Alzheimer's disease (AD) is a progressive amnestic dementia typified by the pathological self-association of the microtubule-associated tau protein into neurofibrillary tangles (NFTs). Important to NFT formation are numerous modifications of tau, including phosphorylation, truncation, and conformational changes. In addition, AD-associated inflammation promotes the formation of peroxynitrite (ONOO-), a potent nitrating agent that can modify protein tyrosine (Tyr) residues. Nitration occurs with biological specificity and can profoundly influence protein folding and function. Increased levels of nitrated proteins have been reported in AD brain and cerebrospinal fluid, and several groups have localized 3-nitrotyrosine (3-NT) to NFTs in AD brain. Immunological probes raised against nitrated alpha-synuclein that also recognize nitrated tau selectively stain NFTs and fibrillar tau inclusions in AD and other tauopathies. These data suggest that nitration of select proteins may facilitate their misfolding and deposition in neurodegenerative disease. The goal of this dissertation is to delineate the relationship between tau nitration and NFT formation in AD. We hypothesize that site-specific nitration induces a change in tau conformation that reduces its affinity for microtubules and promotes its pathological self-assembly. Tau nitration may represent a toxic gain of function whereby the protein becomes structurally permissive to aggregation and/or a loss of function due to deficient microtubule binding and stabilization. The present work examines the effects of nitrative modification on tau structure and function. In chapter one, we highlight salient examples of site-specific nitration in neurodegenerative diseases. In chapter two, we characterize the effects of ONOO--mediated nitration on tau assembly in vitro. In chapter three, we investigate the effects of nitration at individual Tyr residues on the ability of tau to self-assemble and assume specific conformational states. In chapter four, the relationship between nitration and tau-microtubule interactions is explored. In chapter five, we validate the significance of our in vitro findings by staining tauopathy-affected human brain sections with a novel, nitro-tau specific monoclonal antibody. Finally, in chapter six, we summarize the current body of literature on tau nitration and propose general mechanisms for how protein nitration may induce toxicity in neurodegenerative diseases

Last modified

• 07/26/2018

Creator

• Matthew Ryan Reynolds

DOI

• https://doi.org/10.21985/N2KM68

Subject

• Neuroscience Institute Graduate Program

Keyword

• Monoclonal Antibody
• 3, 3'-Dityrosine
• Nitration
• Peroxynitrite
• Alzheimer's
• Tau

Date created

• 2007-05-14

Resource type

• Dissertation

Rights statement

• In Copyright