SPR-5 is a histone H3K4 demethylase with a role in meiotic double-strand break repair

Abstract

Regulation of histone methylation levels has long been implicated in multiple cellular processes, many of which involve transcription. Here, however, we report a unique role for the Caenorhabditis elegans histone demethylase SPR-5 in meiotic DNA double-strand break repair (DSBR). SPR-5 shows enzymatic activity toward H3K4me2 both in vitro and in the nematode germline, and spr-5 mutants show several phenotypes indicating a perturbation of DSBR, including increased p53-dependent germ cell apoptosis, increased levels of the DSBR marker RAD-51, and sensitivity toward DSB-inducing treatments. spr-5 mutants show no transcriptional misregulation of known DSBR involved genes. Instead, SPR-5 shows a rapid subcellular relocalization upon DSB-inducing treatment, which suggests that SPR-5 may function directly in DSBR.lysine specific histone demethylase | meiosis D ynamic regulation of histone methylation status has been linked to multiple biological processes, including transcriptional activation and repression, sex chromosome silencing, and DNA damage response (reviewed in refs. 1 and 2). The recent discovery of histone demethylase enzymes has offered opportunities to further understand the function of these modifications. Histone H3 methylation occurs at multiple lysine (K) residues (H3K4, K9, K27, K36, and K79), and each of these lysine moieties can be methylated to mono-, di-, and trimethylated states. Both the location and the degree of methylation are believed to play a role in the determination of the distinct function a specific methylation event plays in the regulation of chromatin structure and function. Histone H3 methylation at lysine 4 (H3K4me) is a particularly intriguing modification: it has not only been strongly linked to transcriptional activation and enhancer function but more recently has been shown to be enriched at meiotic recombination hotspots (3-7), indicating a potential role for epigenetic control of hotspot localization in regulating meiotic double-strand break (DSB) initiation.The mammalian histone demethylase LSD1 was originally identified as an H3K4me2/1-specific demethylase (8), and studies of LSD1 in various species have presented several common phenotypes suggestive of a role for LSD1 in meiosis. For example, fission yeast lacking LSD1 have a sporulation defect, and flies show a female sterility phenotype (9-11). More recently, a mutation in spr-5, a Caenorhabditis elegans ortholog of LSD1, was found to show a phenotype of progressive sterility (12). The authors used whole-animal samples to identify spr-5 target genes and showed a progressive increase of H3K4me2 for a subset of genes, including spermatogenesis genes (12). The sterility phenotypes detected in several organisms are suggestive of a role for LSD1 orthologs in meiosis; however, LSD1 function in the germline remains largely unknown.Here we examined the germline function of spr-5, using tissuespecific techniques in C. elegans. These experiments uncovered an unexpected set of phenotypes indicating perturbed DSB repair (DSBR), link...

The histone demethylase LSD1/KDM1A promotes the DNA damage response

“…However, besides the recently described noncatalytic role of JMJD2A (Mallette et al, 2012), there is little evidence in the literature that any histone demethylase plays a direct role in the DDR. Previous work had suggested that the Caenorhabditis elegans LSD1 homologue SPR-5 plays a role in meiotic DSB repair, but the precise molecular mechanism or its functional evolutionary conservation were not clear (Nottke et al, 2011). In this study, we provide numerous lines of evidence supporting the notion that human LSD1 plays a direct role in the DDR.…”

Mutation of C. elegans demethylase spr-5 extends transgenerational longevity

“…However, after 10 and 20 generations bearing this mutation, spr-5(by101) and spr-5(by134) mutant worms (G10 and G20) displayed extended lifespan by 19%-44% (Figure 1B and 1C, Supplementary information, Tables S1-S5). Both spr-5 alleles are predicted functional null alleles, the by101 allele has a transposon insertion next to the catalytic residue and the by134 allele has a nonsense mutation which eliminates the majority of the enzymatic domain [4,5]. This trans-generational lifespan extension, similar to the progressive fertility defect and H3K4me2 accumulation, was reverted when worms were backcrossed to provide a single WT copy of spr-5.…”

“…For the most part, the molecular mechanisms behind these transgenerational epigenetic effects are still unknown [1][2][3]. In worms, deletion of SPR-5, the ortholog of the human H3K4me1/2-specific demethylase LSD1 [4], initially do not exhibit phenotypes, however, successive generations lacking this demethylase display increasing infertility concomitant with a global accumulation of DNA methylation of adenines (6mA) and euchromatic histone H3 lysine 4 dimethyl (H3K4me2) and a global decline in heterochromatic H3K9me3 [4][5][6][7]. These progressive phenotypes can be reversed by the addition of a single copy of spr-5 [4].…”

MRG-1 is required for genomic integrity in Caenorhabditis elegans germ cells

“…Recently, it was found that loss of spr-5, which encodes a histone H3K4me2 demethylase, led to elevated levels in germline H3K4me2, p53-dependent apoptosis, and meiotic RAD-51 foci, suggesting that histone modifications play a role in meiotic DSB repair in C. elegans [46]. Intriguingly, we found that dimethylation of the lysine 9 of histone H3 was similarly increased from the early to late pachytene regions in mutants deficient in mrg-1, syp-2, and him-3, compared with wild-type germ lines.…”