Short- and long-term effects of insulin on tyrosine aminotransferase gene expression

Messina, Joseph L.; Chatterjee, A.; Strapko, Helen T.

doi:10.1016/0003-9861(92)90093-c

Cited by 11 publications

(7 citation statements)

References 45 publications

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“…In neonates, both PEPCK and TAT mRNA levels decrease markedly during the first 2 h of refeeding, and then remain almost constant (32). In hepatocytes exposed to insulin for a short period of time, glucocorticoid-and cAMP-induced transcription of the TAT gene is inhibited (33). The results we obtained following glucose treatment after 16 h of fasting were the same as those seen with refeeding after fasting.…”

Section: Discussionsupporting

confidence: 75%

Mechanism of Liver Tyrosine Aminotransferase Increase in Ethanol-Treated Mice and Its Effect on Serum Tyrosine Level

Sakata

Fujino

Matsuda

et al. 2007

J Nutr Sci Vitaminol

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Summary Liver tyrosine aminotransferase (TAT) activity is known to increase with ethanol treatment; however, the mechanism of this increase is unclear. Upon investigation we found that TAT activity and mRNA levels started to increase 2 h after ethanol administration and continued to increase until 6 h after ethanol administration. The increase in ethanol-induced TAT activity could not be explained by calorie loading after fasting, since ethanol loading increased TAT expression, while glucose loading decreased TAT expression. In addition, liver TAT activity was not related to serum tyrosine levels. TAT activity increased when an adenosine A2 agonist, 5 ¢ -N -ethylcarboxamide adenosine, was given. Since TAT activity is increased by cAMP, and ethanol increases cAMP production via an adenosine receptor-dependent mechanism, this increase in ethanol-induced TAT activity may occur via an adenosine receptor-dependent mechanism.

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Section: Discussionsupporting

confidence: 75%

Mechanism of Liver Tyrosine Aminotransferase Increase in Ethanol-Treated Mice and Its Effect on Serum Tyrosine Level

Sakata

Fujino

Matsuda

et al. 2007

J Nutr Sci Vitaminol

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“…While the control of tyrosine aminotransferase expression and activity has been extensively studied as a target of insulin signaling in vertebrates [30]–[34], [36], [38], a connection between tyrosine aminotransferase or tyrosine metabolism and insulin action has not been demonstrated. Prior work in C. elegans has suggested that the hpd-1 gene, which encodes 4-hydroxyphenylpyruvate dioxygenase, is repressed in daf-2 mutants and that knock-down of hpd-1 by RNAi delayed dauer exit and extended lifespan [39].…”

Section: Discussionmentioning

confidence: 99%

TATN-1 Mutations Reveal a Novel Role for Tyrosine as a Metabolic Signal That Influences Developmental Decisions and Longevity in Caenorhabditis elegans

et al. 2013

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Recent work has identified changes in the metabolism of the aromatic amino acid tyrosine as a risk factor for diabetes and a contributor to the development of liver cancer. While these findings could suggest a role for tyrosine as a direct regulator of the behavior of cells and tissues, evidence for this model is currently lacking. Through the use of RNAi and genetic mutants, we identify tatn-1, which is the worm ortholog of tyrosine aminotransferase and catalyzes the first step of the conserved tyrosine degradation pathway, as a novel regulator of the dauer decision and modulator of the daf-2 insulin/IGF-1-like (IGFR) signaling pathway in Caenorhabditis elegans. Mutations affecting tatn-1 elevate tyrosine levels in the animal, and enhance the effects of mutations in genes that lie within the daf-2/insulin signaling pathway or are otherwise upstream of daf-16/FOXO on both dauer formation and worm longevity. These effects are mediated by elevated tyrosine levels as supplemental dietary tyrosine mimics the phenotypes produced by a tatn-1 mutation, and the effects still occur when the enzymes needed to convert tyrosine into catecholamine neurotransmitters are missing. The effects on dauer formation and lifespan require the aak-2/AMPK gene, and tatn-1 mutations increase phospho-AAK-2 levels. In contrast, the daf-16/FOXO transcription factor is only partially required for the effects on dauer formation and not required for increased longevity. We also find that the controlled metabolism of tyrosine by tatn-1 may function normally in dauer formation because the expression of the TATN-1 protein is regulated both by daf-2/IGFR signaling and also by the same dietary and environmental cues which influence dauer formation. Our findings point to a novel role for tyrosine as a developmental regulator and modulator of longevity, and support a model where elevated tyrosine levels play a causal role in the development of diabetes and cancer in people.

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“…The IRS-like element is found in various genes, including phosphoenolpyruvate carboxykinase (PEPCK, [37]) and glucose 6-phosphatase [38] where insulin effects their transcriptional modulation. It is noteworthy that insulin may exert negative regulatory effects on the expression of various genes at both transcriptional and post-transcriptional levels [23,39,40]. In separate investigations, we have been attempting to characterize signal transduction pathways associated with insulin in primary hepatocytes.…”

Section: Discussionmentioning

confidence: 99%

“…The use of artificially high insulin levels will likely confound estimations of drug-metabolizing activity in vitro. Insulin can act as an inducer of the glucokinase [21] and pyruvate kinase genes [22] while also functioning to repress the cAMPmediated induction of tyrosine aminotransferase [23]. Saad et al [18] reported that lowered insulin concentrations or increased insulin:glucagon ratios led to a 2-3-fold elevation in functional activities associated with PB-inducible CYP proteins.…”

Section: Introductionmentioning

confidence: 99%

Insulin-mediated modulation of cytochrome P450 gene induction profiles in primary rat hepatocyte cultures

Sidhu

Omiecinski

1999

J. Biochem. Mol. Toxicol.

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Short- and long-term effects of insulin on tyrosine aminotransferase gene expression

Cited by 11 publications

References 45 publications

Mechanism of Liver Tyrosine Aminotransferase Increase in Ethanol-Treated Mice and Its Effect on Serum Tyrosine Level

Mechanism of Liver Tyrosine Aminotransferase Increase in Ethanol-Treated Mice and Its Effect on Serum Tyrosine Level

TATN-1 Mutations Reveal a Novel Role for Tyrosine as a Metabolic Signal That Influences Developmental Decisions and Longevity in Caenorhabditis elegans

Insulin-mediated modulation of cytochrome P450 gene induction profiles in primary rat hepatocyte cultures

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