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At least 19 recordsLinked to original sources
PubMed1993

Potentially rapid walking in cellular regulatory networks using the gene-gene interference method in yeast.

The recognition that cellular regulatory circuitry is composed of antagonistic elements has made possible a new approach to the selection of regulatory genes, called the gene-gene interference method. The method was used to identify and isolate genes possibly related in an antagonistic way to protein kinase A. Two such genes were recovered: ART1 encodes a potential regulator of cytokinesis and KAI1 appears to be involved in the Start control. The principles of the gene-gene interference method are discussed, as well as its possible general use for 'walking' within the cellular regulatory networks of eukaryotes.

Amino Acid Sequence↗
PubMed1991

A new superfamily of lymphoid and melanoma cell proteins with extensive homology to Schistosoma mansoni antigen Sm23.

A novel cDNA clone termed R2 was isolated by subtractive hybridization of a cDNA library of phytohemagglutinin (PHA)/phorbol myristate acetate-stimulated Jurkat cells and by rescreening a cDNA library of PHA-stimulated peripheral blood lymphocytes. It hybridizes to a single mRNA species of about 2.2 kb, which is inducible in lymphoid cells and codes for a protein of 267 amino acids which contains four potential transmembrane domains. A computer-aided comparison showed strong homology to four other membrane proteins, the pan B cell marker CD37, the pan leukocyte marker CD53, the melanoma antigen ME491 and, surprisingly, the Schistosoma mansoni antigen Sm23. The four human proteins share a number of additional similarities in their overall structure. These include identical spacing of the transmembrane domains, similar hydrophobicity plots, possible N-linked glycosylation sites of similar number and position as well as similar distribution of the cysteine residues. The majority of these characteristics are still conserved in the evolutionary most distant member of this family, the Schistosoma mansoni antigen Sm23. Here we introduce this new protein superfamily and characterize the inducible, lymphoid-specific member R2.

Amino Acid Sequence↗
PubMed1994

Further characterization of CD82/IA4 antigen (type III surface protein): an activation/differentiation marker of mononuclear cells.

The mononuclear cell surface protein IA4 was originally identified in our lab using a mAb selected because of its strong reactivity with three lymphoblastoid variant cell lines which are HLA class I deficient, are LAK susceptible, and form a high number of conjugates with LAK effectors. We previously cloned the cDNA of the IA4 protein, coding for a 267-amino-acid type III integral membrane protein, with four transmembrane domains and three possible N-glycosylation sites. The IA4 protein belongs to the tetra span transmembrane (TST) new family of surface molecules, which also includes CD9, CD37, CD53, CD63, and TAPA-1. IA4 antigen was recently recognized as belonging to a new cluster of differentiation CD82 (International CD Workshop, Boston 1993). The IA4 antigen expression pattern at the surface of immune cells from normal donors was studied. On T lymphocytes, IA4 was barely detectable on resting cells and increased 3.5- to 7-fold following PHA or PHA+PMA stimulation. This IA4 increased expression is correlated with the morphologic change in blast cells and with the expression of activation markers such as CD2 and MHC class II antigens, therefore suggesting that IA4 is an activation marker on T lymphocytes. The expression of IA4 was low on circulating resting monocytes collected by elutriation. However, these monocytes, cultured in medium alone or with GM-CSF, acquired the morphology of macrophage and simultaneously overexpressed MHC Class II, CD14, and IA4 antigens, suggesting that IA4 is a differentiation marker for macrophages, whatever the culture conditions, either adherent (plastic culture dishes) or nonadherent (Teflon culture bags). IA4 stable transfectants of the murine mastocytoma cell line P815 were obtained and used to generate a new mAb. Competitive epitope binding studies have shown that IA4 antigen presents a dominant epitope recognized by most of the mAb prepared either in our lab or elsewhere. This dominant epitope is not shared by any of the other antigens of the TST family. Using this new mAb we were able to biochemically characterize the IA4 antigen as a 28-kDa protein, highly N-glycosylated with different patterns on various cells.

Animals↗
PubMed1993

The genes for CD37, CD53, and R2, all members of a novel gene family, are located on different chromosomes.

CD37, CD53, and R2 leukocyte surface antigens are members of a novel family of structurally related proteins. They all have four transmembrane-spanning domains with a single major extracellular loop. The CD37 is expressed on B cells and on a subpopulation of T cells. The CD53 is known as a panleukocyte marker. The R2 protein is an activation antigen of T cells. The CD37, CD53, and R2 genes were assigned with the help of human/rodent somatic cell hybrids and human-specific probes to human chromosomes 19, 1, and 11, respectively. For the regional assignment, various deletion hybrids were used to map CD37 to 19p13-q13.4, CD53 to 1p12-p31, and R2 to 11p12.

Antigens, CD↗
PubMed1995

KAI1, a metastasis suppressor gene for prostate cancer on human chromosome 11p11.2.

A gene from human chromosome 11p11.2 was isolated and was shown to suppress metastasis when introduced into rat AT6.1 prostate cancer cells. Expression of this gene, designated KAI1, was reduced in human cell lines derived from metastatic prostate tumors. KAI1 specifies a protein of 267 amino acids, with four hydrophobic and presumably transmembrane domains and one large extracellular hydrophilic domain with three potential N-glycosylation sites. KAI1 is evolutionarily conserved, is expressed in many human tissues, and encodes a member of a structurally distinct family of leukocyte surface glycoproteins. Decreased expression of this gene may be involved in the malignant progression of prostate and other cancers.

Amino Acid Sequence↗
PubMed2026

Interaction between CD82 and integrin αVβ3 selectively regulates collective movement of tumor cells via endolysosomal trafficking.

Tetraspanin CD82/KAI1 inhibits cell movement and metastasis of malignant tumors, and reduced and lost expressions of CD82 predict worse outcomes of patients with malignant tumors. Here we found that CD82 inhibits both solitary and collective movement of tumor cells. The CD82 YVAA mutation, which affects CD82 trafficking, selectively abrogates CD82-mediated inhibition of collective migration. Cilengitide, at the concentration that specifically inhibits integrin αVβ3, also selectively blocks collective movement, underscoring a promotive role of integrin αVβ3 in this mode of cell motility. In contrast, integrin αVβ5 appears non-essential for collective migration, and both αVβ3 and αVβ5 are dispensable for solitary movement on fibronectin, highlighting distinct functions of different integrins in different modes of tumor cell movement. CD82 interacts with αVβ3 and αVβ5 integrins and downregulates their protein levels, while CD82 YVAA mutation relinquishes this downregulation without disrupting CD82 interactions with these integrins. Mechanistically, CD82, but not the YVAA mutant, considerably reduces digitation junction-the structure where integrin αVβ3 localizes-and likely directs integrin αVβ3 for lysosomal degradation, thereby lowering its level and suppressing collective migration. Thus, our study reveals that i) integrin αVβ3 promotes collective movement of tumor cells, ii) CD82 counteracts this by diminishing integrin αVβ3 and its presence in microextrusions, and iii) digitation junction likely participates in collective cell movement. Our study further demonstrates that endolysosomal trafficking of CD82 and integrin αVβ3 is needed for their collective movement-regulatory activities and that coupling of metastasis suppressor CD82/KAI1 with different partners regulates different modes of cell movement.

Humans↗
PubMed1995

Molecular analyses of the association of CD4 with two members of the transmembrane 4 superfamily, CD81 and CD82.

Previously, we have shown that CD81 and CD82, two members of the transmembrane 4 superfamily, form multimolecular membrane complexes by associating with each other and with CD4 or CD8 in T cells. In the present study, we further analyzed the molecular basis of the CD4 association with CD81 and CD82 by co-precipitation experiments. First, we examined the regions of CD4 involved in the association with CD81 and CD82 by employing chimeric proteins generated from CD4 and CD2. It was confirmed that CD4, but not CD2, was capable of binding with CD81 and CD82 in transfected cells. We found that the cytoplasmic region of CD4 was sufficient for the chimeric proteins to co-precipitate CD81, while both the cytoplasmic and extracellular regions of CD4 were required for them to efficiently co-precipitate CD82. We next found, by using truncated CD4 lacking the C-terminal 31 amino acids or mutated CD4 with the cysteine residues at 394 and 397 replaced by serine, that the p56lck binding site or the covalent modification with palmitic acid was not necessary for CD4 to associate with CD81 and CD82. Finally, we found that the binding of p56lck to CD4 strongly inhibited its association with CD81 and CD82. It is, therefore, suggested that CD4 exists at least in two physical states, one associated with p56lck and another associated with CD81 and CD82 in the absence or uncoupling of p56lck.

Acylation↗
PubMed1996

Transmembrane-4 superfamily proteins CD81 (TAPA-1), CD82, CD63, and CD53 specifically associated with integrin alpha 4 beta 1 (CD49d/CD29).

Anti-alpha 4 integrin mAb coprecipitated CD81 (TAPA-1), a 25-kDa cell surface protein, from various alpha 4 beta1 -positive hemopoietic cell lines, including Molt4, Jurkat, Ramos, and alpha 4-transfected K562 (KX4C4) cells. In reciprocal experiments, the integrin alpha 4 beta 1 (VLA4, CD49d/CD29) could be reprecipitated from CD81 immunoprecipitates. Anti-alpha 4 integrin mAb also coprecipitated CD81 from the alpha 4 beta 7-positive B cell line RPMI 8866. In contrast, no CD81 was identified in alpha 2 beta 1, alpha 5 beta 1, or alpha L beta 2 immunoprecipitates. Abs to other members of the transmembrane-4 superfamily, including CD53, CD63, and CD82, also coprecipitated alpha 4 beta 1. As shown by confocal microscopy, CD81 and CD82 colocalized with alpha 4 beta 1 in cell surface clusters. The cytoplasmic domain of the alpha 4 integrin was not necessary for alpha 4 beta 1/CD81 association, nor was the association influenced by divalent cations, EDTA, integrin-activating mAb, or alpha 4 subunit cleavage. Notably, two independent alpha 4 adhesion-deficient mutants (D346E and D408E) were deficient in their ability to associate with CD81. Thus, CD81 and other transmembrane-4 superfamily members may participate in functionally relevant interactions with alpha 4 beta 1 and other integrins.

Antibodies, Monoclonal↗
PubMed1995

CD82, tetra-span-transmembrane protein, is a regulated transducing molecule on U937 monocytic cell line.

The mononuclear cell surface protein IA4, recently classified as CD82, was originally identified in our laboratory by the IA4 monoclonal antibody (mAb), because of its high expression on three lymphoblastoid, LAK-susceptible, variant cell lines. We have characterized CD82 as a new activation/differentiation marker of mononuclear cells. This protein belongs to the new family of TST proteins (tetra spans transmembrane), which includes CD9, CD37, CD53, CD63, and CD81 (TAPA-1). Here we demonstrate that cross-linking of IA4 mAbs induces an increase of intracellular free calcium in U937 cells and tyrosine phosphorylation of various proteins. Our data indicate that the intracellular calcium increase is initiated by a phospholipase C (PLC)-induced PtdIns(1,4,5)P3 second messenger followed by a more stable change, linked to extracellular calcium entry. This transducing signal was dependent on dual engagement of both CD82 and Fc receptors. Surface cross-linking of CD82 together with Fc receptors (FcRs) induces a specific long-lasting increase of intracellular calcium, whereas FcR cross-linking alone induces only a transient calcium mobilization. These results suggest that, upon cross-linking of CD82, a multimolecular complex including CD82 and FcR could be induced that is able to trigger signal transduction. We have previously shown that CD82 membrane expression is up-regulated during differentiation of human monocytes. Using U937 cells, we demonstrate here that several cytokines [interleukin-1 beta (IL-1 beta), IL-4, IL-6, IL-13, interferon-gamma, tumor necrosis factor alpha] could significantly up-regulate the surface expression of CD82 antigen, by contrast with FcR surface expression, which was up-regulated only after IFN-gamma treatments. Based on our finding of a strict dependence of CD82 activation on FcR stimulation, we suggest a putative role of CD82 in enhancing FcR-mediated activation of cells from the monocyte/macrophage lineage.

Antibodies, Monoclonal↗
PubMed1994

Mouse homologue of C33 antigen (CD82), a member of the transmembrane 4 superfamily: complementary DNA, genomic structure, and expression.

C33 Ag (CD82) is a member of the transmembrane 4 superfamily (TM4SF) and an activation Ag of T-cells. Recent studies have shown that CD82 associates with CD4 or CD8 and delivers costimulatory signals for the TCR/CD3 pathway. We have isolated cDNA and genomic clones of mouse CD82. Mouse CD82 has 266 amino acid residues with 76% identity to human CD82. The mouse CD82 gene consists of nine exons and spans more than 20 kb of genomic DNA. The genomic organization of CD82 is quite similar to that of three other TM4SF members whose genomic structures were described, i.e., Tapa-1 (CD81), CD53, and CD63. By mapping the 5' end of CD82 transcripts, we found a single major transcription initiation site 144 bp upstream of the ATG initiation codon. We also determined the sequence of the 5' flanking region of CD82 gene for about 2 kb. The 5' flanking sequence has a housekeeping promoter with potential binding motifs for various transcriptional factors. Northern blot analysis showed quite variable expression of the CD82 gene among different organs. The highest expression was seen in the spleen and the kidney. The expression was low in skeletal muscle and hardly detectable in the heart. Northern blot analysis was also carried out for CD81, CD53, and CD63. The expression of the CD81 gene was ubiquitous and similar among different organs, while that of CD53 was seen only in the spleen. The expression of the CD63 gene was ubiquitous, with the highest expression in the kidney. These results together with the comparison of the structures of 5' flanking sequences of these genes indicate distinct regulations of gene expression for these four members of TM4SF.

Amino Acid Sequence↗
PubMed1994

Association of four antigens of the tetraspans family (CD37, CD53, TAPA-1, and R2/C33) with MHC class II glycoproteins.

Four of the tetraspans family antigens expressed in B cells, CD37, CD53, TAPA-1, and R2/C33, as well as at least two other molecules, CD19 and CD21, coprecipitate with DR antigens from mild detergent lysates of human B-cell lines and tonsillar B cells. Coprecipitation and preclearing experiments indicate the existence of large multicomponent complexes containing jointly the seven components, although some "incomplete" complexes lacking some of the components may also exist. The complexes contain only a relatively small fraction of the total cellular pool of relevant molecules. The existence of these "tetraspans-DR complexes" may be related to the previously reported antiproliferative and signaling effects of antibodies against most of their components.

Antibodies, Monoclonal↗
PubMed1992

Identification of membrane antigen C33 recognized by monoclonal antibodies inhibitory to human T-cell leukemia virus type 1 (HTLV-1)-induced syncytium formation: altered glycosylation of C33 antigen in HTLV-1-positive T cells.

We isolated four monoclonal antibodies (MAbs), M38, M101, M104, and C33, which were capable of inhibiting syncytium formation induced in a human T-cell line, MOLT-4-#8, by coculture with human T-cell leukemia virus type 1 (HTLV-1)-positive human T-cell lines. The MAbs had, however, no inhibitory activity on syncytium formation induced in a human osteosarcoma line, HOS, by HTLV-1-positive T-cell lines. They also did not inhibit syncytium formation induced in MOLT-4-#8 by human immunodeficiency virus type 1-positive MOLT-4. All MAbs reacted with various human cell lines of lymphoid and nonlymphoid origins, including HTLV-1-positive T-cell lines. Furthermore, they all reacted with a murine A9 clone containing human chromosome 11 fragment q23-pter. Two MAbs, M104 and C33, immunoprecipitated a membrane antigen with the same molecular size. The antigen (henceforth called C33 antigen) was about 40 to 55 kDa in HTLV-1-negative Jurkat, CEM, MOLT-4, and normal peripheral blood CD4-positive human T cells and about 40 to 75 kDa in HTLV-1-positive C91/PL, TCL-Kan, MT-2, and in fresh HTLV-1-transformed CD4-positive human T-cell lines. Pulse-chase experiments revealed that C33 antigen was synthesized as a 35-kDa precursor that was then processed to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL. In the presence of tunicamycin, a 28-kDa protein was synthesized. The conversion from 35 kDa to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL was inhibited by monensin. Treatment with N-glycanase alone, but not with sialidase and O-glycanase in combination, completely removed the sugar moiety of C33 antigen from both HTLV-1-negative Jurkat and HTLV-1-positive C91/PL. Therefore, C33 antigen has only N-linked carbohydrates, the modification of which appears to be substantially altered in the presence of the HTLV-1 genome.

Antibodies, Monoclonal↗
PubMed1992

C33 antigen recognized by monoclonal antibodies inhibitory to human T cell leukemia virus type 1-induced syncytium formation is a member of a new family of transmembrane proteins including CD9, CD37, CD53, and CD63.

C33 Ag was originally identified by mAb inhibitory to syncytium formation induced by human T cell leukemia virus type 1. The Ag was shown to be a highly heterogeneous glycoprotein consisting of a 28-kDa protein and N-linked oligosaccharides ranging from 10 to 50 kDa. In the present study, cDNA clones were isolated from a human T cell cDNA expression library in Escherichia coli by using mAb C33. The identity of cDNA was verified by immunostaining and immunoprecipitation of transfected NIH3T3 cells with mAb. The cDNA contained an open reading frame of a 267-amino acid sequence which was a type III integral membrane protein of 29.6 kDa with four putative transmembrane domains and three putative N-glycosylation sites. The C33 gene was found to belong to a newly defined family of genes for membrane proteins, such as CD9, CD37, CD53, CD63, and TAPA-1, and was identical to R2, a cDNA recently isolated because of its strong up-regulation after T cell activation. Availability of mAb for C33 Ag enabled us to define its distribution in human leukocytes. C33 Ag was expressed in CD4+ T cells, CD19+ B cells, CD14+ monocytes, and CD16+ granulocytes. Its expression was low in CD8+ T cells and mostly negative in CD16+ NK cells. PHA stimulation enhanced the expression of C33 Ag in CD4+ T cells by about 5-fold and in CD8+ T cells by about 20-fold. PHA stimulation also induced the dramatic size changes in the N-linked sugars previously shown to accompany human T cell leukemia virus type 1-induced transformation of CD4+ T cells.

Amino Acid Sequence↗
PubMed1995

CD82, member of the tetra-span-transmembrane protein family, is a costimulatory protein for T cell activation.

It is now well documented that full activation of T cells requires a two-signal triggering that can be mimicked, in the absence of accessory cells, by co-immobilization of mAbs directed to stimulatory/accessory molecules (CD2, CD3, CD28, adhesion molecules, etc.). In this report, we describe that engagement of CD82 can delivery such a costimulatory signal for full activation of the human T cell line Jurkat, leading to strong IL-2 production and cell differentiation. The CD82 Ag, which belongs to the new tetra-span-transmembrane family (CD9, CD37, CD53, CD63, and CD81 (TAPA-1)), has been identified originally in our laboratory for its enhanced expression on three LAK-susceptible cell lines, and has been characterized as an activation/differentiation marker of mononuclear cells. Jurkat cells, stimulated in vitro by co-immobilization of anti-CD82 and anti-CD3 mAbs, produced high levels of IL-2, became strongly adherent to plastic dishes, and developed dendritic processes. These morphologic changes, associated with a total arrest of cell proliferation, were not the result of cell death but rather of cell differentiation, as shown by an increase in their metabolic activity. Costimulation through both CD82 and CD3 induced up-regulation of both IL-2 and IFN-gamma mRNA synthesis (but not of IL-4) and an increased expression of HLA class I molecules at the cell surface, which was inhibited by anti-IFN-gamma Ab.

Antibodies↗
PubMed1995

[Detection of hepatitis C virus RNA and C33c antigen in the liver tissue from hepatitis C virus infection patients with chronic liver disease].

To study the distribution of hepatitis C virus (HCV) in liver tissue and its pathogenesis, nonisotopic in situ hybridization with a digoxin labelled cDNA probe to 5'-NC region of HCV and immunohistochemical study with monoclonal anti-body of anti HCV C33c were performed on the liver tissue from 24 HCV infection patients with chronic liver disease. The results were as follows: In the liver tissue of 17 patients with HCV infection (both ELISA anti-HCV and nested PCR HCV RNA positive in serum), the positivity of HCV RNA and C33c were 82.3% (14/17) and 88.2% (15/17) respectively. In 7 patients with anti-HCV positive only HCV RNA was not detected in the liver tissue, but 4 out of these 7 cases were C33c positive. The specific signals of HCV RNA and C33c were mainly localized in the cytoplasm of hepatocytes. The distribution of the HCV infected hepatocytes was spotty, scattered or diffuse. There was no relationship between the distribution and the level of alanine transaminase or pathologic changes in liver. There were many lymphocytes and monoclear cells infitrating the periphery of HCV-infected liver cells. The results suggested that replication of HCV in the cytoplasm of hepatocytes elicits the host immune response in cells infected with HCV and this is important in the pathogenesis of HCV infection.

Adult↗