GSK-3α activation mitigates Doxorubicin-induced cardiomyopathy through Keap1/Nrf2/HO-1 axis

Doxorubicin (Dox)-induced cardiomyopathy is marked by excessive oxidative stress, mitochondrial dysfunction and apoptosis, leading to progressive cardiac injury. Although glycogen synthase kinase-3 alpha (GSK-3α) regulates diverse cellular processes, its specific role in Dox-induced cardiomyocyte apoptosis and underlying signaling remains unknown. This study aimed to investigate whether GSK-3α regulates mitochondrial integrity, redox balance, and Nrf2 signaling under Dox stress.

Human cardiomyocytes were subjected to Dox treatment with or without GSK-3α overexpression. Mitochondrial function, reactive oxygen species (ROS) generation, cytochrome-c (Cyt-c) release, autophagy markers, and Keap1/Nrf2/HO-1 signaling were assessed. Cytosolic and nuclear fractions were analysed to determine Nrf2 subcellular localization.

GSK-3α overexpression markedly attenuated Dox-induced mitochondrial dysfunction and apoptosis, as evidenced by reduced ROS generation, preserved mitochondrial membrane potential, and diminished Cyt-c release, a key initiator of caspase-dependent apoptosis. Mechanistically, GSK-3α reduced p62 and Keap1 expression while significantly increasing Nrf2 levels and its downstream effector HO-1 in Dox-treated cells. Importantly, fractionation studies revealed that GSK-3α specifically enhanced Dox-induced nuclear translocation of Nrf2, as evidenced by increased nuclear Nrf2 abundance and an elevated nuclear-to-cytosolic Nrf2 ratio. This enhanced nuclear accumulation supports transcriptional activation of antioxidant defences. Together with increased autophagic activity, these effects synergistically mitigated oxidative and apoptotic signaling.

These findings identify GSK-3α as a novel regulator of the Keap1/Nrf2/HO-1 antioxidant pathway and demonstrate its anti-apoptotic roles in Dox-treated cardiomyocytes. GSK-3α thus emerges as a potential dual-action therapeutic target in Dox-induced cardiomyopathy.