CYCS and chronic obstructive pulmonary disease: In support of an organelle-specific defect, Puente-Maestu and colleagues reported a sensitization of mitochondria to undergo permeability transition and this was associated with increased cytochrome c release from incubated isolated mitochondria of COPD limb skeletal muscle (Puente-Maestu et al., 2009b), noting that mitochondrial permeability transition is a well-established mechanism of tissue dysfunction in various organs (Bauer and Murphy, 2020) and has been proposed to play a role in aging skeletal muscle (Hepple, 2016).