Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The time course of changes in a number of biochemical parameters in rat liver was studied during 10 days of clofibrate administration. Ornithine decarboxylase (ODC) and putrescine levels began to increase within hours of the first dose and reached maxima at about 36 h (40 and 10 times control levels, respectively) and then returned to normal levels by 48 h. This ODC induction by clofibrate is different from that seen in compensatory liver hyperplasia or diethylnitrosamine administration in that it was not accompanied by elevations in cAMP or increased activation of cytoplasmic cAMP-dependent protein kinases, type I or II. Messenger RNA levels, notably of the species coding for the enzymes of the peroxisomal beta-oxidation pathway, increased in parallel with ODC and putrescine to reach a maximum also at 36 h. The enzymes of the peroxisomal beta-oxidation pathway, on the other hand, increased more gradually over time to reach a plateau at approximately 7 - 10 days. The magnitude of increase in mRNA (about 7-fold) was comparable to that of peroxisomal beta-oxidation as measured by cyanide-insensitive palmitoyl-CoA-dependent NAD+ reductase activity; comparable increases in the specific content of enoyl-CoA hydratase: beta-hydroxyacyl-CoA dehydrogenase and of peroxisomal thiolase were observed, as determined by SDS electrophoresis. A gradual increase in long-chain acyl-CoA (1.5-fold) followed the increase in beta-oxidation, whereas a 2-fold increase in acid-soluble CoA (free CoA and short-chain acyl-CoA) was seen as early as 36 h. This sequence of changes is at variance with proposals that increased levels of long-chain acyl-CoA mediate induction of peroxisomal beta-oxidation.
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PMID:Relation between induction of ornithine decarboxylase and specific gene expression in rat liver in response to the tumor promoter agent clofibrate. 301 97

In this paper, we describe the early biochemical changes in liver cells that occur in rats fed a semisynthetic diet containing 20% (w/w) partially hydrogenated fish oil. Within hours the level of ornithine decarboxylase (ODC) increased, peaked at about 24 h (11-fold increase) and returned to subnormal levels within 48 h. The diet evoked a similar rapid increase in the cellular level of mRNA for the bifunctional enzyme of peroxisomal beta-oxidation (enoyl-CoA hydratase: beta-hydroxyacyl-CoA dehydrogenase (HD)) (12-fold), followed by increases in the specific content of HD protein (3-fold) and the capacity for beta-oxidation in peroxisomes (5.3-fold). The cellular level of long-chain acyl-CoA increased 2.1-fold. By contrast, no significant changes were observed in the specific activities of ornithine decarboxylase, peroxisomal beta-oxidation activity and microsomal omega-hydroxylation as well as the level of long-chain acyl-CoA in livers of rats fed (1 week) diets containing 20% (w/w) soybean oil with added 3 or 6% (w/w) of either elaidic acid (18:1(11) (trans)), brassidic acid (22:1(13) (trans)) or erucic acid (22:1(13) (cis)). Expression of normal levels of mRNA for the bifunctional enzyme was also found. Morphometric analyses revealed no proliferation of peroxisomes in these fatty acid-supplemented diets, in contrast to that observed with the partially hydrogenated fish oil diet. These results are consistent with the proposal (Flatmark, T., Christiansen, E.N. and Kryvi, H. (1983) Biochim. Biohys. Acta 753, 460-466) that components in dietary oils, different from C22:1 cis and trans fatty acids, are responsible for the pleiotropic responses evoked in target cells. Thus, the pattern of response induced by partially hydrogenated fish oil mimics those induced by xenobiotic compounds collectively termed peroxisome proliferators.
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PMID:On the mechanism of induction of the enzyme systems for peroxisomal beta-oxidation of fatty acids in rat liver by diets rich in partially hydrogenated fish oil. 341 2