1
|
Jégouzo SAF, Feinberg H, Morrison AG, Holder A, May A, Huang Z, Jiang L, Lasanajak Y, Smith DF, Werling D, Drickamer K, Weis WI, Taylor ME. CD23 is a glycan-binding receptor in some mammalian species. J Biol Chem 2019; 294:14845-14859. [PMID: 31488546 PMCID: PMC6791321 DOI: 10.1074/jbc.ra119.010572] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 08/30/2019] [Indexed: 01/25/2023] Open
Abstract
CD23, the low-affinity IgE receptor found on B lymphocytes and other cells, contains a C-terminal lectin-like domain that resembles C-type carbohydrate-recognition domains (CRDs) found in many glycan-binding receptors. In most mammalian species, the CD23 residues required to form a sugar-binding site are present, although binding of CD23 to IgE does not involve sugars. Solid-phase binding competition assays, glycoprotein blotting experiments, and glycan array analysis employing the lectin-like domains of cow and mouse CD23 demonstrate that they bind to mannose, GlcNAc, glucose, and fucose and to glycoproteins that bear these sugars in nonreducing terminal positions. Crystal structures of the cow CRD in the presence of α-methyl mannoside and GlcNAcβ1-2Man reveal that a range of oligosaccharide ligands can be accommodated in an open binding site in which most interactions are with a single terminal sugar residue. Although mouse CD23 shows a pattern of monosaccharide and glycoprotein binding similar to cow CD23, the binding is weaker. In contrast, no sugar binding was observed in similar experiments with human CD23. The absence of sugar-binding activity correlates with accumulation of mutations in the gene for CD23 in the primate lineage leading to humans, resulting in loss of key sugar-binding residues. These results are consistent with a role for CD23 in many species as a receptor for potentially pathogenic microorganisms as well as IgE. However, the ability of CD23 to bind several different ligands varies between species, suggesting that it has distinct functions in different organisms.
Collapse
Affiliation(s)
- Sabine A F Jégouzo
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hadar Feinberg
- Departments of Structural Biology and Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305
| | - Andrew G Morrison
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Angela Holder
- Department of Pathobiology and Population Sciences, Royal Veterinary College, North Mymms, Hatfield, Hertfordshire AL9 7TA, United Kingdom
| | - Alisha May
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Zhiyao Huang
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Linghua Jiang
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Yi Lasanajak
- Emory Comprehensive Glycomics Core, Emory University School of Medicine, Atlanta, Georgia 30322
| | - David F Smith
- Emory Comprehensive Glycomics Core, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Dirk Werling
- Department of Pathobiology and Population Sciences, Royal Veterinary College, North Mymms, Hatfield, Hertfordshire AL9 7TA, United Kingdom
| | - Kurt Drickamer
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - William I Weis
- Departments of Structural Biology and Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305
| | - Maureen E Taylor
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| |
Collapse
|
2
|
Stemmer N, Strekalova E, Djogo N, Plöger F, Loers G, Lutz D, Buck F, Michalak M, Schachner M, Kleene R. Generation of amyloid-β is reduced by the interaction of calreticulin with amyloid precursor protein, presenilin and nicastrin. PLoS One 2013; 8:e61299. [PMID: 23585889 PMCID: PMC3621835 DOI: 10.1371/journal.pone.0061299] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 03/11/2013] [Indexed: 12/28/2022] Open
Abstract
Dysregulation of the proteolytic processing of amyloid precursor protein by γ-secretase and the ensuing generation of amyloid-β is associated with the pathogenesis of Alzheimer's disease. Thus, the identification of amyloid precursor protein binding proteins involved in regulating processing of amyloid precursor protein by the γ-secretase complex is essential for understanding the mechanisms underlying the molecular pathology of the disease. We identified calreticulin as novel amyloid precursor protein interaction partner that binds to the γ-secretase cleavage site within amyloid precursor protein and showed that this Ca2+- and N-glycan-independent interaction is mediated by amino acids 330–344 in the C-terminal C-domain of calreticulin. Co-immunoprecipitation confirmed that calreticulin is not only associated with amyloid precursor protein but also with the γ-secretase complex members presenilin and nicastrin. Calreticulin was detected at the cell surface by surface biotinylation of cells overexpressing amyloid precursor protein and was co-localized by immunostaining with amyloid precursor protein and presenilin at the cell surface of hippocampal neurons. The P-domain of calreticulin located between the N-terminal N-domain and the C-domain interacts with presenilin, the catalytic subunit of the γ-secretase complex. The P- and C-domains also interact with nicastrin, another functionally important subunit of this complex. Transfection of amyloid precursor protein overexpressing cells with full-length calreticulin leads to a decrease in amyloid-β42 levels in culture supernatants, while transfection with the P-domain increases amyloid-β40 levels. Similarly, application of the recombinant P- or C-domains and of a synthetic calreticulin peptide comprising amino acid 330–344 to amyloid precursor protein overexpressing cells result in elevated amyloid-β40 and amyloid-β42 levels, respectively. These findings indicate that the interaction of calreticulin with amyloid precursor protein and the γ-secretase complex regulates the proteolytic processing of amyloid precursor protein by the γ-secretase complex, pointing to calreticulin as a potential target for therapy in Alzheimer's disease.
Collapse
Affiliation(s)
- Nina Stemmer
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Elena Strekalova
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Nevena Djogo
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Frank Plöger
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Gabriele Loers
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - David Lutz
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Friedrich Buck
- Institut für Klinische Chemie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Melitta Schachner
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
- Center for Neuroscience, Shantou University Medical College, Shantou, China
- * E-mail:
| | - Ralf Kleene
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| |
Collapse
|
3
|
Kaya H, Gümüş S, Uçar E, Aydoğan M, Muşabak U, Tozkoparan E, Bilgiç H. Response. Chest 2013; 143:274-275. [PMID: 23276862 DOI: 10.1378/chest.12-2249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Affiliation(s)
- Hatice Kaya
- Turkish Armed Forces Rehabilitation Center, Gulhane Military Medical Academy, Ankara, Turkey.
| | - Seyfettin Gümüş
- Department of Pulmonary Medicine, Gulhane Military Medical Academy, Ankara, Turkey
| | - Ergun Uçar
- Department of Pulmonary Medicine, Gulhane Military Medical Academy, Ankara, Turkey
| | - Mehmet Aydoğan
- Department of Pulmonary Medicine, Gulhane Military Medical Academy, Ankara, Turkey
| | - Uğur Muşabak
- Department of Allergy and Clinical Immunology, Gulhane Military Medical Academy, Ankara, Turkey
| | - Ergun Tozkoparan
- Department of Pulmonary Medicine, Gulhane Military Medical Academy, Ankara, Turkey
| | - Hayati Bilgiç
- Department of Pulmonary Medicine, Gulhane Military Medical Academy, Ankara, Turkey
| |
Collapse
|
4
|
Edkins AL, Borland G, Acharya M, Cogdell RJ, Ozanne BW, Cushley W. Differential regulation of monocyte cytokine release by αV and β(2) integrins that bind CD23. Immunology 2012; 136:241-51. [PMID: 22348662 DOI: 10.1111/j.1365-2567.2012.03576.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The human soluble CD23 (sCD23) protein displays highly pleiotropic cytokine-like activity. Monocytic cells express the sCD23-binding integrins αVβ(3), αVβ(5), αMβ(2) and αXβ(2), but it is unclear which of these four integrins most acutely regulates sCD23-driven cytokine release. The hypothesis that ligation of different sCD23-binding integrins promoted release of distinct subsets of cytokines was tested. Lipopolysaccharide (LPS) and sCD23 promoted release of distinct groups of cytokines from the THP-1 model cell line. The sCD23-driven cytokine release signature was characterized by elevated amounts of RANTES (CCL5) and a striking increase in interleukin-8 (IL-8; CXCL8) secretion, but little release of macrophage inflammatory protein 1β (MIP-1β; CCL4). Antibodies to αVβ(3) or αXβ(2) both promoted IL-8 release, consistent with the sCD23-driven pattern, but both also evoked strong MIP-1β secretion; simultaneous ligation of these two integrins further increased cytokine secretion but did not alter the pattern of cytokine output. In both model cell lines and primary tissue, integrin-mediated cytokine release was more pronounced in immature monocyte cells than in mature cells. The capacity of anti-integrin monoclonal antibodies to elicit a cytokine release response is epitope-dependent and also reflects the differentiation state of the cell. Although a pattern of cytokine release identical to that provoked by sCD23 could not be elicited with any individual anti-integrin monoclonal antibody, αXβ(2) and αVβ(3) appear to regulate IL-8 release, a hallmark feature of sCD23-driven cytokine secretion, more acutely than αMβ(2) or αVβ(5).
Collapse
Affiliation(s)
- Adrienne L Edkins
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | | | | | | | | | | |
Collapse
|
5
|
|
6
|
Harnett W, Goodridge HS, Allen JM, Harnett M. Receptor usage by the Acanthocheilonema viteae-derived immunomodulator, ES-62. Exp Parasitol 2011; 132:97-102. [PMID: 21925176 DOI: 10.1016/j.exppara.2011.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 07/17/2011] [Accepted: 09/01/2011] [Indexed: 01/15/2023]
Abstract
ES-62 is an immunomodulatory phosphorylcholine (PC)-containing glycoprotein secreted by the rodent filarial nematode Acanthocheilonema viteae. Previously, the use of knockout mice has revealed the effects of ES-62 on macrophages and dendritic cells to be dependent on TLR4. However, it is possible that ES-62 may interact with additional proteins on the surfaces of target cells and hence that cells may vary with respect to receptor usage. In this study, we identified by molecular weight, proteins that interact with ES-62 and found differences amongst the immune system cells studied. Thus, whereas lymphocytes appear to have two major interacting proteins of ∼135 and ∼82 kDa, U937 monocytes only contain an ES-62-binding protein of the latter molecular weight. Binding to the proteins on B cells and U937 cells was blocked by PC, suggesting a critical role for this ES-62 moiety in facilitating interaction. Finally, ES-62 binding is followed by internalization in both macrophages and B cells but only in the former was absence of TLR4 found to block internalization. These findings are consistent with differences in receptor usage by ES-62 amongst different cell-types.
Collapse
Affiliation(s)
- William Harnett
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK.
| | | | | | | |
Collapse
|
7
|
Acharya M, Borland G, Edkins AL, Maclellan LM, Matheson J, Ozanne BW, Cushley W. CD23/FcεRII: molecular multi-tasking. Clin Exp Immunol 2010; 162:12-23. [PMID: 20831712 DOI: 10.1111/j.1365-2249.2010.04210.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
CD23 is the low-affinity receptor for immunoglobulin (Ig)E and plays important roles in the regulation of IgE responses. CD23 can be cleaved from cell surfaces to yield a range of soluble CD23 (sCD23) proteins that have pleiotropic cytokine-like activities. The regions of CD23 responsible for interaction with many of its known ligands, including IgE, CD21, major histocompatibility complex (MHC) class II and integrins, have been identified and help to explain the structure-function relationships within the CD23 protein. Translational studies of CD23 underline its credibility as a target for therapeutic intervention strategies and illustrate its involvement in mediating therapeutic effects of antibodies directed at other targets.
Collapse
Affiliation(s)
- M Acharya
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, CR-UK Beatson Institute, Glasgow, UK
| | | | | | | | | | | | | |
Collapse
|
8
|
Abstract
The spreading epidemic of allergies and asthma has heightened interest in IgE, the central player in the allergic response. The activity of IgE is associated with a network of proteins; prominent among these are its two principal receptors, FcepsilonRI (high-affinity Fc receptor for IgE) and CD23, as well as galectin-3 and several co-receptors for CD23, notably CD21 and various integrins. Here, we review recent progress in uncovering the structures of these proteins and their complexes, and in our understanding of how IgE exerts its effects and how its expression is regulated. The information that has emerged suggests new therapeutic directions for combating allergic disease.
Collapse
|
9
|
Borland G, Edkins AL, Acharya M, Matheson J, White LJ, Allen JM, Bonnefoy JY, Ozanne BW, Cushley W. αvβ5 Integrin Sustains Growth of Human Pre-B Cells through an RGD-independent Interaction with a Basic Domain of the CD23 Protein. J Biol Chem 2007; 282:27315-27326. [PMID: 17540777 DOI: 10.1074/jbc.m609335200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD23 is a type II transmembrane glycoprotein synthesized by hematopoietic cells that has biological activity in both membrane-bound and freely soluble forms, acting via a number of receptors, including integrins. We demonstrate here that soluble CD23 (sCD23) sustains growth of human B cell precursors via an RGD-independent interaction with the alphavbeta5 integrin. The integrin recognizes a tripeptide motif in a small disulfide-bonded loop at the N terminus of the lectin head region of CD23, centered around Arg(172), Lys(173), and Cys(174) (RKC). This RKC motif is present in all forms of sCD23 with cytokine-like activity, and cytokine activity is independent of the lectin head, an "inverse RGD" motif, and the CD21 and IgE binding sites. RKC-containing peptides derived from this region of CD23 bind alphavbeta5 and are biologically active. The binding and activity of these peptides is unaffected by inclusion of a short peptide containing the classic RGD sequence recognized by integrins, and, in far-Western analyses, RKC-containing peptides bind to the beta subunit of the alphavbeta5 integrin. The interaction between alphavbeta5 and sCD23 indicates that integrins deliver to cells important signals initiated by soluble ligands without the requirement for interactions with RGD motifs in their common ligands. This mode of integrin signaling may not be restricted to alphavbeta5.
Collapse
Affiliation(s)
- Gillian Borland
- Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, United Kingdom, the
| | - Adrienne L Edkins
- Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, United Kingdom, the
| | - Mridu Acharya
- Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, United Kingdom, the
| | - Johanne Matheson
- Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, United Kingdom, the
| | - Lindsey J White
- Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, United Kingdom, the
| | - Janet M Allen
- Conway Institute, University College Dublin, Dublin 4, Ireland, and
| | | | - Bradford W Ozanne
- Cancer Research UK Beatson Laboratories, Switchback Road, Glasgow G61 1BD, Scotland, United Kingdom
| | - William Cushley
- Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, United Kingdom, the.
| |
Collapse
|
10
|
Meng JF, McFall C, Rosenwasser LJ. Polymorphism R62W results in resistance of CD23 to enzymatic cleavage in cultured cells. Genes Immun 2007; 8:215-23. [PMID: 17301828 DOI: 10.1038/sj.gene.6364376] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A nonsynonymous single nucleotide polymorphism (SNP) of the low-affinity IgE receptor (FcvarepsilonRII/CD23) gene resulting in an arginine to tryptophan exchange at amino-acid position 62 (R62W) has been associated with enhanced T-cell responses to antigen in allergic subjects. To explore the mechanism, a CD23(a) cDNA was cloned into the plasmid pCMVScript-CD23a-C with a C allele (R62). The pCMVScript-CD23a-T with T (W62) was produced using a site-directed mutagenesis approach. The pCMVScript-CD23a-C only (CC), mixture of pCMVScript-CD23a-T and pCMVSCript-CD23a-C (CT) and pCMVScript-CD23a-T only (TT) plasmids were transfected in Cos-7 cells at equivalence in transfection efficiency. No soluble CD23 was released from TT transfectants whereas a higher level of soluble CD23 was detected in CC than in CT transfectants. Human leukocyte elastase (HLE), cathepsin G, the dust mite allergen Der p I and ADAM 33 (A disintegrin and metalloproteinase) were found to cleave membrane CD23 in CC but not in TT transfectants, implying the resistance of CD23 to enzymatic cleavage associated with T mutant. Addition of tunicamycin resulted in the resistance of CD23 to Der p I mediated cleavage in CC but no change in TT transfectants. These results indicate that R62W influences the stability of membrane CD23 molecules due to possibly diminished N-glycosylation.
Collapse
Affiliation(s)
- J-F Meng
- 1Pediatric Immunology Research Department, Children's Mercy Hospital/School of Medicine, University of Missouri at Kansas City, Kansas City, MO, USA.
| | | | | |
Collapse
|
11
|
Pozzetto U, Aguzzi MS, Maggiano N, Scala E, Capelli A, Castagneto M, Capogrossi MC, Citterio F, Serino F, Facchiano A. RGDS peptide inhibits activation of lymphocytes and adhesion of activated lymphocytes to human umbilical vein endothelial cells in vitro. Immunol Cell Biol 2005; 83:25-32. [PMID: 15661038 DOI: 10.1111/j.1440-1711.2004.01300.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Arg-Gly-Asp (RGD) motif is known to mediate cell adhesion to several extracellular matrix components as well as cell-cell interactions. In the present study, we investigated whether the RGDS peptide interferes with cell-cell recognition-based events such as allogeneic activation of PBMC and PBMC adhesion to human umbilical vein endothelial cells (HUVEC). We show here for the first time, to our knowledge, that RGDS significantly inhibits adhesion of activated PBMC to HUVEC; in addition, RGDS inhibits PBMC allogenenic activation in human mixed lymphocyte reaction assays. Caspases played a pivotal role in both events, because preventing their activation abolished or strongly reduced the observed inhibitory effect. The RGDS antirecognition effect was strongly increased by pretreatment of HUVEC with RGDS, which affected mostly T lymphocyte adhesion to HUVEC. These results indicate that PBMC allogeneic activation, as well as reciprocal recognition between activated PBMC and endothelial cells, are RGDS-dependent events that occur through a dual effect involving anti-adhesive and caspase-dependent mechanisms. These data suggest a potential role of RGDS in cell-mediated immunity, inflammation and organ transplantation.
Collapse
Affiliation(s)
- Ubaldo Pozzetto
- Laboratory of Immunology, Shock Center, IASI, CNR, Rome, Italy.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Pozzetto U, Aguzzi MS, Maggiano N, Scala E, Capelli A, Castagneto M, Capogrossi MC, Citterio F, Serino F, Facchiano A. RGDS peptide inhibits activation of lymphocytes and adhesion of activated lymphocytes to human umbilical vein endothelial cells in vitro. Immunol Cell Biol 2005. [DOI: 10.1111/j.1440-1711.2005.01300.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ubaldo Pozzetto
- Laboratory of Immunology, Shock Center, IASI, CNR Rome Italy
| | - Maria Simona Aguzzi
- Laboratory of Vascular Pathology and Department of Vascular Pathology, IDI Rome Italy
| | - Nicola Maggiano
- Department of Pathology, Catholic University Sacro Cuore Rome Italy
| | - Enrico Scala
- Department of Onco‐Immune‐Dermatology, IDI Rome Italy
| | - Arnaldo Capelli
- Department of Pathology, Catholic University Sacro Cuore Rome Italy
| | - Marco Castagneto
- Department of Surgery, Catholic University Sacro Cuore Rome Italy
| | - Maurizio C Capogrossi
- Laboratory of Vascular Pathology and Department of Vascular Pathology, IDI Rome Italy
| | - Franco Citterio
- Department of Surgery, Catholic University Sacro Cuore Rome Italy
| | - Francesco Serino
- Laboratory of Vascular Pathology and Department of Vascular Pathology, IDI Rome Italy
| | - Antonio Facchiano
- Laboratory of Vascular Pathology and Department of Vascular Pathology, IDI Rome Italy
| |
Collapse
|
13
|
Kijimoto-Ochiai S, Noguchi A, Ohnishi T, Araki Y. Complex formation of CD23/surface immunoglobulin and CD23/CD81/MHC class II on an EBV-transformed human B cell line and inferable role of tetraspanin. Microbiol Immunol 2005; 48:417-26. [PMID: 15215629 DOI: 10.1111/j.1348-0421.2004.tb03531.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
CD23, a low-affinity IgE receptor, is a type II transmembrane protein having a C-type lectin domain and it associates noncovalently with MHC class II on B cells. The results of our immunoprecipitation analysis suggest that CD23 co-exists with at least two additional molecules, surface immunoglobulin (sIg) and CD81 (and/or CD9), on the cell surface of L-KT9 cells (an Epstein-Barr virus (EBV)-transformed human B cell line). When both CD23 and sIg molecules were stimulated simultaneously by the corresponding antibodies, a large increase in CD81 in the immunoprecipitation was observed as compared with the case of stimulation by only one antibody. Simultaneous stimulation by anti-CD23 and anti-Ig may mimic the situation of B cells stimulated by an antigen/IgE complex. In addition, a large increase in MHC class II in the immunoprecipitation was also observed by cross-linking of CD23 with anti-CD23 and its second antibody as compared with the case of stimulation by anti-CD23 alone. The cross-linking of CD23 with anti-CD23 and its antibody may mimic the situation of B cells stimulated by an IgE/antigen/IgE complex. Therefore, the complex formation among CD23, sIg, MHC class II, and CD81 on the cell surface of L-KT9 cells by the antigen/IgE or IgE/antigen/IgE complex is most likely to be closely related to B cell regulatory events by signaling through sIg or MHC class II. Tetraspanins such as CD81 and CD9 are thought to be involved in the formation and the preservation of various different membrane complexes consisting of several functional proteins.
Collapse
|
14
|
Karagiannis SN, Warrack JK, Jennings KH, Murdock PR, Christie G, Moulder K, Sutton BJ, Gould HJ. Endocytosis and recycling of the complex between CD23 and HLA-DR in human B cells. Immunology 2001; 103:319-31. [PMID: 11454061 PMCID: PMC1783243 DOI: 10.1046/j.1365-2567.2001.01238.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The presentation of extremely low doses of antigen to T cells is enhanced by immunoglobulin E (IgE)-dependent antigen focusing to CD23, the low-affinity receptor for IgE, expressed on activated B cells. CD23 contains a C-type lectin domain in its extracellular sequence and a targeting signal for coated pits, required for endocytosis, in its cytoplasmic sequence. CD23 is non-covalently associated with the major histocompatibility complex class II antigen, human leucocyte antigen HLA-DR, on the surface of human B cells, but the fate of this complex following endocytosis is unknown. To answer this question we have labelled these proteins on the surface of RPMI 8866 B cells and traced their route through the cytoplasm. Endocytosis mediated by anti-CD23 antibodies (BU38 and MHM6) led to the loss of CD23 from the cells. Endocytosis mediated by an antibody to HLA-DR (CR3/43) or an antigen-IgE complex (NP-BSA-anti-NP IgE), however, led to recycling of the HLA-DR-CD23 complex to the cell surface on a time scale (3-6 hr) consistent with the recycling of HLA-DR in antigen presentation. Along the latter pathway CD23 label was observed in cytoplasmic organelles that resembled the 'compartments for peptide loading' or 'class II vesicles' described by previous authors. Two features of the recycling process may contribute to the efficiency of antigen presentation. Peptide exchange may be facilitated by the proximity of HLA-DR and antigen in peptide loading compartments of the endosomal network. The return of CD23 with HLA-DR to the cell surface may then help to stabilize specific B-cell-T-cell interactions, contributing to T-cell activation.
Collapse
Affiliation(s)
- S N Karagiannis
- The Randall Centre for Molecular Mechanisms of Cell Function, King's College London, UK.
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Mizejewski GJ. Alpha-fetoprotein structure and function: relevance to isoforms, epitopes, and conformational variants. Exp Biol Med (Maywood) 2001; 226:377-408. [PMID: 11393167 DOI: 10.1177/153537020122600503] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Mammalian alpha-fetoprotein (AFP) is classified as a member of the albuminoid gene superfamily consisting of albumin, AFP, vitamin D (Gc) protein, and alpha-albumin. Molecular variants of AFP have long been reported in the biomedical literature. Early studies identified isoelectric pH isoforms and lectin-binding variants of AFP, which differed in their physicochemical properties, but not in amino acid composition. Genetic variants of AFP, differing in mRNA kilobase length, were later extensively described in rodent models during fetal/perinatal stages, carcinogenesis, and organ regeneration. With the advent of monoclonal antibodies in the early 1980s, multiple antigenic epitopes on native AFP were detected and categorized, culminating in the identification of six to seven major epitopes. During this period, various AFP-binding proteins and receptors were reported to inhibit certain AFP immunoreactions. Concomittantly, human and rodent AFP were cloned and the amino acid sequences of the translated proteins were divulged. Once the amino acid composition of the AFP molecule was known, enzymatic fragments could be identified and synthetic peptide segments synthesized. Following discovery of the molten globule form in 1981, the existence of transitory, intermediate forms of AFP were acknowledged and their physiological significance was realized. In the present review, the various isoforms and variants of AFP are discussed in light of their potential biological relevance.
Collapse
Affiliation(s)
- G J Mizejewski
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany 12201, USA.
| |
Collapse
|