Related Experiment Video
Updated: May 3, 2026
Assay for Phosphorylation and Microtubule Binding Along with Localization of Tau Protein in Colorectal Cancer Cells
Published on: October 10, 2017
Cornel Iridoid Glycoside Attenuates Tau Hyperphosphorylation by Inhibition of PP2A Demethylation
Cui-Cui Yang1, Xue-Xian Kuai2, Ya-Li Li1
1Department of Pharmacology, Xuanwu Hospital of Capital Medical University, Key Laboratory for Neurodegenerative Diseases of Ministry of Education, 45 Changchun Street, Beijing 100053, China.
Abstract:
Aim. The aim of the present study was to investigate the effect of cornel iridoid glycoside (CIG) on tau hyperphosphorylation induced by wortmannin (WT) and GF-109203X (GFX) and the underlying mechanisms. Methods. Human neuroblastoma SK-N-SH cells were preincubated with CIG (50, 100, and 200 µg/ml, resp.) for 24 h and then exposed to 10 µM WT and 10 µM GFX for 3 h after washing out CIG. Immunohistochemistry was used to observe the microtubular cytoskeleton of the cultured cells. Western blotting was used to measure the phosphorylation level of tau protein, glycogen synthase kinase 3 β (GSK-3 β ), and protein phosphatase 2A (PP2A). The activity of PP2A was detected by a biochemical assay. Results. Preincubation of CIG significantly attenuated the WT/GFX-induced tau hyperphosphorylation at the sites of Thr205, Thr212, Ser214, Thr217, Ser396, and PHF-1 and improved the damage of morphology and microtubular cytoskeleton of the cells. CIG did not prevent the decrease in p-AKT-ser473 and p-GSK-3 β -ser9 induced by WT/GFX. However, CIG significantly elevated the activity of PP2A by reducing the demethylation of PP2A catalytic subunit (PP2Ac) at Leu309 and the ratio of PME-1/LCMT in the WT/GFX-treated cells. The results suggest that CIG may be beneficial to the treatment of AD.
Insights
Cornel iridoid glycoside (CIG) reduces tau hyperphosphorylation, a key factor in Alzheimer's disease (AD). CIG enhances protein phosphatase 2A (PP2A) activity, suggesting potential therapeutic benefits for AD.
Area of Science:
- Neuroscience
- Pharmacology
- Biochemistry
Background:
- Tau hyperphosphorylation is a hallmark of Alzheimer's disease (AD).
- Wortmannin (WT) and GF-109203X (GFX) are known inducers of tau hyperphosphorylation.
- Identifying compounds that can mitigate tau pathology is crucial for AD treatment.
Purpose of the Study:
- To investigate the effect of cornel iridoid glycoside (CIG) on WT/GFX-induced tau hyperphosphorylation.
- To elucidate the underlying mechanisms of CIG's action on tau pathology.
Main Methods:
- Human neuroblastoma SK-N-SH cells were used.
- Cells were treated with CIG followed by WT and GFX.
- Immunohistochemistry, Western blotting, and biochemical assays were employed to assess tau phosphorylation, cytoskeletal integrity, and enzyme activity.
Main Results:
- CIG significantly attenuated WT/GFX-induced tau hyperphosphorylation at multiple sites and improved cellular morphology.
- CIG did not affect the phosphorylation status of AKT and GSK-3β.
- CIG elevated protein phosphatase 2A (PP2A) activity by reducing PP2A demethylation.
Conclusions:
- CIG demonstrates neuroprotective effects against tau hyperphosphorylation.
- The mechanism involves the upregulation of PP2A activity.
- CIG shows potential as a therapeutic agent for Alzheimer's disease.
