ACTIVATION OF THE TRANSCRIPTION FACTOR NF-KB IN GH(3) PITUITARY-CELLS

Since several genes expressed in the pituitary can bind the transcript ion factor NF-KB, its presence and regulation was examined in the GH(3 ) pituitary cell line. An electrophoretic mobility shift assay using n uclear extracts and an oligonucleotide probe corresponding to the Ig K B binding site was employed to identify activated NF-KB. One complex p ossessed properties characteristic of NF-KB: co-migration with an NF-K B complex and binding specificity restricted to NF-KB binding DNA sequ ences. Antibodies to the NF-KB subunits NFKB1p50 (p50) and RelA (p65) interacted with the extract-DNA complex. Activation of NF-KB in GH(3) cells was increased by PMA or the cytokine tumor necrosis factor alpha . A synergy between PMA and TNF or a calcium mobilizing agent was seen in NF-KB activation. Further TNF activation was enhanced by TRH. Thes e observations indicate the presence of NF-KB in GH(3) cells and demon strate its activation by hormones/second messengers that act on pituit ary cells.