RIP3 deficiency protects against traumatic brain injury (TBI) through suppressing oxidative stress, inflammation and apoptosis: Dependent on AMPK pathway.

Traumatic brain injury (TBI) is a leading cause of disability and mortality in young adults worldwide. The pathophysiology is not fully understood. Programmed necrosis (necroptosis) is a newly identified mechanism of cell death combining features of both apoptosis and necrosis. Receptor-interacting protein 3 (RIP3) plays an important role in programmed necrosis. However, the effect of RIP3-related pathway in TBI is little to be known. We attempted to explore the significance of RIP3 in regulating TBI in vivo. Significantly, TBI induced over-expression of RIP3 in the hippocampus of mice, as well as RIP1 and phosphorylated mixed lineage kinase domain-like protein (MLKL). Mice after TBI exhibited cognitive dysfunction and activation of glia cells, which were significantly attenuated by RIP3-knockout (KO). Moreover, inflammation and oxidative stress in hippocampus were markedly induced by TBI in wild type (WT) mice. Of note, the reduction of pro-inflammatory cytokines and oxidants was observed in RIP3-deficient mice, which was linked to the blockage of NLR pyrin domain containing 3 (NLRP3)/apoptosis-associated speck-like protein containing a CARD (ASC)/Caspase-1 and kelch-like ECH-associated protein 1 (Keap 1) pathways. Further, TBI induced hippocampus apoptosis, evidenced by the increase of cleaved Caspase-8/-3 and poly (ADP)-ribose polymerase (PARP) in WT mice, whereas being decreased by RIP3-knockout. In addition, RIP3 knockout led to phosphorylation of AMP-activated protein kinase α (AMPKα) in hippocampus of mice after TBI. And of note, the in vitro findings indicated that RIP3-ablation attenuated oxidative stress, inflammation and apoptosis in astrocytes, which was dependent on AMPKα activation. Together, suppressing RIP3 might be served as a therapeutic target against brain injury through inhibiting inflammation, oxidative stress and apoptosis.

Taurine-Upregulated Gene 1 Attenuates Cerebral Angiogenesis following Ischemic Stroke in Rats.

Objective: Angiogenesis is one of the therapeutic targets of cerebral infarction. Long noncoding RNAs (lncRNAs) can regulate the pathological process of angiogenesis following ischemic stroke. Taurine-upregulated gene 1 (TUG1), an lncRNA, is correlated to ischemic stroke. We intended to determine the effect of TUG1 on angiogenesis following an ischemic stroke. Materials and Methods: Middle cerebral artery occlusion (MCAO) was adopted to build a focal ischemic model of the rat brain, and pcDNA-TUG1 and miR-26a mimics were injected into rats. Neurological function was estimated through modified neurological severity scores. The volume of focal brain infarction was calculated through 2,3,5-triphenyltetrazolium chloride staining. The level of TUG1 and miR-26a was measured by PCR. The expression of vascular endothelial growth factor (VEGF) and CD31 was checked using immunohistochemistry and western blot. The correlation between miR-26a and TUG1 was verified through a luciferase reporter assay. Results: TUG1 increased noticeably while miR-26a was markedly reduced in MCAO rats. Overexpression of miR-26a improved neurological function recovery and enhanced cerebral angiogenesis in MCAO rats. TUG1 overexpression aggravated neurological deficits and suppressed cerebral angiogenesis in MCAO rats. Bioinformatics analysis revealed that miR-26a was one of the predicted targets of TUG1. Furthermore, TUG1 combined with miR-26a to regulate angiogenesis. TUG1 overexpression antagonized the role of miR-26a in neurological recovery and angiogenesis in MCAO rats. Conclusions: TUG1/miR-26a, which may act as a regulatory axis in angiogenesis following ischemic stroke, can be considered a potential target for cerebral infarction therapy.