12-O-tetradecanoyl-phorbol-13-acetate (TPA) counteracts the cAMP up-regulation of the expression of the stimulatory guanine nucleotide binding protein (Gsα) and Gsα messenger RNA in cultured pig thyroid cells

K. Dib, B. Delemer, A. El Jamali, B. Haye, C. Jacquemin, C. Corréze

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

In this study, we examined whether the protein kinase C (PKC) pathway could interfere with the regulation of Gs protein in porcine thyroid cells. The two days culture of cells with 12-O-tetradecanoylphorbol 13-acetate (TPA) (0.1 μM) alone neither affected adenylyl cyclase activity, nor the level of Gsα protein in membranes when compared with control cells. The co-addition of TPA with thyrotropin (TSH) (1 mU/ml) or forskolin (fk) (10 μM) in the culture medium, abolished the stimulatory effects of either agonists on the activation of adenylyl cyclase by fk or [AlF4]- and on the increase of Gsα protein. By contrast, TPA had effects neither on the Gi-dependent inhibition of adenylyl cyclase nor on Giα proteins levels. The level of Gsα mRNA measured by Northern blot analysis was increased (200%) in TSH- or fk-treated cells and this increase was counteracted by TPA. The effects of TPA observed after 6-9 h of contact with cells were mimicked by mezerein, a non-phorbol protein kinase C activator and blocked by bisindolylmaleimide a specific protein kinase C inhibitor (GF 109203X). These results suggest that the activation of the PKC pathway prevents the cAMP-dependent up-regulation of Gsα protein and Gsα mRNA expression.

Original languageEnglish (US)
Pages (from-to)229-235
Number of pages7
JournalMolecular and Cellular Endocrinology
Volume99
Issue number2
DOIs
StatePublished - Mar 1994

Keywords

  • Adenylyl cyclase
  • Forskolin
  • G protein
  • Messenger RNA
  • Thyroid cell
  • Thyroid-stimulating hormone
  • α-Subunit

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

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