Chronic physical restraint stress increases oxidative stress in the brain, and dysregulation of oxidative stress can be one of the causes of major depressive disorder. To understand the underlying mechanisms, we undertook a systematic proteomic analysis of hippocampus in a chronic restraint stress mouse model of depression. Combining two-dimensional gel electrophoresis (2D-PAGE) for protein separation with nanoUPLC-ESI-q-TOF tandem mass spectrometry, we identified sixty-three protein spots that changed in the hippocampus of mice subjected to chronic restraint stress. We identified and classified the proteins that changed after chronic stress, into three groups respectively functioning in neural plasticity, metabolic processes and protein aggregation. Of these, 5 proteins including ubiquitin C-terminal hydrolase L1 (UCH-L1), dihydropyrimidinase-related protein 2 (DPYL2), haloacid dehalogenase-like hydrolase domain-containing protein 2 (HDHD2), actin-related protein 2/3 complex subunit 5 (ARPC5) and peroxiredoxin-2 (PRDX2), showed pI shifts attributable to post-translational modifications. Further analysis indicated that UCH-L1 underwent differential oxidations of 2 cysteine residues following chronic stress. We investigated whether the oxidized form of UCH-L1 plays a role in stressed hippocampus, by comparing the effects of UCH-L1 and its Cys mutants on hippocampal cell line HT-22 in response to oxidative stress. This study demonstrated that UCH-L1 wild-type and cysteine to aspartic acid mutants, but not its cysteine to serine mutants, afforded neuroprotective effects against oxidative stress; there were no discernible differences between wild-type UCH-L1 and its mutants in the absence of oxidative stress. These findings suggest that cysteine oxidative modifications of UCH-L1 in the hippocampus play key roles in neuroprotection against oxidative stress caused in major depressive disorder.
Bibliographical noteFunding Information:
* This study was supported by the Global Research Lab Program (No. 2012K1A1A2045441) and the Brain Research Program (2015M3C7A1028373) of the National Research Foundation of Korea. JE Choi was supported by Brain Korea 21 Plus (BK21 Plus) Project. □S This article contains supplemental Figures and Tables. ¶ To whom correspondence should be addressed: College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul, Korea 03760. Tel.: +82-2-3277-3038; Fax: +82-2-3277-3760; E-mail: email@example.com.
HT-22 cells were kindly provided by Professor HJ Kim at Ewha Womans University. IHC result was obtained with the help of Dr. XH Jin and Dr. J Jung in Professor K Lee’s lab (Ewha Womans University). Dr. Peter R. Baker (University of California, San Francisco) kindly helped us upload raw mass spectrometry data into MS-Viewer. We also acknowledge the help of the PRIDE team in uploading raw data via ProteomeXchange. This study was supported by the Global Research Lab Program (No. 2012K1A1A2045441) and the Brain Research Program (2015M3C7A1028373) of the National Research Foundation of Korea. JE Choi was supported by Brain Korea 21 Plus (BK21 Plus) Project.
© 2018 Choi et al.