Nuclear factor-kappaB activated by capacitative Ca2+ entry enhances muscarinic receptor-mediated soluble amyloid precursor protein (sAPPalpha) release in SH-SY5Y cells

Establishment of a novel cellular model for Alzheimer's disease in vitro studies

Alzheimer's disease (AD) is a neurodegenerative disease characterized by memory loss, cognitive impairment, and behavioral and psychological symptoms of dementia. The limited efficacy of drugs for the treatment of neurodegenerative diseases reflects their complex etiology and pathogenesis. A novel in vitro model may help to bridge the gap between existing preclinical animal models and human clinical trials, thus identifying promising therapeutic targets that can be explored in upcoming clinical trials. By assisting in the identification of the mechanism of action and potential dangers, in vitro testing can also shorten the time and expense of translation.

AIM

As a result of these factors, our objective is to develop a powerful and informative cellular model of AD within a short period of time. Through triggering the MAPK and NF-κβ signaling pathways with the aid of small chemical compounds (PAF C-16 and BetA), respectively, in mouse microglial (SIM-A9) and neuroblast Neuro-2a (N2a) cell lines.

RESULTS

PAF C-16, initiated an activation effect at a concentration of 3.12 nM to 25 nM in the SIM-A9 and N2a cell lines after 72 h. BetA, activated the NF-κβ pathway with a concentration of 12.5 nM to 25 nM in the SIM-A9 and N2a cell lines after 72 h. The combination of the activator chemicals provided suitable activation for MEK1/2-ERK and NF-κβ in more than three subcultures. Activators significantly initiate APP and MAPT gene expression, as well as the expression of proteins APP, β. Amyloid, tau, and p-tau. The activation of the targeted pathways leads to significant morphological changes.

CONCLUSION

We can infer that the MEK1/2-ERK and NF-κβ pathways, respectively, are directly activated by the PAF C-16 and BetA chemicals. The activation of MEK1/2-ERK pathway results in the activation of the APP gene, which in turn activates the β. Amyloid protein, which in turn results in plaque. Furthermore, NF-κβ activation results in the activation of the MAPT gene, which leads to Tau and p-Tau protein activation, which ultimately results in tangles. This can be put into practice in just three days, with a high level of activity and stability that is passed down to the next three generations (subculture), with significant morphological changes. In microglial and neuroblast cell lines, we were successful in creating a novel AD-cell model.

Proteasome inhibitors induce apoptosis by superoxide anion generation via NADPH oxidase 5 in human neuroblastoma SH-SY5Y cells

The ubiquitin-proteasome system (UPS) is a major proteolytic system that plays an important role in the regulation of various cell processes, such as cell cycle, stress response, and transcriptional regulation, especially in neurons, and dysfunction of UPS is considered to be a cause of neuronal cell death in neurodegenerative diseases. However, the mechanism of neuronal cell death caused by UPS dysfunction has not yet been fully elucidated. In this study, we investigated the mechanism of neuronal cell death induced by proteasome inhibitors using human neuroblastoma SH-SY5Y cells. Z-Leu-D-Leu-Leu-al (MG132), a proteasome inhibitor, induced apoptosis in SH-SY5Y cells in a concentration- and time-dependent manner. Antioxidants N-acetylcysteine and EUK-8 attenuated MG132-induced apoptosis. Apocynin and diphenyleneiodonium, inhibitors of NADPH oxidase (NOX), an enzyme that produces superoxide anions, also attenuated MG132-induced apoptosis. It was also found that MG132 treatment increased the expression of NOX5, a NOX family member, and that siRNA-mediated silencing of NOX5 and BAPTA-AM, which inhibits NOX5 by chelating calcium, suppressed MG132-induced apoptosis and production of reactive oxygen species in SH-SY5Y cells. These results suggest that MG132 induces apoptosis in SH-SY5Y cells through the production of superoxide anion by NOX5.

NF-κB Pathway and Its Inhibitors: A Promising Frontier in the Management of Alzheimer's Disease

The nuclear factor kappa B (NF-κB) pathway has emerged as a pivotal player in the pathogenesis of various diseases, including neurodegenerative illnesses like Alzheimer's disease (AD). The involvement of the NF-κB pathway in immune system responses, inflammation, oxidative stress, and neuronal survival highlights its significance in AD progression. We discuss the advantages of NF-κB pathway inhibition, including the potential to mitigate neuroinflammation, modulate amyloid beta (Aβ) production, and promote neuronal survival. However, we also acknowledge the limitations and challenges associated with this approach. Balancing the fine line between dampening inflammation and preserving physiological immune responses is critical to avoid unintended consequences. This review combines current knowledge on the NF-κB pathway's intricate involvement in AD pathogenesis, emphasizing its potential as a therapeutic target. By evaluating both advantages and limitations, we provide a holistic view of the feasibility and challenges of NF-κB pathway modulation in AD treatment. As the quest for effective AD therapies continues, an in-depth understanding of the NF-κB pathway's multifaceted roles will guide the development of targeted interventions with the potential to improve AD management.

Inhibition of the NF-κB signaling pathway affects gonadal differentiation and leads to male bias in Paramisgurnus dabryanus

In recent years, sex-controlled breeding has emerged as an effective strategy to enhance the yields of economic animals with different growth characteristics, while increasing the economic benefits of aquaculture. It is known that the NF-κB pathway participates in gonadal differentiation and reproduction. Therefore, we used the large-scale loach as a research model for the present study and selected an effective inhibitor of the NF-κB signaling pathway (QNZ). This, to investigates the impacts of the NF-κB signaling pathway on gonadal differentiation during a critical period of gonad development and after maturation. Simultaneously, the sex ratio bias and the reproductive capacities of adult fish were analyzed. Our results indicated that the inhibition of the NF-κB signaling pathway influenced the expression of genes related to gonad development, regulated the gene expression related to the brain-gonad-liver axis of juvenile loaches, and finally impacted the gonadal differentiation of the large-scale loach and promoted a male-biased sex ratio. Meanwhile, high QNZ concentrations affected the reproductive abilities of adult loaches and inhibited the growth performance of offspring. Thus, our results deepened the exploration of sex control in fish and provided a certain research basis for the sustainable development of the aquaculture industry.

Neuronal Store-Operated Calcium Channels

The endoplasmic reticulum (ER) is the major intracellular calcium (Ca²⁺) storage compartment in eukaryotic cells. In most instances, the mobilization of Ca²⁺ from this store is followed by a delayed and sustained uptake of Ca²⁺ through Ca²⁺-permeable channels of the cell surface named store-operated Ca²⁺ channels (SOCCs). This gives rise to a store-operated Ca²⁺ entry (SOCE) that has been thoroughly investigated in electrically non-excitable cells where it is the principal regulated Ca²⁺ entry pathway. The existence of this Ca²⁺ route in neurons has long been a matter of debate. However, a growing body of experimental evidence indicates that the recruitment of Ca²⁺ from neuronal ER Ca²⁺ stores generates a SOCE. The present review summarizes the main studies supporting the presence of a depletion-dependent Ca²⁺ entry in neurons. It also addresses the question of the molecular composition of neuronal SOCCs, their expression, pharmacological properties, as well as their physiological relevance.

The Mystery of EVP4593: Perspectives of the Quinazoline-Derived Compound in the Treatment of Huntington's Disease and Other Human Pathologies

Quinazoline derivatives have various pharmacological activities and are widely used in clinical practice. Here, we reviewed the proposed mechanisms of the physiological activity of the quinazoline derivative EVP4593 and perspectives for its clinical implication. We summarized the accumulated data about EVP4593 and focused on its activities in different models of Huntington's disease (HD), including patient-specific iPSCs-based neurons. To make a deeper insight into its neuroprotective role in HD treatment, we discussed the ability of EVP4593 to modulate calcium signaling and reduce the level of the huntingtin protein. Moreover, we described possible protective effects of EVP4593 in other pathologies, such as oncology, cardiovascular diseases and parasite invasion. We hope that comprehensive analyses of the molecular mechanisms of EVP4593 activity will allow for the expansion of the scope of the EVP4593 application.

NDUFS3 knockout cancer cells and molecular docking reveal specificity and mode of action of anti-cancer respiratory complex I inhibitors

Inhibition of respiratory complex I (CI) is becoming a promising anti-cancer strategy, encouraging the design and the use of inhibitors, whose mechanism of action, efficacy and specificity remain elusive. As CI is a central player of cellular bioenergetics, a finely tuned dosing of targeting drugs is required to avoid side effects. We compared the specificity and mode of action of CI inhibitors metformin, BAY 87-2243 and EVP 4593 using cancer cell models devoid of CI. Here we show that both BAY 87-2243 and EVP 4593 were selective, while the antiproliferative effects of metformin were considerably independent from CI inhibition. Molecular docking predictions indicated that the high efficiency of BAY 87-2243 and EVP 4593 may derive from the tight network of bonds in the quinone binding pocket, although in different sites. Most of the amino acids involved in such interactions are conserved across species and only rarely found mutated in human. Our data make a case for caution when referring to metformin as a CI-targeting compound, and highlight the need for dosage optimization and careful evaluation of molecular interactions between inhibitors and the holoenzyme.

A scalable organoid model of human autosomal dominant polycystic kidney disease for disease mechanism and drug discovery

Human pluripotent stem-cell-derived organoids are models for human development and disease. We report a modified human kidney organoid system that generates thousands of similar organoids, each consisting of 1-2 nephron-like structures. Single-cell transcriptomic profiling and immunofluorescence validation highlighted patterned nephron-like structures utilizing similar pathways, with distinct morphogenesis, to human nephrogenesis. To examine this platform for therapeutic screening, the polycystic kidney disease genes PKD1 and PKD2 were inactivated by gene editing. PKD1 and PKD2 mutant models exhibited efficient and reproducible cyst formation. Cystic outgrowths could be propagated for months to centimeter-sized cysts. To shed new light on cystogenesis, 247 protein kinase inhibitors (PKIs) were screened in a live imaging assay identifying compounds blocking cyst formation but not overall organoid growth. Scaling and further development of the organoid platform will enable a broader capability for kidney disease modeling and high-throughput drug screens.

Effects of Serum Metabolites on the Pancreatic Transcriptome in Acute Acalculous Cholecystitis

Background

To provide a basis for the diagnosis and treatment of acalculous biliary pancreatitis, this study investigated the impact of serum metabolites on the pancreatic transcriptome in acute acalculous cholecystitis (AAC).

Methods

Fourteen rabbits were randomly divided into two groups (a normal control group of 7 rabbits and an AAC group of 7 rabbits), blood was collected from the 14 rabbits, and metabolomic analysis was performed through ¹H NMR. Two pancreatic tissue chips of the AAC group and the normal control group were prepared and sequenced. We utilized the limma package of R software, the DAVID database, the STRING database, Cytoscape software, and the CFinder analysis tool to perform differential expression gene analysis, gene function enrichment analysis, protein interaction network (PPI) construction, and network module mining, and we performed gene enrichment analysis in each module.

Results

Serum metabolism analysis showed that in AAC, the metabolism of sugar, lipids, and protein, that is, the three major nutrients, was affected to varying degrees, and levels of serum trimethylamine N-oxide (TMAO) increased. Bioinformatic methods were utilized to identify a total of 183 differentially expressed genes and 3 key genes. Enrichment analysis showed that differentially expressed genes were significantly enriched in cation transport, the inflammatory response, the NF-κB pathway, and the cancer signaling pathway.

Conclusion

Metabolomic analysis and functional analysis of 3 key genes demonstrated that abnormal serum metabolites affected the pancreatic transcriptome and induced a sensitive state of inflammation in the pancreas. These metabolites may represent important targets for future research on the pathogenesis, clinical diagnosis, and treatment of noncalculous biliary pancreatitis.

Chronic Neuroinflammation Induced by Lipopolysaccharide Injection into the Third Ventricle Induces Behavioral Changes

The existence of Gram-negative bacteria in the brain, regardless of underlying immune status has been demonstrated by recent studies. The colocalization of lipopolysaccharide (LPS) with Aβ_1-40/42 in amyloid plaques supports the hypothesis that brain microbes may be the cause, triggering chronic neuroinflammation, leading to Alzheimer's disease (AD). To investigate the behavioral changes induced by infectious neuroinflammation, we chose the third ventricle as the site of a single LPS injection (20 μg or 80 μg) in male Wistar rats to avoid mechanical injury to forebrain structures while inducing widespread inflammation throughout the brain. Chronic neuroinflammation induced by LPS resulted in depressive-like behaviors and the impairment of spatial learning; however, there was no evidence of the development of pathological hallmarks (e.g., the phosphorylation of tau) for 10 months following LPS injection. The acceleration of cholesterol metabolism via CYP46A1 and the retardation of cholesterol synthesis via HMGCR were observed in the hippocampus of rats treated with either low-dose or high-dose LPS. The rate-limiting enzymes of cholesterol metabolism (CYP46A1) in SH-SY5Y cells and synthesis (HMGCR) in U251 cells were altered by inflammation stimulators, including LPS, IL-1β, and TNF-α, through the TLR4/MyD88/NF-κB signaling pathway. The data suggest that chronic neuroinflammation provoked by the administration of LPS into the third ventricle may induce depressive-like symptoms and that the loss of cholesterol might be a biomarker of chronic neuroinflammation. The lack of pathological hallmarks of AD in our model indicates that Gram-negative bacteria infection might not be a single cause of AD.

Heme oxygenase-1 attenuates the inhibitory effect of bortezomib against the APRIL-NF-κB-CCL3 signaling pathways in multiple myeloma cells: Corelated with bortezomib tolerance in multiple myeloma

Osteoclasts (OCs) play an essential role in bone destruction in patients with multiple myeloma (MM). Bortezomib can ameliorate bone destruction in patients with MM, but advanced MM often resists bortezomib. We studied the molecular mechanisms of bortezomib tolerance in MM. The expression of the MM-related genes in newly diagnosed patients with MM and normal donors were studied. C-C motif chemokine ligand 3 (CCL3) is a cytokine involved in the differentiation of OCs, and its expression is closely related to APRIL (a proliferation-inducing ligand). We found that bortezomib treatment inhibited APRIL and CCL3. But the heme oxygenase-1 (HO-1) activator hemin attenuated the inhibitory effects of bortezomib on APRIL and CCL3. We induced mononuclear cells to differentiate into OCs, and the enzyme-linked immunosorbent assay showed that the more OCs differentiated, the higher the levels CCL3 secretions detected. Animal experiments showed that hemin promoted MM cell infiltration in mice. The weight and survival rate of tumor mice were associated with HO-1 expression. Immunohistochemical staining showed that HO-1, APRIL, and CCL3 staining were positively stained in the tumor infiltrating sites. Then, MM cells were transfected with L-HO-1/si-HO-1 expression vectors and cultured with an nuclear factor (NF)-kappa B (κB) pathway inhibitor, QNZ. The results showed that HO-1 was the upstream gene of APRIL, NF-κB, and CCL3. We showed that HO-1 could attenuate the inhibitory effect of bortezomib against the APRIL-NF-κB-CCL3 signaling pathways in MM cells, and the tolerance of MM cells to bortezomib and the promotion of bone destruction are related to HO-1.

Identification of 4-N-[2-(4-phenoxyphenyl)ethyl]quinazoline-4,6-diamine as a novel, highly potent and specific inhibitor of mitochondrial complex I

By probing the quinone substrate binding site of mitochondrial complex I with a focused set of quinazoline-based compounds, we identified substitution patterns as being critical for the observed inhibition. The structure activity relationship study also resulted in the discovery of the quinazoline 4-N-[2-(4-phenoxyphenyl)ethyl]quinazoline-4,6-diamine (EVP4593) as a highly potent inhibitor of the multisubunit membrane protein. EVP4593 specifically and effectively reduces the mitochondrial complex I-dependent respiration with no effect on the respiratory chain complexes II-IV. Similar to established Q-site inhibitors, EVP4593 elicits the release of reactive oxygen species at the flavin site of mitochondrial complex I. Recently, EVP4593 was nominated as a lead compound for the treatment of Huntingtons disease. Our results challenge the postulated primary mode-of-action of EVP4593 as an inhibitor of NF-κB pathway activation and/or store-operated calcium influx.

Antimony-Resistant Leishmania donovani Exploits miR-466i To Deactivate Host MyD88 for Regulating IL-10/IL-12 Levels during Early Hours of Infection

Infection with antimony-resistant Leishmania donovani (Sb(R)LD) induces aggressive pathology in the mammalian hosts as compared with ones with antimony-sensitive L. donovani (Sb(S)LD) infection. Sb(R)LD, but not Sb(S)LD, interacts with TLR2/TLR6 to induce IL-10 by exploiting p50/c-Rel subunits of NF-κB in infected macrophages (Mϕs). Most of the TLRs exploit the universal adaptor protein MyD88 to activate NF-κB. We now show that infection of Mϕs from MyD88(-/-) mice with Sb(R)LD gave rise to significantly higher intracellular parasite number coupled with elevated IL-10/IL-12 ratio in the culture supernatant as compared with infection in wild type (WT) Mϕs. Τhese attributes were not seen with Sb(S)LD in similar experiments. Further, Sb(R)LD infection upregulated miR-466i, which binds with 3'-untranslated region, leading to the downregulation of MyD88. Infection of MyD88(-/-) Mϕ or IL-12(-/-) Mϕ with Sb(R)LD induced IL-10 surge at 4 h, whereas the same in WT Mϕ started from 12 h. Thus, absence of IL-12 in MyD88(-/-) mice favored early binding of NF-κB subunits to the IL-10 promoter, resulting in IL-10 surge. Infection of MyD88(-/-) mice with Sb(R)LD showed significantly higher organ parasites coupled with ill-defined and immature hepatic granulomas, whereas in WT mice there were less organ parasites and the granulomas were well defined. From the survival kinetics it was observed that Sb(R)LD-infected MyD88(-/-) mice died by 60 d postinfection, whereas the WT mice continued to survive. Our results demonstrate that Sb(R)LD has evolved a unique strategy to evade host antileishmanial immune repertoire by manipulating host MyD88 to its advantage.

Store-operated calcium entry promotes the degradation of the transcription factor Sp4 in resting neurons

Calcium (Ca(2+)) signaling activated in response to membrane depolarization regulates neuronal maturation, connectivity, and plasticity. Store-operated Ca(2+) entry (SOCE) occurs in response to depletion of Ca(2+) from endoplasmic reticulum (ER), mediates refilling of this Ca(2+) store, and supports Ca(2+) signaling in nonexcitable cells. We report that maximal activation of SOCE occurred in cerebellar granule neurons cultured under resting conditions and that this Ca(2+) influx promoted the degradation of transcription factor Sp4, a regulator of neuronal morphogenesis and function. Lowering the concentration of extracellular potassium, a condition that reduces neuronal excitability, stimulated depletion of intracellular Ca(2+) stores, resulted in the relocalization of the ER Ca(2+) sensor STIM1 into punctate clusters consistent with multimerization and accumulation at junctions between the ER and plasma membrane, and induced a Ca(2+) influx with characteristics of SOCE. Compounds that block SOCE prevented the ubiquitylation and degradation of Sp4 in neurons exposed to a low concentration of extracellular potassium. Knockdown of STIM1 blocked degradation of Sp4, whereas expression of constitutively active STIM1 decreased Sp4 abundance under depolarizing conditions. Our findings indicated that, in neurons, SOCE is induced by hyperpolarization, and suggested that this Ca(2+) influx pathway is a distinct mechanism for regulating neuronal gene expression.

Activation of nucleotide oligomerization domain containing protein 1 induces lipolysis through NF-κB and the lipolytic PKA activation in 3T3-L1 adipocytes

Obesity is associated with chronic inflammation. Toll-like receptors (TLR) and NOD-like receptors (NLR) are two families of pattern recognition receptors that play important roles in the immune response and inflammation in adipocytes. Activation of TLR4 has been shown to stimulate lipolysis from adipose tissue or adipocytes. However, effects of activation of nucleotide-oligomerization domain containing protein 1 (NOD1), one of the prominent members of NLRs, on adipocyte lipolysis have not been studied. Here we report that NOD1 activation by the synthetic ligands (Tri-DAP and C12-iEDAP) stimulated lipolysis in 3T3-L1 adipocytes in a time- and dose-dependent manner. C12-iEDAP-induced lipolysis was attenuated with NOD1 siRNA knockdown, demonstrating the specificity of the effects. Moreover, inhibition of the protein kinase A (PKA)/hormone sensitive lipase (HSL) and NF-κB pathways by the pharmacological inhibitors attenuated the lipolytic effects of C12-iEDAP. Furthermore, we show NOD1 activation induced PKA activation independent of cAMP production and inhibition of NF-κB pathways attenuated phosphorylation of selected PKA lipolytic targets (phosphorylation of Perilipin Ser 517 and HSL Ser 563). Taken together, our results demonstrate a novel role of NOD1 activation, via NF-κB/PKA lipolytic activation, in inducing lipolysis in adipocytes and suggest that NOD1 activation may contribute to dyslipidemia in obesity.

Histidine supplementation improves insulin resistance through suppressed inflammation in obese women with the metabolic syndrome: a randomised controlled trial

AIMS/HYPOTHESIS

Increased inflammation and oxidative stress are associated with insulin resistance (IR) and metabolic disorders. Serum histidine levels are lower and are negatively associated with inflammation and oxidative stress in obese women. The objective of this study was to evaluate the efficacy of histidine supplementation on IR, inflammation, oxidative stress and metabolic disorders in obese women with the metabolic syndrome (MetS).

METHODS

A total of 100 obese women aged 33-51 years with BMI ≥ 28 kg/m² and diagnosed with MetS were included following a health examination in the community hospital in this randomised, double-blinded, placebo-controlled trial. Participants were allocated to interventions by an investigator using sequentially numbered sealed envelopes and received 4 g/day histidine (n = 50) or identical placebo (n = 50) for 12 weeks. Participants then attended the same clinic every 2 weeks for scheduled interviews and to count tablets returned. Serum histidine, HOMA-IR, BMI, waist circumference, fat mass, serum NEFA, and variables connected to inflammation and oxidative stress were measured at baseline and 12 weeks. Participants, examining physicians and investigators assessing the outcomes were blinded to group assignment. In addition, the inflammatory mechanisms of histidine were also explored in adipocytes.

RESULTS

At 12 weeks, a total of 92 participants completed this trail. Compared with the placebo group (n = 47), histidine supplementation significantly decreased HOMA-IR (-1.09 [95% CI -1.49, -0.68]), BMI (-0.86 kg/m² [95% CI -1.55, -0.17]), waist circumference (-2.86 cm [95% CI -3.86, -1.86]), fat mass (-2.71 kg [95% CI -3.69, -1.73]), serum NEFA (-173.26 μmol/l [95% CI -208.57, -137.94]), serum inflammatory cytokines (TNF-α, -3.96 pg/ml [95% CI -5.29, -2.62]; IL-6, -2.15 pg/ml [95% CI -2.52, -1.78]), oxidative stress (superoxide dismutase, 17.84 U/ml [95% CI 15.03, 20.65]; glutathione peroxidase, 13.71 nmol/ml [95% CI 9.65, 17.78]) and increased serum histidine and adiponectin by 18.23 μmol/l [95% CI 11.74, 24.71] and 2.02 ng/ml [95% CI 0.60, 3.44] in histidine supplementation group (n = 45), respectively. There were significant correlations between changes in serum histidine and changes of IR and its risk factors. No side effects were observed during the intervention. In vitro study indicated that histidine suppresses IL6 and TNF mRNA expression and nuclear factor kappa-B (NF-κB) protein production in palmitic acid-induced adipocytes in a dose-dependent manner, and these changes were diminished by an inhibitor of NF-κB.

CONCLUSIONS/INTERPRETATION

Histidine supplementation could improve IR, reduce BMI, fat mass and NEFA and suppress inflammation and oxidative stress in obese women with MetS; histidine could improve IR through suppressed pro-inflammatory cytokine expression, possibly by the NF-κB pathway, in adipocytes.

Peroxynitrite mediates disruption of Ca2+ homeostasis by carbon monoxide via Ca2+ ATPase degradation

AIM

Sublethal carbon monoxide poisoning causes prolonged neurological damage involving oxidative stress. Given the central role of Ca(2+) homeostasis and its vulnerability to stress, we investigated whether CO disrupts neuronal Ca(2+) homeostasis.

RESULTS

Cytosolic Ca(2+) transients evoked by muscarine in SH-SY5Y cells were prolonged by CO (applied via the donor CORM-2), and capacitative Ca(2+) entry (CCE) was dramatically enhanced. Ca(2+) store mobilization by cyclopiazonic acid was similarly augmented, as was the subsequent CCE, and that evoked by thapsigargin. Ca(2+) rises evoked by depolarization were also enhanced by CO, and Ca(2+) levels often did not recover in its presence. CO increased intracellular nitric oxide (NO) and all effects of CO were prevented by inhibiting NO formation. However, NO donors did not mimic the effects of CO. The antioxidant ascorbic acid inhibited effects of CO on Ca(2+) signaling, as did the peroxynitrite scavenger, FeTPPS, and CO increased peroxynitrite formation. Finally, CO caused significant loss of plasma membrane Ca(2+)ATPase (PMCA) protein, detected by Western blot, and this was also observed in brain tissue of rats exposed to CO in vivo.

INNOVATION

The cellular basis of CO-induced neurotoxicity is currently unknown. Our findings provide the first data to suggest signaling pathways through which CO causes neurological damage, thereby opening up potential targets for therapeutic intervention.

CONCLUSION

CO stimulates formation of NO and reactive oxygen species which, via peroxynitrite formation, inhibit Ca(2+) extrusion via PMCA, leading to disruption of Ca(2+) signaling. We propose this contributes to the neurological damage associated with CO toxicity.

Relationships between the amyloid precursor protein and its various proteolytic fragments and neuronal systems

Alzheimer's disease (AD) is a progressive neurodegenerative disease and in its familial form is associated with mutations in the amyloid precursor protein (APP) and the presenilins (PSs). Much data regarding the interactions of APP, its proteolytic fragments and PS have been generated, expanding our understanding of the roles of these proteins in mechanisms underlying cognitive function and revealing many complex relationships with wide ranging cellular systems. In this review, we examine the multiple interactions of APP and its proteolytic fragments with other neuronal systems in terms of feedback loops and use these relationships to build a map. We highlight the complexity involved in the APP proteolytic system and discuss alternative perspectives on the roles of APP and its proteolytic fragments in dynamic processes associated with disease progression in AD. We highlight areas where data are missing and suggest potential confounding factors. We suggest that a systems biology approach enhances representations of the data and may be more useful in modelling both normal cognition and disease processes.

Neuronal store-operated calcium entry pathway as a novel therapeutic target for Huntington's disease treatment

Huntington's disease (HD) is a neurodegenerative disorder caused by a polyglutamine expansion within Huntingtin (Htt) protein. In the phenotypic screen we identified a class of quinazoline-derived compounds that delayed a progression of a motor phenotype in transgenic Drosophila HD flies. We found that the store-operated calcium (Ca(2+)) entry (SOC) pathway activity is enhanced in neuronal cells expressing mutant Htt and that the identified compounds inhibit SOC pathway in HD neurons. The same compounds exerted neuroprotective effects in glutamate-toxicity assays with YAC128 medium spiny neurons primary cultures. We demonstrated a key role of TRPC1 channels in supporting SOC pathway in HD neurons. We concluded that the TRPC1-mediated neuronal SOC pathway constitutes a novel target for HD treatment and that the identified compounds represent a novel class of therapeutic agents for treatment of HD and possibly other neurodegenerative disorders.

Inhibitory effect of a tyrosine-fructose Maillard reaction product, 2,4-bis(p-hydroxyphenyl)-2-butenal on amyloid-β generation and inflammatory reactions via inhibition of NF-κB and STAT3 activation in cultured astrocytes and microglial BV-2 cells

BACKGROUND

Amyloidogenesis is linked to neuroinflammation. The tyrosine-fructose Maillard reaction product, 2,4-bis(p-hydroxyphenyl)-2-butenal, possesses anti-inflammatory properties in cultured macrophages, and in an arthritis animal model. Because astrocytes and microglia are responsible for amyloidogenesis and inflammatory reactions in the brain, we investigated the anti-inflammatory and anti-amyloidogenic effects of 2,4-bis(p-hydroxyphenyl)-2-butenal in lipopolysaccharide (LPS)-stimulated astrocytes and microglial BV-2 cells.

METHODS

Cultured astrocytes and microglial BV-2 cells were treated with LPS (1 μg/ml) for 24 h, in the presence (1, 2, 5 μM) or absence of 2,4-bis(p-hydroxyphenyl)-2-butenal, and harvested. We performed molecular biological analyses to determine the levels of inflammatory and amyloid-related proteins and molecules, cytokines, Aβ, and secretases activity. Nuclear factor-kappa B (NF-κB) DNA binding activity was determined using gel mobility shift assays.

RESULTS

We found that 2,4-bis(p-hydroxyphenyl)-2-butenal (1, 2, 5 μM) suppresses the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as the production of nitric oxide (NO), reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in LPS (1 μg/ml)-stimulated astrocytes and microglial BV-2 cells. Further, 2,4-bis(p-hydroxyphenyl)-2-butenal inhibited the transcriptional and DNA binding activity of NF-κB--a transcription factor that regulates genes involved in neuroinflammation and amyloidogenesis via inhibition of IκB degradation as well as nuclear translocation of p50 and p65. Consistent with the inhibitory effect on inflammatory reactions, 2,4-bis(p-hydroxyphenyl)-2-butenal inhibited LPS-elevated Aβ42 levels through attenuation of β- and γ-secretase activities. Moreover, studies using signal transducer and activator of transcription 3 (STAT3) siRNA and a pharmacological inhibitor showed that 2,4-bis(p-hydroxyphenyl)-2-butenal inhibits LPS-induced activation of STAT3.

CONCLUSIONS

These results indicate that 2,4-bis(p-hydroxyphenyl)-2-butenal inhibits neuroinflammatory reactions and amyloidogenesis through inhibition of NF-κB and STAT3 activation, and suggest that 2,4-bis(p-hydroxyphenyl)-2-butenal may be useful for the treatment of neuroinflammatory diseases like Alzheimer's disease.

Conditional and specific inhibition of NF-κB in mouse pancreatic β cells prevents cytokine-induced deleterious effects and improves islet survival posttransplant

BACKGROUND

Islets are susceptible to damage by proinflammatory cytokines via activation of transcription factor NF-κB. We hypothesized that inhibition of NF-κB activity will decrease cytokine-mediated β-cell injury and improve islet transplant functional outcome.

METHODS

We created a transgenic mouse expressing a degradation resistant N-terminally deleted IκBα (ΔNIκBα) under the control of a commercially available tetracycline-controlled transcriptional activation system using a rat insulin promoter. Isolated islets from transgenic and control mouse strains were exposed to cytokines in vitro and assayed or transplanted.

RESULTS

Western blot analysis showed that ΔNIκBα was significantly increased with doxycycline treatment. Cytokine-induced NF-κB activation was significantly decreased in transgenic (0.065 ± 0.013 absorbance value/μg protein) vs control islets (0.128 ± 0.006; P < .05). Suppression of cytokine-mediated NF-κB activity decreased expression of inducible nitric oxide synthase, monocyte chemoattractant protein-1, and interferon-γ inducible protein-10 RNA transcripts, and significantly decreased nitric oxide production in transgenic islets (0.084 ± 0.043 μM/μg protein) vs. controls (0.594 ± 0.174; P < .01). The insulin stimulation index in islets exposed to cytokines was higher in transgenic vs controls (1.500 ± 0.106 vs 0.800 ± 0.098; P < .01). Syngeneic transplants of a marginal mass of intraportally infused transgenic islets resulted in a reversion to euglycemia in 69.2% of diabetic recipients at a mean of 7.8 ± 1.1 days vs. 35.7% of control islet recipients reverting at a mean of 15.8 ± 2.9 days (P < .05).

CONCLUSION

Conditional and specific suppression of NF-κB activity in β cells protected islets from cytokine-induced dysfunction in vitro and in vivo. These results provide a proof of principle that inhibition of NF-κB activity in donor islets enhances function and improves the outcome of islet transplantation.

Interleukin 22 signaling promotes cell growth in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a specific type of aggressive B-cell non-Hodgkin lymphoma. We recently found that IL-22RA1, one of the two subunits of the interleukin 22 (IL-22) receptor, is expressed in MCL cell lines but not benign lymphocytes. In view of normal functions of IL-22 signaling, we hypothesized that the aberrant expression of IL-22RA1 may contribute to the deregulation of various cell signaling pathways, thereby promoting cell growth in MCL. In this study, we first demonstrated the expression of IL-22RA1 in all three MCL cell lines and eight frozen tumors examined using reverse transcription-polymerase chain reaction and Western blot analysis. In support of the concept that IL-22 signaling is biologically important in MCL, we found that MCL cells treated with recombinant IL-22 had a significant increase in cell growth that was associated with STAT3 activation. To investigate the mechanism underlying the aberrant expression of IL-22RA1, we analyzed the gene promoter of IL-22RA1, and we found multiple binding sites for NF-κB, a transcriptional factor strongly implicated in the pathogenesis of MCL. Pharmacologic inhibition of NF-κB resulted in a substantial reduction in the level of IL-22RA1 protein expression in MCL cells. To conclude, IL-22RA is aberrantly expressed in MCL, and we have provided evidence that IL-22 signaling contributes to the pathogenesis of MCL.

High-throughput sequencing identifies STAT3 as the DNA-associated factor for p53-NF-kappaB-complex-dependent gene expression in human heart failure

BACKGROUND

Genome-wide maps of DNA regulatory elements and their interaction with transcription factors may form a framework for understanding regulatory circuits and gene expression control in human disease, but how these networks, comprising transcription factors and DNA-binding proteins, form complexes, interact with DNA and modulate gene expression remains largely unknown.

METHODS

Using microRNA-21 (mir-21), which is an example of genes that are regulated in heart failure, we performed chromatin immunoprecipitation (ChIP) assays to determine the occupancy of transcription factors at this genetic locus. Tissue ChIP was further performed using human hearts and genome-wide occupancies of these transcription factors were analyzed by high-throughput sequencing.

RESULTS

We show that the transcription factor p53 piggy-backs onto NF-kappaB/RELA and utilizes the kappaB-motif at a cis-regulatory region to control mir-21 expression. p53 behaves as a co-factor in this complex because despite a mutation in its DNA binding domain, mutant p53 was still capable of binding RELA and the cis-element, and inducing mir-21 expression. In dilated human hearts where mir-21 upregulation was previously demonstrated, the p53-RELA complex was also associated with this cis-element. Using high-throughput sequencing, we analyzed genome-wide binding sites for the p53-RELA complex in diseased and control human hearts and found a significant overrepresentation of the STAT3 motif. We further determined that STAT3 was necessary for the p53-RELA complex to associate with this cis-element and for mir-21 expression.

CONCLUSIONS

Our results uncover a mechanism by which transcription factors cooperate in a multi-molecular complex at a cis-regulatory element to control gene expression.

The antidiuretic neurohormone RhoprCAPA-2 downregulates fluid transport across the anterior midgut in the blood-feeding insect Rhodnius prolixus

Osmotic balance in insects is regulated by the excretory system, consisting of Malpighian tubules and the gut under the control of diuretic and antidiuretic factors. Terrestrial insects must conserve water, and antidiuresis is the norm, only interrupted by brief diuretic periods. Surprisingly, little is known about antidiuresis in insects. Two antidiuretic strategies have been described. The first antidiuretic mechanism involves the reabsorption of fluid from the primary urine in the hindgut. More recently, a second antidiuretic strategy was reported, consisting of inhibition of primary urine formation by the Malpighian tubules. Recently, we isolated, characterized, and cloned the gene encoding for the antidiuretic neurohormone (the neuropeptide RhoprCAPA-2) acting on the Malpighian tubules of Rhodnius prolixus. Here we describe a third, novel mechanism central to the antidiuretic strategy of R. prolixus, the inhibition of ion and fluid transport across the anterior midgut by RhoprCAPA-2. Our results show that RhoprCAPA-2 (1 micromol/l) reduces serotonin-stimulated fluid transport from 83 +/- 11 to 12 +/- 12 nl/min and equivalent short-circuit current from 20 +/- 4 to 5 +/- 0.7 microA/cm(2) in diuretic hormone-stimulated anterior midgut. RhoprCAPA-2 appears to function independently of intracellular cGMP or Ca(2+) in the midgut. Thus, the antidiuretic neurohormone RhoprCAPA-2 has multiple target tissues, and we hypothesize that RhoprCAPA-2 functions to coordinate the transport activity of the anterior midgut and Malpighian tubules so that the rate of fluid transport into the haemolymph by the anterior midgut matches the transport rate of Malpighian tubules to maintain the volume and ion composition of haemolymph.

Green tea (-)-epigallocatechin-3-gallate inhibits beta-amyloid-induced cognitive dysfunction through modification of secretase activity via inhibition of ERK and NF-kappaB pathways in mice

Alzheimer's disease (AD) is characterized by the extracellular deposition of beta-amyloid peptide (Abeta) in cerebral plaques. Abeta is derived from the beta-amyloid precursor protein (APP) by the enzymes alpha-, beta- and gamma-secretase. Compounds that enhance alpha-secretase, but inhibit beta- or gamma-secretase activity, have therapeutic potential in the treatment of AD. Green tea, or its major polyphenolic compound, has been shown to have neuroprotective effects. In this study, we investigated the possible effects of (-)-epigallocatechin-3-gallate (EGCG) on memory dysfunction caused by Abeta through the change of Abeta-induced secretase activities. Mice were pretreated with EGCG (1.5 or 3 mg/kg body weight in drinking water) for 3 wk before intracerebroventricular administration of 0.5 microg Abeta(1-42). EGCG dose-dependently reduced the Abeta(1-42)-induced memory dysfunction, which was evaluated using passive avoidance and water maze tests. Abeta(1-42) induced a decrease in brain alpha-secretase and increases in both brain beta- and gamma-secretase activities, which were reduced by EGCG. In the cortex and the hippocampus, expression of the metabolic products of the beta- and gamma-secretases from APP, C99, and Abeta also were dose-dependently suppressed by EGCG. Paralleled with the suppression of beta- and gamma-secretases by EGCG, we found that EGCG inhibited the activation of extracellular signal-regulated kinase and nuclear transcription factor-kappaB in the Abeta(1-42)-injected mouse brains. In addition, EGCG inhibited Abeta(1-42)-induced apoptotic neuronal cell death in the brain. To further test the ability of EGCG to affect memory, EGCG (3 mg/kg body weight) was administered in drinking water for 1 wk to genetically developed preseniline 2 (PS2) mutant AD mice. Compared with untreated mutant PS2 AD mice, treatment with EGCG enhanced memory function and brain alpha-secretase activity but reduced brain beta- and gamma-secretase activities as well as Abeta levels. Moreover, EGCG inhibited the fibrillization of Abeta in vitro with a half maximal inhibitory concentration of 7.5 mg/L. These studies suggest that EGCG may be a beneficial agent in the prevention of development or progression of AD.

Morphine exacerbates HIV-1 Tat-induced cytokine production in astrocytes through convergent effects on [Ca(2+)](i), NF-kappaB trafficking and transcription

Astroglia are key cellular sites where opiate drug signals converge with the proinflammatory effects of HIV-1 Tat signals to exacerbate HIV encephalitis. Despite this understanding, the molecular sites of convergence driving opiate-accelerated neuropathogenesis have not been deciphered. We therefore explored potential points of interaction between the signaling pathways initiated by HIV-1 Tat and opioids in striatal astrocytes. Profiling studies screening 152 transcription factors indicated that the nuclear factor-kappa B (NF-κB) subunit, c-Rel, was a likely candidate for Tat or Tat plus opiate-induced increases in cytokine and chemokine production by astrocytes. Pretreatment with the NF-κB inhibitor parthenolide provided evidence that Tat±morphine-induced release of MCP-1, IL-6 and TNF-α by astrocytes is NF-κB dependent. The nuclear export inhibitor, leptomycin B, blocked the nucleocytoplasmic shuttling of NF-κB; causing p65 (RelA) accumulation in the nucleus, and significantly attenuated cytokine production in Tat±morphine exposed astrocytes. Similarly, chelating intracellular calcium ([Ca²⁺]_i) blocked Tat±morphine-evoked MCP-1 and IL-6 release, while artificially increasing the concentration of extracellular Ca²⁺ reversed this effect. Taken together, these results demonstrate that: 1) exposure to Tat±morphine is sufficient to activate NF-κB and cytokine production, 2) the release of MCP-1 and IL-6 by Tat±morphine are highly Ca²⁺-dependent, while TNF-α appears to be less affected by the changes in [Ca²⁺]_i, and 3) in the presence of Tat, exposure to opiates augments Tat-induced NF-κB activation and cytokine release through a Ca²⁺-dependent pathway.

Differential involvement of TNF alpha in hypoxic suppression of astrocyte glutamate transporters

Transporter-mediated glutamate uptake is a principal function of astrocytes. Our previous studies have shown that this process is compromised under hypoxic conditions through the NF-kappaB mediated inhibition of expression of the glutamate transporters EAAT-1 and EAAT-2. Here, we demonstrate that identical conditions of hypoxia (1% O(2), 24 h) lead to a dramatic increase in TNFalpha production from astrocytes without altering their viability. This hypoxia-evoked production of TNFalpha was prevented in the presence of any of three mechanistically distinct NF-kappaB inhibitors. Exogenous application of TNFalpha was without effect on EAAT-1 expression as determined by Western blotting, but mimicked the effects of hypoxia to suppress expression of EAAT-2. Furthermore thalidomide, which prevents TNFalpha production, was without effect on hypoxic suppression of EAAT-1 but prevented hypoxic suppression of EAAT-2. These data indicate that regulation of glutamate transporter expression in astrocytes by hypoxia is subtype specific. Regulation of both EAAT-1 and EAAT-2 is mediated by NF-kappaB, and this transcriptional regulator is also required for increased production of TNFalpha. However, while TNFalpha is essential for hypoxic suppression of EAAT-2, hypoxic modulation of EAAT-1 expression is unaffected by this cytokine.

Laminin activates NF-kappaB in Schwann cells to enhance neurite outgrowth

Extracellular matrix (ECM) molecules and Schwann cells (SCs) are important components of peripheral nerve regeneration. In this study, the role of the transcription factor nuclear factor kappa B (NF-kappaB) in SC activation in response to laminin and the subsequent effect on in vitro neurite outgrowth was investigated. Immunocytochemistry and Western blot analysis showed that compared with poly-d-lysine (PDL), laminin enhanced the phosphorylation of IkappaB and p65 NF-kappaB signalling proteins in SCs. Phospho NF-kappaB-p65 was localised to the nucleus indicating activation of NF-kappaB. To assess the functional effect of NF-kappaB activation, SCs plated on PDL or laminin were pre-treated with NF-kappaB inhibitors, 6-amino-4-(4-phenoxyphenylethylamino)quinazoline (QNZ) or Z-leu-leu-leu-CHO (MG-132) before NG108-15 neuronal cells were seeded on the SC monolayer. After 24h co-culture in the absence of inhibitors, SCs seeded on laminin enhanced the mean number and length of neurites extended by NG108-15 cells (1.87+/-0.13 neurites; 238.74+/-8.53microm) compared with those cultured in the presence of SCs and PDL (1.26+/-0.07 neurites; 157.57+/-9.80microm). At 72h, neurite length had further increased to 321.83+/-6.60microm in the presence of SCs and laminin. Inhibition of NF-kappaB completely abolished the effect of laminin on SC evoked neurite outgrowth at 24h and reduced the enhancement of neurite length by over 60% at 72h. SC proliferation was unaffected by NF-kappaB inhibition suggesting that the NF-kappaB signalling pathway plays a discrete role in the activation of SCs and their neurotrophic potential.