Presenter: Calvin Summers
Mentor: Eric Selker
Poster: 31
Major: Biology
Cytosine methylation, a fundamental form of epigenetic regulation, is found in many eukaryotes and plays a significant role in cancer and other diseases. Using the genetically tractable model organism Neurospora crassa, the Selker laboratory has identified genes that when mutated, cause the strains to be defective in methylation (dim). The process of DNA methylation in Neurospora has been shown to be dependent on DCDC, a five member complex that directs the histone methyltransferase DIM-5 to trimethylate Lysine 9 on histone H3 (H3K9me3). This mark is recognized by HP1, which directs DIM-2 to methylate DNA. Another silencing complex, HCHC, employs HDA-1, CDP-2, HP1, and CHAP to deacetylate lysines on the histone. While we know a good deal about DNA methylation, it is still unclear whether we have identified all genes involved in the process. Thus this research focuses on our search for dim mutants, and asks whether our current model for DNA methylation is saturated. Using a selection for reactivation of resistance genes silenced by DNA methylation we aimed to answer this question. Interestingly, we predominantly identified known dim genes, including dim-5, dim-7, dim-8, dim-9, chap, cdp-2, and hda-1, suggesting our model may be saturated. We localized mutations in these known dim genes by DNA sequencing. The dim mutant collection generated should be a useful resource for further investigation into the roles of these genes and their protein products in DNA methylation. Understanding epigenetic pathways in Neurospora is an auspicious first step in elucidating mechanisms of complex genetic regulation in our own cells.