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Arar S, Haque MA, Bhatt N, Zhao Y, Kayed R. Effect of Natural Osmolytes on Recombinant Tau Monomer: Propensity of Oligomerization and Aggregation. ACS Chem Neurosci 2024; 15:1366-1377. [PMID: 38503425 PMCID: PMC10995947 DOI: 10.1021/acschemneuro.3c00614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 03/21/2024] Open
Abstract
The pathological misfolding and aggregation of the microtubule associated protein tau (MAPT), a full length Tau2N4R with 441aa, is considered the principal disease relevant constituent in tauopathies including Alzheimer's disease (AD) with an imbalanced ratio in 3R/4R isoforms. The exact cellular fluid composition, properties, and changes that coincide with tau misfolding, seed formation, and propagation events remain obscure. The proteostasis network, along with the associated osmolytes, is responsible for maintaining the presence of tau in its native structure or dealing with misfolding. In this study, for the first time, the roles of natural brain osmolytes are being investigated for their potential effects on regulating the conformational stability of the tau monomer (tauM) and its propensity to aggregate or disaggregate. Herein, the effects of physiological osmolytes myo-inositol, taurine, trimethyl amine oxide (TMAO), betaine, sorbitol, glycerophosphocholine (GPC), and citrulline on tau's aggregation state were investigated. The overall results indicate the ability of sorbitol and GPC to maintain the monomeric form and prevent aggregation of tau, whereas myo-inositol, taurine, TMAO, betaine, and citrulline promote tau aggregation to different degrees, as revealed by protein morphology in atomic force microscopy images. Biochemical and biophysical methods also revealed that tau proteins adopt different conformations under the influence of these osmolytes. TauM in the presence of all osmolytes expressed no toxicity when tested by a lactate dehydrogenase assay. Investigating the conformational stability of tau in the presence of osmolytes may provide a better understanding of the complex nature of tau aggregation in AD and the protective and/or chaotropic nature of osmolytes.
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Affiliation(s)
- Sharif Arar
- Mitchell
Center for Neurodegenerative Diseases, University
of Texas Medical Branch, Galveston, Texas 77555, United States
- Departments
of Neurology, Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Department
of Chemistry, School of Science, The University
of Jordan, Amman 11942, Jordan
| | - Md Anzarul Haque
- Mitchell
Center for Neurodegenerative Diseases, University
of Texas Medical Branch, Galveston, Texas 77555, United States
- Departments
of Neurology, Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Nemil Bhatt
- Mitchell
Center for Neurodegenerative Diseases, University
of Texas Medical Branch, Galveston, Texas 77555, United States
- Departments
of Neurology, Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Yingxin Zhao
- Department
of Internal Medicine, University of Texas
Medical Branch, Galveston, Texas 77555, United States
- Institute
for Translational Sciences, University of
Texas Medical Branch, Galveston, Texas 77555, United States
| | - Rakez Kayed
- Mitchell
Center for Neurodegenerative Diseases, University
of Texas Medical Branch, Galveston, Texas 77555, United States
- Departments
of Neurology, Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, United States
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