BINDING OF THE UBIQUITOUS NUCLEAR TRANSCRIPTION FACTOR YY1 TO A CIS REGULATORY SEQUENCE IN THE HUMAN LINE-1 TRANSPOSABLE ELEMENT

The first step of the currently favored model for the mechanism of tra nsposition of the human LINE-1 element involves the synthesis of full length LINE-1 mRNA. Previous work demonstrated that the 5'-terminal 10 0 base pairs of the human LINE-1 element (L1Hs) has an important role in regulating it's expression. Here we report further deletion analysi s revealing the presence of a cis regulatory element overlapping the r egion between base pairs + 12 and + 18. Oligonucleotides containing th is sequence form a specific complex with a nuclear protein extracted f rom NTera2D1 and Jurkat cells, and with recombinant YY1 produced in E. coli. The complex is competed by YY1 binding sites found in other gen es, and is ablated by anti-YY1 serum. These results suggest that YY1 i s involved in the regulation of Ll Hs transcription and therefore tran sposition.