An imprinting element from the mouse H19 locus functions as a silencer in Drosophila

Abstract

Genomic imprinting as originally described in Sciara is displayed by many organisms. In mammals, X-inactivation and the parent-of-origin-specific silencing of imprinted genes are examples of this phenomenon. A heritable chromatin structural modification may be the critical mechanism in such instances of chromosome condensation and preferential gene inactivation. H19 is an imprinted gene in which the repressed paternal allele is hypermethylated and the compacted chromatin is relatively resistant to digestion by nucleases. In order to uncover underlying conserved epigenetic mechanisms we have introduced a mouse H19 transgene into Drosophila. We show here that a 1.2-kb H19 upstream sequence functions in cis as a parent-of-origin independent silencing element in Drosophila. Strikingly, this cis-acting element is located within an upstream region that is necessary for H19 imprinting in mice. These results suggest involvement of an evolutionary conserved mechanism in both genes silencing in Drosophila and imprinting in mice.