Reduced neuronal expression of synaptic transmission modulator HNK‐1/neural cell adhesion molecule as a potential consequence of amyloid β‐mediated oxidative stress: a proteomic approach

• Published in: Journal of neurochemistry 2005-02, Vol.92 (4), p.705-717
• Main Authors: Thomas, Stefani N., Soreghan, Brian A., Nistor, Mihaela, Sarsoza, Floyd, Head, Elizabeth, Yang, Austin J.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amyloid beta-Peptides - genetics; Amyloid beta-Peptides - pharmacology; amyloid‐β; Animals; Biological and medical sciences; Carbohydrate Conformation; Carbohydrate Sequence; CD57 Antigens - biosynthesis; CD57 Antigens - metabolism; Cells, Cultured; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Down-Regulation; Female; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; Glucuronosyltransferase - isolation & purification; Glucuronosyltransferase - metabolism; glucuronyltransferase; Human Natural Killer (HNK‐1); Isolated neuron and nerve. Neuroglia; liquid chromatography tandem mass spectrometry; Medical sciences; Mice; Mice, Transgenic; Molecular Sequence Data; Neural Cell Adhesion Molecules - antagonists & inhibitors; Neural Cell Adhesion Molecules - biosynthesis; Neurology; Neurons - drug effects; Neurons - enzymology; oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; Peptide Fragments - genetics; Peptide Fragments - pharmacology; Pregnancy; Proteomics - methods; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2004.02892.x

Oxidative stress imparted by reactive oxygen species (ROS) is implicated in the pathogenesis of Alzheimer's disease (AD). Given that amyloid β (Aβ) itself generates ROS that can directly damage proteins, elucidating the functional consequences of protein oxidation can enhance our understanding of the process of Aβ‐mediated neurodegeneration. In this study, we employed a biocytin hydrazide/streptavidin affinity purification methodology followed by two‐dimensional liquid chromatography tandem mass spectrometry coupled with SEQUEST bioinformatics technology, to identify the targets of Aβ‐induced oxidative stress in cultured primary cortical mouse neurons. The Golgi‐resident enzyme glucuronyltransferase (GlcAT‐P) was a carbonylated target that we investigated further owing to its involvement in the biosynthesis of HNK‐1, a carbohydrate epitope expressed on cell adhesion molecules and implicated in modulating the effectiveness of synaptic transmission in the brain. We found that increasing amounts of Aβ, added exogenously to the culture media of primary cortical neurons, significantly decreased HNK‐1 expression. Moreover, in vivo, HNK‐1 immunoreactivity was decreased in brain tissue of a transgenic mouse model of AD. We conclude that a potential consequence of Aβ‐mediated oxidation of GlcAT‐P is impairment of its enzymatic function, thereby disrupting HNK‐1 biosynthesis and possibly adversely affecting synaptic plasticity. Considering that AD is partly characterized by progressive memory impairment and disordered cognitive function, the data from our in vitro studies can be reconciled with results from in vivo studies that have demonstrated that HNK‐1 modulates synaptic plasticity and is critically involved in memory consolidation.