DOT1L inhibition enhances pluripotency beyond acquisition of epithelial identity and without immediate suppression of the somatic transcriptome

Connecting the DOTs on Cell Identity

“…Methylation of H3K79, and not DOT1L protein itself, inhibits pluripotency acquisition as EPZ004777, a first generation DOT1L catalytic inhibitor ( Daigle et al, 2011 ), comparably enhanced reprogramming ( Onder et al, 2012 ). DOT1L inhibition did not alter cellular proliferation ( Onder et al, 2012 ; Wille and Sridharan, 2022 ) or expression of reprogramming transgenes ( Onder et al, 2012 ) demonstrating a role beyond augmentation of reprogramming-capable cells.…”

“…DOT1L-KO is lethal beginning at E11.5 in the mouse ( Jones et al, 2008 ; Feng et al, 2010 ; Liao and Szabó, 2020 ). In vitro , ESCs are globally depleted for H3K79me2 compared to somatic cells ( Sridharan et al, 2013 ) and reducing DOT1L activity enhances reprogramming to induced pluripotent stem cells ( Onder et al, 2012 ; Wille and Sridharan, 2022 ). Wild-type = w.t., and DOT1L knock-out = KO.…”

“…DOT1L disruption inhibits differentiation in vivo and in vitro ( Jones et al, 2008 ; Barry et al, 2009 ; Feng et al, 2010 ; Liao and Szabó, 2020 ). Conversely, inhibiting DOT1L greatly enhances reprogramming from unipotent somatic cells indicating H3K79me is a barrier for pluripotency acquisition ( Onder et al, 2012 ; Wille and Sridharan, 2022 ). Thus, DOT1L activity is a determinate of developmental potential.…”

“…ESCs can divide indefinitely while still being able to differentiate into all embryonic cell types. ESCs are isolated from the blastocyst where H3K79me2 is readily detected ( Ooga et al, 2008 ), albeit still lower compared to differentiated cell types like keratinocytes ( Wille and Sridharan, 2022 ) ( Figure 1 ). In fact, H3K79me2 is the most reduced histone lysine methylation in ESCs compared to mouse embryonic fibroblasts (MEFs) by unbiased mass spectrometry ( Sridharan et al, 2013 ).…”

“…However, unlike 2C cells, both ESCs and differentiated cells share the chromocenter structure of pericentric heterochromatin, hence the requirement for ESCs to maintain low H3K79me is likely to be different than in 2C cells. Even with the uniquely low H3K79me2 enrichment, Dot1l mRNA is expressed at a comparable level in MEFs and ESCs ( Wille and Sridharan, 2022 ). Like early embryogenesis, DOT1L is regulated at the level of protein localization.…”