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The HSP40 chaperone Ydj1 drives amyloid beta 42 toxicity

ABSTRACT: Amyloid beta 42 (Abeta42) is the principal trigger of neurodegeneration during Alzheimer's disease (AD). However, the etiology of its noxious cellular effects remains elusive. In a combinatory genetic and proteomic approach using a yeast model to study aspects of intracellular Abeta42 toxicity, we here identify the HSP40 family member Ydj1, the yeast orthologue of human DnaJA1, as a crucial factor in Abeta42-mediated cell death. We demonstrate that Ydj1/DnaJA1 physically interacts with Abeta42 (in yeast and mouse), stabilizes Abeta42 oligomers, and mediates their translocation to mitochondria. Consequently, deletion of YDJ1 strongly reduces co-purification of Abeta42 with mitochondria and prevents Abeta42-induced mitochondria-dependent cell death. Consistently, purified DnaJ chaperone delays Abeta42 fibrillization in vitro, and heterologous expression of human DnaJA1 induces formation of Abeta42 oligomers and their deleterious translocation to mitochondria in vivo. Finally, downregulation of the Ydj1 fly homologue, Droj2, improves stress resistance, mitochondrial morphology and memory performance in a Drosophila melanogaster AD model. These data reveal an unexpected and detrimental role for specific HSP40s in promoting hallmarks of Abeta42 toxicity.

SUBMITTER: Prof. Frank Madeo

PROVIDER: S-SCDT-EMM-2021-13952 | biostudies-other |

REPOSITORIES: biostudies-other

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The HSP40 chaperone Ydj1 drives amyloid beta 42 toxicity.

Project description:Amyloid beta 42 (Abeta42) is the principal trigger of neurodegeneration during Alzheimer's disease (AD). However, the etiology of its noxious cellular effects remains elusive. In a combinatory genetic and proteomic approach using a yeast model to study aspects of intracellular Abeta42 toxicity, we here identify the HSP40 family member Ydj1, the yeast orthologue of human DnaJA1, as a crucial factor in Abeta42-mediated cell death. We demonstrate that Ydj1/DnaJA1 physically interacts with Abeta42 (in yeast and mouse), stabilizes Abeta42 oligomers, and mediates their translocation to mitochondria. Consequently, deletion of YDJ1 strongly reduces co-purification of Abeta42 with mitochondria and prevents Abeta42-induced mitochondria-dependent cell death. Consistently, purified DnaJ chaperone delays Abeta42 fibrillization in vitro, and heterologous expression of human DnaJA1 induces formation of Abeta42 oligomers and their deleterious translocation to mitochondria in vivo. Finally, downregulation of the Ydj1 fly homologue, Droj2, improves stress resistance, mitochondrial morphology, and memory performance in a Drosophila melanogaster AD model. These data reveal an unexpected and detrimental role for specific HSP40s in promoting hallmarks of Abeta42 toxicity.

| S-EPMC9081910 | biostudies-literature

The HSP40 chaperone Ydj1/DnaJA1 drives amyloid beta toxicity

Project description:Amyloid beta 42 (Abeta42) is the principal trigger of neurodegeneration during Alzheimer’s disease (AD); however, the etiology of Abeta42 toxicity remains elusive. In a proteomic approach using a yeast model for intracellular Abeta42 toxicity, we here identify the HSP40 family member Ydj1, the yeast orthologue of human DnaJA1, as a crucial factor in Abeta42-mediated toxicity.

2022-04-27 | PXD012612 | Pride

Interaction of the molecular chaperone DNAJB6 with growing amyloid-beta 42 (A?42) aggregates leads to sub-stoichiometric inhibition of amyloid formation.

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Inhibition of amyloid beta toxicity in zebrafish with a chaperone-gold nanoparticle dual strategy.

Project description:Alzheimer's disease (AD) is the most prevalent form of neurodegenerative disorders, yet no major breakthroughs have been made in AD human trials and the disease remains a paramount challenge and a stigma in medicine. Here we eliminate the toxicity of amyloid beta (A?) in a facile, high-throughput zebrafish (Danio rerio) model using casein coated-gold nanoparticles (?Cas AuNPs). ?Cas AuNPs in systemic circulation translocate across the blood brain barrier of zebrafish larvae and sequester intracerebral A?42 and its elicited toxicity in a nonspecific, chaperone-like manner. This is evidenced by behavioral pathology, reactive oxygen species and neuronal dysfunction biomarkers assays, complemented by brain histology and inductively coupled plasma-mass spectroscopy. We further demonstrate the capacity of ?Cas AuNPs in recovering the mobility and cognitive function of adult zebrafish exposed to A?. This potent, safe-to-use, and easy-to-apply nanomedicine may find broad use for eradicating toxic amyloid proteins implicated in a range of human diseases.

| S-EPMC6706415 | biostudies-literature

Heme oxygenase-1 protects against Alzheimer's amyloid-β(1-42)-induced toxicity via carbon monoxide production.

Project description:Heme oxygenase-1 (HO-1), an inducible enzyme up-regulated in Alzheimer's disease, catabolises heme to biliverdin, Fe2+ and carbon monoxide (CO). CO can protect neurones from oxidative stress-induced apoptosis by inhibiting Kv2.1 channels, which mediates cellular K+ efflux as an early step in the apoptotic cascade. Since apoptosis contributes to the neuronal loss associated with amyloid β peptide (Aβ) toxicity in AD, we investigated the protective effects of HO-1 and CO against Aβ(1-42) toxicity in SH-SY5Y cells, employing cells stably transfected with empty vector or expressing the cellular prion protein, PrP(c), and rat primary hippocampal neurons. Aβ(1-42) (containing protofibrils) caused a concentration-dependent decrease in cell viability, attributable at least in part to induction of apoptosis, with the PrP(c)-expressing cells showing greater susceptibility to Aβ(1-42) toxicity. Pharmacological induction or genetic over-expression of HO-1 significantly ameliorated the effects of Aβ(1-42). The CO-donor CORM-2 protected cells against Aβ(1-42) toxicity in a concentration-dependent manner. Electrophysiological studies revealed no differences in the outward current pre- and post-Aβ(1-42) treatment suggesting that K+ channel activity is unaffected in these cells. Instead, Aβ toxicity was reduced by the L-type Ca2+ channel blocker nifedipine, and by the CaMKKII inhibitor, STO-609. Aβ also activated the downstream kinase, AMP-dependent protein kinase (AMPK). CO prevented this activation of AMPK. Our findings indicate that HO-1 protects against Aβ toxicity via production of CO. Protection does not arise from inhibition of apoptosis-associated K+ efflux, but rather by inhibition of AMPK activation, which has been recently implicated in the toxic effects of Aβ. These data provide a novel, beneficial effect of CO which adds to its growing potential as a therapeutic agent.

| S-EPMC4454163 | biostudies-literature

C-Terminal Fragment, Aβ<sub>39-42</sub>-Based Tetrapeptides Mitigates Amyloid-β Aggregation-Induced Toxicity.

Project description:Since the introduction of acetyl cholinesterase inhibitors as the first approved drugs by the US Food and Drug Administration for Alzheimer's disease (AD) in clinics, less than satisfactory success in the design of anti-AD agents has impelled the scientists to also focus toward inhibition of Aβ aggregation. Considering the specific binding of fragments for their parent peptide, herein, we synthesized more than 40 new peptides based on a C-terminus tetrapeptide fragment of Aβ1-42. Initial screening by MTT cell viability assay and supportive results by ThT fluorescence assay led us to identify a tetrapeptide showing complete inhibition for Aβ1-42 aggregation. Peptide 20 displayed 100% cell viability at 20 μM concentration, while at lower concentrations of 10 and 2 μM 76.6 and 70% of cells were viable. Peptide 20 was found to restrict the conformational transition of Aβ1-42 peptide toward β-sheet structure. Inhibitory activity of tetrapeptide 20 was further evidenced by the absence of Aβ1-42 aggregates in electron microscopy. Peptide 20 and other significantly active tetrapeptide analogues could prove imperative in the future design of anti-AD agents.

| S-EPMC6645473 | biostudies-literature

Nanospectral data of amyloid beta 1-42 and scrambled amyloid beta 1-42

Project description:Two carrier-free peptides were synthesized and used in experiments: amyloid beta 42 (DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA), and a scrambled variant with the same chemical constituency as amyloid beta 42 (AIAEGDSHVLKEGAYMEIFDVQGHVFGGKIFRVVDLGSHNVA). To perform blockade current measurements, first, the sub-nanopore was wetted by immersion in de-gassed 250 mM NaCl electrolyte for 1-3 days. Subsequently, to measure the blockade current, a transmembrane voltage bias (< 700 mV) was applied to the reservoir relative to the ground in the channel using Ag/AgCl electrodes and the corresponding pore current was measured using either an Axopatch 700B or an Axopatch 200B amplifier with an open bandwidth. The actual bandwidth was inferred from the rise-time to a sharp (10 ps rise-time) input pulse to be about 75 kHz to 100 kHz, depending on the amplifier and the feedback. The analog data were digitized by a 16-bit DigiData 1550B data acquisition system (DAQ, Molecular Devices, Sunnyvale, CA) at a sampling rate of 500 kS/s and recorded in 3 minute-long acquisition windows. A total of 12 Axon binary files (ABF) were collected for amyloid beta 42, and 71 ABF files for scrambled amyloid beta 42.

2022-06-30 | MSV000089779 | MassIVE

Amyloid-beta 42 adsorption following serial tube transfer.

Project description:IntroductionCerebrospinal fluid (CSF) amyloid-beta 38 (A?38), 40 (A?40), 42 (A?42) and total tau (T-tau) are finding increasing utility as biomarkers of Alzheimer's disease (AD). The purpose of this study was to determine whether measured CSF biomarker concentrations were affected by transfer of CSF between tubes, and whether addition of a non-ionic surfactant mitigates any observed effects.MethodsAD and control CSF was transferred consecutively between polypropylene tubes. A? peptides and T-tau were measured with and without addition of Tween 20 (0.05%).ResultsMeasured concentrations of A?42 decreased by approximately 25% with each consecutive transfer. Measured concentrations of A?38 and A?40 were also observed to decrease significantly with each consecutive transfer (approximately 16% loss per transfer). Measured concentrations of T-tau also decreased significantly, but at much smaller magnitude than the A? peptides (approximately 4% loss per transfer). The addition of Tween 20 mitigated this effect in all samples.ConclusionsConsecutive CSF transfer between tubes has a significant impact on the measured concentration of all A? peptides, and significant effect of lesser magnitude on T-tau. This would be sufficient to alter biomarker ratios enough to mislead diagnosis. The introduction of Tween 20 at the initial aliquoting stage was observed to significantly mitigate this effect.

| S-EPMC4059346 | biostudies-literature

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