scholarly journals Bacterial production and direct functional screening of expanded molecular libraries for discovering inhibitors of protein aggregation

2019 ◽  
Vol 5 (10) ◽  
pp. eaax5108 ◽  
Author(s):  
Dafni C. Delivoria ◽  
Sean Chia ◽  
Johnny Habchi ◽  
Michele Perni ◽  
Ilias Matis ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Early Stage ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Functional Screening ◽  
Parkinson’S Diseases ◽  
Aggregation Inhibitors ◽  
Molecular Libraries

Protein misfolding and aggregation are associated with a many human disorders, including Alzheimer’s and Parkinson’s diseases. Toward increasing the effectiveness of early-stage drug discovery for these conditions, we report a bacterial platform that enables the biosynthesis of molecular libraries with expanded diversities and their direct functional screening for discovering protein aggregation inhibitors. We illustrate this approach by performing, what is to our knowledge, the largest functional screen of small-size molecular entities described to date. We generated a combinatorial library of ~200 million drug-like, cyclic peptides and rapidly screened it for aggregation inhibitors against the amyloid-β peptide (Aβ42), linked to Alzheimer’s disease. Through this procedure, we identified more than 400 macrocyclic compounds that efficiently reduce Aβ42 aggregation and toxicity in vitro and in vivo. Finally, we applied a combination of deep sequencing and mutagenesis analyses to demonstrate how this system can rapidly determine structure-activity relationships and define consensus motifs required for bioactivity.

Phenolic Acids Exert Anticholinesterase and Cognition-Improving Effects

2018 ◽  
Vol 15 (6) ◽  
pp. 531-543 ◽  
Author(s):  
Dominik Szwajgier ◽  
Ewa Baranowska-Wojcik ◽  
Kamila Borowiec
Keyword(s):  
Phenolic Acids ◽  
Ex Vivo ◽  
Amyloid Β ◽  
Inhibitory Effect ◽  
In Vivo Studies ◽  
Amyloid Β Peptide ◽  
Beneficial Effects ◽  
Aβ Fibrils

Numerous authors have provided evidence regarding the beneficial effects of phenolic acids and their derivatives against Alzheimer's disease (AD). In this review, the role of phenolic acids as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) is discussed, including the structure-activity relationship. In addition, the inhibitory effect of phenolic acids on the formation of amyloid β-peptide (Aβ) fibrils is presented. We also cover the in vitro, ex vivo, and in vivo studies concerning the prevention and treatment of the cognitive enhancement.

scholarly journals The Amyloid Fibril-Forming β-Sheet Regions of Amyloid β and α-Synuclein Preferentially Interact with the Molecular Chaperone 14-3-3ζ

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6120
Author(s):  
Danielle M. Williams ◽  
David C. Thorn ◽  
Christopher M. Dobson ◽  
Sarah Meehan ◽  
Sophie E. Jackson ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Molecular Chaperones ◽  
Protein Unfolding ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Parkinson’S Diseases ◽  
Amino Acid Form ◽  
Shock Proteins

14-3-3 proteins are abundant, intramolecular proteins that play a pivotal role in cellular signal transduction by interacting with phosphorylated ligands. In addition, they are molecular chaperones that prevent protein unfolding and aggregation under cellular stress conditions in a similar manner to the unrelated small heat-shock proteins. In vivo, amyloid β (Aβ) and α-synuclein (α-syn) form amyloid fibrils in Alzheimer’s and Parkinson’s diseases, respectively, a process that is intimately linked to the diseases’ progression. The 14-3-3ζ isoform potently inhibited in vitro fibril formation of the 40-amino acid form of Aβ (Aβ40) but had little effect on α-syn aggregation. Solution-phase NMR spectroscopy of 15N-labeled Aβ40 and A53T α-syn determined that unlabeled 14-3-3ζ interacted preferentially with hydrophobic regions of Aβ40 (L11-H21 and G29-V40) and α-syn (V3-K10 and V40-K60). In both proteins, these regions adopt β-strands within the core of the amyloid fibrils prepared in vitro as well as those isolated from the inclusions of diseased individuals. The interaction with 14-3-3ζ is transient and occurs at the early stages of the fibrillar aggregation pathway to maintain the native, monomeric, and unfolded structure of Aβ40 and α-syn. The N-terminal regions of α-syn interacting with 14-3-3ζ correspond with those that interact with other molecular chaperones as monitored by in-cell NMR spectroscopy.

scholarly journals Biophysical studies of protein misfolding and aggregation in in vivo models of Alzheimer's and Parkinson's diseases

2020 ◽  
Vol 53 ◽  
Author(s):  
Tessa Sinnige ◽  
Karen Stroobants ◽  
Christopher M. Dobson ◽  
Michele Vendruscolo
Keyword(s):  
Protein Misfolding ◽  
Molecular Mechanisms ◽  
Amyloid Β ◽  
Therapeutic Interventions ◽  
In Vivo Models ◽  
Disease Modifying Drugs ◽  
Parkinson’S Diseases ◽  
Protein Misfolding And Aggregation

Abstract Neurodegenerative disorders, including Alzheimer's (AD) and Parkinson's diseases (PD), are characterised by the formation of aberrant assemblies of misfolded proteins. The discovery of disease-modifying drugs for these disorders is challenging, in part because we still have a limited understanding of their molecular origins. In this review, we discuss how biophysical approaches can help explain the formation of the aberrant conformational states of proteins whose neurotoxic effects underlie these diseases. We discuss in particular models based on the transgenic expression of amyloid-β (Aβ) and tau in AD, and α-synuclein in PD. Because biophysical methods have enabled an accurate quantification and a detailed understanding of the molecular mechanisms underlying protein misfolding and aggregation in vitro, we expect that the further development of these methods to probe directly the corresponding mechanisms in vivo will open effective routes for diagnostic and therapeutic interventions.

scholarly journals Squalamine and Its Derivatives Modulate the Aggregation of Amyloid-β and α-Synuclein and Suppress the Toxicity of Their Oligomers

2021 ◽  
Vol 15 ◽  
Author(s):  
Ryan Limbocker ◽  
Roxine Staats ◽  
Sean Chia ◽  
Francesco S. Ruggeri ◽  
Benedetta Mannini ◽  
...  
Keyword(s):  
Small Molecules ◽  
Neuroblastoma Cells ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Human Neuroblastoma Cells ◽  
Human Neuroblastoma ◽  
Parkinson’S Diseases ◽  
Wide Range ◽  
Opposing Effects

The aberrant aggregation of proteins is a key molecular event in the development and progression of a wide range of neurodegenerative disorders. We have shown previously that squalamine and trodusquemine, two natural products in the aminosterol class, can modulate the aggregation of the amyloid-β peptide (Aβ) and of α-synuclein (αS), which are associated with Alzheimer’s and Parkinson’s diseases. In this work, we expand our previous analyses to two squalamine derivatives, des-squalamine and α-squalamine, obtaining further insights into the mechanism by which aminosterols modulate Aβ and αS aggregation. We then characterize the ability of these small molecules to alter the physicochemical properties of stabilized oligomeric species in vitro and to suppress the toxicity of these aggregates to varying degrees toward human neuroblastoma cells. We found that, despite the fact that these aminosterols exert opposing effects on Aβ and αS aggregation under the conditions that we tested, the modifications that they induced to the toxicity of oligomers were similar. Our results indicate that the suppression of toxicity is mediated by the displacement of toxic oligomeric species from cellular membranes by the aminosterols. This study, thus, provides evidence that aminosterols could be rationally optimized in drug discovery programs to target oligomer toxicity in Alzheimer’s and Parkinson’s diseases.

scholarly journals Soluble α-synuclein–antibody complexes activate the NLRP3 inflammasome in hiPSC-derived microglia

2021 ◽  
Vol 118 (15) ◽  
pp. e2025847118
Author(s):  
Dorit Trudler ◽  
Kristopher L. Nazor ◽  
Yvonne S. Eisele ◽  
Titas Grabauskas ◽  
Nima Dolatabadi ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Amyloid Β ◽  
Induced Pluripotent Stem Cell ◽  
Amyloid Β Peptide ◽  
Human Microglia ◽  
Pyrin Domain ◽  
Toll Like Receptor 2 ◽  
Induced Pluripotent

Parkinson’s disease is characterized by accumulation of α-synuclein (αSyn). Release of oligomeric/fibrillar αSyn from damaged neurons may potentiate neuronal death in part via microglial activation. Heretofore, it remained unknown if oligomeric/fibrillar αSyn could activate the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome in human microglia and whether anti-αSyn antibodies could prevent this effect. Here, we show that αSyn activates the NLRP3 inflammasome in human induced pluripotent stem cell (hiPSC)-derived microglia (hiMG) via dual stimulation involving Toll-like receptor 2 (TLR2) engagement and mitochondrial damage. In vitro, hiMG can be activated by mutant (A53T) αSyn secreted from hiPSC-derived A9-dopaminergic neurons. Surprisingly, αSyn–antibody complexes enhanced rather than suppressed inflammasome-mediated interleukin-1β (IL-1β) secretion, indicating these complexes are neuroinflammatory in a human context. A further increase in inflammation was observed with addition of oligomerized amyloid-β peptide (Aβ) and its cognate antibody. In vivo, engraftment of hiMG with αSyn in humanized mouse brain resulted in caspase-1 activation and neurotoxicity, which was exacerbated by αSyn antibody. These findings may have important implications for antibody therapies aimed at depleting misfolded/aggregated proteins from the human brain, as they may paradoxically trigger inflammation in human microglia.

scholarly journals Neuropharmacological Effects of Quercetin: A Literature-Based Review

2021 ◽  
Vol 12 ◽  
Author(s):  
Md. Shahazul Islam ◽  
Cristina Quispe ◽  
Rajib Hossain ◽  
Muhammad Torequl Islam ◽  
Ahmed Al-Harrasi ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Neuroprotective Effect ◽  
Animal Experiments ◽  
Amyloid Β ◽  
Neuronal Injury ◽  
Amyloid Β Peptide ◽  
Protective Effects ◽  
Neuroprotective Effects

Quercetin (QUR) is a natural bioactive flavonoid that has been lately very studied for its beneficial properties in many pathologies. Its neuroprotective effects have been demonstrated in many in vitro studies, as well as in vivo animal experiments and human trials. QUR protects the organism against neurotoxic chemicals and also can prevent the evolution and development of neuronal injury and neurodegeneration. The present work aimed to summarize the literature about the neuroprotective effect of QUR using known database sources. Besides, this review focuses on the assessment of the potential utilization of QUR as a complementary or alternative medicine for preventing and treating neurodegenerative diseases. An up-to-date search was conducted in PubMed, Science Direct and Google Scholar for published work dealing with the neuroprotective effects of QUR against neurotoxic chemicals or in neuronal injury, and in the treatment of neurodegenerative diseases. Findings suggest that QUR possess neuropharmacological protective effects in neurodegenerative brain disorders such as Alzheimer’s disease, Amyloid β peptide, Parkinson’s disease, Huntington's disease, multiple sclerosis, and amyotrophic lateral sclerosis. In summary, this review emphasizes the neuroprotective effects of QUR and its advantages in being used in complementary medicine for the prevention and treatment o of different neurodegenerative diseases.

An Aβ42 variant that inhibits intra- and extracellular amyloid aggregation and enhances cell viability

2018 ◽  
Vol 475 (19) ◽  
pp. 3087-3103 ◽  
Author(s):  
Ofek Oren ◽  
Victor Banerjee ◽  
Ran Taube ◽  
Niv Papo
Keyword(s):  
Amyloid Fibrils ◽  
Neuronal Cells ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Amyloid Β Peptide ◽  
Cell Cytotoxicity ◽  
Amyloid Aggregation ◽  
Molar Ratios

Aggregation and accumulation of the 42-residue amyloid β peptide (Aβ42) in the extracellular matrix and within neuronal cells is considered a major cause of neuronal cell cytotoxicity and death in Alzheimer's disease (AD) patients. Therefore, molecules that bind to Aβ42 and prevent its aggregation are therapeutically promising as AD treatment. Here, we show that a non-self-aggregating Aβ42 variant carrying two surface mutations, F19S and L34P (Aβ42DM), inhibits wild-type Aβ42 aggregation and significantly reduces Aβ42-mediated cell cytotoxicity. In addition, Aβ42DM inhibits the uptake and internalization of extracellularly added pre-formed Aβ42 aggregates into cells. This was the case in both neuronal and non-neuronal cells co-expressing Aβ42 and Aβ42DM or following pre-treatment of cells with extracellular soluble forms of the two peptides, even at high Aβ42 to Aβ42DM molar ratios. In cells, Aβ42DM associates with Aβ42, while in vitro, the two soluble recombinant peptides exhibit nano-molar binding affinity. Importantly, Aβ42DM potently suppresses Aβ42 amyloid aggregation in vitro, as demonstrated by thioflavin T fluorescence and transmission electron microscopy for detecting amyloid fibrils. Overall, we present a new approach for inhibiting Aβ42 fibril formation both within and outside cells. Accordingly, Aβ42DM should be evaluated in vivo for potential use as a therapeutic lead for treating AD.

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