Impact of Mitophagy and Mitochondrial Unfolded Protein Response as New Adaptive Mechanisms Underlying Old Pathologies: Sarcopenia and Non-Alcoholic Fatty Liver Disease.

Mitochondria are the first-line defense of the cell in the presence of stressing processes that can induce mitochondrial dysfunction. Under these conditions, the activation of two axes is accomplished, namely, (i) the mitochondrial unfolded protein response (UPR) to promote cell recovery and survival of the mitochondrial network; (ii) the mitophagy process to eliminate altered or dysfunctional mitochondria. For these purposes, the former response induces the expression of chaperones, proteases, antioxidant components and protein import and assembly factors, whereas the latter is signaled through the activation of the PINK1/Parkin and BNIP3/NIX pathways.