Sagar, V. K. | bioRxiv Science

bioRxiv2024

Mitochondrial NADK2-dependent NADPH controls Tau oligomer uptake in human neurons

Alterations in NADH and NADPH metabolism are associated with aging, cancer, and Alzheimers Disease. Using 2P-FLIM imaging of the mitochondrial NAD(P)H in live human neurons and PS19 mouse brains, we show that tau oligomers (TauO) upregulate the mitochondrial de novo NADPH synthesis through NADK2. This process controls LRP1-mediated internalization of TauO, setting a vicious cycle for further TauO internalization. Thus, mitochondrial NADK2-dependent NADPH controls a key step in TauO toxicity.

neuroscience↗

bioRxiv2024

Disrupted mitochondrial response to nutrients is a presymptomatic event in the cortex of the APPSAA knock-in mouse model of Alzheimer disease

IntroductionReduced brain energy metabolism, mTOR dysregulation, and extracellular amyloid-{beta} oligomer (xcA{beta}O) buildup characterize AD; how they collectively promote neurodegeneration is poorly understood. We previously reported that xcA{beta}Os inhibit Nutrient-induced Mitochondrial Activity (NiMA) in cultured neurons. We now report NiMA disruption in vivo. MethodsBrain energy metabolism and oxygen consumption were recorded in APPSAA/+ mice using two-photon fluorescence lifetime imaging and multiparametric photoacoustic microscopy. ResultsNiMA is inhibited in APPSAA/+ mice before other defects are detected in these amyloid-{beta}-producing animals that do not overexpress APP or contain foreign DNA inserts into genomic DNA. GSK3{beta} signals through mTORC1 to regulate NiMA independently of mitochondrial biogenesis. Inhibition of GSK3{beta} with lithium or TWS119 stimulates NiMA in cultured human neurons, and mitochondrial activity and oxygen consumption in APPSAA mice. ConclusionNiMA disruption in vivo occurs before histopathological changes and cognitive decline in APPSAA mice, and may represent an early stage in human AD.

neuroscience↗