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Reidenbach AG, Mesleh MF, Casalena D, Vallabh SM, Dahlin JL, Leed AJ, Chan AI, Usanov DL, Yehl JB, Lemke CT, Campbell AJ, Shah RN, Shrestha OK, Sacher JR, Rangel VL, Moroco JA, Sathappa M, Nonato MC, Nguyen KT, Wright SK, Liu DR, Wagner FF, Kaushik VK, Auld DS, Schreiber SL, Minikel EV. Multimodal small-molecule screening for human prion protein binders. J Biol Chem 2020; 295:13516-13531. [PMID: 32723867 PMCID: PMC7521658 DOI: 10.1074/jbc.ra120.014905] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/21/2020] [Indexed: 12/16/2022] Open
Abstract
Prion disease is a rapidly progressive neurodegenerative disorder caused by misfolding and aggregation of the prion protein (PrP), and there are currently no therapeutic options. PrP ligands could theoretically antagonize prion formation by protecting the native protein from misfolding or by targeting it for degradation, but no validated small-molecule binders have been discovered to date. We deployed a variety of screening methods in an effort to discover binders of PrP, including 19F-observed and saturation transfer difference (STD) NMR spectroscopy, differential scanning fluorimetry (DSF), DNA-encoded library selection, and in silico screening. A single benzimidazole compound was confirmed in concentration-response, but affinity was very weak (Kd > 1 mm), and it could not be advanced further. The exceptionally low hit rate observed here suggests that PrP is a difficult target for small-molecule binders. Whereas orthogonal binder discovery methods could yield high-affinity compounds, non-small-molecule modalities may offer independent paths forward against prion disease.
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Affiliation(s)
- Andrew G Reidenbach
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Michael F Mesleh
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Dominick Casalena
- Facilitated Access to Screening Technologies (FAST) Lab, Novartis Institutes for Biomedical Research (NIBR), Cambridge, Massachusetts, USA
| | - Sonia M Vallabh
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Prion Alliance, Cambridge, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Jayme L Dahlin
- Harvard Medical School, Boston, Massachusetts, USA; Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Alison J Leed
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Alix I Chan
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Dmitry L Usanov
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Jenna B Yehl
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Christopher T Lemke
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Arthur J Campbell
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Rishi N Shah
- Undergraduate Research Opportunities Program (UROP), Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Om K Shrestha
- Facilitated Access to Screening Technologies (FAST) Lab, Novartis Institutes for Biomedical Research (NIBR), Cambridge, Massachusetts, USA
| | - Joshua R Sacher
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Victor L Rangel
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Jamie A Moroco
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Murugappan Sathappa
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Maria Cristina Nonato
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Kong T Nguyen
- Artificial Intelligence Molecular Screen (AIMS) Awards Program, Atomwise, San Francisco, California, USA
| | - S Kirk Wright
- Facilitated Access to Screening Technologies (FAST) Lab, Novartis Institutes for Biomedical Research (NIBR), Cambridge, Massachusetts, USA
| | - David R Liu
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA; Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Florence F Wagner
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Virendar K Kaushik
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Douglas S Auld
- Facilitated Access to Screening Technologies (FAST) Lab, Novartis Institutes for Biomedical Research (NIBR), Cambridge, Massachusetts, USA
| | - Stuart L Schreiber
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Eric Vallabh Minikel
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; Prion Alliance, Cambridge, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA.
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Reidenbach AG, Minikel EV, Zhao HT, Guzman SG, Leed AJ, Mesleh MF, Kordasiewicz HB, Schreiber SL, Vallabh SM. Characterization of the Prion Protein Binding Properties of Antisense Oligonucleotides. Biomolecules 2019; 10:E1. [PMID: 31861275 PMCID: PMC7022474 DOI: 10.3390/biom10010001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 01/08/2023] Open
Abstract
Antisense oligonucleotides (ASOs) designed to lower prion protein (PrP) expression in the brain through RNase H1-mediated degradation of PrP RNA are in development as prion disease therapeutics. ASOs were previously reported to sequence-independently interact with PrP and inhibit prion accumulation in cell culture, yet in vivo studies using a new generation of ASOs found that only PrP-lowering sequences were effective at extending survival. Cerebrospinal fluid (CSF) PrP has been proposed as a pharmacodynamic biomarker for trials of such ASOs, but is only interpretable if PrP lowering is indeed the relevant mechanism of action in vivo and if measurement of PrP is unconfounded by any PrP-ASO interaction. Here, we examine the PrP-binding and antiprion properties of ASOs in vitro and in cell culture. Binding parameters determined by isothermal titration calorimetry were similar across all ASOs tested, indicating that ASOs of various chemistries bind full-length recombinant PrP with low- to mid-nanomolar affinity in a sequence-independent manner. Nuclear magnetic resonance, dynamic light scattering, and visual inspection of ASO-PrP mixtures suggested, however, that this interaction is characterized by the formation of large aggregates, a conclusion further supported by the salt dependence of the affinity measured by isothermal titration calorimetry. Sequence-independent inhibition of prion accumulation in cell culture was observed. The inefficacy of non-PrP-lowering ASOs against prion disease in vivo may be because their apparent activity in vitro is an artifact of aggregation, or because the concentration of ASOs in relevant compartments within the central nervous system (CNS) quickly drops below the effective concentration for sequence-independent antiprion activity after bolus dosing into CSF. Measurements of PrP concentration in human CSF were not impacted by the addition of ASO. These findings support the further development of PrP-lowering ASOs and of CSF PrP as a pharmacodynamic biomarker.
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Affiliation(s)
- Andrew G. Reidenbach
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.G.R.); (E.V.M.); (S.G.G.); (S.L.S.)
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Eric Vallabh Minikel
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.G.R.); (E.V.M.); (S.G.G.); (S.L.S.)
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Prion Alliance, Cambridge, MA 02139, USA
| | - Hien T. Zhao
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA; (H.T.Z.); (H.B.K.)
| | - Stacy G. Guzman
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.G.R.); (E.V.M.); (S.G.G.); (S.L.S.)
- Exceptional Research Opportunities Program (EXROP), Howard Hughes Medical Institute (HHMI), Chevy Chase, MD 20815, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alison J. Leed
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.J.L.); (M.F.M.)
| | - Michael F. Mesleh
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.J.L.); (M.F.M.)
| | | | - Stuart L. Schreiber
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.G.R.); (E.V.M.); (S.G.G.); (S.L.S.)
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Sonia M. Vallabh
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (A.G.R.); (E.V.M.); (S.G.G.); (S.L.S.)
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Prion Alliance, Cambridge, MA 02139, USA
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