The chaperone proteins HSP70, HSP40/DnaJ and GRP78/BiP suppress misfolding and formation of β-sheet-containing aggregates by human amylin: a potential role for defective chaperone biology in Type 2 diabetes
| Autor: | Garth J. S. Cooper, Thomas Brittain, Kerry M. Loomes, Vita Chien, Jacqueline F. Aitken, Shaoping Zhang, Christina M. Buchanan, Anthony J. R. Hickey |
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| Rok vydání: | 2010 |
| Předmět: |
Protein Folding
endocrine system Immunoprecipitation Blotting Western Amylin Peptide macromolecular substances Plasma protein binding Biochemistry Protein Structure Secondary Protein structure Animals Humans HSP70 Heat-Shock Proteins Endoplasmic Reticulum Chaperone BiP Molecular Biology Heat-Shock Proteins chemistry.chemical_classification biology Circular Dichroism Cell Biology HSP40 Heat-Shock Proteins Islet Amyloid Polypeptide Rats Solutions Diabetes Mellitus Type 2 chemistry Chaperone (protein) biology.protein Chaperone binding Protein folding Molecular Chaperones Protein Binding |
| Zdroj: | Biochemical Journal. 432:113-121 |
| ISSN: | 1470-8728 0264-6021 |
| DOI: | 10.1042/bj20100434 |
| Popis: | Misfolding of the islet β-cell peptide hA (human amylin) into β-sheet-containing oligomers is linked to β-cell apoptosis and the pathogenesis of T2DM (Type 2 diabetes mellitus). In the present study, we have investigated the possible effects on hA misfolding of the chaperones HSP (heat-shock protein) 70, GRP78/BiP (glucose-regulated protein of 78 kDa/immunoglobulin heavy-chain-binding protein) and HSP40/DnaJ. We demonstrate that hA underwent spontaneous time-dependent β-sheet formation and aggregation by thioflavin-T fluorescence in solution, whereas rA (rat amylin) did not. HSP70, GRP78/BiP and HSP40/DnaJ each independently suppressed hA misfolding. Maximal molar protein/hA ratios at which chaperone activity was detected were 1:200 (HSP70, HSP40/DnaJ and GRP78/BiP). By contrast, none of the chaperones modified the secondary structure of rA. hA, but not rA, was co-precipitated independently with HSP70 and GRP78/BiP by anti-amylin antibodies. As these effects occur at molar ratios consistent with chaperone binding to relatively rare misfolded hA species, we conclude that HSP70 and GRP78/BiP can detect and bind misfolded hA oligomers, thereby effectively protecting hA against bulk misfolding and irreversible aggregation. Defective β-cell chaperone biology could contribute to hA misfolding and initiation of apoptosis in T2DM. |
| Databáze: | OpenAIRE |
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