
| | - Enno Klussmann
- Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz AssociationBerlin, Germany; German Centre for Cardiovascular ResearchBerlin, Germany
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17
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Muñiz M, Riezman H. Trafficking of glycosylphosphatidylinositol anchored proteins from the endoplasmic reticulum to the cell surface. J Lipid Res 2015; 57:352-60. [PMID: 26450970 DOI: 10.1194/jlr.r062760] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Indexed: 11/20/2022] Open
Abstract
In eukaryotes, many cell surface proteins are attached to the plasma membrane via a glycolipid glycosylphosphatidylinositol (GPI) anchor. GPI-anchored proteins (GPI-APs) receive the GPI anchor as a conserved posttranslational modification in the lumen of the endoplasmic reticulum (ER). After anchor attachment, the GPI anchor is structurally remodeled to function as a transport signal that actively triggers the delivery of GPI-APs from the ER to the plasma membrane, via the Golgi apparatus. The structure and composition of the GPI anchor confer a special mode of interaction with membranes of GPI-APs within the lumen of secretory organelles that lead them to be differentially trafficked from other secretory membrane proteins. In this review, we examine the mechanisms by which GPI-APs are selectively transported through the secretory pathway, with special focus on the recent progress made in their actively regulated export from the ER and the trans-Golgi network.
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Affiliation(s)
- Manuel Muñiz
- Departamento de Biología Celular, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain Universidad de Sevilla and Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - Howard Riezman
- National Centre of Competence in Research (NCCR) Chemical Biology, Department of Biochemistry, University of Geneva, Geneva, Switzerland
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18
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Nyholm TK. Lipid-protein interplay and lateral organization in biomembranes. Chem Phys Lipids 2015; 189:48-55. [DOI: 10.1016/j.chemphyslip.2015.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 05/27/2015] [Accepted: 05/29/2015] [Indexed: 01/07/2023]
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19
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Rumah KR, Ma Y, Linden JR, Oo ML, Anrather J, Schaeren-Wiemers N, Alonso MA, Fischetti VA, McClain MS, Vartanian T. The Myelin and Lymphocyte Protein MAL Is Required for Binding and Activity of Clostridium perfringens ε-Toxin. PLoS Pathog 2015; 11:e1004896. [PMID: 25993478 PMCID: PMC4439126 DOI: 10.1371/journal.ppat.1004896] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 04/19/2015] [Indexed: 12/18/2022] Open
Abstract
Clostridium perfringens ε-toxin (ETX) is a potent pore-forming toxin responsible for a central nervous system (CNS) disease in ruminant animals with characteristics of blood-brain barrier (BBB) dysfunction and white matter injury. ETX has been proposed as a potential causative agent for Multiple Sclerosis (MS), a human disease that begins with BBB breakdown and injury to myelin forming cells of the CNS. The receptor for ETX is unknown. Here we show that both binding of ETX to mammalian cells and cytotoxicity requires the tetraspan proteolipid Myelin and Lymphocyte protein (MAL). While native Chinese Hamster Ovary (CHO) cells are resistant to ETX, exogenous expression of MAL in CHO cells confers both ETX binding and susceptibility to ETX-mediated cell death. Cells expressing rat MAL are ~100 times more sensitive to ETX than cells expressing similar levels of human MAL. Insertion of the FLAG sequence into the second extracellular loop of MAL abolishes ETX binding and cytotoxicity. ETX is known to bind specifically and with high affinity to intestinal epithelium, renal tubules, brain endothelial cells and myelin. We identify specific binding of ETX to these structures and additionally show binding to retinal microvasculature and the squamous epithelial cells of the sclera in wild-type mice. In contrast, there is a complete absence of ETX binding to tissues from MAL knockout (MAL-/-) mice. Furthermore, MAL-/- mice exhibit complete resistance to ETX at doses in excess of 1000 times the symptomatic dose for wild-type mice. We conclude that MAL is required for both ETX binding and cytotoxicity.
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Affiliation(s)
- Kareem Rashid Rumah
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
- Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York City, New York, United States of America
| | - Yinghua Ma
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Jennifer R. Linden
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Myat Lin Oo
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Josef Anrather
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Nicole Schaeren-Wiemers
- Neurobiology, Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Miguel A. Alonso
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, Madrid, Spain
| | - Vincent A. Fischetti
- Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York City, New York, United States of America
| | - Mark S. McClain
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Timothy Vartanian
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
- * E-mail:
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20
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Paladino S, Lebreton S, Zurzolo C. Trafficking and Membrane Organization of GPI-Anchored Proteins in Health and Diseases. CURRENT TOPICS IN MEMBRANES 2015; 75:269-303. [PMID: 26015286 DOI: 10.1016/bs.ctm.2015.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are a class of lipid-anchored proteins attached to the membranes by a glycolipid anchor that is added, as posttranslation modification, in the endoplasmic reticulum. GPI-APs are expressed at the cell surface of eukaryotes where they play diverse vital functions. Like all plasma membrane proteins, GPI-APs must be correctly sorted along the different steps of the secretory pathway to their final destination. The presence of both a glycolipid anchor and a protein portion confers special trafficking features to GPI-APs. Here, we discuss the recent advances in the field of GPI-AP trafficking, focusing on the mechanisms regulating their biosynthetic pathway and plasma membrane organization. We also discuss how alterations of these mechanisms can result in different diseases. Finally, we will examine the strict relationship between the trafficking and function of GPI-APs in epithelial cells.
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Affiliation(s)
- Simona Paladino
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Napoli, Italy; CEINGE Biotecnologie Avanzate, Napoli, Italy
| | - Stéphanie Lebreton
- Unité de Trafic Membranaire et Pathogénèse, Institut Pasteur, Paris, France
| | - Chiara Zurzolo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Napoli, Italy; Unité de Trafic Membranaire et Pathogénèse, Institut Pasteur, Paris, France
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21
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Clay CC, Reader JR, Gerriets JE, Wang TT, Harrod KS, Miller LA. Enhanced viral replication and modulated innate immune responses in infant airway epithelium following H1N1 infection. J Virol 2014; 88:7412-25. [PMID: 24741104 PMCID: PMC4054429 DOI: 10.1128/jvi.00188-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/12/2014] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza is the cause of significant morbidity and mortality in pediatric populations. The contribution of pulmonary host defense mechanisms to viral respiratory infection susceptibility in very young children is poorly understood. As a surrogate to compare mucosal immune responses of infant and adult lungs, rhesus monkey primary airway epithelial cell cultures were infected with pandemic influenza A/H1N1 virus in vitro. Virus replication, cytokine secretion, cell viability, and type I interferon (IFN) pathway PCR array profiles were evaluated for both infant and adult cultures. In comparison with adult cultures, infant cultures showed significantly increased levels of H1N1 replication, reduced alpha interferon (IFN-α) protein synthesis, and no difference in cell death following infection. Age-dependent differences in expression levels of multiple genes associated with the type I IFN pathway were observed in H1N1-infected cultures. To investigate the pulmonary and systemic responses to H1N1 infection in early life, infant monkeys were inoculated with H1N1 by upper airway administration. Animals were monitored for virus and parameters of inflammation over a 14-day period. High H1N1 titers were recovered from airways at day 1, with viral RNA remaining detectable until day 9 postinfection. Despite viral clearance, bronchiolitis and alveolitis persisted at day 14 postinfection; histopathological analysis revealed alveolar septal thickening and intermittent type II pneumocyte hyperplasia. Our overall findings are consistent with the known susceptibility of pediatric populations to respiratory virus infection and suggest that intrinsic developmental differences in airway epithelial cell immune function may contribute to the limited efficacy of host defense during early childhood. IMPORTANCE To the best of our knowledge, this study represents the first report of intrinsic developmental differences in infant airway epithelial cells that may contribute to the increased susceptibility of the host to respiratory virus infections. Despite the global burden of influenza, there are currently no vaccine formulations approved for children <6 months of age. Given the challenges of conducting experimental studies involving pediatric patients, rhesus monkeys are an ideal laboratory animal model to investigate the maturation of pulmonary mucosal immune mechanisms during early life because they are most similar to those of humans with regard to postnatal maturation of the lung structure and the immune system. Thus, our findings are highly relevant to translational medicine, and these data may ultimately lead to novel approaches that enhance airway immunity in very young children.
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Affiliation(s)
- Candice C Clay
- California National Primate Research Center, University of California, Davis, California, USA
| | - J Rachel Reader
- California National Primate Research Center, University of California, Davis, California, USA
| | - Joan E Gerriets
- California National Primate Research Center, University of California, Davis, California, USA
| | - Theodore T Wang
- California National Primate Research Center, University of California, Davis, California, USA
| | - Kevin S Harrod
- Infectious Disease Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Lisa A Miller
- California National Primate Research Center, University of California, Davis, California, USA Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, California, USA
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22
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Muñiz M, Zurzolo C. Sorting of GPI-anchored proteins from yeast to mammals--common pathways at different sites? J Cell Sci 2014; 127:2793-801. [PMID: 24906797 DOI: 10.1242/jcs.148056] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are luminal secretory cargos that are attached by a post-translational glycolipid modification, the GPI anchor, to the external leaflet of the plasma membrane. GPI-APs are conserved among eukaryotes and possess many diverse and vital functions for which the GPI membrane attachment appears to be essential. The presence of the GPI anchor and its subsequent modifications along the secretory pathway confer to the anchored proteins unique trafficking properties that make GPI-APs an exceptional system to study mechanisms of sorting. In this Commentary, we discuss the recent advances in the field of GPI-AP sorting focusing on the mechanisms operating at the level of the exit from the ER and from the trans-Golgi network (TGN), which take place, respectively, in yeast and in polarized mammalian cells. By considering the similarities and differences between these two sorting events, we present unifying principles that appear to work at different sorting stations and in different organisms.
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Affiliation(s)
- Manuel Muñiz
- Department of Cell Biology, University of Seville, Avda. Reina Mercedes s/n 41012 Seville, Spain
| | - Chiara Zurzolo
- Institut Pasteur, Unité de Trafic Membranaire et Pathogénèse, 75724 Paris CEDEX 15, France
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MAL hypermethylation is a tissue-specific event that correlates with MAL mRNA expression in esophageal carcinoma. Sci Rep 2013; 3:2838. [PMID: 24088706 PMCID: PMC3789153 DOI: 10.1038/srep02838] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 09/16/2013] [Indexed: 01/10/2023] Open
Abstract
MAL promoter hypermethylation was examined in 260 human esophageal specimens using real-time quantitative methylation-specific PCR (qMSP). MAL hypermethylation showed highly discriminative ROC curve profiles which clearly distinguished esophageal adenocarcinomas (EAC) from both esophageal squamous cell carcinomas (ESCC) and normal esophagus (NE). Both MAL methylation frequency and normalized methylation value (NMV) were significantly higher in Barrett's esophagus (BE), dysplastic BE, and EAC than in ESCC or in NE. Among matched NE and EAC samples, MAL NMVs in EAC were significantly higher than in corresponding NE. There was a significant correlation between MAL hypermethylation and BE segment length. Treatment with 5-aza-2′-deoxycytidine reversed MAL methylation and reactivated MAL mRNA expression in OE33 EAC cells. MAL mRNA levels in EACs with unmethylated MAL were significantly higher than in EACs with methylated MAL. MAL hypermethylation is a common, tissue-specific event in human EAC and correlates with clinical neoplastic progression risk factors.
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24
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Expression of myelin and lymphocyte protein (MAL) in oral carcinogenesis. Med Mol Morphol 2012; 45:222-8. [DOI: 10.1007/s00795-011-0563-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 09/12/2011] [Indexed: 11/26/2022]
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25
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Zhou G, Liang FX, Romih R, Wang Z, Liao Y, Ghiso J, Luque-Garcia JL, Neubert TA, Kreibich G, Alonso MA, Schaeren-Wiemers N, Sun TT. MAL facilitates the incorporation of exocytic uroplakin-delivering vesicles into the apical membrane of urothelial umbrella cells. Mol Biol Cell 2012; 23:1354-66. [PMID: 22323295 PMCID: PMC3315800 DOI: 10.1091/mbc.e11-09-0823] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
MAL, suggested to play a key role in the apical sorting of membrane proteins, is not involved in the apical sorting of uroplakins. Instead, it plays an important role in facilitating the incorporation of the uroplakin-delivering exocytic vesicles into the apical surface of terminally differentiated urothelial umbrella cells. The apical surface of mammalian bladder urothelium is covered by large (500–1000 nm) two-dimensional (2D) crystals of hexagonally packed 16-nm uroplakin particles (urothelial plaques), which play a role in permeability barrier function and uropathogenic bacterial binding. How the uroplakin proteins are delivered to the luminal surface is unknown. We show here that myelin-and-lymphocyte protein (MAL), a 17-kDa tetraspan protein suggested to be important for the apical sorting of membrane proteins, is coexpressed with uroplakins in differentiated urothelial cell layers. MAL depletion in Madin–Darby canine kidney cells did not affect, however, the apical sorting of uroplakins, but it decreased the rate by which uroplakins were inserted into the apical surface. Moreover, MAL knockout in vivo led to the accumulation of fusiform vesicles in mouse urothelial superficial umbrella cells, whereas MAL transgenic overexpression in vivo led to enhanced exocytosis and compensatory endocytosis, resulting in the accumulation of the uroplakin-degrading multivesicular bodies. Finally, although MAL and uroplakins cofloat in detergent-resistant raft fractions, they are associated with distinct plaque and hinge membrane subdomains, respectively. These data suggest a model in which 1) MAL does not play a role in the apical sorting of uroplakins; 2) the propensity of uroplakins to polymerize forming 16-nm particles and later large 2D crystals that behave as detergent-resistant (giant) rafts may drive their apical targeting; 3) the exclusion of MAL from the expanding 2D crystals of uroplakins explains the selective association of MAL with the hinge areas in the uroplakin-delivering fusiform vesicles, as well as at the apical surface; and 4) the hinge-associated MAL may play a role in facilitating the incorporation of the exocytic uroplakin vesicles into the corresponding hinge areas of the urothelial apical surface.
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Affiliation(s)
- Ge Zhou
- Department of Cell Biology, NYU Cancer Institute, NYU Langone Medical Center, New York University, New York, NY 10016, USA
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MAL, but not MAL2, expression promotes the formation of cholesterol-dependent membrane domains that recruit apical proteins. Biochem J 2011; 439:497-504. [PMID: 21732912 DOI: 10.1042/bj20110803] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Our recent studies have been aimed at understanding the mechanisms regulating apical protein sorting in polarized epithelial cells. In particular, we have been investigating how lipid rafts serve to sort apical proteins in the biosynthetic pathway. The recent findings that lipid domains are too small or transient to host apically destined cargo have led to newer versions of the hypothesis that invoke proteins required for lipid domain coalescence and stabilization. MAL (myelin and lymphocyte protein) and its highly conserved family member, MAL2, have emerged as possible regulators of this process in the direct and indirect apical trafficking pathways respectively. To test this possibility, we took a biochemical approach. We determined that MAL, but not MAL2, self-associates, forms higher-order cholesterol-dependent complexes with apical proteins and promotes the formation of detergent-resistant membranes that recruit apical proteins. Such biochemical properties are consistent with a role for MAL in raft coalescence and stabilization. These findings also support a model whereby hydrophobic mismatch between the long membrane-spanning helices of MAL and the short-acyl-chain phospholipids in the Golgi drive formation of lipid domains rich in raft components that are characterized by a thicker hydrophobic core to alleviate mismatch.
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Formin INF2 regulates MAL-mediated transport of Lck to the plasma membrane of human T lymphocytes. Blood 2010; 116:5919-29. [DOI: 10.1182/blood-2010-08-300665] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Expression of the src-family kinase lymphocyte-specific protein tyrosine kinase (Lck) at the plasma membrane is essential for it to fulfill its pivotal role in signal transduction in T lymphocytes. MAL, an integral membrane protein expressed in specific types of lymphoma, has been shown to play an important role in targeting Lck to the plasma membrane. Here we report that MAL interacts with Inverted Formin2 (INF2), a formin with the atypical property of promoting not only actin polymerization but also its depolymerization. In Jurkat T cells, INF2 colocalizes with MAL at the cell periphery and pericentriolar endosomes and along microtubules. Videomicroscopic analysis revealed that the MAL+ vesicles transporting Lck to the plasma membrane move along microtubule tracks. Knockdown of INF2 greatly reduced the formation of MAL+ transport vesicles and the levels of Lck at the plasma membrane and impaired formation of a normal immunologic synapse. The actin polymerization and depolymerization activities of INF2 were both required for efficient Lck targeting. Cdc42 and Rac1, which bind to INF2, regulate Lck transport in both Jurkat and primary human T cells. Thus, INF2 collaborates with MAL in the formation of specific carriers for targeting Lck to the plasma membrane in a process regulated by Cdc42 and Rac1.
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Cao W, Zhang ZY, Xu Q, Sun Q, Yan M, Zhang J, Zhang P, Han ZG, Chen WT. Epigenetic silencing of MAL, a putative tumor suppressor gene, can contribute to human epithelium cell carcinoma. Mol Cancer 2010; 9:296. [PMID: 21092172 PMCID: PMC3002926 DOI: 10.1186/1476-4598-9-296] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 11/22/2010] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND To identify new and useful candidate biomarkers in head and neck squamous cell carcinoma (HNSCC), we performed a genome-wide survey and found that Myelin and lymphocyte-associated protein (MAL) was a gene that was markedly down-regulated in HNSCC. Hence, we investigated the mechanism of MAL silencing and the effects of MAL on the proliferation, invasion, and apoptotic potential in HNSCC. RESULTS MAL was significantly down-regulated in 91.7% of HNSCC specimens at the mRNA level as compared with adjacent normal tissues (P = 0.0004). Moreover, the relative transcript levels of the MAL gene were remarkably decreased by five-fold in nine HNSCC cell lines as compared with normal head and neck epithelium cells. MAL gene expression was restored in 44%, 67%, and 89% in HNSCC cell lines treated with TSA, 5-Aza-dC, and TSA plus 5-Aza-dC, respectively. Furthermore, bisulfate-treated DNA sequencing demonstrated that the two CpG islands (that is, M1 and M2) located in MAL promoter region were completely methylated in the HNSCC cell lines (CpG methylated ratio was more than 90%), and only one CpG island (that is, M1) was partially methylated in HNSCC tissues (CpG methylated ratio between 20% and 90%). A significant reduction in cell proliferation and a change in the cell cycle profile were also observed in MAL transfectants. Matrigel assay demonstrated that the invasiveness of HNSCC cells significantly decreased. A significant increase in the population of apoptotic cells was observed in MAL transfected cells. The exogenous expression of the MAL gene suppressed malignant phenotypes, while the cell death induced by MAL gene transfer was a result of apoptosis as demonstrated by the induction of cleavage of the poly (that is, ADP-ribose) polymerase. Additionally, tumor growth was suppressed in cells expressing MAL as compared with cells not expressing MAL. CONCLUSION Our data suggest that the epigenetic inactivation of MAL, as a candidate tumor suppressor gene, can contribute to human epithelial cell carcinoma and may be served as a biomarker in HNSCC.
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MESH Headings
- Apoptosis/genetics
- Apoptosis/physiology
- Blotting, Western
- Carcinoma/genetics
- Carcinoma/metabolism
- Carcinoma, Squamous Cell
- Cell Cycle/genetics
- Cell Cycle/physiology
- Cell Line, Tumor
- Cell Proliferation
- DNA Methylation/genetics
- Epigenesis, Genetic/genetics
- Gene Expression Regulation, Neoplastic/genetics
- Gene Expression Regulation, Neoplastic/physiology
- Head and Neck Neoplasms/genetics
- Head and Neck Neoplasms/metabolism
- Humans
- Membrane Transport Proteins/genetics
- Membrane Transport Proteins/metabolism
- Microscopy, Confocal
- Myelin Proteins/genetics
- Myelin Proteins/metabolism
- Myelin and Lymphocyte-Associated Proteolipid Proteins
- Neoplasms, Squamous Cell/genetics
- Neoplasms, Squamous Cell/metabolism
- Polymerase Chain Reaction
- Promoter Regions, Genetic/genetics
- Proteolipids/genetics
- Proteolipids/metabolism
- RNA, Messenger/genetics
- Squamous Cell Carcinoma of Head and Neck
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Affiliation(s)
- Wei Cao
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Zhi-yuan Zhang
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Qin Xu
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Qiang Sun
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Ming Yan
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Jun Zhang
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Ping Zhang
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
| | - Ze-guang Han
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
- Chinese National Human Genome Center at Shanghai, 201203, China
| | - Wan-tao Chen
- Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Key Laboratory of Stomatology, Shanghai 200011, China
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Carmosino M, Rizzo F, Procino G, Basco D, Valenti G, Forbush B, Schaeren-Wiemers N, Caplan MJ, Svelto M. MAL/VIP17, a new player in the regulation of NKCC2 in the kidney. Mol Biol Cell 2010; 21:3985-97. [PMID: 20861303 PMCID: PMC2982131 DOI: 10.1091/mbc.e10-05-0456] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The renal-specific Na+-K+-2Cl- cotransporter (NKCC2) is the major salt transport pathway of the apical membrane of the mammalian thick ascending limb of Henle's loop. Here, we analyze the role of the tetraspan protein myelin and lymphocytes-associated protein (MAL)/VIP17 in the regulation of NKCC2. We demonstrated that 1) NKCC2 and MAL/VIP17 colocalize and coimmunoprecipitate in Lilly Laboratories cell porcine kidney cells (LLC-PK1) as well as in rat kidney medullae, 2) a 150-amino acid stretch of NKCC2 C-terminal tail is involved in the interaction with MAL/VIP17, 3) MAL/VIP17 increases the cell surface retention of NKCC2 by attenuating its internalization, and 4) this coincides with an increase in cotransporter phosphorylation. Interestingly, overexpression of MAL/VIP17 in the kidney of transgenic mice results in cysts formation in distal nephron structures consistent with the hypothesis that MAL/VIP17 plays an important role in apical sorting or in maintaining the stability of the apical membrane. The NKCC2 expressed in these mice was highly glycosylated and phosphorylated, suggesting that MAL/VIP17 also is involved in the stabilization of NKCC2 at the apical membrane in vivo. Thus, the involvement of MAL/VIP17 in the activation and surface expression of NKCC2 could play an important role in the regulated absorption of Na+ and Cl- in the kidney.
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Affiliation(s)
- Monica Carmosino
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06511, USA.
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30
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In JG, Tuma PL. MAL2 selectively regulates polymeric IgA receptor delivery from the Golgi to the plasma membrane in WIF-B cells. Traffic 2010; 11:1056-66. [PMID: 20444237 DOI: 10.1111/j.1600-0854.2010.01074.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Myelin and lymphocyte protein 2 (MAL2) has been identified as a hepatic transcytotic regulator that mediates delivery from basolateral endosomes to the subapical compartment (SAC). However, overexpression of polymeric immunoglobulin A-receptor (pIgA-R) in polarized, hepatic WIF-B cells led to the dramatic redistribution of MAL2 into the Golgi and all the transcytotic intermediates occupied by the receptor. Although overexpressed hemagglutinin and dipeptidylpeptidase IV (DPPIV) distributed to the same compartments, MAL2 distributions did not change indicating the effect is selective. Cycloheximide treatment led to decreased pIgA-R and MAL2 intracellular staining, first in the Golgi then the SAC, suggesting they were apically delivered and that MAL2 was mediating the process. This was tested in Clone 9 cells (that lack endogenous MAL2). When expressed alone, pIgA-R was restricted to the Golgi whereas when coexpressed with MAL2, it distributed to the surface, was internalized and delivered to MAL2-positive puncta. In contrast, DPPIV distributions were independent of MAL2. Surface delivery of newly synthesized pIgA-R, but not DPPIV, was enhanced greater than ninefold by MAL2 coexpression. In WIF-B cells where MAL2 expression was knocked down, pIgA-R, but not DPPIV, was retained in the Golgi and its basolateral delivery was impaired. Thus, in addition to its role in transcytosis, MAL2 also regulates pIgA-R delivery from the Golgi to the plasma membrane.
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Affiliation(s)
- Julie G In
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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Lee PS, Teaberry VS, Bland AE, Huang Z, Whitaker RS, Baba T, Fujii S, Secord AA, Berchuck A, Murphy SK. Elevated MAL expression is accompanied by promoter hypomethylation and platinum resistance in epithelial ovarian cancer. Int J Cancer 2010; 126:1378-89. [PMID: 19642140 DOI: 10.1002/ijc.24797] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We previously found that the gene encoding the Myelin and Lymphocyte protein, MAL, was among the most highly expressed genes in serous ovarian cancers from short-term survivors (<3 years) relative to those of long-term survivors (>7 years). In the present study, we have found that this difference in expression is partially attributable to differences in DNA methylation at a specific region within the MAL promoter CpG island. While MAL was largely unmethylated at the transcription start site (Region 1; -48 to +73 bp) in primary serous ovarian cancers, methylation of an upstream region (Region 2; -452 to -266 bp) was inversely correlated with MAL transcription in the primary cancers (R = -0.463) and ovarian cancer cell lines (R = -0.444). Following treatment of the OVCA432 cell line with 5-azacytidine, methylation of Region 2 decreased from 73.3% to 34.7% (p = 0.007) while Region 1 was unaffected. This was accompanied by a 10-fold increase in MAL expression. Since MAL transcripts are elevated in tumors from short-term survivors, all of whom were treated with platinum-based therapy, MAL may have a role in cisplatin response. We therefore determined the 50% growth inhibitory dose of cisplatin in 30 ovarian cancer cell lines and compared this to MAL expression. MAL transcript levels were higher in the resistant ovarian cell lines (p = 0.04). MAL methylation status may therefore serve as a marker of platinum sensitivity while MAL protein may be a target for development of novel therapies aimed at enhancing sensitivity to platinum-based drugs in ovarian cancer.
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Affiliation(s)
- Paula S Lee
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC 27708, USA
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Jackman N, Ishii A, Bansal R. Oligodendrocyte development and myelin biogenesis: parsing out the roles of glycosphingolipids. Physiology (Bethesda) 2009; 24:290-7. [PMID: 19815855 DOI: 10.1152/physiol.00016.2009] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The myelin sheath is an extension of the oligoddendrocyte (OL) plasma membrane enriched in lipids that ensheaths the axons of the central and peripheral nervous system. Here, we review the involvement of glycosphingolipids in myelin/OL functions, including the regulation of OL differentiation, lipid raft-mediated trafficking and signaling, and neuron-glia interactions.
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Affiliation(s)
- Nicole Jackman
- Department of Neuroscience, University of Connecticut Medical School, Farmington, Connecticut, USA
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33
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Dukhovny A, Goldstein Magal L, Hirschberg K. The MAL proteolipid restricts detergent-mediated membrane pore expansion and percolation. Mol Membr Biol 2009; 23:245-57. [PMID: 16785208 DOI: 10.1080/09687860600601445] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Differential solubilization of membrane components by cold 1% Triton X-100 extraction is common practice in cell biology and membrane research, used to define components of, or localization within membrane domains called lipid rafts. In this study, extraction of biological membranes was continuously monitored in single cells by confocal microscopy. The distributions of fluorescently-tagged proteins that label raft and non-raft membranes, cytosolic and cytoskeletal proteins were continuously monitored upon addition of the detergent. Membranes containing the non-raft membrane protein VSVG-GFP were immediately extracted from the plasma membrane, whereas raft-membrane proteins were predominantly resistant to the detergent. The morphological characteristics of differential membrane solubilization consisted of the formation of pores that expand and percolate as the detergent-mediated solubilization proceeds. Pore expansion and percolation was much slower and more restricted in non-polarized MDCK cells than in COS-7 cells. Heterologous overexpression in COS-7 cells of the fluorescently-tagged human MAL, a tetra-spanning, lipid-raft-associated protein, significantly slowed and limited membrane pore expansion and percolation. Extensive percolation resulting in large holes in the membrane was observed for the raft-associated, GPI-GFP-labeled membranes in COS-7 cells. Quantitative analysis carried out using pixel intensity variance as an indicator of membrane pore expansion demonstrated that the MAL protein is capable of modifying the plasma membrane, thereby increasing its resistance to detergent-induced pore formation.
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Affiliation(s)
- Anna Dukhovny
- Department of Pathology, Sackler School of Medicine, Tel Aviv University, Israel
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34
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Overmeer RM, Henken FE, Bierkens M, Wilting SM, Timmerman I, Meijer CJLM, Snijders PJF, Steenbergen RDM. Repression of MAL tumour suppressor activity by promoter methylation during cervical carcinogenesis. J Pathol 2009; 219:327-36. [DOI: 10.1002/path.2598] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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35
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Magal LG, Yaffe Y, Shepshelovich J, Aranda JF, de Marco MDC, Gaus K, Alonso MA, Hirschberg K. Clustering and lateral concentration of raft lipids by the MAL protein. Mol Biol Cell 2009; 20:3751-62. [PMID: 19553470 DOI: 10.1091/mbc.e09-02-0142] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
MAL, a compact hydrophobic, four-transmembrane-domain apical protein that copurifies with detergent-resistant membranes is obligatory for the machinery that sorts glycophosphatidylinositol (GPI)-anchored proteins and others to the apical membrane in epithelia. The mechanism of MAL function in lipid-raft-mediated apical sorting is unknown. We report that MAL clusters formed by two independent procedures-spontaneous clustering of MAL tagged with the tandem dimer DiHcRED (DiHcRED-MAL) in the plasma membrane of COS7 cells and antibody-mediated cross-linking of FLAG-tagged MAL-laterally concentrate markers of sphingolipid rafts and exclude a fluorescent analogue of phosphatidylethanolamine. Site-directed mutagenesis and bimolecular fluorescence complementation analysis demonstrate that MAL forms oligomers via xx intramembrane protein-protein binding motifs. Furthermore, results from membrane modulation by using exogenously added cholesterol or ceramides support the hypothesis that MAL-mediated association with raft lipids is driven at least in part by positive hydrophobic mismatch between the lengths of the transmembrane helices of MAL and membrane lipids. These data place MAL as a key component in the organization of membrane domains that could potentially serve as membrane sorting platforms.
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Buser AM, Schmid D, Kern F, Erne B, Lazzati T, Schaeren-Wiemers N. The myelin protein MAL affects peripheral nerve myelination: a new player influencing p75 neurotrophin receptor expression. Eur J Neurosci 2009; 29:2276-90. [PMID: 19508690 DOI: 10.1111/j.1460-9568.2009.06785.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The myelin and lymphocyte protein (MAL) is a raft-associated membrane protein predominantly expressed by oligodendrocytes and Schwann cells. Here we show that MAL regulates myelination in the peripheral nervous system. In mice overexpressing MAL, myelination was retarded and fibers were hypomyelinated, whereas myelination in MAL knockout mice was accelerated. This was not due to impaired Schwann cell proliferation, differentiation or axonal sorting. We found that the expression level of p75 neurotrophin receptor mRNA and protein was strongly reduced in developing sciatic nerves in MAL-overexpressing mice. This reduction is well correlated with the observed alterations in myelination initiation, speed of myelination and alterations in Remak bundle development. Our results suggest a functional role for MAL in peripheral myelination by influencing the expression of membrane components that mediate axon-glia interaction during ensheathment and myelin wrapping.
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Affiliation(s)
- A M Buser
- Neurobiology, Department of Biomedicine and Neurology, University Hospital Basel, Basel, Switzerland
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37
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Horne HN, Lee PS, Murphy SK, Alonso MA, Olson JA, Marks JR. Inactivation of the MAL gene in breast cancer is a common event that predicts benefit from adjuvant chemotherapy. Mol Cancer Res 2009; 7:199-209. [PMID: 19208741 DOI: 10.1158/1541-7786.mcr-08-0314] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dysregulation of MAL (myelin and lymphocyte protein) has been implicated in several malignancies including esophageal, ovarian, and cervical cancers. The MAL protein functions in apical transport in polarized epithelial cells; therefore, its disruption may lead to loss of organized polarity characteristic of most solid malignancies. Bisulfite sequencing of the MAL promoter CpG island revealed hypermethylation in breast cancer cell lines and 69% of primary tumors analyzed compared with normal breast epithelial cells. Differential methylation between normal and cancer DNA was confined to the proximal promoter region. In a subset of breast cancer cell lines including T47D and MCF7 cells, promoter methylation correlated with transcriptional silencing that was reversible with the methylation inhibitor 5-aza-2'-deoxycytidine. In addition, expression of MAL reduced motility and resulted in a redistribution of lipid raft components in MCF10A cells. MAL protein expression measured by immunohistochemistry revealed no significant correlation with clinicopathologic features. However, in patients who did not receive adjuvant chemotherapy, reduced MAL expression was a significant predictive factor for disease-free survival. These data implicate MAL as a commonly altered gene in breast cancer with implications for response to chemotherapy.
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Affiliation(s)
- Hisani N Horne
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA.
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Fanayan S, Shehata M, Agterof AP, McGuckin MA, Alonso MA, Byrne JA. Mucin 1 (MUC1) is a novel partner for MAL2 in breast carcinoma cells. BMC Cell Biol 2009; 10:7. [PMID: 19175940 PMCID: PMC2644682 DOI: 10.1186/1471-2121-10-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Accepted: 01/28/2009] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The MAL2 gene, encoding a four-transmembrane protein of the MAL family, is amplified and overexpressed in breast and other cancers, yet the significance of this is unknown. MAL-like proteins have trafficking functions, but their molecular roles are largely obscure, partly due to a lack of known binding partners. METHODS Yeast two-hybrid screening of a breast carcinoma cDNA expression library was performed using a full-length MAL2 bait, and subsequent deletion mapping experiments were performed. MAL2 interactions were confirmed by co-immunoprecipitation analyses and confocal microscopy was employed to compare protein sub-cellular distributions. Sucrose density gradient centrifugation of membranes extracted in cold Triton X-100 was employed to compare protein distributions between Triton X-100-soluble and -insoluble fractions. RESULTS The tumor-associated protein mucin 1 (MUC1) was identified as a potential MAL2 partner, with MAL2/MUC1 interactions being confirmed in myc-tagged MAL2-expressing MCF-10A cells using co-immunoprecipitation assays. Deletion mapping experiments demonstrated a requirement for the first MAL2 transmembrane domain for MUC1 binding, whereas the MAL2 N-terminal domain was required to bind D52-like proteins. Confocal microscopy identified cytoplasmic co-localisation of MUC1 and MAL2 in breast cell lines, and centrifugation of cell lysates to equilibrium in sucrose density gradients demonstrated that MAL2 and MUC1 proteins were co-distributed between Triton X-100-soluble and -insoluble fractions. However co-immunoprecipitation analyses detected MAL2/MUC1 interactions in Triton X-100-soluble fractions only. Myc-MAL2 expression in MCF-10A cells was associated with both increased MUC1 detection within Triton X-100-soluble and -insoluble fractions, and increased MUC1 detection at the cell surface. CONCLUSION These results identify MUC1 as a novel MAL2 partner, and suggest a role for MAL2 in regulating MUC1 expression and/or localisation.
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Affiliation(s)
- Susan Fanayan
- Molecular Oncology Laboratory, Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead, 2145 NSW, Australia
| | - Mona Shehata
- Molecular Oncology Laboratory, Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead, 2145 NSW, Australia
- The University of Sydney Discipline of Paediatrics and Child Health, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
| | - Annelies P Agterof
- Molecular Oncology Laboratory, Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead, 2145 NSW, Australia
- Department of Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands
| | - Michael A McGuckin
- Epithelial Cancer and Mucosal Biology Laboratory, Mater Medical Research Institute, Mater Health Services, South Brisbane 4101 Qld, Australia
| | - Miguel A Alonso
- Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid and Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049-Madrid, Spain
| | - Jennifer A Byrne
- Molecular Oncology Laboratory, Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead, 2145 NSW, Australia
- The University of Sydney Discipline of Paediatrics and Child Health, The Children's Hospital at Westmead, Locked Bag 4001, Westmead 2145, NSW, Australia
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Martín‐Belmonte F, Rodríguez‐Fraticelli AE. Chapter 3 Acquisition of Membrane Polarity in Epithelial Tube Formation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 274:129-82. [DOI: 10.1016/s1937-6448(08)02003-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Antón O, Batista A, Millán J, Andrés-Delgado L, Puertollano R, Correas I, Alonso MA. An essential role for the MAL protein in targeting Lck to the plasma membrane of human T lymphocytes. ACTA ACUST UNITED AC 2008; 205:3201-13. [PMID: 19064697 PMCID: PMC2605221 DOI: 10.1084/jem.20080552] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The MAL protein is an essential component of the specialized machinery for apical targeting in epithelial cells. The src family kinase Lck plays a pivotal role in T cell signaling. We show that MAL is required in T cells for efficient expression of Lck at the plasma membrane and activation of IL-2 transcription. To investigate the mechanism by which MAL regulates Lck targeting, we analyzed the dynamics of Lck and found that it travels to the plasma membrane in specific transport carriers containing MAL. Coimmunoprecipitation experiments indicated an association of MAL with Lck. Both carrier formation and partitioning of Lck into detergent-insoluble membranes were ablated in the absence of MAL. Polarization of T cell receptor for antigen (TCR) and microtubule-organizing center to immunological synapse (IS) were also defective. Although partial correction of the latter defects was possible by forced expression of Lck at the plasma membrane, their complete correction, formation of transport vesicles, partitioning of Lck, and restoration of signaling pathways, which are required for IL-2 transcription up-regulation, were achieved by exogenous expression of MAL. We concluded that MAL is required for recruitment of Lck to specialized membranes and formation of specific transport carriers for Lck targeting. This novel transport pathway is crucial for TCR-mediated signaling and IS assembly.
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Affiliation(s)
- Olga Antón
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
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Catino MA, Paladino S, Tivodar S, Pocard T, Zurzolo C. N- andO-Glycans Are Not Directly Involved in the Oligomerization and Apical Sorting of GPI Proteins. Traffic 2008; 9:2141-50. [DOI: 10.1111/j.1600-0854.2008.00826.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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MAL decreases the internalization of the aquaporin-2 water channel. Proc Natl Acad Sci U S A 2007; 104:16696-701. [PMID: 17940053 DOI: 10.1073/pnas.0708023104] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Body water homeostasis depends critically on the hormonally regulated trafficking of aquaporin-2 (AQP2) water channels in renal collecting duct epithelial cells. Several types of posttranslational modifications are clearly involved in controlling the distribution of AQP2 between intracellular vesicles and the apical plasma membrane. Little is known, however, about the protein interactions that govern the trafficking of AQP2 between these organelles. MAL is a detergent-resistant membrane-associated protein implicated in apical sorting events. We wondered, therefore, whether MAL plays a role in the regulated trafficking of AQP2 between intracellular vesicles and the apical surface. We find that AQP2 and MAL are coexpressed in epithelial cells of the kidney collecting duct. These two proteins interact, both in the native kidney and when expressed by transfection in cultured cells. The S256-phosphorylated form of AQP2 appears to interact more extensively with MAL than does the water channel protein not phosphorylated at this serine. We find that MAL is not involved in detergent-resistant membrane association or apical delivery of AQP2 in LLC-PK(1) renal epithelial cells. Instead, MAL increases the S256 phosphorylation and apical surface expression of AQP2. Furthermore, internalization experiments show that MAL induces surface expression of AQP2 by attenuating its internalization. Thus, the involvement of MAL in the cell surface retention of apical membrane proteins could play an important role in regulated absorption and secretion in transporting epithelia.
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Bosco A, McKenna KL, Devitt CJ, Firth MJ, Sly PD, Holt PG. Identification of Novel Th2-Associated Genes in T Memory Responses to Allergens. THE JOURNAL OF IMMUNOLOGY 2006; 176:4766-77. [PMID: 16585570 DOI: 10.4049/jimmunol.176.8.4766] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Atopic diseases are associated with hyperexpression of Th2 cytokines by allergen-specific T memory cells. However, clinical trials with recently developed Th2 inhibitors in atopics have proven disappointing, suggesting underlying complexities in atopy pathogenesis which are not satisfactorily explained via the classical Th1/Th2 paradigm. One likely possibility is that additional Th2-associated genes which are central to disease pathogenesis remain unidentified. The aim of the present study was to identify such novel Th2-associated genes in recall responses to the inhalant allergen house dust mite. In contrast to earlier human microarray studies in atopy which focused on mitogen-activated T cell lines and clones, we concentrated on PBMC-derived primary T cells stimulated under more physiological conditions of low dose allergen exposure. We screened initially for allergen-induced gene activation by microarray, and validated novel genes in independent panels of subjects by quantitative RT-PCR. Kinetic analysis of allergen responses in PBMC revealed an early wave of novel atopy-associated genes involved in signaling which were coexpressed with IL-4 and IL-4R, followed by a later wave of genes encoding the classical Th2 effector cytokines. We further demonstrate that these novel activation-associated Th2 genes up-regulate in response to another atopy-associated physiological stimulus bacterial superantigen, but remain quiescent in nonphysiological responses in primary T cells or cell lines driven by potent mitogens, which may account for their failure to be detected in earlier microarray studies.
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Affiliation(s)
- Anthony Bosco
- Telethon Institute for Child Health Research, and Centre for Child Health Research, Faculty of Medicine and Dentistry, University of Western Australia, Perth, Western Australia
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Tashima Y, Taguchi R, Murata C, Ashida H, Kinoshita T, Maeda Y. PGAP2 is essential for correct processing and stable expression of GPI-anchored proteins. Mol Biol Cell 2006; 17:1410-20. [PMID: 16407401 PMCID: PMC1382328 DOI: 10.1091/mbc.e05-11-1005] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Biosynthesis of glycosylphosphatidylinositol-anchored proteins (GPI-APs) in the ER has been extensively studied, whereas the molecular events during the transport of GPI-APs from the ER to the cell surface are poorly understood. Here, we established new mutant cell lines whose surface expressions of GPI-APs were greatly decreased despite normal biosynthesis of GPI-APs in the ER. We identified a gene responsible for this defect, designated PGAP2 (for Post-GPI-Attachment to Proteins 2), which encoded a Golgi/ER-resident membrane protein. The low surface expression of GPI-APs was due to their secretion into the culture medium. GPI-APs were modified/cleaved by two reaction steps in the mutant cells. First, the GPI anchor was converted to lyso-GPI before exiting the trans-Golgi network. Second, lyso-GPI-APs were cleaved by a phospholipase D after transport to the plasma membrane. Therefore, PGAP2 deficiency caused transport to the cell surface of lyso-GPI-APs that were sensitive to a phospholipase D. These results demonstrate that PGAP2 is involved in the processing of GPI-APs required for their stable expression at the cell surface.
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Affiliation(s)
- Yuko Tashima
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
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Potter BA, Hughey RP, Weisz OA. Role of N- and O-glycans in polarized biosynthetic sorting. Am J Physiol Cell Physiol 2006; 290:C1-C10. [PMID: 16338974 DOI: 10.1152/ajpcell.00333.2005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The maintenance of proper epithelial function requires efficient sorting of newly synthesized and recycling proteins to the apical and basolateral surfaces of differentiated cells. Whereas basolateral protein sorting signals are generally confined to their cytoplasmic regions, apical targeting signals have been identified that localize to luminal, transmembrane, and cytoplasmic aspects of proteins. In the past few years, both N- and O-linked glycans have been identified as apical sorting determinants. Glycan structures are extraordinarily diverse and have tremendous information potential. Moreover, because the oligosaccharides added to a given protein can change depending on cell type and developmental stage, the potential exists for altering sorting pathways by modulation of the expression pattern of enzymes involved in glycan synthesis. In this review, we discuss the evidence for glycan-mediated apical sorting along the biosynthetic pathway and present possible mechanisms by which these common and heterogeneous posttranslational modifications might function as specific sorting signals.
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Affiliation(s)
- Beth A Potter
- Laboratory of Epithelial Cell Biology, Renal-Electrolyte Division, Univ. of Pittsburgh School of Medicine, 978 Scaife Hall, 3550 Terrace St., Pittsburgh, PA 15261, USA
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Gielen E, Baron W, Vandeven M, Steels P, Hoekstra D, Ameloot M. Rafts in oligodendrocytes: Evidence and structure–function relationship. Glia 2006; 54:499-512. [PMID: 16927294 DOI: 10.1002/glia.20406] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The plasma membrane of eukaryotic cells exhibits lateral inhomogeneities, mainly containing cholesterol and sphingomyelin, which provide liquid-ordered microdomains (lipid "rafts") that segregate membrane components. Rafts are thought to modulate the biological functions of molecules that become associated with them, and as such, they appear to be involved in a variety of processes, including signal transduction, membrane sorting, cell adhesion and pathogen entry. Although still a matter of ongoing debate, evidence in favor of the presence of these microdomains is gradually accumulating but a consensus on issues like their size, lifetime, composition, and biological significance has yet to be reached. Here, we provide an overview of the evidence supporting the presence of rafts in oligodendrocytes, the myelin-producing cells of the central nervous system, and discuss their functional significance. The myelin membrane differs fundamentally from the plasma membrane, both in lipid and protein composition. Moreover, since myelin membranes are unusually enriched in glycosphingolipids, questions concerning the biogenesis and functional relevance of microdomains thus appear of special interest in oligodendrocytes. The current picture of rafts in oligodendrocytes is mainly based on detergent methods. The robustness of such data is discussed and alternative methods that may provide complementary data are indicated.
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Affiliation(s)
- Ellen Gielen
- Biomedical Research Institute, Hasselt University and transnationale Universiteit Limburg, Agoralaan, B-3590 Diepenbeek, Belgium
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Dannaeus K, Bessonova M, Jönsson JI. Characterization of the mouse myeloid-associated differentiation marker (MYADM) gene: promoter analysis and protein localization. Mol Biol Rep 2005; 32:149-57. [PMID: 16172915 DOI: 10.1007/s11033-005-0753-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2005] [Indexed: 11/26/2022]
Abstract
Hematopoietic differentiation is a complex process involving many genes inducing functional changes and characteristics of different cell lineages. To understand this process, it is important to identify genes involved in lineage commitment and maturation of hematopoietic progenitor cells. Recently we isolated the novel gene MYADM which is strongly up-regulated as multipotent progenitor cells differentiate towards myeloid cells. Because it is not expressed in lymphocytes, understanding the transcriptional control of MYADM could further explain differences in gene expression between myeloid and lymphoid cells. To identify regulatory elements controlling its restricted expression, we have analyzed the 5'-flanking region of the MYADM gene. The proximal promoter was found to lack both TATA and CCAAT boxes, but contained several potential binding sites for both ubiquitous and myeloid-specific transcription factors. Maximal promoter activity was contained within 800 bp from the tentative transcription initiation site, which was reduced as portions of the 5'-end were deleted, and completely abolished when the transcription initiation site was deleted. This promoter sequence had higher activity in myeloid cells compared to B cells, and activity was enhanced during myeloid differentiation, suggesting that we have identified the MYADM core promoter. Computer predictions had suggested MYADM to encode a protein with multiple transmembrane domains. By immunofluorescence and confocal microscopy we demonstrate that the protein is localized to the nuclear envelope and to intracytoplasmic membranes, indicating that MYADM constitutes an integral membrane protein.
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Affiliation(s)
- Karin Dannaeus
- Division of Molecular Medicine, Department of Laboratory Medicine, Lund University, University Hospital MAS, SE-205 02 Malmö, Sweden
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Gould RM, Morrison HG, Gilland E, Campbell RK. Myelin tetraspan family proteins but no non-tetraspan family proteins are present in the ascidian (Ciona intestinalis) genome. THE BIOLOGICAL BULLETIN 2005; 209:49-66. [PMID: 16110093 DOI: 10.2307/3593141] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Several of the proteins used to form and maintain myelin sheaths in the central nervous system (CNS) and the peripheral nervous system (PNS) are shared among different vertebrate classes. These proteins include one-to-several alternatively spliced myelin basic protein (MBP) isoforms in all sheaths, proteolipid protein (PLP) and DM20 (except in amphibians) in tetrapod CNS sheaths, and one or two protein zero (P0) isoforms in fish CNS and in all vertebrate PNS sheaths. Several other proteins, including 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP), myelin and lymphocyte protein (MAL), plasmolipin, and peripheral myelin protein 22 (PMP22; prominent in PNS myelin), are localized to myelin and myelin-associated membranes, though class distributions are less well studied. Databases with known and identified sequences of these proteins from cartilaginous and teleost fishes, amphibians, reptiles, birds, and mammals were prepared and used to search for potential homologs in the basal vertebrate, Ciona intestinalis. Homologs of lipophilin proteins, MAL/plasmolipin, and PMP22 were identified in the Ciona genome. In contrast, no MBP, P0, or CNP homologs were found. These studies provide a framework for understanding how myelin proteins were recruited during evolution and how structural adaptations enabled them to play key roles in myelination.
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Affiliation(s)
- Robert M Gould
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, Illinois 60612, USA.
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Nagata N, Yoshida NL, Sugita Y, Arai T, Seki YI, Kubo M, Tsujimoto G, Akasawa A, Saito H, Oshida T. Mite-antigen Stimulates MAL Expression in Peripheral Blood T Cells of Mite-sensitive Subjects. Allergol Int 2005. [DOI: 10.2332/allergolint.54.273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Campo C, Mason A, Maouyo D, Olsen O, Yoo D, Welling PA. Molecular mechanisms of membrane polarity in renal epithelial cells. Rev Physiol Biochem Pharmacol 2004; 153:47-99. [PMID: 15674648 DOI: 10.1007/s10254-004-0037-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Exciting discoveries in the last decade have cast light onto the fundamental mechanisms that underlie polarized trafficking in epithelial cells. It is now clear that epithelial cell membrane asymmetry is achieved by a combination of intracellular sorting operations, vectorial delivery mechanisms and plasmalemma-specific fusion and retention processes. Several well-defined signals that specify polarized segregation, sorting, or retention processes have, now, been described in a number of proteins. The intracellular machineries that decode and act on these signals are beginning to be described. In addition, the nature of the molecules that associate with intracellular trafficking vesicles to coordinate polarized delivery, tethering, docking, and fusion are also becoming understood. Combined with direct visualization of polarized sorting processes with new technologies in live-cell fluorescent microscopy, new and surprising insights into these once-elusive trafficking processes are emerging. Here we provide a review of these recent advances within an historically relevant context.
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Affiliation(s)
- C Campo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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