Retinoic acid (RA) regulates 17beta-hydroxysteroid dehydrogenase type 2 expression in endometrium: interaction of RA receptors with specificity protein (SP) 1/SP3 for estradiol metabolism.
BACKGROUND
The enzyme 17beta-hydroxysteroid dehydrogenase type 2 (HSD17B2) exerts a local antiestrogenic effect by metabolizing biologically active estradiol to inactive estrone in endometrial epithelial cells. Retinoic acid (RA) induces HSD17B2 expression, but the underlying mechanism is not known.


OBJECTIVE
Our objective was to elucidate the molecular mechanisms responsible for HSD17B2 expression in human endometrial cells.


METHODS
Human endometrial Ishikawa and RL95-2 cell lines were cultured in the presence or absence of RA to analyze endogenous HSD17B2 expression, transcription factor complex formation, and promoter activity.


RESULTS
RA induced HSD17B2 mRNA levels in a dose- and time-dependent manner in endometrial cells. The RA antagonist ANG11273 abolished RA-induced HSD17B2 expression. Small interfering RNA ablation of RA receptor (RAR)alpha or retinoid X receptor (RXR)alpha completely blocked RA-induced HSD17B2 gene expression. Analysis of serial deletion and site-directed mutants of the HSD17B2 promoter fused to a reporter gene indicated that RA induction requires a cis-regulatory sequence that binds the specificity protein (SP) class of transcription factors. Chromatin-immunoprecipitation-PCR and gel-shift assays showed that RARalpha/RXRalpha and SP1/SP3 interact with this HSD17B2 promoter sequence. Small interfering RNA ablation of SP1 and SP3 expression markedly decreased HSD17B2 basal expression and blocked RA-induced expression. Finally, immunoprecipitationimmunoblotting demonstrated RA-induced interactions between RARalpha/RXRalpha and SP1/SP3 in intact endometrial cells.


CONCLUSIONS
In endometrial epithelial cells, RA stimulates formation of a multimeric complex comprised of RARalpha/RXRalpha tethered to transcription factors SP1 and SP3 on the HSD17B2 promoter. Assembly of this transcriptional complex is necessary for RA induction of HSD17B2 expression and may be an important mechanism for local estradiol inactivation in the endometrium.
Cheng
You-Hong
YH
Division of Reproductive Biology Research, Department of Obstetrics and Gynecology, Northwestern University, 303 E. Superior Street, Chicago, IL 60611, USA. y-cheng@northwestern.edu
Yin
Ping
P
Xue
Qing
Q
Yilmaz
Bertan
B
Dawson
Marcia I
MI
Bulun
Serdar E
SE
D015067:17-Hydroxysteroid Dehydrogenases / Q000235:genetics*; D045744:Cell Line, Tumor; D004717:Endometrium / Q000201:enzymology*; D004847:Epithelial Cells / Q000201:enzymology; D004958:Estradiol / Q000378:metabolism*; D004960:Estradiol Dehydrogenases; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000494:pharmacology; D018168:Receptors, Retinoic Acid / Q000502:physiology*; D016329:Sp1 Transcription Factor / Q000502:physiology*; D051705:Sp3 Transcription Factor / Q000502:physiology*; D014212:Tretinoin / Q000494:pharmacology*
D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; D051705:Sp3 Transcription Factor; D004958:Estradiol; D014212:Tretinoin; D015067:17-Hydroxysteroid Dehydrogenases; D004960:Estradiol Dehydrogenases; C523763:HSD17B2 protein, human