Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms by which renal failure causes hyperlipoproteinemia remain unclear. To investigate the potential role of the low-density lipoprotein (LDL) receptor in lipoprotein metabolism in uremia we measured LDL receptor function in peripheral blood mononuclear cells (PBMC) from uremic patients and control subjects using a functional assay in which proliferation of lectin-stimulated PBMC in the presence of lovastatin was dependent upon internalization of exogenous cholesterol via a functional LDL receptor. The amount of LDL required to reverse 50% of lovastatin-induced inhibition of proliferation in PBMC from uremic patients was significantly greater (3.6 +/- 1.8 micrograms/ml, N = 33, P < 0.05) than controls, (1.99 +/- 0.6 micrograms/ml, N = 37). Abnormal LDL receptor function in four uremic patients normalized following renal transplantation. To investigate the molecular basis for LDL receptor dysfunction, we directly quantitated LDL receptor messenger RNA (mRNA) in PBMC from uremic patients and control subjects using a ribonuclease protection assay. LDL receptor mRNA expression in uremic patients was 0.42 +/- 0.08 (N = 10), significantly lower (P < 0.015) than in normal subjects, 0.71 +/- 0.08 (N = 14). These data suggest that an acquired defect in LDL receptor function in PBMC from uremic patients exists which may be due to decreased LDL receptor expression. These abnormalities, if present in other tissues, could contribute to the aberrant lipoprotein metabolism which is a consistent feature of uremia.
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PMID:Decreased low-density lipoprotein receptor function and mRNA levels in lymphocytes from uremic patients. 145 9

We designed a rapid method for determining mRNA content of cholesterol biosynthesis enzymes and LDL receptor (LDLR) using a ribonuclease protection assay (RPA). 32P-labeled cRNA fragments for genes of human LDLR and the enzymes HMG-CoA synthase (HMGS), HMG-CoA reductase (HMGR), mevalonate kinase (MK), farnesyl pyrophosphate synthase (FPPS), and squalene synthase (SQS) were prepared by in vitro transcription. Total RNA prepared from HepG2 cells was hybridized with the cRNA probe and the hybridized mRNA was determined under protection from RNase digestion. Probe content used in this assay was excess in determining the desired mRNA in total RNA, and surplus probes were completely digested using RNase under standard conditions. When cells were cultured in DMEM supplemented with 10% fetal calf serum (FCS), mRNA levels of FPPS, SQS, and LDLR were about 4- to 7-fold higher than those of HMGS, HMGR, and MK. On incubation with DMEM supplemented with 10% lipoprotein-deficient serum (LPDS) for 8 h, all messenger RNA levels increased 1.5- to 3.5-fold. In addition, when the HMG-CoA reductase inhibitor compactin was added to 10% LPDS-DMEM, these levels increased even further and the change in mRNA level seemed to differ between the enzymes and LDLR. From these results, we conclude that RPA is a useful method for determining the very small amount of mRNA level of cholesterol biosynthesis enzymes and LDLR in the cell.
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PMID:Determination of mRNA levels of cholesterol biosynthesis enzymes and LDL receptor using ribonuclease protection assay. 855 80

The effect of various 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on the induction of HMG-CoA reductase and low density lipoprotein (LDL) receptor mRNA were quantitatively determined in the cultured human hepatoma cell line Hep G2 by means of a ribonuclease protection assay. Lipophilic inhibitors including mevastatin, simvastatin, atorvastatin and NK-104 were able to increase the levels of mRNAs for HMG-CoA reductase and the LDL receptor, but the hydrophilic inhibitor pravastatin was not effective in Hep G2 cells as had previously been reported. The LDL receptor mRNA was induced by NK-104 most effectively between 0.1 to 10 microM among the lipophilic inhibitors, whereas the degrees of induction of HMG-CoA reductase mRNA by these inhibitors did not differ significantly from each other. When cells were treated with a 200-fold excess of the IC50 concentration of each inhibitor, NK-104 was able to induce LDL receptor mRNA most effectively. These results indicate that the effect of HMG-CoA reductase inhibitors on the upregulation of mRNA for reductase and LDL receptor are different from each other and among these lipophilic inhibitors. NK-104 is most effective in inducing LDL receptor mRNA in Hep G2 cells.
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PMID:Relative induction of mRNA for HMG CoA reductase and LDL receptor by five different HMG-CoA reductase inhibitors in cultured human cells. 1148 Apr 54