Electrochemical detection of anti-tau antibodies binding to tau protein and inhibition of GSK-3β-catalyzed phosphorylation

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• 作者：Jose O. Esteves-Villanueva ; Sanela Martic-Milne ; ^{martic@oakland.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Tau ; Phosphorylation ; Antibodies ; Kinases ; Impedance
• 刊名：Analytical Biochemistry
• 出版年：2016
• 出版时间：1 March 2016
• 年：2016
• 卷：496
• 期：Complete
• 页码：55-62
• 全文大小：1108 K

文摘

Tau protein hyperphosphorylation triggers tau aggregation and its toxicity, leading to neuronal death and cell-to-cell toxicity. Hence, inhibition of protein kinases is a viable tool toward reduction of tau toxicity. By targeting various epitopes of Tau441 protein immobilized on Au surface, the protein kinase inhibition by anti-tau antibodies was measured by surface electrochemistry. The electrochemical impedance spectroscopy was used to measure the charge transfer resistance (R_ct) of nonphosphorylated tau–Au film (nTau–Au) and compared with the phosphorylated tau–Au film (pTau–Au). The pTau–Au films were characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF–SIMS), which indicated high phosphorus content. The R_ct factor was used as the measure of inhibition efficacies by anti-tau antibodies (D8, A10, P262, and Tau46) in addition to antibody formulation intravenous immunoglobulin (IVIG). The R_ct factor for pTau–Au in the absence of antibodies was 0.25 ± 0.08, indicating a dramatic decrease in R_ct on phosphorylation. The R_ct factors for Tau46 and A10 were 0.57 ± 0.22 and 0.65 ± 0.26, respectively, indicating phosphorylation inhibition. All antibodies exhibited similar binding to nTau–Au. The proposed electrochemical assay may be used for detection of other posttranslational modifications.