Germ cell-specific deletion of Pex3 reveals essential roles of PEX3-dependent peroxisomes in spermiogenesis

Peroxisomes are organelles enclosed by a single membrane and are present in various species.The abruption of peroxisomes is correlated with peroxisome biogenesis disorders and single peroxisomal enzyme deficiencies that induce diverse diseases in different organs.However,little is known about the protein compositions and corresponding roles of heterogeneous peroxisomes in various organs.Through transcriptomic and proteomic analyses,we observed heterogenous peroxisomal components among different organs,as well as between testicular somatic cells and different developmental stages of germ cells.As Pex3 is expressed in both germ cells and Sertoli cells,we generated Pex3 germ cell-and Sertoli cell-specific knockout mice.While Pex3 deletion in Sertoli cells did not affect spermatogenesis,the deletion in germ cells resulted in male sterility,manifested as the destruction of intercellular bridges between spermatids and the formation of multinucleated giant cells.Proteomic analysis of the Pex3-deleted spermatids revealed defective expressions of peroxisomal proteins and spermiogenesis-related proteins.These findings provide new insights that PEX3-dependent peroxisomes are essential for germ cells undergoing spermiogenesis,but not for Sertoli cells.

DDX3X regulates cell survival and cell cycle during mouse early embryonic development

DDX3X is a highly conserved DEAD-box RNA helicase that participates in RNA transcription, RNA splicing, and mRNA transport, translation, and nucleo-cytoplasmic transport. It is highly expressed in metaphase II （MII） oocytes and is the predominant DDX3 variant in the ovary and embryo. However, whether it is important in mouse early embryo development remains unknown. In this study, we investigated the function of DDX3X in early embryogenesis by cytoplasmic microinjection with its siRNA in zygotes or single blastomeres of 2-cell embryos. Our results showed that knockdown of Ddx3x in zygote cytoplasm led to dramatically diminished blastocyst formarion, reduced cell numbers, and an increase in the number of apoptotic cells in blastocysts. Meanwhile, there was an accumulation of p53 in RNAi blastocysts. In addition, the ratio of cell cycle arrest during 2-cell to 4-cell transition increased following microinjection of Ddx3x siRNA into single blastomeres of 2-cell embryos compared with control. These results suggest that Ddx3x is an essential gene associated with cell survival and cell cycle control in mouse early embryos, and thus plays key roles in normal embryo development.

Flotillin-2 is an acrosome-related protein involved in mouse spermiogenesis

Spermatogenesis is a complex process of terminal differentiation by which mature sperms are generated,and it can be divided into three phases：mitosis,meiosis and spermiogenesis.In a previous study,we established a series of proteomic profiles for spermatogenesis to understand the regulation of male fertility and infertility.Here,we further investigated the localization and the role of flotillin-2 in spermiogenesis.Flotillin-2 expression was investigated in the testis of male CD1 mice at various developmental stages of spermatogenesis by using Western blotting,immunohistochemistry and immunofluorescence.Flotillin-2 was knocked down in vivo in three-week-old male mice using intratesticular injection of small inhibitory RNA（siRNA）,and sperm abnormalities were assessed three weeks later.Flotillin-2 was expressed at high levels in male germ cells during spermatogenesis.Flotillin-2 immunoreactivity was observed in pachytene spermatocytes as a strong dot-shaped signal and in round spermatids as a sickle-shaped distribution ahead of the acrosome.Immunofluorescence confirmed flotillin-2 was localized in front of the acrosome in round spermatids,indicating that flotillin-2 was localized to the Golgi apparatus.Knockdown of flotillin-2 in vivo led to a significant increase in head sperm abnormalities isolated from the cauda epididymis,compared with control siRNA-injected testes.This study indicates that flotillin-2 is a novel Golgi-related protein involved in sperm acrosome biogenesis.

A susceptibility locus rs7099208 is associated with non-obstructive azoospermia via reduction in the expression of FAM160B1

Non-obstructive azoospermia （NOA） is a severe defect in male reproductive health that occurs in 1% of adult men. In a previous study, we identified that rs7099208 is located within the last intron of FAM160B1 at 10q25.3. In this study, we analysed expression Quantitative Trait Loci （eQTL） of FAM16OB1, ABLIM1 and TRUB1, the three genes surrounding rs7099208. Only the expression level of FAM16OB1 was reduced for the homozygous alternate genotype （GG） of rs7099208, but not for the homozygous reference or heterozygous geno- types. FAM160B1 is predominantly expressed in human testes, where it is found in spermatocytes and round sper- matids. From 17 patients with NOA and five with obstructive azoospermia （OA）, immunohistochemistry revealed that expression of FAM160B1 is reduced, or undetectable in NOA patients, but not in OA cases or normal men. We conclude that rs7099208 is associated with NOA via a reduction in the expression of FAM160B1.

The expression and localization of a novel protein phosphatase inhibitor 2810408A11Rik in mouse testis and sperm

This study investigated the expression and distribution of 2810408A11Rik in mouse testis and sperm, and explored its role in sperrnatogenesis and sperm function. The expression levels of 2810408A11Rik mRNA in multiple tissue samples were analyzed using bioinformatic resources and RT-PCR technique. A specific rabbit polyclonal antibody was prepared by prokaryotic expression of 2810408A11Rik recombinant protein and utilized for animal immunization. Western blotting, immunohistochemistry and immunofluorescence were used to detect the expression and distribution of 2810408A11Rik. The results of the bioinformatic analysi and RT-PCR showed that 2810408A11Rik mRNA was specifically expressed in mouse testis, and 2810408AllRik protein included a protein phosphatase inhibitor domain. Western blotting assays, immunohistochemistry and immunofluorescence confirmed the expression of 2810408A11Rik protein in mouse testis, especially in post-meiosis round and long spermatids, and that it is localized in the acrosome and the post-nucleus area of sperm. Our findings suggest that 2810408A11Rik may play an important role in spermatogenesis, sperm capacitation and fertilization.

Generation of patient-specific pluripotent stem cells and directed differentiation of embryonic stem cells for regenerative medicine

Embryonic stem（ES） cells are pluripotent cells that can give rise to derivatives of all three embryonic germ layers. Due to its characteristics, the patient-specific ES cells are of great potential for transplantation therapies. Several strategies can reprogramme somatic cells back to pluripotent stem cells： nuclear transfer, fusion with ES cells, treatment with cell extract and induction by specific factors. Considering the future clinical use, the differentiation from ES to neurons, cardiomyocytes and many other types of cells currently provide basic cognition and experience to regenerative medicine. This article will review two courses, the reprogramming of differentiated cells and the differentiation of ES cells to specific cell types.

The testis-specifically expressed gene Trim69 is not essential for fertility in mice

Protein ubiquitination is essential for diverse cellular functions including spermatogenesis.The tripartite motif(TRIM)family proteins,most of which have E3 ubiquitin ligase activity,are highly conserved in mammals.They are involved in important cellular processes such as embryonic development,immunity,and fertility.Our previous studies indicated that Trim69,a testis-specific expressed TRIM family gene,potentially participates in the spermatogenesis by mediating testicular cells apoptosis.In this study,we investigated the biological functions of Trim69 in male mice by established Trim69 knockout mice with CRISPR/Cas9 genomic editing technology.Here,we reported that the male Trim69 knockout mice had normal fertility.The adult knockout mice have shown that the appearance of testes,testis/body weight ratios,testicular histomorphology,and the number and quality of sperm were consistent with wild-type mice.These results indicated that the E3 ubiquitin ligase protein Trim69 was not essential for male mouse fertility,and it might be compensated by other TRIM family members such as Trim58 in Trim69-deficiency testis.This study would help to elucidate the functions of tripartite motif protein family and the regulation of spermatogenesis.

CircAST:Full-length Assembly and Quantification of Alternatively Spliced Isoforms in Circular RNAs

Circular RNAs(circ RNAs),covalently closed continuous RNA loops,are generated from cognate linear RNAs through back splicing events,and alternative splicing events may generate different circ RNA isoforms at the same locus.However,the challenges of reconstruction and quantification of alternatively spliced full-length circ RNAs remain unresolved.On the basis of the internal structural characteristics of circ RNAs,we developed Circ AST,a tool to assemble alternatively spliced circ RNA transcripts and estimate their expression by using multiple splice graphs.Simulation studies showed that Circ AST correctly assembled the full sequences of circ RNAs with a sensitivity of 85.63%–94.32%and a precision of 81.96%–87.55%.By assigning reads to specific isoforms,Circ AST quantified the expression of circ RNA isoforms with correlation coefficients of 0.85–0.99 between theoretical and estimated values.We evaluated Circ AST on an in-house mouse testis RNA-seq dataset with RNase R treatment for enriching circ RNAs and identified 380 circ RNAs with full-length sequences different from those of their corresponding cognate linear RNAs.RT-PCR and Sanger sequencing analyses validated 32 out of 37 randomly selected isoforms,thus further indicating the good performance of Circ AST,especially for isoforms with low abundance.We also applied Circ AST to published experimental data and observed substantial diversity in circular transcripts across samples,thus suggesting that circ RNA expression is highly regulated.Circ AST can be accessed freely at https://github--com.3pco.8686c.com/xiaofengsong/CircAST.

RNA Guided Genome Editing in Mouse Germ-Line Stem Cells

Spermatogonial stem cells （SSCs） reside on the basement membrane of the seminiferous tubules in mammalian testes （Nagano et al., 1998）. After isolation and purification of SSCs from mouse testis, SSCs can be cultured in vitro to derive germ-line stem cells （GSCs） which have the ability of proliferation over 2 years （Kanatsu-Shinohara et al.. 2003;

RSBP15 interacts with and stabilizes dRSPH3 during sperm axoneme assembly in Drosophila

Flagellum in sperm is composed of over 200 different proteins and is essential for sperm motility. In particular, defects in the assembly of the radial spoke in the flagellum result in male infertility due to loss of sperm motility. However, mechanisms regulating radial spoke assembly remain unclear in metazoans.Here, we identified a novel Drosophila protein radial spoke binding protein 15(RSBP15) which plays an important role in regulating radial spoke assembly. Loss of RSBP15 results in complete lack of mature sperms in seminal vesicles(SVs), asynchronous individualization complex(IC) and defective "9 + 2"structure in flagella. RSBP15 is colocalized with dRSPH3 in sperm flagella, and interacts with dRSPH3 through its DD_R_PKA superfamily domain which is important for the stabilization of dRSPH3. Moreover,loss of dRSPH3, as well as dRSPH1, dRSPH4 a and dRSPH9, showed similar phenotypes to rsbp15 KO mutant. Together, our results suggest that RSBP15 acts in stabilizing the radial spoke protein complex to anchor and strengthen the radial spoke structures in sperm flagella.

Inhibition of vascular endothelial growth factor expression by Chinese medicine of Hedyotis diffusa Willd herbal compounds

The Hedyotis diffusa Willd herbal compounds(HDWHCs)are commonly used as Chinese medicine to treat cancer patients with established clinical therapeutic efficacy in China.However,the underlying mechanisms remain to be elucidated.In this study,we used freeze-dried powder of the water extracts of HDWHCs to investigate the potential mechanisms of HDWHCs in cancer treatment.HDWHCs treatment significantly inhibited vascular endothelial growth factor(VEGF)mRNA levels and VEGF transcriptional activation in cancer cells.HDWHCs also had a remarkable inhibitory effect on the expression of hypoxia-inducible factor 1alpha(HIF-1alpha).Forced expression of HIF-1αrestored VEGF transcriptional activation inhibited by HDWHCs,indicating that HDWHCs suppressed VEGF expression through decreasing HIF-1alpha expression.Moreover,HDWHCs inhibited cyclooxygenase-2(COX-2)expression,and overexpression of HIF-1alpha restored HDWHCs’inhibitory effect on COX-2 at transcriptional level.These findings may provide better understanding of HDWHCs’anti-cancer mechanism in cancer treatment.