Regulation of oxytocin expression in the bovine corpus luteum. Orphan receptors and the oxytocin promoter.
The bovine oxytocin gene is massively up-regulated during the early development of the corpus luteum. Oxytocin transcription is induced in a highly synchronous fashion in the granulosa cells of the dominant follicle at the time of ovulation. The possibility to isolate large numbers of differentiating granulosa-luteal cells from exactly defined stages of development allows the investigation of the factors controlling oxytocin expression in vivo by molecular and cell biology methods. Using primary cultures of bovine granulosa cells the synergistic activation of oxytocin transcription by the cAMP pathway and stimulation of IGF-I or insulin receptors could be established. Analysis of transcription factors isolated from the nuclei of bovine granulosa cells and corpus luteum led to the identification of the tissue-specific orphan receptor SF-1 binding to the promoter of the actively transcribed oxytocin gene. The luteinizing bovine granulosa cells provide the only easily accessible experimental system established so far in which the endogenous oxytocin gene is expressed. Although the link between increased cAMP level and receptor tyrosine kinase activation on the one hand and the induction of oxytocin transcription on the other has not been established yet, these experiments constitute one of the few direct approaches to investigate the complexity of events that regulate oxytocin expression in vivo.
Walther
N
N
Institute for Hormone and Fertility Research, University of Hamburg, Germany.
Wehrenberg
U
U
Kascheike
B
B
Jansen
M
M
Ivell
R
R
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D002478:Cells, Cultured; D003338:Corpus Luteum / Q000254:growth & development / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins; D006801:Humans; D008184:Luteal Cells / Q000378:metabolism; D008969:Molecular Sequence Data; D010121:Oxytocin / Q000235:genetics*; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D010121:Oxytocin; D004247:DNA; D000242:Cyclic AMP