Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The beta-globin locus control region (LCR) confers high levels of position-independent, copy number-dependent expression onto globin transgenes. Here > 40 independent transgenic mouse lines and founders that carried the LCR in cis with the beta-globin gene promoter driving a lacZ reporter gene were studied. Expression of the lacZ transgene was assayed by measuring beta-galactosidase enzyme activity in fetal liver extracts, the levels of which correlated with the quantity of lacZ mRNA determined using RNase protection assays. Unexpectedly, expression of the lacZ transgene was found to show strong position effects, varying as much as 700-fold per transgene copy. These position effects occurred even if the whole beta-globin gene was incorporated as part of the lacZ reporter gene. Moreover, DNase I-hypersensitive sites appeared in the transgene LCR in high expressing but not in low expressing lines, suggesting that the LCR itself was position dependent. In contrast, MEL cell clones, in which transcriptionally active integration sites were selected for, gave < 13-fold variation in expression per copy of an LCR-lacZ construct. These results show that the lacZ reporter affects the ability of the LCR to activate chromatin in mice and that culture cells are not an adequate model for position-independent gene expression studies.
 ...
PMID:The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice. 867 Aug 75

Our previous works have verified that the beta-globin gene carrying large fragments of erythroid enhancer transferred by retrovirus vector caused the unstable provirus integration and low virus titer in infected cells, but the 36bp enhancer had not this negative effect. In order to circumvent this problem, we inserted the intact beta-globin gene (beta) or partially IVS II deleted beta-globin gene (delta beta) and truncated erythroid enhancer (36bp, 292bp and 341bp) into the N2A retrovirus vector. Recombinants were transfected into psi-2 ecotropic pachaging cells first, then the produced virus were used to infect PA317 amphotropic packaging cells. Virus supernatent from PA317 clonies with high virus titer and intact provirus integration was used to infect MEL cells. RNase protection assay was used to detect the expression of beta-globin gene. Results showed that not only the stable provirus integration and high virus titer of the transferred genes, but also the high levels expression of beta-globin gene carrying 292bp or 341bp erythroid enhancer were got.
 ...
PMID:[Effect of erythroid enhancer on the expression of beta-globin gene in mice erythroleukemia (MEL) cells]. 869 94

The beta1,4-N-acetylgalactosaminyltransferase (beta1,4GalNAc-T) (EC) gene is expressed in normal brain tissues and in various malignant transformed cells, such as malignant melanoma, neuroblastoma, and adult T cell leukemia. To analyze the regulatory mechanisms of gene expression, we determined the genomic organization of the beta1, 4GalNAc-T gene. The gene consists of at least 11 exons and spans >8 kilobase pairs. The coding region is located in exons 2-11. To determine the transcription initiation sites, 5'-rapid amplification of cDNA ends analysis and ribonuclease protection assays were performed using RNA obtained from the human melanoma cell line SK-MEL-31. Consequently, we defined three transcription initiation sites and the alternative usage of three exons. Exons 1a and 1b partially overlap; the latter is part (3'-side) of the former and corresponds to the 5'-noncoding region of the cDNA clone previously isolated. The third transcript, exon 1c, corresponds to nucleotides -520 to -412 (position +1 = A of ATG of beta1,4GalNAc-T cDNA), which are considered to be in intron 1 based on the cloned cDNA sequence. Ribonuclease protection assays revealed the corresponding protection bands in samples of the gene-expressing cell lines. 5'-Flanking regions of individual initiation sites showed promoter activity when analyzed by chloramphenicol acetyltransferase assay in SK-MEL-31 cells. The multiple transcription initiation sites and their promoters/enhancers identified here might be differentially involved in the cell type-specific expression of the beta1,4GalNAc-T gene. This gene was assigned to human chromosome 12q13.3 by means of fluorescence in situ hybridization.
 ...
PMID:Genomic organization and chromosomal assignment of the human beta1, 4-N-acetylgalactosaminyltransferase gene. Identification of multiple transcription units. 870 39

We have previously described the development of oncoretrovirus vectors for human gamma-globin using a truncated beta-globin promoter, modified gamma-globin cassette, and alpha-globin enhancer. However, one of these vectors is genetically unstable, and both vectors exhibit variable expression patterns in cultured cells, common characteristics of oncoretrovirus vectors for globin genes. To address these problems, we identified and removed the vector sequences responsible for genetic instability and flanked the resultant vector with the chicken beta-globin HS4 chromatin insulator to protect expression from chromosomal position effects. After determining that flanking with the cHS4 element allowed higher, more uniform levels of gamma-globin expression in MEL cell lines, we tested these vectors using a mouse bone marrow transduction and transplantation model. When present, the gamma-globin cassettes from the uninsulated vectors were expressed in only 2% to 5% of red blood cells (RBCs) long term, indicating they are highly sensitive to epigenetic silencing. In contrast, when present the gamma-globin cassette from the insulated vector was expressed in 49% +/- 20% of RBCs long term. RNase protection analysis indicated that the insulated gamma-globin cassette was expressed at 23% +/- 16% per copy of mouse alpha-globin in transduced RBCs. These results demonstrate that flanking a globin vector with the cHS4 insulator increases the likelihood of expression nearly 10-fold, which in turn allows for gamma-globin expression approaching the therapeutic range for sickle cell anemia and beta thalassemia.
 ...
PMID:Development of virus vectors for gene therapy of beta chain hemoglobinopathies: flanking with a chromatin insulator reduces gamma-globin gene silencing in vivo. 1220 Mar 60

Several commercial preparations of human chorionic gonadotropin (hCG) have been tested as therapy for Kaposi's sarcoma (KS) in clinical trials, but with discordant outcomes. We also have found dramatic differences in the cytotoxic effects of four different commercial hCG preparations on an established KS cell line, KSIMM. A co-purified moiety (ies) present in these preparations may explain these differences. The eosinophil-derived neurotoxin ribonuclease, extended with four extra residues ((-4)EDN), has been suggested to be the putative anti-KS compound in the hCG preparations, being specifically recognized by the cells through its N terminal extension. We therefore synthesized a 16-residue peptide (MSLHV-NT12 EDN), made to resemble the active recognition sequence of (-4)EDN. MSLHV-NT12 EDN displays a dose-dependent cytotoxic effect on KSIMM (killing 50% of the cells at 9 microg/ml). The cytotoxic effect is specific for KS cells, MSLHV-NT12 EDN being harmless even at 100 microg/ml for a melanoma cell line (SK-MEL-28) or for normal human fibroblasts. We also demonstrated that MSLHV-NT12 EDN induces apoptosis in KSIMM cells. In conclusion, MSLHV-NT12 EDN is a specific proapoptotic substance for KS cells, which warrants further investigation into its in vivo effects.
 ...
PMID:A synthetic peptide derived from the human eosinophil-derived neurotoxin induces apoptosis in Kaposi's sarcoma cells. 1527 5