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Kim M, Jung KH, Kim JL, Koo HJ, Jung HJ, Lee H, Lee KH. Imaging Very Late Antigen-4 on MOLT4 Leukemia Tumors with Cysteine Site-Specific 89Zr-Labeled Natalizumab Immuno-Positron Emission Tomography. Mol Pharm 2024; 21:1353-1363. [PMID: 38282332 DOI: 10.1021/acs.molpharmaceut.3c01024] [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] [Indexed: 01/30/2024]
Abstract
Very late antigen-4 (VLA4; CD49d) is a promising immune therapy target in treatment-resistant leukemia and multiple myeloma, and there is growing interest in repurposing the humanized monoclonal antibody (Ab), natalizumab, for this purpose. Positron emission tomography with radiolabeled Abs (immuno-PET) could facilitate this effort by providing information on natalizumab's in vivo pharmacokinetic and target delivery properties. In this study, we labeled natalizumab with 89Zr specifically on sulfhydryl moieties via maleimide-deferoxamine conjugation. High VLA4-expressing MOLT4 human T cell acute lymphoblastic leukemia cells showed specific 89Zr-natalizumab binding that was markedly blocked by excess Ab. In nude mice bearing MOLT4 tumors, 89Zr-natalizumab PET showed high-contrast tumor uptake at 7 days postinjection. Biodistribution studies confirmed that uptake was the highest in MOLT4 tumors (2.22 ± 0.41%ID/g) and the liver (2.33 ± 0.76%ID/g), followed by the spleen (1.51 ± 0.42%ID/g), while blood activity was lower at 1.12 ± 0.21%ID/g. VLA4-specific targeting in vivo was confirmed by a 58.1% suppression of tumor uptake (0.93 ± 0.15%ID/g) when excess Ab was injected 1 h earlier. In cultured MOLT4 cells, short-term 3 day exposure to the proteasome inhibitor bortezomib (BTZ) did not affect the α4 integrin level, but BTZ-resistant cells that survived the treatment showed increased α4 integrin expression. When the effects of BTZ treatment were tested in mice, there was no change of the α4 integrin level or 89Zr-natalizumab uptake in MOLT4 leukemia tumors, which underscores the complexity of tumor VLA4 regulation in vivo. In conclusion, 89Zr-natalizumab PET may be useful for noninvasive monitoring of tumor VLA4 and may assist in a more rational application of Ab-based therapies for hematologic malignancies.
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Affiliation(s)
- Mina Kim
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06355, Korea
| | - Kyung-Ho Jung
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06355, Korea
| | - Jung Lim Kim
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Hyun-Jung Koo
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Hye Jin Jung
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Hyunjong Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Kyung-Han Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06355, Korea
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2
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Querol Cano L, Dunlock VME, Schwerdtfeger F, van Spriel AB. Membrane organization by tetraspanins and galectins shapes lymphocyte function. Nat Rev Immunol 2024; 24:193-212. [PMID: 37758850 DOI: 10.1038/s41577-023-00935-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2023] [Indexed: 09/29/2023]
Abstract
Immune receptors are not randomly distributed at the plasma membrane of lymphocytes but are segregated into specialized domains that function as platforms to initiate signalling, as exemplified by the B cell or T cell receptor complex and the immunological synapse. 'Membrane-organizing proteins' and, in particular, tetraspanins and galectins, are crucial for controlling the spatiotemporal organization of immune receptors and other signalling proteins. Deficiencies in specific tetraspanins and galectins result in impaired immune synapse formation, lymphocyte proliferation, antibody production and migration, which can lead to impaired immunity, tumour development and autoimmunity. In contrast to conventional ligand-receptor interactions, membrane organizers interact in cis (on the same cell) and modulate receptor clustering, receptor dynamics and intracellular signalling. New findings have uncovered their complex and dynamic nature, revealing shared binding partners and collaborative activity in determining the composition of membrane domains. Therefore, immune receptors should not be envisaged as independent entities and instead should be studied in the context of their spatial organization in the lymphocyte membrane. We advocate for a novel approach to study lymphocyte function by globally analysing the role of membrane organizers in the assembly of different membrane complexes and discuss opportunities to develop therapeutic approaches that act via the modulation of membrane organization.
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Affiliation(s)
- Laia Querol Cano
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Vera-Marie E Dunlock
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Fabian Schwerdtfeger
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Annemiek B van Spriel
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands.
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3
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Schmidt SC, Massenberg A, Homsi Y, Sons D, Lang T. Microscopic clusters feature the composition of biochemical tetraspanin-assemblies and constitute building-blocks of tetraspanin enriched domains. Sci Rep 2024; 14:2093. [PMID: 38267610 PMCID: PMC10808221 DOI: 10.1038/s41598-024-52615-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 01/21/2024] [Indexed: 01/26/2024] Open
Abstract
Biochemical approaches revealed that tetraspanins are multi-regulatory proteins forming a web, where they act in tetraspanin-enriched-microdomains (TEMs). A microscopic criterion differentiating between web and TEMs is lacking. Using super-resolution microcopy, we identify co-assemblies between the tetraspanins CD9 and CD81 and CD151 and CD81. CD9 assemblies contain as well the CD9/CD81-interaction partner EWI-2. Moreover, CD9 clusters are proximal to clusters of the CD81-interaction partner CD44 and CD81-/EWI-2-interacting ezrin-radixin-moesin proteins. Assemblies scatter unorganized across the cell membrane; yet, upon EWI-2 elevation, they agglomerate into densely packed arranged-crowds in a process independent from actin dynamics. In conclusion, microscopic clusters are equivalent to biochemical tetraspanin-assemblies, defining in their entirety the tetraspanin web. Cluster-agglomeration enriches tetraspanins, which makes agglomerations to a microscopic complement of TEMs. The microscopic classification of tetraspanin assemblies advances our understanding of this enigmatic protein family, whose members play roles in a plethora of cellular functions, diseases, and pathogen infections.
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Affiliation(s)
- Sara C Schmidt
- Faculty of Mathematics and Natural Sciences, Life & Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straße 31, 53115, Bonn, Germany
| | - Annika Massenberg
- Faculty of Mathematics and Natural Sciences, Life & Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straße 31, 53115, Bonn, Germany
| | - Yahya Homsi
- Faculty of Mathematics and Natural Sciences, Life & Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straße 31, 53115, Bonn, Germany
| | - Dominik Sons
- Faculty of Mathematics and Natural Sciences, Life & Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straße 31, 53115, Bonn, Germany
| | - Thorsten Lang
- Faculty of Mathematics and Natural Sciences, Life & Medical Sciences (LIMES) Institute, University of Bonn, Carl-Troll-Straße 31, 53115, Bonn, Germany.
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4
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Bailly C, Thuru X. Targeting of Tetraspanin CD81 with Monoclonal Antibodies and Small Molecules to Combat Cancers and Viral Diseases. Cancers (Basel) 2023; 15:cancers15072186. [PMID: 37046846 PMCID: PMC10093296 DOI: 10.3390/cancers15072186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/04/2023] [Accepted: 04/04/2023] [Indexed: 04/14/2023] Open
Abstract
Tetraspanin CD81 plays major roles in cell-cell interactions and the regulation of cellular trafficking. This cholesterol-embarking transmembrane protein is a co-receptor for several viruses, including HCV, HIV-1 and Chikungunya virus, which exploits the large extracellular loop EC2 for cell entry. CD81 is also an anticancer target implicated in cancer cell proliferation and mobility, and in tumor metastasis. CD81 signaling contributes to the development of solid tumors (notably colorectal, liver and gastric cancers) and has been implicated in the aggressivity of B-cell lymphomas. A variety of protein partners can interact with CD81, either to regulate attachment and uptake of viruses (HCV E2, claudin-1, IFIM1) or to contribute to tumor growth and dissemination (CD19, CD44, EWI-2). CD81-protein interactions can be modulated with molecules targeting the extracellular domain of CD81, investigated as antiviral and/or anticancer agents. Several monoclonal antibodies anti-CD81 have been developed, notably mAb 5A6 active against invasion and metastasis of triple-negative breast cancer cells. CD81-EC2 can also be targeted with natural products (trachelogenin and harzianoic acids A-B) and synthetic compounds (such as benzothiazole-quinoline derivatives). They are weak CD81 binders but offer templates for the design of new compounds targeting the open EC2 loop. There is no anti-CD81 compound in clinical development at present, but this structurally well-characterized tetraspanin warrants more substantial considerations as a drug target.
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Affiliation(s)
- Christian Bailly
- OncoWitan, Scientific Consulting Office, F-59290 Lille, France
- Institut de Chimie Pharmaceutique Albert Lespagnol (ICPAL), Faculty of Pharmacy, University of Lille, F-59006 Lille, France
- CNRS, Inserm, CHU Lille, UMR9020-U1277-Canther-Cancer Heterogeneity Plasticity and Resistance to Therapies, OncoLille Institut, University of Lille, F-59000 Lille, France
| | - Xavier Thuru
- CNRS, Inserm, CHU Lille, UMR9020-U1277-Canther-Cancer Heterogeneity Plasticity and Resistance to Therapies, OncoLille Institut, University of Lille, F-59000 Lille, France
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5
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Ding Y, Chen J, Li S, Wren JD, Bajpai AK, Wang J, Tanaka T, Rice HC, Hays FA, Lu L, Zhang XA. EWI2 and its relatives in Tetraspanin-enriched membrane domains regulate malignancy. Oncogene 2023; 42:861-868. [PMID: 36788350 DOI: 10.1038/s41388-023-02623-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/24/2023] [Accepted: 02/01/2023] [Indexed: 02/16/2023]
Abstract
Experimental studies on immunoglobulin superfamily (IgSF) member EWI2 reveal that it suppresses a variety of solid malignant tumors including brain, lung, skin, and prostate cancers in animal models and inhibits tumor cell movement and growth in vitro. While EWI2 appears to support myeloid leukemia in mouse models and maintain leukemia stem cells. Bioinformatics analyses suggest that EWI2 gene expression is downregulated in glioblastoma but upregulated in melanoma, pancreatic cancer, and liver cancer. The mechanism of action for EWI2 is linked to its inhibition of growth factor receptors and cell adhesion proteins through its associated tetraspanin-enriched membrane domains (TEMDs), by altering the cell surface clustering and endolysosome trafficking/turnover of these transmembrane proteins. Recent studies also show that EWI2 modulates the nuclear translocation of ERK and TFEB to change the activities of these gene expression regulators. For EWI2 relatives including FPRP, IgSF3, and CD101, although their roles in malignant diseases are not fully clear and remain to be determined experimentally, FPRP and IgSF3 likely promote the progression of solid malignant tumors while CD101 seems to modulate immune cells of tumor microenvironment. Distinctive from other tumor regulators, the impacts of EWI subfamily members on solid malignant tumors are likely to be context dependent. In other words, the effect of a given EWI subfamily member on a tumor probably depends on the molecular network and composition of TEMDs in that tumor. Collectively, EWI2 and its relatives are emerged as important regulators of malignant diseases with promising potentials to become anti-cancer therapeutics and cancer therapy targets.
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Affiliation(s)
- Yingjun Ding
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Junxiong Chen
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Shuping Li
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Jonathan D Wren
- Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | | | - Jie Wang
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Takemi Tanaka
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Heather C Rice
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Franklin A Hays
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Lu Lu
- University of Tennessee Health Science Center, Memphis, TN, USA
| | - Xin A Zhang
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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6
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Abstract
Single-pass transmembrane receptors (SPTMRs) represent a diverse group of integral membrane proteins that are involved in many essential cellular processes, including signal transduction, cell adhesion, and transmembrane transport of materials. Dysregulation of the SPTMRs is linked with many human diseases. Despite extensive efforts in past decades, the mechanisms of action of the SPTMRs remain incompletely understood. One major hurdle is the lack of structures of the full-length SPTMRs in different functional states. Such structural information is difficult to obtain by traditional structural biology methods such as X-ray crystallography and nuclear magnetic resonance (NMR). The recent rapid development of single-particle cryo-electron microscopy (cryo-EM) has led to an exponential surge in the number of high-resolution structures of integral membrane proteins, including SPTMRs. Cryo-EM structures of SPTMRs solved in the past few years have tremendously improved our understanding of how SPTMRs function. In this review, we will highlight these progresses in the structural studies of SPTMRs by single-particle cryo-EM, analyze important structural details of each protein involved, and discuss their implications on the underlying mechanisms. Finally, we also briefly discuss remaining challenges and exciting opportunities in the field.
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Affiliation(s)
- Kai Cai
- Departments of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75231, USA
| | - Xuewu Zhang
- Departments of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75231, USA
- Departments of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75231, USA
- Corresponding Author: Xuewu Zhang, Department of pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA;
| | - Xiao-chen Bai
- Departments of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75231, USA
- Departments of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75231, USA
- Corresponding Author: Xiao-chen Bai, Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390, USA;
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7
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Jimbo K, Nakajima-Takagi Y, Ito T, Koide S, Nannya Y, Iwama A, Tojo A, Konuma T. Immunoglobulin superfamily member 8 maintains myeloid leukemia stem cells through inhibition of β-catenin degradation. Leukemia 2022; 36:1550-1562. [PMID: 35418614 DOI: 10.1038/s41375-022-01564-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 03/09/2022] [Accepted: 03/30/2022] [Indexed: 11/10/2022]
Abstract
The identification of characteristic differences between cancer stem cells and their normal counterparts remains a key challenge for cancer treatment. Here, we investigated the role of immunoglobulin superfamily member 8 (Igsf8, also known as EWI-2, PGRL, and CD316) on normal and malignant hematopoietic stem cells, mainly using the conditional knockout model. Deletion of Igsf8 did not affect steady state hematopoiesis, but it led to a significant improvement of survival in mouse myeloid leukemia models. Deletion of Igsf8 significantly depletes leukemia stem cells (LSCs) through enhanced apoptosis and β-catenin degradation. At a molecular level, we found that activation of β-catenin in LSCs depends on Igsf8, which promotes the association of FZD4 with its co-receptor LRP6 in the presence of Igsf8. Similarly, IGSF8 inhibition blocks the colony-forming ability of LSCs and improves the survival of recipients in xenograft models of myeloid leukemia. Collectively, these data indicate strong genetic evidence identifying Igsf8 as a key regulator of myeloid leukemia and the possibility that targeting IGSF8 may serve as a new therapeutic approach against myeloid leukemia.
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Affiliation(s)
- Koji Jimbo
- Division of Hematopoietic Disease Control, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,Division of Molecular Therapy, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,Division of Stem Cell and Molecular Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yaeko Nakajima-Takagi
- Division of Stem Cell and Molecular Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Takahiro Ito
- Laboratory of Cell Fate Dynamics and Therapeutics, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Shuhei Koide
- Division of Stem Cell and Molecular Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yasuhito Nannya
- Division of Hematopoietic Disease Control, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,Department of Hematology/Oncology, Research Hospital, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Atsushi Iwama
- Division of Stem Cell and Molecular Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Arinobu Tojo
- Division of Molecular Therapy, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,Department of Hematology/Oncology, Research Hospital, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Takaaki Konuma
- Division of Hematopoietic Disease Control, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan. .,Department of Hematology/Oncology, Research Hospital, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
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8
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Garcia-Mayea Y, Mir C, Carballo L, Sánchez-García A, Bataller M, LLeonart ME. TSPAN1, a novel tetraspanin member highly involved in carcinogenesis and chemoresistance. Biochim Biophys Acta Rev Cancer 2021; 1877:188674. [PMID: 34979155 DOI: 10.1016/j.bbcan.2021.188674] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 12/11/2022]
Abstract
The tetraspanin (TSPAN) family constitutes a poorly explored family of membrane receptors involved in various physiological processes, with relevant roles in anchoring multiple proteins, acting as scaffolding proteins, and cell signaling. Recent studies have increasingly demonstrated the involvement of TSPANs in cancer. In particular, tetraspanin 1 (also known as TSPAN1, NET-1, TM4C, C4.8 or GEF) has been implicated in cell survival, proliferation and invasion. Recently, our laboratory revealed a key role of TSPAN1 in the acquired resistance of tumor cells to conventional chemotherapy (e.g., cisplatin). In this review, we summarize and discuss the latest research on the physiological mechanisms of TSPANs in cancer and, in particular, on TSPAN1 regulating resistance to chemotherapy. A model of TSPAN1 action is proposed, and the potential of targeting TSPAN1 in anticancer therapeutic strategies is discussed.
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Affiliation(s)
- Yoelsis Garcia-Mayea
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Cristina Mir
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Laia Carballo
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Almudena Sánchez-García
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Marina Bataller
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Matilde E LLeonart
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain; Spanish Biomedical Research Network Center in Oncology, CIBERONC, Spain.
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9
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Quantitative characterization of tetraspanin 8 homointeractions in the plasma membrane. Biochem J 2021; 478:3643-3654. [PMID: 34524408 DOI: 10.1042/bcj20210459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 11/17/2022]
Abstract
The spatial distribution of proteins in cell membranes is crucial for signal transduction, cell communication and membrane trafficking. Members of the Tetraspanin family organize functional protein clusters within the plasma membrane into so-called Tetraspanin-enriched microdomains (TEMs). Direct interactions between Tetraspanins are believed to be important for this organization. However, studies thus far have utilized mainly co-immunoprecipitation methods that cannot distinguish between direct and indirect, through common partners, interactions. Here we study Tetraspanin 8 homointeractions in living cells via quantitative fluorescence microscopy. We demonstrate that Tetraspanin 8 exists in a monomer-dimer equilibrium in the plasma membrane. Tetraspanin 8 dimerization is described by a high dissociation constant (Kd = 14 700 ± 1100 Tspan8/µm2), one of the highest dissociation constants measured for membrane proteins in live cells. We propose that this high dissociation constant, and thus the short lifetime of the Tetraspanin 8 dimer, is critical for Tetraspanin 8 functioning as a master regulator of cell signaling.
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10
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Sun G, Chen J, Ding Y, Wren JD, Xu F, Lu L, Wang Y, Wang DW, Zhang XA. A Bioinformatics Perspective on the Links Between Tetraspanin-Enriched Microdomains and Cardiovascular Pathophysiology. Front Cardiovasc Med 2021; 8:630471. [PMID: 33860000 PMCID: PMC8042132 DOI: 10.3389/fcvm.2021.630471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/15/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Tetraspanins and integrins are integral membrane proteins. Tetraspanins interact with integrins to modulate the dynamics of adhesion, migration, proliferation, and signaling in the form of membrane domains called tetraspanin-enriched microdomains (TEMs). TEMs also contain other cell adhesion proteins like immunoglobulin superfamily (IgSF) proteins and claudins. Cardiovascular functions of these TEM proteins have emerged and remain to be further revealed. Objectives: The aims of this study are to explore the roles of these TEM proteins in the cardiovascular system using bioinformatics tools and databases and to highlight the TEM proteins that may functionally associate with cardiovascular physiology and pathology. Methods: For human samples, three databases-GTEx, NCBI-dbGaP, and NCBI-GEO-were used for the analyses. The dbGaP database was used for GWAS analysis to determine the association between target genes and human phenotypes. GEO is an NCBI public repository that archives genomics data. GTEx was used for the analyses of tissue-specific mRNA expression levels and eQTL. For murine samples, GeneNetwork was used to find gene-phenotype correlations and gene-gene correlations of expression levels in mice. The analysis of cardiovascular data was the focus of this study. Results: Some integrins and tetraspanins, such as ITGA8 and Cd151, are highly expressed in the human cardiovascular system. TEM components are associated with multiple cardiovascular pathophysiological events in humans. GWAS and GEO analyses showed that human Cd82 and ITGA9 are associated with blood pressure. Data from mice also suggest that various cardiovascular phenotypes are correlated with integrins and tetraspanins. For instance, Cd82 and ITGA9, again, have correlations with blood pressure in mice. Conclusion: ITGA9 is related to blood pressure in both species. KEGG analysis also linked ITGA9 to metabolism and MAPK signaling pathway. This work provides an example of using integrated bioinformatics approaches across different species to identify the connections of structurally and/or functionally related molecules to certain categories of diseases.
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Affiliation(s)
- Ge Sun
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Junxiong Chen
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Yingjun Ding
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Jonathan D. Wren
- Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Fuyi Xu
- University of Tennessee Health Science Center, Memphis, TN, United States
| | - Lu Lu
- University of Tennessee Health Science Center, Memphis, TN, United States
| | - Yan Wang
- Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Dao-wen Wang
- Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Xin A. Zhang
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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11
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Synapse type-specific proteomic dissection identifies IgSF8 as a hippocampal CA3 microcircuit organizer. Nat Commun 2020; 11:5171. [PMID: 33057002 PMCID: PMC7560607 DOI: 10.1038/s41467-020-18956-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 09/23/2020] [Indexed: 12/20/2022] Open
Abstract
Excitatory and inhibitory neurons are connected into microcircuits that generate circuit output. Central in the hippocampal CA3 microcircuit is the mossy fiber (MF) synapse, which provides powerful direct excitatory input and indirect feedforward inhibition to CA3 pyramidal neurons. Here, we dissect its cell-surface protein (CSP) composition to discover novel regulators of MF synaptic connectivity. Proteomic profiling of isolated MF synaptosomes uncovers a rich CSP composition, including many CSPs without synaptic function and several that are uncharacterized. Cell-surface interactome screening identifies IgSF8 as a neuronal receptor enriched in the MF pathway. Presynaptic Igsf8 deletion impairs MF synaptic architecture and robustly decreases the density of bouton filopodia that provide feedforward inhibition. Consequently, IgSF8 loss impairs excitation/inhibition balance and increases excitability of CA3 pyramidal neurons. Our results provide insight into the CSP landscape and interactome of a specific excitatory synapse and reveal IgSF8 as a critical regulator of CA3 microcircuit connectivity and function. Mossy fiber synapses are key in CA3 microcircuit function. Here, the authors profile the mossy fiber synapse proteome and cell-surface interactome. They uncover a diverse repertoire of cell-surface proteins and identify the receptor IgSF8 as a regulator of CA3 microcircuit connectivity and function.
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12
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Umeda R, Satouh Y, Takemoto M, Nakada-Nakura Y, Liu K, Yokoyama T, Shirouzu M, Iwata S, Nomura N, Sato K, Ikawa M, Nishizawa T, Nureki O. Structural insights into tetraspanin CD9 function. Nat Commun 2020; 11:1606. [PMID: 32231207 PMCID: PMC7105497 DOI: 10.1038/s41467-020-15459-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 03/06/2020] [Indexed: 01/16/2023] Open
Abstract
Tetraspanins play critical roles in various physiological processes, ranging from cell adhesion to virus infection. The members of the tetraspanin family have four membrane-spanning domains and short and large extracellular loops, and associate with a broad range of other functional proteins to exert cellular functions. Here we report the crystal structure of CD9 and the cryo-electron microscopic structure of CD9 in complex with its single membrane-spanning partner protein, EWI-2. The reversed cone-like molecular shape of CD9 generates membrane curvature in the crystalline lipid layers, which explains the CD9 localization in regions with high membrane curvature and its implications in membrane remodeling. The molecular interaction between CD9 and EWI-2 is mainly mediated through the small residues in the transmembrane region and protein/lipid interactions, whereas the fertilization assay revealed the critical involvement of the LEL region in the sperm-egg fusion, indicating the different dependency of each binding domain for other partner proteins. Tetraspanins play critical roles in various physiological processes, ranging from cell adhesion to virus infection. Here authors report the crystal structure of CD9 and the cryo-electron microscopic structure of CD9 in complex with its single membrane-spanning partner protein, EWI-2.
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Affiliation(s)
- Rie Umeda
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yuhkoh Satouh
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi, 371-8512, Japan.,Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, Japan
| | - Mizuki Takemoto
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.,Preferred Networks, Inc., Bunkyo-ku, Tokyo, Japan
| | - Yoshiko Nakada-Nakura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kehong Liu
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takeshi Yokoyama
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Mikako Shirouzu
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi, 371-8512, Japan.,Gunma University Initiative for Advanced Research (GIAR), Gunma University, Maebashi, 371-8512, Japan
| | - Masahito Ikawa
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. .,Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology, Bunkyo-ku, Tokyo, Japan.
| | - Osamu Nureki
- Department of Biological Sciences Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
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13
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Zhang J, Wu T, Zhan S, Qiao N, Zhang X, Zhu Y, Yang N, Sun Y, Zhang XA, Bleich D, Han X. TIMP-1 and CD82, a promising combined evaluation marker for PDAC. Oncotarget 2018; 8:6496-6512. [PMID: 28030805 PMCID: PMC5351648 DOI: 10.18632/oncotarget.14133] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 11/11/2016] [Indexed: 11/25/2022] Open
Abstract
Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a widely secreted protein that regulates cell motility, proliferation, and apoptosis. Although it is recognized that TIMP-1-tetraspanin CD63 regulates epithelial cell apoptosis and proliferation, how TIMP-1 controls cell motility is not well understood. In this study, we identify tetraspanin CD82 (also called KAI1) as a component of the promiscuous TIMP-1 interacting protein complex on cell surface of human pancreatic adenocarcinoma cells. CD82 directly binds to TIMP-1 N-terminal region through its large extracellular loop and co-localizes with TIMP-1 in both cancer cell lines and clinical samples. Moreover, CD82 facilitates membrane-bound TIMP-1 endocytosis, which significantly contributes to the anti-migration effect of TIMP-1. CD82 silencing partially eliminates these functions. TIMP-1 and CD82 expression status in patients with pancreatic ductal adenocarcinoma (PDAC) might demonstrate future usefulness as a differentiation marker and give us new insight into tumorigenic metastatic potential.
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Affiliation(s)
- Jiexin Zhang
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Tijun Wu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Shanshan Zhan
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Nan Qiao
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Xu Zhang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Yunxia Zhu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Nan Yang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Yujie Sun
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Xin A Zhang
- Stephenson Cancer Center and Department of Physiology, University of Oklahoma Health Science Center, Oklahoma, OK, USA
| | - David Bleich
- Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Xiao Han
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
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14
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Fitter S, Gronthos S, Ooi SS, Zannettino AC. The Mesenchymal Precursor Cell Marker Antibody STRO-1 Binds to Cell Surface Heat Shock Cognate 70. Stem Cells 2017; 35:940-951. [DOI: 10.1002/stem.2560] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/25/2016] [Accepted: 12/02/2016] [Indexed: 01/07/2023]
Affiliation(s)
- Stephen Fitter
- Myeloma Research Laboratory, Faculty of Health and Medical Science, Adelaide Medical School
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
| | - Stan Gronthos
- Mesenchymal Stem Cell Laboratory, Faculty of Health and Medical Sciences, Adelaide Medical School, University of Adelaide; Adelaide South Australia Australia
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
| | - Soo Siang Ooi
- Myeloma Research Laboratory, Faculty of Health and Medical Science, Adelaide Medical School
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
| | - Andrew C.W. Zannettino
- Myeloma Research Laboratory, Faculty of Health and Medical Science, Adelaide Medical School
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
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15
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EWI-2 negatively regulates TGF-β signaling leading to altered melanoma growth and metastasis. Cell Res 2015; 25:370-85. [PMID: 25656846 DOI: 10.1038/cr.2015.17] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 09/24/2014] [Accepted: 11/07/2014] [Indexed: 01/02/2023] Open
Abstract
In normal melanocytes, TGF-β signaling has a cytostatic effect. However, in primary melanoma cells, TGF-β-induced cytostasis is diminished, thus allowing melanoma growth. Later, a second phase of TGF-β signaling supports melanoma EMT-like changes, invasion and metastasis. In parallel with these "present-absent-present" TGF-β signaling phases, cell surface protein EWI motif-containing protein 2 (EWI-2 or IgSF8) is "absent-present-absent" in melanocytes, primary melanoma, and metastatic melanoma, respectively, suggesting that EWI-2 may serve as a negative regulator of TGF-β signaling. Using melanoma cell lines and melanoma short-term cultures, we performed RNAi and overexpression experiments and found that EWI-2 negatively regulates TGF-β signaling and its downstream events including cytostasis (in vitro and in vivo), EMT-like changes, cell migration, CD271-dependent invasion, and lung metastasis (in vivo). When EWI-2 is present, it associates with cell surface tetraspanin proteins CD9 and CD81 - molecules not previously linked to TGF-β signaling. Indeed, when associated with EWI-2, CD9 and CD81 are sequestered and have no impact on TβR2-TβR1 association or TGF-β signaling. However, when EWI-2 is knocked down, CD9 and CD81 become available to provide critical support for TβR2-TβR1 association, thus markedly elevating TGF-β signaling. Consequently, all of those TGF-β-dependent functions specifically arising due to EWI-2 depletion are reversed by blocking or depleting cell surface tetraspanin proteins CD9 or CD81. These results provide new insights into regulation of TGF-β signaling in melanoma, uncover new roles for tetraspanins CD9 and CD81, and strongly suggest that EWI-2 could serve as a favorable prognosis indicator for melanoma patients.
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16
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Weekes MP, Tomasec P, Huttlin EL, Fielding CA, Nusinow D, Stanton RJ, Wang ECY, Aicheler R, Murrell I, Wilkinson GWG, Lehner PJ, Gygi SP. Quantitative temporal viromics: an approach to investigate host-pathogen interaction. Cell 2014; 157:1460-1472. [PMID: 24906157 PMCID: PMC4048463 DOI: 10.1016/j.cell.2014.04.028] [Citation(s) in RCA: 316] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 02/18/2014] [Accepted: 04/03/2014] [Indexed: 12/11/2022]
Abstract
A systematic quantitative analysis of temporal changes in host and viral proteins throughout the course of a productive infection could provide dynamic insights into virus-host interaction. We developed a proteomic technique called “quantitative temporal viromics” (QTV), which employs multiplexed tandem-mass-tag-based mass spectrometry. Human cytomegalovirus (HCMV) is not only an important pathogen but a paradigm of viral immune evasion. QTV detailed how HCMV orchestrates the expression of >8,000 cellular proteins, including 1,200 cell-surface proteins to manipulate signaling pathways and counterintrinsic, innate, and adaptive immune defenses. QTV predicted natural killer and T cell ligands, as well as 29 viral proteins present at the cell surface, potential therapeutic targets. Temporal profiles of >80% of HCMV canonical genes and 14 noncanonical HCMV open reading frames were defined. QTV is a powerful method that can yield important insights into viral infection and is applicable to any virus with a robust in vitro model. PaperClip
>8,000 proteins quantified over eight time points, including 1,200 cell-surface proteins Temporal profiles of 139/171 canonical HCMV proteins and 14 noncanonical HCMV ORFs Multiple families of cell-surface receptors selectively modulated by HCMV Multiple signaling pathways modulated during HCMV infection
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Affiliation(s)
- Michael P Weekes
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK.
| | - Peter Tomasec
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - Edward L Huttlin
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Ceri A Fielding
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - David Nusinow
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Richard J Stanton
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - Eddie C Y Wang
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - Rebecca Aicheler
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - Isa Murrell
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - Gavin W G Wilkinson
- School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XX, UK
| | - Paul J Lehner
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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17
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Normal muscle regeneration requires tight control of muscle cell fusion by tetraspanins CD9 and CD81. Nat Commun 2013; 4:1674. [PMID: 23575678 DOI: 10.1038/ncomms2675] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 03/01/2013] [Indexed: 12/16/2022] Open
Abstract
Skeletal muscle regeneration after injury follows a remarkable sequence of synchronized events. However, the mechanisms regulating the typical organization of the regenerating muscle at different stages remain largely unknown. Here we show that muscle regeneration in mice lacking either CD9 or CD81 is abnormal and characterized by the formation of discrete giant dystrophic myofibres, which form more quickly in the absence of both tetraspanins. We also show that, in myoblasts, these two tetraspanins associate with the immunoglobulin domain molecule CD9P-1 (EWI-F/FPRP), and that grafting of CD9P-1-depleted myoblasts in regenerating muscles also leads to abnormal regeneration. In vitro myotubes lacking CD9P-1 or both CD9 and CD81 fuse with a higher frequency than normal myotubes. Our study unveils a mechanism preventing inappropriate fusion of myotubes that has an important role in the restitution of normal muscle architecture during muscle regeneration.
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18
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Ma ZB, Li K, Wang J, Guo GH. Role of KAI1/CD82 polymorphisms in colon cancer risk in Han Chinese population. Med Oncol 2013; 30:668. [PMID: 23873015 DOI: 10.1007/s12032-013-0668-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 07/12/2013] [Indexed: 01/29/2023]
Abstract
The aim of this study is to investigate the associations between KAI1/CD82 gene polymorphisms and colorectal cancer (CRC)-risk predisposition. We undertook a case-control study to analyze two KAI1/CD82 polymorphisms (exon 3 -29166 C>T and exon 9 -52840 C>A) in an Han Chinese population, by extraction of genomic DNA from the peripheral blood of 356 patients with CRC and 378 control participants, and performed KAI1/CD82 genotyping using DNA sequencing. The obtained results indicated that overall, no statistically significant association was observed in exon 9 (-52840 C>A). Nevertheless, exon 3 (-29166 C>T) genotype was at increased risk of CRC (P = 0.006; odds ratio = 1.299, CI 95% 1.058-1.549). Furthermore, -29166 T allele CRCs were more significantly common in patients with tumor size of >4 cm than C allele CRC and in cases of poor differentiation and advanced pathological stage. These findings led us to conclude that polymorphism in exon 3 (-29166 C>T) was observed to be associated with susceptibility of CRC. However, exon 9 (-52840 C>A) polymorphism showed no correlation to CRC susceptibility. Nevertheless, further investigation with a larger sample size is needed to support our results.
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Affiliation(s)
- Zhen-Bin Ma
- Department of Gastroenterology, Affiliated Hospital of Binzhou Medical College, No. 661, Yellow-River Second Street, 256600 Binzhou, China.
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Samreen B, Khaliq S, Ashfaq UA, Khan M, Afzal N, Shahzad MA, Riaz S, Jahan S. Hepatitis C virus entry: role of host and viral factors. INFECTION GENETICS AND EVOLUTION 2012; 12:1699-709. [PMID: 22878095 DOI: 10.1016/j.meegid.2012.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 07/13/2012] [Accepted: 07/16/2012] [Indexed: 12/24/2022]
Abstract
Hepatitis C virus (HCV) has been considered to be a significant risk factor in developing liver associated diseases including hepatocellular carcinoma all over the world. HCV is an enveloped positive strand virus comprising a complex between genomic RNA and viral envelope glycoproteins (E1 and E2), which are anchored within host derived double-layered lipid membrane surrounding the nucleocapsid composed of several copies of core protein. HCV cell entry is the first step in infection and viral replication into host cells mainly hepatocytes. HCV cell entry is a complex process involving both the viral (envelope glycoproteins E1/E2) and host factors (cellular receptors and associated factors i.e. CD81, SR-BI, LDL-R, CLDN1, Occludin, DC-SIGN, L-SIGN and Glycosaminoglycans). Besides these the expression of certain other conditions such as polarization and EWI-2 expression inhibits the viral cell entry. Exploring the mechanism of HCV entry will help to better understand the viral life cycle and possible therapeutic targets against HCV infection including viral and host factors involved in this process. New strategies such as RNAi represents a new option for targeting the host or viral factors for prevention and therapeutic against HCV infection. In the current review we try to summarize the current knowledge about mechanism and interaction of cellular and viral factors involved in HCV cell entry and its implication as therapeutic target to inhibit HCV infection.
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Affiliation(s)
- Baila Samreen
- National Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
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20
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Gordón-Alonso M, Sala-Valdés M, Rocha-Perugini V, Pérez-Hernández D, López-Martín S, Ursa A, Alvarez S, Kolesnikova TV, Vázquez J, Sánchez-Madrid F, Yáñez-Mó M. EWI-2 association with α-actinin regulates T cell immune synapses and HIV viral infection. THE JOURNAL OF IMMUNOLOGY 2012; 189:689-700. [PMID: 22689882 DOI: 10.4049/jimmunol.1103708] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
EWI motif-containing protein 2 (EWI-2) is a member of the Ig superfamily that links tetraspanin-enriched microdomains to the actin cytoskeleton. We found that EWI-2 colocalizes with CD3 and CD81 at the central supramolecular activation cluster of the T cell immune synapse. Silencing of the endogenous expression or overexpression of a cytoplasmic truncated mutant of EWI-2 in T cells increases IL-2 secretion upon Ag stimulation. Mass spectrometry experiments of pull-downs with the C-term intracellular domain of EWI-2 revealed the specific association of EWI-2 with the actin-binding protein α-actinin; this association was regulated by PIP2. α-Actinin regulates the immune synapse formation and is required for efficient T cell activation. We extended these observations to virological synapses induced by HIV and found that silencing of either EWI-2 or α-actinin-4 increased cell infectivity. Our data suggest that the EWI-2-α-actinin complex is involved in the regulation of the actin cytoskeleton at T cell immune and virological synapses, providing a link between membrane microdomains and the formation of polarized membrane structures involved in T cell recognition.
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IgSF8: a developmentally and functionally regulated cell adhesion molecule in olfactory sensory neuron axons and synapses. Mol Cell Neurosci 2012; 50:238-49. [PMID: 22687584 DOI: 10.1016/j.mcn.2012.05.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 05/10/2012] [Accepted: 05/28/2012] [Indexed: 01/08/2023] Open
Abstract
Here, we investigated an Immunoglobulin (Ig) superfamily protein IgSF8 which is abundantly expressed in olfactory sensory neuron (OSN) axons and their developing synapses. We demonstrate that expression of IgSF8 within synaptic neuropil is transitory, limited to the period of glomerular formation. Glomerular expression decreases after synaptic maturation and compartmental glomerular organization is achieved, although expression is maintained at high levels within the olfactory nerve layer (ONL). Immunoprecipitations indicate that IgSF8 interacts with tetraspanin CD9 in the olfactory bulb (OB). CD9 is a component of tetraspanin-enriched microdomains (TEMs), specialized microdomains of the plasma membrane known to regulate cell morphology, motility, invasion, fusion and signaling, in both the nervous and immune systems, as well as in tumors. In vitro, both IgSF8 and CD9 localize to puncta within axons and growth cones of OSNs, consistent with TEM localization. When the olfactory epithelium (OE) was lesioned, forcing OSN regeneration en masse, IgSF8 was once again able to be detected in OSN axon terminals as synapses were reestablished. Finally, we halted synaptic maturation within glomeruli by unilaterally blocking functional activity and found that IgSF8 did not undergo exclusion from this subcellular compartment and instead continued to be detected in adult glomeruli. These data support the hypothesis that IgSF8 facilitates OSN synapse formation.
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Tetraspanin-interacting protein IGSF8 is dispensable for mouse fertility. Fertil Steril 2012; 98:465-70. [PMID: 22609062 DOI: 10.1016/j.fertnstert.2012.04.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 04/13/2012] [Accepted: 04/17/2012] [Indexed: 12/27/2022]
Abstract
OBJECTIVE To determine the physiological role of IGSF8 for fertility. DESIGN Experimental prospective study. SETTING Academic basic research laboratory. ANIMAL(S) C57BL/6J and hybrid B6D2F1 mice, as well as Cd9 and Igsf8 knockout mice (C57BL/6J and 129/SvJ mix background), were used for this study. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) In vitro and in vivo fertility tests of Igsf8 knockout mice. RESULT(S) Tetraspanin family member CD9 plays an important role in sperm-egg fusion. Recently, some researchers have reported that CD9 tightly associates with the immunoglobulin superfamily member IGSF8 on the egg surface and that IGSF8 is undetectable on the surface of Cd9-deficient eggs. This led us to hypothesize that IGSF8 participates in sperm-egg fusion together with CD9. To examine the physiological role of IGSF8 in vivo, we generated Igsf8-deficient mice by homologous recombination and examined the fertility of the females. CONCLUSION(S) The Igsf8-deficient female mice showed no fertilization defect in vitro or in vivo. We observed that Igsf8-deficient eggs retained the normal level and localization of CD9, resulting in normal microvilli formation, which indicates that IGSF8 is dispensable in fertility.
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Prostaglandins in cancer cell adhesion, migration, and invasion. Int J Cell Biol 2012; 2012:723419. [PMID: 22505934 PMCID: PMC3299390 DOI: 10.1155/2012/723419] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 10/08/2011] [Indexed: 12/21/2022] Open
Abstract
Prostaglandins exert a profound influence over the adhesive, migratory, and invasive behavior of cells during the development and progression of cancer. Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1) are upregulated in inflammation and cancer. This results in the production of prostaglandin E2 (PGE2), which binds to and activates G-protein-coupled prostaglandin E1–4 receptors (EP1–4). Selectively targeting the COX-2/mPGES-1/PGE2/EP1–4 axis of the prostaglandin pathway can reduce the adhesion, migration, invasion, and angiogenesis. Once stimulated by prostaglandins, cadherin adhesive connections between epithelial or endothelial cells are lost. This enables cells to invade through the underlying basement membrane and extracellular matrix (ECM). Interactions with the ECM are mediated by cell surface integrins by “outside-in signaling” through Src and focal adhesion kinase (FAK) and/or “inside-out signaling” through talins and kindlins. Combining the use of COX-2/mPGES-1/PGE2/EP1–4 axis-targeted molecules with those targeting cell surface adhesion receptors or their downstream signaling molecules may enhance cancer therapy.
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Differential functions of phospholipid binding and palmitoylation of tumour suppressor EWI2/PGRL. Biochem J 2011; 437:399-411. [PMID: 21609323 DOI: 10.1042/bj20101381] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The tumour suppressor EWI2 associates with tetraspanins and regulates tumour cell movement and proliferation. The short cytoplasmic domain of EWI2 is positively charged; five out of the ten residues of this domain are basic. In the present study we demonstrated that the EWI2 cytoplasmic tail interacts specifically with negatively charged PIPs (phosphatidylinositol phosphates), but not with other membrane lipids. The PIPs that interact with EWI2 cytoplasmic tail include PtdIns5P, PtdIns4P, PtdIns3P, PtdIns(3,5)P(2) and PtdIns(3,4)P2. The binding affinity of PIPs to the EWI2 tail, however, is not solely based on charge because PtdIns5P, PtdIns4P and PtdIns3P have a higher affinity to EWI2 than PtdIns(3,5)P(2) and PtdIns(3,4)P(2) do. Mutation of either of two basic residue clusters in the EWI2 cytoplasmic tail abolishes PIP binding, and PIP binding is also determined by the position of basic residues in the EWI2 cytoplasmic tail. In addition, EWI2 is constitutively palmitoylated at the cytoplasmic cysteine residues located at the N-terminal of those basic residues. The PIP interaction is not required for, but appears to regulate, the palmitoylation, whereas palmitoylation is neither required for nor regulates the PIP interaction. Functionally, the PIP interaction regulates the stability of EWI2 proteins, whereas palmitoylation is needed for tetraspanin-EWI2 association and EWI2-dependent inhibition of cell migration and lamellipodia formation. For cell-cell adhesion and cell proliferation, the PIP interaction functions in opposition to the palmitoylation. In conclusion, the EWI2 cytoplasmic tail actively engages with the cell membrane via PIP binding and palmitoylation, which play differential roles in EWI2 functions.
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25
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Wang HX, Kolesnikova TV, Denison C, Gygi SP, Hemler ME. The C-terminal tail of tetraspanin protein CD9 contributes to its function and molecular organization. J Cell Sci 2011; 124:2702-10. [PMID: 21771881 DOI: 10.1242/jcs.085449] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Tetraspanin protein CD9 supports sperm-egg fusion, and regulates cell adhesion, motility, metastasis, proliferation and signaling. The large extracellular loop and transmembrane domains of CD9 engage in functionally important interactions with partner proteins. However, neither functional nor biochemical roles have been shown for the CD9 C-terminal tail, despite it being highly conserved throughout vertebrate species. To gain new insight into the CD9 tail, three C-terminal amino acids (Glu-Met-Val) were replaced with residues corresponding to C-terminal amino acids from tetraspanin protein CD82 (Pro-Lys-Tyr). Wild-type and mutant CD9 were then stably expressed in MOLT-4, K562, U937, RD and HT1080 cells. Whereas wild-type CD9 inhibited cell adhesion and spreading on fibronectin, mutant CD9 did not. Wild-type CD9 also promoted homotypic cell-cell aggregation and microvilli formation, whereas mutant CD9 did not. Protein interactions of wild-type and mutant CD9 were compared quantitatively using stable isotope labeling with amino acids in cell culture (SILAC) in conjunction with liquid-chromatography-tandem mass spectrometry (LC-MS/MS) technology. SILAC results showed that, despite wild-type and mutant CD9 having identical expression levels, mutant CD9 and its major transmembrane interacting partners were recovered in substantially reduced amounts from 1% Brij 96 lysates. Immunoprecipitation experiments confirmed that mutant CD9 recovery was decreased in Brij 96, but not in more stringent Triton X-100 detergent. Additionally, compared with wild-type CD9 complexes, mutant CD9 complexes were larger and more oligomerized in Brij 96 detergent, consistent with decreased Brij 96 solubility, perhaps due to more membrane domains packing more tightly together. In conclusion, multiple CD9 functions depend on its C-terminal tail, which affects the molecular organization of CD9 complexes, as manifested by their altered solubilization in Brij 96 and organization on the cell surface.
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Affiliation(s)
- Hong-Xing Wang
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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Abstract
Among the 33 human tetraspanin proteins, CD151, CD9 and Tspan12 play particularly important roles in cancer. Tetraspanin CD151, in partnership with integrins α6β1 and α6β4, modulates tumour cell growth, invasion, migration, metastasis, signalling and drug sensitivity. Tetraspanin CD9 has suppressor functions in multiple tumour cell types. Major CD9 partner proteins, such as EWI-2 and EWI-F, may modulate these tumour-suppressor functions. Tetraspanin Tspan12 mutations are linked to a human disease called familial exudative vitreoretinopathy. In addition, as a regulator of the metalloprotease ADAM10 (a disintegrin and metalloprotease 10) maturation and function, Tspan12 probably contributes to the pro-tumorigenic functions of ADAM10.
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Abstract
The tetraspanins represent a large superfamily of four-transmembrane proteins that are expressed on all nucleated cells. Tetraspanins play a prominent role in the organization of the plasma membrane by co-ordinating the spatial localization of transmembrane proteins and signalling molecules into 'tetraspanin microdomains'. In immune cells, tetraspanins interact with key leucocyte receptors [including MHC molecules, integrins, CD4/CD8 and the BCR (B-cell receptor) complex] and as such can modulate leucocyte receptor activation and downstream signalling pathways. There is now ample evidence that tetraspanins on B-lymphocytes are important in controlling antibody production. The tetraspanin CD81 interacts with the BCR complex and is critical for CD19 expression and IgG production, whereas the tetraspanin CD37 inhibits IgA production and is important for IgG production. By contrast, the tetraspanins CD9, Tssc6 and CD151 appear dispensable for humoral immune responses. Thus individual tetraspanin family members have specific functions in B-cell biology, which is evidenced by recent studies in tetraspanin-deficient mice and humans. The present review focuses on tetraspanins expressed by B-lymphocytes and discusses novel insights into the function of tetraspanins in the humoral immune response.
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Chen Z, Gu S, Trojanowicz B, Liu N, Zhu G, Dralle H, Hoang-Vu C. Down-regulation of TM4SF is associated with the metastatic potential of gastric carcinoma TM4SF members in gastric carcinoma. World J Surg Oncol 2011; 9:43. [PMID: 21521534 PMCID: PMC3107803 DOI: 10.1186/1477-7819-9-43] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Accepted: 04/27/2011] [Indexed: 12/20/2022] Open
Abstract
Background The aim of this study was to clarify the clinical significance of TM4SF members CD9, CD63 and CD82 in human gastric carcinoma. Methods By employing RT-PCR and immunohistochemistry, we studied the expression of CD9, CD63 and CD82 in 49 paired tissue specimens of normal gastric mucosa and carcinoma. All tissues were obtained from patients who underwent curative surgery. Results All normal gastric epithelium and gastric ulcer tissues strongly expressed transcripts and proteins of CD9, CD63 and CD82 as compared with corresponding controls. We found a significant correlation between CD63 mRNA level and different pM statuses (P = 0.036). Carcinomas in M0 stage revealed a stronger expression of CD63 than carcinomas in M1 stage. Expression of CD9 protein was found significantly stronger in pN0, pM0 than in advanced pN stages (P = 0.03), pM1 (P = 0.013), respectively. We found the relationship between CD63 expression, gender (p = 0.09) and nodal status (p = 0.028), respectively. Additionally, advanced and metastasized tumor tissues revealed significantly down-regulated CD82 protein expression (p = 0.033 and p = 0, respectively), which correlated with the tumor pTNM stage (p = 0.001). Conclusion The reduction of CD9, CD63 and CD82 expression are indicators for the metastatic potential of gastric carcinoma cells. Unlike their expression in other tumor types, the constitutive expression of CD63 may indicate that this factor does play a direct role in human gastric carcinogenesis.
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Affiliation(s)
- Zhouxun Chen
- Department of General Surgery, The first affiliated Hospital of Wenzhou medical School, Wenzhou 325000, Zhejiang, PR, China.
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Abstract
Tetraspanin CD9 is associated with integrin adhesion receptors and it was reported that CD9 regulates integrin-dependent cell migration and invasion. Pro- and anti-migratory effects of CD9 have been linked to adhesion-dependent signalling pathways, including phosphorylation of FAK (focal adhesion kinase) and activation of phosphoinositide 3-kinase, p38 MAPK (mitogen-activated protein kinase) and JNK (c-Jun N-terminal kinase). In the present paper, we describe a novel mechanism whereby CD9 specifically controls localization of talin1, one of the critical regulators of integrin activation, to focal adhesions: CD9-deficiency leads to impaired localization of talin1 to focal adhesions and correlates with increased motility of breast cancer cells.
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30
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Montpellier C, Tews BA, Poitrimole J, Rocha-Perugini V, D'Arienzo V, Potel J, Zhang XA, Rubinstein E, Dubuisson J, Cocquerel L. Interacting regions of CD81 and two of its partners, EWI-2 and EWI-2wint, and their effect on hepatitis C virus infection. J Biol Chem 2011; 286:13954-65. [PMID: 21343309 DOI: 10.1074/jbc.m111.220103] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
CD81 is a tetraspanin protein that is involved in several essential cellular functions, as well as in the hepatitis C virus (HCV) infection. CD81 interacts with a high stoichiometry with its partner proteins EWI-2, EWI-2wint, and EWI-F. These latter proteins modify the functions of CD81 and can thereby potentially inhibit infection or modulate cell migration. Here, we characterized the cleavage of EWI-2 leading to the production of EWI-2wint, which has been shown to inhibit HCV infection. We determined the regions of EWI-2/EWI-2wint and CD81 that are important for their interaction and their functionality. More precisely, we identified a glycine zipper motif in the transmembrane domain of EWI-2/EWI-2wint that is essential for the interaction with CD81. In addition, we found that palmitoylation on two juxtamembranous cysteines in the cytosolic tail of EWI-2/EWI-2wint is required for their interaction with CD81 as well as with CD9, another tetraspanin. Thus, we have shown that palmitoylation of a tetraspanin partner protein can influence the interaction with a tetraspanin. We therefore propose that palmitoylation not only of tetraspanins, but also of their partner proteins is important in regulating the composition of complexes in tetraspanin networks. Finally, we identified the regions in CD81 that are necessary for its functionality in HCV entry and we demonstrated that EWI-2wint needs to interact with CD81 to exert its inhibitory effect on HCV infection.
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Affiliation(s)
- Claire Montpellier
- Center for Infection and Immunity of Lille, Hepatitis C Laboratory, University Lille Nord de France, CNRS UMR8204, INSERM U1019, Pasteur Institute of Lille, 59021 Lille, France
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CD151: Basis Sequence: Mouse. ACTA ACUST UNITED AC 2011; 2011. [PMID: 25983660 DOI: 10.1038/mp.a004123.01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chambrion C, Le Naour F. The tetraspanins CD9 and CD81 regulate CD9P1-induced effects on cell migration. PLoS One 2010; 5:e11219. [PMID: 20574531 PMCID: PMC2888588 DOI: 10.1371/journal.pone.0011219] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 05/20/2010] [Indexed: 12/15/2022] Open
Abstract
CD9P-1 is a cell surface protein with immunoglobulin domains and an unknown function that specifically associates with tetraspanins CD9 and CD81. Overexpression of CD9P-1 in HEK-293 cells induces dramatic changes in cell spreading and migration on various matrices. Experiments using time-lapse videomicroscopy revealed that CD9P-1 expression has led to higher cell motility on collagen I but lower motility on fibronectin through a beta1-integrins dependent mechanism. On collagen I, the increase in cell motility induced by CD9P-1 expression was found to involve integrin alpha2beta1 and CD9P-1 was observed to associate with this collagen receptor. The generation of CD9P-1 mutants demonstrated that the transmembrane and the cytoplasmic domains are necessary for inducing effects on cell motility. On the other hand, expression of tetraspanins CD9 or CD81 was shown to reverse the effects of CD9P-1 on cell motility on collagen I or fibronectin with a concomitant association with CD9P-1. Thus, the ratio of expression levels between CD9P-1 and its tetraspanin partners can regulate cell motility.
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Affiliation(s)
- Célia Chambrion
- Inserm U1004, Villejuif, France
- Univ. Paris-Sud 11, Institut André Lwoff, Villejuif, France
| | - François Le Naour
- Univ. Paris-Sud 11, Institut André Lwoff, Villejuif, France
- Inserm U785, Villejuif, France
- * E-mail:
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Ito C, Yamatoya K, Yoshida K, Maekawa M, Miyado K, Toshimori K. Tetraspanin family protein CD9 in the mouse sperm: unique localization, appearance, behavior and fate during fertilization. Cell Tissue Res 2010; 340:583-94. [PMID: 20428892 DOI: 10.1007/s00441-010-0967-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 03/12/2010] [Indexed: 02/07/2023]
Abstract
A tetraspanin family protein, CD9, has not previously been identified in sperm cells. Here, we characterize sperm CD9 in the mouse, including its unique localization in sperm, appearance during spermatogenesis, and behavior and fate during mouse fertilization. In sperm, CD9 is an inner acrosomal membrane-associated protein, not a plasma membrane-associated protein. Its molecular weight is approximately 24 kDa throughout its processing, from testicular germ cells to acrosome-reacted sperm. A temporal difference was found between mRNA and protein expression; CD9 mRNA was detected in the stages from spermatogonia through round spermatids showing the strongest levels in midpachytene spermatocytes. CD9 protein was detected in the cytoplasm throughout the stages from spermatogonia to spermatocytes. While CD9 was weakly expressed in the spermatids from step 1 through step 14, the signals became clearly positive at the marginal region of the anterior acrosome in elongated spermatids. After the acrosome reaction, the majority of sperm CD9 was retained in the inner acrosomal membrane, but some quantity of CD9 was found on the plasma membrane covering the equatorial segment as detected by immunogold electron microscopy using anti-CD9 antibody. CD9 was maintained on the sperm head after reaching the perivitelline space of CD9-deficient eggs that were recovered after natural mating with wild males. Thus, this study characterizes CD9 in sperm development and fertilization.
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Affiliation(s)
- Chizuru Ito
- Department of Anatomy and Developmental Biology, Chiba University Graduate School of Medicine, Inohana, Chiba, Japan
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34
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Abstract
Despite high expression levels at the plasma membrane or in intracellular vesicles, tetraspanins remain among the most mysterious transmembrane molecules 20 years after their discovery. Several genetic studies in mammals and invertebrates have demonstrated key physiological roles for some of these tetraspanins, in particular in the immune response, sperm-egg fusion, photoreceptor function and the normal function of certain epithelia. Other studies have highlighted their ability to modulate cell migration and metastasis formation. Their role in the propagation of infectious agents has drawn recent attention, with evidence for HIV budding in tetraspanin-enriched plasma membrane domains. Infection of hepatocytic cells by two major pathogens, the hepatitis C virus and the malaria parasite, also requires the tetraspanin CD81. The function of tetraspanins is thought to be linked to their ability to associate with one another and a wealth of other integral proteins, thereby building up an interacting network or 'tetraspanin web'. On the basis of the biochemical dissection of the tetraspanin web and recent analysis of the dynamics of some of its constituents, we propose that tetraspanins tightly regulate transient interactions between a variety of molecules and as such favour the efficient assembly of specialized structures upon proper stimulation.
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35
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Glazar AI, Evans JP. Immunoglobulin superfamily member IgSF8 (EWI-2) and CD9 in fertilisation: evidence of distinct functions for CD9 and a CD9-associated protein in mammalian sperm-egg interaction. Reprod Fertil Dev 2009; 21:293-303. [PMID: 19210920 DOI: 10.1071/rd08158] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 09/29/2008] [Indexed: 11/23/2022] Open
Abstract
On the mouse egg, the tetraspanin CD9 is nearly essential for sperm-egg fusion, with another tetraspanin, CD81, playing a complementary role. Based on what is known about these proteins, egg tetraspanins are likely to be involved in regulation of membrane order through associations with other egg membrane proteins. Here, we identify a first-level interaction (stable in 1% Triton X-100) between CD9 and the immunoglobulin superfamily member IgSF8 (also known as EWI-2), the first evidence in eggs of such an interaction of CD9 with another protein. We also compared the effects of antibody-mediated perturbation of IgSF8 and CD9, evaluating the robustness of these perturbations in IVF conditions that heavily favour fertilisation and those in which fertilisation occurs less frequently. These studies demonstrate that IgSF8 participates in mouse gamete interactions and identify discrete effects of antibody-mediated perturbation of CD9 and IgSF8. An anti-IgSF8 antibody had moderate inhibitory effects on sperm-egg binding, whereas an anti-CD9 antibody significantly inhibited sperm-egg fusion and, in certain assays, had an inhibitory effect on binding as well. The present study highlights the critical importance of design of IVF experiments for the detection of different effects of experimental manipulations on gamete interactions.
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Affiliation(s)
- Amanda I Glazar
- Department of Biochemistry, Division of Reproductive Biology, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolf Street, Baltimore, MD 21205, USA
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36
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Glioblastoma inhibition by cell surface immunoglobulin protein EWI-2, in vitro and in vivo. Neoplasia 2009; 11:77-86, 4p following 86. [PMID: 19107234 DOI: 10.1593/neo.81180] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 10/22/2008] [Accepted: 10/23/2008] [Indexed: 01/28/2023] Open
Abstract
EWI-2, a cell surface IgSF protein, is highly expressed in normal human brain but is considerably diminished in glioblastoma tumors and cell lines. Moreover, loss of EWI-2 expression correlated with a shorter survival time in human glioma patients, suggesting that EWI-2 might be a natural inhibitor of glioblastoma. In support of this idea, EWI-2 expression significantly impaired both ectopic and orthotopic tumor growth in nude mice in vivo. In vitro assays provided clues regarding EWI-2 functions. Expression of EWI-2 in T98G and/or U87-MG malignant glioblastoma cell lines failed to alter two-dimensional cell proliferation but inhibited glioblastoma colony formation in soft agar and caused diminished cell motility and invasion. At the biochemical level, EWI-2 markedly affects the organization of four molecules (tetraspanin proteins CD9 and CD81 and matrix metalloproteinases MMP-2 and MT1-MMP), which play key roles in the biology of astrocytes and gliomas. EWI-2 causes CD9 and CD81 to become more associated with each other, whereas CD81 and other tetraspanins become less associated with MMP-2 and MT1-MMP. We propose that EWI-2 inhibition of glioblastoma growth in vivo is at least partly explained by the capability of EWI-2 to inhibit growth and/or invasion in vitro. Underlying these functional effects, EWI-2 causes a substantial molecular reorganization of multiple molecules (CD81, CD9, MMP-2, and MT1-MMP) known to affect proliferation and/or invasion of astrocytes and/or glioblastomas.
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37
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Hemler ME. Targeting of tetraspanin proteins--potential benefits and strategies. Nat Rev Drug Discov 2009; 7:747-58. [PMID: 18758472 DOI: 10.1038/nrd2659] [Citation(s) in RCA: 253] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The tetraspanin transmembrane proteins have emerged as key players in malignancy, the immune system, during fertilization and infectious disease processes. Tetraspanins engage in a wide range of specific molecular interactions, occurring through the formation of tetraspanin-enriched microdomains (TEMs). TEMs therefore serve as a starting point for understanding how tetraspanins affect cell signalling, adhesion, morphology, motility, fusion and virus infection. An abundance of recent evidence suggests that targeting tetraspanins, for example, by monoclonal antibodies, soluble large-loop proteins or RNAi technology, should be therapeutically beneficial.
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Affiliation(s)
- Martin E Hemler
- Dana-Farber Cancer Institute, 44 Binney Street, Boston, Massachussetts 02115, USA.
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38
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Rocha-Perugini V, Montpellier C, Delgrange D, Wychowski C, Helle F, Pillez A, Drobecq H, Le Naour F, Charrin S, Levy S, Rubinstein E, Dubuisson J, Cocquerel L. The CD81 partner EWI-2wint inhibits hepatitis C virus entry. PLoS One 2008; 3:e1866. [PMID: 18382656 PMCID: PMC2270906 DOI: 10.1371/journal.pone.0001866] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 02/18/2008] [Indexed: 12/13/2022] Open
Abstract
Two to three percent of the world's population is chronically infected with hepatitis C virus (HCV) and thus at risk of developing liver cancer. Although precise mechanisms regulating HCV entry into hepatic cells are still unknown, several cell surface proteins have been identified as entry factors for this virus. Among these molecules, the tetraspanin CD81 is essential for HCV entry. Here, we have identified a partner of CD81, EWI-2wint, which is expressed in several cell lines but not in hepatocytes. Ectopic expression of EWI-2wint in a hepatoma cell line susceptible to HCV infection blocked viral entry by inhibiting the interaction between the HCV envelope glycoproteins and CD81. This finding suggests that, in addition to the presence of specific entry factors in the hepatocytes, the lack of a specific inhibitor can contribute to the hepatotropism of HCV. This is the first example of a pathogen gaining entry into host cells that lack a specific inhibitory factor.
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Affiliation(s)
- Vera Rocha-Perugini
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - Claire Montpellier
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - David Delgrange
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - Czeslaw Wychowski
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - François Helle
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - André Pillez
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - Hervé Drobecq
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
| | - François Le Naour
- INSERM-U602, Institut André-Lwoff, Université Paris XI, Hôpital Paul Brousse, Villejuif, France
| | - Stéphanie Charrin
- INSERM-U602, Institut André-Lwoff, Université Paris XI, Hôpital Paul Brousse, Villejuif, France
| | - Shoshana Levy
- Division of Oncology, Department of Medicine, Stanford University Medical Center, Stanford, California, United States of America
| | - Eric Rubinstein
- INSERM-U602, Institut André-Lwoff, Université Paris XI, Hôpital Paul Brousse, Villejuif, France
| | - Jean Dubuisson
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
- * E-mail: (JD); (LC)
| | - Laurence Cocquerel
- Institut de Biologie de Lille (UMR8161), CNRS, Universités de Lille I et Lille II, Institut Pasteur de Lille, Lille, France
- Division of Oncology, Department of Medicine, Stanford University Medical Center, Stanford, California, United States of America
- * E-mail: (JD); (LC)
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39
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Lazo PA. Functional implications of tetraspanin proteins in cancer biology. Cancer Sci 2007; 98:1666-77. [PMID: 17727684 PMCID: PMC11159418 DOI: 10.1111/j.1349-7006.2007.00584.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 06/30/2007] [Accepted: 07/03/2007] [Indexed: 12/25/2022] Open
Abstract
Human tetraspanin proteins are a group of 33 highly hydrophobic membrane proteins that can form complexes in cholesterol-rich microdomains, distinct from lipid rafts, on the cell surface in a dynamic and reversible way. These complexes are composed of a core of several tetraspanin proteins that organize other membrane proteins such as integrins, human leukocyte antigen (HLA) antigens and some growth factor receptors. Although most tetraspanin proteins have been studied individually, tetraspanin proteins and their complexes can have effects on cellular adhesion and motility, interactions with stroma or affect signaling by growth factors, and for most of them no ligand has been identified. Functionally these proteins have been mostly studied in cells of lymphoid lineage, but they are present in all cell types. Data is also available for some tumors, where some tetraspanins have been identified as metastasis suppressors, but their significance is still not clear. Some of their implications in tumor biology and the areas that deserve further study are outlined.
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Affiliation(s)
- Pedro A Lazo
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, CSIC-Universidad de Salamanca, Salamanca, E-37007, Spain.
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40
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Kettner S, Kalthoff F, Graf P, Priller E, Kricek F, Lindley I, Schweighoffer T. EWI-2/CD316 is an inducible receptor of HSPA8 on human dendritic cells. Mol Cell Biol 2007; 27:7718-26. [PMID: 17785435 PMCID: PMC2169036 DOI: 10.1128/mcb.00180-07] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activation of dendritic cells is marked by changes both on their cell surfaces and in their functions. We define EWI-2/CD316 as an early activation marker of dendritic cells upregulated by Toll-like receptor ligands clearly before CD86 and CD83. By expression cloning, human heat shock protein A8 (HSPA8), a member of the hsp70 family, was identified as the ligand for EWI-2. Soluble EWI-2 bound both to cells expressing HSPA8 and also to immobilized HSPA8 protein. Although heat shock proteins are evolutionarily well conserved, other members of this class, including human hsp60 and mycobacterial hsp65, did not bind to EWI-2. The ligation of EWI-2 enhanced the CCL21/SLC-dependent migration of activated mature dendritic cells but attenuated their antigen-specific stimulatory capacities. Important functions of recently activated dendritic cells are thus critically modulated by the newly discovered HSPA8-EWI-2 interaction.
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Affiliation(s)
- Sandra Kettner
- Novartis Institutes for Biomedical Research Vienna, A-1230 Vienna, Austria
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41
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Kovalenko OV, Yang XH, Hemler ME. A novel cysteine cross-linking method reveals a direct association between claudin-1 and tetraspanin CD9. Mol Cell Proteomics 2007; 6:1855-67. [PMID: 17644758 DOI: 10.1074/mcp.m700183-mcp200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Tetraspanins serve as molecular organizers of multiprotein microdomains in cell membranes. Hence to understand functions of tetraspanin proteins, it is critical to identify laterally interacting partner proteins. Here we used a novel technical approach involving exposure and cross-linking of membrane-proximal cysteines coupled with LC-MS/MS protein identification. In this manner we identified nine potential tetraspanin CD9 partners, including claudin-1. Chemical cross-linking yielded a CD9-claudin-1 heterodimer, thus confirming direct association and adding claudin-1 to the short list of proteins that can directly associate with CD9. Interaction of CD9 (and other tetraspanins) with claudin-1 was supported by subcellular colocalization and was confirmed in multiple cell lines, although other claudins (claudin-2, -3, -4, -5, and -7) associated to a much lesser extent. Moreover claudin-1 was distributed very similarly to CD9 in sucrose gradients and, like CD9, was released from A431 and A549 cells upon cholesterol depletion. These biochemical features of claudin-1 are characteristic of tetraspanin microdomain proteins. Although claudins are major structural components of intercellular tight junctions, CD9-claudin-1 complexes did not reside in tight junctions, and depletion of key tetraspanins (CD9 and CD151) by small interfering RNA had no effect on paracellular permeability. However, tetraspanin depletion did cause a marked decrease in the stability of newly synthesized claudin-1. In conclusion, these results (a) validate a technical approach that appears to be particularly well suited for identifying protein partners directly associated with tetraspanins or with other proteins that contain membrane-proximal cysteines and (b) provide insight into how non-junctional claudins may be regulated in the context of tetraspanin-enriched microdomains.
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Affiliation(s)
- Oleg V Kovalenko
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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42
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Barraud-Lange V, Naud-Barriant N, Bomsel M, Wolf JP, Ziyyat A. Transfer of oocyte membrane fragments to fertilizing spermatozoa. FASEB J 2007; 21:3446-9. [PMID: 17575263 DOI: 10.1096/fj.06-8035hyp] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Several families of molecules are implicated in the membrane fusion process between sperm and oocyte. Among these, CD9 tetraspanin, a membrane-organizing molecule, plays a crucial role, since the fertilizing ability of CD9-/- oocytes is dramatically impaired. CD9 controls alpha6-beta1 integrin relocation involved in the membrane reorganization that occurs on oocyte fertilization but is not expressed on sperm. We report here that, together with several other proteins, the CD9 tetraspanin is transferred from the oocyte to the fertilizing spermatozoa present in the perivitelline space before fertilization. Transfer of CD9 from oocyte to sperm from CD9-/- male mice still occurs. CD9 acquisition by sperm results from a transfer of membrane fragments from the plasma membrane of the oocyte, in a process similar to trogocytosis, the recently described mechanism of intercellular exchange of membrane patches. Acquisition of CD9 by the sperm may be crucial for the membrane reorganization in sperm required for fusion with the oocyte, a process that is similar to the role CD9 plays in oocyte membrane reorganization.
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Affiliation(s)
- Virginie Barraud-Lange
- Université Paris 13, UFR SMBH, Laboratoire de Biologie de la Reproduction, and AP-HP Hôpital Jean Verdier, Bondy, France
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43
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44
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Sala-Valdés M, Ursa A, Charrin S, Rubinstein E, Hemler ME, Sánchez-Madrid F, Yáñez-Mó M. EWI-2 and EWI-F link the tetraspanin web to the actin cytoskeleton through their direct association with ezrin-radixin-moesin proteins. J Biol Chem 2006; 281:19665-75. [PMID: 16690612 DOI: 10.1074/jbc.m602116200] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
EWI-2 and EWI-F, two members of a novel subfamily of Ig proteins, are direct partners of tetraspanins CD9 (Tspan29) and CD81 (Tspan28). These EWI proteins contain a stretch of basic charged amino acids in their cytoplasmic domains that may act as binding sites for actin-linking ezrin-radixin-moesin (ERM) proteins. Confocal microscopy analysis revealed that EWI-2 and EWI-F colocalized with ERM proteins at microspikes and microvilli of adherent cells and at the cellular uropod in polarized migrating leukocytes. Immunoprecipitation studies showed the association of EWI-2 and EWI-F with ERM proteins in vivo. Moreover, pulldown experiments and protein-protein binding assays with glutathione S-transferase fusion proteins containing the cytoplasmic domains of EWI proteins corroborated the strong and direct interaction between ERMs and these proteins. The active role of ERMs was further confirmed by double transfections with the N-terminal domain of moesin, which acts as a dominant negative form of ERMs, and was able to delocalize EWIs from the uropod of polarized leukocytes. In addition, direct association of EWI partner CD81 C-terminal domain with ERMs was also demonstrated. Functionally, silencing of endogenous EWI-2 expression by short interfering RNA in lymphoid CEM cells augmented cell migration, cellular polarity, and increased phosphorylation of ERMs. Hence, EWI proteins, through their direct interaction with ERM proteins, act as linkers to connect tetraspanin-associated microdomains to actin cytoskeleton regulating cell motility and polarity.
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Affiliation(s)
- Mónica Sala-Valdés
- Servicio de Inmunología, Hospital Universitario de La Princesa, UAM, Madrid 28006, Spain
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Yang XH, Kovalenko OV, Kolesnikova TV, Andzelm MM, Rubinstein E, Strominger JL, Hemler ME. Contrasting effects of EWI proteins, integrins, and protein palmitoylation on cell surface CD9 organization. J Biol Chem 2006; 281:12976-85. [PMID: 16537545 DOI: 10.1074/jbc.m510617200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
CD9, a tetraspanin protein, makes crucial contributions to sperm egg fusion, other cellular fusions, epidermal growth factor receptor signaling, cell motility, and tumor suppression. Here we characterize a low affinity anti-CD9 antibody, C9BB, which binds preferentially to homoclustered CD9. Using mAb C9BB as a tool, we show that cell surface CD9 homoclustering is promoted by expression of alpha3beta1 and alpha6beta4 integrins and by palmitoylation of the CD9 and beta4 proteins. Conversely, CD9 is shifted toward heteroclusters upon expression of CD9 partner proteins (EWI-2 and EWI-F) or other tetraspanins, or upon ablation of CD9 palmitoylation. Furthermore, unpalmitoylated CD9 showed enhanced EWI-2 association, thereby demonstrating a previously unappreciated role for tetraspanin palmitoylation, and underscoring how depalmitoylation and EWI-2 association may collaborate to shift CD9 from homo- to heteroclusters. In conclusion, we have used a novel molecular probe (mAb C9BB) to demonstrate the existence of multiple types of CD9 complex on the cell surface. A shift from homo- to heteroclustered CD9 may be functionally significant because the latter was especially obvious on malignant epithelial tumor cells. Hence, because of its specialized properties, C9BB may be more useful than other anti-CD9 antibodies for monitoring CD9 during tumor progression.
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Affiliation(s)
- Xiuwei H Yang
- Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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46
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Abstract
Cell-surface proteins of the tetraspanin family are small, and often hidden by a canopy of tall glycoprotein neighbours in the cell membrane. Consequently, tetraspanins have been understudied and underappreciated, despite their presence on nearly all cell and tissue types. Important new genetic evidence has now emerged, and is bolstered by new insights into the cell biology, signalling and biochemistry of tetraspanins. These new findings provide a framework for better understanding of these mysterious molecules in the regulation of cellular processes, from signalling to motility.
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Affiliation(s)
- Martin E Hemler
- Dana-Farber Cancer Institute and Harvard Medical School, 44 Binney Street, Boston, Massachusetts 02115, USA.
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Abstract
Tetraspanins are evolutionarily conserved membrane proteins that tend to associate laterally with one another and to cluster dynamically with numerous partner proteins in membrane microdomains. Consequently, members of this family are involved in the coordination of intracellular and intercellular processes, including signal transduction; cell proliferation, adhesion, and migration; cell fusion; and host-parasite interactions.
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Affiliation(s)
- Shoshana Levy
- Division of Oncology, Department of Medicine, Stanford University Medical Center, Stanford, CA, USA.
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Wright MD, Moseley GW, van Spriel AB. Tetraspanin microdomains in immune cell signalling and malignant disease. ACTA ACUST UNITED AC 2005; 64:533-42. [PMID: 15496196 DOI: 10.1111/j.1399-0039.2004.00321.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A contemporary goal of researchers in leucocyte signalling has been to uncover how cells physically organize and compartmentalize signalling molecules into efficient, regulated signalling networks. This work has revealed important roles of membrane microdomains that are characterized by their distinctive protein and lipid compositions. Recent studies have demonstrated that besides typical cholesterol- and glycosphingolipid-enriched 'rafts', leucocyte membranes are equipped with a different type of microdomain, made up of tetraspanin proteins. Tetraspanin proteins are involved in the organization of tetraspanin-enriched microdomains by virtue of their capacity to specifically associate with key molecules, including integrins, leucocyte receptors and signalling proteins. The aspects of leucocyte function influenced by tetraspanin microdomains include adhesion, proliferation and antigen presentation. However, the mechanisms by which tetraspanin complexes link to intracellular signalling pathways, are still largely unknown. This review discusses how tetraspanin microdomains might function to regulate signalling in lymphoid and myeloid cells, and how they relate to lipid rafts. In addition, we discuss new insights into the role of tetraspanins in malignant disease.
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Affiliation(s)
- M D Wright
- Leucocyte Membrane Protein Laboratory, Austin Research Institute, Victoria, Australia
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Yang X, Kovalenko OV, Tang W, Claas C, Stipp CS, Hemler ME. Palmitoylation supports assembly and function of integrin-tetraspanin complexes. ACTA ACUST UNITED AC 2005; 167:1231-40. [PMID: 15611341 PMCID: PMC2172609 DOI: 10.1083/jcb.200404100] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
As observed previously, tetraspanin palmitoylation promotes tetraspanin microdomain assembly. Here, we show that palmitoylated integrins (α3, α6, and β4 subunits) and tetraspanins (CD9, CD81, and CD63) coexist in substantially overlapping complexes. Removal of β4 palmitoylation sites markedly impaired cell spreading and signaling through p130Cas on laminin substrate. Also in palmitoylation-deficient β4, secondary associations with tetraspanins (CD9, CD81, and CD63) were diminished and cell surface CD9 clustering was decreased, whereas core α6β4–CD151 complex formation was unaltered. There is also a functional connection between CD9 and β4 integrins, as evidenced by anti-CD9 antibody effects on β4-dependent cell spreading. Notably, β4 palmitoylation neither increased localization into “light membrane” fractions of sucrose gradients nor decreased solubility in nonionic detergents—hence it does not promote lipid raft association. Instead, palmitoylation of β4 (and of the closely associated tetraspanin CD151) promotes CD151–α6β4 incorporation into a network of secondary tetraspanin interactions (with CD9, CD81, CD63, etc.), which provides a novel framework for functional regulation.
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Affiliation(s)
- Xiuwei Yang
- Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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Little KD, Hemler ME, Stipp CS. Dynamic regulation of a GPCR-tetraspanin-G protein complex on intact cells: central role of CD81 in facilitating GPR56-Galpha q/11 association. Mol Biol Cell 2004; 15:2375-87. [PMID: 15004227 PMCID: PMC404030 DOI: 10.1091/mbc.e03-12-0886] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
By means of a variety of intracellular scaffolding proteins, a vast number of heterotrimeric G protein-coupled receptors (GPCRs) may achieve specificity in signaling through a much smaller number of heterotrimeric G proteins. Members of the tetraspanin family organize extensive complexes of cell surface proteins and thus have the potential to act as GPCR scaffolds; however, tetraspanin-GPCR complexes had not previously been described. We now show that a GPCR, GPR56/TM7XN1, and heterotrimeric G protein subunits, Galpha(q), Galpha(11), and Gbeta, associate specifically with tetraspanins and CD81, but not with other tetraspanins. CD9 Complexes of GPR56 with CD9 and CD81 remained intact when fully solubilized and were resistant to cholesterol depletion. Hence they do not depend on detergent-insoluble, raft-like membrane microdomains for stability. A central role for CD81 in promoting or stabilizing a GPR56-CD81-Galpha(q/11) complex was revealed by CD81 immunodepletion and reexpression experiments. Finally, antibody engagement of cell surface CD81 or cell activation with phorbol ester revealed two distinct mechanisms by which GPR56-CD81-Galpha(q/11) complexes can be dynamically regulated. These data reveal a potential role for tetraspanins CD9 and CD81 as GPCR scaffolding proteins.
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Affiliation(s)
- Kevin D Little
- Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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