HNK-1 Carrier Glycoproteins Are Decreased in the Alzheimer’s Disease Brain

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• 作者：María-Salud García-Ayllón ; Arancha Botella-López…
• 关键词：Alzheimer’s disease ; β ; amyloid ; Glycoprotein ; Glycoform ; HNK ; 1 ; Cerebrospinal fluid
• 刊名：Molecular Neurobiology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：54
• 期：1
• 页码：188-199
• 全文大小：
• 刊物主题：Neurosciences; Neurobiology; Cell Biology; Neurology;
• 出版者：Springer US
• ISSN：1559-1182
• 卷排序：54

文摘

The human natural killer-1 (HNK-1), 3-sulfonated glucuronic acid, is a glycoepitope marker of cell adhesion that participates in cell-cell and cell-extracellular matrix interactions and in neurite growth. Very little is known about the regulation of the HNK-1 glycan in neurodegenerative disease, particularly in Alzheimer’s disease (AD). In this study, we investigate changes in the levels of HNK-1 carrier glycoproteins in AD. We demonstrate an overall decrease in HNK-1 immunoreactivity in glycoproteins extracted from the frontal cortex of AD subjects, compared with levels from non-demented controls (NDC). Immunoblotting of ventricular post-mortem and lumbar ante-mortem cerebrospinal fluid with HNK-1 antibodies indicate similar levels of carrier glycoproteins in AD and NDC samples. Decrease in HNK-1 carrier glycoproteins were not paralleled by changes in messenger RNA (mRNA) levels of the enzymes involved in the synthesis of the glycoepitope, β-1,4-galactosyltransferase (β4GalT), glucuronyltransferases GlcAT-P and GlcAT-S, or sulfotransferase HNK-1ST. Over-expression of amyloid precursor protein in Tg2576 transgenic mice and in vitro treatment of SH-SY5Y neuroblastoma cells with the amyloidogenic Aβ42 peptide resulted in a decrease in HNK-1 immunoreactivity levels in brain and cellular extracts, whereas the levels of soluble HNK-1 glycoproteins detected in culture media were not affected by Aβ treatment. HNK-1 levels remain unaffected in the brain extracts of Tg-VLW mice, a model of mutant hyperphosphorylated tau, and in SH-SY5Y cells over-expressing hyperphosphorylated wild-type tau. These results provide evidence that cellular levels of HNK-1 carrier glycoforms are decreased in the brain of AD subjects, probably influenced by the β-amyloid protein.