Acute kidney injury (AKI) is a life-threatening and costly condition, affecting ~15% of all hospitalized patients, including up to 65% of those requiring intensive care. Despite the consequences and expense associated with AKI, proactive fluid management and dialysis remain the only interventions. Yet, as AKI develops, cells initially induce protective pathways to maintain their viability. One pathway, the Unfolded Protein Response (UPR), is initiated in the endoplasmic reticulum (ER) and can protect cells from the accumulation of damaged proteins and oxidative injury, preserving protein homeostasis (“proteostasis”) despite environmental stress. However, as a result of unmitigated stress, ER stress and UPR activation are cytotoxic, and emerging data suggest that the UPR may cause AKI. To directly link the UPR to AKI, and to ask if ER stress and the UPR are directly associated with AKI, a unique inducible nephron-tubule-specific knockout (KO) mouse was created and characterized. In this model, the gene encoding GRP170, a molecular chaperone that maintains ER proteostasis, can be deleted at will. The applicant’s published data indicate that GRP170 ablation causes inappropriate UPR activation and a severe AKI-like phenotype. To more precisely define how the UPR contributes to AKI, the applicant has recently been focused on heterozygous GRP170NT+/- mice, which have more subtle UPR activation but are susceptible to kidney injury only when subjected to an additional renal stressor. Preliminary data indicate a temporal association between stimulation of one UPR stress sensor, PERK, and early AKI, implying a causal link. Hence this GRP170NT+/- model is the ideal tool with which to clarify the UPR-AKI relationship, avoiding interference from the confounding variables that hindered prior in vivo studies. To this end, the first objective of this project is to discern the mechanism by which PERK drives AKI caused via two clinically-relevant insults: a commonly used nephrotoxic chemotherapeutic, cisplatin, and Ischemia-Reperfusion Injury (IRI). The second objective is to determine if a preclinical PERK-specific inhibitor ameliorates AKI in vivo. Together, these two approaches will clarify the role of PERK in AKI and inform development and/or repurposing of PERK-modulating drugs for AKI. Enhanced experimental training will expand the applicant’s experience with diverse techniques and resources, including murine and renal tubule epithelial cell culture AKI models, imaging, and transcriptomics. In addition to technical competence, this award will further develop the applicant’s writing, presenting, mentoring, and management skills. Training will be realized in the labs of well-established co-mentors with complementary expertise and a history of educating successful trainees. Training will be enhanced by the exceptional environment offered at the University of Pittsburgh. Formal coursework, participation in seminars, and presentations at local and national meetin...