Oxidative and Nitrosative Modifications of Biliverdin Reductase-A in the Brain of Subjects with Alzheimer's Disease and Amnestic Mild Cognitive Impairment
Affiliations: [a] Department of Chemistry, Center of Membrane Sciences, and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA | [b] Institute of Pharmacology, Catholic University School of Medicine, Roma, Italy | [c] Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
Correspondence:
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Correspondence to: Prof. D. Allan Butterfield, Department of Chemistry, Center of Membrane Sciences, and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40506-0055, USA. Tel.: 859-257-3184, Fax: 859-259-5876; E-mail: dabcns@uky.edu.
Note: [#] Both the authors contributed equally.
Abstract: Biliverdin reductase-A (BVR-A) is a pleiotropic enzyme and plays pivotal role in the antioxidant defense against free radicals as well as in cell homeostasis. Together with heme oxygenase, BVR-A forms a powerful system involved in the cell stress response during neurodegenerative disorders including Alzheimer's disease (AD), whereas due to the serine/threonine/tyrosine kinase activity the enzyme regulates glucose metabolism and cell proliferation. In this paper, we report results that demonstrate BVR-A undergoes post-translational oxidative and nitrosative modifications in the hippocampus, but not cerebellum, of subjects with AD and amnestic mild cognitive impairment (MCI). A significant increase of nitrated BVR-A was demonstrated only in AD and MCI hippocampi, whereas no significant modifications were found in cerebellar tissue. In addition, a significant reduction in protein carbonyl-derivatives of BVR-A was found in both AD and MCI hippocampi (15% and 18%, respectively). Biliverdin reductase-bound 4-hydroxynonenals were not modified in hippocampi and cerebella from AD and MCI subjects. These results supported the hypothesis of a prevalence of nitrosative stress-induced modifications on BVR-A structure, and this evidence was confirmed by a significant upregulation of inducible nitric oxide synthase in hippocampal tissue of subjects with AD and MCI that was not present in cerebellum. In conclusion, nitrosative stress-induced modifications on hippocampal BVR-A are an early event in the pathogenesis of AD since they appear also in MCI subjects and could contribute to the antioxidant and metabolic derangement characteristic of these neurodegenerative disorders.
