An in vivo platform for identifying inhibitors of protein aggregation.

Protein aggregation underlies an array of human diseases, yet only one small-molecule therapeutic targeting this process has been successfully developed to date. Here, we introduce an in vivo system, based on a ß-lactamase tripartite fusion construct, that is capable of identifying aggregation-prone sequences in the periplasm of Escherichia coli and inhibitors that prevent their aberrant self-assembly. We demonstrate the power of the system using a range of proteins, from small unstructured peptides (islet amyloid polypeptide and amyloid ß) to larger, folded immunoglobulin domains. Configured in a 48-well format, the split ß-lactamase sensor readily differentiates between aggregation-prone and soluble sequences. Performing the assay in the presence of 109 compounds enabled a rank ordering of inhibition and revealed a new inhibitor of islet amyloid polypeptide aggregation. This platform can be applied to both amyloidogenic and other aggregation-prone systems, independent of sequence or size, and can identify small molecules or other factors able to ameliorate or inhibit protein aggregation.

ESI-IMS-MS: A method for rapid analysis of protein aggregation and its inhibition by small molecules.

Electrospray ionisation-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS) is a powerful method for the study of conformational changes in protein complexes, including oligomeric species populated during protein self-aggregation into amyloid fibrils. Information on the mass, stability, cross-sectional area and ligand binding capability of each transiently populated intermediate, present in the heterogeneous mixture of assembling species, can be determined individually in a single experiment in real-time. Determining the structural characterisation of oligomeric species and alterations in self-assembly pathways observed in the presence of small molecule inhibitors is of great importance, given the urgent demand for effective therapeutics. Recent studies have demonstrated the capability of ESI-IMS-MS to identify small molecule modulators of amyloid assembly and to determine the mechanism by which they interact (positive, negative, non-specific binding, or colloidal) in a high-throughput format. Here, we demonstrate these advances using self-assembly of Aß40 as an example, and reveal two new inhibitors of Aß40 fibrillation.

Insights into the consequences of co-polymerisation in the early stages of IAPP and Aß peptide assembly from mass spectrometry.

The precise molecular mechanisms by which different peptides and proteins assemble into highly ordered amyloid deposits remain elusive. The fibrillation of human amylin (also known as islet amyloid polypeptide, hIAPP) and the amyloid-beta peptide (Aß-40) are thought to be pathogenic factors in Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD), respectively. Amyloid diseases may involve co-aggregation of different protein species, in addition to the self-assembly of single precursor sequences. Here we investigate the formation of heterogeneous pre-fibrillar, oligomeric species produced by the co-incubation of hIAPP and Aß-40 using electrospray ionisation-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS)-based methods. Conformational properties and gas-phase stabilities of amyloid oligomers formed from hIAPP or Aß40 alone, and from a 1 : 1 mixture of hIAPP and Aß40 monomers, were determined and compared. We show that co-assembly of the two sequences results in hetero-oligomers with distinct properties and aggregation kinetics properties compared with the homo-oligomers present in solution. The observations may be of key significance to unravelling the mechanisms of amyloid formation in vivo and elucidating how different sequences and/or assembly conditions can result in different fibril structures and/or pathogenic outcomes.

Pharmacogenetics to Avoid Loss of Hearing (PALOH) trial: a protocol for a prospective observational implementation trial.

INTRODUCTION: In conjunction with a beta-lactam, aminoglycosides are the first-choice antibiotic for empirical treatment of sepsis in the neonatal period. The m.1555A>G variant predisposes to ototoxicity after aminoglycoside administration and has a prevalence of 1 in 500. Current genetic testing can take over 24 hours, an unacceptable delay in the acute setting. This prospective-observational trial will implement a rapid point of care test (POCT), facilitating tailored antibiotic prescribing to avoid hearing loss. METHODS AND ANALYSIS: The genedrive POCT can detect the m.1555A>G variant in 26 min from buccal swab. This system will be integrated into the clinical pathways at two large UK neonatal centres over a minimum 6-month period. The primary outcome is the number of neonates successfully tested for the variant out of all babies prescribed antibiotics. As a secondary outcome, clinical timings will be compared with data collected prior to implementation, measuring the impact on routine practice. ETHICS AND DISSEMINATION: Approval for the trial was granted by the Research Ethics Committee (REC) and Human Research Authority in August 2019. Results will be published in full on completion of the study. TRIAL REGISTRATION NUMBER: ISRCTN13704894. PROTOCOL VERSION: V 1.3.

Diagnosing and Preventing Hearing Loss in the Genomic Age.

Over the past two decades, significant technological advances have facilitated the identification of hundreds of genes associated with hearing loss. Variants in many of these genes result in severe congenital hearing loss with profound implications for the affected individual and their family. This review collates these advances, summarizing the current state of genomic knowledge in childhood hearing loss. We consider how current and emerging genetic technologies have the potential to alter our approach to the management and diagnosis of hearing loss. We review approaches being taken to ensure that these discoveries are used in clinical practice to detect genetic hearing loss as soon as possible to reduce unnecessary investigations, provide information about reproductive risks, and facilitate regular follow-up and early treatment. We also highlight how rapid sequencing technology has the potential to identify children susceptible to antibiotic-induced hearing loss and how this adverse reaction can be avoided.

Screening and classifying small-molecule inhibitors of amyloid formation using ion mobility spectrometry-mass spectrometry.

The search for therapeutic agents that bind specifically to precursor protein conformations and inhibit amyloid assembly is an important challenge. Identifying such inhibitors is difficult because many protein precursors of aggregation are partially folded or intrinsically disordered, which rules out structure-based design. Furthermore, inhibitors can act by a variety of mechanisms, including specific or nonspecific binding, as well as colloidal inhibition. Here we report a high-throughput method based on ion mobility spectrometry-mass spectrometry (IMS-MS) that is capable of rapidly detecting small molecules that bind to amyloid precursors, identifying the interacting protein species and defining the mode of inhibition. Using this method we have classified a variety of small molecules that are potential inhibitors of human islet amyloid polypeptide (hIAPP) aggregation or amyloid-beta 1-40 aggregation as specific, nonspecific, colloidal or non-interacting. We also demonstrate the ability of IMS-MS to screen for inhibitory small molecules in a 96-well plate format and use this to discover a new inhibitor of hIAPP amyloid assembly.