scholarly journals Desmin forms toxic, seeding-competent amyloid aggregates that persist in muscle fibers

2019 ◽  
Vol 116 (34) ◽  
pp. 16835-16840 ◽  
Author(s):  
Niraja Kedia ◽  
Khalid Arhzaouy ◽  
Sara K. Pittman ◽  
Yuanzi Sun ◽  
Mark Batchelor ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Therapeutic Potential ◽  
Epigallocatechin Gallate ◽  
Amyloid Formation ◽  
Myofibrillar Myopathy ◽  
Protein Aggregate ◽  
Disease Mutations ◽  
Amyloid Aggregates ◽  
Associated Proteins

Desmin-associated myofibrillar myopathy (MFM) has pathologic similarities to neurodegeneration-associated protein aggregate diseases. Desmin is an abundant muscle-specific intermediate filament, and disease mutations lead to its aggregation in cells, animals, and patients. We reasoned that similar to neurodegeneration-associated proteins, desmin itself may form amyloid. Desmin peptides corresponding to putative amyloidogenic regions formed seeding-competent amyloid fibrils. Amyloid formation was increased when disease-associated mutations were made within the peptide, and this conversion was inhibited by the anti-amyloid compound epigallocatechin-gallate. Moreover, a purified desmin fragment (aa 117 to 348) containing both amyloidogenic regions formed amyloid fibrils under physiologic conditions. Desmin fragment-derived amyloid coaggregated with full-length desmin and was able to template its conversion into fibrils in vitro. Desmin amyloids were cytotoxic to myotubes and disrupted their myofibril organization compared with desmin monomer or other nondesmin amyloids. Finally, desmin fragment amyloid persisted when introduced into mouse skeletal muscle. These data suggest that desmin forms seeding-competent amyloid that is toxic to myofibers. Moreover, small molecules known to interfere with amyloid formation and propagation may have therapeutic potential in MFM.

scholarly journals The Human NUP58 Nucleoporin Can Form Amyloids In Vitro and In Vivo

Biomedicines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1451
Author(s):  
Lavrentii G. Danilov ◽  
Svetlana E. Moskalenko ◽  
Andrew G. Matveenko ◽  
Xenia V. Sukhanova ◽  
Mikhail V. Belousov ◽  
...  
Keyword(s):  
Phase Separation ◽  
Disulfide Bonds ◽  
Amyloid Fibrils ◽  
Bioinformatic Analysis ◽  
Amyloid Formation ◽  
Amyloid Aggregates ◽  
Protease Treatment

Amyloids are fibrillar protein aggregates with a cross-β structure and unusual features, including high resistance to detergent or protease treatment. More than two hundred different proteins with amyloid or amyloid-like properties are already known. Several examples of nucleoporins (e.g., yeast Nup49, Nup100, Nup116, and human NUP153) are supposed to form amyloid fibrils. In this study, we demonstrated an ability of the human NUP58 nucleoporin to form amyloid aggregates in vivo and in vitro. Moreover, we found two forms of NUP58 aggregates: oligomers and polymers stabilized by disulfide bonds. Bioinformatic analysis revealed that all known orthologs of this protein are potential amyloids which possess several regions with conserved ability to aggregation. The biological role of nucleoporin amyloid formation is debatable. We suggest that it is a rather abnormal process, which is characteristic for many proteins implicated in phase separation.

scholarly journals Deletion of Serf2 shifts amyloid conformation in an Aβ amyloid mouse model

2021 ◽  
Author(s):  
E. Stroo ◽  
L. Janssen ◽  
O. Sin ◽  
W. Hogewerf ◽  
M. Koster ◽  
...  
Keyword(s):  
Mouse Model ◽  
Amyloid Fibrils ◽  
Mammalian Brain ◽  
Amyloid Formation ◽  
List Type ◽  
Lung Maturation ◽  
Disease Manifestation ◽  
Aβ Amyloid ◽  
Perinatal Lethality

AbstractNeurodegenerative diseases like Alzheimer, Parkinson and Huntington disease are characterized by aggregation-prone proteins that form amyloid fibrils through a nucleation process. Despite the shared β-sheet structure, recent research has shown that structurally different polymorphs exist within fibrils of the same protein. These polymorphs are associated with varying levels of toxicity and different disease phenotypes. MOAG-4 and its human orthologs SERF1 and SERF2 have previously been shown to modify the nucleation and drive amyloid formation and protein toxicity in vitro and in C. elegans. To further explore these findings, we generated a Serf2 knockout (KO) mouse model and crossed it with the APPPS1 mouse model for Aβ amyloid pathology. Full-body KO of Serf2 resulted in a developmental delay and perinatal lethality due to insufficient lung maturation. Therefore, we proceeded with a brain-specific Serf2 KO, which was found to be viable. We examined the Aβ pathology at 1 and 3 months of age, which is before and after the start of amyloid deposition. We show that SERF2 deficiency does not affect the production and overall Aβ levels. Serf2 KO-APPPS1 mice displayed an increased intracellular Aβ accumulation at 1 month and a higher number of Aβ deposits compared to APPPS1 mice with similar Aβ levels. Moreover, conformation-specific dyes and electron microscopy revealed a difference in the structure and amyloid content of these Aβ deposits. Together, our results reveal that SERF2 causes a structural shift in Aβ aggregation in a mammalian brain. These findings indicate that a single endogenous factor may contribute to amyloid polymorphisms, allowing for new insights into this phenomenon’s contribution to disease manifestation.HighlightsLoss of SERF2 slows embryonic development and causes perinatal lethalitySERF2 affects proliferation in a cell-autonomous fashionBrain-specific Serf2 knockout does not affect viability or Aβ productionBrain deletion of Serf2 shifts the amyloid conformation of Aβ

scholarly journals Inducers of Senescence, Toxic Compounds, and Senolytics: The Multiple Faces of Nrf2-Activating Phytochemicals in Cancer Adjuvant Therapy

2018 ◽  
Vol 2018 ◽  
pp. 1-32 ◽  
Author(s):  
Marco Malavolta ◽  
Massimo Bracci ◽  
Lory Santarelli ◽  
Md Abu Sayeed ◽  
Elisa Pierpaoli ◽  
...  
Keyword(s):  
Adjuvant Therapy ◽  
Therapeutic Potential ◽  
Epigallocatechin Gallate ◽  
Natural Compounds ◽  
Related Factor ◽  
Phenethyl Isothiocyanate ◽  
Toxic Compounds ◽  
In Vivo Effects

The reactivation of senescence in cancer and the subsequent clearance of senescent cells are suggested as therapeutic intervention in the eradication of cancer. Several natural compounds that activate Nrf2 (nuclear factor erythroid-derived 2-related factor 2) pathway, which is involved in complex cytoprotective responses, have been paradoxically shown to induce cell death or senescence in cancer. Promoting the cytoprotective Nrf2 pathway may be desirable for chemoprevention, but it might be detrimental in later stages and advanced cancers. However, senolytic activity shown by some Nrf2-activating compounds could be used to target senescent cancer cells (particularly in aged immune-depressed organisms) that escape immunosurveillance. We herein describe in vitro and in vivo effects of fifteen Nrf2-interacting natural compounds (tocotrienols, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, silybin, phenethyl isothiocyanate, sulforaphane, triptolide, allicin, berberine, piperlongumine, fisetin, and phloretin) on cellular senescence and discuss their use in adjuvant cancer therapy. In light of available literature, it can be concluded that the meaning and the potential of adjuvant therapy with natural compounds in humans remain unclear, also taking into account the existence of few clinical trials mostly characterized by uncertain results. Further studies are needed to investigate the therapeutic potential of those compounds that display senolytic activity.

scholarly journals Comparative study of the stabilities of synthetic in vitro and natural ex vivo transthyretin amyloid fibrils

2020 ◽  
Vol 295 (33) ◽  
pp. 11379-11387 ◽  
Author(s):  
Sara Raimondi ◽  
P. Patrizia Mangione ◽  
Guglielmo Verona ◽  
Diana Canetti ◽  
Paola Nocerino ◽  
...  
Keyword(s):  
Thermodynamic Stability ◽  
Amyloid Fibrils ◽  
Current Knowledge ◽  
Ex Vivo ◽  
Biochemical Properties ◽  
Amyloid Formation ◽  
Free Energies

Systemic amyloidosis caused by extracellular deposition of insoluble fibrils derived from the pathological aggregation of circulating proteins, such as transthyretin, is a severe and usually fatal condition. Elucidation of the molecular pathogenic mechanism of the disease and discovery of effective therapies still represents a challenging medical issue. The in vitro preparation of amyloid fibrils that exhibit structural and biochemical properties closely similar to those of natural fibrils is central to improving our understanding of the biophysical basis of amyloid formation in vivo and may offer an important tool for drug discovery. Here, we compared the morphology and thermodynamic stability of natural transthyretin fibrils with those of fibrils generated in vitro either using the common acidification procedure or primed by limited selective cleavage by plasmin. The free energies for fibril formation were −12.36, −8.10, and −10.61 kcal mol−1, respectively. The fibrils generated via plasmin cleavage were more stable than those prepared at low pH and were thermodynamically and morphologically similar to natural fibrils extracted from human amyloidotic tissue. Determination of thermodynamic stability is an important tool that is complementary to other methods of structural comparison between ex vivo fibrils and fibrils generated in vitro. Our finding that fibrils created via an in vitro amyloidogenic pathway are structurally similar to ex vivo human amyloid fibrils does not necessarily establish that the fibrillogenic pathway is the same for both, but it narrows the current knowledge gap between in vitro models and in vivo pathophysiology.

Nanoencapsulated dietary polyphenols for cancer prevention and treatment: successes and challenges

Nanomedicine ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. 1147-1162 ◽  
Author(s):  
Shams Tabrez ◽  
Nasimudeen R Jabir ◽  
Vaqar Mustafa Adhami ◽  
Mohammad Imran Khan ◽  
Mohammed Moulay ◽  
...  
Keyword(s):  
Cancer Prevention ◽  
Therapeutic Potential ◽  
Epigallocatechin Gallate ◽  
Systemic Delivery ◽  
Dietary Polyphenols ◽  
Prevention And Treatment ◽  
In Vivo Animal Models ◽  
Successes And Challenges

Many dietary polyphenols have been investigated for their therapeutic potential either as single agents or in combinations. Despite the significant anticancer potential of these polyphenols in in vitro cell culture and in vivo animal models, their clinical applications have been limited because of challenges such as ineffective systemic delivery, stability and low bioavailability. Nanoencapsulation of these polyphenols could prolong circulation, improve localization, enhance efficacy and reduce the chances of multidrug resistance. This review summarized the use of various polyphenols especially epigallocatechin gallate, quercetin, curcumin and resveratrol as nanoformulations for cancer prevention and treatment. Despite some success, more research is warranted to design a nanoencapsulated combination of polyphenols, effective in in vitro, in vivo and human systems.

scholarly journals Designing transthyretin mutants affecting tetrameric structure: implications in amyloidogenicity

2000 ◽  
Vol 348 (1) ◽  
pp. 167-172 ◽  
Author(s):  
Clara REDONDO ◽  
Ana M. DAMAS ◽  
Maria João M. SARAIVA
Keyword(s):  
Molecular Mechanisms ◽  
Amyloid Fibrils ◽  
Hydrophobic Interactions ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Structural Determinants ◽  
Tetrameric Structure ◽  
Structural Subunit ◽  
The Stability

The molecular mechanisms that convert soluble transthyretin (TTR) tetramers into insoluble amyloid fibrils are still unknown; dissociation of the TTR tetramer is a pre-requisite for amyloid formation in vitro and involvement of monomers and/or dimers in fibril formation has been suggested by structural studies. We have designed four mutated proteins with the purpose of stabilizing [Ser117 → Cys (S117C) and Glu92 → Cys (E92C)] or destabilizing [Asp18 → Asn (D18N) and Leu110 → Ala (D110A)] the dimer/tetramer interactions in TTR, aiming at elucidating structural determinants in amyloidogenesis. The resistance of the mutated proteins to dissociation was analysed by HPLC studies of diluted TTR preparations. Both ‘stabilized’ mutants migrated as tetramers and, upon dilution, no other TTR species was observed, confirming the increased resistance to dissociation. For the ‘destabilized’ mutants, a mixture of tetrameric and monomeric forms co-existed at low dilution and the latter increased upon 10-fold dilution. Both of the destabilizing mutants formed amyloid in vitro when acidified. This result indicated that both the AB loop of TTR, destabilized in D18N, and the hydrophobic interactions affecting the dimer-dimer interfaces in L110A are implicated in the stability of the tetrameric structure. The stabilized mutants, which were dimeric in nature through disulphide bonding, were unable to polymerize into amyloid, even at pH 3.2. When the amyloid formation assay was repeated in the presence of 2-mercaptoethanol, upon disruption of the S-S bridges of these stable dimers, amyloid fibril formation was observed. This experimental evidence suggests that monomers, rather than dimers, are the repeating structural subunit comprising the amyloid fibrils.

scholarly journals Barriers to Small Molecule Drug Discovery for Systemic Amyloidosis

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3571
Author(s):  
Gareth J. Morgan
Keyword(s):  
Small Molecules ◽  
Light Chain ◽  
Amyloid Fibrils ◽  
Systemic Amyloidosis ◽  
Light Chains ◽  
Al Amyloidosis ◽  
Amyloid Formation ◽  
Amyloid Fibril Formation ◽  
Amyloid Light Chain

Inhibition of amyloid fibril formation could benefit patients with systemic amyloidosis. In this group of diseases, deposition of amyloid fibrils derived from normally soluble proteins leads to progressive tissue damage and organ failure. Amyloid formation is a complex process, where several individual steps could be targeted. Several small molecules have been proposed as inhibitors of amyloid formation. However, the exact mechanism of action for a molecule is often not known, which impedes medicinal chemistry efforts to develop more potent molecules. Furthermore, commonly used assays are prone to artifacts that must be controlled for. Here, potential mechanisms by which small molecules could inhibit aggregation of immunoglobulin light-chain dimers, the precursor proteins for amyloid light-chain (AL) amyloidosis, are studied in assays that recapitulate different aspects of amyloidogenesis in vitro. One molecule reduced unfolding-coupled proteolysis of light chains, but no molecules inhibited aggregation of light chains or disrupted pre-formed amyloid fibrils. This work demonstrates the challenges associated with drug development for amyloidosis, but also highlights the potential to combine therapies that target different aspects of amyloidosis.

scholarly journals Cholinesterase-inhibiting Potential and Anti-BACE1 Activities of Edible Leaves of Selected Thai Local Plants

2019 ◽  
Vol 16 (3) ◽  
pp. 155-163
Author(s):  
Uthaiwan SUTTISANSANEE ◽  
Kalyarat KRUAWAN
Keyword(s):  
Amyloid Fibrils ◽  
The Elderly ◽  
Amyloid Formation ◽  
Key Enzymes ◽  
Brain Functions ◽  
Polarity Index ◽  
Alzhiemer's Disease ◽  
Local Plants ◽  
Garcinia Cowa

Alzhiemer’s disease (AD) is common amongst the elderly and is associated with decline in brain functions in terms of memory and cognitive loss. The causes of the disease may occur through loss of presynaptic markers of cholinergic system and deposition of amyloid fibrils in the brain. Cholinesterases (ChEs) including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are the key enzymes controlling degradation of neurotransmitters, acetylcholines (AChs), in cholinergic hypothesis. Whereas overproduction of b-secretase (BACE1) can generate insoluble b-amyloid peptides. Thus, retardation on enzyme reactions can lead to potential AD prevention. The aim of this research was to investigate in vitro anti-AD activity through key enzymes inhibitions from Thai local plants with edible sour leaves, including Garcinia cowa Roxb., Spondias pinnata (Linn.f.) Kurz, Syzygium gratum (Wight) S.N. Mitra., Tamarind indica L. and Cratoxylum formosum (Jack) Dyer. Leaves were extracted in organic solvents with different polarity index values (ethanol and hexane). As results, all plants possessed different degrees of anti-ChEs activity, in which ethanolic extracts of Spondias pinnata and Tamarind indica exhibited significantly higher ChEs inhibitory activities than Syzygium gratum, Garcinia cowa and Cratoxylum formosum, respectively. Interestingly, most hexane extracts exhibited higher anti-AChE activities than ethanol extracts, while the contrary results were observed in anti-BChE activity. Besides, only Cratoxylum formosum, Garcinia cowa and Tamarind indica extracts possessed anti-BACE1 activity. The information received from this study would be great support of future drug development or nutraceutical agents against AD occurrence regarding its cholinergic and b-amyloid formation hypotheses.

scholarly journals Peptides derived from gp43, the most antigenic protein from Paracoccidioides brasiliensis, form amyloid fibrils in vitro: implications for vaccine development

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thyago R. Cardim-Pires ◽  
Ricardo Sant’Anna ◽  
Debora Foguel
Keyword(s):  
In Silico ◽  
Amyloid Fibrils ◽  
Vaccine Development ◽  
Paracoccidioides Brasiliensis ◽  
In Silico Analysis ◽  
Antigenic Protein ◽  
Amyloid Aggregates ◽  
Important Health ◽  
Potential Vaccine

AbstractFungal infection is an important health problem in Latin America, and in Brazil in particular. Paracoccidioides (mainly P. brasiliensis and P. lutzii) is responsible for paracoccidioidomycosis, a disease that affects mainly the lungs. The glycoprotein gp43 is involved in fungi adhesion to epithelial cells, which makes this protein an interesting target of study. A specific stretch of 15 amino acids that spans the region 181–195 (named P10) of gp43 is an important epitope of gp43 that is being envisioned as a vaccine candidate. Here we show that synthetic P10 forms typical amyloid aggregates in solution in very short times, a property that could hamper vaccine development. Seeds obtained by fragmentation of P10 fibrils were able to induce the aggregation of P4, but not P23, two other peptides derived from gp43. In silico analysis revealed several regions within the P10 sequence that can form amyloid with steric zipper architecture. Besides, in-silico proteolysis studies with gp43 revealed that aggregation-prone, P10-like peptides could be generated by several proteases, which suggests that P10 could be formed under physiological conditions. Considering our data in the context of a potential vaccine development, we redesigned the sequence of P10, maintaining the antigenic region (HTLAIR), but drastically reducing its aggregation propensity.

scholarly journals Peptides derived from gp43, the most antigenic protein from Paracoccidioides brasiliensis, form amyloid fibrils in vitro: implications for vaccine development

2021 ◽  
Author(s):  
Thyago R. Cardim-Pires ◽  
Ricardo Sant’Anna ◽  
Debora Foguel
Keyword(s):  
In Silico ◽  
Amyloid Fibrils ◽  
Vaccine Development ◽  
Paracoccidioides Brasiliensis ◽  
In Silico Analysis ◽  
Antigenic Protein ◽  
Amyloid Aggregates ◽  
Important Health ◽  
Potential Vaccine

Abstract Fungal infection is an important health problem in Latin America, and in Brazil in particular. Paracoccidioides (P. brasiliensis and P. lutzii) is responsible for paracoccidioidomycosis, a disease that affects mainly the lungs. The glycoprotein gp43 is involved in fungi adhesion to epithelial cells, which makes this protein an interesting target of study. A specific stretch of 15 amino acids that spans the region 181-195 (named P10) of gp43 is an important epitope of gp43 that is being envisioned as a vaccine candidate. Here we show that synthetic P10 forms typical amyloid aggregates in solution in very short times, a property that could hamper vaccine development. Seeds obtained by fragmentation of P10 fibrils were able to induce the aggregation of P4, but not P23, two other peptides derived from gp43. In silico analysis revealed several regions within the P10 sequence that are capable of forming amyloid with steric zipper architecture. Besides, in-silico proteolysis studies with gp43 revealed that aggregation-prone, P10-like peptides could be generated by several proteases, which suggests that P10 could be formed under physiological conditions. Considering our data in the context of a potential vaccine development, we redesigned the sequence of P10, maintaining the antigenic region (HTLAIR), but drastically reducing its aggregation propensity.

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