Document Detail


Cysteine string protein monitors late steps in cystic fibrosis transmembrane conductance regulator biogenesis.
MedLine Citation:
PMID:  16469739     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We examined the role of the cysteine string protein (Csp) in cystic fibrosis transmembrane conductance regulator (CFTR) biogenesis in relation to another J-domain protein, Hdj-2, a recognized CFTR cochaperone. Increased expression of Csp produced a dose-dependent reduction in mature (band C) CFTR and an increase in immature (band B) CFTR. Exogenous expression of Hdj-2 also increased CFTR band B, but unlike Csp, Hdj-2 increased band C as well. The Csp-induced block of CFTR maturation required Hsp70, because a J-domain mutant (H43Q) that interferes with the ability of Csp to stimulate Hsp70 ATPase activity relieved the Csp-induced block of CFTR maturation. Nevertheless, Csp H43Q still increased immature CFTR. Csp-induced band B CFTR was found adjacent to the nucleus, co-localizing with calnexin, and it remained detergent-soluble. These data indicate that Csp did not block CFTR maturation by promoting the aggregation or degradation of immature CFTR. Csp knockdown by RNA interference produced a 5-fold increase in mature CFTR and augmented cAMP-stimulated CFTR currents. Thus, the production of mature CFTR is inversely related to the expression level of Csp. Both Csp and Hdj-2 associated with the CFTR R-domain in vitro, and Hdj-2 binding was displaced by Csp, suggesting common interaction sites. Combined expression of Csp and Hdj-2 mimicked the effect of Csp alone, a block of CFTR maturation. But together, Csp and Hdj-2 produced additive increases in CFTR band B, and this did not depend on their interactions with Hsp70, consistent with direct chaperone actions of these proteins. Like Hdj-2, Csp reduced the aggregation of NBD1 in vitro in the absence of Hsp70. Our data suggest that both Csp and Hdj-2 facilitate the biosynthesis of immature CFTR, acting as direct CFTR chaperones, but in addition, Csp is positioned later in the CFTR biogenesis cascade where it regulates the production of mature CFTR by limiting its exit from the endoplasmic reticulum.
Authors:
Hui Zhang; Bela Z Schmidt; Fei Sun; Steven B Condliffe; Michael B Butterworth; Robert T Youker; Jeffrey L Brodsky; Meir Aridor; Raymond A Frizzell
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2006-02-09
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  281     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-04-17     Completed Date:  2006-06-13     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11312-21     Citation Subset:  IM    
Affiliation:
Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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MeSH Terms
Descriptor/Qualifier:
Actins / metabolism
Anions
Biological Transport
Calnexin / metabolism,  pharmacology
Cell Line
Cell Membrane / metabolism
Cyclic AMP / metabolism
Cystic Fibrosis Transmembrane Conductance Regulator / biosynthesis*,  genetics*
Detergents / metabolism,  pharmacology
Dose-Response Relationship, Drug
Endoplasmic Reticulum / metabolism
HSP40 Heat-Shock Proteins / chemistry*,  metabolism
HSP70 Heat-Shock Proteins / chemistry,  metabolism
Humans
Immunoblotting
Immunoprecipitation
Membrane Proteins / chemistry*
Microscopy, Fluorescence
Molecular Chaperones / metabolism
Mutation
Oocytes / metabolism
Protein Binding
Protein Folding
Protein Structure, Tertiary
RNA / metabolism
RNA Interference
Time Factors
Transfection
Grant Support
ID/Acronym/Agency:
DK60835/DK/NIDDK NIH HHS; DK62318/DK/NIDDK NIH HHS; DK68196/DK/NIDDK NIH HHS; DK72506/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Actins; 0/Anions; 0/CFTR protein, human; 0/DNAJA1 protein, human; 0/Detergents; 0/HSP40 Heat-Shock Proteins; 0/HSP70 Heat-Shock Proteins; 0/Membrane Proteins; 0/Molecular Chaperones; 0/cysteine string protein; 126880-72-6/Cystic Fibrosis Transmembrane Conductance Regulator; 139873-08-8/Calnexin; 60-92-4/Cyclic AMP; 63231-63-0/RNA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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