A Foldable CFTRΔF508 Biogenic Intermediate Accumulates upon Inhibition of the Hsc70-CHIP E3 Ubiquitin Ligase
CFTRΔF508 exhibits a correctable protein-folding defect that leads to its misfolding and premature degradation, which is the cause of cystic fibrosis (CF). Herein we report on the characterization of the CFTRΔF508 biogenic intermediate that is selected for proteasomal degradation and identification...
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Published in | The Journal of cell biology Vol. 167; no. 6; pp. 1075 - 1085 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Rockefeller University Press
20.12.2004
The Rockefeller University Press |
Subjects | |
Online Access | Get full text |
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Summary: | CFTRΔF508 exhibits a correctable protein-folding defect that leads to its misfolding and premature degradation, which is the cause of cystic fibrosis (CF). Herein we report on the characterization of the CFTRΔF508 biogenic intermediate that is selected for proteasomal degradation and identification of cellular components that polyubiquitinate CFTRΔF508. Nonubiquitinated CFTRΔF508 accumulates in a kinetically trapped, but folding competent conformation, that is maintained in a soluble state by cytosolic Hsc70. Ubiquitination of Hsc70-bound CFTRΔF508 requires CHIP, a U box containing cytosolic cochaperone. CHIP is demonstrated to function as a scaffold that nucleates the formation of a multi-subunit E3 ubiquitin ligase whose reconstituted activity toward CFTR is dependent upon Hdj2, Hsc70, and the E2 UbcH5a. Inactivation of the Hsc70-CHIP E3 leads CFTRΔF508 to accumulate in a nonaggregated state, which upon lowering of cell growth temperatures, can fold and reach the cell surface. Inhibition of CFTRΔF508 ubiquitination can increase its cell surface expression and may provide an approach to treat CF. |
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Bibliography: | Abbreviations used in this paper: ApoB48, apolipoprotein B48; BFA, brefeldin A; CF, cystic fibrosis; ERQC, endoplasmic reticulum quality control system; NBD, nucleotide binding domain; TCRα, T cell receptor α subunit; TPR, tetratricopeptide repeat motifs. Correspondence to D.M. Cyr: dmcyr@med.unc.edu |
ISSN: | 0021-9525 1540-8140 |
DOI: | 10.1083/jcb.200410065 |