Targeting and Interpreting DNA Methylation in Arabidopsis thaliana

DNA methylation is a highly conserved epigenetic modification associated with gene silencing in eukaryotic organisms. Although pathways controlling the establishment, maintenance and removal of DNA methylation have been identified, relatively little is understood about how the DNA methylation machinery is targeted to transposons and repeats or how DNA methylation influences gene expression. Using the plant model Arabidopsis thaliana, my laboratory has recently identified several protein complexes involved in these key aspects of DNA methylation. Highlights from this work include: (1) The identified a number of proteins that control DNA methylation via the RNA-directed DNA methylation pathway (RdDM) and (2) unanticipated roles for a family of Methyl-DNA binding Domain (MBD) proteins in the suppression of gene silencing in connection with members of a non-canonical family of small heat shock-related proteins. Using a combination of genetic, genomic and biochemical approaches were are beginning to uncover the mechanisms through which these proteins function, which will provide insight not only into normal biological processes but also into how alterations in chromatin modifications can lead to aberrant gene expression and developmental defects.