scholarly journals A Chemical Chaperone That Prevents Insulin Fibrillation

2021 ◽  
Author(s):  
Anirban Das ◽  
Yogesh Gangarde ◽  
Ishu Saraogi
Keyword(s):  
Peptide Hormone ◽  
Soluble Form ◽  
Aggregation Kinetics ◽  
Amyloid Formation ◽  
Native Structure ◽  
Chemical Chaperone ◽  
Physiological Conditions ◽  
Toxic Species ◽  
Primary Nucleation ◽  
Binding Experiment

Insulin, a peptide hormone, is susceptible to amyloid formation upon exposure to aberrant physiological conditions, result-ing in a loss of its bioactivity. For mitigating insulin aggregation, we report a molecule called PAD-S, which completely inhibit-ed insulin fibril formation, and preserved insulin in its soluble form. Circular Dichroism spectroscopy showed that PAD-S was able to maintain the native structure of insulin, thus acting as a chemical chaperone. Seeded aggregation kinetics suggest that PAD-S inhibited primary nucleation events during aggregation. This is consistent with molecular docking results which suggest that PAD-S binds strongly to native insulin monomers/dimers. Through a competitive binding experiment with ‘LVEALYL’ peptide, we conclude that PAD-S likely binds to the amyloid prone B11-B17 residues of insulin thereby prevent-ing its aggregation. PAD-S was also effective in disaggregating preformed insulin fibrils to non-toxic species. PAD-S treated insulin was functional as indicated by its ability to phosphorylate Akt. PAD-S was also highly effective in preventing the ag-gregation of insulin biosimilars. The low cellular cytotoxicity of PAD-S, and amelioration of aggregation-induced toxicity by PAD-S treated insulin further highlights its potential as an effective chemical chaperone.

scholarly journals An anticancer drug suppresses the primary nucleation reaction that initiates the production of the toxic Aβ42 aggregates linked with Alzheimer’s disease

2016 ◽  
Vol 2 (2) ◽  
pp. e1501244 ◽  
Author(s):  
Johnny Habchi ◽  
Paolo Arosio ◽  
Michele Perni ◽  
Ana Rita Costa ◽  
Maho Yagi-Utsumi ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Anticancer Drug ◽  
Self Assembly ◽  
Molecular Mechanisms ◽  
Neuroblastoma Cells ◽  
Toxic Species ◽  
Primary Nucleation ◽  
Rational Drug ◽  
Amyloid Aβ

The conversion of the β-amyloid (Aβ) peptide into pathogenic aggregates is linked to the onset and progression of Alzheimer’s disease. Although this observation has prompted an extensive search for therapeutic agents to modulate the concentration of Aβ or inhibit its aggregation, all clinical trials with these objectives have so far failed, at least in part because of a lack of understanding of the molecular mechanisms underlying the process of aggregation and its inhibition. To address this problem, we describe a chemical kinetics approach for rational drug discovery, in which the effects of small molecules on the rates of specific microscopic steps in the self-assembly of Aβ42, the most aggregation-prone variant of Aβ, are analyzed quantitatively. By applying this approach, we report that bexarotene, an anticancer drug approved by the U.S. Food and Drug Administration, selectively targets the primary nucleation step in Aβ42 aggregation, delays the formation of toxic species in neuroblastoma cells, and completely suppresses Aβ42 deposition and its consequences in a Caenorhabditis elegans model of Aβ42-mediated toxicity. These results suggest that the prevention of the primary nucleation of Aβ42 by compounds such as bexarotene could potentially reduce the risk of onset of Alzheimer’s disease and, more generally, that our strategy provides a general framework for the rational identification of a range of candidate drugs directed against neurodegenerative disorders.

A2T and A2V Aβ peptides exhibit different aggregation kinetics, primary nucleation, morphology, structure, and LTP inhibition

2016 ◽  
Vol 84 (4) ◽  
pp. 488-500 ◽  
Author(s):  
Brian Murray ◽  
Mirco Sorci ◽  
Joseph Rosenthal ◽  
Jennifer Lippens ◽  
David Isaacson ◽  
...  
Keyword(s):  
Aggregation Kinetics ◽  
Aβ Peptides ◽  
Primary Nucleation

scholarly journals Time-resolved studies define the nature of toxic IAPP intermediates, providing insight for anti-amyloidosis therapeutics

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Andisheh Abedini ◽  
Annette Plesner ◽  
Ping Cao ◽  
Zachary Ridgway ◽  
Jinghua Zhang ◽  
...  
Keyword(s):  
Cell Death ◽  
Rational Drug Design ◽  
Amyloid Formation ◽  
Β Cell ◽  
Time Resolved ◽  
Toxic Species ◽  
Aromatic Interactions ◽  
Rational Drug ◽  
The Common ◽  
Β Sheet

Islet amyloidosis by IAPP contributes to pancreatic β-cell death in diabetes, but the nature of toxic IAPP species remains elusive. Using concurrent time-resolved biophysical and biological measurements, we define the toxic species produced during IAPP amyloid formation and link their properties to induction of rat INS-1 β-cell and murine islet toxicity. These globally flexible, low order oligomers upregulate pro-inflammatory markers and induce reactive oxygen species. They do not bind 1-anilnonaphthalene-8-sulphonic acid and lack extensive β-sheet structure. Aromatic interactions modulate, but are not required for toxicity. Not all IAPP oligomers are toxic; toxicity depends on their partially structured conformational states. Some anti-amyloid agents paradoxically prolong cytotoxicity by prolonging the lifetime of the toxic species. The data highlight the distinguishing properties of toxic IAPP oligomers and the common features that they share with toxic species reported for other amyloidogenic polypeptides, providing information for rational drug design to treat IAPP induced β-cell death.

scholarly journals Members of the GADD45 Protein Family Show Distinct Propensities to form Toxic Amyloid-Like Aggregates in Physiological Conditions

2021 ◽  
Vol 22 (19) ◽  
pp. 10700
Author(s):  
Giovanni Smaldone ◽  
Daniela Caruso ◽  
Annamaria Sandomenico ◽  
Emanuela Iaccarino ◽  
Annalia Focà ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Protein Family ◽  
Label Free ◽  
Cellular Functions ◽  
Physiological Conditions ◽  
Toxic Species ◽  
High Molecular Weight Species ◽  
Functional Implications ◽  
Uv Visible ◽  
Strong Interactors

The three members (GADD45α, GADD45β, and GADD45γ) of the growth arrest and DNA damage-inducible 45 (GADD45) protein family are involved in a myriad of diversified cellular functions. With the aim of unravelling analogies and differences, we performed comparative biochemical and biophysical analyses on the three proteins. The characterization and quantification of their binding to the MKK7 kinase, a validated functional partner of GADD45β, indicate that GADD45α and GADD45γ are strong interactors of the kinase. Despite their remarkable sequence similarity, the three proteins present rather distinct biophysical properties. Indeed, while GADD45β and GADD45γ are marginally stable at physiological temperatures, GADD45α presents the Tm value expected for a protein isolated from a mesophilic organism. Surprisingly, GADD45α and GADD45β, when heated, form high-molecular weight species that exhibit features (ThT binding and intrinsic label-free UV/visible fluorescence) proper of amyloid-like aggregates. Cell viability studies demonstrate that they are endowed with a remarkable toxicity against SHSY-5Y and HepG2 cells. The very uncommon property of GADD45β to form cytotoxic species in near-physiological conditions represents a puzzling finding with potential functional implications. Finally, the low stability and/or the propensity to form toxic species of GADD45 proteins constitute important features that should be considered in interpreting their many functions.

scholarly journals Cross-talk between individual phenol-soluble modulins in Staphylococcus aureus biofilm enables rapid and efficient amyloid formation

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Masihuz Zaman ◽  
Maria Andreasen
Keyword(s):  
Staphylococcus Aureus ◽  
Self Assembly ◽  
Biofilm Formation ◽  
Opportunistic Pathogen ◽  
Amyloid Formation ◽  
Secondary Nucleation ◽  
Primary Nucleation ◽  
Functional Amyloids ◽  
High Degree

The infective ability of the opportunistic pathogen Staphylococcus aureus, recognized as the most frequent cause of biofilm-associated infections, is associated with biofilm-mediated resistance to host immune response. Phenol-soluble modulins (PSM) comprise the structural scaffold of S. aureus biofilms through self-assembly into functional amyloids, but the role of individual PSMs during biofilm formation remains poorly understood and the molecular pathways of PSM self-assembly are yet to be identified. Here we demonstrate high degree of cooperation between individual PSMs during functional amyloid formation. PSMα3 initiates the aggregation, forming unstable aggregates capable of seeding other PSMs resulting in stable amyloid structures. Using chemical kinetics we dissect the molecular mechanism of aggregation of individual PSMs showing that PSMα1, PSMα3 and PSMβ1 display secondary nucleation whereas PSMβ2 aggregates through primary nucleation and elongation. Our findings suggest that various PSMs have evolved to ensure fast and efficient biofilm formation through cooperation between individual peptides.

scholarly journals SERF engages in a fuzzy complex that accelerates primary nucleation of amyloid proteins

2019 ◽  
Vol 116 (46) ◽  
pp. 23040-23049 ◽  
Author(s):  
Ben A. Meinen ◽  
Varun V. Gadkari ◽  
Frederick Stull ◽  
Brandon T. Ruotolo ◽  
James C. A. Bardwell
Keyword(s):  
Ion Mobility ◽  
Amyloid Fibrils ◽  
Structural Diversity ◽  
Disordered Proteins ◽  
Amyloid Formation ◽  
Disordered Protein ◽  
Primary Nucleation ◽  
Age Related ◽  
Related Proteins ◽  
High Degree

The assembly of small disordered proteins into highly ordered amyloid fibrils in Alzheimer’s and Parkinson’s patients is closely associated with dementia and neurodegeneration. Understanding the process of amyloid formation is thus crucial in the development of effective treatments for these devastating neurodegenerative diseases. Recently, a tiny, highly conserved and disordered protein called SERF was discovered to modify amyloid formation in Caenorhabditis elegans and humans. Here, we use kinetics measurements and native ion mobility-mass spectrometry to show that SERF mainly affects the rate of primary nucleation in amyloid formation for the disease-related proteins Aβ40 and α-synuclein. SERF’s high degree of plasticity enables it to bind various conformations of monomeric Aβ40 and α-synuclein to form structurally diverse, fuzzy complexes. This structural diversity persists into early stages of amyloid formation. Our results suggest that amyloid nucleation is considerably more complex than age-related conversion of Aβ40 and α-synuclein into single amyloid-prone conformations.

scholarly journals Mechanism of amyloid protein aggregation and the role of inhibitors

2019 ◽  
Vol 91 (2) ◽  
pp. 211-229 ◽  
Author(s):  
Sara Linse
Keyword(s):  
Total Concentration ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Aggregation Process ◽  
Secondary Nucleation ◽  
Toxic Species ◽  
Primary Nucleation ◽  
Effective Inhibition ◽  
Aβ Aggregation

Abstract Inhibition of amyloid β peptide (Aβ) aggregation is an important goal due to the connection of this process with Alzheimer’s disease. Traditionally, inhibitors were developed with an aim to retard the overall macroscopic aggregation. However, recent advances imply that approaches based on mechanistic insights may be more powerful. In such approaches, the microscopic steps underlying the aggregation process are identified, and it is established which of these step(s) lead to neurotoxicity. Inhibitors are then derived to specifically target steps involved in toxicity. The Aβ aggregation process is composed of at minimum three microscopic steps: primary nucleation of monomers only, secondary nucleation of monomers on fibril surface, and elongation of fibrils by monomer addition. The vast majority of toxic species are generated from the secondary nucleation process: this may be a key process to inhibit in order to limit toxicity. Inhibition of primary nucleation, which delays the emergence of toxic species without affecting their total concentration, may also be effective. Inhibition of elongation may instead increase the toxicity over time. Here we briefly review findings regarding secondary nucleation of Aβ, its dominance over primary nucleation, and attempts to derive inhibitors that specifically target secondary nucleation with an aim to limit toxicity.

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