Dopaminergic and Ligand-Independent Activation of Steroid Hormone Receptors

In vitro, dopamine faithfully mimicked the effect of progesterone by causing a translocation of chicken progestersone receptor (cPR) from cytoplasm to nucleus, and a serine residue in the cPR was identified that is not necessary for progester one-dependent activation of cPR, but is essential for dopamine activation of this receptor.

Abstract

The current view of how steroid hormone receptors affect gene transcription is that these receptors, on binding ligand, change to a state in which they can interact with chromatin and regulate transcription of target genes. Receptor activation is believed to be dependent only on this ligand-binding event. Selected steroid hormone receptors can be activated in a ligand-independent manner by a membrane receptor agonist, the neurotransmitter dopamine. In vitro, dopamine faithfully mimicked the effect of progesterone by causing a translocation of chicken progesterone receptor (cPR) from cytoplasm to nucleus. Dual activation by progesterone and dopamine was dissociable, and a serine residue in the cPR was identified that is not necessary for progesterone-dependent activation of cPR, but is essential for dopamine activation of this receptor.