Assessing Autophagic Activity and Aggregate Formation of Mutant Huntingtin in Mammalian Cells

The accumulation of mutant aggregate-prone proteins is a hallmark of the majority of neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's diseases. Autophagy, a cytosolic bulk degradation system, is the major clearance pathway for several aggregate-prone proteins, such as mutant huntingtin. The autophagosome-associated protein LC3-II is a specific marker of autophagic flux within cells, whereas aggregate formation of mutant huntingtin represents a good readout for studying autophagy modulation. Here we describe the method of assessing autophagic flux using LC3-II western blotting and substrate clearance by expressing the N-terminal fragment of huntingtin (htt exon 1) containing an expanded polyglutamine tract in mammalian cells.