Pharmacological inhibition of GSK3 attenuates DNA damage-induced apoptosis via reduction of p53 mitochondrial translocation and Bax oligomerization in neuroblastoma SH-SY5Y CELLS

Patchara Ngok-Ngam,Jutamaad Satayavivad,Apinya Thiantanawat,Piyajit Watcharasit

doi:10.2478/s11658-012-0039-y

Patchara Ngok-Ngam, Jutamaad Satayavivad + Show 2 more

Open Access

https://doi.org/10.2478/s11658-012-0039-y

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Abstract

Glycogen synthase kinase-3 (GSK3) and p53 play crucial roles in the mitochondrial apoptotic pathway and are known to interact in the nucleus. However, it is not known if GSK3 has a regulatory role in the mitochondrial translocation of p53 that participates in apoptotic signaling following DNA damage. In this study, we demonstrated that lithium and SB216763, which are pharmacological inhibitors of GSK3, attenuated p53 accumulation and caspase-3 activation, as shown by PARP cleavage induced by the DNA-damaging agents doxorubicin, etoposide and camptothecin. Furthermore, each of these agents induced translocation of p53 to the mitochondria and activated the mitochondrial pathway of apoptosis, as evidenced by the release of cytochrome C from the mitochondria. Both mitochondrial translocation of p53 and mitochondrial release of cytochrome C were attenuated by inhibition of GSK3, indicating that GSK3 promotes the DNA damage-induced mitochondrial translocation of p53 and the mitochondrial apoptosis pathway. Interestingly, the regulation of p53 mitochondrial translocation by GSK3 was only evident with wild-type p53, not with mutated p53. GSK3 inhibition also reduced the phosphorylation of wild-type p53 at serine 33, which is induced by doxorubicin, etoposide and camptothecin in the mitochondria. Moreover, inhibition of GSK3 reduced etoposide-induced association of p53 with Bcl2 and Bax oligomerization. These findings show that GSK3 promotes the mitochondrial translocation of p53, enabling its interaction with Bcl2 to allow Bax oligomerization and the subsequent release of cytochrome C. This leads to caspase activation in the mitochondrial pathway of intrinsic apoptotic signaling.

Highlights

Glycogen synthase kinase-3 (GSK3) is a serine/threonine kinase that plays critical roles in the regulation of multiple signaling pathways, including the wnt/wingless, insulin and apoptotic signaling pathways
Considering the recently identified direct action of p53 in the mitochondria in inducing apoptosis [31, 32] and the direct interaction between p53 and GSK3 involved in activating the mitochondrial pathway of apoptosis [4, 11], we tested whether GSK3 plays a role in regulating mitochondrial p53
Our findings show that after DNA damage, GSK3 promotes p53 translocation to the mitochondria, Bax oligomerization associated with the mitochondria, and mitochondriamediated apoptotic signaling

Summary

Introduction

GSK3 is a serine/threonine kinase that plays critical roles in the regulation of multiple signaling pathways, including the wnt/wingless, insulin and apoptotic signaling pathways. It is involved in the regulation of a variety of fundamental processes, including some related to cell structure, metabolism and survival [1, 2]. GSK3 has been shown to promote apoptotic cell death induced by several types of damage that involve the intrinsic mitochondrial pathway. These include DNA damage [4], endoplasmic reticulum stress [5,6,7] and mitochondrial toxins [8, 9]. GSK3 has been shown to promote the intrinsic pathway of apoptotic signaling in which mitochondria have a critical role [1, 3]

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