Effects of Liquiritin on Mitochondrial Dynamics in Cerebral Ischemia-Reperfusion Injury by Regulating Nurr1 via the YAP-INF2-Mitochondrial Fission Pathway

This study investigated whether liquiritin can alleviate cerebral ischemia-reperfusion injury by regulating Nurr1 to mediate mitochondrial homeostasis. SH-SY5Y cells were subjected to glucose deprivation and reperfusion to establish a cerebral ischemia-reperfusion injury model in vitro. Cell viability and apoptosis were then determined using a cell counting kit and flow cytometry analysis. The degree of mitochondrial swelling was evaluated using a cell mitochondria isolation kit. Reactive superoxide generation, mitochondrial membrane potential, adenosine triphosphate (ATP) content, and mitochondrial ultrastructure were analyzed using dihydroethidium, JC-1 (5,5 ',6,6 '-tetrachloro1,1 ',3,3 '-tetramethylbenzimidazolylcarbocyanine iodide), luciferase-based ATP bioluminescent assays, and transmission electron microscopy, respectively. Quantitative reverse transcription PCR and western blot assays were conducted to detect levels of mitochondrial fission-related factors. Glucose deprivation and reperfusion exposure significantly reduced the viability and induced apoptosis of SH-SY5Y cells, indicating that glucose deprivation and reperfusion exposure successfully induced cerebral ischemia-reperfusion injury. Glucose deprivation and reperfusion exposure also increased the degree of mitochondrial swelling, promoted an increase in superoxide, and decreased mitochondrial membrane potential and ATP enzyme levels. Cerebral ischemia-reperfusion injury also significantly increases Drp1 and Fis1 protein expression, reduces mitofusin-2 and optic atrophy 1 levels, increases nuclear receptor-related 1 and inverted formin-2 expression, and decreases yes-associated protein expression. Electron microscopy further revealed sparse mitochondria and broken cristae. However, these findings were reversed by liquiritin in a dose-dependent manner and were further abolished after carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone treatment. Our study suggests that the protective effects of liquiritin on cerebral ischemia-reperfusion injury are linked to nuclear receptor-related 1 upregulation, followed by the regulation of yes-associated protein-inverted formin-2-mitochondrial fission pathways. Liquiritin may represent a novel therapeutic agent for treating cerebral ischemia-reperfusion injury.