Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Pharmacologic doses of 17 alpha-ethinyl estradiol are known to increase the number of low density lipoprotein (LDL) receptors in livers of rats, thereby producing a profound fall in plasma cholesterol levels. We now report that ethinyl estradiol exerts the same effect in livers of male and female rabbits and that the increase in receptor number is correlated with a 6- to 8-fold increase in the levels of receptor mRNA. Receptor protein was measured by ligand blotting, and mRNA levels were measured by a quantitative solution hybridization/S1 nuclease protection assay using uniformly 32P-labeled single-stranded cDNA probes. These experiments demonstrate that pharmacologic induction of the mRNA for the LDL receptor in liver can lead to increased LDL receptor levels and a fall in plasma cholesterol in experimental animals.
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PMID:Increased mRNA for low density lipoprotein receptor in livers of rabbits treated with 17 alpha-ethinyl estradiol. 241 43

We administered CS-514, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, alone and in combination with cholestyramine to heterozygous Watanabe heritable hyperlipidemic rabbits. This rabbit model for heterozygous familial hypercholesterolemia has hepatic low-density lipoprotein receptors that are assumed to be half as many as in normal rabbits. CS-514 alone lowered plasma low-density lipoprotein cholesterol levels by 50%, and in combination with cholestyramine, it lowered levels by 80%. The membrane-binding assay showed these drugs caused 1.5- and 1.8-fold increases in the number of hepatic low-density lipoprotein receptors, respectively. We also measured the amount of mRNA for low-density lipoprotein receptor by S1 nuclease protection assay in the same livers as above. These drugs induced mutant mRNA for the low-density lipoprotein receptor, which has an in-flame deletion of 12 nucleotides, as well as normal receptor mRNA. CS-514 alone produced a 1.8-fold increase in the amount of mRNA for the normal receptor and a 2.3-fold increase for the mutant mRNA, whereas CS-514 in combination with cholestyramine produced 1.9- and 3.1-fold increases, respectively. We conclude that CS-514 induces mRNA for the low-density lipoprotein receptor, subsequently increasing the receptor protein in the liver, and then reduces the levels of plasma cholesterol, and that the induction is augmented when the drug is administered in combination with cholestyramine.
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PMID:Induction of mRNA for low-density lipoprotein receptors in heterozygous Watanabe heritable hyperlipidemic rabbits treated with CS-514 (Pravastatin) and cholestyramine. 249 35

The Watanabe heritable hyperlipidemic (WHHL) rabbit, an animal with familial hypercholesterolemia, produces a mutant receptor for plasma low-density lipoprotein (LDL) that is not transported to the cell surface at a normal rate. Cloning and sequencing of complementary DNA's from normal and WHHL rabbits, shows that this defect arises from an in-frame deletion of 12 nucleotides that eliminates four amino acids from the cysteine-rich ligand binding domain of the LDL receptor. A similar mutation, detected by S1 nuclease mapping of LDL receptor messenger RNA, occurred in a patient with familial hypercholesterolemia whose receptor also fails to be transported to the cell surface. These findings suggest that animal cells may have fail-safe mechanisms that prevent the surface expression of improperly folded proteins with unpaired or improperly bonded cysteine residues.
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PMID:Deletion in cysteine-rich region of LDL receptor impedes transport to cell surface in WHHL rabbit. 301 Apr 66

We have isolated and sequenced overlapping cDNA clones covering the entire sequence of human apolipoprotein B-100 (apoB-100). DNA sequence analysis and determination of the mRNA transcription initiation site by S1 nuclease mapping showed that the apoB mRNA consists of 14,112 nucleotides including the 5' and 3' untranslated regions which are 128 and 301 nucleotides respectively. The DNA-derived protein sequence shows that apoB-100 is 513,000 daltons and contains 4560 amino acids including a 24-amino-acid-long signal peptide. The mol. wt of apoB-100 implies that there is one apoB molecule per LDL particle. Computer analysis of the predicted secondary structure of the protein showed that some of the potential alpha helical and beta sheet structures are amphipathic, whereas others have non-amphipathic neutral to apolar character. These latter regions may contribute to the formation of the lipid-binding domains of apoB-100. The protein contains 25 cysteines and 20 potential N-glycosylation sites. The majority of cysteines are distributed in the amino terminal portion of the protein. Four of the potential glycosylation sites are in predicted beta turn structures and may represent true glycosylation positions. ApoB lacks the tandem repeats which are characteristic of other apolipoproteins. The mean hydrophobicity the mean value of H1 and helical hydrophobic moment the mean value of microH profiles of apoB showed the presence of several potential helical regions with strong polar character and high hydrophobic moment. The region with the highest hydrophobic moment, between amino acid residues 3352 and 3369, contains five closely spaced, positively charged residues, and has sequence homology to the LDL receptor binding site of apoE. This region is flanked by three neighbouring regions with positively charged amino acids and high hydrophobic moment that are located between residues 3174 and 3681. One or more of these closely spaced apoB sequences may be involved in the formation of the LDL receptor-binding domain of apoB-100. Blotting analysis of intestinal RNA and hybridization of the blots with carboxy apoB cDNA probes produced a single 15-kb hybridization band whereas hybridization with amino terminal probes produced two hybridization bands of 15 and 8 kb. Our data indicate that both forms of apoB mRNA contain common sequences which extend from the amino terminal of apoB-100 to the vicinity of nucleotide residue 6300. These two messages may have resulted from differential splicing of the same primary apoB mRNA transcript.
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PMID:The complete sequence and structural analysis of human apolipoprotein B-100: relationship between apoB-100 and apoB-48 forms. 303 Jul 29

A Japanese subject with homozygous familial hypercholesterolemia was found to have a 7.8-kilobase deletion in the gene for the low density lipoprotein receptor. The deletion joins intron 15 to the middle of exon 18, which encodes the 3' untranslated region, thereby removing all 3' splice acceptor sites distal to intron 15. By S1 nuclease mapping, we demonstrated that the 5' splice donor site of intron 15 is no longer used. Instead a continuous transcript is produced in which exon 15 is followed by the remaining segments of intron 15 and exon 18. The translational reading frame of exon 15 continues for 165 nucleotides into intron 15 before a termination codon is reached. This mRNA should produce a truncated receptor that lacks the normal membrane-spanning region and cytoplasmic domain and that has 55 novel amino acids at its COOH terminus. A cDNA expression vector containing this sequence produced a receptor that behaved similarly to the truncated protein produced by the Japanese patient, i.e. greater than 90% of the receptor was secreted from the cell, and the receptors remaining on the surface showed defective internalization. The deletion in this subject resulted from a recombination between two repetitive sequences of the Alu family, one in intron 15 and the other in exon 18. To date, Alu sequences have been observed at the deletion joints of all four gross deletions in the low density lipoprotein receptor gene that have been characterized. Within these Alu sequences, six out of the seven breakpoints have occurred in the left arm. These data suggest that recombination between Alu sequences may be a frequent cause of deletions in the human genome.
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PMID:Alu-Alu recombination deletes splice acceptor sites and produces secreted low density lipoprotein receptor in a subject with familial hypercholesterolemia. 381 45

Regulation of intracellular cholesterol metabolism has been studied in Epstein-Barr virus-transformed lymphoblasts from patients with Niemann-Pick type C (NPC) and the Nova Scotia type D (NPD) disease. Addition of LDL to normal lymphoblasts cultured in lipoprotein-deficient medium increased cholesterol esterification 10-fold (to a maximum of 1.0 nmol/h/mg protein at 15 h), while little stimulation was seen in NPC cells. The response by NPD lymphoblasts was intermediate, reaching approximately half of normal values by 14-24 h. Lymphoblasts from both NPC and NPD obligate heterozygotes exhibited 50% of normal LDL-stimulated cholesterol esterification at 6 h, when activity was < 10% of normal values in patient cells. Fluorescence staining with filipin indicated excessive intracellular accumulation of LDL-derived cholesterol in both NPC and NPD lymphoblasts. Downregulation of LDL receptor mRNA levels by LDL, measured by S1 nuclease protection assay, was also impaired in NP lymphoblasts and fibroblasts (NPC > NPD), although a similar rate of receptor protein down-regulation by LDL (t1/2 = 10-15 h) was observed in normal and NP lymphoblasts. In contrast, LDL down-regulation of 3-hydroxy-3-methylglutaryl-CoA reductase mRNA did not appear to be affected in NP cells: LDL produced a 3-fold (lymphoblasts) or > 10-fold (fibroblasts) decrease by 12 h in both normal and affected cells. Thus, NPC and NPD lymphoblasts exhibit distinct defects in cholesterol esterification and storage, similar to those observed in mutant fibroblasts. Other regulatory responses are also impaired in NPC lymphoblasts but appear to be less affected in NPD cells. Lymphoblasts should provide a valuable immortalized cell line model for study of defective regulation of cholesterol esterification and transport in Niemann-Pick type II disease, and may also be suitable for diagnosis and carrier detection.
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PMID:Regulation of intracellular cholesterol metabolism is defective in lymphoblasts from Niemann-Pick type C and type D patients. 820 65

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