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:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cadmium, in addition to producing a variety of toxic manifestations, is known to accumulate in certain "target" organs which include liver and kidney where histological and functional damage becomes apparent. The daily intraperitoneal injection of cadmium chloride for 21 or 45 days stimulated the activities of hepatic pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1, 6-diphosphatase and glucose-6-phosphatase elevated blood glucose and urea, and lowered hepatic glycogen in rats. Whereas chronic Cd treatment failed to alter adenosine-3', 5'-monophosphate phosphodiesterase (PDE) activity, cyclic AMP (cAMY and the activity of basal and fluoride-stimulated forms of hepatic adenylate cyclase (AC) were markedly increased. However, the cAMP binding to hepatic protein kinase was decreased as was the kinase activity ration. An acute dose of Cd decreased hepatic glycogen content and increased blood glucose, serum urea, and hepatic cAMP. Chronic exposure to Cd induced adrenal hypertrophy and augmented adrenal norepinephrine and epinephrine as well as the activity of adrenal tyrosine hydroxylase. This treatment decreased prostatic and testicular weights of mature rats. Although cAMP as well as AC activity of the prostate gland were reduced, cAMP binding to the prostatic protein kinase was increased as was the activity of the cAMP-dependent form of the enzyme. Testicular AC and PDE activities, however, were stimulated, although cAMP remained unaffected. Whereas the activities of the cAMP-dependent and the independent forms of testicular protein kinase were significantly depressed, the binding of cAMP to protein kinase from testes of Cd-treated rats was not affected. In most cases, the observed metabolic alterations persisted up to 28 days on cessation of Cd administration. Subacute Cd treatment suppressed pancreatic function as evidenced by lowered serum immunoreactive insulin (IRI) in presence of hyperglycemia, as well as by partial inhibition of phentolamine-stimulated increases in serum IRI. Although chronic Cd treatment failed to alter the concentration of brain stem norepinephrine and cerebrocortical acetylcholine esterase activity, serotonin levels of brain stem were depressed and the concentration of striatal dopamine and cerebrocortical acetylcholine were significantly elevated when compared with the values seen in control nonexposed animals.
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PMID:Aspects of the biochemical toxicology of cadmium. 17 84

A variety of 6- and 8-substituted analogs of cAMP (cyclic adenosine 3:5-monophosphate) have been tested for their ability to increase activity of tyrosine aminotransferase (EC 2.6.1.5) in cultured Reuber H35 hepatoma cells. Some analogs, particularly the 8-thio-substituted ones, produced effects approximately equivalent to those generated by N-6, O2'-dibutyryl cAMP. In contrast, cAMP and its O-2-monobutyryl derivative were relatively ineffective even at very high concentrations, whereas three other analogs actually depressed the activity of the aminotransferase. Changes in enzyme activity generated by the various analogs were paralleled closely by changes in the relative rate of aminotransferase synthesis. An excellent correlation was found to exist between the ability of any given analog to influence the activity of tyrosine aminotransferase and that of phosphoenolpyruvate carboxykinase (EC 4.1.1.32). A similar correlation was found to exist between the ability of various analogs to evelate the activity of these enzymes and to inhibit reversibly the growth of H35 cells. Only one of five inhibitors of cAMP phosphodiesterase activity tested produce any increase in aminotransferase activity when added alone. All of the 6- and 8-substituted analogs tested, including noniducers, stimulated f1 histone phosphorylation in crude rat liver extracts with approximately equal potencies. On the other hand, dibutyryl cAMP was only a weak activator of protein kinase in vitro, even though it is a potent enzyme inducer. A possible resolution of this apparent discrepancy has been provided by preliminary analyses of site-specific f1 histone phosphorylation in whole cells. Only compounds active as aminotransferase inducers are capable of stimulating phosphorylation of the serine-37 residue of endogenous f1 histone (3- to 10-fold).
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PMID:Effects of 6- and 8-substituted analogs of adenosine 3':5'-monophosphate on phosphoenolpyruvate carboxykinase and tyrosine aminotransferase in hepatoma cell cultures. 23 87

A single-dose administration of 6-hydroxydopamine (50 mg/kg body weight, sc) to infant rats resulted in an enlargement, higher fresh weight, markedly elevated lipid content, and higher total protein content of their interscapular and cervical brown adipose tissue. The protein kinase (EC 2.7.1.37) activation ratio in the tissue was decreased as was the phosphoenolpyruvate carboxykinase (EC 4.1.1.32) activity. Fatty acid synthetase, on the other hand, showed an increased activity. These changes commenced as soon as 24 h after the administration of the drug, were fully developed 2-4 days later, and persisted for at least 14 days. The results are in line with the assumption that 6-hydroxydopamine administration causes chemical sympathectomy of brown adipose tissue. This is further supported by the fact that treatment with alpha-methyltyrosine, which is known to competively inhibit norepinephrine systhesis, results in similar changes in brown fat of infant rats. Hence it seems that 6-hydroxydopamine administration offers a simple and inexpensive experimental model for studies of the role norepinephrine-mediated sympathetic nervous system in brown tissue function and development.
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PMID:Effect of 6-hydroxydopamine and alpha-methyltyrosine on brown adipose tissue of infant rats. 87 60

The phosphoenolpyruvate carboxykinase (PEPCK) gene is highly expressed in cultured rat hepatoma cells, but extinguished in hepatoma x fibroblast hybrids. Extinction of PEPCK gene expression in hybrids is a polygenic process that involves several fibroblast loci, only one of which (tissue-specific extinguisher-1, TSE1) has been characterized to date. To identify sequence elements of the PEPCK gene that are involved both in TSE1-mediated extinction and in TSE1-independent processes, we assayed expression of chimeric PEPCK transgenes in transiently and stably transfected hybrid cells. We report that TSE1 responsiveness mapped to the PEPCK CRE (cAMP response element), as shown previously for the tyrosine aminotransferase gene. This was expected from the recent identification of the TSE1 gene product as a regulatory subunit of protein kinase A. However, none of the transgenes we assayed were responsive to TSE1-independent extinction mechanisms, suggesting that these controls require DNA sequences and/or chromatin structures that were not present in the transfected reporters. The implications of these findings are discussed.
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PMID:Multiple elements regulate phosphoenolpyruvate carboxykinase gene expression in hepatoma hybrid cells. 133 26

Cyclic AMP treatment of hepatoma cells leads to increased protein binding at the cyclic AMP response element (CRE) of the tyrosine aminotransferase (TAT) gene in vivo, as revealed by genomic footprinting, whereas no increase is observed at the CRE of the phosphoenolpyruvate carboxykinase (PEPCK) gene. Several criteria establish that the 43 kDa CREB protein is interacting with both of these sites. Two classes of CRE with different affinity for CREB are described. One class, including the TATCRE, is characterized by asymmetric and weak binding sites (CGTCA), whereas the second class containing symmetrical TGACGTCA sites shows a much higher binding affinity for CREB. Both classes show an increase in binding after phosphorylation of CREB by protein kinase A (PKA). An in vivo phosphorylation-dependent change in binding of CREB increases the occupancy of weak binding sites used for transactivation, such as the TATCRE, while high affinity sites may have constitutive binding of transcriptionally active and inactive CREB dimers, as demonstrated by in vivo footprinting at the PEPCK CRE. Thus, lower basal level and higher relative stimulation of transcription by cyclic AMP through low affinity CREs should result, allowing finely tuned control of gene activation.
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PMID:Phosphorylation of CREB affects its binding to high and low affinity sites: implications for cAMP induced gene transcription. 135 12

Transcription of phosphoenolpyruvate carboxykinase (PEPCK) gene is induced in response to cyclic AMP (cAMP) or cAMP elevating hormones. The role of transcription factors (DNA binding proteins) in the induction process has been studied. Two nuclear proteins, apparent mol. wt of 53 and 30 kDa, have been shown to bind to the 5'-flanking DNA of PEPCK gene which contains hormonal responsive elements as well as TATA box. DNA binding activity of 53 kDa protein increases by 3.5 fold in cells treated with 8-(4-chlorophenylthio)-cAMP (8-CPT-cAMP). The increased binding activity may be due to the phosphorylation of this protein by an activated cAMP-dependent protein kinase (cA kinase) in treated cells. Based on this observation, a hypothesis that 53 kDa may be specific transcription factor for PEPCK and therefore, play a major role in the regulation of this gene is proposed.
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PMID:Identification of DNA binding proteins which may regulate phosphoenolpyruvate carboxykinase gene. 191 37

We have examined the binding of factors in rat liver nuclear extracts to the phosphoenolpyruvate carboxykinase (PEPCK) gene cyclic AMP (cAMP) response element (CRE) and other CREs and have isolated a rat liver CRE-binding protein (CREBP) cDNA. In addition, we have examined the influence of altering the phosphorylation state of nuclear factors on both CRE binding and in vitro transcription. Specific binding to the PEPCK CRE was measured in a mobility shift assay. CRE sequences of the PEPCK, somatostatin, and glycoprotein hormone alpha subunit genes competed equally for binding of rat liver nuclear factors to the PEPCK CRE, whereas mutant PEPCK CRE sequences did not compete for binding. Oligonucleotides complementary to rat pheochromocytoma CREBP (Gonzalez et al., Nature [London] 337:749-752, 1989) were used to prime rat liver and brain cDNA in the polymerase chain reaction. The predominant CREBP molecule obtained was identical to the rat pheochromocytoma CREBP except for a 14-amino-acid deletion in the N-terminal half that was also present in a human placental cDNA (Hoeffler et al., Science 242:1430-1433, 1988). The regulation of transcription by cAMP was examined by coincubation of rat liver nuclear extract with the purified catalytic subunit of cAMP-dependent protein kinase (protein kinase A). Although binding to the CRE was unaffected, in vitro transcription directed by the PEPCK promoter was stimulated by catalytic subunit, and this effect was blocked by protein kinase inhibitor peptide. In contrast, when nuclear extract was coincubated with phosphatase, there was substantial inhibition of in vitro transcription directed by the PEPCK promoter, but there was no effect on binding to the CRE. The major effects of catalytic subunit were exerted through the CRE, but residual stimulation was evident in promoter fragments containing only the TATA element. These data suggest that factors are bound to the CRE at constitutively high levels and that their capacity for transcriptional activation is regulated by phosphorylation.
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PMID:Cyclic AMP-dependent protein kinase regulates transcription of the phosphoenolpyruvate carboxykinase gene but not binding of nuclear factors to the cyclic AMP regulatory element. 214 84

A cell-free system for the study of transcription from the promoter of the phosphoenolpyruvate carboxykinase (GTP) gene by using nuclear extracts from rat tissues was developed. The level of basal transcription from the phosphoenolpyruvate carboxykinase (PEPCK) promoter between -490 and +73 was highest when extracts from liver nuclei, rather than kidney, spleen, and HeLa nuclear extracts, were used. A series of 5' deletions and block mutations were also tested for their effects on basal transcription in vitro. The promoter truncated to -355 had the highest rate of basal transcription, while subsequent deletion to -277 markedly decreased the rate of transcription. Further deletion of the promoter to -134 resulted in a twofold increase in the basal level of transcription compared with that of the promoter deleted to -277. However, subsequent deletion of the NF-1-CCAAT-binding transcription factor binding site or the proximal cyclic AMP (cAMP) regulatory element caused a decrease in basal transcription. Block mutations were inserted into nine specific protein-binding regions of the PEPCK promoter previously shown to be of functional significance or to bind nuclear proteins. Mutation of the TATA box resulted in a 94% decrease in the level of transcription noted with the intact promoter, while sequence substitutions within the proximal cAMP regulatory element decreased the transcription rate to 25%. The addition of the catalytic subunit of cAMP-dependent protein kinase to the in vitro system stimulated transcription from the intact promoter or from a promoter deletion to -109. However, a promoter deletion to -68, which removes the proximal cAMP regulatory element, was unresponsive to added protein kinase catalytic subunit. These findings indicate that the PEPCK promoter between -490 and +73 contains sequences responsive to hormonal and tissue-specific factors in nuclei from rat tissues. The sensitivity of this in vitro transcription system closely mimics the process regulating PEPCK transcription in rat tissues and should make it ideal for testing the function of purified transcription factors.
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PMID:In vitro analysis of promoter elements regulating transcription of the phosphoenolpyruvate carboxykinase (GTP) gene. 230 49

Cyclic AMP-stimulated mRNA levels in cultured rat hepatocytes were inhibited by three different inhibitors of cAMP-dependent protein kinase activity: (i) Rp-cAMPS, a cAMP analog with a sulfur substitution at the equatorial oxygen of the cyclic monophosphate; (ii) H8, an isoquinoline sulfonamide derivative; and (iii) PKI, a 20-amino acid synthetic peptide of the Walsh protein kinase inhibitor. These inhibitors specifically blocked the cAMP-stimulated increase in mRNA for tyrosine aminotransferase and phosphoenolpyruvate carboxykinase; they had no effect on the level of albumin mRNA which is not cAMP regulated. These results provide functional evidence that kinase activity involving protein phosphorylation is required in cAMP-mediated gene expression in mammalian cells.
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PMID:Catalytic subunit of cAMP-dependent protein kinase is essential for cAMP-mediated mammalian gene expression. 283 Jan 34

Stage VI Xenopus oocytes were injected with a plasmid (pBB0.6-CAT) which contains the cAMP regulatory element (CRE) from the rat liver phosphoenolpyruvate carboxykinase (PEPCK) gene fused upstream from a reporter gene [chloramphenicol acetyltransferase (CAT)]. Inhibition of the expression of the reporter gene (average = 51%) was observed in the presence of 10 microM progesterone, which is known to lead to inactivation of the oocyte cAMP dependent protein kinase (A kinase). In contrast, oocytes injected with a control plasmid (pSV2CAT), which contains no CRE, exhibited a variable increase (average = 31%) in CAT activity after progesterone treatment. Injection of the purified bovine cardiac A kinase catalytic subunit prior to exposure of oocytes injected with pBB0.6 CAT to progesterone prevents the loss of CAT activity generated by incubation with the steroid. Gel retardation analyses with oocyte lysates and a labeled synthetic oligonucleotide fragment containing the CRE from the PEPCK gene showed the existence of a complex with the same Rf and specificity as that formed with rat liver extracts. Subsequent exposure to progesterone, however, led to a rapid and extensive decrease in this binding activity. Taken together, these results are consistent with but do not prove the hypothesis that progesterone treatment and A kinase inactivation lead to a decrease in pBB0.6 CAT expression by virtue of a decline in the binding activity of an oocyte factor(s) to the CRE of the PEPCK fragment in pBB0.6-CAT, thereby decreasing transcription of the CAT gene.
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PMID:Progesterone decreases DNA binding factor activity and the expression in Xenopus oocytes of a cAMP responsive gene from rat liver. 297 91


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