Cyclic AMP-induced forkhead transcription factor, FKHR, cooperates with CCAAT/enhancer-binding protein beta in differentiating human endometrial stromal cells.
Decidual transformation of human endometrial stromal (ES) cells requires sustained activation of the protein kinase A (PKA) pathway. In a search for novel transcriptional mediators of this process, we used differential display PCR analysis of undifferentiated primary ES cells and cells stimulated with 8-bromo-cAMP (8-Br-cAMP). We now report on the role of forkhead homologue in rhabdomyosarcoma (FKHR), a recently described member of the forkhead/winged-helix transcription factor family, as a mediator of endometrial differentiation. Sustained 8-Br-cAMP stimulation resulted in the induction and nuclear accumulation of FKHR in differentiating ES cells. Immunohistochemical studies revealed that endometrial stromal expression of FKHR in vivo is confined to decidualizing cells during the late secretory phase of the cycle and coincides with the expression of CCAAT/enhancer-binding protein beta (C/EBPbeta). Reporter gene studies showed that FKHR potently enhances PKA-dependent activation of the tissue-specific decidual prolactin (dPRL) promoter, a major differentiation marker in human ES cells. Transcriptional augmentation by FKHR was effected through functional cooperation with C/EBPbeta and binding to a composite FKHR-C/EBPbeta response unit in the proximal promoter region. Furthermore, FKHR and C/EBPbeta were shown to interact directly in a glutathione S-transferase pull-down assay. These results provide the first evidence of regulated expression of FKHR and demonstrate that FKHR has an integral role in PKA-dependent endometrial differentiation through its ability to bind and functionally cooperate with C/EBPbeta.
Christian
Mark
M
Institute of Reproductive and Developmental Biology, Wolfson & Weston Research Centre for Family Health, Imperial College Faculty of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom.
Zhang
Xiaohui
X
Schneider-Merck
Tanja
T
Unterman
Terry G
TG
Gellersen
Birgit
B
White
John O
JO
Brosens
Jan J
JJ
D001483:Base Sequence; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004717:Endometrium / Q000166:cytology / Q000378:metabolism*; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D006801:Humans; D007150:Immunohistochemistry; D011485:Protein Binding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*
D022782:CCAAT-Enhancer-Binding Protein-beta; D017931:DNA Primers; D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D011994:Recombinant Proteins; D014157:Transcription Factors; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases