PT  - JOURNAL ARTICLE
AU  - Stephan Immenschuh
AU  - Thomas Kietzmann
AU  - Vera Hinke
AU  - Matthias Wiederhold
AU  - Norbert Katz
AU  - Ursula Muller-Eberhard
TI  - The Rat Heme Oxygenase-1 Gene Is Transcriptionally Induced via the Protein Kinase A Signaling Pathway in Rat Hepatocyte Cultures
AID  - 10.1124/mol.53.3.483
DP  - 1998 Mar 01
TA  - Molecular Pharmacology
PG  - 483--491
VI  - 53
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/53/3/483.short
4100  - http://molpharm.aspetjournals.org/content/53/3/483.full
SO  - Mol Pharmacol1998 Mar 01; 53
AB  - Heme oxygenase-1 (HO-1) is the inducible form of the rate-limiting enzyme of heme degradation; it regulates the cellular content of heme. To investigate the role of the cAMP-dependent protein kinase (PKA) signaling pathway on hepatic HO-1 gene expression, primary rat hepatocyte cultures were treated with the PKA-stimulating agents dibutyryl-cAMP (Bt2cAMP), forskolin, and glucagon. HO-1 mRNA levels were induced by these agents in a time-dependent manner with a transient maximum after 6 hr of treatment. The induction of HO-1 was dose dependent, reaching a maximum at concentrations of 250 μm Bt2cAMP and 50 nm glucagon, respectively. The accumulation of HO-1 mRNA correlated with increased levels of HO-1 protein as determined by Western blot analysis. The Bt2cAMP-dependent induction of HO-1 mRNA expression was prevented by pretreatment with the PKA inhibitor KT5720 but not with the protein kinase G inhibitor KT5823. HO-1 mRNA induction by CdCl2 and heme was differentially affected by Bt2cAMP. Up-regulation of the HO-1 gene by Bt2cAMP occurred on the transcriptional level as determined by nuclear run-off assay and blocking of the Bt2cAMP-dependent induction of HO-1 mRNA by actinomycin D. Treatment with Bt2cAMP increased the half-life of HO-1 mRNA from 4.7 to 5.5 hr. Taken together, the results of the current study demonstrate that HO-1 gene expression is induced by activation of the cAMP signal transduction pathway via a transcriptional mechanism in primary rat hepatocyte cultures.