Aggregation Of Islet Amyloid Polypeptide Research Articles

Site-Specific Alkylation of the Islet Amyloid Polypeptide Accelerates Self-Assembly and Potentiates Perturbation of Lipid Membranes

The accumulation of insoluble amyloids in the pancreatic islets is a pathological hallmark of type II diabetes and correlates closely with the loss of β-cell mass. The predominant component of these amyloid deposits is the islet amyloid polypeptide (IAPP). The factors contributing to the conversion of IAPP from a monomeric bioactive peptide hormone into insoluble amyloid fibrils remain partially elusive. In this study, we investigated the effect of the oxidative non-enzymatic post-translational modification induced by the reactive metabolite 4-hydroxynonenal (HNE) on IAPP aggregation and cytotoxicity. Incubation of IAPP with exogenous HNE accelerated its self-assembly into β-sheet fibrils and led to the formation of a Michael adduct on the His-18 side chain. To model this covalent modification, the imidazole N(π) position of histidine was alkylated using a close analogue of HNE, the octyl chain. IAPP lipidated at His-18 showed a hastened random coil-to-β-sheet conformational conversion into fibrillar assemblies with a distinct morphology, a low level of binding to thioflavin T, and a high surface hydrophobicity. Introducing an octyl chain on His-18 enhanced the ability of the peptide to perturb synthetic lipid vesicles, to permeabilize the plasma membrane, and to induce the death of pancreatic β-cells. Alkylated IAPP triggered the self-assembly of unmodified IAPP by prompting primary nucleation and increased its capacity to perturb the plasma membrane, indicating that only a small proportion of the modified peptide is necessary to shift the balance toward the formation of proteotoxic species. This study underlines the importance of studying IAPP post-translational modifications induced by oxidative metabolites in the context of pancreatic amyloids.

4-Phenylbutyrate (PBA) treatment reduces hyperglycemia and islet amyloid in a mouse model of type 2 diabetes and obesity

Amyloid deposits in pancreatic islets, mainly formed by human islet amyloid polypeptide (hIAPP) aggregation, have been associated with loss of β-cell mass and function, and are a pathological hallmark of type 2 diabetes (T2D). Treatment with chaperones has been associated with a decrease in endoplasmic reticulum stress leading to improved glucose metabolism. The aim of this work was to investigate whether the chemical chaperone 4-phenylbutyrate (PBA) prevents glucose metabolism abnormalities and amyloid deposition in obese agouti viable yellow (Avy) mice that overexpress hIAPP in β cells (Avy hIAPP mice), which exhibit overt diabetes. Oral PBA treatment started at 8 weeks of age, when Avy hIAPP mice already presented fasting hyperglycemia, glucose intolerance, and impaired insulin secretion. PBA treatment strongly reduced the severe hyperglycemia observed in obese Avy hIAPP mice in fasting and fed conditions throughout the study. This effect was paralleled by a decrease in hyperinsulinemia. Importantly, PBA treatment reduced the prevalence and the severity of islet amyloid deposition in Avy hIAPP mice. Collectively, these results show that PBA treatment elicits a marked reduction of hyperglycemia and reduces amyloid deposits in obese and diabetic mice, highlighting the potential of chaperones for T2D treatment.

1238-P: The Proinflammatory but Not Cytotoxic Effect of Aggregated IAPP on Islet Endothelial Cells Requires TLR2/4 Signaling

We have found that aggregation of the β-cell peptide human islet amyloid polypeptide (hIAPP) causes inflammation and toxicity in islet endothelial cells (IECs), which likely contributes to the islet capillary abnormalities seen in T2D. Based on data from other cell types where hIAPP stimulates the innate immune response, we hypothesized that TLR2/4 signaling is required for the effect of hIAPP on IECs. To test this, we treated MS-1 cells (an immortalized murine IEC cell line) with vehicle control, hIAPP ± the TLR2/4 inhibitor OxPAPc, or, in parallel, the TLR2/TLR4 agonists PAM3CSK4 or LPS for 24h. Cell viability and gene expression were determined. hIAPP resulted in increased levels of inflammatory markers and loss of cell viability (Table). Treatment with the TLR2/4 inhibitor blocked upregulation of Il6 and Vcam1 but not Edn1 expression and did not improve cell viability (Table). Conversely, treatment of IECs with TLR2/4 ligands led to upregulation of Il6 and Vcam1 but not Edn1 expression and did not recapitulate the decrease in cell viability induced by hIAPP (Table). We conclude that TLR2/4 signaling is necessary for the hIAPP-induced proinflammatory response in IECs. In contrast, hIAPP-induced cell death does not require TLR2/4 activation but may contribute to the innate immune response by stimulating release of damage associated molecular patterns and, thereby, inducing TLR signaling.View largeDownload slideView largeDownload slide DisclosureJ. J. Castillo: None. A. Aplin: None. M. F. Hogan: None. A. T. Templin: None. N. Esser: None. R. Akter: None. R. L. Hull: None.FundingNational Institutes of Health (R01DK088082); U.S. Department of Veterans Affairs (BX004063)

Self-Assembled Nanochaperones Inhibit the Aggregation of Human Islet Amyloid Polypeptide Associated with Type 2 Diabetes

Human islet amyloid polypeptide (hIAPP) aggregation is closely associated with dysfunction and apoptosis of pancreatic β-cells in type 2 diabetes (T2D). Accordingly, hIAPP amyloid inhibitors have shown promise against T2D. Here, by mimicking the function of natural molecular chaperones, nanochaperones (nChaps) based on self-assembled polymeric micelles with tunable surface microdomains for T2D treatment are reported. By capturing the aggregation-prone species of hIAPP onto the hydrophobic microdomains and segregating them by hydrophilic PEG chains, this kind of nChaps could effectively prevent hIAPP aggregation, block cell adhesion of hIAPP, facilitate hIAPP aggregates degradation and reduce hIAPP-related cytotoxicity. Therefore, our work will provide useful insights to develop a biomimetic strategy for the treatment of T2D.

Small Molecule Targeting of Feline Islet Amyloid Polypeptide for the Management of Feline Diabetes Mellitus

In a majority of feline diabetic patients, amyloid deposits have been detected in the islets of Langerhans. These deposits originate from islet amyloid polypeptide (IAPP), a satiety hormone produced and co-secreted with insulin by beta-cells. Islet amyloid deposits have been associated with beta-cell death during progression of diabetes. Several molecular entities have been shown to inhibit human IAPP aggregation, including silibinin and resveratrol. However, these agents have poor bioavailability and cause multiple pharmacological effects. An effective means to stop or prevent pancreatic amyloidosis in feline diabetes mellitus with small drug-like molecules is still not available. We hypothesize that it is possible to inhibit the aggregation of feline IAPP selectively by small molecules. The overall objective of this project is to establish the structure-activity relationship of our in-house designed small molecules to impede feline IAPP aggregation and to prepare new analogs for further drug development.We evaluated the effect of 250 newly synthetized small molecules to reduce the formation of feline IAPP fibrils in vitro using Thioflavin T (ThT) fluorescence assays. Screening of small molecules were performed on human IAPP to identify selective inhibitors of feline IAPP. The inhibition of oligomer formation was assessed with photo-induced cross-linking of unmodified protein (PICUP) assays. Inhibition of feline IAPP was confirmed with transmission electron microscopy. Based on the screening of newly synthesized molecules, we discovered selective inhibitors, including JF-19-33, of feline IAPP. Identifying selective inhibitors of feline IAPP aggregation will open up a new therapeutic approach to reducing β-cell death and slowing progression of feline diabetes mellitus.

The Molecular Effect of Natural IAPP Variants on Pancreatic Beta Cell Gene Expression

Diabetes is the seventh leading cause of death and it is still likely to be underreported. Pancreatic beta cells, which are responsible for releasing insulin, have been found to undergo apoptosis in this disease, causing an imbalance in glucose reabsorption. Previous research has shown that islet amyloid polypeptide (IAPP), co-secreted with insulin, aggregates in these cells and contributes to their cell death. Therefore, finding inhibitors for this phenomenon is crucial to allow beta cells to live longer and increase survival rate and quality of life for patients with diabetes. We have found several natural IAPP variants that are inhibitors of human IAPP (hIAPP) aggregation. This work focuses on two natural IAPP variants – IAPPvR and IAPPvC.Both variants are capable of inhibiting human IAPP fiber formation and rescue the cells from the toxic effects of hIAPP. RNA seq results were used to identify differentially expressed genes responsible for the rescue. RNA seq data revealed several genes related to the unfolded protein response system and vesicle function. Further analysis is necessary to confirm the molecular mechanism responsible for this cellular response.

Molecular Effects of hIAPP on Pancreatic β‐cells

A common pathological feature of Type II diabetes is the presence of islet amyloid polypeptide (IAPP) aggregates in the pancreatic beta cells. These aggregates are a possible explanation for the death of beta cells in diabetes patients. The purpose of this study is to determine if human IAPP (hIAPP) is toxic to β-cells and investigate possible mechanisms for its toxicity. Cell viability and cytotoxicity assays along with cell imaging and RNA- seq data were used to determine the effects of hIAPP on pancreatic β-cells. Results show that the addition of increasing amounts of hIAPP led to decreased cell viability. Cytotoxicity assay indicated membrane damage, while cell imaging showed changes in the morphology of cells as a result of hIAPP. RNA-seq analysis revealed differentially expressed genes related to cellular stress and the UPR system. These results suggest that hIAPP is toxic to cells and is damaging to the cell membrane. Further analysis is necessary to determine the molecular mechanism of hIAPP toxicity.

The Effect of Cholesterol on Membrane-Bound Islet Amyloid Polypeptide.

Islet amyloid polypeptide (IAPP) is a proposed cause of the decreased beta-cell mass in patients with type-II diabetes. The molecular composition of the cell-membrane is important for regulating IAPP cytotoxicity and aggregation. Cholesterol is present at high concentrations in the pancreatic beta-cells, and in-vitro experiments have indicated that it affects the amyloid formation of IAPP either by direct interactions or by changing the properties of the membrane. In this study we apply atomistic, unbiased molecular dynamics simulations at a microsecond timescale to investigate the effect of cholesterol on membrane bound IAPP. Simulations were performed with various combinations of cholesterol, phosphatidylcholine (PC) and phosphatidylserine (PS) lipids. In all simulations, the helical structure of monomer IAPP was stabilized by the membrane. We found that cholesterol decreased the insertion depth of IAPP compared to pure phospholipid membranes, while PS lipids counteract the effect of cholesterol. The aggregation propensity has previously been proposed to correlate with the insertion depth of IAPP, which we found to decrease with the increased ordering of the lipids induced by cholesterol. Cholesterol is depleted in the vicinity of IAPP, and thus our results suggest that the effect of cholesterol is indirect.

Optimized experimental pre-treatment strategy for temporary inhibition of islet amyloid polypeptide aggregation

Islet amyloid polypeptide (IAPP) is a neuroendocrine hormone from pancreatic β-cells. Misfolded, aggregated IAPP is believed to be toxic to islet cells and amyloid deposits in the pancreas are pathological hallmarks of type 2 diabetes. Rapid fibrillization of this peptide makes it difficult to study in its soluble form, impeding a better understanding of its role. In this study, a variety of popular pretreatment methods were tested for their ability to delay aggregation of IAPP, including solutions of hexafluoroisopropanol, sodium hydroxide, hydrochloric acid, phosphate buffered saline, ammonium hydroxide, as well as tris buffer at different pH and containing either calcium (II), zinc (II), or iron (II). Aggregation was assessed using the thioflavin T fluorescence assay as well as by transmission electron microscopy. Tris buffer at pH 8.1 containing Zn(II) was found to have the best balance of temporary inhibition of aggregation and biological relevance.

Boosting the Photodynamic Degradation of Islet Amyloid Polypeptide Aggregates Via a “Bait-Hook-Devastate” Strategy

Photosensitizers that can generate reactive oxygen species (ROS) upon irradiation have emerged as promising agents for photodynamic degradation of toxic amyloid aggregates that are linked to many amyloidogenic diseases. However, due to the ultrastable β-sheet structure in amyloid aggregates and inefficient utilization of the generated ROS, it usually requires high stoichiometric concentration of the photosensitizer and/or intensive light irradiation to fully dissociate aggregates. In this work, we have developed a "bait-hook-devastate" strategy to boost the efficiency of the photodynamic degradation of amyloid aggregates. This strategy employs anionic polyacrylic acid as a bait to accumulate cationic human islet amyloid polypeptide (IAPP) aggregates and positively charged photosensitizer TPCI in a confined area through electronic interactions. Multiple characterization studies proved that the utilization rate of ROS generated by TPCI was remarkably improved via this strategy, which amplified the ability of TPCI to dissociate IAPP aggregates. Rapid and complete degradation of IAPP aggregates could be achieved by irradiating the system under very mild conditions for less than 30 min, and the IAPP-mediated cytotoxicity was also largely alleviated, providing a new paradigm to accelerate photodynamic degradation of amyloid aggregates for further practical applications.

Synthesis of Yakuchinone B-Inspired Inhibitors against Islet Amyloid Polypeptide Aggregation.

Type 2 diabetes mellitus (T2DM) is associated with pancreatic β-cell dysfunction and insulin resistance. Islet amyloid polypeptide (IAPP) aggregation is found to induce islet β-cell death in T2DM patients. Recently, we demonstrated that yakuchinone B derivative 1 exhibited inhibitory activity against IAPP aggregation. Thus, in this study, a series of synthesized yakuchinone B-inspired compounds were tested for their anti-IAPP aggregation activity. Four of these compounds, 4e-h, showed greater activity than the lead compound 1, in the sub-μM range (IC50 = 0.7-0.8 μM). The molecular docking analysis revealed crucial hydrogen bonds between the compounds and residues S19 and N22 and important hydrophobic interactions with residue I26. Notably, compounds 4g and 4h significantly protected β-cells against IAPP-induced toxicity with EC50 values of 0.1 and 0.2 μM, respectively. In contrast, the protective activities of compounds 4e and 4f were weak. Overall, these results suggest that the compounds exhibiting IAPP aggregation-inhibiting activity have the potential to treat T2DM.

Hsp70 Inhibits Aggregation of IAPP by Binding to the Heterogeneous Prenucleation Oligomers

Molecular chaperone Hsp70 plays important roles in the pathology of amyloid diseases by inhibiting aberrant aggregation of proteins. However, the biophysical mechanism of the interaction of Hsp70 with the intrinsically disordered proteins (IDPs) is unclear. Here, we report that Hsp70 inhibits aggregation of islet amyloid polypeptide (IAPP) at substoichiometric concentrations under diverse solution conditions, including in the absence of ATP. The inhibitory effect is strongest if Hsp70 is added in the beginning of aggregation but progressively less if added later, indicating a role for Hsp70 in preventing nucleation of IAPP. However, ensemble measurement of the binding affinity suggests poor interactions between Hsp70 and IAPP. Therefore, we hypothesize that the interaction must involve a rare species (e.g., the oligomeric intermediates of IAPP). Size exclusion chromatography and field flow fractionation are then used to fractionate the constituent species. Multiangle light scattering and fluorescence correlation spectroscopy measurements indicate that the dominant fraction in size exclusion chromatography contains a few nanomolar Hsp70-IAPP complexes amid several μmoles of free Hsp70. Using single-particle two-color coincidence detection measurements, we detected a minor fraction that exhibits fluorescence bursts arising from heterogeneous oligomeric complexes of IAPP and Hsp70. Taken together, our results indicate that Hsp70 interacts poorly with the monomers but strongly with oligomers of IAPP. This is likely a generic feature of the interactions of Hsp70 chaperones with the amyloidogenic IDPs. Whereas high-affinity interactions with the oligomers prevent aberrant aggregation, poor interaction with the monomers averts interference with the physiological functions of the IDPs.

Glycans to improve efficacy and solubility of protein aggregation inhibitors.

Glycans to improve efficacy and solubility of protein aggregation inhibitors.

Amyloid Aggregation under the Lens of Liquid–Liquid Phase Separation

Increasing experiments suggest that amyloid peptides can undergo liquid-liquid phase separation (LLPS) before the formation of amyloid fibrils. However, the exact role of LLPS in amyloid aggregation at the molecular level remains elusive. Here, we investigated the LLPS and amyloid fibrillization of a coarse-grained peptide, capable of capturing fundamental properties of amyloid aggregation over a wide range of concentrations in molecular dynamics simulations. On the basis of the Flory-Huggins theory of polymer solutions, we determined the binodal and spinodal concentrations of LLPS in the low-concentration regime, ϕBL and ϕSL, respectively. Only at concentrations above ϕBL, peptides formed metastable or stable oligomers corresponding to the high-density liquid phase (HDLP) in LLPS, out of which the nucleated conformational conversion to fibril seeds occurred. Below ϕSL, the HDLP was metastable and transient, and the subsequent fibrillization process followed the traditional nucleation and elongation mechanisms. Only above ϕSL, the HDLP became stable, and the initial fibril nucleation and growth were governed by the high local peptide concentrations. The predicted saturation of amyloid aggregation half-times with increasing peptide concentration to a constant, instead of the traditional power-law scaling to zero, was confirmed by simulations and by a thioflavin-T kinetic assay and the transmission electron microscopy of islet amyloid polypeptide (IAPP) aggregation. Our study provides a unified picture of amyloid aggregation for a wide range of concentrations within the framework of LLPS, which may help us better understand the etiology of amyloid diseases, where the amyloid protein concentration can vary by ∼9 orders of magnitude depending on the organ location and facilitate the engineering of novel amyloid-based functional materials.

A new biological prospective for the 2-phenylbenzofurans as inhibitors of α-glucosidase and of the islet amyloid polypeptide formation

In this study, we have investigated a series of hydroxylated 2-phenylbenzofurans compounds for their inhibitory activity against α-amylase and α-glucosidase activity.Inhibitors of carbohydrate degrading enzymes seem to have an important role as antidiabetic drugs.Diabetes mellitus is a wide-spread metabolic disease characterized by elevated levels of blood glucose. The most common is type 2 diabetes, which can lead to severe complications. Since the aggregates of islet amyloid polypeptide (IAPP) are common in diabetic patients, the effect of compounds to inhibit amyloid fibril formation was also determined.All the compounds assayed showed to be more active against α-glucosidase. Compound 16 showed the lowest IC50 value of the series, and it is found to be 167 times more active than acarbose, the reference compound. The enzymatic activity assays showed that compound 16 acts as a mixed-type inhibitor of α-glucosidase. Furthermore, compound 16 displayed effective inhibition of IAPP aggregation and it manifested no significant cytotoxicity.To predict the binding of compound 16 to IAPP and α-glucosidase protein complexes, molecular docking studies were performed.Altogether, our results support that the 2-phenylbenzofuran derivatives could represent a promising candidate for developing molecules able to modulate multiple targets involved in diabetes mellitus disorder.

Inhibition of human islet amyloid polypeptide aggregation and cellular toxicity by oleuropein and derivatives from olive oil

AbstractBackgroundBeta‐cell death is the key feature of type 2 diabetes mellitus (T2DM). One hypothesis for the mechanism of this feature is amyloid formation by the human Islet Amyloid Polypeptide (hIAPP). Clinical trials and population studies indicate the healthy virtues of the Mediterranean diet, especially the extra virgin olive oil (EVOO) found in this diet. This oil is enriched in phenolic compounds shown to be effective against several aging and lifestyle diseases. Oleuropein (Ole), one of the most abundant polyphenols in EVOO, has been reported to be anti‐diabetic.MethodI report here a broad biophysical approach and cell biology techniques that enabled me to characterize the different molecular mechanisms by which tyrosol (TYR), hydroxytyrosol (HT), oleuropein (Ole) and oleuropein aglycone (OleA) modulate the hIAPP fibrillation in vitro and their effects on cell cytotoxicity.ResultOleA was found to be more active than Ole, HT and TYR at low micromolar concentrations. I further demonstrated that comparing to other used polyphenols, OleA inhibits the cytotoxicity induced by hIAPP aggregates by protecting more the cell membrane from permeabilization and then from death.ConclusionThese findings highlight the benefits of consuming EVOO and the great potential of its polyphenols. Moreover, they support the possible pharmacological use of EVOO polyphenols for T2DM prevention and therapy as well as for many other amyloid‐related diseases.

Deciphering the Inhibitory Mechanism of hIAPP‐Derived Fragment Peptide Against hIAPP Aggregation in Type 2 Diabetes**

AbstractThe aggregates of human islet amyloid polypeptide (hIAPP or amylin) are well‐known causative agents of type 2 diabetes (T2D). Previous experimental studies reported that hexapeptide ANFLVH inhibited IAPP aggregation and completely prevented IAPP‐mediated toxicity. However, the underlying inhibitory mechanism at the atomic level is not completely understood. In this regard, the molecular mechanism of the inhibition of hIAPP aggregation in the presence of ANFLVH has been elucidated by molecular dynamics (MD) simulations in the present study. MD simulation analysis highlighted that ANFLVH prevented the conformational transition of hIAPP by stabilizing the native helical conformation. The binding free energy analysis by the molecular mechanics Poisson‐Boltzmann surface area (MM‐PBSA) method highlighted favourable binding (ΔGbinding=−49.90±0.67 kcal/mol) of ANFLVH with hIAPP and depicted a significant contribution of the van der Waals interaction term (ΔEvdW=−46.33±0.32 kcal/mol) in the stability of the hIAPP‐ANFLVH complex. The per‐residue binding free energy highlighted that ANFLVH strongly interacted with His18 of hIAPP, which has been reported as a key residue in mediating the hIAPP self‐assembly process. The present work sheds light on the inhibitory mechanism of ANFLVH against hIAPP aggregation at the atomic level. The study will guide the rational design and development of therapeutic candidates against hIAPP aggregation in T2D.

Effect of DNA Origami Nanostructures on hIAPP Aggregation.

The aggregation of human islet amyloid polypeptide (hIAPP) plays a major role in the pathogenesis of type 2 diabetes mellitus (T2DM), and numerous strategies for controlling hIAPP aggregation have been investigated so far. In particular, several organic and inorganic nanoparticles (NPs) have shown the potential to influence the aggregation of hIAPP and other amyloidogenic proteins and peptides. In addition to conventional NPs, DNA nanostructures are receiving more and more attention from the biomedical field. Therefore, in this work, we investigated the effects of two different DNA origami nanostructures on hIAPP aggregation. To this end, we employed in situ turbidity measurements and ex situ atomic force microscopy (AFM). The turbidity measurements revealed a retarding effect of the DNA nanostructures on hIAPP aggregation, while the AFM results showed the co-aggregation of hIAPP with the DNA origami nanostructures into hybrid peptide–DNA aggregates. We assume that this was caused by strong electrostatic interactions between the negatively charged DNA origami nanostructures and the positively charged peptide. Most intriguingly, the influence of the DNA origami nanostructures on hIAPP aggregation differed from that of genomic double-stranded DNA (dsDNA) and appeared to depend on DNA origami superstructure. DNA origami nanostructures may thus represent a novel route for modulating amyloid aggregation in vivo.

Targeting Human Islet Amyloid Polypeptide Aggregation and Toxicity in Type 2 Diabetes: An Overview of Peptide-Based Inhibitors.

Type 2 diabetes (T2D) is a chronic metabolic disease characterized by insulin resistance and a progressive loss of pancreatic islet β-cell mass, which leads to insufficient secretion of insulin and hyperglycemia. Emerging evidence suggests that toxic oligomers and fibrils of human islet amyloid polypeptide (hIAPP) contribute to the death of β-cells and lead to T2D pathogenesis. These observations have opened new avenues for the development of islet amyloid therapies for the treatment of T2D. The peptide-based inhibitors are of great value as therapeutic agents against hIAPP aggregation in T2D owing to their biocompatibility, feasibility of synthesis and modification, high specificity, low toxicity, proteolytic stability (modified peptides), and weak immunogenicity as well as the large size of involved interfaces during self-aggregation of hIAPP. An understanding of what has been done and achieved will provide key insights into T2D pathology and assist in the discovery of more potent drug candidates for the treatment of T2D. In this article, we review various peptide-based inhibitors of hIAPP aggregation, including those derived from the hIAPP sequence and those not based on the sequence, consisting of both natural as well as unnatural amino acids and their derivatives. The present review will be beneficial in advancing the field of peptide medicine for the treatment of T2D.

Heterologous Expression of Immature Forms of Human Islet Amyloid Polypeptide in Yeast Triggers Intracellular Aggregation and Cytotoxicity.

Diabetes is a major public health issue that has attained alarming levels worldwide. Pancreatic aggregates of human islet amyloid polypeptide (IAPP) represent a major histopathological hallmark of type 2 diabetes. IAPP is expressed in β-cells as pre-pro-IAPP (ppIAPP) that is first processed to pro-IAPP (pIAPP) and finally to its mature form (matIAPP), being released upon glucose stimulation together with insulin. Impairment and overload of the IAPP processing machinery seem to be associated with the accumulation of immature IAPP species and the formation of toxic intracellular oligomers, which have been associated with β-cell dyshomeostasis and apoptosis. Nevertheless, the pathological importance of these immature IAPP forms for the assembly and cytotoxicity of these oligomers is not completely understood. Here, we describe the generation and characterization of unprecedented Saccharomyces cerevisiae models recapitulating IAPP intracellular oligomerization. Expression of green fluorescent protein (GFP) fusions of human ppIAPP, pIAPP, and matIAPP proved to be toxic in yeast cells at different extents, with ppIAPP exerting the most deleterious effect on yeast growth and cell viability. Although expression of all IAPP constructs induced the formation of intracellular aggregates in yeast cells, our data point out the accumulation of insoluble oligomeric species enriched in immature ppIAPP as the trigger of the high toxicity mediated by this construct in cells expressing ppIAPP-GFP. In addition, MS/MS analysis indicated that oligomeric species found in the ppIAPP-GFP lysates contain the N-terminal sequence of the propeptide fused to GFP. These models represent powerful tools for future research focused on the relevance of immature forms in IAPP-induced toxicity. Furthermore, they are extremely useful in high-throughput screenings for genetic and chemical modulators of IAPP aggregation.