Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine whether there are differences between the U1, U2, and U3 small nuclear RNA's of human cancer cells (HeLa cells) and human normal fibroblasts (IMR-90 cells), and between these uridine-rich small nuclear RNA's of human and Novikoff hepatoma cells, the cells were first incubated in Eagle's medium with [32P]Pi to label these RNA's uniformly. No differences were found between the RNase T1 fingerprints of the purified U1, U2, and U3 RNA's of HeLa cells and IMR-90 cells. The RNase T1 fingerprints of U1 RNA's from human tissues were very similar to that of the U1 RNA of Novikoff hepatoma cells. The RNase T1 fingerprints of U2 and U3 RNA's from human tissues had many similarities to those of Novikoff hepatoma cells, but a few differences were found, such as a point mutation of the U-U-Gp in the rat U2 RNA to A-U-Gp (U leads to A) in human U2 RNA. Unlike the three U3 RNA's of Novikoff hepatoma cells, U3 RNA from human tissues appears to be only one species. These results indicate that U1, U2, and U3 RNA's of human cancer cells are essentially the same as those of human normal cells. In addition, the uridine-rich small nuclear RNA's appear to be conserved through evolution.
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PMID:Comparison of RNase T1 fingerprints of U1, U2, and U3 small nuclear RNA's of HeLa cells, human normal fibroblasts, and Novikoff hepatoma cells. 616 60

Insulin directly down-regulates the gene expression of the rat CYP2E1 by altering its mRNA stability (De Waziers, I., Garlatti, M., Bouguet, J., Beaune, P. H., and Barouki, R. (1995) Mol. Pharmacol. 47, 474-479). Because the regulation of CYP mRNA stability was poorly understood, the molecular mechanisms involved in this regulation in the rat hepatoma H4IIEC3 cell line were studied. By using RNase T1 protection methods, the formation of a major CYP2E1 RNA-protein complex was observed. By competition experiments, the binding site of this complex was located on a 16-nucleotide sequence in the 5'-proximal region of the CYP2E1-coding sequence. Insulin did not modify the binding pattern of proteins to this sequence. and transfections of expression vectors or antisense oligonucleotides were undertaken to demonstrate the actual functionality of the 16-mer sequence. The insertion of this sequence in a luciferase gene was sufficient to render the chimeric mRNA sensitive to insulin. Furthermore, transfection of H4IIEC3 cells with antisense oligonucleotide complementary to this sequence blocked the insulin effect on the CYP2E1 mRNA expression, i.e. its rapid degradation. All these results demonstrate that this 16-nucleotide sequence is implicated in the CYP2E1 post-transcriptional regulation by insulin.
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PMID:Identification of a 16-nucleotide sequence that mediates post-transcriptional regulation of rat CYP2E1 by insulin. 1227 Sep 35

Diabetes has been reported to increase CYP2E1 (cytochrome P450) and CYP2B1 expression at both the mRNA and protein levels in rat livers. This increase has been attributed to mRNA stabilization and can be reversed by daily insulin treatment. In a previous study, we showed that this hormone directly down-regulates CYP2E1 and 2B1 expression through a post-transcriptional mechanism in rat hepatoma cell lines. We then aimed to identify the molecular mechanisms involved in this regulation. We first identified a 16-mer sequence that we later showed to be the actual functional target of insulin on the rat CYP2E1 mRNA. Similar work was performed with CYP2B1. We first investigated the presence of mRNA-protein interactions. Using cytoplasmic proteins of Fao cells treated or not with insulin (0.1 microM) and the full-length CYP2B1 mRNA as a probe, a major CYP2B1 RNA-protein complex was observed with RNase T1 protection experiments. With the use of different CYP2B1 mRNA probes and by means of competition experiments with antisense oligonucleotides, a protein fixation site was located on a 16-nt sequence in the 5' part of the coding region. This sequence has a hairpin loop structure, shows 80% sequence identity with a structure previously identified on CYP2E1 and is also responsible for the post-transcriptional effects of insulin on this mRNA. Protein(s) bound to both CYP2B1 and CYP2E1 sequences are cytosolic and have an apparent molecular mass of 60 kDa. The protein(s) that bind(s) to both these sequences and the insulin transduction signal involved in this regulation remain(s) to identified.
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PMID:Regulatory sequence responsible for insulin destabilization of cytochrome P450 2B1 (CYP2B1) mRNA. 1561 13