title: The ubiquitin C-terminal hydrolase L1 (UCH-L1) C terminus plays a key role in protein stability, but its farnesylation is not required for membrane association in primary neurons.
abstract: Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a deubiquitinating enzyme that is highly expressed in neurons. A possible role for UCH-L1 in neurodegeneration has been highlighted because of its presence in Lewy bodies associated with Parkinson disease and neurofibrillary tangles observed in Alzheimer disease. UCH-L1 exists in two forms in neurons, a soluble cytoplasmic form (UCH-L1(C)) and a membrane-associated form (UCH-L1(M)). Alzheimer brains show reduced levels of soluble UCH-L1(C) correlating with the formation of UCH-L1-immunoreactive tau tangles, whereas UCH-L1(M) has been implicated in α-synuclein dysfunction. Given these reports of divergent roles, we investigated the properties of UCH-L1 membrane association. Surprisingly, our results indicate that UCH-L1 does not partition to the membrane in the cultured cell lines we tested. Furthermore, in primary cultured neurons, a proportion of UCH-L1(M) does partition to the membrane, but, contrary to a previous report, this does not require farnesylation. Deletion of the four C-terminal residues caused the loss of protein solubility, abrogation of substrate binding, increased cell death, and an abnormal intracellular distribution, consistent with protein dysfunction and aggregation. These data indicate that UCH-L1 is differently processed in neurons compared with clonal cell lines and that farnesylation does not account for the membrane association in neurons.
authors.affiliation: From the School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Bishop
authors.affiliation: From the School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
authors.forename: Philip
authors.initials: P
authors.lastname: Rubin
authors.affiliation: From the School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Thomson
authors.affiliation: From the School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
authors.forename: Dan
authors.initials: D
authors.lastname: Rocca
authors.affiliation: From the School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom J.M.Henley@bristol.ac.uk.
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Henley
mesh_terms: D000818:Animals; D017209:Apoptosis; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D057809:HEK293 Cells; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D061251:Primary Cell Culture; D017368:Protein Prenylation; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D043222:Ubiquitin Thiolesterase / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: C489034:UCHL1 protein, rat; D043222:Ubiquitin Thiolesterase
keywords: Membrane Protein; Neurobiology; Posttranslational Modification (PTM); Protein Misfolding; Ubiquitination