MOF influences meiotic expansion of H2AX phosphorylation and spermatogenesis in mice.

Three waves of H2AX phosphorylation (γH2AX) have been observed in male meiotic prophase I: the first is ATM-dependent and occurs at leptonema, while the second and third are ATR-dependent, occuring at zygonema and pachynema, respectively. The third wave of H2AX phosphorylation marks and silences unsynapsed chromosomes. Little is known about H2AX phosphorylation expands to chromatin-wide regions in spermatocytes. Here, we report that histone acetyltransferase (HAT) MOF is involved in all three waves of H2AX phosphorylation expansion. Germ cell-specific deletion of Mof in spermatocytes by Stra8-Cre (Mof cKO) caused global loss of H4K16ac. In leptotene and zygotene spermatocytes of cKO mice, the γH2AX signals were observed only along the chromosomal axes, and chromatin-wide H2AX phosphorylation was lost. In almost 40% of early-mid pachytene spermatocytes from Mof cKO mice, γH2AX and MDC1 were detected along the unsynapsed axes of the sex chromosomes, but failed to expand, which consequently caused meiotic sex chromosome inactivation (MSCI) failure. Furthermore, though RAD51 was proficiently recruited to double-strand break (DSB) sites, defects in DSB repair and crossover formation were observed in Mof cKO spermatocytes, indicating that MOF facilitates meiotic DSB repair after RAD51 recruitment. We propose that MOF regulates male meiosis and is involved in the expansion of all three waves of H2AX phosphorylation from the leptotene to pachytene stages, initiated by ATM and ATR, respectively.

A homozygous FANCM frameshift pathogenic variant causes male infertility.

PURPOSE: Fanconi anemia (FA) genes play important roles in spermatogenesis. In mice, disruption of Fancm impairs male fertility and testicular integrity, but whether FANCM pathogenic variants (PV) similarly affect fertility in men is unknown. Here we characterize a Pakistani family having three infertile brothers, two manifesting oligoasthenospermia and one exhibiting azoospermia, born to first-cousin parents. A homozygous PV in FANCM (c.1946_1958del, p.P648Lfs*16) was found cosegregating with male infertility. Our objective is to validate that FANCM p.P648Lfs*16 is the PV causing infertility in this family. METHODS: Exome and Sanger sequencing were used for PV screening. DNA interstrand crosslink (ICL) sensitivity was assessed in lymphocytes from patients. A mouse model carrying a PV nearly equivalent to that in the patients (FancmΔC/ΔC) was generated, followed by functional analysis in spermatogenesis. RESULTS: The loss-of-function FANCM PV increased ICL sensitivity in lymphocytes of patients and FancmΔC/ΔC spermatogonia. Adult FancmΔC/ΔC mice showed spermatogenic failure, with germ cell loss in 50.2% of testicular tubules and round-spermatid maturation arrest in 43.5% of tubules. In addition, neither bone marrow failure nor cancer/tumor was detected in all the patients or adult FancmΔC/ΔC mice. CONCLUSION: These findings revealed male infertility to be a novel phenotype of human patients with a biallelic FANCM PV.

Correction: A homozygous FANCM frameshift pathogenic variant causes male infertility.

Hao Win, Hui Ma and Sajjad Hussain were incorrectly affiliated to 'Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030 USA'. These authors should only have been affiliated to 'Hefei National Laboratory for Physical Sciences at Microscale, The First Affiliated Hospital of USTC, USTC-SJH Joint Center for Human Reproduction and Genetics, The CAS Key Laboratory of Innate Immunity and Chronic Diseases, School of Life Sciences, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center of Genetics and Development, University of Science and Technology of China, Hefei 230027, China'. They were also not noted as contributing equally to the paper. Both these errors have now been corrected in the PDF and HTML versions of the paper.

IsomiR Bank: a research resource for tracking IsomiRs.

UNLABELLED: : Next-Generation Sequencing (NGS) technology has revealed that microRNAs (miRNAs) are capable of exhibiting frequent differences from their corresponding mature reference sequences, generating multiple variants: the isoforms of miRNAs (isomiRs). These isomiRs mainly originate via the imprecise and alternative cleavage during the pre-miRNA processing and post-transcriptional modifications that influence miRNA stability, their sub-cellular localization and target selection. Although several tools for the identification of isomiR have been reported, no bioinformatics resource dedicated to gather isomiRs from public NGS data and to provide functional analysis of these isomiRs is available to date. Thus, a free online database, IsomiR Bank has been created to integrate isomiRs detected by our previously published algorithm CPSS. In total, 2727 samples (Small RNA NGS data downloaded from ArrayExpress) from eight species (Arabidopsis thaliana, Drosophila melanogaster, Danio rerio, Homo sapiens, Mus musculus, Oryza sativa, Solanum lycopersicum and Zea mays) are analyzed. At present, 308 919 isomiRs from 4706 mature miRNAs are collected into IsomiR Bank. In addition, IsomiR Bank provides target prediction and enrichment analysis to evaluate the effects of isomiRs on target selection. AVAILABILITY AND IMPLEMENTATION: IsomiR Bank is implemented in PHP/PERL + MySQL + R format and can be freely accessed at http://mcg.ustc.edu.cn/bsc/isomir/ CONTACTS: : aoli@ustc.edu.cn or qshi@ustc.edu.cn SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

SpermatogenesisOnline 1.0: a resource for spermatogenesis based on manual literature curation and genome-wide data mining.

Human infertility affects 10-15% of couples, half of which is attributed to the male partner. Abnormal spermatogenesis is a major cause of male infertility. Characterizing the genes involved in spermatogenesis is fundamental to understand the mechanisms underlying this biological process and in developing treatments for male infertility. Although many genes have been implicated in spermatogenesis, no dedicated bioinformatic resource for spermatogenesis is available. We have developed such a database, SpermatogenesisOnline 1.0 (http://mcg.ustc.edu.cn/sdap1/spermgenes/), using manual curation from 30 233 articles published before 1 May 2012. It provides detailed information for 1666 genes reported to participate in spermatogenesis in 37 organisms. Based on the analysis of these genes, we developed an algorithm, Greed AUC Stepwise (GAS) model, which predicted 762 genes to participate in spermatogenesis (GAS probability >0.5) based on genome-wide transcriptional data in Mus musculus testis from the ArrayExpress database. These predicted and experimentally verified genes were annotated, with several identical spermatogenesis-related GO terms being enriched for both classes. Furthermore, protein-protein interaction analysis indicates direct interactions of predicted genes with the experimentally verified ones, which supports the reliability of GAS. The strategy (manual curation and data mining) used to develop SpermatogenesisOnline 1.0 can be easily extended to other biological processes.

microRNA 376a regulates follicle assembly by targeting Pcna in fetal and neonatal mouse ovaries.

In mammals, the primordial follicle pool, providing all oocytes available to a female throughout her reproductive life, is established perinatally. Dysregulation of primordial follicle assembly results in female reproductive diseases, such as premature ovarian insufficiency and infertility. Female mice lacking Dicer1 (Dicer), a gene required for biogenesis of microRNAs, show abnormal morphology of follicles and infertility. However, the contribution of individual microRNAs to primordial follicle assembly remains largely unknown. Here, we report that microRNA 376a (miR-376a) regulates primordial follicle assembly by modulating the expression of proliferating cell nuclear antigen (Pcna), a gene we previously reported to regulate primordial follicle assembly by regulating oocyte apoptosis in mouse ovaries. miR-376a was shown to be negatively correlated with Pcna mRNA expression in fetal and neonatal mouse ovaries and to directly bind to Pcna mRNA 3' untranslated region. Cultured 18.5 days postcoitum mouse ovaries transfected with miR-376a exhibited decreased Pcna expression both in protein and mRNA levels. Moreover, miR-376a overexpression significantly increased primordial follicles and reduced apoptosis of oocytes, which was very similar to those in ovaries co-transfected with miR-376a and siRNAs targeting Pcna. Taken together, our results demonstrate that miR-376a regulates primordial follicle assembly by modulating the expression of Pcna. To our knowledge, this is the first microRNA-target mRNA pair that has been reported to regulate mammalian primordial follicle assembly and further our understanding of the regulation of primordial follicle assembly.

A DNAH17 missense variant causes flagella destabilization and asthenozoospermia.

Asthenozoospermia is a common cause of male infertility, but its etiology remains incompletely understood. We recruited three Pakistani infertile brothers, born to first-cousin parents, displaying idiopathic asthenozoospermia but no ciliary-related symptoms. Whole-exome sequencing identified a missense variant (c.G5408A, p.C1803Y) in DNAH17, a functionally uncharacterized gene, recessively cosegregating with asthenozoospermia in the family. DNAH17, specifically expressed in testes, was localized to sperm flagella, and the mutation did not alter its localization. However, spermatozoa of all three patients showed higher frequencies of microtubule doublet(s) 4-7 missing at principal piece and end piece than in controls. Mice carrying a homozygous mutation (Dnah17M/M) equivalent to that in patients recapitulated the defects in patients' sperm tails. Further examinations revealed that the doublets 4-7 were destabilized largely due to the storage of sperm in epididymis. Altogether, we first report that a homozygous DNAH17 missense variant specifically induces doublets 4-7 destabilization and consequently causes asthenozoospermia, providing a novel marker for genetic counseling and diagnosis of male infertility.

RPL10L Is Required for Male Meiotic Division by Compensating for RPL10 during Meiotic Sex Chromosome Inactivation in Mice.

The mammalian sex chromosomes have undergone profound changes during their evolution from an ancestral pair of autosomes [1-4]. Specifically, the X chromosome has acquired a paradoxical sex-biased function by redistributing gene contents [5, 6] and has generated a disproportionately high number of retrogenes that are located on autosomes and exhibit male-biased expression patterns [6]. Several selection-based models have been proposed to explain this phenomenon, including a model of sexual antagonism driving X inactivation (SAXI) [6-8] and a compensatory mechanism based on meiotic sex chromosome inactivation (MSCI) [6, 8-11]. However, experimental evidence correlating the function of X-chromosome-derived autosomal retrogenes with evolutionary forces remains limited [12-17]. Here, we show that the deficiency of Rpl10l, a murine autosomal retrogene of Rpl10 with testis-specific expression, disturbs ribosome biogenesis in late-prophase spermatocytes and prohibits the transition from prophase into metaphase of the first meiotic division, resulting in male infertility. Rpl10l expression compensates for the lack of Rpl10, which exhibits a broad expression pattern but is subject to MSCI during spermatogenesis. Importantly, ectopic expression of RPL10L prevents the death of cultured RPL10-deficient somatic cells, and Rpl10l-promoter-driven transgenic expression of Rpl10 in spermatocytes restores spermatogenesis and fertility in Rpl10l-deficient mice. Our results demonstrate that Rpl10l plays an essential role during the meiotic stage of spermatogenesis by compensating for MSCI-mediated transcriptional silencing of Rpl10. These data provide direct evidence for the compensatory hypothesis and add novel insight into the evolution of X-chromosome-derived autosomal retrogenes and their role in male fertility.

Inhibitors of phosphatidylinositol 3'-kinases promote mitotic cell death in HeLa cells.

The phosphatidylinositol 3-kinase (PI3K) pathway plays an important role in many biological processes, including cell cycle progression, cell growth, survival, actin rearrangement and migration, and intracellular vesicular transport. However, the involvement of the PI3K pathway in the regulation of mitotic cell death remains unclear. In this study, we treated HeLa cells with the PI3K inhibitors, 3-methyladenine (3-MA, as well as a widely used autophagy inhibitor) and wortmannin to examine their effects on cell fates using live cell imaging. Treatment with 3-MA decreased cell viability in a time- and dose-dependent manner and was associated with caspase-3 activation. Interestingly, 3-MA-induced cell death was not affected by RNA interference-mediated knockdown (KD) of beclin1 (an essential protein for autophagy) in HeLa cells, or by deletion of atg5 (an essential autophagy gene) in mouse embryonic fibroblasts (MEFs). These data indicate that cell death induced by 3-MA occurs independently of its ability to inhibit autophagy. The results from live cell imaging studies showed that the inhibition of PI3Ks increased the occurrence of lagging chromosomes and cell cycle arrest and cell death in prometaphase. Furthermore, PI3K inhibitors promoted nocodazole-induced mitotic cell death and reduced mitotic slippage. Overexpression of Akt (the downstream target of PI3K) antagonized PI3K inhibitor-induced mitotic cell death and promoted nocodazole-induced mitotic slippage. These results suggest a novel role for the PI3K pathway in regulating mitotic progression and preventing mitotic cell death and provide justification for the use of PI3K inhibitors in combination with anti-mitotic drugs to combat cancer.

Tetraploid cells from cytokinesis failure induce aneuploidy and spontaneous transformation of mouse ovarian surface epithelial cells.

Most ovarian cancers originate from the ovarian surface epithelium and are characterized by aneuploid karyotypes. Aneuploidy, a consequence of chromosome instability, is an early event during the development of ovarian cancers. However, how aneuploid cells are evolved from normal diploid cells in ovarian cancers remains unknown. In the present study, cytogenetic analyses of a mouse syngeneic ovarian cancer model revealed that diploid mouse ovarian surface epithelial cells (MOSECs) experienced an intermediate tetraploid cell stage, before evolving to aneuploid (mainly near-tetraploid) cells. Using long-term live-cell imaging followed by fluorescence in situ hybridization (FISH), we demonstrated that tetraploid cells originally arose from cytokinesis failure of bipolar mitosis in diploid cells, and gave rise to aneuploid cells through chromosome mis-segregation during both bipolar and multipolar mitoses. Injection of the late passage aneuploid MOSECs resulted in tumor formation in C57BL/6 mice. Therefore, we reveal a pathway for the evolution of diploid to aneuploid MOSECs and elucidate a mechanism for the development of near-tetraploid ovarian cancer cells.

Regulation of asymmetrical cytokinesis by cAMP during meiosis I in mouse oocytes.

Mammalian oocytes undergo an asymmetrical first meiotic division, extruding half of their chromosomes in a small polar body to preserve maternal resources for embryonic development. To divide asymmetrically, mammalian oocytes relocate chromosomes from the center of the cell to the cortex, but little is known about the underlying mechanisms. Here, we show that upon the elevation of intracellular cAMP level, mouse oocytes produced two daughter cells with similar sizes. This symmetrical cell division could be rescued by the inhibition of PKA, a cAMP-dependent protein kinase. Live cell imaging revealed that a symmetrically localized cleavage furrow resulted in symmetrical cell division. Detailed analyses demonstrated that symmetrically localized cleavage furrows were caused by the inappropriate central positioning of chromosome clusters at anaphase onset, indicating that chromosome cluster migration was impaired. Notably, high intracellular cAMP reduced myosin II activity, and the microinjection of phospho-myosin II antibody into the oocytes impeded chromosome migration and promoted symmetrical cell division. Our results support the hypothesis that cAMP plays a role in regulating asymmetrical cell division by modulating myosin II activity during mouse oocyte meiosis I, providing a novel insight into the regulation of female gamete formation in mammals.