| First Author | Schoorlemmer J | Year | 1994 |
| Journal | Mol Cell Biol | Volume | 14 |
| Issue | 2 | Pages | 1122-36 |
| PubMed ID | 8289793 | Mgi Jnum | J:18820 |
| Mgi Id | MGI:67043 | Doi | 10.1128/mcb.14.2.1122 |
| Citation | Schoorlemmer J, et al. (1994) Characterization of a negative retinoic acid response element in the murine Oct4 promoter. Mol Cell Biol 14(2):1122-36 |
| abstractText | Expression of Oct4 in embryonic stem cells is controlled by a distal upstream stem cell-specific enhancer that is deactivated during retinoic acid (RA)-induced differentiation by an indirect mechanism not involving binding of RA receptors (H. Okazawa, K. Okamoto, F. Ishino, T. Ishino-Kaneko, S. Takeda, Y. Toyoda, M. Muramatsu, and H. Hamada, EMBO J. 10:2997-3005, 1991). Here we report that in RA-treated P19 embryonal carcinoma cells the Oct4 promoter is also subject to negative regulation by RA. The minimal Oct4 promoter sequence mediating repression consists of a promoter-proximal sequence containing a GC-rich SP1 consensus-like sequence and several hormone response element half-sites that can be arranged into direct repeats with different spacing. The GC box binds a nuclear factor that is invariably present in undifferentiated and RA-treated differentiated P19 cells. By contrast, the hormone response element-containing sequence binds factors that are induced following RA treatment. Mutational analysis and competition experiments show that the functional entity binding the RA-induced factor is a direct repeat sequence with a spacing of one nucleotide, previously shown to be a binding site for COUP transcription factors (COUP-TFs). Cotransfected orphan receptors COUP-TF1, ARP-1, and EAR-2 were able to repress the activity of Oct4 promoter-driven reporters in P19 EC cells, albeit with different efficiencies. Furthermore, the negative transcriptional effect of COUP-TFs is dominant over the activating effect of the Oct4 embryonic stem cell-specific enhancer. These results show that negative regulation of Oct4 expression during RA-induced differentiation of embryonic stem cells is controlled by two different mechanisms, including deactivation of the embryonic stem cell-specific enhancer and promoter silencing by orphan nuclear hormone receptors. |
