Abstract
SummaryBAF complexes are composed of different subunits with varying functional and developmental roles, although many subunits have not been examined in depth. Here we show that the Baf45 subunit Dpf2 maintains pluripotency and ESC differentiation potential. Dpf2 co-occupies enhancers with Oct4, Sox2, p300, and the BAF subunit Brg1, and deleting Dpf2 perturbs ESC self-renewal, induces repression of Tbx3, and impairs mesendodermal differentiation without dramatically altering Brg1 localization. Mesendodermal differentiation can be rescued by restoring Tbx3 expression, whose distal enhancer is positively regulated by Dpf2-dependent H3K27ac maintenance and recruitment of pluripotency TFs and Brg1. In contrast, the PRC2 subunit Eed binds an intragenic Tbx3 enhancer to oppose Dpf2-dependent Tbx3 expression and mesendodermal differentiation. The PRC2 subunit Ezh2 likewise opposes Dpf2-dependent differentiation through a distinct mechanism involving Nanog repression. Together, these findings delineate distinct mechanistic roles for specific BAF and PRC2 subunits during ESC differentiation.
Highlights
Embryonic stem cells (ESCs) are capable of self-renewal and differentiation into all cell types of the body, which is conferred by the coordination of key factors, including transcription factors (TFs), polycomb complexes, microRNAs, and histone modifiers (Tee and Reinberg, 2014; Li and Belmonte, 2017)
Dpf2 Loss Affects ESC Self-Renewal and Leads to Increased Apoptosis and Cell-Cycle Defects Given the previously described biochemical interaction of DPF2 with OCT4 in mouse ESCs (Pardo et al, 2010; van den Berg et al, 2010) and the prominent role of OCT4 as a member of the core pluripotency network (Li and Belmonte, 2017), we set out to study the role of Dpf2 in ESCs
We generated a conditional of Dpf2 allele in ESCs by adding LoxP sites around exon 4 (Figure S1A). 4-Hydroxytamoxifen (4-OHT) treatment of Dpf2 fl/fl ESCs resulted in an out-of-frame mutation yielding a complete Dpf2 knockout (KO) at the protein level (Figure S1B)
Summary
Embryonic stem cells (ESCs) are capable of self-renewal and differentiation into all cell types of the body, which is conferred by the coordination of key factors, including transcription factors (TFs), polycomb complexes, microRNAs, and histone modifiers (Tee and Reinberg, 2014; Li and Belmonte, 2017) Such factors include ATP-dependent chromatin remodeling complexes that hydrolyze ATP to change the conformation of chromatin, thereby modulating the access of TFs to chromosomal DNA (Kadoch and Crabtree, 2015). BAF45d, called Dpf, is the only ubiquitously expressed BAF45
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