Male Fertility Defect Associated with Disrupted BRCA1-PALB2 Interaction in Mice

Simhadri, Srilatha; Peterson, Shaun; Patel, Dharm S; Huo, Yanying; Cai, Hong; Bowman-Colin, Christian; Miller, Shoreh; Ludwig, Thomas; Ganesan, Shridar; Bhaumik, Mantu; Bunting, Samuel F.; Jasin, Maria; Xia, Bing

doi:10.1074/jbc.m114.566141

Cited by 70 publications

(79 citation statements)

References 51 publications

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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%

“…However, the formation of RAD51 foci was not affected by the deletion of MRG15. Although localization of PALB2 to DNA damage sites can be regulated by BRCA1 independently with MRG15 and depletion of PALB2 leads to loss of RAD51 focus formation in the DNA damage sites of somatic cells, inhibition of the interaction between PALB2 and BRCA1 does not affect formation of RAD51 foci in meiotic double-strand breaks, even if it results in male sterility, likely secondary to defect in sex chromosome synapsis (42). Because there were no significant defects in meiosis Mrg15 null testes, MRG15 is apparently not required for meiotic homologous recombination.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

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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“…Similarly, Palb2 knock-in mice that disrupt interaction with BRCA1 have been generated. In contrast to either Brca1 or Palb2 knock-out mice, these Palb2 mutants are viable, indicating that although the interaction between BRCA1 and PALB2 contributes to HR, either protein is largely functional in the absence of this interaction (45). This again signifies that interaction with BRCA1 is not equivalent to function and, together with data showing that disruption of BRCA1-BRIP1 also does not recapitulate knock-out phenotypes, suggests caution when interpreting the importance of BRCA1 protein-protein interactions.…”

Section: Connecting Brca Network Biochemistry To the Ddrmentioning

confidence: 98%

Deciphering the BRCA1 Tumor Suppressor Network

Jiang

Greenberg

2015

Journal of Biological Chemistry

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The BRCA1 tumor suppressor protein is a central constituent of several distinct macromolecular protein complexes that execute homology-directed DNA damage repair and cell cycle checkpoints. Recent years have borne witness to an exciting phase of discovery at the basic molecular level for how this network of DNA repair proteins acts to maintain genome stability and suppress cancer. The clinical dividends of this investment are now being realized with the approval of first-in-class BRCAtargeted therapies for ovarian cancer and identification of molecular events that determine responsiveness to these agents. Further delineation of the basic science underlying BRCA network function holds promise to maximally exploit genome instability for hereditary and sporadic cancer therapy.The breast cancer early-onset genes BRCA1 and BRCA2 were discovered by positional cloning approaches in kindreds with a high prevalence of breast and ovarian cancer. The initial lack of clarity presented by the domain structure of the proteins was remedied by a series of discoveries that revealed the proteins biochemically interact in large nuclear foci in response to DNA damage and are required to execute homology-directed DNA repair and cell cycle checkpoints (1). These observations strongly suggested that a common function in genome integrity maintenance is necessary to suppress cancer. Subsequent advances in protein purification and mass spectrometry methodologies have led to the expansion of this concept with the discovery that at least 13 different tumor suppressor proteins interact with BRCA1 and BRCA2. Despite these striking similarities, a linear model of BRCA-dependent DNA repair and tumor suppression is challenged by multiple other observations, namely, only ϳ5% of each protein exists in association with the BRCA1-BRCA2 complex, and breast cancers occurring in individuals with germ-line BRCA1 or BRCA2 mutations typically display different histopathologies and gene expression profiles. Coupled with the realization that chemoresistance mechanisms in BRCA1 and BRCA2 mutant cancers also differ, these features have inspired a network model relating BRCA molecular function in DNA repair to tumor suppression. We highlight recent insights into the BRCA tumor suppressor network and stress the connections between basic molecular knowledge of these proteins and their roles in genome integrity, tumor suppression, and response to therapy.

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“…We generated siRNA-resistant versions of wild type PALB2, its phospho-dead mutant S157A/S376A (S/A) and phospho-mimicking mutants S157D/S376D (S/D) and S157E/S376E (S/E), and reconstituted these expression constructs into PALB2-depleted cells to evaluate how manipulating the phosphorylation status of PALB2 affects HR repair. We included the PALB2 L21A mutant, which we and others have shown to be HR deficient (19,21), as a negative control (Fig. 4B).…”

Section: The Ddr Kinase Atm Is Required For Ir-induced Palb2mentioning

confidence: 99%

“…PALB2 also supports spermatogenesis, as PALB2 mutant animals suffered from reduced fertility, presumably due to defects in meiosis (19).…”

mentioning

confidence: 99%