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Query: UNIPROT:P06889 (Mol)
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It has previously been shown that the Epstein-Barr virus (EBV) genome may be detected in some thymic tumors. We have investigated specimens of normal thymus, thymitis with lymphoid hyperplasia and a large spectrum of thymic epithelial tumors obtained from european patients for the presence of EBV genome by in situ hybridization and DNA-blotting methods. Cell lines established from seven of the thymic tumors were also tested for EBV. No EBV genome was demonstrated in any of the tumors examined, which included various types of thymoma and thymic carcinomas, nor in the non-neoplastic thymic specimens. However, unlike previous reports, no examples of lymphoepithelial-like thymic carcinoma, nor specimen from Asian patients were included in this study. We suggest that EBV is linked to a specific epithelial tumor type, namely the lymphoepithelial-like carcinoma, regardless of its site, and not to thymic tumors in general.
Virchows Arch B Cell Pathol Incl Mol Pathol 1990
PMID:Absence of the Epstein-Barr virus genome in the normal thymus, thymic epithelial tumors, thymic lymphoid hyperplasia in a European population. 198 4

109 malignant lymphomas were surveyed by Southern blot analysis and polymerase chain reaction (PCR) for Epstein-Barr virus (EBV) DNA and compared with 16 examples of non-neoplastic lymphadenopathy and 4 normal thymuses. In specimens positive by the method of Southern and PCR, in situ hybridization studies were performed on formalin-fixed, paraffin-embedded sections. By Southern blot analysis, two of seven Hodgkin's disease samples (29%) (one of mixed cellularity and the other of lymphocyte predominance type), three of 56 B-cell lymphomas (5.6%) and five of 46 T-cell lymphomas (11%) demonstrated EBV DNA. However, the 16 examples of lymphadenitis and the 4 normal thymuses showed no EBV DNA. With PCR, EBV DNA was identified in one B-cell lymphoma, nine T-cell lymphomas, ten lymphadenitis specimens and two of the normal thymus, in addition to the positive specimens determined by the Southern blotting method. These results indicate that the presence of EBV DNA is not related to lymphoid malignancy, but enhancement of the DNA is demonstrated in some neoplastic conditions. By in situ hybridization, EBV genomes were not detected in all PCR-positive cases, but only in those positive by Southern blot analysis.
Virchows Arch B Cell Pathol Incl Mol Pathol 1990
PMID:Analysis of Epstein-Barr viral genomes in lymphoid malignancy using Southern blotting, polymerase chain reaction and in situ hybridization. 198 7

Transgenic mouse lines carrying the N-myc oncogene deregulated by the immunoglobulin heavy-chain enhancer spontaneously develop B-lymphoid tumors (R. Dildrop, A. Ma, K. Zimmerman, E. Hsu, A. Tesfaye, R. DePinho, and F. W. Alt, EMBO J. 8:1121-1128, 1989; H. Rosenbaum, E. Webb, J. M. Adams, S. Cory, and A. W. Harris, EMBO J. 8:749-755). Permanent cell lines derived from these tumors (E mu-N-myc cell lines) express extremely high levels of the N-myc transgene but little or no detectable endogenous N-myc or c-myc. We have employed nuclear run-on assays to show that down-regulation of endogenous N- and c-myc expression occurs at the transcriptional level. To determine whether the lack of endogenous myc gene transcription is a direct effect of high-level N-myc transgene expression, we have generated Abelson murine leukemia virus (A-MuLV)-transformed cell lines from prelymphomatous E mu-N-myc mice (A-MuLV/E mu-N-myc cell lines). Although these A-MuLV/E mu-N-myc lines express very high levels of the N-myc transgene, they continue to transcribe the endogenous c-myc gene. These findings demonstrate that high-level N-myc gene expression alone does not necessarily lead to down-regulation of endogenous myc gene expression and suggest that events associated with transformation by N-myc may be critical to this process.
Mol Cell Biol 1991 Jan
PMID:Mechanism of endogenous myc gene down-regulation in E mu-N-myc tumors. 198 38

Xenopus oocytes, arrested in G2 before the first meiotic division, accumulate histone mRNA and protein in the absence of chromosomal DNA replication and therefore represent an attractive biological system in which to examine histone gene expression uncoupled from the cell cycle. Previous studies have shown that sequences necessary for maximal levels of transcription in oocytes are present within 200 bp at the 5' end of the transcription initiation site for genes encoding each of the five major Xenopus histone classes. We have defined by site-directed mutagenesis individual regulatory sequences and characterized DNA-binding proteins required for histone H2B gene transcription in injected oocytes. The Xenopus H2B gene has a relatively simple promoter containing several transcriptional regulatory elements, including TFIID, CBP, and ATF/CREB binding sites, required for maximal transcription. A sequence (CTTTACAT) in the H2B promoter resembling the conserved octamer motif (ATTTGCAT), the target for cell-cycle regulation of a human H2B gene, is not required for transcription in oocytes. Nonetheless, substitution of a consensus octamer motif for the variant octamer element activates H2B transcription. Oocyte factors, presumably including the ubiquitous Oct-1 factor, specifically bind to the consensus octamer motif but not to the variant sequence. Our results demonstrate that a transcriptional regulatory element involved in lymphoid-specific expression of immunoglobulin genes and in S-phase-specific activation of mammalian H2B histone genes can activate transcription in nondividing amphibian oocytes.
Mol Cell Biol 1991 Feb
PMID:A variant octamer motif in a Xenopus H2B histone gene promoter is not required for transcription in frog oocytes. 199 Feb 76

cDNAs for the murine lyn protein tyrosine kinase gene were cloned from mouse bone marrow-derived monocytic cells. Comparison of the human and murine genes demonstrated a 94% homology in peptide sequence. Comparable to the human gene, murine lyn was found to be expressed in myeloid and B-lymphoid lineage cells. During the cloning, two types of cDNAs were obtained that differed by the presence (lynA) or absence (lynB) of 63 bp within the amino-terminal coding region of the gene. The genomic structure of the murine lyn gene demonstrates that the two types of lyn transcripts are derived from alternative splicing utilizing an internal splice donor site. Transcripts for both forms were found to be expressed in myeloid cells. lyn-specific antisera detected comparable levels of proteins of 56 and 53 kDa in hematopoietic cells. these 56- and 53-kDa proteins comigrated with proteins produced by in vitro translation or in vivo expression of the lynA and lynB cDNAs, respectively. The two forms had comparable in vitro kinase activities in immunoprecipitates and showed similar peptide patterns, with partial V8 digestion of the in vitro-phosphorylated proteins. The potential significance of the two lyn proteins is discussed.
Mol Cell Biol 1991 May
PMID:Hematopoietic cells express two forms of lyn kinase differing by 21 amino acids in the amino terminus. 201 60

Recent studies have demonstrated the presence and the regulatory function of some neuropeptides in the immune system. In the present study, we have used labeled cholecystokinin (26-33) amide to characterize high affinity cholecystokinin (CCK) binding sites on a human JURKAT lymphoma cell line. Binding was temperature dependent, saturable, and specific. Analysis of the data demonstrated a single class of binding sites with high affinity for the ligand (Kd approximately 3.2 +/- 0.5 x 10(-11) M) and a binding capacity of 0.42 fmol/10(6) cells (approximately 300 sites/cell). These CCK binding sites displayed a typical CCK-B pharmacological profile, established by use of several agonists and antagonists selective for the CCK receptor types, namely compound L-364,718, the Merck CCK antagonist selective for the peripheral CCK receptor (CCK-A), and compound L-365,260, the Merck CCK antagonist selective for the central CCK receptor (CCK-B). The CCK cyclic analogue recently developed in our laboratory that is highly selective for the CCK-B receptor (i.e., JMV320) also showed high affinity for the CCK receptor on the JURKAT cell line. The presence of CCK-B-like binding sites on a lymphoid cell line could provide a useful model for pharmacological characterization of CCK-B binding sites and could contribute to a better understanding of their regulation.
Mol Pharmacol 1991 May
PMID:Pharmacological characterization of type B cholecystokinin binding sites on the human JURKAT T lymphocyte cell line. 203 33

Protein kinases have been implicated in a number of regulatory mechanisms including signal transduction in many cells. To address the possibility that the large granular lymphocyte (LGL) also uses one or more unique protein kinases for LGL functions, an efficient method was developed to obtain partial cDNA clones for putative protein kinases from a rat LGL tumor cell line, RNK. Using the polymerase chain reaction (PCR), one hundred and nine amplified DNA segments were cloned and sequenced from a RNK cDNA library. One hundred and eight of these segments were putative protein kinases based on their deduced sequences. Among these were nine putative protein kinases, seven of which were putative tyrosine kinases and two were putative serine kinases. Only four of the putative kinases identified in this study were identical, or nearly identical, to previously published protein kinases. The deduced amino acid sequences of the remaining clones differed by seven or more amino acid residues in the amplified segments from all known protein kinase, and were considered to be novel putative protein kinases. Two of the five novel putative kinases showed lymphoid-restricted patterns of expression on Northern analyses. The method described in this paper provides an efficient cloning strategy for novel protein kinases, and is similar to that published in a previous report. Although the PCR primers used in this report differ only slightly from those in the previous report, we used a much higher annealing temp (50 degrees C) than in the previous report (37 degrees C), which may in part account for our higher yield of putative protein kinase sequences.
Mol Immunol
PMID:Novel putative protein kinase clones from a rat large granular lymphocyte tumor cell line. 206 20

We examined a series of extrachromosomal DNA substrates for V(D)J recombination under replicating and nonreplicating conditions. Complete and partial replications were examined by monitoring the loss of prokaryote-specific adenine methylation at 14 to 22 MboI-DpnI restriction sites (GATC) on the substrates. Some of these sites are within 2 bases of the signal sequence ends. We found that neither coding joint nor signal joint formation requires substrate replication. After ruling out replication as a substrate requirement, we determined whether replication had any effect on the efficiency of V(D)J recombination. Quantitation of V(D)J recombination efficiency on nonreplicating substrates requires some method of monitoring the entry of substrate molecules into the cells. We devised such a method by monitoring DNA repair of substrates into which we had substituted deoxyuridine for 10 to 20% of the thymidine nucleotides in the DNA. The substrates which enter the lymphoid cells were repaired efficiently in vivo by the eukaryotic uracil DNA repair system. Upon plasmid harvest, we distinguished repaired (entered) from unrepaired (not entered) plasmids by cleaving unrepaired molecules with uracil DNA glycoylase and Escherichia coli endonuclease IV in vitro. This method of monitoring DNA entry does not appear to underestimate or overestimate the amount of DNA entry. By using this method, we found no significant quantitative effect of DNA replication on V(D)J recombination efficiency.
Mol Cell Biol 1991 Aug
PMID:V(D)J recombination: evidence that a replicative mechanism is not required. 207 2

The dynamic process in rat thymocyte restoration after their destruction by glucocorticoid (GC) administration was examined. Thymus weight and thymocyte count became minimal 4-5 days after the administration. Then the thymus took a course of recovery. Endogenous DNA synthesis in thymocytes, reflecting their proliferation within thymus, decreased for 4 days but began to increase 6-8 days after GC treatment. Thymocyte responsiveness to soybean lectin (SBL), a possible stimulator for T-cell-precursors, showed elevation 4-5 days after the treatment. A marked decrease of lymphocytes in the cortex and unclearness of cortico-medullary junction were observed 2-3 days after GC treatment. Clusters of small lymphoid cells, which possibly contained SBL-responding cells, were found in the subcapsular area 4 days after the treatment and successively, large lymphocytes became visible in the same area. Thereafter, small lymphocytes in the cortical mid and deep zones increased, and cortico-medullary junction was restored. These histological features are discussed from the view of correspondence with the dynamic changes of endogenous DNA synthesis and SBL responsiveness in the thymocytes after GC administration.
Cell Mol Biol 1990
PMID:Rat thymus reconstitution after thymocyte destruction by glucocorticoid treatment--from the view of endogenous DNA synthesis and soybean lectin responsiveness in thymocytes. 208 23

The immunoglobulin genes have B-cell-specific promoter and enhancer elements. The regulation of these elements is thought to be mediated to a large degree by the trans-activating factor oct-2, which binds the octamer element (ATTTGCAT). We have further examined the role of this octamer element in directing the lymphoid-specific expression of the immunoglobulin H enhancer. No direct relationship was found between the levels of expression of the Cmu gene and oct-2. Indeed, variable amounts of oct-2 were detected in all of the hemopoietic lineage cells tested in this study.
Mol Cell Biol 1990 Mar
PMID:Octamer-binding proteins in diverse hemopoietic cells. 210 71


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