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

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.

Neuroprotective Functions for the Histone Deacetylase SIRT6

“…Tau is phosphorylated by several kinases including CHK2 and GSK3 (Martin et al, 2013), known to be activated by DNA damage (Iijima-Ando et al, 2010; Ngok-Ngam et al, 2013; Watcharasit et al, 2002). While no changes were observed in CHK2 activation, we observed decreased levels of phospho-GSK3, a marker for increased GSK3 activity (Fig.…”

Specific glycogen synthase kinase-3 inhibition reduces neuroendocrine markers and suppresses neuroblastoma cell growth

“…17,18 Furthermore, GSK-3 has been shown to promote DNA damage-induced apoptosis in neuroblastoma cells expressing wild-type p53. 19 However it is not known which isoform of GSK-3 regulates cancer cell proliferation. To date there are conflicting and contradictory reports of the role of GSK-3 isoforms in modulation of cell growth.…”

Neurotrophic effects of lithium stimulate the reduction of ischemic and neurodegenerative brain damage

“…Ингибиро-вание литием GSK-3β тормозит два основных процесса в патогенезе БА: литий уменьшает гиперфосфорилирова-ние тау-белка [46,47] и снижает избыточный синтез β-амилоида [48,49]. Кроме того, литий стимулирует про-лиферацию клеток-предшественников нейронов в куль-турах клеток [50,51], активирует дыхательную цепь мито-хондрий [52], снижает воспаление за счет снижения син-теза интерлейкина-1 бета (IL-1β), фактора некроза опухо-ли альфа (TNF-α) [53] и арахидоновой кислоты [54]. Пе-речисленные механизмы действия лития актуальны не только для лечения БА, но и других нейродегенеративных заболеваний [55].…”