Parkin ubiquitinates and promotes the degradation of RanBP2

Parkinson disease (PD) is a common neurodegenerative disorder, which involves the deterioration of dopaminergic neurons in the pars compacta of the substantia nigra. The etiology of PD is still unknown, but recent identification of mutations in familial cases of PD has advanced the understanding of the molecular mechanisms of this neurological disease. Mutations in the parkin gene, which encodes for ubiquitin-protein ligase (E3), have been implicated in autosomal recessive juvenile Parkinsonism, an early onset and common familial form of PD. Here we reported that Parkin selectively binds to RanBP2, which is localized in the cytoplasmic filament of the nuclear pore complex and belongs to the small ubiquitin-related modifier E3 ligase family. We also demonstrated that RanBP2 becomes a target for Parkin E3 ubiquitin-ligase and is processed via Parkin-mediated ubiquitination and subsequent proteasomal degradation. Furthermore, Parkin controls the intracellular levels of sumoylated HDAC4, as a result of the ubiquitination and degradation of RanBP2. Our findings suggested that the intracellular levels of RanBP2 and its functional activity may be modulated by Parkin-mediated ubiquitination and proteasomal pathways.