Interaction of the Transcription Factor YY1 with Human Poly(ADP-Ribosyl) Transferase

Poly(ADP-ribosyl) transferase (ADPRT) is a nuclear enzyme that catalyzes the synthesis of ADP-ribose polymers from NAD+as well as the transfer of these polymers onto acceptor proteins. The function of ADPRT is thought to be related to a number of nuclear processes including DNA repair and transcription. The transcription factor Yin Yang 1 (YY1) is a potent regulator of RNA polymerase II (Pol II)-dependent transcription. In this study Alu-retroposon-associated binding sites for YY1 located in the distal region of the promoter of the human ADPRT gene have been identified suggesting a possible involvement of this protein in the regulation of ADPRT-gene expression. In the presence of the recombinant automodification domain of the ADPRT the formation of specific YY1 complexes, detected in gel-shift experiments, was strongly inhibited, indicating that this domain of the enzyme may interact directly with YY1. In accordance with this result YY1 was specifically precipitated from nuclear extracts by ADPRT immobilized on sepharose. These results suggest a direct ADPRT–YY1 interaction which may be of impotrance in the regulation of Pol II-dependent transcription. They also indicate that in some human promoters this regulation may be mediated by retroposons of the Alu family.