Establishment of new detection methods for the discovery and development of novel ABCA1 and ABCA7 modulators as Alzheimer’s disease (AD) therapeutics and diagnostics
Molecular and Cellular Neurology and Neuropathology
Organic Molecular Chemistry - Synthesis and Characterisation
Cell Biology
Final Report Abstract
It has been established that the (over)production, degradation, and clearance of amyloidbeta (Aβ) proteins are key elements in the pathophysiology of Alzheimer’s disease (AD). Lipid transporters of the ATP-binding cassette (ABC) transporter superfamily have been associated to AD, and particularly ABCA1 and ABCA7 were statistically proven risk factors. Despite gained knowledge of recent years, both ABCA1 and ABCA7 are under-studied ABC transporters for which (almost) no modulators have been discovered so far. These modulators are, however, necessary as molecular tools to study the (patho)physiology of these transporters, and which may serve as template molecules for novel AD therapeutics and diagnostics. Unfortunately, for both ABCA1 and ABCA7, no established, well-characterized, and widely applied assessment platforms are available that allow for the development of small-molecular modulators. Research on ABCA1 and ABCA7 lacks almost every necessary component for a functional assay workflow. Thus, the aims of this project were the development of functional testing platforms for small-molecule screening and assessment, as well as the discovery of structurally novel modulators of both ABCA1 and ABCA7. A multiple-tracked strategy was followed to enable success on all levels, particularly concerning a cell lines, b functional tracers, c known literature modulators, d reported assay protocols, e collaborative partners, and f compound libraries. Murine macrophages were identified as easy-to-handle, most reliable, and high-throughput suitable host systems for ABCA1 expression. Unfortunately, no ABCA7 host system could be generated. A straightforward assay workflow based on a fluoro-labelled cholesterol derivative was established for assessment of ABCA1 transport activity, while the development of a crude membrane-based ATPase assay was unfortunately unsuccessful. The scarce literature data on potent and weak ABCA1 inhibition could be reproduced, strengthening the overall confidence in the assessment platform and the generated data. Applying particularly polypharmacological ABC transporter modulators, structurally novel drugs and drug-like molecules could be identified as in part very strong inhibitors of ABCA1. Screening of collaborators’ compound libraries of diverse origin also resulted in hit molecules with rather broad potency range but high biological hit rates. An organic-synthetic approach by an Indian collaborator provided further potent hit molecules against ABCA1. Most strikingly, the developed computational workflow could provide ABCA1 inhibitors with a hit rate of 95.5%. The obtained molecules were structurally very diverse belonging to various classes, and had in part very high potency against ABCA1. In summary, despite major drawbacks that the projects had, the final goals to establish a cell-biological workflow and to discover and develop novel modulators could be accomplished for ABCA1. The established assay, the obtained small-molecules, as well as the developed computational model may be re-used for translation into other fields of research.
Publications
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A Novel Huntington’s Disease Assessment Platform to Support Future Drug Discovery and Development. International Journal of Molecular Sciences, 23(23), 14763.
Wu, Jingyun; Möhle, Luisa; Brüning, Thomas; Eiriz, Iván; Rafehi, Muhammad; Stefan, Katja; Stefan, Sven Marcel & Pahnke, Jens
