Chromatin remodeling of embryonic stem cells by e1a alters global histone h3 lysine 18 acetylation and loss of pluripotency

Abstract

Oncoviruses such as the E1A adenovirus are capable of simultaneously interfering with several classes of chromatin-modifying proteins and are useful in studying epigenetic regulation of gene expression. The genomic landscape of the embryonic stem cells is highly complex, which is characterized by numerous locus-specific chromatin modifications and controlled by more than hundred enzymes. To better understand the regulatory mechanisms involved in maintaining stem cell identity, we introduced E1A and mutant isoforms into mouse ESC (mESC). We found that E1A rapidly suppresses stem cell identity, leading to the loss of stem-cell specific gene expression, silencing of stem-cell specific enhancers, and loss of pluripotency. Analysis of mutant E1A isoforms in mESC reveal a specific requirement for its N-terminal domain involved in sequestration of lysine acetyl transferases, P300/CBP, but not for domains involved in pRB- or P400-family interaction. In response to E1A, acetylation of P300 targets, H3K18 and H3K27, was globally inhibited. Furthermore, H3K18 acetylation, which is enriched at the promoters of pluripotency-associated genes, was rapidly eliminated from the promoters of OCT4, NANOG, SOX2 and KLF4. These studies indicate that E1A deregulates transcriptional machinery necessary for ESC self-renewal and pluripotency and suggests that promoter-associated H3K18ac may be involved in maintaining stem cell identity.