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Dopaminergic and ligand-independent activation of steroid hormone receptors

R F Power1, S K Mani, J Codina

  • 1Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.

Science (New York, N.Y.)
|December 13, 1991
PubMed

Insights

Steroid hormone receptors can be activated without a ligand, as dopamine mimics progesterone. A specific serine residue in the chicken progesterone receptor (cPR) is key for this ligand-independent activation.

Area of Science:

  • Molecular Endocrinology
  • Neuroendocrinology
  • Gene Regulation

Background:

  • Steroid hormone receptors traditionally require ligand binding for activation and gene transcription regulation.
  • Receptor activation is generally considered solely dependent on the ligand-binding event.
  • Emerging evidence suggests alternative pathways for receptor activation.

Purpose of the Study:

  • To investigate ligand-independent activation of steroid hormone receptors.
  • To explore the role of dopamine as a non-traditional activator of the progesterone receptor.
  • To identify specific molecular mechanisms underlying dopamine-mediated receptor activation.

Main Methods:

  • In vitro experiments using chicken progesterone receptor (cPR).
  • Assessing receptor translocation from cytoplasm to nucleus.
  • Mutational analysis of specific amino acid residues within the cPR.

Main Results:

  • Dopamine, a neurotransmitter, activated cPR in a ligand-independent manner.
  • Dopamine mimicked progesterone's effect by inducing cPR translocation to the nucleus.
  • A specific serine residue was identified as essential for dopamine-dependent activation but not for progesterone-dependent activation.

Conclusions:

  • Steroid hormone receptors can be activated through ligand-independent pathways.
  • Dopamine acts as a functional agonist for the progesterone receptor, highlighting cross-talk between signaling systems.
  • Specific amino acid residues mediate distinct activation pathways, offering insights into receptor regulation.

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