March 26th, 2012
Tiffany's winning poster presentation is entitled, "Identifying Genes Controlling Epigenetic Stability in Induced Pluripotent Stem Cells (IPSCs)"
Abstract: The retroviral transduction of four embryonic stem cell transcription factors, Myc, Klf4, Oct3/4, and Sox2, collectively referred to as MKOS, are capable of reverting mouse fibroblast cells into an embryonic stem cell like fate. MKOS induced stem cells are referred to as Induced Pluripotent Stem Cells (IPSCs). However, IPSCs retain an epigenetic memory of their previous cell fate and exhibit incomplete reprogramming of specific methylation sites. I hypothesize that specific polymorphisms control the persistence of epigenetic marks in IPSCs. If this hypothesis is true then the reduced expression of regulatory genes will significantly decrease the presence of epigenetic marks in IPSCs. I am reprogramming fibroblasts from the recombinant inbred mouse strains of the Collaborative Cross by introducing a lentiviral vector containing the MKOS genes. Upon successful reprogramming I will profile the methylation patterns of an established embryonic stem cell line in addition to differentiated fibroblasts and reprogrammed IPSCs from each mouse strain. Methylation profiles will be compared to identify strains with the greatest retained fibroblast marks. These will be used in a genome-wide quantitative trait analysis to identify candidate genes regulating epigenome stability. Candidate genes will be tested using a ROSA26 targeting vector designed with an entry site that will be used to introduce candidate gene-specific RNAi's. The methylation patterns of IPSCs will be analyzed for changes in expression of epigenetic marks in response to candidate gene expression knockdown. At the end of this research we hope to have a list of identified, tested, and confirmed candidate genes affecting IPSC epigenetics.
Tiffany is working under the guidance of Dr. David Threadgill. She is the third Genetics PhD student in three years to win an award at the symposium. Last years recipient of this award was Shilpa Swarup, and the previous years winner was April Wynn.