Poster abstracts
Poster number 53 submitted by Meredith Sigman
Tipping the epigenetic scales between genes and transposable elements
Meredith J. Sigman (Molecular Genetics, OSU), Diego Cuerda Gil (Molecular Genetics, OSU), R. Keith Slotkin (Molecular Genetics, OSU)
Abstract:
Transposable elements (TEs) are mobile fragments of DNA that cause double-stranded DNA breaks upon transposition and are thus inherently mutagenic. To prevent DNA damage, multicellular organisms such as the model plant Arabidopsis thaliana transcriptionally silence TEs via heterochromatin formation enacted through epigenetic modifications such as DNA and histone methylation. Cytosine methylation is added to a locus through a small RNA-guided pathway termed RNA-directed DNA Methylation (RdDM). My research examines which RdDM associated factors are sufficient to tip a locus into a methylated “TE-like” state. I have successfully recruited RdDM to a genic locus through the addition of homologous sRNAs. Additionally previous work shows that RdDM factors are associated with double-strand break (DSB) repair. The dual role of canonical RdDM proteins in DSB repair begs the question of whether this pathway can also serve as a preliminary surveillance mechanism capable of targeting TE and exogenous DNA at the genome integration step. I assayed whether a DSB could trigger RdDM at a broken locus through the use of CRISPR-Cas9. Finally, the methylation of DNA and histones can be removed by demethylases to protect a locus from RdDM. We hypothesize that the histone demethylase IBM1 is a key factor in determining whether a locus creating sRNAs will transition into RdDM.
References:
Wei et al. (2012) A role for sRNAs in double strand break repair. Cell , Volume 149 , Issue 1 , 101 - 112
Keywords: Epigenetic, Transposable Element, RNA-directed DNA Methylation