A prominent role of PDIA6 in processing of misfolded proinsulin
Autor: | Anthony W. Purcell, Nadine L. Dudek, Philippa M. Saunders, Jon E. Mangum, Sheena Wee, Ralf B. Schittenhelm, Dhana G. Gorasia, Rochelle Ayala Perez, Helena Safavi-Hemami, Michael J. Hubbard |
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Rok vydání: | 2016 |
Předmět: |
0301 basic medicine
Protein Folding endocrine system endocrine system diseases Protein Disulfide-Isomerases Biophysics Biology Endoplasmic-reticulum-associated protein degradation digestive system Biochemistry Cell Line Analytical Chemistry Mice 03 medical and health sciences Calnexin Animals Glucose homeostasis Protein precursor Molecular Biology Proinsulin nutritional and metabolic diseases Co-chaperone 030104 developmental biology Foldase Mutagenesis Site-Directed Protein folding hormones hormone substitutes and hormone antagonists |
Zdroj: | Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 1864:715-723 |
ISSN: | 1570-9639 |
Popis: | Despite its critical role in maintaining glucose homeostasis, surprisingly little is known about proinsulin folding in the endoplasmic reticulum. In this study we aimed to understand the chaperones involved in the maturation and degradation of proinsulin. We generated pancreatic beta cell lines expressing FLAG-tagged proinsulin. Several chaperones (including BiP, PDIA6, calnexin, calreticulin, GRP170, Erdj3 and ribophorin II) co-immunoprecipitated with proinsulin suggesting a role for these proteins in folding. To investigate the chaperones responsible for targeting misfolded proinsulin for degradation, we also created a beta cell line expressing FLAG-tagged proinsulin carrying the Akita mutation (Cys96Tyr). All chaperones found to be associated with wild type proinsulin also co-immunoprecipitated with Akita proinsulin. However, one additional protein, namely P58(IPK), specifically precipitated with Akita proinsulin and approximately ten fold more PDIA6, but not other PDI family members, was bound to Akita proinsulin. The latter suggests that PDIA6 may act as a key reductase and target misfolded proinsulin to the ER-degradation pathway. The preferential association of PDIA6 to Akita proinsulin was also confirmed in another beta cell line (βTC-6). Furthermore, for the first time, a physiologically relevant substrate for PDIA6 has been evidenced. Thus, this study has identified several chaperones/foldases that associated with wild type proinsulin and has also provided a comprehensive interactome for Akita misfolded proinsulin. |
Databáze: | OpenAIRE |
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