AUTHOR=Zhu Lin-nan , Qiao Hong-hua , Chen Ling , Sun Le-ping , Hui Jia-liang , Lian Yong-ling , Xie Wei-bing , Ding Jiu-yang , Meng Yun-le , Zhu Bo-feng , Qiu Ping-ming 

TITLE=SUMOylation of Alpha-Synuclein Influences on Alpha-Synuclein Aggregation Induced by Methamphetamine

JOURNAL=Frontiers in Cellular Neuroscience

VOLUME=Volume 12 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2018.00262

DOI=10.3389/fncel.2018.00262

ISSN=1662-5102

ABSTRACT=Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH abusers are at high risk of neurodegenerative disorders, including Parkinson's disease (PD). Previous studies have demonstrated that METH causes α-syn aggregation in the laboratory animal and human. In this study, exposure to high METH doses increased the expression of alpha-synuclein (α-syn) and the small ubiquitin-related modifier 1 (SUMO-1) in vitro and in vivo. Therefore, we hypothesized that SUMOylation of α-syn is involved in high-dose METH-induced α-syn aggregation. We measured the levels of α-syn SUMOylation and these enzymes involved in the SUMOylation cycle in SH-SY5Y human neuroblastoma cells (SH-SY5Y cells), cultures of C57 BL/6 primary mouse neurons and brain tissues of mice exposed to METH. We also determined the effect of α-syn SUMOylation on α-syn aggregation after METH exposure by overexpressing the key enzyme of SUMOylation cycle or silencing SUMO-1 in vitro. Then, we make introduced mutations in major SUMOylation acceptor sites of α-syn by transfecting a lentivirus containing the sequence of WT α-syn or K96/102R α-syn into SH-SY5Y cells and injecting an adenovirus containing the sequence of WT α-syn or K96/102R α-syn into mouse striatum. Levels of the ubiquitin-proteasome system (UPS)-related makers ubiquitin (Ub) and UbE1, as well as the autophagy-lysosome pathway (ALP)-related markers LC3, P62 and lysosomal associated membrane protein 2A (LAMP2A), were also measured in SH-SY5Y cells transfected with lentivirus and mice injected with adenovirus. The results showed that METH exposure decreases the SUMOylation level of α-syn, although the protein expression levels of α-syn and SUMO-1 are increased. One possible cause is the reduction of UBC9 level. The increase in α-syn SUMOylation by UBC9 overexpression relieves METH-induced α-syn overexpression and aggregation, whereas the decrease in α-syn SUMOylation by SUMO-1 silencing exacerbates the same pathology. Furthermore, mutations in the major SUMOylation acceptor sites of α-syn aggravate α-syn overexpression and aggregation by impairing degradation through the UPS and the ALP in vitro and in vivo. These results suggest that SUMOylation of α-syn plays an essential role in METH-induced α-syn overexpression and aggregation at high doses and may be a suitable target for the treatment of neurodegenerative diseases.