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 3

Selective neurodegeneration in the SN of monkeys targeted by AAV9-parkin gRNA/Cas9.

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Selective neurodegeneration in the SN of monkeys targeted by AAV9-parkin...
(A) Immunostaining of the 6-year-old monkey prefrontal cortex and SN injected with control AAV9 gRNA or AAV9-parkin gRNA/Cas9. Antibodies to NeuN, PV, and ChAT were used to identify neurons while anti-RFP was used to show viral infection. Representative images of multiple technical replicates from 3 animals. (B) Superplot analysis of the number of cortical NeuN-, SN PV–, and ChAT-positive neurons in control gRNA/Cas9– and parkin gRNA/Cas9–injected monkeys, with each group comprising 3 monkeys. For each image captured at ×20 magnification, the number of NeuN-, PV-, or ChAT-positive cells was recorded and color coded to represent the specific monkey brain it originated from. The average count of these cells in each animal was used for paired 2-tailed t test to obtain P values. Data are represented as means ± SEM (n = 3 each group). (C) Western blotting analysis of neuronal and mitochondria proteins in the control and parkin KD SN of 6-year-old monkeys. (D) Ratios of parkin, S65-parkin, NeuN, TH, and SNAP25 to vinculin on Western blots from 2 independent experiments. (E) EM indicates that targeting parkin by AAV9 parkin gRNA/Cas9 resulted in degenerated neurons (upper panels) and axons (lower panels) in the SN as compared with the AAV control gRNA SN in a 6-year-old monkey. Representative images of multiple technical replicates from 1 control gRNA– and 1 parkin gRNA/Cas9-injected monkey. (F) Representative 18F-DOPA PET/CT imaging shows the reduction of dopamine in the striatum 2 months after injection of AAV parkin gRNA/Cas9 into the SN at one side in an adult monkey at age 8 years. The other side SN of the same monkey was injected with control gRNA/Cas9.