NADPH oxidase 2 activity disrupts Calmodulin/CaMKIIα complex via redox modifications of CaMKIIα-contained Cys30 and Cys289: Implications in Parkinson's disease

Ca²⁺/calmodulin-dependent protein kinase II α (CaMKIIα) signaling in the brain plays a critical role in regulating neuronal Ca²⁺ homeostasis. Its dysfunctional activity is associated with various neurological and neurodegenerative disorders, including Parkinson's disease (PD). Using computational modeling analysis, we predicted that, two essential cysteine residues contained in CaMKIIα, Cys30 and Cys289, may undergo redox modifications impacting the proper functioning of the CaMKIIα docking site for Ca²⁺/CaM, thus impeding the formation of the CaMKIIα:Ca²⁺/CaM complex, essential for a proper modulation of CaMKIIα kinase activity. Our subsequent in vitro investigations confirmed the computational predictions, specifically implicating Cys30 and Cys289 residues in impairing CaMKIIα:Ca²⁺/CaM interaction. We observed CaMKIIα:Ca²⁺/CaM complex disruption in dopamine (DA) nigrostriatal neurons of post-mortem Parkinson's disease (PD) patients' specimens, addressing the high relevance of this event in the disease. CaMKIIα:Ca²⁺/CaM complex disruption was also observed in both in vitro and in vivo rotenone models of PD, where this phenomenon was associated with CaMKIIα kinase hyperactivity. Moreover, we observed that, NADPH oxidase 2 (NOX2), a major enzymatic generator of superoxide anion (O₂^●-) and hydrogen peroxide (H₂O₂) in the brain with implications in PD pathogenesis, is responsible for CaMKIIα:Ca²⁺/CaM complex disruption associated to a stable Ca²⁺CAM-independent CaMKIIα kinase activity and intracellular Ca²⁺ accumulation. The present study highlights the importance of oxidative stress, in disturbing the delicate balance of CaMKIIα signaling in calcium dysregulation, offering novel insights into PD pathogenesis.