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Song Y, Cui J, Zhu J, Kim B, Kuo ML, Potts PR. RNATACs: Multispecific small molecules targeting RNA by induced proximity. Cell Chem Biol 2024; 31:1101-1117. [PMID: 38876100 DOI: 10.1016/j.chembiol.2024.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 05/09/2024] [Accepted: 05/22/2024] [Indexed: 06/16/2024]
Abstract
RNA-targeting small molecules (rSMs) have become an attractive modality to tackle traditionally undruggable proteins and expand the druggable space. Among many innovative concepts, RNA-targeting chimeras (RNATACs) represent a new class of multispecific, induced proximity small molecules that act by chemically bringing RNA targets into proximity with an endogenous RNA effector, such as a ribonuclease (RNase). Depending on the RNA effector, RNATACs can alter the stability, localization, translation, or splicing of the target RNA. Although still in its infancy, this new modality has the potential for broad applications in the future to treat diseases with high unmet need. In this review, we discuss potential advantages of RNATACs, recent progress in the field, and challenges to this cutting-edge technology.
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Affiliation(s)
- Yan Song
- Induced Proximity Platform, Amgen Research, Thousand Oaks, CA 91320, USA.
| | - Jia Cui
- Induced Proximity Platform, Amgen Research, Thousand Oaks, CA 91320, USA
| | - Jiaqiang Zhu
- Induced Proximity Platform, Amgen Research, Thousand Oaks, CA 91320, USA
| | - Boseon Kim
- Induced Proximity Platform, Amgen Research, Thousand Oaks, CA 91320, USA
| | - Mei-Ling Kuo
- Induced Proximity Platform, Amgen Research, Thousand Oaks, CA 91320, USA
| | - Patrick Ryan Potts
- Induced Proximity Platform, Amgen Research, Thousand Oaks, CA 91320, USA.
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2
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Maniam S, Maniam S. Screening Techniques for Drug Discovery in Alzheimer's Disease. ACS OMEGA 2024; 9:6059-6073. [PMID: 38371787 PMCID: PMC10870277 DOI: 10.1021/acsomega.3c07046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/22/2023] [Accepted: 12/25/2023] [Indexed: 02/20/2024]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive and irreversible impairment of memory and other cognitive functions of the aging brain. Pathways such as amyloid beta neurotoxicity, tau pathogenesis and neuroinflammatory have been used to understand AD, despite not knowing the definite molecular mechanism which causes this progressive disease. This review attempts to summarize the small molecules that target these pathways using various techniques involving high-throughput screening, molecular modeling, custom bioassays, and spectroscopic detection tools. Novel and evolving screening methods developed to advance drug discovery initiatives in AD research are also highlighted.
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Affiliation(s)
- Sandra Maniam
- Department
of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
| | - Subashani Maniam
- School
of Science, STEM College, RMIT University, Melbourne, Victoria 3001, Australia
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3
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Weaver DF. Druggable targets for the immunopathy of Alzheimer's disease. RSC Med Chem 2023; 14:1645-1661. [PMID: 37731705 PMCID: PMC10507808 DOI: 10.1039/d3md00096f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 06/21/2023] [Indexed: 09/22/2023] Open
Abstract
Alzheimer's disease (AD) is one of the leading threats to the health and socioeconomic well-being of humankind. Though research to develop disease modifying therapies for AD has traditionally focussed on the misfolding and aggregation of proteins, this approach has failed to yield a definitively curative agent. Accordingly, the search for additional or alternative approaches is a medicinal chemistry priority. Dysfunction of the brain's neuroimmune-neuroinflammation axis has emerged as a leading contender. Neuroimmunity however is mechanistically complex, rendering the recognition of candidate receptors a challenging task. Herein, a review of the role of neuroimmunity in the biomolecular pathogenesis of AD is presented with the identification of a 'druggable dozen' targets; in turn, each identified target represents one or more discrete receptors centred on a common biochemical mechanism. The druggable dozen is composed of both cellular and molecular messenger targets, with a 'targetable ten' microglial targets as well as two cytokine-based targets. For each target, the underlying molecular basis, with a consideration of strengths and weaknesses, is considered.
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Affiliation(s)
- Donald F Weaver
- Krembil Research Institute, University Health Network, Department of Chemistry, University of Toronto 60 Leonard Avenue Toronto ON M5T 0S8 Canada
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4
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Aspnes GE, Coffey SB, Darout E, Dechert-Schmitt AM, Dullea RG, Kamlet AS, Limberakis C, Londregan AT, McClure KF, Menhaji-Klotz E, Piotrowski DW, Polivkova J, Raymer B, Ruggeri RB, Salatto CT, Tu M, Wei L, Xiao J. Small molecule inhibitors of PCSK9. SAR investigations of head and amine groups. Bioorg Med Chem Lett 2023:129394. [PMID: 37379958 DOI: 10.1016/j.bmcl.2023.129394] [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: 03/16/2023] [Revised: 06/02/2023] [Accepted: 06/24/2023] [Indexed: 06/30/2023]
Abstract
Our previous work on the optimization of a new class of small molecule PCSK9 mRNA translation inhibitors focused on empirical optimization of the amide tail region of the lead PF-06446846 (1). This work resulted in compound 3 that showed an improved safety profile. We hypothesized that this improvement was related to diminished binding of 3 to non-translating ribosomes and an apparent improvement in transcript selectivity. Herein, we describe our efforts to further optimize this series of inhibitors through modulation of the heterocyclic head group and the amine fragment. Some of the effort was guided by an emerging cryo electron microscopy structure of the binding mode of 1 in the ribosome. These efforts led to the identification of 15 that was deemed suitable for evaluation in a humanized PCSK9 mouse model and a rat toxicology study. Compound 15 demonstrated a dose dependent reduction of plasma PCSK9 levels. The rat toxicological profile was not improved over that of 1, which precluded 15 from further consideration as a clinical candidate.
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Affiliation(s)
- Gary E Aspnes
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Steven B Coffey
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Etzer Darout
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | | | - Robert G Dullea
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Adam S Kamlet
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Chris Limberakis
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Allyn T Londregan
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Kim F McClure
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Elnaz Menhaji-Klotz
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - David W Piotrowski
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA.
| | - Jana Polivkova
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Brian Raymer
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Roger B Ruggeri
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | | | - Meihua Tu
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Liuqing Wei
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - Jun Xiao
- Pfizer Medicine Design, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
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CD33 isoforms in microglia and Alzheimer's disease: Friend and foe. Mol Aspects Med 2023; 90:101111. [PMID: 35940942 DOI: 10.1016/j.mam.2022.101111] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/18/2022] [Accepted: 07/27/2022] [Indexed: 02/08/2023]
Abstract
Alzheimer's disease (AD) is the most common form of neurodegenerative disease and is considered the main cause of dementia worldwide. Genome-wide association studies combined with integrated analysis of functional datasets support a critical role for microglia in AD pathogenesis, identifying them as important potential therapeutic targets. The ability of immunomodulatory receptors on microglia to control the response to pathogenic amyloid-β aggregates has gained significant interest. Siglec-3, also known as CD33, is one of these immunomodulatory receptors expressed on microglia that has been identified as an AD susceptibility factor. Here, we review recent advances made in understanding the multifaceted roles that CD33 plays in microglia with emphasis on two human-specific CD33 isoforms that differentially correlate with AD susceptibility. We also describe several different therapeutic approaches for targeting CD33 that have been advanced for the purpose of skewing microglial cell responses.
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Alzheimer's Disease-Associated Alternative Splicing of CD33 Is Regulated by the HNRNPA Family Proteins. Cells 2023; 12:cells12040602. [PMID: 36831269 PMCID: PMC9954446 DOI: 10.3390/cells12040602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Genetic variations of CD33 have been implicated as a susceptibility factor of Alzheimer's disease (AD). A polymorphism on exon 2 of CD33, rs12459419, affects the alternative splicing of this exon. The minor allele is associated with a reduced risk of AD and promotes the skipping of exon 2 to produce a shorter CD33 isoform lacking the extracellular ligand-binding domain, leading to decreased suppressive signaling on microglial activity. Therefore, factors that regulate the splicing of exon 2 may alter the disease-associated properties of CD33. Herein, we sought to identify the regulatory proteins of CD33 splicing. Using a panel of RNA-binding proteins and a human CD33 minigene, we found that exon 2 skipping of CD33 was promoted by HNRNPA1. Although the knockdown of HNRNPA1 alone did not reduce exon 2 skipping, simultaneous knockdown of HNRNPA1 together with that of HNRNPA2B1 and HNRNPA3 promoted exon 2 inclusion, suggesting functional redundancy among HNRNPA proteins. Similar redundant regulation by HNRNPA proteins was observed in endogenous CD33 of THP-1 and human microglia-like cells. Although mouse Cd33 showed a unique splicing pattern of exon 2, we confirmed that HNRNPA1 promoted the skipping of this exon. Collectively, our results revealed novel regulatory relationships between CD33 and HNRNPA proteins.
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Dimitrova YN, Gutierrez JA, Huard K. It's ok to be outnumbered - sub-stoichiometric modulation of homomeric protein complexes. RSC Med Chem 2023; 14:22-46. [PMID: 36760737 PMCID: PMC9890894 DOI: 10.1039/d2md00212d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022] Open
Abstract
An arsenal of molecular tools with increasingly diversified mechanisms of action is being developed by the scientific community to enable biological interrogation and pharmaceutical modulation of targets and pathways of ever increasing complexity. While most small molecules interact with the target of interest in a 1 : 1 relationship, a noteworthy number of recent examples were reported to bind in a sub-stoichiometric manner to a homomeric protein complex. This approach requires molecular understanding of the physiologically relevant protein assemblies and in-depth characterization of the compound's mechanism of action. The recent literature examples summarized here were selected to illustrate methods used to identify and characterize molecules with such mechanisms. The concept of one small molecule targeting a homomeric protein assembly is not new but the subject deserves renewed inspection in light of emerging technologies and increasingly diverse target biology, to ensure relevant in vitro systems are used and valuable compounds with potentially novel sub-stoichiometric mechanisms of action aren't overlooked.
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Affiliation(s)
| | | | - Kim Huard
- Genentech 1 DNA Way South San Francisco CA 94080 USA
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8
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Barraza SJ, Bhattacharyya A, Trotta CR, Woll MG. Targeting strategies for modulating pre-mRNA splicing with small molecules: Recent advances. Drug Discov Today 2023; 28:103431. [PMID: 36356786 DOI: 10.1016/j.drudis.2022.103431] [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: 08/03/2022] [Revised: 10/27/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022]
Abstract
The concept of using small molecules to therapeutically modulate pre-mRNA splicing was validated with the US Food and Drug Administration (FDA) approval of Evrysdi® (risdiplam) in 2020. Since then, efforts have continued unabated toward the discovery of new splicing-modulating drugs. However, the drug development world has evolved in the 10 years since risdiplam precursors were first identified in high-throughput screening (HTS). Now, new mechanistic insights into RNA-processing pathways and regulatory networks afford increasingly feasible targeted approaches. In this review, organized into classes of biological target, we compile and summarize small molecules discovered, devised, and developed since 2020 to alter pre-mRNA splicing.
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Affiliation(s)
- Scott J Barraza
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ, USA.
| | | | | | - Matthew G Woll
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ, USA
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Palacios DS. Drug Hunting at the Nexus of Medicinal Chemistry and Chemical Biology and the Discovery of Novel Therapeutic Modalities. J Med Chem 2022; 65:13594-13613. [PMID: 36206538 DOI: 10.1021/acs.jmedchem.2c01491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Small molecules designed to modulate protein function have been remarkably successful in advancing human health. As the frontiers of medicine and understanding of disease pathogenesis continue to expand, small molecule scientists must also pursue the development of novel therapeutic modalities beyond functional protein modulation to address diseases of unmet medical need. In this vein, this Perspective will highlight two emerging modalities, selective mRNA splice modulation and targeted protein degradation, as mechanisms that affect protein abundance, rather than protein function, to broaden the scope of low-molecular-weight treatable diseases. Key to the elucidation and development of these mechanisms was the interplay and contemporaneous efforts in medicinal chemistry and chemical biology. Continued research at the intersection of these two fields will be critical for the identification of novel targets and mechanisms toward the development of the next generation of small molecule therapeutics.
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Affiliation(s)
- Daniel S Palacios
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 10675 John Jay Hopkins Drive, San Diego, California 92121, United States
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