Protein Kinase C-Delta Mediates Cell Cycle Reentry and Apoptosis Induced by Amyloid-Beta Peptide in Post-Mitotic Cortical Neurons.

Amyloid-beta peptide (Aß) is a neurotoxic constituent of senile plaques in the brains of Alzheimer's disease (AD) patients. The detailed mechanisms by which protein kinase C-delta (PKCδ) contributes to Aß toxicity is not yet entirely understood. Using fully differentiated primary rat cortical neurons, we found that inhibition of Aß25-35-induced PKCδ increased cell viability with restoration of neuronal morphology. Using cyclin D1, proliferating cell nuclear antigen (PCNA), and histone H3 phosphorylated at Ser-10 (p-Histone H3) as the respective markers for the G1-, S-, and G2/M-phases, PKCδ inhibition mitigated cell cycle reentry (CCR) and subsequent caspase-3 cleavage induced by both Aß25-35 and Aß1-42 in the post-mitotic cortical neurons. Upstream of PKCδ, signal transducers and activators of transcription (STAT)-3 mediated PKCδ induction, CCR, and caspase-3 cleavage upon Aß exposure. Downstream of PKCδ, aberrant neuronal CCR was triggered by overactivating cyclin-dependent kinase-5 (CDK5) via calpain2-dependent p35 cleavage into p25. Finally, PKCδ and CDK5 also contributed to Aß25-35 induction of p53-upregulated modulator of apoptosis (PUMA) in cortical neurons. Together, we demonstrated that, in the post-mitotic neurons exposed to Aßs, STAT3-dependent PKCδ expression triggers calpain2-mediated p35 cleavage into p25 to overactivate CDK5, thus leading to aberrant CCR, PUMA induction, caspase-3 cleavage, and ultimately apoptosis.

Glucosamine Enhancement of Learning and Memory Functions by Promoting Fibroblast Growth Factor 21 Production.

Fibroblast growth factor 21 (FGF21) plays a crucial role in metabolism and brain function. Glucosamine (GLN) has been recognized for its diverse beneficial effects. This study aimed to elucidate the modulation of FGF21 production by GLN and its impact on learning and memory functions. Using both in vivo and in vitro models, we investigated the effects of GLN on mice fed with a normal diet or high-fat diet and on mouse HT22 hippocampal cells, STHdhQ7/Q7 striatal cells, and rat primary cortical neurons challenged with GLN. Our results indicated that GLN promotes learning and memory functions in mice and upregulates FGF21 expression in the hippocampus, cortex, and striatum, as well as in HT22 cells, STHdhQ7/Q7 cells, and cortical neurons. In animals receiving GLN together with an FGF21 receptor FGFR1 inhibitor (PD173074), the GLN-enhanced learning and memory functions and induction of FGF21 production in the hippocampus were significantly attenuated. While exploring the underlying molecular mechanisms, the potential involvement of NF-κB, Akt, p38, JNK, PKA, and PPARα in HT22 and NF-κB, Akt, p38, and PPARα in STHdhQ7/Q7 were noted; GLN was able to mediate the activation of p65, Akt, p38, and CREB in HT22 and p65, Akt, and p38 in STHdhQ7/Q7 cells. Our accumulated findings suggest that GLN may increase learning and memory functions by inducing FGF21 production in the brain. This induction appears to be mediated, at least in part, through GLN's activation of the NF-κB, Akt, p38, and PKA/CREB pathways.

Polysaccharides from Basella alba Protect Post-Mitotic Neurons against Cell Cycle Re-Entry and Apoptosis Induced by the Amyloid-Beta Peptide by Blocking Sonic Hedgehog Expression.

The amyloid-beta peptide (Aß) is the neurotoxic component in senile plaques of Alzheimer's disease (AD) brains. Previously we have reported that Aß toxicity is mediated by the induction of sonic hedgehog (SHH) to trigger cell cycle re-entry (CCR) and apoptosis in post-mitotic neurons. Basella alba is a vegetable whose polysaccharides carry immunomodulatory and anti-cancer actions, but their protective effects against neurodegeneration have never been reported. Herein, we tested whether polysaccharides derived from Basella alba (PPV-6) may inhibit Aß toxicity and explored its underlying mechanisms. In differentiated rat cortical neurons, Aß25-35 reduced cell viability, damaged neuronal structure, and compromised mitochondrial bioenergetic functions, all of which were recovered by PPV-6. Immunocytochemistry and western blotting revealed that Aß25-35-mediated induction of cell cycle markers including cyclin D1, proliferating cell nuclear antigen (PCNA), and histone H3 phosphorylated at Ser-10 (p-Histone H3) in differentiated neurons was all suppressed by PPV-6, along with mitigation of caspase-3 cleavage. Further studies revealed that PPV-6 inhibited Aß25-35 induction of SHH; indeed, PPV-6 was capable of suppressing neuronal CCR and apoptosis triggered by the exogenous N-terminal fragment of sonic hedgehog (SHH-N). Our findings demonstrated that, in the fully differentiated neurons, PPV-6 exerts protective actions against Aß neurotoxicity via the downregulation of SHH to suppress neuronal CCR and apoptosis.

A selective inhibitor of the NLRP3 inflammasome as a potential therapeutic approach for neuroprotection in a transgenic mouse model of Huntington's disease.

BACKGROUND: Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of the CAG repeat in the huntingtin (HTT) gene. When the number of CAG repeats exceeds 36, the translated expanded polyglutamine-containing HTT protein (mutant HTT [mHTT]) interferes with the normal functions of many cellular proteins and subsequently jeopardizes important cellular machineries in major types of brain cells, including neurons, astrocytes, and microglia. The NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome, which comprises NLRP3, ASC, and caspase-1, is involved in the activation of IL-1ß and IL-18 and has been implicated in various biological functions. Although the existence of the NLRP3 inflammasome in the brain has been documented, the roles of the NLRP3 inflammasome in HD remain largely uncharacterized. MCC950 is a highly selective and potent small-molecule inhibitor of NLRP3 that has been used for the treatment of several diseases such as Alzheimer's disease. However, whether MCC950 is also beneficial in HD remains unknown. Therefore, we hypothesized that MCC950 exerts beneficial effects in a transgenic mouse model of HD. METHODS: To evaluate the effects of MCC950 in HD, we used the R6/2 (B6CBA-Tg[HDexon1]62Gpb/1J) transgenic mouse model of HD, which expresses exon 1 of the human HTT gene carrying 120 ± 5 CAG repeats. Male transgenic R6/2 mice were treated daily with MCC950 (10 mg/kg of body weight; oral administration) or water for 5 weeks from the age of 7 weeks. We examined neuronal density, neuroinflammation, and mHTT aggregation in the striatum of R6/2 mice vs. their wild-type littermates. We also evaluated the motor function, body weight, and lifespan of R6/2 mice. RESULTS: Systematic administration of MCC950 to R6/2 mice suppressed the NLRP3 inflammasome, decreased IL-1ß and reactive oxygen species production, and reduced neuronal toxicity, as assessed based on increased neuronal density and upregulation of the NeuN and PSD-95 proteins. Most importantly, oral administration of MCC950 increased neuronal survival, reduced neuroinflammation, extended lifespan, and improved motor dysfunction in R6/2 mice. CONCLUSIONS: Collectively, our findings indicate that MCC950 exerts beneficial effects in a transgenic mouse model of HD and has therapeutic potential for treatment of this devastating neurodegenerative disease.

Emerging Roles of Sonic Hedgehog in Adult Neurological Diseases: Neurogenesis and Beyond.

Sonic hedgehog (Shh), a member of the hedgehog (Hh) family, was originally recognized as a morphogen possessing critical characters for neural development during embryogenesis. Recently, however, Shh has emerged as an important modulator in adult neural tissues through different mechanisms such as neurogenesis, anti-oxidation, anti-inflammation, and autophagy. Therefore, Shh may potentially have clinical application in neurodegenerative diseases and brain injuries. In this article, we present some examples, including ours, to show different aspects of Shh signaling and how Shh agonists or mimetics are used to alter the neuronal fates in various disease models, both in vitro and in vivo. Other potential mechanisms that are discussed include alteration of mitochondrial function and anti-aging effect; both are critical for age-related neurodegenerative diseases. A thorough understanding of the protective mechanisms elicited by Shh may provide a rationale to design innovative therapeutic regimens for various neurodegenerative diseases.

Roles of p62 in BDNF-dependent autophagy suppression and neuroprotection against mitochondrial dysfunction in rat cortical neurons.

Previously, we have reported that pre-conditioning of primary rat cortical neurons with brain-derived neurotrophic factor (BDNF) may exert neuroprotective effects against 3-nitropropionic acid (3-NP), a mitochondrial complex II inhibitor. However, the underlying mechanisms, especially potential involvements of autophagy, remain elusive. In this work, we tested the hypothesis that BDNF may suppress 3-NP-induced autophagy to exert its neuroprotective effects by inducing the expression of p62/sequestosome-1 in primary cortical neurons. We found that 3-NP increased total level of microtubule-associated protein 1A/1B-light chain (LC)-3 as well as the LC3-II/LC3-I ratio, an index of autophagy, in primary cortical neurons. BDNF decreased LC3-II/LC3-I ratio and time-dependently induced expression of p62. Knockdown of p62 by siRNA restored LC3-II/LC3-I ratio and increased total LC3 levels associated with BDNF exposure; p62 knockdown also abolished BDNF-dependent neuroprotection against 3-NP. Upstream of p62, we found that BDNF triggered phosphorylation of mammalian target of rapamycin (mTOR) and its downstream mediator p70S6K; importantly, the mTOR inhibitor rapamycin reduced both BDNF-dependent p62 induction as well as 3-NP resistance. BDNF is known to induce c-Jun in cortical neurons. We found that c-Jun knockdown in part attenuated BDNF-mediated p62 induction, whereas p62 knockdown had no significant effects on c-Jun expression. In addition to suppressing p62 induction, rapamycin also partially suppressed BDNF-induced c-Jun expression, but c-Jun knockdown failed to affect mTOR activation. Together, our results suggested that BDNF inhibits 3-NP-induced autophagy via, at least in part, mTOR/c-Jun-dependent induction of p62 expression, together contributing to neuroprotection against mitochondrial inhibition.

Enlargement of the WHO international repository for platelet transfusion-relevant bacteria reference strains.

BACKGROUND AND OBJECTIVES: Interventions to prevent and detect bacterial contamination of platelet concentrates (PCs) have reduced, but not eliminated the sepsis risk. Standardized bacterial strains are needed to validate detection and pathogen reduction technologies in PCs. Following the establishment of the First International Reference Repository of Platelet Transfusion-Relevant Bacterial Reference Strains (the 'repository'), the World Health Organization (WHO) Expert Committee on Biological Standardisation (ECBS) endorsed further repository expansion. MATERIALS AND METHODS: Sixteen bacterial strains, including the four repository strains, were distributed from the Paul-Ehrlich-Institut (PEI) to 14 laboratories in 10 countries for enumeration, identification and growth measurement on days 2, 4 and 7 after low spiking levels [10-25 colony-forming units (CFU)/PC bag]. Spore-forming (Bacillus cereusPEI-B-P-07-S, Bacillus thuringiensisPEI-B-P-57-S), Gram-negative (Enterobacter cloacaePEI-B-P-43, Morganella morganiiPEI-B-P-74, PEI-B-P-91, Proteus mirabilisPEI-B-P-55, Pseudomonas fluorescensPEI-B-P-77, Salmonella choleraesuisPEI-B-P-78, Serratia marcescensPEI-B-P-56) and Gram-positive (Staphylococcus aureusPEI-B-P-63, Streptococcus dysgalactiaePEI-B-P-71, Streptococcus bovisPEI-B-P-61) strains were evaluated. RESULTS: Bacterial viability was conserved after transport to the participating laboratories with one exception (M. morganiiPEI-B-P-74). All other strains showed moderate-to-excellent growth. Bacillus cereus, B. thuringiensis, E. coli, K. pneumoniae, P. fluorescens, S. marcescens, S. aureus and S. dysgalactiae grew to >106 CFU/ml by day 2. Enterobacter cloacae, P. mirabilis, S. epidermidis, S. bovis and S. pyogenes achieved >106 CFU/ml at day 4. Growth of S. choleraesuis was lower and highly variable. CONCLUSION: The WHO ECBS approved all bacterial strains (except M. morganiiPEI-B-P-74 and S. choleraesuisPEI-B-P-78) for repository enlargement. The strains were stable, suitable for spiking with low CFU numbers, and proliferation was independent of the PC donor.

More Insight into BDNF against Neurodegeneration: Anti-Apoptosis, Anti-Oxidation, and Suppression of Autophagy.

In addition to its well-established neurotrophic action, brain-derived neurotrophic factor (BDNF) also possesses other neuroprotective effects including anti-apoptosis, anti-oxidation, and suppression of autophagy. We have shown before that BDNF triggers multiple mechanisms to confer neuronal resistance against 3-nitropropionic acid (3-NP)-induced mitochondrial dysfunction in primary rat cortical cultures. The beneficial effects of BDNF involve the induction of anti-oxidative thioredoxin with the resultant expression of anti-apoptotic B-cell lymphoma 2 (Bcl-2) as well as erythropoietin (EPO)-dependent stimulation of sonic hedgehog (SHH). We further revealed that BDNF may bring the expression of sulfiredoxin, an ATP-dependent antioxidant enzyme, to offset mitochondrial inhibition in cortical neurons. Recently, we provided insights into another novel anti-oxidative mechanism of BDNF, which involves the augmentation of sestrin2 expression to endow neuronal resistance against oxidative stress induced by 3-NP; BDNF induction of sestrin2 entails the activation of a pathway involving nitric oxide (NO), cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG), and nuclear factor-κB (NF-κB). Apart from anti-apoptosis and anti-oxidation, we demonstrated in our most recent study that BDNF may activate the mammalian target of rapamycin (mTOR) with resultant activation of transcription factor c-Jun, thereby stimulating the expression of p62/sequestosome-1 to suppress heightened autophagy as a result of 3-NP exposure. Together, our results provide in-depth insight into multi-faceted protective mechanisms of BDNF against mitochondrial dysfunction commonly associated with the pathogenesis of many chronic neurodegenerative disorders. Delineation of the protective signaling pathways elicited by BDNF would endow a rationale to develop novel therapeutic regimens to halt or prevent the progression of neurodegeneration.

Oncostatin M-dependent Mcl-1 induction mediated by JAK1/2-STAT1/3 and CREB contributes to bioenergetic improvements and protective effects against mitochondrial dysfunction in cortical neurons.

Oncostatin M (OSM), a cytokine in the interleukin-6 (IL-6) family, has been proposed to play a protective role in the central nervous system, such as attenuation of excitotoxicity induced by N-methyl-D-aspartate (NMDA) and glutamate. However, the potential neuroprotective effects of OSM against mitochondrial dysfunction have never been reported. In the present study, we tested the hypothesis that OSM may confer neuronal resistance against 3-nitropropionic acid (3-NP), a plant toxin that irreversibly inhibits the complex II of the mitochondrial electron transport chain, and characterized the underlying molecular mechanisms. We found that OSM preconditioning dose- and time-dependently protected cortical neurons against 3-NP toxicity. OSM stimulated expression of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic Bcl-2 family member expressed in differentiating myeloid cells, that required prior phosphorylation of Janus kinase-1 (JAK1), JAK2, extracellular signal-regulated kinase-1/2 (ERK1/2), signal transducer and activator of transcription-3 (STAT3), STAT1, and cAMP-response element-binding protein (CREB). Pharmacological inhibitors of JAK1, JAK2, ERK1/2, STAT3, STAT1, and CREB as well as the siRNA targeting at STAT3 and Mcl-1 all abolished OSM-dependent 3-NP resistance. Finally, OSM-dependent Mcl-1 induction contributed to the enhancements of mitochondrial bioenergetics including increases in spare respiratory capacity and ATP production. In conclusion, our findings indicated that OSM induces Mcl-1 expression via activation of ERK1/2, JAK1/2, STAT1/3, and CREB; furthermore, OSM-mediated Mcl-1 induction contributes to bioenergetic improvements and neuroprotective effects against 3-NP toxicity in cortical neurons. OSM may thus serve as a novel neuroprotective agent against mitochondrial dysfunction commonly associated with pathogenic mechanisms underlying neurodegeneration.

Peroxisome proliferator-activated receptor-gamma dependent pathway reduces the phosphorylation of dynamin-related protein 1 and ameliorates hippocampal injury induced by global ischemia in rats.

BACKGROUND: Dynamin-related protein 1 (Drp1) is a mitochondrial fission protein that, upon phosphorylation at serine 616 (p-Drp1(Ser616)), plays a pivotal role in neuronal death after ischemia. In the present study, we hypothesized that peroxisome proliferator-activated receptor-gamma (PPARγ)-dependent pathway can reduce the expression of p-Drp1(Ser616) and ameliorate hippocampal injury induced by global ischemia in rats. RESULTS: We found that pretreatment of the rats with Mdivi-1, a selective Drp1 inhibitor, decreased the level of transient global ischemia (TGI)-induced p-Drp1(Ser616) and reduced cellular contents of oxidized proteins, activated caspase-3 expression as well as the extent of DNA fragmentation. Delivery of siRNA against Drp1 attenuated the expression of p-Drp1(Ser616) that was accompanied by alleviation of the TGI-induced protein oxidation, activated caspase-3 expression and DNA fragmentation in hippocampal proteins. Exogenous application of pioglitazone, a PPARγ agonist, reduced the p-Drp1(Ser616) expression, decreased TGI-induced oxidative stress and activated caspase-3 expression, lessened the extents of DNA fragmentation, and diminished the numbers of TUNEL-positive neuronal cells; all of these effects were reversed by GW9662, a PPARγ antagonist. CONCLUSIONS: Our findings thus indicated that inhibition of TGI-induced p-Drp1(Ser616) expression by Drp1 inhibitor and Drp1-siRNA can decrease protein oxidation, activated caspase-3 expression and neuronal damage in the hippocampal CA1 subfield. PPARγ agonist, through PPARγ-dependent mechanism and via decreasing p-Drp1(Ser616) expression, can exert anti-oxidative and anti-apoptotic effects against ischemic neuronal injury.

Roles of PTEN-induced putative kinase 1 and dynamin-related protein 1 in transient global ischemia-induced hippocampal neuronal injury.

Recent studies showed that increased mitochondrial fission is an early event of cell death during cerebral ischemia and dynamin-related protein 1 (Drp1) plays an important role in mitochondrial fission, which may be regulated by PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine/threonine-protein kinase thought to protect cells from stress-induced mitochondrial dysfunction and regulate mitochondrial fission. However, the roles of PINK1 and Drp1 in hippocampal injury caused by transient global ischemia (TGI) remain unknown. We therefore tested the hypothesis that TGI may induce PINK1 causing downregulation of Drp1 phosphorylation to enhance hippocampal neuronal survival, thus functioning as an endogenous neuroprotective mechanism. We found progressively increased PINK1 expression in the hippocampal CA1 subfield1-48 h following TGI, reaching the maximal level at 4 h. Despite lack of changes in the expression level of total Drp1 and phosphor-Drp1 at Ser637, TGI induced a time-dependent increase of Drp1 phosphorlation at Ser616 that peaked after 24 h. Notably, PINK1-siRNA increased p-Drp1(Ser616) protein level in hippocampal CA1 subfield 24 h after TGI. The PINK1 siRNA also aggravated the TGI-induced oxidative DNA damage with an increased 8-hydroxy-deoxyguanosine (8-OHdG) content in hippocampal CA1 subfield. Furthermore, PINK1 siRNA also augmented TGI-induced apoptosis as evidenced by the increased numbers of TUNEL-positive staining and enhanced DNA fragmentation. These findings indicated that PINK1 is an endogenous protective mediator vital for neuronal survival under ischemic insult through regulating Drp1 phosphorylation at Ser616.

Multidrug resistant Acinetobacter baumannii reaches a new frontier: prosthetic hip joint infection.

Acinetobacter baumannii is an emerging nosocomial pathogen primarily in countries with a high prevalence of multidrug resistance. Here we report the detection of a bla OXA23 carbapenemase-producing A. baumannii strain in a German patient with prosthetic hip joint infection following several hip joint surgeries but no history of foreign travel.

Roles of Sestrin2 and Ribosomal Protein S6 in Transient Global Ischemia-Induced Hippocampal Neuronal Injury.

Recent studies suggested that sestrin2 is a crucial modulator for the production of reactive oxygen species (ROS). In addition, sestrin2 may also regulate ribosomal protein S6 (RpS6), a molecule important for protein synthesis, through the effect of mammalian target of rapamycin (mTOR) complex that is pivotal for longevity. However, the roles of sestrin2 in cerebral ischemia, in which oxidative stress is one of the major pathogenic mechanisms, are still less understood. In this study, we hypothesized that sestrin2 may protect hippocampal CA1 neurons against transient global ischemia (TGI)-induced apoptosis by regulating RpS6 phosphorylation in rats. We found that sestrin2 expression was progressively increased in the hippocampal CA1 subfield 1-48 h after TGI, reaching the maximal level at 24 h, and declined thereafter. Further, an increased extent of RpS6 phosphorylation, but not total RpS6 protein level, was observed in the hippocampal CA1 subfield after TGI. The sestrin2 siRNA, which substantially blocked the expression of TGI-induced sestrin2, also abolished RpS6 phosphorylation. TGI with reperfusion may induce oxidative stress with the resultant formation of 8-hydroxy-deoxyguanosine (8-OHdG). We found that sestrin2 siRNA further augmented the formation of 8-OHdG induced by TGI with reperfusion for 4 h. Consistently, sestrin2 siRNA also enhanced apoptosis induced by TGI with reperfusion for 48 h based on the analysis of DNA fragmentation by agarose gel electrophoresis, DNA fragmentation sandwich ELISA, and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. Together these findings indicated that TGI-induced sestrin2 expression contributed to RpS6 phosphorylation and neuroprotection against ischemic injury in the hippocampal CA1 subfield.

[Current concept for the microbiological safety of cell-based medicinal products]. / Aktuelles Konzept zur mikrobiologischen Sicherheit von zellbasierten Arzneimitteln.

Ensuring microbiological safety in advanced-therapy medicinal products is still a big challenge for manufacturers. There are fundamental problems, especially in cell-based medicinal products, regarding sterility of source materials, short shelf-life of final products, and the selection of suitable microbiological methods. Different from classical medicinal products, there is the need to evaluate a large number of possible risks and to calculate the risk-benefit balance. Depending on the source material, the presence of micro-organisms with specific growth requirements has to be considered. They cannot be detected by conventional testing methods, but may replicate after the application of the preparation in the recipient. Mycoplasmas are the primary representatives of these contaminants and specific testing procedures are required. Additionally, depending on the source and processing of the biological material, specific testing methods for mycobacteria and other contaminants should be included. Alternative microbiological methods (e.g. NAT, flow cytometry) should be applied in order to reduce the time to detection and to provide reliable results before application of a preparation, but should be also assessed for their possible use for the detection of conventionally undetectable micro-organisms.

Spontaneous bacterial peritonitis by Pasteurella multocida under treatment with rifaximin.

Spontaneous bacterial peritonitis (SBP) is a life-threatening complication of liver cirrhosis. Recently, rifaximin, a non-absorbable antibiotic which is used to prevent recurrent hepatic encephalopathy, has been proposed as effective prophylaxis for SBP. Here, we present an unusual case of SBP under treatment with rifaximin. A 50-year-old woman with liver cirrhosis was admitted because of tense ascites and abdominal pain. She was under long-term oral prophylaxis with rifaximin due to hepatic encephalopathy. Paracentesis revealed SBP caused by Pasteurella multocida, which was sensitive to multiple antibiotics, including rifaximin. Treatment with ceftriaxone resulted in rapid resolution of the peritonitis and restoration of the patient. Since P. multocida is usually transmitted from pets, the patient's cat was tested and could be identified as the most likely source of infection. This case should elicit our awareness that uncommon pathogens and unusual routes of transmission may lead to SBP, despite antibacterial prophylaxis with non-absorbable antibiotics. Nevertheless, such infections may still remain sensitive to systemic therapy with conventional antibiotics.

c-Jun-dependent sulfiredoxin induction mediates BDNF protection against mitochondrial inhibition in rat cortical neurons.

In current study, we tested the hypothesis that c-Jun-dependent sulfiredoxin expression mediates protective effects of brain-derived neurotrophic factor (BDNF) against neurotoxicity induced by 3-nitropropionic acid (3-NP), a mitochondrial complex II inhibitor, in primary rat cortical cultures. We found that BDNF-dependent c-Jun expression and nuclear translocation required prior phosphorylation of extracellular signal-regulated kinase (ERK)1/2, but not Akt. BDNF also transiently activated the expression of sulfiredoxin, an ATP-dependent antioxidant enzyme, at both mRNA and protein levels. Furthermore, both c-Jun siRNA and ERK1/2 inhibitor PD98059 suppressed BDNF-induced sulfiredoxin expression. Finally, PD98059, c-Jun siRNA, and sulfiredoxin siRNA all abrogated BDNF-mediated 3-NP resistance. Together, these results established a signaling cascade of "BDNF → ERK1/2-Pi → c-Jun → sulfiredoxin → 3-NP resistance". We therefore conclude that c-Jun-induced sulfiredoxin mediates the BDNF-dependent neuroprotective effects against 3-NP toxicity in primary rat cortical neurons, at least in part.

The importance of dye chemistry and TiCl4 surface treatment in the behavior of Al2O3 recombination barrier layers deposited by atomic layer deposition in solid-state dye-sensitized solar cells.

Atomic layer deposition (ALD) was used to fabricate Al(2)O(3) recombination barriers in solid-state dye-sensitized solar cells (ss-DSSCs) employing an organic hole transport material (HTM) for the first time. Al(2)O(3) recombination barriers of varying thickness were incorporated into efficient ss-DSSCs utilizing the Z907 dye adsorbed onto a 2 µm-thick nanoporous TiO(2) active layer and the HTM spiro-OMeTAD. The impact of Al(2)O(3) barriers was also studied in devices employing different dyes, with increased active layer thicknesses, and with substrates that did not undergo the TiCl(4) surface treatment. In all instances, electron lifetimes (as determined by transient photovoltage measurements) increased and dark current was suppressed after Al(2)O(3) deposition. However, only when the TiCl(4) treatment was eliminated did device efficiency increase; in all other instances efficiency decreased due to a drop in short-circuit current. These results are attributed in the former case to the similar effects of Al(2)O(3) ALD and the TiCl(4) surface treatment whereas the insulating properties of Al(2)O(3) hinder charge injection and lead to current loss in TiCl(4)-treated devices. The impact of Al(2)O(3) barrier layers was unaffected by doubling the active layer thickness or using an alternative ruthenium dye, but a metal-free donor-π-acceptor dye exhibited a much smaller decrease in current due to its higher excited state energy. We develop a model employing prior research on Al(2)O(3) growth and dye kinetics that successfully predicts the reduction in device current as a function of ALD cycles and is extendable to different dye-barrier systems.

Ginsenoside compound K reduces the progression of Huntington's disease via the inhibition of oxidative stress and overactivation of the ATM/AMPK pathway.

Background: Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of trinucleotide CAG repeat in the Huntingtin (Htt) gene. The major pathogenic pathways underlying HD involve the impairment of cellular energy homeostasis and DNA damage in the brain. The protein kinase ataxia-telangiectasia mutated (ATM) is an important regulator of the DNA damage response. ATM is involved in the phosphorylation of AMP-activated protein kinase (AMPK), suggesting that AMPK plays a critical role in response to DNA damage. Herein, we demonstrated that expression of polyQ-expanded mutant Htt (mHtt) enhanced the phosphorylation of ATM. Ginsenoside is the main and most effective component of Panax ginseng. However, the protective effect of a ginsenoside (compound K, CK) in HD remains unclear and warrants further investigation. Methods: This study used the R6/2 transgenic mouse model of HD and performed behavioral tests, survival rate, histological analyses, and immunoblot assays. Results: The systematic administration of CK into R6/2 mice suppressed the activation of ATM/AMPK and reduced neuronal toxicity and mHTT aggregation. Most importantly, CK increased neuronal density and lifespan and improved motor dysfunction in R6/2 mice. Conversely, CK enhanced the expression of Bcl2 protected striatal cells from the toxicity induced by the overactivation of mHtt and AMPK. Conclusions: Thus, the oral administration of CK reduced the disease progression and markedly enhanced lifespan in the transgenic mouse model (R6/2) of HD.

Cystic fibrosis hetero- and homozygosity is associated with inhibition of breast cancer growth.

Cystic fibrosis (CF) is the most common lethal recessive genetic disease of the Caucasian population. Although reports of cancer frequency in CF have emphasized an elevated observed-to-expected ratio of 6.5 for digestive tract cancers, these studies also show a significantly decreased observed-to-expected ratio for other malignancies including breast cancer. The cystic fibrosis transmembrane conductance regulator (CFTR) functions as an ATP channel. We found that heterozygous and homozygous CFTR knockout mice had elevated blood ATP concentrations. Elevated extracellular ATP is known to inhibit tumor growth in vivo and in vitro. Using double mutant mice created by F2 generation crosses of CFTR knockout and nude mice, we observed reduced breast tumor implantability in CFTR homozygous nude animals. Decreased tumor growth rate was observed in both CFTR heterozygous and homozygous nude animals. Extracellular ATP reduced human breast tumor cell growth rate in vitro, and a breast tumor transfected with human CFTR that had high extracellular ATP concentrations in vitro correspondingly had a slower growth rate in vivo. The results suggest that both CFTR heterozygosity and homozygosity suppress breast cancer growth and that elevated extracellular ATP can account for this phenomenon.