Tracking mutant huntingtin aggregation kinetics in cells reveals three major populations that include an invariant oligomer pool

Abstract

Huntington disease is caused by expanded polyglutamine sequences in huntingtin, which procures its aggregation into intracellular inclusion bodies (IBs). Aggregate intermediates, such as soluble oligomers, are predicted to be toxic to cells, yet because of a lack of quantitative methods, the kinetics of aggregation in cells remains poorly understood. We used sedimentation velocity analysis to define and compare the heterogeneity and flux of purified huntingtin with huntingtin expressed in mammalian cells under non-denaturing conditions. Non-pathogenic huntingtin remained as hydrodynamically elongated monomers in vitro and in cells. Purified polyglutamine-expanded pathogenic huntingtin formed..