Nigral ATP13A2 depletion induces Parkinson's disease-related neurodegeneration in non-human primates

Abstract

Abstract Lysosomal impairment is strongly implicated in Parkinson's disease (PD). Among the several PD-linked genes, the ATP13A2 gene, associated with the PARK9 locus, encodes a transmembrane lysosomal P5-type ATPase that acts as a lysosomal polyamine exporter. Mutations in the ATP13A2 gene were primarily identified as the cause of Kufor-Rakeb syndrome (KRS), a juvenile-onset form of PD. Subsequently, an increasing list of several homozygous and compound-heterozygous mutations has been described. These mutations result in truncation of the ATP13A2 protein, leading to a loss of function but surprisingly causing heterogeneity and variability in the clinical symptoms associated with different brain pathologies. In vitro studies show that its loss compromises lysosomal function, contributing to cell death. To understand the role of ATP13A2 dysfunction in disease, we disrupted its expression through a viral vector-based approach in nonhuman primates. Here, in this pilot study, we injected bilaterally into the substantia nigra of macaque monkeys, a lentiviral vector expressing an ATP13A2 small hairpin RNA. Animals were terminated five months later, and brains were harvested to evaluate cerebral pathological markers known to be affected in KRS and PD. We characterised the pattern of dopaminergic loss in the striatum and the substantia nigra, the regional distribution of α-synuclein immunoreactivity in several brain structures, and its pathological status (i.e., S129 phosphorylation), the accumulation of heavy metals in nigral sections and occurrence of lysosomal dysfunction. Our findings show that lentivirus-mediated ATP13A2 silencing can induce significant and ongoing degeneration in the nigrostriatal pathway, α-synuclein pathology, and iron accumulation in nonhuman primates.