Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exposure of human leukemia HL-60 cells to an oligodeoxynucleotide complementary to an 18-base sequence (codons 2-7) of c-myb-encoded mRNA has previously been shown to result in inhibition of cell proliferation. Because HL-60 cells express high levels of transferrin receptor we adapted a DNA delivery system based on receptor-mediated endocytosis to introduce myb oligomers complexed with a transferrin-polylysine conjugate into those cells. A DNA.RNA duplex resistant to S1 nuclease digestion was detected as early as 12 hr after culture of HL-60 cells in the presence of the myb antisense/transferrin-polylysine complex. Exposure of HL-60 cells to the myb antisense/transferrin-polylysine complex resulted in rapid and profound inhibition of proliferation and loss of cell viability much more pronounced than that occurring in cells exposed to free myb antisense oligodeoxynucleotides. The transferrin-polylysine/myb sense complex or the transferrin-polylysine conjugate alone had no effect on HL-60 cell proliferation and viability. These findings indicate that myb synthetic oligodeoxynucleotides enter efficiently into HL-60 by transferrin receptor-mediated endocytosis and exert a profound biological effect. Such a delivery system could exploit other ligand-receptor interactions for the selective delivery of oncogene-targeted antisense oligodeoxynucleotides.
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PMID:Inhibition of leukemia cell proliferation by receptor-mediated uptake of c-myb antisense oligodeoxynucleotides. 149 97

Transferrin is an iron-binding protein that is expressed as a major product in liver and secreted into the plasma. To study the tissue-specific regulatory regions of this gene, the genomic mouse transferrin (mTf) gene was cloned and characterized by partial sequence analysis and S1 nuclease mapping of the transcriptional start site. Fusion genes containing the transferrin gene promoter and 5'-flanking sequences were ligated to the human growth hormone (hGH) gene and used to produce transgenic mice. A deletion construct containing the -581 to +50 region of the transferrin gene was sufficient to direct a high level of liver-specific expression resembling endogenous transferrin gene expression. Deletion to -139 base pairs of 5'-flanking sequence gave a construct which retained liver specificity, but the magnitude of expression decreased severalfold. These results demonstrate the presence of a liver-specific transcriptional element between -139 and +50 and suggest the presence of a distal element between -581 and -139 that can further increase expression. Surprisingly, fusion constructs containing -3 kilobase pairs (kb) of 5'-flanking sequence gave higher levels of mRNA in nonhepatic tissues than did either the -581 or -139 construct. Further studies indicated that the high levels of circulating hGH in these transgenic mice specifically induced the endogenous transferrin and albumin genes in liver and also stimulated the normally low levels of expression of the endogenous transferrin gene in brain, heart, kidney, and muscle. A mutated hGH gene that does not produce active growth hormone was fused to the -3- to +50-kb transferrin sequences to produce the -3-kb mTf-hGX construct. A liver-specific pattern of expression was observed in transgenic mice harboring the -3-kb mTf-hGX construct, and this mutated transgene was shown to be induced four- to sevenfold by either bovine or human growth hormone. These results demonstrate the presence of a growth hormone-responsive element between -3 and +50 kb in the 5'-flanking region of the mTf gene promoter.
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PMID:Expression from the transferrin gene promoter in transgenic mice. 260 14

Apolipoprotein E (apoE) isoforms are key determinants of susceptibility to late-onset Alzheimer's disease (AD). The epsilon 4 and epsilon 2 alleles have been associated with increased and decreased risk for AD, respectively. We have generated and characterized transgenic mice in which the human apoE2 gene is expressed under the control of the platelet-derived growth factor B-chain (PDGF-B) promoter, or the transferrin (TF) promoter. S1 nuclease analysis and immunoblotting showed that the PDGF-B apoE2 mice express apoE2 exclusively in the brain whereas the TF apoE2 mice express apoE2 in the liver and in the brain. In the TF apoE2 mouse line, apoE2 is also detected in the plasma. The PDGF-B apoE2 and the TF apoE2 transgenic mice were bred back to apoE(-)(/)(-) background. Immunohistochemical analysis showed that the PDGF apoE2 x apoE(-)(/)(-) and the TF apoE2 x apoE(-)(/)(-) mice express human apoE2 within the neocortex in hippocampal neurons and glial cells, respectively. ApoE(-)(/)(-) mice have been shown to develop age-dependent loss of synaptophysin. Immunoblotting of mouse brain extracts and immunohistochemical analysis of brain sections showed that apoE expression in both apoE2 x apoE(-)(/)(-) transgenic lines was associated with significant recovery of brain synaptophysin levels as compared to the levels of apoE(-)(/)(-) littermates of the same age. These apoE2-expressing mice, when bred back on amyloid precursor protein (APP) transgenic mice or other mouse lines featuring alterations in lipoprotein metabolism, may provide new mouse models for elucidating the role of apoE2 in lipid homeostasis in the brain and in the pathogenesis of AD.
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PMID:Generation and characterization of two transgenic mouse lines expressing human ApoE2 in neurons and glial cells. 1213 50