Functional Roles of Acetylated Histone Marks at Mouse Meiotic Recombination Hot Spots

Abstract

Meiotic recombination initiates following the formation of DNA doublestrand breaks (DSBs) by the Spo11 endonuclease early in prophase I, at discrete regions in the genome coined "hot spots." In mammals, meiotic DSB site selection is directed in part by sequence-specific binding of PRDM9, a polymorphic histone H3 (H3K4Me3) methyltransferase. However, other chromatin features needed for meiotic hot spot specification are largely unknown. Here we show that the recombinogenic cores of active hot spots in mice harbor several histone H3 and H4 acetylation and methylation marks that are typical of open, active chromatin. Further, deposition of these open chromatin-associated histone marks is dynamic and is manifest at spermatogonia and/or pre-leptotene-stage cells, which facilitates PRDM9 binding and access for Spo11 to direct the formation of DSBs, which are initiated at the leptotene stage. Importantly, manipulating histone acetylase and deacetylase activities established that histone acetylation marks are necessary for both hot spot activity and crossover resolution. We conclude that there are functional roles for histone acetylation marks at mammalian meiotic recombination hot spots.KEYWORDS crossover, double-strand break initiation, histone acetylation, meiotic recombination, mouse meiosis M eiotic recombination commences only following the double-stranded cleavage of DNA by the meiosis-specific Spo11 endonuclease in leptotene to early zygotene meiosis I cells (1-4), at discrete regions of the genome coined meiotic recombination "hot spots" (5, 6). Meiotic DNA double-strand breaks (DSBs) are then repaired by homologous recombination (HR) pathways, mediated by the meiosis-specific Rad51 and DMC1 repair proteins in mid-and late-zygotene-stage cells (4,7,8). The chromatin features, regulatory factors, and histone modifications that contribute to the control of mammalian meiotic DSB site selection by Spo11 and to the initiation, crossover (CO) activity, and resolution of meiotic recombination events are generally poorly understood.In mice and humans, one key regulator of DSB site selection is PRDM9 (5, 9-13), a polymorphic histone H3 methyltransferase that binds in a sequence-specific fashion to polymorphic sequences that are present in nearly 90% of hot spot cores (14) and that generates the trimethylated histone H3 lysine 4 (H3K4Me3) mark that is a hallmark of open chromatin (15,16). However, in addition to the known role for the H3K4Me3 mark at hot spot cores, an emerging body of evidence suggests that several histone modifications associated with open chromatin, including acetylation, methylation, and

A co-expression network in hexaploid wheat reveals mostly balanced expression and lack of significant gene loss of homeologous meiotic genes upon polyploidization

“…This gene has been previously reported to have a key role in homologous chromosome pairing, synapsis, DNA recombination and accurate chromosome segregation during meiosis in maize [ 84 ], Arabidopsis [ 85 ] and wheat [ 59 ]. Other hub genes identified in modules 28 and 41 encoded for the high mobility group proteins [ 86-90 ], histone deacetylase [ 91-94 ], and F-box proteins [ 95 ].…”

Age-Dependent Alterations in Meiotic Recombination Cause Chromosome Segregation Errors in Spermatocytes

“…Spermatocyte DNA was purified and used in both a NCO assay (e.g., B to universal (U) PCR), which non-selectively amplifies both COs and NCOs and a CO assay, which specifically amplifies CO recombinants (e.g., B to D PCR) (Figure 2B) (Cole and Jasin, 2011) at two meiotic hotspots: A3 on the longest mouse autosome (Chr1) and 59.5 on the shortest mouse autosome (Chr19) (Figure 2C) (Cole et al, 2014; Cole et al, 2010; Getun et al, 2016; Getun et al, 2012; Kelmenson et al, 2005). …”

Repeated losses of PRDM9-directed recombination despite the conservation of PRDM9 across vertebrates

“…During meiosis, PRDM9 binds sequences throughout the genome, as specified by its ZF array (reviewed in Ségurel et al, 2011), and the SET domain of PRDM9 makes H3K4me3 and H3K36me3 marks nearby (Eram et al, 2014; Powers et al, 2016). These actions ultimately serve to recruit SPO11 to initiate DSBs, by a mechanism that remains unknown but is associated with the presence of both histone marks (Grey et al, 2017; Getun et al, 2017) and may involve KRAB and SSXRD domains (Parvanov et al, 2017).

10.7554/eLife.24133.003Figure 1.Phylogenetic distribution and evolution of PRDM9 orthologs in vertebrates.Shown are the four domains: KRAB domain (in tan), SSXRD (in white), PR/SET (in light green) and ZF (in gray/dark green; the approximate structure of identified ZFs is also shown).

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