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Veterans Health Administration
Michigan
Background and Innovation: Lysosomes (with an acidic milieu of pH around 4.5) contain numerous acidic hydrolases for maintaining cellular homeostasis via the degradation of unwanted cellular components. NCOA7 (nuclear receptor coactivator 7), a member of the Tre2/Bub2/Cdc16 (TBC), lysin motif (LysM), domain catalytic (TLDc) protein family, was initially implicated in the oxidative stress as oxidation resistance proteins. However, new research demonstrates that NCOA7 directly binds and modulates vacuolar H+- ATPase (V-ATPase) assembly and activity to control endolysosomal acidification. Our pilot data from SNP- edited, human stem cell-derived endothelial cells have demonstrated that allele-specific binding of the inflammatory transcription factor NF-κB to a common intronic variant SNP rs11154337 in NCOA7 controls gene expression. Namely, we found that a C/C genotype, present in ~25% of the population, promoted lower NCOA7 expression and less lysosomal acidification (Prelim Data). Global Ncoa7 transgenic knockout mice (Ncoa7-/-, KO) are viable up to 18 months of age, with comparable gross brain structure to wild-type littermate (WT). However, upon ischemic stroke, compared to WT mice, we found that Ncoa7 KO mice exhibited worsened ischemic stroke outcomes (higher mortality, worsened blood-brain barrier impairment, increased astrogliosis and microglial activation, and abnormal accumulation of myelin basic protein, MBP) (Prelim Data). Whether the above worsened ischemic stroke outcomes resulted from V-ATPase dysfunction and lysosomal de-acidification remains unknown. In this proposal, we will test our hypotheses: 1). NCOA7 plays an important role in V-ATPase activity and lysosomal function in stroke brain in a cell-specific manner; 2). NCOA7 deficient in neurons and in oligodendrocytes drives lysosomal dysfunction and oxysterol/bile acid- specific inflammation, as well as abnormal cholesterol and MBP accumulation; 3). Post-stroke administration of NCOA7 activator Compound 958 will stimulate NCOA7 activity and reduce stroke brain damage. Significance and Impact to Veterans Healthcare: Cardiovascular diseases such as hypertension and pre- hypertension are common in active US military personnel. Moreover, post-traumatic stress disorder is associated with different cardiovascular and cerebrovascular diseases in older veterans. Collectively, these are well-established risk factors for stroke. The goal of this proposal is to study cellular mechanisms underlying the worsened ischemic stroke outcomes in NCOA7 deficient conditions and to determine whether pharmacological stimulation of NCOA7 is a novel therapeutic strategy for improving acute ischemic stroke outcomes. Therefore, our proposal is closely relevant to Veterans and the VA mission. Path to translation/implementation: completion of this study will directly address our knowledge gap about role of NCOA7 in regulating lysosome function and cholesterol metabolism in the stroke brains. To explore pharmacological tools, utilizing computational modeling, we developed a novel small molecule activator of NCOA7, Compound 958, which reduced pulmonary endothelial immunoactivation and robustly improved survival of a mouse model of acute COVID-19 (Prelim Data). Our findings from this study will reveal potentials of NCOA7 as a therapeutic target for attenuating V-ATPase dysfunction in stroke brain, and efficacy of NCOA7 activator Compound 958 in stroke therapy.