[Abstract Title]. - Society for Neuroscience

Poster
279. Steroids and Plasticity I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 279.17/MM31
Topic: E.01.c. Steroids and plasticity
Support: NIH HD042635
NIH DA013185
Title: Surface biotinylation reveals an estradiol regulation of membrane ERα levels
Authors: *R. DOMINGUEZ, G. BONDAR, P. MICEVYCH;
Neurobio., David Geffen Sch. of Medicin, Los Angeles, CA
Abstract: Estradiol regulates reproduction by binding to and activating both intracellular and
membrane estrogen receptor-α (ERα) in the hypothalamus and limbic system. Activation of
intracellular ERα results in the formation of dimers, which bind to specific sites on DNA and
mediate the transcription of estradiol sensitive genes. There is a rapid component of estradiol
action that also regulates reproduction through the interaction of a membrane-associated ERα
with a metabotropic glutamate receptor-1a to activate intracellular signaling pathways. While the
localization and activation of ERα in the plasma membrane has been demonstrated, the question
of whether ERα is a transmembrane protein remains an open question. The present study tested
the hypothesis that a portion of the ERα is exposed to the extracellular environment and that
estradiol regulates the levels of ERα in the membrane. Surface biotinylation was used to identify
membrane proteins. Treatment of neurons and astrocytes in vitro with 10 nM estradiol for 0-120
min had a biphasic effect on levels of biotinylated ERα in the plasma membrane. The amount of
biotinylated ERα increased for the first 30-60 min of estradiol treatment. Hypothalamic tissue
analyzed 30 min after the third cycle of 5 µg estradiol benzoate every fourth day, also had an
increase in membrane ERα immunoreactivity revealed by western blot. These results indicate
that estradiol regulates the levels of ERα in the membrane suggesting a mechanism of regulation
that involves translocation to and internalization from the plasma membrane. Supported by NIH
HD042635 & DA013185.
Disclosures: R. Dominguez , None; G. Bondar, None; P. Micevych, None.
Poster
279. Steroids and Plasticity I