1
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Cao X, Zhang Y, Ding Y, Wan Y. Identification of RNA structures and their roles in RNA functions. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00748-6. [PMID: 38926530 DOI: 10.1038/s41580-024-00748-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2024] [Indexed: 06/28/2024]
Abstract
The development of high-throughput RNA structure profiling methods in the past decade has greatly facilitated our ability to map and characterize different aspects of RNA structures transcriptome-wide in cell populations, single cells and single molecules. The resulting high-resolution data have provided insights into the static and dynamic nature of RNA structures, revealing their complexity as they perform their respective functions in the cell. In this Review, we discuss recent technical advances in the determination of RNA structures, and the roles of RNA structures in RNA biogenesis and functions, including in transcription, processing, translation, degradation, localization and RNA structure-dependent condensates. We also discuss the current understanding of how RNA structures could guide drug design for treating genetic diseases and battling pathogenic viruses, and highlight existing challenges and future directions in RNA structure research.
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Affiliation(s)
- Xinang Cao
- Stem Cell and Regenerative Biology, Genome Institute of Singapore, Singapore, Singapore
| | - Yueying Zhang
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, UK
| | - Yiliang Ding
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, UK.
| | - Yue Wan
- Stem Cell and Regenerative Biology, Genome Institute of Singapore, Singapore, Singapore.
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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2
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Tong Y, Zanon PRA, Yang X, Su X, Childs-Disney JL, Disney MD. Transcriptome-wide mapping of small-molecule RNA-binding sites in live cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.30.596700. [PMID: 38853865 PMCID: PMC11160777 DOI: 10.1101/2024.05.30.596700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Small molecules targeting RNA can be valuable chemical probes and potential therapeutics. The interactions between small molecules, particularly fragments, and RNA, however, can be difficult to detect due to their modest affinities and short residence times. Here, we describe the procedures for mapping the molecular fingerprints of small molecules in vitro and throughout the human transcriptome in live cells, identifying both the targets bound by the small molecule and the sites of binding therein. For complete details on the use and execution of this protocol, please refer to 1.
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3
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Fang L, Velema WA, Lee Y, Xiao L, Mohsen MG, Kietrys AM, Kool ET. Pervasive transcriptome interactions of protein-targeted drugs. Nat Chem 2023; 15:1374-1383. [PMID: 37653232 DOI: 10.1038/s41557-023-01309-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 07/27/2023] [Indexed: 09/02/2023]
Abstract
The off-target toxicity of drugs targeted to proteins imparts substantial health and economic costs. Proteome interaction studies can reveal off-target effects with unintended proteins; however, little attention has been paid to intracellular RNAs as potential off-targets that may contribute to toxicity. To begin to assess this, we developed a reactivity-based RNA profiling methodology and applied it to uncover transcriptome interactions of a set of Food and Drug Administration-approved small-molecule drugs in vivo. We show that these protein-targeted drugs pervasively interact with the human transcriptome and can exert unintended biological effects on RNA functions. In addition, we show that many off-target interactions occur at RNA loci associated with protein binding and structural changes, allowing us to generate hypotheses to infer the biological consequences of RNA off-target binding. The results suggest that rigorous characterization of drugs' transcriptome interactions may help assess target specificity and potentially avoid toxicity and clinical failures.
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Affiliation(s)
- Linglan Fang
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Willem A Velema
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Yujeong Lee
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Lu Xiao
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | | | - Anna M Kietrys
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Eric T Kool
- Department of Chemistry, Stanford University, Stanford, CA, USA.
- Sarafan ChEM-H Institute, Stanford University, Stanford, CA, USA.
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4
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Signoria I, van der Pol WL, Groen EJN. Innovating spinal muscular atrophy models in the therapeutic era. Dis Model Mech 2023; 16:dmm050352. [PMID: 37787662 PMCID: PMC10565113 DOI: 10.1242/dmm.050352] [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] [Indexed: 10/04/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a severe, monogenetic, neuromuscular disease. A thorough understanding of its genetic cause and the availability of robust models has led to the development and approval of three gene-targeting therapies. This is a unique and exciting development for the field of neuromuscular diseases, many of which remain untreatable. The development of therapies for SMA not only opens the door to future therapeutic possibilities for other genetic neuromuscular diseases, but also informs us about the limitations of such treatments. For example, treatment response varies widely and, for many patients, significant disability remains. Currently available SMA models best recapitulate the severe types of SMA, and these models are genetically and phenotypically more homogeneous than patients. Furthermore, treating patients is leading to a shift in phenotypes with increased variability in SMA clinical presentation. Therefore, there is a need to generate model systems that better reflect these developments. Here, we will first discuss current animal models of SMA and their limitations. Next, we will discuss the characteristics required to future-proof models to assist the field in the development of additional, novel therapies for SMA.
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Affiliation(s)
- Ilaria Signoria
- Department of Neurology and Neurosurgery, UMC Utrecht Brain Center, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands
| | - W. Ludo van der Pol
- Department of Neurology and Neurosurgery, UMC Utrecht Brain Center, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands
| | - Ewout J. N. Groen
- Department of Neurology and Neurosurgery, UMC Utrecht Brain Center, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands
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5
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Gibaut QR, Bush JA, Tong Y, Baisden JT, Taghavi A, Olafson H, Yao X, Childs-Disney JL, Wang ET, Disney MD. Transcriptome-Wide Studies of RNA-Targeted Small Molecules Provide a Simple and Selective r(CUG) exp Degrader in Myotonic Dystrophy. ACS CENTRAL SCIENCE 2023; 9:1342-1353. [PMID: 37521782 PMCID: PMC10375898 DOI: 10.1021/acscentsci.2c01223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Indexed: 08/01/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is caused by a highly structured RNA repeat expansion, r(CUG)exp, harbored in the 3' untranslated region (3' UTR) of dystrophia myotonica protein kinase (DMPK) mRNA and drives disease through a gain-of-function mechanism. A panel of low-molecular-weight fragments capable of reacting with RNA upon UV irradiation was studied for cross-linking to r(CUG)expin vitro, affording perimidin-2-amine diazirine (1) that bound to r(CUG)exp. The interactions between the small molecule and RNA were further studied by nuclear magnetic resonance (NMR) spectroscopy and molecular modeling. Binding of 1 in DM1 myotubes was profiled transcriptome-wide, identifying 12 transcripts including DMPK that were bound by 1. Augmenting the functionality of 1 with cleaving capability created a chimeric degrader that specifically targets r(CUG)exp for elimination. The degrader broadly improved DM1-associated defects as assessed by RNA-seq, while having limited effects on healthy myotubes. This study (i) provides a platform to investigate molecular recognition of ligands directly in disease-affected cells; (ii) illustrates that RNA degraders can be more specific than the binders from which they are derived; and (iii) suggests that repeating transcripts can be selectively degraded due to the presence of multiple ligand binding sites.
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Affiliation(s)
- Quentin
M. R. Gibaut
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica A. Bush
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Yuquan Tong
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jared T. Baisden
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Amirhossein Taghavi
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Hailey Olafson
- Center
for NeuroGenetics, University of Florida, Gainesville, Florida 32610, United States
- Department
of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, United States
| | - Xiyuan Yao
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica L. Childs-Disney
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Eric T. Wang
- Center
for NeuroGenetics, University of Florida, Gainesville, Florida 32610, United States
- Department
of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, United States
| | - Matthew D. Disney
- The
Department of Chemistry, UF Scripps Biomedical
Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
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6
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Zhao Q, Lv X, Dong Y, Hong H, Zheng Y, Yang L, Gong J. IMB5036 overcomes resistance to multiple chemotherapeutic drugs in human cancer cells through pyroptosis by targeting the KH-type splicing regulatory protein. Life Sci 2023; 328:121941. [PMID: 37451400 DOI: 10.1016/j.lfs.2023.121941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/26/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
AIMS IMB5036 is a pyridazinone compound with antiproliferative and antitumour activity against hepatoma and pancreatic cancer. In this study, we attempted to identify the target protein of IMB5036 and test its potential for overcoming multidrug resistance and inducing pyroptosis. MATERIALS AND METHODS We examined the effects of IMB5036 on cancer cells by in vitro assays, a molecular docking model and in vivo tumour models. We performed pull-down experiments using biotinylated IMB5036 and identified the binding proteins. Gene knockdown were used to investigate the oncogenic role of KH-type splicing regulatory protein (KSRP). Western blot was used to detect for mechanism-associated molecules. KEY FINDINGS IMB5036 could overcome resistance to multiple chemotherapeutic drugs at the cellular level and in vivo. Furthermore, IMB5036 was not a P-glycoprotein (P-gp) substrate and downregulated the expression of P-gp. We identified KSRP as a binding protein of IMB5036. The knockdown of KSRP inhibited the proliferation of MCF7 and MCF7/adriamycin (MCF7/ADR) cells. In addition, IMB5036 induced pyroptosis in both MCF7 and MCF7/ADR cells via KSRP. SIGNIFICANCE We found IMB5036 binds to KSRP and overcomes multidrug resistance via gasdermin E (GSDME)-dependent pyroptosis.
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Affiliation(s)
- Qi Zhao
- Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Department of Pharmacology, Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xing Lv
- Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Department of Biochemistry & Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, China
| | - Yanqun Dong
- Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hanyu Hong
- Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Department of Biopharmaceuticals, School of Pharmaceutics Sciences, Wenzhou Medical University, Zhejiang, China
| | - Yanbo Zheng
- Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Lijun Yang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, Shanxi, China.
| | - Jianhua Gong
- Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
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7
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Ottesen EW, Singh NN, Luo D, Kaas B, Gillette B, Seo J, Jorgensen H, Singh RN. Diverse targets of SMN2-directed splicing-modulating small molecule therapeutics for spinal muscular atrophy. Nucleic Acids Res 2023; 51:5948-5980. [PMID: 37026480 PMCID: PMC10325915 DOI: 10.1093/nar/gkad259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/13/2023] [Accepted: 03/28/2023] [Indexed: 04/08/2023] Open
Abstract
Designing an RNA-interacting molecule that displays high therapeutic efficacy while retaining specificity within a broad concentration range remains a challenging task. Risdiplam is an FDA-approved small molecule for the treatment of spinal muscular atrophy (SMA), the leading genetic cause of infant mortality. Branaplam is another small molecule which has undergone clinical trials. The therapeutic merit of both compounds is based on their ability to restore body-wide inclusion of Survival Motor Neuron 2 (SMN2) exon 7 upon oral administration. Here we compare the transcriptome-wide off-target effects of these compounds in SMA patient cells. We captured concentration-dependent compound-specific changes, including aberrant expression of genes associated with DNA replication, cell cycle, RNA metabolism, cell signaling and metabolic pathways. Both compounds triggered massive perturbations of splicing events, inducing off-target exon inclusion, exon skipping, intron retention, intron removal and alternative splice site usage. Our results of minigenes expressed in HeLa cells provide mechanistic insights into how these molecules targeted towards a single gene produce different off-target effects. We show the advantages of combined treatments with low doses of risdiplam and branaplam. Our findings are instructive for devising better dosing regimens as well as for developing the next generation of small molecule therapeutics aimed at splicing modulation.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Diou Luo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Bailey Kaas
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Benjamin J Gillette
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Hannah J Jorgensen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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8
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Chingarande RG, Tian K, Kuang Y, Sarangee A, Hou C, Ma E, Ren J, Hawkins S, Kim J, Adelstein R, Chen S, Gillis KD, Gu LQ. Real-time label-free detection of dynamic aptamer-small molecule interactions using a nanopore nucleic acid conformational sensor. Proc Natl Acad Sci U S A 2023; 120:e2108118120. [PMID: 37276386 PMCID: PMC10268594 DOI: 10.1073/pnas.2108118120] [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: 05/18/2021] [Accepted: 04/14/2023] [Indexed: 06/07/2023] Open
Abstract
Nucleic acids can undergo conformational changes upon binding small molecules. These conformational changes can be exploited to develop new therapeutic strategies through control of gene expression or triggering of cellular responses and can also be used to develop sensors for small molecules such as neurotransmitters. Many analytical approaches can detect dynamic conformational change of nucleic acids, but they need labeling, are expensive, and have limited time resolution. The nanopore approach can provide a conformational snapshot for each nucleic acid molecule detected, but has not been reported to detect dynamic nucleic acid conformational change in response to small -molecule binding. Here we demonstrate a modular, label-free, nucleic acid-docked nanopore capable of revealing time-resolved, small molecule-induced, single nucleic acid molecule conformational transitions with millisecond resolution. By using the dopamine-, serotonin-, and theophylline-binding aptamers as testbeds, we found that these nucleic acids scaffolds can be noncovalently docked inside the MspA protein pore by a cluster of site-specific charged residues. This docking mechanism enables the ion current through the pore to characteristically vary as the aptamer undergoes conformational changes, resulting in a sequence of current fluctuations that report binding and release of single ligand molecules from the aptamer. This nanopore tool can quantify specific ligands such as neurotransmitters, elucidate nucleic acid-ligand interactions, and pinpoint the nucleic acid motifs for ligand binding, showing the potential for small molecule biosensing, drug discovery assayed via RNA and DNA conformational changes, and the design of artificial riboswitch effectors in synthetic biology.
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Affiliation(s)
- Rugare G. Chingarande
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO65211
| | - Kai Tian
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO65211
| | - Yu Kuang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO65211
| | - Aby Sarangee
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Chengrui Hou
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Emily Ma
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Jarett Ren
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Sam Hawkins
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Joshua Kim
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Ray Adelstein
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Sally Chen
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
| | - Kevin D. Gillis
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO65211
| | - Li-Qun Gu
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, MO65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO65211
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9
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Zhang L, Xie X, Djokovic N, Nikolic K, Kosenkov D, Abendroth F, Vázquez O. Reversible Control of RNA Splicing by Photoswitchable Small Molecules. J Am Chem Soc 2023. [PMID: 37276581 DOI: 10.1021/jacs.3c03275] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dynamics are intrinsic to both RNA function and structure. Yet, the available means to precisely provide RNA-based processes with spatiotemporal resolution are scarce. Here, our work pioneers a reversible approach to regulate RNA splicing within primary patient-derived cells by synthetic photoswitches. Our small molecule enables conditional real-time control at mRNA and protein levels. NMR experiments, together with theoretical calculations, photochemical characterization, fluorescence polarization measurements, and living cell-based assays, confirmed light-dependent exon inclusion as well as an increase in the target functional protein. Therefore, we first demonstrated the potential of photopharmacology modulation in splicing, tweaking the current optochemical toolkit. The timeliness on the consolidation of RNA research as the driving force toward therapeutical innovation holds the promise that our approach will contribute to redrawing the vision of RNA.
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Affiliation(s)
- Lei Zhang
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
| | - Xiulan Xie
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
| | - Nemanja Djokovic
- Department of Pharmaceutical Chemistry, University of Belgrade, Belgrade, 11000, Serbia
| | - Katarina Nikolic
- Department of Pharmaceutical Chemistry, University of Belgrade, Belgrade, 11000, Serbia
| | - Dmitri Kosenkov
- Department of Chemistry and Physics, Monmouth University, West Long Branch, New Jersey 07764, United States
| | - Frank Abendroth
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
| | - Olalla Vázquez
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
- Center for Synthetic Microbiology (SYNMIKRO), University of Marburg, Marburg, D-35043, Germany
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10
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Yang X, Childs-Disney JL, Disney MD. A meditation on accelerating the development of small molecule medicines targeting RNA. Expert Opin Drug Discov 2023; 18:115-117. [PMID: 35658797 PMCID: PMC9878438 DOI: 10.1080/17460441.2022.2084528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/27/2022] [Indexed: 02/06/2023]
Affiliation(s)
- Xueyi Yang
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458
| | | | - Matthew D. Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458
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11
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Torroba B, Macabuag N, Haisma EM, O'Neill A, Herva ME, Redis RS, Templin MV, Black LE, Fischer DF. RNA-based drug discovery for spinal muscular atrophy: a story of small molecules and antisense oligonucleotides. Expert Opin Drug Discov 2023; 18:181-192. [PMID: 36408582 DOI: 10.1080/17460441.2022.2149733] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Spinal Muscular Atrophy (SMA), the second most prevalent autosomal genetic disease affecting infants, is caused by the lack of SMN1, which encodes a neuron functioning vital protein, SMN. Improving exon 7 splicing in the paralogous gene SMN2, also coding for SMN protein, increases protein production efficiency from SMN2 to overcome the genetic deficit in SMN1. Several molecular mechanisms have been investigated to improve SMN2 functional splicing. AREAS COVERED This manuscript will cover two of the three mechanistically distinct available treatment options for SMA, both targeting the SMN2 splicing mechanism. The first therapeutic, nusinersen (Spinraza®, 2017), is an antisense oligonucleotide (ASO) targeting the splicing inhibitory sequence in the intron downstream of exon 7 from SMN2, thus increasing exon 7 inclusion. The second drug is a small molecule, risdiplam (Evrysdi®, 2021), that enhances the binding of splice factors and also promotes exon 7 inclusion. Both therapies, albeit through different mechanisms, increase full-length SMN protein expression. EXPERT OPINION Nusinersen and risdiplam have directly helped SMA patients and families, but they also herald a sea change in drug development for genetic diseases. This piece aims to draw parallels between both development histories; this may help chart the course for future targeted agents.
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Affiliation(s)
| | | | | | - Amy O'Neill
- Charles River Laboratories, Saffron Walden, UK
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12
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Haga CL, Phinney DG. Strategies for targeting RNA with small molecule drugs. Expert Opin Drug Discov 2023; 18:135-147. [PMID: 35934990 DOI: 10.1080/17460441.2022.2111414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Historically, therapeutic treatment of disease has been restricted to targeting proteins. Of the approximately 20,000 translated human proteins, approximately 1600 are associated with diseases. Strikingly, less than 15% of disease-associated proteins are predicted or known to be 'druggable.' While the concept and narrative of protein druggability continue to evolve with the development of novel technological and pharmacological advances, most of the human proteome remains undrugged. Recent genomic studies indicate that less than 2% of the human genome encodes for proteins, and while as much as 75% of the genome is transcribed, RNA has largely been ignored as a druggable target for therapeutic interventions. AREAS COVERED This review delineates the theory and techniques involved in the development of small molecule inhibitors of RNAs from brute force, high-throughput screening technologies to de novo molecular design using computational machine and deep learning. We will also highlight the potential pitfalls and limitations of targeting RNA with small molecules. EXPERT OPINION Although significant advances have recently been made in developing systems to identify small molecule inhibitors of RNAs, many challenges remain. Focusing on RNA structure and ligand binding sites may help bring drugging RNA in line with traditional protein drug targeting.
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Affiliation(s)
- Christopher L Haga
- Department of Molecular Medicine, UF Scripps Biomedical Research, Jupiter, FL, USA
| | - Donald G Phinney
- Department of Molecular Medicine, UF Scripps Biomedical Research, Jupiter, FL, USA
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13
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Gibaut QMR, Akahori Y, Bush JA, Taghavi A, Tanaka T, Aikawa H, Ryan LS, Paegel BM, Disney MD. Study of an RNA-Focused DNA-Encoded Library Informs Design of a Degrader of a r(CUG) Repeat Expansion. J Am Chem Soc 2022; 144:21972-21979. [PMID: 36399603 PMCID: PMC9878440 DOI: 10.1021/jacs.2c08883] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A solid-phase DNA-encoded library (DEL) was studied for binding the RNA repeat expansion r(CUG)exp, the causative agent of the most common form of adult-onset muscular dystrophy, myotonic dystrophy type 1 (DM1). A variety of uncharged and novel RNA binders were identified to selectively bind r(CUG)exp by using a two-color flow cytometry screen. The cellular activity of one binder was augmented by attaching it with a module that directly cleaves r(CUG)exp. In DM1 patient-derived muscle cells, the compound specifically bound r(CUG)exp and allele-specifically eliminated r(CUG)exp, improving disease-associated defects. The approaches herein can be used to identify and optimize ligands and bind RNA that can be further augmented for functionality including degradation.
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Affiliation(s)
- Quentin M. R. Gibaut
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Yoshihiro Akahori
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica A. Bush
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Amirhossein Taghavi
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Toru Tanaka
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Haruo Aikawa
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Lucas S. Ryan
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Brian M. Paegel
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States; Department of Chemistry and Pharmaceutical Sciences, University of California, Irvine, California 92617, United States
| | - Matthew D. Disney
- Department of Chemistry, UF Scripps Biomedical Research and The Scripps Research Institute, Jupiter, Florida 33458, United States
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14
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Alternative RNA Conformations: Companion or Combatant. Genes (Basel) 2022; 13:genes13111930. [DOI: 10.3390/genes13111930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/04/2022] Open
Abstract
RNA molecules, in one form or another, are involved in almost all aspects of cell physiology, as well as in disease development. The diversity of the functional roles of RNA comes from its intrinsic ability to adopt complex secondary and tertiary structures, rivaling the diversity of proteins. The RNA molecules form dynamic ensembles of many interconverting conformations at a timescale of seconds, which is a key for understanding how they execute their cellular functions. Given the crucial role of RNAs in various cellular processes, we need to understand the RNA molecules from a structural perspective. Central to this review are studies aimed at revealing the regulatory role of conformational equilibria in RNA in humans to understand genetic diseases such as cancer and neurodegenerative diseases, as well as in pathogens such as bacteria and viruses so as to understand the progression of infectious diseases. Furthermore, we also summarize the prior studies on the use of RNA structures as platforms for the rational design of small molecules for therapeutic applications.
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15
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Childs-Disney JL, Yang X, Gibaut QMR, Tong Y, Batey RT, Disney MD. Targeting RNA structures with small molecules. Nat Rev Drug Discov 2022; 21:736-762. [PMID: 35941229 PMCID: PMC9360655 DOI: 10.1038/s41573-022-00521-4] [Citation(s) in RCA: 154] [Impact Index Per Article: 77.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2022] [Indexed: 01/07/2023]
Abstract
RNA adopts 3D structures that confer varied functional roles in human biology and dysfunction in disease. Approaches to therapeutically target RNA structures with small molecules are being actively pursued, aided by key advances in the field including the development of computational tools that predict evolutionarily conserved RNA structures, as well as strategies that expand mode of action and facilitate interactions with cellular machinery. Existing RNA-targeted small molecules use a range of mechanisms including directing splicing - by acting as molecular glues with cellular proteins (such as branaplam and the FDA-approved risdiplam), inhibition of translation of undruggable proteins and deactivation of functional structures in noncoding RNAs. Here, we describe strategies to identify, validate and optimize small molecules that target the functional transcriptome, laying out a roadmap to advance these agents into the next decade.
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Affiliation(s)
| | - Xueyi Yang
- Department of Chemistry, Scripps Research, Jupiter, FL, USA
| | | | - Yuquan Tong
- Department of Chemistry, Scripps Research, Jupiter, FL, USA
| | - Robert T Batey
- Department of Biochemistry, University of Colorado, Boulder, CO, USA.
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16
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Rozza R, Janoš P, Spinello A, Magistrato A. Role of computational and structural biology in the development of small-molecule modulators of the spliceosome. Expert Opin Drug Discov 2022; 17:1095-1109. [PMID: 35983696 DOI: 10.1080/17460441.2022.2114452] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
INTRODUCTION RNA splicing is a pivotal step of eukaryotic gene expression during which the introns are excised from the precursor (pre-)RNA and the exons are joined together to form mature RNA products (i.e a protein-coding mRNA or long non-coding (lnc)RNAs). The spliceosome, a complex ribonucleoprotein machine, performs pre-RNA splicing with extreme precision. Deregulated splicing is linked to cancer, genetic, and neurodegenerative diseases. Hence, the discovery of small-molecules targeting core spliceosome components represents an appealing therapeutic opportunity. AREA COVERED Several atomic-level structures of the spliceosome and distinct splicing-modulators bound to its protein/RNA components have been solved. Here, we review recent advances in the discovery of small-molecule splicing-modulators, discuss opportunities and challenges for their therapeutic applicability, and showcase how structural data and/or all-atom simulations can illuminate key facets of their mechanism, thus contributing to future drug-discovery campaigns. EXPERT OPINION This review highlights the potential of modulating pre-RNA splicing with small-molecules, and anticipates how the synergy of computer and wet-lab experiments will enrich our understanding of splicing regulation/deregulation mechanisms. This information will aid future structure-based drug-discovery efforts aimed to expand the currently limited portfolio of selective splicing-modulators.
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Affiliation(s)
- Riccardo Rozza
- National Research Council of Italy, Institute of Materials-foundry (CNR-IOM) C/o SISSA, Trieste, Italy
| | - Pavel Janoš
- National Research Council of Italy, Institute of Materials-foundry (CNR-IOM) C/o SISSA, Trieste, Italy
| | - Angelo Spinello
- Department of Biological, Chemical and Pharmaceutical Sciences, University of Palermo, Palermo, Italy
| | - Alessandra Magistrato
- National Research Council of Italy, Institute of Materials-foundry (CNR-IOM) C/o SISSA, Trieste, Italy
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17
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Sexton AN, Vandivier LE, Petter JC, Mukherjee H, Craig Blain J. Determination of RNA-ligand interactions with the photoaffinity platform PEARL-seq. Methods 2022; 205:83-88. [PMID: 35764246 DOI: 10.1016/j.ymeth.2022.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/29/2022] [Accepted: 06/23/2022] [Indexed: 10/17/2022] Open
Abstract
In the development of therapeutics, it is important to establish engagement of a compound to its intended target and identify other targets it binds to. Methods for demonstrating target engagement in the growing field of RNA-targeted therapeutics are therefore needed. We present a detailed protocol for Photoaffinity Evaluation of RNA Ligation-Sequencing (PEARL-seq), a platform for determining interactions between small molecule ligands and their target RNA(s). PEARL-seq allows detection of binding and crosslinking events with single nucleotide resolution and allows measurement of enrichment of the target RNA relative to all other RNAs. PEARL-seq is a valuable tool in the effort to verify bona fide RNA-ligand interactions.
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Affiliation(s)
- Alec N Sexton
- Arrakis Therapeutics, 828 Winter Street, Waltham MA, USA
| | | | | | | | - J Craig Blain
- Arrakis Therapeutics, 828 Winter Street, Waltham MA, USA
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18
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Tong Y, Gibaut QMR, Rouse W, Childs-Disney JL, Suresh BM, Abegg D, Choudhary S, Akahori Y, Adibekian A, Moss WN, Disney MD. Transcriptome-Wide Mapping of Small-Molecule RNA-Binding Sites in Cells Informs an Isoform-Specific Degrader of QSOX1 mRNA. J Am Chem Soc 2022; 144:11620-11625. [PMID: 35737519 PMCID: PMC9594100 DOI: 10.1021/jacs.2c01929] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The interactions between cellular RNAs in MDA-MB-231 triple negative breast cancer cells and a panel of small molecules appended with a diazirine cross-linking moiety and an alkyne tag were probed transcriptome-wide in live cells. The alkyne tag allows for facile pull-down of cellular RNAs bound by each small molecule, and the enrichment of each RNA target defines the compound's molecular footprint. Among the 34 chemically diverse small molecules studied, six bound and enriched cellular RNAs. The most highly enriched interaction occurs between the novel RNA-binding compound F1 and a structured region in the 5' untranslated region of quiescin sulfhydryl oxidase 1 isoform a (QSOX1-a), not present in isoform b. Additional studies show that F1 specifically bound RNA over DNA and protein; that is, we studied the entire DNA, RNA, and protein interactome. This interaction was used to design a ribonuclease targeting chimera (RIBOTAC) to locally recruit Ribonuclease L to degrade QSOX1 mRNA in an isoform-specific manner, as QSOX1-a, but not QSOX1-b, mRNA and protein levels were reduced. The RIBOTAC alleviated QSOX1-mediated phenotypes in cancer cells. This approach can be broadly applied to discover ligands that bind RNA in cells, which could be bioactive themselves or augmented with functionality such as targeted degradation.
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Affiliation(s)
- Yuquan Tong
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Quentin M R Gibaut
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Warren Rouse
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Jessica L Childs-Disney
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Blessy M Suresh
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Daniel Abegg
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Shruti Choudhary
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Yoshihiro Akahori
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Alexander Adibekian
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Walter N Moss
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Matthew D Disney
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
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19
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Kanda S, Moulton E, Butchbach MER. Effects of inhibitors of SLC9A-type sodium-protein exchangers on Survival Motor Neuron 2 ( SMN2) mRNA splicing and expression. Mol Pharmacol 2022; 102:92-105. [PMID: 35667685 PMCID: PMC9341265 DOI: 10.1124/molpharm.122.000529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/09/2022] [Indexed: 11/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive, pediatric-onset disorder caused by the loss of spinal motor neurons thereby leading to muscle atrophy. SMA is caused by the loss of or mutations in the survival motor neuron 1 (SMN1) gene. SMN1 is duplicated in humans to give rise to the paralogous SMN2 gene. This paralog is nearly identical except for a cytosine to thymine (C-to-T) transition within an exonic splicing enhancer (ESE) element within exon 7. As a result, the majority of SMN2 transcripts lack exon 7 (SMNΔ7) which produces a truncated and unstable SMN protein. Since SMN2 copy number is inversely related to disease severity, it is a well-established target for SMA therapeutics development. 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of sodium/proton exchangers (NHEs), has previously been shown to increase exon 7 inclusion and SMN protein levels in SMA cells. In this study, NHE inhibitors were evaluated for their ability to modulate SMN2 expression. EIPA as well as 5-(N,N-hexamethylene)amiloride (HMA) increase exon 7 inclusion in SMN2 splicing reporter lines as well as in SMA fibroblasts. The EIPA-induced exon 7 inclusion occurs via a unique mechanism that does not involve previously identified splicing factors. Transcriptome analysis identified novel targets, including TIA1 and FABP3, for further characterization. EIPA and HMA are more selective at inhibiting the NHE5 isoform, which is expressed in fibroblasts as well as in neuronal cells. These results show that NHE5 inhibition increases SMN2 expression and may be a novel target for therapeutics development. Significance Statement This study demonstrates a molecular mechanism by which inhibitors of the sodium-protein exchanger increase the alternative splicing of SMN2 in spinal muscular atrophy cells. NHE5 selective inhibitors increase the inclusion of full-length SMN2 mRNAs by targeting TIA1 and FABP3 expression, which is distinct from other small molecule regulators of SMN2 alternative splicing. This study provides a novel means to increase full-length SMN2 expression and a novel target for therapeutics development.
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Affiliation(s)
- Sambee Kanda
- Biological Sciences, University of Delaware, United States
| | - Emily Moulton
- Biomedical Research, Nemours Children's Hospital Delaware, United States
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20
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Abstract
Being able to effectively target RNA with potent ligands will open up a large number of potential therapeutic options. The knowledge on how to achieve this is ever expanding but an important question that remains open is what chemical matter is suitable to achieve this goal. The high flexibility of an RNA as well as its more limited chemical diversity and featureless binding sites can be difficult to target selectively but can be addressed by well-designed cyclic peptides. In this review we will provide an overview of reported cyclic peptide ligands for therapeutically relevant RNA targets and discuss the methods used to discover them. We will also provide critical insights into the properties required for potent and selective interaction and suggestions on how to assess these parameters. The use of cyclic peptides to target RNA is still in its infancy but the lessons learned from past examples can be adopted for the development of novel potent and selective ligands.
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Affiliation(s)
- Sunit Pal
- Chemical Genomics Centre of the Max Planck Society, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Peter 't Hart
- Chemical Genomics Centre of the Max Planck Society, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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21
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Yamamura T, Horinouchi T, Aoto Y, Lennon R, Nozu K. The Contribution of COL4A5 Splicing Variants to the Pathogenesis of X-Linked Alport Syndrome. Front Med (Lausanne) 2022; 9:841391. [PMID: 35211492 PMCID: PMC8861460 DOI: 10.3389/fmed.2022.841391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/10/2022] [Indexed: 11/25/2022] Open
Abstract
X-linked Alport syndrome (XLAS) is caused by pathogenic variants in COL4A5 and is characterized by progressive kidney disease, hearing loss, and ocular abnormalities. Recent advances in genetic analysis and further understanding of genotype-phenotype correlations in affected male patients raises the importance of detecting splicing variants in COL4A5. Aberrant splicing of COL4A5 is caused not only by canonical splice site variants but also non-canonical splice site variants such as deep intronic changes or even substitutions in exons. Patients with splicing variants account for ~15% of all cases in XLAS. In addition, it has been shown that there is a significant difference in kidney survival depending on the aberrant splicing patterns of transcripts- in particular in-frame or out-of-frame nucleotide changes in transcripts. Therefore, cDNA analysis of patient mRNA is necessary to determine the impact of splice site variants and to confirm a diagnosis of XLAS and to predict the kidney prognosis. However, it is usually difficult to amplify COL4A5 transcripts extracted from peripheral blood leukocytes. For these cases, in vitro minigene assays or RNA sequence extracted from urine derived cells can confirm aberrant splicing patterns. Moreover, controlling aberrant splicing by nucleic acids or small molecular compounds in genetic diseases are attracting attention as a potential therapeutic strategy. Here, we review the frequency of splicing variants in COL4A5, the latest diagnostic strategies, and the prospects for new therapeutic approaches.
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Affiliation(s)
- Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.,Wellcome Centre for Cell-Matrix Research, Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom.,Department of Paediatric Nephrology, Royal Manchester Children's Hospital, Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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22
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Chappie TA, Abdelmessih M, Ambroise CW, Boehm M, Cai M, Green M, Guilmette E, Steppan CM, Stevens LM, Wei L, Xi S, Hasson SA. Discovery of Small-Molecule CD33 Pre-mRNA Splicing Modulators. ACS Med Chem Lett 2022; 13:55-62. [PMID: 35059124 PMCID: PMC8762744 DOI: 10.1021/acsmedchemlett.1c00396] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 12/29/2021] [Indexed: 01/16/2023] Open
Abstract
CD33/Siglec 3 is a myeloid lineage cell surface receptor that is known to regulate microglia activity. Multiple genome-wide association studies (GWAS) have identified genetic variants in the CD33 gene that convey protection from late-onset Alzheimer's disease. Furthermore, mechanistic studies into GWAS-linked variants suggest that disease protection is attributed to the alternative splicing of exon 2 of the CD33 pre-mRNA. Using a phenomimetic screen, a series of compounds were found to enhance the exclusion of CD33 exon 2, acting as a chemomimetic of the GWAS-linked gene variants. Additional studies confirmed that meyloid lineage cells treated with several of these compounds have a reduced full-length V-domain containing CD33 protein, while targeted RNA-seq concordantly demonstrated that compound 1 increases exon 2 skipping in cellular mRNA pools. These studies demonstrate how pharmacological interventions can be used to manipulate disease-relevant pre-mRNA splicing and provide a starting point for future efforts to identify small molecules that alter neuroimmune function that is rooted in the human biology of neurodegenerative disease.
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Affiliation(s)
- Thomas A. Chappie
- Internal
Medicine Medicinal Chemistry, Pfizer, Inc., Cambridge, Massachusetts 02139, United States,
| | - Mario Abdelmessih
- Primary
Pharmacology Group, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Claude W. Ambroise
- Internal
Medicine Research Unit, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Markus Boehm
- Internal
Medicine Medicinal Chemistry, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Mi Cai
- Internal
Medicine Research Unit, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Michael Green
- Internal
Medicine Medicinal Chemistry, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Edward Guilmette
- Internal
Medicine Research Unit, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Claire M. Steppan
- Primary
Pharmacology Group, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Lucy M. Stevens
- Primary
Pharmacology Group, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Liuqing Wei
- Internal
Medicine Medicinal Chemistry, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Simon Xi
- Internal
Medicine Research Unit, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
| | - Samuel A. Hasson
- Internal
Medicine Research Unit, Pfizer, Inc., Cambridge, Massachusetts 02139, United States
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23
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Abstract
Targeting of pre-mRNA splicing has yielded a rich variety of strategies for altering gene expression as a treatment for disease. The search for therapeutics that can modulate splicing has been dominated by antisense oligonucleotides (ASOs) and small molecule compounds, with each platform achieving remarkably effective results in the clinic. The success of RNA-targeting drugs has led to the exploration of new strategies to expand the repertoire of this type of therapeutic. Here, we discuss some of the more common causes of faulty gene expression and provide examples of approaches that have been developed to target and correct these defects for therapeutic value.
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Affiliation(s)
- Jessica L Centa
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Michelle L Hastings
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA.
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24
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Balaratnam S, Rhodes C, Bume DD, Connelly C, Lai CC, Kelley JA, Yazdani K, Homan PJ, Incarnato D, Numata T, Schneekloth Jr JS. A chemical probe based on the PreQ 1 metabolite enables transcriptome-wide mapping of binding sites. Nat Commun 2021; 12:5856. [PMID: 34615874 PMCID: PMC8494917 DOI: 10.1038/s41467-021-25973-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 08/26/2021] [Indexed: 02/08/2023] Open
Abstract
The role of metabolite-responsive riboswitches in regulating gene expression in bacteria is well known and makes them useful systems for the study of RNA-small molecule interactions. Here, we study the PreQ1 riboswitch system, assessing sixteen diverse PreQ1-derived probes for their ability to selectively modify the class-I PreQ1 riboswitch aptamer covalently. For the most active probe (11), a diazirine-based photocrosslinking analog of PreQ1, X-ray crystallography and gel-based competition assays demonstrated the mode of binding of the ligand to the aptamer, and functional assays demonstrated that the probe retains activity against the full riboswitch. Transcriptome-wide mapping using Chem-CLIP revealed a highly selective interaction between the bacterial aptamer and the probe. In addition, a small number of RNA targets in endogenous human transcripts were found to bind specifically to 11, providing evidence for candidate PreQ1 aptamers in human RNA. This work demonstrates a stark influence of linker chemistry and structure on the ability of molecules to crosslink RNA, reveals that the PreQ1 aptamer/ligand pair are broadly useful for chemical biology applications, and provides insights into how PreQ1, which is similar in structure to guanine, interacts with human RNAs.
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Affiliation(s)
- Sumirtha Balaratnam
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - Curran Rhodes
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - Desta Doro Bume
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - Colleen Connelly
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - Christopher C. Lai
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - James A. Kelley
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - Kamyar Yazdani
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
| | - Philip J. Homan
- grid.48336.3a0000 0004 1936 8075Center for Cancer Research Collaborative Bioinformatics Resource, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA ,grid.418021.e0000 0004 0535 8394Advanced Biomedical Computational Science, Frederick National Laboratory for Cancer Research, Frederick, MD 21702 USA
| | - Danny Incarnato
- grid.4830.f0000 0004 0407 1981Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | - Tomoyuki Numata
- grid.177174.30000 0001 2242 4849Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-shi Fukuoka, 812-8582 Japan ,grid.208504.b0000 0001 2230 7538Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba-shi, Ibaraki, 305-8566 Japan
| | - John S. Schneekloth Jr
- grid.48336.3a0000 0004 1936 8075Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702 USA
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25
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Alternative Splicing Role in New Therapies of Spinal Muscular Atrophy. Genes (Basel) 2021; 12:genes12091346. [PMID: 34573328 PMCID: PMC8468182 DOI: 10.3390/genes12091346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/17/2022] Open
Abstract
It has been estimated that 80% of the pre-mRNA undergoes alternative splicing, which exponentially increases the flow of biological information in cellular processes and can be an attractive therapeutic target. It is a crucial mechanism to increase genetic diversity. Disturbed alternative splicing is observed in many disorders, including neuromuscular diseases and carcinomas. Spinal Muscular Atrophy (SMA) is an autosomal recessive neurodegenerative disease. Homozygous deletion in 5q13 (the region coding for the motor neuron survival gene (SMN1)) is responsible for 95% of SMA cases. The nearly identical SMN2 gene does not compensate for SMN loss caused by SMN1 gene mutation due to different splicing of exon 7. A pathologically low level of survival motor neuron protein (SMN) causes degeneration of the anterior horn cells in the spinal cord with associated destruction of α-motor cells and manifested by muscle weakness and loss. Understanding the regulation of the SMN2 pre-mRNA splicing process has allowed for innovative treatment and the introduction of new medicines for SMA. After describing the concept of splicing modulation, this review will cover the progress achieved in this field, by highlighting the breakthrough accomplished recently for the treatment of SMA using the mechanism of alternative splicing.
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26
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Tang Z, Akhter S, Ramprasad A, Wang X, Reibarkh M, Wang J, Aryal S, Thota SS, Zhao J, Douglas JT, Gao P, Holmstrom ED, Miao Y, Wang J. Recognition of single-stranded nucleic acids by small-molecule splicing modulators. Nucleic Acids Res 2021; 49:7870-7883. [PMID: 34283224 PMCID: PMC8373063 DOI: 10.1093/nar/gkab602] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 12/16/2022] Open
Abstract
Risdiplam is the first approved small-molecule splicing modulator for the treatment of spinal muscular atrophy (SMA). Previous studies demonstrated that risdiplam analogues have two separate binding sites in exon 7 of the SMN2 pre-mRNA: (i) the 5'-splice site and (ii) an upstream purine (GA)-rich binding site. Importantly, the sequence of this GA-rich binding site significantly enhanced the potency of risdiplam analogues. In this report, we unambiguously determined that a known risdiplam analogue, SMN-C2, binds to single-stranded GA-rich RNA in a sequence-specific manner. The minimum required binding sequence for SMN-C2 was identified as GAAGGAAGG. We performed all-atom simulations using a robust Gaussian accelerated molecular dynamics (GaMD) method, which captured spontaneous binding of a risdiplam analogue to the target nucleic acids. We uncovered, for the first time, a ligand-binding pocket formed by two sequential GAAG loop-like structures. The simulation findings were highly consistent with experimental data obtained from saturation transfer difference (STD) NMR and structure-affinity-relationship studies of the risdiplam analogues. Together, these studies illuminate us to understand the molecular basis of single-stranded purine-rich RNA recognition by small-molecule splicing modulators with an unprecedented binding mode.
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Affiliation(s)
- Zhichao Tang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66047, USA
| | - Sana Akhter
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA
| | - Ankita Ramprasad
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66047, USA
| | - Xiao Wang
- Analytical Research & Development, Merck and Co., Inc., Kenilworth, NJ 07033, USA
| | - Mikhail Reibarkh
- Analytical Research & Development, Merck and Co., Inc., Kenilworth, NJ 07033, USA
| | - Jinan Wang
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA
| | - Sadikshya Aryal
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66047, USA
| | - Srinivas S Thota
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66047, USA
| | - Junxing Zhao
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66047, USA
| | - Justin T Douglas
- Nuclear Magnetic Resonance Lab, University of Kansas, Lawrence, KS 66045, USA
| | - Philip Gao
- Protein Production Group, University of Kansas, Lawrence, KS 66047, USA
| | - Erik D Holmstrom
- Department of Molecular Biosciences and Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA
| | - Yinglong Miao
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA
| | - Jingxin Wang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66047, USA
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27
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A synthetic small molecule stalls pre-mRNA splicing by promoting an early-stage U2AF2-RNA complex. Cell Chem Biol 2021; 28:1145-1157.e6. [PMID: 33689684 PMCID: PMC8380659 DOI: 10.1016/j.chembiol.2021.02.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/25/2021] [Accepted: 02/11/2021] [Indexed: 12/20/2022]
Abstract
Dysregulated pre-mRNA splicing is an emerging Achilles heel of cancers and myelodysplasias. To expand the currently limited portfolio of small-molecule drug leads, we screened for chemical modulators of the U2AF complex, which nucleates spliceosome assembly and is mutated in myelodysplasias. A hit compound specifically enhances RNA binding by a U2AF2 subunit. Remarkably, the compound inhibits splicing of representative substrates and stalls spliceosome assembly at the stage of U2AF function. Computational docking, together with structure-guided mutagenesis, indicates that the compound bridges the tandem U2AF2 RNA recognition motifs via hydrophobic and electrostatic moieties. Cells expressing a cancer-associated U2AF1 mutant are preferentially killed by treatment with the compound. Altogether, our results highlight the potential of trapping early spliceosome assembly as an effective pharmacological means to manipulate pre-mRNA splicing. By extension, we suggest that stabilizing assembly intermediates may offer a useful approach for small-molecule inhibition of macromolecular machines.
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28
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Zhang P, Liu X, Abegg D, Tanaka T, Tong Y, Benhamou RI, Baisden J, Crynen G, Meyer SM, Cameron MD, Chatterjee AK, Adibekian A, Childs-Disney JL, Disney MD. Reprogramming of Protein-Targeted Small-Molecule Medicines to RNA by Ribonuclease Recruitment. J Am Chem Soc 2021; 143:13044-13055. [PMID: 34387474 DOI: 10.1021/jacs.1c02248] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Reprogramming known medicines for a novel target with activity and selectivity over the canonical target is challenging. By studying the binding interactions between RNA folds and known small-molecule medicines and mining the resultant dataset across human RNAs, we identified that Dovitinib, a receptor tyrosine kinase (RTK) inhibitor, binds the precursor to microRNA-21 (pre-miR-21). Dovitinib was rationally reprogrammed for pre-miR-21 by using it as an RNA recognition element in a chimeric compound that also recruits RNase L to induce the RNA's catalytic degradation. By enhancing the inherent RNA-targeting activity and decreasing potency against canonical RTK protein targets in cells, the chimera shifted selectivity for pre-miR-21 by 2500-fold, alleviating disease progression in mouse models of triple-negative breast cancer and Alport Syndrome, both caused by miR-21 overexpression. Thus, targeted degradation can dramatically improve selectivity even across different biomolecules, i.e., protein versus RNA.
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Affiliation(s)
- Peiyuan Zhang
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Xiaohui Liu
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Daniel Abegg
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Toru Tanaka
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Yuquan Tong
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Raphael I Benhamou
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Jared Baisden
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Gogce Crynen
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Samantha M Meyer
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Michael D Cameron
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | - Arnab K Chatterjee
- California Institute for Biomedical Research (CALIBR), Scripps Research, La Jolla, California 92037, United States
| | - Alexander Adibekian
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
| | | | - Matthew D Disney
- Department of Chemistry, Scripps Research, Jupiter, Florida 33458, United States
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29
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Regulated control of gene therapies by drug-induced splicing. Nature 2021; 596:291-295. [PMID: 34321659 PMCID: PMC8966400 DOI: 10.1038/s41586-021-03770-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 06/23/2021] [Indexed: 01/13/2023]
Abstract
So far, gene therapies have relied on complex constructs that cannot be finely controlled1,2. Here we report a universal switch element that enables precise control of gene replacement or gene editing after exposure to a small molecule. The small-molecule inducers are currently in human use, are orally bioavailable when given to animals or humans and can reach both peripheral tissues and the brain. Moreover, the switch system, which we denote Xon, does not require the co-expression of any regulatory proteins. Using Xon, the translation of the desired elements for controlled gene replacement or gene editing machinery occurs after a single oral dose of the inducer, and the robustness of expression can be controlled by the drug dose, protein stability and redosing. The ability of Xon to provide temporal control of protein expression can be adapted for cell-biology applications and animal studies. Additionally, owing to the oral bioavailability and safety of the drugs used, the Xon switch system provides an unprecedented opportunity to refine and tailor the application of gene therapies in humans.
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30
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Abstract
Risdiplam (Evrysdi™) is an orally administered, survival motor neuron 2 (SMN2)-directed RNA splicing modifier being developed by Roche, PTC Therapeutics Inc and the SMA Foundation for the treatment of the spinal muscular atrophy. The small molecule is designed to treat spinal muscular atrophy caused by mutations in chromosome 5q leading to SMN protein deficiency. The drug boosts the ability of an alternative gene SMN2 to produce full-length and functional SMN protein. In August 2020, Evrysdi™ (risdiplam) received its first approval in the USA for the treatment of spinal muscular atrophy in patients 2 months of age and older. Risdiplam is in pre-registration for this indication in numerous countries worldwide, including the European Union, Brazil, Chile, China, Indonesia, Russia, South Korea and Taiwan. This article summarizes the milestones in the development of risdiplam leading to this first approval for spinal muscular atrophy.
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Affiliation(s)
- Sohita Dhillon
- Springer Nature, Mairangi Bay, Private Bag 65901, Auckland, 0754, New Zealand.
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31
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Ajiro M, Awaya T, Kim YJ, Iida K, Denawa M, Tanaka N, Kurosawa R, Matsushima S, Shibata S, Sakamoto T, Studer R, Krainer AR, Hagiwara M. Therapeutic manipulation of IKBKAP mis-splicing with a small molecule to cure familial dysautonomia. Nat Commun 2021; 12:4507. [PMID: 34301951 PMCID: PMC8302731 DOI: 10.1038/s41467-021-24705-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 06/21/2021] [Indexed: 01/10/2023] Open
Abstract
Approximately half of genetic disease-associated mutations cause aberrant splicing. However, a widely applicable therapeutic strategy to splicing diseases is yet to be developed. Here, we analyze the mechanism whereby IKBKAP-familial dysautonomia (FD) exon 20 inclusion is specifically promoted by a small molecule splice modulator, RECTAS, even though IKBKAP-FD exon 20 has a suboptimal 5' splice site due to the IVS20 + 6 T > C mutation. Knockdown experiments reveal that exon 20 inclusion is suppressed in the absence of serine/arginine-rich splicing factor 6 (SRSF6) binding to an intronic splicing enhancer in intron 20. We show that RECTAS directly interacts with CDC-like kinases (CLKs) and enhances SRSF6 phosphorylation. Consistently, exon 20 splicing is bidirectionally manipulated by targeting cellular CLK activity with RECTAS versus CLK inhibitors. The therapeutic potential of RECTAS is validated in multiple FD disease models. Our study indicates that small synthetic molecules affecting phosphorylation state of SRSFs is available as a new therapeutic modality for mechanism-oriented precision medicine of splicing diseases.
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Affiliation(s)
- Masahiko Ajiro
- Department of Drug Discovery Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tomonari Awaya
- Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Young Jin Kim
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Kei Iida
- Medical Research Support Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Masatsugu Denawa
- Medical Research Support Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Nobuo Tanaka
- Medical Research Support Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Ryo Kurosawa
- Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shingo Matsushima
- Department of Drug Discovery Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Saiko Shibata
- Department of Drug Discovery Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tetsunori Sakamoto
- Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Rolenz Studer
- Center for Stem Cell Biology, Sloan Kettering Institute, New York, NY, USA
| | | | - Masatoshi Hagiwara
- Department of Drug Discovery Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan. .,Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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32
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Bush JA, Williams CC, Meyer SM, Tong Y, Haniff HS, Childs-Disney JL, Disney MD. Systematically Studying the Effect of Small Molecules Interacting with RNA in Cellular and Preclinical Models. ACS Chem Biol 2021; 16:1111-1127. [PMID: 34166593 PMCID: PMC8867596 DOI: 10.1021/acschembio.1c00014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The interrogation and manipulation of biological systems by small molecules is a powerful approach in chemical biology. Ideal compounds selectively engage a target and mediate a downstream phenotypic response. Although historically small molecule drug discovery has focused on proteins and enzymes, targeting RNA is an attractive therapeutic alternative, as many disease-causing or -associated RNAs have been identified through genome-wide association studies. As the field of RNA chemical biology emerges, the systematic evaluation of target validation and modulation of target-associated pathways is of paramount importance. In this Review, through an examination of case studies, we outline the experimental characterization, including methods and tools, to evaluate comprehensively the impact of small molecules that target RNA on cellular phenotype.
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Affiliation(s)
- Jessica A Bush
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Christopher C Williams
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Samantha M Meyer
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Yuquan Tong
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Hafeez S Haniff
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jessica L Childs-Disney
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Matthew D Disney
- The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
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33
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An X, Chen C, Wang T, Huang A, Zhang D, Han MJ, Wang J. Genetic Incorporation of Selenotyrosine Significantly Improves Enzymatic Activity of Agrobacterium radiobacter Phosphotriesterase. Chembiochem 2021; 22:2535-2539. [PMID: 32789938 DOI: 10.1002/cbic.202000460] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/11/2020] [Indexed: 12/16/2022]
Abstract
Tyrosine plays important roles in many enzymes. To facilitate enzyme design, mechanistic studies and minimize structural perturbation in the active site, here we report the genetic incorporation of a novel unnatural amino acid selenotyrosine (SeHF), which has single-atom replacement in comparison to tyrosine. The arPTE-(Agrobacterium radiobacter Phosphotriesterase) Tyr309SeHF mutant exhibits a significant 12-fold increase in kcat and 3.2-fold enhancement in kcat /KM at pH 7.0. Molecular dynamics simulations show that the SeHF309 mutation results in a conformational switch which opens up the product release pocket and increases the product release rate, thereby elevating the overall enzyme activity. Significant improvement of the catalytic efficiency at neutral pH by single unnatural amino acid (UAA) mutation broadens the application of this enzyme, and provides valuable insights to the mechanism. Our method represents a new approach for designing enzymes with enhanced activity.
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Affiliation(s)
- Xiaojing An
- Laboratory of Non-coding RNA, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
| | - Chao Chen
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China.,University of the Chinese Academy of Sciences (UCAS), Hefei, China
| | - Tianyuan Wang
- Laboratory of Non-coding RNA, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
| | - Aiping Huang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Ming-Jie Han
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Jiangyun Wang
- Laboratory of Non-coding RNA, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
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34
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Ratni H, Scalco RS, Stephan AH. Risdiplam, the First Approved Small Molecule Splicing Modifier Drug as a Blueprint for Future Transformative Medicines. ACS Med Chem Lett 2021; 12:874-877. [PMID: 34141064 DOI: 10.1021/acsmedchemlett.0c00659] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/19/2021] [Indexed: 12/17/2022] Open
Abstract
Not too long ago, the concept of selectively targeting mRNA with small molecules was perceived as a formidable scientific challenge. The discovery of small molecule splicing modifiers and the development of risdiplam for the treatment of spinal muscular atrophy (SMA) have firmly established proof of concept for this exciting new platform and transformed a scientific curiosity into a viable technology to target disease. Today, several approaches to target mRNA with small molecules, supported by biophysical and screening methods, are in place to deliver new drugs with high therapeutic relevance.
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Affiliation(s)
- Hasane Ratni
- pRED, Pharma Research & Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Renata S. Scalco
- pRED, Pharma Research & Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Alexander H. Stephan
- pRED, Pharma Research & Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, 4070 Basel, Switzerland
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35
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Kelaini S, Chan C, Cornelius VA, Margariti A. RNA-Binding Proteins Hold Key Roles in Function, Dysfunction, and Disease. BIOLOGY 2021; 10:biology10050366. [PMID: 33923168 PMCID: PMC8146904 DOI: 10.3390/biology10050366] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 02/06/2023]
Abstract
RNA-binding proteins (RBPs) are multi-faceted proteins in the regulation of RNA or its RNA splicing, localisation, stability, and translation. Amassing proof from many recent and dedicated studies reinforces the perception of RBPs exerting control through differing expression levels, cellular localization and post-transcriptional alterations. However, since the regulation of RBPs is reliant on the micro-environment and events like stress response and metabolism, their binding affinities and the resulting RNA-RBP networks may be affected. Therefore, any misregulation and disruption in the features of RNA and its related homeostasis can lead to a number of diseases that include diabetes, cardiovascular disease, and other disorders such as cancer and neurodegenerative diseases. As such, correct regulation of RNA and RBPs is crucial to good health as the effect RBPs exert through loss of function can cause pathogenesis. In this review, we will discuss the significance of RBPs and their typical function and how this can be disrupted in disease.
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36
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RNA-Targeting Splicing Modifiers: Drug Development and Screening Assays. Molecules 2021; 26:molecules26082263. [PMID: 33919699 PMCID: PMC8070285 DOI: 10.3390/molecules26082263] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 02/06/2023] Open
Abstract
RNA splicing is an essential step in producing mature messenger RNA (mRNA) and other RNA species. Harnessing RNA splicing modifiers as a new pharmacological modality is promising for the treatment of diseases caused by aberrant splicing. This drug modality can be used for infectious diseases by disrupting the splicing of essential pathogenic genes. Several antisense oligonucleotide splicing modifiers were approved by the U.S. Food and Drug Administration (FDA) for the treatment of spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD). Recently, a small-molecule splicing modifier, risdiplam, was also approved for the treatment of SMA, highlighting small molecules as important warheads in the arsenal for regulating RNA splicing. The cellular targets of these approved drugs are all mRNA precursors (pre-mRNAs) in human cells. The development of novel RNA-targeting splicing modifiers can not only expand the scope of drug targets to include many previously considered “undruggable” genes but also enrich the chemical-genetic toolbox for basic biomedical research. In this review, we summarized known splicing modifiers, screening methods for novel splicing modifiers, and the chemical space occupied by the small-molecule splicing modifiers.
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37
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Natua S, Ashok C, Shukla S. Hypoxia-induced alternative splicing in human diseases: the pledge, the turn, and the prestige. Cell Mol Life Sci 2021; 78:2729-2747. [PMID: 33386889 PMCID: PMC11072330 DOI: 10.1007/s00018-020-03727-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/24/2020] [Accepted: 11/28/2020] [Indexed: 12/30/2022]
Abstract
Maintenance of oxygen homeostasis is an indispensable criterion for the existence of multicellular life-forms. Disruption of this homeostasis due to inadequate oxygenation of the respiring tissues leads to pathological hypoxia, which acts as a significant stressor in several pathophysiological conditions including cancer, cardiovascular defects, bacterial infections, and neurological disorders. Consequently, the hypoxic tissues develop necessary adaptations both at the tissue and cellular level. The cellular adaptations involve a dramatic alteration in gene expression, post-transcriptional and post-translational modification of gene products, bioenergetics, and metabolism. Among the key responses to oxygen-deprivation is the skewing of cellular alternative splicing program. Herein, we discuss the current concepts of oxygen tension-dependent alternative splicing relevant to various pathophysiological conditions. Following a brief description of cellular response to hypoxia and the pre-mRNA splicing mechanism, we outline the impressive number of hypoxia-elicited alternative splicing events associated with maladies like cancer, cardiovascular diseases, and neurological disorders. Furthermore, we discuss how manipulation of hypoxia-induced alternative splicing may pose promising strategies for novel translational diagnosis and therapeutic interventions.
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Affiliation(s)
- Subhashis Natua
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, Madhya Pradesh, India
| | - Cheemala Ashok
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, Madhya Pradesh, India
| | - Sanjeev Shukla
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, Madhya Pradesh, India.
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38
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A general fragment-based approach to identify and optimize bioactive ligands targeting RNA. Proc Natl Acad Sci U S A 2020; 117:33197-33203. [PMID: 33318191 PMCID: PMC7777249 DOI: 10.1073/pnas.2012217117] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
RNAs have important functions that are dictated by their structure. Indeed, small molecules that interact with RNA structures can perturb function, serving as chemical probes and lead medicines. Here we describe the development of a fragment-based approach to discover and optimize bioactive small molecules targeting RNA. We extended the target validation method chemical cross-linking and isolation by pull-down (Chem-CLIP) to identify and map the binding sites of low molecular weight fragments that engage RNA or Chem-CLIP fragment mapping (Chem-CLIP-Frag-Map). Using Chem-CLIP-Frag-Map, we identified several fragments that bind the precursor to oncogenic microRNA-21 (pre-miR-21). Assembly of these fragments provided a specific bioactive compound with improved potency that inhibits pre-miR-21 processing, reducing mature miR-21 levels. The compound exerted selective effects on the transcriptome and selectively mitigated a miR-21-associated invasive phenotype in triple-negative breast cancer cells. The Chem-CLIP-Frag-Map approach should prove general to expedite the identification and optimization of small molecules that bind RNA targets.
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39
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Singh RN, Ottesen EW, Singh NN. The First Orally Deliverable Small Molecule for the Treatment of Spinal Muscular Atrophy. Neurosci Insights 2020; 15:2633105520973985. [PMID: 33283185 PMCID: PMC7691903 DOI: 10.1177/2633105520973985] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 10/27/2020] [Indexed: 12/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is 1 of the leading causes of infant mortality. SMA
is mostly caused by low levels of Survival Motor Neuron (SMN) protein due to
deletion of or mutation in the SMN1 gene. Its nearly identical
copy, SMN2, fails to compensate for the loss of
SMN1 due to predominant skipping of exon 7. Correction of
SMN2 exon 7 splicing by an antisense oligonucleotide (ASO),
nusinersen (Spinraza™), that targets the intronic splicing silencer N1 (ISS-N1)
became the first approved therapy for SMA. Restoration of SMN levels using gene
therapy was the next. Very recently, an orally deliverable small molecule,
risdiplam (Evrysdi™), became the third approved therapy for SMA. Here we discuss
how these therapies are positioned to meet the needs of the broad phenotypic
spectrum of SMA patients.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
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40
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Ando S, Suzuki S, Okubo S, Ohuchi K, Takahashi K, Nakamura S, Shimazawa M, Fuji K, Hara H. Discovery of a CNS penetrant small molecule SMN2 splicing modulator with improved tolerability for spinal muscular atrophy. Sci Rep 2020; 10:17472. [PMID: 33060681 PMCID: PMC7562719 DOI: 10.1038/s41598-020-74346-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 09/28/2020] [Indexed: 01/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease, typically resulting from loss-of-function mutations in the survival motor neuron 1 (SMN1) gene. Nusinersen/SPINRAZA, a splice-switching oligonucleotide that modulates SMN2 (a paralog of SMN1) splicing and consequently increases SMN protein levels, has a therapeutic effect for SMA. Previously reported small-molecule SMN2 splicing modulators such as risdiplam/EVRYSDI and its analog SMN-C3 modulate not only the splicing of SMN2 but also that of secondary splice targets, including forkhead box protein M1 (FOXM1). Through screening SMA patient-derived fibroblasts, a novel small molecule, designated TEC-1, was identified that selectively modulates SMN2 splicing over three secondary splice targets. TEC-1 did not strongly affect the splicing of FOXM1, and unlike risdiplam, did not induce micronucleus formation. In addition, TEC-1 showed higher selectively on galactosylceramidase and huntingtin gene expression compared to previously reported compounds (e.g., SMN-C3) due to off-target effects on cryptic exon inclusion and nonsense-mediated mRNA decay. Moreover, TEC-1 significantly ameliorated the disease phenotype in an SMA murine model in vivo. Thus, TEC-1 may have promising therapeutic potential for SMA, and our study demonstrates the feasibility of RNA-targeting small-molecule drug development with an improved tolerability profile.
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Affiliation(s)
- Shiori Ando
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | | | | | - Kazuki Ohuchi
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Kei Takahashi
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Shinsuke Nakamura
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Koji Fuji
- Reborna Biosciences Inc., Kanagawa, 251-0012, Japan
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan.
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41
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Meyer SM, Williams CC, Akahori Y, Tanaka T, Aikawa H, Tong Y, Childs-Disney JL, Disney MD. Small molecule recognition of disease-relevant RNA structures. Chem Soc Rev 2020; 49:7167-7199. [PMID: 32975549 PMCID: PMC7717589 DOI: 10.1039/d0cs00560f] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Targeting RNAs with small molecules represents a new frontier in drug discovery and development. The rich structural diversity of folded RNAs offers a nearly unlimited reservoir of targets for small molecules to bind, similar to small molecule occupancy of protein binding pockets, thus creating the potential to modulate human biology. Although the bacterial ribosome has historically been the most well exploited RNA target, advances in RNA sequencing technologies and a growing understanding of RNA structure have led to an explosion of interest in the direct targeting of human pathological RNAs. This review highlights recent advances in this area, with a focus on the design of small molecule probes that selectively engage structures within disease-causing RNAs, with micromolar to nanomolar affinity. Additionally, we explore emerging RNA-target strategies, such as bleomycin A5 conjugates and ribonuclease targeting chimeras (RIBOTACs), that allow for the targeted degradation of RNAs with impressive potency and selectivity. The compounds discussed in this review have proven efficacious in human cell lines, patient-derived cells, and pre-clinical animal models, with one compound currently undergoing a Phase II clinical trial and another that recently garnerd FDA-approval, indicating a bright future for targeted small molecule therapeutics that affect RNA function.
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Affiliation(s)
- Samantha M Meyer
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Christopher C Williams
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Yoshihiro Akahori
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Toru Tanaka
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Haruo Aikawa
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Yuquan Tong
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Jessica L Childs-Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Matthew D Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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42
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Wilkinson IVL, Terstappen GC, Russell AJ. Combining experimental strategies for successful target deconvolution. Drug Discov Today 2020; 25:S1359-6446(20)30373-1. [PMID: 32971235 DOI: 10.1016/j.drudis.2020.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/10/2020] [Accepted: 09/14/2020] [Indexed: 02/06/2023]
Abstract
Investment in phenotypic drug discovery has led to increased demand for rapid and robust target deconvolution to aid successful drug development. Although methods for target identification and mechanism of action (MoA) discovery are flourishing, they typically lead to lists of putative targets. Validating which target(s) are involved in the therapeutic mechanism of a compound poses a significant challenge, requiring direct binding, target engagement, and functional studies in relevant physiological contexts. A combination of orthogonal approaches can allow target identification beyond the proteome as well as aid prioritisation for resource-intensive target validation studies.
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Affiliation(s)
- Isabel V L Wilkinson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, UK
| | - Georg C Terstappen
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3PQ, UK
| | - Angela J Russell
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, UK; Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3PQ, UK.
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43
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Mukherjee H, Blain JC, Vandivier LE, Chin DN, Friedman JE, Liu F, Maillet A, Fang C, Kaplan JB, Li J, Chenoweth DM, Christensen AB, Petersen LK, Hansen NJV, Barrera L, Kubica N, Kumaravel G, Petter JC. PEARL-seq: A Photoaffinity Platform for the Analysis of Small Molecule-RNA Interactions. ACS Chem Biol 2020; 15:2374-2381. [PMID: 32804474 DOI: 10.1021/acschembio.0c00357] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
RNA is emerging as a valuable target for the development of novel therapeutic agents. The rational design of RNA-targeting small molecules, however, has been hampered by the relative lack of methods for the analysis of small molecule-RNA interactions. Here, we present our efforts to develop such a platform using photoaffinity labeling. This technique, termed Photoaffinity Evaluation of RNA Ligation-Sequencing (PEARL-seq), enables the rapid identification of small molecule binding locations within their RNA targets and can provide information on ligand selectivity across multiple different RNAs. These data, when supplemented with small molecule SAR data and RNA probing data enable the construction of a computational model of the RNA-ligand structure, thereby enabling the rational design of novel RNA-targeted ligands.
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Affiliation(s)
- Herschel Mukherjee
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - J. Craig Blain
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Lee E. Vandivier
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Donovan N. Chin
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Jessica E. Friedman
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Fei Liu
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Ashley Maillet
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Chao Fang
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Jenifer B. Kaplan
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Jinxing Li
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, United States
| | - David M. Chenoweth
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, United States
| | | | | | | | - Luis Barrera
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | - Neil Kubica
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
| | | | - Jennifer C. Petter
- Arrakis Therapeutics, 830 Winter Street, Waltham, Massachusetts, United States
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44
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Costales MG, Childs-Disney JL, Haniff HS, Disney MD. How We Think about Targeting RNA with Small Molecules. J Med Chem 2020; 63:8880-8900. [PMID: 32212706 PMCID: PMC7486258 DOI: 10.1021/acs.jmedchem.9b01927] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RNA offers nearly unlimited potential as a target for small molecule chemical probes and lead medicines. Many RNAs fold into structures that can be selectively targeted with small molecules. This Perspective discusses molecular recognition of RNA by small molecules and highlights key enabling technologies and properties of bioactive interactions. Sequence-based design of ligands targeting RNA has established rules for affecting RNA targets and provided a potentially general platform for the discovery of bioactive small molecules. The RNA targets that contain preferred small molecule binding sites can be identified from sequence, allowing identification of off-targets and prediction of bioactive interactions by nature of ligand recognition of functional sites. Small molecule targeted degradation of RNA targets (ribonuclease-targeted chimeras, RIBOTACs) and direct cleavage by small molecules have also been developed. These growing technologies suggest that the time is right to provide small molecule chemical probes to target functionally relevant RNAs throughout the human transcriptome.
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Affiliation(s)
- Matthew G Costales
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jessica L Childs-Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Hafeez S Haniff
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Matthew D Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
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45
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Ottesen EW, Singh RN. Characteristics of circular RNAs generated by human Survival Motor Neuron genes. Cell Signal 2020; 73:109696. [PMID: 32553550 PMCID: PMC7387165 DOI: 10.1016/j.cellsig.2020.109696] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023]
Abstract
Circular RNAs (circRNAs) belong to a diverse class of stable RNAs expressed in all cell types. Their proposed functions include sponging of microRNAs (miRNAs), sequestration and trafficking of proteins, assembly of multimeric complexes, production of peptides, and regulation of transcription. Backsplicing due to RNA structures formed by an exceptionally high number of Alu repeats lead to the production of a vast repertoire of circRNAs by human Survival Motor Neuron genes, SMN1 and SMN2, that code for SMN, an essential multifunctional protein. Low levels of SMN due to deletion or mutation of SMN1 result in spinal muscular atrophy (SMA), a major genetic disease of infants and children. Mild SMA is also recorded in adult population, expanding the spectrum of the disease. Here we review SMN circRNAs with respect to their biogenesis, sequence features, and potential functions. We also discuss how SMN circRNAs could be exploited for diagnostic and therapeutic purposes.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America.
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46
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Haniff HS, Knerr L, Chen JL, Disney MD, Lightfoot HL. Target-Directed Approaches for Screening Small Molecules against RNA Targets. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2020; 25:869-894. [PMID: 32419578 PMCID: PMC7442623 DOI: 10.1177/2472555220922802] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
RNA molecules have a variety of cellular functions that can drive disease pathologies. They are without a doubt one of the most intriguing yet controversial small-molecule drug targets. The ability to widely target RNA with small molecules could be revolutionary, once the right tools, assays, and targets are selected, thereby defining which biomolecules are targetable and what constitutes drug-like small molecules. Indeed, approaches developed over the past 5-10 years have changed the face of small molecule-RNA targeting by addressing historic concerns regarding affinity, selectivity, and structural dynamics. Presently, selective RNA-protein complex stabilizing drugs such as branaplam and risdiplam are in clinical trials for the modulation of SMN2 splicing, compounds identified from phenotypic screens with serendipitous outcomes. Fully developing RNA as a druggable target will require a target engagement-driven approach, and evolving chemical collections will be important for the industrial development of this class of target. In this review we discuss target-directed approaches that can be used to identify RNA-binding compounds and the chemical knowledge we have today of small-molecule RNA binders.
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Affiliation(s)
- Hafeez S. Haniff
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL, USA
| | - Laurent Knerr
- Medicinal Chemistry, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Jonathan L. Chen
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL, USA
| | - Matthew D. Disney
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL, USA
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47
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Jackson TC, Kochanek PM. RNA Binding Motif 5 (RBM5) in the CNS-Moving Beyond Cancer to Harness RNA Splicing to Mitigate the Consequences of Brain Injury. Front Mol Neurosci 2020; 13:126. [PMID: 32765218 PMCID: PMC7381114 DOI: 10.3389/fnmol.2020.00126] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/22/2020] [Indexed: 12/14/2022] Open
Abstract
Gene splicing modulates the potency of cell death effectors, alters neuropathological disease processes, influences neuronal recovery, but may also direct distinct mechanisms of secondary brain injury. Therapeutic targeting of RNA splicing is a promising avenue for next-generation CNS treatments. RNA-binding proteins (RBPs) regulate a variety of RNA species and are prime candidates in the hunt for druggable targets to manipulate and tailor gene-splicing responses in the brain. RBPs preferentially recognize unique consensus sequences in targeted mRNAs. Also, RBPs often contain multiple RNA-binding domains (RBDs)—each having a unique consensus sequence—suggesting the possibility that drugs could be developed to block individual functional domains, increasing the precision of RBP-targeting therapies. Empirical characterization of most RBPs is lacking and represents a major barrier to advance this emerging therapeutic area. There is a paucity of data on the role of RBPs in the brain including, identification of their unique mRNA targets, defining how CNS insults affect their levels and elucidating which RBPs (and individual domains within) to target to improve neurological outcomes. This review focuses on the state-of-the-art of the RBP tumor suppressor RNA binding motif 5 (RBM5) in the CNS. We discuss its potent pro-death roles in cancer, which motivated our interest to study it in the brain. We review recent studies showing that RBM5 levels are increased after CNS trauma and that it promotes neuronal death in vitro. Finally, we conclude with recent reports on the first set of RBM5 regulated genes identified in the intact brain, and discuss how those findings provide new clues germane to its potential function(s) in the CNS, and pose new questions on its therapeutic utility to mitigate CNS injury.
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Affiliation(s)
- Travis C Jackson
- Morsani College of Medicine, USF Health Heart Institute, University of South Florida, Tampa, FL, United States.,Morsani College of Medicine, Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, United States
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, Department of Critical Care Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
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48
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Angelbello AJ, Chen JL, Disney MD. Small molecule targeting of RNA structures in neurological disorders. Ann N Y Acad Sci 2020; 1471:57-71. [PMID: 30964958 PMCID: PMC6785366 DOI: 10.1111/nyas.14051] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 02/15/2019] [Accepted: 02/19/2019] [Indexed: 12/11/2022]
Abstract
Aberrant RNA structure and function operate in neurological disease progression and severity. As RNA contributes to disease pathology in a complex fashion, that is, via various mechanisms, it has become an attractive therapeutic target for small molecules and oligonucleotides. In this review, we discuss the identification of RNA structures that cause or contribute to neurological diseases as well as recent progress toward the development of small molecules that target them, including small molecule modulators of pre-mRNA splicing and RNA repeat expansions that cause microsatellite disorders such as Huntington's disease and amyotrophic lateral sclerosis. The use of oligonucleotide-based modalities is also discussed. There are key differences between small molecule and oligonucleotide targeting of RNA. The former targets RNA structure, while the latter prefers unstructured regions. Thus, some targets will be preferentially targeted by oligonucleotides and others by small molecules.
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Affiliation(s)
| | - Jonathan L Chen
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida
| | - Matthew D Disney
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida
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49
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Singh RN, Seo J, Singh NN. RNA in spinal muscular atrophy: therapeutic implications of targeting. Expert Opin Ther Targets 2020; 24:731-743. [PMID: 32538213 DOI: 10.1080/14728222.2020.1783241] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Spinal muscular atrophy (SMA) is caused by low levels of the Survival Motor Neuron (SMN) protein due to deletions of or mutations in the SMN1 gene. Humans carry another nearly identical gene, SMN2, which mostly produces a truncated and less stable protein SMNΔ7 due to predominant skipping of exon 7. Elevation of SMN upon correction of SMN2 exon 7 splicing and gene therapy have been proven to be the effective treatment strategies for SMA. AREAS COVERED This review summarizes existing and potential SMA therapies that are based on RNA targeting.We also discuss the mechanistic basis of RNA-targeting molecules. EXPERT OPINION The discovery of intronic splicing silencer N1 (ISS-N1) was the first major step towards developing the currently approved antisense-oligonucleotide (ASO)-directed therapy (SpinrazaTM) based on the correction of exon 7 splicing of the endogenous SMN2pre-mRNA. Recently, gene therapy (Zolgensma) has become the second approved treatment for SMA. Small compounds (currently in clinical trials) capable of restoring SMN2 exon 7 inclusion further expand the class of the RNA targeting molecules for SMA therapy. Endogenous RNA targets, such as long non-coding RNAs, circular RNAs, microRNAs and ribonucleoproteins, could be potentially exploited for developing additional SMA therapies.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University , Ames, IA, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University , Ames, IA, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University , Ames, IA, USA
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50
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Chen JL, Zhang P, Abe M, Aikawa H, Zhang L, Frank AJ, Zembryski T, Hubbs C, Park H, Withka J, Steppan C, Rogers L, Cabral S, Pettersson M, Wager TT, Fountain MA, Rumbaugh G, Childs-Disney JL, Disney MD. Design, Optimization, and Study of Small Molecules That Target Tau Pre-mRNA and Affect Splicing. J Am Chem Soc 2020; 142:8706-8727. [PMID: 32364710 PMCID: PMC7357857 DOI: 10.1021/jacs.0c00768] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Approximately 95% of human genes are alternatively spliced, and aberrant splicing events can cause disease. One pre-mRNA that is alternatively spliced and linked to neurodegenerative diseases is tau (microtubule-associated protein tau), which can cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) and can contribute to Alzheimer's disease. Here, we describe the design of structure-specific lead small molecules that directly target tau pre-mRNA from sequence. This was followed by hit expansion and analogue synthesis to further improve upon these initial lead molecules. The emergent compounds were assessed for functional activity in a battery of assays, including binding assays and an assay that mimics molecular recognition of tau pre-mRNA by a U1 small nuclear ribonucleoprotein (snRNP) splicing factor. Compounds that emerged from these studies had enhanced potency and selectivity for the target RNA relative to the initial hits, while also having significantly improved drug-like properties. The compounds are shown to directly target tau pre-mRNA in cells, via chemical cross-linking and isolation by pull-down target profiling, and to rescue disease-relevant splicing of tau pre-mRNA in a variety of cellular systems, including primary neurons. More broadly, this study shows that lead, structure-specific compounds can be designed from sequence and then further optimized for their physicochemical properties while at the same time enhancing their activity.
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Affiliation(s)
- Jonathan L. Chen
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Peiyuan Zhang
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Masahito Abe
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Haruo Aikawa
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Liying Zhang
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Alexander J. Frank
- Department of Chemistry & Biochemistry, State University of New York at Fredonia, Fredonia, New York 14063, United States
| | - Timothy Zembryski
- Department of Chemistry & Biochemistry, State University of New York at Fredonia, Fredonia, New York 14063, United States
| | - Christopher Hubbs
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - HaJeung Park
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jane Withka
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Claire Steppan
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Lucy Rogers
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Shawn Cabral
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Martin Pettersson
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Travis T. Wager
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Matthew A. Fountain
- Department of Chemistry & Biochemistry, State University of New York at Fredonia, Fredonia, New York 14063, United States
| | - Gavin Rumbaugh
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica L. Childs-Disney
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Matthew D. Disney
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter
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