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 transposition of the human LINE-1 element involves the synthesis of full length LINE-1 mRNA. Previous work demonstrated that the 5'-terminal 100 base pairs of the human LINE-1 element (L1Hs) has an important role in regulating it's expression. Here we report further deletion analysis revealing the presence of a cis regulatory element overlapping the region between base pairs + 12 and + 18. Oligonucleotides containing this sequence form a specific complex with a nuclear protein extracted from NTera2D1 and Jurkat cells, and with recombinant YY1 produced in E. coli. The complex is competed by YY1 binding sites found in other genes, and is ablated by anti-YY1 serum. These results suggest that YY1 is involved in the regulation of Ll Hs transcription and therefore transposition.