Castaneum As a Novel Model Organism for DNA Methylation Analysis
DNA methylation is a covalent modification that exerts an important influence on gene expression and can be faithfully inherited, in some cases over many generations. Proper methylation patterns are critical for eukaryotic development, and aberrant methylation-induced silencing of tumor suppressor genes is a common feature of human cancer. Unfortunately, the sequence preferences, mechanism of transcriptional control, and the contribution to development of DNA methylation are poorly understood in animals, in large part due to the lack of a good genetic model organism. High resolution mapping of DNA methylation using custom tiling microarrays(our preliminary work) indicates that the flour beetle Tribolium castaneum is an excellent candidate. The Tribolium genome is extensively methylated, including gene promoters, suggesting that DNA methylation regulates development. Heavy methylation of the X chromosone suggests that, like mammals, beetles use DNA methylation for dosage compensation. I propose to 1) map DNA methylation at high resolution in five other modestly -sized animal genomes to determine how the functions of methylation have evolved in the animal lineage, 2) map DNA methylation in different developmental stages of male and female T. castaneum, as well as in beetles with a knockdown of the major DNA methyltransferase gene (Dnmt1), to understand the role of methylation in beetle development and X chromosome dosage compensation, and 3) map histone H2A.Z in wild-type and Dnmt1 knockdown animals to determine whether H2A.Z and methylation regulate chromatin by mutual exclusion, as our recent study has shown to occur in plants. These experiments will identify evolutionarily conserved functions of DNA methylation, shed light on the role of DNA methylation in development, contribute to an understanding of the mechanism by which methylation regulates transcription, and establish Tribolium as a new model organism for DNA methylation analysis.
Arnold O. Beckman exemplifies the meaning of the word humanitarian. Combined with his unwavering enthusiasm for life, his keen sense of humor and his strong moral and ethical principles, he is a national icon.