Project Summary Acute kidney injury (AKI) is a common and severe complication in hospitalized patients, which is associated with high morbidity and mortality rates. Patients who survive an episode of AKI are at increased risk for progression to chronic kidney disease and end-stage renal disease. Therefore, there is a dire need to identify therapeutic strategies to prevent or treat AKI. The kidneys have a high metabolic rate and substantial decreases in the levels of nicotinamide adenine dinucleotide (NAD+) and NAD+/NADH imbalance impairs energy generation and kidney function during AKI. Augmentation of NAD+ may protect kidney tubule against diverse stressors. However, how NAD+/NADH imbalance contributes to development of AKI remains unknown. Our preliminary studies involving a druggable genome screen have discovered an unexpected role of a transcriptional repressor CtBP2 (C-Terminal Binding Protein 2) in renal epithelial cell death. CtBP2 is a NAD+/NADH-dependent transcriptional repressor. Our studies show that CtBP2 is activated in ischemic, nephrotoxic, and rhabdomyolysis-associated AKI. Moreover, in multiple mouse models of AKI, pharmacological inhibition of CtBP2 mitigated renal impairment, suggesting a pathogenic role. Furthermore, we found that CtBP2 is acetylated and this is critical for nuclear localization during AKI. Our ChIP-seq (chromatin immunoprecipitation followed by sequencing) studies showed that CtBP2 transcriptionally suppresses many genes involved in energy metabolism, including NAD+ biosynthesis in AKI. We hypothesize that CtBP2 is a pathogenic regulator of RTEC dysfunction and cell death that regulates NAD+/NADH imbalance-mediated metabolic dysregulation as a stress-induced metabolic sensor during AKI. To test this hypothesis, we will investigate a role of p300 in nuclear localization and activation of CtBP2 in AKI (Aim 1) and determine a pathogenic role of CtBP2 in renal injury and metabolic changes during AKI (Aim 2). These studies will significantly advance our understanding of the molecular mechanisms of CtBP2 activation during AKI. These outcomes will define novel molecular networks that underlie the severity of AKI and could lead to development of CtBP2 inhibition as a novel therapeutic strategy.