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Signal transduction pathways implicated in the decrease in CYP1A1, 1A2 and 3A6 activity produced by serum from

Mihaela Levitchi1, Caroline Fradette, Anne-Marie Bleau

  • 1Département de Pharmacologie, Faculté de Médecine, Université de Montréal, Montreal, Quebec, Canada H3C 3J7.

Biochemical Pharmacology
|July 10, 2004
PubMed

Insights

Inflammation and viral infections reduce cytochrome P450 (CYP450) enzyme activity via specific signaling pathways. This study identifies protein tyrosine kinases, mitogen-activated protein kinase, and protein kinase C as key mediators in this process.

Area of Science:

  • Biochemistry
  • Pharmacology
  • Immunology

Background:

  • Cytochrome P450 (CYP450) enzymes are crucial for drug metabolism.
  • Inflammatory and viral conditions can alter CYP450 activity, impacting drug efficacy and toxicity.
  • Understanding the underlying molecular mechanisms is essential for managing drug therapy during illness.

Purpose of the Study:

  • To investigate the signal transduction pathways responsible for the decrease in CYP450 1A1/1A2 and 3A6 activity during inflammation and viral infections.
  • To identify specific kinases involved in mediating these changes in enzyme activity.

Main Methods:

  • Hepatocytes from rabbits with induced inflammation were incubated with inflammatory or viral sera.
  • Inhibitors of various protein kinases were used to block specific signaling pathways.
  • Protein phosphorylation, specifically of Erk1/2, was assessed.
  • Changes in total CYP450 content and specific isoform activities were measured.

Main Results:

  • Serum from inflammatory and viral conditions reduced total CYP450 content and CYP1A1/1A2 and 3A6 activity.
  • This reduction was partially prevented by inhibiting Janus-associated protein tyrosine kinase, double-stranded RNA-dependent protein kinase, protein kinase C, and p42/44 mitogen-activated protein kinase.
  • Inflammatory serum increased Erk1/2 phosphorylation, indicating p42/44 mitogen-activated protein kinase activation.
  • Nitric oxide was indirectly implicated in the enzyme activity decrease.

Conclusions:

  • The decrease in CYP450 1A1/1A2 and 3A6 activity during inflammation and viral infections involves the activation of protein tyrosine kinases, p42/44 mitogen-activated protein kinase, and protein kinase C.
  • These signaling pathways mediate the observed reduction in enzyme activity without altering protein expression.
  • Nitric oxide may also play a role in this inhibitory process.

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