Abstract
The embryonic transcription factor DUX regulates chromatin opening and gene expression in totipotent cleavage-stage mouse embryos, and its expression in embryonic stem cells promotes their conversion to 2-cell embryo-like cells (2CLCs) with extraembryonic potential. However, little is known regarding which domains within mouse DUX interact with particular chromatin and transcription regulators. Here, we reveal that the C-terminus of mouse DUX contains five uncharacterized ∼100 amino acid (aa) repeats followed by an acidic 14 amino acid tail. Unexpectedly, structure-function approaches classify two repeats as ‘active’ and three as ‘inactive’ in cleavage/2CLC transcription program enhancement, with differences narrowed to a key 6 amino acid section. Our proximity dependent biotin ligation (BioID) approach identified factors selectively associated with active DUX repeat derivatives (including the 14aa ‘tail’), including transcription and chromatin factors such as SWI/SNF (BAF) complex, as well as nucleolar factors that have been previously implicated in regulating the Dux locus. Finally, our mechanistic studies reveal cooperativity between DUX active repeats and the acidic tail in cofactor recruitment, DUX target opening, and transcription. Taken together, we provide several new insights into DUX structure-function, and mechanisms of chromatin and gene regulation.
Competing Interest Statement
Bradley Cairns is a founder and stockholder of Paterna Biosciences Inc. Paterna focuses on germline stem cell growth, which is fully outside the scope and field of work in this manuscript.
Footnotes
The section on similarity of the DUX repeats has been replaced by quantitative approaches, and the interpretation revised. Additional experiments were performed on an 'inactive' DUX repeat which reinforce the inactivity of these repeats, and show that it does not confer the opening of chromatin. Additional controls are added and/or discussed, such as the construct with the DUX homeodomains but lacking the C-terminal repeats. The summary table has been expanded to add dynamic range. Multiple clarifications and corrections to text and references are provided.