SCIENCE@home

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

A. Saxena,Y. Banasavadi-Siddegowda,Yifei Fan,Sumit Bhattacharya,G. Roy,D. Giovannucci,R. Frizzell,Xiaodong Wang

Published 2012 in Journal of Biological Chemistry

ABSTRACT

Background: Hsp105 prevents protein aggregation, accelerates Hsc70 nucleotide exchange, and functionally relates to Hsp90. Results: Hsp105 facilitates CFTR quality control coincident with translation, enhances its post-translational folding, and stabilizes misfolded CFTR at cell periphery. Conclusion: Hsp105 is a versatile regulator in CFTR folding and quality control. Significance: Hsp105 plays distinct roles in CFTR folding from other Hsc70 nucleotide exchange factors. Heat shock protein 105/110-kDa (Hsp105/110), a member of the Hsp70 super family of molecular chaperones, serves as a nucleotide exchange factor for Hsc70, independently prevents the aggregation of misfolded proteins, and functionally relates to Hsp90. We investigated the roles of human Hsp105α, the constitutively expressed isoform, in the biogenesis and quality control of the cystic fibrosis transmembrane conductance regulator (CFTR). In the endoplasmic reticulum (ER), Hsp105 facilitates CFTR quality control at an early stage in its biosynthesis but promotes CFTR post-translational folding. Deletion of Phe-508 (ΔF508), the most prevalent mutation causing cystic fibrosis, interferes with de novo folding of CFTR, impairing its export from the ER and accelerating its clearance in the ER and post-Golgi compartments. We show that Hsp105 preferentially associates with and stabilizes ΔF508 CFTR at both levels. Introduction of the Hsp105 substrate binding domain potently increases the steady state level of ΔF508 CFTR by reducing its early-stage degradation. This in turn dramatically enhances ΔF508 CFTR cell surface functional expression in cystic fibrosis airway epithelial cells. Although other Hsc70 nucleotide exchange factors such as HspBP1 and BAG-2 inhibit CFTR post-translational degradation in the ER through cochaperone CHIP, Hsp105 has a primary role promoting CFTR quality control at an earlier stage. The Hsp105-mediated multilevel regulation of ΔF508 CFTR folding and quality control provides new opportunities to understand how chaperone machinery regulates the homeostasis and functional expression of misfolded proteins in the cell. Future studies in this direction will inform therapeutics development for cystic fibrosis and other protein misfolding diseases.

PUBLICATION RECORD

CITATION MAP

EXTRACTION MAP

CLAIMS

  • No claims are published for this paper.

CONCEPTS

  • No concepts are published for this paper.

REFERENCES

Showing 1-88 of 88 references · Page 1 of 1

CITED BY

Showing 1-54 of 54 citing papers · Page 1 of 1