# UBC9 mediates mitophagy to attenuate oxidative stress by regulating SUMOylation of PINK1 in the Parkinson’s disease progression

## TL;DR

UBC9 helps protect brain cells in Parkinson’s disease by modifying PINK1, reducing oxidative stress and improving cell survival.

## Contribution

UBC9 is shown to regulate PINK1 SUMOylation, promoting mitophagy and reducing neurodegeneration in Parkinson’s disease models.

## Key findings

- UBC9 overexpression reduces MPP+-induced cell death and oxidative stress in SH-SY5Y cells.
- UBC9 promotes PINK1 SUMOylation at K522 and K363, stabilizing PINK1 and enhancing mitophagy.
- UBC9 alleviates motor deficits and mitochondrial dysfunction in MPTP-treated mice via PINK1.

## Abstract

Parkinson’s disease (PD) is a neurodegenerative disease characterized by progressive loss of dopaminergic neurons. UBC9 is related to the formation of several cancers. Nevertheless, the function of UBC9 in PD and the potential mechanisms are vague.

MPP⁺-induced SH-SY5Y cells and MPTP-treated C57BL/6 mice were applied to induce PD models. Cell viability, proliferation and apoptosis were measured using CCK-8, EdU and Annexin V/PI staining, respectively. JC-1 staining and fluorescent probes DCFH-DA were employed to measure mitochondrial membrane potential and ROS production. The SOD, GSH and MDA content were determined by the commercially kits. SUMOylation of PINK1 were predicted by SUMOplot and verified by co-IP/Western blot. Mitophagy-related proteins, SUMO enzymes, and TH were analyzed by qRT-PCR/Western blot. LC3 expression was detected via immunofluorescence staining. Transmission electron microscopy was performed to detect autophagy. MPTP-induced brain injury was evaluated using Nissl staining, IHC and TUNEL assay. Motor function was observed via open field test and pole test.

PINK1 and UBC9 were low-expressed in MPP+-induced SH-SY5Y cells. UBC9 mediated PINK1 SUMOylation. UBC9 overexpression promoted cell viability and reduced cells apoptosis in MPP+-stimulated SH-SY5Y cells, which was reversed after PINK1 silence or CsA treatment. Moreover, UBC9 overexpression counteracted MPP+-induced mitophagy, and oxidative stress. However, these findings were reversed by CsA or PINK1 silencing. PINK1 bound SUMO1 at the K522, K363 and K193 sites, further regulating cells viability and apoptosis. In MPTP-treated mice, UBC9 overexpression alleviated mitochondrial dysfunction and motor deficits via PINK1 SUMOylation.

UBC9 mediated mitophagy to attenuate MPP+/MPTP-induced neurotoxicity and oxidative stress by regulating PINK1 SUMOylation, suggesting that UBC9 may play a preventive role in PD progression.

UBC9 enhanced PINK1 stability by promoting SUMOylation of PINK1 at the K522R/K363R position.UBC9 regulated MPP+-induced SH-SY5Y cells proliferation and apoptosis via PINK1.UBC9 alleviated MPTP-induced motor dysfunction and oxidative stress via PINK1-mediated mitophagy.

UBC9 enhanced PINK1 stability by promoting SUMOylation of PINK1 at the K522R/K363R position.

UBC9 regulated MPP+-induced SH-SY5Y cells proliferation and apoptosis via PINK1.

UBC9 alleviated MPTP-induced motor dysfunction and oxidative stress via PINK1-mediated mitophagy.