DIFFERENTIAL EXPRESSION OF 4 MEMBERS OF THE POU FAMILY OF PROTEINS INACTIVATED AND PHORBOL 12-MYRISTATE 13-ACETATE-TREATED JURKAT T-CELLS

The POU family of proteins binds specifically to octamer DNA motifs pr esent in the promoters of several genes and regulates their expression . We identified the presence of four members of the POU family of prot eins, Oct-1, Oct-2, Oct-T1, and Oct-T2, in the human T-cell line Jurka t. To obtain insight into the physiological role played by these prote ins in T cells, we studied the time course of expression of these gene s in resting, activated, and phorbol 12-myristate 13-acetate (PMA)-tre ated cells. The expression of the gene encoding Oct-1 (now assigned th e name OTF1 for octamer-binding transcription factor 1) remained uncha nged and the levels of Oct-T2 mRNA decreased with increasing time of i ncubation to undetectable amounts in all three states of T-cell growth . The levels of Oct-2 mRNA and protein were increased in activated cel ls, were increased to a lesser extent in the PMA-treated cells, and we re undetectable in resting cells. The levels of the Oct-T1 transcripts increased dramatically in PMA-treated cells but not in resting or act ivated cells. Sequence analysis of the Oct-T1 cDNA showed an open read ing frame coding for a POU domain-containing protein of 42.7 kDa. Tran sient transfection of the gene encoding Oct-T1 decreased the activity of the interleukin 2 gene promoter in activated Jurkat cells. Further, there is evidence for an additional octamer-binding protein, Oct-T3, in Jurkat T cells.