# Mechanisms of diabetic amyloid formation via 2D IR spectroscopy

> **NIH NIH R01** · UNIVERSITY OF WISCONSIN-MADISON · 2021 · $545,944

## Abstract

Mechanisms of diabetic amyloid formation via 2D IR spectroscopy
Abstract
 Type 2 diabetes afflicts nearly 26 million Americans and causes a larger economic loss than all cancers
combined. It starts as insulin resistance, but ultimately the pancreatic β-cells that make insulin fail, resulting in
overt diabetes. Failure is partially due to aggregation of the hormone known as the human islet amyloid
polypeptide (hIAPP or amylin) into amyloid plaques that occupy up to 80% of the islet space. Surprisingly, the
amyloid fibers themselves are not cytotoxic. Many researchers believe that the toxic species are oligomers of
hIAPP, perhaps by interfering with receptor mediated processes or permeabilizing the membrane. As a result,
there is much interest in understanding the mechanism by which hIAPP aggregates, because the aggregation
pathway dictates the structures and populations of these cytotoxic intermediates. The first cryoEM structure of
amylin was recently reported, but very little structural information exists about intermediates because applying
most structural biology tools to kinetically evolving proteins is difficult. We discovered an oligomeric species by
monitoring the aggregation kinetics of hIAPP using a technology that we invented, on-the-fly 2D IR spectroscopy.
In doing so, we discovered that hIAPP forms oligomers with a parallel β-sheet in the FGAIL region, prior to
restructuring into its fibrillar structure. The need to restructure results in a prolonged lifetime and stable population
of the oligomers. We observed this “FGAIL oligomer” in 4 different mammalian species known to contract type 2
diabetes, strengthening our hypothesis that this intermediate is a key player in the disease. Most importantly, we
realized that we could trap the oligomer with a few benignly placed mutations. Our trapped oligomers are nearly
as toxic as wild-type hIAPP, but persist in vitro for days rather than hours. Because it is stable for so long, it
enables many new structural, biochemical, and physiological assays not previously possible. And, it provides an
intellectual basis to create a new knock-in mouse to investigate hIAPP oligomers in an animal model. With that
goal in mind, we have begun working with humanized mice and developed the technology to image pancreas
tissues with 2D IR microscopy. Specific Aim 1 will generate a series of trapped oligomers, each of which will be
tested for its suitability as a model for hIAPP oligomers. Specific Aim 2 will investigate the aggregation pathway
that leads to a recently reported cryoEM structure to determine if this polymorph is formed from a new or existing
mechanistic pathway. In Aim 3, we link our in vitro observations to in vivo physiology via 2D IR imaging of two
transgenic mouse models. We seek to understand hIAPP aggregation from a fundamental perspective, which is
important for inhibitor design and hormone replacement therapies, and utilize that information to translate our in
vitro work into in vivo anim...

## Key facts

- **NIH application ID:** 10264901
- **Project number:** 5R01DK079895-15
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** Martin T Zanni
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $545,944
- **Award type:** 5
- **Project period:** 2008-03-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10264901

## Citation

> US National Institutes of Health, RePORTER application 10264901, Mechanisms of diabetic amyloid formation via 2D IR spectroscopy (5R01DK079895-15). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10264901. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*