title: UCH-L1 Inhibition Decreases the Microtubule-Binding Function of Tau Protein.
abstract: Ubiquitin C-terminal hydrolase L1 (UCH-L1) is critical for protein degradation and free ubiquitin recycling. In Alzheimer's disease brains, UCH-L1 is negatively related to neurofibrillary tangles whose major component is hyperphosphorylated tau protein, but the direct action of UCH-L1 on tau has not been reported. In the current study, mouse neuroblastoma Neuro2a (N2a) cells were treated by the different concentrations of UCH-L1 inhibitor LDN (2.5, 5 and 10 μM) to inhibit the hydrolase activity of UCH-L1. In addition, we also used UCH-L1 siRNA to treat the HEK293/tau441 cells to decrease the expression of UCH-L1. After LDN and UCH-L1 siRNA treatment, we used immunofluorescence, immunoprecipitation, and tau-microtubule binding assay to measure the microtubule-binding ability and post-translational modifications of tau protein. All the results presented that both inhibition of the activity and expression of UCH-L1 induced the decreased microtubule-binding ability and increased phosphorylation of tau protein. Abnormal aggregation and ubiquitination of tau protein was also observed after UCH-L1 inhibition. The above results suggested that aggregation of tau protein might be devoted to the abnormal post-translational modifications of tau protein. Our study first indicates that dysfunction of UCH-L1 most likely affected normal biological function of tau protein through decreasing degradation of ubiquitinated and hyperphosphorylated tau.
authors.forename: Min
authors.initials: M
authors.lastname: Xie
authors.forename: Yun
authors.initials: Y
authors.lastname: Han
authors.forename: Quntao
authors.initials: Q
authors.lastname: Yu
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Shaohui
authors.initials: S
authors.lastname: Wang
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Liao
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D008870:Microtubules / Q000378:metabolism*; D009447:Neuroblastoma / Q000473:pathology; D010091:Oximes / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D043222:Ubiquitin Thiolesterase / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects; D016875:tau Proteins / Q000378:metabolism*
chemical_list: D007211:Indoles; C525086:LDN 57444; D010091:Oximes; D034741:RNA, Small Interfering; C507533:Ubiquitin carboxyl-Terminal Hydrolase L-1, human; D016875:tau Proteins; D043222:Ubiquitin Thiolesterase
keywords: Aggregation; UCH-L1 inhibition; microtubule-binding function; post-translational modification; tau protein