MRE11 is essential for the long-term viability of undifferentiated spermatogonia.

In the meiotic prophase, programmed SPO11-linked DNA double-strand breaks (DSBs) are repaired by homologous recombination (HR). The MRE11-RAD50-NBS1 (MRN) complex is essential for initiating DNA end resection, the first step of HR. However, residual DNA end resection still occurs in Nbs1 knockout (KO) spermatocytes for unknown reasons. Here, we show that DNA end resection is completely abolished in Mre11 KO spermatocytes. In addition, Mre11 KO, but not Nbs1 KO, undifferentiated spermatogonia are rapidly exhausted due to DSB accumulation, proliferation defects, and elevated apoptosis. Cellular studies reveal that a small amount of MRE11 retained in the nucleus of Nbs1 KO cells likely underlies the differences between Mre11 and Nbs1 KO cells. Taken together, our study not only demonstrates an irreplaceable role of the MRE11 in DNA end resection at SPO11-linked DSBs but also unveils a unique function of MRE11 in maintaining the long-term viability of undifferentiated spermatogonia.

Correlations of religious beliefs with anxiety and depression of Chinese adolescents.

Objective: This study was designed to investigate the prevalence of religious belief and its relationship with psychiatric symptoms among Chinese adolescents. Methods: This study recruited 11,603 adolescents in Grades 7-9 from March 21 to 31, 2020 in five cities in China. The religious beliefs of adolescents were collected by asking whether they held religious beliefs and what type of religious beliefs they held. The Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder-7 Scale (GAD-7) were used to assess depressive and anxiety symptoms in all adolescents. Demographics, religious beliefs, and mental health status were collected through the professional version of Wenjuanxing. Results: Of 11,069 valid questionnaires collected, 847 (7.7%) reported holding religious beliefs. Adolescents with religious beliefs showed significantly more severe symptoms of depression and anxiety compared to those without religious beliefs (both p<0.05). Logistic regression analysis revealed that religious belief was a risk factor for symptoms of depression (OR = 1.37, 95%CI: 1.16-1.61, p < 0.001) and anxiety (OR = 1.49, 95%CI: 1.23-1.79, p < 0.001) after controlling age, gender, and parental marital status. Conclusions: Our findings suggest that religiousness in adolescents was associated with a higher likelihood of depression/more intense depressive symptoms. In addition, religious Chinese adolescents should be provided with more resources to help them cope with mental health concerns.

Y chromosome polymorphisms contribute to an increased risk of non-obstructive azoospermia: a retrospective study of 32,055 Chinese men.

PURPOSE: To investigate the prevalence of Y chromosome polymorphisms in Chinese men and analyze their associations with male infertility and female adverse pregnancy outcomes. METHODS: The clinical data of 32,055 Chinese men who underwent karyotype analysis from October 2014 to September 2019 were collected. Fisher's exact test, chi-square test, or Kruskal-Wallis test was used to analyze the effects of Y chromosome polymorphism on semen parameters, azoospermia factor (AZF) microdeletions, and female adverse pregnancy outcomes. RESULTS: The incidence of Y chromosome polymorphic variants was 1.19% (381/32,055) in Chinese men. The incidence of non-obstructive azoospermia (NOA) was significantly higher in men with the Yqh- variant than that in men with normal karyotype and other Y chromosome polymorphic variants (p < 0.050). The incidence of AZF microdeletions was significantly different among the normal karyotype and different Y chromosome polymorphic variant groups (p < 0.001). The detection rate of AZF microdeletions was 28.92% (24/83) in the Yqh- group and 2.50% (3/120) in the Y ≤ 21 group. The AZFb + c region was the most common AZF microdeletion (78.57%, 22/28), followed by AZFc microdeletion (7.14%,2/28) in NOA patients with Yqh- variants. There was no significant difference in the distribution of female adverse pregnancy outcomes among the normal karyotype and different Y chromosome polymorphic variant groups (p = 0.528). CONCLUSIONS: Patients with 46,XYqh- variant have a higher incidence of NOA and AZF microdeletions than patients with normal karyotype and other Y chromosome polymorphic variants. Y chromosome polymorphic variants do not affect female adverse pregnancy outcomes.

Splicing Mutation in DNALI1 Causes Male Infertility with Severe Oligoasthenoteratozoospermia in Humans.

Oligo-astheno-teratozoospermia (OAT), which is a common cause of male infertility, can be caused by genetic factors. This study reports on a case of a male patient suffering from infertility concomitant with OAT. Whole-exome sequencing (WES) confirmed the presence of a homozygous variant (NM_003462: c.464-1G > A) in the DNALI1 gene via Sanger sequencing. Immunofluorescence staining demonstrated that the DNALI1 signal was nearly undetectable in the patient's sperm. Bioinformatics analysis revealed that this mutation could reverse the splicing of the exon 4 acceptor splice site. A minigene experiment was performed to verify the mutation and the results confirmed that the mutation disrupted the splicing. Our findings show that this rare mutation in DNALI1 contributes to male infertility and OAT in humans, thereby expanding our understanding of the causes and pathogenesis of male infertility. This knowledge facilitates genetic counseling, clinical diagnosis, and therapeutic development of male infertility.

Re-assessment of the close relationship between serum FSH levels and semen quality: a retrospective cohort study of 11,929 Chinese men.

PURPOSE: To establish a medically valuable normal reference interval of follicle-stimulating hormone (FSH) levels in males with normal semen and to assess the predictive value of FSH in males exhibiting semen abnormalities. METHODS: The study involved male patients who underwent their initial serum sex hormone test and semen test between October 2013 and June 2023. The reference interval was identified as the 95% confidence interval (CI) of FSH values in the patients with normal semen parameters. Then, in the total study population, receiver operating characteristic (ROC) curves were performed to evaluate the discriminatory ability of FSH for oligozoospermia and non-obstructive azoospermia (NOA). Besides, multivariable logistic regression was performed to investigate the association of FSH with oligozoospermia and NOA adjusted by age. RESULTS: A total of 11,929 patients were finally enrolled in the study. The normal reference interval of FSH ranged from 1.70 IU/L to 7.60 IU/L (median: 3.98 IU/L) based on 4595 patients with normal semen routine parameters. In the total patients, ROC curves showed FSH to have a "fair" discriminatory ability for oligozoospermia (area under receiver operating characteristic curve (AUC) 0.747, threshold 7.32 IU/L, accuracy 0.734, positive predictive value (PPV) 0.754, negative predictive value (NPV) 0.726), while ROC curves showed FSH to have a "excellent" discriminatory ability for NOA (AUC: 0.921, threshold 10.18 IU/L, accuracy 0.903, PPV 0.593, NPV 0.972). Besides, multivariable logistic regression showed that FSH ≥ 7.32 IU/L was associated with a 8.51-fold increase in the risk of oligozoospermia adjusted by age, while FSH ≥ 10.18 IU/L was associated with a 38.93-fold increase in the risk of NOA. CONCLUSIONS: Our findings indicated that the reference interval for FSH in males with normal semen was 1.70-7.60 IU/L and found that FSH was capable of effectively discerning oligospermia and NOA.

The neural correlates of apathy in the context of aging and brain disorders: a meta-analysis of neuroimaging studies.

Introduction: Apathy is a prevalent mood disturbance that occurs in a wide range of populations, including those with normal cognitive aging, mental disorders, neurodegenerative disorders and traumatic brain injuries. Recently, neuroimaging technologies have been employed to elucidate the neural substrates underlying brain disorders accompanying apathy. However, the consistent neural correlates of apathy across normal aging and brain disorders are still unclear. Methods: This paper first provides a brief review of the neural mechanism of apathy in healthy elderly individuals, those with mental disorders, neurodegenerative disorders, and traumatic brain injuries. Further, following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, the structural and functional neuroimaging meta-analysis using activation likelihood estimation method is performed on the apathy group with brain disorders and the healthy elderly, aiming at exploring the neural correlates of apathy. Results: The structural neuroimaging meta-analysis showed that gray matter atrophy is associated with apathy in the bilateral precentral gyrus (BA 13/6), bilateral insula (BA 47), bilateral medial frontal gyrus (BA 11), bilateral inferior frontal gyrus, left caudate (putamen) and right anterior cingulate, while the functional neuroimaging meta-analysis suggested that the functional connectivity in putamen and lateral globus pallidus is correlated with apathy. Discussion: Through the neuroimaging meta-analysis, this study has identified the potential neural locations of apathy in terms of brain structure and function, which may offer valuable pathophysiological insights for developing more effective therapeutic interventions for affected patients.

Effects of major depression and bipolar disorder on erectile dysfunction: a two-sample mendelian randomization study.

BACKGROUND AND AIMS: There are currently no clear conclusions about whether major depression (MD) and bipolar disorder (BD) increase the risk of erectile dysfunction (ED). In our study, we used a Mendelian randomization (MR) analysis to discover the causal associations between MD, BD and ED. METHODS: We got single-nucleotide polymorphisms (SNPs) related to MD, BD and ED from the MRC IEU Open genome-wide association study (GWAS) datasets. After a series of selection, SNPs left were selected as instrumental variables (IVs) of MD and BD for the following MR test to evaluate the relationship of genetically predicted MD or BD with the incidence of ED. Among them, we used the random-effects inverse-variance weighted (IVW) method as the main analysis. Finally, sensitivity analyses were further performed using Cochran's Q test, funnel plots, MR-Egger regression, Leave-one-out method and MR- pleiotropy residual sum and outlier (PRESSO). RESULTS: Genetically-predicted MD was causally related to the incidence of ED in the IVW methods (odds ratio (OR), 1.53; 95% confidence interval (CI), 1.19-1.96; p = 0.001), while no causal impact of BD on the risk of ED (OR = 0.95, 95% CI 0.87-1.04; p = 0.306). The results of sensitivity analyses supported our conclusion, and no directional pleiotropy were found. CONCLUSION: The findings of this research found evidence of a causal relationship between MD and ED. However, we did not find a causal relationship between BD and ED in European populations.

Development and validation predictive models of sperm retrieval for azoospermic men undergoing testicular sperm aspiration: a multicentre, retrospective, cohort study.

PURPOSE: Testicular sperm aspiration (TESA) is widely used to retrieve sperm from testis. Diagnostic testicular biopsy should not be routinely performed for azoospermia. Therefore, a good predictive model is needed before TESA. METHODS: A total of 1972 azoospermia patients constituted the modelling set, and 260 azoospermia patients from two other centres constituted the validation set. An integrated predictive model was built using logistic regression. Receiver operating characteristic (ROC), calibration and decision curve analyses were performed to evaluate the performance of follicle-stimulating hormone (FSH), semen volume, testicular volume and the integrated model. RESULTS: The FSH level was the best univariate predictor for successful sperm retrieval (SSR) and was better than semen volume and testicular volume alone (p<0.001, threshold 6.17 IU/L, modelling set area under receiver operating characteristic curve (AUC) 0.80, accuracy 0.79; validation set AUC 0.87, accuracy 0.78). The integrated predictive model had excellent accuracy for predicting SSR (modelling set: AUC 0.93, accuracy 0.89; validation set: AUC 0.96, accuracy: 0.89). Calibration curve analysis indicated that the integrated model calibration was good and better than that of FSH, semen volume and testicular volume alone. Decision curve analysis indicated with a threshold probability between 0.05 and 0.98, the integrated model added more benefit than treating either all or no patients. CONCLUSIONS: The integrated model has excellent discrimination and good calibration. It can help azoospermic men make better decisions before TESA. It should be noted that TESA is not the first-line treatment for non-obstructive azoospermia because of a low sperm retrieval rate.

Long-Term Disturbed Expression and DNA Methylation of SCAP/SREBP Signaling in the Mouse Lung From Assisted Reproductive Technologies.

Assisted reproductive technology (ART) has been linked to cholesterol metabolic and respiratory disorders later in life, but the mechanisms by which biosynthetic signaling remain unclear. Lung inflammatory diseases are tightly linked with the sterol regulatory element-binding protein (SREBP) and SREBP cleavage-activating protein (SCAP), but this has not been shown in an ART offspring. Here, mouse models from a young to old age were established including in vitro fertilization (IVF), intracytoplasmic injection (ICSI), and in vivo fertilized groups. In our results, significantly higher plasma levels of CRP, IgM, and IgG were identified in the aged ICSI mice. Additionally, pulmonary inflammation was found in four aged ART mice. At three weeks, ART mice showed significantly downregulated levels of Scap, Srebp-1a, Srebp-1c, and Srebf2 mRNA in the lung. At the same time, significant differences in the DNA methylation rates of Scap-Srebfs and protein expression of nuclear forms of SREBPs (nSREBPs) were detected in the ART groups. Only abnormalities in the expression levels of Srebp-1a and Srebp-1c mRNA and nSREBP1 protein were found in the ART groups at 10 weeks. However, at 1.5 years old, aberrant expression levels and DNA methylation of SCAP, SREBP1, and SREBP2, and their associated target genes, were observed in the lung of the ART groups. Our results indicate that ART increases long-term alterations in SCAP/SREBP expression that may be associated with their aberrant methylation status in mouse.

Sperm DNA fragmentation and male fertility: a retrospective study of 5114 men attending a reproductive center.

PURPOSE: The sperm DNA fragmentation index (DFI) was quantitatively measured and its relationship with age, semen quality, and infertility conditions was investigated. METHODS: Semen routine test and sperm DFI were performed in 2760 infertile male and 2354 male whose spouse experienced at least one unexplained miscarriage to analyze the correlation between sperm DNA damage, semen routine parameters, and age. RESULTS: Sperm DFI was significantly lower from patients whose wife experienced unexplained miscarriage compared to infertility males (p = 0.000). An inverse correlation between sperm DFI and sperm progressive motility was observed (rs = - 0.465, p = 0.000) and sperm DFI was positively correlated with age (rs = 0.255, p = 0.000). However, the correlation between sperm DFI and sperm concentration, semen volume, total sperm count, and motile sperm count were not proved. CONCLUSIONS: Sperm DFI is an important indicator for evaluating the quality of semen. Sperm DNA integrity testing is preferentially recommended to those who have decreased sperm progressive motility, especially older men. An integrative analysis of sperm DFI, sperm progressive motility, age, and infertility conditions can provide a more comprehensive assessment of male fertility.

Decreased miR-149 expression in sperm is correlated with the quality of early embryonic development in conventional in vitro fertilization.

miRNAs play a critical role in the regulation of highly orchestrated gene expression profiles during spermatogenesis and early human embryonic development. However, there is much less information available on the effects of sperm-borne miRNAs on human embryonic development than on spermatogenesis. This study was designed to assess the relationship between two sperm-borne miRNAs (miR-34c and miR-149) and preimplantation embryo development in conventional in vitro fertilization treatment. A positive correlation was seen between a decreased level of miR-149 and a higher percentage of good-quality embryos on day 3 in conventional in vitro fertilization treatment (P < 0.0001), but no correlation was seen between miR-34c and a higher percentage of good-quality embryos (P = 0.1084). Receiver-operating characteristic curve analysis and logistic regression analysis showed that sperm-borne miR-149 with decreased expression was significantly associated with a high rate of good-quality embryos (area under the curve 0.781) (odds ratio: 0.078, 95 % confidence interval: 0.024-0.259, P < 0.0001). Our results demonstrate that the expression profile of miR-149 with significantly decreased expression could be used as a first indication of early embryonic development and may provide novel insight into the biological background of idiopathic infertile males.

Improved oral bioavailability and anti-chronic renal failure activity of chrysophanol via mixed polymeric micelles.

AIMS: This study was designed to prepare chrysophanol-loaded micelles (CLM) to improve the oral bioavailability, targetability and anti-chronic renal failure (CRF) activity of chrysophanol (CH). METHODS: The preparation of CLM was achieved via thin-film dispersion technique. The in vitro release of CLM compared with free CH was measured in phosphate buffer solution (PBS) containing 0.5%w/v sodium dodecyl sulphate (pH 6.8) while the pharmacokinetic and anti-CRF activity study was also conducted in rats. Moreover, the tissue distribution of CLM was investigated in the mice. RESULTS: The CLM had particle size (PS) of 29.64 ± 0.71 nm, and encapsulation efficiency (EE) of 90.48 ± 1.22%w/w. The cumulative release rate of CH from the micellar system was significantly higher than that of the free CH (86%m/m vs. 15%m/m, p < 0.01). In vivo pharmacokinetic studies showed that the bioavailability of CLM after oral administration was substantially improved (about 3.4 times) compared with free drugs (p < 0.01). Also, it was observed that CLM accumulated well in the liver and brain. Moreover, in vitro renal podocytes study showed that CLM had better protection against renal podocyte damage than the free CH. In addition, CLM significantly (p < 0.01) reduced levels of blood urea nitrogen (BUN), kidney injury molecule-1 (Kim-1), and serum creatinine (SCr), which obviously improved kidney damage in rats with CRF. CONCLUSIONS: Collectively, these findings suggest that mixed micelles may be used as a promising drug delivery system for oral bioavailability improvement and concomitantly enhance the anti-CRF activity of CH, as well as provide a basis for the clinical application of CH.

Sperm Ribosomal DNA Promoter Methylation Levels Are Correlated With Paternal Aging and May Relate With in vitro Fertilization Outcomes.

The impact of aging on reproductive outcomes has received considerable critical attention; however, there is much less information available on the effects of paternal age compared to the effects of maternal age. In this study, methylation levels of sperm rDNA promoter regions and Long Interspersed Nucleotide Element 1 (LINE-1) were measured using pyrosequencing and fertilization, day 3 good-quality embryo, pregnancies, and implantation results were assessed. We observed significantly increasing levels of DNA methylation in the sperm rDNA promoter regions with age based on stratifying the samples by age alone (P = 0.0001) and performing linear regression analysis (P < 0.0001). Meanwhile, no statistically significant correlations were observed between global LINE-1 methylation with age. No statistically significant correlations were observed between sperm rDNA promoter methylation levels and either the day 3 good-quality embryo rate or clinical pregnancy rate. In contrast, the correlation between sperm rDNA promoter methylation levels and fertilization (2 pronuclei) rate was nearly significant (P = 0.0707), especially the methylation levels of some individual CpG units (CpG_10, P = 0.0176; CpG_11, P = 0.0438; CpG_14, P = 0.0232) and rDNA promoter methylation levels measured using primerS2 (P = 0.0513). No significant correlation was found between sperm rDNA promoter methylation levels and fertilization rates (2 pronuclei, 1 pronuclei, and 1 polypronuclei). Our results demonstrate that sperm are susceptible to age-associated alterations in methylation levels of rDNA promoter regions, suggesting that sperm rDNA promoter methylation levels can be applied to DNA methylation-based age prediction, and that the aberrant methylation of rDNA promoters may be partially responsible for enhanced disease susceptibility of offspring sired by older fathers. Methylation levels of sperm rDNA promoter regions may correlate with polypronuclei rates of IVF programs.

Differential microRNAs expression in seminal plasma of normospermic patients with different sperm DNA fragmentation indexes.

Sperm DNA fragmentation index (SDF), as an important supplement to routine semen parameters, has been proposed to discriminate between fertile and infertile men, and predicts the outcomes of natural conception and in vitro fertilization. Unfortunately there are uncertainty and contradictory evidences regarding the importance of SDF. An important reason is the fact that significant and fundamental research about SDF is rare. This study was designed to characterize the microRNA (miRNA) expression profile in seminal plasma of normospermic patients with different SDF and their implications in human fertility. Using next-generation sequencing (NGS), a total of 897 human miRNAs were detected from 10 seminal plasma samples, out of which 431 differentially expressed miRNAs in 5 pairs of seminal plasma samples (each pair of seminal plasma samples obtained from the same male), with 14 miRNAs were identified in all the pairs. According to the fold change and expression level, 7 miRNAs including miR-374b-5p, miR-429, hsa-miR-26b-5p, miR-21-5p, miR-4257, miR-135b-5p and miR-134-5p were selected for further excavation. MiR-374b-5p and miR-26b-5p were significantly different in 3 sets of individual seminal plasma samples with different SDF from total 90 infertile patients (30 patients each set). Our results demonstrate that the profile of miR-374b and miR-26b with significantly decreased expression could be used as a first indication of increased SDF. And miR-374b and miR-26b could serve as adjunct biomarkers for the diagnosis of idiopathic infertile males.

An APC Mutation in a Large Chinese Kindred With Familial Adenomatous Polyposis Was Identified Using Both Next Generation Sequencing and Simple STR Marker Haplotypes.

BACKGROUND: Familial adenomatous polyposis (FAP) is an autosomal dominant disorder characterized primarily by the development of numerous adenomatous polyps in the colon and a high risk for colorectal cancer. FAP is caused by germline mutations of the adenomatous polyposis coli (APC) gene. The proband in this family was a 39-year-old female patient with the pathologic diagnosis of adenomatous polyps, and then a five-generation kindred with FAP was characterized in the following years. This article identified an APC mutation, and demonstrated the practical use of APC-linked STR markers, which could be used to reduce misdiagnosis of prenatal diagnosis or preimplantation genetic diagnosis resulted from contamination or allele drop-out. METHODS: Next-generation sequencing (NGS) was used to identify the possible APC mutations in an affected individual from a family with autosomal dominant colon cancer. Targeted sequencing then used to identify additional related individuals with the mutation. Three short tandem repeat (STR) loci, D5S299, D5S134, and D5S346, were used for PCR-based microsatellite analysis of the APC gene in the extended family. RESULTS: We identified an APC: p.W553X mutation. The STR haplotype at the APC locus, A1B4C1, was shared by all clinically affected individuals with the APC: p.W553X mutation. In addition, the APC: p.D1822V variant was observed in 40% affected individuals and in two unaffected individuals. CONCLUSION: We described a protein truncation mutation, APC: p.W553X; demonstrated the value of APC-linked STR markers (D5S299, D5S134, and D5S346) haplotypes; and suggested the potential role of these haplotypes in detecting loss of heterozygosity of the APC gene.

MicroRNA-338-5p alleviates cerebral ischemia/reperfusion injury by targeting connective tissue growth factor through the adenosine 5'-monophosphate-activated protein kinase/mammalian target of rapamycin signaling pathway.

Cerebral ischemia/reperfusion (CIR) injury could lead to the function of brain cell disorder and cerebral infarction. MicroRNAs (miRNAs) have been reported to participate in the progression and protection of CIR injury. Thus, our study aimed to investigate the functional effects of microRNA-338-5p (miR-338-5p) on proliferation, apoptosis, and inflammatory response of CIR injury. According to the results, miR-338-5p was downregulated in the brain of the mice caused by CIR injury, and overexpression of miR-338-5p reduced the neurological deficit and infarct volume of the brain in the mice caused by CIR injury. Meanwhile, miR-338-5p overexpression promoted the proliferation, while suppressed the apoptosis and the inflammatory response of Neuro-2a cells exposed to hypoxia/reoxygenation (H/R). Interestingly, miR-338-5p directly targeted connective tissue growth factor (CTGF) and overexpression of CTGF reversed the functional effects of miR-338-5p on proliferation, apoptosis, and inflammatory response in Neuro-2a cells caused by H/R. More importantly, miR-338-5p affected the adenosine 5¢-monophosphate (AMP)-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway by regulating CTGF expression in Neuro-2a cells exposed to H/R. Taken together, we concluded that MiR-338-5p promoted the proliferation, while suppressed the apoptosis and the inflammatory response of cells exposed to H/R by targeting CTGF through the AMPK/mTOR signaling pathway.

Altered expression of DNA damage repair genes in the brain tissue of mice conceived by in vitro fertilization.

Our previous study revealed a higher incidence of gene dynamic mutation in newborns conceived by IVF, highlighting that IVF may be disruptive to the DNA stability of IVF offspring. However, the underlying mechanisms remain unclear. The DNA damage repair system plays an essential role in gene dynamic mutation and neurodegenerative disease. To evaluate the long-term impact of IVF on DNA damage repair genes, we established an IVF mouse model and analyzed gene and protein expression levels of MSH2, MSH3, MSH6, MLH1, PMS2, OGG1, APEX1, XPA and RPA1 and also the amount of H2AX phosphorylation of serine 139 which is highly suggestive of DNA double-strand break (γH2AX expression level) in the brain tissue of IVF conceived mice and their DNA methylation status using quantitative real-time PCR, western blotting and pyrosequencing. Furthermore, we assessed the capacity of two specific non-physiological factors in IVF procedures during preimplantation development. The results demonstrated that the expression and methylation levels of some DNA damage repair genes in the brain tissue of IVF mice were significantly changed at 3 weeks, 10 weeks and 1.5 years of age, when compared with the in vivo control group. In support of mouse model findings, oxygen concentration of in vitro culture environment was shown to have the capacity to modulate gene expression and DNA methylation levels of some DNA damage repair genes. In summary, our study indicated that IVF could bring about long-term alterations of gene and protein expression and DNA methylation levels of some DNA damage repair genes in the brain tissue and these alterations might be resulted from the different oxygen concentration of culture environment, providing valuable perspectives to improve the safety and efficiency of IVF at early embryonic stage and also throughout different life stages.

Decreased expression of MRE11 and RAD50 in testes from humans with spermatogenic failure.

PURPOSE: To assess testicular mRNA and protein expression levels of MRE11 and RAD50 in human azoospermia patients. METHODS: Patients diagnosed with maturation arrest at the spermatocyte stage (MA) and Sertoli cell-only syndrome (SCOS) were recruited through diagnostic testicular biopsy. Patients with normal spermatogenesis were studied as controls. In addition, knockdown of MRE11 and RAD50 was performed in GC-2spd(ts) cells to investigate their roles in cellular proliferation and apoptosis. RESULTS: mRNA and protein expression levels of MRE11 and RAD50 were measured using quantitative polymerase chain reaction, western blotting, and immunohistochemistry, respectively. Knockdown of both MRE11 and RAD50 utilized transfection with small interfering RNAs. CONCLUSION: Our findings demonstrated altered expression levels of MRE11 and RAD50 in human testes with MA and SCOS, and showed that these alterations might be associated with impaired spermatogenesis. These results offer valuable new perspectives into the molecular mechanisms of male infertility.

NBS1 is required for SPO11-linked DNA double-strand break repair in male meiosis.

DNA double-strand breaks (DSBs) pose a serious threat to genomic stability. Paradoxically, hundreds of programed DSBs are generated by SPO11 in meiotic prophase, which are exclusively repaired by homologous recombination (HR) to promote obligate crossover between homologous chromosomes. In somatic cells, MRE11-RAD50-NBS1 (MRN) complex-dependent DNA end resection is a prerequisite for HR repair, especially for DSBs that are covalently linked with proteins or chemicals. Interestingly, all meiotic DSBs are linked with SPO11 after being generated. Although MRN complex's function in meiotic DSB repair has been established in lower organisms, the role of MRN complex in mammalian meiotic DSB repair is not clear. Here, we show that MRN complex is essential for repairing meiotic SPO11-linked DSBs in male mice. In male germ cells, conditional inactivation of NBS1, a key component of MRN complex, causes dramatic reduction of DNA end resection and defective HR repair in meiotic prophase. NBS1 loss severely disrupts chromosome synapsis, generates abnormal chromosome structures, and eventually leads to meiotic arrest and male infertility in mice. Unlike in somatic cells, the recruitment of NBS1 to SPO11-linked DSB sites is MDC1-independent but requires other phosphorylated proteins. Collectively, our study not only reveals the significance of MRN complex in repairing meiotic DSBs but also discovers a unique mechanism that recruits MRN complex to SPO11-linked DSB sites.