1
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Weinelt N, Wächtershäuser KN, Celik G, Jeiler B, Gollin I, Zein L, Smith S, Andrieux G, Das T, Roedig J, Feist L, Rotter B, Boerries M, Pampaloni F, van Wijk SJL. LUBAC-mediated M1 Ub regulates necroptosis by segregating the cellular distribution of active MLKL. Cell Death Dis 2024; 15:77. [PMID: 38245534 PMCID: PMC10799905 DOI: 10.1038/s41419-024-06447-6] [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: 08/10/2023] [Revised: 12/22/2023] [Accepted: 01/05/2024] [Indexed: 01/22/2024]
Abstract
Plasma membrane accumulation of phosphorylated mixed lineage kinase domain-like (MLKL) is a hallmark of necroptosis, leading to membrane rupture and inflammatory cell death. Pro-death functions of MLKL are tightly controlled by several checkpoints, including phosphorylation. Endo- and exocytosis limit MLKL membrane accumulation and counteract necroptosis, but the exact mechanisms remain poorly understood. Here, we identify linear ubiquitin chain assembly complex (LUBAC)-mediated M1 poly-ubiquitination (poly-Ub) as novel checkpoint for necroptosis regulation downstream of activated MLKL in cells of human origin. Loss of LUBAC activity inhibits tumor necrosis factor α (TNFα)-mediated necroptosis, not by affecting necroptotic signaling, but by preventing membrane accumulation of activated MLKL. Finally, we confirm LUBAC-dependent activation of necroptosis in primary human pancreatic organoids. Our findings identify LUBAC as novel regulator of necroptosis which promotes MLKL membrane accumulation in human cells and pioneer primary human organoids to model necroptosis in near-physiological settings.
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Affiliation(s)
- Nadine Weinelt
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Kaja Nicole Wächtershäuser
- Physical Biology Group, Buchmann Institute for Molecular Life Sciences (BMLS), Biological Sciences (IZN), Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438, Frankfurt am Main, Germany
| | - Gulustan Celik
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Birte Jeiler
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Isabelle Gollin
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Laura Zein
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Sonja Smith
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Geoffroy Andrieux
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Tonmoy Das
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Jens Roedig
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Leonard Feist
- GenXPro GmbH, Altenhoeferallee 3, 60438, Frankfurt am Main, Germany
| | - Björn Rotter
- GenXPro GmbH, Altenhoeferallee 3, 60438, Frankfurt am Main, Germany
| | - Melanie Boerries
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
- German Cancer Consortium (DKTK) partner site Freiburg and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Francesco Pampaloni
- Physical Biology Group, Buchmann Institute for Molecular Life Sciences (BMLS), Biological Sciences (IZN), Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438, Frankfurt am Main, Germany
| | - Sjoerd J L van Wijk
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany.
- German Cancer Consortium (DKTK) partner site Frankfurt/Mainz and German Cancer Research Center (DKFZ), Heidelberg, Germany.
- University Cancer Centre Frankfurt (UCT), University Hospital Frankfurt, Goethe-University Frankfurt, Frankfurt, Germany.
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2
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Abstract
T cell activation is initiated by the recognition of specific antigenic peptides and subsequently accomplished by complex signaling cascades. These aspects have been extensively studied for decades as pivotal factors in the establishment of adaptive immunity. However, how receptors or signaling molecules are organized in the resting state prior to encountering antigens has received less attention. Recent advancements in super-resolution microscopy techniques have revealed topographically controlled pre-formed organization of key molecules involved in antigen recognition and signal transduction on microvillar projections of T cells before activation and substantial effort has been dedicated to characterizing the topological structure of resting T cells over the past decade. This review will summarize our current understanding of how key surface receptors are pre-organized on the T-cell plasma membrane and discuss the potential role of these receptors, which are preassembled prior to ligand binding in the early activation events of T cells.
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Affiliation(s)
- Yunmin Jung
- Department of Nano-Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science, Seoul, Republic of Korea
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3
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Guo Z, Liu X, Wang N, Mo P, Shen J, Liu M, Zhang H, Wang P, Zhang Z. Membrane component ergosterol builds a platform for promoting effector secretion and virulence in Magnaporthe oryzae. THE NEW PHYTOLOGIST 2023; 237:930-943. [PMID: 36300785 DOI: 10.1111/nph.18575] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
The plasma membrane (PM) functions as a physical border between the extracellular and cytoplasmic environments that contribute to the interaction between host plants and pathogenic fungi. As a specific sterol constituent in the cell membrane, ergosterol plays a significant role in fungal development. However, the role of ergosterol in the infection of the rice blast fungus Magnaporthe oryzae remains unclear. In this study, we found that a sterol reductase, MoErg4, is involved in ergosterol biosynthesis and the regulation of plasma membrane integrity in M. oryzae. We found that defects in ergosterol biosynthesis disrupt lipid raft formation in the PM and cause an abnormal distribution of the t-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein MoSso1, inhibiting its interaction with the v-SNARE protein MoSnc1. In addition, we found that MoSso1-MoSnc1 interaction is important for biotrophic interface complex development and cytoplasmic effector protein secretion. Our findings suggested that ergosterol-enriched lipid rafts constitute a platform for interactions among various SNARE proteins that are required for the development and pathogenicity of M. oryzae.
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Affiliation(s)
- Ziqian Guo
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xinyu Liu
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Nian Wang
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Pengcheng Mo
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ju Shen
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Muxing Liu
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Haifeng Zhang
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ping Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, 70118, USA
| | - Zhengguang Zhang
- Department of Plant Pathology, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
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4
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Huang Y, Guo Y, Xu Y, Liu F, Dai S. Flotillin-1 promotes EMT of gastric cancer via stabilizing Snail. PeerJ 2022; 10:e13901. [PMID: 35990908 PMCID: PMC9387518 DOI: 10.7717/peerj.13901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/24/2022] [Indexed: 01/19/2023] Open
Abstract
Gastric cancer is one of the most common malignancies worldwide and has been identified as the third leading cause of cancer-related mortality. Flotillin-1 is a lipid raft-associated scaffolding protein and plays an important role in the progression and development of several malignant carcinomas. Flotillin-1 is involved in epithelial-mesenchymal transition (EMT) process of several solid tumors to promote metastasis. However, the detailed characteristics and mechanisms of Flotillin-1 in gastric cancer have rarely been investigated. In this study, we found Flotillin-1 upregulated in gastric cancer, and the high expression of Flotillin-1 correlated with a worse prognosis. The migration and invasion ability of gastric cancer cells was upregulated by overexpressing Flotillin-1. Knockdown of Flotillin-1 inhibits gastric cancer cells metastasis. Flotillin-1 is a key regulator of EMT process and promotes gastric cancer cells metastasis through inducing EMT. Flotillin-1 may interact with a deubiquitinase to inhibit the ubiquitination of Snail in gastric cancer cells to promote EMT process. Our study provides a rationale and potential target for the treatment of gastric cancer.
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Affiliation(s)
- Ying Huang
- The Fifth Hospital of Shijiazhuang, Shijiazhuang, Hebei, China
| | - Yun Guo
- The Fifth Hospital of Shijiazhuang, Shijiazhuang, Hebei, China
| | - Yi Xu
- The Fifth Hospital of Shijiazhuang, Shijiazhuang, Hebei, China
| | - Fei Liu
- Research Center, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Suli Dai
- Research Center, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
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5
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Kumar R, Pereira RS, Niemann J, Azimpour AI, Zanetti C, Karantanou C, Minka W, Minciacchi VR, Kowarz E, Meister M, Godavarthy PS, Maguer-Satta V, Lefort S, Wiercinska E, Bonig H, Marschalek R, Krause DS. The differential role of the lipid raft-associated protein flotillin 2 for progression of myeloid leukemia. Blood Adv 2022; 6:3611-3624. [PMID: 35298613 PMCID: PMC9631564 DOI: 10.1182/bloodadvances.2021005992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 03/08/2022] [Indexed: 11/20/2022] Open
Abstract
Lipid raft-associated proteins play a vital role in membrane-mediated processes. The lipid microdomain-associated protein flotillin 2 (FLOT2), which has a scaffolding function, is involved in polarization, as well as in actin cytoskeletal organization of primitive and mature hematopoietic cells and has been associated with different malignancies. However, its involvement in myeloid leukemias is not well studied. Using murine transplantation models, we show here that the absence of FLOT2 from leukemia-initiating cells (LICs) altered the disease course of BCR-ABL1+ chronic myeloid leukemia (CML), but not of MLL-AF9-driven acute myeloid leukemia (AML). While FLOT2 was required for expression of the adhesion molecule CD44 on both CML- and AML-LIC, a defect in the cytoskeleton, cell polarity, and impaired homing ability of LIC was only observed in FLOT2-deficient BCR-ABL1+ compared with MLL-AF9+ cells. Downstream of CD44, BCR-ABL1 kinase-independent discrepancies were observed regarding expression, localization, and activity of cell division control protein 42 homolog (CDC42) between wild-type (WT) and FLOT2-deficient human CML and AML cells. Inhibition of CDC42 by ML141 impaired the homing of CML LIC and, thereby, CML progression. This suggested that alteration of both CD44 and CDC42 may be causative of impaired CML progression in the absence of FLOT2. In summary, our data suggest a FLOT2-CD44-CDC42 axis, which differentially regulates CML vs AML progression, with deficiency of FLOT2 impairing the development of CML.
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Affiliation(s)
- Rahul Kumar
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Raquel S. Pereira
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Julian Niemann
- Institute of Molecular Medicine, Ulm University, Ulm, Germany
| | - Alexander I. Azimpour
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Costanza Zanetti
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Christina Karantanou
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Wahyu Minka
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Valentina R. Minciacchi
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Eric Kowarz
- Institute of Pharmaceutical Biology, Goethe University, Frankfurt am Main, Germany
| | - Melanie Meister
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Parimala S. Godavarthy
- Department of Internal Medicine II, Hematology, Oncology, Clinical Immunology and Rheumatology, University Hospital Tübingen, Tübingen, Germany
| | | | - Sylvain Lefort
- CRCL, INSERM U1052-CNRS UMR5286, Centre Léon Bérard, Lyon, France
| | - Eliza Wiercinska
- German Red Cross Blood Service Baden-Württemberg-Hessen, Institute Frankfurt, Frankfurt, Germany
| | - Halvard Bonig
- German Red Cross Blood Service Baden-Württemberg-Hessen, Institute Frankfurt, Frankfurt, Germany
- Goethe University, Institute for Transfusion Medicine and Immunohematology, Frankfurt, Germany
- Division of Hematology, Department of Medicine, University of Washington, Seattle, WA
| | - Rolf Marschalek
- Institute of Pharmaceutical Biology, Goethe University, Frankfurt am Main, Germany
| | - Daniela S. Krause
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
- German Red Cross Blood Service Baden-Württemberg-Hessen, Institute Frankfurt, Frankfurt, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- German Cancer Consortium (DKTK), Germany
- Frankfurt Cancer Institute, Frankfurt, Germany; and
- Institute for General Pharmacology and Toxicology, Institute for Biochemistry II, Goethe University, Frankfurt am Main, Germany
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6
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da Silva RAG, Tay WH, Ho FK, Tanoto FR, Chong KKL, Choo PY, Ludwig A, Kline KA. Enterococcus faecalis alters endo-lysosomal trafficking to replicate and persist within mammalian cells. PLoS Pathog 2022; 18:e1010434. [PMID: 35390107 PMCID: PMC9017951 DOI: 10.1371/journal.ppat.1010434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 04/19/2022] [Accepted: 03/10/2022] [Indexed: 12/02/2022] Open
Abstract
Enterococcus faecalis is a frequent opportunistic pathogen of wounds, whose infections are associated with biofilm formation, persistence, and recalcitrance toward treatment. We have previously shown that E. faecalis wound infection persists for at least 7 days. Here we report that viable E. faecalis are present within both immune and non-immune cells at the wound site up to 5 days after infection, raising the prospect that intracellular persistence contributes to chronic E. faecalis infection. Using in vitro keratinocyte and macrophage infection models, we show that E. faecalis becomes internalized and a subpopulation of bacteria can survive and replicate intracellularly. E. faecalis are internalized into keratinocytes primarily via macropinocytosis into single membrane-bound compartments and can persist in late endosomes up to 24 h after infection in the absence of colocalization with the lysosomal protease Cathepsin D or apparent fusion with the lysosome, suggesting that E. faecalis blocks endosomal maturation. Indeed, intracellular E. faecalis infection results in heterotypic intracellular trafficking with partial or absent labelling of E. faecalis-containing compartments with Rab5 and Rab7, small GTPases required for the endosome-lysosome trafficking. In addition, E. faecalis infection results in marked reduction of Rab5 and Rab7 protein levels which may also contribute to attenuated Rab incorporation into E. faecalis-containing compartments. Finally, we demonstrate that intracellular E. faecalis derived from infected keratinocytes are significantly more efficient in reinfecting new keratinocytes. Together, these data suggest that intracellular proliferation of E. faecalis may contribute to its persistence in the face of a robust immune response, providing a primed reservoir of bacteria for subsequent reinfection.
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Affiliation(s)
- Ronni A. G. da Silva
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
- Singapore-MIT Alliance for Research and Technology, Antimicrobial Drug Resistance Interdisciplinary Research Group, Singapore
| | - Wei Hong Tay
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Foo Kiong Ho
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Frederick Reinhart Tanoto
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Kelvin K. L. Chong
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Pei Yi Choo
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Alexander Ludwig
- School of Biological Sciences, Nanyang Technological University, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore
| | - Kimberly A. Kline
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
- Singapore-MIT Alliance for Research and Technology, Antimicrobial Drug Resistance Interdisciplinary Research Group, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore
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7
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Neutrophils lacking ERM proteins polarize and crawl directionally but have decreased adhesion strength. Blood Adv 2021; 4:3559-3571. [PMID: 32761234 DOI: 10.1182/bloodadvances.2020002423] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 06/28/2020] [Indexed: 12/19/2022] Open
Abstract
Ezrin/radixin/moesin (ERM) proteins are adaptors that link the actin cytoskeleton to the cytoplasmic domains of membrane proteins. Leukocytes express mostly moesin with lower levels of ezrin but no radixin. When leukocytes are activated, ERMs are postulated to redistribute membrane proteins from microvilli into uropods during polarization and to transduce signals that influence adhesion and other responses. However, these functions have not been tested in leukocytes lacking all ERMs. We used knockout (KO) mice with neutrophils lacking ezrin, moesin, or both proteins (double knockout [DKO]) to probe how ERMs modulate cell shape, adhesion, and signaling in vitro and in vivo. Surprisingly, chemokine-stimulated DKO neutrophils still polarized and redistributed ERM-binding proteins such as PSGL-1 and CD44 to the uropods. Selectin binding to PSGL-1 on moesin KO or DKO neutrophils activated kinases that enable integrin-dependent slow rolling but not those that generate neutrophil extracellular traps. Flowing neutrophils of all genotypes rolled normally on selectins and, upon chemokine stimulation, arrested on integrin ligands. However, moesin KO and DKO neutrophils exhibited defective integrin outside-in signaling and reduced adhesion strength. In vivo, DKO neutrophils displayed normal directional crawling toward a chemotactic gradient, but premature detachment markedly reduced migration from venules into inflamed tissues. Our results demonstrate that stimulated neutrophils do not require ERMs to polarize or to move membrane proteins into uropods. They also reveal an unexpected contribution of moesin to integrin outside-in signaling and adhesion strengthening.
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Zhao R, Shan Y, Zhou X, Zhang C, Zhao R, Zhao L, Shan B. MicroRNA‑485‑5p suppresses the progression of esophageal squamous cell carcinoma by targeting flotillin‑1 and inhibits the epithelial‑mesenchymal transition. Oncol Rep 2021; 45:93. [PMID: 33846817 PMCID: PMC8047942 DOI: 10.3892/or.2021.8044] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/02/2021] [Indexed: 02/07/2023] Open
Abstract
As esophageal squamous cell carcinoma (ESCC) is one of the most frequently diagnosed cancers in Asia, it is crucial to uncover its underlying molecular mechanisms that support its development and progression. Several articles have reported that microRNA (miR)-485-5p inhibits the malignant phenotype in a number of cancer types, such as lung, gastric and breast cancer, but to the best of our knowledge, its function in ESCC has not been studied in depth until the present study. It is of great significance to probe the regulatory action and underlying mechanism of miR-485-5p in ESCC. In brief, this study identified that miR-485-5p expression in ESCC tissues was significantly lower than that in normal tissues. The decrease in miR-485-5p expression was associated with a larger tumour size and poor histology and stage. The expression of miR-485-5p was relatively high in Eca 109 and TE-1 cells, but relatively low in KYSE 30. The overexpression of miR-485-5p inhibited cell proliferation, migration and invasion in vitro, whereas miR-485-5p knockdown did the opposite. Flotillin-1 (FLOT-1) can facilitate the malignant phenotype in various cancer types. The present study found that in ESCC tissue, the protein expression of FLOT-1 was negatively correlated with miR-485-5p expression. Further experiments showed that miR-485-5p directly targeted the 3′-untranslated region of FLOT-1. The overexpression of miR-485-5p significantly suppressed the mRNA and protein expression levels of FLOT-1, whereas knockdown had the reverse effects. Furthermore, overexpression of miR-485-5p restrained epithelial-mesenchymal metastasis (EMT)-related factors at both the mRNA and protein levels. At the same time, it also inhibited the growth of ESCC and restrained the EMT in vivo. In summary, miR-485-5p was found to be an inhibitor of ESCC and may have potential as a novel target candidate for ESCC treatment.
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Affiliation(s)
- Riyang Zhao
- Research Centre, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
| | - Yanan Shan
- Research Centre, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
| | - Xinliang Zhou
- Department of Oncology, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
| | - Cong Zhang
- Research Centre, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
| | - Ruinian Zhao
- Research Centre, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
| | - Lianmei Zhao
- Research Centre, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
| | - Baoen Shan
- Research Centre, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
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9
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Abstract
Flotillins 1 and 2 are two ubiquitous, highly conserved homologous proteins that assemble to form heterotetramers at the cytoplasmic face of the plasma membrane in cholesterol- and sphingolipid-enriched domains. Flotillin heterotetramers can assemble into large oligomers to form molecular scaffolds that regulate the clustering of at the plasma membrane and activity of several receptors. Moreover, flotillins are upregulated in many invasive carcinomas and also in sarcoma, and this is associated with poor prognosis and metastasis formation. When upregulated, flotillins promote plasma membrane invagination and induce an endocytic pathway that allows the targeting of cargo proteins in the late endosomal compartment in which flotillins accumulate. These late endosomes are not degradative, and participate in the recycling and secretion of protein cargos. The cargos of this Upregulated Flotillin–Induced Trafficking (UFIT) pathway include molecules involved in signaling, adhesion, and extracellular matrix remodeling, thus favoring the acquisition of an invasive cellular behavior leading to metastasis formation. Thus, flotillin presence from the plasma membrane to the late endosomal compartment influences the activity, and even modifies the trafficking and fate of key protein cargos, favoring the development of diseases, for instance tumors. This review summarizes the current knowledge on flotillins and their role in cancer development focusing on their function in cellular membrane remodeling and vesicular trafficking regulation.
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10
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Flotillins: At the Intersection of Protein S-Palmitoylation and Lipid-Mediated Signaling. Int J Mol Sci 2020; 21:ijms21072283. [PMID: 32225034 PMCID: PMC7177705 DOI: 10.3390/ijms21072283] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 02/07/2023] Open
Abstract
Flotillin-1 and flotillin-2 are ubiquitously expressed, membrane-associated proteins involved in multifarious cellular events from cell signaling, endocytosis, and protein trafficking to gene expression. They also contribute to oncogenic signaling. Flotillins bind the cytosolic leaflet of the plasma membrane and endomembranes and, upon hetero-oligomerization, serve as scaffolds facilitating the assembly of multiprotein complexes at the membrane-cytosol interface. Additional functions unique to flotillin-1 have been discovered recently. The membrane-binding of flotillins is regulated by S-palmitoylation and N-myristoylation, hydrophobic interactions involving specific regions of the polypeptide chain and, to some extent, also by their oligomerization. All these factors endow flotillins with an ability to associate with the sphingolipid/cholesterol-rich plasma membrane domains called rafts. In this review, we focus on the critical input of lipids to the regulation of the flotillin association with rafts and thereby to their functioning. In particular, we discuss how the recent developments in the field of protein S-palmitoylation have contributed to the understanding of flotillin1/2-mediated processes, including endocytosis, and of those dependent exclusively on flotillin-1. We also emphasize that flotillins affect directly or indirectly the cellular levels of lipids involved in diverse signaling cascades, including sphingosine-1-phosphate and PI(4,5)P2. The mutual relations between flotillins and distinct lipids are key to the regulation of their involvement in numerous cellular processes.
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11
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Daněk M, Angelini J, Malínská K, Andrejch J, Amlerová Z, Kocourková D, Brouzdová J, Valentová O, Martinec J, Petrášek J. Cell wall contributes to the stability of plasma membrane nanodomain organization of Arabidopsis thaliana FLOTILLIN2 and HYPERSENSITIVE INDUCED REACTION1 proteins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:619-636. [PMID: 31610051 DOI: 10.1111/tpj.14566] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/11/2019] [Accepted: 09/17/2019] [Indexed: 05/24/2023]
Abstract
Current models of plasma membrane (PM) postulate its organization in various nano- and micro-domains with distinct protein and lipid composition. While metazoan PM nanodomains usually display high lateral mobility, the dynamics of plant nanodomains is often highly spatially restricted. Here we have focused on the determination of the PM distribution in nanodomains for Arabidopsis thaliana flotillin (AtFLOT) and hypersensitive induced reaction proteins (AtHIR), previously shown to be involved in response to extracellular stimuli. Using in vivo laser scanning and spinning disc confocal microscopy in Arabidopsis thaliana we present here their nanodomain localization in various epidermal cell types. Fluorescence recovery after photobleaching (FRAP) and kymographic analysis revealed that PM-associated AtFLOTs contain significantly higher immobile fraction than AtHIRs. In addition, much lower immobile fractions have been found in tonoplast pool of AtHIR3. Although members of both groups of proteins were spatially restricted in their PM distribution by corrals co-aligning with microtubules (MTs), pharmacological treatments showed no or very low role of actin and microtubular cytoskeleton for clustering of AtFLOT and AtHIR into nanodomains. Finally, pharmacological alteration of cell wall (CW) synthesis and structure resulted in changes in lateral mobility of AtFLOT2 and AtHIR1. Accordingly, partial enzymatic CW removal increased the overall dynamics as well as individual nanodomain mobility of these two proteins. Such structural links to CW could play an important role in their correct positioning during PM communication with extracellular environment.
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Affiliation(s)
- Michal Daněk
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Praha 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
| | - Jindřiška Angelini
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague 6, Czech Republic
| | - Kateřina Malínská
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Praha 6, Czech Republic
| | - Jan Andrejch
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague 6, Czech Republic
| | - Zuzana Amlerová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague 6, Czech Republic
| | - Daniela Kocourková
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Praha 6, Czech Republic
| | - Jitka Brouzdová
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Praha 6, Czech Republic
| | - Olga Valentová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague 6, Czech Republic
| | - Jan Martinec
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Praha 6, Czech Republic
| | - Jan Petrášek
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Praha 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
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12
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Ficht X, Ruef N, Stolp B, Samson GPB, Moalli F, Page N, Merkler D, Nichols BJ, Diz-Muñoz A, Legler DF, Niggli V, Stein JV. In Vivo Function of the Lipid Raft Protein Flotillin-1 during CD8 + T Cell-Mediated Host Surveillance. THE JOURNAL OF IMMUNOLOGY 2019; 203:2377-2387. [PMID: 31548330 DOI: 10.4049/jimmunol.1900075] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 08/24/2019] [Indexed: 01/12/2023]
Abstract
Flotillin-1 (Flot1) is an evolutionary conserved, ubiquitously expressed lipid raft-associated scaffolding protein. Migration of Flot1-deficient neutrophils is impaired because of a decrease in myosin II-mediated contractility. Flot1 also accumulates in the uropod of polarized T cells, suggesting an analogous role in T cell migration. In this study, we analyzed morphology and migration parameters of murine wild-type and Flot1-/- CD8+ T cells using in vitro assays and intravital two-photon microscopy of lymphoid and nonlymphoid tissues. Flot1-/- CD8+ T cells displayed significant alterations in cell shape and motility parameters in vivo but showed comparable homing to lymphoid organs and intact in vitro migration to chemokines. Furthermore, their clonal expansion and infiltration into nonlymphoid tissues during primary and secondary antiviral immune responses was comparable to wild-type CD8+ T cells. Taken together, Flot1 plays a detectable but unexpectedly minor role for CD8+ T cell behavior under physiological conditions.
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Affiliation(s)
- Xenia Ficht
- Theodor Kocher Institute, University of Bern, 3012 Bern, Switzerland
| | - Nora Ruef
- Department of Oncology, Microbiology and Immunology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Bettina Stolp
- Theodor Kocher Institute, University of Bern, 3012 Bern, Switzerland.,Department for Infectious Diseases, Integrative Virology, Center for Integrative Infectious Disease Research, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Guerric P B Samson
- Biotechnology Institute Thurgau at the University of Konstanz, 8280 Kreuzlingen, Switzerland
| | - Federica Moalli
- Theodor Kocher Institute, University of Bern, 3012 Bern, Switzerland.,Scientific Institute for Research and Healthcare, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Nicolas Page
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland
| | - Doron Merkler
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland
| | - Ben J Nichols
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Alba Diz-Muñoz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; and
| | - Daniel F Legler
- Biotechnology Institute Thurgau at the University of Konstanz, 8280 Kreuzlingen, Switzerland
| | - Verena Niggli
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
| | - Jens V Stein
- Department of Oncology, Microbiology and Immunology, University of Fribourg, 1700 Fribourg, Switzerland;
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Li HT, Ye C, Zhou M, Yang Y, Jin Q, Pan CF. Moxifloxacin suppresses airway inflammation and modulates expression of caveolin-1 and flotillin-1 in airway smooth muscle cells of asthmatic rats. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:469. [PMID: 31700905 DOI: 10.21037/atm.2019.08.43] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Background Moxifloxacin (MXF) possesses anti-inflammatory properties on asthmatic airway smooth muscle cells (ASMCs) beyond their antimicrobial effects, but the mechanisms are still unknown. This study was to investigate effects of MXF on expression of caveolin-1 (Cav-1) and flotillin-1 (FLOT1) in ASMCs in asthmatic rats. Methods ASMCs were collected from the airway and cultured in vitro. Cells from normal rats were treated with normal saline (Group N); cells from asthmatic rats were incubated with normal saline (Group A) or MXF (20 mg/L) (Group M); Cav-1 expression was up-regulated by transferring Cav-1 expressing lentivirus (Group L) and FLOT1 expression down-regulated by using siRNA in cells from asthmatic rats (Group S). The expressions of Cav-1, FLOT1 and p65 NF-κB were measured by Western blotting and quantificational real-time polymerase chain reaction (qRT-PCR), and interleukin-8 (IL-8) and eotaxin contents were measured by enzyme-linked immunosorbent assay (ELISA). Results Compared with normal control, Cav-1 expression significantly decreased in asthmatic groups (P<0.01); MXF up-regulated Cav-1 expression in asthmatic groups (P<0.01). However, compared with normal control, the expression of FLOT1 and p65 NF-κB dramatically increased in asthmatic groups (P<0.01); MXF down-regulated the expression of FLOT1 and p65 NF-κB in asthmatic groups (P<0.01); meanwhile, the expressions of FLOT1 and p65 NF-κB decreased after up-regulation of Cav-1 expression in asthmatic groups (P=0.01). Compared with asthmatic groups, the IL-8 and eotaxin contents significantly decreased in MXF Groups, Cav-1 up-regulation asthmatic groups and FLOT1 down-regulation asthmatic groups (P<0.01). Conclusions MXF can modulate the airway inflammation, upregulate Cav-1 expression, downregulate the expression of FLOT1 and p65 NF-κB in asthmatic rat ASMCs, which may be related to the anti-inflammatory effects of MXF in asthmatic ASMCs.
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Affiliation(s)
- Hui-Ting Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, Tongji University School, Shanghai 200433, China
| | - Cong Ye
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, Tongji University School, Shanghai 200433, China
| | - Min Zhou
- Department of Respiratory Medicine, Shanghai Jinshan Central Hospital, Shanghai 201500, China
| | - Yan Yang
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, Tongji University School, Shanghai 200433, China
| | - Quan Jin
- Department of Respiratory Medicine, Jinshan Hospital, Fudan University, Shanghai 201508, China
| | - Chun-Feng Pan
- Department of Respiratory Medicine, Jinshan Hospital, Fudan University, Shanghai 201508, China
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14
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Dong Z, Cheng F, Yang Y, Zhang F, Chen G, Liu D. Expression and functional analysis of flotillins in Dugesia japonica. Exp Cell Res 2019; 374:76-84. [DOI: 10.1016/j.yexcr.2018.11.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 11/08/2018] [Accepted: 11/13/2018] [Indexed: 12/20/2022]
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15
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Liu XX, Liu WD, Wang L, Zhu B, Shi X, Peng ZX, Zhu HC, Liu XD, Zhong MZ, Xie D, Zeng MS, Ren CP. Roles of flotillins in tumors. J Zhejiang Univ Sci B 2018; 19:171-182. [PMID: 29504311 DOI: 10.1631/jzus.b1700102] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The identification and use of molecular biomarkers have greatly improved the diagnosis and treatment of malignant tumors. However, a much deeper understanding of oncogenic proteins is needed for the benefit to cancer patients. The lipid raft marker proteins, flotillin-1 and flotillin-2, were first found in goldfish retinal ganglion cells during axon regeneration. They have since been found in a variety of cells, mainly on the inner surface of cell membranes, and not only act as a skeleton to provide a platform for protein-protein interactions, but also are involved in signal transduction, nerve regeneration, endocytosis, and lymphocyte activation. Previous studies have shown that flotillins are closely associated with tumor development, invasion, and metastasis. In this article, we review the functions of flotillins in relevant cell processes, their underlying mechanisms of action in a variety of tumors, and their potential applications to tumor molecular diagnosis and targeted therapy.
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Affiliation(s)
- Xu-Xu Liu
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Wei-Dong Liu
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Lei Wang
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Bin Zhu
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Xiao Shi
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Zi-Xuan Peng
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - He-Cheng Zhu
- Changsha Kexin Cancer Hospital, Changsha 410205, China
| | - Xing-Dong Liu
- Changsha Kexin Cancer Hospital, Changsha 410205, China
| | - Mei-Zuo Zhong
- Changsha Kexin Cancer Hospital, Changsha 410205, China
| | - Dan Xie
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China
| | - Mu-Sheng Zeng
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China
| | - Cai-Ping Ren
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
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16
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Guo AY, Liang XJ, Liu RJ, Li XX, Bi W, Zhou LY, Tang CE, Yan A, Chen ZC, Zhang PF. Flotilin-1 promotes the tumorigenicity and progression of malignant phenotype in human lung adenocarcinoma. Cancer Biol Ther 2018; 18:715-722. [PMID: 28825855 DOI: 10.1080/15384047.2017.1360445] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Lung adenocarcinoma (LUAD) accounts for the most common histological subtype of lung cancer which remains the leading cause of cancer death worldwide. The discovery of more sensitive and specific novel target biomarkers for predicting the development and progression of LUAD is imperative. Flotillin-1 (Flot-1) has been reported to have important roles in the progression of several tumor types but not been reported in the progression of LUAD. Here, we demonstrated that the expression of flotillin-1 was upregulated in 5 LUAD cells. Moreover, multiple approaches were used to explore the tumorigenicity of flotillin-1 in LUAD cell lines. The expression levels of flotillin-1 were analyzed by immunoblotting after overexpression and siRNA-based knockdown. Cell proliferation, scratch wound healing, transwell migration and matrigel invasion and xenograft tumor growth assays were used to determine the role of flotillin-1 in LUAD progression. Downregulation of flotillin-1 reversed, whereas upregulation of flotillin-1 enhanced, the malignant phenotype of LUAD cells in vitro. Consistently, cells with flotillin-1 knockdown formed smaller tumors in nude mice than cells transfected with the empty vector. Furthermore, the control group demonstrated significantly more tumorigenic effects compared to the flotillin-1-silenced group in the xenograft model of LUAD. In all, there draws a conclusion that flotillin-1 is a tumorigenic protein that plays an important role in promoting the proliferation and tumorigenicity of LUAD, suggesting that flotillin-1 may represent a novel the therapeutic target to LUAD.
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Affiliation(s)
- Ai Yun Guo
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Xu Jun Liang
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Rui Jie Liu
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Xiao Xiao Li
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Wu Bi
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Liu Ying Zhou
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Can E Tang
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Ang Yan
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Zhu Chu Chen
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Peng Fei Zhang
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
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17
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Abstract
PURPOSE OF REVIEW We review P-selectin glycoprotein ligand-1 (PSGL-1) as a selectin and chemokine-binding adhesion molecule. PSGL-1 is widely studied in neutrophils. Here, we focus on T cells, because PSGL-1 was recently described as a major immunomodulatory molecule during viral infection. PSGL-1 also plays a crucial role in T-cell homeostasis by binding to lymphoid chemokines, and can induce tolerance by enhancing the functions of regulatory T cells. RECENT FINDINGS PSGL-1 was originally described as a leukocyte ligand for P-selectin, but it is actually a ligand for all selectins (P-, L- and E-selectin), binds chemokines, activates integrins and profoundly affects T-cell biology. It has been shown recently that PSGL-1 can modulate T cells during viral infection by acting as a negative regulator for T-cell functions. Absence of PSGL-1 promotes effector CD4 and CD8 T-cell differentiation and prevents T-cell exhaustion. Consistent with this, tumor growth was significantly reduced in PSGL-1-deficient mice because of an enhanced number of effector T cells together with reduced levels of inhibitory receptors that induce T-cell exhaustion. SUMMARY PSGL-1 is the best-studied selectin ligand and has become a posterchild of versatility in leukocyte adhesion, inflammation and immunology. The direct involvement of PSGL-1 in T-cell biology suggests that it might be a drug target. Indeed, PSGL-1 has been tested in some clinical trials and recently, PSGL-1 blockers were proposed as a potential cotherapy in cancer immunotherapy.
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18
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Wu CY, Tsai YY, Chen SY, Lin YP, Shin JW, Wu CC, Yang BC. Interaction of Zap70 and CXCR4 receptor at lamellipodia that determines the directionality during Jurkat T cells chemotaxis. Mol Immunol 2017; 90:245-254. [DOI: 10.1016/j.molimm.2017.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/21/2017] [Accepted: 08/13/2017] [Indexed: 10/19/2022]
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19
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Martins L, Leme AFP, Kantovitz KR, de Luciane Martins EN, Sallum EA, Casati MZ, Nociti FH. Leucine-Rich Amelogenin Peptide (LRAP) Uptake by Cementoblast Requires Flotillin-1 Mediated Endocytosis. J Cell Physiol 2016; 232:556-565. [DOI: 10.1002/jcp.25453] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 06/07/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Luciane Martins
- Division of Periodontics, Department of Prosthodontics and Periodontics; Piracicaba Dental School, University of Campinas-UNICAMP; Piracicaba, Sao Paulo Brazil
| | | | - Kamila Rosamilia Kantovitz
- Department of Pediatric Dentistry, Piracicaba Dental School; University of Campinas-UNICAMP; Piracicaba, Sao Paulo Brazil
| | | | - Enilson Antonio Sallum
- Division of Periodontics, Department of Prosthodontics and Periodontics; Piracicaba Dental School, University of Campinas-UNICAMP; Piracicaba, Sao Paulo Brazil
| | - Márcio Zaffalon Casati
- Division of Periodontics, Department of Prosthodontics and Periodontics; Piracicaba Dental School, University of Campinas-UNICAMP; Piracicaba, Sao Paulo Brazil
| | - Francisco Humberto Nociti
- Division of Periodontics, Department of Prosthodontics and Periodontics; Piracicaba Dental School, University of Campinas-UNICAMP; Piracicaba, Sao Paulo Brazil
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20
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Abstract
Palmitoylated cysteines typically target transmembrane proteins to domains enriched in cholesterol and sphingolipids (lipid rafts). P-selectin glycoprotein ligand-1 (PSGL-1), CD43, and CD44 are O-glycosylated proteins on leukocytes that associate with lipid rafts. During inflammation, they transduce signals by engaging selectins as leukocytes roll in venules, and they move to the raft-enriched uropods of polarized cells upon chemokine stimulation. It is not known how these glycoproteins associate with lipid rafts or whether this association is required for signaling or for translocation to uropods. Here, we found that loss of core 1-derived O-glycans in murine C1galt1(-/-) neutrophils blocked raft targeting of PSGL-1, CD43, and CD44, but not of other glycosylated proteins, as measured by resistance to solubilization in nonionic detergent and by copatching with a raft-resident sphingolipid on intact cells. Neuraminidase removal of sialic acids from wild-type neutrophils also blocked raft targeting. C1galt1(-/-) neutrophils or neuraminidase-treated neutrophils failed to activate tyrosine kinases when plated on immobilized anti-PSGL-1 or anti-CD44 F(ab')2. Furthermore, C1galt1(-/-) neutrophils incubated with anti-PSGL-1 F(ab')2 did not generate microparticles. In marked contrast, PSGL-1, CD43, and CD44 moved normally to the uropods of chemokine-stimulated C1galt1(-/-) neutrophils. These data define a role for core 1-derived O-glycans and terminal sialic acids in targeting glycoprotein ligands for selectins to lipid rafts of leukocytes. Preassociation of these glycoproteins with rafts is required for signaling but not for movement to uropods.
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21
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Bodin S, Planchon D, Rios Morris E, Comunale F, Gauthier-Rouvière C. Flotillins in intercellular adhesion - from cellular physiology to human diseases. J Cell Sci 2014; 127:5139-47. [PMID: 25413346 DOI: 10.1242/jcs.159764] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Flotillin 1 and 2 are ubiquitous and highly conserved proteins. They were initially discovered in 1997 as being associated with specific caveolin-independent cholesterol- and glycosphingolipid-enriched membrane microdomains and as being expressed during axon regeneration. Flotillins have a role in a large number of physiopathological processes, mainly through their function in membrane receptor clustering and in the regulation of clathrin-independent endocytosis. In this Commentary, we summarize the research performed so far on the role of flotillins in cell-cell adhesion. Recent studies have demonstrated that flotillins directly regulate the formation of cadherin complexes. Indeed, flotillin microdomains are required for the dynamic association and stabilization of cadherins at cell-cell junctions and also for cadherin signaling. Moreover, because flotillins regulate endocytosis and also the actin cytoskeleton, they could have an indirect role in the assembly and stabilization of cadherin complexes. Because it has also recently been shown that flotillins are overexpressed during neurodegenerative diseases and in human cancers, where their upregulation is associated with metastasis formation and poor prognosis, understanding to what extent flotillin upregulation participates in the development of such pathologies is thus of particular interest, as well as how, at the molecular level, it might affect cell adhesion processes.
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Affiliation(s)
- Stéphane Bodin
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Damien Planchon
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Eduardo Rios Morris
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Franck Comunale
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Cécile Gauthier-Rouvière
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
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Meister M, Tikkanen R. Endocytic trafficking of membrane-bound cargo: a flotillin point of view. MEMBRANES 2014; 4:356-71. [PMID: 25019426 PMCID: PMC4194039 DOI: 10.3390/membranes4030356] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 06/28/2014] [Accepted: 07/02/2014] [Indexed: 12/03/2022]
Abstract
The ubiquitous and highly conserved flotillin proteins, flotillin-1 and flotillin-2, have been shown to be involved in various cellular processes such as cell adhesion, signal transduction through receptor tyrosine kinases as well as in cellular trafficking pathways. Due to the fact that flotillins are acylated and form hetero-oligomers, they constitutively associate with cholesterol-enriched lipid microdomains. In recent years, such microdomains have been appreciated as platforms that participate in endocytosis and other cellular trafficking steps. This review summarizes the current findings on the role of flotillins in membrane-bound cargo endocytosis and endosomal trafficking events. We will discuss the proposed function of flotillins in endocytosis in the light of recent findings that point towards a role for flotillins in a step that precedes the actual endocytic uptake of cargo molecules. Recent findings have also revealed that flotillins may be important for endosomal sorting and recycling of specific cargo molecules. In addition to these aspects, the cellular trafficking pathway of flotillins themselves as potential cargo in the context of growth factor signaling will be discussed.
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Affiliation(s)
- Melanie Meister
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
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23
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Flotillins in receptor tyrosine kinase signaling and cancer. Cells 2014; 3:129-49. [PMID: 24709906 PMCID: PMC3980747 DOI: 10.3390/cells3010129] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 02/11/2014] [Accepted: 02/12/2014] [Indexed: 01/23/2023] Open
Abstract
Flotillins are highly conserved proteins that localize into specific cholesterol rich microdomains in cellular membranes. They have been shown to be associated with, for example, various signaling pathways, cell adhesion, membrane trafficking and axonal growth. Recent findings have revealed that flotillins are frequently overexpressed in various types of human cancers. We here review the suggested functions of flotillins during receptor tyrosine kinase signaling and in cancer. Although flotillins have been implicated as putative cancer therapy targets, we here show that great caution is required since flotillin ablation may result in effects that increase instead of decrease the activity of specific signaling pathways. On the other hand, as flotillin overexpression appears to be related with metastasis formation in certain cancers, we also discuss the implications of these findings for future therapy aspects.
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24
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Bitsikas V, Riento K, Howe JD, Barry NP, Nichols BJ. The role of flotillins in regulating aβ production, investigated using flotillin 1-/-, flotillin 2-/- double knockout mice. PLoS One 2014; 9:e85217. [PMID: 24465508 PMCID: PMC3897416 DOI: 10.1371/journal.pone.0085217] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 11/28/2013] [Indexed: 11/18/2022] Open
Abstract
Flotillin 1 and flotillin 2 associate in the plasma membrane to form microdomains that have roles in cell signaling, regulation of cell-cell contacts, membrane-cytoskeletal interactions, and endocytosis. They are thought to be involved in the trafficking and hence processing of the Amyloid Precursor Protein, APP. In this study we set out to obtain in vivo confirmation of a link between flotillins and cleavage of APP to release amyloidogenic Aβ peptide, and to generate tools that would allow us to ask whether flotillins are functionally redundant. We used a mouse model for Aβ-dependent cerebral amyloidosis, APPPS1 mice, combined with deletion of either flotillin 1 singly, or flotillin 1 and flotillin 2 together. There was a small but significant reduction in Aβ levels, and the abundance of congo-red stained plaques, in brains of 12 week old mice lacking flotillin 1. A similar reduction in Aβ levels was observed in the flotillin 1-/-, flotillin 2-/- double knockouts. We did not observe large effects on the clustering or endocytosis of APP in flotillin 1-/- mouse embryonic fibroblasts. We conclude that flotillins are likely to play some role in APP trafficking or processing, but the relevant cellular mechanisms require more investigation. The availability of flotillin 1-/-, flotillin 2-/- mice, which have no overt phenotypes, will facilitate research into flotillin function in vivo.
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Affiliation(s)
- Vassilis Bitsikas
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Kirsi Riento
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Jonathan D. Howe
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Nicholas P. Barry
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Benjamin J. Nichols
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
- * E-mail:
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Niggli V. Insights into the mechanism for dictating polarity in migrating T-cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 312:201-70. [PMID: 25262243 DOI: 10.1016/b978-0-12-800178-3.00007-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review is focused on mechanisms of chemokine-induced polarization of T-lymphocytes. Polarization involves, starting from spherical cells, formation of a morphologically and functionally different rear (uropod) and front (leading edge). This polarization is required for efficient random and directed T-cell migration. The addressed topics concern the specific location of cell organelles and of receptors, signaling molecules, and cytoskeletal proteins in chemokine-stimulated polarized T-cells. In chemokine-stimulated, polarized T-cells, specific proteins, signaling molecules and organelles show enrichment either in the rear, the midzone, or the front; different from the random location in spherical resting cells. Possible mechanisms involved in this asymmetric location will be discussed. A major topic is also the functional role of proteins and cell organelles in T-cell polarization and migration. Specifically, the roles of adhesion and chemokine receptors, cytoskeletal proteins, signaling molecules, scaffolding proteins, and membrane microdomains in these processes will be discussed. The polarity which is established during contact formation of T-cells with antigen-presenting cells is not discussed in detail.
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Affiliation(s)
- Verena Niggli
- Institute of Pathology, University of Bern, Bern, Switzerland.
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26
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Baumann T, Affentranger S, Niggli V. Analysis of close associations of uropod-associated proteins in human T-cells using the proximity ligation assay. PeerJ 2013; 1:e186. [PMID: 24167781 PMCID: PMC3807586 DOI: 10.7717/peerj.186] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 10/02/2013] [Indexed: 01/09/2023] Open
Abstract
We have shown previously that the raft-associated proteins flotillin-1 and -2 are rapidly recruited to the uropods of chemoattractant-stimulated human neutrophils and T-cells and are involved in cell polarization. Other proteins such as the adhesion receptor PSGL-1, the actin-membrane linker proteins ezrin/radixin/moesin (ERM) and the signaling enzyme phosphatidylinositol-4-phosphate 5-kinase type Iγ90 (PIPKIγ90) also accumulate in the T-cell uropod. Using the in situ proximity ligation assay (PLA) we now have investigated putative close associations of these proteins in human freshly isolated T-cells before and after chemokine addition. The PLA allows in situ subcellular localization of close proximity of endogenous proteins at single-molecule resolution in fixed cells. It allows detection also of weaker and transient complexes that would not be revealed with co-immunoprecipitation approaches. We previously provided evidence for heterodimer formation of tagged flotillin-1 and -2 in T-cells before and after chemokine addition using fluorescence resonance energy transfer (FRET). We now confirm these findings using PLA for the endogenous flotillins in fixed human T-cells. Moreover, in agreement with the literature, our PLA findings confirm a close association of endogenous PSGL-1 and ERM proteins both in resting and chemokine-activated human T-cells. In addition, we provide novel evidence using the PLA for close associations of endogenous activated ERM proteins with PIPKIγ90 and of endogenous flotillins with PSGL-1 in human T-cells, before and after chemokine addition. Our findings suggest that preformed clusters of these proteins coalesce in the uropod upon cell stimulation.
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Affiliation(s)
- Tommy Baumann
- Institute of Pathology, University of Bern , Bern , Switzerland
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27
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Guillaume E, Comunale F, Do Khoa N, Planchon D, Bodin S, Gauthier-Rouvière C. Flotillin microdomains stabilize cadherins at cell-cell junctions. J Cell Sci 2013; 126:5293-304. [PMID: 24046456 DOI: 10.1242/jcs.133975] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cadherins are essential in many fundamental processes and assemble at regions of cell-cell contact in large macromolecular complexes named adherens junctions. We have identified flotillin 1 and 2 as new partners of the cadherin complexes. We show that flotillins are localised at cell-cell junctions (CCJs) in a cadherin-dependent manner. Flotillins and cadherins are constitutively associated at the plasma membrane and their colocalisation at CCJ increases with CCJ maturation. Using three-dimensional structured illumination super-resolution microscopy, we found that cadherin and flotillin complexes are associated with F-actin bundles at CCJs. The knockdown of flotillins dramatically affected N- and E-cadherin recruitment at CCJs in mesenchymal and epithelial cell types and perturbed CCJ integrity and functionality. Moreover, we determined that flotillins are required for cadherin association with GM1-containing plasma membrane microdomains. This allows p120 catenin binding to the cadherin complex and its stabilization at CCJs. Altogether, these data demonstrate that flotillin microdomains are required for cadherin stabilization at CCJs and for the formation of functional CCJs.
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Affiliation(s)
- Emilie Guillaume
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
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28
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Mathis L, Wernimont S, Affentranger S, Huttenlocher A, Niggli V. Determinants of phosphatidylinositol-4-phosphate 5-kinase type Iγ90 uropod location in T-lymphocytes and its role in uropod formation. PeerJ 2013; 1:e131. [PMID: 24010013 PMCID: PMC3757496 DOI: 10.7717/peerj.131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 07/25/2013] [Indexed: 12/27/2022] Open
Abstract
We have previously identified phosphatidylinositol-4-phosphate 5-kinase type I (PIPKI)γ90 as a T cell uropod component. However, the molecular determinants and functional consequences of its localization remain unknown. In this report, we seek to better understand the mechanisms involved in PIPKIγ90 uropod targeting and the role that PIPKIγ90 plays in T cell uropod formation. During T cell activation, PIPKIγ90 cocaps with the membrane microdomain-associated proteins flotillin-1 and -2 and accumulates in the uropod. We report that the C-terminal 26 amino acid extension of PIPKIγ90 is required for its localization to the uropod. We further use T cells from PIPKIγ90(-/-) mice and human T cells expressing a kinase-dead PIPKIγ90 mutant to examine the role of PIPKIγ90 in a T cell uropod formation. We find that PIPKIγ90 deficient T cells have elongated uropods on ICAM-1. Moreover, in human T cells overexpression of PIPKIγ87, a naturally occurring isoform lacking the last 26 amino acids, suppresses uropod formation and impairs capping of uropod proteins such as flotillins. Transfection of human T cells with a dominant-negative mutant of flotillin-2 in turn attenuates capping of PIPKIγ90. Our data contribute to the understanding of the molecular mechanisms that regulate T cell uropod formation.
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Affiliation(s)
- Lucia Mathis
- Institute of Pathology, University of Bern, Bern, Switzerland
| | - Sarah Wernimont
- Departments of Medical Microbiology and Immunology and Pediatrics, University of Wisconsin, Madison, WI, United States of America
| | | | - Anna Huttenlocher
- Departments of Medical Microbiology and Immunology and Pediatrics, University of Wisconsin, Madison, WI, United States of America
| | - Verena Niggli
- Institute of Pathology, University of Bern, Bern, Switzerland
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29
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Martinelli S, Chen EJH, Clarke F, Lyck R, Affentranger S, Burkhardt JK, Niggli V. Ezrin/Radixin/Moesin proteins and flotillins cooperate to promote uropod formation in T cells. Front Immunol 2013; 4:84. [PMID: 23579783 PMCID: PMC3619129 DOI: 10.3389/fimmu.2013.00084] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 03/24/2013] [Indexed: 01/13/2023] Open
Abstract
T cell uropods are enriched in specific proteins including adhesion receptors such as P-selectin glycoprotein ligand-1 (PSGL-1), lipid raft-associated proteins such as flotillins and ezrin/radixin/moesin (ERM) proteins which associate with cholesterol-rich raft domains and anchor adhesion receptors to the actin cytoskeleton. Using dominant mutants and siRNA technology we have tested the interactions among these proteins and their role in shaping the T cell uropod. Expression of wild type (WT) ezrin-EGFP failed to affect the morphology of human T cells or chemokine-induced uropod recruitment of PSGL-1 and flotillin-1 and -2. In contrast, expression of constitutively active T567D ezrin-EGFP induced a motile, polarized phenotype in some of the transfected T cells, even in the absence of chemokine. These cells featured F-actin-rich ruffles in the front and uropod enrichment of PSGL-1 and flotillins. T567D ezrin-EGFP was itself strongly enriched in the rear of the polarized T cells. Uropod formation induced by T567D ezrin-EGFP was actin-dependent as it was attenuated by inhibition of Rho-kinase or myosin II, and abolished by disruption of actin filaments. While expression of constitutively active ezrin enhanced cell polarity, expression of a dominant-negative deletion mutant of ezrin, 1-310 ezrin-EGFP, markedly reduced uropod formation induced by the chemokine SDF-1, T cell front-tail polarity, and capping of PSGL-1 and flotillins. Transfection of T cells with WT or T567D ezrin did not affect chemokine-mediated chemotaxis whereas 1-310 ezrin significantly impaired spontaneous 2D migration and chemotaxis. siRNA-mediated downregulation of flotillins in murine T cells attenuated moesin capping and uropod formation, indicating that ERM proteins and flotillins cooperate in uropod formation. In summary, our results indicate that activated ERM proteins function together with flotillins to promote efficient chemotaxis of T cells by structuring the uropod of migrating T cells.
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30
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Kono M, Takagi Y, Kawauchi S, Wada A, Morikawa T, Funakoshi K. Non-activated T and B lymphocytes become morphologically distinguishable after detergent treatment. Cytometry A 2013; 83:396-402. [DOI: 10.1002/cyto.a.22262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 01/10/2013] [Accepted: 01/13/2013] [Indexed: 11/11/2022]
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31
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Baumann T, Affentranger S, Niggli V. Evidence for chemokine-mediated coalescence of preformed flotillin hetero-oligomers in human T-cells. J Biol Chem 2012; 287:39664-72. [PMID: 23012365 DOI: 10.1074/jbc.m112.412742] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that endogenous flotillin-1 and -2, closely related proteins implicated in scaffolding of membrane microdomains, are rapidly recruited to the uropods of chemoattractant-stimulated human neutrophils and T-cells and are involved in cell polarization. Coexpressed flotillin-1 and -2, but not singly expressed proteins, are also targeted to the uropod of T-cells and neutrophils. Biochemical studies suggest formation of flotillin homo- and hetero-oligomers in other cell types, but so far knowledge is lacking on in situ flotillin organization in leukocytes. We have now analyzed flotillin organization in human T-cells using fluorescence resonance energy transfer (FRET). Coexpressed C-terminally tagged flotillin-1-mCherry and flotillin-2-enhanced green fluorescent protein (EGFP) show significant FRET when analyzed in intact human T-cells in the absence and presence of chemokine. In contrast, little FRET was observed between coexpressed flotillin-1-mCherry and flotillin-1-EGFP before or after chemokine addition, indicating predominant formation of heterodimers and/or -oligomers. Interestingly coexpression of untagged flotillin-2 strongly enhanced FRET between differently tagged flotillin-1 molecules in resting and chemokine-stimulated cells, indicating that close contacts of flotillin-1 molecules only occur in flotillin-2-containing hetero-oligomers. Comparable results were obtained for tagged flotillin-2. We further show that disruption of the actin network, depletion of intracellular calcium, and inhibition of phospholipase C all result in suppression of chemokine-induced polarization and flotillin cap formation, but do not abolish FRET between tagged flotillin-1 and -2. Our results support predominant formation of flotillin-1 and -2 hetero-oligomers in resting and chemokine-stimulated human T-cells which may importantly contribute to structuring of the uropod.
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Affiliation(s)
- Tommy Baumann
- Institute of Pathology, University of Bern, Murtenstrasse 31, 3010 Bern, Switzerland
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32
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Andersson ER. The role of endocytosis in activating and regulating signal transduction. Cell Mol Life Sci 2012; 69:1755-71. [PMID: 22113372 PMCID: PMC11114983 DOI: 10.1007/s00018-011-0877-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/23/2011] [Accepted: 10/24/2011] [Indexed: 02/07/2023]
Abstract
Endocytosis is increasingly understood to play crucial roles in most signaling pathways, from determining which signaling components are activated, to how the signal is subsequently transduced and/or terminated. Whether a receptor-ligand complex is internalized via a clathrin-dependent or clathrin-independent endocytic route, and the complexes' subsequent trafficking through specific endocytic compartments, to then be recycled or degraded, has profound effects on signaling output. This review discusses the roles of endocytosis in three markedly different signaling pathways: the Wnt, Notch, and Eph/Ephrin pathways. These offer fundamentally different signaling systems: (1) diffusible ligands inducing signaling in one cell, (2) membrane-tethered ligands inducing signaling in a contacting receptor cell, and (3) bi-directional receptor-ligand signaling in two contacting cells. In each of these systems, endocytosis controls signaling in fascinating ways, and comparison of their similarities and dissimilarities will help to expand our understanding of endocytic control of signal transduction across multiple signaling pathways.
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Affiliation(s)
- Emma R Andersson
- Department of Cell and Molecular Biology, Karolinska Institute, 171 77, Stockholm, Sweden.
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33
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Otto GP, Nichols BJ. The roles of flotillin microdomains--endocytosis and beyond. J Cell Sci 2012; 124:3933-40. [PMID: 22194304 DOI: 10.1242/jcs.092015] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Flotillins are membrane proteins that form microdomains in the plasma membrane of all mammalian cell types studied to date. They span the evolutionary spectrum, with proteins related to flotillins present in bacteria, fungi, plants and metazoans, which suggests that they perform important, and probably conserved, functions. Flotillins have been implicated in myriad processes that include endocytosis, signal transduction and regulation of the cortical cytoskeleton, yet the molecular mechanisms that underlie flotillin function in these different cases are still poorly understood. In this Commentary, we will provide an introduction to these intriguing proteins, summarise their proposed functions and discuss in greater detail some recent insights into the role of flotillin microdomains in endocytosis that have been provided by several independent studies. Finally, we will focus on the questions that are raised by these new experiments and their implications for future studies.
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Affiliation(s)
- Grant P Otto
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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