Regucalcin confers resistance to amyloid-β toxicity in neuronally differentiated PC12 cells

Amyloid-β (Aβ), a primary component of amyloid plaques, has been widely associated with the pathogenesis of Alzheimer's disease. The Ca²⁺-binding protein regucalcin (RGN) plays multiple roles in maintaining cell functions by regulating intracellular calcium homeostasis, various signaling pathways, and gene expression systems. Here, we investigated the functional role of RGN against Aβ-induced cytotoxicity in neuronally differentiated PC12 cells. Overexpression of RGN reduced Aβ-induced apoptosis by reducing mitochondrial dysfunction and caspase activation. It also attenuated Aβ-induced reactive oxygen species production and oxidative damage and decreased Aβ-induced nitric oxide (NO) overproduction, upregulation of inducible NO synthase by nuclear factor-κB, and nitrosative damage. Interestingly, the genetic disruption of RGN increased the susceptibility of neuronally differentiated PC12 cells to Aβ toxicity. Thus, RGN possesses antioxidant activity against Aβ-induced oxidative and nitrosative stress and may play protective roles against Aβ-induced neurotoxicity in Alzheimer's disease.