<i>Obox4</i> promotes zygotic genome activation upon loss of <i>Dux</i>.

Guo, Youjia; Kitano, Tomohiro; Inoue, Kimiko; Murano, Kensaku; Hirose, Michiko; Li, Ten D; Sakashita, Akihiko; Ishizu, Hirotsugu et al. · Elife · 2024

basic_science · Level V

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Abstract

Once fertilized, mouse zygotes rapidly proceed to zygotic genome activation (ZGA), during which long terminal repeats (LTRs) of murine endogenous retroviruses with leucine tRNA primer (MERVL) are activated by a conserved homeodomain-containing transcription factor, DUX. However, <i>Dux</i>-knockout embryos produce fertile mice, suggesting that ZGA is redundantly driven by an unknown factor(s). Here, we present multiple lines of evidence that the multicopy homeobox gene, <i>Obox4</i>, encodes a transcription factor that is highly expressed in mouse two-cell embryos and redundantly drives ZGA. Genome-wide profiling revealed that OBOX4 specifically binds and activates MERVL LTRs as well as a subset of murine endogenous retroviruses with lysine tRNA primer (MERVK) LTRs. Depletion of <i>Obox4</i> is tolerated by embryogenesis, whereas concomitant <i>Obox4</i>/<i>Dux</i> depletion markedly compromises embryonic development. Our study identified OBOX4 as a transcription factor that provides genetic redundancy to preimplantation development.

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