Transcriptional response to calcium-sensing receptor stimulation

Endocrinology. 2012 Oct;153(10):4716-28. doi: 10.1210/en.2012-1343. Epub 2012 Aug 17.

Abstract

Elevated extracellular Ca(2+) concentrations stimulate the G-protein coupled receptor calcium-sensing receptor. Here we show that this stimulation induces the expression of biologically active early growth response protein 1 (Egr-1), a zinc finger transcription factor. Expression of a dominant-negative mutant of the ternary complex factor Ets-like protein-1 (Elk-1), a key transcriptional regulator of serum response element-driven gene transcription, prevented Egr-1 expression, indicating that Elk-1 or related ternary complex factors connect the intracellular signaling cascade elicited by activation of calcium-sensing receptors with transcription of the Egr-1 gene. These data were corroborated by the fact that stimulation of calcium-sensing receptors increased the transcriptional activation potential of Elk-1. In addition, activator protein-1 (AP-1) transcriptional activity was significantly elevated after the stimulation of calcium-sensing receptors. The expression of a dominant-negative mutant of Elk-1 reduced c-Fos expression and prevented the up-regulation of AP-1 activity as a result of calcium-sensing receptor stimulation, indicating that ternary complex factors control both Egr-1- and AP-1-regulated transcription. In addition, AP-1 activity was reduced after the expression of a dominant-negative mutant of c-Jun in cells expressing an activated calcium-sensing receptor. Stimulus-transcription coupling leading to the up-regulation of Egr-1 and AP-1 controlled transcription in cells expressing calcium-sensing receptors required the protein kinases Raf and ERK, whereas the overexpression of MAPK phosphatase-1 interrupted the signaling cascade connecting calcium-sensing receptor stimulation with transcription of Egr-1 and AP-1 controlled genes. The fact that calcium-sensing receptor stimulation activates the transcription factors Egr-1, Elk-1, and AP-1 indicates that regulation of gene transcription is an integral part of calcium-sensing receptor induced signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Early Growth Response Protein 1 / biosynthesis
  • HEK293 Cells
  • Humans
  • Promoter Regions, Genetic
  • Receptors, Calcium-Sensing / genetics*
  • Receptors, Calcium-Sensing / metabolism
  • Signal Transduction / physiology*
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism
  • Transcription, Genetic*
  • Transcriptional Activation*
  • ets-Domain Protein Elk-1 / genetics
  • ets-Domain Protein Elk-1 / metabolism

Substances

  • EGR1 protein, human
  • Early Growth Response Protein 1
  • Receptors, Calcium-Sensing
  • Transcription Factor AP-1
  • ets-Domain Protein Elk-1
  • Calcium