Genetic inactivation of the USP19 deubiquitinase regulates a-synuclein ubiquitination and inhibits accumulation of Lewy body like aggregates in mice

Abstract

The USP19 deubiquitinase is found in a locus associated with Parkinson's Disease (PD), interacts with heat shock proteins and promotes secretion of a-synuclein (a-syn) through the misfolding associated protein secretion (MAPS) pathway. Since these processes might modulate the processing of a-syn aggregates during the progression of PD, we tested the effect of USP19 knockout (KO) in mice expressing the A53T mutation of a-syn and in whom a-syn preformed fibrils (PFF) had been injected in the striatum. Compared to WT, KO brains showed decreased accumulation of phospho-synuclein (pSyn) positive aggregates. The improved pathology was associated with less activation of microglia, higher levels of synaptic marker proteins and improved performance in a tail suspension test. Exposure of primary neurons from WT and KO mice to PFF in vitro also led to decreased accumulation of pSyn aggregates. KO did not affect uptake of PFF in the cultured neurons. It also did not affect the propagation of aggregates as assessed by exposing WT or KO neurons to PFF and measuring pSyn positive aggregates in non-exposed adjacent neurons separated using a microfluidics device. We conclude that USP19 instead modulates intracellular dynamics of aggregates. Indeed, at the early time following PFF injection when the number of pSyn positive neurons were similar in WT and KO brains, the KO neurons contained less aggregates. KO brain aggregates stained more intensely with anti-ubiquitin antibodies. Immunoprecipitation of soluble proteins from primary neurons exposed to PFF with antibodies to ubiquitin or pSyn showed higher levels of ubiquitinated a-syn oligomeric species in the KO neurons. We propose that the improved pathology in USP19 KO brains may arise from decreased formation or enhanced clearance of the more ubiquitinated aggregates and/or enhanced disassembly towards more soluble oligomeric species. USP19 inhibition may represent a novel therapeutic approach that targets the intracellular dynamics of a-syn complexes.

Mono-UFMylation promotes misfolding-associated secretion of α-synuclein

“…Several recent studies have linked UFM1 and USP19 to the intercellular transfer of neurodegenerative disease–associated neurotoxic proteins. Specifically, in UFM1-deficient induced pluripotent stem cell–derived neurons and in USP19 KO mice, the seeding and propagation of misfolded Tau and α-Syn are inhibited ( 45 – 47 ). Although the underlying mechanisms are unclear, these studies and our work consolidate an emerging theme that the dynamics of protein aggregation may be influenced by a functional interplay between USP19 and UFM1 in either MAPS or a related UcPS process.…”

Imaging spatial transcriptomics reveals molecular patterns of vulnerability to pathology in a transgenic α-synucleinopathy model

“…Several other deubiquitinases (Usp10, Usp15, Usp19) showed inconsistent patterns of alteration. These proteins are generally considered to be promoters of α-synuclein aggregation, as the deubiquitination of α-synuclein stops it from proceeding through proteasomal or autophagic degradation 86,87 ; however, some DUBs have may have the opposite effect 88 , so this effect is not entirely clear. Notably, Usp19, the inhibition of which reduces α-synuclein aggregation in the α-synuclein PFF mouse model 87 , was expressed more highly in pSyn + compared to pSynα-syn-tg neurons, indicating that either the presence of pSyn pathology induces Usp19, or cells with intrinsically higher Usp19 are more predisposed to developing pathology.…”