A potential anti-amyloidogenic therapy for type 2 diabetes based on the QBP1 peptide

The self-assembly and aggregation of human islet amyloid polypeptide (hIAPP, or amylin) into β-sheet-rich structures, such as oligomers and fibrils, are implicated in pancreatic β-cell dysfunction and failure, contributing to the pathogenesis of Type 2 Diabetes (T2D). Consequently, extensive research has focused on identifying inhibitors, particularly short peptides, capable of targeting hIAPP and disrupting its amyloidogenic process, offering potential therapeutic strategies to prevent or slow T2D progression. In this study, we demonstrate the effectiveness of the anti-amyloidogenic peptide QBP1 in blocking the critical conformational transition to β-structure experienced by the hIAPP monomer, thereby in preventing amyloidogenesis and in reducing the cytotoxicity associated with its amyloid forms. First, we evaluated the anti-amyloidogenic effects of QBP1 through an in vitro aggregation methods, including a Thioflavin-T binding assay, dot blotting using the oligomer-specific A11 and fibril-specific OC antibodies, and negative staining electron microscopy. To assess its cytoprotective potential of QBP1 on hIAPP-induced toxicity, we examined its effects when fused to a protein transduction domain (penetratin) in INS-1E pancreatic β-cells, using viability assays and transcriptome analysis. Our results demonstrate that QBP1 effectively halts the formation of early toxic hIAPP intermediates, preventing amyloid progression and preserving β-cell viability and function. Additionally, molecular dynamics simulations revealed that QBP1 stabilizes amylin through strong van der Waals interactions and π-H bonds at hydrophobic and aromatic residues (i.e., W, F), forming a stable binding network that prevents aggregation. Binding free energy analysis confirmed its high affinity, driven by favourable non-polar solvation energy and optimized structural complementarity. Collectively, these findings position QBP1 as a promising therapeutic candidate for preventing islet amyloid formation and mitigating β-cell dysfunction in T2D.