Activity of estradiol and selective estrogen receptor modulators in the mouse N20.1 oligodendrocyte/astrocytes cell line.
OBJECTIVE
The mechanism through which estrogen exerts its neuroprotective and anti-neurodegenerative effects in the central nervous system is poorly understood. Human glial cells are implicated in the pathogenesis of Alzheimer's disease and have both alpha and beta estrogen receptors (ER). We developed a glial cell model for ER function using the N20.1 mouse oligodendroglial cell line to evaluate the response of ERalpha and ERbeta to estradiol (E2), a raloxifene analog LY117018 (LY) and 4-hydroxytamoxifen (4OHT).


METHODS
We tested the ability of exogenous ER to activate transcription in response to ligands (100 nM) using the glial cell line N20.1 in a transient cotransfection assay with an ERalpha or ERbeta expression vector, an ERE-driven reporter and a Renilla luciferase transfection control.


RESULTS
Endogenous ER was not detected in the N20.1 cells by Western immunoblotting. E2 stimulated both ERalpha and ERbeta on both ERE- and AP-1 driven promoters. The transcription stimulation by E2 in the ERalpha and ERbeta through the AP-1driven promoter, though significant, was not of the same magnitude as the stimulation of the ERalpha through the ERE-driven promoter. 4OHT and LY did not show significant transcriptional activation of either the ERalpha or ERbeta, through either the ERE or AP-1 driven promoters. LY, at a 10-fold higher concentration than E2, showed a difference in its antagonist activity on the ERbeta through the AP-1 pathway when compared with the ERE- driven promoter, demonstrating not only promoter specificity, but also receptor specificity.


CONCLUSIONS
This is the first description of the activity of 4OHT and LY on estrogen receptors in glia.
Guzmán
Cristina B
CB
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, USA. cguzman@med.wayne.edu
Deighton-Collins
Sarah
S
Martinez
Angela
A
Kleerekoper
Michael
M
Zhao
Changqing
C
Benjamins
Joyce A
JA
Skafar
D F
DF
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D008024:Ligands; D008156:Luciferases / Q000235:genetics; D051379:Mice; D009457:Neuroglia / Q000187:drug effects; D009836:Oligodendroglia / Q000187:drug effects / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011759:Pyrrolidines / Q000494:pharmacology; D020849:Raloxifene Hydrochloride / Q000031:analogs & derivatives / Q000494:pharmacology; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D014162:Transfection
D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D008024:Ligands; D011759:Pyrrolidines; D020845:Selective Estrogen Receptor Modulators; D013876:Thiophenes; D013629:Tamoxifen; C016601:afimoxifene; D020849:Raloxifene Hydrochloride; D004958:Estradiol; C025430:LY 117018; D008156:Luciferases