ER stress and neonatal hypoxia ischemia encephalopathy

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Neonatal hypoxia ischemia (HI) is an injury to the neonatal brain caused by interrupted blood flow. It occurs in 2-4 of 1000 full-term births and 60% of premature infants. It is the leading cause of mortality and morbidity associated with life-long neurological impairments. Endoplasmic reticulum (ER) stress is a major pathology encountered after HI, associated with dysregulation of protein folding leading to apoptosis and inflammation. HI induced ER stress up regulates the pro-apoptotic Inositol requiring enzyme-1 alpha (IRE1α) signaling pathway and is also associated with reactive oxygen species (ROS) accumulation, mainly from the NADPH-dependent cytochrome P450 reductase (NPR) and P450 2E1 (CYP) complex. Bax-inhibitor 1 (BI-1) protein, expressed on ER membrane, has been shown to play a major role in inhibiting ER stress induced signaling pathways. BI-1 can directly bind to IRE1α thus inhibiting this pro-apoptotic pathway as well as reduce ROS accumulation by dissociating the NPR-CYP complex. The objective of this study is to establish BI-1s anti-apoptotic and anti-inflammatory effects in an in vitro oxygen glucose deprivation (OGD) model and in an in vivo neonatal HI rat model as well as to elucidate the mechanisms via which it confers its protective properties. Our central hypothesis is that (1) transfection of cells with Ad- TMBIM6 vector will improve cell viability after OGD as well as help determine BI-s-1s major pathways; (2) overexpression of the BI-1 protein in the brain, via Ad-TMBIM6 injection will improve recovery after neonatal HI by reducing ER stress induced (a) neuronal apoptosis via inhibition of IRE1α signaling pathway and (b) neuroinflammation via dissociation of the NPR-CYP complex and subsequent inhibition of ROS. Specific Aim 1: To determine the role of ER stress signaling pathways in the anti-apoptotic and anti-inflammatory mechanisms of BI-1 in an in vitro Oxygen Glucose Deprivation (OGD) model. Specific Aim 2: To determine whether BI-1 upregulation exerts its anti-apoptotic effects via the IRE1α signaling pathway in an in vivo neonatal HI rat model. Specific Aim 3: To investigate the anti-inflammatory effects of BI-1 overexpression and the signalling pathways involved in an in vivo neonatal HI rat model. The long-term goals of this proposal are to: 1) establish BI-1 as main regulator of ER stress 2) establish BI-1s signaling pathways after neonatal HI; 3) provide a basis for BI-1 as a potential therapeutic target.