Measuring Nonselective and Selective Autophagy in the Liver

Administration of leupeptin, a specific inhibitor of lysosomal cysteine proteinases, to starved rats or mice inhibits autolysosomal protein degradation and results in accumulation of autolysosomes in their livers. Immunoblotting of liver homogenates to examine autophagic flux in vivo reveals elevated levels of the selective autophagy substrate p62 and the autophagosomal membrane protein LC3-II in the livers of leupeptin-treated animals. Percoll density gradient centrifugation can be used to isolate autolysosomes from the livers of untreated and leupeptin-treated animals. Moreover, autolysosomes can be examined for the presence of sequestered cytoplasmic proteins as well as degradation intermediates.