Tilianin mediates neuroprotection against ischemic injury by attenuating CaMKII-dependent mitochondrion-mediated apoptosis and MAPK/NF-κB signaling

Abstract

Aims: Tilianin, a naturally occurring flavonoid glycoside, possesses versatile biological activities including antioxidant, anti-inflammatory, energy collecting and anti-hypoxic effects. Little is known about the mechanisms underlying the effect of tilianin against ischemic injury in neuronal cells. We aimed to determine the potential targets and mechanisms of tilianin treatment behind the crosstalk pathways induced by oxygen-glucose deprivation (OGD).

Main methods: We used an in silico docking model for interaction mode analysis and in vitro models for mechanistic exploration and target verification. Protein changes were measured using cellular immunofluorescence and ELISA techniques.

Key findings: The ability of tilianin to promote recovery of OGD-induced neurocytotoxic injury was demonstrated by maintenance of cell viability, membrane integrity and nuclear homogeneity. Tilianin treatment was also found to balance the concentrations of proapoptotic and antiapoptotic proteins that had been modified by OGD-induced mitochondrial dysfunction. Of these intersectional cascades, Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) was found to bind efficiently with tilianin. This presented a certain binding score along with down-regulation of ox-CaMKII and p-CaMKII in SH-SY5Y cells affected by OGD. Importantly, after utilizing KN93, one specific CaMKII inhibitor, tilianin-mediated neuroprotection against OGD was abolished. This effect was accompanied by upregulation of mitochondrial function. Thus, the beneficial effects of tilianin toward mitochondrion-mediated apoptosis and p38/JNK/NF-κB-associated inflammatory pathways were reversed following CaMKII inhibition.

Significance: Our study indicated that attenuation of CaMKII-linked signaling mediated through mitochondria and p38/JNK/NF-κB inflammatory pathways is a key mechanism by which tilianin exerts its neuroprotective effects against cerebral ischemia.

Keywords: Apoptosis; Ca(2+)/calmodulin-dependent protein kinase II; Mitochondria; Mitogen-activated protein kinase; Nuclear factor kappa B; Oxygen-glucose deprivation; Tilianin.