PRSS50-mediated inhibition of MKP3/ERK signaling is crucial for meiotic progression and sperm quality

Serine protease 50(PRSS50/TSP50)is highly expressed in spermatocytes.Our study investigated its role in testicular development and spermatogenesis.Initially,PRSS50 knockdown was observed to impair DNA synthesis in spermatocytes.To further explore this,we generated PRSS50 knockout(Prss50^(−/−))mice(Mus musculus),which exhibited abnormal spermatid nuclear compression and reduced male fertility.Furthermore,dysplastic seminiferous tubules and decreased sex hormones were observed in 4-week-old Prss50^(−/−)mice,accompanied by meiotic progression defects and increased apoptosis of spermatogenic cells.Mechanistic analysis indicated that PRSS50 deletion resulted in increased phosphorylation of extracellular signal-regulated protein kinases 1 and 2(ERK1/2)and elevated levels of MAP kinase phosphatase 3(MKP3),a specific ERK antagonist,potentially accounting for testicular dysplasia in adolescent Prss50−/−mice.Taken together,these findings suggest that PRSS50 plays an important role in testicular development and spermatogenesis,with the MKP3/ERK signaling pathway playing a significant role in this process.

Support vector machine for prediction of meiotic recombination hotspots and coldspots in Saccharomyces cerevisiae

A novel method for predicting hotspots and coldspots using support vector machine （SVM） based on statistical learning theory is developed. This method is applied to published 303 hot and 48 cold open reading frames （ORFs） in Saccharomyces cerevisiae. The sequence features of general dinucleotide abundance and dinucleotide abundance based on codon usage are extracted, and then the data sets are classified with different parameters and kernel functions combined with the method of two-fold cross validation. The result indicates that 87.47% accuracy can be reached when classifying hot and cold ORF sequences with the kernel of radial basis function combined with dinucleotide abundance based on codon usage.

Phosphorylation of histone H3 on Ser10 by auto-phosphorylated PAK1 is not essential for chromatin condensation and meiotic progression in porcine oocytes

Background： The p21-activated kinase 1 （PAK1）is essential of microtubule assembly during oocyte meiotic maturation porcine oocytes. for mitosis and plays an important role in the regulatio in mice; however, little is known about its role in Result： Total p21-activated kinase 1 （PAK1） and phosphorylated PAK1 at Thr423 （PAK1^Thr423） were consistently expressed in porcine oocytes from the germinal vesicle （GV） to the second metaphase （MII） stages, but phosphorylation of histone H3 at Serr10 （H3^ser10） was only expressed after the GV stage. Immunofiuorescence analysis revealed that PAK1Thr423 and H3^ser10 colocalized on chromosomes after the GV stage. Blocking of endogenous PAK1^Thr423 by injecting a specific antibody decreased the phosphorylation level of H3^ser10; however, it had no impact on chromatin condensation, meiotic progression, cleavage rate of blastomeres or the rate of blastocyst formation. Conclusion： Phosphorylation of PAK1^Thr423 is a spontaneous activation process and the activated PAK1^Thr423 can promote the phosphorylation of H3^ser10; however, this pathway is not required for meiotic maturation of porcine oocytes or early embryonic development.

Identification of reference genes provides functional insights into meiotic recombination suppressors in Gerbera hybrida

Gerbera Hybrida is one of the important cut flowers across the world.The novel traits are the primarily market requirements and the breeding targets,mainly determined by the degree of genetic variation after hybridization.However,meiotic recombination is highly conserved in most eukaryotes which suppressed the crossover formation and limited the genetic diversity.Recently,several meiotic recombination suppressors have been identified and characterized in plants,whereas it remains elusive in G.hybrida.In order to characterize the expression patterns of these suppressors in G.hybrida,20 candidate reference genes were identified from the transcriptome datasets of G.hybrida,and their expression stabilities during plant development were evaluated by geNorm,NormFinder and BestKeeper.Although the most stable reference genes were variable in different softwares,comprehensive ranking revealed that PGK2 was the most stable reference gene and GAPDH was the most unstable one.The expression patterns of FANCM,FIGL1,RECQ4,RM1,and FLIP further validated that PGK2 was suitable for normalization of gene expression.Our study identified a reliable reference gene for gene expression during meiotic recombination,and provided functional insights into meiotic recombination suppressors in G.hybrida.

Pins homolog LGN regulates meiotic spindle organization in mouse oocytes

Mouse oocytes undergo polarization during meiotic maturation, and this polarization is essential for asymmetric cell divisions that maximize retention of maternal components required for early development. Without conventional centrosomes, the meiotic spindle has less focused poles and is barrel-shaped. The migration of meiotic spindles to the cortex is accompanied by a local reorganization and polarization of the cortex. LGN is a conserved protein involved in cell polarity and regulation of spindle organization. In the present study, we characterized the localization dynamics of LGN during mouse oocyte maturation and analyzed the effects of LGN upregulation and downregulation on meiotic spindle organization. At the germinal vesicle stage, LGN is distributed both cytoplasmically and at the cortex. During maturation, LGN localizes to the meiotic spindle apparatus and cortical LGN becomes less concentrated at the actin cap region. Excessive LGN induces meiotic spindle organization defects by elongating the spindle and enhancing pole focusing, whereas depletion of LGN by RNA interference results in meiotic spindle deformation and chromosome misalignment. Furthermore, the N-terminus of LGN has the ability of full-length LGN to regulate spindle organization, whereas the C-terminus of LGN controls cortical localization and polarization. Our results reveal that LGN is cortically polarized in mouse oocytes and is critical for meiotic spindle organization.

Casein kinase 2 modulates the spindle assembly checkpoint to orchestrate porcine oocyte meiotic progression

Background:CK2(casein kinase 2)is a serine/threonine-selective protein kinase that has been involved in a variety of cellular processes such as DNA repair,cell cycle control and circadian rhythm regulation.However,its functional roles in oocyte meiosis have not been fully determined.Results:We report that CK2 is essential for porcine oocyte meiotic maturation by regulating spindle assembly checkpoint(SAC).Immunostaining and immunoblotting analysis showed that CK2 was constantly expressed and located on the chromosomes during the entire oocyte meiotic maturation.Inhibition of CK2 activity by its selective inhibitor CX-4945 impaired the first polar body extrusion and arrested oocytes at M I stage,accompanied by the presence of BubR1 at kinetochores,indicative of activated SAC.In addition,we found that spindle/chromosome structure was disrupted in CK2-inhibited oocytes due to the weakened microtubule stability,which is a major cause resulting in the activation of SAC.Last,we found that the level DNA damage as assessed byγH2A.X staining was considerably elevated when CK2 was inhibited,suggesting that DNA damage might be another critical factor leading to the SAC activation and meiotic failure of oocytes.Conclusions:Our findings demonstrate that CK2 promotes the porcine oocyte maturation by ensuring normal spindle assembly and DNA damage repair.

NEW OBSERVATIONS ON THE MEIOTIC PROCESS IN THE MARINE DINOFLAGELLATE NOCTILUCA SCINTILLANS (NOCTILUCALES, DINOPHYCEAE)

The meiotic process in Noctiluca scintillans were observed under light microscope. Some abnormal cell divisions, incompletely separated "zoospores" and the changes of the zoospores are described in this paper. Together with the findings of field samplings and the previous results by other researchers, the process of meiosis in N. scintillans was supposed to be a pathway to reduce the extra high density of NH 3-N within the cell in order to ensure normal population growth.

Investigation on Evolutionary Relationships of the Subgenomes in Interspecific Triploid Cotton via Meiotic FISH

We report in this paper primary studies on interspecific species of cotton vis GISH(genomic in situ hybridization).We use interspecific triploid hybrids(F1 from hybridization of allotetraploid cultivated species with diploid A,D,or C genome species) and two cultivated tetraploids to study

The genome-wide meiotic recombination landscape in ciliates and its implications for crossover regulation and genome evolution

Meiotic recombination is essential for sexual reproduction and its regulation has been extensively studied in many taxa.However,genome-wide recombination landscape has not been reported in ciliates and it remains unknown how it is affected by the unique features of ciliates:the synaptonemal complex(SC)-independent meiosis and the nuclear dimorphism.Here,we show the recombination landscape in the model ciliate Tetrahymena thermophila by analyzing single-nucleotide polymorphism datasets from 38 hybrid progeny.We detect 1021 crossover(CO)events(35.8 per meiosis),corresponding to an overall CO rate of 9.9 cM/Mb.However,gene conversion by non-crossover is rare(1.03 per meiosis)and not biased towards G or C alleles.Consistent with the reported roles of SC in CO interference,we find no obvious sign of CO interference.CO tends to occur within germ-soma common genomic regions and many of the 44 identified CO hotspots localize at the centromeric or subtelomeric regions.Gene ontology analyses show that CO hotspots are strongly associated with genes responding to environmental changes.We discuss these results with respect to how nuclear dimorphism has potentially driven the formation of the observed recombination landscape to facilitate environmental adaptation and the sharing of machinery among meiotic and somatic recombination.

A TOP6BL mutation abolishes meiotic DNA double-strand break formation and causes human infertility

Meiosis is pivotal for sexual reproduction and fertility. Meiotic programmed DNA double-strand breaks(DSBs) initiate homologous recombination, ensuring faithful chromosome segregation and generation of gametes. However, few studies have focused on meiotic DSB formation in human reproduction.Here, we report four infertile siblings born to a consanguineous marriage, with three brothers suffering from non-obstructive azoospermia and one sister suffering from unexplained infertility with normal menstrual cycles and normal ovary sizes with follicular activity. An autosomal recessive mutation in TOP6BL was found co-segregating with infertility in this family. Investigation of one male patient revealed failure in programmed meiotic DSB formation and meiotic arrest prior to pachytene stage of prophase I.Mouse models carrying similar mutations to that in patients recapitulated the spermatogenic abnormalities of the patient. Pathogenicity of the mutation in the female patient was supported by observations in mice that meiotic programmed DSBs failed to form in mutant oocytes and oocyte maturation failure due to absence of meiotic recombination. Our study thus illustrates the phenotypical characteristics and the genotype-phenotype correlations of meiotic DSB formation failure in humans.

Centromere pairing precedes meiotic chromosome pairing in plants

Meiosis is a specialized eukaryotic cell division, in which diploid cells undergo a single round of DNA replication and two rounds of nuclear division to produce haploid gametes. In most eukaryotes, the core events of meiotic prophase I are chromosomal pairing,synapsis and recombination. To ensure accurate chromosomal segregation, homologs have to identify and align along each other at the onset of meiosis. Although much progress has been made in elucidating meiotic processes, information on the mechanisms underlying chromosome pairing is limited in contrast to the meiotic recombination and synapsis events. Recent research in many organisms indicated that centromere interactions during early meiotic prophase facilitate homologous chromosome pairing, and functional centromere is a prerequisite for centromere pairing such as in maize. Here, we summarize the recent achievements of chromosome pairing research on plants and other organisms, and outline centromere interactions, nuclear chromosome orientation,and meiotic cohesin, as main determinants of chromosome pairing in early meiotic prophase.

A dynamic regulation of nitrogen on floret primordia development in wheat

Nitrogen(N)fertilization is critical for spike and floret development,which affects the number of fertile florets per spike(NFFs).However,the physiological regulation of the floret development process by N fertilization is largely unknown.A high temporal-resolution investigation of floret primordia number and morphology,dry matter,and N availability was conducted under three N fertilization levels:0(N0),120(N1)and 240(N2)kg ha^(−1).Interestingly,fertile florets at anthesis stage were determined by those floret primordia with meiotic ability at booting stage:meiotic ability was a threshold that predicted whether a floret primordium became fertile or abortive florets.Because the developmental rate of the 4th floret primordium in the central spikelet was accelerated and then they acquired meiotic ability,the NFFs increased gradually as N application increased,but the increase range decreased under N2.There were no differences in spike N concentration among treatments,but leaf N concentration was increased in the N1 and N2 treatments.Correspondingly,dry matter accumulation and N content of the leaf and spike in the N1 and N2 treatments was increased as compared to N0.Clearly,optimal N fertilization increased leaf N availability and transport of assimilates to spikes,and allowed more floret primordia to acquire meiotic ability and become fertile florets,finally increasing NFFs.There was no difference in leaf N concentration between N1 and N2 treatment,whereas soil N concentration at 0–60 cm soil layers was higher in N2 than in N1 treatment,implying that there was still some N fertilization that remained unused.Therefore,improving the leaf’s ability to further use N fertilizer is vital for greater NFFs.

SGK3在小鼠卵母细胞第一次减数分裂恢复中的作用及其机制

目的:探讨血清和糖皮质激素诱导的蛋白激酶3(SGK3)在小鼠卵母细胞第一次减数分裂恢复中的作用,初步阐明SGK3在哺乳动物卵母细胞早期发育中的调控机制。方法:利用超排卵技术获取生发泡(GV)期小鼠卵母细胞,利用显微注射技术将表达质粒体外转录获得的SGK3 mRNA注射至GV期卵母细胞,分为对照组、Tris-EDTA缓冲液(TE)组和SGK3 mRNA组,采用Western blotting法检测各组小鼠卵母细胞中SGK3蛋白表达水平,显微注射SGK3 mRNA后1、2、3和4 h观察并计算各组卵母细胞生发泡破裂(GVBD)率,采用SGK3抗体稀释抑制实验观察各组卵母细胞形态表现,采用Western blotting法检测体外培养不同时间点卵母细胞中磷酸化SGK3(pSer48)(SGK3-pSer48)和磷酸化细胞分裂周期蛋白2(CDC2)(pTyr15)(CDC2-pTyr15)蛋白表达水平。结果:与对照组和TE组比较,SGK3 mRNA组小鼠卵母细胞中SGK3蛋白表达水平升高(P<0.01),显微注射后1和2 h时GVBD率升高(P<0.01)。SGK3抗体稀释抑制实验,随着SGK3抗体浓度增加,各组小鼠卵母细胞GVBD率呈浓度依赖性降低。过表达SGK3后,与对照组比较,SGK3 mRNA组小鼠卵母细胞中检测不到CDC2-pTyr15蛋白表达的时间至少提前1 h。不同稀释浓度SGK3抗体作用后,与对照组比较,随着SGK3抗体浓度升高和时间的延长,小鼠卵母细胞中CDC2-pTyr15蛋白表达水平逐渐降低(P<0.01),SGK3-pSer486蛋白表达水平逐渐升高(P<0.01)。结论:过表达SGK3可以增加小鼠卵母细胞GVBD率,加快CDC2-pTyr15的脱磷酸化,而CDC2-pTyr15的脱磷酸化晚于SGK3-Ser486的磷酸化。SGK3可能作为CDC2上游调节因子参与调控小鼠卵母细胞第一次减数分裂的恢复。

A new TEX11 mutation causes azoospermia and testicular meiotic arrest

There are many unknown genetic factors that lead to infertility in nonobstructive azoospermia men.Here,we performed whole-exome sequencing in blood samples obtained from 40 azoospermia patients with meiotic arrest and found a novel c.151_154del(p.D51fs)frame-shift mutation in exon 3 of the testis expressed 11(TEX11)gene in one patient.Sanger sequencing analysis of the patient and 288 fertile men was performed to validate the mutation.Immunohistochemical analysis showed TEX11 expression in late-pachytene spermatocytes and in round spermatids in fertile human testes.In contrast,testes of the patient with TEX11 mutation underwent meiotic arrest and lacked TEX11 expression.Western blotting of human embryonic kidney(HEK293)cells transfected with a vector for the p.D51fs TEX11 variant detected no TEX11 expression.In conclusion,we identified a novel frame-shift mutation in the TEX11 gene in an azoospermia patient,emphasizing that this gene should be included in genetic screening panels for the clinical evaluation of azoospermia patients.

Rescue of male infertility through correcting a genetic mutation causing meiotic arrest in spermatogonial stem cells

Azoospermia patients who carry a monogenetic mutation that causes meiotic arrest may have their biological child through genetic correction in spermatogonial stem cells(SSCs).However,such therapy for infertility has not been experimentally investigated yet.In this study,a mouse model with an X-linked testis-expressed 11(TEX11)mutation(Tex11PM/Y)identified in azoospermia patients exhibited meiotic arrest due to aberrant chromosome segregation.Tex11PM/Y SSCs could be isolated and expanded in vitro normally,and the mutation was corrected by clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated endonuclease 9(Cas9),leading to the generation of repaired SSC lines.Whole-genome sequencing demonstrated that the mutation rate in repaired SSCs is comparable with that of autonomous mutation in untreated Tex11PM/Y SSCs,and no predicted off-target sites are modified.Repaired SSCs could restore spermatogenesis in infertile males and give rise to fertile offspring at a high efficiency.In summary,our study establishes a paradigm for the treatment of male azoospermia by combining in vitro expansion of SSCs and gene therapy.

Behavior of Meiotic Chromosomes in Pinus wallichiana,P.strobus and Their Hybrid and nrDNA Localization in Pollen Mother Cells of the Hybrid by Using FISH

The complete process of meiosis was investigated in Pinus wallichiana, P. strobus and their artificial hybrid （F1） using microsporocytes. It is revealed that there were slightly lower chiasma frequency, lower ring bivalent frequency, lower meiotic index and distinctly higher frequency of aberrance （chromosomal bridges, fragments or micronuclei） in pollen mother cells （PMCs） of the hybrid （F1） than those of the parental species, which showed a certain degree of differentiation between homologous chromosomes of the two parents. However, relatively higher frequency of ring bivalents and higher meiotic index in all the three entities indicate the great stability of genomes of parental species, and the differentiation of genomes between the two parents must have been slight. Total nineteen signal loci of 18S rDNA were observed in nine bivalents of the hybrid （F1）, among which one bivalent bears two loci, while the others have only one. It is suggested that distinct differentiation at genetic level existed in homologous chromosomes of the two parental species, whereas only slight differentiation at karyotypic and genomic levels take place between the parent species.

Meiotic nuclear divisions 1(MND1)fuels cell cycle progression by activating a KLF6/E2F1 positive feedback loop in lung adenocarcinoma

Background:Considering the increase in the proportion of lung adenocarcinoma(LUAD)cases among all lung cancers and its considerable contribution to cancer-related deaths worldwide,we sought to identify novel oncogenes to provide potential targets and facilitate a better understanding of the malignant progression of LUAD.Methods:The results from the screening of transcriptome and survival analyses according to the integrated Gene Expression Omnibus(GEO)datasets and The Cancer Genome Atlas(TCGA)data were combined,and a promising risk biomarker called meiotic nuclear divisions 1(MND1)was selectively acquired.Cell viability assays and subcutaneous xenograftmodelswere used to validate the oncogenic role ofMND1 in LUADcell proliferation and tumor growth.Aseries of assays,including mass spectrometry,co-immunoprecipitation(Co-IP),and chromatin immunoprecipitation(ChIP),were performed to explore the underlying mechanism.Results:MND1 up-regulation was identified to be an independent risk factor for overall survival in LUAD patients evaluated by both tissue microarray staining and third party data analysis.In vivo and in vitro assays showed that MND1 promoted LUAD cell proliferation by regulating cell cycle.The results of the Co-IP,ChIP and dual-luciferase reporter assays validated that MND1 competitively bound to tumor suppressor Kruppel-like factor 6(KLF6),and thereby protecting E2F transcription factor 1(E2F1)from KLF6-induced transcriptional repression.Luciferase reporter and ChIP assays found that E2F1 activated MND1 transcription by binding to its promoter in a feedback manner.Conclusions:MND1,KLF6,and E2F1 form a positive feedback loop to regulate cell cycle and confer DDP resistance in LUAD.MND1 is crucial for malignant progression and may be a potential therapeutic target in LUAD patients.

New insights into the role of DNA synthesis in meiotic recombination

Meiosis comprises two rounds of nuclear division following a single phase of DNA replication, leading to the production of haploid gametes and is essential for sexual reproduction in eukaryotes. Unlike mitosis, meiosis involves homologous chromosome pairing, synapsis, and recombination during prophase I. Meiotic recombination not only ensures the accurate segregation of homologs, but also redistributes alleles among offspring. DNA synthesis is a critical process during meiotic recombination, but our understanding of the proteins that execute and regulate it is limited. This review summarizes the recent advances in defining the role of DNA synthesis in meiotic recombina- tion through analyses of DNA synthesis genes, with specific emphasis on DNA polymerases （e.g., Pole and PolS）, replication processivity factor RFC1 and translesion polymerases （e.g., Pol~）. We also present a new double strand break repair model for meiotic recombination, which includes lagging strand DNA synthesis and leading strand elongation. Finally, we propose that DNA synthesis is one of critical factors for discriminating meiotic recombination pathways and that this differentiation may be conserved among eukaryotes.

减数分裂内切酶1高表达对肝细胞癌预后的影响

目的探讨减数分裂内切酶1(EME1)的高表达对肝细胞癌(HCC)预后的临床意义。方法利用癌症和肿瘤基因图谱(TCGA)数据库及高通量基因表达(GEO)数据库,对HCC肿瘤与非肿瘤组织差异表达基因进行筛选并进行生存分析。回顾性收集2010年1月-2014年12月于解放军总医院第五医学中心行肝癌切除术的80例患者的病理组织样本,采用免疫组织化学法检测EME1的表达情况,进行生存分析,评估EME1对肝癌患者术后5年生存率的影响;采用基因富集分析预测EME1在HCC中的功能。结果TCGA数据库筛选出371例HCC癌组织及50例非肿瘤组织样本,分析显示EME1 mRNA在HCC癌组织中明显高表达。筛选GEO数据库中的107例样本(包括70例HCC癌组织,37例非肿瘤组织),癌组织的EME1 mRNA表达量明显高于非肿瘤组织(P<0.05)。生存分析显示EME1高表达组术后5年总体生存率明显低于低表达组(44.1%vs.53.0%,P<0.05)。免疫组化结果半定量分析显示,EME1高表达组的总体生存率明显低于低表达组(32.8%vs.45.0%,P<0.05),多因素COX分析显示,EME1高表达[风险比(HR)=2.234,95%CI 1.073~4.649,P=0.032]和中国肝癌分期(CNLC)高分期(HR=4.317,95%CI 1.799~10.359,P=0.001)是影响HCC患者术后5年生存率的独立危险因素。结论EME1在HCC组织中高表达,并与HCC患者的不良预后相关,可作为HCC治疗的潜在靶点。

沉默减数分裂内切酶1(EME1)抑制肝癌细胞增殖的机制

目的探讨减数分裂内切酶1(EME1)在肝癌组织中的表达及其对肝癌细胞生物学行为的影响。方法筛选TCGA数据库肝癌样本中的差异表达基因。采用免疫组化和Western Blot分析EME1在肝癌组织中的表达丰度。通过短发夹RNA(shRNA)构建慢病毒并感染BEL-7404细胞干扰EME1基因表达,分为沉默组(shEME1)和对照组(shCtrl)。通过实时荧光定量PCR法和Western Blot检测两组EME1 mRNA和蛋白表达水平,Celigo计数法及MTT活性检测细胞增殖率,流式细胞术检测细胞周期,Caspase3/7活性检测细胞凋亡。两组间比较采用成组t检验。结果TCGA结果显示EME1的mRNA表达水平在肝癌组织中是癌旁组织的18.9倍(114.5±153.0 vs 8.0±7.2,t=5.00,P<0.001);EME1的蛋白表达水平在肝癌组织中是癌旁组织的7.0倍(免疫组化检测,8.4±2.6 vs 1.2±0.4,t=7.55,P<0.001)和2.5倍(Western Blot检测,249.0%±35.5%vs 100.0%±77.8%,t=3.02,P<0.05)。慢病毒感染后,相对于对照组,沉默组EME1的mRNA表达水平下降了29.9%(29.9%±0.9%vs 100.0%±3.6%,t=32.82,P<0.001),蛋白表达水平显著下降了35.7%(35.7%±14.9%vs 100.0%±28.9%,t=3.42,P<0.05);细胞计数下降了45.1%(4053±167 vs 8988±477,t=16.91,P<0.001)、细胞活性下降至66.9%(0.518±0.046 vs 0.774±0.022,t=8.74,P<0.001)及细胞克隆形成能力下降至29.0%(75±6 vs 260±9,t=28.92,P<0.001)。与对照组比较,沉默组G1期细胞(49.9%vs 44.0%,t=8.96,P<0.001)比例增多,G2/M期(15.9%vs 17.9%,t=9.13,P<0.001)与S期(34.2%vs 38.1%,t=6.91,P<0.001)的细胞比例减少;Caspase3/7活性增强了1.5倍(145.8%±5.9%vs 100.0%±2.3%,t=12.50,P<0.001)。结论EME1在肝癌组织中高表达,沉默EME1基因可抑制肝癌细胞增殖,促进细胞凋亡。