Peroxiredoxin 1 inhibits streptozotocin-induced Alzheimer’s disease-like pathology in hippocampal neuronal cells via the blocking of Ca²⁺/Calpain/Cdk5-mediated mitochondrial fragmentation

Oxidative stress plays an essential role in the progression of Alzheimer’s disease (AD), the most common age-related neurodegenerative disorder. Streptozotocin (STZ)-induced abnormal brain insulin signaling and oxidative stress play crucial roles in the progression of Alzheimer’s disease (AD)-like pathology. Peroxiredoxins (Prxs) are associated with protection from neuronal death induced by oxidative stress. However, the molecular mechanisms underlying Prxs on STZ-induced progression of AD in the hippocampal neurons are not yet fully understood. Here, we evaluated whether Peroxiredoxin 1 (Prx1) affects STZ-induced AD-like pathology and cellular toxicity. Prx1 expression was increased by STZ treatment in the hippocampus cell line, HT-22 cells. We evaluated whether Prx1 affects STZ-induced HT-22 cells using overexpression. Prx1 successfully protected the forms of STZ-induced AD-like pathology, such as neuronal apoptosis, synaptic loss, and tau phosphorylation. Moreover, Prx1 suppressed the STZ-induced increase of mitochondrial dysfunction and fragmentation by down-regulating Drp1 phosphorylation and mitochondrial location. Prx1 plays a role in an upstream signal pathway of Drp1 phosphorylation, cyclin-dependent kinase 5 (Cdk5) by inhibiting the STZ-induced conversion of p35 to p25. We found that STZ-induced of intracellular Ca²⁺ accumulation was an important modulator of AD-like pathology progression by regulating Ca²⁺-mediated Calpain activation, and Prx1 down-regulated STZ-induced intracellular Ca²⁺ accumulation and Ca²⁺-mediated Calpain activation. Finally, we identified that Prx1 antioxidant capacity affected Ca²⁺/Calpain/Cdk5-mediated AD-like pathology progress. Therefore, these findings demonstrated that Prx1 is a key factor in STZ-induced hippocampal neuronal death through inhibition of Ca²⁺/Calpain/Cdk5-mediated mitochondrial dysfunction by protecting against oxidative stress.