The design of inhibitors of protein-protein interactions mediating amyloid self-assembly is a major challenge mainly due to the dynamic nature of the involved structures and interfaces. Interactions of amyloidogenic polypeptides with other proteins are important modulators of self-assembly. Here we present a hot-segment-linking approach to design a series of mimics of the IAPP cross-amyloid interaction surface with Aβ (ISMs) as nanomolar inhibitors of amyloidogenesis and cytotoxicity of Aβ, IAPP, or both polypeptides. The nature of the linker determines ISM structure and inhibitory function including both potency and target selectivity. Importantly, ISMs effectively suppress both self- and cross-seeded IAPP self-assembly. Our results provide a novel class of highly potent peptide leads for targeting protein aggregation in Alzheimer's disease, type 2 diabetes, or both diseases and a chemical approach to inhibit amyloid self-assembly and pathogenic interactions of other proteins as well.

The interaction of the intrinsically disordered polypeptide islet amyloid polypeptide (IAPP), which is associated with type 2 diabetes (T2D), with the Alzheimer's disease amyloid-β (Aβ) peptide modulates their self-assembly into amyloid fibrils and may link the pathogeneses of these two cell-degenerative diseases. However, the molecular determinants of this interaction remain elusive. Using a systematic alanine scan approach, fluorescence spectroscopy, and other biophysical methods, including heterocomplex pulldown assays, far-UV CD spectroscopy, the thioflavin T binding assay, transmission EM, and molecular dynamics simulations, here we identified single aromatic/hydrophobic residues within the amyloid core IAPP region as hot spots or key residues of its cross-interaction with Aβ40(42) peptide. Importantly, we also find that none of these residues in isolation plays a key role in IAPP self-assembly, whereas simultaneous substitution of four aromatic/hydrophobic residues with Ala dramatically impairs both IAPP self-assembly and hetero-assembly with Aβ40(42). Furthermore, our experiments yielded several novel IAPP analogs, whose sequences are highly similar to that of IAPP but have distinct amyloid self- or cross-interaction potentials. The identified similarities and major differences controlling IAPP cross-peptide interaction with Aβ40(42) its amyloid self-assembly offer a molecular basis for understanding the underlying mechanisms. We propose that these insights will aid in designing intervention strategies and novel IAPP analogs for the management of type 2 diabetes, Alzheimer's disease, or other diseases related to IAPP dysfunction or cross-amyloid interactions.

In this paper we report the synthesis of a series of benzoxaborole derivatives, their inhibition properties against some carbonic anhydrases (CAs), recognized as important drug targets, and the characterization of the binding mode of these molecules to the CA active site. Our data provide the first experimental evidence that benzoxaboroles can be efficiently used as CA inhibitors.

Alzheimer's disease (AD) and type 2 diabetes (T2D) are linked to the self-association of β-amyloid peptide (Aβ) and islet amyloid polypeptide (IAPP), respectively. We have shown that IAPP-GI, a soluble IAPP analogue and mimic of nonamyloidogenic and nontoxic IAPP, binds Aβ with high affinity and blocks its cytotoxic self-assembly and fibrillogenesis. We have also shown that IAPP and Aβ interact with each other into nonfibrillar and nontoxic heterocomplexes that suppress cytotoxic self-association by both polypeptides. The Aβ-IAPP interaction might thus be a molecular link between AD and T2D. We studied the role of individual IAPP-GI and IAPP regions in their inhibitory function on Aβ40 self-association and cytotoxicity. We found that the presence of the two hot-spot regions of the Aβ-IAPP interaction interface in IAPP(8-28) is not sufficient for inhibitory function and that, in addition to IAPP(8-28), the presence of the N-terminal region IAPP(1-7) is absolutely required. By contrast, the C-terminal region, IAPP(30-37), is not required although its presence together with IAPP(1-7) in IAPP-GI results in a marked enhancement of the inhibitory effect as compared to IAPP(1-28)-GI. We suggest that the inhibitory effect of IAPP-GI and IAPP on Aβ40 fibrillogenesis and cell toxicity is mediated primarily by interactions involving the hot regions of the Aβ-IAPP interaction interface and the N terminus of IAPP while a concerted and likely structure-stabilizing action of the N- and C-terminal IAPP regions potentiates this effect. These results identify important molecular determinants of the amyloid suppressing function of the Aβ40-IAPP interaction and could contribute to the design of novel inhibitors of Aβ40 aggregation and cell degeneration.

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More selective interactions of nanoparticles with cells would substantially increase their potential for diagnostic and therapeutic applications. Thus, it would not only be highly desirable that nanoparticles can be addressed to any cell with high target specificity and affinity, but that we could unequivocally define whether they rest immobilized on the cell surface as a diagnostic tag, or if they are internalized to serve as a delivery vehicle for drugs. To date no class of targets is known that would allow direction of nanoparticle interactions with cells alternatively into one of these mutually exclusive events. Using MCF-7 breast cancer cells expressing the human Y 1 -receptor, we demonstrate that G protein-coupled receptors provide us with this option. We show that quantum dots carrying a surface-immobilized antagonist remain with nanomolar affinity on the cell surface, and particles carrying an agonist are internalized upon receptor binding. The receptor functions like a logic "and-gate" that grants cell access only to those particles that carry a receptor ligand "and" where the ligand is an agonist. We found that agonist-and antagonistmodified nanoparticles bind to several receptor molecules at a time. This multiligand binding leads to five orders of magnitude increased-receptor affinities, compared with free ligand, in displacement studies. More than 800 G protein-coupled receptors in humans provide us with the paramount advantage that targeting of a plethora of cells is possible, and that switching from cell recognition to cell uptake is simply a matter of nanoparticle surface modification with the appropriate choice of ligand type.nanoparticle targeting | drug delivery | quantum dots | nanoparticle receptor interaction | cell membrane binding

BackgroundA novel prediction algorithm is needed for the identification of effective tumor associated mutated neoantigens. Only those with no homology to self wild type antigens are true predicted neoantigens (TPNAs) and can elicit an antitumor T cell response, not attenuated by central tolerance. To this aim, the mutational landscape was evaluated in HCV-associated hepatocellular carcinoma.MethodsLiver tumor biopsies and adjacent non-tumor liver tissues were obtained from 9 HCV-chronically infected subjects and subjected to RNA-Seq analysis. Mutant peptides were derived from single nucleotide variations and TPNAs were predicted using two prediction servers (e.g. NetTepi and NetMHCstabpan) by comparison with corresponding wild-type sequences, non-related self and pathogen-related antigens. Immunological confirmation was obtained in preclinical as well as clinical setting.ResultsThe development of such an improved algorithm resulted in a handful of TPNAs despite the large number of predicted neoantigens. Furthermore, TPNAs may share homology to pathogen’s antigens and be targeted by a pre-existing T cell immunity. Cross-reactivity between such antigens was confirmed in an experimental pre-clinical setting. Finally, TPNAs homologous to pathogen’s antigens were found in the only HCC long-term survival patient, suggesting a correlation between the pre-existing T cell immunity specific for these TPNAs and the favourable clinical outcome.ConclusionsThe new algorithm allowed the identification of the very few TPNAs in cancer cells, and those targeted by a pre-existing immunity strongly correlated with long-term survival. Only such TPNAs represent the optimal candidates for immunotherapy strategies.Electronic supplementary materialThe online version of this article (10.1186/s12967-018-1662-9) contains supplementary material, which is available to authorized users.