Muscone inhibits the progression of atherosclerotic plaques in mice aorta by inhibiting the NF-κB/p65 pathway.

Atherosclerosis (AS) is considered to be one of the main pathogenic factors of coronary heart disease, cerebral infarction and peripheral vascular disease. Oxidative stress and inflammation run through the occurrence and development of atherosclerosis and related cardiovascular events. Muscone is a natural extract of deer musk and also the main physiological active substance of musk. This study investigated the impact of muscone on atherosclerosis. ApoE-/- mice were used to establised AS model and injected with low-dose (4 mg/kg/day) or high-dose (8 mg/kg/day) of muscone intraperitoneally for 4 weeks. Then aortic tissues were collected, and pathological sections of the aorta were prepared for oil red staining, HE and masson staining. The changes of MDA, SOD, VCAM-1, NF-κB, and TNF-α were observed by Western blotting or immunofluorescence staining. The results showed that high-dose muscone could effectively reduce the plaque area/aortic root area and relative atherosclerotic area, reduce the collagen composition in plaque tissue. In addition, we also found that high-dose muscone can effectively increase MDA level, reduce the level of SOD, and inhibit the expression of VCAM-1, NF-κB/p65, TNF-α in arterial plaques. Our results indicate that the administration of muscone has the benefit of inhibiting atherosclerosis. The potential mechanisms may be associated with antioxidant effect and inhibition of inflammatory reaction in arterial plaques. With the increasing understanding of the relationship between muscone and atherosclerosis, muscone has high potential value as a new drug to treat atherosclerosis.

METTL14 promotes doxorubicin-induced cardiomyocyte ferroptosis by regulating the KCNQ1OT1-miR-7-5p-TFRC axis.

Doxorubicin (DOX) has toxic effects on the heart, causing cardiomyopathy and heart injury, but the underlying mechanisms of these effects require further investigation. This study investigated the role of DOX in promoting ferroptosis to induce myocardial injury. AC16 cardiomyocyte and neonatal rat ventricle cardiomyocytes were used as an in vitro model to study the molecules involved in myocardial injury using gene silencing, ectopic expression, and RNA immunoprecipitation. Messenger RNA and protein level analyses showed that DOX treatment resulted in the upregulation of methyltransferase-like 14 (METTL14), which catalyzes the m6A modification of the long non-coding RNA KCNQ1OT1, a miR-7-5p sponge. The RNA-binding protein IGF2BP1 is associated with KCNQ1OT1 to increase its stability and robustly inhibit miR-7-5p activity. Furthermore, a lack of miR-7-5p expression led to increased levels of transferrin receptor, promoting the uptake of iron and production of lipid reactive oxygen species and demonstrating that DOX-induced ferroptosis occurs in AC16 cells. Additionally, we found that miR-7-5p targets METTL14 in AC16 cells. Meanwhile, the role of METTL14/KCNQ1OT1/miR-7-5p axis in regulating ferroptosis in neonatal rat ventricle cardiomyocytes was also confirmed. Our results indicate that selectively inhibiting ferroptosis mediated by a METTL14/KCNQ1OT1/miR-7-5p positive feedback loop in cardiomyocytes could provide a new therapeutic approach to control DOX-induced cardiac injury.

Perfluorooctane sulfonate promotes hepatic lipid accumulation and steatosis in high-fat diet mice through AMP-activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC) pathway.

Perfluorooctane sulfonate (PFOS) is a hepatotoxic environmental organic pollutant that can cause aberrant lipid accumulation in the liver. However, the molecular mechanism underlying PFOS-induced hepatic steatosis remains unclear. Our research showed that subchronic PFOS exposure inhibited AMP-activated protein kinase (AMPK) phosphorylation, leading to increased acetyl-CoA carboxylase (ACC) activity, attenuated fatty acid ß-oxidation, and consequent liver lipid accumulation. We found that 1 mg/kg/day PFOS exposure significantly aggravated steatosis in high-fat diet (HFD)-fed mice, along with reduced AMPK activity. Oil Red O results showed that PFOS exposure caused fat accumulation in HepG2 cells. As predicted, PFOS treatment reduced the level of phosphorylated AMPK in a concentration-dependent manner, leading to subsequent increase in ACC activity and lipid droplet accumulation in HepG2 cells. Treatment with 200-µM AMPK agonist AICAR alleviated PFOS-induced ACC activation and lipid accumulation. In summary, our data highlight a crucial role of AMPK/ACC pathway in PFOS-mediated liver lipid metabolic disorders.

PFOS facilitates liver inflammation and steatosis: An involvement of NLRP3 inflammasome-mediated hepatocyte pyroptosis.

Perfluorooctane sulfonate (PFOS) is a fluorinated organic pollutant with substantial accumulation in mammalian liver tissues. However, the impact of chronic PFOS exposure on liver disease progression and the underlying molecular mechanisms remain elusive. Herein, we for the first time revealed that micromolar range of PFOS exposure initiates the activation of NLR pyrin domain containing 3 (NLRP3) inflammasome to drive hepatocyte pyroptosis. We showed that 5 mg/kg/day PFOS exposure may exacerbated liver inflammation and steatosis in high-fat diet (HFD)-fed mice with concurrently elevated expression of NLRP3 and caspase-1. PFOS exposure resulted in viability impairment and LDH release in BRL-3A rat liver cells. 25-100 µM concentrations of PFOS exposure activated the NLRP3 inflammasome, leading to consequent GSDMD cleavage, IL-1ß release and the initiation of pyroptosis in a dose-dependent manner, whereas treatment with 10 µM NLRP3 inhibitor MCC950 abrogated this effect. Moreover, pretreatment of 5 mM ROS scavenger N-acetyl-L-cysteine (NAC) ameliorated PFOS-induced NLRP3 inflammasome activation and pyroptosis. Collectively, our data highlight a pivotal role of pyroptotic death in PFOS-mediated liver inflammation and metabolic disorder.

Perfluorooctane sulfonate aggravates CCl4-induced hepatic fibrosis via HMGB1/TLR4/Smad signaling.

Perfluorooctane sulfonate (PFOS) is a widespread environmental pollutant and may cause a variety of adverse health effects. The hepatotoxicity of PFOS has attracted particular attention, given the fact that the liver has one of the highest PFOS accumulations among human tissues. In this study, we revealed that subchronic PFOS exposure may exacerbate carbon tetrachloride (CCl4 )-induced liver fibrosis in animal models. Administration with 1 mg/kg PFOS every other day for 56 days dramatically enhanced CCl4 -mediated liver injury and hepatic stellate cell (HSC) activation. Furthermore, PFOS exposure may promote the activation of high-mobility group box 1 (HMGB1)/toll-like receptor 4 (TLR4) signaling pathway through inducing the secretion of HMGB1 from hepatocytes. PFOS exposure induced the translocation of HMGB1 from the nucleus into the cytoplasm of hepatocytes and cultured BRL-3A cells at a starting concentration of 50 µM. This process is accompanied with concurrent flux of calcium, suggesting a link between calcium signaling and HMGB1 release following PFOS exposure. Finally, we showed that PFOS-exposed conditional medium (PFOS-CM) of hepatocytes may induce the translocation of Smad2/3 in HSCs in a TLR4-dependent manner. Taken together, subchronic PFOS exposure might play a pro-fibrotic role via a HMGB1/TLR4-dependent Smad signaling in HSCs. Our findings for the first time uncovered an involvement of PFOS exposure in liver fibrosis via HMGB1/TLR4/Smad signaling.

Scaling Up Human Immunodeficiency Virus Screening and Antiretroviral Therapy Among Men Who Have Sex With Men to Achieve the 90-90-90 Targets in China.

INTRODUCTION: The Joint United Nations Programme on human immunodeficiency virus (HIV)/acquired immune deficiency syndrome has proposed the 90-90-90 targets by 2020. Human immunodeficiency virus epidemic is spreading rapidly among men who have sex with men (MSM) in China. This study investigates how the scale-up of HIV testing and treatment in achieving the targets and its cost-effectiveness. METHODS: We constructed a compartmental model to forecast the HIV epidemic in Chinese MSM based on various "test-and-treat" scale-up scenarios. We assessed their cost effectiveness based on the cost for each HIV infection, death, and disability-adjusted life years (DALYs) prevented by the scale-up. RESULTS: If the current epidemic continued, HIV prevalence among Chinese MSM would increase from 9.2% in 2016 to 12.6% (9.2-15.6%) in 2020 and 16.2% (11.3-20.0%) in 2025. By 2020, 49.2% of infected MSM would be diagnosed and 40.1% of whom on treatment, falling short of the 90-90-90 targets, so would be even by 2025. To achieve these targets by 2020, additional 850,000 HIV screening tests and 112,500 person-years of antiretroviral treatment (ART) annually are necessary. This spending is US $478 million during 2016 to 2020, which almost tripled the status quo. However, by delaying to 2025, an investment of US $1210 million over 2016 to 2025 corresponding to 52% increase to the status quo, will enable extra 340,000 HIV screening tests and 60,000 person-year on ART annually. In both scenarios, the incremental cost-effectiveness ratio was US $733 to 960 for each DALY prevented, indicating highly cost-effective scenarios. CONCLUSIONS: Achieving the 90-90-90 targets by 2020 requires steep increase in investment, but delaying the targets to 2025 is practical and cost-effective.

Nrf2 Signaling Elicits a Neuroprotective Role Against PFOS-mediated Oxidative Damage and Apoptosis.

Perfluorooctanesulfonate (PFOS) may cause neurotoxicity through the initiation of oxidative stress. In the current study, we investigated the role of anti-oxidant nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in PFOS-induced neurotoxicity. We found that human neuroblastoma SH-SY5Y cells exhibited significant apoptotic cell death following PFOS exposure, and this process was accompanied with apparent accumulation of reactive oxidative species (ROS). In addition, we revealed that PFOS exposure caused marked activation of Nrf2 pathway and the expression of Nrf2 transcription target heme oxygenase-1. We further found that pre-treatment with ROS scavenger N-acetyl-L-cysteine (NAC) dramatically ameliorated PFOS-induced ROS production and Nrf2 signaling. In keeping with these findings, western blot and Cell Counter Kit-8 analyses revealed that pre-incubation with NAC suppressed PFOS-induced expression of pro-apoptotic proteins and impairment of neuronal viability. Moreover, antagonizing Nrf2 pathway with Nrf2 inhibitor brusatol resulted in increased ROS production and enhanced PFOS-induced expression of apoptosis related proteins. Finally, we showed that PFOS exposure altered mitochondrial transmembrane potential and disrupted normal mitochondrial morphology in SH-SY5Y cells. Whereas treatment with NAC ameliorated PFOS-induced mitochondrial disorders, co-incubation with brusatol augmented PFOS-induced mitochondrial deficits, consequently contributing to neuronal apoptosis. These results manifest that Nrf2 pathway plays a protective role in PFOS-induced neurotoxicity, providing new insights into the prevention and treatment of PFOS-related toxicities.

A Global Estimate of the Acceptability of Pre-exposure Prophylaxis for HIV Among Men Who have Sex with Men: A Systematic Review and Meta-analysis.

Pre-exposure prophylaxis (PrEP) is a new biomedical intervention for HIV prevention. This study systematically reviews the acceptability of PrEP among men who have sex with men (MSM) worldwide. We searched major English databases to identify English-language articles published between July 2007 and July 2016, which reported the acceptability of PrEP and associated population characteristics. Meta-analysis was conducted to estimate a pooled acceptability, and meta-regression and subgroup analysis were used to analyse heterogeneities. The estimated acceptance from included sixty-eight articles was 57.8% (95% confidence internal 52.4-63.1%). MSM who were younger (4/5 studies, range of adjusted odds ratio (aOR) = 1.39-3.47), better educated (aOR = 1.49-7.70), wealthier (aOR = 1.31-13.03) and previously aware of PrEP (aOR = 1.33-3.30) showed significantly higher acceptance. Male sex workers (84.0% [26.3-98.7%] were more likely to accept PrEP than general MSM. Self-perceived low efficacy, concern about side effects, adherence, affordability, and stigma were main barriers. This review identifies a moderate acceptability of PrEP in MSM. Efficacy, perception of HIV risk and experienced stigma determine its acceptance.

Arsenic trioxide mediates HAPI microglia inflammatory response and subsequent neuron apoptosis through p38/JNK MAPK/STAT3 pathway.

Arsenic is a widely distributed toxic metalloid all over the world. Inorganic arsenic species are supposed to affect astrocytic functions and to cause neuron apoptosis in CNS. Microglias are the key cell type involved in innate immune responses in CNS, and microglia activation has been linked to inflammation and neurotoxicity. In this study, using ELISA, we showed that Arsenic trioxide up-regulated the expression and secretion of IL-1ß in a dose-dependent manner and a time-dependent manner in cultured HAPI microglia cells. The secretion of IL-1ß caused the apoptosis of SH-SY5Y. These pro-inflammatory responses were inhibited by the STAT3 blocker, AG490 and P38/JNK MAPK blockers SB202190, SP600125. Further, Arsenic trioxide exposure could induce phosphorylation and activation of STAT3, and the translocation of STAT3 from the cytosol to the nucleus in this HAPI microglia cell line. Thus, the STAT3 signaling pathway can be activated after Arsenic trioxide treatment. However, P38/JNK MAPK blockers SB202190, SP600125 also obviously attenuated STAT3 activation and transnuclear transport induced by Arsenic trioxide. In concert with these results, we highlighted that the secretion of IL-1ß and STAT3 activation induced by Arsenic trioxide can be mediated by elevation of P38/JNK MAPK in HAPI microglia cells and then induced the toxicity of neurons.

Arsenic trioxide mediates HAPI microglia inflammatory response and the secretion of inflammatory cytokine IL-6 via Akt/NF-κB signaling pathway.

Arsenic is a widely distributed toxic metalloid in around the world. Inorganic arsenic species are deemed to affect astrocytes functions and to cause neuron apoptosis. Microglia are the key cell type involved in innate immune responses in CNS, and microglia activation has been linked to inflammation and neurotoxicity. In this study, using ELISA and reverse transcriptase PCR (RT-PCR), we showed that Arsenic trioxide up-regulated the expression and secretion of IL-6 in a dose-dependent manner and a time-dependent manner in cultured HAPI microglia cells. These pro-inflammatory responses were inhibited by the Akt blocker, LY294002. Further, Arsenic trioxide exposure could induce phospho rylationand degradation of IкBα, and the translocation of NF-κB p65 from the cytosol to the nucleus in this HAPI microglia cell line. Thus, the NF-кB signaling pathway can be activated after Arsenic trioxide treatment. Besides, Akt blocker LY294002 also obviously attenuated NF-кB activation and transnuclear induced by Arsenic trioxide. In concert with these results, we highlighted that the secretion of pro-inflammatory cytokine and NF-кB activation induced by Arsenic trioxide can be mediated by elevation of p-Akt in HAPI microglia cells.

Perfluorooctane sulfonate (PFOS) impairs the proliferation of C17.2 neural stem cells via the downregulation of GSK-3ß/ß-catenin signaling.

The neurotoxic effects of perfluorooctane sulfonate (PFOS) have attracted significant research attention in recent years. In the present study, we investigated the impact of PFOS exposure on the physiology of neural stem cells (NSCs) in vitro. We showed that PFOS exposure markedly attenuated the proliferation of C17.2 neural stem cells in both dose- and time-dependent manners. Additionally, we found that PFOS decreased Ser9 phosphorylation of glycogen synthase kinase-3ß (pSer9-GSK-3ß), leading to the activation of GSK-3ß and resultant downregulation of cellular ß-catenin. Furthermore, blockage of GSK-3ß with lithium chloride significantly attenuated both the PFOS-induced downregulation of GSK-3ß/ß-catenin and the proliferative impairment of C17.2 cells. Notably, the expression of various downstream targets was altered accordingly, such as c-myc, cyclin D1 and survivin. In conclusion, the present study demonstrated that PFOS decreased the proliferation of C17.2 cells via the negative modulation of the GSK-3ß/ß-catenin pathway. We present the potential mechanisms underlying the PFOS-induced toxic effects on NSCs to provide novel insights into the neurotoxic mechanism of PFOS. Copyright © 2016 John Wiley & Sons, Ltd.

2,3,7,8-tetrachlorodibenzo-p-dioxin exposure influence the expression of glutamate transporter GLT-1 in C6 glioma cells via the Ca(2+) /protein kinase C pathway.

The widespread environmental contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is considered one of the most toxic dioxin-like compounds. Although epidemiological studies have shown that TCDD exposure is linked to some neurological and neurophysiological disorders, the underlying mechanism of TCDD-mediated neurotoxicity has remained unclear. Astrocytes are the most abundant cells in the nervous systems, and are recognized as the important mediators of normal brain functions as well as neurological, neurodevelopmental and neurodegenerative brain diseases. In this study, we investigated the role of TCDD in regulating the expression of glutamate transporter GLT-1 in astrocytes. TCDD, at concentrations of 0.1-100 nm, had no significantly harmful effect on the viability of C6 glioma cells. However, the expression of GLT-1 in C6 glioma cells was downregulated in a dose- and time-dependent manner. TCDD also caused activation of protein kinase C (PKC), as TCDD induced translocation of the PKC from the cytoplasm or perinuclear to the membrane. The translocation of PKC was inhibited by one Ca(2+) blocker, nifedipine, suggesting that the effects are triggered by the initial elevated intracellular concentration of free Ca(2+) . Finally, we showed that inhibition of the PKC activity reverses the TCDD-triggered reduction of GLT-1. In summary, our results suggested that TCDD exposure could downregulate the expression of GLT-1 in C6 via Ca(2+) /PKC pathway. The downregulation of GLT-1 might participate in TCDD-mediated neurotoxicity. Copyright © 2016 John Wiley & Sons, Ltd.

Autophagy potentially protects against 2,3,7,8-tetrachlorodibenzo-p-Dioxin induced apoptosis in SH-SY5Y cells.

The environmental toxicant TCDD may elicit cytotoxic effects by inducing reactive oxygen species (ROS) generation. Autophagy is one of the first lines of defense against oxidative stress damage. Herein, we investigated whether autophagy played a regulatory role in TCDD-induced neurotoxicity. Here, we showed that TCDD exposure caused marked autophagy in SH-SY5Y cells, whose dose range was close to that inducing apoptosis. Electron microscopic and Western blot analyses revealed that TCDD induced autophagy at a starting dose of approximate 100 nM. Interestingly, 100-200 nM TCDD exposure resulted in obviously decreased cell viability and evident apoptotic phenotype. Furthermore, the levels of pro-apoptotic molecules, Bax and cleaved-PARP, increased significantly, whereas Bcl2 declined after exposed to 100 nM TCDD. In addition, the apoptosis was verified using flow cytometrical analysis. These data strongly suggested that TCDD induced both autophagy and apoptosis at a similar dose range in SH-SY5Y cells. Interestingly, pretreatment with ROS scavenger, N-acetyl-cysteine (NAC), could effectively block both TCDD-induced apoptosis and autophagy. More surprisingly, inhibition of autophagy with 3-methyladenine (3MA), remarkably augmented TCDD-induced apoptosis. The findings implicated that the onset of autophagy might serve as a protective mechanism to ameliorate ROS-triggered cytotoxic effects in human SH-SY5Y neuronal cells under TCDD exposure. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1068-1079, 2016.

Zinc deficiency impairs the renewal of hippocampal neural stem cells in adult rats: involvement of FoxO3a activation and downstream p27(kip1) expression.

Zinc plays an important role in the development and maintenance of central neural system. Zinc deficiency has been known to alter normal brain function, whose molecular mechanism remains largely elusive. In the present study, we established a zinc deficiency-exposed rat model, and, using western blot and immunohistochemical analyses, found that the expression of FoxO3a and p27(kip1) was remarkably up-regulated in the rat brain hippocampus. Immunofluorescence assay showed that FOXO3a and p27(kip1) were significantly co-localized with nestin, the marker of neural stem cells (NSCs). Furthermore, we identified that the proportion of proliferating NSCs was markedly decreased in zinc-deficient rat hippocampaus. Using C17.2 neural stem cells, it was revealed that exposure to zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethy) ethylenediamine induced the expression of FoxO3a and p27(kip1) , which coincided with reduced NSC proliferation. Furthermore, depletion of FoxO3a inhibited p27(kip1) expression and restored the growth of NSCs. On the basis of these data, we concluded that FoxO3a/p27(kip1) signaling might play a significant role in zinc deficiency-induced growth impairment of NSCs and consequent neurological disorders. We describe here that zinc deficiency induces the proliferative impairment of hippocampal neural stem cells partially through the activation of FOXO3a-p27 axis in rats. Neural progenitor cells exhibited significantly up-regulated expression of FOXO3a and p27 after zinc deficiency in vivo and in vitro. Depletion of FOXO3a ameliorates zinc deficiency-induced expression of p27 and growth impairment of neural stem cells. We provide novel insight into the mechanisms underlying zinc deficiency-induced neurological deficits.

Critical Role of TAK1-Dependent Nuclear Factor-κB Signaling in 2,3,7,8-Tetrachlorodibenzo-p-dioxin-induced Astrocyte Activation and Subsequent Neuronal Death.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been recently shown to elicit inflammatory response in a number of cell-types. However, whether TCDD could provoke inflammation in astrocytes, the most abundant glial cells in central nervous system (CNS), remains virtually unknown. In the present study, we showed that TCDD exposure could induce evident astrocyte activation both in vivo and in vitro. Further, we found that TGF-ß-activated kinase 1 (TAK1), a critical regulator of NF-κB signaling, was rapidly phosphorylated in the process of TCDD-induced reactive astroglia. Exposure to TCDD led to rapid TAK1 and NF-κB p65 phosphorylation, as well as IKBα degradation. Moreover, blockage of TAK1 using siRNA oligos or TAK1 inhibitor 5Z-7-oxozeaenol significantly attenuated TCDD-induced astrocyte activation as well as the release of TNF-α. Finally, we showed that the conditioned medium of TCDD-treated astrocytes promoted the apoptosis of PC12 neuronal cells, which could be blocked with the pre-treatment of TAK1 inhibitor. Taken together, these findings suggested that TCDD could promote the inflammatory activation of astrocytes through modulating TAK1-NF-κB cascade, implicating that reactive astrocytes might contribute to TCDD-induced adverse effects on CNS system.

2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin induces premature senescence of astrocytes via WNT/ß-catenin signaling and ROS production.

2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous environmental contaminant that could exert significant neurotoxicity in the human nervous system. Nevertheless, the molecular mechanism underlying TCDD-mediated neurotoxicity has not been clarified clearly. Herein, we investigated the potential role of TCDD in facilitating premature senescence in astrocytes and the underlying molecular mechanisms. Using the senescence-associated ß-galactosidase (SA-ß-Gal) assay, we demonstrated that TCDD exposure triggered significant premature senescence of astrocyte cells, which was accompanied by a marked activation of the Wingless and int (WNT)/ß-catenin signaling pathway. In addition, TCDD altered the expression of senescence marker proteins, such as p16, p21 and GFAP, which together have been reported to be upregulated in aging astrocytes, in both dose- and time-dependent manners. Further, TCDD led to cell-cycle arrest, F-actin reorganization and the accumulation of cellular reactive oxygen species (ROS). Moreover, the ROS scavenger N-acetylcysteine (NAC) markedly attenuated TCDD-induced ROS production, cellular oxidative damage and astrocyte senescence. Notably, the application of XAV939, an inhibitor of WNT/ß-catenin signaling pathway, ameliorated the effect of TCDD on cellular ß-catenin level, ROS production, cellular oxidative damage and premature senescence in astrocytes. In summary, our findings indicated that TCDD might induce astrocyte senescence via WNT/ß-catenin and ROS-dependent mechanisms.

2,3,7,8-Tetrachlorodibenzo-p-dioxin promotes astrocyte activation and the secretion of tumor necrosis factor-α via PKC/SSeCKS-dependent mechanisms.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous environmental pollutant that could induce significant toxic effects in the human nervous system. However, the underlying molecular mechanism has not been entirely elucidated. Reactive astrogliosis has implicated in various neurological diseases via the production of a variety of pro-inflammatory mediators. Herein, we investigated the potential role of TCDD in facilitating astrocyte activation and the underlying molecular mechanisms. We showed that TCDD induced rapid astrocyte activation following TCDD exposure, which was accompanied by significantly elevated expression of Src-Suppressed-C Kinase Substrate (SSeCKS), a protein involved in protein kinase C (PKC)-mediated Nuclear Factor kappa B signaling, suggesting a possible involvement of PKC-induced SSeCKS activation in TCDD-triggered reactive astroglia. In keeping with the finding, we found that the level of phosphorylated Nuclear Factor kappa B p65 was remarkably increased after TCDD treatment. Furthermore, interference of SSeCKS attenuated TCDD-induced inducible nitric oxide synthase, glial fibrillary acidic protein, phospho-p65 expression, and tumor necrosis factor-α secretion in astrocytes. In addition, pre-treatment with PKC inhibitor also attenuated TCDD-induced astrocyte activation, as well as SSeCKS expression. Interestingly, we found that TCDD treatment could lead to SSeCKS perinuclear localization, which could be abolished after treatment with PKC inhibitor. Finally, we showed that inhibition of PKC activity or SSeCKS expression would impair TCDD-triggered tumor necrosis factor-α secretion. Our results suggested that TCDD exposure could lead to astrocyte activation through PKC/SSeCKS-dependent mechanisms, highlighting that astrocytes might be important target of TCDD-induced neurotoxicity. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) elicits neurotoxic effects. Here, we show TCDD induces pro-inflammatory responses in astrocytes. TCDD initiates an increase of [Ca2+]i, followed by the activation of PKC, which then induces the activation of Src-suppressed C-kinase substrate (SSeCKS). SSeCKS promotes NF-κB activation and the secretion of TNF-α and nitric oxide in astrocytes.

Pivotal roles of p53 transcription-dependent and -independent pathways in manganese-induced mitochondrial dysfunction and neuronal apoptosis.

Chronic exposure to excessive manganese (Mn) has been known to lead to neuronal loss and a clinical syndrome resembling idiopathic Parkinson's disease (IPD). p53 plays an integral role in the development of various human diseases, including neurodegenerative disorders. However, the role of p53 in Mn-induced neuronal apoptosis and neurological deficits remains obscure. In the present study, we showed that p53 was critically involved in Mn-induced neuronal apoptosis in rat striatum through both transcription-dependent and -independent mechanisms. Western blot and immunohistochemistrical analyses revealed that p53 was remarkably upregulated in the striatum of rats following Mn exposure. Coincidentally, increased level of cleaved PARP, a hallmark of apoptosis, was observed. Furthermore, using nerve growth factor (NGF)-differentiated PC12 cells as a neuronal cell model, we showed that Mn exposure decreased cell viability and induced apparent apoptosis. Importantly, p53 was progressively upregulated, and accumulated in both the nucleus and the cytoplasm. The cytoplasmic p53 had a remarkable distribution in mitochondria, suggesting an involvement of p53 mitochondrial translocation in Mn-induced neuronal apoptosis. In addition, Mn-induced impairment of mitochondrial membrane potential (ΔΨm) could be partially rescued by pretreatment with inhibitors of p53 transcriptional activity and p53 mitochondrial translocation, Pifithrin-α (PFT-α) and Pifithrin-µ (PFT-µ), respectively. Moreover, blockage of p53 activities with PFT-α and PFT-µ significantly attenuated Mn-induced reactive oxidative stress (ROS) generation and mitochondrial H2O2 production. Finally, we observed that pretreatment with PFT-α and PFT-µ ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings implicate that p53 transcription-dependent and -independent pathways may play crucial roles in the regulation of Mn-induced neuronal death.

LIN28 expression in rat spinal cord after injury.

LIN28, an RNA-binding protein, is known to be involved in the regulation of many cellular processes, such as embryonic stem cell proliferation, cell fate succession, developmental timing, and oncogenesis. However, its expression and function in central nervous system still unclear. In this study, we performed an acute spinal cord contusion injury (SCI) model in adult rats and investigated the dynamic changes of LIN28 expression in spinal cord. Western blot and immunohistochemistry analysis revealed that LIN28 was present in normal spinal cord. It gradually increased, reached a peak at 3 day, and then nearly declined to the basal level at 14 days after SCI. Double immunofluorescence staining showed that LIN28 immunoreactivity was found in neurons, astrocytes and a handful of microglia. Interestingly, LIN28 expression was increased predominantly in astrocytes but not in neurons. Moreover, the colocalization of LIN28 and proliferating cell nuclear antigen was detected after injury. Western blot showed that LIN28 participated in lipopolysaccharide (LPS) induced astrocytes inflammatory responses by NF-κB signaling pathway. These results suggested that LIN28 may be involved in the pathologic process of SCI, and further research is needed to have a good understanding of its function and mechanism.

[Properties and biocompatibility of collagen scaffold modified by genipin cross-linked L-lysine].

Collagen (Coll), as the basic material of matrix scaffolds for cell growth, has been widely used in the field of tissue engineering and regenerative medicine. In this study, collagen protein was modified by L-lysine (Lys), and cross-linked by genipin (GN) to prepare the L-lysine-modified collagen (Lys-Coll-GN) scaffolds. Microstructure, pore size, porosity, stability and biocompatibility of Lys-Coll-GN scaffolds were observed. The results showed that the bond between L-lysine and collagen protein molecule was formed by generating amide linkage, and mouse embryo fibroblasts proliferation was not inhibited in the Lys-Coll-GN scaffolds. In the multiple comparisons of Coll-scaf- folds, Coll-GN scaffolds and Lys-Coll-GN scaffolds, Coll-scaffolds was the worst in mechanical characteristics while the highest in biodegradation rate. Compared to Coll-GN scaffolds, Lys-Coll-GN scaffolds had more fiber structure, higher interval porosity (P<0. 01). Although the tensile stress of Lys-Coll-GN scaffolds reduced significantly, its e- longation length extended when the scaffolds was fractured (P<0. 01). The percentage of Lys-Coll-GN scaffolds residual weight was lower than that of Coll-GN scaffolds after all the scaffolds were treated by collagenase for 5 days (P<0. 01). This study suggested that Lys-Coll-GN scaffold had good biocompatibility, and it improved the mechanical property and degradation velocity for collagen-based scaffold. This study gave a new predominant type of tissue engineering scaffold for the regenerative medicine.