Expression of Oct-4 during differentiation of murine F9 cells.

Oct-4 is a transcription factor that shares a common structural motif with members of the POU family. The mRNA for Oct-4 is found in growing oocytes and in totipotent or pluripotent cells of the early mouse embryo. Oct-4 is down-regulated in embryos during differentiation events associated with blastocyst implantation and gastrulation. Oct-4 gene expression is also down-regulated when murine embryonic stem cells or embryonal carcinoma cells are induced to differentiate in the presence of retinoic acid. A polyclonal antibody that can recognize a unique peptide sequence in the C-terminus of mouse Oct-4 has been prepared. It specifically recognizes Oct-4 protein as tested by Western blots and gel mobility shift assays. This antibody has been used to measure Oct-4 protein levels during retinoic acid induced differentiation of F9 embryonal carcinoma cells, It was observed that Oct-4 protein was abundant in undifferentiated F9 cells but decreased to levels below detection as the cells differentiated, consistent with changes in levels of expression in early embryos.