Role of the AMPK pathway in promoting autophagic flux via modulating mitochondrial dynamics in neurodegenerative diseases: Insight into prion diseases

Neurons are highly energy demanding cells dependent on the mitochondrial oxidative phosphorylation system. Mitochondria generate energy via respiratory complexes that constitute the electron transport chain. Adenosine triphosphate depletion or glucose starvation act as a trigger for the activation of adenosine monophosphate-activated protein kinase (AMPK). AMPK is an evolutionarily conserved protein that plays an important role in cell survival and organismal longevity through modulation of energy homeostasis and autophagy. Several studies suggest that AMPK activation may improve energy metabolism and protein clearance in the brains of patients with vascular injury or neurodegenerative disease. Mild mitochondrial dysfunction leads to activated AMPK signaling, but severe endoplasmic reticulum stress and mitochondrial dysfunction may lead to a shift from autophagy towards apoptosis and perturbed AMPK signaling. Hence, controlling mitochondrial dynamics and autophagic flux via AMPK activation might be a useful therapeutic strategy in neurodegenerative diseases to reinstate energy homeostasis and degrade misfolded proteins. In this review article, we discuss briefly the role of AMPK signaling in energy homeostasis, the structure of AMPK, activation mechanisms of AMPK, regulation of AMPK, the role of AMPK in autophagy, the role of AMPK in neurodegenerative diseases, and finally the role of autophagic flux in prion diseases.