Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the effect of different promoters on the expression of an altered dihydrofolate reductase (DHFR) gene conferring methotrexate (MTX) resistance in different cell types, double-copy retroviral vectors were constructed carrying a murine mutant DHFR under the control of five different promoters, i.e., human adenosine deaminase (ADA), simian virus 40 (SV40), thymidine kinase (TK), human beta-actin, and cytomegalovirus (CMV). Their expression was compared in NIH-3T3 cells, three human leukemia cell lines, and mouse bone marrow. The variant DHFR is readily expressed from these various promoters in retroviral vectors at a selectable level. In 3T3 cells, the DHFR constructs containing the SV40 promoter conferred the highest levels of resistance to MTX. In K562 and Raji cells, the construct with the TK promoter produced the highest level of resistance. However granulocyte-macrophage colony-forming unit (CFU-GM) colonies from mouse marrow were more resistant to MTX when infected with vectors containing the SV40 promoter and ADA promoter as compared to the other promoter constructs. These studies show that mouse fibroblast cell lines such as NIH-3T3 do not predict the effectiveness of retroviral-mediated gene transfer for marrow progenitor cells, and that the activity of retroviral vector-encoded promoters vary in an unpredictable manner from cell type to cell type. Possible implications for basic gene transfer studies and clinical applications are discussed.
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PMID:Comparison of the expression of a mutant dihydrofolate reductase under control of different internal promoters in retroviral vectors. 152 11

Amphotropic helper-free retrovirus vectors containing the bacterial neomycin phosphotransferase gene (neo) and the human adenosine deaminase gene (adenosine aminohydrolase, EC 3.5.4.4; ADA) were used to transduce canine marrow cells. In one approach, dogs were treated for 7 days with recombinant human granulocyte colony-stimulating factor to stimulate hematopoietic cell division. Bone marrow cells were collected and transduced by 24 hours of cocultivation on vector-producing cells followed by incubation in a vector-containing long-term marrow culture system for 4 days. Transduced autologous marrow (0.4 to 1.0 x 10(8) cells/kg) was infused into dogs administered otherwise lethal total body irradiation (TBI) of 920 cGy. Two of four dogs engrafted, and their marrows showed intermittently between 1% and 11% G418-resistant colony-forming unit granulocyte-macrophage (CFU-GM) colonies for up to 2 years after transplantation. In a different experimental approach, autologous marrow, obtained at the time of the PB neutrophil nadir 7 days after a single cyclophosphamide injection (40 mg/kg intravenously), was cocultivated for 24 hours on vector-producing cells and infused at doses of 0.06 to 0.18 x 10(8) cells/kg into dogs administered 920 cGy TBI. One of three dogs engrafted, and the marrow showed intermittently 1% to 10% G418-resistant CFU-GM colonies for at least 2 years. Culture results were confirmed by polymerase chain reaction (PCR) showing the presence of the neo gene in marrow cells, peripheral blood (PB) granulocytes, and PB and lymph node lymphocytes. Dilution experiments indicated that up to 10% of marrow, lymph node, and PB cells contained the neo gene, consistent with the culture results. Samples harboring the neo gene also contained the gene for human ADA. However, repeated analyses of PB and marrow cells for human ADA gene expression by starch gel electrophoresis were negative. PB samples of all dogs were free of helper virus, and no long-term side effects from the transduction were observed.
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PMID:Retrovirus-mediated gene transduction into long-term repopulating marrow cells of dogs. 172 5