Lsh, a member of the SNF2 family, is required for genome-wide methylation

Methylation patterns of the mammalian genome are thought to be crucial for development. The precise mechanisms designating specific genomic loci for m ethylation are not known. Targeted deletion of Lsh results in perinatal let hality with a rather normal development. We report here, however, that Lsh( -/-) mice show substantial loss of methylation throughout the genome. The h ypomethylated loci comprise repetitive elements and single copy genes. This suggests that global genomic methylation is not absolutely required for no rmal embryogenesis. Based on the similarity of Lsh to other SNF2 chromatin remodeling proteins, it suggests that alteration of chromatin affects globa l methylation patterns in mice.