Paternal H3K4 methylation is required for minor zygotic gene activation and early mouse embryonic development

Abstract

Epigenetic modifications, such as DNA methylation and histone modifications, are dynamically altered predominantly in paternal pronuclei soon after fertilization. To identify which histone modifications are required for early embryonic development, we utilized histone K-M mutants, which prevent endogenous histone methylation at the mutated site. We prepared four single K-M mutants for histone H3.3, K4M, K9M, K27M, and K36M, and demonstrate that overexpression of H3.3 K4M in embryos before fertilization results in developmental arrest, whereas overexpression after fertilization does not affect the development. Furthermore, loss of H3K4 methylation decreases the level of minor zygotic gene activation (ZGA) predominantly in the paternal pronucleus, and we obtained similar results from knockdown of the H3K4 methyltransferase Mll3/4. We therefore conclude that H3K4 methylation, likely established by Mll3/4 at the early pronuclear stage, is essential for the onset of minor ZGA in the paternal pronucleus, which is necessary for subsequent preimplantation development in mice.

Setd1b, encoding a histone 3 lysine 4 methyltransferase, is a maternal effect gene required for the oogenic gene expression program

“…The acquisition of H3K4me2/ me3 in the male pronucleus, pronuclear fusion and cell division precede zygotic genome activation (Aoshima et al, 2015), although in the mouse minor zygotic transcription activity has been detected at the pronuclear stage (Abe et al, 2015).…”

Histone Variant H3.3: A versatile H3 variant in health and in disease

“…Mutation of H3.3 K27, but not of H3.1 K27, results in de-repression of pericentromeric transcripts, HP1 mislocalization, dysfunctional chromosome segregation and developmental arrest (Santenard et al, 2010). In paternal pronucleus (PN), overexpression of a H3.3 K4M mutant before fertilization causes a significant reduction in global H3K4me3, decreasing the level of minor zygotic gene activation (ZGA) in PN, and as a consequence, reducing the survival rate of the embryo (Aoshima et al, 2015). Together, these studies suggest that H3.3 affects embryo development after fertilization through specific post-translation modification of its N-terminal tail.…”

Genetic mosaics and time-lapse imaging identify functions of histone H3.3 residues in mouse oocytes and embryos

“…For example, H3.3K27R expressed in 1C zygotes results in defective heterochromatin formation and compromises pre-implantation development (Santenard et al, 2010). Studies in glioblastomas identified dominant negative effects of K-to-M mutations in H3.3 (Lewis et al, 2013;Schwartzentruber et al, 2012) and application in early embryos showed that K4 is essential for embryonic genome activation (Aoshima et al, 2015). Additionally, when H3.3 mutants were used to rescue H3.3 knockdown-induced developmental arrest in early embryos, H3.3K36 was shown to inhibit chromatin over-condensation .…”