Chromatin accessibility and its relationship to pluripotency and the induction of pluripotent stem cells

Abstract

Chromatin within stem cells is dynamic and relaxed, allowing transcription and thus lineage specification to occur rapidly. To determine how this property can be used to enhance the generation of induced pluripotent stem cells (iPSC), I examined whether the expression of histone variants or peptidyl-prolyl isomerases (Ppiases) could increase the hyperdynamic, plastic nature of stem cell chromatin and thereby increase the efficiency and speed of reprogramming. I used molecular cloning to generate expression vectors containing the histone variants H3T and H2A.B. I used line-scanning microscopy to measure chromatin dynamics, with initial results suggesting that stem cells are more hyperdynamic in nature than differentiated cells. Although the research on the effect of histone variants and Ppiases on chromatin dynamics and reprogramming was not completed, another study showed that the expression of other histone variants does enhance reprogramming and may also induce an open chromatin structure. If this holds true for the histone variants studied here or Ppiase B (PpiB), this could further enhance the generation of iPSC and make future autologous engraftments of iPSC more feasible.