Improve induced pluripotent stem cell generation by manipulating epigenetic statuses

Reprogramming of somatic cells to a pluripotent state can be achieved by introduction of defined transcription factors. The derived induced pluripotent stem (iPS) cells have molecular profiles and developmental potentials similar to embryonic stem (ES) cells. However, this reprogramming process is inefficient and its underlying mechanisms are poorly understood. To improve the efficiency of iPS cell generation and shed light on its mechanisms, I aimed to identify epigenetic modulations that can enhance iPS cell generation. By studying chemicals modulating epigenetic status and ES-cell enriched epigenetic factors, I demonstrate that butyrate, a histone deacetylase (HDAC) inhibitor, and Kdm2b, a histone demethylase specific for H3 lysine 36 dimethylation (H3K36me2) are capable of facilitating iPS cell generation. Butyrate not only enhances the efficiency of iPS cell generation, but also suppresses the formation of partially reprogrammed cells and transformed cells. The enhancing effect of butyrate on reprogramming appears to depend on c-Myc and occurs early in reprogramming. Genome-wide microarray analysis shows that a set of ES cell-enriched genes are upregulated upon butyrate treatment. Kdm2b promotes iPS cell generation via its demethylase and DNA binding activities. The Kdm2b-mediated effect on reprogramming is independent of its role in suppressing senescence. Kdm2b functions at the beginning of reprogramming and enhances activation of early responsive genes in reprogramming. Kdm2b regulates gene activation by directly binding to and demethylating its target loci. Collectively, the research in this dissertation show that iPS cell generation can be improved by manipulating epigenetic statuses, highlighting the importance of epigenetic modifications in the establishment of pluripotency.Doctor of Philosoph