Synaptonemal complex stability depends on repressive histone marks of the lateral element-associated repeat sequences

Abstract

The synaptonemal complex (SC) is the central key structure for meiosis in organisms undergoing sexual reproduction. During meiotic prophase I, homologous chromosomes exchange genetic information at the time they are attached to the lateral elements by specific DNA sequences. Most of these sequences, so far identified, consist of repeat DNA, which are subject to chromatin structural changes during meiotic prophase I. In this work, we addressed the effect of altering the chromatin structure of repeat DNA sequences mediating anchorage to the lateral elements of the SC. Administration of the histone deacetylase inhibitor trichostatin A into live rats caused death of cells in the pachytene stage as well as changes in histone marks along the synaptonemal complex. The most notable effect was partial loss of histone H3 lysine 27 trimethylation. Our work describes the epigenetic landscape of lateral element-associated chromatin and reveals a critical role of histone marks in synaptonemal complex integrity.

Superresolution imaging reveals structurally distinct periodic patterns of chromatin along pachytene chromosomes

“…Because histone modifications are known to regulate DNA participation in recombination and transcription, we tested if SMLM could be used to localize histone modifications in the context of chromatin. As was previously shown with confocal microscopy (13), the signals of repressive histone mark (H3K27me3) colocalized with SYCP3 at several points in our images as well (Fig. 3A).…”

“…Conventional light microscopy (LM) has shown the colocalization of H3K27me3 and H3K9me3 with synaptonemal complex protein 3 (SYCP3) (13), but due to the resolution limitations of LM (∼ 200 nm), the precise distribution of these marks along the pachytene chromosome has not been described yet. With the advent of various superresolution methods (14), particularly single-molecule localization microscopy (SMLM)-based methods (15)(16)(17) and recently developed strategies for labeling DNA (18,19), it is now possible to study DNA structures at the molecular scale.…”

Super-resolution imaging reveals structurally distinct periodic patterns of chromatin along pachytene chromosomes

“…Since histone modifications are known to regulate DNA participation in recombination and transcription, we tested if SMLM could be used to localize histone modifications in the context of chromatin. As was previously shown with confocal microscopy, 12 the signals of repressive histone mark (H3K27me3) co-localized with SYCP3 at several points in our images as well. However, instead of colocalisation with SYCP3 over the whole length, we find large, periodic clusters ( Fig.…”

“…Previously, it was reported that H3K27me3 is present exclusively at pachytene stage and co-localises with SC. 12 We find periodic clusters of this histone mark near the axis of the synaptonemal complex. The pattern of H3K27me3 is especially interesting as it is occasionally symmetrical on each side of the SC, which hints towards an association with defined regions of the genome.…”

Epigenetics of the Synaptonemal Complex

“…H3K27me3 colocalizes with SYCP3 along patches through the whole length of the SC. Strikingly; this pattern is only seen in pachytene stage when the SC is mature (Hernández-Hernández et al, 2010). Furthermore, this histone mark was enriched in SINE-and LTR-LEARS.…”