Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes
There are many factors that regulate the rate of synthesis of δ- aminolevulinate synthase (ALA-S), the enzyme which governs the rate-limiting step in heme biosynthesis. In rat hepatocytes, phenobarbital increases ALA-S gene transcription and dibutyryl cAMP potentiates this induction, whereas insulin...
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1997
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Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00039861_v341_n2_p259_Varone http://hdl.handle.net/20.500.12110/paper_00039861_v341_n2_p259_Varone |
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paper:paper_00039861_v341_n2_p259_Varone2023-06-08T14:25:03Z Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes Varone, Cecilia Laura Cánepa, Eduardo Tomás aminolevulinic acid synthase cAMP diacylglycerol gene expression hepatocytes phorbol esters protein kinase C 5 aminolevulinate synthase bucladesine cyclic AMP dioctanoin glucose heme insulin messenger RNA phenobarbital phorbol 13 acetate 12 myristate protein kinase C animal cell article controlled study enzyme activation gene expression regulation liver cell male nonhuman priority journal protein expression rat transcription regulation Animalia Canis familiaris There are many factors that regulate the rate of synthesis of δ- aminolevulinate synthase (ALA-S), the enzyme which governs the rate-limiting step in heme biosynthesis. In rat hepatocytes, phenobarbital increases ALA-S gene transcription and dibutyryl cAMP potentiates this induction, whereas insulin and glucose have the opposite effect. The present report provides evidence that protein kinase C (PKC) activation negatively influences ALA-S mRNA levels, as measured by Northern and slot-blot analysis. The addition of 1,2-dioctanoyl-sn-glycerol (DOG) or 12-O-tetradecanoylphorbol 13-acetate (TPA), a PKC activator that mimics diacylglycerol function, to cultures led to a significant decrease of both basal and phenobarbital-induced ALA-S mRNA levels in a dose-dependent manner. This TPA effect depends on the specific activation of PKC because the analog 4α-phorbol 12,13-diacetate, a nonstimulatory PKC phorbol ester, is unable to inhibit ALA-S mRNA. Furthermore, the effect of TPA is blocked by the PKC inhibitors staurosporine and calphostin C. Desensitization of the PKC pathway by prolonged exposure to TPA abolished the subsequent action of the phorbol ester. On the other hand, neither TPA nor DOG modified the half-life of ALA-S mRNA. The study of the combinatorial action of TPA and cAMP revealed that the inhibitory effect of TPA overcomes dibutyryl cAMP induction. Thus, these results indicate that PKC plays an essential role in regulating ALA-S expression, probably at a transcriptional level. Fil:Varone, C.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Cánepa, E.T. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00039861_v341_n2_p259_Varone http://hdl.handle.net/20.500.12110/paper_00039861_v341_n2_p259_Varone |
institution |
Universidad de Buenos Aires |
institution_str |
I-28 |
repository_str |
R-134 |
collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
topic |
aminolevulinic acid synthase cAMP diacylglycerol gene expression hepatocytes phorbol esters protein kinase C 5 aminolevulinate synthase bucladesine cyclic AMP dioctanoin glucose heme insulin messenger RNA phenobarbital phorbol 13 acetate 12 myristate protein kinase C animal cell article controlled study enzyme activation gene expression regulation liver cell male nonhuman priority journal protein expression rat transcription regulation Animalia Canis familiaris |
spellingShingle |
aminolevulinic acid synthase cAMP diacylglycerol gene expression hepatocytes phorbol esters protein kinase C 5 aminolevulinate synthase bucladesine cyclic AMP dioctanoin glucose heme insulin messenger RNA phenobarbital phorbol 13 acetate 12 myristate protein kinase C animal cell article controlled study enzyme activation gene expression regulation liver cell male nonhuman priority journal protein expression rat transcription regulation Animalia Canis familiaris Varone, Cecilia Laura Cánepa, Eduardo Tomás Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
topic_facet |
aminolevulinic acid synthase cAMP diacylglycerol gene expression hepatocytes phorbol esters protein kinase C 5 aminolevulinate synthase bucladesine cyclic AMP dioctanoin glucose heme insulin messenger RNA phenobarbital phorbol 13 acetate 12 myristate protein kinase C animal cell article controlled study enzyme activation gene expression regulation liver cell male nonhuman priority journal protein expression rat transcription regulation Animalia Canis familiaris |
description |
There are many factors that regulate the rate of synthesis of δ- aminolevulinate synthase (ALA-S), the enzyme which governs the rate-limiting step in heme biosynthesis. In rat hepatocytes, phenobarbital increases ALA-S gene transcription and dibutyryl cAMP potentiates this induction, whereas insulin and glucose have the opposite effect. The present report provides evidence that protein kinase C (PKC) activation negatively influences ALA-S mRNA levels, as measured by Northern and slot-blot analysis. The addition of 1,2-dioctanoyl-sn-glycerol (DOG) or 12-O-tetradecanoylphorbol 13-acetate (TPA), a PKC activator that mimics diacylglycerol function, to cultures led to a significant decrease of both basal and phenobarbital-induced ALA-S mRNA levels in a dose-dependent manner. This TPA effect depends on the specific activation of PKC because the analog 4α-phorbol 12,13-diacetate, a nonstimulatory PKC phorbol ester, is unable to inhibit ALA-S mRNA. Furthermore, the effect of TPA is blocked by the PKC inhibitors staurosporine and calphostin C. Desensitization of the PKC pathway by prolonged exposure to TPA abolished the subsequent action of the phorbol ester. On the other hand, neither TPA nor DOG modified the half-life of ALA-S mRNA. The study of the combinatorial action of TPA and cAMP revealed that the inhibitory effect of TPA overcomes dibutyryl cAMP induction. Thus, these results indicate that PKC plays an essential role in regulating ALA-S expression, probably at a transcriptional level. |
author |
Varone, Cecilia Laura Cánepa, Eduardo Tomás |
author_facet |
Varone, Cecilia Laura Cánepa, Eduardo Tomás |
author_sort |
Varone, Cecilia Laura |
title |
Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
title_short |
Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
title_full |
Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
title_fullStr |
Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
title_full_unstemmed |
Evidence that protein kinase C is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
title_sort |
evidence that protein kinase c is involved in δ-aminolevulinate synthase expression in rat hepatocytes |
publishDate |
1997 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00039861_v341_n2_p259_Varone http://hdl.handle.net/20.500.12110/paper_00039861_v341_n2_p259_Varone |
work_keys_str_mv |
AT varonececilialaura evidencethatproteinkinasecisinvolvedindaminolevulinatesynthaseexpressioninrathepatocytes AT canepaeduardotomas evidencethatproteinkinasecisinvolvedindaminolevulinatesynthaseexpressioninrathepatocytes |
_version_ |
1768543539282575360 |