NPD1 inhibits excessive autophagy by targeting RNF146 and wnt/β-catenin pathway in cerebral ischemia-reperfusion injury.

Cerebral ischemia-reperfusion (I/R) injury is a common pathological feature in ischemic stroke. Autophagy plays a key role in I/R-induced neuronal death. Neuroprotectin D1 (NPD1) is a docosahexaenoic acid derivative with neuroprotective and anti-inflammatory properties. The purpose of this study was to investigate the mediatory role of NPD1 on I/R-induced injury and to elucidate the underlying mechanisms involved in this process. An I/R injury model was established in PC12 cells induced by oxygen and glucose deprivation/reoxygenation OGD/R). NPD1 at increasing doses (5, 10, 20, 50, 100 nM) were added to cells one hour before OGD/R. To investigate the effect of ring finger protein 146 (RFP146) deficiency in I/R injury, PC12 cells were transiently transfected with small interfering RNF146 before further experiment. Compared to the controls, OGD/R-challenged cells exhibited significantly decreased cell viability, induced oxidative stress, and excessive autophagic cell death following OGD/R. Pretreatment with NPD1 protected cells against ischemic injury as evidenced by enhanced cell survival, decreased oxidative stress markers, and a lower level of autophagy compared to drug-free group. OGD/R also increased the level of RFP146 and inhibited the expression of β-catenin in PC12 cells. NPD1 treatment promoted the production of RNF146 and β-catenin in cells following OGD/R experiment. Moreover, RNF146 deficiency significantly inhibited β-catenin expression and reversed the protective effects of NPD1 in OGD/R-induced cells. NPD1 alleviated excessive autophagy via regulating RNF146 and Wnt/β-catenin signaling, suggesting the potential therapeutic use of NPD1 for the protection against cerebral I/R injury.