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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The T-cell surface proteins CD4 (L3T4) and CD8 (Lyt2) are first expressed on thymocytes as they undergo maturation in the thymus. Two immature T-lymphoma cell clones SL12.4 and RS4.2 which constitutively express low or undetectable levels of CD4 and CD8 were used to investigate the activation of CD4 and CD8 gene expression. The protein synthesis inhibitors cycloheximide (CHX) and pactamycin rapidly and reversibly increased CD4 and CD8 mRNA in the cloned cell lines, suggesting that a labile inhibitor protein(s) may regulate the expression of these transcripts. Cell surface CD4 and CD8 proteins were transiently detectable following a pulse of CHX. Thymic epithelial cell lines also induced CD4 and CD8 mRNA and cell surface protein, as well as TCR-alpha mRNA when co-cultivated with SL12.4 T lymphoma cells. The increase in CD4 and CD8 was modest, but stable for at least 22 cell generations after the thymic epithelial inducer cells were removed. Epithelial cells of non-thymic origin did not cause induction of these T-cell differentiation markers in SL12.4 T-lymphoma cells. Since the induction elicited by thymic epithelial cells and protein synthesis inhibitors differed dramatically in kinetics and reversibility, it is likely that these inducers act, at least in part, via different mechanisms. This lymphoma model system may be useful for analysis of molecular events which occur in immature thymocytes undergoing differentiation.
Mol Immunol
PMID:A model system for T-lymphocyte differentiation: regulation of CD4 and CD8 gene expression in SL12.4 T-lymphoma cell clones. 167 30

Expression and structural organization of tyrosine aminotransferase (TAT) gene in Morris hepatoma cell line 7777 with active and glucocorticoid-inducible TAT gene and in hepatoma 8994, where TAT gene does not function were analysed. No differences in the number of receptor macromolecules, translocation and nuclear binding of hormone-receptor complexes in hormone sensitive (7777) and resistant (8994) cell lines were demonstrated. Dexamethasone increases TAT gene transcription in 7777 cell line but not 8994. Restriction analysis of TAT gene does not reveal any differences either in structural or in regulatory regions. Gel retardation assay with cloned TAT fragment (-400 b.p.) from normal hepatocytes showed identical shift of mobility in 7777 and 8994 cell lines. Moreover, 5'-flanking sequence (-890 b.p.) of TAT gene linked to the bacterial CAT gene is transiently expressed in both cell lines. We have shown that HpaII site (-105 b.p.) of TAT gene is methylated in those cells where TAT gene does not function (thymus, spleen, Zajdela ascites hepatoma) and is demethylated in TAT gene expressing hepatoma 7777 and normal rat hepatocytes. In hepatoma 8994 there are no DNAse I hypersensitive regions, typical to functioning TAT gene from hepatoma 7777 and normal hepatocytes.
Mol Biol (Mosk)
PMID:[Differences in expression and functional organization of the rat tyrosine aminotransferase gene in two lines of Morris hepatoma, 8994 and 7777]. 167 93

Using single and double labeling immunohistochemical techniques and a large panel of monoclonal antibodies against B-cell differentiation antigens, including those newly defined at the Fourth International Leucocyte Typing Workshop, we have examined the immunophenotype and tissue distribution of human thymic B-cells. The existence of a distinct B-cell population as a constant constituent of the thymic microenvironment has been noted only recently. We found a significant population of B-lymphocytes in the thymic medulla expressing the B-cell restricted antigens CD19, CD20, CD22, CD37, CD72, CD76 and IgM and IgD. As with other extrafollicular B-lymphocytes, they differ significantly from both follicle mantle and germinal center cells in morphology and immunophenotype, which points to alternative modes of B-cell differentiation. Thymic B-cells themselves show considerable heterogeneity and a subpopulation with dendritic features and the expression of CD23 has been referred to as "asteroid" cells. Their close association with T-cells and medullary epithelial cells points to a functional role for B-cells in the thymus. A second population of B-lymphocytes together with frequent lymph follicles is found within the extrathymic perviascular space. Though separated from the medulla by a layer of epithelial cells, a clear distinction between the B-cells of these two compartments is not always possible. The intramedullary B-cell compartment shows a parallel numeric increase with the occurrence of germinal centers in the perivascular space, mostly due to an accumulation of B-cells in the medulla adjacent to these lymph follicles. Thus a close relationship between the intra- and extramedullary B-cell population of the thymus seems likely.
Virchows Arch B Cell Pathol Incl Mol Pathol 1991
PMID:Phenotype and topography of human thymic B cells. An immunohistologic study. 168 54

The dynamics of lymphoid cell subpopulations in bronchoalveolar lavage fluid (BALF) and the systemic lymphoid organs of mice after intravenous injection of B16 melanoma cells were examined with a fluorescence-activated cell sorter. The lymphoid cell subpopulations of BALF and mediastinal lymph nodes showed significant changes in numbers and proportions, while those of other lymphoid organs including inguinal lymph nodes, thymus and spleen, showed little change. In week 1, the cells with a Thy-1.2+, Lyt-1+, L3T4-, Lyt-2- phenotype and asialo-Gm1+ cells in BALF significantly increased and L3T4+ cells slightly increased in number. By week 3, the numbers of Lyt-2+ cells in BALF markedly increased in number (by about 90 times) compared with controls. The number of Thy-1.2+ cells in mediastinal lymph nodes also increased significantly by week 3. Mice that had been pretreated with an immunosuppressive dose of cyclophosphamide were also inoculated intravenously with B16 melanoma cells. In these mice, a significantly increased number of pleural tumors developed and the number of Thy-1.2+ cells in BALF was markedly reduced from week 1 to 3. The results indicate that L3T4 and Lyt-2 double negative T-cells and natural killer (NK) cells may be generated and/or mobilized to the lung in an early phase of experimental metastasis of B16 melanoma cells and that at a later stage, when multiple metastases develop, T-cells with a Lyt-2+ phenotype markedly increase, probably as an expression of a host reaction against proliferating metastatic tumor cells.
Virchows Arch B Cell Pathol Incl Mol Pathol 1990
PMID:In vivo dynamics of pulmonary lymphoid cell subpopulations generated against pulmonary metastasis: evaluation by bronchoalveolar lavage fluid. 169 54

Rubromycins, a class of quinone antibacterials, were discovered to selectively inhibit human immunodeficiency virus-1 (HIV-1) RNA-directed DNA polymerase (reverse transcriptase) (RT) activity more potently than cellular DNA polymerase alpha. beta- and gamma-rubromycin each inhibited equipotently HIV-1 RT and avian myeloblastosis virus RT, in a concentration-dependent manner, and were significantly weaker as inhibitors of calf thymus DNA polymerase alpha. These agents inhibited HIV-1 RT reversibly, were competitive with respect to template.primer, and were noncompetitive with respect to TTP. Dixon analyses yielded HIV RT Ki values of 0.27 +/- 0.014 and 0.13 +/- 0.012 microM for beta- and gamma-rubromycin, respectively. Similarly, using DNA polymerase alpha, the Ki values were 25.1 +/- 4.3 and 3.9 +/- 0.6 microM for beta- and gamma-rubromycin, respectively. Because these agents were toxic to noninfected human T lymphoid cells using concentrations at or above 6 microM, HIV-1 infectivity studies were carried out at 0.8-6 microM. At these concentrations, which are below the range expected to provide protection, no significant antiviral activity was observed. Although beta- and gamma-rubromycins did not possess sufficient HIV RT inhibitory potency or selectivity versus mammalian DNA polymerase to demonstrate antiviral activities, these studies support the hypothesis that specific molecules containing quinone functional groups can selectively inhibit viral polymerase activities over cellular polymerase activities. In addition, these studies suggest that rubromycins may be lead structures for the development of more potent and selective agents.
Mol Pharmacol 1990 Jul
PMID:Inhibition of human immunodeficiency virus-1 reverse transcriptase activity by rubromycins: competitive interaction at the template.primer site. 169 17

Mouse mammary tumor virus (MMTV) is an endogenous murine retrovirus that is expressed in the epithelial cells of the mammary and salivary glands, lungs, kidneys, and seminal vesicles and in the lymphoid cells of the spleen and thymus. Several studies have shown that the long terminal repeat (LTR) of this virus can direct the expression of reporter genes to the same tissues in transgenic mice. To determine whether multiple regulatory elements within the LTR are involved in this tissue-specific expression, we have established lines of transgenic mice containing transgenes that have deletions in the MMTV LTR. Deletions of all LTR sequences upstream of -364 or of LTR sequences from -165 to -665 both result in the expression of linked reporter genes such as the simian virus 40 early region or the bacterial enzyme chloramphenicol acetyltransferase in novel sites, such as the heart, brain, and skeletal muscle; expression of endogenous MMTV and transgenes containing the full-length LTR is not detected in these organs. Negative regulation appears to involve more than one region, since deletion of sequences between either -201 and -471 or -201 and -344, as well as sequences upstream of -364, results in inappropriate expression in heart, brain, and skeletal muscle. Therefore, a negative regulatory element(s) in the MMTV LTR can suppress transcription from the viral promoter in several different organs. This represents the first example of generalized negative regulatory elements that act in many different tissues in transgenic mice to prevent inappropriate expression of a gene.
Mol Cell Biol 1990 Nov
PMID:Negative regulation in correct tissue-specific expression of mouse mammary tumor virus in transgenic mice. 170 Feb 74

The synthesis of 2'-deoxyuridine 5'-triphosphate analogues with fluorescent residues of fluorescein and rhodamine nature at C5 of the uracil base was performed. Reverse transcriptase of avian myeloblastosis virus, DNA polymerase beta of rat liver, terminal deoxynucleotidyl transferase of calf thymus and E. coli DNA polymerase I, Klenow fragment, were shown to be capable to incorporate a nucleotide residue with fluorescent label into 3'-terminus of oligonucleotide. These fluorescent labeled oligonucleotides were used as primers for synthesis of (-)-chain of M13mp10 phage. Fluorescently labeling template-primer complexes were used for DNA sequencing.
Mol Biol (Mosk)
PMID:[Fluorescent analogs of nucleoside-5'-phosphates for the study of nucleic acids by nonradioactive methods]. 170 Dec 17

The preprotachykinin-A gene, the common gene of mRNAs encoding both substance-P (SP) and neurokinin-A (NKA), was shown to be expressed in Sprague-Dawley rat thymus by detection of specific mRNA in gel-blot analyses. In situ hybridization revealed dispersed PPT-A-labeled cells in sections from rat thymus, with a concentration of grains over a subpopulation of cells in the thymic medulla. Also, neuropeptide-Y mRNA-expressing cells were found in the rat thymus, primarily in the thymic medulla. Rat thymic extracts contained SP-like immunoreactivity (SP-LI), and the major part of the immunoreactivity coeluted with authentic SP and SP sulfoxide standards. SP-LI was also detected in human thymus, which contained between 0.09-0.88 ng SP-LI/g wet wt. Evidence for translation of preprotachykinin-A mRNA in the rat thymus was obtained from the demonstration of NKA-LI in thymic cells with an epithelial-like cell morphology. Combined with previous observations on the immunoregulatory roles of tachykinin peptides and the existence of specific receptors on immunocompetent cells, the demonstration of intrathymic synthesis of NKA suggests a role for NKA-LI peptides in T-cell differentiation in the thymus.
Mol Endocrinol 1990 Aug
PMID:Expression of preprotachykinin-A and neuropeptide-Y messenger RNA in the thymus. 170 57

A monoform antibody [anti-TFA antibody] against TFA-protein adducts (TFA-adducts) was obtained by affinity purification of a polyclonal antiserum, raised in rabbits against TFA-rabbit serum albumin, on a N-epsilon-TFA-L-lysine matrix coupled to Affi-Gel 102. The anti-TFA antibody did recognize TFA-adducts of distinct molecular mass on Western blots of hepatocyte homogenates or microsomal membranes obtained from rats pretreated with halothane. The anti-TFA antibody also recognized cross-reactive polypeptides with apparent molecular masses of 52 kDa and 64 kDa on Western blots of hepatocyte homogenates obtained from rats not treated with halothane or metabolites thereof. The 52-kDa and 64-kDa cross-reactive polypeptides were localized in the 3,000 x g particulate fraction of liver homogenates. Recognition, on Western blots, of TFA-adducts and both the 52-kDa and 64-kDa cross-reactive polypeptides by anti-TFA antibody was sensitive to competition by N-epsilon-TFA-L-lysine (IC50 less than 100 microM) and N-epsilon-acetyl-L-lysine (IC50 approximately 10 mM). Treatment with piperidine (1 M) did abolish the recognition of TFA-adducts but not that of the 52-kDa and the 64-kDa cross-reactive polypeptides by anti-TFA antibody on Western blots. In antibody-exchange experiments, anti-TFA antibody was affinity-adsorbed on Western blots to the 52-kDa or the 64-kDa cross-reactive polypeptides of the rat heart, followed by spontaneous transfer to target TFA-adducts present on Western blots of rat liver microsomal membranes. The majority of these target TFA-adducts were recognized by anti-TFA antibody transferring from the source 52-kDa or 64-kDa cross-reactive polypeptides. When examined up to 10 days after exposure of rats to a single dose of halothane, no influence on the constitutive level of expression, in the liver, of either cross-reactive polypeptide was observed. In contrast, TFA-adducts were persistent for greater than 90 hr but less than 10 days. In addition to the liver, the 52-kDa and the 64-kDa cross-reactive polypeptides were prominently expressed in the heart and the kidney and, to a much lesser degree, in the spleen, the thymus, the lung, and skeletal muscle of the rat. Considerable variation in the level of expression of the 52-kDa and the 64-kDa cross-reactive polypeptides was recognized in livers of the six human individuals tested so far.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Pharmacol 1991 Sep
PMID:Halothane metabolism: immunochemical evidence for molecular mimicry of trifluoroacetylated liver protein adducts by constitutive polypeptides. 171 32

During platelet secretion granule membrane glycoproteins are translocated to the plasma membrane. We report here the biochemical and immunohistochemical characterization of a panel of platelet-secretion-specific, CD62 and CD63 monoclonal antibodies (MoAb), which we raised to thrombin-activated platelets. The CD62 MoAb identify the alpha-granule membrane protein GMP-140, also designated platelet activation-dependent granule external membrane protein (PADGEM). The number of epitopes on thrombin-activated platelets ranged from 15,000 to 20,000. The CD63 MoAb recognize a 30-60 kDalton integral membrane protein of lysosomes. Due to its distinct localization, we have designated the CD63 antigen lysosome integral membrane protein, CD63 (LIMP-CD63). The number of epitopes on thrombin-activated platelets ranged from 9000 to 11,000. Expression of GMP-140, a member of the Selectin family (also referred as the LEC-CAM family) of adhesion molecules, and LIMP-CD63 was examined on human spleen, thymus and lymph node by immunohistochemistry. Both GMP-140 and LIMP-CD63 showed a wide distribution in lymphoid tissues; vascular endothelial cells and tissue compartments that were readily accessible to blood-borne components were uniformly positive for GMP-140 and LIMP-CD63. Furthermore, LIMP-CD63 was expressed in polymorphonuclear granulocytes and macrophages.
Virchows Arch B Cell Pathol Incl Mol Pathol 1991
PMID:Biochemical and immunohistochemical characteristics of CD62 and CD63 monoclonal antibodies. Expression of GMP-140 and LIMP-CD63 (CD63 antigen) in human lymphoid tissues. 172 56


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