Background:The mechanism of action of resveratrol on sirtuin and mitochondrial metabolism remains elusive. Results: Resveratrol increases the mitochondrial NAD ϩ level by direct stimulation of complex I, leading to a SIRT3-dependent

Resveratrol is often described as a promising therapeutic molecule for numerous diseases, especially in metabolic and neurodegenerative disorders. While the mechanism of action is still debated, an increasing literature reports that resveratrol regulates the mitochondrial respiratory chain function. In a recent study we have identified mitochondrial complex I as a direct target of this molecule. Nevertheless, the mechanisms and consequences of such an interaction still require further investigation. In this study, we identified in silico by docking study a binding site for resveratrol at the nucleotide pocket of complex I. In vitro, using solubilized complex I, we demonstrated a competition between NAD+ and resveratrol. At low doses (<5μM), resveratrol stimulated complex I activity, whereas at high dose (50 μM) it rather decreased it. In vivo, in brain mitochondria from resveratrol treated young mice, we showed that complex I activity was increased, whereas the respiration rate was not improved. Moreover, in old mice with low antioxidant defenses, we demonstrated that complex I activation by resveratrol led to oxidative stress. These results bring new insights into the mechanism of action of resveratrol on mitochondria and highlight the importance of the balance between pro- and antioxidant effects of resveratrol depending on its dose and age. These parameters should be taken into account when clinical trials using resveratrol or analogues have to be designed.

Mitochondrial dynamics and distribution are critical for supplying ATP in response to energy demand. CLUH is a protein involved in mitochondrial distribution whose dysfunction leads to mitochondrial clustering, the metabolic consequences of which remain unknown. To gain insight into the role of CLUH on mitochondrial energy production and cellular metabolism, we have generated CLUHknockout cells using CRISPR/Cas9. Mitochondrial clustering was associated with a smaller cell size and with decreased abundance of respiratory complexes, resulting in oxidative phosphorylation (OXPHOS) defects. This energetic impairment was found to be due to the alteration of mitochondrial translation and to a metabolic shift towards glucose dependency. Metabolomic profiling by mass spectroscopy revealed an increase in the concentration of some amino acids, indicating a dysfunctional Krebs cycle, and increased palmitoylcarnitine concentration, indicating an alteration of fatty acid oxidation, and a dramatic decrease in the concentrations of phosphatidylcholine and sphingomyeline, consistent with the decreased cell size. Taken together, our study establishes a clear function for CLUH in coupling mitochondrial distribution to the control of cell energetic and metabolic status.