Abeta Aggregation Research Articles

The ryanodine receptor-calstabin interaction stabilizer S107 protects hippocampal neurons from GABAergic synaptic alterations induced by Abeta42 oligomers.

The oligomeric form of the peptide amyloid beta 42 (Abeta42) contributes to the development of synaptic abnormalities and cognitive impairments associated with Alzheimer's disease (AD). To date, there is a gap in knowledge regarding how Abeta42 alters the elementary parameters of GABAergic synaptic function. Here we found that Abeta42 increased the frequency and amplitude of miniature GABAergic currents as well as the amplitude of evoked inhibitory postsynaptic currents. When we focused on paired pulse depression (PPD) to establish whether GABA release probability was affected by Abeta42, we did not observe any significant change. On the other hand, a more detailed investigation of the presynaptic effects induced by Abeta42 by means of multiple probability fluctuation analysis and cumulative amplitude analysis showed an increase in both the size of the readily releasable pool responsible for synchronous release and the number of release sites. We further explored whether ryanodine receptors (RyRs) contributed to exacerbating these changes by stabilizing the interaction between RyRs and the accessory protein calstabin. We observed that the RyR-calstabin interaction stabilizer S107 restored the synaptic parameters to values comparable to those measured in control conditions. In conclusion, our results clarify the mechanisms of potentiation of GABAergic synapses induced by Abeta42. We further suggest that RyRs are involved in the control of synaptic activity during the early stage of AD onset and that their stabilization could represent a new therapeutical approach for AD treatment. KEY POINTS: Accumulation of the peptide amyloid beta 42 (Abeta42) is a key characteristic of Alzheimer's disease (AD) and causes synaptic dysfunctions. To date, the effects of Abeta42 accumulation on GABAergic synapses are poorly understood. The findings reported here suggest that, similarly to what is observed on glutamatergic synapses, Abeta42 modifies GABAergic synapses by targeting ryanodine receptors and causing calcium dysregulation. The GABAergic impairments can be restored by the ryanodine receptor-calstabin interaction stabilizer S107. Based on this research, RyRs stabilization may represent a novel pharmaceutical strategy for preventing or delaying AD.

Semax, a Synthetic Regulatory Peptide, Affects Copper-Induced Abeta Aggregation and Amyloid Formation in Artificial Membrane Models

Alzheimer’s disease, the most common form of dementia, is characterized by the aggregation of amyloid beta protein (Aβ). The aggregation and toxicity of Aβ are strongly modulated by metal ions and phospholipidic membranes. In particular, Cu2+ ions play a pivotal role in modulating Aβ aggregation. Although in the last decades several natural or synthetic compounds were evaluated as candidate drugs, to date, no treatments are available for the pathology. Multifunctional compounds able to both inhibit fibrillogenesis, and in particular the formation of oligomeric species, and prevent the formation of the Aβ:Cu2+ complex are of particular interest. Here we tested the anti-aggregating properties of a heptapeptide, Semax, an ACTH-like peptide, which is known to form a stable complex with Cu2+ ions and has been proven to have neuroprotective and nootropic effects. We demonstrated through a combination of spectrofluorometric, calorimetric, and MTT assays that Semax not only is able to prevent the formation of Aβ:Cu2+ complexes but also has anti-aggregating and protective properties especially in the presence of Cu2+. The results suggest that Semax inhibits fiber formation by interfering with the fibrillogenesis of Aβ:Cu2+ complexes.

CSF proteomic changes in pre‐preclinical Alzheimer’s disease: A monozygotic twin study

AbstractBackgroundDrivers of amyloid beta (abeta) aggregation in early Alzheimer’s disease (AD) are poorly understood. Studies in autosomal dominant AD suggested that increased abeta production is an early feature. We aimed to identify early AD changes in the CSF proteome using a monozygotic discordant twin‐pair model. This model provides a proxy for disease progression as twins from pairs discordant for abeta aggregation who have normal abeta (a‐) can be considered to in an earlier stage of AD than discordant twins who have abnormal abeta (a+). We investigated whether CSF proteins associated with abeta aggregation in discordant a‐ twins correlated with markers of amyloid production using cross‐twin cross‐trait (CTCT) analysis.MethodWe included 48 cognitively normal monozygotic twin pairs from the EMIF PreclinAD study. We performed CSF proteomics by OLINK multiplex panels (673 proteins), and ELISA’s for tau, abeta40, and BACE1. We defined abeta aggregation by visual read on dynamic [18F]flutemetamol PET images. We compared CSF protein levels of twins that had both normal abeta (concordant a‐) with those of discordant twins with normal abeta (discordant a‐) and those of discordant twins with abnormal abeta (discordant a+). Enrichment analysis of proteins that differed between groups was performed using Gene Ontology. In CTCT analysis in the total cohort, we correlated protein levels of one twin with the concentration of abeta40 and BACE1, markers of abeta production, in the co‐twin. A significant CTCT correlation suggests that proteins have a common genetic background. Analysis were corrected for age and sex.ResultAverage age was 68 years (range 61‐86). Forty‐one pairs were concordant abeta‐, and 7 twin pairs were discordant for abeta aggregation. Relative to concordant a‐ twins, discordant a‐ twins showed a decrease in 1 protein and an increase in 74 proteins. Of the increased proteins, 61 were also increased in discordant a+ twins (figure). These proteins were enriched for nervous system development, immune activation and related processes. They correlated with abeta40 and BACE1 in CTCT analysis.ConclusionAround the onset of amyloid aggregation there is an increase in proteins involved in nervous system development and immune activation, which is related to increased amyloid production.

Caenorhabditis elegans hub genes that respond to amyloid beta are homologs of genes involved in human Alzheimer's disease.

The prominent characteristic of Alzheimer’s disease (AD) is the accumulation of amyloid beta (Abeta) proteins in the form of plaques that cause molecular and cellular alterations in the brain. Due to the paucity of brain samples of early-stage Abeta aggregation, animal models have been developed to study early events in AD. Caenorhabditis elegans is a genetically tractable animal model for AD. Here, we used transcriptomic data, network-based protein-protein interactions and weighted gene co-expression network analysis (WGCNA), to detect modules and their gene ontology in response to Abeta aggregation in C. elegans. Additionally, hub genes and their orthologues in human and mouse were identified to study their relation to AD. We also found several transcription factors (TFs) responding to Abeta accumulation. Our results show that Abeta expression in C. elegans relates to general processes such as molting cycle, locomotion, and larval development plus AD-associated processes, including protein phosphorylation, and G-protein coupled receptor-regulated pathways. We reveal that many hub genes and TFs including ttbk-2, daf-16, and unc-49 have human and mouse orthologues that are directly or potentially associated with AD and neural development. In conclusion, using systems biology we identified important genes and biological processes in C. elegans that respond to Abeta aggregation, which could be used as potential diagnostic or therapeutic targets. In addition, because of evolutionary relationship to AD in human, we suggest that C. elegans is a useful model for studying early molecular events in AD.

Abstract # 2052 Serum amyloid A inhibits the clearance of amyloid beta from the brain

Alzheimer’s disease (AD) is the most common cause of dementia, and is thought to arise due to the abnormal accumulation of amyloid beta (Abeta) and tau in the brain. In the healthy brain, Abeta is predominantly cleared by transporters at the blood-brain barrier (BBB). Transporter deficiencies promote Abeta accumulation in the brain, which contributes to AD. Systemic inflammation is a risk factor for AD, and we have previously shown that lipopolysaccharide (LPS)-induced inflammation inhibits Abeta clearance from the brain (efflux). However, the contributing mechanisms of inflammation to Abeta efflux deficiency are not completely understood. Serum amyloid A (SAA) is an acute phase lipoprotein that is highly increased in blood following LPS treatment, and crosses the BBB. SAA has also been implicated in AD, but its mechanistic contributions are unclear. We hypothesized that SAA causes Abeta accumulation in the brain by inhibiting its efflux across the BBB. To test this, we assessed efflux of 125I-Abeta1-42 injected into the lateral ventricle of mice in the presence or absence of two isoforms of SAA-SAA1 and SAA2. We found that Abeta efflux was inhibited by SAA2, but not SAA1, suggesting an isoform-specific mechanism of Abeta efflux inhibition. Our findings suggest that SAA could be an important molecular link between systemic inflammation and AD.

L‐proline and betaine inhibit extracellular enzymes mediated abeta 1‐42 aggregation, oxidative stress, and toxicity

AbstractExtracellular amyloid plaques are characteristics of Alzheimer's disease (AD). The amyloid plaques mainly consist of amyloid‐β (abeta) fragments. Extracellular biomolecules play a key role in abeta aggregation and subsequent plaque formation during AD. Among them, extracellular enzymes are known to induce abeta aggregation by catalyzing the crosslinking of abeta proteins. Although several therapeutic strategies have been studied to combat AD, studies to treat extracellular enzymes mediated abeta aggregation and toxicity is not explored in detail yet. Here we study the potential of osmolyte molecules l‐proline and betaine to inhibit the abeta aggregation and toxicity promoted by extracellular enzymes transglutaminase and lysyl oxidase in vitro. Results reveal that l‐proline and betaine have the potential to inhibit extracellular matrix enzymes mediated abeta aggregation/fibril formation and toxicity and oxidative stress in brain endothelial cells. Hence osmolytes could have the potential to modulate the effects of extracellular molecules during AD.

Identification of disulfiram as a secretase-modulating compound with beneficial effects on Alzheimer\u2019s disease hallmarks

ADAM10 is a metalloproteinase acting on the amyloid precursor protein (APP) as an alpha-secretase in neurons. Its enzymatic activity results in secretion of a neuroprotective APP cleavage product (sAPP-alpha) and prevents formation of the amyloidogenic A-beta peptides, major hallmarks of Alzheimer’s disease (AD). Elevated ADAM10 levels appeared to contribute to attenuation of A-beta-plaque formation and learning and memory deficits in AD mouse models. Therefore, it has been assumed that ADAM10 might represent a valuable target in AD therapy. Here we screened a FDA-approved drug library and identified disulfiram as a novel ADAM10 gene expression enhancer. Disulfiram increased ADAM10 production as well as sAPP-alpha in SH-SY5Y human neuronal cells and additionally prevented A-beta aggregation in an in vitro assay in a dose-dependent fashion. In addition, acute disulfiram treatment of Alzheimer model mice induced ADAM10 expression in peripheral blood cells, reduced plaque-burden in the dentate gyrus and ameliorated behavioral deficits. Alcohol-dependent patients are subjected to disulfiram-treatment to discourage alcohol-consumption. In such patients, enhancement of ADAM10 by disulfiram-treatment was demonstrated in peripheral blood cells. Our data suggest that disulfiram could be repurposed as an ADAM10 enhancer and AD therapeutic. However, efficacy and safety has to be analyzed in Alzheimer patients in the future.

Fucoidan inhibits amyloid-β-induced toxicity in transgenic Caenorhabditis elegans by reducing the accumulation of amyloid-β and decreasing the production of reactive oxygen species.

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. As the aging population is increasing, AD is becoming one of the leading causes of disability and death among the elderly. However, currently there is no cure for this disease. Fucoidan is a complex sulfated polysaccharide mainly found in brown seaweed. Recent studies have shown that fucoidan is neuroprotective and may have potential to be used for treating and/or preventing neurodegenerative diseases such as AD. In this study, we investigated the effects and possible mechanisms of fucoidan on Abeta induced toxicity in a transgenic Caenorhabditis elegans (C. elegans) AD model. The results showed that the supplementation of fucoidan alleviated the paralyzed phenotype induced by Abeta. The number of Abeta deposits in the AD animals was reduced by fucoidan treatment. Further analysis of the levels of Abeta showed that fucoidan significantly decreased the accumulation of Abeta in transgenic AD C. elegans. It was found that fucoidan treatment elevated the activity of proteosomes; therefore, fucoidan might decrease Abeta accumulation by promoting proteolysis. In addition, fucoidan treatment reduced the production of reactive oxygen species (ROS) stimulated by Abeta induction. These results suggested that fucoidan might exert its protective effects against Abeta-induced toxicity in transgenic AD C. elegans by reducing the accumulation of toxic Abeta and decreasing Abeta-induced production of ROS, thus ameliorating the progression of the AD phenotype.

Novel Curcumin loaded nanoparticles engineered for Blood-Brain Barrier crossing and able to disrupt Abeta aggregates

The formation of extracellular aggregates built up by deposits of β-amyloid (Aβ) is a hallmark of Alzheimer’s disease (AD). Curcumin has been reported to display anti-amyloidogenic activity, not only by inhibiting the formation of new Aβ aggregates, but also by disaggregating existing ones. However, the uptake of Curcumin into the brain is severely restricted by its low ability to cross the blood-brain barrier (BBB). Therefore, novel strategies for a targeted delivery of Curcumin into the brain are highly desired. Here, we encapsulated Curcumin as active ingredient in PLGA (polylactide-co-glycolic-acid) nanoparticles (NPs), modified with g7 ligand for BBB crossing. We performed in depth analyses of possible toxicity of these NPs, uptake, and, foremost, their ability to influence Aβ pathology in vitro using primary hippocampal cell cultures. Our results show no apparent toxicity of the formulated NPs, but a significant decrease of Aβ aggregates in response to Curcumin loaded NPs. We thus conclude that brain delivery of Curcumin using BBB crossing NPs is a promising future approach in the treatment of AD.

Vulnerability of primary neurons derived from Tg2576 Alzheimer mice to oxygen and glucose deprivation: role of intraneuronal amyloid-β accumulation and astrocytes.

ABSTRACTMicrovascular dysfunction is considered an integral part of Alzheimer disease (AD) pathogenesis, but the possible relationship between amyloid pathology, microvascular dysfunction and cell death is still unclear. In order to investigate the influence of intraneuronal amyloid-β (Aβ) accumulation on vulnerability to hypoxia, we isolated primary cortical neurons from Tg2576 (carrying the amyloid precursor protein APPSwe mutation) and wild-type fetal mice. We first demonstrated that neurons isolated from Tg2576 newborn mice show an increase in VEGFa mRNA expression and a decrease in the expression of the two VEGF receptors, Flt1 and Kdr, compared with wild-type cells. Moreover, APPSwe primary neurons displayed higher spontaneous and glutamate-induced cell death. We then deprived the cultures of oxygen and glucose (OGD) as an in vitro model of hypoxia. After OGD, APPSwe neurons display higher levels of cell death in terms of percentage of pyknotic/fragmented nuclei and mitochondrial depolarization, accompanied by an increase in the intraneuronal Aβ content. To explore the influence of intraneuronal Aβ peptide accumulation, we used the γ-secretase inhibitor LY450139, which showed that the reduction of the intracellular amyloid fully protects APPSwe neurons from OGD-induced degeneration. Conditioned medium from OGD-exposed APPSwe or wild-type astrocytes protected APPswe neurons but not wild-type neurons, during OGD. In conclusion, the presence of the mutated human APP gene, leading to the intracellular accumulation of APP and Aβ fragments, worsens OGD toxicity. Protection of APPSwe neurons can be obtained either using a γ-secretase inhibitor or astrocyte conditioned medium.

Introducing Euro-Glo, a rare earth metal chelate with numerous applications for the fluorescent localization of myelin and amyloid plaques in brain tissue sections

The vast majority of fluorochromes are organic in nature and none of the few existing chelates have been applied as histological tracers for localizing brain anatomy and pathology. New methodIn this study we have developed and characterized a Europium chelate with the ability to fluorescently label normal and pathological myelin in control and toxicant-exposed rats, as well as the amyloid plaques in aged AD/Tg mice. ResultsThis study demonstrates how Euro-Glo can be used for the detailed labeling of both normal myelination in the control rat as well as myelin pathology in the kainic acid exposed rat. In addition, this study demonstrates how E-G will label the shell of amyloid plaques in an AD/Tg mouse model of Alzheimer’s disease a red color, while the plaque core appears blue in color. The observed E-G staining pattern is compared with that of well characterized tracers specific for the localization of myelin (Black-Gold II), degenerating neurons (Fluoro-Jade C), A-beta aggregates (Amylo-Glo) and glycolipids (PAS). Comparisons with existing methodsThis study represents the first time a rare earth metal (REM) chelate has been used as a histochemical tracer in the brain. This novel tracer, Euro-Glo (E-G), exhibits numerous advantages over conventional organic fluorophores including high intensity emission, high resistance to fading, compatibility with multiple labeling protocols, high Stoke’s shift value and an absence of bleed-through of the signal through other filters. ConclusionsEuro-Glo represents the first fluorescent metal chelate to be used as a histochemical tracer, specifically to localize normal and pathological myelin as well as amyloid plaques.

Sex differences between APPswePS1dE9 mice in A-beta accumulation and pancreatic islet function during the development of Alzheimer's disease.

The pathogenesis of Alzheimer's disease (AD), a type of neurodegenerative disease characterized by learning and memory impairment, is often associated with pathological features, such as amyloid-beta (Aβ) accumulation and insulin resistance. The transgenic mouse, APPswePS1dE9 (APP/PS1), is one of the most commonly used animal models in pathogenesis studies of AD. The purpose of this study is to investigate the sex differences between APP/PS1 mice in the pathogenesis of AD. The impairment of glucose and insulin tolerance was found to develop earlier in male APP/PS1 mice than in females. Plasma insulin levels were significantly decreased in male APP/PS1 mice, while total cholesterol levels in male APP/PS1 mice were higher than those in females. Triglyceride levels in male mice in both the wild-type (WT) and APP/PS1 groups were higher than in their female littermates. Soluble and insoluble Aβ levels in female APP/PS1 mouse brains were higher than those in males. And the learning and memorizing abilities of female APP/PS1 mice were poorer than those of males. Our results concluded that there were sex differences in Aβ formation, pancreatic islet function and insulin sensitivity between male and female APP/PS1 mice during the pathogenesis of AD.

REGIONAL DISTRIBUTION OF AMYLOID-BETA, SOLUBLE APP AND SYNAPTIC MARKERS IN HUMAN BRAINS

We recently reported the strong regional association between postsynaptic markers and Abeta accumulation in human brains, suggesting that synapses play important roles in Abeta accumulation (Shinohara et al., Acta Neuropathologica 2013;125(4):535-547). To further reveal potential mechanism underlying the involvement of synapses in Abeta accumulation, we determined the regional distribution of soluble APPalpha and APPbeta by specific ELISAs and addressed their association with the regional distribution of Abeta, synaptic markers and other related molecules. Twelve brain regions including neocortical, limbic and subcortical areas were dissected from brains of non-demented individuals with or without Abeta accumulation (n = 27, age = 89.7 ± 9.4 years) and sporadic Alzheimer’s disease (AD) patients (n=19, age = 84.7 ± 7.8 years) extracted according to increasing insolubility by a sequential three-step method (TBS, Triton-X and guanidine). The levels of Abeta40, Abeta42, sAPPalpha, sAPPbeta, APP, BACE1, PSD95, synaptophysin, LRP1 were determined by ELISAs. In non-demented individuals, the regional distribution of sAPPalpha and sAPPbeta correlated with one another, while their correlation with full-length APP was weak. Importantly, the correlations between insoluble Abeta (especially Abeta42) and sAPPalpha or sAPPbeta were strong. Moreover, the postsynaptic marker PSD95 showed strong regional correlation with sAPPalpha and sAPPbeta. No significant association was observed between BACE1 and sAPPbeta. The distribution of sAPPalpha and sAPPbeta also showed strong regional association with Abeta accumulation in AD patients. These results suggest a potential involvement of synaptic function in the metabolism of soluble APP, associated with the accumulation of Abeta during the development of sporadic Alzheimer’s disease. We are currently addressing how synapses regulate the metabolism of soluble APP by in vivo microdialysis or another experimental system.

Effects of Lipid Membrane Curvatures on Binding, Secondary Structure, and Aggregation of Amyloid-Beta Protein

Conversion of amyloid-beta (Abeta) protein from a non-toxic monomer into the toxic aggregates is the possible pathogenic pathways in Alzheimer's disease. Recent studies have suggested that lipid membranes play key roles in protein aggregation. It has been demonstrated that Abeta accumulated and formed amyloid fibrils in specific intra- or extracellular membrane structures such as intraluminal vesicles of multivesicular bodies (MVBs) and exosomes with a diameter that ranges from 30 to 80 nm. These studies raise the possibility that Abeta preferentially binds to small-sized intra- or extracellular vesicles with a high membrane curvature, although the presence of specific lipid components might also influence the interaction. Indeed, it has been reported that small lipid vesicles (≤50 nm) composed of PC accelerated Abeta fibrillation. However, the binding modes and the mechanisms of Abeta aggregation on lipid vesicles of high curvature are not fully understood. Here, we observed that a high positive curvature of lipid vesicles with diameters of ∼30 nm enhanced the binding of Abeta with anionic PG membranes in the liquid crystalline phase and with zwitterionic PC membranes in the gel phase. The binding modes of Abeta to these membranes differ in terms of the depth of the protein in the membrane and of the protein secondary structure. Amyloid fibril formation of Abeta was accelerated in the presence of the vesicles and at high protein-to-lipid ratios. Under these conditions, the protein highly accumulated on the surfaces, as demonstrated by high (∼10ˆ7 Mˆ-1) binding constants. Our findings suggest that packing defects on membranes with high curvatures might result in the accumulation of toxic protein aggregates.

Differential effect of intranasally administrated kinin B1 and B2 receptor antagonists in Alzheimer's disease mice.

An Increasing body of evidence supports a critical role of brain inflammation in the pathogenesis of Alzheimer's disease. A principal aspect of the brain immune response to inflammation is the activation of microglia. It has been shown that the kinin system is activated during brain inflammation and previously we demonstrated that bradykinin B1 receptor agonist reduced microglial activation in vitro. The aim of the present study was to investigate the effects of bradykinin B1 or B2 receptor antagonists on microglial release of pro-inflammatory factors in BV2 microglia. In vivo, we focused on the effects of intranasally given kinin antagonists on amyloid burden and microglia/macrophage marker expression in brains of 5X familial Alzheimer's disease mice. The present data show that pharmacological antagonism of B1 receptor (R-715) but not B2 receptor (HOE-140) markedly increased nitric oxide and tumor necrosis factor alpha release from BV2 microglial cells. We also showed that intranasal treatment with R-715 but not HOE-140 of Alzheimer's mice enhanced amyloid beta burden and microglia/macrophages activation. Taken together, our data reveal a possible role for the bradykinin B1 receptor in neuroinflammation and in the control of Abeta accumulation in transgenic mice, possibly through regulation of glial cell responses.

Folic acid deficiency enhances abeta accumulation in APP/PS1 mice brain and decreases amyloid-associated miRNAs expression

Recent efforts have revealed the microRNA (miRNA) pathways in the pathogenesis of Alzheimer's disease (AD). Epidemiological studies have revealed an association between folic acid deficiency and AD risk. However, the effects of folic acid deficiency on miRNA expression in AD animals have not been observed. We aimed to find if folic acid deficiency may enhance amyloid-β (Aβ) peptide deposition and regulate amyloid-associated miRNAs and their target genes expression in APP/PS1 mice. APP/PS1 mice and N2a cells were treated with folic acid-deficient diet or medium. Cognitive function of mice was assessed using the Morris water maze. miRNA profile was tested by polymerase chain reaction (PCR) array. Different expressional miRNAs were validated by real-time PCR. The deposition of Aβ plaques was evaluated by immunohistochemistry and enzyme-linked immunosorbent assay. APP and BACE1 proteins in mice brain and N2a cells were determined by Western blot. Folic acid deficiency aggravated amyloid pathology in AD mice. The AD+FD group showed shorter time spent in the target zone during the probe test. Analysis of miRNAs predicted to target these genes revealed several miRNA candidates that were differentially modulated by folic acid deficiency. In APP/PS1 mice brains and N2a cells with folic acid-deficient treatment, miR-106a-5p, miR-200b-3p and miR-339-5p were down-regulated, and their target genes APP and BACE1 were up-regulated. In conclusion, folic acid deficiency can enhance Aβ accumulation in APP/PS1 mice brain and decrease amyloid-associated miRNAs expression.

Early intraneuronal Abeta deposition in the hippocampus of APP transgenic mice.

Increasing evidence suggests that intraneuronal amyloid-beta (Abeta) accumulation may be an early event in Alzheimer's disease (AD) pathogenesis. However direct in vivo evidence regarding initial Abeta seeding is missing. Using an APP transgenic mouse model, our sensitive immunocytochemical procedures revealed a novel intraneuronal Abeta deposition in the somas of hippocampal CA1/subiculum neurons far in advance of the occurrence of extracellular Abetaplaques. These deposits increased exponentially with age and were elevated approximately 4-fold (p < 0.001) by high fat/high cholesterol diet. Abeta40 and Abeta42 were the major constituents of these deposits and were co-localized with lysosomal markers. Our results are consistent with the notion that the earliest Abeta deposition occurs intraneuronally, prior to extracellular amyloid plaque formation.

Isoglutaminyl cyclase contributes to CCL2-driven neuroinflammation in Alzheimer's disease.

The brains of Alzheimer’s disease (AD) patients are characterized by deposits of Abeta peptides and by accompanying chronic inflammation. Here, we provide evidence that the enzyme isoglutaminyl cyclase (isoQC) is a novel factor contributing to both aspects of AD pathology. Two putative substrates of isoQC, N-truncated Abeta peptides and the monocyte chemoattractant chemokine CCL2, undergo isoQC-catalyzed pyroglutamate (pGlu) modification. This triggers Abeta aggregation and facilitates the biological activity of CCL2, which collectively results in the formation of high molecular weight Abeta aggregates, glial cell activation, neuroinflammation and neuronal cell death. In mouse brain, we found isoQC to be neuron-specifically expressed in neocortical, hippocampal and subcortical structures, localized to the endoplasmic reticulum and Golgi apparatus as well as co-expressed with its substrate CCL2. In aged APP transgenic Tg2576 mice, both isoQC and CCL2 mRNA levels are up-regulated and isoQC and CCL2 proteins were found to be co-induced in Abeta plaque-associated reactive astrocytes. Also, in mouse primary astrocyte culture, a simultaneous up-regulation of isoQC and CCL2 expression was revealed upon Abeta and pGlu-Abeta stimulation. In brains of AD patients, the expression of isoQC and CCL2 mRNA and protein is up-regulated compared to controls and correlates with pGlu-Abeta load and with the decline in mini-mental state examination. Our observations provide evidence for a dual involvement of isoQC in AD pathogenesis by catalysis of pGlu-Abeta and pGlu-CCL2 formation which mutually stimulate inflammatory events and affect cognition. We conclude that isoQC inhibition may target both major pathological events in the development of AD.Electronic supplementary materialThe online version of this article (doi:10.1007/s00401-015-1395-2) contains supplementary material, which is available to authorized users.

Genetics in psychiatry – diagnostic support or an illness classification!

Psychiatric diseases and their diagnosis are basically dependent upon phenomenology, other than a few conditions where the focus is on purely the medical condition. The changing and evolving picture of psychiatric nosology inculcates genetic findings as well. It has helped clinicians in understanding the disease pathology, its course, prognosis and the intervention options. This comprehensive, pedagogically-oriented review is aimed to include different advancements in genetic association studies along with various terms and findings in psychiatry, which have facilitated deeper understanding of illness at the molecular level. Findings on Alzheimer's disease, Autism spectrum disorder, schizophrenia and eating disorders are discussed. Existing interventions can be further modified by addition of modulators, inhibitors of A-beta aggregation, immunotherapy and inhibitors which can be generated on the basis of genetic association studies and its findings.

Activation of 5-HT(2C) receptor promotes the expression of neprilysin in U251 human glioma cells.

Abeta accumulation, a hallmark of Alzheimer's disease, promotes the disease progress in multiple facets. Abeta is formed through amyloidogenic cleavage pathway of amyloid precursor protein (APP). Production of Abeta can be decreased via activation of 5-HT2C receptor, which enhances alternative APP non-amyloidogenic cleavage. Besides, as one of the best characterized Aβ degrading enzymes, neprilysin (NEP) in AD progress has drawn more and more attention. We investigated whether there exists any connection between 5-HT2C receptor and NEP expression. The mRNA and protein expressions of NEP were increased after treatment of 5-HT2C receptor agonist RO-60-0175 in concentration- and time-dependent manners, and NEP expression was decreased after treatment of 5-HT2C receptor antagonist SB242084 correspondingly. These results suggest that 5-HT2C receptor may inhibit the Abeta formation by promoting NEP expression. The underlying mechanism will be explored in follow-up study and may provide potential target for AD therapy.