Termination of immediate-early gene expression after stimulation by parathyroid hormone or isoproterenol

Xin Chen, Jia Chun Dai, Edward M. Greenfield

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

cAMP/PKA signaling transiently stimulates mRNA expression of immediate-early genes, including IL-6 and c-fos. We confirmed that these mRNAs are transiently stimulated by parathyroid hormone (PTH) in ROS 17/2.8 osteoblastic cells. Consistent with the role for cAMP/PKA signaling in this response PTH induces transient cAMP elevation, PKA activation, and cAMP-responsive element-binding protein (CREB) phosphorylation. Our goal was to determine whether termination of immediate-early gene expression is due to receptor desensitization or cAMP degradation. The approaches used were 1) inhibition of PTH receptor desensitization with G proteincoupled receptor kinase 2 (GRK2) antisense oligonucleotides or antisense plasmids, 2) sustained activation of adenyl cyclase with forskolin, and 3) inhibition of cAMP degradation with 3-isobutyl-l-methylxanthine. These experiments show that mechanisms downstream of receptor desensitization and cAMP degradation are primarily responsible for termination of PKA activity, CREB phosphorylation, and immediate-early gene expression. Similar conclusions were also obtained in response to PTH in a second osteoblastic cell line (MC3T3-E1) and in response to isoproterenol in NIH3T3 fibroblasts. This conclusion may therefore reflect a general mechanism for termination of immediate-early gene expression after induction by cAMP/PKA.

Original languageEnglish (US)
Pages (from-to)C1432-C1440
JournalAmerican Journal of Physiology - Cell Physiology
Volume283
Issue number5 52-5
DOIs
StatePublished - Nov 2002

Keywords

  • IL-6
  • Osteoblast
  • Receptor desensitization
  • c-fos
  • cAMP degradation

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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