Exp Mol Med.  2012 Oct;44(10):615-621.

Effects of echinomycin on endothelin-2 expression and ovulation in immature rats primed with gonadotropins

• Wang Z
• Zhang Z
• Wu Y
• Chen L
• Luo Q
• Zhang J
• Chen J
• Luo Z
• Huang X
• Cheng Y

Abstract

Echinomycin is a small-molecule inhibitor of hypoxia-inducible factor-1 DNA-binding activity, which plays a crucial role in ovarian ovulation in mammalians. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1alpha-mediated endothelin (ET)-2 expressions contributed to ovarian ovulation in response to human chorionic gonadotropin (hCG) during gonadotropin-induced superuvulation. By real-time RT-PCR analysis, ET-2 mRNA level was found to significantly decrease in the ovaries after echinomycin treatment, while HIF-1alpha mRNA and protein expression was not obviously changed. Further analysis also showed that these changes of ET-2 mRNA were consistent with HIF-1 activity in the ovaires, which is similar with HIF-1alpha and ET-2 expression in the granulosa cells with gonadotropin and echinomycin treatments. The results of HIF-1alpha and ET-2 expression in the granulosa cells transfected with cis-element oligodeoxynucleotide (dsODN) under gonadotropin treatment further indicated HIF-1alpha directly mediated the transcriptional activation of ET-2 during gonadotropin-induced superuvulation. Taken together, these results demonstrated that HIF-1alpha-mediated ET-2 transcriptional activation is one of the important mechanisms regulating gonadotropin-induced mammalian ovulatory precess in vivo.

Keyword

echinomycin; endothelin-2; gene expression regulation; gonadotropins; granulosa cells; hypoxia-inducible factor 1, alpha subunit; ovary; ovulation

MeSH Terms

Animals
Cells, Cultured
Chorionic Gonadotropin/*pharmacology
Echinomycin/*pharmacology
Endothelin-2/genetics/*metabolism
Female
Gonadotropins, Equine/*pharmacology
Granulosa Cells/drug effects/metabolism
Humans
Hypoxia-Inducible Factor 1, alpha Subunit/*antagonists & inhibitors/genetics/metabolism/physiology
Oligonucleotides/genetics
Ovary/cytology/drug effects/physiology
Rats
Rats, Sprague-Dawley
Superovulation/*drug effects
Transcriptional Activation