Contrasts in neuronal aggregates

The protein aggregates of various neurodegenerative diseases are not created equal. So say Matsumoto et al. (page 75), who find that the aggregates of familial amyotrophic lateral sclerosis (fALS) are unusually porous compared to those of Huntington's disease (HD).

Both diseases are associated with the neuronal aggregation of a mutant protein in affected individuals. For fALS, the mutant protein is the free radical scavenger SOD1. The authors found that, unlike mutant htt, which forms a solid, impenetrable aggregate in HD, mutant SOD1 formed a honeycomb-like structure. YFP and other globular proteins were able to diffuse freely through cells containing SOD1 aggregates.

Certain proteins were not as free to come and go, however. These proteins might thus be the basis for cellular toxicity. The proteasome, a known interacting partner for...