Down-Regulation of IRF6 Protects Cortical Neurons Against Traumatic Neuronal Injury Through Activating Akt-eNOS Pathway

Abstract

Interferon regulatory factor 6 (IRF6) is a novel and unique member of the IRF family of transcription factors, and the regulation and function of IRF6 remain unknown. Recently, IRF6 was shown to be upregulated after TBI and could promote neuronal apoptosis under oxidative stress conditions. This study aimed to investigate the role of IRF6 in traumatic neuronal injury (TNI) in primary cultured mouse cortical neurons. We found that the expression of IRF6 was significantly increased within 48 after TNI, and peaked at 24 h. Knockdown of IRF6 using specific targeted small interfering RNA (siRNA) attenuated TNI-induced loss of neuronal viability and release of lactate dehydrogenase. The results of TUNEL staining showed that IRF6 knockdown markedly reduced neuronal apoptosis, which was accompanied by decreased activity of caspase-3. Furthermore, downregulation of IRF6 inhibited lipid peroxidation, promoted the activity of endogenous antioxidative enzymes, and differently regulated the expression of inflammatory cytokines after TNI. In addition, IRF6 knockdown significantly increased phosphorylation of Akt and endothelial nitric oxide synthase (eNOS), whereas blocking Akt-eNOS pathway via selective antagonists partly prevented the protective effects of IRF6 knockdown. These data show that downregulation of IRF6 affords protection against TNI through Akt-eNOS pathway-mediated antioxidative and anti-inflammatory activity.

Niche Cells Crosstalk In Neuroinflammation After Traumatic Brain Injury

“…TBI leads to series of profiles changes in neuron to present protective or harmful effects, initiating consequential inflammation and oxidative stress. For instance, induction of nociceptin/orphanin FQ 64 , accounts for the pain, anxiety and even inflammation in rat model 65 , and down-regulating IRF6 is proven to attenuate neuronal apoptosis 66 . The key to enhance the survival of new-born neurons from neurogenic niche, is lessening aberrant development and ectopic localization 67 .…”