Presynaptic association of Rad51 protein with selected sites in meiotic chromatin.

Plug, Annemieke W.; Xu, Jihong; Reddy, Gurucharan; Golub, Efim I.; Ashley, Terry

doi:10.1073/pnas.93.12.5920

Cited by 103 publications

(69 citation statements)

References 36 publications

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“…Similar foci have also been observed in mitotic S-phase cells and are thought to identify sites where stalled or broken replication forks undergo repair (Tashiro et al, 1996;Golub et al, 1998;Raderschall et al, 1999). Consistent with a role in the repair of DSBs, RAD51 foci form during meiosis at the time when genetically programmed DSBs are generated (Plug et al, 1996;Barlow et al, 1997;Moens et al, 1997;Scully et al, 1997b).…”

Section: Introductionmentioning

confidence: 59%

BRCA2-dependent and independent formation of RAD51 nuclear foci

2003

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The formation of RAD51 foci in response to ionizing radiation (IR) represents an important step in the repair of DNA double-strand breaks. RAD51 foci also appear during S phase and are thought to be required for the restart of stalled or broken replication forks. The RAD51 recombinase interacts directly with the breast cancerassociated tumour suppressor BRCA2, an interaction that is required for normal recombination proficiency, radiation resistance and genome stability. In CAPAN-1 cells, which express a truncated form of BRCA2 that is cytoplasmic because of loss of the nuclear localization signal, the formation of IR-induced RAD51 foci is impaired. In this work, we show that S-phase RAD51 foci form normally in CAPAN-1 cells expressing truncated BRCA2. Moreover, we find that RAD51 specifically associates with chromatin at S phase in a reaction that is BRCA2-independent. The observed BRCA2-dependent and independent formation of RAD51 foci shows that intact BRCA2 is not required for RAD51 focus formation per se, leading us to suggest that S phase and IR-induced RAD51 foci assemble by distinct pathways with defined protein requirements.

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Section: Introductionmentioning

confidence: 59%

BRCA2-dependent and independent formation of RAD51 nuclear foci

2003

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“…Many proteins that control homology-directed DNA repair, such as RAD51, BRCA1, BRCA2, and PALB2, are also involved in the regulation of meiotic homologous recombination (39)(40)(41)(42). When MRG15 is downregulated in somatic cells, localization of RAD51, BRCA2, and PALB2 to DNA damage sites is suppressed (21).…”

Section: Discussionmentioning

confidence: 99%

MRG15 is required for pre-mRNA splicing and spermatogenesis

Iwamori

Tominaga

Sato

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Splicing can be epigenetically regulated and involved in cellular differentiation in somatic cells, but the interplay of epigenetic factors and the splicing machinery during spermatogenesis remains unclear. To study these interactions in vivo, we generated a germline deletion of MORF-related gene on chromosome 15 (MRG15), a multifunctional chromatin organizer that binds to methylated histone H3 lysine 36 (H3K36) in introns of transcriptionally active genes and has been implicated in regulation of histone acetylation, homology-directed DNA repair, and alternative splicing in somatic cells. Conditional KO (cKO) males lacking MRG15 in the germline are sterile secondary to spermatogenic arrest at the round spermatid stage. There were no significant alterations in meiotic division and histone acetylation. Specific mRNA sequences disappeared from 66 germ cell-expressed genes in the absence of MRG15, and specific intronic sequences were retained in mRNAs of 4 genes in the MRG15 cKO testes. In particular, introns were retained in mRNAs encoding the transition proteins that replace histones during sperm chromatin condensation. In round spermatids, MRG15 colocalizes with splicing factors PTBP1 and PTBP2 at H3K36me3 sites between the exons and single intron of transition nuclear protein 2 (Tnp2). Thus, our results reveal that MRG15 is essential for premRNA splicing during spermatogenesis and that epigenetic regulation of pre-mRNA splicing by histone modification could be useful to understand not only spermatogenesis but also, epigenetic disorders underlying male infertile patients.infertility | fertility defects | splicing defects | epigenetics | spermiogenesis S permatogenesis is a complex process involving several biological events and dramatic changes of chromatin structure. Male germ cells undergo stem cell self-renewal, mitotic divisions in spermatogonial proliferation, genomic rearrangement by meiotic homologous recombination at the spermatocyte stage, and morphological changes of round spermatids into elongated spermatids to form mature spermatozoa (1-3). During spermiogenesis, nucleosomal histone proteins are replaced with transition nuclear proteins (TNPs) and subsequently, protamines, the major nucleosomal proteins in spermatozoa. Moreover, epigenetic modifications, such as histone methylation, dramatically change throughout spermatogenesis (3, 4).Pre-mRNA splicing generates protein diversity and is involved in the regulation of cellular differentiation (5, 6). Recent advances have shown that histone modifications regulate alternative splicing through recruitment of splicing regulators via chromatin binding proteins, such as MORF-related gene on chromosome 15 (MRG15) (7). Histone H3 lysine 36 (H3K36) is methylated proximal to tissuespecific splicing regions (8-12). MRG15 specifically recognizes the methylated H3K36 and recruits polypyrimidine tract binding protein (PTB) at intronic splicing silencer elements near an exon to suppress exon insertions into mRNA (7). MRG15 is also a component of histone acetyltransfe...

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“…Rad51, the eukaryotic homolog of RecA, forms protein-DNA filaments similar to the RecA-DNA presynaptic complex (37), and promotes homologous pairing and strand exchange (38). At the onset of meiotic prophase, Rad51 foci on the chromatin coalesce into large linear arrays (39,40) that were proposed to comprise multiple Rad51-DNA filaments bound to many dsDNA sequences (40). Notably, the Rad51 foci are induced by DNA damages and colocalize with DNA repair sites that were coined repairosomes (41).…”

Section: Discussionmentioning

confidence: 99%

Ordered intracellular RecA–DNA assemblies: A potential site of in vivo RecA-mediated activities

Levin-Zaidman

Frenkiel-Krispin

Shimoni

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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The inducible SOS response increases the ability of bacteria to cope with DNA damage through various DNA repair processes in which the RecA protein plays a central role. Here we present the first study of the morphological aspects that accompany the SOS response in Escherichia coli. We find that induction of the SOS system in wild-type bacteria results in a fast and massive intracellular coaggregation of RecA and DNA into a lateral macroscopic assembly. The coaggregates comprise substantial portions of both the cellular RecA and the DNA complement. The structural features of the coaggregates and their relation to in vitro RecA-DNA networks, as well as morphological studies of strains carrying RecA mutants, are all consistent with the possibility that the intracellular assemblies represent a functional entity in which RecA-mediated DNA repair and protection activities occur.biocrystallization ͉ DNA repair ͉ homology search ͉ stress response R ecA-mediated DNA recombination and repair processes proceed through several sequential phases (1-3). A presynaptic filament in which RecA molecules coat a single-stranded DNA substrate is initially formed. The filament acts then as a sequence-specific DNA-binding entity, capable of searching and binding dsDNA sites that are homologous to the RecA-coated segment. Within the resulting joint species, DNA strand exchange and heteroduplex extension processes are promoted. The mechanism that enables a rapid search for DNA homology in vivo, within a highly crowded and complex genome, remains enigmatic.To reach its target, any sequence-specific DNA-binding protein must overcome two general obstacles: a minute cellular concentration of the target, and a vast excess of nontarget, yet still competitive, DNA sites. The search for a homologous DNA site conducted by the RecA-DNA presynaptic filament shares these hurdles, but is further encumbered by the uniquely adverse diffusion characteristics of its components. A DNA target corresponds to a segment that is part of, and embedded within, the chromosome. This, and the large structural asymmetry of DNA, conspire to minimize the diffusion constant of DNA sites (4, 5). In a homology search executed by the RecA-DNA filament, both the searching and the target entities are chromosomal DNA sites whose small diffusion constants drastically attenuate their encounter rate. How then does a RecA-mediated intracellular search evade the kinetic impediments that are intrinsic to the nature of its components?Here we show that damages inflicted on bacterial DNA lead to a rapid formation of an ordered intracellular assembly that accommodates both RecA and DNA. We suggest that the striated morphology of this RecA-DNA assembly is capable of promoting an in vivo homology search by attenuating both the sampling volume and the dimensionality of the process. Moreover, RecA was shown to protect chromosomal DNA from degradation (6) through unknown mechanisms. The tight crystalline packaging that is progressively assumed by the intracellular RecA-DNA assemblies as ...

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Presynaptic association of Rad51 protein with selected sites in meiotic chromatin.

Cited by 103 publications

References 36 publications

BRCA2-dependent and independent formation of RAD51 nuclear foci

BRCA2-dependent and independent formation of RAD51 nuclear foci

MRG15 is required for pre-mRNA splicing and spermatogenesis

Ordered intracellular RecA–DNA assemblies: A potential site of in vivo RecA-mediated activities

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