The C289G and C418R missense mutations cause rapid sequestration of human Parkin into insoluble aggregates.

Mutations in the parkin gene are responsible for autosomal recessive parkinsonism. The disease-linked missense mutations are highly concentrated in the RING-IBR-RING domains of Parkin. In this study, we investigated the consequences of several missense parkin gene mutations in cell culture. We have demonstrated that two of these mutations (C289G and C418R), which replace consensus cysteine residues in the RING domains, significantly decrease the solubility of Parkin in cells. Upon overexpression, the presumably misfolded proteins formed cytoplasmic aggregates that concentrated into large perinuclear inclusion bodies when proteasome activity was inhibited. This process required active microtubule-dependent retrograde transport, as previously reported for aggresome formation. These results provide information on the molecular basis of the loss of function caused by mutations of critical residues in Parkin. They also contribute to our understanding of the cellular mechanism underlying the aggregation of mutant Parkin.