Generation of gene-modified cynomolgus monkey via Cas9/RNA-mediated gene targeting in one-cell embryos.

Monkeys serve as important model species for studying human diseases and developing therapeutic strategies, yet the application of monkeys in biomedical researches has been significantly hindered by the difficulties in producing animals genetically modified at the desired target sites. Here, we first applied the CRISPR/Cas9 system, a versatile tool for editing the genes of different organisms, to target monkey genomes. By coinjection of Cas9 mRNA and sgRNAs into one-cell-stage embryos, we successfully achieve precise gene targeting in cynomolgus monkeys. We also show that this system enables simultaneous disruption of two target genes (Ppar-γ and Rag1) in one step, and no off-target mutagenesis was detected by comprehensive analysis. Thus, coinjection of one-cell-stage embryos with Cas9 mRNA and sgRNAs is an efficient and reliable approach for gene-modified cynomolgus monkey generation.

A male germ-cell-specific ribosome controls male fertility.

Ribosomes are highly sophisticated translation machines that have been demonstrated to be heterogeneous in the regulation of protein synthesis1,2. Male germ cell development involves complex translational regulation during sperm formation3. However, it remains unclear whether translation during sperm formation is performed by a specific ribosome. Here we report a ribosome with a specialized nascent polypeptide exit tunnel, RibosomeST, that is assembled with the male germ-cell-specific protein RPL39L, the paralogue of core ribosome (RibosomeCore) protein RPL39. Deletion of RibosomeST in mice causes defective sperm formation, resulting in substantially reduced fertility. Our comparison of single-particle cryo-electron microscopy structures of ribosomes from mouse kidneys and testes indicates that RibosomeST features a ribosomal polypeptide exit tunnel of distinct size and charge states compared with RibosomeCore. RibosomeST predominantly cotranslationally regulates the folding of a subset of male germ-cell-specific proteins that are essential for the formation of sperm. Moreover, we found that specialized functions of RibosomeST were not replaceable by RibosomeCore. Taken together, identification of this sperm-specific ribosome should greatly expand our understanding of ribosome function and tissue-specific regulation of protein expression pattern in mammals.

Single-Cell Quantitative Proteomic Analysis of Human Oocyte Maturation Revealed High Heterogeneity in In Vitro-Matured Oocytes.

Oocyte maturation is pertinent to the success of in vitro maturation (IVM), which is used to overcome female infertility, and produced over 5000 live births worldwide. However, the quality of human IVM oocytes has not been investigated at single-cell proteome level. Here, we quantified 2094 proteins in human oocytes during in vitro and in vivo maturation (IVO) by single-cell proteomic analysis and identified 176 differential proteins between IVO and germinal vesicle oocytes and 45 between IVM and IVO oocytes including maternal effect proteins, with potential contribution to the clinically observed decreased fertilization, implantation, and birth rates using human IVM oocytes. IVM and IVO oocytes showed separate clusters in principal component analysis, with higher inter-cell variability among IVM oocytes, and have little correlation between mRNA and protein changes during maturation. The patients with the most aberrantly expressed proteins in IVM oocytes had the lowest level of estradiol per mature follicle on trigger day. Our data provide a rich resource to evaluate effect of IVM on oocyte quality and study mechanism of oocyte maturation.

A novel protein encoded by circRsrc1 regulates mitochondrial ribosome assembly and translation during spermatogenesis.

BACKGROUND: Circular RNAs (circRNAs) are a large class of mammalian RNAs. Several protein products translated by circRNAs have been reported to be involved in the development of various tissues and systems; however, their physiological functions in male reproduction have yet not been explored. RESULTS: Here, we report an endogenous circRNA (circRsrc1) that encodes a novel 161-amino-acid protein which we named Rsrc1-161aa through circRNA sequencing coupled with mass spectrometry analysis on mouse testicular tissues. Deletion of Rsrc1-161aa in mice impaired male fertility with a significant decrease in sperm count and motility due to dysfunctions of mitochondrial energy metabolism. A series of in vitro rescue experiments revealed that circRsrc1 regulates mitochondrial functions via its encoded protein Rsrc1-161aa. Mechanistically, Rsrc1-161aa directly interacts with mitochondrial protein C1qbp and enhances its binding activity to mitochondrial mRNAs, thereby regulating the assembly of mitochondrial ribosomes and affecting the translation of oxidative phosphorylation (OXPHOS) proteins and mitochondrial energy metabolism. CONCLUSIONS: Our studies reveal that Rsrc1-161aa protein encoded by circRsrc1 regulates mitochondrial ribosome assembly and translation during spermatogenesis, thereby affecting male fertility.

Functional screening of congenital heart disease risk loci identifies 5 genes essential for heart development in zebrafish.

Congenital heart disease (CHD) is the most common birth defect worldwide and a main cause of perinatal and infant mortality. Our previous genome-wide association study identified 53 SNPs that associated with CHD in the Han Chinese population. Here, we performed functional screening of 27 orthologous genes in zebrafish using injection of antisense morpholino oligos. From this screen, 5 genes were identified as essential for heart development, including iqgap2, ptprt, ptpn22, tbck and maml3. Presumptive roles of the novel CHD-related genes include heart chamber formation (iqgap2 and ptprt) and atrioventricular canal formation (ptpn22 and tbck). While deficiency of maml3 led to defective cardiac trabeculation and consequent heart failure in zebrafish embryos. Furthermore, we found that maml3 mutants showed decreased cardiomyocyte proliferation which caused a reduction in cardiac trabeculae due to inhibition of Notch signaling. Together, our study identifies 5 novel CHD-related genes that are essential for heart development in zebrafish and first demonstrates that maml3 is required for Notch signaling in vivo.

Multi-Omics Approaches for Revealing the Epigenetic Regulation of Histone H3.1 during Spermatogonial Stem Cell Differentiation In Vitro.

Epigenetic regulation, particularly post-translational modifications (PTMs) of histones, participates in spermatogonial stem cell (SSCs) differentiation. However, there is a lack of systemic studies of histone PTM regulation during the differentiation of SSCs due to its low number in vivo. Herein, we quantified dynamic changes of 46 different PTMs on histone H3.1 by targeted quantitative proteomics using mass spectrometry during SSCs differentiation in vitro, in combination with our RNA-seq data. We identified seven histone H3.1 modifications to be differentially regulated. In addition, we selected H3K9me2 and H3S10ph for subsequent biotinylated peptide pull-down experiments and identified 38 H3K9me2-binding proteins and 42 H3S10ph-binding proteins, which contain several transcription factors, such as GTF2E2 and SUPT5H, which appear to be crucial for epigenetic regulation of SSC differentiation.

Potential clinical value of in vitro spermatogenesis†.

Infertility has become the third most common disease threatening human health, immediately after tumors and cardiovascular diseases. Male infertility is primarily caused by spermatogenesis disorders that may be classified as either genetic or non-genetic. For part of non-genetic disorders, in vitro spermatogenesis can be induced by adjusting the microenvironment of the testis culture. Establishing the in vitro spermatogenic induction system helps to clarify the critical molecular mechanisms in spermatogonia self-renewal, spermatocyte meiosis, and sperm formation during spermatogenesis. In this review, we summarize recent advances in the field of in vitro sperm cells induction. Therefore, we hope to provide ideas and solutions for the clinical treatment of male infertility.

Dual functions for the ssDNA-binding protein RPA in meiotic recombination.

Meiotic recombination permits exchange of genetic material between homologous chromosomes. The replication protein A (RPA) complex, the predominant ssDNA-binding complex, is required for nearly all aspects of DNA metabolism, but its role in mammalian meiotic recombination remains unknown due to the embryonic lethality of RPA mutant mice. RPA is a heterotrimer of RPA1, RPA2, and RPA3. We find that loss of RPA1, the largest subunit, leads to disappearance of RPA2 and RPA3, resulting in the absence of the RPA complex. Using an inducible germline-specific inactivation strategy, we find that loss of RPA completely abrogates loading of RAD51/DMC1 recombinases to programmed meiotic DNA double strand breaks, thus blocking strand invasion required for chromosome pairing and synapsis. Surprisingly, loading of MEIOB, SPATA22, and ATR to DNA double strand breaks is RPA-independent and does not promote RAD51/DMC1 recruitment in the absence of RPA. Finally, inactivation of RPA reduces crossover formation. Our results demonstrate that RPA plays two distinct roles in meiotic recombination: an essential role in recombinase recruitment at early stages and an important role in promoting crossover formation at later stages.

Mebendazole-Induced Blood-Testis Barrier Injury in Mice Testes by Disrupting Microtubules in Addition to Triggering Programmed Cell Death.

Mebendazole (MBZ) is a synthetic benzimidazole known for its antiparasitic properties. In recent years, growing evidence showed that MBZ was also used as an anti-tumor agent. However, whether (and to what extent) this drug treatment affected the male reproductive system was not well-understood. In this study, male C57BL/6 mice were injected with 40 mg/kg/day of MBZ. The treatment was for 3 and 7 days. Our results showed that the injected mice exhibited an abnormal spermatogenic phase with a significant decrease in sperm. We further detected microtubule disruption and transient functional destruction of the blood-testes barrier (BTB) in the MBZ-injected mice testes (BTB). Our data confirmed that MBZ suppressed the expression of the BTB junction-associated proteins and disrupted the Sertoli cells' function in vivo. Moreover, MBZ-treated mice demonstrated an aberrant caspase-3 signalling pathway, which resulted in the apoptosis of the germ cells. Here, we present our data, indicating that MBZ impairs BTB by reducing the expression of the microtubules' and BTB junction-associated proteins. The last leads to activating the caspase-3 pathway, which triggers extensive germ cell apoptosis.

Systematic analysis of the ubiquitome in mouse testis.

A growing body of evidence now supports the fact that protein ubiquitination is an important modification during the regulation of spermatogenesis. However, little is known about the ubiquitome of the testis. In this study, we created a large-scale mouse testis ubiquitome profile using di-glycine remnant antibodies and mass spectrometry and identified a total of 14,219 ubiquitination sites in 4217 proteins. Bioinformatics and phenotypic analyses showed that the ubiquitinated proteins were closely related to meiosis and spermiogenesis. And 512 ubiquitination regulatory enzymes were identified in testis that can exert regulatory functions over ubiquitination: the homologous to E6AP C-terminus (HECT) and multi-subunit RING-finger type E3 ligases were significantly enriched. In addition, we identified 22 new ubiquitination sites on testicular histones and 146 ubiquitinated epigenetic factors, thus demonstrating that ubiquitination plays an important role in epigenetic regulation. Collectively, this in-depth characterization of the ubiquitome in mouse testis could provide a rich resource for further studies of regulatory events at the protein level during spermatogenesis. All MS data are available via ProteomeXchange with the identifier PXD025866.

Phosphoproteomic Analysis of Neonatal Regenerative Myocardium Revealed Important Roles of Checkpoint Kinase 1 via Activating Mammalian Target of Rapamycin C1/Ribosomal Protein S6 Kinase b-1 Pathway.

BACKGROUND: In mammals, regenerative therapy after myocardial infarction is hampered by the limited regenerative capacity of adult heart, whereas a transient regenerative capacity is maintained in the neonatal heart. Systemic phosphorylation signaling analysis on ischemic neonatal myocardium might be helpful to identify key pathways involved in heart regeneration. Our aim was to define the kinase-substrate network in ischemic neonatal myocardium and to identify key pathways involved in heart regeneration after ischemic insult. METHODS: Quantitative phosphoproteomics profiling was performed on infarct border zone of neonatal myocardium, and kinase-substrate network analysis revealed 11 kinases with enriched substrates and upregulated phosphorylation levels, including checkpoint kinase 1 (CHK1) kinase. The effect of CHK1 on cardiac regeneration was tested on Institute of Cancer Research CD1 neonatal and adult mice that underwent apical resection or myocardial infarction. RESULTS: In vitro, CHK1 overexpression promoted whereas CHK1 knockdown blunted cardiomyocyte proliferation. In vivo, inhibition of CHK1 hindered myocardial regeneration on resection border zone in neonatal mice. In adult myocardial infarction mice, CHK1 overexpression on infarct border zone upregulated mammalian target of rapamycin C1/ribosomal protein S6 kinase b-1 pathway, promoted cardiomyocyte proliferation, and improved cardiac function. Inhibiting mammalian target of rapamycin activity by rapamycin blunted the neonatal cardiomyocyte proliferation induced by CHK1 overexpression in vitro. CONCLUSIONS: Our study indicates that phosphoproteome of neonatal regenerative myocardium could help identify important signaling pathways involved in myocardial regeneration. CHK1 is found to be a key signaling responsible for neonatal regeneration. Myocardial overexpression of CHK1 could improve cardiac regeneration in adult hearts by activating the mammalian target of rapamycin C1/ribosomal protein S6 kinase b-1 pathway. Thus, CHK1 might serve as a potential novel target in myocardial repair after myocardial infarction.

Oocyte stage-specific effects of MTOR determine granulosa cell fate and oocyte quality in mice.

MTOR (mechanistic target of rapamycin) is a widely recognized integrator of signals and pathways key for cellular metabolism, proliferation, and differentiation. Here we show that conditional knockout (cKO) of Mtor in either primordial or growing oocytes caused infertility but differentially affected oocyte quality, granulosa cell fate, and follicular development. cKO of Mtor in nongrowing primordial oocytes caused defective follicular development leading to progressive degeneration of oocytes and loss of granulosa cell identity coincident with the acquisition of immature Sertoli cell-like characteristics. Although Mtor was deleted at the primordial oocyte stage, DNA damage accumulated in oocytes during their later growth, and there was a marked alteration of the transcriptome in the few oocytes that achieved the fully grown stage. Although oocyte quality and fertility were also compromised when Mtor was deleted after oocytes had begun to grow, these occurred without overtly affecting folliculogenesis or the oocyte transcriptome. Nevertheless, there was a significant change in a cohort of proteins in mature oocytes. In particular, down-regulation of PRC1 (protein regulator of cytokinesis 1) impaired completion of the first meiotic division. Therefore, MTOR-dependent pathways in primordial or growing oocytes differentially affected downstream processes including follicular development, sex-specific identity of early granulosa cells, maintenance of oocyte genome integrity, oocyte gene expression, meiosis, and preimplantation developmental competence.

MORC2B is essential for meiotic progression and fertility.

The microrchidia (MORC) family proteins are chromatin-remodelling factors and function in diverse biological processes such as DNA damage response and transposon silencing. Here, we report that mouse Morc2b encodes a functional germ cell-specific member of the MORC protein family. Morc2b arose specifically in the rodent lineage through retrotransposition of Morc2a during evolution. Inactivation of Morc2b leads to meiotic arrest and sterility in both sexes. Morc2b-deficient spermatocytes and oocytes exhibit failures in chromosomal synapsis, blockades in meiotic recombination, and increased apoptosis. Loss of MORC2B causes mis-regulated expression of meiosis-specific genes. Furthermore, we find that MORC2B interacts with MORC2A, its sequence paralogue. Our results demonstrate that Morc2b, a relatively recent gene, has evolved an essential role in meiosis and fertility.

TCTE1 is a conserved component of the dynein regulatory complex and is required for motility and metabolism in mouse spermatozoa.

Flagella and cilia are critical cellular organelles that provide a means for cells to sense and progress through their environment. The central component of flagella and cilia is the axoneme, which comprises the "9+2" microtubule arrangement, dynein arms, radial spokes, and the nexin-dynein regulatory complex (N-DRC). Failure to properly assemble components of the axoneme leads to defective flagella and in humans leads to a collection of diseases referred to as ciliopathies. Ciliopathies can manifest as severe syndromic diseases that affect lung and kidney function, central nervous system development, bone formation, visceral organ organization, and reproduction. T-Complex-Associated-Testis-Expressed 1 (TCTE1) is an evolutionarily conserved axonemal protein present from Chlamydomonas (DRC5) to mammals that localizes to the N-DRC. Here, we show that mouse TCTE1 is testis-enriched in its expression, with its mRNA appearing in early round spermatids and protein localized to the flagellum. TCTE1 is 498 aa in length with a leucine rich repeat domain at the C terminus and is present in eukaryotes containing a flagellum. Knockout of Tcte1 results in male sterility because Tcte1-null spermatozoa show aberrant motility. Although the axoneme is structurally normal in Tcte1 mutant spermatozoa, Tcte1-null sperm demonstrate a significant decrease of ATP, which is used by dynein motors to generate the bending force of the flagellum. These data provide a link to defining the molecular intricacies required for axoneme function, sperm motility, and male fertility.

The Protein Phosphorylation Landscape of Mouse Spermatids during Spermiogenesis.

The characteristic tadpole shape of sperm is formed from round spermatids via spermiogenesis, a process which results in dramatic morphological changes in the final stage of spermatogenesis in the testis. Protein phosphorylation, as one of the most important post-translational modifications, can regulate spermiogenesis; however, the phosphorylation events taking place during this process have not been systematically analyzed. In order to better understand the role of phosphorylation in spermiogenesis, large-scale phosphoproteome profiling is performed using IMAC and TiO2 enrichment. In total, 13 835 phosphorylation sites, in 4196 phosphoproteins, are identified in purified mouse spermatids undergoing spermiogenesis in two biological replicates. Overall, 735 testis-specific proteins are identified to be phosphorylated, and are expressed at high levels during spermiogenesis. Gene ontology analysis shows enrichment of the identified phosphoproteins in terms of histone modification, cilium organization, centrosome and the adherens junction. Further characterization of the kinase-substrate phosphorylation network demonstrates enrichment of phosphorylation substrates related to the regulation of spermiogenesis. This global protein phosphorylation landscape of spermiogenesis shows wide phosphoregulation across a diverse range of processes during spermiogenesis and can help to further characterize the process of sperm generation. All MS data are available via ProteomeXchange with the identifier PXD011890.

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.

Major spliceosome defects cause male infertility and are associated with nonobstructive azoospermia in humans.

Processing of pre-mRNA into mRNA is an important regulatory mechanism in eukaryotes that is mediated by the spliceosome, a huge and dynamic ribonucleoprotein complex. Splicing defects are implicated in a spectrum of human disease, but the underlying mechanistic links remain largely unresolved. Using a genome-wide association approach, we have recently identified single nucleotide polymorphisms in humans that associate with nonobstructive azoospermia (NOA), a common cause of male infertility. Here, using genetic manipulation of corresponding candidate loci in Drosophila, we show that the spliceosome component SNRPA1/U2A is essential for male fertility. Loss of U2A in germ cells of the Drosophila testis does not affect germline stem cells, but does result in the accumulation of mitotic spermatogonia that fail to differentiate into spermatocytes and mature sperm. Lack of U2A causes insufficient splicing of mRNAs required for the transition of germ cells from proliferation to differentiation. We show that germ cell-specific disruption of other components of the major spliceosome manifests with the same phenotype, demonstrating that mRNA processing is required for the differentiation of spermatogonia. This requirement is conserved, and expression of human SNRPA1 fully restores spermatogenesis in U2A mutant flies. We further report that several missense mutations in human SNRPA1 that inhibit the assembly of the major spliceosome dominantly disrupt spermatogonial differentiation in Drosophila. Collectively, our findings uncover a conserved and specific requirement for the major spliceosome during the transition from spermatogonial proliferation to differentiation in the male testis, suggesting that spliceosome defects affecting the differentiation of human spermatogonia contribute to NOA.

Identification of seven genes essential for male fertility through a genome-wide association study of non-obstructive azoospermia and RNA interference-mediated large-scale functional screening in Drosophila.

Non-obstructive azoospermia (NOA) is a complex and severe condition whose etiology remains largely unknown. In a genome-wide association study (GWAS) of NOA in Chinese men, few loci reached genome-wide significance, although this might be a result of genetic heterogeneity. Single nucleotide polymorphisms (SNPs) without genome-wide significance may also indicate genes that are essential for fertility, and multiple stage validation can lead to false-negative results. To perform large-scale functional screening of the genes surrounding these SNPs, we used in vivo RNA interference (RNAi) in Drosophila, which has a short maturation cycle and is suitable for high-throughput analysis. The analysis found that 7 (31.8%) of the 22 analyzed orthologous Drosophila genes were essential for male fertility. These genes corresponded to nine loci. Of these genes, leukocyte-antigen-related-like (Lar) is primarily required in germ cells to sustain spermatogenesis, whereas CG12404, doublesex-Mab-related 11E (dmrt11E), CG6769, estrogen-related receptor (ERR) and sulfateless (sfl) function in somatic cells. Interestingly, ERR and sfl are also required for testis morphogenesis. Our study thus demonstrates that SNPs without genome-wide significance in GWAS may also provide clues to disease-related genes and therefore warrant functional analysis.

CRISPR/Cas9-mediated Dax1 knockout in the monkey recapitulates human AHC-HH.

Mutations in the DAX1 locus cause X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH), which manifest with primary adrenal insufficiency and incomplete or absent sexual maturation, respectively. The associated defects in spermatogenesis can range from spermatogenic arrest to Sertoli cell only syndrome. Conclusions from Dax1 knockout mouse models provide only limited insight into AHC/HH disease mechanisms, because mouse models exhibit more extensive abnormalities in testicular development, including disorganized and incompletely formed testis cords with decreased number of peritubular myoid cells and male-to-female sex reversal. We previously reported successful clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated genome targeting in cynomolgus monkeys. Here, we describe a male fetal monkey in which targeted genome editing using CRISPR/Cas9 produced Dax1-null mutations in most somatic tissues and in the gonads. This DAX1-deficient monkey displayed defects in adrenal gland development and abnormal testis architecture with small cords, expanded blood vessels and extensive fibrosis. Sertoli cell formation was not affected. This phenotype strongly resembles findings in human patients with AHC-HH caused by mutations in DAX1. We further detected upregulation of Wnt/ß-catenin-VEGF signaling in the fetal Dax1-deficient testis, suggesting abnormal activation of signaling pathways in the absence of DAX1 as one mechanism of AHC-HH. Our study reveals novel insight into the role of DAX1 in HH and provides proof-of-principle for the generation of monkey models of human disease via CRISPR/Cas9-mediated gene targeting.