Le rôle de l’AMPK dans le vieillissement et la perte de plasticité neuronale liée au vieillissement chez C. elegans

The dramatic increase in life expectancy during the 20th century was accompanied by a resultant epidemic of age-related pathologies including neurodegenerative diseases. Unfortunately, current therapeutics primarily focusing on protein misfolding aspects of diseases such as Alzheimer’s Disease (AD) have been unsuccessful in the clinical trials. Recent epidemiological studies have suggested a strong association between metabolic dysfunction and neurodegeneration. Therefore, an alternative approach is to target metabolic pathways disrupted in AD models for therapeutics. AMP activated protein kinase (AMPK) is activated in a low energy state via sensing the AMP: ATP ratio. Once active, AMPK promotes longevity in model organism and protects against a wide range of age related diseases including neurodegenerative diseases. In addition, AMPK regulates mitochondrial homeostasis and mitochondrial networks in mammals. However, whether mitochondrial regulation causally links AMPK to protection against neurodegenerative disease is unknown. Here we use a learning and memory protocol in C. elegans as readout of neuronal function. We show that nematodes expressing the toxic amyloid peptide Aβ1-42 in the neurons display impaired learning ability, which can be rescued by constitutive activation of AMPK (CA-AMPK). We further show that CA-AMPK enhances learning ability in wild type nematodes by promoting mitochondrial fusion. Indeed, fusion deficient worms show impaired learning, which can be rescued by restoring mitochondrial fusion specifically in the neurons. Additional results suggest that AMPK might promote its beneficial effects on neuronal function via inhibition of CREBregulated transcriptional co-activator 1 (CRTC-1). Our results show that targeting neuronal metabolism may be a viable therapeutic option to restore neuronal function in the context of neurodegenerative diseases.