Recessive loss of function of the neuronal ubiquitin hydrolase UCHL1 leads to early-onset progressive neurodegeneration.

Departments of Neurosurgery, Neurobiology, Genetics, Program on Neurogenetics, Diagnostic Radiology, Neurology, Molecular, Cellular, and Developmental Biology, and Pharmacology, and Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06510.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 01/2013; DOI: 10.1073/pnas.1222732110
Source: PubMed

ABSTRACT Ubiquitin C-terminal hydrolase-L1 (UCHL1), a neuron-specific de-ubiquitinating enzyme, is one of the most abundant proteins in the brain. We describe three siblings from a consanguineous union with a previously unreported early-onset progressive neurodegenerative syndrome featuring childhood onset blindness, cerebellar ataxia, nystagmus, dorsal column dysfuction, and spasticity with upper motor neuron dysfunction. Through homozygosity mapping of the affected individuals followed by whole-exome sequencing of the index case, we identified a previously undescribed homozygous missense mutation within the ubiquitin binding domain of UCHL1 (UCHL1(GLU7ALA)), shared by all affected subjects. As demonstrated by isothermal titration calorimetry, purified UCHL1(GLU7ALA), compared with WT, exhibited at least sevenfold reduced affinity for ubiquitin. In vitro, the mutation led to a near complete loss of UCHL1 hydrolase activity. The GLU7ALA variant is predicted to interfere with the substrate binding by restricting the proper positioning of the substrate for tunneling underneath the cross-over loop spanning the catalytic cleft of UCHL1. This interference with substrate binding, combined with near complete loss of hydrolase activity, resulted in a >100-fold reduction in the efficiency of UCHL1(GLU7ALA) relative to WT. These findings demonstrate a broad requirement of UCHL1 in the maintenance of the nervous system.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The reversible phosphorylation of proteins regulates most biological processes, while abnormal phosphorylation is a cause or consequence of many diseases including Alzheimer's disease (AD). One of the hallmarks of AD is the formation of neurofibrillary tangles (NFTs), which is composed of hyperphosphorylated tau proteins. Sodium selenate has been recently found to reduce tau hyperphosphorylation and NFTs formation, and to improve spatial learning and motor performance in AD mice. In the current study, the phosphoproteomics of N2aSW cells treated with selenate were investigated. To avoid missing low-abundance phosphoproteins, both the total proteins of cells and the phosphor-enriched proteins were extracted and subjected to the two-dimensional gel electrophoresis with Pro-Q diamond staining and then LC-MS/MS analysis. A total of 65 proteins were altered in phosphorylation level, of which 39 were up-regulated and 26 were down-regulated. All identified phosphoproteins were bioinformatically annotated according to their physiochemical features, subcellular location, and biological function. Most of these significantly changed phosphoproteins are involved in crucial neural processes such as protesome activity, oxidative stress, cysteine and methionine metabolism, and energy metabolism. Furthermore, decreases were found in homocysteine, phosphor-tau and amyloid β upon selenate treatment. Our results suggest that selenate may intervene in the pathological process of AD by altering the phosphorylation of some key proteins involved in oxidative stress, energy metabolism and protein degradation, thus play important roles in maintaining redox homeostasis, generating ATP, and clearing misfolded proteins and aggregates. The present paper provides some new clues to the mechanism of selenate in AD prevention.
    PLoS ONE 12/2014; 9(12):e113307. DOI:10.1371/journal.pone.0113307 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Deposition of amyloid β protein (Aβ) to form neuritic plaques in the brain is the pathological hallmark of Alzheimer's disease (AD). Aβ is produced by β- and γ-cleavages of amyloid β precursor protein (APP). Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a de-ubiquitinating enzyme that cleaves ubiquitin at its carboxyl terminal. Dysfunction of UCHL1 has been reported in neurodegenerative diseases. However, whether UCHL1 affects Aβ production and AD progression remains unknown. Here we report that UCHL1 interacts with APP and regulates Aβ production. UCHL1 increases free ubiquitin level and accelerates the lysosomal degradation of APP by promoting its ubiquitination. Furthermore, we demonstrate that overexpression of UCHL1 by intracranial injection of UCHL1-expressing rAAV reduces Aβ production, inhibits neuritic plaque formation and improves memory deficits in AD transgenic model mice. Our study suggests that UCHL1 may delay Alzheimer's progression by regulating APP degradation in a long-term fashion, and that overexpression of UCHL1 may be a safe and effective disease-modifying strategy to treat AD.
    Scientific Reports 12/2014; 4:7298. DOI:10.1038/srep07298 · 5.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have previously reported that presynaptic dysfunction and cognitive decline have been found in lipoprotein lipase (LPL) deficient mice, but the mechanism remains to be elucidated. Accumulating evidence supported that α-synuclein (α-syn) and ubiquitin C-terminal hydrolase L1 (UCHL1) are required for normal synaptic and cognitive function. In this study, we found that α-syn aggregated and the expression of UCHL1 decreased in the brain of LPL deficient mice. Reduction of UCHL1 was resulted from nuclear retention of DNA cytosine-5-methyltransferase 1 in LPL knockout mice. Reverse changes were found in cultured cells overexpressing LPL. Furthermore, deficiency of LPL increased ubiquitination of α-syn. These results indicated that aggregation of α-syn and reduction of UCHL1 expression in LPL deficient mice may affect synaptic function. Copyright © 2015. Published by Elsevier Ltd.
    Neuroscience 01/2015; 290. DOI:10.1016/j.neuroscience.2014.12.068 · 3.33 Impact Factor


Available from
Nov 21, 2014