Alzheimer disease (AD) brains feature amply documented biochemical alterations: diminished overall glucose consumption concomitant with an increased non-oxidative (?aerobic?) glycolysis which is paralleled by diminished oxygen consumption, oxidative stress, and changes in the activity of mitochondrial enzymes involved in energy metabolism. The causal-temporal relationship between mitochondria changes and AD? related readouts (any and all of those) is yet to be established. The overarching hypothesis of this proposal is that a decrease in glycolytic flux, an increase in aerobic glycolysis, and oxidative stress are the consequence of abnormal interaction of mitochondrial oxidation with glycolysis that is triggered by disease-causing idiopathic or inherited factors (e.g., mutated presenilins or other AD-associated proteins). The damage occurs at the level of mitochondria?glycolysis interface-related functions such as pyruvate oxidation or transport into mitochondria, or the functioning of mitochondrial metabolite shuttles that are involved in glycolytic NAD+ regeneration. This results in the adaptive changes in mitochondrial proteome, such as the changes in tricarboxylic acid cycle or respiratory chain enzyme activities. In turn, these changes may lead to an increased ROS production and Ca2+ dysregulation. Furthermore, as the cellular and mitochondrial ROS scavenging systems are fueled by NAD(P)H, a decrease in glycolytic flux would decrease the capacity of ROS scavenging systems and augment the oxidative stress. This proposal will verify a subset of hypotheses that stem from this overarching scenario. Specifically, we intend to demonstrate (hypothesis 1) that the changes in mitochondria occur in AD neurons when they are still immature (at the neural precursor stage) and get augmented upon their maturation. Further (hypothesis 2), we will elucidate whether changing pyruvate utilization and/or the shuttles that are involved in regenerating glycolytic NAD+ (malate aspartate shuttle and alpha-glycerophosphate shuttle) is sufficient to trigger the remodeling of mitoproteome toward AD energy phenotype described above. Further, (hypothesis 3) we will check whether augmenting the cellular pool of NAD(P)H by pharmacological means would prevent the changes in mitoproteome, diminish the oxidative stress and improve the bioenergetics of AD neurons. Finally, we will test the effects of various pharmacological compounds studied in non-human cells and mouse AD models in other Projects of this PPG on the bioenergetics of human AD neurons. These hypotheses will be tested in human neuronal precursors and neurons derived from hiPSC. The isogenic non-diseased PSEN1 mutant cells will be used in these studies, as well as PSEN1 knockout cells, and isogenic hiPSCs bearing Tau-A152T mutation.