Identification of putative downstream genes of Oct-3, a pluripotent cell-specific transcription factor

Background: Oct-3, a pluripotent cell-specific POU transcription factor, appears to be a key regulator in pluripotential early embryonic cells and germ cells. In order to study how pluripotency is maintained, it is essential to know what genes are regulated by Oct-3. Results: By employing a subtraction method, we identified several pluripotent cell-specific genes. Based upon expression patterns in various cell lines lacking or possessing Oct-3 function, about half of the genes were placed downstream of Oct-3. These downstream genes included a previously-known gene (Glut-3: a gene for a glucose transporter) and novel genes (226, 383 and 880). Their expression patterns paralleled that of Oct-3: all of these genes were highly expressed in pluripotent cells such as EC/ES cells, but switched off upon differentiation. More importantly, their expression was rescued in 'revertant' cells that ectopically acquired the Oct-3 transactivating function. Furthermore, the expression profiles of Glut-3, 226 and 383 during mouse development also overlapped that of Oct-3. The Glut-3 gene possessed multiple Oct-3 binding sites in its transcriptional regulatory regions, suggesting that at least one of the downstream genes was a direct target of Oct-3. Conclusions: A large proportion of pluripotent cell-specific genes appear to be downstream targets of Oct-3.