Year 1

Our laboratory is known for its discovery of the family of nuclear receptors (NHRs) that use hormones to control genes and thereby regulate embryonic development, cell growth, physiology and metabolism. The goal of this project is to explore how NHRs activate gene networks to produce human induced pluripotent stem cells (hiPSCs). We will determine the specific sites on the genome where NHRs and the reprogramming factor (Oct4) bind and determine how binding results in “epigenetic” modifications. Epigenetic modifications are the result of enzymatic action on chromatin which is a combination of DNA and histones. The first goal is a massive project to establish all the genome wide DNA methylation changes in adipose derived human induced pluripotent stem cells and embryonic stem cells. DNA methylation is considered a silencing signal in the genome and marks genes that are inactive in a particular cell. Using state-of-the-art technology we discovered the first differences in the methylation patterns between these two cell types. These important differences between ES and iPSC cell types may influence their differentiation capabilities. We are currently performing experiments to map the sites of histone modifications and will correlate these sites with the identified DNA methylation sites. We have also used high resolution RNA sequencing technology to determine the global collection of all genes that are expressed (termed the “transcriptome”) in human iPS cells. A comparison of this transcriptome with an ES cell (ES H1) demonstrated that these 2 cell types are very similar at the gene level. We are currently on track to complete the stated milestones and goals of the funded project.