Two major proteolysis systems, the ubiquitin-proteasome system, and the autophagy-lysosome system, contribute to degradation of various types of protein and/or protein aggregates. In general, the autophagy-lysosome system is involved in bulk intracellular degradation of proteins and organelles, while the ubiquitin-proteasome system is selective. During autophagy, a cytosolic form of LC3 (LC3-I) is conjugated to phosphatidylethanolamine to form LC3-phosphatidylethanolamine conjugate (LC3-II), which is recruited to autophagosomal membranes, and LC3-II is degraded by lysosomal hydrolases after the fusion of autophagosomes with lysosomes. Therefore, lysosomal turnover of LC3-II reflects starvation-induced autophagic activity, and detection of LC3 by immunoblotting or immunofluorescence has become a reliable method for monitoring autophagy. When autophagy is impaired, the level of p62/ SQSTM1, a ubiquitin-and LC3-binding protein, is increased in addition to the accumulation of ubiquitinated proteins. Here, we describe basic protocols to analyze endogenous LC3-II, p62, and autophagy-related proteins by immunoblotting, immunofluorescence, and electron microscopy.
CITATION STYLE
Tanida, I., & Waguri, S. (2010). Measurement of autophagy in cells and tissues. In Methods in Molecular Biology (Vol. 648, pp. 193–214). Humana Press Inc. https://doi.org/10.1007/978-1-60761-756-3_13
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