Mutation of a Ubiquitin Carboxy Terminal Hydrolase L1 Lipid Binding Site Alleviates Cell Death, Axonal Injury, and Behavioral Deficits After Traumatic Brain Injury in Mice

• Published in: Neuroscience Vol. 475; pp. 127 - 136
• Main Authors: Mi, Zhiping, Liu, Hao, Rose, Marie E., Ma, Jie, Reay, Daniel P., Ma, Xiecheng, Henchir, Jeremy J., Dixon, C. Edward, Graham, Steven H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.11.2021
• Subjects: Animals; axonal injury; Axons - metabolism; Binding Sites; Brain Injuries, Traumatic; Cell Death; controlled cortical impact; deubiquitinating enzymes; Lipids; Mice; Mutation - genetics; protein ubiquitination; ubiquitin proteasome pathway; Ubiquitin Thiolesterase - genetics; Ubiquitin Thiolesterase - metabolism; APP; UCHL1; controlled cortical impact; axonal injury; UPP; protein ubiquitination; deubiquitinating enzymes; CCI; TBI; ubiquitin proteasome pathway; WT; CyPgs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2021.09.001

•Mutation of UCHL1’s C152 lipid binding site alleviated TBI-induced cell death.•C152 mutation decreased ubiquitinated proteins, activation of autophagy after TBI.•C152 mutation decreased white and gray matter injury after TBI.•C152 mutation improved motor and cognitive function after TBI. Ubiquitin carboxy terminal hydrolase L1 (UCHL1) is a protein highly expressed in neurons that may play important roles in the ubiquitin proteasome pathway (UPP) in neurons, axonal integrity, and motor function after traumatic brain injury (TBI). Binding of reactive lipid species to cysteine 152 of UCHL1 results in unfolding, aggregation, and inactivation of the enzyme. To test the role of this mechanism in TBI, mice bearing a cysteine to alanine mutation at site 152 (C152A mice) that renders UCHL1 resistant to inactivation by reactive lipids were subjected to the controlled cortical impact model (CCI) of TBI and compared to wild type (WT) controls. Alterations in protein ubiquitination and activation of autophagy pathway markers in traumatized brain were detected by immunoblotting. Cell death and axonal injury were determined by histological assessment and anti-amyloid precursor protein (APP) immunohistochemistry. Behavioral outcomes were determined using the beam balance and Morris water maze tests. C152A mice had reduced accumulation of ubiquitinated proteins, decreased activation of the autophagy markers Beclin-1 and LC3B, a decreased number of abnormal axons, decreased CA1 cell death, and improved motor and cognitive function compared to WT controls after CCI; no significant change in spared tissue volume was observed. These results suggest that binding of lipid substrates to cysteine 152 of UCHL1 is important in the pathogenesis of injury and recovery after TBI and may be a novel target for future therapeutic approaches.