Ubiquitin C-terminal hydrolase-L1 protects cystic fibrosis transmembrane conductance regulator from early stages of proteasomal degradation

Mark J. Henderson, Neeraj Vij, Pamela L. Zeitlin

Research output: Contribution to journalArticle

Abstract

ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) degradation involves ubiquitin modification and efficient proteasomal targeting of the nascent misfolded protein. We show that a deubiquitinating enzyme, ubiquitin C-terminal hydrolase-L1 (UCH-L1), is highly expressed in cystic fibrosis (CF) airway epithelial cells in vitro and in vivo. We hypothesized that the elevation in UCH-L1 in CF cells represents a cellular adaptation to counterbalance excessive proteasomal degradation. The bronchial epithelial cell lines IB3-1 (CF, high UCH-L1 expression) and S9 (non-CF, low UCH-L1 expression) were transiently transfected with wild type (WT) or ΔF508 CFTR, WTUCH-L1 or small interfering RNA-UCH-L1, and a variety of ubiquitin mutants. We observed a positive correlation between UCH-L1 expression and steady state levels of WT- or ΔF508-CFTR, and this stabilizing effect was confined to the early stages of CFTR synthesis. Immunolocalization of UCH-L1 by confocal microscopy revealed a partial co-localization with a ribosomal subunit and the endoplasmic reticulum. The UCH-L1-associated increase in CFTR levels was correlated with an increase in ubiquitinated CFTR (CFTR-Ub). Co-transfection with mutant ubiquitins and treatment with proteasome inhibitors suggested that UCH-L1 was reducing the proteasomal targeting of CFTR during synthesis by shortening conjugated polyubiquitin chains. Although not sufficient by itself to rescue mutant CFTR therapeutically, the elevation of UCH-L1 and its effect on CFTR processing provides insight into its potential roles in CF and other diseases.

Original languageEnglish (US)
Pages (from-to)11314-11325
Number of pages12
JournalJournal of Biological Chemistry
Volume285
Issue number15
DOIs
StatePublished - Apr 9 2010

Fingerprint

Ubiquitin Thiolesterase
Cystic Fibrosis Transmembrane Conductance Regulator
Degradation
Cystic Fibrosis
Ubiquitin
Epithelial Cells
Ubiquitins
Polyubiquitin
Ribosome Subunits
Proteasome Inhibitors
Confocal microscopy
Confocal Microscopy
Endoplasmic Reticulum
Small Interfering RNA
Transfection

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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Ubiquitin C-terminal hydrolase-L1 protects cystic fibrosis transmembrane conductance regulator from early stages of proteasomal degradation. / Henderson, Mark J.; Vij, Neeraj; Zeitlin, Pamela L.

In: Journal of Biological Chemistry, Vol. 285, No. 15, 09.04.2010, p. 11314-11325.

Research output: Contribution to journalArticle

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