Dihydropyridine derivatives modulate heat shock responses and have a neuroprotective effect in a transgenic mouse model of Alzheimer’s disease

Heat shock proteins (Hsps) have chaperone activity and play a pivotal role in the homeostasis of proteins by preventing misfolding, by clearing aggregated and damaged proteins from cells and by maintaining proteins in an active state. Alzheimer’s disease (AD) is thought to be caused by β- amyloid peptide that triggers tau hyperphosphorylation, which is neurotoxic. Although proteostasis capacity declines with age and facilitates the manifestation of neurodegenerative diseases such as AD, the upregulation of chaperones improves prognosis. Our research goal is to identify potent Hsp co-inducers that enhance protein homeostasis for the treatment of AD, especially 1,4-dihydropyridine derivatives optimized for their ability to modulate cellular stress responses. Based on favorable toxicological data and Hsp co-inducing activity, LA1011 was selected for the in vivo analysis of its neuroprotective effect in the APPxPS1 mouse model of AD. Here, we report that 6 months of LA1011 administration effectively improved the spatial learning and memory functions in wild type mice and eliminated neurodegeneration in double mutant mice. Furthermore, Hsp co-inducer therapy preserves the number of neurons, increases dendritic spine density, and reduces tau pathology and amyloid plaque formation in transgenic AD mice. In conclusion, the Hsp co-inducer LA1011 is neuroprotective and therefore is a potential pharmaceutical candidate for the therapy of neurodegenerative diseases, particularly AD

Béta-amiloid peptidek aggregációja és kölcsönhatása fehérjékkel; új neuroprotektív vegyületek alkalmazása az Alzheimer-kór megelőzésére = Beta-amyloid aggregation and interaction with proteins; novel neuroprotective compounds for prevention of Alzheimer's disease

Új, standardizálható módszert dolgoztunk ki toxikus �béta-amiloid (Abéta) 1-42 peptid oligomerek előállítására, a preparált oligomereket fiziko-kémiai módszerekkel jellemeztük. Két új neuroprotektív peptidmimetikum vegyületcsaládot találtunk, ezek az anyagok megvédik a neuronokat az Alzheimer-kór (AK) állatmodelljében az Abéta neurotoxikus hatásától. Mindkét vegyületcsoportot szabadalmilag védjük, mint az AK potenciális gyógyszerjelölt vegyületeit. Új ex vivo módszert dolgoztunk ki az Abéta peptidek toxicitásának mérésére (patkány hippocampus szelet, MTT-teszt), a módszer alkalmas az új neuroprotektív vegyületeink aktivitásmérésére is. Az ex vivo hippocampus szeleteket sikerrel alkalmaztuk a neuronális plaszticitás (LTP) mérésére, az Abéta-toxicitás meghatározására, multielektród array (MEA) technikával. In vivo, egysejt-elvezetéses elektrofiziológiai mérésekkel bizonyítottuk az új peptidmimetikumaink neuroprotektív hatását. Proteomikai módszerekkel azonosítottuk az Abéta peptidekkel kölcsönhatásba lépő fehérjéket, ezek elsősorban plazmamembrán, ill. intraneuronális fehérjék (mitokondrium, endoplazmás reticulum, mikrotubuláris rendszer). Az intraneuronális fehérjék és az Abéta peptidek kölcsönhatásai kulcsszerepet játszhatnak az AK patogenezisében. Igazoltuk, hogy a Zn2+ ionok toxikus Abéta-aggregátumok képződését indukálják. Az AK transzgén állatmodelljén bizonyítottuk, hogy a Zn-kelátorok (pl. Perindopril) neuroprotektív hatásúak. Új AK-állatmodellt dolgoztunk ki az Abéta oligomerek icv bevitelével. | A new method was introduced for the preparation of toxic beta-amyloid (Abeta) 1-42 oligomers, these assemblies were characterized with physicochemical methods. Two families of novel neuroprotective peptidomimetics were found, these substances protect neurons against the toxic effect of Abeta in tg mouse models of Alzheimer’s disease (AD). Both groups of the novel substances will be patented as putative drug candidates for AD treatment. A new ex vivo method was introduced for toxicity measurement of Abeta peptides (rat hippocampal slices, MTT-assay); this method proved to be suitable for activity measurement of the novel neuroprotective substances. Hippocampal slices were successfully used for measurement of neuronal plasticity (LTP) for demonstrating neurotoxicity of Abeta aggregates, applying multielectrode array (MEA) technique. The neuroprotective effect of our novel peptidomimetics was demonstrated also in vivo, using one-cell electrophysiology. Proteomic methods were used for identification of proteins interacting with Abeta peptides; these are mainly plasma membrane and intraneuronal (mitochondrial, endoplasmatic reticular and microtubular) proteins. Interaction of intracellular proteins with Abeta may play key role in AD pathogenesis. The role of Zn2+ ions in formation of toxic Abeta-aggregates was demonstrated. Zn2+-chelators (e.g. Perindopril) were neuroprotective in a tg-mouse model of AD. A new AD rat model was introduced using icv administration of synthetic Abeta oligomers

Membrane-Lipid Therapy in Operation: The HSP Co-Inducer BGP-15 Activates Stress Signal Transduction Pathways by Remodeling Plasma Membrane Rafts

Aging and pathophysiological conditions are linked to membrane changes which modulate membrane-controlled molecular switches, causing dysregulated heat shock protein (HSP) expression. HSP co-inducer hydroxylamines such as BGP-15 provide advanced therapeutic candidates for many diseases since they preferentially affect stressed cells and are unlikely have major side effects. In the present study in vitro molecular dynamic simulation, experiments with lipid monolayers and in vivo ultrasensitive fluorescence microscopy showed that BGP-15 alters the organization of cholesterol-rich membrane domains. Imaging of nanoscopic long-lived platforms using the raft marker glycosylphosphatidylinositol-anchored monomeric green fluorescent protein diffusing in the live Chinese hamster ovary (CHO) cell plasma membrane demonstrated that BGP-15 prevents the transient structural disintegration of rafts induced by fever-type heat stress. Moreover, BGP-15 was able to remodel cholesterol-enriched lipid platforms reminiscent of those observed earlier following non-lethal heat priming or membrane stress, and were shown to be obligate for the generation and transmission of stress signals. BGP-15 activation of HSP expression in B16-F10 mouse melanoma cells involves the Rac1 signaling cascade in accordance with the previous observation that cholesterol affects the targeting of Rac1 to membranes. Finally, in a human embryonic kidney cell line we demonstrate that BGP-15 is able to inhibit the rapid heat shock factor 1 (HSF1) acetylation monitored during the early phase of heat stress, thereby promoting a prolonged duration of HSF1 binding to heat shock elements. Taken together, our results indicate that BGP-15 has the potential to become a new class of pharmaceuticals for use in ‘membrane-lipid therapy’ to combat many various protein-misfolding diseases associated with aging

Studies for improving a rat model of Alzheimer's disease: ICV administration of well-characterized - β-amyloid 1-42 oligomers induce dysfunction in spatial memory

During the past 15 years, several genetically altered mouse models of human Alzheimer's disease (AD) have been developed. These costly models have greatly facilitated the evaluation of novel therapeutic approaches. Injecting synthetic -amyloid (A) 1-42 species into different parts of the brain of non-transgenic rodents frequently provided unreliable results, owing to a lack of a genuine characterization of the administered A aggregates. Previously, we have published a new rat AD-model in which protofibrillar-fibrillar A1-42 was administered into rat entorhinal cortex (Sipos 2007). In order to develop a more reliable model, we have injected well-characterized toxic soluble A1-42 species (oligomers, protofibrils and fibrils) intracerebroventricularly (icv) into rat brain. Studies of the distribution of fluorescent-labeled A1-42 in the brain showed that soluble A-species diffused into all parts of the rat brain. After seven days, the A-treated animals showed a significant decrease of spatial memory in Morris water maze test and impairment of synaptic plasticity (LTP) measured in acute hippocampal slices. The results of histological studies (decreased number of viable neurons, increased tau levels and decreased number of dendritic spines) also supported that icv administration of well-characterized toxic soluble A species into rat brain provides a reliable rat AD-model

Models of 21st century digital university

From “cognition and memory” to “cognition-action” “Cognition and memory”, represented on the diagram below, is the only enhanced learning method so far. The teacher is the only holder of the information to be transferred to the student. The acquisition of knowledge is confirmed by the student’s reproduction of the information (by means of essay, etc.). Regarding the study of controversies, the information is under construction and not yet defined. As the end of the debate is not known, we can..

Fibrillar A beta(1-42) enhances NMDA receptor sensitivity via the integrin signaling pathway

The aggregated form of amyloid-beta (Abeta) (1-42) has been shown to increase N-methyl-D-aspartic acid (NMDA) evoked neuronal activity in vivo. Here we further characterized this phenomenon by investigating the role of integrin activation and downstream Src kinase activity using in vivo electrophysiology and in vitro intracellular Ca (2+) measurements. Pretreatment of differentiated SH-SY5Y cells with fibrillar Abeta (1-42) markedly enhanced the intracellular calcium increases caused by NMDA receptor (NMDA-R) stimulation. Function blocking antibody against beta1 integrin depressed the facilitatory effects of Abeta (1-42). Similarly, Abeta (1-42) facilitated NMDA-R driven firing of hippocampal neurons in vivo, and this effect was reduced by neutralizing antibody against beta1 integrins. The positive action of Abeta (1-42) on NMDA-R dependent responses was also depressed by an inhibitor known to block Src kinase. These results support the hypothesis that aggregated Abeta (1-42) is recognized by the beta1 subunit containing integrins and may induce a Src kinase dependent NMDA receptor phosphorylation