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Guérin A, Moncada-Vélez M, Jackson K, Ogishi M, Rosain J, Mancini M, Langlais D, Nunez A, Webster S, Goyette J, Khan T, Marr N, Avery DT, Rao G, Waterboer T, Michels B, Neves E, Iracema Morais C, London J, Mestrallet S, Quartier dit Maire P, Neven B, Rapaport F, Seeleuthner Y, Lev A, Simon AJ, Montoya J, Barel O, Gómez-Rodríguez J, Orrego JC, L’Honneur AS, Soudée C, Rojas J, Velez AC, Sereti I, Terrier B, Marin N, García LF, Abel L, Boisson-Dupuis S, Reis J, Marinho A, Lisco A, Faria E, Goodnow CC, Vasconcelos J, Béziat V, Ma CS, Somech R, Casanova JL, Bustamante J, Franco JL, Tangye SG. Helper T cell immunity in humans with inherited CD4 deficiency. J Exp Med 2024; 221:e20231044. [PMID: 38557723 PMCID: PMC10983808 DOI: 10.1084/jem.20231044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 01/04/2024] [Accepted: 01/31/2024] [Indexed: 04/04/2024] Open
Abstract
CD4+ T cells are vital for host defense and immune regulation. However, the fundamental role of CD4 itself remains enigmatic. We report seven patients aged 5-61 years from five families of four ancestries with autosomal recessive CD4 deficiency and a range of infections, including recalcitrant warts and Whipple's disease. All patients are homozygous for rare deleterious CD4 variants impacting expression of the canonical CD4 isoform. A shorter expressed isoform that interacts with LCK, but not HLA class II, is affected by only one variant. All patients lack CD4+ T cells and have increased numbers of TCRαβ+CD4-CD8- T cells, which phenotypically and transcriptionally resemble conventional Th cells. Finally, patient CD4-CD8- αβ T cells exhibit intact responses to HLA class II-restricted antigens and promote B cell differentiation in vitro. Thus, compensatory development of Th cells enables patients with inherited CD4 deficiency to acquire effective cellular and humoral immunity against an unexpectedly large range of pathogens. Nevertheless, CD4 is indispensable for protective immunity against at least human papillomaviruses and Trophyrema whipplei.
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Affiliation(s)
- Antoine Guérin
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Marcela Moncada-Vélez
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | | | - Masato Ogishi
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Jérémie Rosain
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
- Study Center for Primary Immunodeficiencies, Necker Hospital for Sick Children, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Mathieu Mancini
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
- Dahdaleh Institute of Genomic Medicine, McGill Research Centre on Complex Traits, McGill University, Montreal, Canada
| | - David Langlais
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
- Dahdaleh Institute of Genomic Medicine, McGill Research Centre on Complex Traits, McGill University, Montreal, Canada
| | - Andrea Nunez
- Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Samantha Webster
- Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Jesse Goyette
- Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Taushif Khan
- Department of Human Immunology, Sidra Medicine, Doha, Qatar
- The Jackson Laboratory, Farmington, CT, USA
| | - Nico Marr
- Department of Human Immunology, Sidra Medicine, Doha, Qatar
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Danielle T. Avery
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Geetha Rao
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Tim Waterboer
- Division of Infections and Cancer Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Birgitta Michels
- Division of Infections and Cancer Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Esmeralda Neves
- Immunology Department—Pathology, University Hospital Center of Porto, Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Cátia Iracema Morais
- Immunology Department—Pathology, University Hospital Center of Porto, Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Jonathan London
- Service of Internal Medicine, Diaconesse-Croix Saint Simon Hospital, Paris, France
| | - Stéphanie Mestrallet
- Department of Internal Medicine and Infectious Diseases, Manchester Hospital, Charleville-Mézières, France
| | - Pierre Quartier dit Maire
- Pediatric Immunology-Hematology and Rheumatology Unit, Necker Hospital for Sick Children, Paris, France
| | - Bénédicte Neven
- Pediatric Immunology-Hematology and Rheumatology Unit, Necker Hospital for Sick Children, Paris, France
| | - Franck Rapaport
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Yoann Seeleuthner
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Atar Lev
- Department of Pediatrics and Immunology Service, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Aviv School of Medicine, Tel Aviv, Israel
| | - Amos J. Simon
- Department of Pediatrics and Immunology Service, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Aviv School of Medicine, Tel Aviv, Israel
| | - Jorge Montoya
- San Vicente de Paul University Hospital, Medellin, Colombia
| | - Ortal Barel
- The Genomic Unit, Sheba Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Julio Gómez-Rodríguez
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Julio C. Orrego
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Anne-Sophie L’Honneur
- Department of Virology, Paris Cité University and Cochin Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Camille Soudée
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Jessica Rojas
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Alejandra C. Velez
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Irini Sereti
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Benjamin Terrier
- Department of Internal Medicine, Cochin Hospital, Assistance Publique–Hôpitaux de Paris, Paris Cité University, Paris, France
| | - Nancy Marin
- Cellular Immunology and Immunogenetics Group, University of Antioquia UdeA, Medellin, Colombia
| | - Luis F. García
- Cellular Immunology and Immunogenetics Group, University of Antioquia UdeA, Medellin, Colombia
| | - Laurent Abel
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Stéphanie Boisson-Dupuis
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Joel Reis
- Dermatology Service, University Hospital Center of Porto, Porto, Portugal
| | - Antonio Marinho
- School of Medicine and Biomedical Sciences, University of Porto, Porto, Portugal
- Department of Clinical Immunology, University Hospital Center of Porto, Porto, Portugal
| | - Andrea Lisco
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Emilia Faria
- Allergy and Clinical Immunology Department, University Hospital Center of Coimbra, Coimbra, Portugal
| | - Christopher C. Goodnow
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Julia Vasconcelos
- Immunology Department—Pathology, University Hospital Center of Porto, Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Vivien Béziat
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Cindy S. Ma
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Raz Somech
- Department of Pediatrics and Immunology Service, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Aviv School of Medicine, Tel Aviv, Israel
| | - Jean-Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
- Howard Hughes Medical Institute, New York, NY, USA
- Department of Pediatrics, Necker Hospital for Sick Children, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Jacinta Bustamante
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
- Study Center for Primary Immunodeficiencies, Necker Hospital for Sick Children, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Jose Luis Franco
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Stuart G. Tangye
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
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2
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Glassman CR, Parrish HL, Lee MS, Kuhns MS. Reciprocal TCR-CD3 and CD4 Engagement of a Nucleating pMHCII Stabilizes a Functional Receptor Macrocomplex. Cell Rep 2018; 22:1263-1275. [PMID: 29386113 PMCID: PMC5813697 DOI: 10.1016/j.celrep.2017.12.104] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/07/2017] [Accepted: 12/27/2017] [Indexed: 12/24/2022] Open
Abstract
CD4+ T cells convert the time that T cell receptors (TCRs) interact with peptides embedded within class II major histocompatibility complex molecules (pMHCII) into signals that direct cell-fate decisions. In principle, TCRs relay information to intracellular signaling motifs of the associated CD3 subunits, while CD4 recruits the kinase Lck to those motifs upon coincident detection of pMHCII. But the mechanics by which this occurs remain enigmatic. In one model, the TCR and CD4 bind pMHCII independently, while in another, CD4 interacts with a composite surface formed by the TCR-CD3 complex bound to pMHCII. Here, we report that the duration of TCR-pMHCII interactions impact CD4 binding to MHCII. In turn, CD4 increases TCR confinement to pMHCII via reciprocal interactions involving membrane distal and proximal CD4 ectodomains. The data suggest that a precisely assembled macrocomplex functions to reliably convert TCR-pMHCII confinement into reproducible signals that orchestrate adaptive immunity.
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Affiliation(s)
- Caleb R Glassman
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724, USA
| | - Heather L Parrish
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724, USA
| | - Mark S Lee
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724, USA
| | - Michael S Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724, USA; The BIO-5 Institute, The University of Arizona College of Medicine, Tucson, AZ 85724, USA; The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, AZ 85724, USA; The University of Arizona Cancer Center, The University of Arizona College of Medicine, Tucson, AZ 85724, USA.
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3
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Liaunardy-Jopeace A, Murton BL, Mahesh M, Chin JW, James JR. Encoding optical control in LCK kinase to quantitatively investigate its activity in live cells. Nat Struct Mol Biol 2017; 24:1155-1163. [PMID: 29083415 PMCID: PMC5736103 DOI: 10.1038/nsmb.3492] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 09/25/2017] [Indexed: 11/16/2022]
Abstract
LCK is a tyrosine kinase essential for initiating T-cell antigen receptor (TCR) signaling. A complete understanding of LCK function is constrained by a paucity of methods to quantitatively study its function within live cells. To address this limitation, we generated LCK*, in which a key active site lysine is replaced by a photo-caged equivalent, using genetic code expansion. This enabled fine temporal and spatial control over kinase activity, allowing us to quantify phosphorylation kinetics in situ using biochemical and imaging approaches. We find that auto-phosphorylation of the LCK active site loop is indispensable for its catalytic activity and that LCK can stimulate its own activation by adopting a more open conformation, which can be modulated by point mutations. We then show that CD4 and CD8, the T cell coreceptors, can enhance LCK activity, helping to explain their effect in physiological TCR signaling. Our approach also provides general insights into SRC-family kinase dynamics.
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Affiliation(s)
| | - Ben L Murton
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC-LMB, Cambridge, UK
| | - Mohan Mahesh
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, UK
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, UK
| | - John R James
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC-LMB, Cambridge, UK
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4
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Matsubara T, Nishii N, Takashima S, Takasu M, Imaeda N, Aiki-Oshimo K, Yamazoe K, Kakisaka M, Takeshima SN, Aida Y, Kametani Y, Kulski JK, Ando A, Kitagawa H. Identification and characterization of two CD4 alleles in Microminipigs. BMC Vet Res 2016; 12:222. [PMID: 27717346 PMCID: PMC5055687 DOI: 10.1186/s12917-016-0856-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 10/04/2016] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND We previously identified two phenotypes of CD4+ cells with and without reactions to anti-pig CD4 monoclonal antibodies by flow cytometry in a herd of Microminipigs. In this study, we analyzed the coding sequences of CD4 and certified the expression of CD4 molecules in order to identify the genetic sequence variants responsible for the positive and negative PBMCs reactivity to anti-pig CD4 monoclonal antibodies. RESULTS We identified two CD4 alleles, CD4.A and CD4.B, corresponding to antibody positive and negative, respectively, by nucleotide sequencing of PCR products using CD4 specific primer pairs. In comparison with the swine CD4 amino-acid sequence [GenBank: NP_001001908], CD4.A had seven amino-acid substitutions and CD4.B had 15 amino-acid substitutions. The amino-acid sequences within domain 1 of CD4.B were identical to the swine CD4.2 [GenBank: CAA46584] sequence that had been reported previously to be a modified CD4 molecule that had lost reactivity with an anti-pig CD4 antibody in NIH miniature pigs. Homozygous and heterozygous CD4.A and CD4.B alleles in the Microminipigs herd were characterised by using the RFLP technique with the restriction endonuclease, BseRI. The anti-pig CD4 antibody recognized pig PBMCs with CD4.AA and CD4.AB, but did not recognized those with CD4.BB. We transfected HeLa cells with the FLAG-tagged CD4.A or CD4.B vectors, and certified that transfected HeLa cells expressed FLAG in both vectors. The failure of cells to react with anti-CD4 antibodies in CD4.B pigs was associated to ten amino-acid substitutions in domain 1 and/or one amino-acid substitution in joining region 3 of CD4.B. We also found exon 8 was defective in some CD4.A and CD4.B resulting in the loss of the transmembrane domain, which implies that these CD4 proteins are secreted from helper T cells into the circulation. CONCLUSIONS We identified that amino-acids substitutions of domain 1 in CD4.B gave rise to the failure of some CD4 expressing cells to react with particular anti-pig CD4 monoclonal antibodies. In addition, we developed a PCR-RFLP method that enabled us to simply identify the CD4 sequence variant and the positive and negative PBMCs reactivity to our anti-pig CD4 monoclonal antibodies without the need to use flow cytometric analysis.
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Affiliation(s)
- Tatsuya Matsubara
- United Graduate School of Veterinary Sciences, Gifu University, Gifu, 501-1193 Japan
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | - Naohito Nishii
- United Graduate School of Veterinary Sciences, Gifu University, Gifu, 501-1193 Japan
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | - Satoshi Takashima
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | - Masaki Takasu
- United Graduate School of Veterinary Sciences, Gifu University, Gifu, 501-1193 Japan
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | - Noriaki Imaeda
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | - Kayo Aiki-Oshimo
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | - Kazuaki Yamazoe
- United Graduate School of Veterinary Sciences, Gifu University, Gifu, 501-1193 Japan
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
| | | | | | - Yoko Aida
- Viral Infectious Diseases Unit, RIKEN, Wako, 351-0198 Japan
| | - Yoshie Kametani
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Isehara, 259-1193 Japan
| | - Jerzy K. Kulski
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Isehara, 259-1193 Japan
- School of Psychiatry and Clinical Neurosciences, The University of Western Australia, Crawley, WA 6009 Australia
| | - Asako Ando
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Isehara, 259-1193 Japan
| | - Hitoshi Kitagawa
- United Graduate School of Veterinary Sciences, Gifu University, Gifu, 501-1193 Japan
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
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Glassman CR, Parrish HL, Deshpande NR, Kuhns MS. The CD4 and CD3δε Cytosolic Juxtamembrane Regions Are Proximal within a Compact TCR-CD3-pMHC-CD4 Macrocomplex. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:4713-22. [PMID: 27183595 PMCID: PMC4875830 DOI: 10.4049/jimmunol.1502110] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/29/2016] [Indexed: 12/15/2022]
Abstract
TCRs relay information about peptides embedded within MHC molecules (pMHC) to the ITAMs of the associated CD3γε, CD3δε, and CD3ζζ signaling modules. CD4 then recruits the Src kinase p56(Lck) (Lck) to the TCR-CD3 complex to phosphorylate the ITAMs, initiate intracellular signaling, and drive CD4(+) T cell fate decisions. Whereas the six ITAMs of CD3ζζ are key determinants of T cell development, activation, and the execution of effector functions, multiple models predict that CD4 recruits Lck proximal to the four ITAMs of the CD3 heterodimers. We tested these models by placing FRET probes at the cytosolic juxtamembrane regions of CD4 and the CD3 subunits to evaluate their relationship upon pMHC engagement in mouse cell lines. The data are consistent with a compact assembly in which CD4 is proximal to CD3δε, CD3ζζ resides behind the TCR, and CD3γε is offset from CD3δε. These results advance our understanding of the architecture of the TCR-CD3-pMHC-CD4 macrocomplex and point to regions of high CD4-Lck + ITAM concentrations therein. The findings thus have implications for TCR signaling, as phosphorylation of the CD3 ITAMs by CD4-associated Lck is important for CD4(+) T cell fate decisions.
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Affiliation(s)
- Caleb R Glassman
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724
| | - Heather L Parrish
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724
| | - Neha R Deshpande
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724; The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, AZ 85724; and
| | - Michael S Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ 85724; The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, AZ 85724; and The BIO5 Institute, The University of Arizona College of Medicine, Tucson, AZ 85724
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6
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Parrish HL, Glassman CR, Keenen MM, Deshpande NR, Bronnimann MP, Kuhns MS. A Transmembrane Domain GGxxG Motif in CD4 Contributes to Its Lck-Independent Function but Does Not Mediate CD4 Dimerization. PLoS One 2015; 10:e0132333. [PMID: 26147390 PMCID: PMC4493003 DOI: 10.1371/journal.pone.0132333] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 06/14/2015] [Indexed: 12/24/2022] Open
Abstract
CD4 interactions with class II major histocompatibility complex (MHC) molecules are essential for CD4+ T cell development, activation, and effector functions. While its association with p56lck (Lck), a Src kinase, is important for these functions CD4 also has an Lck-independent role in TCR signaling that is incompletely understood. Here, we identify a conserved GGxxG motif in the CD4 transmembrane domain that is related to the previously described GxxxG motifs of other proteins and predicted to form a flat glycine patch in a transmembrane helix. In other proteins, these patches have been reported to mediate dimerization of transmembrane domains. Here we show that introducing bulky side-chains into this patch (GGxxG to GVxxL) impairs the Lck-independent role of CD4 in T cell activation upon TCR engagement of agonist and weak agonist stimulation. However, using Forster’s Resonance Energy Transfer (FRET), we saw no evidence that these mutations decreased CD4 dimerization either in the unliganded state or upon engagement of pMHC concomitantly with the TCR. This suggests that the CD4 transmembrane domain is either mediating interactions with an unidentified partner, or mediating some other function such as membrane domain localization that is important for its role in T cell activation.
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Affiliation(s)
- Heather L. Parrish
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Caleb R. Glassman
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Madeline M. Keenen
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Neha R. Deshpande
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Matthew P. Bronnimann
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Michael S. Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- The Arizona Center on Aging, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- The BIO-5 Institute, The University of Arizona College of Medicine, Tucson, Arizona, United States of America
- * E-mail:
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7
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CD4 blockade directly inhibits mouse and human CD4(+) T cell functions independent of Foxp3(+) Tregs. J Autoimmun 2013; 47:73-82. [PMID: 24055067 DOI: 10.1016/j.jaut.2013.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/20/2013] [Accepted: 08/26/2013] [Indexed: 11/22/2022]
Abstract
CD4(+) helper T cells orchestrate protective immunity against pathogens, yet can also induce undesired pathologies including allergies, transplant rejection and autoimmunity. Non-depleting CD4-specific antibodies such as clone YTS177.9 were found to promote long-lasting T cell tolerance in animal models. Thus, CD4 blockade could represent a promising therapeutic approach for human autoimmune diseases. However, the mechanisms underlying anti-CD4-induced tolerance are incompletely resolved. Particularly, multiple immune cells express CD4 including Foxp3(+) regulatory T cells (Tregs) and dendritic cells (DCs), both controlling the activation of CD4(+)Foxp3(-) helper T cells. Utilizing mixed leukocyte reactions (MLRs) reflecting physiological interactions between T cells and DCs, we report that anti-CD4 treatment inhibits CD4(+)Foxp3(-) T cell proliferation in an IL-2-independent fashion. Notably, YTS177.9 binding induces a rapid internalization of CD4 on both CD4(+)Foxp3(-) T cells and Foxp3(+) Tregs. However, no expansion or activation of immunosuppressive CD4(+)Foxp3(+) Tregs was observed following anti-CD4 treatment. Additionally, cytokine production, maturation and T cell priming capacity of DCs are not affected by anti-CD4 exposure. In line with these data, the selective ablation of Foxp3(+) Tregs from MLRs by the use of diphtheria toxin (DT)-treated bacterial artificial chromosome (BAC)-transgenic DEREG mice completely fails to abrogate the suppressive activity of multiple anti-CD4 antibodies. Instead, tolerization is associated with the defective expression of various co-stimulatory receptors including OX40 and CD30, suggesting altered signaling through the TCR complex. Consistent with our findings in mice, anti-CD4 treatment renders human CD4(+) T cells tolerant in the absence of Tregs. Thus, our results establish that anti-CD4 antibodies can directly tolerize pathogenic CD4(+)Foxp3(-) helper T cells. This has important implications for the treatment of human inflammatory diseases.
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8
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Kuhns MS, Badgandi HB. Piecing together the family portrait of TCR-CD3 complexes. Immunol Rev 2013; 250:120-43. [PMID: 23046126 DOI: 10.1111/imr.12000] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The pre-T-cell receptor (TCR)-, αβTCR-, and γδTCR-CD3 complexes are members of a family of modular biosensors that are responsible for driving T-cell development, activation, and effector functions. They inform essential checkpoint decisions by relaying key information from their ligand-binding modules (TCRs) to their signaling modules (CD3γε + CD3δε and CD3ζζ) and on to the intracellular signaling apparatus. Their actions shape the T-cell repertoire, as well as T-cell-mediated immunity; yet, the mechanisms that underlie their activity remain an enigma. As with any molecular machine, understanding how they function depends upon understanding how their parts fit and work together. In the 30 years since the initial biochemical and genetic characterizations of the αβTCR, the structure and function of the individual components of these family members have been extensively characterized. Cumulatively, this information has allowed us to piece together a portrait of the αβTCR-CD3 complex and outline the form of the remaining family members. Here we review the known structural and functional characteristics of the components of these TCR-CD3 complex family members. We then discuss how these data have informed our understanding of the architecture of the αβTCR-CD3 complex as well as their implications for the other family members. The intent is to provide a framework for considering: (i) how these thematically similar complexes diverge to execute their specific functions and (ii) how our knowledge of the form and function of these distinct family members can cross-inform our understanding of the other family members.
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Affiliation(s)
- Michael S Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine, Tucson, USA.
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9
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Kuhns MS, Davis MM. TCR Signaling Emerges from the Sum of Many Parts. Front Immunol 2012; 3:159. [PMID: 22737151 PMCID: PMC3381686 DOI: 10.3389/fimmu.2012.00159] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 05/27/2012] [Indexed: 11/30/2022] Open
Abstract
“How does T cell receptor signaling begin?” Answering this question requires an understanding of how the parts of the molecular machinery that mediates this process fit and work together. Ultimately this molecular architecture must (i) trigger the relay of information from the TCR-pMHC interface to the signaling substrates of the CD3 molecules and (ii) bring the kinases that modify these substrates in close proximity to interact, initiate, and sustain signaling. In this contribution we will discuss advances of the last decade that have increased our understanding of the complex machinery and interactions that underlie this type of signaling.
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Affiliation(s)
- Michael S Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine Tucson, AZ, USA
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10
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Hackl H, Rommer A, Konrad TA, Nassimbeni C, Wieser R. Tetracycline regulator expression alters the transcriptional program of mammalian cells. PLoS One 2010; 5:e13013. [PMID: 20886048 PMCID: PMC2945318 DOI: 10.1371/journal.pone.0013013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 09/03/2010] [Indexed: 11/19/2022] Open
Abstract
Background Tetracycline regulated ectopic gene expression is a widely used tool to study gene function. However, the tetracycline regulator (tetR) itself has been reported to cause certain phenotypic changes in mammalian cells. We, therefore, asked whether human myeloid U937 cells expressing the tetR in an autoregulated manner would exhibit alterations in gene expression upon removal of tetracycline. Methodology/Principal Findings Microarray analyses revealed that 172 and 774 unique genes were significantly differentially expressed by at least 2- or 1.5-fold, respectively, when tetR expressing U937 cells were maintained in media with or without the antibiotic. Conclusions/Significance These alterations in gene expression are likely to contribute to the phenotypic consequences of tetR expression. In addition, they need to be taken into consideration when using the tetR system for the identification of target genes of transcription factors or other genes of interest.
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Affiliation(s)
- Hubert Hackl
- Biocenter, Section for Bioinformatics, Innsbruck Medical University, Innsbruck, Austria
| | - Anna Rommer
- Clinic of Medicine I, Medical University of Vienna, Vienna, Austria
- Institute of Human Genetics, Medical University of Vienna, Vienna, Austria
| | - Torsten A. Konrad
- Institute of Human Genetics, Medical University of Vienna, Vienna, Austria
| | | | - Rotraud Wieser
- Clinic of Medicine I, Medical University of Vienna, Vienna, Austria
- Institute of Human Genetics, Medical University of Vienna, Vienna, Austria
- * E-mail:
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11
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Vignali DAA. CD4 on the road to coreceptor status. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2010; 184:5933-4. [PMID: 20483776 PMCID: PMC3142941 DOI: 10.4049/jimmunol.1090037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Dario A A Vignali
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA.
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12
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Moldovan MC, Sabbagh L, Breton G, Sékaly RP, Krummel MF. Triggering of T cell activation via CD4 dimers. THE JOURNAL OF IMMUNOLOGY 2006; 176:5438-45. [PMID: 16622011 DOI: 10.4049/jimmunol.176.9.5438] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The onset of activation in Th cells is triggered by localized co-engagement of TCRs and the coreceptor CD4. A CD4 crystal suggested that CD4 may form dimers in some circumstances. In this study, we use live-cell fluorescence resonance energy transfer imaging to demonstrate that CD4 dimers are present at a basal level on the cell surface and accumulate at the synapse. Mechanistically, we reveal two conditions under which dimers are highly relevant. First, CD4 dimers are more proficient in mediating prolonged cell contacts with APCs in the presence or absence of Ag. This is consistent with a model whereby the dimer functions to increase T-APC avidity. Second, we show that dimer mutations result in an increased level of an inactive lckTyr(505) bound to the CD4 molecule relative to dimer-competent CD4. We also find a consistent defect in signaling onset in these cells. This supports a role for CD4 dimerization in maintaining active signaling machinery. We suggest that modulation of the dimer/monomer ratio may permit tuning of activation thresholds during initial engagement.
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13
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Kawagoe H, Potter M, Ellis J, Grosveld GC. TEL2, an ETS factor expressed in human leukemia, regulates monocytic differentiation of U937 Cells and blocks the inhibitory effect of TEL1 on ras-induced cellular transformation. Cancer Res 2004; 64:6091-100. [PMID: 15342392 DOI: 10.1158/0008-5472.can-04-0839] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
TEL2 is a member of the ETS family of transcription factors, which is highly similar to TEL1/ETV6. It binds to DNA via the ETS domain and interacts with itself or TEL1 via the pointed domain. The expression of TEL2 in normal and leukemic hematopoietic cells suggests a role in hematopoietic development. In this article, we describe the role of TEL2 in hematopoietic differentiation and cellular transformation. Quantitative reverse transcription-PCR showed that the expression of TEL2 mRNA was down-regulated during monocytic differentiation of U937 and HL60 induced by 1,25-(OH)2 vitamin D3 and 12-O-tetradecanoylphorbol 13-acetate, respectively. Overexpression of TEL2 in U937 cells inhibited differentiation induced by vitamin D3. In contrast, overexpression of a TEL2 mutant lacking either the pointed domain or a functional ETS domain induced both differentiation of U937 cells and inhibited their growth in vitro and in vivo. In addition, these mutants blocked TEL2-mediated transcriptional repression of a synthetic promoter containing TEL2 binding sites. These data suggest that dominant-negative inhibition of TEL2 might cause differentiation. Quantitative reverse transcription-PCR demonstrated that TEL2 is expressed at higher level in some primary human leukemia samples than in normal bone marrow. Furthermore, overexpression of TEL2 in NIH3T3-UCLA cells blocked the inhibitory effect of TEL1 on Ras-induced cellular transformation. These results suggest that TEL2 may play an important role in hematopoiesis and oncogenesis.
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Affiliation(s)
- Hiroyuki Kawagoe
- Department of Genetics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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14
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Capparelli R, Costabile A, Viscardi M, Iannelli D. Monoallelic expression of mouse Cd4 gene. Mamm Genome 2004; 15:579-84. [PMID: 15457337 DOI: 10.1007/s00335-004-2351-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Accepted: 03/30/2004] [Indexed: 12/01/2022]
Abstract
A 7-bp deletion in the Cd4 gene, present in the strain MOLF/Ei of Mus musculus molossinus and absent in laboratory mouse strains ( Mus musculus musculus), provided the means to distinguish the parental origin of the Cd4 alleles expressed in single cells of F1 (AKR x MOLF/Ei) and F1 (Balb/C x MOLF/Ei) hybrids. Single-cell RT-PCR showed that the individual CD4+ lymphocyte expresses either the maternal or the paternal Cd4 allele, never both. In situ hybridization proved that Cd4 alleles replicate asynchronously, as expected in the case of genes expressed monoallelically.
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Affiliation(s)
- Rosanna Capparelli
- School of Biotechnological Sciences, University of Naples Federico II, Italy
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15
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Caslini C, Serna A, Rossi V, Introna M, Biondi A. Modulation of cell cycle by graded expression of MLL-AF4 fusion oncoprotein. Leukemia 2004; 18:1064-71. [PMID: 14990976 DOI: 10.1038/sj.leu.2403321] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Acute lymphoblastic leukemia (ALLs) expressing MLL-AF4, the fusion product of t(4;11)(q21;q23), show marked leucocytosis and extramedullary disease in multiple organs, respond poorly to chemotherapy and have poor prognosis. In vitro, leukemic cells with the t(4;11) show resistance to serum deprivation-induced or interferon gamma-regulated CD95-mediated apoptosis. In addition, t(4;11) cells have prolonged doubling time and lower percentage of cells in cycle compared to non-t(4;11) B lineage cell lines. In this study, we examine the time- and level-dependent effects of MLL-AF4 conditional expression on cell cycle and differentiation of myelomonocytic leukemia cell line U937. By varying the concentration of tetracycline in growth media, we found that increasing levels of MLL-AF4 expression result in a progressive decrease in growth rate and fraction of S phase cells, paralleled by an increase in percentage of cells expressing CD11b. Our results demonstrate a dosage-dependent effect of MLL-AF4 fusion oncoprotein on cell cycle progression, with increasing expression levels resulting in the accumulation in G1, prolonged doubling time, both findings that might be responsible for the increased resistance to etoposide-mediated cytotoxicity. We propose the cell cycle control exerted by MLL-AF4 may be responsible of resistance to cell-death promoting stimuli in leukemia carrying the t(4;11) translocation.
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Affiliation(s)
- C Caslini
- Centro Ricerche M Tettamanti, Clinica Pediatrica Università Milano-Bicocca, Monza, Italy
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16
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La Gruta NL, Liu H, Dilioglou S, Rhodes M, Wiest DL, Vignali DAA. Architectural Changes in the TCR:CD3 Complex Induced by MHC:Peptide Ligation. THE JOURNAL OF IMMUNOLOGY 2004; 172:3662-9. [PMID: 15004169 DOI: 10.4049/jimmunol.172.6.3662] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A hallmark of T cell activation is the ligation-induced down-modulation of the TCR:CD3 complex. However, little is known about the molecular events that drive this process. The CD3 zeta-chain has been shown to play a unique role in regulating the assembly, transport, and cell surface expression of the TCR:CD3 complex. In this study we have investigated the relationship between CD3zeta and the TCRalphabetaCD3epsilondeltagamma complex after ligation by MHC:peptide complexes. Our results show that there is a significant increase in free surface CD3zeta, which is not associated with the TCR:CD3 complex, after T cell stimulation. This may reflect dissociation of CD3zeta from the TCRalphabetaCD3epsilondeltagamma complex or transport of intracellular CD3zeta directly to the cell surface. We also show that MHC:peptide ligation also results in exposure of the TCR-associated CD3zeta NH2 terminus, which is ordinarily buried in the complex. These observations appears to be dependent on Src family protein tyrosine kinases, which are known to be critical for efficient T cell activation. These data suggest a mechanism by which ligated TCR may be differentiated from unligated TCR and selectively down-modulated.
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Affiliation(s)
- Nicole L La Gruta
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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17
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Kerry SE, Buslepp J, Cramer LA, Maile R, Hensley LL, Nielsen AI, Kavathas P, Vilen BJ, Collins EJ, Frelinger JA. Interplay between TCR affinity and necessity of coreceptor ligation: high-affinity peptide-MHC/TCR interaction overcomes lack of CD8 engagement. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:4493-503. [PMID: 14568922 PMCID: PMC3755740 DOI: 10.4049/jimmunol.171.9.4493] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD8 engagement is believed to be a critical event in the activation of naive T cells. In this communication, we address the effects of peptide-MHC (pMHC)/TCR affinity on the necessity of CD8 engagement in T cell activation of primary naive cells. Using two peptides with different measured avidities for the same pMHC-TCR complex, we compared biochemical affinity of pMHC/TCR and the cell surface binding avidity of pMHC/TCR with and without CD8 engagement. We compared early signaling events and later functional activity of naive T cells in the same manner. Although early signaling events are altered, we find that high-affinity pMHC/TCR interactions can overcome the need for CD8 engagement for proliferation and CTL function. An integrated signal over time allows T cell activation with a high-affinity ligand in the absence of CD8 engagement.
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MESH Headings
- Animals
- Antigens, Viral/immunology
- Aspartic Acid/genetics
- CD8 Antigens/immunology
- CD8 Antigens/metabolism
- CD8-Positive T-Lymphocytes/cytology
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- COS Cells
- Chlorocebus aethiops
- Cytokines/metabolism
- Cytotoxicity, Immunologic
- Glycoproteins/immunology
- H-2 Antigens/genetics
- H-2 Antigens/immunology
- H-2 Antigens/metabolism
- Histocompatibility Antigen H-2D
- Ligands
- Lymphocyte Activation/genetics
- Lymphocytic choriomeningitis virus/immunology
- Lysine/genetics
- Membrane Microdomains/genetics
- Membrane Microdomains/immunology
- Membrane Microdomains/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mutagenesis, Site-Directed
- Peptide Fragments/genetics
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- Protein Binding/genetics
- Protein Binding/immunology
- Protein Structure, Tertiary/genetics
- Receptor Cross-Talk/immunology
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/physiology
- Signal Transduction/genetics
- Signal Transduction/immunology
- Viral Proteins/immunology
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Affiliation(s)
- Samantha E. Kerry
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Jennifer Buslepp
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Lorraine A. Cramer
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Robert Maile
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Lucinda L. Hensley
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Alma I. Nielsen
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Paula Kavathas
- Department of Laboratory Medicine, Yale University, New Haven, CT 06520
| | - Barbara J. Vilen
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
| | - Edward J. Collins
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Jeffrey A. Frelinger
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599
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18
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Doucey MA, Goffin L, Naeher D, Michielin O, Baumgärtner P, Guillaume P, Palmer E, Luescher IF. CD3 delta establishes a functional link between the T cell receptor and CD8. J Biol Chem 2003; 278:3257-64. [PMID: 12215456 DOI: 10.1074/jbc.m208119200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
T cells expressing T cell receptor (TCR) complexes that lack CD3 delta, either due to deletion of the CD3 delta gene, or by replacement of the connecting peptide of the TCR alpha chain, exhibit severely impaired positive selection and TCR-mediated activation of CD8 single-positive T cells. Because the same defects have been observed in mice expressing no CD8 beta or tailless CD8 beta, we examined whether CD3 delta serves to couple TCR.CD3 with CD8. To this end we used T cell hybridomas and transgenic mice expressing the T1 TCR, which recognizes a photoreactive derivative of the PbCS 252-260 peptide in the context of H-2K(d). We report that, in thymocytes and hybridomas expressing the T1 TCR.CD3 complex, CD8 alpha beta associates with the TCR. This association was not observed on T1 hybridomas expressing only CD8 alpha alpha or a CD3 delta(-) variant of the T1 TCR. CD3 delta was selectively co-immunoprecipitated with anti-CD8 antibodies, indicating an avid association of CD8 with CD3 delta. Because CD8 alpha beta is a raft constituent, due to this association a fraction of TCR.CD3 is raft-associated. Cross-linking of these TCR-CD8 adducts results in extensive TCR aggregate formation and intracellular calcium mobilization. Thus, CD3 delta couples TCR.CD3 with raft-associated CD8, which is required for effective activation and positive selection of CD8(+) T cells.
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Affiliation(s)
- Marie-Agnès Doucey
- Institute for Biochemistry, University of Lausanne, Epalinges 1066, Switzerland
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19
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Washington LT, Huh YO, Powers LC, Duvic M, Jones D. A stable aberrant immunophenotype characterizes nearly all cases of cutaneous T-cell lymphoma in blood and can be used to monitor response to therapy. BMC Clin Pathol 2002; 2:5. [PMID: 12475398 PMCID: PMC140025 DOI: 10.1186/1472-6890-2-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2002] [Accepted: 12/10/2002] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND: Abnormal variations in the expression level of some commonly expressed T-cell antigens are a feature of many T-cell malignancies. METHODS: We sought to assess the frequency of such abnormal antigen expression by flow cytometry in peripheral blood (PB) samples from patients with mycosis fungoides (MF) and Sézary syndrome (SS). We correlated presence of morphologically identifiable tumor cells on PB smear with the frequency of abnormalities in the level of expression of CD3, CD4, CD7, CD8 and CD26. We also examined the degree of stability of these abnormal findings in tumor cells over the course of disease. The flow cytometric findings in 100 PB samples from 44 patients, including 38 who had multiple sequential PB samples (2-8 samples each), were assessed. RESULTS: Abnormalities were seen in the expression level of one or more T-cell markers in 41 cases (93%) including CD3 in 34% of patients, CD4 in 54%, CD26 in 86% and CD 45 in 40% (10 cases tested). In all but 2 cases, the abnormal T-cell immunophenotype remained similar over the course of treatment and correlated with the relative numbers of tumor cells counted on PB smear. CONCLUSIONS: Using a standard T-cell panel, stable phenotypically aberrant T-cell populations representing the tumor are detected in the vast majority of involved PB samples in MF/SS and can be used to monitor response to therapy.
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Affiliation(s)
- LaBaron T Washington
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston TX, USA
| | - Yang O Huh
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston TX, USA
| | - Linda C Powers
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston TX, USA
| | - Madeleine Duvic
- Department of Dermatology, The University of Texas MD Anderson Cancer Center, Houston TX, USA
| | - Dan Jones
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston TX, USA
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20
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Clapham PR, McKnight Á. Cell surface receptors, virus entry and tropism of primate lentiviruses. J Gen Virol 2002; 83:1809-1829. [PMID: 12124446 DOI: 10.1099/0022-1317-83-8-1809] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Human immunodeficiency virus (HIV) exploits cell surface receptors to attach to and gain entry into cells. The HIV envelope spike glycoprotein on the surface of virus particles binds both CD4 and a seven-transmembrane coreceptor. These interactions trigger conformational changes in the envelope spike that induce fusion of viral and cellular membranes and entry of the viral core into the cell cytoplasm. Other cell surface receptors also interact with gp120 and aid attachment of virus particles. This review describes these receptors, their roles in HIV entry and their influence on cell tropism.
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Affiliation(s)
- Paul R Clapham
- Center for AIDS Research, Program in Molecular Medicine, Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Biotech II, 373, Plantation Street, Worcester. MA 01605, USA1
| | - Áine McKnight
- The Wohl Virion Center, Department of Immunology and Molecular Pathology, The Windeyer Institute for Medical Sciences, University College London, 46 Cleveland Street, London W1P 6DB, UK2
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21
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Gao GF, Rao Z, Bell JI. Molecular coordination of alphabeta T-cell receptors and coreceptors CD8 and CD4 in their recognition of peptide-MHC ligands. Trends Immunol 2002; 23:408-13. [PMID: 12133804 DOI: 10.1016/s1471-4906(02)02282-2] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The interaction of the alphabeta T-cell receptor (TCR) with its ligand, peptide-MHC (pMHC), is enhanced by the recognition of the coreceptor CD8 or CD4 to the same pMHC in the immunological synapse. In the past few years, the coordination of these interactions at the molecular level has been revealed by analysis of their complex crystal structures and binding dynamics. Here we discuss the interactions of pMHC with the TCR and coreceptor CD8 or CD4 on the surfaces of alphabeta T cells and antigen presenting cells, and the implications for TCR signalling and the T-cell repertoire.
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Affiliation(s)
- George F Gao
- Nuffield Dept. of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Headington, Oxford, UK.
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22
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Arnold PY, La Gruta NL, Miller T, Vignali KM, Adams PS, Woodland DL, Vignali DAA. The majority of immunogenic epitopes generate CD4+ T cells that are dependent on MHC class II-bound peptide-flanking residues. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:739-49. [PMID: 12097376 DOI: 10.4049/jimmunol.169.2.739] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Peptides bind to MHC class II molecules with a defined periodicity such that the peptide-flanking residues (PFRs) P-1 and P11, which lie outside the core binding sequence (P1-P9), are solvent exposed and accessible to the TCR. Using a novel MHC class II:peptide binding assay, we defined the binding register for nine immunogenic epitopes to formally identify the flanking residues. Seven of the nine epitopes, restricted by H-2A(k), H-2A(g7), or H-2E(k), were found to generate T cells that were completely dependent on either P-1 or P11, with dependency on P-1 favored over P11. Such PFR dependency appears to be influenced by the type of amino acid exposed, in that residues that can form salt bridges or hydrogen bonds are favored over small or hydrophobic residues. Peptides containing alanine substitutions at P-1 or P11 in place of PFRs that mediate dependency were considerably less immunogenic and mediated a substantially reduced in vitro recall response to the native protein, inferring that PFR recognition increases immunogenicity. Our data suggest that PFR recognition is a common event characteristic of all MHC class II-restricted T cell responses. This key feature, which is not shared by MHC class I-restricted responses, may underlie the broad functional diversity displayed by MHC class II-restricted T cells.
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Affiliation(s)
- Paula Y Arnold
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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23
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Batard P, Szollosi J, Luescher I, Cerottini JC, MacDonald R, Romero P. Use of phycoerythrin and allophycocyanin for fluorescence resonance energy transfer analyzed by flow cytometry: advantages and limitations. CYTOMETRY 2002; 48:97-105. [PMID: 12116371 DOI: 10.1002/cyto.10106] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND This study validates the use of phycoerythrin (PE) and allophycocyanin (APC) for fluorescence energy transfer (FRET) analyzed by flow cytometry. METHODS FRET was detected when a pair of antibody conjugates directed against two noncompetitive epitopes on the same CD8alpha chain was used. FRET was also detected between antibody conjugate pairs specific for the two chains of the heterodimeric alpha (4)beta(1) integrin. Similarly, the association of T-cell receptor (TCR) with a soluble antigen ligand was detected by FRET when anti-TCR antibody and MHC class I/peptide complexes (<<tetramers>>) were used. RESULTS FRET efficiency was always less than 10%, probably because of steric effects associated with the size and structure of PE and APC. Some suggestions are given to take into account this and other effects (e.g., donor and acceptor concentrations) for a better interpretation of FRET results obtained with this pair of fluorochromes. CONCLUSIONS We conclude that FRET assays can be carried out easily with commercially available antibodies and flow cytometers to study arrays of multimolecular complexes.
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Affiliation(s)
- Pascal Batard
- Division of Clinical Onco-Immunology, Ludwig Institute for Cancer Research, Lausanne Branch, University Hospital (CHUV), Niveau 5, Avenue Pierre Decker 4, 1005 Lausanne, Switzerland.
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24
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Zal T, Zal MA, Gascoigne NRJ. Inhibition of T cell receptor-coreceptor interactions by antagonist ligands visualized by live FRET imaging of the T-hybridoma immunological synapse. Immunity 2002; 16:521-34. [PMID: 11970876 DOI: 10.1016/s1074-7613(02)00301-1] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The diverse effects of TCR agonists and antagonists on T cell activation are believed to be modified by the differential recruitment of CD4 or CD8 coreceptors to the TCR-MHCp complex. We used three-dimensional live cell imaging of fluorescence resonance energy transfer (FRET) between CD3zeta and CD4 fused to variants of the green fluorescent protein to investigate TCR-CD4 interactions during T cell activation. We demonstrate that recognition of agonist MHCp complexes triggers intermolecular interaction between CD4 and TCR, detectable across the T-hybridoma-APC contact area. This interaction is blocked by the presence of antagonist ligands without decreasing the recruitment of zeta and CD4 or preventing their partial colocalization in the immunological synapse.
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Affiliation(s)
- Tomasz Zal
- Deptartment of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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25
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Shah K, Gadella TW, van Erp H, Hecht V, de Vries SC. Subcellular localization and oligomerization of the Arabidopsis thaliana somatic embryogenesis receptor kinase 1 protein. J Mol Biol 2001; 309:641-55. [PMID: 11397085 DOI: 10.1006/jmbi.2001.4706] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Arabidopsis thaliana somatic embryogenesis receptor kinase 1 (AtSERK1) gene is expressed in developing ovules and early embryos. AtSERK1 is also transiently expressed during somatic embryogenesis. The predicted AtSERK1 protein contains an extracellular domain with a leucine zipper motif followed by five leucine-rich repeats, a proline-rich region, a single transmembrane region and an intracellular kinase domain. The AtSERK1 cDNA was fused to two different variants of green fluorescent protein (GFP), a yellow-emitting GFP (YFP) and a cyan-emitting GFP (CFP), and transiently expressed in both plant protoplasts and insect cells. Using confocal laser scanning microscopy it was determined that the AtSERK1-YFP fusion protein is targeted to plasma membranes in both plant and animal cells. The extracellular leucine-rich repeats, and in particular the N-linked oligosaccharides that are present on them appear to be essential for correct localization of the AtSERK1-YFP protein. The potential for dimerization of the AtSERK1 protein was investigated by measuring the YFP/CFP fluorescence emission ratio using fluorescence spectral imaging microscopy. This ratio will increase due to fluorescence resonance energy transfer if the AtSERK1-CFP and AtSERK1-YFP fusion proteins interact. In 15 % of the cells the YFP/CFP emission ratio for plasma membrane localized AtSERK1 proteins was enhanced. Yeast-protein interaction experiments confirmed the possibility for AtSERK1 homodimerization. Elimination of the extracellular leucine zipper domain reduced the YFP/CFP emission ratio to control levels indicating that without the leucine zipper domain AtSERK1 is monomeric.
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Affiliation(s)
- K Shah
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen, The Netherlands
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26
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Pozzetto U, Facchiano A, Serino F. Rational design of biologically active peptides: inhibition of T cell activation through interference with CD4 function. Transplant Int (2000) 13 [Suppl 1]: S306-S310. Transpl Int 2001; 13:456-61. [PMID: 11140247 DOI: 10.1111/j.1432-2277.2000.tb01027.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In our laboratory we generated one synthetic cyclic peptide (Pep4) and tested it in human mitogen stimulation assays (MSA) and mixed lymphocytes reactions (MLR) generating dose-response curves showing a dose-dependent inhibition of MSA up to 80% and MLR up to 98%. MSA and MLR were repeated after pre incubation of the Pep4 with each separate responder cell subset and subsequent reconstitution: these experiments showed inhibition only when the peptide was present in culture. Pep4 showed species specificity since it was ineffective in inhibiting rat MLR. Combination effect analysis with Pep4 and cyclosporine showed a combination index > 1. This rationally designed peptide (Pep4) shows powerful inhibition of human T cell activation and, although the exact mechanism is still undefined, it seems to exert its major action on the T cell surface, interfering with co receptor interaction and disrupting the same activation signal pathway inhibited by cyclosporine A.
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Affiliation(s)
- U Pozzetto
- Shock Center CNR, c/o Universitá Sacro Cuore, Via Pineta Sacchetti 526, 00168 Rome, Italy
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27
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Leitenberg D, Balamuth F, Bottomly K. Changes in the T cell receptor macromolecular signaling complex and membrane microdomains during T cell development and activation. Semin Immunol 2001; 13:129-38. [PMID: 11308296 DOI: 10.1006/smim.2000.0304] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Initiation and propagation of T cell receptor signaling pathways involves the mobilization and aggregation of a variety of signaling intermediates with the T cell receptor and associated molecules into specialized signaling complexes. Accumulating evidence suggests that differential regulation of the formation and composition of the T cell receptor macromolecular signaling complex may affect the different biological consequences of T cell activation. The regulatory mechanisms involved in the assembly of these complexes remains poorly understood, but in part is affected by the avidity of the T cell receptor ligand, co-stimulatory signals, and by the differentiation state of the T cell.
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Affiliation(s)
- D Leitenberg
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520-8011, USA
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28
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Xiong Y, Kern P, Chang H, Reinherz E. T Cell Receptor Binding to a pMHCII Ligand Is Kinetically Distinct from and Independent of CD4. J Biol Chem 2001; 276:5659-67. [PMID: 11106664 DOI: 10.1074/jbc.m009580200] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Immune recognition of pMHCII ligands by a helper T lymphocyte involves its antigen-specific T cell receptor (TCR) and CD4 coreceptor. We have characterized the binding of both molecules to the same pMHCII. The D10 alphabeta TCR heterodimer binds to conalbumin/I-A(k) with virtually identical kinetics and affinity as the single chain ValphaVbeta domain module (scD10) (Kd = 6-8 microm). The CD4 ectodomain does not alter either interaction. Moreover, CD4 alone demonstrates weak pMHCII binding (Kd = 200 microm), with no discernable affinity for the alphabeta TCR heterodimer. Hence, rather than providing a major contribution to binding energy, the critical role for the coreceptor in antigen-specific activation likely results from transient inducible recruitment of the CD4 cytoplasmic tail-associated lck tyrosine kinase to the pMHCII-ligated TCR complex.
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MESH Headings
- Antigen Presentation
- CD4 Antigens/genetics
- CD4 Antigens/metabolism
- Genes, MHC Class II
- Histocompatibility Antigens Class II
- Humans
- Kinetics
- Ligands
- Lymphocyte Activation
- Models, Immunological
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Peptides/metabolism
- Protein Binding
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Recombinant Fusion Proteins/immunology
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
- T-Lymphocytes, Helper-Inducer/immunology
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Affiliation(s)
- Y Xiong
- Laboratory of Immunobiology, Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA
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29
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Gao GF, Jakobsen BK. Molecular interactions of coreceptor CD8 and MHC class I: the molecular basis for functional coordination with the T-cell receptor. IMMUNOLOGY TODAY 2000; 21:630-6. [PMID: 11114424 DOI: 10.1016/s0167-5699(00)01750-3] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In recent years, substantial progress has been made towards understanding the molecular basis for CD8 binding to class I MHC and the coreceptor's role in cytotoxic T-cell activation. Here, we review the structural, mechanistic and functional studies that point to a model of coordination of T-cell receptor and CD8 signaling that might provide the key to cytotoxic T-cell activation.
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MESH Headings
- Animals
- CD8 Antigens/chemistry
- CD8 Antigens/metabolism
- Histocompatibility Antigens Class I/chemistry
- Histocompatibility Antigens Class I/metabolism
- Humans
- Lymphocyte Activation/immunology
- Mice
- Models, Immunological
- Models, Molecular
- Polymorphism, Genetic
- Protein Binding
- Protein Conformation
- Protein Isoforms/chemistry
- Protein Isoforms/metabolism
- Protein Structure, Tertiary
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Solubility
- Structure-Activity Relationship
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
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Affiliation(s)
- G F Gao
- Dept. of Molecular and Cellular Biology, 7 Divinity Avenue, Cambridge, Harvard University, Massachusetts, MA 02138, USA.
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30
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Papavasiliou FN, Schatz DG. Cell-cycle-regulated DNA double-stranded breaks in somatic hypermutation of immunoglobulin genes. Nature 2000; 408:216-21. [PMID: 11089977 DOI: 10.1038/35041599] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Targeted hypermutation of immunoglobulin variable region genes occurs in B cells during an immune response, and gives rise to families of related mutant antibodies which are then selected for their binding affinity to the immunizing antigen. Somatic hypermutation predominantly generates point mutations, many of which occur at specific residues (hotspots). The reaction has been linked to transcription and requires the presence of immunoglobulin enhancers, but replacement of the variable gene by heterologous sequences, or the variable region promoter by a heterologous promoter, does not interfere with the mutation process. Here we show the existence of abundant DNA double-strand breaks (DSBs) in hypermutating sequences. Generation of the DSBs is coupled to transcription, enhancer-dependent, and correlates with the appearance of nearby mutations. Furthermore, the DSBs are cell-cycle restricted, being found almost exclusively in cells that have completed, or nearly completed, DNA replication. We propose a model for somatic hypermutation in which mutations are introduced into the DNA during repair of DSBs by homologous recombination. The finding of DSBs during somatic hypermutation may help to explain the chromosomal translocations found in some B-cell tumours.
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Affiliation(s)
- F N Papavasiliou
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA
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31
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Hennecke J, Carfi A, Wiley DC. Structure of a covalently stabilized complex of a human alphabeta T-cell receptor, influenza HA peptide and MHC class II molecule, HLA-DR1. EMBO J 2000; 19:5611-24. [PMID: 11060013 PMCID: PMC305780 DOI: 10.1093/emboj/19.21.5611] [Citation(s) in RCA: 211] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An alphabeta T-cell receptor (alphabetaTCR)/hemagglutinin (HA) peptide/human leukocyte antigen (HLA)-DR1 complex was stabilized by flexibly linking the HA peptide with the human HA1.7 alphabetaTCR, to increase the local concentration of the interacting proteins once the peptide has been loaded onto the major histocompatibility complex (MHC) molecule. The structure of the complex, determined by X-ray crystallography, has a binding mode similar to that of the human B7 alphabetaTCR on a pMHCI molecule. Twelve of the 15 MHC residues contacted are at the same positions observed earlier in class I MHC/peptide/TCR complexes. One contact, to an MHC loop outside the peptide-binding site, is conserved and specific to pMHCII complexes. TCR gene usage in the response to HA/HLA-DR appears to conserve charged interactions between three lysines of the peptide and acidic residues on the TCR.
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MESH Headings
- Amino Acid Sequence
- Binding Sites/genetics
- Crystallography, X-Ray
- Drug Stability
- HLA-DR1 Antigen/chemistry
- HLA-DR1 Antigen/genetics
- Hemagglutinin Glycoproteins, Influenza Virus/chemistry
- Hemagglutinin Glycoproteins, Influenza Virus/genetics
- Humans
- In Vitro Techniques
- Macromolecular Substances
- Models, Molecular
- Molecular Sequence Data
- Protein Conformation
- Protein Engineering
- Protein Folding
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Sequence Homology, Amino Acid
- Static Electricity
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Affiliation(s)
- J Hennecke
- Department of Molecular and Cellular Biology, Harvard University, Howard Hughes Medical Institute, 7 Divinity Avenue, Cambridge, MA 02138, USA
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32
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Pozzetto U, Facchiano A, Serino F. Rational design of biologically active peptides: inhibition of T cell activation through interference with CD4 function. Transpl Int 2000. [DOI: 10.1111/j.1432-2277.2000.tb02046.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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33
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CD3 IMMUNODEFICIENCIES. Radiol Clin North Am 2000. [DOI: 10.1016/s0033-8389(22)00175-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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34
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Zapata DA, Pacheco-Castro A, Torres PS, Millán R, Regueiro JR. CD3 IMMUNODEFICIENCIES. Immunol Allergy Clin North Am 2000. [DOI: 10.1016/s0889-8561(05)70130-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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35
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Zapata DA, Pacheco-Castro A, Torres PS, Ramiro AR, San José E, Alarcón B, Alibaud L, Rubin B, Toribio ML, Regueiro JR. Conformational and biochemical differences in the TCR.CD3 complex of CD8(+) versus CD4(+) mature lymphocytes revealed in the absence of CD3gamma. J Biol Chem 1999; 274:35119-28. [PMID: 10574994 DOI: 10.1074/jbc.274.49.35119] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Mature CD4(+) and CD8(+) T lymphocytes are believed to build and express essentially identical surface alphabeta T-cell receptor-CD3 (TCR.CD3) complexes. However, TCR.CD3 expression has been shown to be more impaired in CD8(+) cells than in CD4(+) cells when CD3gamma is absent in humans or mice. We have addressed this paradox by performing a detailed phenotypical and biochemical analysis of the TCR.CD3 complex in human CD3gamma-deficient CD8(+) and CD4(+) T cells. The results indicated that the membrane TCR.CD3 complex of CD8(+) T lymphocytes was conformationally different from that of CD4(+) lymphocytes in the absence of CD3gamma. In addition, CD8(+), but not CD4(+), CD3gamma-deficient T lymphocytes were shown to contain abnormally glycosylated TCRbeta proteins, together with a smaller, abnormal TCR chain (probably incompletely processed TCRalpha). These results suggest the existence of hitherto unrecognized biochemical differences between mature CD4(+) and CD8(+) T lymphocytes in the intracellular control of alphabetaTCR. CD3 assembly, maturation, or transport that are revealed when CD3gamma is absent. Such lineage-specific differences may be important in receptor-coreceptor interactions during antigen recognition.
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Affiliation(s)
- D A Zapata
- Inmunología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain
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36
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Garcia KC. Molecular interactions between extracellular components of the T-cell receptor signaling complex. Immunol Rev 1999; 172:73-85. [PMID: 10631938 DOI: 10.1111/j.1600-065x.1999.tb01357.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural and biochemical basis of antigen recognition by the T-cell receptor (TCR)-CD3 signaling complex has been illuminated greatly over the past few years. Structural biology has contributed enormously to this understanding through the determination of crystal structures of many of the individual components of this complex, and some of the complexes. A number of general principles can be derived for the structure of the alpha beta TCR and its interaction with peptide-major histocompatibility complex (pMHC) in class I systems, as well as interaction of the CD8 co-receptor with MHC. Large buried surface areas within the protein-protein interfaces, and varying degrees of shape complementarity appear critical for modulating the stability of the multicomponent, low-affinity macromolecular complexes consisting of TCR, pMHC, CD8 or CD4, and CD3 gamma, delta, epsilon and zeta. Significant structural alterations in TCR and pMHC, upon complex formation, hint at an as yet unclear role for conformational change in both recognition and activation. Subtle chemical alterations in key peptide residues which contact the TCR can have dramatic agonist or antagonist effects on receptor activation, which correlate only loosely with the TCR/pMHC complex affinity, implying an ability of the signaling complex to "sense" fine differences in the interface. The stoichiometry of an activated TCR signaling complex is still an unresolved issue, as is the structure and disposition of the CD3 components. However, functional experiments are bridging this gap and providing us with preliminary working models of the multimeric assemblies.
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Affiliation(s)
- K C Garcia
- Department of Microbiology and Immunology, Stanford University School of Medicine, CA 94305-5124, USA.
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37
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Ulivieri C, Pacini S, Bartalini S, Valensin S, Telford JL, Baldari CT. Obligatory cross-talk with the tyrosine kinases assembled with the TCR/CD3 complex in CD4 signal transduction. Eur J Immunol 1999; 29:2625-35. [PMID: 10458777 DOI: 10.1002/(sici)1521-4141(199908)29:08<2625::aid-immu2625>3.0.co;2-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dissection of the CD4 signal transduction pathway has revealed striking similarities with the TCR/CD3 pathway. Furthermore, downstream signaling by CD4 is impaired in cells lacking surface TCR, suggesting a role for the TCR/CD3 complex in CD4 signal transduction. We have investigated the molecular basis for the dependence of CD4 signaling on TCR/CD3 expression. Using the phosphotyrosine binding domains of the Shc adaptor and the Fyn kinase, which both participate in CD4 signaling, as baits, we show that CD4 induces tyrosine phosphorylation of a subset of the proteins phosphorylated in response to TCR/CD3 engagement. The phosphoprotein patterns were dramatically altered in cells defective for TCR/CD3 expression, and were recoverable by reconstitution of correctly assembled TCR, suggesting that CD4 uses TCR/CD3-associated tyrosine kinases to signal. Among the tyrosine kinases associated with the resting TCR/CD3 complex, only Fyn is activated following CD4 engagement. The failure of Fyn to become phosphorylated in cells defective for TCR expression underlines the unique role of TCR/CD3 associated Fyn in CD4 signal transduction. While no calcium mobilization was measurable in cells defective for TCR/CD3 expression in response to CD4 engagement, the Ras/MAP kinase pathway could be partially activated. Thus, CD4 activates at least two signaling pathways, and tyrosine kinases associated with the TCR/CD3 complex are key components of one of these pathways.
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Affiliation(s)
- C Ulivieri
- Department of Evolutionary Biology, University of Siena, Siena, Italy
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38
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Liu H, Vignali DAA. Differential CD3ζ Phosphorylation Is Not Required for the Induction of T Cell Antagonism by Altered Peptide Ligands. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.2.599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
T cells recognize foreign Ags in the form of short peptides bound to MHC molecules. Ligation of the TCR:CD3 complex gives rise to the generation of two tyrosine-phosphorylated forms of the CD3 ζ-chain, pp21 and pp23. Replacement of residues in MHC-bound peptides that alter its recognition by the TCR can generate altered peptide ligands (APL) that antagonize T cell responses to the original agonist peptide, leading to altered T cell function and anergy. This biological process has been linked to differential CD3ζ phosphorylation and generation of only the pp21 phospho-species. Here, we show that T cells expressing CD3ζ mutants, which cannot be phosphorylated, exhibit a 5-fold reduction in IL-2 production and a 30-fold reduction in sensitivity following stimulation with an agonist peptide. However, these T cells are still strongly antagonized by APL. These data demonstrate that: 1) the threshold required for an APL to block a response is much lower than for an agonist peptide to induce a response, 2) CD3ζ is required for full agonist but not antagonist responses, and 3) differential CD3ζ phosphorylation is not a prerequisite for T cell antagonism.
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Affiliation(s)
- Haiyan Liu
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105; and
- †Graduate Program in Pathology and
| | - Dario A. A. Vignali
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105; and
- ‡Department of Pathology, University of Tennessee Medical Center, Memphis, TN 38163
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39
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Abstract
Exciting breakthroughs in the last two years have begun to elucidate the structural basis of cellular immune recognition. Crystal structures have been determined for full-length and truncated forms of alpha beta T cell receptor (TCR) heterodimers, both alone and in complex with their peptide-MHC (pMHC) ligands or with anti-TCR antibodies. In addition, a truncated CD8 coreceptor has been visualized with a pMHC. Aided in large part by the substantial body of knowledge accumulated over the last 25 years on antibody structure, a number of general conclusions about TCR structure and its recognition of antigen can already be derived from the relatively few TCR structures that have been determined. Small, but important, variations between TCR and antibody structures bear on their functional differences as well as on their specific antigen recognition requirements. As observed in antibodies, canonical CDR loop structures are already emerging for some of the TCR CDR loops. Highly similar docking orientations of the TCR V alpha domains in the TCR/pMHC complex appear to play a primary role in dictating orientation, but the V beta positions diverge widely. Similar TCR contact positions, but whose exact amino acid content can vary, coupled with relatively poor interface shape complementarity, may explain the flexibility and short half-lives of many TCR interactions with pMHC. Here we summarize the current state of this field, and suggest that the knowledge gap between the three-dimensional structure and the signaling function of the TCR can be bridged through a synthesis of molecular biological and biophysical techniques.
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Affiliation(s)
- K C Garcia
- Scripps Research Institute, Department of Molecular Biology, La Jolla, California 92037, USA.
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40
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Madrenas J. Differential signalling by variant ligands of the T cell receptor and the kinetic model of T cell activation. Life Sci 1999; 64:717-31. [PMID: 10075104 DOI: 10.1016/s0024-3205(98)00381-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The structural basis of T cell activation through the T cell receptor is still a major unresolved issue in T cell biology. The wealth of information on the generation and structure of T cell receptor ligands and the biochemistry of signal transduction from this receptor have been useful in the initial approach to explain how T cell activation occurs. More recently, the generation of variant T cell receptor ligands with partial agonist or antagonist properties, the determination of crystal structures for unengaged and engaged T cell receptors, and the kinetics of T cell receptor interactions with peptide:MHC molecule complexes have provided new insights on T cell receptor function. The common theme arising from these experiments is that the T cell receptor is a versatile signalling machine, with an inherent flexibility for ligand recognition that translates in different signalling patterns. Here, I will review the data on differential signalling from the T cell receptor upon recognition of partial agonist and antagonist ligands and how these data impact on a more general kinetic model of T cell receptor-mediated activation.
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Affiliation(s)
- J Madrenas
- The John P. Robarts Research Institute, and the Department of Microbiology and Immunology, University of Western Ontario, London, Canada.
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41
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Vignali DAA, Vignali KM. Profound Enhancement of T Cell Activation Mediated by the Interaction Between the TCR and the D3 Domain of CD4. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.3.1431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
CD4 plays an important role in the activation and development of CD4+ T cells. This is mediated via its bivalent interaction with MHC class II molecules and the TCR:CD3 complex through p56lck. Recent studies have implicated a third site of interaction between the membrane-proximal extracellular domains of CD4 and the TCR. Due to these multiple interactions, direct evidence for the functional importance of this extracellular association has remained elusive. Furthermore, the residues that mediate this interaction are unknown. In this study, we analyzed the function of 61 CD4 mutants. Alanine substitution of just 2 residues, either Q114/F182 or F182/F201, which are partially buried and located close to the D2/D3 interface, completely abrogated CD4 function. Direct evidence for the functional importance of TCR:CD4.D3 interaction was obtained using an anti-CD3fos:anti-CD4jun-bispecific Ab. Surprisingly, it induced strong T cell activation in hybridomas transfected with cytoplasmic-tailless CD4, despite the lack of association with either p56lck or MHC class II molecules. However, this effect was completely abrogated with the CD4 mutants Q114A/F182A or F182A/F201A. These data demonstrate that TCR:CD4.D3 interaction can have a profound effect on T cell activation and obviates the need for receptor oligomerization.
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Affiliation(s)
- Dario A. A. Vignali
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38101; and
- †Department of Pathology, University of Tennessee Medical Center, Memphis, TN 38163
| | - Kate M. Vignali
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38101; and
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Thatte J, Qadri A, Radu C, Ward ES. Molecular requirements for T cell recognition by a major histocompatibility complex class II-restricted T cell receptor: the involvement of the fourth hypervariable loop of the Valpha domain. J Exp Med 1999; 189:509-20. [PMID: 9927513 PMCID: PMC2192911 DOI: 10.1084/jem.189.3.509] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/1998] [Revised: 10/20/1998] [Indexed: 11/22/2022] Open
Abstract
The role of two central residues (K68, E69) of the fourth hypervariable loop of the Valpha domain (HV4alpha) in antigen recognition by an MHC class II-restricted T cell receptor (TCR) has been analyzed. The TCR recognizes the NH2-terminal peptide of myelin basic protein (Ac1-11, acetylated at NH2 terminus) associated with the class II MHC molecule I-Au. Lysine 68 (K68) and glutamic acid 69 (E69) of HV4alpha have been mutated both individually and simultaneously to alanine (K68A, E69A). The responsiveness of transfectants bearing wild-type and mutated TCRs to Ac1-11-I-Au complexes has been analyzed in the presence and absence of expression of the coreceptor CD4. The data demonstrate that in the absence of CD4 expression, K68 plays a central role in antigen responsiveness. In contrast, the effect of mutating E69 to alanine is less marked. CD4 coexpression can partially compensate for the loss of activity of the K68A mutant transfectants, resulting in responses that, relative to those of the wild-type transfectants, are highly sensitive to anti-CD4 antibody blockade. The observations support models of T cell activation in which both the affinity of the TCR for cognate ligand and the involvement of coreceptors determine the outcome of the T cell-antigen-presenting cell interaction.
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Affiliation(s)
- J Thatte
- Center for Immunology and Department of Microbiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75235-8576, USA
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Carson RT, Desai DD, Vignali KM, Vignali2 DAA. Cutting Edge: Immunoregulation of Th Cells by Naturally Processed Peptide Antagonists. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.1.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Th cells recognize protein Ags as short peptides bound to MHC class II molecules. Altered peptide ligands can antagonize (inhibit) T cell responses to stimulatory peptides. Peptides generated by APC may contain peptide flanking residues (PFR), which lie outside the minimal binding epitope and can be recognized by the TCR. Our data show that PFR-dependent T cells were found to be potently antagonized by peptides that lack PFR and responded poorly to native protein or the immunogenic epitope delivered by a recombinant influenza virus. These data provide the first evidence that Ag processing generates both stimulatory and antagonist peptides from a single immunogenic epitope, an observation that may have important implications for T cell immunoregulation and autoimmunity.
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Affiliation(s)
- Richard T. Carson
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38101; and
| | - Dharmesh D. Desai
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38101; and
| | - Kate M. Vignali
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38101; and
| | - Dario A. A. Vignali2
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38101; and
- †Department of Pathology, University of Tennessee Medical Center, Memphis, TN 38163
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Gratton S, Julius M, Sékaly RP. lck-Independent Inhibition of T Cell Antigen Response by the HIV gp120. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.7.3551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
Binding of the HIV envelope glycoprotein gp120 to CD4 inhibits T cell activation. We have used a murine T cell clone transfected with either wild-type human CD4 or mutated forms of CD4 to characterize the pathways involved in this inhibitory effect of gp120. Ag-induced proliferation of T cell clones transfected with human CD4 was completely inhibited in the presence of gp120, even though stimulation of this clone is independent of a CD4/MHC class II interaction. In addition, our results demonstrate that the inhibition by gp120 is not due to the sequestration of lck from TCR and does not require activation of lck by gp120. This suggests that CD4 can regulate the initiation of T cell activation independently of its interaction with lck. Moreover, we demonstrate that the nonresponsiveness induced by gp120 can be reversed by soluble CD4 when added early after onset of stimulation and that gp120 exerts its inhibitory effect when cells are in the G0 ≥ 1 phase of the cell cycle.
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Affiliation(s)
- Sophie Gratton
- *Laboratoire d’Immunologie, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
- †Division of Experimental Medicine, Department of Medicine, McGill University, Montréal, Québec, Canada
| | - Michael Julius
- ‡Department of Immunology, University of Toronto and the Wellesley Hospital Research Institute, Toronto, Ontario, Canada; and
| | - Rafick-Pierre Sékaly
- *Laboratoire d’Immunologie, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
- §Département de Microbiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
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Sim BC, Lo D, Gascoigne NR. Preferential expression of TCR V alpha regions in CD4/CD8 subsets: class discrimination or co-receptor recognition? IMMUNOLOGY TODAY 1998; 19:276-82. [PMID: 9639993 DOI: 10.1016/s0167-5699(98)01257-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- B C Sim
- Scripps Research Institue, La Jolla, CA 92037, USA
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Boer J, Bonten-Surtel J, Grosveld G. Overexpression of the nucleoporin CAN/NUP214 induces growth arrest, nucleocytoplasmic transport defects, and apoptosis. Mol Cell Biol 1998; 18:1236-47. [PMID: 9488438 PMCID: PMC108836 DOI: 10.1128/mcb.18.3.1236] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/1997] [Accepted: 12/02/1997] [Indexed: 02/06/2023] Open
Abstract
The human CAN gene was first identified as a target of t(6;9)(p23;q34), associated with acute myeloid leukemia and myelodysplastic syndrome, which results in the expression of a DEK-CAN fusion gene. CAN, also called NUP214, is a nuclear pore complex (NPC) protein that contains multiple FG-peptide sequence motifs. It interacts at the NPC with at least two other proteins, the nucleoporin NUP88 and hCRM1 (exportin 1), which was recently shown to function as a nuclear export receptor. Depletion of CAN in knockout mouse embryonic cells results in cell cycle arrest in G2, followed by inhibition of nuclear protein import and a block of mRNA export. We overexpressed CAN and DEK-CAN in U937 myeloid precursor cells. DEK-CAN expression did not interfere with terminal myeloid differentiation of U937 cells, whereas CAN-overexpressing cells arrested in G0, accumulated mRNA in their nuclei, and died in an apoptotic manner. Interestingly, we found that hCRM1 and import factor p97/importin beta colocalized with the ectopically expressed CAN protein, resulting in depletion of both factors from the NPC. Overexpression of the C-terminal FG-repeat region of CAN, which contains the binding site for hCRM1, caused sequestering of hCRM1 in the nucleoplasm and was sufficient to inhibit cell growth and to induce apoptosis. These results confirm that CAN plays a crucial role in nucleocytoplasmic transport and imply an essential role for hCRM1 in cell growth and survival.
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Affiliation(s)
- J Boer
- Department of Genetics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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Abstract
Stem cell factor (SCF) binding to the c-kit receptor triggers homodimerization and intermolecular tyrosine phosphorylation of the c-kit receptor, thus initiating signal transduction. Receptor dimerization is a critical early step in this process. Prior biochemical studies of c-kit receptor dimerization have mainly used affinity cross-linking techniques, which are beset with problems including low efficiency of cross-linking and the usual requirement for radiolabeled SCF to detect the cross-linked complex. We used the fluorescence resonance energy transfer (FRET) technique to examine the effects of SCF and other hematopoietic cytokines on c-kitreceptor dimerization. The nonneutralizing anti–c-kit receptor monoclonal antibody 104D2 was directly conjugated to fluorescein isothiocyanate (FITC) or to the carbocyanine dye Cy3 and used to label cytokine-responsive human hematopoietic cell lines. The ability of SCF to induce c-kit receptor dimerization was assessed by flow cytometric analysis of FRET between the donor fluorochrome FITC and the acceptor fluorochrome Cy3. SCF induced a dose-dependent increase inc-kit receptor dimerization that correlated well with the concentrations of SCF required to stimulate cell proliferation. Receptor dimerization was detectable within 3 minutes after the addition of SCF and was maximal 30 minutes after the addition of SCF. Confocal microscopy showed redistribution of the c-kit receptor (from a diffuse distribution on the cell surface to “caps” at one end of the cell) within 3 minutes after SCF addition, followed by receptor internalization. Reappearance of the c-kit receptor on the cell surface required new protein synthesis, suggesting that thec-kit receptor is not recycled to the cell surface after internalization. Finally, erythropoietin (Epo), but not the structurally and functionally related cytokine thrombopoietin (Tpo), stimulated c-kit receptor dimerization detectable by FRET, and tyrosine phosphorylation of the c-kit receptor. These results suggest that exposure to Epo can activate the c-kit receptor and provide further evidence for cross-talk between the Epo andc-kit receptors in human hematopoietic cell lines. Studies with progeny of burst-forming unit-erythroid (BFU-E) suggest that the FRET technique is sufficiently sensitive to detectc-kit receptor dimerization on normal human hematopoietic cells.
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Abstract
AbstractStem cell factor (SCF) binding to the c-kit receptor triggers homodimerization and intermolecular tyrosine phosphorylation of the c-kit receptor, thus initiating signal transduction. Receptor dimerization is a critical early step in this process. Prior biochemical studies of c-kit receptor dimerization have mainly used affinity cross-linking techniques, which are beset with problems including low efficiency of cross-linking and the usual requirement for radiolabeled SCF to detect the cross-linked complex. We used the fluorescence resonance energy transfer (FRET) technique to examine the effects of SCF and other hematopoietic cytokines on c-kitreceptor dimerization. The nonneutralizing anti–c-kit receptor monoclonal antibody 104D2 was directly conjugated to fluorescein isothiocyanate (FITC) or to the carbocyanine dye Cy3 and used to label cytokine-responsive human hematopoietic cell lines. The ability of SCF to induce c-kit receptor dimerization was assessed by flow cytometric analysis of FRET between the donor fluorochrome FITC and the acceptor fluorochrome Cy3. SCF induced a dose-dependent increase inc-kit receptor dimerization that correlated well with the concentrations of SCF required to stimulate cell proliferation. Receptor dimerization was detectable within 3 minutes after the addition of SCF and was maximal 30 minutes after the addition of SCF. Confocal microscopy showed redistribution of the c-kit receptor (from a diffuse distribution on the cell surface to “caps” at one end of the cell) within 3 minutes after SCF addition, followed by receptor internalization. Reappearance of the c-kit receptor on the cell surface required new protein synthesis, suggesting that thec-kit receptor is not recycled to the cell surface after internalization. Finally, erythropoietin (Epo), but not the structurally and functionally related cytokine thrombopoietin (Tpo), stimulated c-kit receptor dimerization detectable by FRET, and tyrosine phosphorylation of the c-kit receptor. These results suggest that exposure to Epo can activate the c-kit receptor and provide further evidence for cross-talk between the Epo andc-kit receptors in human hematopoietic cell lines. Studies with progeny of burst-forming unit-erythroid (BFU-E) suggest that the FRET technique is sufficiently sensitive to detectc-kit receptor dimerization on normal human hematopoietic cells.
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Zamoyska R. CD4 and CD8: modulators of T-cell receptor recognition of antigen and of immune responses? Curr Opin Immunol 1998; 10:82-7. [PMID: 9523116 DOI: 10.1016/s0952-7915(98)80036-8] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The response of T cells to antigen involves the participation of a number of distinct receptor-ligand engagements. The major players in the recognition of complexes of major histocompatibility complex molecules and peptide antigens are the T-cell receptors and the co-receptors CD4 and CD8. Progress in understanding the physical structures of these molecules, and how complexes between them are formed, is helping our understanding of how they participate in regulating the signals transduced to T cells.
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Affiliation(s)
- R Zamoyska
- National Institute for Medical Research, London, UK.
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50
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Carson RT, Vignali KM, Woodland DL, Vignali DA. T cell receptor recognition of MHC class II-bound peptide flanking residues enhances immunogenicity and results in altered TCR V region usage. Immunity 1997; 7:387-99. [PMID: 9324359 DOI: 10.1016/s1074-7613(00)80360-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Naturally processed MHC class II-bound peptides possess ragged NH2 and COOH termini. It is not known whether these peptide flanking residues (PFRs), which lie outside the MHC anchor residues, are recognized by the TCR or influence immunogenicity. Here we analyzed T cell responses to the COOH-terminal PFR of the H-2A(k) immunodominant epitope of hen egg lysozyme (HEL) 52-61. Surprisingly, the majority of T cells were completely dependent on, and specific for, the COOH-terminal PFR of the immunogen. In addition, there were striking correlations between TCR V beta usage and PFR dependence. We hypothesize that the V alpha CDR1 region recognizes NH2-terminal PFRs, while the V beta CDR1 region recognizes COOH-terminal PFRs. Last, peptides containing PFRs were considerably more immunogenic and mediated a greater recall response to the HEL protein. These results demonstrate that PFRs, which are a unique characteristic of peptides bound to MHC class II molecules, can have a profound effect on TCR recognition and T cell function. These data may have important implications for peptide-based immunotherapy and vaccine development.
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Affiliation(s)
- R T Carson
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101, USA
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