INHIBITION OF TRANSCRIPTIONAL REGULATOR YIN-YANG-1 BY ASSOCIATION WITH C-MYC

Yin-Yang-1 (YY1) regulates the transcription of many genes, including the oncogenes c-fos and c-myc. Depending on the context, YY1 acts as a transcriptional repressor, a transcriptional activator, or a transcri ptional initiator. The yeast two-hybrid system was used to screen a hu man complementary DNA (cDNA) library for proteins that associate with YY1, and a c-myc cDNA was isolated. Affinity chromatography confirmed that YY1 associates with c-Myc but not with Max. In cotransfections, c -Myc inhibits both the repressor and the activator functions of YY1, w hich suggests that one way c-Myc acts is by modulating the activity of YY1.