Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amount of cytosolic glucocorticoid receptor in liver of Ts18, Ts16, and Ts19 vs euploid mouse fetuses was studied after incubation of [3H]dexamethasone with cytosol followed by isoelectric focusing on polyacrylamide gels. In addition, corticosterone concentrations and enzyme activities of alanine aminotransferase and tyrosine aminotransferase were measured in the cytosol of the livers. The amount of glucocorticoid receptor in the cytosol fractions of the livers was always higher in the Ts18 than in the euploid fetuses of the same litter. It was also significantly (P less than 0.0005) higher if pooled data from different litters were analyzed. The ratio of the glucocorticoid receptor in Ts18 vs euploid mice varied between 1.3 and 4.7, with a mean of 2.1. In contrast, the glucocorticoid receptor levels in Ts16 and Ts19 fetuses were not different from the corresponding euploid controls. Comparing the corticosterone levels of the three trisomies tested with the corresponding euploid fetuses, no significant differences were found, indicating that the markedly elevated cytosolic glucocorticoid receptor concentrations in Ts18 were not due to different corticosterone levels. This finding is consistent with the assignment of the glucocorticoid receptor gene to chromosome 18 in the mouse. There was no correlation between glucocorticoid receptor levels and the activity of the two glucocorticoid inducible enzymes tested in the liver of mouse fetuses.
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PMID:Evidence of a gene-dosage effect for the glucocorticoid receptor in trisomy 18 mice. 290 26

This study shows that the derived hepatoma cell line Fao displays different sensitivities for glucocorticoid induction of tyrosine aminotransferase (TAT), alanine aminotransferase (AAT) and gamma-glutamyltransferase (GGT). This was seen in the different behaviors of nine steroids with respect to these three effects: (1) in the presence of full agonists (dexamethasone or deacylcortivazol), half-maximal induction of GGT occurred at approx 5- to 6-fold higher agonist concentrations than those required for half-maximal induction of AAT and TAT; (2) in the presence of full antagonists (RU 486, R5020, or progesterone) the GGT response induced by an equal agonist concentration was inhibited at concentrations approx 4- to 5-fold lower than those required for an equivalent inhibition of TAT response; (3) in the presence of cortexolone, deoxycorticosterone, 11 beta-hydroxyprogesterone and dexamethasone-3'-oxetanone, there was a partial agonistic effect (30-50%) on TAT and AAT responses, whereas there was a mainly antagonistic effect (very weak agonistic effect: 0-10%) on GGT response; (4) regardless of the steroid or its full or partial agonist activity, a given TAT induction level (50%, for example) always corresponded to the same AAT and GGT induction levels (50 and 10% respectively). We provide evidence showing that the three above-mentioned biological responses are mediated via the same type of glucocorticoid receptor binding site. Consequently, this differential behavior probably originates from a phenomenon occurring after the common steps (activation, translocation) that follow the formation of the steroid-receptor complex. This leads us to propose a model in which this phenomenon is assumed to originate from a difference in the affinities of the activated receptor for the nuclear acceptor sites of the TAT and GGT genes.
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PMID:Description and analysis of differential sensitivity to glucocorticoids in Fao cells. 290 11

1-Aminooxy-3-aminopropane was shown to be a potent competitive inhibitor (Ki = 3.2 nM) of homogenous mouse kidney ornithine decarboxylase, a potent irreversible inhibitor (Ki = 50 microM) of homogeneous liver adenosylmethionine decarboxylase and a potent competitive (Ki = 2.3 microM) of homogeneous bovine brain spermidine synthase. It did not inhibit homogeneous bovine brain spermine synthase and it did not serve as a substrate for spermidine synthase. The compound did not inhibit tyrosine aminotransferase, alanine aminotransferase or aspartate aminotransferase, which are pyridoxal phosphate-containing enzymes like ornithine decarboxylase. The inactivation of adenosylmethionine decarboxylase was partially prevented by pyruvate, which is the coenzyme of adenosylmethionine decarboxylase, and by the substrate, adenosylmethionine. 1-Aminooxy-3-aminopropane at 0.5 mM concentration inhibited the growth of HL-60 promyelocytic leukemia cells and this inhibition was prevented by spermidine but not by putrescine.
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PMID:1-Aminooxy-3-aminopropane, a new and potent inhibitor of polyamine biosynthesis that inhibits ornithine decarboxylase, adenosylmethionine decarboxylase and spermidine synthase. 386 Nov 82

The expression of alanine aminotransferase (EC 2.6.1.2), an enzyme that is inducible in the liver, has been examined in somatic hybrid cells formed by crossing well-differentiated rat hepatoma cells with rat diploid epithelial cells, the former characterized by high activity and inducibility of the enzyme, and the latter by the absence of detectable activity. The hybrid cells that contain essentially complete chromosomal sets of the two parents show only very low activity and little inducibility. Among numerous "segregated" hybrid subclones, which have lost up to 40% of the chromosomes initially present, several show expression of intermediate levels of enzyme activity and very little inducibility, and two independent subclones are characterized by full re-expression of both baseline and inducible enzyme activity. The electrophoretic mobility of the enzyme from the latter hybrids, from the hepatoma parental cells, and from rat liver is identical. The absence of a correlation between total chromosome number of the hybrid cells and re-expression of alanine aminotransferase suggests that the loss of specific chromosomes is required for re-expression. In these hybrid cells, the re-expression of alanine aminotransferase baseline and inducibility is independent of that of tyrosine aminotransferase inducibility.
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PMID:Expression of differentiated functions in hepatoma cell hybrids: alanine aminotransferase. 434 88

Growth of cultured rat hepatoma cells in the presence of 5-bromodeoxyuridine results in a rapid inhibition of the synthesis of adrenal steroid-inducible tyrosine aminotransferase (EC 2.6.1.5) and slower decreases in the concentrations of lactate dehydrogenase (EC 1.1.1.27), alcohol dehydrogenase (EC.1.1.1.1), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49). During the same period, neither overall cell growth nor the concentrations of malate dehydrogenase (EC 1.1.1.37), acid phosphatase (EC 3.1.3.2), or alanine aminotransferase (EC 2.6.1.2) were significantly decreased by the base analog. Addition of thymidine to the growth medium rapidly counteracts the inhibition of tyrosine aminotransferase synthesis but restores the normal concentrations of lactate-, alcohol-, and glucose-6-phosphate dehydrogenases much more slowly. Growth of the cells for only one generation in the presence of bromodeoxyuridine, followed by the addition of thymidine, produces transient decreases in the concentrations of the three "late-responding" dehydrogenases, beginning 2-3 generations after exposure to the analog.It is concluded that the selective inhibitory effects of the analog could result from a mechanism in which bromodeoxyuridine is uniformly incorporated into cellular DNA, but inhibits the transcription of only certain genes into messenger RNA. A mathematical model is derived to account for the observed differences in the kinetics of the inhibition of synthesis of the gene products that are sensitive to the analog.
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PMID:Differential effect of 5-bromodeoxyuridine on the concentrations of specific enzymes in hepatoma cells in culture. 439 42

Involution of the thymus was observed in rats bearing AH 130 (solid-type) tumors. The thymus weight decreased with tumor growth. Daily injection of a pharmacological dose of hydrocortisone into normal rats resulted in involution of the thymus and marked increase in alanine aminotransferase activity. This treatment also caused slight increase in the activity of tyrosine aminotransferase but not of aspartate aminotransferase in these animals. Involution of the thymus in tumor-bearing rats, however, was not accompanied by appreciable increases in the activities of these aminotransferases, even at an advanced stage of tumor growth when the plasma corticosterone level was very high and significant increase in the activities of all these enzymes was observed in the liver. Further, additional injections of hydrocortisone into rats with tumors weighing more than 5% of the body weight did not cause any appreciable change in alanine aminotransferase activity in the thymus, although in rats with smaller tumors it slightly increased the enzyme activity in the thymus. Furthermore, in normal rats, increase in alanine aminotransferase activity in the thymus with involution of the glands was observed with a dose of corticosterone close to the physiological range attained in rats with tumors in an advanced stage.
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PMID:Aminotransferase activities and involution of the thymus in rats bearing AH 130 tumors. 611 Apr 78

The effect of ethanol on the activity of ornithine decarboxylase (ODC), tyrosine aminotransferase (TAT), alanine aminotransferase (ALAT) and lactate dehydrogenase (LD), as well as on protein concentration, was studied in regenerating rat liver after partial hepatectomy. It was found that administration of an ethanol-containing liquid diet for 5 days after partial hepatectomy caused a significant accumulation of proteins in the liver. The activities of ODC and TAT were stimulated by ethanol treatment in the beginning of the regeneration. In control livers, partial hepatectomy decreased the activity of ALAT, but ethanol prevented this decrease. No differences in the activity of LD was found between ethanol and control groups after partial hepatectomy. When the half-lives of ODC and TAT were measured 24 hr after partial hepatectomy by using cycloheximide, it appeared that ethanol caused a significant stabilization of both enzymes. It is concluded that ethanol caused inhibition of degradation of ODC and TAT and it is suggested that this could be a general phenomenon, and could markedly contribute to the pathological accumulation of proteins in the liver after chronic ethanol consumption.
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PMID:Inhibition of protein degradation in regenerating rat liver by ethanol treatment. 611 5

After the 18.5-day flight on board the biosatellite Cosmos-936, the activity of 6 glucocorticoid-activated enzymes in the rat liver was investigated. It was found that at R+O activities of tyrosine aminotransferase and tryptophane pyrrolase, as well as fructose-1,6-diphosphatase, glucose-6-phosphatase, aspartate aminotransferase and alanine aminotransferase increased. The two former enzymes react rapidly (within several hours) to an increase in the glucocorticoid level, whereas those latter react only to a continuous prolonged effect of glucocorticoids. These increases were paralleled by a growth in the glycogen concentration in the liver. The findings indicate that during the flight the rats underwent a chronic stress induced by weightlessness.
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PMID:[Activity of various liver enzymes in rats following a flight aboard the Cosmos-936 biosatellite]. 612 Oct 82

Rats having a protein-free diet available ad libitum were fed a daily casein meal at the beginning of either the light- or the dark-phase of the day. A control group received a mixed-diet ad libitum. In all three groups, daily food ingestion was the same and casein corresponded to 12% of total intake. Liver activities of alanine, aspartate, ornithine and tyrosine aminotransferase, ornithine decarboxylase and serine dehydratase were assessed. In mixed-fed controls, all activities were low. Tyrosine aminotransferase and ornithine decarboxylase exhibited clear circadian rhythms of low amplitude. Feeding casein as a concentrated meal had no effect on aspartate aminotransferase. It depressed alanine aminotransferase and serine dehydratase activities. Tyrosine aminotransferase and ornithine decarboxylase exhibited rapid and strong stimulatory responses but, within 12 hours, returned to levels similar to those observed in mixed-fed controls. Ornithine aminotransferase was increased in the group receiving the casein meal during the light phase. It is concluded that the capacity for amino acid catabolism remains low in separately-fed animals, and that only tyrosine and especially ornithine, which may become limiting for urea synthesis, are actively metabolized. Thus, when high fluxes of amino acids reach the liver following the absorption of the casein meal, more amino acids are available for incorporation into newly synthesized proteins.
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PMID:Activity of several enzymes of amino acid catabolism in the liver of rats fed protein as a meal. 613 52

We report here our recent data on the effects of antiglucocorticoids in two established cell lines (HTC, FAZA). These steroid hormone target tissues were designed to consider the problem of differential antagonism and lack of correlation between antiglucocorticoid activity and competition for the glucocorticoid receptor. In the systems chosen, several responses were considered which may be differentially antagonized: induction of tyrosine aminotransferase (TAT), alanine aminotransferase (AAT) and tryptophan oxygenase (TPO). By testing the anti-inducing capacities of a number of steroids, we found a few synthetic compounds like promegestone and R 25055 which exert a stronger antagonism against TAT and AAT induction than natural steroids like progesterone. The availability of highly radioactive antagonists (promegestone, progesterone) has greatly facilitated our "whole cell" study and allowed us to detect the antagonists in isolated nuclei whose purity and morphological integrity were controlled by specific criteria; our results suggest that the binding of the antagonists to the nucleus proceeds via the glucocorticoid receptor. The appearance of promegestone and progesterone in the nucleus suggests that the nucleus may be involved in the mechanism of action of anti-glucocorticoids.
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PMID:Antagonism of glucocorticoid action in cultured hepatoma cells. 614 80


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