Yong Liang1, Jing Xu2, Yu Wang3,4, Jia-Yu Tang5, Song-Lin Yang5, Hong-Guang Xiang4, Shi-Xing Wu4, Xiao-Juan Li4. 1. Department of Neurology, The First Hospital of Changsha, Changsha, China. 2. Department of Clinical Laboratory, Jiangxi Maternal and Child Health Hospital, Nanchang, China. 3. Department of Neurology, The Second Xiangya Hospital of Central South University, Changsha, China. 4. Department of Neurology, Geological Mining Hospital of Hunan Province, Changsha, China. 5. Department of Neurology, Brain Hospital of Hunan Province, Changsha, China.
Abstract
BACKGROUND/AIMS: Cerebral ischemia-reperfusion (I/R) injury involves multiple independently fatal terminal pathways. CK2α/NADPH oxidase is an important signaling pathway associated with ischemia-reperfusion injury, and miR-125b can regulate oxidative stress-related injury. In this study, we investigated whether the effect of miR-125b in rat brain I/R injury occurs through its modulation of the CK2α/NADPH oxidase pathway. METHODS: Rats were subjected to 2 h of cerebral ischemia followed by 24 h of reperfusion to establish an I/R injury model. Neurological deficit was evaluated using a five-point score. Infarct volume was evaluated with 2, 3, 5-triphenyltetrazolium chloride (TTC) staining, and RT-PCR was used to detect expressions of miR125b and CK2α. We then examined the association between miR-125b expression and the CK2α/NADPH oxidative signaling pathway in a PC-12 cell oxygen-glucose deprivation and reoxygenation (OGD/R) injury model. Transfection with miR-125b mimics, an miR-125b inhibitor, and luciferase reporter gene plasmid was accomplished using commercial kits. In these cells, Western blots were used to detect the levels of expression of CK2α, cleaved caspase-3, NOX2, and NOX4. RT-PCR was used to detect the expressions of CK2α, miR125b, NOX2, and NOX4. We evaluated Lactate Dehydrogenase (LDH) level, NADPH oxidase activity, and caspase-3 activity using commercial kits. Mitochondrial reactive oxygen species (ROS) were measured by fluorescence microscopy. For both PC-12 cells and rat brains, histological analyses were conducted to observe morphological changes, and apoptosis was measured using a commercial kit. RESULTS: I/R rats exhibited an increase in neurological deficit score, infarct volume, and cellular apoptosis, along with miR-125b elevation and CK2α downregulation. OGD/R treatment increased PC-12 cells' injuries, cellular apoptosis, and ROS levels. These changes were associated with miR-125b elevation, CK2α downregulation and activations of NOX2 and NOX4, mimicking our in vivo findings. All of these effects were reversed by the inhibition of miR-125b, confirming a strong correlation between miR-125b activity and the CK2α/NADPH oxidase signaling pathway. CONCLUSIONS: Based on these observations, we conclude that inhibition of miR-125b protects the rat brain from I/R injury by regulating the CK2α/NADPH oxidative signaling pathway.
BACKGROUND/AIMS: Cerebral ischemia-reperfusion (I/R) injury involves multiple independently fatal terminal pathways. CK2α/NADPH oxidase is an important signaling pathway associated with ischemia-reperfusion injury, and miR-125b can regulate oxidative stress-related injury. In this study, we investigated whether the effect of miR-125b in rat brain I/R injury occurs through its modulation of the CK2α/NADPH oxidase pathway. METHODS:Rats were subjected to 2 h of cerebral ischemia followed by 24 h of reperfusion to establish an I/R injury model. Neurological deficit was evaluated using a five-point score. Infarct volume was evaluated with 2, 3, 5-triphenyltetrazolium chloride (TTC) staining, and RT-PCR was used to detect expressions of miR125b and CK2α. We then examined the association between miR-125b expression and the CK2α/NADPH oxidative signaling pathway in a PC-12 cell oxygen-glucose deprivation and reoxygenation (OGD/R) injury model. Transfection with miR-125b mimics, an miR-125b inhibitor, and luciferase reporter gene plasmid was accomplished using commercial kits. In these cells, Western blots were used to detect the levels of expression of CK2α, cleaved caspase-3, NOX2, and NOX4. RT-PCR was used to detect the expressions of CK2α, miR125b, NOX2, and NOX4. We evaluated Lactate Dehydrogenase (LDH) level, NADPH oxidase activity, and caspase-3 activity using commercial kits. Mitochondrial reactive oxygen species (ROS) were measured by fluorescence microscopy. For both PC-12 cells and rat brains, histological analyses were conducted to observe morphological changes, and apoptosis was measured using a commercial kit. RESULTS: I/R rats exhibited an increase in neurological deficit score, infarct volume, and cellular apoptosis, along with miR-125b elevation and CK2α downregulation. OGD/R treatment increased PC-12 cells' injuries, cellular apoptosis, and ROS levels. These changes were associated with miR-125b elevation, CK2α downregulation and activations of NOX2 and NOX4, mimicking our in vivo findings. All of these effects were reversed by the inhibition of miR-125b, confirming a strong correlation between miR-125b activity and the CK2α/NADPH oxidase signaling pathway. CONCLUSIONS: Based on these observations, we conclude that inhibition of miR-125b protects the rat brain from I/R injury by regulating the CK2α/NADPH oxidative signaling pathway.