Novel long non-coding RNAs in neuronal survival in focal cerebral ischemia

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 DESCRIPTION (provided by applicant): Focal cerebral ischemia (ischemic stroke) is the most common cause of disability and the fourth leading cause of death in the United State. Despite of the efforts on developing the pharmacological and surgical treatments of the disease, tissue plasminogen activator (tPA) is the only effective therapy at present. A better understanding of the pathological process and the discovery of new targets and therapies will significantly advance the field. There have been little studies on lncRNAs in cerebral ischemia. Through an lncRNA array analysis in a rat model of focal cerebral ischemia/reperfusion (IR), we have identified CAMK2D-associated transcript 1 (C2dat1) and 2 (C2dat2) (C2dat1-2) as two novel IR-induced lncRNAs that specifically regulated the expression of CaMKIIδ in rat and mouse models of focal cerebral IR. In our pilot study, C2dat1-2 mRNAs were upregulated in a time-dependent manner in mouse cortical penumbra after focal ischemic brain injury, which was accompanied by increased expression of CaMKIIδ at transcript and protein levels. The expression patterns of C2dat1-2 and CAMK2D were confirmed in mouse Neuro-2a cells in response to in vitro ischemia (oxygen-glucose deprivation/re-oxygenation, OGD/R). Knockdown of C2dat1 resulted in a significant blockade of CaMKIIδ expression, and potentiated OGD/R-induced cell death. Mechanistically, reduced CaMKIIδ expression upon silencing C2dat1 inhibited OGD/R-induced activation of the NF-κB signaling pathway. Further analysis showed that the downregulation of IKKα and further inhibition of IκBα degradation accounted for the inhibition of the NF-κB signaling activity by depleting C2dat1-2. Thus, C2dat1 appears to promote neuronal survival through regulating the NF-κB signaling pathway. Therefore, lncRNAs may be potential targets for therapeutic intervention of ischemia brain injury. Based on these preliminary findings, we hypothesize that C2dat1-2 are novel IR-induced lncRNAs that regulate the expression of CaMKIIδ to promote neuronal survival through the activation of the NF-κB signaling pathway. The primary goal of this application is to determine the function and signaling mechanisms of C2dat1-2, as well as the associated CaMKIIδ in IR- induced neuronal injury. The long-term goal is to gain more insights into the molecular bases of IR-associated biological processes and to identify novel therapeutic targets that confer neuroprotection during IR. Two specific aims are proposed: Specific Aim 1. Define the role of C2dat1-2 as novel ischemia-induced lncRNAs that promote neuronal survival by modulating CaMKIIδ expression in mouse primary neuronal cultures. Specific Aim 2. Determine if knockdown of C2dat1-2 potentiate IR-induced cell death in mouse model of focal cerebral ischemia and if the effects are mediated through down-regulation of CaMKIIδ.