Amyloid deposition occurs in at least twenty five different human diseases. This project is focused on amyloid formation by Islet Amyloid Polypeptide (IAPP, Amylin), the hormone responsible for pancreatic islet amyloid in type 2 diabetes. IAPP is normally secreted as a soluble polypeptide together with insulin, but aggregates via an unknown mechanism in type 2 diabetes to form extracellular islet amyloid. Islet amyloid, or the process of its formation, is toxic to ?-cells and contributes to the patholog of type 2 diabetes. Amyloid formation by IAPP has been recently shown to be a major complicating factor in islet cell transplantation. Diabetes has reached epidemic proportions in the United States and is emerging as a major health threat in the developing world. Relatively little is known about the mechanism of amyloid formation by IAPP or about the nature of the toxic species generated during its formation. The research will (I) determine the mechanism of amyloid formation by IAPP;(II) examine the effects of a mutation in IAPP which has been proposed to be linked to early onset diabetes;(III) define the most toxic species populated during amyloid assembly and define their conformational properties;(IV) critically test the hypotheses that accelerating amyloid formation reduces IAPP induced cytotoxicity. The research will provide insight into strategies for the treatment of type 2 diabetes and for the prevention of islet graft failure after transplantation. The lessons learned will also aid in the design of more soluble variants of IAPP to treat type 1 diabetes. An interdisciplinary combination of experimental biophysics, biochemistry and cell biology will be used to address these issues. The methods being developed are expected to be broadly applicable and will aid efforts to better control amyloid formation in other diseases.
Five specific aims will be carried out. The first involves studies of the mechanism of amyloid formation by IAPP.
The second aim will examine the basis for enhanced amyloid formation by a natural mutant of human IAPP.
The third aim will interrogate the conformational properties of toxic intermediates populated during amyloid formation by IAPP using high resolution methods, while the fourth aim will conduct comparative studies of toxic and non-toxic IAPP inhibitor complexes.
The final aim will test a new strategy for preventing IAPP toxicity.
The pancreatic hormone IAPP aggregates in type 2 diabetes to form pathological deposits known as amyloid which kill the insulin producing beta-cells. IAPP amyloid deposits are also believed to be a major complicating factor in islet cell transplantation. This project will determine the mechanism of amyloid formation by IAPP and will develop methods for preventing it. Diabetes is reaching epidemic proportions in the Western World and this project will have a direct impact on human health.
|Zhang, Xiaoxue; St Clair, Johnna R; London, Erwin et al. (2017) Islet Amyloid Polypeptide Membrane Interactions: Effects of Membrane Composition. Biochemistry 56:376-390|
|Brar, Gurkirat S; Barrow, Breanne M; Watson, Matthew et al. (2017) Neprilysin Is Required for Angiotensin-(1-7)'s Ability to Enhance Insulin Secretion via Its Proteolytic Activity to Generate Angiotensin-(1-2). Diabetes 66:2201-2212|
|Raj, Shriya; Nazemidashtarjandi, Saeed; Kim, Jihyun et al. (2017) Changes in glucosylceramide structure affect virulence and membrane biophysical properties of Cryptococcus neoformans. Biochim Biophys Acta 1859:2224-2233|
|Akter, Rehana; Cao, Ping; Noor, Harris et al. (2016) Islet Amyloid Polypeptide: Structure, Function, and Pathophysiology. J Diabetes Res 2016:2798269|
|Wong, Amy G; Wu, Chun; Hannaberry, Eleni et al. (2016) Analysis of the Amyloidogenic Potential of Pufferfish (Takifugu rubripes) Islet Amyloid Polypeptide Highlights the Limitations of Thioflavin-T Assays and the Difficulties in Defining Amyloidogenicity. Biochemistry 55:510-8|
|Abedini, Andisheh; Cao, Ping; Raleigh, Daniel P (2016) Detection of Helical Intermediates During Amyloid Formation by Intrinsically Disordered Polypeptides and Proteins. Methods Mol Biol 1345:55-66|
|Cao, Ping; Raleigh, Daniel P (2016) In Vitro Studies of Membrane Permeability Induced by Amyloidogenic Polypeptides Using Large Unilamellar Vesicles. Methods Mol Biol 1345:283-90|
|Wong, Amy G; Raleigh, Daniel P (2016) The dye SYPRO orange binds to amylin amyloid fibrils but not pre-fibrillar intermediates. Protein Sci 25:1834-40|
|Lee, Christine C; Julian, Mark C; Tiller, Kathryn E et al. (2016) Design and Optimization of Anti-amyloid Domain Antibodies Specific for ?-Amyloid and Islet Amyloid Polypeptide. J Biol Chem 291:2858-73|
|Peran, Ivan; Watson, Matthew D; Bilsel, Osman et al. (2016) Selenomethionine, p-cyanophenylalanine pairs provide a convenient, sensitive, non-perturbing fluorescent probe of local helical structure. Chem Commun (Camb) 52:2055-8|
Showing the most recent 10 out of 59 publications