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Wilhelm CR, Upadhye MA, Eschbacher KL, Karandikar NJ, Boyden AW. Proteolipid Protein-Induced Mouse Model of Multiple Sclerosis Requires B Cell-Mediated Antigen Presentation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 211:944-953. [PMID: 37548478 PMCID: PMC10528642 DOI: 10.4049/jimmunol.2200721] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 07/18/2023] [Indexed: 08/08/2023]
Abstract
The pathogenic role B cells play in multiple sclerosis is underscored by the success of B cell depletion therapies. Yet, it remains unclear how B cells contribute to disease, although it is increasingly accepted that mechanisms beyond Ab production are involved. Better understanding of pathogenic interactions between B cells and autoreactive CD4 T cells will be critical for novel therapeutics. To focus the investigation on B cell:CD4 T cell interactions in vivo and in vitro, we previously developed a B cell-dependent, Ab-independent experimental autoimmune encephalomyelitis (EAE) mouse model driven by a peptide encompassing the extracellular domains of myelin proteolipid protein (PLPECD). In this study, we demonstrate that B cell depletion significantly inhibited PLPECD-induced EAE disease, blunted PLPECD-elicited delayed-type hypersensitivity reactions in vivo, and reduced CD4 T cell activation, proliferation, and proinflammatory cytokine production. Further, PLPECD-reactive CD4 T cells sourced from B cell-depleted donor mice failed to transfer EAE to naive recipients. Importantly, we identified B cell-mediated Ag presentation as the critical mechanism explaining B cell dependence in PLPECD-induced EAE, where bone marrow chimeric mice harboring a B cell-restricted MHC class II deficiency failed to develop EAE. B cells were ultimately observed to restimulate significantly higher Ag-specific proliferation from PLP178-191-reactive CD4 T cells compared with dendritic cells when provided PLPECD peptide in head-to-head cultures. We therefore conclude that PLPECD-induced EAE features a required pathogenic B cell-mediated Ag presentation function, providing for investigable B cell:CD4 T cell interactions in the context of autoimmune demyelinating disease.
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Affiliation(s)
- Connor R. Wilhelm
- Iowa City Veterans Affairs Medical Center
- Department of Pathology Graduate Program, University of Iowa, Iowa City, IA USA
| | - Mohit A. Upadhye
- Iowa City Veterans Affairs Medical Center
- Department of Pathology Graduate Program, University of Iowa, Iowa City, IA USA
| | | | - Nitin J. Karandikar
- Department of Pathology, University of Iowa Carver College of Medicine
- Iowa City Veterans Affairs Medical Center
- Department of Pathology Graduate Program, University of Iowa, Iowa City, IA USA
| | - Alexander W. Boyden
- Department of Pathology, University of Iowa Carver College of Medicine
- Iowa City Veterans Affairs Medical Center
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2
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Melnik BC, Stadler R, Weiskirchen R, Leitzmann C, Schmitz G. Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma. Int J Mol Sci 2023; 24:ijms24076102. [PMID: 37047075 PMCID: PMC10094152 DOI: 10.3390/ijms24076102] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/05/2023] [Accepted: 03/16/2023] [Indexed: 03/29/2023] Open
Abstract
Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.
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3
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A conformational switch in clathrin light chain regulates lattice structure and endocytosis at the plasma membrane of mammalian cells. Nat Commun 2023; 14:732. [PMID: 36759616 PMCID: PMC9911608 DOI: 10.1038/s41467-023-36304-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 01/25/2023] [Indexed: 02/11/2023] Open
Abstract
Conformational changes in endocytic proteins are regulators of clathrin-mediated endocytosis. Three clathrin heavy chains associated with clathrin light chains (CLC) assemble into triskelia that link into a geometric lattice that curves to drive endocytosis. Structural changes in CLC have been shown to regulate triskelia assembly in solution, yet the nature of these changes, and their effects on lattice growth, curvature, and endocytosis in cells are unknown. Here, we develop a new correlative fluorescence resonance energy transfer (FRET) and platinum replica electron microscopy method, named FRET-CLEM. With FRET-CLEM, we measure conformational changes in clathrin at thousands of individual morphologically distinct clathrin-coated structures. We discover that the N-terminus of CLC repositions away from the plasma membrane and triskelia vertex as coats curve. Preventing this conformational switch with chemical tools increases lattice sizes and inhibits endocytosis. Thus, a specific conformational switch in the light chain regulates lattice curvature and endocytosis in mammalian cells.
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Roberts AD, Taraska JW. B cell receptor (BCR) endocytosis. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 194:159-177. [PMID: 36631191 DOI: 10.1016/bs.pmbts.2022.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The B cell receptor (BCR) interacts with foreign antigens to mediate B cell activation and secretion of antibodies. B cell activation begins with initiation of signaling pathways, such as NFAT, NF-κB, and MAPK, and endocytosis of the BCR-antigen complex. Many studies have investigated the signaling pathways associated with BCR activation, and this work has led to significant advances in drug therapies to treat cancer and autoimmune diseases that are linked to aberrant BCR signaling. Less is known, however, about the mechanisms of BCR endocytosis and the role endocytosis plays in B cell pathogenesis. This chapter will review key characteristics of the BCR, including a review of signaling pathways, and endocytic mechanisms associated with the activated BCR. We will also review recent studies investigating the role of BCR endocytosis disease pathogenesis.
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Affiliation(s)
- Aleah D Roberts
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States.
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5
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Pineau J, Moreau H, Duménil AML, Pierobon P. Polarity in immune cells. Curr Top Dev Biol 2023; 154:197-222. [PMID: 37100518 DOI: 10.1016/bs.ctdb.2023.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Immune cells are responsible for pathogen detection and elimination, as well as for signaling to other cells the presence of potential danger. In order to mount an efficient immune response, they need to move and search for a pathogen, interact with other cells, and diversify the population by asymmetric cell division. All these actions are regulated by cell polarity: cell polarity controls cell motility, which is crucial for scanning peripheral tissues to detect pathogens, and recruiting immune cells to sites of infection; immune cells, in particular lymphocytes, communicate with each other by a direct contact called immunological synapse, which entails a global polarization of the cell and plays a role in activating lymphocyte response; finally, immune cells divide asymmetrically from a precursor, generating a diversity of phenotypes and cell types among daughter cells, such as memory and effector cells. This review aims at providing an overview from both biology and physics perspectives of how cell polarity shapes the main immune cell functions.
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Affiliation(s)
- Judith Pineau
- Institut Curie, PSL Research University, INSERM U932, Paris, Cedex, France; Université Paris Cité, Paris, France
| | - Hélène Moreau
- Institut Curie, PSL Research University, INSERM U932, Paris, Cedex, France
| | | | - Paolo Pierobon
- Institut Curie, PSL Research University, INSERM U932, Paris, Cedex, France.
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6
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Wong P, Cina DP, Sherwood KR, Fenninger F, Sapir-Pichhadze R, Polychronakos C, Lan J, Keown PA. Clinical application of immune repertoire sequencing in solid organ transplant. Front Immunol 2023; 14:1100479. [PMID: 36865546 PMCID: PMC9971933 DOI: 10.3389/fimmu.2023.1100479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 01/25/2023] [Indexed: 02/16/2023] Open
Abstract
Background Measurement of T cell receptor (TCR) or B cell receptor (BCR) gene utilization may be valuable in monitoring the dynamic changes in donor-reactive clonal populations following transplantation and enabling adjustment in therapy to avoid the consequences of excess immune suppression or to prevent rejection with contingent graft damage and to indicate the development of tolerance. Objective We performed a review of current literature to examine research in immune repertoire sequencing in organ transplantation and to assess the feasibility of this technology for clinical application in immune monitoring. Methods We searched MEDLINE and PubMed Central for English-language studies published between 2010 and 2021 that examined T cell/B cell repertoire dynamics upon immune activation. Manual filtering of the search results was performed based on relevancy and predefined inclusion criteria. Data were extracted based on study and methodology characteristics. Results Our initial search yielded 1933 articles of which 37 met the inclusion criteria; 16 of these were kidney transplant studies (43%) and 21 were other or general transplantation studies (57%). The predominant method for repertoire characterization was sequencing the CDR3 region of the TCR β chain. Repertoires of transplant recipients were found to have decreased diversity in both rejectors and non-rejectors when compared to healthy controls. Rejectors and those with opportunistic infections were more likely to have clonal expansion in T or B cell populations. Mixed lymphocyte culture followed by TCR sequencing was used in 6 studies to define an alloreactive repertoire and in specialized transplant settings to track tolerance. Conclusion Methodological approaches to immune repertoire sequencing are becoming established and offer considerable potential as a novel clinical tool for pre- and post-transplant immune monitoring.
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Affiliation(s)
- Paaksum Wong
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Davide P Cina
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Karen R Sherwood
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Franz Fenninger
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Ruth Sapir-Pichhadze
- Department of Medicine, Division of Nephrology, McGill University, Montreal, QC, Canada.,Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada
| | - Constantin Polychronakos
- Department of Pediatrics, The Research Institute of the McGill University Health Centre and the Montreal Children's Hospital, Montreal, QC, Canada
| | - James Lan
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Paul A Keown
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
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7
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Matveeva O, Nechipurenko Y, Lagutkin D, Yegorov YE, Kzhyshkowska J. SARS-CoV-2 infection of phagocytic immune cells and COVID-19 pathology: Antibody-dependent as well as independent cell entry. Front Immunol 2022; 13:1050478. [PMID: 36532011 PMCID: PMC9751203 DOI: 10.3389/fimmu.2022.1050478] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/08/2022] [Indexed: 12/05/2022] Open
Abstract
Our review summarizes the evidence that COVID-19 can be complicated by SARS-CoV-2 infection of immune cells. This evidence is widespread and accumulating at an increasing rate. Research teams from around the world, studying primary and established cell cultures, animal models, and analyzing autopsy material from COVID-19 deceased patients, are seeing the same thing, namely that some immune cells are infected or capable of being infected with the virus. Human cells most vulnerable to infection include both professional phagocytes, such as monocytes, macrophages, and dendritic cells, as well as nonprofessional phagocytes, such as B-cells. Convincing evidence has accumulated to suggest that the virus can infect monocytes and macrophages, while data on infection of dendritic cells and B-cells are still scarce. Viral infection of immune cells can occur directly through cell receptors, but it can also be mediated or enhanced by antibodies through the Fc gamma receptors of phagocytic cells. Antibody-dependent enhancement (ADE) most likely occurs during the primary encounter with the pathogen through the first COVID-19 infection rather than during the second encounter, which is characteristic of ADE caused by other viruses. Highly fucosylated antibodies of vaccinees seems to be incapable of causing ADE, whereas afucosylated antibodies of persons with acute primary infection or convalescents are capable. SARS-CoV-2 entry into immune cells can lead to an abortive infection followed by host cell pyroptosis, and a massive inflammatory cascade. This scenario has the most experimental evidence. Other scenarios are also possible, for which the evidence base is not yet as extensive, namely productive infection of immune cells or trans-infection of other non-immune permissive cells. The chance of a latent infection cannot be ruled out either.
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Affiliation(s)
- Olga Matveeva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia,*Correspondence: Olga Matveeva, ; Julia Kzhyshkowska,
| | | | - Denis Lagutkin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia,National Medical Research Center of Phthisiopulmonology and Infectious Diseases under the Ministry of Health of the Russian Federation, Moscow, Russia
| | - Yegor E. Yegorov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Julia Kzhyshkowska
- Institute of Transfusion Medicine and Immunology, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany,German Red Cross Blood Service Baden-Württemberg – Hessen, Mannheim, Germany,Laboratory of Translational Cellular and Molecular Biomedicine, Tomsk State University, Tomsk, Russia,*Correspondence: Olga Matveeva, ; Julia Kzhyshkowska,
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8
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McShane AN, Malinova D. The Ins and Outs of Antigen Uptake in B cells. Front Immunol 2022; 13:892169. [PMID: 35572544 PMCID: PMC9097226 DOI: 10.3389/fimmu.2022.892169] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 11/13/2022] Open
Abstract
A review of our current knowledge of B cell antigen uptake mechanisms, the relevance of these processes to pathology, and outstanding questions in the field. Specific antigens induce B cell activation through the B cell receptor (BCR) which initiates downstream signaling and undergoes endocytosis. While extensive research has shed light on the signaling pathways in health and disease, the endocytic mechanisms remain largely uncharacterized. Given the importance of BCR-antigen internalization for antigen presentation in initiating adaptive immune responses and its role in autoimmunity and malignancy, understanding the molecular mechanisms represents critical, and largely untapped, potential therapeutics. In this review, we discuss recent advancements in our understanding of BCR endocytic mechanisms and the role of the actin cytoskeleton and post-translational modifications in regulating BCR uptake. We discuss dysregulated BCR endocytosis in the context of B cell malignancies and autoimmune disorders. Finally, we pose several outstanding mechanistic questions which will critically advance our understanding of the coordination between BCR endocytosis and B cell activation.
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Affiliation(s)
- Adam Nathan McShane
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Dessislava Malinova
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
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9
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Kramer L, Song HW, Mitchell K, Kartik M, Jain R, Escarra VL, Quiros E, Fu H, Singh A, Roy K. Lipid Membrane‐Based Antigen Presentation to B Cells Using a Fully Synthetic Ex Vivo Germinal Center Model. ADVANCED NANOBIOMED RESEARCH 2022; 2. [DOI: 10.1002/anbr.202100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Liana Kramer
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Hannah W. Song
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Kaiya Mitchell
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Mythili Kartik
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Ritika Jain
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Victoria Lozano Escarra
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Enrique Quiros
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Harrison Fu
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
| | - Ankur Singh
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
- George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology 313 Ferst Dr NW Atlanta GA 30332 USA
- Parker H. Petit Institute for Bioengineering and Bioscience Georgia Institute of Technology 315 Ferst Dr NW Atlanta GA 30332 USA
| | - Krishnendu Roy
- Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Medicine 313 Ferst Dr NW Atlanta GA 30332 USA
- Parker H. Petit Institute for Bioengineering and Bioscience Georgia Institute of Technology 315 Ferst Dr NW Atlanta GA 30332 USA
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10
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Alfonzo-Méndez MA, Sochacki KA, Strub MP, Taraska JW. Dual clathrin and integrin signaling systems regulate growth factor receptor activation. Nat Commun 2022; 13:905. [PMID: 35173166 PMCID: PMC8850434 DOI: 10.1038/s41467-022-28373-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 01/18/2022] [Indexed: 12/20/2022] Open
Abstract
The crosstalk between growth factor and adhesion receptors is key for cell growth and migration. In pathological settings, these receptors are drivers of cancer. Yet, how growth and adhesion signals are spatially organized and integrated is poorly understood. Here we use quantitative fluorescence and electron microscopy to reveal a mechanism where flat clathrin lattices partition and activate growth factor signals via a coordinated response that involves crosstalk between epidermal growth factor receptor (EGFR) and the adhesion receptor β5-integrin. We show that ligand-activated EGFR, Grb2, Src, and β5-integrin are captured by clathrin coated-structures at the plasma membrane. Clathrin structures dramatically grow in response to EGF into large flat plaques and provide a signaling platform that link EGFR and β5-integrin through Src-mediated phosphorylation. Disrupting this EGFR/Src/β5-integrin axis prevents both clathrin plaque growth and dampens receptor signaling. Our study reveals a reciprocal regulation between clathrin lattices and two different receptor systems to coordinate and enhance signaling. These findings have broad implications for the regulation of growth factor signaling, adhesion, and endocytosis.
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Affiliation(s)
- Marco A Alfonzo-Méndez
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Bethesda, MD, 20892, USA
| | - Kem A Sochacki
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Bethesda, MD, 20892, USA
| | - Marie-Paule Strub
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Bethesda, MD, 20892, USA
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Bethesda, MD, 20892, USA.
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11
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Clathrin-mediated endocytosis cooperates with bulk endocytosis to generate vesicles. iScience 2022; 25:103809. [PMID: 35198874 PMCID: PMC8841809 DOI: 10.1016/j.isci.2022.103809] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/02/2021] [Accepted: 01/20/2022] [Indexed: 11/25/2022] Open
Abstract
Clathrin-mediated endocytosis, the most prominent endocytic mode, is thought to be generated primarily from relatively flat patches of the plasma membrane. By employing conventional and platinum replica electron microscopy and super-resolution STED microscopy in neuroendocrine chromaffin cells, we found that large Ω-shaped or dome-shaped plasma membrane invaginations, previously thought of as the precursor of bulk endocytosis, are primary sites for clathrin-coated pit generation after depolarization. Clathrin-coated pits are more densely packed at invaginations rather than flat membranes, suggesting that invaginations are preferred sites for clathrin-coated pit formation, likely because their positive curvature facilitates coated-pit formation. Thus, clathrin-mediated endocytosis closely collaborates with bulk endocytosis to enhance endocytic capacity in active secretory cells. This direct collaboration between two classically independent endocytic pathways is of broad importance given the central role of both clathrin-mediated endocytosis and bulk endocytosis in neurons, endocrine cells, immune cells, and many other cell types throughout the body. Bulk membrane invaginations are primary sites for clathrin-coated pit formation Invaginations are preferred over flat membrane for clathrin-coated pit formation Clathrin-coated vesicle formation from membrane invagination is suggested Clathrin-mediated and bulk endocytosis collaborate to enhance endocytic capacity
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12
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Ghosh D, Jiang W, Mukhopadhyay D, Mellins ED. New insights into B cells as antigen presenting cells. Curr Opin Immunol 2021; 70:129-137. [PMID: 34242927 DOI: 10.1016/j.coi.2021.06.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/07/2021] [Accepted: 06/09/2021] [Indexed: 01/06/2023]
Abstract
In addition to their role as antibody producing cells, B cells make a critical contribution to adaptive immune responses by functioning as professional antigen-presenting cells (APC). Distinctive features of B cells as APC include the expression of the B cell receptor (BCR) for antigen and regulated expression of HLA-DO. Here, we discuss recent progress in investigation of B cells as APC. We start with an update on the canonical MHC class II antigen presentation pathway in B cells and alternative pathways, including generation of extracellular vesicles. Turning to APC function, we highlight the roles of B cells as thymic APC, as APC for T follicular helper (TFH), as APC for CD4 memory T cells and as presenters of idiotypic BCR determinants. We also note recent examples that link B cell Ag-presentation to disease. Emerging evidence indicates that, in addition to unique features of B cells compared to other professional APC, there is appreciable heterogeneity among B cells, arising from, for example, B cell activation state or the microenvironment.
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Affiliation(s)
- Debopam Ghosh
- Department of Pediatrics, Program in Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Wei Jiang
- Department of Pediatrics, Program in Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Dhriti Mukhopadhyay
- Department of Surgery, University of Arizona, Tucson, AZ 85724, USA; Tuba City Regional Health Care, Tuba City, AZ 86045, USA
| | - Elizabeth D Mellins
- Department of Pediatrics, Program in Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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13
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Bhanja A, Rey-Suarez I, Song W, Upadhyaya A. Bidirectional feedback between BCR signaling and actin cytoskeletal dynamics. FEBS J 2021; 289:4430-4446. [PMID: 34124846 PMCID: PMC8669062 DOI: 10.1111/febs.16074] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 05/24/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022]
Abstract
When B cells are exposed to antigens, they use their B-cell receptors (BCRs) to transduce this external signal into internal signaling cascades and uptake antigen, which activate transcriptional programs. Signaling activation requires complex cytoskeletal remodeling initiated by BCR signaling. The actin cytoskeletal remodeling drives B-cell morphological changes, such as spreading, protrusion, contraction, and endocytosis of antigen by mechanical forces, which in turn affect BCR signaling. Therefore, the relationship between the actin cytoskeleton and BCR signaling is a two-way feedback loop. These morphological changes represent the indirect ways by which the actin cytoskeleton regulates BCR signaling. Recent studies using high spatiotemporal resolution microscopy techniques have revealed that actin also can directly influence BCR signaling. Cortical actin networks directly affect BCR mobility, not only during the resting stage by serving as diffusion barriers, but also at the activation stage by altering BCR diffusivity through enhanced actin flow velocities. Furthermore, the actin cytoskeleton, along with myosin, enables B cells to sense the physical properties of its environment and generate and transmit forces through the BCR. Consequently, the actin cytoskeleton modulates the signaling threshold of BCR to antigenic stimulation. This review discusses the latest research on the relationship between BCR signaling and actin remodeling, and the research techniques. Exploration of the role of actin in BCR signaling will expand fundamental understanding of the relationship between cell signaling and the cytoskeleton and the mechanisms underlying cytoskeleton-related immune disorders and cancer.
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Affiliation(s)
- Anshuman Bhanja
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Ivan Rey-Suarez
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA
| | - Wenxia Song
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Arpita Upadhyaya
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA.,Department Physics, University of Maryland, College Park, MD, USA
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14
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Find your coat: Using correlative light and electron microscopy to study intracellular protein coats. Curr Opin Cell Biol 2021; 71:21-28. [PMID: 33684808 DOI: 10.1016/j.ceb.2021.01.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/27/2021] [Accepted: 01/30/2021] [Indexed: 12/14/2022]
Abstract
Protein coats, important for vesicular trafficking in eukaryotic cells, help shape membranes and package cargo. But their dynamic construction cannot be fully understood until the distinct steps of their assembly in their native intracellular context at molecular resolution can be visualized. For this, correlative light and electron microscopy (CLEM) is an essential tool. Here, we discuss how emerging CLEM techniques have been used to study the assembly of protein coats inside cells. We review how current and developing CLEM technologies are poised to answer fundamental questions of protein coat architecture at the nanoscale.
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