scholarly journals Rational design of a conformation-specific antibody for the quantification of Aβ oligomers

2020 ◽  
Vol 117 (24) ◽  
pp. 13509-13518 ◽  
Author(s):  
Francesco A. Aprile ◽  
Pietro Sormanni ◽  
Marina Podpolny ◽  
Shianne Chhangur ◽  
Lisa-Maria Needham ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Misfolding ◽  
Rational Design ◽  
Design Method ◽  
Amyloid Β ◽  
In Vitro Assays ◽  
Aβ Oligomers ◽  
Detection And Quantification

Protein misfolding and aggregation is the hallmark of numerous human disorders, including Alzheimer’s disease. This process involves the formation of transient and heterogeneous soluble oligomers, some of which are highly cytotoxic. A major challenge for the development of effective diagnostic and therapeutic tools is thus the detection and quantification of these elusive oligomers. Here, to address this problem, we develop a two-step rational design method for the discovery of oligomer-specific antibodies. The first step consists of an “antigen scanning” phase in which an initial panel of antibodies is designed to bind different epitopes covering the entire sequence of a target protein. This procedure enables the determination through in vitro assays of the regions exposed in the oligomers but not in the fibrillar deposits. The second step involves an “epitope mining” phase, in which a second panel of antibodies is designed to specifically target the regions identified during the scanning step. We illustrate this method in the case of the amyloid β (Aβ) peptide, whose oligomers are associated with Alzheimer’s disease. Our results show that this approach enables the accurate detection and quantification of Aβ oligomers in vitro, and inCaenorhabditis elegansand mouse hippocampal tissues.

scholarly journals Cu-Based Turn-on Fluorescent Sensors for Cu-rich Amyloid β Aggregates

2021 ◽  
Author(s):  
Yiran Huang ◽  
Liang Sun ◽  
Liviu M. Mirica
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Fluorescence Imaging ◽  
Protein Misfolding ◽  
Picolinic Acid ◽  
Amyloid Β ◽  
Fluorescent Sensors ◽  
Aβ Oligomers ◽  
Turn On ◽  
Aβ Aggregation

<div>Protein misfolding and metal dishomeostasis are two key</div><div>pathological factors of Alzheimer’s disease. Previous studies have showed that Cu‐mediated Aβ aggregation pathways lead to formation of neurotoxic Aβ oligomers. Herein, we reported a series of picolinic acid‐based Cu‐activatable sensors, which can be used for the fluorescence imaging of Cu‐rich Aβ aggregates.</div>

Prions and Neurodegenerative Diseases: A Focus on Alzheimer’s Disease

2021 ◽  
pp. 1-16
Author(s):  
Alessio Crestini ◽  
Francesca Santilli ◽  
Stefano Martellucci ◽  
Elena Carbone ◽  
Maurizio Sorice ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Diseases ◽  
Protein Misfolding ◽  
Amyloid Β ◽  
Specific Protein ◽  
Cellular Prion Protein ◽  
Aβ Oligomers ◽  
The Central Nervous System ◽  
Induced Signal

Specific protein misfolding and aggregation are mechanisms underlying various neurodegenerative diseases such as prion disease and Alzheimer’s disease (AD). The misfolded proteins are involved in prions, amyloid-β (Aβ), tau, and α-synuclein disorders; they share common structural, biological, and biochemical characteristics, as well as similar mechanisms of aggregation and self-propagation. Pathological features of AD include the appearance of plaques consisting of deposition of protein Aβ and neurofibrillary tangles formed by the hyperphosphorylated tau protein. Although it is not clear how protein aggregation leads to AD, we are learning that the cellular prion protein (PrPC) plays an important role in the pathogenesis of AD. Herein, we first examined the pathogenesis of prion and AD with a focus on the contribution of PrPC to the development of AD. We analyzed the mechanisms that lead to the formation of a high affinity bond between Aβ oligomers (AβOs) and PrPC. Also, we studied the role of PrPC as an AβO receptor that initiates an AβO-induced signal cascade involving mGluR5, Fyn, Pyk2, and eEF2K linking Aβ and tau pathologies, resulting in the death of neurons in the central nervous system. Finally, we have described how the PrPC-AβOs interaction can be used as a new potential therapeutic target for the treatment of PrPC-dependent AD.

scholarly journals The inhibition of cellular toxicity of amyloid-β by dissociated transthyretin

2020 ◽  
Vol 295 (41) ◽  
pp. 14015-14024 ◽  
Author(s):  
Qin Cao ◽  
Daniel H. Anderson ◽  
Wilson Y. Liang ◽  
Joshua Chou ◽  
Lorena Saelices
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protective Effect ◽  
Amyloid Β ◽  
Inhibitory Effect ◽  
Aβ Oligomers ◽  
Cellular Toxicity ◽  
Computational Docking

The protective effect of transthyretin (TTR) on cellular toxicity of β-amyloid (Aβ) has been previously reported. TTR is a tetrameric carrier of thyroxine in blood and cerebrospinal fluid, the pathogenic aggregation of which causes systemic amyloidosis. However, studies have documented a protective effect of TTR against cellular toxicity of pathogenic Aβ, a protein associated with Alzheimer's disease. TTR binds Aβ, alters its aggregation, and inhibits its toxicity both in vitro and in vivo. In this study, we investigate whether the amyloidogenic ability of TTR and its antiamyloid inhibitory effect are associated. Using protein aggregation and cytotoxicity assays, we found that the dissociation of the TTR tetramer, required for its amyloid pathogenesis, is also necessary to prevent cellular toxicity from Aβ oligomers. These findings suggest that the Aβ-binding site of TTR may be hidden in its tetrameric form. Aided by computational docking and peptide screening, we identified a TTR segment that is capable of altering Aβ aggregation and toxicity, mimicking TTR cellular protection. EM, immune detection analysis, and assessment of aggregation and cytotoxicity revealed that the TTR segment inhibits Aβ oligomer formation and also promotes the formation of nontoxic, nonamyloid amorphous aggregates, which are more sensitive to protease digestion. Finally, this segment also inhibits seeding of Aβ catalyzed by Aβ fibrils extracted from the brain of an Alzheimer's patient. Together, these findings suggest that mimicking the inhibitory effect of TTR with peptide-based therapeutics represents an additional avenue to explore for the treatment of Alzheimer's disease.

scholarly journals CNI-1493 inhibits Aβ production, plaque formation, and cognitive deterioration in an animal model of Alzheimer's disease

2008 ◽  
Vol 205 (7) ◽  
pp. 1593-1599 ◽  
Author(s):  
Michael Bacher ◽  
Richard Dodel ◽  
Bayan Aljabari ◽  
Kathy Keyvani ◽  
Philippe Marambaud ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Memory Performance ◽  
Amyloid Β ◽  
Amyloid Plaque ◽  
Amyloid Β Protein ◽  
Aβ Oligomers ◽  
App Processing ◽  
Model Of Alzheimer’S Disease

Alzheimer's disease (AD) is characterized by neuronal atrophy caused by soluble amyloid β protein (Aβ) peptide “oligomers” and a microglial-mediated inflammatory response elicited by extensive amyloid deposition in the brain. We show that CNI-1493, a tetravalent guanylhydrazone with established antiinflammatory properties, interferes with Aβ assembly and protects neuronal cells from the toxic effect of soluble Aβ oligomers. Administration of CNI-1493 to TgCRND8 mice overexpressing human amyloid precursor protein (APP) for a treatment period of 8 wk significantly reduced Aβ deposition. CNI-1493 treatment resulted in 70% reduction of amyloid plaque area in the cortex and 87% reduction in the hippocampus of these animals. Administration of CNI-1493 significantly improved memory performance in a cognition task compared with vehicle-treated mice. In vitro analysis of CNI-1493 on APP processing in an APP-overexpressing cell line revealed a significant dose-dependent decrease of total Aβ accumulation. This study indicates that the antiinflammatory agent CNI-1493 can ameliorate the pathophysiology and cognitive defects in a murine model of AD.

scholarly journals Trichostatin A ameliorates Alzheimer’s disease-related pathology and cognitive deficits by increasing albumin expression and Aβ clearance in APP/PS1 mice

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Qiang Su ◽  
Tian Li ◽  
Pei-Feng He ◽  
Xue-Chun Lu ◽  
Qi Yu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Western Blotting ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Trichostatin A ◽  
Amyloid Β ◽  
Aβ Oligomers ◽  
Aβ Clearance

Abstract Background Alzheimer’s disease (AD) is an intractable neurodegenerative disorder in the elderly population, currently lacking a cure. Trichostatin A (TSA), a histone deacetylase inhibitor, showed some neuroprotective roles, but its pathology-improvement effects in AD are still uncertain, and the underlying mechanisms remain to be elucidated. The present study aims to examine the anti-AD effects of TSA, particularly investigating its underlying cellular and molecular mechanisms. Methods Novel object recognition and Morris water maze tests were used to evaluate the memory-ameliorating effects of TSA in APP/PS1 transgenic mice. Immunofluorescence, Western blotting, Simoa assay, and transmission electron microscopy were utilized to examine the pathology-improvement effects of TSA. Microglial activity was assessed by Western blotting and transwell migration assay. Protein-protein interactions were analyzed by co-immunoprecipitation and LC-MS/MS. Results TSA treatment not only reduced amyloid β (Aβ) plaques and soluble Aβ oligomers in the brain, but also effectively improved learning and memory behaviors of APP/PS1 mice. In vitro study suggested that the improvement of Aβ pathology by TSA was attributed to the enhancement of Aβ clearance, mainly by the phagocytosis of microglia, and the endocytosis and transport of microvascular endothelial cells. Notably, a meaningful discovery in the study was that TSA dramatically upregulated the expression level of albumin in cell culture, by which TSA inhibited Aβ aggregation and promoted the phagocytosis of Aβ oligomers. Conclusions These findings provide a new insight into the pathogenesis of AD and suggest TSA as a novel promising candidate for the AD treatment.

scholarly journals Bacterial Extracellular DNA Promotes β-Amyloid Aggregation

2021 ◽  
Vol 9 (6) ◽  
pp. 1301
Author(s):  
George Tetz ◽  
Victor Tetz
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Misfolding ◽  
Amyloid Β ◽  
Extracellular Dna ◽  
Bacterial Dna ◽  
Aβ Aggregation ◽  
The Brain

Alzheimer’s disease is associated with prion-like aggregation of the amyloid β (Aβ) peptide and the subsequent accumulation of misfolded neurotoxic aggregates in the brain. Therefore, it is critical to clearly identify the factors that trigger the cascade of Aβ misfolding and aggregation. Numerous studies have pointed out the association between microorganisms and their virulence factors and Alzheimer’s disease; however, their exact mechanisms of action remain unclear. Recently, we discovered a new pathogenic role of bacterial extracellular DNA, triggering the formation of misfolded Tau aggregates. In this study, we investigated the possible role of DNA extracted from different bacterial and eukaryotic cells in triggering Aβ aggregation in vitro. Interestingly, we found that the extracellular DNA of some, but not all, bacteria is an effective trigger of Aβ aggregation. Furthermore, the acceleration of Aβ nucleation and elongation can vary based on the concentration of the bacterial DNA and the bacterial strain from which this DNA had originated. Our findings suggest that bacterial extracellular DNA might play a previously overlooked role in the Aβ protein misfolding associated with Alzheimer’s disease pathogenesis. Moreover, it highlights a new mechanism of how distantly localized bacteria can remotely contribute to protein misfolding and diseases associated with this process. These findings might lead to the use of bacterial DNA as a novel therapeutic target for the prevention and treatment of Alzheimer’s disease.

scholarly journals A rationally designed bicyclic peptide remodels Aβ42 aggregation in vitro and reduces its toxicity in a worm model of Alzheimer’s disease

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tatsuya Ikenoue ◽  
Francesco A. Aprile ◽  
Pietro Sormanni ◽  
Francesco S. Ruggeri ◽  
Michele Perni ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Rational Design ◽  
Therapeutic Potential ◽  
Amyloid Β ◽  
Disordered Proteins ◽  
Amyloid Β Peptide ◽  
Model Of Alzheimer’S Disease ◽  
Worm Model

Abstract Bicyclic peptides have great therapeutic potential since they can bridge the gap between small molecules and antibodies by combining a low molecular weight of about 2 kDa with an antibody-like binding specificity. Here we apply a recently developed in silico rational design strategy to produce a bicyclic peptide to target the C-terminal region (residues 31–42) of the 42-residue form of the amyloid β peptide (Aβ42), a protein fragment whose aggregation into amyloid plaques is linked with Alzheimer’s disease. We show that this bicyclic peptide is able to remodel the aggregation process of Aβ42 in vitro and to reduce its associated toxicity in vivo in a C. elegans worm model expressing Aβ42. These results provide an initial example of a computational approach to design bicyclic peptides to target specific epitopes on disordered proteins.

scholarly journals Cu-Based Turn-on Fluorescent Sensors for Cu-rich Amyloid β Aggregates

2021 ◽  
Author(s):  
Yiran Huang ◽  
Liang Sun ◽  
Liviu M. Mirica
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Fluorescence Imaging ◽  
Protein Misfolding ◽  
Picolinic Acid ◽  
Amyloid Β ◽  
Fluorescent Sensors ◽  
Aβ Oligomers ◽  
Turn On ◽  
Aβ Aggregation

<div>Protein misfolding and metal dishomeostasis are two key</div><div>pathological factors of Alzheimer’s disease. Previous studies have showed that Cu‐mediated Aβ aggregation pathways lead to formation of neurotoxic Aβ oligomers. Herein, we reported a series of picolinic acid‐based Cu‐activatable sensors, which can be used for the fluorescence imaging of Cu‐rich Aβ aggregates.</div>

scholarly journals In Vitro and In Vivo Efficacies of the Linear and the Cyclic Version of an All-d-Enantiomeric Peptide Developed for the Treatment of Alzheimer’s Disease

2021 ◽  
Vol 22 (12) ◽  
pp. 6553
Author(s):  
Sarah Schemmert ◽  
Luana Cristina Camargo ◽  
Dominik Honold ◽  
Ian Gering ◽  
Janine Kutzsche ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Β ◽  
Pharmacokinetic Profile ◽  
Rational Drug Design ◽  
Multiple Sources ◽  
Aβ Oligomers ◽  
Rational Drug

Multiple sources of evidence suggest that soluble amyloid β (Aβ)-oligomers are responsible for the development and progression of Alzheimer’s disease (AD). In order to specifically eliminate these toxic Aβ-oligomers, our group has developed a variety of all-d-peptides over the past years. One of them, RD2, has been intensively studied and showed such convincing in vitro and in vivo properties that it is currently in clinical trials. In order to further optimize the compounds and to elucidate the characteristics of therapeutic d-peptides, several rational drug design approaches have been performed. Two of these d-peptides are the linear tandem (head-to-tail) d-peptide RD2D3 and its cyclized form cRD2D3. Tandemization and cyclization should result in an increased in vitro potency and increase pharmacokinetic properties, especially crossing the blood­–brain-barrier. In comparison, cRD2D3 showed a superior pharmacokinetic profile to RD2D3. This fact suggests that higher efficacy can be achieved in vivo at equally administered concentrations. To prove this hypothesis, we first established the in vitro profile of both d-peptides here. Subsequently, we performed an intraperitoneal treatment study. This study failed to provide evidence that cRD2D3 is superior to RD2D3 in vivo as in some tests cRD2D3 failed to show equal or higher efficacy.

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