Cleavage of GSK‐3β by calpain counteracts the inhibitory effect of Ser9 phosphorylation on GSK‐3β activity induced by H2O2

Authors:
Open Access
Publisher website
Google Scholar
Abstract
Glycogen synthase kinase‐3 beta (GSK‐3β) dysfunction may play an essential role in the pathogenesis of psychiatric, metabolic, neurodegenerative diseases, in which oxidative stress exists concurrently. Some studies have shown that GSK‐3β activity is up‐regulated under oxidative stress. This study evaluated how oxidative stress regulates GSK‐3β activity in human embryonic kidney 293 (HEK293)/Tau cells treated with hydrogen peroxide (H2O2). Here, we show that H2O2 induced an obvious increase of GSK‐3β activity. Surprisingly, H2O2 dramatically increased phosphorylation of GSK‐3β at Ser9, an inactive form of GSK‐3β,while there were no changes of phosphorylation of GSK‐3β at Tyr216. Moreover, H2O2 led to a transient [Ca2+]i elevation, and simultaneously increased the truncation of GSK‐3β into two fragments of 40 kDa and 30 kDa, whereas inhibition of calpain decreased the truncation and recovered the activity of GSK‐3β. Furthermore, tau was hyperphosphorylated at Ser396, Ser404, and Thr231, three most common GSK‐3β targeted sites after 100 μM H2O2 administration in HEK293/Tau cells, whereas inhibition of calpain blocked the tau phosphorylation. In addition, we found that there were no obvious changes of Cyclin‐dependent kinase 5 (CDK5) expression (responsible for tau phosphorylation) and of p35 cleavage, the regulatory subunit of CDK5 in H2O2‐treated HEK293/Tau cells. In conclusion, Ca2+‐dependent calpain activation leads to GSK‐3β truncation, which counteracts the inhibitory effect of Ser9 phosphorylation, up‐regulates GSK‐3β activity, and phosphorylates tau in H2O2‐treated HEK293/Tau cells.
Funding Information
  • National Natural Science Foundation of China (81271405, 31071226)

This publication has 43 references indexed in Scilit: