Regulation of C/EBPβ/NF-M Activity by Kinase Oncogenes

CAAT Enhancer Binding proteins (C/EBP) belong to a family of transcription factors which are implicated in a number of developmental and growth regulatory processes. One member of this family known as C/EBPβ (called NF-M in the chicken system) is particularly important in myelomonocytic cells because it is targeted by kinases and collaborates with the Myb oncoprotein to induce the expression of myeloid specific genes. Experiments dissecting the structure of NF-M suggest that it is a repressed transcription factor. Using the yeast two-hybrid system we showed that a negative regulatory domain masks the transactivation domain. Examination of NF-M mutants suggests that kinase (proto-) oncogenes uncover the concealed transcriptional activity by phosphorylation of the negative regulatory domain.