Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cryptic splice donor site in the first intracytoplasmic (IC) exon of the murine Fc gamma RIIB gene generates a previously unknown Fc gamma RIIB isoform. Three membrane Fc gamma RIIB polypeptides of 37, 32, and 30 kDa were immunoprecipitated by Fc gamma RIIB-specific Abs, and three Fc gamma RIIB cDNAs of 1071, 987, and 930 bp were amplified by reverse transcriptase-PCR with Fc gamma RIIB-specific oligonucleotides from the mastocytoma cells P815. The 1071-bp cDNA contains all sequences of IC exons and encodes the 37-kDa Fc gamma RIIB1 isoform. The 930-bp cDNA lacks sequences of the first IC exon and encodes the 30-kDa Fc gamma RIIB2 isoform. The 987-bp cDNA has an 84-nucleotide deletion of the first IC exon 3' sequences. When stably transfected in the lymphoma B cells IIA1.6, or in the mast cells RBL-2H3, this cDNA encoded 32-kDa Fc gamma RIIB whose biologic properties were undistinguishable from those of Fc gamma RIIB1: they inhibited B cell activation when coaggregated to B cell receptors and capped when aggregated at 37 degrees C, but failed to mediate endocytosis or phagocytosis. Sequences responsible for capping and inhibition of internalization, previously assigned to sequences encoded by the first IC exon, can thus be mapped in the 19 N-terminal residues. These residues are highly conserved in human Fc gamma RIIB1. The 87-bp first IC exon of the human gene ends by a single splice site in the downstream intron and encodes a 19-amino acid insertion. The 32-kDa Fc gamma RIIB is the murine homologue of human Fc gamma RIIB1. We propose to name it Fc gamma RIIB1'. Fc gamma RIIB1' was expressed in myeloid and lymphoid cell lines, in normal spleen cells, and in resting or LPS-activated B cells.
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PMID:Identification, molecular cloning, biologic properties, and tissue distribution of a novel isoform of murine low-affinity IgG receptor homologous to human Fc gamma RIIB1. 868 14

The immunosuppressive drug mycophenolate mofetil (MMF) acts by releasing mycophenolic acid (MPA), which inhibits the enzyme inosine monophosphate dehydrogenase (IMPDH) and thus inhibits de novo purine synthesis. Unlike cyclosporine (CsA), MMF has no direct effect on cytokine gene expression in vitro. We examined the effect of MMF, in comparison to CsA, on in vivo production of interferon-gamma (IFN-gamma) in mice. Two stimuli for IFN-gamma induction were used: (1) allogeneic P815 mastocytoma ascites tumour cells and (2) bacterial lipopolysaccharide (LPS). The allogeneic response is dependent on clonal expansion of T cells, while the LPS response is polyclonal and T cell independent. Since major histocompatibility complex (MHC) induction in mouse kidney is IFN-gamma dependent, we assessed the in vivo induction of IFN-gamma indirectly by measuring MHC induction in mouse kidneys in three systems: radiolabelled antibody binding assay, immunoperoxidase staining in tissue sections, and Northern blotting for steady-state MHC mRNA levels. IFN-gamma steady-state mRNA levels were assessed by reverse transcriptase polymerase chain reaction (RT-PCR). In the allogeneic response, MMF (40-160 mg/kg/day) reduced the production of IFN-gamma in a dose-dependent fashion. MHC class I and II induction was reduced by 35% to 74% and 30% to 74%, respectively. However, MMF had less effect on the induction of MHC by a nonimmune stimulus, bacterial LPS, whereas CsA reduced the induction of IFN-gamma in both responses. We conclude that MMF reduces the IFN-dependent induction of MHC in vivo during specific immune responses, probably by limiting clonal expansion, while preserving nonspecific cytokine production in response to LPS.
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PMID:Mycophenolate mofetil reduces production of interferon-dependent major histocompatibility complex induction during allograft rejection, probably by limiting clonal expansion. 964 Jun 25

The mammary tumor is one of the popular neoplastic diseases in female dogs. In the present study, the expression of canine c-kit proto-oncogene in mammary tumor specimens was investigated to evaluate its potential usefulness as a tumor marker. By comparing the homology among the nucleotide sequences reported for human mouse, rat and feline c-kit c-DNA, a pair of primers was synthesized for the reverse transcriptase-polymerase chain reaction (RT-PCR) method. The RT-PCR product of canine spleen total RNA was shown to have 756 bp in size and to be highly homologous to the corresponding sequences reported for the mammalian species. The expression of c-kit transcript was detected in 11 mammary tumors of different histopathology including adenocarcinomas, benign and malignant mixed tumors. The level of the transcription in adenocarcinomas was significantly higher than those in malignant mixed tumors. Fifteen canine tumor specimens originated from various tissues were also tested for their c-kit transcript. In all of the mastocytoma samples examined, high expression of the mRNA was detected. Of other 12 tumors, only low level of RT-PCR products were detected in 5 samples, whereas no apparent amplification was observed in 7 tumors. These results indicate that the high expression of c-kit transcript is helpful for the diagnosis of canine mammary tumors.
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PMID:Frequent expression of the c-kit proto-oncogene in canine malignant mammary tumor. 987 35

Mast cells play a central role in IgE-dependent allergic responses. Although they have been reported to express only low-affinity IgG receptors and no high-affinity receptors (FcgammaRI), our recent study showed that canine mastocytoma CM-MC cells are activated by monomeric canine IgG, suggesting the presence of FcgammaRI on CM-MC cells. In the present study, we measured the affinity of canine IgG with CM-MC cells, determined the presence of the FcgammaRI protein and mRNA, and identified the cDNA sequence of it. The results showed that (7.5+/-3.1)x10(4) receptor molecules are expressed on a CM-MC cell with a Ka of (9.1+/-1.6)x10(7)M(-1) for binding to monomeric canine IgG. Canine IgG-conjugated beads precipitated an approximately 72-kDa surface protein, whose size is consistent with that of the FcgammaRI alpha subunit of humans and mouse. The expression of FcgammaRI mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR), and the cDNA encoding the FcgammaRI alpha subunit was found to be 84% and 78% similar to that of humans and the mouse, respectively. The predicted amino acid sequence was 72% and 63% identical, respectively. Canine mastocytoma CM-MC cells are therefore very useful for studying FcgammaRI-mediated signal transduction in mast cells.
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PMID:Presence and primary sequence of a high-affinity IgG receptor on canine mastocytoma (CM-MC) cells. 1281 28