1
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Dayan Elshan NGR, Wolff KC, Riva L, Woods AK, Grabovyi G, Wilson K, Pedroarena J, Ghorai S, Nazarian A, Weiss F, Liu Y, Mazumdar W, Song L, Okwor N, Malvin J, Bakowski MA, Beutler N, Kirkpatrick MG, Gebara-Lamb A, Huang E, Nguyen-Tran VTB, Chi V, Li S, Rogers TF, McNamara CW, Gupta AK, Rahimi A, Chen JJ, Joseph SB, Schultz PG, Chatterjee AK. Discovery of CMX990: A Potent SARS-CoV-2 3CL Protease Inhibitor Bearing a Novel Warhead. J Med Chem 2024; 67:2369-2378. [PMID: 38335279 PMCID: PMC10895651 DOI: 10.1021/acs.jmedchem.3c01938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
There remains a need to develop novel SARS-CoV-2 therapeutic options that improve upon existing therapies by an increased robustness of response, fewer safety liabilities, and global-ready accessibility. Functionally critical viral main protease (Mpro, 3CLpro) of SARS-CoV-2 is an attractive target due to its homology within the coronaviral family, and lack thereof toward human proteases. In this disclosure, we outline the advent of a novel SARS-CoV-2 3CLpro inhibitor, CMX990, bearing an unprecedented trifluoromethoxymethyl ketone warhead. Compared with the marketed drug nirmatrelvir (combination with ritonavir = Paxlovid), CMX990 has distinctly differentiated potency (∼5× more potent in primary cells) and human in vitro clearance (>4× better microsomal clearance and >10× better hepatocyte clearance), with good in vitro-to-in vivo correlation. Based on its compelling preclinical profile and projected once or twice a day dosing supporting unboosted oral therapy in humans, CMX990 advanced to a Phase 1 clinical trial as an oral drug candidate for SARS-CoV-2.
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Affiliation(s)
- N G R Dayan Elshan
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Karen C Wolff
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Laura Riva
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ashley K Woods
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Gennadii Grabovyi
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Katy Wilson
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - James Pedroarena
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Sourav Ghorai
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Armen Nazarian
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Frank Weiss
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yuyin Liu
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Wrickban Mazumdar
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lirui Song
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Neechi Okwor
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Jacqueline Malvin
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Malina A Bakowski
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Nathan Beutler
- Department of Immunology and Microbiology, The Scripps Research Institute, 10466 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Melanie G Kirkpatrick
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Amal Gebara-Lamb
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Edward Huang
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Vân T B Nguyen-Tran
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Victor Chi
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Shuangwei Li
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Thomas F Rogers
- Department of Immunology and Microbiology, The Scripps Research Institute, 10466 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Case W McNamara
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Anil Kumar Gupta
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Alireza Rahimi
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Jian Jeffrey Chen
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Sean B Joseph
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Peter G Schultz
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Arnab K Chatterjee
- Calibr at Scripps Research Institute, 11119 North Torrey Pines Road, La Jolla, California 92037, United States
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2
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Oh CK, Nakamura T, Beutler N, Zhang X, Piña-Crespo J, Talantova M, Ghatak S, Trudler D, Carnevale LN, McKercher SR, Bakowski MA, Diedrich JK, Roberts AJ, Woods AK, Chi V, Gupta AK, Rosenfeld MA, Kearns FL, Casalino L, Shaabani N, Liu H, Wilson IA, Amaro RE, Burton DR, Yates JR, Becker C, Rogers TF, Chatterjee AK, Lipton SA. Targeted protein S-nitrosylation of ACE2 inhibits SARS-CoV-2 infection. Nat Chem Biol 2023; 19:275-283. [PMID: 36175661 PMCID: PMC10127945 DOI: 10.1038/s41589-022-01149-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 08/24/2022] [Indexed: 12/12/2022]
Abstract
Prevention of infection and propagation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a high priority in the Coronavirus Disease 2019 (COVID-19) pandemic. Here we describe S-nitrosylation of multiple proteins involved in SARS-CoV-2 infection, including angiotensin-converting enzyme 2 (ACE2), the receptor for viral entry. This reaction prevents binding of ACE2 to the SARS-CoV-2 spike protein, thereby inhibiting viral entry, infectivity and cytotoxicity. Aminoadamantane compounds also inhibit coronavirus ion channels formed by envelope (E) protein. Accordingly, we developed dual-mechanism aminoadamantane nitrate compounds that inhibit viral entry and, thus, the spread of infection by S-nitrosylating ACE2 via targeted delivery of the drug after E protein channel blockade. These non-toxic compounds are active in vitro and in vivo in the Syrian hamster COVID-19 model and, thus, provide a novel avenue to pursue therapy.
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Affiliation(s)
- Chang-Ki Oh
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Tomohiro Nakamura
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Nathan Beutler
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA, USA
| | - Xu Zhang
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Juan Piña-Crespo
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Maria Talantova
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Swagata Ghatak
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Dorit Trudler
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Lauren N Carnevale
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Scott R McKercher
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Malina A Bakowski
- Calibr, a division of the Scripps Research Institute, La Jolla, CA, USA
| | - Jolene K Diedrich
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | - Amanda J Roberts
- Animal Models Core, Scripps Research Institute, La Jolla, CA, USA
| | - Ashley K Woods
- Calibr, a division of the Scripps Research Institute, La Jolla, CA, USA
| | - Victor Chi
- Calibr, a division of the Scripps Research Institute, La Jolla, CA, USA
| | - Anil K Gupta
- Calibr, a division of the Scripps Research Institute, La Jolla, CA, USA
| | - Mia A Rosenfeld
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Fiona L Kearns
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Lorenzo Casalino
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Namir Shaabani
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA, USA
| | - Hejun Liu
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA, USA
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA, USA
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Dennis R Burton
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA, USA
| | - John R Yates
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA
| | | | - Thomas F Rogers
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA, USA
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | | | - Stuart A Lipton
- Departments of Molecular Medicine and Neuroscience, Neurodegeneration New Medicines Center, La Jolla, CA, USA.
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA, USA.
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3
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Zhang CX, Love MS, McNamara CW, Chi V, Woods AK, Joseph S, Arnold SL. Determining the Relationship Between Clofazimine Gastrointestinal Levels and anti‐
Cryptosporidium
Efficacy in Mice. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r4981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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4
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Oh CK, Nakamura T, Beutler N, Zhang X, Piña-Crespo J, Talantova M, Ghatak S, Trudler D, Carnevale LN, McKercher SR, Bakowski MA, Diedrich JK, Roberts AJ, Woods AK, Chi V, Gupta AK, Rosenfeld MA, Kearns FL, Casalino L, Shaabani N, Liu H, Wilson IA, Amaro RE, Burton DR, Yates JR, Becker C, Rogers TF, Chatterjee AK, Lipton SA. Targeted protein S-nitrosylation of ACE2 as potential treatment to prevent spread of SARS-CoV-2 infection. bioRxiv 2022:2022.04.05.487060. [PMID: 35411336 PMCID: PMC8996617 DOI: 10.1101/2022.04.05.487060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Prevention of infection and propagation of SARS-CoV-2 is of high priority in the COVID-19 pandemic. Here, we describe S-nitrosylation of multiple proteins involved in SARS-CoV-2 infection, including angiotensin converting enzyme 2 (ACE2), the receptor for viral entry. This reaction prevents binding of ACE2 to the SARS-CoV-2 Spike protein, thereby inhibiting viral entry, infectivity, and cytotoxicity. Aminoadamantane compounds also inhibit coronavirus ion channels formed by envelope (E) protein. Accordingly, we developed dual-mechanism aminoadamantane nitrate compounds that inhibit viral entry and thus spread of infection by S-nitrosylating ACE2 via targeted delivery of the drug after E-protein channel blockade. These non-toxic compounds are active in vitro and in vivo in the Syrian hamster COVID-19 model, and thus provide a novel avenue for therapy.
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5
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Bakowski MA, Beutler N, Wolff KC, Kirkpatrick MG, Chen E, Nguyen TTH, Riva L, Shaabani N, Parren M, Ricketts J, Gupta AK, Pan K, Kuo P, Fuller M, Garcia E, Teijaro JR, Yang L, Sahoo D, Chi V, Huang E, Vargas N, Roberts AJ, Das S, Ghosh P, Woods AK, Joseph SB, Hull MV, Schultz PG, Burton DR, Chatterjee AK, McNamara CW, Rogers TF. Drug repurposing screens identify chemical entities for the development of COVID-19 interventions. Nat Commun 2021; 12:3309. [PMID: 34083527 PMCID: PMC8175350 DOI: 10.1038/s41467-021-23328-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 04/19/2021] [Indexed: 12/15/2022] Open
Abstract
The ongoing pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), necessitates strategies to identify prophylactic and therapeutic drug candidates for rapid clinical deployment. Here, we describe a screening pipeline for the discovery of efficacious SARS-CoV-2 inhibitors. We screen a best-in-class drug repurposing library, ReFRAME, against two high-throughput, high-content imaging infection assays: one using HeLa cells expressing SARS-CoV-2 receptor ACE2 and the other using lung epithelial Calu-3 cells. From nearly 12,000 compounds, we identify 49 (in HeLa-ACE2) and 41 (in Calu-3) compounds capable of selectively inhibiting SARS-CoV-2 replication. Notably, most screen hits are cell-line specific, likely due to different virus entry mechanisms or host cell-specific sensitivities to modulators. Among these promising hits, the antivirals nelfinavir and the parent of prodrug MK-4482 possess desirable in vitro activity, pharmacokinetic and human safety profiles, and both reduce SARS-CoV-2 replication in an orthogonal human differentiated primary cell model. Furthermore, MK-4482 effectively blocks SARS-CoV-2 infection in a hamster model. Overall, we identify direct-acting antivirals as the most promising compounds for drug repurposing, additional compounds that may have value in combination therapies, and tool compounds for identification of viral host cell targets.
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Affiliation(s)
- Malina A Bakowski
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA.
| | - Nathan Beutler
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Karen C Wolff
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | | | - Emily Chen
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Tu-Trinh H Nguyen
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Laura Riva
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Namir Shaabani
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Mara Parren
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - James Ricketts
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Anil K Gupta
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Kastin Pan
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Peiting Kuo
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - MacKenzie Fuller
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, USA
- HUMANOID CoRE, UC San Diego, La Jolla, CA, USA
| | - Elijah Garcia
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - John R Teijaro
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Linlin Yang
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Debashis Sahoo
- Department of Computer Science and Engineering, Jacobs School of Engineering, UC San Diego, La Jolla, CA, USA
- Department of Pediatrics, UC San Diego, La Jolla, CA, USA
| | - Victor Chi
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Edward Huang
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Natalia Vargas
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Amanda J Roberts
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, CA, USA
| | - Soumita Das
- HUMANOID CoRE, UC San Diego, La Jolla, CA, USA
- Department of Pathology, UC San Diego, La Jolla, CA, USA
| | - Pradipta Ghosh
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, USA
- HUMANOID CoRE, UC San Diego, La Jolla, CA, USA
- Department of Medicine, UC San Diego, La Jolla, CA, USA
| | - Ashley K Woods
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Sean B Joseph
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Mitchell V Hull
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Peter G Schultz
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Dennis R Burton
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | | | - Case W McNamara
- Calibr, a division of The Scripps Research Institute, La Jolla, CA, USA
| | - Thomas F Rogers
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA.
- UC San Diego Division of Infectious Diseases and Global Public Health, UC San Diego School of Medicine, La Jolla, CA, USA.
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6
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Arnold SL, Conrad T, McNamara C, Love M, Chi V, Woods A, Joseph S, Riggs M, Schaefer D, Betzer DP, Barrett L, Van Voorhis W, Tam PYI, Hermann D. Predicting the impact of infectious diarrhea pathophysiology on drug disposition. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.07532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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De Silva P, Stamatopoulos B, Chi V, Garaud S, Francois R, Thibaud V, Solinas C, Boisson A, Duvillier H, Rouas R, Lewalle P, Gallo K, Bron D. BACH2 AND FOXP1 GENE EXPRESSIONS ARE SIGNIFICANTLY ALTERED IN T AND B CELLS FROM CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS COMPARED TO AGED-MATCHED HEALTHY DONORS IMPACTING SURVIVAL. J Geriatr Oncol 2019. [DOI: 10.1016/s1879-4068(19)31173-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Lim RKV, Yu S, Cheng B, Li S, Kim NJ, Cao Y, Chi V, Kim JY, Chatterjee AK, Schultz PG, Tremblay MS, Kazane SA. Targeted Delivery of LXR Agonist Using a Site-Specific Antibody-Drug Conjugate. Bioconjug Chem 2015; 26:2216-22. [PMID: 25945727 DOI: 10.1021/acs.bioconjchem.5b00203] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Liver X receptor (LXR) agonists have been explored as potential treatments for atherosclerosis and other diseases based on their ability to induce reverse cholesterol transport and suppress inflammation. However, this therapeutic potential has been hindered by on-target adverse effects in the liver mediated by excessive lipogenesis. Herein, we report a novel site-specific antibody-drug conjugate (ADC) that selectively delivers a LXR agonist to monocytes/macrophages while sparing hepatocytes. The unnatural amino acid para-acetylphenylalanine (pAcF) was site-specifically incorporated into anti-CD11a IgG, which binds the α-chain component of the lymphocyte function-associated antigen 1 (LFA-1) expressed on nearly all monocytes and macrophages. An aminooxy-modified LXR agonist was conjugated to anti-CD11a IgG through a stable, cathepsin B cleavable oxime linkage to afford a chemically defined ADC. The anti-CD11a IgG-LXR agonist ADC induced LXR activation specifically in human THP-1 monocyte/macrophage cells in vitro (EC50-27 nM), but had no significant effect in hepatocytes, indicating that payload delivery is CD11a-mediated. Moreover, the ADC exhibited higher-fold activation compared to a conventional synthetic LXR agonist T0901317 (Tularik) (3-fold). This novel ADC represents a fundamentally different strategy that uses tissue targeting to overcome the limitations of LXR agonists for potential use in treating atherosclerosis.
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Affiliation(s)
- Reyna K V Lim
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Shan Yu
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Bo Cheng
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Sijia Li
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Nam-Jung Kim
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yu Cao
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Victor Chi
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ji Young Kim
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Arnab K Chatterjee
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Peter G Schultz
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States.,Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Matthew S Tremblay
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Stephanie A Kazane
- California Institute for Biomedical Research (Calibr) , 11119 North Torrey Pines Road, La Jolla, California 92037, United States
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9
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Kim MS, Ma JSY, Yun H, Cao Y, Kim JY, Chi V, Wang D, Woods A, Sherwood L, Caballero D, Gonzalez J, Schultz PG, Young TS, Kim CH. Redirection of genetically engineered CAR-T cells using bifunctional small molecules. J Am Chem Soc 2015; 137:2832-5. [PMID: 25692571 DOI: 10.1021/jacs.5b00106] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chimeric antigen receptor (CAR)-engineered T cells (CAR-Ts) provide a potent antitumor response and have become a promising treatment option for cancer. However, despite their efficacy, CAR-T cells are associated with significant safety challenges related to the inability to control their activation and expansion and terminate their response. Herein, we demonstrate that a bifunctional small molecule "switch" consisting of folate conjugated to fluorescein isothiocyanate (folate-FITC) can redirect and regulate FITC-specific CAR-T cell activity toward folate receptor (FR)-overexpressing tumor cells. This system was shown to be highly cytotoxic to FR-positive cells with no activity against FR-negative cells, demonstrating the specificity of redirection by folate-FITC. Anti-FITC-CAR-T cell activation and proliferation was strictly dependent on the presence of both folate-FITC and FR-positive cells and was dose titratable with folate-FITC switch. This novel treatment paradigm may ultimately lead to increased safety for CAR-T cell immunotherapy.
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Affiliation(s)
- Min Soo Kim
- California Institute for Biomedical Research , 11119 North Torrey Pines Road, Suite 100, La Jolla, California 92037, United States
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10
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Tarcha EJ, Chi V, Muñoz-Elías EJ, Bailey D, Londono LM, Upadhyay SK, Norton K, Banks A, Tjong I, Nguyen H, Hu X, Ruppert GW, Boley SE, Slauter R, Sams J, Knapp B, Kentala D, Hansen Z, Pennington MW, Beeton C, Chandy KG, Iadonato SP. Durable pharmacological responses from the peptide ShK-186, a specific Kv1.3 channel inhibitor that suppresses T cell mediators of autoimmune disease. J Pharmacol Exp Ther 2012; 342:642-53. [PMID: 22637724 DOI: 10.1124/jpet.112.191890] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Kv1.3 channel is a recognized target for pharmaceutical development to treat autoimmune diseases and organ rejection. ShK-186, a specific peptide inhibitor of Kv1.3, has shown promise in animal models of multiple sclerosis and rheumatoid arthritis. Here, we describe the pharmacokinetic-pharmacodynamic relationship for ShK-186 in rats and monkeys. The pharmacokinetic profile of ShK-186 was evaluated with a validated high-performance liquid chromatography-tandem mass spectrometry method to measure the peptide's concentration in plasma. These results were compared with single-photon emission computed tomography/computed tomography data collected with an ¹¹¹In-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-conjugate of ShK-186 to assess whole-blood pharmacokinetic parameters as well as the peptide's absorption, distribution, and excretion. Analysis of these data support a model wherein ShK-186 is absorbed slowly from the injection site, resulting in blood concentrations above the Kv1.3 channel-blocking IC₅₀ value for up to 7 days in monkeys. Pharmacodynamic studies on human peripheral blood mononuclear cells showed that brief exposure to ShK-186 resulted in sustained suppression of cytokine responses and may contribute to prolonged drug effects. In delayed-type hypersensitivity, chronic relapsing-remitting experimental autoimmune encephalomyelitis, and pristane-induced arthritis rat models, a single dose of ShK-186 every 2 to 5 days was as effective as daily administration. ShK-186's slow distribution from the injection site and its long residence time on the Kv1.3 channel contribute to the prolonged therapeutic effect of ShK-186 in animal models of autoimmune disease.
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Affiliation(s)
- Eric J Tarcha
- Kineta Inc., 219 Terry Ave N., Suite 300, Seattle, WA 98109-5208, USA.
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11
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Munoz E, Tarcha E, Londono L, Norton K, Banks A, Chi V, Beeton C, Chandy K, Iadonato S. Durable pharmacological responses from the peptide drug ShK-186, a specific Kv1.3 channel inhibitor that suppresses T cell mediators of autoimmune disease (51.5). The Journal of Immunology 2012. [DOI: 10.4049/jimmunol.188.supp.51.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
The Potassium Kv1.3 channel on effector memory T cells is a target to treat autoimmune diseases. ShK-186, a specific peptide inhibitor of Kv1.3, has shown promise in animal models of multiple sclerosis and rheumatoid arthritis. Here, we describe the development of methods to establish a pharmacokinetic (PK) - pharmacodynamic (PD) relationship for ShK-186, and test the hypothesis that the drug has a sustained PD effect in autoimmune disease models. The PK of ShK-186 was evaluated in rats and cynomolgus monkeys using HPLC-MS/MS and ELISA methods to measure the free fraction in plasma. These results were compared with SPECT/CT data collected with an 111In-DOTA-conjugate of ShK to assess whole blood PK parameters as well as the drug’s absorption, distribution and excretion. Our data suggest ShK-186 is absorbed slowly from the injection site resulting in blood concentrations above the Kv1.3 channel-blocking Kd for up to 7 days in monkey. PD studies on human peripheral blood mononuclear cells show that transient ShK-186 treatment results in a sustained suppression of cytokine responses and may contribute to prolonged drug effects. Moreover, in rat delayed-type hypersensitivity and chronic relapsing experimental autoimmune encephalomyelitis, a single dose of drug every 3 - 5 days is as effective as daily administration. These data suggest the PD effects of ShK-186 are governed primarily by slow distribution from peripheral tissues and long residence time on the Kv1.3 channel.
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Affiliation(s)
| | | | | | | | | | - Victor Chi
- 3Department of Physiology and Biophysics and the Department of Surgery, UC Irvine, Irvine, CA
| | - Christine Beeton
- 2Molecular Physiology and Biophysics, Baylor Col. of Medicne, Houston, TX
| | - K. Chandy
- 3Department of Physiology and Biophysics and the Department of Surgery, UC Irvine, Irvine, CA
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12
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Chi V, Pennington MW, Norton RS, Tarcha EJ, Londono LM, Sims-Fahey B, Upadhyay SK, Lakey JT, Iadonato S, Wulff H, Beeton C, Chandy KG. Development of a sea anemone toxin as an immunomodulator for therapy of autoimmune diseases. Toxicon 2011; 59:529-46. [PMID: 21867724 DOI: 10.1016/j.toxicon.2011.07.016] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/16/2011] [Accepted: 07/20/2011] [Indexed: 01/05/2023]
Abstract
Electrophysiological and pharmacological studies coupled with molecular identification have revealed a unique network of ion channels--Kv1.3, KCa3.1, CRAC (Orai1 + Stim1), TRPM7, Cl(swell)--in lymphocytes that initiates and maintains the calcium signaling cascade required for activation. The expression pattern of these channels changes during lymphocyte activation and differentiation, allowing the functional network to adapt during an immune response. The Kv1.3 channel is of interest because it plays a critical role in subsets of T and B lymphocytes implicated in autoimmune disorders. The ShK toxin from the sea anemone Stichodactyla helianthus is a potent blocker of Kv1.3. ShK-186, a synthetic analog of ShK, is being developed as a therapeutic for autoimmune diseases, and is scheduled to begin first-in-man phase-1 trials in 2011. This review describes the journey that has led to the development of ShK-186.
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Affiliation(s)
- Victor Chi
- Department of Physiology and Biophysics, UC Irvine, Irvine, CA 92697, USA
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13
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Chi V, Tarcha EJ, Lechuga TJ, Nguyen HM, Pennington MW, Iadonato SP, Chandy KG. Development of a competition ELISA to assess stability and measure ShK‐186 in plasma samples. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.812.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Victor Chi
- Physiology and BiophysicsUniversity of CaliforniaIrvineIrvineCA
| | | | | | - Hai M Nguyen
- Physiology and BiophysicsUniversity of CaliforniaIrvineIrvineCA
| | | | | | - K George Chandy
- Physiology and BiophysicsUniversity of CaliforniaIrvineIrvineCA
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14
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Abstract
We discuss the potential use of inhibitors of Kv1.3 potassium channels in T lymphocytes as therapeutics for multiple sclerosis. Current treatment strategies target the immune system in a non-selective manner. The resulting general immunosuppression, toxic side-effects and increased risk of opportunistic infections create the need for more selective therapeutics. Autoreactive effector-memory T (T(EM)) cells, considered to be major mediators of autoimmunity, express large numbers of Kv1.3 channels. Selective blockers of Kv1.3 inhibit calcium signaling, cytokine production and proliferation of T(EM) cells in vitro, and T(EM) cell-motility in vivo. Kv1.3 blockers ameliorate disease in animal models of multiple sclerosis, rheumatoid arthritis, type 1 diabetes mellitus and contact dermatitis without compromising the protective immune response to acute infections. Kv1.3 blockers have a good safety profile in rodents and primates.
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Affiliation(s)
- Srikant Rangaraju
- University of California, Department of Physiology and Biophysics, Irvine, California 92697, USA
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15
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Rangaraju S, Khoo KK, Feng ZP, Crossley G, Nugent D, Khaytin I, Chi V, Pham C, Calabresi P, Pennington MW, Norton RS, Chandy KG. Potassium channel modulation by a toxin domain in matrix metalloprotease 23. J Biol Chem 2009; 285:9124-36. [PMID: 19965868 DOI: 10.1074/jbc.m109.071266] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peptide toxins found in a wide array of venoms block K(+) channels, causing profound physiological and pathological effects. Here we describe the first functional K(+) channel-blocking toxin domain in a mammalian protein. MMP23 (matrix metalloprotease 23) contains a domain (MMP23(TxD)) that is evolutionarily related to peptide toxins from sea anemones. MMP23(TxD) shows close structural similarity to the sea anemone toxins BgK and ShK. Moreover, this domain blocks K(+) channels in the nanomolar to low micromolar range (Kv1.6 > Kv1.3 > Kv1.1 = Kv3.2 > Kv1.4, in decreasing order of potency) while sparing other K(+) channels (Kv1.2, Kv1.5, Kv1.7, and KCa3.1). Full-length MMP23 suppresses K(+) channels by co-localizing with and trapping MMP23(TxD)-sensitive channels in the ER. Our results provide clues to the structure and function of the vast family of proteins that contain domains related to sea anemone toxins. Evolutionary pressure to maintain a channel-modulatory function may contribute to the conservation of this domain throughout the plant and animal kingdoms.
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Affiliation(s)
- Srikant Rangaraju
- Department of Physiology and Biophysics, University of California, Irvine, California 92697, USA
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16
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Pennington MW, Beeton C, Galea CA, Smith BJ, Chi V, Monaghan KP, Garcia A, Rangaraju S, Giuffrida A, Plank D, Crossley G, Nugent D, Khaytin I, Lefievre Y, Peshenko I, Dixon C, Chauhan S, Orzel A, Inoue T, Hu X, Moore RV, Norton RS, Chandy KG. Engineering a stable and selective peptide blocker of the Kv1.3 channel in T lymphocytes. Mol Pharmacol 2009; 75:762-73. [PMID: 19122005 DOI: 10.1124/mol.108.052704] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Kv1.3 potassium channels maintain the membrane potential of effector memory (T(EM)) T cells that are important mediators of multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis. The polypeptide ShK-170 (ShK-L5), containing an N-terminal phosphotyrosine extension of the Stichodactyla helianthus ShK toxin, is a potent and selective blocker of these channels. However, a stability study of ShK-170 showed minor pH-related hydrolysis and oxidation byproducts that were exacerbated by increasing temperatures. We therefore engineered a series of analogs to minimize the formation of these byproducts. The analog with the greatest stability, ShK-192, contains a nonhydrolyzable phosphotyrosine surrogate, a methionine isostere, and a C-terminal amide. ShK-192 shows the same overall fold as ShK, and there is no evidence of any interaction between the N-terminal adduct and the rest of the peptide. The docking configuration of ShK-192 in Kv1.3 shows the N-terminal para-phosphonophenylalanine group lying at the junction of two channel monomers to form a salt bridge with Lys(411) of the channel. ShK-192 blocks Kv1.3 with an IC(50) of 140 pM and exhibits greater than 100-fold selectivity over closely related channels. After a single subcutaneous injection of 100 microg/kg, approximately 100 to 200 pM concentrations of active peptide is detectable in the blood of Lewis rats 24, 48, and 72 h after the injection. ShK-192 effectively inhibits the proliferation of T(EM) cells and suppresses delayed type hypersensitivity when administered at 10 or 100 microg/kg by subcutaneous injection once daily. ShK-192 has potential as a therapeutic for autoimmune diseases mediated by T(EM) cells.
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Affiliation(s)
- M W Pennington
- Bachem Bioscience Inc., King of Prussia, Pennsylvania, USA
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17
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Matheu MP, Beeton C, Garcia A, Chi V, Rangaraju S, Safrina O, Monaghan K, Uemura MI, Li D, Pal S, de la Maza LM, Monuki E, Flügel A, Pennington MW, Parker I, Chandy KG, Cahalan MD. Imaging of effector memory T cells during a delayed-type hypersensitivity reaction and suppression by Kv1.3 channel block. Immunity 2008; 29:602-14. [PMID: 18835197 DOI: 10.1016/j.immuni.2008.07.015] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Revised: 12/03/2007] [Accepted: 07/09/2008] [Indexed: 01/07/2023]
Abstract
Effector memory T (Tem) cells are essential mediators of autoimmune disease and delayed-type hypersensitivity (DTH), a convenient model for two-photon imaging of Tem cell participation in an inflammatory response. Shortly (3 hr) after entry into antigen-primed ear tissue, Tem cells stably attached to antigen-bearing antigen-presenting cells (APCs). After 24 hr, enlarged Tem cells were highly motile along collagen fibers and continued to migrate rapidly for 18 hr. Tem cells rely on voltage-gated Kv1.3 potassium channels to regulate calcium signaling. ShK-186, a specific Kv1.3 blocker, inhibited DTH and suppressed Tem cell enlargement and motility in inflamed tissue but had no effect on homing to or motility in lymph nodes of naive and central memory T (Tcm) cells. ShK-186 effectively treated disease in a rat model of multiple sclerosis. These results demonstrate a requirement for Kv1.3 channels in Tem cells during an inflammatory immune response in peripheral tissues. Targeting Kv1.3 allows for effector memory responses to be suppressed while central memory responses remain intact.
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Affiliation(s)
- Melanie P Matheu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA 92697-4561, USA
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Zhang SL, Kozak JA, Jiang W, Yeromin AV, Chen J, Yu Y, Penna A, Shen W, Chi V, Cahalan MD. Store-dependent and -independent modes regulating Ca2+ release-activated Ca2+ channel activity of human Orai1 and Orai3. J Biol Chem 2008; 283:17662-71. [PMID: 18420579 DOI: 10.1074/jbc.m801536200] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
We evaluated currents induced by expression of human homologs of Orai together with STIM1 in human embryonic kidney cells. When co-expressed with STIM1, Orai1 induced a large inwardly rectifying Ca(2+)-selective current with Ca(2+)-induced slow inactivation. A point mutation of Orai1 (E106D) altered the ion selectivity of the induced Ca(2+) release-activated Ca(2+) (CRAC)-like current while retaining an inwardly rectifying I-V characteristic. Expression of the C-terminal portion of STIM1 with Orai1 was sufficient to generate CRAC current without store depletion. 2-APB activated a large relatively nonselective current in STIM1 and Orai3 co-expressing cells. 2-APB also induced Ca(2+) influx in Orai3-expressing cells without store depletion or co-expression of STIM1. The Orai3 current induced by 2-APB exhibited outward rectification and an inward component representing a mixed calcium and monovalent current. A pore mutant of Orai3 inhibited store-operated Ca(2+) entry and did not carry significant current in response to either store depletion or addition of 2-APB. Analysis of a series of Orai1-3 chimeras revealed the structural determinant responsible for 2-APB-induced current within the sequence from the second to third transmembrane segment of Orai3. The Orai3 current induced by 2-APB may reflect a store-independent mode of CRAC channel activation that opens a relatively nonselective cation pore.
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Affiliation(s)
- Shenyuan L Zhang
- Department of Physiology and Biophysics, University of California, Irvine, California 92697, USA
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19
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Beeton C, Smith BJ, Sabo JK, Crossley G, Nugent D, Khaytin I, Chi V, Chandy KG, Pennington MW, Norton RS. The D-Diastereomer of ShK Toxin Selectively Blocks Voltage-gated K+ Channels and Inhibits T Lymphocyte Proliferation. J Biol Chem 2008; 283:988-97. [DOI: 10.1074/jbc.m706008200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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20
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Abstract
Immunohistochemistry (IHC) is a valuable technique utilized to localize/visualize protein expression in a mounted tissue section using specific antibodies. There are two methods: the direct and indirect method. In this experiment, we will only describe the use of indirect IHC staining. Indirect IHC staining utilizes highly specific primary and biotin-conjugated secondary antibodies. Primary antibodies are utilized to discretely identify proteins of interest by binding to a specific epitope, while secondary antibodies subtract for non-specific background staining and amplify signal by forming complexes to the primary antibody. Slides can either be generated from frozen sections, or paraffin embedded sections mounted on glass slides. In this protocol, we discuss the preparation of paraffin-embedded sections by dewaxing, hydration using an alcohol gradient, heat induced antigen retrieval, and blocking of endogenous peroxidase activity and non-specific binding sites. Some sections are then stained with antibodies specific for T cell marker CD8 and while others are stained for tyrosine hydroxylase. The slides are subsequently treated with appropriate secondary antibodies conjugated to biotin, then developed utilizing avidin-conjugated horseradish peroxidase (HRP) with Diaminiobenzidine (DAB) as substrate. Following development, the slides are counterstained for contrast, and mounted under coverslips with permount. After adequate drying, these slides are then ready for imaging.
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Affiliation(s)
- Victor Chi
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA.
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21
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McConnachie L, Bodor M, Kowdley K, Levy A, Tung B, Thummel K, Phillips B, Bajpai M, Chi V, Esmay JD, Shen DD, Ho RJY. Human liver cytochrome P450 2D6 genotype, full-length messenger ribonucleic acid, and activity assessed with a novel cytochrome P450 2D6 substrate*1. Clin Pharmacol Ther 2004; 75:282-97. [PMID: 15060507 DOI: 10.1016/j.clpt.2003.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The goal of this study was to develop and validate a cytochrome P450 (CYP) 2D6 probe substrate with improved sensitivity to elucidate the relationship of CYP2D6 ribonucleic acid transcript levels, genotype, and enzyme activity in human liver biopsy samples. METHODS CYP2D6 activity in tissue homogenates of liver biopsy specimens collected from control subjects (with no apparent liver disease), liver biopsy subjects, liver transplant subjects, and liver bank specimens was assessed with a calcimimetic, R-568, a high-clearance and specific substrate of CYP2D6. The livers were genotyped for the 6 most common CYP2D6 genetic variants (ie, *3, *4, *5, *6, *7, and *8). The 1.5-kilobase CYP2D6 messenger ribonucleic acid (referred to as full-length) transcripts were estimated with a semiquantitative reverse transcription-polymerase chain reaction assay. RESULTS As a CYP2D6-specific catalytic probe, R-568 offers a 20-fold higher sensitivity compared with that of dextromethorphan. The improved assay sensitivity allowed evaluation of CYP2D6 enzyme activity in a few milligrams of tissue collected from biopsy specimens. The ratio of CYP2D6 enzyme activity to transcript remained relatively constant within each group of subjects, especially within the control group. However, mean activity to transcript varied greatly across the 4 groups of subjects. The liver samples in the control group showed significantly higher enzyme activity but a lower transcript level. CONCLUSIONS A combination of genotyping and messenger ribonucleic acid level determination could allow a quantitative estimation of functional CYP2D6 activity in healthy human livers with a reasonable degree of confidence. Kinetic study with R-568 indicates that this compound is probably the most sensitive CYP2D6 probe substrate available.
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Affiliation(s)
- Lisa McConnachie
- Department of Pharmaceutics, Medicine, Surgery and Pharmacy, University of Washington, Seattle, WA 98195-7610, USA
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Abstract
Understanding the relative motion of objects in contact is essential for controlling macroscopic lubrication and adhesion, for comprehending biological macromolecular interfaces, and for developing submicrometre-scale electromechanical devices. An object undergoing lateral motion while in contact with a second object can either roll or slide. The resulting energy loss and mechanical wear depend largely on which mode of motion occurs. At the macroscopic scale, rolling is preferred over sliding, and it is expected to have an equally important role in the microscopic domain. Although progress has been made in our understanding of the dynamics of sliding at the atomic level, we have no comparable insight into rolling owing to a lack of experimental data on microscopic length scales. Here we produce controlled rolling of carbon nanotubes on graphite surfaces using an atomic force microscope. We measure the accompanying energy loss and compare this with sliding. Moreover, by reproducibly rolling a nanotube to expose different faces to the substrate and to an external probe, we are able to study the object over its complete surface.
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Affiliation(s)
- M R Falvo
- Department of Physics and Astronomy, North Carolina Center for Nanoscale Materials, University of North Carolina, Chapel Hill 27599, USA
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Falvo MR, Clary G, Helser A, Paulson S, Taylor RM, Chi V, Brooks FP, Washburn S, Superfine R. Nanomanipulation Experiments Exploring Frictional and Mechanical Properties of Carbon Nanotubes. Microsc Microanal 1998; 4:504-512. [PMID: 9990873 DOI: 10.1017/s1431927698980485] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
: In many cases in experimental science, the instrument interface becomes a limiting factor in the efficacy of carrying out unusual experiments or prevents the complete understanding of the acquired data. We have developed an advanced interface for scanning probe microscopy (SPM) that allows intuitive rendering of data sets and natural instrument control, all in real time. The interface, called the nanoManipulator, combines a high-performance graphics engine for real-time data rendering with a haptic interface that places the human operator directly into the feedback loop that controls surface manipulations. Using a hand-held stylus, the operator moves the stylus laterally, directing the movement of the SPM tip across the sample. The haptic interface enables the user to "feel" the surface by forcing the stylus to move up and down in response to the surface topography. In this way the user understands the immediate location of the tip on the sample and can quickly and precisely maneuver nanometer-scale objects. We have applied this interface to studies of the mechanical properties of nanotubes and to substrate-nanotube interactions. The mechanical properties of carbon nanotubes have been demonstrated to be extraordinary. They have an elastic modulus rivaling that of the stiffest material known, diamond, while maintaining a remarkable resistance to fracture. We have used atomic-force microscopy (AFM) to manipulate the nanotubes through a series of configuration that reveal buckling behavior and high-strain resilience. Nanotubes also serve as test objects for nanometer-scale contact mechanics. We have found that nanotubes will roll under certain conditions. This has been determined through changes in the images and through the acquisition of lateral force during manipulation. The lateral force data show periodic stick-slip behavior with a periodicity matching the perimeter of the nanotube.
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Affiliation(s)
- MR Falvo
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255
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24
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Abstract
The curling of a graphitic sheet to form carbon nanotubes produces a class of materials that seem to have extraordinary electrical and mechanical properties. In particular, the high elastic modulus of the graphite sheets means that the nanotubes might be stiffer and stronger than any other known material, with beneficial consequences for their application in composite bulk materials and as individual elements of nanometre-scale devices and sensors. The mechanical properties are predicted to be sensitive to details of their structure and to the presence of defects, which means that measurements on individual nanotubes are essential to establish these properties. Here we show that multiwalled carbon nanotubes can be bent repeatedly through large angles using the tip of an atomic force microscope, without undergoing catastrophic failure. We observe a range of responses to this high-strain deformation, which together suggest that nanotubes are remarkably flexible and resilient.
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Affiliation(s)
- M R Falvo
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill 27599, USA
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25
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Abstract
We present our results on the manipulation of individual viruses using an advanced interface for atomic force microscopes (AFMs). We show that the viruses can be dissected, rotated, and translated with great facility. We interpret the behavior of tobacco mosaic virus with a mechanical model that makes explicit the competition between sample-substrate lateral friction and the flexural rigidity of the manipulated object. The manipulation behavior of tobacco mosaic virus on graphite is shown to be consistent with values of lateral friction observed on similar interfaces and the flexural rigidity expected for macromolecular assemblies. The ability to manipulate individual samples broadens the scope of possible studies by providing a means for positioning samples at specific binding sites or predefined measuring devices. The mechanical model provides a framework for interpreting quantitative measurements of virus binding and mechanical properties and for understanding the constraints on the successful, nondestructive AFM manipulation of delicate samples.
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Affiliation(s)
- M R Falvo
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill 27599, USA
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