Microcystins (MCs) pollution is a worldwide environmental issue concerning about human health. Microcystin-leucine-arginine (MC-LR), the most common type of MCs produced by cyanobacteria, could enter the brain and bring about damage to the nervous system. Up to date, it is not clear about the mechanism of MC-LR-induced neurotoxicity. Amyloid-β (Aβ) deposits are hallmark of Alzheimer's disease (AD). In this study, we revealed that MC-LR exposure at environment-related doses (1, 7.5, 15 μg/L) could promote Aβ accumulation in mouse brain. Mechanically, we firstly found that Aβ accumulation is closely associated with abnormal Aβ degradation due to autophagy flux blockade and lysosome dysfunctions in neurons after MC-LR exposure. Moreover, an adverse outcome pathway (AOP) framework oriented to neurotoxicity of MC-LR was conducted in this study. MC-LR inhibited the activity of protein phosphatase 2A (PP2A) in neurons, which is regarded as a molecular initiating event (MIE). In addition, the abnormalities in autophagy were observed after MC-LR exposure. The hindered autophagosome-lysosome fusion and disrupted lysosomal function were key events (KEs) after MC-LR exposure, which contributed to proteostasis dysregulation, ultimately leading to Aβ abnormal degradation and learning deficits as adverse outcomes (AO) of neurotoxicity. This study provided novel information about MC-LR neurotoxicity and new insights into understanding the mechanisms underlying the environmental chemicals-induced neurodegeneration diseases, which has deep implications for public health.

Nanoplastics (NPs) are unavoidable hazardous materials that result from the human production and use of plastics. While there is evidence that NPs can bioaccumulate in the brain, no enough research regarding the pathways by which NPs reach the brain was conducted, and it is also urgently needed to evaluate the health threat to the nervous system. Here, we observed accumulation of polystyrene nanoplastics (PS-NPs) with different surface modifications (PS, PS-COOH, and PS-NH2) in mouse brains. Further studies showed that PS-NPs disrupted the tight junctions between endothelial cells and transport into endothelial cells via the endocytosis and macropinocytosis pathways. Additionally, NPs exposure induced a series of alternations in behavioral tests, including anxiety- and depression-like changes and impaired social interaction performance. Further results identified that NPs could be internalized into neurons and localized in the mitochondria, bringing about mitochondrial dysfunction and a concurrent decline of ATP production, which might be associated with abnormal animal behaviors. The findings provide novel insights into the neurotoxicity of NPs and provide a basis for the formulation of policy on plastic production and usage by relevant government agencies.

Numerous studies have shown microcystins (MCs) inducing male reproductive toxicity, but the underlying mechanisms in humans are unclear. Therefore, this study aimed to evaluate the mediating role of serum sex hormones in the association between MC exposure and semen quality. In this study, we measured the levels of semen MCs and serum sex hormones in Chinese men [sample 1 (n = 649); sample 2 (n = 924)]. The results showed that there was a non-significant dose-dependent relationship between semen MCs and semen volume reduction (p for trend = 0.079) in sample 1, and semen MCs were significantly negatively associated with total motility, progressive motility, curvilinear velocity, mean angular displacement and acrosome integrity (p < 0.05) in sample 2. We also found that semen MCs were significantly positively associated with serum follicle stimulating hormone (FSH) (β = 0.151; 95% CI: 0.065, 0.236), but negatively associated with serum inhibin B (INHB) (β = −0.605; 95% CI: −0.944, −0.265), and these linear associations were confirmed in restricted cubic spline (RCS) models (all p non-linearity > 0.1). Furthermore, mediation analysis revealed that serum INHB mediated 19.86% of the adverse effect of MC exposure on acrosome integrity. In conclusion, this study reveals the mediating roles of serum sex hormones in the relationship between MC exposure and decreased semen quality in men.

Nanoplastics (NPs), regarded as the emerging contaminants, can enter and be mostly accumulated in the digest tract, which pose the potential threat to intestinal health. In this study, mice were orally exposed to polystyrene (PS), PS-COOH and PS-NH2 NPs with the size of ∼100 nm at a human equivalent dose for 28 consecutive days. All three kinds of PS-NPs triggered Crohn's ileitis-like features, such as ileum structure impairment, increased proinflammatory cytokines and intestinal epithelial cell (IEC) necroptosis, and PS-COOH/PS-NH2 NPs exhibited higher adverse effects on ileum tissues. Furthermore, we found PS-NPs induced necroptosis rather than apoptosis via activating RIPK3/MLKL pathway in IECs. Mechanistically, we found that PS-NPs accumulated in the mitochondria and subsequently caused mitochondrial stress, which initiated PINK1/Parkin-mediated mitophagy. However, mitophagic flux was blocked due to lysosomal deacidification caused by PS-NPs, and thus led to IEC necroptosis. We further found that mitophagic flux recovery by rapamycin can alleviate NP-induced IEC necroptosis. Our findings revealed the underlying mechanisms concerning NP-triggered Crohn's ileitis-like features and might provide new insights for the further safety assessment of NPs.

Asthenozoospermia, characterized by poor sperm motility, is a common cause of male infertility. Improving energy metabolism and alleviating oxidative stress through drug regimens are potential therapeutic strategies. In this study, we observed upregulated miR-24-3p levels in asthenozoospermia spermatozoa, contributing to energy metabolism disorder and oxidative stress by reducing GSK3β expression. Thus, reducing miR-24-3p levels using drugs is expected to improve sperm motility. The blood-testis barrier (BTB) protects the testis from xenobiotics and drugs. In this study, we found that Sertoli cell-derived small extracellular vesicles (SC-sEV) can traverse the BTB and enter germ cells. We successfully loaded miR-24-3p inhibitor into SC-sEV, creating the nano-drug SC-sEV@miR-24-3p inhibitor, which effectively delivers miR-24-3p inhibitor into germ cells. In a gossypol-induced mouse asthenozoospermia model, administration of SC-sEV@miR-24-3p inhibitor significantly improved sperm motility, in vitro fertilization success, and blastocyst formation rates. As anticipated, it also improved the litter size of asthenozoospermia mice. These results suggest that SC-sEV@miR-24-3p inhibitor holds promise as a potential clinical treatment for asthenospermia.

Epidemiological studies suggest a global decline in male fertility, which accounts for approximately50% of infertility cases in couples. Male infertility is a multifactorial and complex issue that may arise due to congenital, acquired, idiopathic, or other unknown factors [1] . Microcystins（MCs）, a group of cyanobacterial toxins,

Microcystin-LR (MC-LR) has been identified to pose an increasing threat to the male reproductive system in vivo and in vitro studies with the objects like mammal animals, amphibians, aquatic organisms, etc. This review demonstrates the latest research advances of the male reproductive toxicity induced by MC-LR in detail, which mainly consists of two aspects, namely pathological injuries to testis and prostate, as well as the endocrine disruption. Apart from the direct toxicity to the male reproductive system, we also underline the transgenerational reproductive toxicity that prenatal exposure may pass on to male offspring. This review also demonstrates the interactive effects between MC-LR and other compounds, including synergistic effects with some toxicants and antagonistic effects with some medicine or chemical modification. In terms of the mechanisms of MC-LR-induced toxicity, we mainly focus on the epigenetic modification and non-coding RNAs (ncRNAs)-related mechanisms which have provided a new perspective.

Vol. 129, No. 12 Research LetterOpen AccessAssociation between Semen Microcystin Levels and Reproductive Quality: A Cross-Sectional Study in Jiangsu and Anhui Provinces, China Dihui Xu, Wen Yu, Yuhan Ma, Yang Luo, Guanghui Xu, Zou Xiang, Yabing Chen, and Xiaodong Han Dihui Xu Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China , Wen Yu Department of Andrology, Affiliated Drum Tower Hospital, School of Medicine, Nanjing University, Nanjing, China , Yuhan Ma Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China , Yang Luo Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China , Guanghui Xu Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China , Zou Xiang Department of Health Technology and Informatics, Faculty of Health and Social Sciences, Hong Kong Polytechnic University, Hong Kong, China , Yabing Chen Address correspondence to Xiaodong Han, Immunology and Reproductive Biology Laboratory, Medical School, Nanjing University, Nanjing 210093 China. Telephone: 86-025-83686497. Email: E-mail Address: [email protected] or Yabing Chen, Immunology and Reproductive Biology Laboratory, Medical School, Nanjing University, Nanjing 210093 China. Email: E-mail Address: [email protected] Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China , and Xiaodong Han Address correspondence to Xiaodong Han, Immunology and Reproductive Biology Laboratory, Medical School, Nanjing University, Nanjing 210093 China. Telephone: 86-025-83686497. Email: E-mail Address: [email protected] or Yabing Chen, Immunology and Reproductive Biology Laboratory, Medical School, Nanjing University, Nanjing 210093 China. Email: E-mail Address: [email protected] Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, China Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China Published:1 December 2021CID: 127702https://doi.org/10.1289/EHP9736AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit IntroductionCurrently, male factor infertility is a primary or contributing cause for ∼50% of couples with infertility (Agarwal et al. 2021). In recent years, microcystins (MCs), a group of cyanobacterial toxins, have gained widespread attention given the global worsening of environmental water pollution (Svirčev et al. 2019). MCs exert multiorgan toxicity in both wildlife and humans (Li et al. 2021). Indeed, toxicological studies have found that exposure to MCs can induce male infertility as reviewed by Chen et al. (Chen et al. 2016). Although previous analysis supports the notion that the testis is the second most important target organ of MCs (Chen and Xie 2005), to our knowledge, there have been no epidemiological studies regarding the effects of MCs on male reproductive health. Therefore, we conducted a cross-sectional study to assess the association between MC exposure and male reproductive quality.MethodsMale partners of couples were enrolled at their visit to the Reproductive Medical Center, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China. The study population was heterogeneous, including infertile men and healthy men whose partners suffered from female factor infertility. The criteria for subject selection were minimal: a) being 20–40 y old at the time of recruitment; b) living for over 3 y in the Jiangsu or Anhui area, where frequent water blooms have been observed; and c) no potential occupational exposure to MCs. From June 2020 to January 2021, 2,588 eligible men were invited to join our study and complete the questionnaire under the guidance of a trained nurse. Of the 2,588 men, 873 were excluded as follows: 384 reported that the abstinence time was <2 or >7d; 439 had chromosomal abnormality or experienced inflammation or surgery of the reproductive or urological system, sexually transmitted diseases, azoospermia, or a varicocele; 50 semen samples were missing. Thus, the final sample size was 1,715 in our study. We defined "cigarette smoker" as those individuals who smoked more than one cigarette per day for more than 6 consecutive months. Participants who had quit smoking for less than 6 months prior were still classified as "current smoker." We defined "alcohol drinker" as those who consumed alcohol at least once (or 50 g) per week for more than 6 consecutive months. Participants who had quit drinking for less than 6 months prior were still defined as "current alcohol drinker." Each participant provided a semen sample by masturbation. In addition, a total of 1,251 study participants provided venous blood samples for the measurement of inhibin B (924 samples) and other reproductive hormones [649 samples, including follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), total testosterone (T), and estradiol (E2)], respectively. The work was approved by the Ethical Committee of Drum Tower Hospital affiliated with Nanjing University Medical School. Written informed consent was provided by each participant in this study.MCs contained in the semen samples were examined using an enzyme-linked immunosorbent assay (ELISA) kit (Beacon Analytical Systems, Inc.) as described in a previous study (Zheng et al. 2017). A recovery test with a spiked microcystin standard in semen samples was carried out to verify the validity of the ELISA results. The average recovery was 90.2%, and the relative standard deviation was 13.1%. The semen volume was estimated based on the graduation marks on a semen collector. The sperm concentration, motility and motion parameters were assessed using a BEION S3 computer-aided sperm analysis system (CASA; Beion Medical Technology). Sperm morphology was analyzed using Shorr staining according to the World Health Organization criteria. The DNA fragmentation index (DFI) and high DNA stainability (HDS) were determined using an Accuri C5 Flow Cytometer (Becton Dickinson). Serum inhibin B was measured using an ELISA kit (Kangrun Biotech). Serum FSH, LH, PRL, T, and E2 levels were measured by a chemiluminescence assay using an Atellica Solution system (Siemens).A random forest model was applied to impute concentrations of MCs below the limit of detection (LOD) (0.1μg/L) (Amit and Geman 1997). Available data for the age, body mass index (BMI), and BMI2 of the participants were used as the parameters to impute the concentrations of MCs lower than the LOD. The missing data for baseline characteristics were imputed using the mean or mode. Multivariable linear regression was used to evaluate the changes in semen quality parameters and reproductive hormones across semen MC quartiles. Age, BMI, BMI2, abstinence time, educational level, and smoking and alcohol consumption history were regarded as potential covariates for regression models based on the results of Spearman's rank correlation (range of the absolute value of correlations: 0.001–0.343). A 2-sided p<0.05 was considered statistically significant. Because of the exploratory nature of this analysis, p<0.1 was considered statistically suggestive. We used Python (version 3.7; Python Software Foundation) for the random forest model and SPSS (version 20.0; SPSS Inc.) for all other statistical analyses.Results and DiscussionThe participants were of a mean age of 30.8 y old and had a mean BMI of 24.73kg/m3 (Table 1). The distributions of the semen quality parameters, reproductive hormone levels and semen MC levels are also listed in Table 1. The semen quality in our study population was similar to that in other populations (Toft et al. 2012). Semen MC quartiles were negatively associated with the total sperm count (p for trend=0.033) (Table 2). A previous study demonstrated that MC-LR could reduce epididymal sperm counts in mice (Chen et al. 2016). We found a suggestive association between MC levels and semen volume (p for trend=0.054). Sperm concentration was not significantly associated with MC exposure. Therefore, the decrease in the total sperm count may have been due to the MC-induced reduction of the semen volume, but not of the sperm concentration in men. For total motility, progressive motility, curvilinear velocity (VCL) and the frequency of the sperm with a normal morphology, negative trends were observed across MC quartiles (p for trend=0.010, 0.010, 0.026, and 0.008, respectively). Moreover, MC quartiles were associated with increases in the frequency of head abnormalities (p for trend=0.016). These results support the hypothesis that MCs might be toxins that could compromise the vitality and morphology of the sperm. Our findings are consistent with those of previous animal studies that showed that MC-LR reduced sperm motility while increased the percentage of abnormal sperm in rodents (Chen et al. 2016).Table 1 Demographics, reproductive quality parameters, and semen MC levels of the study participants in Jiangsu and Anhui provinces, China, from June 2020 to January 2021.Table 1 has five columns, namely, Variables begin superscript lowercase a end superscript, Uppercase n, Mean plus or minus Standard deviation, Median (fifth, ninety-fifth), and lowercase n (percentage).VariablesanMean±SDMedian (5th, 95th)n (%)Age (y)1,71530.8±3.831.0 (25.0, 38.0)—BMI (kg/m2)1,70824.73±3.7524.49 (19.03, 31.14)—Abstinence time (d)1,715——— 2–4———1,058 (61.7) 5–7———657 (38.3)Educational level1,714——— Junior and below———382 (22.3) Senior and above———1,332 (77.7)Income (yuan per person per year)1,685——— 20,000 and below———224 (13.3) 20,000–50,000———491 (29.1) 50,000 and above———970 (57.6)Smoking history1,714——— Current———802 (46.8) Never———738 (43.1) Ever———174 (10.2)Alcohol consumption history1,711——— Current———504 (29.5) Never———1,010 (59.0) Ever———197 (11.5)Tea/coffee consumption1,715——— Yes———1,300 (75.8) No———415 (24.2)Semen parameter————Semen volume (mL)1,7153.5±1.43.2 (1.8, 6.0)—Sperm concentration (106/mL)1,71567.5±50.756.6 (9.4, 160.2)—Total sperm count (106)1,715225.2±180.4183.7 (28.1, 548.6)—Total motility (%)1,71548.0±20.049.1 (14.0, 79.4)—Progressive motility (%)1,71537.4±18.137.3 (7.9, 67.2)—Curvilinear velocity (μm/s)1,71542.5±9.642.7 (27.9, 56.5)—Straight-line velocity (μm/s)1,71519.1±4.919.2 (11.3, 26.6)—Morphologically normal (%)1,7155.7±3.15.5 (0.9, 10.9)—Abnormal head (%)1,71593.5±3.493.2 (88.2, 99.1)—Abnormal midpiece (%)1,71510.3±1.810.0 (7.7, 13.2)—Abnormal tail (%)1,7159.7±2.19.5 (6.8, 13.6)—DNA fragmentation index (%)1,13417.11±10.0514.99 (5.92, 36.83)—High DNA stainability (%)1,1344.79±4.223.25 (1.33, 14.22)—Reproductive hormone————FSH (mIU/mL)6494.68±2.414.20 (1.92, 9.24)—LH (mIU/mL)6493.42±1.713.14 (1.38, 6.46)—PRL (μg/L)6498.78±4.337.87 (4.08, 16.31)—T (nmol/L)64911.46±5.2210.41 (4.83, 21.34)—E2 (pmol/L)649137.06±37.93133.81 (85.50, 212.20)—Inhibin B (pg/mL)924156±59.30150.48 (78.47, 260.74)—MCs (μg/L)b1,7150.16±0.070.16 (0.20. Quartile 1 was used as a reference group. The concentrations of MCs below the LOD were imputed with the random forest model. The missing data for BMI were imputed with mean. The missing data for smoking history, alcohol consumption history and educational levels were imputed with mode. Estimates calculated using multiple linear regression models were adjusted for age, BMI and BMI2 (continuous), abstinence time (2–4 d vs. 5–7 d), smoking history (current, former, and never), alcohol consumption history (current, former, and never), and educational level (junior high school and below vs. senior high school and above). The test for trend was performed by entering the median value of each quartile of semen MC levels as a continuous variable in the models. —, no data available; CI, confidence interval; DFI, DNA fragmentation index; HDS, high DNA stainability; VCL, curvilinear velocity; VSL, straight-line velocity.aSemen volume, sperm concentration, total sperm count, and inhibin B were square root-transformed. DFI, HDS, FSH, LH, PRL, T, and E2 were ln-transformed. Other parameters were not transformed.MC quartiles were found to be positively associated with the FSH levels (p for trend=0.001) but negatively associated with the inhibin B levels (p for trend=0.005) in this study. A previous study has also reported that increased FSH and decreased inhibin B levels were observed in infertile men (Meachem et al. 2001). Therefore, MCs might induce male infertility by disrupting the functionality of the two hormones. In addition, the association between semen MC levels and LH, PRL, T, or E2 levels in serum was not found in this study. However, increased LH and decreased T levels were previously observed in male mice following exposure to MC-LR (Chen et al. 2016). Moreover, MC-LR induced an increase in E2 levels in male zebrafish in a dose-dependent manner (Lin et al. 2018). The discrepancy between our findings in an epidemiological study and previous animal models can possibly be explained by species specificity, lower exposure levels by humans, or other factors. Of note, MCs can impair the synthesis of reproductive hormones via disrupting the hypothalamic–pituitary–gonadal (HPG) axis (Lin et al. 2018), in addition to damaging the testis. Therefore, the relationship between reproductive hormones and MC levels in other body fluids, such as cerebrospinal fluid, is worth further investigation.We measured MC levels in semen, which might present a more direct metric to assess the impacts of MCs on male reproductive health than that in urine or serum. Furthermore, we carried out comprehensive measurements using a relatively large sample size with strict exclusion criteria. However, there were also several limitations. First, we did not establish the relation between serum MCs and semen MCs, because toxins are transported by blood. Second, we did not consider the impact of potential exposure to other environmental pollutants, such as chemicals, secondhand smoke, and traffic exhaust. Third, further studies are required to determine whether our findings are generalizable to other populations, because all the study subjects were selected from those who visited just one reproductive medical center.In conclusion, this is the first epidemiological investigation, to our knowledge, to evaluate the toxicity of MCs on reproductive quality in men. Our data suggested that semen MC levels were significantly associated with various male reproductive quality parameters. Given the widespread cyanobacterial pollution globally, our study can provide a reference for raising the awareness of the necessity of water bloom control.AcknowledgmentsThe authors thank the staff at the Andrology Laboratory, the Affiliated Drum Tower Hospital of Nanjing University Medical School for measuring semen quality parameters. The authors also thank K. He and K. Chen from Nanjing University for their advice on the use of the random forest regression model. This work was supported by the National Natural Science Foundation of China (31901182; 31870492), Fundamental Research Funds for the Central Universities (0214-14380471), and the Natural Science Foundation of Jiangsu Province of China (BK20190316).ReferencesAgarwal A, Baskaran S, Parekh N, Cho CL, Henkel R, Vij S, et al.2021. Male infertility. Lancet 397(10271):319–333, PMID: 33308486, 10.1016/S0140-6736(20)32667-2. Crossref, Medline, Google ScholarAmit Y, Geman D. 1997. Shape quantization and recognition with randomized trees. Neural Comput 9(7):1545–1588, 10.1162/neco.1997.9.7.1545. Crossref, Google ScholarChen J, Xie P. 2005. Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in two freshwater shrimps, Palaemon modestus and Macrobrachium nipponensis, from a large shallow, eutrophic lake of the subtropical China. Toxicon 45(5):615–625, PMID: 15777958, 10.1016/j.toxicon.2005.01.003. 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Crossref, Medline, Google ScholarThe authors declare they have no actual or potential competing financial interests.FiguresReferencesRelatedDetails Vol. 129, No. 12 December 2021Metrics About Article Metrics Publication History Manuscript received30 May 2021Manuscript revised21 September 2021Manuscript accepted5 November 2021Originally published1 December 2021 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. 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There is a growing concern regarding the toxic effects of nanoplastics (NPs) on aquatic and marine organism, while relatively few studies about their toxicity evaluation on mammals are conducted. In the present study, we observed accumulation of polystyrene NPs (PS NPs) in mice spleen, lung, kidney, small intestine, large intestine, testis, and brain after oral exposure to PS NPs (~100 nm, 10 mg/mL, 100 μL) for 28 days, and NPs were identified to induce cell apoptosis, inflammation, and structure disorder in these tissues. We also found that PS NPs could bring about hematological system injury and lipid metabolism disorder. Further in vitro studies identified that PS NPs could be absorbed by the intestinal epithelial Caco-2 cells by macropinocytosis and clathrin-mediated endocytosis, and induced disruption of tight junction between Caco-2 cells. Moreover, we found that it was easier for PS-NH2 and PS-COOH to enter into Caco-2 cells, which may be associated with observed stronger toxicity of PS-NH2 and PS-COOH NPs. In summary, this study demonstrated that NPs exposure brings about toxic effects to mice. This study could provide new insights regarding the distribution of NPs in humans, and helps us to evaluate the potential physiological risks of NPs to human beings.

It has been reported that microcystin-leucine-arginine (MC-LR) can enter into the brain and demonstrate neurotoxicity resulting in learning and memory deficits. While, there is still a lack of clear understanding of the related molecular mechanisms. In this study, we observed β-amyloid (Aβ) accumulation and tau hyperphosphorylation (p-tau) at sites of Ser396 and Thr205 in mouse hippocampus and cortex, Alzheimer's disease (AD) like changes, after chronic exposure to MC-LR at different concentrations (1, 7.5, 15 and 30 μg/L) for 180 days. The hallmarks of AD are characterized by senile plaques and neurofibrillary tangles (NFT), with associated loss of neurons, resulting in cognitive impairment and dementia. Similarly, the production of Aβ and tau hyperphosphorylation was also detected in HT-22 cells treated with MC-LR. In addition, MC-LR promoted increased expressions of BACE1 and PS1, but reduced mRNA expressions of ADAM family members both in vivo and in vitro, promoting the Aβ production. Moreover, we identified Akt/GSK-3β signal pathway mediated the Aβ and p-tau accumulation, bringing about Alzheimer's disease-like changes. Furthermore, microglial cells were activated in those mice exposed to MC-LR. Inflammatory cytokines were also found being activated to release in vitro. In conclusion, this study could provide a clue for MC-LR-induced neurotoxicity, which gave insights into the environmental risks of Alzheimer's disease.

Background: Since primary prostate cancer (PCa) can advance to the life-threatening metastatic PCa, exploring the molecular mechanisms underlying PCa metastasis is crucial for developing the novel targeted preventive strategies for decreasing the mortality of PCa. RNA N6-methyladenosine (m6A) is an emerging regulatory mechanism for gene expression and its specific roles in PCa progression remains elusive. Methods: Western blotting, quantitative real-time PCR and immunohistochemical analyses were used to detect target gene expression in PCa cells in vitro and prostate tissues from patients. RNA immunoprecipitation was conducted to analyze the specific binding of mRNA to the target protein. Migration and invasion assays were used to assess the migratory capacities of cancer cells. The correlation between target gene expression and survival rate of PCa patients was analyzed based the TCGA database. Results: We found that total RNA N6-methyladenosine (m6A) modification levels were markedly upregulated in human PCa tissues due to increased expression of methyltransferase like 3 (METTL3). Further studies revealed that the migratory and invasive capacities of PCa cells were markedly suppressed upon METTL3 knockdown. Mechanistically, METTL3 mediates m6A modification of USP4 mRNA at A2696, and m6A reader protein YTHDF2 binds to and induces degradation of USP4 mRNA by recruiting RNA-binding protein HNRNPD to the mRNA. Decrease of USP4 fails to remove the ubiquitin group from ELAVL1 protein, resulting in a reduction of ELAVL1 protein. Lastly, downregulation of ELAVL1 in turn increases ARHGDIA expression, promoting migration and invasion of PCa cells. Conclusions: Our findings highlight the role of METTL3 in modulating invasion and metastasis of PCa cells, providing insight into promising therapeutic strategies for hindering PCa progressing to deadly metastases.

Microcystin-leucine-arginine (MC-LR) has been identified to be a hazardous material to cause hepatotoxicity. In this study, mice were exposed to MC-LR dissolved in drinking water at doses of 1, 10, 20 and 30 μg/L for 90 and 180 days, respectively. We validated MC-LR accelerated spermatid exfoliation and caused large vacuoles in testes, reducing sperm count and increasing percentage of morphologically abnormal sperm. Furthermore, we found MC-LR induced the apical ectoplasmic specialization (ES) disassembly by disrupting F-actin organization. Further studies identified that downregulation of Palladin, the actin crosslinking protein, might be associated with disassembly of the apical ES in mice testis following MC-LR exposure. We also confirmed that MC-LR disrupted the interaction between Palladin and other actin-related proteins and thus impeded the F-actin organization. Additionally, we found that autophagy initiated by AMPK/ULK1 signaling pathway mediated the degradation of Palladin in Sertoli cells challenged with MC-LR. Following exposure to MC-LR, reduced PP2A activity and upregulated expression of LKB1 and CAMKK2 could activate AMPK. In conclusion, these results revealed MC-LR induced the degradation of Palladin via AMPK/ULK1-mediated autophagy, which might result in the apical ES disorder and spermatid exfoliation from spermatogenic epithelium. Our work may provide a new perspective to understand MC-LR-induced male infertility.