Altered O-GlcNAcylation and mitochondrial dysfunction,a molecular link between brain glucose dysregulation and sporadic Alzheimer's disease

Alzheimer’s disease is a neurodegenerative disease that affected over 6.5 million people in the United States in 2021,with this number expected to double in the next 40 years without any sort of treatment.Due to its heterogeneity and complexity,the etiology of Alzheimer’s disease,especially sporadic Alzheimer’s disease,remains largely unclear.Compelling evidence suggests that brain glucose hypometabolism,preceding Alzheimer’s disease hallmarks,is involved in the pathogenesis of Alzheimer’s disease.Herein,we discuss the potential causes of reduced glucose uptake and the mechanisms underlying glucose hypometabolism and Alzheimer’s disease pathology.Specifically,decreased O-Glc NAcylation levels by glucose deficiency alter mitochondrial functions and together contribute to Alzheimer’s disease pathogenesis.One major problem with Alzheimer’s disease research is that the disease progresses for several years before the onset of any symptoms,suggesting the critical need for appropriate models to study the molecular changes in the early phase of Alzheimer’s disease progression.Therefore,this review also discusses current available sporadic Alzheimer’s disease models induced by metabolic abnormalities and provides novel directions for establishing a human neuronal sporadic Alzheimer’s disease model that better represents human sporadic Alzheimer’s disease as a metabolic disease.

Mitochondrial dysfunction and cellularmetabolic deficiency in Alzheimer's disease

Alzheimer＇s disease （AD） is an age-related neurodegenerative disorder. The pathology of AD includes amyloid-β （Aβ） deposits in neuritic plaques and neurofibrillary tangles composed of hyperphosphorylated tau, as well as neuronal loss in specific brain regions. Increasing epidemiological and functional neuroimaging evidence indicates that global and regional disruptions in brain metabolism are involved in the pathogenesis of this disease. Aβ precursor protein is cleaved to produce both extracellular and intracellular Aβ, accumulation of which might interfere with the homeostasis of cellular metabolism. Mitochondria are highly dynamic organelles that not only supply the main energy to the cell but also regulate apoptosis. Mitochondrial dysfunction might contribute to Aβ neurotoxicity. In this review, we summarize the pathways ofAβ generation and its potential neurotoxic effects on cellular metabolism and mitochondrial dysfunction.