RARγ is Essential for Retinoic Acid Induced Chromatin Remodeling and Transcriptional Activation in Embryonic Stem Cells

Abstract

SummaryWe have utilized retinoic acid receptor c (gamma) knockout (RARc 2/2 ) embryonic stem (ES) cells as a model system to analyze RARc mediated transcriptional regulation of stem cell differentiation. Most of the transcripts regulated by all-trans retinoic acid (RA) in ES cells are dependent upon functional RARc signaling. Notably, many of these RA-RARc target genes are implicated in retinoid uptake and metabolism. For instance, Lrat (lecithin:retinol acyltransferase), Stra6 (stimulated by retinoic acid 6), Crabp2 (cellular retinoic acid binding protein 2), and Cyp26a1 (cytochrome p450 26a1) transcripts are induced in wild type (WT), but not in RARc 2/2 cells. Transcripts for the transcription factors Pbx1 (pre-B cell leukemia homeobox-1), Wt1 (Wilm's tumor gene-1), and Meis1 (myeloid ecotropic viral integration site-1) increase upon RA treatment of WT, but not RARc 2/2 cells. In contrast, Stra8, Dleu7, Leftb, Pitx2, and Cdx1 mRNAs are induced by RA even in the absence of RARc. Mapping of the epigenetic signature of Meis1 revealed that RA induces a rapid increase in the H3K9/ K14ac epigenetic mark at the proximal promoter and at two sites downstream of the transcription start site in WT, but not in RARc 2/2 cells. Thus, RA-associated increases in H3K9/K14ac epigenetic marks require RARc and are associated with increased Meis1 transcript levels, whereas H3K4me3 is present at the Meis1 proximal promoter even in the absence of RARc. In contrast, at the Lrat proximal promoter primarily the H3K4me3 mark, and not the H3K9/K14ac mark, increases in response to RA, independently of the presence of RARc. Our data show major epigenetic changes associated with addition of the RARc agonist RA in ES cells.

An Alternative Retinoic Acid-responsive Stra6 Promoter Regulated in Response to Retinol Deficiency

“…Ϫ/Ϫ ES cells (38) to delineate the dynamics of the increase in Stra6 transcripts associated with RA treatment of murine ES cells in culture. We demonstrated that there is a 24-fold increase in Stra6 transcripts 48 h after RA addition in WT ES cells and that this increase does not occur in the RAR␥ Ϫ/Ϫ ES cells (Fig.…”

“…On a molecular level, RA mediates major changes in epigenetic marks on specific target genes (33)(34)(35)(36)(37). We recently showed that Stra6 transcripts are increased by RA treatment of embryonic stem (ES) cells and that this induction depends on RAR␥ (38).…”

Phosphorylation of the retinoic acid receptor RARγ2 is crucial for the neuronal differentiation of mouse embryonic stem cells

“…Because these genes are activated as early as 2 hours after RA addition to the cell aggregates, one can hypothesize that they are involved in the commitment of ESC to the neuronal lineage. A recent study conducted by Kashyap et al (Kashyap et al, 2013) has also shown that inactivation of RARc is associated with a reduced expression of several genes. However, the cells were not analysed under the same conditions as here and there was no correlation with neuronal differentiation.…”

Nascent RNA interaction keeps PRC2 activity poised and in check

“…(Right) Differential expression is also displayed with individual bars. Data were obtained from GSE43221 (Kashyap et al 2013).…”