Amyloid-β peptide (Aβ) aggregation is one of the hallmarks of Alzheimer’s disease (AD). Mutations... more Amyloid-β peptide (Aβ) aggregation is one of the hallmarks of Alzheimer’s disease (AD). Mutations in Aβ are associated with early onset familial AD, and the Arctic mutant E22G (Aβarc) is an extremely aggregation-prone variant. Here, we show that BRICHOS, a natural anti-amyloid chaperone domain, from Bri2 efficiently inhibits aggregation of Aβarc by mainly interfering with secondary nucleation. This is qualitatively different from the microscopic inhibition mechanism for the wild-type Aβ, against which Bri2 BRICHOS has a major effect on both secondary nucleation and fibril end elongation. The monomeric Aβ42arc peptide aggregates into amyloid fibrils significantly faster than wild-type Aβ (Aβ42wt), as monitored by thioflavin T (ThT) binding, but the final ThT intensity was strikingly lower for Aβ42arc compared to Aβ42wt fibrils. The Aβ42arc peptide formed large aggregates, single-filament fibrils, and multiple-filament fibrils without obvious twists, while Aβ42wt fibrils displayed a polymorphic pattern with typical twisted fibril architecture. Recombinant human Bri2 BRICHOS binds to the Aβ42arc fibril surface and interferes with the macroscopic fibril arrangement by promoting single-filament fibril formation. This study provides mechanistic insights on how BRICHOS efficiently affects the aggressive Aβ42arc aggregation, resulting in both delayed fibril formation kinetics and altered fibril structure.
The deposition of proteins in the form of amyloid fibrils is closely associated with several seri... more The deposition of proteins in the form of amyloid fibrils is closely associated with several serious diseases. The events that trigger the conversion from soluble functional proteins into insoluble amyloid are not fully understood. Many proteins that are not associated with disease can form amyloid with similar structural characteristics as the disease-associated fibrils, which highlights the potential risk of cross-seeding of disease amyloid by amyloid-like structures encountered in our surrounding. Of particular interest are common food proteins that can be transformed into amyloid under conditions similar to cooking. We here investigate cross-seeding of amyloid-β (Aβ), a peptide known to form amyloid during the development of Alzheimer’s disease, by 16 types of amyloid fibrils derived from food proteins or peptides. Kinetic studies using thioflavin T fluorescence as output show that none of the investigated protein fibrils accelerates the aggregation of Aβ. In at least two cases ...
Activities of the BRICHOS domain against amyloid fibril formation and amyloid-induced neurotoxici... more Activities of the BRICHOS domain against amyloid fibril formation and amyloid-induced neurotoxicity are affected by pH.
Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded protein... more Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded proteins such as amyloid beta (Aβ) in senile plaques, and hyperphosphorylated tau and truncated tau in neurofibrillary tangles (NFT). The BRI2 protein inhibits Aβ aggregation via its BRICHOS domain and regulates critical proteins involved in initiating the amyloid cascade, which has been hypothesized to be central in AD pathogenesis. We recently detected the deposition of BRI2 ectodomain associated with Aβ plaques and concomitant changes in its processing enzymes in early stages of AD. Here, we aimed to investigate the effects of recombinant BRI2 ectodomain (rBRI276-266) on Aβ aggregation and on important molecular pathways involved in early stages of AD, including the unfolded protein response (UPR), phosphorylation and truncation of tau, as well as apoptosis. We found that rBRI276-266 delays Aβ fibril formation, although less efficiently than the BRI2 BRICHOS domain (BRI2 residues 113-231). I...
During storage in the silk gland, the N-terminal domain (NT) of spider silk proteins (spidroins) ... more During storage in the silk gland, the N-terminal domain (NT) of spider silk proteins (spidroins) keeps the aggregation-prone repetitive region in solution at extreme concentrations. We observe that NTs from different spidroins have co-evolved with their respective repeat region, and now use an NT that is distantly related to previously used NTs, for efcient recombinant production of the amyloid-β peptide (Aβ) implicated in Alzheimer’s disease. A designed variant of NT from Nephila clavipes fagelliform spidroin, which in nature allows production and storage of β-hairpin repeat segments, gives exceptionally high yields of diferent human Aβ variants as a solubility tag. This tool enables efficient production of target peptides also in minimal medium and gives up to 10 times more isotope-labeled monomeric Aβ peptides per liter bacterial culture than previously reported
CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopat... more CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is the most common familial form of stroke, which is caused by mutations located in the epidermal growth factor (EGF)-like repeats of the NOTCH3 gene. Mutations cause the NOTCH3 (N3) protein to misfold and aggregate. These aggregates will be a component of granular osmiophilic material, which when accumulated around the arteries and arterioles is believed to cause the degradation of vascular smooth muscle cells (VSMC). VSMC degradation affects blood flow regulation and leads to white matter and neuronal death. Currently, there is no treatment for CADASIL. The dementia-relevant BRICHOS domain is a small multitalented protein with functions that include ATP-independent chaperone-like properties. BRICHOS has been shown to prevent the aggregation of both fibrillar and non-fibrillar structures. Therefore, the objective of this study is to investigate whether BRICHOS exhibits anti-aggregat...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 20, 2014
The amyloid-β hypothesis of Alzheimer's Disease (AD) focuses on accumulation of amyloid-β pep... more The amyloid-β hypothesis of Alzheimer's Disease (AD) focuses on accumulation of amyloid-β peptide (Aβ) as the main culprit for the myriad physiological changes seen during development and progression of AD including desynchronization of neuronal action potentials, consequent development of aberrant brain rhythms relevant for cognition, and final emergence of cognitive deficits. The aim of this study was to elucidate the cellular and synaptic mechanisms underlying the Aβ-induced degradation of gamma oscillations in AD, to identify aggregation state(s) of Aβ that mediate the peptides neurotoxicity, and to test ways to prevent the neurotoxic Aβ effect. We show that Aβ(1-42) in physiological concentrations acutely degrades mouse hippocampal gamma oscillations in a concentration- and time-dependent manner. The underlying cause is an Aβ-induced desynchronization of action potential generation in pyramidal cells and a shift of the excitatory/inhibitory equilibrium in the hippocampal ne...
Peptide-like compounds containing an arginine have been shown to bind and stabilize the central h... more Peptide-like compounds containing an arginine have been shown to bind and stabilize the central helix of the Alzheimer's disease related amyloid-β peptide (Aβ) in an α-helical conformation, thereby delaying its aggregation into cytotoxic species. Here we study a novel Aβ targeting ligand AEDabDab containing the triamino acid, N(γ)-(2-aminoethyl)-2,4-diaminobutanoic (AEDab) acid. The new AEDab triamino acid carries an extra positive charge in the side chain and is designed to be incorporated into a ligand AEDabDab where the AEDab replaces an arginine moiety in a previously developed ligand Pep1b. This is done in order to increase the Aβ-ligand interaction, and molecular dynamics (MD) simulation of the stability of the Aβ central helix in the presence of the AEDabDab ligand shows further stabilization of the helical conformation of Aβ compared to the previously reported Pep1b as well as compared to the AEOrnDab ligand containing an N(δ)-(2-aminoethyl)-2,5-diaminopentanoic acid uni...
Amyloid-β peptide (Aβ) aggregation is one of the hallmarks of Alzheimer’s disease (AD). Mutations... more Amyloid-β peptide (Aβ) aggregation is one of the hallmarks of Alzheimer’s disease (AD). Mutations in Aβ are associated with early onset familial AD, and the Arctic mutant E22G (Aβarc) is an extremely aggregation-prone variant. Here, we show that BRICHOS, a natural anti-amyloid chaperone domain, from Bri2 efficiently inhibits aggregation of Aβarc by mainly interfering with secondary nucleation. This is qualitatively different from the microscopic inhibition mechanism for the wild-type Aβ, against which Bri2 BRICHOS has a major effect on both secondary nucleation and fibril end elongation. The monomeric Aβ42arc peptide aggregates into amyloid fibrils significantly faster than wild-type Aβ (Aβ42wt), as monitored by thioflavin T (ThT) binding, but the final ThT intensity was strikingly lower for Aβ42arc compared to Aβ42wt fibrils. The Aβ42arc peptide formed large aggregates, single-filament fibrils, and multiple-filament fibrils without obvious twists, while Aβ42wt fibrils displayed a polymorphic pattern with typical twisted fibril architecture. Recombinant human Bri2 BRICHOS binds to the Aβ42arc fibril surface and interferes with the macroscopic fibril arrangement by promoting single-filament fibril formation. This study provides mechanistic insights on how BRICHOS efficiently affects the aggressive Aβ42arc aggregation, resulting in both delayed fibril formation kinetics and altered fibril structure.
The deposition of proteins in the form of amyloid fibrils is closely associated with several seri... more The deposition of proteins in the form of amyloid fibrils is closely associated with several serious diseases. The events that trigger the conversion from soluble functional proteins into insoluble amyloid are not fully understood. Many proteins that are not associated with disease can form amyloid with similar structural characteristics as the disease-associated fibrils, which highlights the potential risk of cross-seeding of disease amyloid by amyloid-like structures encountered in our surrounding. Of particular interest are common food proteins that can be transformed into amyloid under conditions similar to cooking. We here investigate cross-seeding of amyloid-β (Aβ), a peptide known to form amyloid during the development of Alzheimer’s disease, by 16 types of amyloid fibrils derived from food proteins or peptides. Kinetic studies using thioflavin T fluorescence as output show that none of the investigated protein fibrils accelerates the aggregation of Aβ. In at least two cases ...
Activities of the BRICHOS domain against amyloid fibril formation and amyloid-induced neurotoxici... more Activities of the BRICHOS domain against amyloid fibril formation and amyloid-induced neurotoxicity are affected by pH.
Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded protein... more Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded proteins such as amyloid beta (Aβ) in senile plaques, and hyperphosphorylated tau and truncated tau in neurofibrillary tangles (NFT). The BRI2 protein inhibits Aβ aggregation via its BRICHOS domain and regulates critical proteins involved in initiating the amyloid cascade, which has been hypothesized to be central in AD pathogenesis. We recently detected the deposition of BRI2 ectodomain associated with Aβ plaques and concomitant changes in its processing enzymes in early stages of AD. Here, we aimed to investigate the effects of recombinant BRI2 ectodomain (rBRI276-266) on Aβ aggregation and on important molecular pathways involved in early stages of AD, including the unfolded protein response (UPR), phosphorylation and truncation of tau, as well as apoptosis. We found that rBRI276-266 delays Aβ fibril formation, although less efficiently than the BRI2 BRICHOS domain (BRI2 residues 113-231). I...
During storage in the silk gland, the N-terminal domain (NT) of spider silk proteins (spidroins) ... more During storage in the silk gland, the N-terminal domain (NT) of spider silk proteins (spidroins) keeps the aggregation-prone repetitive region in solution at extreme concentrations. We observe that NTs from different spidroins have co-evolved with their respective repeat region, and now use an NT that is distantly related to previously used NTs, for efcient recombinant production of the amyloid-β peptide (Aβ) implicated in Alzheimer’s disease. A designed variant of NT from Nephila clavipes fagelliform spidroin, which in nature allows production and storage of β-hairpin repeat segments, gives exceptionally high yields of diferent human Aβ variants as a solubility tag. This tool enables efficient production of target peptides also in minimal medium and gives up to 10 times more isotope-labeled monomeric Aβ peptides per liter bacterial culture than previously reported
CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopat... more CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is the most common familial form of stroke, which is caused by mutations located in the epidermal growth factor (EGF)-like repeats of the NOTCH3 gene. Mutations cause the NOTCH3 (N3) protein to misfold and aggregate. These aggregates will be a component of granular osmiophilic material, which when accumulated around the arteries and arterioles is believed to cause the degradation of vascular smooth muscle cells (VSMC). VSMC degradation affects blood flow regulation and leads to white matter and neuronal death. Currently, there is no treatment for CADASIL. The dementia-relevant BRICHOS domain is a small multitalented protein with functions that include ATP-independent chaperone-like properties. BRICHOS has been shown to prevent the aggregation of both fibrillar and non-fibrillar structures. Therefore, the objective of this study is to investigate whether BRICHOS exhibits anti-aggregat...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 20, 2014
The amyloid-β hypothesis of Alzheimer's Disease (AD) focuses on accumulation of amyloid-β pep... more The amyloid-β hypothesis of Alzheimer's Disease (AD) focuses on accumulation of amyloid-β peptide (Aβ) as the main culprit for the myriad physiological changes seen during development and progression of AD including desynchronization of neuronal action potentials, consequent development of aberrant brain rhythms relevant for cognition, and final emergence of cognitive deficits. The aim of this study was to elucidate the cellular and synaptic mechanisms underlying the Aβ-induced degradation of gamma oscillations in AD, to identify aggregation state(s) of Aβ that mediate the peptides neurotoxicity, and to test ways to prevent the neurotoxic Aβ effect. We show that Aβ(1-42) in physiological concentrations acutely degrades mouse hippocampal gamma oscillations in a concentration- and time-dependent manner. The underlying cause is an Aβ-induced desynchronization of action potential generation in pyramidal cells and a shift of the excitatory/inhibitory equilibrium in the hippocampal ne...
Peptide-like compounds containing an arginine have been shown to bind and stabilize the central h... more Peptide-like compounds containing an arginine have been shown to bind and stabilize the central helix of the Alzheimer's disease related amyloid-β peptide (Aβ) in an α-helical conformation, thereby delaying its aggregation into cytotoxic species. Here we study a novel Aβ targeting ligand AEDabDab containing the triamino acid, N(γ)-(2-aminoethyl)-2,4-diaminobutanoic (AEDab) acid. The new AEDab triamino acid carries an extra positive charge in the side chain and is designed to be incorporated into a ligand AEDabDab where the AEDab replaces an arginine moiety in a previously developed ligand Pep1b. This is done in order to increase the Aβ-ligand interaction, and molecular dynamics (MD) simulation of the stability of the Aβ central helix in the presence of the AEDabDab ligand shows further stabilization of the helical conformation of Aβ compared to the previously reported Pep1b as well as compared to the AEOrnDab ligand containing an N(δ)-(2-aminoethyl)-2,5-diaminopentanoic acid uni...
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