Dataset Information

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls.

ABSTRACT: Neurodegenerative diseases are distinguished by characteristic protein aggregates initiated by disease-specific 'seed' proteins; however, roles of other co-aggregated proteins remain largely unexplored. Compact hippocampal aggregates were purified from Alzheimer's and control-subject pools using magnetic-bead immunoaffinity pulldowns. Their components were fractionated by electrophoretic mobility and analyzed by high-resolution proteomics. Although total detergent-insoluble aggregates from Alzheimer's and controls had similar protein content, within the fractions isolated by tau or A?1-42 pulldown, the protein constituents of Alzheimer-derived aggregates were more abundant, diverse, and post-translationally modified than those from controls. Tau- and A?-containing aggregates were distinguished by multiple components, and yet shared >90% of their protein constituents, implying similar accretion mechanisms. Alzheimer-specific protein enrichment in tau-containing aggregates was corroborated for individuals by three analyses. Five proteins inferred to co-aggregate with tau were confirmed by precise in situ methods, including proximity ligation amplification that requires co-localization within 40 nm. Nematode orthologs of 21 proteins, which showed Alzheimer-specific enrichment in tau-containing aggregates, were assessed for aggregation-promoting roles in C. elegans by RNA-interference 'knockdown'. Fifteen knockdowns (71%) rescued paralysis of worms expressing muscle A?, and 12 (57%) rescued chemotaxis disrupted by neuronal A? expression. Proteins identified in compact human aggregates, bound by antibody to total tau, were thus shown to play causal roles in aggregation based on nematode models triggered by A?1-42 . These observations imply shared mechanisms driving both types of aggregation, and/or aggregate-mediated cross-talk between tau and A?. Knowledge of protein components that promote protein accrual in diverse aggregate types implicates common mechanisms and identifies novel targets for drug intervention.

SUBMITTER: Ayyadevara S

PROVIDER: S-EPMC5013017 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls.

Ayyadevara Srinivas S Balasubramaniam Meenakshisundaram M Parcon Paul A PA Barger Steven W SW Griffin W Sue T WS Alla Ramani R Tackett Alan J AJ Mackintosh Samuel G SG Petricoin Emanuel E Zhou Weidong W Shmookler Reis Robert J RJ

Aging cell 20160723 5

Neurodegenerative diseases are distinguished by characteristic protein aggregates initiated by disease-specific 'seed' proteins; however, roles of other co-aggregated proteins remain largely unexplored. Compact hippocampal aggregates were purified from Alzheimer's and control-subject pools using magnetic-bead immunoaffinity pulldowns. Their components were fractionated by electrophoretic mobility and analyzed by high-resolution proteomics. Although total detergent-insoluble aggregates from Alzhe ...[more]

PMID: 27448508

Similar Datasets

Project description:Misfolding- and aggregation-prone proteins underlying Parkinson's, Huntington's and Machado-Joseph diseases, namely alpha-synuclein, huntingtin, and ataxin-3 respectively, adopt numerous intracellular conformations during pathogenesis, including globular intermediates and insoluble amyloid-like fibrils. Such conformational diversity has complicated research into amyloid-associated intracellular dysfunction and neurodegeneration. To this end, recombinant single-chain Fv antibodies (scFvs) are compelling molecular tools that can be selected against specific protein conformations, and expressed inside cells as intrabodies, for investigative and therapeutic purposes.Using atomic force microscopy (AFM) and live-cell fluorescence microscopy, we report that a human scFv selected against the fibrillar form of alpha-synuclein targets isomorphic conformations of misfolded polyglutamine proteins. When expressed in the cytoplasm of striatal cells, this conformation-specific intrabody co-localizes with intracellular aggregates of misfolded ataxin-3 and a pathological fragment of huntingtin, and enhances the aggregation propensity of both disease-linked polyglutamine proteins. Using this intrabody as a tool for modulating the kinetics of amyloidogenesis, we show that escalating aggregate formation of a pathologic huntingtin fragment is not cytoprotective in striatal cells, but rather heightens oxidative stress and cell death as detected by flow cytometry. Instead, cellular protection is achieved by suppressing aggregation using a previously described intrabody that binds to the amyloidogenic N-terminus of huntingtin. Analogous cytotoxic results are observed following conformational targeting of normal or polyglutamine-expanded human ataxin-3, which partially aggregate through non-polyglutamine domains.These findings validate that the rate of aggregation modulates polyglutamine-mediated intracellular dysfunction, and caution that molecules designed to specifically hasten aggregation may be detrimental as therapies for polyglutamine disorders. Moreover, our findings introduce a novel antibody-based tool that, as a consequence of its general specificity for fibrillar conformations and its ability to function intracellularly, offers broad research potential for a variety of human amyloid diseases.

Dataset Information

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls.

Publications

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets