Browsing by Subject "Protein aggregation"

Now showing 1 - 4 of 4
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    Crystal structure of a conformational antibody that binds tau oligomers and inhibits pathological seeding by extracts from donors with Alzheimer's disease
    (American Society for Biochemistry and Molecular Biology, 2020-07-31) Abskharon, Romany; Seidler, Paul M.; Sawaya, Michael R.; Cascio, Duilio; Yang, Tianxiao P.; Philipp, Stephan; Williams, Christopher Kazu; Newell, Kathy L.; Ghetti, Bernardino; DeTure, Michael A.; Dickson, Dennis W.; Vinters, Harry V.; Felgner, Philip L.; Nakajima, Rie; Glabe, Charles G.; Eisenberg, David S.; Pathology and Laboratory Medicine, School of Medicine
    Soluble oligomers of aggregated tau accompany the accumulation of insoluble amyloid fibrils, a histological hallmark of Alzheimer disease (AD) and two dozen related neurodegenerative diseases. Both oligomers and fibrils seed the spread of Tau pathology, and by virtue of their low molecular weight and relative solubility, oligomers may be particularly pernicious seeds. Here, we report the formation of in vitro tau oligomers formed by an ionic liquid (IL15). Using IL15-induced recombinant tau oligomers and a dot blot assay, we discovered a mAb (M204) that binds oligomeric tau, but not tau monomers or fibrils. M204 and an engineered single-chain variable fragment (scFv) inhibited seeding by IL15-induced tau oligomers and pathological extracts from donors with AD and chronic traumatic encephalopathy. This finding suggests that M204-scFv targets pathological structures that are formed by tau in neurodegenerative diseases. We found that M204-scFv itself partitions into oligomeric forms that inhibit seeding differently, and crystal structures of the M204-scFv monomer, dimer, and trimer revealed conformational differences that explain differences among these forms in binding and inhibition. The efficiency of M204-scFv antibodies to inhibit the seeding by brain tissue extracts from different donors with tauopathies varied among individuals, indicating the possible existence of distinct amyloid polymorphs. We propose that by binding to oligomers, which are hypothesized to be the earliest seeding-competent species, M204-scFv may have potential as an early-stage diagnostic for AD and tauopathies, and also could guide the development of promising therapeutic antibodies.
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    A pair of peptides inhibits seeding of the hormone transporter transthyretin into amyloid fibrils
    (American Society for Biochemistry and Molecular Biology, 2019-04-12) Saelices, Lorena; Nguyen, Binh A.; Chung, Kevin; Wang, Yifei; Ortega, Alfredo; Lee, Ji H.; Coelho, Teresa; Bijzet, Johan; Benson, Merrill D.; Eisenberg, David S.; Pathology and Laboratory Medicine, School of Medicine
    The tetrameric protein transthyretin is a transporter of retinol and thyroxine in blood, cerebrospinal fluid, and the eye, and is secreted by the liver, choroid plexus, and retinal epithelium, respectively. Systemic amyloid deposition of aggregated transthyretin causes hereditary and sporadic amyloidoses. A common treatment of patients with hereditary transthyretin amyloidosis is liver transplantation. However, this procedure, which replaces the patient's variant transthyretin with the WT protein, can fail to stop subsequent cardiac deposition, ultimately requiring heart transplantation. We recently showed that preformed amyloid fibrils present in the heart at the time of surgery can template or seed further amyloid aggregation of native transthyretin. Here we assess possible interventions to halt this seeding, using biochemical and EM assays. We found that chemical or mutational stabilization of the transthyretin tetramer does not hinder amyloid seeding. In contrast, binding of the peptide inhibitor TabFH2 to ex vivo fibrils efficiently inhibits amyloid seeding by impeding self-association of the amyloid-driving strands F and H in a tissue-independent manner. Our findings point to inhibition of amyloid seeding by peptide inhibitors as a potential therapeutic approach.
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    Structural polymorphism of amyloid fibrils in ATTR amyloidosis revealed by cryo-electron microscopy
    (Springer Nature, 2024-01-17) Nguyen, Binh An; Singh, Virender; Afrin, Shumaila; Yakubovska, Anna; Wang, Lanie; Ahmed, Yasmin; Pedretti, Rose; Fernandez-Ramirez, Maria del Carmen; Singh, Preeti; Pękała, Maja; Cabrera Hernandez, Luis O.; Kumar, Siddharth; Lemoff, Andrew; Gonzalez-Prieto, Roman; Sawaya, Michael R.; Eisenberg, David S.; Benson, Merrill Douglas; Saelices, Lorena; Pathology and Laboratory Medicine, School of Medicine
    ATTR amyloidosis is caused by the deposition of transthyretin in the form of amyloid fibrils in virtually every organ of the body, including the heart. This systemic deposition leads to a phenotypic variability that has not been molecularly explained yet. In brain amyloid conditions, previous studies suggest an association between clinical phenotype and the molecular structures of their amyloid fibrils. Here we investigate whether there is such an association in ATTRv amyloidosis patients carrying the mutation I84S. Using cryo-electron microscopy, we determined the structures of cardiac fibrils extracted from three ATTR amyloidosis patients carrying the ATTRv-I84S mutation, associated with a consistent clinical phenotype. We found that in each ATTRv-I84S patient, the cardiac fibrils exhibited different local conformations, and these variations can co-exist within the same fibril. Our finding suggests that one amyloid disease may associate with multiple fibril structures in systemic amyloidoses, calling for further studies.
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    β-Bracelets: Macrocyclic cross-β epitope mimics based on a tau conformational strain
    (American Chemical Society, 2023) Rajewski, Benjamin H.; Makwana, Kamlesh M.; Angera, Isaac J.; Geremia, Danielle K.; Zepeda, Anna R.; Hallinan, Grace I.; Vidal, Ruben; Ghetti, Bernardino; Serrano, Arnaldo L.; Del Valle, Juan R.; Pathology and Laboratory Medicine, School of Medicine
    The aggregation of misfolded tau into neurotoxic fibrils is linked to the progression of Alzheimer’s disease (AD) and related tauopathies. Disease-associated conformations of filamentous tau are characterized by hydrophobic interactions between sidechains on unique and distant β-strand modules within each protomer. Here, we report the design and diversity-oriented synthesis of β-arch peptide macrocycles comprised of the aggregation-prone PHF6 hexapeptide of tau and the cross-β module specific to the AD tau fold. Termed “β-bracelets”, these proteomimetics assemble in a sequence- and macrocycle-dependent fashion, resulting in amyloid-like fibrils that feature in-register parallel β-sheet structure. Backbone N-amination of a selected β-bracelet affords soluble inhibitors of tau aggregation. We further demonstrate that the N-aminated macrocycles block the prion-like cellular seeding activity of recombinant tau as well as mature fibrils from AD patient extracts. These studies establish β-bracelets as a new class of cross-β epitope mimic and demonstrate their utility in the rational design of molecules targeting amyloid propagation and seeding.