Human Heat Shock Protein 105/110 kDa (Hsp105/110) Regulates Biogenesis and Quality Control of Misfolded Cystic Fibrosis Transmembrane Conductance Regulator at Multiple Levels

The CFTR (cystic fibrosis transmembrane conductance regulator) gene, defective in cystic fibrosis, codes for a polytopic apical membrane protein functioning as a chloride channel. Wild-type (wt) CFTR matures inefficiently and CFTR with a deletion of Phe-508 (F508del), the most frequent mutation, is substantially retained as a core-glycosylated intermediate in the endoplasmic reticulum (ER), probably due to misfolding that is recognized by the cellular quality control machinery involving molecular chaperones. Here, we overexpressed the heat-shock protein (Hsp) 70 chaperone in vivo and observed no changes in degradation rate of the core-glycosylated form, nor in the efficiency of its conversion into the fully glycosylated form, for either wt- or F508del-CFTR, contrary to previous in vitro studies on the affect of heat-shock cognate (Hsc) 70 on part of the first nucleotide-binding domain of CFTR. Co-transfection of Hsp70 with its co-chaperone human DnaJ homologue (Hdj)-1/Hsp40, however, stabilizes the immature form of wt-CFTR, but not of F508del-CFTR, suggesting that these chaperones act on a wt-specific conformation. As the efficiency of conversion into the fully glycosylated form is not increased under Hsp70/Hdj-1 overexpression, the lack of these two chaperones does not seem to be critical for CFTR maturation and ER retention. The effects of 4-phenylbutyrate and deoxyspergualin, described previously to interfere with Hsp70 binding, were also tested upon CFTR degradation and processing. The sole effect observed was destabilization of F508del-CFTR.

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Faculty Opinions recommendation of Sequential quality-control checkpoints triage misfolded cystic fibrosis transmembrane conductance regulator.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1046329.496274 ◽

2006 ◽

Author(s):

Davis Ng

Keyword(s):

Cystic Fibrosis ◽

Quality Control ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Cystic Fibrosis Transmembrane

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The Cochaperone HspBP1 Inhibits the CHIP Ubiquitin Ligase and Stimulates the Maturation of the Cystic Fibrosis Transmembrane Conductance Regulator

Molecular Biology of the Cell ◽

10.1091/mbc.e04-04-0293 ◽

2004 ◽

Vol 15 (9) ◽

pp. 4003-4010 ◽

Cited By ~ 116

Author(s):

Simon Alberti ◽

Karsten Böhse ◽

Verena Arndt ◽

Anton Schmitz ◽

Jörg Höhfeld

Keyword(s):

Cystic Fibrosis ◽

Quality Control ◽

Ubiquitin Ligase ◽

Molecular Chaperones ◽

Protein Quality ◽

Regulatory Mechanism ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Ubiquitin Ligase Activity ◽

Cystic Fibrosis Transmembrane

The CHIP ubiquitin ligase turns molecular chaperones into protein degradation factors. CHIP associates with the chaperones Hsc70 and Hsp90 during the regulation of signaling pathways and during protein quality control, and directs chaperone-bound clients to the proteasome for degradation. Obviously, this destructive activity should be carefully controlled. Here, we identify the cochaperone HspBP1 as an inhibitor of CHIP. HspBP1 attenuates the ubiquitin ligase activity of CHIP when complexed with Hsc70. As a consequence, HspBP1 interferes with the CHIP-induced degradation of immature forms of the cystic fibrosis transmembrane conductance regulator (CFTR) and stimulates CFTR maturation. Our data reveal a novel regulatory mechanism that determines folding and degradation activities of molecular chaperones.

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Sequential Quality-Control Checkpoints Triage Misfolded Cystic Fibrosis Transmembrane Conductance Regulator

Cell ◽

10.1016/j.cell.2006.06.041 ◽

2006 ◽

Vol 126 (3) ◽

pp. 571-582 ◽

Cited By ~ 300

Author(s):

J. Michael Younger ◽

Liling Chen ◽

Hong-Yu Ren ◽

Meredith F.N. Rosser ◽

Emma L. Turnbull ◽

...

Keyword(s):

Cystic Fibrosis ◽

Quality Control ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Cystic Fibrosis Transmembrane

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Stress activated MAPK influence the quality control of misfolded cystic fibrosis transmembrane conductance regulator.

The FASEB Journal ◽

10.1096/fasebj.27.1_supplement.lb126 ◽

2013 ◽

Vol 27 (S1) ◽

Author(s):

Ramanath Narayana Hegde ◽

Seetharaman Parashuraman ◽

Francesco Iorio ◽

Diego Di Bernardo ◽

Alberto Luini

Keyword(s):

Cystic Fibrosis ◽

Quality Control ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Cystic Fibrosis Transmembrane

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Small heat shock proteins target mutant cystic fibrosis transmembrane conductance regulator for degradation via a small ubiquitin-like modifier–dependent pathway

Molecular Biology of the Cell ◽

10.1091/mbc.e12-09-0678 ◽

2013 ◽

Vol 24 (2) ◽

pp. 74-84 ◽

Cited By ~ 56

Author(s):

Annette Ahner ◽

Xiaoyan Gong ◽

Bela Z. Schmidt ◽

Kathryn W. Peters ◽

Wael M. Rabeh ◽

...

Keyword(s):

Cystic Fibrosis ◽

Heat Shock ◽

Heat Shock Proteins ◽

Airway Epithelial Cells ◽

Small Heat Shock Proteins ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Shock Proteins ◽

The Impact ◽

Cystic Fibrosis Transmembrane

Small heat shock proteins (sHsps) bind destabilized proteins during cell stress and disease, but their physiological functions are less clear. We evaluated the impact of Hsp27, an sHsp expressed in airway epithelial cells, on the common protein misfolding mutant that is responsible for most cystic fibrosis. F508del cystic fibrosis transmembrane conductance regulator (CFTR), a well-studied protein that is subject to cytosolic quality control, selectively associated with Hsp27, whose overexpression preferentially targeted mutant CFTR to proteasomal degradation. Hsp27 interacted physically with Ubc9, the small ubiquitin-like modifier (SUMO) E2 conjugating enzyme, implying that F508del SUMOylation leads to its sHsp-mediated degradation. Enhancing or disabling the SUMO pathway increased or blocked Hsp27’s ability to degrade mutant CFTR. Hsp27 promoted selective SUMOylation of F508del NBD1 in vitro and of full-length F508del CFTR in vivo, which preferred endogenous SUMO-2/3 paralogues that form poly-chains. The SUMO-targeted ubiquitin ligase (STUbL) RNF4 recognizes poly-SUMO chains to facilitate nuclear protein degradation. RNF4 overexpression elicited F508del degradation, whereas Hsp27 knockdown blocked RNF4’s impact on mutant CFTR. Similarly, the ability of Hsp27 to degrade F508del CFTR was lost during overexpression of dominant-negative RNF4. These findings link sHsp-mediated F508del CFTR degradation to its SUMOylation and to STUbL-mediated targeting to the ubiquitin–proteasome system and thereby implicate this pathway in the disposal of an integral membrane protein.

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Cystic Fibrosis Transmembrane Conductance Regulator Degradation Depends on the Lectins Htm1p/EDEM and the Cdc48 Protein Complex in Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.e04-01-0024 ◽

2004 ◽

Vol 15 (9) ◽

pp. 4125-4135 ◽

Cited By ~ 73

Author(s):

Andreas Gnann ◽

John R. Riordan ◽

Dieter H. Wolf

Keyword(s):

Cystic Fibrosis ◽

Quality Control ◽

Protein Quality ◽

Hereditary Disease ◽

Yeast Cells ◽

Common Mutation ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Yeast Saccharomyces Cerevisiae ◽

Cystic Fibrosis Transmembrane

Cystic fibrosis is the most widespread hereditary disease among the white population caused by different mutations of the apical membrane ATP-binding cassette transporter cystic fibrosis transmembrane conductance regulator (CFTR). Its most common mutation, ΔF508, leads to nearly complete degradation via endoplasmic reticulum-associated degradation (ERAD). Elucidation of the quality control and degradation mechanisms might give rise to new therapeutic approaches to cure this disease. In the yeast Saccharomyces cerevisiae, a variety of components of the protein quality control and degradation system have been identified. Nearly all of these components share homology with mammalian counterparts. We therefore used yeast mutants defective in the ERAD system to identify new components that are involved in human CFTR quality control and degradation. We show the role of the lectin Htm1p in the degradation process of CFTR. Complementation of the HTM1 deficiency in yeast cells by the mammalian orthologue EDEM underlines the necessity of this lectin for CFTR degradation and highlights the similarity of quality control and ERAD in yeast and mammals. Furthermore, degradation of CFTR requires the ubiquitin protein ligases Der3p/Hrd1p and Doa10p as well as the cytosolic trimeric Cdc48p-Ufd1p-Npl4p complex. These proteins also were found to be necessary for ERAD of a mutated yeast “relative” of CFTR, Pdr5*p.

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Small Hsps as Therapeutic Targets of Cystic Fibrosis Transmembrane Conductance Regulator Protein

International Journal of Molecular Sciences ◽

10.3390/ijms22084252 ◽

2021 ◽

Vol 22 (8) ◽

pp. 4252

Author(s):

Stéphanie Simon ◽

Abdel Aissat ◽

Fanny Degrugillier ◽

Benjamin Simonneau ◽

Pascale Fanen ◽

...

Keyword(s):

Cystic Fibrosis ◽

Heat Shock ◽

Heat Shock Proteins ◽

Small Heat Shock Proteins ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Regulator Protein ◽

Shock Proteins ◽

Cystic Fibrosis Transmembrane

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal and pathological cells. Here, we have reviewed the role played by HspB1, HspB4 and HspB5 in the context of Cystic Fibrosis (CF), a severe monogenic autosomal recessive disease linked to mutations in Cystic Fibrosis Transmembrane conductance Regulator protein (CFTR) some of which trigger its misfolding and rapid degradation, particularly the most frequent one, F508del-CFTR. While HspB1 and HspB4 favor the degradation of CFTR mutants, HspB5 and particularly one of its phosphorylated forms positively enhance the transport at the plasma membrane, stability and function of the CFTR mutant. Moreover, HspB5 molecules stimulate the cellular efficiency of currently used CF therapeutic molecules. Different strategies are suggested to modulate the level of expression or the activity of these small heat shock proteins in view of potential in vivo therapeutic approaches. We then conclude with other small heat shock proteins that should be tested or further studied to improve our knowledge of CFTR processing.

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