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Gising J, Honarnejad S, Bras M, Baillie GL, McElroy SP, Jones PS, Morrison A, Beveridge J, Hallberg M, Larhed M. The Discovery of New Inhibitors of Insulin-Regulated Aminopeptidase by a High-Throughput Screening of 400,000 Drug-like Compounds. Int J Mol Sci 2024; 25:4084. [PMID: 38612894 PMCID: PMC11012289 DOI: 10.3390/ijms25074084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/25/2024] [Accepted: 04/02/2024] [Indexed: 04/14/2024] Open
Abstract
With the ambition to identify novel chemical starting points that can be further optimized into small drug-like inhibitors of insulin-regulated aminopeptidase (IRAP) and serve as potential future cognitive enhancers in the clinic, we conducted an ultra-high-throughput screening campaign of a chemically diverse compound library of approximately 400,000 drug-like small molecules. Three biochemical and one biophysical assays were developed to enable large-scale screening and hit triaging. The screening funnel, designed to be compatible with high-density microplates, was established with two enzyme inhibition assays employing either fluorescent or absorbance readouts. As IRAP is a zinc-dependent enzyme, the remaining active compounds were further evaluated in the primary assay, albeit with the addition of zinc ions. Rescreening with zinc confirmed the inhibitory activity for most compounds, emphasizing a zinc-independent mechanism of action. Additionally, target engagement was confirmed using a complementary biophysical thermal shift assay where compounds causing positive/negative thermal shifts were considered genuine binders. Triaging based on biochemical activity, target engagement, and drug-likeness resulted in the selection of 50 qualified hits, of which the IC50 of 32 compounds was below 3.5 µM. Despite hydroxamic acid dominance, diverse chemotypes with biochemical activity and target engagement were discovered, including non-hydroxamic acid compounds. The most potent compound (QHL1) was resynthesized with a confirmed inhibitory IC50 of 320 nM. Amongst these compounds, 20 new compound structure classes were identified, providing many new starting points for the development of unique IRAP inhibitors. Detailed characterization and optimization of lead compounds, considering both hydroxamic acids and other diverse structures, are in progress for further exploration.
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Affiliation(s)
- Johan Gising
- The Beijer Laboratory, Science for Life Laboratory, Department of Medicinal Chemistry, Biomedical Centre, Uppsala University, P.O. Box 574, SE-751 23 Uppsala, Sweden; (J.B.); (M.L.)
| | - Saman Honarnejad
- Pivot Park Screening Centre, Kloosterstraat 9, 5349 AB Oss, The Netherlands; (S.H.); (M.B.)
| | - Maaike Bras
- Pivot Park Screening Centre, Kloosterstraat 9, 5349 AB Oss, The Netherlands; (S.H.); (M.B.)
| | - Gemma L. Baillie
- BioAscent Discovery Ltd., Bo‘Ness Road, Newhouse, Motherwell ML1 5UH, UK; (G.L.B.); (S.P.M.); (P.S.J.); (A.M.)
| | - Stuart P. McElroy
- BioAscent Discovery Ltd., Bo‘Ness Road, Newhouse, Motherwell ML1 5UH, UK; (G.L.B.); (S.P.M.); (P.S.J.); (A.M.)
| | - Philip S. Jones
- BioAscent Discovery Ltd., Bo‘Ness Road, Newhouse, Motherwell ML1 5UH, UK; (G.L.B.); (S.P.M.); (P.S.J.); (A.M.)
| | - Angus Morrison
- BioAscent Discovery Ltd., Bo‘Ness Road, Newhouse, Motherwell ML1 5UH, UK; (G.L.B.); (S.P.M.); (P.S.J.); (A.M.)
| | - Julia Beveridge
- The Beijer Laboratory, Science for Life Laboratory, Department of Medicinal Chemistry, Biomedical Centre, Uppsala University, P.O. Box 574, SE-751 23 Uppsala, Sweden; (J.B.); (M.L.)
| | - Mathias Hallberg
- The Beijer Laboratory, Department of Pharmaceutical Biosciences, Neuropharmacology and Addiction Research, Biomedical Centre, Uppsala University, P.O. Box 591, SE-751 24 Uppsala, Sweden;
| | - Mats Larhed
- The Beijer Laboratory, Science for Life Laboratory, Department of Medicinal Chemistry, Biomedical Centre, Uppsala University, P.O. Box 574, SE-751 23 Uppsala, Sweden; (J.B.); (M.L.)
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Mpakali A, Barla I, Lu L, Ramesh KM, Thomaidis N, Stern LJ, Giastas P, Stratikos E. Mechanisms of Allosteric Inhibition of Insulin-Regulated Aminopeptidase. J Mol Biol 2024; 436:168449. [PMID: 38244767 DOI: 10.1016/j.jmb.2024.168449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 01/12/2024] [Accepted: 01/14/2024] [Indexed: 01/22/2024]
Abstract
Inhibition of Insulin-Regulated Aminopeptidase is being actively explored for the treatment of several human diseases and several classes of inhibitors have been developed although no clinical applications have been reported yet. Here, we combine enzymological analysis with x-ray crystallography to investigate the mechanism employed by two of the most studied inhibitors of IRAP, an aryl sulfonamide and a 2-amino-4H-benzopyran named HFI-419. Although both compounds have been hypothesized to target the enzyme's active site by competitive mechanisms, we discovered that they instead target previously unidentified proximal allosteric sites and utilize non-competitive inhibition mechanisms. X-ray crystallographic analysis demonstrated that the aryl sulfonamide stabilizes the closed, more active, conformation of the enzyme whereas HFI-419 locks the enzyme in a semi-open, and likely less active, conformation. HFI-419 potency is substrate-dependent and fails to effectively block the degradation of the physiological substrate cyclic peptide oxytocin. Our findings demonstrate alternative mechanisms for inhibiting IRAP through allosteric sites and conformational restricting and suggest that the pharmacology of HFI-419 may be more complicated than initially considered. Such conformation-specific interactions between IRAP and small molecules can be exploited for the design of more effective second-generation allosteric inhibitors.
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Affiliation(s)
- Anastasia Mpakali
- Laboratory of Biochemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece; National Centre for Scientific Research Demokritos, Athens 15341, Greece
| | - Ioanna Barla
- Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece
| | - Liying Lu
- Department of Pathology, UMass Chan Medical School, Worcester, MA 01650, USA
| | - Karthik M Ramesh
- Department of Pathology, UMass Chan Medical School, Worcester, MA 01650, USA
| | - Nikolaos Thomaidis
- Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece
| | - Lawrence J Stern
- Department of Pathology, UMass Chan Medical School, Worcester, MA 01650, USA
| | - Petros Giastas
- Department of Biotechnology, School of Applied Biology & Biotechnology, Agricultural University of Athens, Athens 11855, Greece
| | - Efstratios Stratikos
- Laboratory of Biochemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece; National Centre for Scientific Research Demokritos, Athens 15341, Greece.
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Vear A, Thalmann C, Youngs K, Hannan N, Gaspari T, Chai SY. Development of a sandwich ELISA to detect circulating, soluble IRAP as a potential disease biomarker. Sci Rep 2023; 13:17565. [PMID: 38001104 PMCID: PMC10673851 DOI: 10.1038/s41598-023-44038-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/03/2023] [Indexed: 11/26/2023] Open
Abstract
There is growing interest in the use of the enzyme, insulin regulated aminopeptidase (IRAP), as a biomarker for conditions such as cardio-metabolic diseases and ischemic stroke, with upregulation in its tissue expression in these conditions. However, quantification of circulating IRAP has been hampered by difficulties in detecting release of the truncated, soluble form of this enzyme into the blood stream. The current study aimed to develop a sandwich ELISA using novel antibodies directed towards the soluble portion of IRAP (sIRAP), to improve accuracy in detection and quantification of low levels of sIRAP in plasma. A series of novel anti-IRAP antibodies were developed and found to be highly specific for sIRAP in Western blots. A sandwich ELISA was then optimised using two distinct antibody combinations to detect sIRAP in the low nanogram range (16-500 ng/ml) with a sensitivity of 9 ng/ml and intra-assay variability < 10%. Importantly, the clinical validity of the ELISA was verified by the detection of significant increases in the levels of sIRAP throughout gestation in plasma samples from pregnant women. The specific and sensitive sandwich ELISA described in this study has the potential to advance the development of IRAP as a biomarker for certain diseases.
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Affiliation(s)
- Anika Vear
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Claudia Thalmann
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Kristina Youngs
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Natalie Hannan
- Department of Obstetrics and Gynaecology, University of Melbourne, Heidelberg, VIC, 3084, Australia
- Mercy Perinatal, Mercy Hospital for Women, Heidelberg, VIC, 3084, Australia
| | - Tracey Gaspari
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Siew Yeen Chai
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia.
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