Membrane-initiated estradiol signaling in immortalized hypothalamic N-38 neurons.

ABSTRACT: Regulation of sexual reproduction by estradiol involves the activation of estrogen receptors (ERs) in the hypothalamus. Of the two classical ERs involved in reproduction, ER? appears to be the critical isoform. The role of ER? in reproduction has been found to involve a nuclear ER? that induces a genomic mechanism of action. More recently, a plasma membrane ER? has been shown to trigger signaling pathways involved in reproduction. Mechanisms underlying membrane-initiated estradiol signaling are emerging, including evidence that activation of plasma membrane ER? involves receptor trafficking. The present study examined the insertion of ER? into the plasma membrane of N-38 neurons, an immortalized murine hypothalamic cell line. We identified, using western blotting and PCR that N-38 neurons express full-length 66kDa ER? and a 52kDa ER? spliced variant missing the fourth exon - ER??4. Using surface biotinylation, we observed that treatment of N-38 neurons with estradiol or with a membrane impermeant estradiol elevated plasma membrane ER? protein levels, indicating that membrane signaling increased receptor insertion into the cell membrane. Insertion of ER? was blocked by the ER antagonist ICI 182,780 or with the protein kinase C (PKC) pathway inhibitor bisindolylmaleimide (BIS). Downstream membrane-initiated signaling was confirmed by estradiol activation of PKC-theta (PKC?) and the release of intracellular calcium. These results indicate that membrane ER? levels in N-38 neurons are dynamically autoregulated by estradiol.

SUBMITTER: Dominguez R 

PROVIDER: S-EPMC3636190 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature