Deficiency of parkin causes neurodegeneration and accumulation of pathological α-synuclein in monkey models
Rui Han, … , Xiao-Jiang Li, Weili Yang
Rui Han, … , Xiao-Jiang Li, Weili Yang
Published October 15, 2024
Citation Information: J Clin Invest. 2024;134(20):e179633. https://doi.org/10.1172/JCI179633.
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Deficiency of parkin causes neurodegeneration and accumulation of pathological α-synuclein in monkey models

Abstract

Parkinson’s disease (PD) is characterized by age-dependent neurodegeneration and the accumulation of toxic phosphorylated α-synuclein (pS129-α-syn). The mechanisms underlying these crucial pathological changes remain unclear. Mutations in parkin RBR E3 ubiquitin protein ligase (PARK2), the gene encoding parkin that is phosphorylated by PTEN-induced putative kinase 1 (PINK1) to participate in mitophagy, cause early onset PD. However, current parkin-KO mouse and pig models do not exhibit neurodegeneration. In the current study, we utilized CRISPR/Cas9 technology to establish parkin-deficient monkey models at different ages. We found that parkin deficiency leads to substantia nigra neurodegeneration in adult monkey brains and that parkin phosphorylation decreases with aging, primarily due to increased insolubility of parkin. Phosphorylated parkin is important for neuroprotection and the reduction of pS129-α-syn. Consistently, overexpression of WT parkin, but not a mutant form that cannot be phosphorylated by PINK1, reduced the accumulation of pS129-α-syn. These findings identify parkin phosphorylation as a key factor in PD pathogenesis and suggest it as a promising target for therapeutic interventions.

Authors

Rui Han, Qi Wang, Xin Xiong, Xiusheng Chen, Zhuchi Tu, Bang Li, Fei Zhang, Chunyu Chen, Mingtian Pan, Ting Xu, Laiqiang Chen, Zhifu Wang, Yanting Liu, Dajian He, Xiangyu Guo, Feng He, Peng Wu, Peng Yin, Yunbo Liu, Xiaoxin Yan, Shihua Li, Xiao-Jiang Li, Weili Yang

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Figure 6

Parkin deficiency increased pS129-α-syn accumulation.

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Parkin deficiency increased pS129-α-syn accumulation. (A) Increased pS12...
(A) Increased pS129-α-syn in parkin-deficient monkey (Park-4) as compared with a 3-year-old WT monkey. The ratios of pS129- α-syn to total α-syn from 2-4 independent Western blotting assays are presented (right panel). (B) Western blotting showing that targeting parkin via injection of AAV9-parkin gRNA/Cas9 into the striatum of an aged monkey (22 years old) increased the amount of insoluble pS129-α-syn. At least 3 independent experiments using monkey brain tissues from 1 WT and 1 parkin KD were performed, and representative images are presented. (C) Representative images of immunostaining of the SN of the young (9 years old) and old (22 years old) monkeys injected with AAV9-parkin gRNA/Cas9 revealing the increased staining of pS129-α-syn as compared with AAV9 control gRNA/Cas9 injection. (D) High-magnification micrographs showing cytoplasmic pS129-α-syn accumulation (arrow) and aggregates in a 22-year-old monkey. (E) Quantification of the numbers of pS129-α-syn aggregates in the SN of young (7 and 9 years old) and old (22 and 25 years old) monkeys. The injected SN regions were used to obtain the average numbers of pS129-α-syn aggregates (×40 or per 0.04 μm2) in multiple images. The number of aggregates was recorded and color coded to represent the specific monkey brain it originated from. (F) DAB staining of pS129-α-syn and immunofluorescent staining of NeuN allowed for detection of pS129-α-syn aggregates, which are present both intracellularly, within the cell body (arrows), and extracellularly, outside the cell body or in the neuronal processes that may not be identifiable by staining. Representative immunostaining images are from multiple technical replicates of at least 2 monkey brains.