Expression of TCF, TPF/YY1, and the Sp family transcription factors in rabbit endometrium throughout pregnancy

TCF, TPF/YY1, and the Sp family are specific transcription factors that bind sequences found within the uteroglobin (UG) gene promoter region that are necessary for transcription. To date, UG gene expression and regulation in vivo are not fully understood. The purpose of this study was to assess the expression patterns of these factors in the rabbit endometrium throughout pregnancy.

Endometrial nuclear extracts were obtained from female rabbits on days 0, 3, 5, 7, 15, and 28 after mating. Transcription factor expression was assessed by DNA-protein binding assays using endometrial nuclear proteins and specific oligonucleotides. Band shifts were observed on 4% acrylamide gels and analyzed by densitometry.

The expression patterns of the transcription factors analyzed here differed, as TPF/YY1 and Sp3/SpR-2 were expressed constitutively while TCF and Sp1 showed variable expression patterns throughout pregnancy.

Our results suggest that UG gene expression in the intact pregnant rabbit is controlled by two constitutive and two regulated factors, and that the DNA-binding sites are located at the TATA box and the GT1 sites within the gene promoter.