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Zhang L, Wen X, Chen X, Zhou Y, Wang K, Zhu Y. GhCASPL1 regulates secondary cell wall thickening in cotton fibers by stabilizing the cellulose synthase complex on the plasma membrane. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2024; 66:2632-2647. [PMID: 39315818 PMCID: PMC11622535 DOI: 10.1111/jipb.13777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 08/26/2024] [Accepted: 08/30/2024] [Indexed: 09/25/2024]
Abstract
Cotton (Gossypium hirsutum) fibers are elongated single cells that rapidly accumulate cellulose during secondary cell wall (SCW) thickening, which requires cellulose synthase complex (CSC) activity. Here, we describe the CSC-interacting factor CASPARIAN STRIP MEMBRANE DOMAIN-LIKE1 (GhCASPL1), which contributes to SCW thickening by influencing CSC stability on the plasma membrane. GhCASPL1 is preferentially expressed in fiber cells during SCW biosynthesis and encodes a MARVEL domain protein. The ghcaspl1 ghcaspl2 mutant exhibited reduced plant height and produced mature fibers with fewer natural twists, lower tensile strength, and a thinner SCW compared to the wild type. Similarly, the Arabidopsis (Arabidopsis thaliana) caspl1 caspl2 double mutant showed a lower cellulose content and thinner cell walls in the stem vasculature than the wild type but normal plant morphology. Introducing the cotton gene GhCASPL1 successfully restored the reduced cellulose content of the Arabidopsis caspl1 caspl2 mutant. Detergent treatments, ultracentrifugation assays, and enzymatic assays showed that the CSC in the ghcaspl1 ghcaspl2 double mutant showed reduced membrane binding and decreased enzyme activity compared to the wild type. GhCASPL1 binds strongly to phosphatidic acid (PA), which is present in much higher amounts in thickening fiber cells compared to ovules and leaves. Mutating the PA-binding site in GhCASPL1 resulted in the loss of its colocalization with GhCesA8, and it failed to localize to the plasma membrane. PA may alter membrane structure to facilitate protein-protein interactions, suggesting that GhCASPL1 and PA collaboratively stabilize the CSC. Our findings shed light on CASPL functions and the molecular machinery behind SCW biosynthesis in cotton fibers.
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Affiliation(s)
- Li Zhang
- Institute for Advanced StudiesWuhan UniversityWuhan430072China
| | - Xingpeng Wen
- Institute for Advanced StudiesWuhan UniversityWuhan430072China
- State Key Laboratory of Hybrid Rice, Hubei Hongshan Laboratory, College of Life SciencesWuhan UniversityWuhan430072China
- TaiKang Center for Life and Medical SciencesWuhan UniversityWuhan430072China
| | - Xin Chen
- State Key Laboratory of Protein and Plant Gene Research, College of Life SciencesPeking UniversityBeijing100871China
| | - Yifan Zhou
- State Key Laboratory of Hybrid Rice, Hubei Hongshan Laboratory, College of Life SciencesWuhan UniversityWuhan430072China
| | - Kun Wang
- State Key Laboratory of Hybrid Rice, Hubei Hongshan Laboratory, College of Life SciencesWuhan UniversityWuhan430072China
| | - Yuxian Zhu
- Institute for Advanced StudiesWuhan UniversityWuhan430072China
- State Key Laboratory of Hybrid Rice, Hubei Hongshan Laboratory, College of Life SciencesWuhan UniversityWuhan430072China
- TaiKang Center for Life and Medical SciencesWuhan UniversityWuhan430072China
- State Key Laboratory of Protein and Plant Gene Research, College of Life SciencesPeking UniversityBeijing100871China
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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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Mei M, Liu M, Mei Y, Zhao J, Li Y. Sphingolipid metabolism in brain insulin resistance and neurological diseases. Front Endocrinol (Lausanne) 2023; 14:1243132. [PMID: 37867511 PMCID: PMC10587683 DOI: 10.3389/fendo.2023.1243132] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 09/22/2023] [Indexed: 10/24/2023] Open
Abstract
Sphingolipids, as members of the large lipid family, are important components of plasma membrane. Sphingolipids participate in biological signal transduction to regulate various important physiological processes such as cell growth, apoptosis, senescence, and differentiation. Numerous studies have demonstrated that sphingolipids are strongly associated with glucose metabolism and insulin resistance. Insulin resistance, including peripheral insulin resistance and brain insulin resistance, is closely related to the occurrence and development of many metabolic diseases. In addition to metabolic diseases, like type 2 diabetes, brain insulin resistance is also involved in the progression of neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. However, the specific mechanism of sphingolipids in brain insulin resistance has not been systematically summarized. This article reviews the involvement of sphingolipids in brain insulin resistance, highlighting the role and molecular biological mechanism of sphingolipid metabolism in cognitive dysfunctions and neuropathological abnormalities of the brain.
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Affiliation(s)
- Meng Mei
- Department of Pharmacy, Wuhan Children’s Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Maochang Liu
- Department of Pharmacy, Wuhan Children’s Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yan Mei
- Department of Pharmacy, Wuhan Children’s Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Zhao
- Administrative Office, Beijing University of Chinese Medicine, Beijing, China
| | - Yang Li
- Department of Pharmacy, Wuhan Children’s Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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4
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Saldaña-Villa AK, Lara-Lemus R. The Structural Proteins of Membrane Rafts, Caveolins and Flotillins, in Lung Cancer: More Than Just Scaffold Elements. Int J Med Sci 2023; 20:1662-1670. [PMID: 37928877 PMCID: PMC10620868 DOI: 10.7150/ijms.87836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 08/25/2023] [Indexed: 11/07/2023] Open
Abstract
Lung cancer is one of the most frequently diagnosed cancers worldwide. Due to its late diagnosis, it remains the leading cause of cancer-related deaths. Despite it is mostly associated to tobacco smoking, recent data suggested that genetic factors are of the highest importance. In this context, different processes meaningful for the development and progression of lung cancer such endocytosis, protein secretion and signal transduction, are controlled by membrane rafts. These highly ordered membrane domains contain proteins such as caveolins and flotillins, which were traditionally considered scaffold proteins but have currently been given a preponderant role in lung cancer. Here, we summarize current knowledge regarding the involvement of caveolins and flotillins in lung cancer from a molecular point of view.
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Affiliation(s)
| | - Roberto Lara-Lemus
- Department of Molecular Biomedicine and Translational Research, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”. Mexico City, Mexico
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5
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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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6
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Labat-de-Hoz L, Rubio-Ramos A, Correas I, Alonso MA. The MAL Family of Proteins: Normal Function, Expression in Cancer, and Potential Use as Cancer Biomarkers. Cancers (Basel) 2023; 15:2801. [PMID: 37345137 DOI: 10.3390/cancers15102801] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/06/2023] [Accepted: 05/15/2023] [Indexed: 06/23/2023] Open
Abstract
The MAL family of integral membrane proteins consists of MAL, MAL2, MALL, PLLP, CMTM8, MYADM, and MYADML2. The best characterized members are elements of the machinery that controls specialized pathways of membrane traffic and cell signaling. This review aims to help answer the following questions about the MAL-family genes: (i) is their expression regulated in cancer and, if so, how? (ii) What role do they play in cancer? (iii) Might they have biomedical applications? Analysis of large-scale gene expression datasets indicated altered levels of MAL-family transcripts in specific cancer types. A comprehensive literature search provides evidence of MAL-family gene dysregulation and protein function repurposing in cancer. For MAL, and probably for other genes of the family, dysregulation is primarily a consequence of gene methylation, although copy number alterations also contribute to varying degrees. The scrutiny of the two sources of information, datasets and published studies, reveals potential prognostic applications of MAL-family members as cancer biomarkers-for instance, MAL2 in breast cancer, MAL2 and MALL in pancreatic cancer, and MAL and MYADM in lung cancer-and other biomedical uses. The availability of validated antibodies to some MAL-family proteins sanctions their use as cancer biomarkers in routine clinical practice.
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Affiliation(s)
- Leticia Labat-de-Hoz
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Armando Rubio-Ramos
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Isabel Correas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- 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, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Rubio-Ramos A, Bernabé-Rubio M, Labat-de-Hoz L, Casares-Arias J, Kremer L, Correas I, Alonso MA. MALL, a membrane-tetra-spanning proteolipid overexpressed in cancer, is present in membraneless nuclear biomolecular condensates. Cell Mol Life Sci 2022; 79:236. [PMID: 35399121 PMCID: PMC8995265 DOI: 10.1007/s00018-022-04270-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/08/2022] [Accepted: 03/22/2022] [Indexed: 12/04/2022]
Abstract
Proteolipids are proteins with unusual lipid-like properties. It has long been established that PLP and plasmolipin, which are two unrelated membrane-tetra-spanning myelin proteolipids, can be converted in vitro into a water-soluble form with a distinct conformation, raising the question of whether these, or other similar proteolipids, can adopt two different conformations in the cell to adapt their structure to distinct environments. Here, we show that MALL, another proteolipid with a membrane-tetra-spanning structure, distributes in membranes outside the nucleus and, within the nucleus, in membrane-less, liquid-like PML body biomolecular condensates. Detection of MALL in one or other environment was strictly dependent on the method of cell fixation used, suggesting that MALL adopts different conformations depending on its physical environment —lipidic or aqueous— in the cell. The acquisition of the condensate-compatible conformation requires PML expression. Excess MALL perturbed the distribution of the inner nuclear membrane proteins emerin and LAP2β, and that of the DNA-binding protein BAF, leading to the formation of aberrant nuclei. This effect, which is consistent with studies identifying overexpressed MALL as an unfavorable prognostic factor in cancer, could contribute to cell malignancy. Our study establishes a link between proteolipids, membranes and biomolecular condensates, with potential biomedical implications.
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Affiliation(s)
- Armando Rubio-Ramos
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Miguel Bernabé-Rubio
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Leticia Labat-de-Hoz
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Javier Casares-Arias
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Leonor Kremer
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Madrid, Spain
| | - Isabel Correas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049, Madrid, Spain
- 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, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
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Mazzucco M, Mannheim W, Shetty SV, Linden JR. CNS endothelial derived extracellular vesicles are biomarkers of active disease in multiple sclerosis. Fluids Barriers CNS 2022; 19:13. [PMID: 35135557 PMCID: PMC8822708 DOI: 10.1186/s12987-021-00299-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 12/20/2021] [Indexed: 12/13/2022] Open
Abstract
Background Multiple sclerosis (MS) is a complex, heterogenous disease characterized by inflammation, demyelination, and blood–brain barrier (BBB) permeability. Currently, active disease is determined by physician confirmed relapse or detection of contrast enhancing lesions via MRI indicative of BBB permeability. However, clinical confirmation of active disease can be cumbersome. As such, disease monitoring in MS could benefit from identification of an easily accessible biomarker of active disease. We believe extracellular vesicles (EV) isolated from plasma are excellent candidates to fulfill this need. Because of the critical role BBB permeability plays in MS pathogenesis and identification of active disease, we sought to identify EV originating from central nervous system (CNS) endothelial as biomarkers of active MS. Because endothelial cells secrete more EV when stimulated or injured, we hypothesized that circulating concentrations of CNS endothelial derived EV will be increased in MS patients with active disease. Methods To test this, we developed a novel method to identify EV originating from CNS endothelial cells isolated from patient plasma using flow cytometry. Endothelial derived EV were identified by the absence of lymphocyte or platelet markers CD3 and CD41, respectively, and positive expression of pan-endothelial markers CD31, CD105, or CD144. To determine if endothelial derived EV originated from CNS endothelial cells, EV expressing CD31, CD105, or CD144 were evaluated for expression of the myelin and lymphocyte protein MAL, a protein specifically expressed by CNS endothelial cells compared to endothelial cells of peripheral organs. Results Quality control experiments indicate that EV detected using our flow cytometry method are 0.2 to 1 micron in size. Flow cytometry analysis of EV isolated from 20 healthy controls, 16 relapsing–remitting MS (RRMS) patients with active disease not receiving disease modifying therapy, 14 RRMS patients with stable disease not receiving disease modifying therapy, 17 relapsing-RRMS patients with stable disease receiving natalizumab, and 14 RRMS patients with stable disease receiving ocrelizumab revealed a significant increase in the plasma concentration of CNS endothelial derived EV in patients with active disease compared to all other groups (p = 0.001). Conclusions: For the first time, we have identified a method to identify CNS endothelial derived EV in circulation from human blood samples. Results from our pilot study indicate that increased levels of CNS endothelial derived EV may be a biomarker of BBB permeability and active disease in MS. Supplementary Information The online version contains supplementary material available at 10.1186/s12987-021-00299-4.
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Affiliation(s)
- Michael Mazzucco
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, 1300 York Ave, New York, NY, 10065, USA
| | - William Mannheim
- Department of Neurology, Weill Cornell Medical College, New York, NY, USA
| | - Samantha V Shetty
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, 1300 York Ave, New York, NY, 10065, USA
| | - Jennifer R Linden
- The Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, 1300 York Ave, New York, NY, 10065, USA.
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Plasmolipin regulates basolateral-to-apical transcytosis of ICAM-1 and leukocyte adhesion in polarized hepatic epithelial cells. Cell Mol Life Sci 2022; 79:61. [PMID: 34999972 PMCID: PMC8743267 DOI: 10.1007/s00018-021-04095-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 11/30/2022]
Abstract
Apical localization of Intercellular Adhesion Receptor (ICAM)-1 regulates the adhesion and guidance of leukocytes across polarized epithelial barriers. Here, we investigate the molecular mechanisms that determine ICAM-1 localization into apical membrane domains of polarized hepatic epithelial cells, and their effect on lymphocyte-hepatic epithelial cell interaction. We had previously shown that segregation of ICAM-1 into apical membrane domains, which form bile canaliculi and bile ducts in hepatic epithelial cells, requires basolateral-to-apical transcytosis. Searching for protein machinery potentially involved in ICAM-1 polarization we found that the SNARE-associated protein plasmolipin (PLLP) is expressed in the subapical compartment of hepatic epithelial cells in vitro and in vivo. BioID analysis of ICAM-1 revealed proximal interaction between this adhesion receptor and PLLP. ICAM-1 colocalized and interacted with PLLP during the transcytosis of the receptor. PLLP gene editing and silencing increased the basolateral localization and reduced the apical confinement of ICAM-1 without affecting apicobasal polarity of hepatic epithelial cells, indicating that ICAM-1 transcytosis is specifically impaired in the absence of PLLP. Importantly, PLLP depletion was sufficient to increase T-cell adhesion to hepatic epithelial cells. Such an increase depended on the epithelial cell polarity and ICAM-1 expression, showing that the epithelial transcytotic machinery regulates the adhesion of lymphocytes to polarized epithelial cells. Our findings strongly suggest that the polarized intracellular transport of adhesion receptors constitutes a new regulatory layer of the epithelial inflammatory response.
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Shulgin AA, Lebedev TD, Prassolov VS, Spirin PV. Plasmolipin and Its Role in Cell Processes. Mol Biol 2021; 55:773-785. [PMID: 34955555 PMCID: PMC8682038 DOI: 10.1134/s0026893321050113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/26/2021] [Accepted: 04/05/2021] [Indexed: 12/04/2022]
Abstract
The mechanisms involved in the origin and development of malignant and neurodegenerative diseases are an important area of modern biomedicine. A crucial task is to identify new molecular markers that are associated with rearrangements of intracellular signaling and can be used for prognosis and the development of effective treatment approaches. The proteolipid plasmolipin (PLLP) is a possible marker. PLLP is a main component of the myelin sheath and plays an important role in the development and normal function of the nervous system. PLLP is involved in intracellular transport, lipid raft formation, and Notch signaling. PLLP is presumably involved in various disorders, such as cancer, schizophrenia, Alzheimer's disease, and type 2 diabetes mellitus. PLLP and its homologs were identified as possible virus entry receptors. The review summarizes the data on the PLLP structure, normal functions, and role in diseases.
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Affiliation(s)
- A. A. Shulgin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
- Moscow Institute of Physics and Technology (State University), 141701 Dolgoprudny, Moscow oblast Russia
| | - T. D. Lebedev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - V. S. Prassolov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - P. V. Spirin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
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Jeong J, Shin JH, Li W, Hong JY, Lim J, Hwang JY, Chung JJ, Yan Q, Liu Y, Choi J, Wysolmerski J. MAL2 mediates the formation of stable HER2 signaling complexes within lipid raft-rich membrane protrusions in breast cancer cells. Cell Rep 2021; 37:110160. [PMID: 34965434 PMCID: PMC8762588 DOI: 10.1016/j.celrep.2021.110160] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 08/16/2021] [Accepted: 12/02/2021] [Indexed: 12/18/2022] Open
Abstract
The lipid raft-resident protein, MAL2, has been implicated as contributing to the pathogenesis of several malignancies, including breast cancer, but the underlying mechanism for its effects on tumorigenesis is unknown. Here, we show that MAL2-mediated lipid raft formation leads to HER2 plasma membrane retention and enhanced HER2 signaling in breast cancer cells. We demonstrate physical interactions between HER2 and MAL2 in lipid rafts using proximity ligation assays. Super-resolution structured illumination microscopy imaging displays the structural organization of the HER2/Ezrin/NHERF1/PMCA2 protein complex. Formation of this protein complex maintains low intracellular calcium concentrations in the vicinity of the plasma membrane. HER2/MAL2 protein interactions in lipid rafts are enhanced in trastuzumab-resistant breast cancer cells. Our findings suggest that MAL2 is crucial for lipid raft formation, HER2 signaling, and HER2 membrane stability in breast cancer cells, suggesting MAL2 as a potential therapeutic target. Jeong et al. show that the formation of MAL2-mediated lipid raft-rich membrane protrusions is crucial for HER2 signaling in breast cancer cells. MAL2 is required for the formation of HER2/Ezrin/NHERF1/PMCA2 protein complexes. Formation of these protein complexes leads to a low calcium environment in the plasma membrane
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12
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Ligocki AJ, Fury W, Gutierrez C, Adler C, Yang T, Ni M, Bai Y, Wei Y, Lehmann GL, Romano C. Molecular characteristics and spatial distribution of adult human corneal cell subtypes. Sci Rep 2021; 11:16323. [PMID: 34381080 PMCID: PMC8357950 DOI: 10.1038/s41598-021-94933-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 07/19/2021] [Indexed: 12/13/2022] Open
Abstract
Bulk RNA sequencing of a tissue captures the gene expression profile from all cell types combined. Single-cell RNA sequencing identifies discrete cell-signatures based on transcriptomic identities. Six adult human corneas were processed for single-cell RNAseq and 16 cell clusters were bioinformatically identified. Based on their transcriptomic signatures and RNAscope results using representative cluster marker genes on human cornea cross-sections, these clusters were confirmed to be stromal keratocytes, endothelium, several subtypes of corneal epithelium, conjunctival epithelium, and supportive cells in the limbal stem cell niche. The complexity of the epithelial cell layer was captured by eight distinct corneal clusters and three conjunctival clusters. These were further characterized by enriched biological pathways and molecular characteristics which revealed novel groupings related to development, function, and location within the epithelial layer. Moreover, epithelial subtypes were found to reflect their initial generation in the limbal region, differentiation, and migration through to mature epithelial cells. The single-cell map of the human cornea deepens the knowledge of the cellular subsets of the cornea on a whole genome transcriptional level. This information can be applied to better understand normal corneal biology, serve as a reference to understand corneal disease pathology, and provide potential insights into therapeutic approaches.
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Affiliation(s)
- Ann J Ligocki
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA
| | - Wen Fury
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA
| | | | | | - Tao Yang
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA
| | - Min Ni
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA
| | - Yu Bai
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA
| | - Yi Wei
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA
| | | | - Carmelo Romano
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, 10591, USA.
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13
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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: 15] [Impact Index Per Article: 3.8] [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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14
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Labat-de-Hoz L, Rubio-Ramos A, Casares-Arias J, Bernabé-Rubio M, Correas I, Alonso MA. A Model for Primary Cilium Biogenesis by Polarized Epithelial Cells: Role of the Midbody Remnant and Associated Specialized Membranes. Front Cell Dev Biol 2021; 8:622918. [PMID: 33585461 PMCID: PMC7873843 DOI: 10.3389/fcell.2020.622918] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022] Open
Abstract
Primary cilia are solitary, microtubule-based protrusions surrounded by a ciliary membrane equipped with selected receptors that orchestrate important signaling pathways that control cell growth, differentiation, development and homeostasis. Depending on the cell type, primary cilium assembly takes place intracellularly or at the cell surface. The intracellular route has been the focus of research on primary cilium biogenesis, whereas the route that occurs at the cell surface, which we call the "alternative" route, has been much less thoroughly characterized. In this review, based on recent experimental evidence, we present a model of primary ciliogenesis by the alternative route in which the remnant of the midbody generated upon cytokinesis acquires compact membranes, that are involved in compartmentalization of biological membranes. The midbody remnant delivers part of those membranes to the centrosome in order to assemble the ciliary membrane, thereby licensing primary cilium formation. The midbody remnant's involvement in primary cilium formation, the regulation of its inheritance by the ESCRT machinery, and the assembly of the ciliary membrane from the membranes originally associated with the remnant are discussed in the context of the literature concerning the ciliary membrane, the emerging roles of the midbody remnant, the regulation of cytokinesis, and the role of membrane compartmentalization. We also present a model of cilium emergence during evolution, and summarize the directions for future research.
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Affiliation(s)
- Leticia Labat-de-Hoz
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Armando Rubio-Ramos
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Javier Casares-Arias
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel Bernabé-Rubio
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Isabel Correas
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
- Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel A. Alonso
- Centro de Biología Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
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Herpes Simplex Virus 1 Spread in Oligodendrocytic Cells Is Highly Dependent on MAL Proteolipid. J Virol 2020; 94:JVI.01739-19. [PMID: 31748392 PMCID: PMC6997773 DOI: 10.1128/jvi.01739-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 11/12/2019] [Indexed: 12/31/2022] Open
Abstract
Herpes simplex virus 1 (HSV-1) is a neurotropic pathogen that can infect many types of cells and establish latent infections in neurons. HSV-1 may spread from infected to uninfected cells by two main routes: by cell-free virus or by cell-to-cell spread. In the first case, virions exit into the extracellular space and then infect another cell from the outside. In the second case, viral transmission occurs through cell-to-cell contacts via a mechanism that is still poorly understood. A third mode of spread, using extracellular vesicles, also exists. In this study, we demonstrate the important role for a myelin protein, myelin and lymphocyte protein (MAL), in the process of cell-to-cell viral spread in oligodendrocytes. We show that MAL is involved in trafficking of virions along cell processes and that MAL depletion produces a significant alteration in the viral cycle, which reduces cell-to cell spread of HSV-1. Myelin and lymphocyte protein (MAL) is a tetraspan integral membrane protein that resides in detergent-insoluble membrane fractions enriched in condensed membranes. MAL is expressed in oligodendrocytes, in Schwann cells, where it is essential for the stability of myelin, and at the apical membrane of epithelial cells, where it has a critical role in transport. In T lymphocytes, MAL is found at the immunological synapse and plays a crucial role in exosome secretion. However, no involvement of MAL in viral infections has been reported so far. Here, we show that herpes simplex virus 1 (HSV-1) virions travel in association with MAL-positive structures to reach the end of cellular processes, which contact uninfected oligodendrocytes. Importantly, the depletion of MAL led to a significant decrease in infection, with a drastic reduction in the number of lytic plaques in MAL-silenced cells. These results suggest a significant role for MAL in viral spread at cell contacts. The participation of MAL in the cell-to-cell spread of HSV-1 may shed light on the involvement of proteolipids in this process. IMPORTANCE Herpes simplex virus 1 (HSV-1) is a neurotropic pathogen that can infect many types of cells and establish latent infections in neurons. HSV-1 may spread from infected to uninfected cells by two main routes: by cell-free virus or by cell-to-cell spread. In the first case, virions exit into the extracellular space and then infect another cell from the outside. In the second case, viral transmission occurs through cell-to-cell contacts via a mechanism that is still poorly understood. A third mode of spread, using extracellular vesicles, also exists. In this study, we demonstrate the important role for a myelin protein, myelin and lymphocyte protein (MAL), in the process of cell-to-cell viral spread in oligodendrocytes. We show that MAL is involved in trafficking of virions along cell processes and that MAL depletion produces a significant alteration in the viral cycle, which reduces cell-to cell spread of HSV-1.
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16
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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: 3.2] [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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17
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Lara-Lemus R. On The Role of Myelin and Lymphocyte Protein (MAL) In Cancer: A Puzzle With Two Faces. J Cancer 2019; 10:2312-2318. [PMID: 31258734 PMCID: PMC6584422 DOI: 10.7150/jca.30376] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 02/07/2019] [Indexed: 12/25/2022] Open
Abstract
Myelin and lymphocyte protein (MAL) is an integral membrane protein constituent of lipid rafts, and it is implicated in apical transport of proteins in polarized epithelial cells. However, beyond the involvement of MAL in apical sorting and as its function as a raft stabilizer, it is still not totally clear how MAL participates in cell proliferating processes. More controversial and interesting is the fact that MAL has been implicated in carcinogenesis in two opposite ways. First, this protein is overexpressed in ovarian cancer and some kinds of lymphomas where it seems to favor cancer progression. Conversely, it has been reported that downregulation of the MAL gene by promoter hypermethylation is a hallmark of several adenocarcinomas. So far, there is not enough experimental evidence to help us understand this phenomenon, and no MAL mutations or MAL isoforms have been associated with these opposite functions. This review provides an updated summary of the structure and functions of MAL, and we will discuss the possible mechanisms underlying its roles as a tumor suppressor and a tumor progression factor.
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Affiliation(s)
- Roberto Lara-Lemus
- Department of Research in Biochemistry, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”. Mexico City, 14080. Mexico
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18
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Post-Wildfire Landslide Hazard Assessment: The Case of The 2017 Montagna Del Morrone Fire (Central Apennines, Italy). GEOSCIENCES 2019. [DOI: 10.3390/geosciences9040175] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This work focused on a post-wildfire landslide hazard assessment, applied to the 2017 Montagna del Morrone fire. This wildfire increased the possibility of landslides triggering, as confirmed by the occurrence of a debris flow, triggered by an intense, short duration rainfall event in August 2018. The study area was investigated through a detailed analysis incorporating morphometric analysis of the topography and hydrography and geomorphological field mapping, followed by the landslide hazard assessment. In detail, the analysis was performed following a heuristic or expert-based approach, integrated using GIS technology. This approach led to the identification of five instability factors. These factors were analyzed for the construction of thematic maps. Hence, each factor was evaluated by assigning appropriate expert-based ranks and weights and combined in a geomorphology-based matrix, that defines four landslide hazard classes (low, moderate, high, and very high). Moreover, the morphometric analysis allowed us to recognize basins prone to debris flows, which, in relevant literature, are those that show a Melton ratio of >0.6 and a watershed length of <2.7 km. Finally, all the collected data were mapped through a cartographic and weighted overlay process in order to realize a new zonation of landslide hazard for the study area, which can be used in civil protection warning systems for the occurrence of landslides in mountainous forested environments.
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19
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Jiang S, Wang X, Song D, Liu X, Gu Y, Xu Z, Wang X, Zhang X, Ye Q, Tong Z, Yan B, Yu J, Chen Y, Sun M, Wang Y, Gao S. Cholesterol Induces Epithelial-to-Mesenchymal Transition of Prostate Cancer Cells by Suppressing Degradation of EGFR through APMAP. Cancer Res 2019; 79:3063-3075. [PMID: 30987997 DOI: 10.1158/0008-5472.can-18-3295] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 03/04/2019] [Accepted: 04/11/2019] [Indexed: 11/16/2022]
Abstract
Cholesterol increases the risk of aggressive prostate cancer and has emerged as a potential therapeutic target for prostate cancer. The functional roles of cholesterol in prostate cancer metastasis are not fully understood. Here, we found that cholesterol induces the epithelial-to-mesenchymal transition (EMT) through extracellular-regulated protein kinases 1/2 pathway activation, which is mediated by EGFR and adipocyte plasma membrane-associated protein (APMAP) accumulation in cholesterol-induced lipid rafts. Mechanistically, APMAP increases the interaction with EGFR substrate 15-related protein (EPS15R) to inhibit the endocytosis of EGFR by cholesterol, thus promoting cholesterol-induced EMT. Both the mRNA and protein levels of APMAP are upregulated in clinical prostate cancer samples. Together, these findings shed light onto an APMAP/EPS15R/EGFR axis that mediates cholesterol-induced EMT of prostate cancer cells. SIGNIFICANCE: This study delineates the molecular mechanisms by which cholesterol increases prostate cancer progression and demonstrates that the binding of cholesterol-induced APMAP with EPS15R inhibits EGFR internalization and activates ERK1/2 to promote EMT. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/79/12/3063/F1.large.jpg.
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Affiliation(s)
- Siyuan Jiang
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Xuetong Wang
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Dalong Song
- Department of Urology, GuiZhou provincial people's hospital, Guiyang, China
| | - XiaoJun Liu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Yinmin Gu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Zhiyuan Xu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Xiaodong Wang
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Xiaolu Zhang
- Department of Medicine, The University of Toledo Health Sciences Campus, Toledo, Ohio
| | - Qinong Ye
- Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Collaborative Innovation Center for Cancer Medicine, Beijing, China
| | - Zhou Tong
- Shanxi Academy of Advanced Research and Innovation, Taiyuan, China
| | - BingXue Yan
- Shanxi Academy of Advanced Research and Innovation, Taiyuan, China
| | - Jie Yu
- Department of Pathology, the People's Hospital of Suzhou National Hi-Tech District, Suzhou, China
| | - Yunzhao Chen
- Department of Pathology, the People's Hospital of Suzhou National Hi-Tech District, Suzhou, China
| | - Minxuan Sun
- Jiangsu Key Lab of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Yang Wang
- Shanxi Academy of Advanced Research and Innovation, Taiyuan, China
| | - Shan Gao
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China. .,Shanxi Academy of Advanced Research and Innovation, Taiyuan, China.,Medical College, Guizhou University, Guiyang, China
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20
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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: 1.9] [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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21
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Trafficking and regulation of the NKCC2 cotransporter in the thick ascending limb. Curr Opin Nephrol Hypertens 2018; 26:392-397. [PMID: 28614115 DOI: 10.1097/mnh.0000000000000351] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE OF REVIEW The kidney Na-K-2Cl cotransporter (NKCC2) is essential for urinary concentration and renal electrolyte handling. Loss of function mutations in the NKCC2 gene cause urinary salt and potassium wasting, whereas excessive NKCC2 function has been linked to high blood pressure. Loop diuretics, targeting the transporter, are instrumental for relieving edema or hypertension. This review focuses on intrinsic mechanisms regulating NKCC2 activity at the posttranslational level, namely its trafficking and phosphorylation. RECENT FINDINGS Protein networks mediating cellular turnover of NKCC2 have recently received major attention. Several key components of its apical trafficking were identified, including respective chaperones, SNARE protein family members and raft-associated proteins. NKCC2 internalization has been characterized qualitatively and quantitatively. Kinase and phosphatase pathways regulating NKCC2 activity have been clarified and links between NKCC2 phosphorylation and trafficking proposed. Constitutive and inducible NKCC2 trafficking and phosphorylation mechanisms have been specified with focus on endocrine control of thick ascending limb (TAL) function by vasopressin. SUMMARY Proper NKCC2 trafficking and phosphorylation are critical to the TAL function in the physiological context of urinary concentration and extracellular volume regulation. Clarification of the underlying mechanisms and respective protein networks may open new therapeutic perspectives for better management of renal electrolyte disorders and blood pressure control.
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Garcia-Castillo MD, Chinnapen DJF, Lencer WI. Membrane Transport across Polarized Epithelia. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a027912. [PMID: 28213463 DOI: 10.1101/cshperspect.a027912] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Polarized epithelial cells line diverse surfaces throughout the body forming selective barriers between the external environment and the internal milieu. To cross these epithelial barriers, large solutes and other cargoes must undergo transcytosis, an endocytic pathway unique to polarized cell types, and significant for the development of cell polarity, uptake of viral and bacterial pathogens, transepithelial signaling, and immunoglobulin transport. Here, we review recent advances in our knowledge of the transcytotic pathway for proteins and lipids. We also discuss briefly the promise of harnessing the molecules that undergo transcytosis as vehicles for clinical applications in drug delivery.
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Affiliation(s)
| | - Daniel J-F Chinnapen
- Division of Gastroenterology, Boston Children's Hospital, Boston, Massachusetts 02155.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02155.,Department of Pediatrics, Harvard Digestive Diseases Center, Boston, Massachusetts 02155
| | - Wayne I Lencer
- Division of Gastroenterology, Boston Children's Hospital, Boston, Massachusetts 02155.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02155.,Department of Pediatrics, Harvard Digestive Diseases Center, Boston, Massachusetts 02155
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Ventimiglia LN, Alonso MA. Biogenesis and Function of T Cell-Derived Exosomes. Front Cell Dev Biol 2016; 4:84. [PMID: 27583248 PMCID: PMC4987406 DOI: 10.3389/fcell.2016.00084] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/02/2016] [Indexed: 12/23/2022] Open
Abstract
Exosomes are a particular type of extracellular vesicle, characterized by their endosomal origin as intraluminal vesicles present in large endosomes with a multivesicular structure. After these endosomes fuse with the plasma membrane, exosomes are secreted into the extracellular space. The ability of exosomes to carry and selectively deliver bioactive molecules (e.g., lipids, proteins, and nucleic acids) confers on them the capacity to modulate the activity of receptor cells, even if these cells are located in distant tissues or organs. Since exosomal cargo depends on cell type, a detailed understanding of the mechanisms that regulate the biochemical composition of exosomes is fundamental to a comprehensive view of exosome function. Here, we review the latest advances concerning exosome function and biogenesis in T cells, with particular focus on the mechanism of protein sorting at multivesicular endosomes. Exosomes secreted by specific T-cell subsets can modulate the activity of immune cells, including other T-cell subsets. Ceramide, tetraspanins and MAL have been revealed to be important in exosome biogenesis by T cells. These molecules, therefore, constitute potential molecular targets for artificially modulating exosome production and, hence, the immune response for therapeutic purposes.
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Affiliation(s)
- Leandro N Ventimiglia
- Cell Biology and Immunology, Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid Madrid, Spain
| | - Miguel A Alonso
- Cell Biology and Immunology, Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid Madrid, Spain
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Bijlard M, de Jonge JC, Klunder B, Nomden A, Hoekstra D, Baron W. MAL Is a Regulator of the Recruitment of Myelin Protein PLP to Membrane Microdomains. PLoS One 2016; 11:e0155317. [PMID: 27171274 PMCID: PMC4865042 DOI: 10.1371/journal.pone.0155317] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/27/2016] [Indexed: 11/18/2022] Open
Abstract
In oligodendrocytes (OLGs), an indirect, transcytotic pathway is mediating transport of de novo synthesized PLP, a major myelin specific protein, from the apical-like plasma membrane to the specialized basolateral-like myelin membrane to prevent its premature compaction. MAL is a well-known regulator of polarized trafficking in epithelial cells, and given its presence in OLGs it was therefore of interest to investigate whether MAL played a similar role in PLP transport in OLGs, taking into account its timely expression in these cells. Our data revealed that premature expression of mCherry-MAL in oligodendrocyte progenitor cells interfered with terminal OLG differentiation, although myelin membrane formation per se was not impaired. In fact, also PLP transport to myelin membranes via the cell body plasma membrane was unaffected. However, the typical shift of PLP from TX-100-insoluble membrane domains to CHAPS-resistant, but TX-100-soluble membrane domains, seen in the absence of MAL expression, is substantially reduced upon expression of the MAL protein. Interestingly, not only in vitro, but also in developing brain a strongly diminished shift from TX-100 resistant to TX-100 soluble domains was observed. Consistently, the MAL-expression mediated annihilation of the typical membrane microdomain shift of PLP is also reflected by a loss of the characteristic surface expression profile of conformation-sensitive anti-PLP antibodies. Hence, these findings suggest that MAL is not involved in vesicular PLP trafficking to either the plasma membrane and/or the myelin membrane as such. Rather, we propose that MAL may regulate PLP’s distribution into distinct membrane microdomains that allow for lateral diffusion of PLP, directly from the plasma membrane to the myelin membrane once the myelin sheath has been assembled.
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Affiliation(s)
- Marjolein Bijlard
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Jenny C. de Jonge
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Bert Klunder
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Anita Nomden
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Dick Hoekstra
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Wia Baron
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
- * E-mail:
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Yaffe Y, Hugger I, Yassaf IN, Shepshelovitch J, Sklan EH, Elkabetz Y, Yeheskel A, Pasmanik-Chor M, Benzing C, Macmillan A, Gaus K, Eshed-Eisenbach Y, Peles E, Hirschberg K. The myelin proteolipid plasmolipin forms oligomers and induces liquid-ordered membranes in the Golgi complex. J Cell Sci 2015; 128:2293-302. [DOI: 10.1242/jcs.166249] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 05/18/2015] [Indexed: 01/27/2023] Open
Abstract
ABSTRACT
Myelin comprises a compactly stacked massive surface area of protein-poor thick membrane that insulates axons to allow fast signal propagation. Increasing levels of the myelin protein plasmolipin (PLLP) were correlated with post-natal myelination; however, its function is unknown. Here, the intracellular localization and dynamics of PLLP were characterized in primary glial and cultured cells using fluorescently labeled PLLP and antibodies against PLLP. PLLP localized to and recycled between the plasma membrane and the Golgi complex. In the Golgi complex, PLLP forms oligomers based on fluorescence resonance energy transfer (FRET) analyses. PLLP oligomers blocked Golgi to plasma membrane transport of the secretory protein vesicular stomatitis virus G protein (VSVG), but not of a VSVG mutant with an elongated transmembrane domain. Laurdan staining analysis showed that this block is associated with PLLP-induced proliferation of liquid-ordered membranes. These findings show the capacity of PLLP to assemble potential myelin membrane precursor domains at the Golgi complex through its oligomerization and ability to attract liquid-ordered lipids. These data support a model in which PLLP functions in myelin biogenesis through organization of myelin liquid-ordered membranes in the Golgi complex.
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Affiliation(s)
- Yakey Yaffe
- Department of Pathology, Sackler School of Medicine, Tel-Aviv 69978, Israel
| | - Ilan Hugger
- Department of Pathology, Sackler School of Medicine, Tel-Aviv 69978, Israel
| | - Inbar Nevo Yassaf
- Department of Pathology, Sackler School of Medicine, Tel-Aviv 69978, Israel
| | | | - Ella H. Sklan
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel-Aviv 69978, Israel
| | - Yechiel Elkabetz
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel-Aviv 69978, Israel
| | - Adva Yeheskel
- Bioinformatics Unit, G.S.W. Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Metsada Pasmanik-Chor
- Bioinformatics Unit, G.S.W. Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Carola Benzing
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and ARC Centre of Excellence in Advanced Molecular Imaging, Centre for Vascular Research University of New South Wales, Sydney, Australia 2033
| | - Alexander Macmillan
- Biomedical Imaging Facility, University of New South Wales, Sydney, Australia 2033
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and ARC Centre of Excellence in Advanced Molecular Imaging, Centre for Vascular Research University of New South Wales, Sydney, Australia 2033
| | - Yael Eshed-Eisenbach
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Elior Peles
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Koret Hirschberg
- Department of Pathology, Sackler School of Medicine, Tel-Aviv 69978, Israel
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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: 4.4] [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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Reales E, Bernabé-Rubio M, Casares-Arias J, Rentero C, Fernández-Barrera J, Rangel L, Correas I, Enrich C, Andrés G, Alonso MA. The MAL protein is crucial for proper membrane condensation at the ciliary base, which is required for primary cilium elongation. J Cell Sci 2015; 128:2261-70. [DOI: 10.1242/jcs.164970] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/30/2015] [Indexed: 01/11/2023] Open
Abstract
ABSTRACT
The base of the primary cilium contains a zone of condensed membranes whose importance is not known. Here, we have studied the involvement of MAL, a tetraspanning protein that exclusively partitions into condensed membrane fractions, in the condensation of membranes at the ciliary base and investigated the importance of these membranes in primary cilium formation. We show that MAL accumulates at the ciliary base of epithelial MDCK cells. Knockdown of MAL expression resulted in a drastic reduction in the condensation of membranes at the ciliary base, the percentage of ciliated cells and the length of the cilia, but did not affect the docking of the centrosome to the plasma membrane or produce missorting of proteins to the pericentriolar zone or to the membrane of the remaining cilia. Rab8 (for which there are two isoforms, Rab8A and Rab8b), IFT88 and IFT20, which are important components of the machinery of ciliary growth, were recruited normally to the ciliary base of MAL-knockdown cells but were unable to elongate the primary cilium correctly. MAL, therefore, is crucial for the proper condensation of membranes at the ciliary base, which is required for efficient primary cilium extension.
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Affiliation(s)
- Elena Reales
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Miguel Bernabé-Rubio
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Javier Casares-Arias
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Carles Rentero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Barcelona 08036, Spain
| | - Jaime Fernández-Barrera
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Laura Rangel
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Isabel Correas
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Carlos Enrich
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Barcelona 08036, Spain
| | - Germán Andrés
- Electron Microscopy Unit, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
| | - Miguel A. Alonso
- Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
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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: 67] [Impact Index Per Article: 6.7] [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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29
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Affiliation(s)
- Yusong Guo
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3200;
| | - Daniel W. Sirkis
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3200;
| | - Randy Schekman
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3200;
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30
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Roppolo D, Boeckmann B, Pfister A, Boutet E, Rubio MC, Dénervaud-Tendon V, Vermeer JEM, Gheyselinck J, Xenarios I, Geldner N. Functional and Evolutionary Analysis of the CASPARIAN STRIP MEMBRANE DOMAIN PROTEIN Family. PLANT PHYSIOLOGY 2014; 165:1709-1722. [PMID: 24920445 PMCID: PMC4119050 DOI: 10.1104/pp.114.239137] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/08/2014] [Indexed: 05/20/2023]
Abstract
CASPARIAN STRIP MEMBRANE DOMAIN PROTEINS (CASPs) are four-membrane-span proteins that mediate the deposition of Casparian strips in the endodermis by recruiting the lignin polymerization machinery. CASPs show high stability in their membrane domain, which presents all the hallmarks of a membrane scaffold. Here, we characterized the large family of CASP-like (CASPL) proteins. CASPLs were found in all major divisions of land plants as well as in green algae; homologs outside of the plant kingdom were identified as members of the MARVEL protein family. When ectopically expressed in the endodermis, most CASPLs were able to integrate the CASP membrane domain, which suggests that CASPLs share with CASPs the propensity to form transmembrane scaffolds. Extracellular loops are not necessary for generating the scaffold, since CASP1 was still able to localize correctly when either one of the extracellular loops was deleted. The CASP first extracellular loop was found conserved in euphyllophytes but absent in plants lacking Casparian strips, an observation that may contribute to the study of Casparian strip and root evolution. In Arabidopsis (Arabidopsis thaliana), CASPL showed specific expression in a variety of cell types, such as trichomes, abscission zone cells, peripheral root cap cells, and xylem pole pericycle cells.
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Affiliation(s)
- Daniele Roppolo
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Brigitte Boeckmann
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Alexandre Pfister
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Emmanuel Boutet
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Maria C Rubio
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Valérie Dénervaud-Tendon
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Joop E M Vermeer
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Jacqueline Gheyselinck
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Ioannis Xenarios
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
| | - Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne, Quartier Sorge, Lausanne 1015, Switzerland (D.R., A.P., M.C.R., V.D.-T., J.E.M.V., N.G.);Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland (B.B., E.B., I.X.);Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, 50080 Zaragoza, Spain (M.C.R.);Vital-IT Group and University of Lausanne, Quartier Sorge, Bâtiment Génopode, Lausanne 1015, Switzerland (I.X.); andInstitute of Plant Sciences, University of Bern, 3013 Bern, Switzerland (D.R., J.G.)
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Influenza A virus hemagglutinin and neuraminidase mutually accelerate their apical targeting through clustering of lipid rafts. J Virol 2014; 88:10039-55. [PMID: 24965459 DOI: 10.1128/jvi.00586-14] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In polarized epithelial cells, influenza A virus hemagglutinin (HA) and neuraminidase (NA) are intrinsically associated with lipid rafts and target the apical plasma membrane for viral assembly and budding. Previous studies have indicated that the transmembrane domain (TMD) and cytoplasmic tail (CT) of HA and NA are required for association with lipid rafts, but the raft dependencies of their apical targeting are controversial. Here, we show that coexpression of HA with NA accelerated their apical targeting through accumulation in lipid rafts. HA was targeted to the apical plasma membrane even when expressed alone, but the kinetics was much slower than that of HA in infected cells. Coexpression experiments revealed that apical targeting of HA and NA was accelerated by their coexpression. The apical targeting of HA was also accelerated by coexpression with M1 but not M2. The mutations in the outer leaflet of the TMD and the deletion of the CT in HA and NA that reduced their association with lipid rafts abolished the acceleration of their apical transport, indicating that the lipid raft association is essential for efficient apical trafficking of HA and NA. An in situ proximity ligation assay (PLA) revealed that HA and NA were accumulated and clustered in the cytoplasmic compartments only when both were associated with lipid rafts. Analysis with mutant viruses containing nonraft HA/NA confirmed these findings. We further analyzed lipid raft markers by in situ PLA and suggest a possible mechanism of the accelerated apical transport of HA and NA via clustering of lipid rafts. IMPORTANCE Lipid rafts serve as sites for viral entry, particle assembly, and budding, leading to efficient viral replication. The influenza A virus utilizes lipid rafts for apical plasma membrane targeting and particle budding. The hemagglutinin (HA) and neuraminidase (NA) of influenza virus, key players for particle assembly, contain determinants for apical sorting and lipid raft association. However, it remains to be elucidated how lipid rafts contribute to the apical trafficking and budding. We investigated the relation of lipid raft association of HA and NA to the efficiency of apical trafficking. We show that coexpression of HA and NA induces their accumulation in lipid rafts and accelerates their apical targeting, and we suggest that the accelerated apical transport likely occurs by clustering of lipid rafts at the TGN. This finding provides the first evidence that two different raft-associated viral proteins induce lipid raft clustering, thereby accelerating apical trafficking of the viral proteins.
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Abstract
Hepatocytes, like other epithelia, are situated at the interface between the organism's exterior and the underlying internal milieu and organize the vectorial exchange of macromolecules between these two spaces. To mediate this function, epithelial cells, including hepatocytes, are polarized with distinct luminal domains that are separated by tight junctions from lateral domains engaged in cell-cell adhesion and from basal domains that interact with the underlying extracellular matrix. Despite these universal principles, hepatocytes distinguish themselves from other nonstriated epithelia by their multipolar organization. Each hepatocyte participates in multiple, narrow lumina, the bile canaliculi, and has multiple basal surfaces that face the endothelial lining. Hepatocytes also differ in the mechanism of luminal protein trafficking from other epithelia studied. They lack polarized protein secretion to the luminal domain and target single-spanning and glycosylphosphatidylinositol-anchored bile canalicular membrane proteins via transcytosis from the basolateral domain. We compare this unique hepatic polarity phenotype with that of the more common columnar epithelial organization and review our current knowledge of the signaling mechanisms and the organization of polarized protein trafficking that govern the establishment and maintenance of hepatic polarity. The serine/threonine kinase LKB1, which is activated by the bile acid taurocholate and, in turn, activates adenosine monophosphate kinase-related kinases including AMPK1/2 and Par1 paralogues has emerged as a key determinant of hepatic polarity. We propose that the absence of a hepatocyte basal lamina and differences in cell-cell adhesion signaling that determine the positioning of tight junctions are two crucial determinants for the distinct hepatic and columnar polarity phenotypes.
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Affiliation(s)
- Aleksandr Treyer
- Albert Einstein College of Medicine, Department of Developmental and Molecular Biology, Bronx, New York, USA
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Abstract
Tyrosine phosphorylation is one of the key covalent modifications that occur in multicellular organisms. Since its discovery more than 30 years ago, tyrosine phosphorylation has come to be understood as a fundamentally important mechanism of signal transduction and regulation in all eukaryotic cells. The tyrosine kinase Lck (lymphocyte-specific protein tyrosine kinase) plays a crucial role in the T-cell response by transducing early activation signals triggered by TCR (T-cell receptor) engagement. These signals result in the phosphorylation of immunoreceptor tyrosine-based activation motifs present within the cytosolic tails of the TCR-associated CD3 subunits that, once phosphorylated, serve as scaffolds for the assembly of a large supramolecular signalling complex responsible for T-cell activation. The existence of membrane nano- or micro-domains or rafts as specialized platforms for protein transport and cell signalling has been proposed. The present review discusses the signals that target Lck to membrane rafts and the importance of these specialized membranes in the transport of Lck to the plasma membrane, the regulation of Lck activity and the phosphorylation of the TCR.
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Aranda JF, Reglero-Real N, Marcos-Ramiro B, Ruiz-Sáenz A, Fernández-Martín L, Bernabé-Rubio M, Kremer L, Ridley AJ, Correas I, Alonso MA, Millán J. MYADM controls endothelial barrier function through ERM-dependent regulation of ICAM-1 expression. Mol Biol Cell 2013; 24:483-94. [PMID: 23264465 PMCID: PMC3571871 DOI: 10.1091/mbc.e11-11-0914] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 11/15/2012] [Accepted: 12/14/2012] [Indexed: 11/18/2022] Open
Abstract
The endothelium maintains a barrier between blood and tissue that becomes more permeable during inflammation. Membrane rafts are ordered assemblies of cholesterol, glycolipids, and proteins that modulate proinflammatory cell signaling and barrier function. In epithelial cells, the MAL family members MAL, MAL2, and myeloid-associated differentiation marker (MYADM) regulate the function and dynamics of ordered membrane domains. We analyzed the expression of these three proteins in human endothelial cells and found that only MYADM is expressed. MYADM was confined in ordered domains at the plasma membrane, where it partially colocalized with filamentous actin and cell-cell junctions. Small interfering RNA (siRNA)-mediated MYADM knockdown increased permeability, ICAM-1 expression, and leukocyte adhesion, all of which are features of an inflammatory response. Barrier function decrease in MYADM-silenced cells was dependent on ICAM-1 expression. Membrane domains and the underlying actin cytoskeleton can regulate each other and are connected by ezrin, radixin, and moesin (ERM) proteins. In endothelial cells, MYADM knockdown induced ERM activation. Triple-ERM knockdown partially inhibited ICAM-1 increase induced by MYADM siRNA. Importantly, ERM knockdown also reduced ICAM-1 expression in response to the proinflammatory cytokine tumor necrosis factor-α. MYADM therefore regulates the connection between the plasma membrane and the cortical cytoskeleton and so can control the endothelial inflammatory response.
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Affiliation(s)
- Juan F. Aranda
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Natalia Reglero-Real
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Beatriz Marcos-Ramiro
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Ana Ruiz-Sáenz
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Laura Fernández-Martín
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Miguel Bernabé-Rubio
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Leonor Kremer
- Centro Nacional de Biotecnología. Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain
| | - Anne J. Ridley
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, United Kingdom
| | - Isabel Correas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Miguel A. Alonso
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Jaime Millán
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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Abstract
Epithelial cells have an apical-basolateral axis of polarity, which is required for epithelial functions including barrier formation, vectorial ion transport and sensory perception. Here we review what is known about the sorting signals, machineries and pathways that maintain this asymmetry, and how polarity proteins interface with membrane-trafficking pathways to generate membrane domains de novo. It is becoming apparent that membrane traffic does not simply reinforce polarity, but is critical for the generation of cortical epithelial cell asymmetry.
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Werner HB, Krämer-Albers EM, Strenzke N, Saher G, Tenzer S, Ohno-Iwashita Y, De Monasterio-Schrader P, Möbius W, Moser T, Griffiths IR, Nave KA. A critical role for the cholesterol-associated proteolipids PLP and M6B in myelination of the central nervous system. Glia 2013; 61:567-86. [PMID: 23322581 DOI: 10.1002/glia.22456] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 11/30/2012] [Indexed: 12/13/2022]
Abstract
The formation of central nervous system myelin by oligodendrocytes requires sterol synthesis and is associated with a significant enrichment of cholesterol in the myelin membrane. However, it is unknown how oligodendrocytes concentrate cholesterol above the level found in nonmyelin membranes. Here, we demonstrate a critical role for proteolipids in cholesterol accumulation. Mice lacking the most abundant myelin protein, proteolipid protein (PLP), are fully myelinated, but PLP-deficient myelin exhibits a reduced cholesterol content. We therefore hypothesized that "high cholesterol" is not essential in the myelin sheath itself but is required for an earlier step of myelin biogenesis that is fully compensated for in the absence of PLP. We also found that a PLP-homolog, glycoprotein M6B, is a myelin component of low abundance. By targeting the Gpm6b-gene and crossbreeding, we found that single-mutant mice lacking either PLP or M6B are fully myelinated, while double mutants remain severely hypomyelinated, with enhanced neurodegeneration and premature death. As both PLP and M6B bind membrane cholesterol and associate with the same cholesterol-rich oligodendroglial membrane microdomains, we suggest a model in which proteolipids facilitate myelination by sequestering cholesterol. While either proteolipid can maintain a threshold level of cholesterol in the secretory pathway that allows myelin biogenesis, lack of both proteolipids results in a severe molecular imbalance of prospective myelin membrane. However, M6B is not efficiently sorted into mature myelin, in which it is 200-fold less abundant than PLP. Thus, only PLP contributes to the high cholesterol content of myelin by association and co-transport.
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Affiliation(s)
- Hauke B Werner
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Goettingen, Germany.
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Abstract
Phagocytosis and innate immune responses to solid structures are topics of interest and debate. Alum, monosodium urate, calcium pyrophosphate dehydrate, silica and by extension all solid entities draw varying degrees of attention from phagocytes, such as antigen presenting cells. For some, innocuous soluble metabolites turn into fierce irritants upon crystallization, pointing to divergent signaling mechanisms of a given substance in its soluble and solid states. Over the years, many mechanisms have been proposed, including phagocytic receptors, toll like receptors, and NACHT-LRRs (NLRs), as well as several other protein structure mediated recognition of the solids. Is there a more general mechanism for sensing solids? In this perspective, I present an alternative view on the topic that membrane lipids can engage solid surfaces, and the binding intensity leads to cellular activation. I argue from the stands of evolution and biological necessity, as well as the progression of our understanding of cellular membranes and phagocytosis. The effort is to invite debate of the topic from a less familiar yet equally thrilling viewing angle.
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Affiliation(s)
- Yan Shi
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China.
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Takiar V, Mistry K, Carmosino M, Schaeren-Wiemers N, Caplan MJ. VIP17/MAL expression modulates epithelial cyst formation and ciliogenesis. Am J Physiol Cell Physiol 2012; 303:C862-71. [PMID: 22895261 PMCID: PMC3469709 DOI: 10.1152/ajpcell.00338.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 08/13/2012] [Indexed: 11/22/2022]
Abstract
The polarized organization of epithelial cells is required for vectorial solute transport and may be altered in renal cystic diseases. Vesicle integral protein of 17 kDa (VIP17/MAL) is involved in apical vesicle transport. VIP17/MAL overexpression in vivo results in renal cystogenesis of unknown etiology. Renal cystogenesis can occur as a consequence of defects of the primary cilium. To explore the role of VIP17/MAL in renal cystogenesis and ciliogenesis, we examined the polarization and ciliary morphology of wild-type and VIP17/MAL overexpressing Madin-Darby canine kidney renal epithelial cells grown in two-dimensional (2D) and three-dimensional (3D) cyst culture. VIP17/MAL is apically localized when expressed in cells maintained in 2D and 3D culture. VIP17/MAL overexpressing cells produce more multilumen cysts compared with controls. While the distributions of basolateral markers are not affected, VIP17/MAL expression results in aberrant sorting of the apical marker gp135 to the primary cilium. VIP17/MAL overexpression is also associated with shortened or absent cilia. Immunofluorescence analysis performed on kidney sections from VIP17/MAL transgenic mice also demonstrates fewer and shortened cilia within dilated lumens (P < 0.01). These studies demonstrate that VIP17/MAL overexpression results in abnormal cilium and cyst development, in vitro and in vivo, suggesting that VIP17/MAL overexpressing mice may develop cysts secondary to a ciliary defect.
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Affiliation(s)
- Vinita Takiar
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut 06520-8026, USA
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40
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Abstract
The polarized distribution of proteins and lipids at the surface membrane of epithelial cells results in the formation of an apical and a basolateral domain, which are separated by tight junctions. The generation and maintenance of epithelial polarity require elaborate mechanisms that guarantee correct sorting and vectorial delivery of cargo molecules. This dynamic process involves the interaction of sorting signals with sorting machineries and the formation of transport carriers. Here we review the recent advances in the field of polarized sorting in epithelial cells. We especially highlight the role of lipid rafts in apical sorting.
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Yaffe Y, Shepshelovitch J, Nevo-Yassaf I, Yeheskel A, Shmerling H, Kwiatek JM, Gaus K, Pasmanik-Chor M, Hirschberg K. The MARVEL transmembrane motif of occludin mediates oligomerization and targeting to the basolateral surface in epithelia. J Cell Sci 2012; 125:3545-56. [PMID: 22492786 DOI: 10.1242/jcs.100289] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Occludin (Ocln), a MARVEL-motif-containing protein, is found in all tight junctions. MARVEL motifs are comprised of four transmembrane helices associated with the localization to or formation of diverse membrane subdomains by interacting with the proximal lipid environment. The functions of the Ocln MARVEL motif are unknown. Bioinformatics sequence- and structure-based analyses demonstrated that the MARVEL domain of Ocln family proteins has distinct evolutionarily conserved sequence features that are consistent with its basolateral membrane localization. Live-cell microscopy, fluorescence resonance energy transfer (FRET) and bimolecular fluorescence complementation (BiFC) were used to analyze the intracellular distribution and self-association of fluorescent-protein-tagged full-length human Ocln or the Ocln MARVEL motif excluding the cytosolic C- and N-termini (amino acids 60-269, FP-MARVEL-Ocln). FP-MARVEL-Ocln efficiently arrived at the plasma membrane (PM) and was sorted to the basolateral PM in filter-grown polarized MDCK cells. A series of conserved aromatic amino acids within the MARVEL domain were found to be associated with Ocln dimerization using BiFC. FP-MARVEL-Ocln inhibited membrane pore growth during Triton-X-100-induced solubilization and was shown to increase the membrane-ordered state using Laurdan, a lipid dye. These data demonstrate that the Ocln MARVEL domain mediates self-association and correct sorting to the basolateral membrane.
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Affiliation(s)
- Yakey Yaffe
- Department of Pathology, Sackler School of Medicine, Tel-Aviv 69978, Israel
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42
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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: 31] [Impact Index Per Article: 2.4] [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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Surma MA, Klose C, Simons K. Lipid-dependent protein sorting at the trans-Golgi network. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:1059-67. [PMID: 22230596 DOI: 10.1016/j.bbalip.2011.12.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Revised: 12/02/2011] [Accepted: 12/03/2011] [Indexed: 12/14/2022]
Abstract
In eukaryotic cells, the trans-Golgi network serves as a sorting station for post-Golgi traffic. In addition to coat- and adaptor-mediated mechanisms, studies in mammalian epithelial cells and yeast have provided evidence for lipid-dependent protein sorting as a major delivery mechanism for cargo sorting to the cell surface. The mechanism for lipid-mediated sorting is the generation of raft platforms of sphingolipids, sterols and specific sets of cargo proteins by phase segregation in the TGN. Here, we review the evidence for such lipid-raft-based sorting at the TGN, as well as their involvement in the formation of TGN-to-PM transport carriers. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
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Affiliation(s)
- Michal A Surma
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
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45
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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: 26] [Impact Index Per Article: 1.9] [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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Ziegler A, Seelig J. Contributions of Glycosaminoglycan Binding and Clustering to the Biological Uptake of the Nonamphipathic Cell-Penetrating Peptide WR9. Biochemistry 2011; 50:4650-64. [DOI: 10.1021/bi1019429] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- André Ziegler
- Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Joachim Seelig
- Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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Antón OM, Andrés-Delgado L, Reglero-Real N, Batista A, Alonso MA. MAL protein controls protein sorting at the supramolecular activation cluster of human T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2011; 186:6345-56. [PMID: 21508261 DOI: 10.4049/jimmunol.1003771] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
T cell membrane receptors and signaling molecules assemble at the immunological synapse (IS) in a supramolecular activation cluster (SMAC), organized into two differentiated subdomains: the central SMAC (cSMAC), with the TCR, Lck, and linker for activation of T cells (LAT), and the peripheral SMAC (pSMAC), with adhesion molecules. The mechanism of protein sorting to the SMAC subdomains is still unknown. MAL forms part of the machinery for protein targeting to the plasma membrane by specialized mechanisms involving condensed membranes or rafts. In this article, we report our investigation of the dynamics of MAL during the formation of the IS and its role in SMAC assembly in the Jurkat T cell line and human primary T cells. We observed that under normal conditions, a pool of MAL rapidly accumulates at the cSMAC, where it colocalized with condensed membranes, as visualized with the membrane fluorescent probe Laurdan. Mislocalization of MAL to the pSMAC greatly reduced membrane condensation at the cSMAC and redistributed machinery involved in docking microtubules or transport vesicles from the cSMAC to the pSMAC. As a consequence of these alterations, the raft-associated molecules Lck and LAT, but not the TCR, were missorted to the pSMAC. MAL, therefore, regulates membrane order and the distribution of microtubule and transport vesicle docking machinery at the IS and, by doing so, ensures correct protein sorting of Lck and LAT to the cSMAC.
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Affiliation(s)
- Olga M Antón
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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Aranda JF, Reglero-Real N, Kremer L, Marcos-Ramiro B, Ruiz-Sáenz A, Calvo M, Enrich C, Correas I, Millán J, Alonso MA. MYADM regulates Rac1 targeting to ordered membranes required for cell spreading and migration. Mol Biol Cell 2011; 22:1252-62. [PMID: 21325632 PMCID: PMC3078064 DOI: 10.1091/mbc.e10-11-0910] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Membrane organization into condensed domains or rafts provides molecular platforms for selective recruitment of proteins. Cell migration is a general process that requires spatiotemporal targeting of Rac1 to membrane rafts. The protein machinery responsible for making rafts competent to recruit Rac1 remains elusive. Some members of the MAL family of proteins are involved in specialized processes dependent on this type of membrane. Because condensed membrane domains are a general feature of the plasma membrane of all mammalian cells, we hypothesized that MAL family members with ubiquitous expression and plasma membrane distribution could be involved in the organization of membranes for cell migration. We show that myeloid-associated differentiation marker (MYADM), a protein with unique features within the MAL family, colocalizes with Rac1 in membrane protrusions at the cell surface and distributes in condensed membranes. MYADM knockdown (KD) cells had altered membrane condensation and showed deficient incorporation of Rac1 to membrane raft fractions and, similar to Rac1 KD cells, exhibited reduced cell spreading and migration. Results of rescue-of-function experiments by expression of MYADM or active Rac1L61 in cells knocked down for Rac1 or MYADM, respectively, are consistent with the idea that MYADM and Rac1 act on parallel pathways that lead to similar functional outcomes.
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Affiliation(s)
- Juan F Aranda
- Centro de Biología Molecular Severo Ochoa, Cantoblanco, 28049 Madrid, Spain
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49
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Saslowsky DE, Cho JA, Chinnapen H, Massol RH, Chinnapen DJF, Wagner JS, De Luca HE, Kam W, Paw BH, Lencer WI. Intoxication of zebrafish and mammalian cells by cholera toxin depends on the flotillin/reggie proteins but not Derlin-1 or -2. J Clin Invest 2011; 120:4399-4409. [PMID: 21041954 DOI: 10.1172/jci42958] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 09/15/2010] [Indexed: 02/06/2023] Open
Abstract
Cholera toxin (CT) causes the massive secretory diarrhea associated with epidemic cholera. To induce disease, CT enters the cytosol of host cells by co-opting a lipid-based sorting pathway from the plasma membrane, through the trans-Golgi network (TGN), and into the endoplasmic reticulum (ER). In the ER, a portion of the toxin is unfolded and retro- translocated to the cytosol. Here, we established zebrafish as a genetic model of intoxication and examined the Derlin and flotillin proteins, which are thought to be usurped by CT for retro-translocation and lipid sorting, respectively. Using antisense morpholino oligomers and siRNA, we found that depletion of Derlin-1, a component of the Hrd-1 retro-translocation complex, was dispensable for CT-induced toxicity. In contrast, the lipid raft-associated proteins flotillin-1 and -2 were required. We found that in mammalian cells, CT intoxication was dependent on the flotillins for trafficking between plasma membrane/endosomes and two pathways into the ER, only one of which appears to intersect the TGN. These results revise current models for CT intoxication and implicate protein scaffolding of lipid rafts in the endo-somal sorting of the toxin-GM1 complex.
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Affiliation(s)
- David E Saslowsky
- Division of Gastroenterology, Children's Hospital, Boston, Massachusetts, USA
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Safouane M, Berland L, Callan-Jones A, Sorre B, Römer W, Johannes L, Toombes GES, Bassereau P. Lipid Cosorting Mediated by Shiga Toxin Induced Tubulation. Traffic 2010; 11:1519-29. [DOI: 10.1111/j.1600-0854.2010.01116.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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