JOP. J Pancreas (Online) 2005; 6(4):287-302.

Type 2 Diabetes Mellitus as a Conformational Disease

Melvin R Hayden1, Suresh C Tyagi2, Michelle M Kerklo3, Mark R Nicolls3

1Department of Family and Community Medicine, University of Missouri. Columbia, Missouri, USA. 2Department of Physiology and Biophysics, University of Louisville School of Medicine. Louisville, Kentucky, USA. 3Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center. Denver, Colorado, USA


Conformational diseases are conditions that arise from the dysfunctional aggregation of proteins in non-native conformations. Type 2 diabetes mellitus can be defined as a conformational disease because a constituent beta cell protein, islet amyloid polypeptide, undergoes a change in tertiary structure followed by self-association and tissue deposition. Type 2 diabetes mellitus is associated with multiple metabolic derangements that result in the excessive production of reactive oxygen species and oxidative stress. These reactive oxygen species set in motion a host of redox reactions which can result in unstable nitrogen and thiol species that contribute to additional redox stress. The ability of a cell to deal with reactive oxygen species and oxidative stress requires functional chaperones, antioxidant production, protein degradation and a cascade of intracellular events collectively known as the unfolded protein response. It is known that beta cells are particularly susceptible to perturbations in this quality control system and that reactive oxygen species play an important role in the development and/or progression of diabetes mellitus. Oxidative stress and increased insulin production contribute to endoplasmic reticulum stress, protein misfolding, and induction of the unfolded protein response. As the cellís quality control system becomes overwhelmed, conformational changes occur to islet amyloid polypeptide intermediates, generating stable oligomers with an anti-parallel crossed beta-pleated sheet structure that eventually accumulate as space-occupying lesions within the islets. By approaching type 2 diabetes mellitus as a conformational disease in which there is a structural transition from physiological protein to pathological protein, it is possible that the relentless nature of disease progression can be understood in relation to other conformational diseases.

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Keywords Amyloid; Diabetes Mellitus, Type 2; Islets of Langerhans; Islets of Langerhans Transplantation; Molecular Chaperones; Protein Conformation

Correspondance Mark Nicolls: mark.nicolls@uchsc.edu