scholarly journals Looking for a generic inhibitor of amyloid-like fibril formation among flavone derivatives

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1271 ◽  
Author(s):  
Tomas Šneideris ◽  
Lina Baranauskienė ◽  
Jonathan G. Cannon ◽  
Rasa Rutkienė ◽  
Rolandas Meškys ◽  
...  
Keyword(s):  
Beta Amyloid ◽  
Structural Features ◽  
Alpha Synuclein ◽  
Fibril Formation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Amyloid Fibril Formation ◽  
Flavone Derivatives ◽  
Alpha Synuclein Aggregation

A range of diseases is associated with amyloid fibril formation. Despite different proteins being responsible for each disease, all of them share similar features including beta-sheet-rich secondary structure and fibril-like protein aggregates. A number of proteins can form amyloid-like fibrilsin vitro, resembling structural features of disease-related amyloids. Given these generic structural properties of amyloid and amyloid-like fibrils, generic inhibitors of fibril formation would be of interest for treatment of amyloid diseases. Recently, we identified five outstanding inhibitors of insulin amyloid-like fibril formation among the pool of 265 commercially available flavone derivatives. Here we report testing of these five compounds and of epi-gallocatechine-3-gallate (EGCG) on aggregation of alpha-synuclein and beta-amyloid. We used a Thioflavin T (ThT) fluorescence assay, relying on halftimes of aggregation as the measure of inhibition. This method avoids large numbers of false positive results. Our data indicate that four of the five flavones and EGCG inhibit alpha-synuclein aggregation in a concentration-dependent manner. However none of these derivatives were able to increase halftimes of aggregation of beta-amyloid.

Lysophosphatidic acid rapidly induces protein kinase D activation through a pertussis toxin-sensitive pathway

2000 ◽  
Vol 278 (1) ◽  
pp. C33-C39 ◽  
Author(s):  
Lina Paolucci ◽  
James Sinnett-Smith ◽  
Enrique Rozengurt
Keyword(s):  
Protein Kinase ◽  
Pertussis Toxin ◽  
Lysophosphatidic Acid ◽  
Kinase Inhibitor ◽  
Structural Features ◽  
Protein Kinase D ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Swiss 3T3

Protein kinase D (PKD) is a serine-threonine protein kinase with distinct structural features and enzymological properties. Herein we demonstrate that lysophosphatidic acid (LPA) induces rapid PKD activation in mouse Swiss 3T3 and Rat-1 cells. LPA induced PKD activation in a concentration-dependent fashion with maximal stimulation (7.6-fold) achieved at 5 μM. Treatment of Swiss 3T3 cells with the protein kinase C (PKC) inhibitors GF-I, Ro-31–8220, and Gö-7874 completely abrogated PKD activation induced by LPA at concentrations that did not inhibit PKD activity when added directly to the in vitro kinase assays. PKD activation induced by LPA was attenuated markedly and selectively by prior exposure of either Swiss 3T3 or Rat-1 cells to pertussis toxin (PTx) in a concentration-dependent manner. In contrast, treatment with the protein tyrosine kinase inhibitor genistein, the MEK inhibitor PD-098059, or the phosphoinositide 3-kinase inhibitor wortmannin did not affect PKD activation in response to LPA. These results provide the first example of PTx-sensitive and PKC-dependent PKD activation and identify a novel Gi-dependent event in the action of LPA.

scholarly journals Structural Features of Three Hetero-Galacturonans from Passiflora foetida Fruits and Their in Vitro Immunomodulatory Effects

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 615 ◽  
Author(s):  
Ya Song ◽  
Peng Wen ◽  
Huili Hao ◽  
Minqian Zhu ◽  
Yuanming Sun ◽  
...  
Keyword(s):  
Structural Features ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Minimum Effective Concentration ◽  
Enhancing Effect ◽  
Traditional Chinese Herbal Medicine ◽  
Raw264.7 Macrophages ◽  
Pharmaceutical Industries ◽  
Passiflora Foetida

Passiflora foetida is a horticultural plant and vital traditional Chinese herbal medicine. In our previous study, the characterization and immuno-enhancing effect of fruits polysaccharide 1 (PFP1), a water-eluted hetero-mannan from wild Passiflora foetida fruits, were investigated. Herein, another three salt-eluted novel polysaccharides, namely PFP2, PFP3, and PFP4, were obtained and structurally characterized. The results showed that PFP2, PFP3, and PFP4 were three structurally similar hetero-galacturonans with different molecular weights of 6.11 × 104, 4.37 × 104, and 3.48 × 105 g/mol, respectively. All three of these hetero-galacturonans are mainly composed of galacturonic acid, galactose, arabinose (75.69%, 80.39%, and 74.30%, respectively), and other monosaccharides including mannose, fucose, glucose, ribose, xylose, and glucuronic acid (24.31%, 19.61, and 25.70%, respectively), although differences in their backbone structure exist. Additionally, immunomodulatory assay indicated that the three hetero-galacturonans possess the ability to promote the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in RAW264.7 macrophages in a concentration-dependent manner (p < 0.05). Especially, PFP3 displayed a stronger enhancing effect than PFP2 and PFP4 at the minimum effective concentration. Therefore, the results suggested that the obtained three salt-eluted hetero-galacturonans, especially PFP3, could be utilized as immunomodulatory effectivity ingredients in nutritional/pharmaceutical industries.

Inhibition of amyloid fibrillation of HEWL by 4-methylcoumarin and 4- methylthiocoumarin derivatives

2020 ◽  
Vol 21 ◽  
Author(s):  
Shivani Kumar ◽  
Manoj Kumar ◽  
Yogesh Kumar Tyagi ◽  
Suresh Kumar
Keyword(s):  
Molecular Dynamics ◽  
Protein Aggregation ◽  
Fibril Formation ◽  
Significant Inhibition ◽  
Fluorescence Assay ◽  
Intrinsic Fluorescence ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Amyloid Fibrillation

Background: Several human diseases like Parkinson’s, Alzheimer’s disease, and systemic amyloidosis are associated with the misfolding and aggregation of protein molecules. Objective: The present study demonstrated the comparison of 4-methyl coumarin and 4methylthiocoumarin derivative for their anti-amyloidogenic and disaggregation activity. The hen egg-white lysozyme is used as a model system to study protein aggregation and disaggregation under in vitro conditions. Methods: Techniques used in the study were Thioflavin T fluorescence assay, intrinsic fluorescence assay, circular dichroism, transmission electron microscopy, and molecular dynamics. Results: Fifteen compounds were screened for their anti-amyloidogenic and disaggregation potential. Six compounds significantly inhibited the fibril formation, whereas ten compounds showed disaggregation property of pre-formed fibrils. Under in vitro conditions, the compound C3 and C7 showed significant inhibition of fibril formation in a concentration-dependent manner as compared to control. C3 and C7 demonstrated 93% and 76% inhibition of fibril formation, respectively. Discussion: Furthermore, C3 and C7 exhibited 83% and 76% disaggregation activity, respectively, of pre-formed HEWL fibrils at their highest concentration. These anti-amyloidogenic and disaggregation potential of C3 and C7 were validated by intrinsic fluorescence, CD, molecular dynamics, and TEM study. Conclusion: C3 and C7 are novel 4-methylthiocoumarin derivatives that can be used as a lead for alleviation and symptoms associated with protein aggregation disorders.

scholarly journals Influence of specific HSP70 domains on fibril formation of the yeast prion protein Ure2

2013 ◽  
Vol 368 (1617) ◽  
pp. 20110410 ◽  
Author(s):  
Li-Qiong Xu ◽  
Si Wu ◽  
Alexander K. Buell ◽  
Samuel I. A. Cohen ◽  
Li-Jun Chen ◽  
...  
Keyword(s):  
Fibril Formation ◽  
Structural Basis ◽  
Dependent Manner ◽  
Atpase Domain ◽  
Concentration Dependent Manner ◽  
Hsp70 Family ◽  
Constitutive Overexpression ◽  
Mechanistic Basis ◽  
Substrate Binding Domain

Ure2p is the protein determinant of the Saccharomyces cerevisiae prion state [ URE3 ]. Constitutive overexpression of the HSP70 family member SSA1 cures cells of [ URE3 ]. Here, we show that Ssa1p increases the lag time of Ure2p fibril formation in vitro in the presence or absence of nucleotide. The presence of the HSP40 co-chaperone Ydj1p has an additive effect on the inhibition of Ure2p fibril formation, whereas the Ydj1p H34Q mutant shows reduced inhibition alone and in combination with Ssa1p. In order to investigate the structural basis of these effects, we constructed and tested an Ssa1p mutant lacking the ATPase domain, as well as a series of C-terminal truncation mutants. The results indicate that Ssa1p can bind to Ure2p and delay fibril formation even in the absence of the ATPase domain, but interaction of Ure2p with the substrate-binding domain is strongly influenced by the C-terminal lid region. Dynamic light scattering, quartz crystal microbalance assays, pull-down assays and kinetic analysis indicate that Ssa1p interacts with both native Ure2p and fibril seeds, and reduces the rate of Ure2p fibril elongation in a concentration-dependent manner. These results provide new insights into the structural and mechanistic basis for inhibition of Ure2p fibril formation by Ssa1p and Ydj1p.

scholarly journals Natural Alkaloid Compounds as Inhibitors for Alpha-Synuclein Seeded Fibril Formation and Toxicity

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3736
Author(s):  
Simona S. Ghanem ◽  
Hend S. Fayed ◽  
Qi Zhu ◽  
Jia-Hong Lu ◽  
Nishant N. Vaikath ◽  
...  
Keyword(s):  
Cell Viability ◽  
Therapeutic Strategy ◽  
Amyloid Fibril ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Fibril Formation ◽  
Amyloid Fibril Formation ◽  
Dependent Cell ◽  
Natural Alkaloid

The accumulation and aggregation of α-synuclein (α-syn) is the main pathologic event in Parkinson’s disease (PD), dementia with Lewy bodies, and multiple system atrophy. α-Syn-seeded fibril formation and its induced toxicity occupy a major role in PD pathogenesis. Thus, assessing compounds that inhibit this seeding process is considered a key towards the therapeutics of synucleinopathies. Using biophysical and biochemical techniques and seeding-dependent cell viability assays, we screened a total of nine natural compounds of alkaloid origin extracted from Chinese medicinal herbs. Of these compounds, synephrine, trigonelline, cytisine, harmine, koumine, peimisine, and hupehenine exhibited in vitro inhibition of α-syn-seeded fibril formation. Furthermore, using cell viability assays, six of these compounds inhibited α-syn-seeding-dependent toxicity. These six potent inhibitors of amyloid fibril formation and toxicity caused by the seeding process represent a promising therapeutic strategy for the treatment of PD and other synucleinopathies.

scholarly journals Microtubule bundling by MAP65-1 protects against severing by inhibiting the binding of katanin

2019 ◽  
Vol 30 (13) ◽  
pp. 1587-1597 ◽  
Author(s):  
Graham M. Burkart ◽  
Ram Dixit
Keyword(s):  
Cortical Microtubule ◽  
Structural Features ◽  
Cross Linking ◽  
Dependent Manner ◽  
Protective Mechanisms ◽  
Concentration Dependent Manner ◽  
Mutant Proteins ◽  
Microtubule Severing ◽  
Biological Studies

The microtubule-severing enzyme katanin (KTN1) regulates the organization and turnover of microtubule arrays by the localized breakdown of microtubule polymers. In land plants, KTN1 activity is essential for the formation of linearly organized cortical microtubule arrays that determine the axis of cell expansion. Cell biological studies have shown that even though KTN1 binds to the sidewalls of single and bundled microtubules, severing activity is restricted to microtubule cross-over and nucleation sites, indicating that cells contain protective mechanisms to prevent indiscriminate microtubule severing. Here, we show that the microtubule-bundling protein MAP65-1 inhibits KTN1-mediated microtubule severing in vitro. Severing is inhibited at bundled microtubule segments and the severing rate of nonbundled microtubules is reduced by MAP65-1 in a concentration-dependent manner. Using various MAP65-1 mutant proteins, we demonstrate that efficient cross-linking of microtubules is crucial for this protective effect and that microtubule binding alone is not sufficient. Reduced severing due to microtubule bundling by MAP65-1 correlated to decreased binding of KTN1 to these microtubules. Taken together, our work reveals that cross-linking of microtubules by MAP65-1 confers resistance to severing by inhibiting the binding of KTN1 and identifies the structural features of MAP65-1 that are important for this activity.

scholarly journals Microtubule bundling by MAP65-1 protects against severing by inhibiting the binding of katanin

2019 ◽  
Author(s):  
Graham M Burkart ◽  
Ram Dixit
Keyword(s):  
Cortical Microtubule ◽  
Structural Features ◽  
Dependent Manner ◽  
Protective Mechanisms ◽  
Concentration Dependent Manner ◽  
Mutant Proteins ◽  
Microtubule Severing ◽  
Biological Studies

ABSTRACTThe microtubule-severing enzyme katanin regulates the organization and turnover of microtubule arrays by the localized breakdown of microtubule polymers. In land plants, katanin (KTN1) activity is essential for the formation of linearly organized cortical microtubule arrays which determine the axis of cell expansion. Cell biological studies have shown that even though KTN1 binds to the sidewalls of single and bundled microtubules, severing activity is restricted to microtubule crossover and nucleation sites, indicating that cells contain protective mechanisms to prevent indiscriminate microtubule severing. Here, we show that the microtubule bundling protein MAP65-1 inhibits KTN1-mediated microtubule severing in vitro. Severing is inhibited at bundled microtubule segments and the severing rate of non-bundled microtubules is reduced by MAP65-1 in a concentration-dependent manner. Using various MAP65-1 mutant proteins, we demonstrate that efficient crosslinking of microtubules is crucial for this protective effect and that microtubule binding alone is not sufficient. Reduced severing due to microtubule bundling by MAP65-1 correlated to decreased binding of KTN1 to these microtubules. Taken together, our work reveals that crosslinking of microtubules by MAP65-1 confers resistance to severing by inhibiting the binding of katanin and identifies the structural features of MAP65-1 that are important for this activity.Highlight SummaryCortical microtubule bundles resist severing in vivo. Here, we show that crosslinking of microtubules by MAP65-1 inhibits severing in a dose-dependent manner by preventing katanin from binding to these microtubules.

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