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Abstract
When most full-grown, follicle cell-invested oocytes from Xenopus laevis are placed in an appropriate culture medium, they resume growth and remain physiologically healthy for at least 2-3 weeks. Rates of growth by full-grown oocytes in vitro generally approximate and can even exceed the most rapid growth rate achieved by vitellogenic oocytes in vivo. Resumption of oocyte growth can be correlated with the loss of investing follicle cells, which under normal conditions appear to interfere with vitellogenin and nutrient access to the oocyte. The final size reached by the oocyte within the ovary is thus not an intrinsic property of the oocyte but is extrinsically imposed by the somatic environment.
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Affiliation(s)
- R A Wallace
- Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
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2
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Misulovin Z, Yang XW, Yu W, Heintz N, Meffre E. A rapid method for targeted modification and screening of recombinant bacterial artificial chromosome. J Immunol Methods 2001; 257:99-105. [PMID: 11687243 DOI: 10.1016/s0022-1759(01)00452-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Modification of bacterial artificial chromosomes (BACs) has been a useful method to produce genomic DNA fragments for studying gene expression and function in vitro and in vivo. The original technique involved restrictions for BAC modification and required multiple cloning steps to target sequences into the shuttle vector. Selection and screening of BAC recombinants was accomplished by drug resistance and Southern blotting. We have developed a PCR-based method for producing the modified shuttle vectors and for screening for BACs carrying homologous integrants. The combination of these techniques allows for rapid and easy targeted BAC sequence deletion or insertion.
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Affiliation(s)
- Z Misulovin
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10021-6399, USA
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3
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Yu W, Nagaoka H, Misulovin Z, Meffre E, Suh H, Jankovic M, Yannoutsos N, Casellas R, Besmer E, Papavasiliou F, Qin X, Nussenzweig MC. RAG expression in B cells in secondary lymphoid tissues. Cold Spring Harb Symp Quant Biol 2001; 64:207-10. [PMID: 11232286 DOI: 10.1101/sqb.1999.64.207] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- W Yu
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021, USA
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4
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Abstract
The mannose receptor (MR) binds foreign and host ligands through interactions with their carbohydrates. Two portions of MR have distinct carbohydrate recognition properties. One is conferred by the amino-terminal cysteine-rich domain (Cys-MR), which plays a critical role in binding sulfated glycoproteins including pituitary hormones. The other is achieved by tandemly arranged C-type lectin domains that facilitate carbohydrate-dependent uptake of infectious microorganisms. This dual carbohydrate binding specificity enables MR to bind ligands by interacting with both sulfated and non-sulfated polysaccharide chains. We previously determined crystal structures of Cys-MR complexed with 4-SO(4)-N-acetylglucosamine and with an unidentified ligand resembling Hepes (N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]). In continued efforts to elucidate the mechanism of sulfated carbohydrate recognition by Cys-MR, we characterized the binding affinities between Cys-MR and potential carbohydrate ligands using a fluorescence-based assay. We find that Cys-MR binds sulfated carbohydrates with relatively high affinities (K(D)=0.1 mM to 1.0 mM) compared to the affinities of other lectins. Cys-MR also binds Hepes with a K(D) value of 3.9 mM, consistent with the suggestion that the ligand in the original Cys-MR crystal structure is Hepes. We also determined crystal structures of Cys-MR complexed with 3-SO(4)-Lewis(x), 3-SO(4)-Lewis(a), and 6-SO(4)-N-acetylglucosamine at 1.9 A, 2.2 A, and 2.5 A resolution, respectively, and the 2.0 A structure of Cys-MR that had been treated to remove Hepes. The conformation of the Cys-MR binding site is virtually identical in all Cys-MR crystal structures, suggesting that Cys-MR does not undergo conformational changes upon ligand binding. The structures are used to rationalize the binding affinities derived from the biochemical studies and to elucidate the molecular mechanism of sulfated carbohydrate recognition by Cys-MR.
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Affiliation(s)
- Y Liu
- Division of Biology 156-29, California Institute of Technology, Pasadena, 91125, USA
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5
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Guo M, Gong S, Maric S, Misulovin Z, Pack M, Mahnke K, Nussenzweig MC, Steinman RM. A monoclonal antibody to the DEC-205 endocytosis receptor on human dendritic cells. Hum Immunol 2000; 61:729-38. [PMID: 10980384 DOI: 10.1016/s0198-8859(00)00144-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
DEC-205 is a multilectin receptor for adsorptive endocytosis, expressed in mouse dendritic cells (DC) and some epithelia. DEC-205 is homologous to the macrophage mannose receptor (MMR). A cDNA for murine DEC-205 was used to identify 3 overlapping human DEC-205 clones from a lymphocyte library. The human homologue is a transmembrane protein of 1722 aminoacids with 10 externally disposed C-type lectin domains having 77% identity to the mouse counterpart. The NH(2) terminal cysteine-rich and fibronectin type II domains were expressed and used to immunize mice. A hybridoma, MG38, which specifically recognized the immunogen was obtained from a DEC-205 knockout mouse. The antibody precipitated a 205 kD protein from metabolically labeled, monocyte-derived DCs. MG38 labeled mature monocyte-derived DCs but showed weak or no labeling of other peripheral blood mononuclear cells. In tissue sections, MG38 identified DEC-205 on thymic cortical epithelium and DCs in the thymic medulla and tonsillar T cell areas. In contrast, an anti-MMR antibody stained DEC-205 negative, macrophages in the thymus cortex, the trabeculae of the thymus and tonsil, as well as efferent lymphatics in the tonsil. Therefore, the MG38 anti-DEC-205 antibody is useful for identifying DCs and reveals clear differences in sites where MMR and DEC-205 are expressed in lymphoid tissues.
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Affiliation(s)
- M Guo
- Laboratory of Molecular Immunology, Rockefeller University, New York, New York, USA
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6
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Leteux C, Chai W, Loveless RW, Yuen CT, Uhlin-Hansen L, Combarnous Y, Jankovic M, Maric SC, Misulovin Z, Nussenzweig MC, Feizi T. The cysteine-rich domain of the macrophage mannose receptor is a multispecific lectin that recognizes chondroitin sulfates A and B and sulfated oligosaccharides of blood group Lewis(a) and Lewis(x) types in addition to the sulfated N-glycans of lutropin. J Exp Med 2000; 191:1117-26. [PMID: 10748230 PMCID: PMC2193175 DOI: 10.1084/jem.191.7.1117] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The mannose receptor (MR) is an endocytic protein on macrophages and dendritic cells, as well as on hepatic endothelial, kidney mesangial, tracheal smooth muscle, and retinal pigment epithelial cells. The extracellular portion contains two types of carbohydrate-recognition domain (CRD): eight membrane-proximal C-type CRDs and a membrane-distal cysteine-rich domain (Cys-MR). The former bind mannose-, N-acetylglucosamine-, and fucose-terminating oligosaccharides, and may be important in innate immunity towards microbial pathogens, and in antigen trapping for processing and presentation in adaptive immunity. Cys-MR binds to the sulfated carbohydrate chains of pituitary hormones and may have a role in hormonal clearance. A second feature of Cys-MR is binding to macrophages in marginal zones of the spleen, and to B cell areas in germinal centers which may help direct MR-bearing cells toward germinal centers during the immune response. Here we describe two novel classes of carbohydrate ligand for Cys-MR: chondroitin-4 sulfate chains of the type found on proteoglycans produced by cells of the immune system, and sulfated blood group chains. We further demonstrate that Cys-MR interacts with cells in the spleen via the binding site for sulfated carbohydrates. Our data suggest that the three classes of sulfated carbohydrate ligands may variously regulate the trafficking and function of MR-bearing cells.
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Affiliation(s)
- C Leteux
- The Glycosciences Laboratory, Imperial College School of Medicine, Northwick Park Hospital, Harrow HA1 3UJ, United Kingdom
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7
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Yu W, Misulovin Z, Suh H, Hardy RR, Jankovic M, Yannoutsos N, Nussenzweig MC. Coordinate regulation of RAG1 and RAG2 by cell type-specific DNA elements 5' of RAG2. Science 1999; 285:1080-4. [PMID: 10446057 DOI: 10.1126/science.285.5430.1080] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
RAG1 and RAG2 are essential for V(D)J recombination and lymphocyte development. These genes are thought to encode a transposase derived from a mobile genetic element that was inserted into the vertebrate genome 450 million years ago. The regulation of RAG1 and RAG2 was investigated in vivo with bacterial artificial chromosome (BAC) transgenes containing a fluorescent indicator. Coordinate expression of RAG1 and RAG2 in B and T cells was found to be regulated by distinct genetic elements found on the 5' side of the RAG2 gene. This observation suggests a mechanism by which asymmetrically disposed cis DNA elements could influence the expression of the primordial transposon and thereby capture RAGs for vertebrate evolution.
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Affiliation(s)
- W Yu
- Laboratory of Molecular Immunology, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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8
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Yu W, Nagaoka H, Jankovic M, Misulovin Z, Suh H, Rolink A, Melchers F, Meffre E, Nussenzweig MC. Continued RAG expression in late stages of B cell development and no apparent re-induction after immunization. Nature 1999; 400:682-7. [PMID: 10458165 DOI: 10.1038/23287] [Citation(s) in RCA: 300] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Models of B-cell development in the immune system suggest that only those immature B cells in the bone marrow that undergo receptor editing express V(D)J-recombination-activating genes (RAGs). Here we investigate the regulation of RAG expression in transgenic mice carrying a bacterial artificial chromosome that encodes a green fluorescent protein reporter instead of RAG2. We find that the reporter is expressed in all immature B cells in the bone marrow and spleen. Endogenous RAG messenger RNA is expressed in immature B cells in bone marrow and spleen and decreases by two orders of magnitude as they acquire higher levels of surface immunoglobulin M (IgM). Once RAG expression is stopped it is not re-induced during immune responses. Our findings may help to reconcile a series of apparently contradictory observations, and suggest a new model for the mechanisms that regulate allelic exclusion, receptor editing and tolerance.
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Affiliation(s)
- W Yu
- Laboratory of Molecular Immunology, The Rockefeller University, New York, New York 10021, USA
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9
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Cortes P, Weis-Garcia F, Misulovin Z, Nussenzweig A, Lai JS, Li G, Nussenzweig MC, Baltimore D. In vitro V(D)J recombination: signal joint formation. Proc Natl Acad Sci U S A 1996; 93:14008-13. [PMID: 8943051 PMCID: PMC19485 DOI: 10.1073/pnas.93.24.14008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The first step of V(D)J recombination, specific cleavage at the recombination signal sequence (RSS), can be carried out by the recombination activating proteins RAG1 and RAG2. In vivo, the cleaved coding and signal ends must be rejoined to generate functional antigen receptors and maintain chromosomal integrity. We have investigated signal joint formation using deletion and inversion substrates in a cell free system. RAG1 and RAG2 alone or in combination were unable to generate signal joints. However, RAG1 and RAG2 complemented with nuclear extracts were able to recombine an extrachromosomal substrate and form precise signal joints. The in vitro reaction resembled authentic V(D)J recombination in being Ku-antigen-dependent.
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Affiliation(s)
- P Cortes
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, Rockefeller University, New York, NY 10021, USA
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10
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Mitchell RN, Barnes KA, Grupp SA, Sanchez M, Misulovin Z, Nussenzweig MC, Abbas AK. Intracellular targeting of antigens internalized by membrane immunoglobulin in B lymphocytes. J Exp Med 1995; 181:1705-14. [PMID: 7722449 PMCID: PMC2192014 DOI: 10.1084/jem.181.5.1705] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
An important function of membrane immunoglobulin (mIg), the B cell antigen receptor, is to endocytose limiting quantities of antigen for efficient presentation to class II-restricted T cells. We have used a panel of mIg mutants to analyze the mechanism of mIg-mediated antigen presentation, and specifically to explore the ability of mIg to target internalized antigen to intracellular processing compartments. Transfected mIgs carrying substitutions for the transmembrane Tyr587 residue fail to efficiently present specifically bound antigen. However, these mutants internalize antigen normally, and their defect cannot be attributed to a lack of mIg-associated Ig alpha/Ig beta molecules. A novel functional assay for detecting antigenic peptides in subcellular fractions shows that wild-type mIg transfectants generate class II-peptide complexes intracellularly, whereas only free antigenic peptides are detectable in the mutant mIg transfectants. Furthermore, an antigen competition assay reveals that antigen internalized by the mutant mIgs fails to enter the intracellular processing compartment accessed by wild-type mIg. Therefore, mIg specifically targets bound and endocytosed antigen to the intracellular compartment where processed peptides associate with class II molecules, and the transmembrane Tyr587 residue plays an obligatory role in this process. Targeting of internalized antigen may be mediated by receptor-associated chaperones, and may be a general mechanism for optimizing the presentation of specifically bound and endocytosed antigens in b lymphocytes and other antigen-presenting cells.
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Affiliation(s)
- R N Mitchell
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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11
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Abstract
Lymphocytes express multicomponent receptor complexes that mediate diverse antigen-dependent and antigen-independent responses. Despite the central role of antigen-independent events in B cell development, little is known about the mechanisms by which they are initiated. The association between the membrane immunoglobulin (Ig) M heavy chair (micron) and the Ig alpha-Ig beta heterodimer is now shown to be essential in inducing both the transition from progenitor to precursor B cells and subsequent allelic exclusion in transgenic mice. The cytoplasmic domain of Ig beta is sufficient to induce these early antigen-independent events by a mechanism that requires conserved tyrosine residues in this protein.
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Affiliation(s)
- F Papavasiliou
- Laboratory of Molecular Immunology, Rockefeller University, New York, NY 10021, USA
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12
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Abstract
Altered transcription is a recurrent theme in the field of cancer biology. But despite the central role of transcription in transformation, little is known about the mechanism by which dominant nuclear oncogenes induce malignancies. Homeobox family proteins are prominent examples of transcriptional regulators which control development and can function as oncogenes. Here we explore the molecular basis for transformation by this class of regulators using Oct-2 and Oct-1. We show that the DNA binding POU domains of these proteins are selective and sequence-specific transcriptional repressors that produce malignant lymphomas when they are expressed in T cells of transgenic mice. Mutagenesis experiments identified a specific set of promoters, those containing octamer regulatory elements, as the targets for transformation by selective inhibition of gene expression.
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Affiliation(s)
- X F Qin
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, Rockfeller University
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13
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Muta T, Kurosaki T, Misulovin Z, Sanchez M, Nussenzweig MC, Ravetch JV. A 13-amino-acid motif in the cytoplasmic domain of Fc gamma RIIB modulates B-cell receptor signalling. Nature 1994; 369:340. [PMID: 8183374 DOI: 10.1038/369340a0] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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14
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Abstract
RAG-1 and RAG-2 are developmentally regulated genes that are essential for the assembly of antigen receptors in lymphoid cells. Here we describe transgenic mice that carry RAG-1 and RAG-2 under the control of the proximal lck promoter. Persistent expression of RAG-1 and RAG-2 was associated with incomplete thymopoiesis and profoundly compromised cellular immunity. In addition, RAG transgenic mice rapidly developed lymphadenopathy, splenomegaly, and lymphocytic perivascular infiltrates. These effects required both RAG-1 and RAG-2, since mice that carried either gene exclusively were indistinguishable from wild-type controls. We propose that in addition to a previously documented role in V(D)J recombination, RAG-1 and RAG-2 expression must be properly regulated for completion of normal T cell development
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Affiliation(s)
- J Wayne
- Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021
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15
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Muta T, Kurosaki T, Misulovin Z, Sanchez M, Nussenzweig MC, Ravetch JV. A 13-amino-acid motif in the cytoplasmic domain of Fc gamma RIIB modulates B-cell receptor signalling. Nature 1994; 368:70-3. [PMID: 8107887 DOI: 10.1038/368070a0] [Citation(s) in RCA: 408] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The Fc receptor on B lymphocytes, Fc gamma RIIB (beta 1 isoform), helps to modulate B-cell activation triggered by the surface immunoglobulin complex. Crosslinking of membrane immunoglobulin by antigen or anti-Ig F(ab')2 antibody induces a transient increase in cytosolic free Ca2+, a rise in inositol-3-phosphate, activation of protein kinase C, and enhanced protein tyrosine phosphorylation. Crosslinking Fc gamma RIIB with the surface immunoglobulin complex confers a dominant signal that prevents or aborts lymphocyte activation triggered through the ARH-1 motifs of the signal transduction subunits Ig-alpha and Ig-beta. Here we show that Fc gamma RIIB modulates membrane immunoglobulin-induced Ca2+ mobilization by inhibiting Ca2+ influx, without changing the pattern of tyrosine phosphorylation. A 13-amino-acid motif in the cytoplasmic domain of Fc gamma RIIB is both necessary and sufficient for this effect. Tyrosine at residue 309 in this motif is phosphorylated upon co-crosslinking with surface immunoglobulin; mutation of this residue aborts the inhibitory effect of Fc gamma RIIB. This inhibition is directly coupled to signalling mediated through Ig-alpha and Ig-beta as evidenced by chimaeric IgM/alpha and IgM/beta molecules. The 13-residue motif in Fc gamma RIIB controls lymphocyte activation by inhibiting a Ca2+ signalling pathway triggered through ARH-1 motifs as a result of recruitment of novel SH2-containing proteins that interact with this Fc gamma RIIB cytoplasmic motif.
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Affiliation(s)
- T Muta
- DeWitt Wallace Research Laboratory, Sloan-Kettering Institute, New York, New York 10021
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16
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Burkhardt AL, Costa T, Misulovin Z, Stealy B, Bolen JB, Nussenzweig MC. Ig alpha and Ig beta are functionally homologous to the signaling proteins of the T-cell receptor. Mol Cell Biol 1994; 14:1095-103. [PMID: 8289790 PMCID: PMC358465 DOI: 10.1128/mcb.14.2.1095-1103.1994] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Signal transduction by antigen receptors and some Fc receptors requires the activation of a family of receptor-associated transmembrane accessory proteins. One common feature of the cytoplasmic domains of these accessory molecules is the presence is at least two YXXA repeats that are potential sites for interaction with Src homology 2 domain-containing proteins. However, the degree of similarity between the different receptor-associated proteins varies from that of T-cell receptor (TCR) zeta and Fc receptor RIIIA gamma chains, which are homologous, to the distantly related Ig alpha and Ig beta proteins of the B-cell antigen receptor. To determine whether T- and B-cell antigen receptors are in fact functionally homologous, we have studied signal transduction by chimeric immunoglobulins bearing the Ig alpha or Ig beta cytoplasmic domain. We found that Ig alpha and Ig beta cytoplasmic domains were able to activate Ca2+ flux, interleukin-2 secretion, and phosphorylation of the same group of cellular substrates as the TCR in transfected T cells. Chimeric proteins were then used to examine the minimal requirements for activation of the Fyn, Lck, and ZAP kinases in T cells. Both Ig alpha and Ig beta were able to trigger Fyn, Lck, and ZAP directly without involvement of TCR components. Cytoplasmic tyrosine residues in Ig beta were required for recruitment and activation of ZAP-70, but these amino acids were not essential for the activation of Fyn and Lck. We conclude that Fyn and Lck are able to recognize a clustered nonphosphorylated immune recognition receptor, but activation of these kinases is not sufficient to induce cellular responses such as Ca2+ flux and interleukin-2 secretion. In addition, the molecular structures involved in antigen receptor signaling pathways are conserved between T and B cells.
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Affiliation(s)
- A L Burkhardt
- Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021
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17
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Sanchez M, Misulovin Z, Burkhardt AL, Mahajan S, Costa T, Franke R, Bolen JB, Nussenzweig M. Signal transduction by immunoglobulin is mediated through Ig alpha and Ig beta. J Exp Med 1993; 178:1049-55. [PMID: 7688784 PMCID: PMC2191166 DOI: 10.1084/jem.178.3.1049] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Immunoglobulin (Ig) antigen receptors are composed of a noncovalently-associated complex of Ig and two other proteins, Ig alpha and Ig beta. The cytoplasmic domain of both of these Ig associated proteins contains a consensus sequence that is shared with the signaling proteins of the T cell and Fc receptor. To test the idea that Ig alpha-Ig beta heterodimers are the signaling components of the Ig receptor, we have studied Ig mutations that interfere with signal transduction. We find that specific mutations in the transmembrane domain of Ig that inactivate Ca2+ and phosphorylation responses also uncouple IgM from Ig alpha-Ig beta. These results define amino acid residues that are essential for the assembly of the Ig receptor. Further, receptor activity can be fully reconstituted in Ca2+ flux and phosphorylation assays by fusing the cytoplasmic domain of Ig alpha with the mutant Igs. In contrast, fusion of the cytoplasmic domain of Ig beta to the inactive Ig reconstitutes only Ca2+ responses. Thus, Ig alpha and Ig beta are both necessary and sufficient to mediate signal transduction by the Ig receptor in B cells. In addition, our results suggest that Ig alpha and Ig beta can activate different signaling pathways.
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Affiliation(s)
- M Sanchez
- Howard Hughes Medical Institute, Rockefeller University, New York, NY 10021
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18
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Abstract
Humoral immune responses are initiated by binding of antigen to the immunoglobulins (Igs) on the plasma membrane of B lymphocytes. On the cell surface, Ig forms a complex with several other proteins, two of which, MB-1 and B29, have been implicated in receptor assembly. We have reconstituted Ig receptor function in T lymphocytes by transfection of cloned receptor components. We found that efficient transport of IgM to the surface of T cells required coexpression of B29. Furthermore, IgM and B29 alone were sufficient to reconstitute antigen-specific signal transduction by Ig in the transfected T cells. Crosslinking of IgM with either antireceptor antibodies or antigen induced a calcium flux, phosphoinositol turnover, and interleukin secretion in T cells. These experiments establish a requirement for B29 in Ig receptor function, and suggest that the signaling apparatus of T and B cells is structurally homologous.
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MESH Headings
- Antibodies, Monoclonal
- B-Lymphocytes/immunology
- Blotting, Northern
- Calcium/metabolism
- Cell Line
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cloning, Molecular
- DNA/genetics
- Humans
- Immunoglobulin M/isolation & purification
- Immunoglobulin M/metabolism
- Inositol Phosphates/metabolism
- Interleukin-2/metabolism
- Kinetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Antigen, B-Cell/physiology
- Signal Transduction
- T-Lymphocytes/immunology
- Transfection
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Affiliation(s)
- T E Costa
- Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021
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19
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Rasmussen B, Noller HF, Daubresse G, Oliva B, Misulovin Z, Rothstein DM, Ellestad GA, Gluzman Y, Tally FP, Chopra I. Molecular basis of tetracycline action: identification of analogs whose primary target is not the bacterial ribosome. Antimicrob Agents Chemother 1991; 35:2306-11. [PMID: 1725100 PMCID: PMC245376 DOI: 10.1128/aac.35.11.2306] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Tetracycline analogs fell into two classes on the basis of their mode of action. Tetracycline, chlortetracycline, minocycline, doxycycline, and 6-demethyl-6-deoxytetracycline inhibited cell-free translation directed by either Escherichia coli or Bacillus subtilis extracts. A second class of analogs tested, including chelocardin, anhydrotetracycline, 6-thiatetracycline, anhydrochlortetracycline, and 4-epi-anhydrochlortetracycline, failed to inhibit protein synthesis in vitro or were very poor inhibitors. Tetracyclines of the second class, however, rapidly inhibited the in vivo incorporation of precursors into DNA and RNA as well as protein. The class 2 compounds therefore have a mode of action that is entirely distinct from the class 1 compounds, such as tetracycline that are used clinically. Although tetracyclines of the second class entered the cytoplasm, the ability of these analogs to inhibit macromolecular synthesis suggests that the cytoplasmic membrane is their primary site of action. The interaction of class 1 and class 2 tetracyclines with ribosomes was studied by examining their effects on the chemical reactivity of bases in 16S rRNA to dimethyl sulfate. Class 1 analogs affected the reactivity of bases to dimethyl sulfate. The response with class 2 tetracyclines varied, with some analogs affecting reactivity and others (chelocardin and 4-epi-anhydrotetracycline) not.
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Affiliation(s)
- B Rasmussen
- Infectious Disease/Molecular Biology Research Section, American Cyanamid, Lederle Laboratories, Pearl River, New York 10965
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20
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Chopra I, Hacker K, Misulovin Z, Rothstein DM. Sensitive biological detection method for tetracyclines using a tetA-lacZ fusion system. Antimicrob Agents Chemother 1990; 34:111-6. [PMID: 2158271 PMCID: PMC171530 DOI: 10.1128/aac.34.1.111] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A sensitive microbiological detection system for tetracyclines, utilizing an Escherichia coli strain containing a cloned tetA-lacZ gene fusion, is described. Expression of beta-galactosidase by the fusion plasmid pUB3610 remained subject to regulatory control by the TetR repressor protein, with the presence of tetracyclines in the growth medium leading to a 12-fold induction of beta-galactosidase synthesis. Because synthesis of beta-galactosidase was influenced to a small extent by the carbon source and the addition of cyclic AMP to the medium, cells were grown in the presence of cyclic AMP to enhance the sensitivity of the assay. All commonly marketed tetracyclines and some derivatives at concentrations as low as 0.1 ng/ml could be detected in the growth medium. A plate assay utilizing the fusion plasmid that detects 1 ng of tetracycline has also been developed.
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Affiliation(s)
- I Chopra
- Department of Microbiology, School of Medical Sciences, University of Bristol, United Kingdom
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Philippe J, Drucker DJ, Knepel W, Jepeal L, Misulovin Z, Habener JF. Alpha-cell-specific expression of the glucagon gene is conferred to the glucagon promoter element by the interactions of DNA-binding proteins. Mol Cell Biol 1988; 8:4877-88. [PMID: 3062372 PMCID: PMC365581 DOI: 10.1128/mcb.8.11.4877-4888.1988] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The glucagon gene is expressed specifically in the alpha cells of the pancreatic islets. We show here that 300 base pairs of the 5'-flanking region of the rat glucagon gene, linked to a chloramphenicol acetyltransferase reporter plasmid transfected into islet cell lines of different hormone-producing phenotypes, directs transcription only in glucagon-producing islet cells. Deletional and linker-scanning mutations and DNase I footprinting assays identify three transcriptional control elements within these 300 base pairs. Two of these elements (G2 and G3) independently display enhancerlike functions on both homologous and heterologous promoters in glucagon (alpha) cells, but only on heterologous promoters in insulin- (beta) and somatostatin- (delta) expressing cells, and not in non-islet cells. The proximal promoter element (G1), characterized by low intrinsic transcriptional activity, is critical for specific expression of the glucagon gene in alpha cells. However, nuclear extracts prepared from all three islet cell phenotypes give similar protection to the three control elements of the glucagon 5'-flanking sequence. We conclude that these phenotypically distinct islet cell lines all contain regulatory DNA-binding proteins interacting with the three control elements of the glucagon gene, but that factors interacting with the glucagon promoter result in transcriptional activation only in alpha cells, to restrict glucagon gene expression to these cells. These observations suggest that interactions of nuclear proteins with cis-control elements are involved in the programmed developmental expression of the islet polypeptide hormone genes.
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Affiliation(s)
- J Philippe
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston
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Shapira M, Misulovin Z, Arnon R. Specificity and cross-reactivity of synthetic peptides derived from a major antigenic site of influenza hemagglutinin. Mol Immunol 1985; 22:23-8. [PMID: 2579325 DOI: 10.1016/0161-5890(85)90030-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A synthetic peptide corresponding to sequence 138-164 of influenza hemagglutinin elicited in rabbits antibodies that recognized different parts of the peptide, namely the loop region (139-146) and the rest of the peptide, region 147-164. This was shown both by direct binding and by competitive-inhibition experiments. Individual antisera differed in their specificity. The contribution of the Asp residue at position 144 to the antigenic specificity was shown in various inhibition assays. These data are in accordance with the reported effect of the exchange Gly----Asp on the serological specificity of influenza virus.
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Abstract
Appropriately-sized oocytes from Xenopus laevis can be grown in vitro in vitellogenin-containing serum for up to 2 weeks. The source of serum appears to be unimportant. Rates of oocyte growth are somewhat better than those achieved in the presence of vitellogenin alone. Rana pipiens oocytes grow about twice as fast as X. laevis oocytes under identical conditions. The oocyte culture conditions described appear to be applicable to amphibian oocytes in general.
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Abstract
Xenpus laevis oocytes over a size range of 0.15--0.78 mm3 were dissected from their follicles and cultured in a defined medium for up to 28 days. Oocytes grew at average rates of 0.021 mm3.day-1 in the absence of insulin and 0.030 mm3.day-1 in the presence of insulin. The latter average growth rate corresponds to the fastest growth rate reported to date for oocytes in vivo. Oocytes grown in vitro can reach a size of at least 1.43 mm3, which is larger than the maximum size generally found in vivo. During growth in vitro; oocytes also acquire both a normal pigment pattern and, once they reach about 0.7 mm3, the ability to undergo complete maturation as a response to externally applied progesterone. These results show that Xenopus oocytes freed of their follicular investments are able to grow and differentiate in vitro.
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Zor U, Lamprecht SA, Misulovin Z, Koch Y, Lindner HR. Refractoriness of ovarian adenylate cyclase to continued hormonal stimulation. Biochim Biophys Acta 1976; 428:761-5. [PMID: 1276180 DOI: 10.1016/0304-4165(76)90206-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Culture of preovulatory rat follicles with luteinizing hormone, follicle-stimulating hormone or prostaglandin E2 for 24 h reduced the subsequent response of adenylate cyclase to the homologous by 80, 50 and 90%, respectively; yet follicles refractory to luteinizing hormone fully responded to follicle-stimulating hormone responded to luteinizing hormone and prostaglandin E2, and those refractory to prostaglandin E2 could be stimulated by either gonadotropin. Desensitization of the adenylate cyclase system by luteinizing hormone was achieved by hormone concentrations of 0.8--2.0 mug/ml in the medium; a lower dose of luteinizing hormone (0.4 mug/ml), though effective in stimulating adenylate cyclase, did not induce refractoriness. Prostaglandin E2 caused partial refractoriness at dose levels of 0.1--0.25 mug/ml; higher dose levels were more effective. These findings suggest that continued exposure to the preovulatory follicle to elevated levels of hormones may cause perturbations in either the interaction between the hormone and its specific receptor or in a subsequent step essential for activation of adenylate cyclase.
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