Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, we describe the efficiency of second gene translation in bicistronic constructs containing either a short (36bp) synthetic intercistron or known internal ribosomal entry sites (IRES). Experiments were performed using two different gene combinations: Herpes simplex virus-thymidine kinase (HSV-TK) and neomycine (NEO) or human glucocerebrosidase (hGC) and a methotrexate (MTX) resistant mutant dihydrofolate reductase (DHFR). We demonstrate that upon transfection, second gene translation is efficient using either an IRES or a 36-bp intercistron. Infection with retrovirus carrying the TK and NEO genes linked via a 36-bp intercistron resulted in both G418R (NEO expression) and gancyclovir (GCV) sensitivity (TK expression), indicating that both genes were expressed and thus that the genomic DNA and RNA of this bicistronic construct were intact. Likewise, retrovirus carrying the hGC and mutant DHFR gene separated by a short intercistron was harvested from MTXR murine PsiCRE cells. However, infection of PA317 cells with this virus supernatant did not result in the presence of hGC enzyme activity in these murine cells. Proviral DNA and RNA analyses indicated that the hGC coding region was lost from the original construct in the infected PA317 cells. In contrast, retrovirus carrying the hGC and DHFR cDNAs was linked via an IRES functioned as expected. Based on these results, we conclude that the efficiency of second gene translation using short synthetic intercistrons might prove useful in bicistronic constructs, depending on the gene combination used.
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PMID:Second gene expression in bicistronic constructs using short synthetic intercistrons and viral IRES sequences. 983 67

To develop a gene therapy protocol suitable for the treatment of a benign disease such as Gaucher disease, we have developed two bicistronic vectors that allow transduced cells to be selected for with methotrexate (MTX). The two vectors differ in the presence or absence of a mutant polyoma enhancer (delta Mo + PyF101) replacing the wild-type retroviral enhancer in the LTR. Infection of human TF-1 and K562 cells, Gaucher type II fibroblasts and murine hemopoietic bone marrow cells conferred MTX resistance and glucocerebrosidase (GC) expression. Upon increasing MTX concentrations, the number of proviral copies and GC activity increased, demonstrating in vitro selection of retrovirus-transduced cells. At high MTX selection pressure, up to 140 microM for infected Gaucher type II fibroblasts, no endogenous wild-type DHFR amplification could be detected, indicating that both retroviral constructs provide sufficient DHFR protein levels. Upon transduction, murine bone marrow cells were protected against otherwise lethal MTX concentrations (range 1-5 microM MTX). Flow cytometry specific for human GC (hGC) demonstrated that in vitro selection resulted in increased percentages of hGC-positive murine cells. In conclusion, the generated bicistronic vectors are ideally suited to investigate whether an in vivo selection approach for retrovirus-transduced cells is feasible. Such a strategy might abolish the need for a high initial transduction efficiency and might result in a gene therapy protocol devoid of the undesirable need for marrow ablative treatment of the recipient.
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PMID:Methotrexate selectable retroviral vectors for Gaucher disease. 993 Mar 44