Figure 1.

A schematic indicating autophagosome and lysosome formation under (A) normal conditions in the presence of wild-type htt or (B–D) in the presence of mhtt. Three possible consequences of mhtt expression in neurons are (B) inefficient cargo loading of autophagosomes; (C) increased normal autophagic flux in response to mhtt, resulting in an increased number of autophagosomes, lysosomes and autolysosomes; and (D) increased number of autophagosomes and lysosomes when turnover is blocked distally, for example, by diminished fusion of autophagosomes and lysosomes.