The primary goal of this proposal is the design of small molecule compounds which target newly identified protein structures with direct relevance to insulin secreting 2-cell viability in type II diabetes. Islet amyloid polypeptide (IAPP) is a 37-residue peptide hormone, which is co-secreted with insulin by the 2-cells of the endocrine pancreas. IAPP belongs to a class of aggregation prone proteins, which includes A2 from Alzheimer's, in which a wild-type protein precursor irreversibly forms/folds into 2-sheet rich fibrillar amyloid plaques. The origin of 2-cell death in type II diabetes is poorly understood. Like most amyloid diseases, it is the presence, rather than the extent, of amyloid deposition that is correlated with pathology. Instead, it is the intermediates of the assembly reaction that have been implicated in cell death. Importantly, this cytotoxicity is mediated by the formation of membrane bound protein structures. In the case of IAPP, this is highly intriguing since, despite the 2-sheet nature of mature amyloid, membrane bound states are 1-helical. The overall hypothesis pursued by this proposal is that small-molecule, structure based targeting of pre-amyloidogenic states will enable elucidation of the mechanism of IAPP induced cytotoxicity. These efforts will provide novel descriptions of IAPP oligomerization at a molecular level, and provide a rational design path for the creation of lead compounds that ameliorate 2-cell death. Our concurrently pursued aims include synergistic efforts in synthetic chemistry, cell and structural biology. Importantly, we will target the 1-helical intermediates of IAPP by synthesizing small molecules designed to mimic the surface presentation of one edge of an 1-helix. Cellular methods will be developed to assess toxicity and localization of IAPP. Diffraction, NMR and computational methods will be employed to elucidate the alternative oligomeric states at atomic resolution and to provide structure based guidance for small molecule synthesis.

Public Health Relevance

Changes to the shape of a protein surface can result in its inadvertent assembly into toxic structures. This process occurs in numerous diseases including type II diabetes and Alzheimer's. A novel synthetic chemistry approach is proposed that allows for the mimicking of protein surface using small molecules. This will enable the testing of hypotheses about the molecular basis of toxicity in the insulin secreting cells of type II diabetics.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM094693-03
Application #
8442327
Study Section
Macromolecular Structure and Function D Study Section (MSFD)
Program Officer
Fabian, Miles
Project Start
2011-04-01
Project End
2015-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
3
Fiscal Year
2013
Total Cost
$302,274
Indirect Cost
$118,924
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
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Hebda, James A; Magzoub, Mazin; Miranker, Andrew D (2014) Small molecule screening in context: lipid-catalyzed amyloid formation. Protein Sci 23:1341-8
Kumar, Sunil; Miranker, Andrew D (2013) A foldamer approach to targeting membrane bound helical states of islet amyloid polypeptide. Chem Commun (Camb) 49:4749-51
Last, Nicholas B; Miranker, Andrew D (2013) Common mechanism unites membrane poration by amyloid and antimicrobial peptides. Proc Natl Acad Sci U S A 110:6382-7
Last, Nicholas B; Schlamadinger, Diana E; Miranker, Andrew D (2013) A common landscape for membrane-active peptides. Protein Sci 22:870-82
Magzoub, Mazin; Miranker, Andrew D (2012) Concentration-dependent transitions govern the subcellular localization of islet amyloid polypeptide. FASEB J 26:1228-38