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Liu G, Lipari P, Mollin A, Jung S, Teplova I, Li W, Ying L, More V, Lennox W, Yeh S, McGann E, Moon YC, Rice C, Huarte E, Gruszka B, Ray B, Goodwin E, Buckendahl P, Yurkow E, Braughton B, Narasimhan J, Welch E, Voronin G, Weetall M. Comparison of pharmaceutical properties and biological activities of prednisolone, deflazacort, and vamorolone in DMD disease models. Hum Mol Genet 2024; 33:211-223. [PMID: 37819629 PMCID: PMC10800023 DOI: 10.1093/hmg/ddad173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 09/26/2023] [Accepted: 10/09/2023] [Indexed: 10/13/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a progressive disabling X-linked recessive disorder that causes gradual and irreversible loss of muscle, resulting in early death. The corticosteroids prednisone/prednisolone and deflazacort are used to treat DMD as the standard of care; however, only deflazacort is FDA approved for DMD. The novel atypical corticosteroid vamorolone is being investigated for treatment of DMD. We compared the pharmaceutical properties as well as the efficacy and safety of the three corticosteroids across multiple doses in the B10-mdx DMD mouse model. Pharmacokinetic studies in the mouse and evaluation of p-glycoprotein (P-gP) efflux in a cellular system demonstrated that vamorolone is not a strong P-gp substrate resulting in measurable central nervous system (CNS) exposure in the mouse. In contrast, deflazacort and prednisolone are strong P-gp substrates. All three corticosteroids showed efficacy, but also side effects at efficacious doses. After dosing mdx mice for two weeks, all three corticosteroids induced changes in gene expression in the liver and the muscle, but prednisolone and vamorolone induced more changes in the brain than did deflazacort. Both prednisolone and vamorolone induced depression-like behavior. All three corticosteroids reduced endogenous corticosterone levels, increased glucose levels, and reduced osteocalcin levels. Using micro-computed tomography, femur bone density was decreased, reaching significance with prednisolone. The results of these studies indicate that efficacious doses of vamorolone, are associated with similar side effects as seen with other corticosteroids. Further, because vamorolone is not a strong P-gp substrate, vamorolone distributes into the CNS increasing the potential CNS side-effects.
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Affiliation(s)
- Grace Liu
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Philip Lipari
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Anna Mollin
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Stephen Jung
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Irina Teplova
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Wencheng Li
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Lanqing Ying
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Vijay More
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - William Lennox
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Shirley Yeh
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Eric McGann
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Young-Choon Moon
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Cari Rice
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Eduardo Huarte
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Barbara Gruszka
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Balmiki Ray
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Elizabeth Goodwin
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Patricia Buckendahl
- Rutgers University, Molecular Imaging Center, 41 Gordon Road, Piscataway, NJ 08854, United States
| | - Edward Yurkow
- Rutgers University, Molecular Imaging Center, 41 Gordon Road, Piscataway, NJ 08854, United States
| | - Bruce Braughton
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Jana Narasimhan
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Ellen Welch
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Gregory Voronin
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
| | - Marla Weetall
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, United States
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2
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Schultz A, Cheng SY, Kirchner E, Costello S, Miettinen H, Chaverra M, King C, George L, Zhao X, Narasimhan J, Weetall M, Slaugenhaupt S, Morini E, Punzo C, Lefcort F. Reduction of retinal ganglion cell death in mouse models of familial dysautonomia using AAV-mediated gene therapy and splicing modulators. Sci Rep 2023; 13:18600. [PMID: 37903840 PMCID: PMC10616160 DOI: 10.1038/s41598-023-45376-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 10/18/2023] [Indexed: 11/01/2023] Open
Abstract
Familial dysautonomia (FD) is a rare neurodevelopmental and neurodegenerative disease caused by a splicing mutation in the Elongator Acetyltransferase Complex Subunit 1 (ELP1) gene. The reduction in ELP1 mRNA and protein leads to the death of retinal ganglion cells (RGCs) and visual impairment in all FD patients. Currently patient symptoms are managed, but there is no treatment for the disease. We sought to test the hypothesis that restoring levels of Elp1 would thwart the death of RGCs in FD. To this end, we tested the effectiveness of two therapeutic strategies for rescuing RGCs. Here we provide proof-of-concept data that gene replacement therapy and small molecule splicing modifiers effectively reduce the death of RGCs in mouse models for FD and provide pre-clinical foundational data for translation to FD patients.
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Affiliation(s)
- Anastasia Schultz
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Shun-Yun Cheng
- Department of Ophthalmology, Neurobiology and Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Emily Kirchner
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Stephanann Costello
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Heini Miettinen
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Marta Chaverra
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Colin King
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Lynn George
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
- Department of Biological and Physical Science, Montana State University Billings, Billings, MT, USA
| | - Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ, 07080, USA
| | | | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ, 07080, USA
| | - Susan Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA
| | - Elisabetta Morini
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA
| | - Claudio Punzo
- Department of Ophthalmology, Neurobiology and Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Frances Lefcort
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA.
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3
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Schultz A, Cheng SY, Kirchner E, Costello S, Miettinen H, Chaverra M, King C, George L, Zhao X, Narasimhan J, Weetall M, Slaugenhaupt S, Morini E, Punzo C, Lefcort F. Reduction of retinal ganglion cell death in mouse models of familial dysautonomia using AAV-mediated gene therapy and splicing modulators. bioRxiv 2023:2023.05.22.541535. [PMID: 37293016 PMCID: PMC10245894 DOI: 10.1101/2023.05.22.541535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Familial dysautonomia (FD) is a rare neurodevelopmental and neurodegenerative disease caused by a splicing mutation in the Elongator Acetyltransferase Complex Subunit 1 ( ELP1 ) gene. The reduction in ELP1 mRNA and protein leads to the death of retinal ganglion cells (RGCs) and visual impairment in all FD patients. Currently, patient symptoms are managed, but there is no treatment for the disease. We sought to test the hypothesis that restoring levels of Elp1 would thwart the death of RGCs in FD. To this end, we tested the effectiveness of two therapeutic strategies for rescuing RGCs. Here we provide proof-of-concept data that gene replacement therapy and small molecule splicing modifiers effectively reduce the death of RGCs in mouse models for FD and provide pre-clinical data foundation for translation to FD patients.
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4
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Morini E, Chekuri A, Logan EM, Bolduc JM, Kirchner EG, Salani M, Krauson AJ, Narasimhan J, Gabbeta V, Grover S, Dakka A, Mollin A, Jung SP, Zhao X, Zhang N, Zhang S, Arnold M, Woll MG, Naryshkin NA, Weetall M, Slaugenhaupt SA. Development of an oral treatment that rescues gait ataxia and retinal degeneration in a phenotypic mouse model of familial dysautonomia. Am J Hum Genet 2023; 110:531-547. [PMID: 36809767 PMCID: PMC10027479 DOI: 10.1016/j.ajhg.2023.01.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/30/2023] [Indexed: 02/22/2023] Open
Abstract
Familial dysautonomia (FD) is a rare neurodegenerative disease caused by a splicing mutation in elongator acetyltransferase complex subunit 1 (ELP1). This mutation leads to the skipping of exon 20 and a tissue-specific reduction of ELP1, mainly in the central and peripheral nervous systems. FD is a complex neurological disorder accompanied by severe gait ataxia and retinal degeneration. There is currently no effective treatment to restore ELP1 production in individuals with FD, and the disease is ultimately fatal. After identifying kinetin as a small molecule able to correct the ELP1 splicing defect, we worked on its optimization to generate novel splicing modulator compounds (SMCs) that can be used in individuals with FD. Here, we optimize the potency, efficacy, and bio-distribution of second-generation kinetin derivatives to develop an oral treatment for FD that can efficiently pass the blood-brain barrier and correct the ELP1 splicing defect in the nervous system. We demonstrate that the novel compound PTC258 efficiently restores correct ELP1 splicing in mouse tissues, including brain, and most importantly, prevents the progressive neuronal degeneration that is characteristic of FD. Postnatal oral administration of PTC258 to the phenotypic mouse model TgFD9;Elp1Δ20/flox increases full-length ELP1 transcript in a dose-dependent manner and leads to a 2-fold increase in functional ELP1 in the brain. Remarkably, PTC258 treatment improves survival, gait ataxia, and retinal degeneration in the phenotypic FD mice. Our findings highlight the great therapeutic potential of this novel class of small molecules as an oral treatment for FD.
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Affiliation(s)
- Elisabetta Morini
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA.
| | - Anil Chekuri
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA; Grousbeck Gene Therapy Center, Schepens Eye Research Institute and Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Emily M Logan
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Jessica M Bolduc
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Emily G Kirchner
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Monica Salani
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Aram J Krauson
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | | | | | | | - Amal Dakka
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Anna Mollin
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | - Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Nanjing Zhang
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Sophie Zhang
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | | | | | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Susan A Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA.
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5
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Zaworski PG, Schwartz R, Burr J, Skutnik D, Mollin A, Kumar B, Ngumah Q, Welch E, Johnson B, Narasimhan J, Weetall M. Quantitation of Pax-6 protein in ocular impression cytology samples using an electrochemiluminescence immunoassay. Anal Biochem 2022; 656:114876. [PMID: 36058293 DOI: 10.1016/j.ab.2022.114876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/15/2022]
Abstract
Paired box protein Pax-6 (oculothrombin) is a transcription factor that plays an important regulatory role in ocular, brain, and pancreatic development. Mutations of the PAX6 gene cause aniridia and Peters anomaly. Reduction in Pax-6 protein is also associated with ocular diseases such as dry eye. An electrochemiluminescence immunoassay method using the Meso Scale Discovery platform was developed to measure Pax-6 protein levels in corneal epithelial cells obtained by impression cytology. Impression cytology involves harvesting ocular epithelial cells by applying a polyethersulfone membrane patch briefly to the ocular surface using a commercially available EYEPRIM™ device. The epithelial cells that adhere to the membrane patch of the EYEPRIM™ device provide a biological sample which can be assayed for Pax-6 protein levels. Assay development identified an antibody pair capable of detecting purified recombinant Pax-6 protein produced in mammalian cells. The optimized assay has a dynamic range of 24 pg mL-1 to 100,000 pg mL-1 and a lower limit of quantification of 24 pg mL-1. Assay selectivity was demonstrated using either HeLa or HEK293 cells transfected with inhibitory RNA. Finally, the method was validated by measuring Pax-6 protein levels in impression cytology acquired samples obtained using the EYEPRIM™ device from rabbit cornea.
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Affiliation(s)
| | | | - Jeffrey Burr
- PharmOptima, 6710 Quality Way, Portage, MI, 49002, USA
| | | | - Anna Mollin
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA
| | - Binit Kumar
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA
| | - Quintus Ngumah
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA
| | - Ellen Welch
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA
| | - Briana Johnson
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA
| | - Jana Narasimhan
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA
| | - Marla Weetall
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ, 07080, USA.
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6
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Narasimhan J, Letinski S, Jung SP, Gerasyuto A, Wang J, Arnold M, Chen G, Hedrick J, Dumble M, Ravichandran K, Levitz T, Cui C, Drennan CL, Stubbe J, Karp G, Branstrom A. Ribonucleotide reductase, a novel drug target for gonorrhea. eLife 2022; 11:e67447. [PMID: 35137690 PMCID: PMC8865847 DOI: 10.7554/elife.67447] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [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: 02/11/2021] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
Antibiotic-resistant Neisseria gonorrhoeae (Ng) are an emerging public health threat due to increasing numbers of multidrug resistant (MDR) organisms. We identified two novel orally active inhibitors, PTC-847 and PTC-672, that exhibit a narrow spectrum of activity against Ng including MDR isolates. By selecting organisms resistant to the novel inhibitors and sequencing their genomes, we identified a new therapeutic target, the class Ia ribonucleotide reductase (RNR). Resistance mutations in Ng map to the N-terminal cone domain of the α subunit, which we show here is involved in forming an inhibited α4β4 state in the presence of the β subunit and allosteric effector dATP. Enzyme assays confirm that PTC-847 and PTC-672 inhibit Ng RNR and reveal that allosteric effector dATP potentiates the inhibitory effect. Oral administration of PTC-672 reduces Ng infection in a mouse model and may have therapeutic potential for treatment of Ng that is resistant to current drugs.
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Affiliation(s)
| | | | | | | | - Jiashi Wang
- PTC Therapeutics, IncSouth PlainfieldUnited States
| | | | | | - Jean Hedrick
- PTC Therapeutics, IncSouth PlainfieldUnited States
| | | | - Kanchana Ravichandran
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Talya Levitz
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Chang Cui
- Department of Chemistry and Chemical Biology, Harvard UniversityCambridgeUnited States
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
- Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - JoAnne Stubbe
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Gary Karp
- PTC Therapeutics, IncSouth PlainfieldUnited States
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7
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Zhao X, Feng Z, Risher N, Mollin A, Sheedy J, Ling KKY, Narasimhan J, Dakka A, Baird JD, Ratni H, Lutz C, Chen K, Naryshkin N, Ko CP, Welch E, Metzger F, Weetall M. SMN protein is required throughout life to prevent spinal muscular atrophy disease progression. Hum Mol Genet 2021; 31:82-96. [PMID: 34368854 DOI: 10.1093/hmg/ddab220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/19/2021] [Accepted: 07/22/2021] [Indexed: 11/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by the loss of the survival motor neuron 1 (SMN1) gene function. The related SMN2 gene partially compensates but produces insufficient levels of SMN protein due to alternative splicing of exon 7. Evrysdi™ (risdiplam), recently approved for the treatment of SMA, and related compounds promote exon 7 inclusion to generate full-length SMN2 mRNA and increase SMN protein levels. SMNΔ7 type I SMA mice survive without treatment for ~ 17 days. SMN2 mRNA splicing modulators increase survival of SMN∆7 mice with treatment initiated at postnatal day 3 (PND3). To define SMN requirements for adult mice, SMNΔ7 mice were dosed with a SMN2 mRNA splicing modifier from PND3 to PND40, then dosing was stopped. Mice not treated after PND40 showed progressive weight loss, necrosis, and muscle atrophy after ~ 20 days. Male mice presented a more severe phenotype than female mice. Mice dosed continuously did not show disease symptoms. The estimated half-life of SMN protein is 2 days indicating that the SMA phenotype reappeared after SMN protein levels returned to baseline. Although SMN protein levels decreased with age in mice and SMN protein levels were higher in brain than in muscle, our studies suggest that SMN protein is required throughout the life of the mouse and is especially essential in adult peripheral tissues including muscle. These studies indicate that drugs such as risdiplam will be optimally therapeutic when given as early as possible after diagnosis and potentially will be required for the life of an SMA patient.
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Affiliation(s)
- Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Zhihua Feng
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Nicole Risher
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Anna Mollin
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | - Karen K Y Ling
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | | | - Amal Dakka
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - John D Baird
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Hasane Ratni
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | | | | | | | - Chien-Ping Ko
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Ellen Welch
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Friedrich Metzger
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
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8
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Gerasyuto AI, Arnold MA, Wang J, Chen G, Zhang X, Smith S, Woll MG, Baird J, Zhang N, Almstead NG, Narasimhan J, Peddi S, Dumble M, Sheedy J, Weetall M, Branstrom AA, Prasad JVN, Karp GM. Correction to Discovery and Optimization of Indolyl-Containing 4-Hydroxy-2-pyridone Type II DNA Topoisomerase Inhibitors Active against Multidrug Resistant Gram-Negative Bacteria. J Med Chem 2018; 61:9394. [PMID: 30351051 PMCID: PMC8154551 DOI: 10.1021/acs.jmedchem.8b01538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Gerasyuto AI, Arnold MA, Wang J, Chen G, Zhang X, Smith S, Woll MG, Baird J, Zhang N, Almstead NG, Narasimhan J, Peddi S, Dumble M, Sheedy J, Weetall M, Branstrom AA, Prasad JVN, Karp GM. Discovery and Optimization of Indolyl-Containing 4-Hydroxy-2-Pyridone Type II DNA Topoisomerase Inhibitors Active against Multidrug Resistant Gram-negative Bacteria. J Med Chem 2018; 61:4456-4475. [PMID: 29727185 PMCID: PMC5991783 DOI: 10.1021/acs.jmedchem.8b00114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
There exists an urgent medical need to identify new chemical entities (NCEs) targeting multidrug resistant (MDR) bacterial infections, particularly those caused by Gram-negative pathogens. 4-Hydroxy-2-pyridones represent a novel class of nonfluoroquinolone inhibitors of bacterial type II topoisomerases active against MDR Gram-negative bacteria. Herein, we report on the discovery and structure-activity relationships of a series of fused indolyl-containing 4-hydroxy-2-pyridones with improved in vitro antibacterial activity against fluoroquinolone resistant strains. Compounds 6o and 6v are representative of this class, targeting both bacterial DNA gyrase and topoisomerase IV (Topo IV). In an abbreviated susceptibility screen, compounds 6o and 6v showed improved MIC90 values against Escherichia coli (0.5-1 μg/mL) and Acinetobacter baumannii (8-16 μg/mL) compared to the precursor compounds. In a murine septicemia model, both compounds showed complete protection in mice infected with a lethal dose of E. coli.
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Affiliation(s)
- Aleksey I Gerasyuto
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Michael A Arnold
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Jiashi Wang
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Guangming Chen
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Xiaoyan Zhang
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Sean Smith
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Matthew G Woll
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - John Baird
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Nanjing Zhang
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Neil G Almstead
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Jana Narasimhan
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Srinivasa Peddi
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Melissa Dumble
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Josephine Sheedy
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Marla Weetall
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Arthur A Branstrom
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - J V N Prasad
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
| | - Gary M Karp
- PTC Therapeutics, Inc. , 100 Corporate Court , South Plainfield , New Jersey 07080 , United States
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10
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Arnold MA, Gerasyuto AI, Wang J, Du W, Gorske YJK, Arasu T, Baird J, Almstead NG, Narasimhan J, Peddi S, Ginzburg O, Lue SW, Hedrick J, Sheedy J, Lagaud G, Branstrom AA, Weetall M, Prasad JVNV, Karp GM. 4-Hydroxy-2-pyridones: Discovery and evaluation of a novel class of antibacterial agents targeting DNA synthesis. Bioorg Med Chem Lett 2017; 27:5014-5021. [PMID: 29032026 DOI: 10.1016/j.bmcl.2017.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/27/2017] [Accepted: 10/04/2017] [Indexed: 01/01/2023]
Abstract
The continued emergence of bacteria resistant to current standard of care antibiotics presents a rapidly growing threat to public health. New chemical entities (NCEs) to treat these serious infections are desperately needed. Herein we report the discovery, synthesis, SAR and in vivo efficacy of a novel series of 4-hydroxy-2-pyridones exhibiting activity against Gram-negative pathogens. Compound 1c, derived from the N-debenzylation of 1b, preferentially inhibits bacterial DNA synthesis as determined by standard macromolecular synthesis assays. The structural features of the 4-hydroxy-2-pyridone scaffold required for antibacterial activity were explored and compound 6q, identified through further optimization of the series, had an MIC90 value of 8 μg/mL against a panel of highly resistant strains of E. coli. In a murine septicemia model, compound 6q exhibited a PD50 of 8 mg/kg in mice infected with a lethal dose of E. coli. This novel series of 4-hydroxy-2-pyridones serves as an excellent starting point for the identification of NCEs treating Gram-negative infections.
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Affiliation(s)
- Michael A Arnold
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA.
| | - Aleksey I Gerasyuto
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Jiashi Wang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Wu Du
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Yi Jin Kim Gorske
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Tamil Arasu
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - John Baird
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Neil G Almstead
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Jana Narasimhan
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Srinivasa Peddi
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Olya Ginzburg
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Stanley W Lue
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Jean Hedrick
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Josephine Sheedy
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Guy Lagaud
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Arthur A Branstrom
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Marla Weetall
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - J V N Vara Prasad
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Gary M Karp
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
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11
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Woll MG, Qi H, Turpoff A, Zhang N, Zhang X, Chen G, Li C, Huang S, Yang T, Moon YC, Lee CS, Choi S, Almstead NG, Naryshkin NA, Dakka A, Narasimhan J, Gabbeta V, Welch E, Zhao X, Risher N, Sheedy J, Weetall M, Karp GM. Discovery and Optimization of Small Molecule Splicing Modifiers of Survival Motor Neuron 2 as a Treatment for Spinal Muscular Atrophy. J Med Chem 2016; 59:6070-85. [DOI: 10.1021/acs.jmedchem.6b00460] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Matthew G. Woll
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Hongyan Qi
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Anthony Turpoff
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nanjing Zhang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Xiaoyan Zhang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Guangming Chen
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Chunshi Li
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Song Huang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Tianle Yang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Young-Choon Moon
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Chang-Sun Lee
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Soongyu Choi
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Neil G. Almstead
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nikolai A. Naryshkin
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Amal Dakka
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Jana Narasimhan
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Vijayalakshmi Gabbeta
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Ellen Welch
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Xin Zhao
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nicole Risher
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Josephine Sheedy
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Marla Weetall
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Gary M. Karp
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
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12
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Veselkov DA, Laponogov I, Pan XS, Selvarajah J, Skamrova GB, Branstrom A, Narasimhan J, Prasad JVNV, Fisher LM, Sanderson MR. Structure of a quinolone-stabilized cleavage complex of topoisomerase IV from Klebsiella pneumoniae and comparison with a related Streptococcus pneumoniae complex. Acta Crystallogr D Struct Biol 2016; 72:488-96. [PMID: 27050128 PMCID: PMC4822561 DOI: 10.1107/s2059798316001212] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/19/2016] [Indexed: 11/24/2022]
Abstract
Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. For K. pneumoniae, this is the first high-resolution cleavage complex structure to be reported. Klebsiella pneumoniae is a Gram-negative bacterium that is responsible for a range of common infections, including pulmonary pneumonia, bloodstream infections and meningitis. Certain strains of Klebsiella have become highly resistant to antibiotics. Despite the vast amount of research carried out on this class of bacteria, the molecular structure of its topoisomerase IV, a type II topoisomerase essential for catalysing chromosomal segregation, had remained unknown. In this paper, the structure of its DNA-cleavage complex is reported at 3.35 Å resolution. The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. This complex is compared with a similar complex from Streptococcus pneumoniae, which has recently been solved.
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Affiliation(s)
- Dennis A Veselkov
- Randall Division of Cell and Molecular Biophysics, King's College London, 3rd Floor, New Hunt's House, Guy's Campus, London SE1 1UL, England
| | - Ivan Laponogov
- Randall Division of Cell and Molecular Biophysics, King's College London, 3rd Floor, New Hunt's House, Guy's Campus, London SE1 1UL, England
| | - Xiao-Su Pan
- Cardiovascular and Cell Sciences Research Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, England
| | - Jogitha Selvarajah
- Cardiovascular and Cell Sciences Research Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, England
| | - Galyna B Skamrova
- Randall Division of Cell and Molecular Biophysics, King's College London, 3rd Floor, New Hunt's House, Guy's Campus, London SE1 1UL, England
| | - Arthur Branstrom
- PTC Therapeutics Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Jana Narasimhan
- PTC Therapeutics Inc., 100 Corporate Court, South Plainfield, NJ 07080, USA
| | | | - L Mark Fisher
- Cardiovascular and Cell Sciences Research Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, England
| | - Mark R Sanderson
- Randall Division of Cell and Molecular Biophysics, King's College London, 3rd Floor, New Hunt's House, Guy's Campus, London SE1 1UL, England
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13
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Zhao X, Feng Z, Ling KKY, Mollin A, Sheedy J, Yeh S, Petruska J, Narasimhan J, Dakka A, Welch EM, Karp G, Chen KS, Metzger F, Ratni H, Lotti F, Tisdale S, Naryshkin NA, Pellizzoni L, Paushkin S, Ko CP, Weetall M. Pharmacokinetics, pharmacodynamics, and efficacy of a small-molecule SMN2 splicing modifier in mouse models of spinal muscular atrophy. Hum Mol Genet 2016; 25:1885-1899. [PMID: 26931466 PMCID: PMC5062580 DOI: 10.1093/hmg/ddw062] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/22/2016] [Indexed: 12/26/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by the loss or mutation of both copies of the survival motor neuron 1 (SMN1) gene. The related SMN2 gene is retained, but due to alternative splicing of exon 7, produces insufficient levels of the SMN protein. Here, we systematically characterize the pharmacokinetic and pharmacodynamics properties of the SMN splicing modifier SMN-C1. SMN-C1 is a low-molecular weight compound that promotes the inclusion of exon 7 and increases production of SMN protein in human cells and in two transgenic mouse models of SMA. Furthermore, increases in SMN protein levels in peripheral blood mononuclear cells and skin correlate with those in the central nervous system (CNS), indicating that a change of these levels in blood or skin can be used as a non-invasive surrogate to monitor increases of SMN protein levels in the CNS. Consistent with restored SMN function, SMN-C1 treatment increases the levels of spliceosomal and U7 small-nuclear RNAs and corrects RNA processing defects induced by SMN deficiency in the spinal cord of SMNΔ7 SMA mice. A 100% or greater increase in SMN protein in the CNS of SMNΔ7 SMA mice robustly improves the phenotype. Importantly, a ∼50% increase in SMN leads to long-term survival, but the SMA phenotype is only partially corrected, indicating that certain SMA disease manifestations may respond to treatment at lower doses. Overall, we provide important insights for the translation of pre-clinical data to the clinic and further therapeutic development of this series of molecules for SMA treatment.
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Affiliation(s)
- Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Zhihua Feng
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Karen K Y Ling
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Anna Mollin
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | - Shirley Yeh
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | | | - Amal Dakka
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Ellen M Welch
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Gary Karp
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Karen S Chen
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Friedrich Metzger
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, Basel 4070, Switzerland
| | - Hasane Ratni
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, Basel 4070, Switzerland
| | - Francesco Lotti
- Department of Pathology and Cell Biology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA and
| | - Sarah Tisdale
- Department of Pathology and Cell Biology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA and
| | | | - Livio Pellizzoni
- Department of Pathology and Cell Biology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA and
| | - Sergey Paushkin
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Chien-Ping Ko
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA,
| | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA,
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14
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Naryshkin NA, Weetall M, Dakka A, Narasimhan J, Zhao X, Feng Z, Ling KKY, Karp GM, Qi H, Woll MG, Chen G, Zhang N, Gabbeta V, Vazirani P, Bhattacharyya A, Furia B, Risher N, Sheedy J, Kong R, Ma J, Turpoff A, Lee CS, Zhang X, Moon YC, Trifillis P, Welch EM, Colacino JM, Babiak J, Almstead NG, Peltz SW, Eng LA, Chen KS, Mull JL, Lynes MS, Rubin LL, Fontoura P, Santarelli L, Haehnke D, McCarthy KD, Schmucki R, Ebeling M, Sivaramakrishnan M, Ko CP, Paushkin SV, Ratni H, Gerlach I, Ghosh A, Metzger F. Motor neuron disease. SMN2 splicing modifiers improve motor function and longevity in mice with spinal muscular atrophy. Science 2014; 345:688-93. [PMID: 25104390 DOI: 10.1126/science.1250127] [Citation(s) in RCA: 346] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Spinal muscular atrophy (SMA) is a genetic disease caused by mutation or deletion of the survival of motor neuron 1 (SMN1) gene. A paralogous gene in humans, SMN2, produces low, insufficient levels of functional SMN protein due to alternative splicing that truncates the transcript. The decreased levels of SMN protein lead to progressive neuromuscular degeneration and high rates of mortality. Through chemical screening and optimization, we identified orally available small molecules that shift the balance of SMN2 splicing toward the production of full-length SMN2 messenger RNA with high selectivity. Administration of these compounds to Δ7 mice, a model of severe SMA, led to an increase in SMN protein levels, improvement of motor function, and protection of the neuromuscular circuit. These compounds also extended the life span of the mice. Selective SMN2 splicing modifiers may have therapeutic potential for patients with SMA.
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Affiliation(s)
| | - Marla Weetall
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Amal Dakka
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Jana Narasimhan
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Xin Zhao
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Zhihua Feng
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Karen K Y Ling
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Gary M Karp
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Hongyan Qi
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Matthew G Woll
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Guangming Chen
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Nanjing Zhang
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | | | - Priya Vazirani
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | | | - Bansri Furia
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Nicole Risher
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Josephine Sheedy
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Ronald Kong
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Jiyuan Ma
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Anthony Turpoff
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Chang-Sun Lee
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Xiaoyan Zhang
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Young-Choon Moon
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | | | - Ellen M Welch
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Joseph M Colacino
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - John Babiak
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Neil G Almstead
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Stuart W Peltz
- PTC Therapeutics, 100 Corporate Court, South Plainfield, NJ 07080, USA.
| | - Loren A Eng
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Karen S Chen
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Jesse L Mull
- Department of Stem Cell and Regenerative Biology and the Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Maureen S Lynes
- Department of Stem Cell and Regenerative Biology and the Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology and the Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Paulo Fontoura
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Luca Santarelli
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Daniel Haehnke
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | | | - Roland Schmucki
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Martin Ebeling
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Manaswini Sivaramakrishnan
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Chien-Ping Ko
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Sergey V Paushkin
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Hasane Ratni
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Irene Gerlach
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Anirvan Ghosh
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Friedrich Metzger
- Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Grenzacherstrasse 124, 4070 Basel, Switzerland.
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15
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Naryshkin N, Narasimhan J, Dakka A, Gabbeta V, Haley M, Crona J, Jung S, Vazirani P, Furia B, Qi H, Woll M, Yang T, Lee S, Choi S, Chen G, Zhang S, Zhang N, Huang S, Li C, Turpoff A, Hedrick J, Zhao X, Mollin A, Letinski S, Risher N, Paushkin S, Kobayashi D, McCarthy K, Pleiss M, Chen K, Almstead N, Colacino J, Babiak J, Peltz S, Karp G, Weetall M, Welch E. P3.12 Small molecule compounds that correct alternative splicing of the SMN2 gene and restore SMN protein expression and function. Neuromuscul Disord 2011. [DOI: 10.1016/j.nmd.2011.06.906] [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: 10/17/2022]
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16
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Zaborske JM, Narasimhan J, Jiang L, Wek SA, Dittmar KA, Freimoser F, Pan T, Wek RC. Genome-wide analysis of tRNA charging and activation of the eIF2 kinase Gcn2p. J Biol Chem 2009; 284:25254-67. [PMID: 19546227 DOI: 10.1074/jbc.m109.000877] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [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
When cells are subjected to nutritional stress, uncharged tRNAs accumulate and activate Gcn2p phosphorylation of eukaryotic initiation factor-2 (eIF2) and the general amino acid control pathway. The Gcn2p regulatory domain homologous to histidyl-tRNA synthetases is proposed to bind to uncharged tRNA, directly contributing to activation of Gcn2p. Here we apply a microarray technology to analyze genome-wide changes in tRNA charging in yeast upon activation of Gcn2p in response to amino acid starvation and high salinity, a stress not directly linked to nutritional deficiency. This microarray technology is applicable for all eukaryotic cells. Strains were starved for histidine, leucine, or tryptophan and shown to rapidly induce Gcn2p phosphorylation of eIF2. The relative charging level of all tRNAs was measured before and after starvation, and Gcn2p activation and the intracellular levels of the starved amino acid correlate with the observed decrease in tRNA charging. Interestingly, in some cases, tRNAs not charged with the starved amino acid became deacylated more rapidly than tRNAs charged with the starved amino acid. This increase in uncharged tRNA levels occurred although the intracellular levels for these non-starved amino acids remained unchanged. Additionally, treatment of a wild-type strain with high salinity stress showed transient changes in the charging of several different tRNAs. These results suggest that Gcn2p can be activated by many different tRNA species in the cell. These results also depict a complex cellular relationship between tRNA charging, amino acid availability, and non-nutrient stress. These relationships are best revealed by simultaneous monitoring of the charging level of all tRNAs.
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Affiliation(s)
- John M Zaborske
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA
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17
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Narasimhan J, Joyce BR, Naguleswaran A, Smith AT, Livingston MR, Dixon SE, Coppens I, Wek RC, Sullivan WJ. Translation regulation by eukaryotic initiation factor-2 kinases in the development of latent cysts in Toxoplasma gondii. J Biol Chem 2008; 283:16591-601. [PMID: 18420584 DOI: 10.1074/jbc.m800681200] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [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
A key problem in the treatment of numerous pathogenic eukaryotes centers on their development into latent forms during stress. For example, the opportunistic protist Toxoplasma gondii converts to latent cysts (bradyzoites) responsible for recrudescence of disease. We report that Toxoplasma eukaryotic initiation factor-2alpha (TgIF2alpha) is phosphorylated during stress and establish that protozoan parasites utilize translation control to modulate gene expression during development. Importantly, TgIF2alpha remains phosphorylated in bradyzoites, explaining how these cells maintain their quiescent state. Furthermore, we have characterized novel eIF2 kinases; one in the endoplasmic reticulum and a likely regulator of the unfolded protein response (TgIF2K-A) and another that is a probable responder to cytoplasmic stresses (TgIF2K-B). Significantly, our data suggest that 1) the regulation of protein translation through eIF2 kinases is associated with development, 2) eIF2alpha phosphorylation is employed by cells to maintain a latent state, and 3) endoplasmic reticulum and cytoplasmic stress responses evolved in eukaryotic cells before the early diverging Apicomplexa. Given its importance to pathogenesis, eIF2 kinase-mediated stress responses may provide opportunities for novel therapeutics.
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Affiliation(s)
- Jana Narasimhan
- Department of Pharmacology and Toxicology and Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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18
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Zhou D, Palam LR, Jiang L, Narasimhan J, Staschke KA, Wek RC. Phosphorylation of eIF2 Directs ATF5 Translational Control in Response to Diverse Stress Conditions. J Biol Chem 2008; 283:7064-73. [DOI: 10.1074/jbc.m708530200] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Dunand-Sauthier I, Walker CA, Narasimhan J, Pearce AK, Wek RC, Humphrey TC. Stress-activated protein kinase pathway functions to support protein synthesis and translational adaptation in response to environmental stress in fission yeast. Eukaryot Cell 2006; 4:1785-93. [PMID: 16278445 PMCID: PMC1287851 DOI: 10.1128/ec.4.11.1785-1793.2005] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The stress-activated protein kinase (SAPK) pathway plays a central role in coordinating gene expression in response to diverse environmental stress stimuli. We examined the role of this pathway in the translational response to stress in Schizosaccharomyces pombe. Exposing wild-type cells to osmotic stress (KCl) resulted in a rapid but transient reduction in protein synthesis. Protein synthesis was further reduced in mutants disrupting the SAPK pathway, including the mitogen-activated protein kinase Wis1 or the mitogen-activated protein kinase Spc1/Sty1, suggesting a role for these stress response factors in this translational control. Further polysome analyses revealed a role for Spc1 in supporting translation initiation during osmotic stress, and additionally in facilitating translational adaptation. Exposure to oxidative stress (H2O2) resulted in a striking reduction in translation initiation in wild-type cells, which was further reduced in spc1- cells. Reduced translation initiation correlated with phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2alpha) in wild-type cells. Disruption of Wis1 or Spc1 kinase or the downstream bZip transcription factors Atf1 and Pap1 resulted in a marked increase in eIF2alpha phosphorylation which was dependent on the eIF2alpha kinases Hri2 and Gcn2. These findings suggest a role for the SAPK pathway in supporting translation initiation and facilitating adaptation to environmental stress in part through reducing eIF2alpha phosphorylation in fission yeast.
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Affiliation(s)
- Isabelle Dunand-Sauthier
- MRC Radiation and Genome Stability Unit, Harwell, Didcot, United Kingdom, and Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, USA
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20
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Abstract
The biological effects of the ISG15 protein arise in part from its conjugation to cellular targets as a primary response to interferon-alpha/beta induction and other markers of viral or parasitic infection. Recombinant full-length ISG15 has been produced for the first time in high yield by mutating Cys78 to stabilize the protein and by cloning in a C-terminal arginine cap to protect the C terminus against proteolytic inactivation. The cap is subsequently removed with carboxypeptidase B to yield mature biologically active ISG15 capable of stoichiometric ATP-dependent thiolester formation with its human UbE1L activating enzyme. The three-dimensional structure of recombinant ISG15C78S was determined at 2.4-A resolution. The ISG15 structure comprises two beta-grasp folds having main chain root mean square deviation (r.m.s.d.) values from ubiquitin of 1.7 A (N-terminal) and 1.0 A (C-terminal). The beta-grasp domains pack across two conserved 3(10) helices to bury 627 A2 that accounts for 7% of the total solvent-accessible surface area. The distribution of ISG15 surface charge forms a ridge of negative charge extending nearly the full-length of the molecule. Additionally, the N-terminal domain contains an apolar region comprising almost half its solvent accessible surface. The C-terminal domain of ISG15 was superimposed on the structure of Nedd8 (r.m.s.d. = 0.84 A) bound to its AppBp1-Uba3 activating enzyme to model ISG15 binding to UbE1L. The docking model predicts several key side-chain interactions that presumably define the specificity between the ubiquitin and ISG15 ligation pathways to maintain functional integrity of their signaling.
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Affiliation(s)
- Jana Narasimhan
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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21
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Abstract
Phosphorylation of eukaryotic initiation factor-2 (eIF2) is an important mechanism mitigating cellular injury in response to diverse environmental stresses. While all eukaryotic organisms characterized to date contain an eIF2 kinase stress response pathway, the composition of eIF2 kinases differs, with mammals containing four distinct family members and the well-studied lower eukaryote Saccharomyces cerevisiae expressing only a single eIF2 kinase. We are interested in the mechanisms by which multiple eIF2 kinases interface with complex stress signals and elicit response pathways. In this report we find that in addition to two previously described eIF2 kinases related to mammalian HRI, designated Hri1p and Hri2p, the yeast Schizosaccharomyces pombe expresses a third eIF2 kinase, a Gcn2p ortholog. To delineate the roles of each eIF2 kinase, we constructed S. pombe strains expressing only a single eIF2 kinase gene or deleted for the entire eIF2 kinase family. We find that Hri2p is the primary activated eIF2 kinase in response to exposure to heat shock, arsenite, or cadmium. Gcn2p serves as the primary eIF2 kinase induced during a nutrient downshift, treatment with the amino acid biosynthetic inhibitor 3-aminotriazole, or upon exposure to high concentrations of sodium chloride. In one stress example, exposure to H(2)O(2), there is early tandem activation of both Hri2p and Gcn2p. Interestingly, with extended stress conditions there is activation of alternative secondary eIF2 kinases, suggesting that eukaryotes have mechanisms of coordinate activation of eIF2 kinase in their stress remediation responses. Deletion of these eIF2 kinases renders S. pombe more sensitive to many of these stress conditions.
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Affiliation(s)
- Ke Zhan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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22
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Sullivan WJ, Narasimhan J, Bhatti MM, Wek RC. Parasite-specific eIF2 (eukaryotic initiation factor-2) kinase required for stress-induced translation control. Biochem J 2004; 380:523-31. [PMID: 14989696 PMCID: PMC1224182 DOI: 10.1042/bj20040262] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [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: 02/17/2004] [Revised: 02/27/2004] [Accepted: 03/01/2004] [Indexed: 01/31/2023]
Abstract
The ubiquitous intracellular parasite Toxoplasma gondii (phylum Apicomplexa) differentiates into an encysted form (bradyzoite) that can repeatedly re-emerge as a life-threatening acute infection (tachyzoite) upon impairment of immunity. Since the switch from tachyzoite to bradyzoite is a stress-induced response, we sought to identify components related to the phosphorylation of the alpha subunit of eIF2 (eukaryotic initiation factor-2), a well-characterized event associated with stress remediation in other eukaryotic systems. In addition to characterizing Toxoplasma eIF2alpha (TgIF2alpha), we have discovered a novel eIF2 protein kinase, designated TgIF2K-A (Toxoplasma gondii initiation factor-2kinase). Although the catalytic domain of TgIF2K-A contains sequence and structural features that are conserved among members of the eIF2 kinase family, TgIF2K-A has an extended N-terminal region that is highly divergent from other eIF2 kinases. TgIF2K-A specifically phosphorylates the regulatory serine residue of yeast eIF2alpha in vitro and in vivo, and can modulate translation when expressed in the yeast model system. We also demonstrate that TgIF2K-A phosphorylates the analogous regulatory serine residue of recombinant TgIF2alpha in vitro. Finally, we demonstrate that TgIF2alpha phosphorylation in tachyzoites is enhanced in response to heat shock or alkaline stress, conditions known to induce parasite differentiation in vitro. Collectively, this study suggests that eIF2 kinase-mediated stress responses are conserved in Apicomplexa, and a novel family member exists that may control parasite-specific events, including the clinically relevant conversion into bradyzoite cysts.
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Affiliation(s)
- William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Medical Sciences Bldg, Indianapolis, IN 46202, USA.
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23
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Narasimhan J, Staschke KA, Wek RC. Dimerization Is Required for Activation of eIF2 Kinase Gcn2 in Response to Diverse Environmental Stress Conditions. J Biol Chem 2004; 279:22820-32. [PMID: 15010461 DOI: 10.1074/jbc.m402228200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [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: 11/06/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, starvation for amino acids induces phosphorylation of the alpha subunit of eukaryotic initiation factor 2alpha by Gcn2 protein kinase, leading to elevated translation of GCN4. Gcn4p is a transcriptional activator of hundreds of genes involved in remedying nutrient deprivation. In addition to a conserved kinase domain, Gcn2p has a regulatory region homologous to histidyl tRNA synthetase enzymes that binds uncharged tRNA that accumulates during amino acid starvation. Flanking the carboxyl terminus of the histidyl-tRNA synthetase-related domain is a region spanning 162 residues that participates in the activation of the protein kinase. Gel filtration and chemical cross-linking analysis of the recombinant carboxyl-terminal Gcn2 protein revealed that this region is a stable homodimer that is highly resistant to high concentrations of salt. Residue alterations in three hydrophobic segments and one segment with a proposed amphipathic alpha-helix in this Gcn2p carboxyl terminus blocked oligomerization, supporting the role of hydrophobic interactions in the dimerization interface of Gcn2p. Introduction of residue substitutions that impaired dimerization into the full-length protein prevented the ability of Gcn2p to phosphorylate its substrate eukaryotic initiation factor-2alpha and induce GCN4 translational expression in yeast cells subjected to a variety of stresses including amino acid limitation or exposure to rapamycin or high levels of NaCl. This latter stress can be overcome by addition of increasing amounts of K+ ions, indicating that the Na+/K+ ion balance is central to this stress induction. We conclude that dimerization involving hydrophobic segments in the carboxyl-terminal region is required for activation of Gcn2p in response to a multitude of stresses.
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Affiliation(s)
- Jana Narasimhan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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24
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Abstract
Induction of the 17-kDa ubiquitin-like protein ISG15/UCRP and its subsequent conjugation to cellular targets is the earliest response to type I interferons. The polypeptide is synthesized as a precursor containing a carboxyl-terminal extension whose correct processing is required for subsequent ligation of the exposed mature carboxyl terminus. Recombinant pro-ISG15 is processed in extracts of human lung fibroblasts by a constitutive 100-kDa enzyme whose activity is unaffected by type I interferon stimulation. The processing enzyme has been purified to apparent homogeneity by a combination of ion exchange and hydrophobic chromatography and found to be stimulated 12-fold by micromolar concentrations of ubiquitin. Analysis of the products of pro-ISG15 processing enzyme demonstrates specific cleavage exclusively at the Gly(157)-Gly(158) peptide bond to generate a mature ISG15 carboxyl terminus. Irreversible inhibition of pro-ISG15 processing activity by thiol-specific alkylating agents and a pH rate dependence conforming to titration of a single group of pK(a) 8.1 indicate the 100-kDa enzyme is a thiol protease. Partial sequencing of a trypsin-derived peptide indicates the enzyme is either the human ortholog of yeast Ubp1 or a Ubp1-related protein. As yeast do not contain ISG15, these results suggest that a ubiquitin-specific enzyme was recruited for pro-ISG15/UCRP processing by adaptive divergence.
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Affiliation(s)
- J L Potter
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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25
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O'Brien WJ, Narasimhan J, Guy J, Tom P, Taylor JL. The effects of interferon-alpha and acyclovir on herpes simplex virus type-1 ribonucleotide reductase. Antiviral Res 1998; 38:107-16. [PMID: 9707373 DOI: 10.1016/s0166-3542(98)00016-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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: 11/28/2022]
Abstract
Herpes simplex virus-type 1 (HSV-1) encodes both the small (UL40) and large (UL39) subunits of the enzyme, ribonucleotide reductase. Treatment of HSV-1-infected cells with interferon-alpha (IFN-alpha) reduced the levels of both enzyme subunits. Reduced steady state levels of the large subunit were demonstrated by immunoblot using polyclonal antibody specific for the viral enzyme. Reduction in the amount of small subunit was shown by a reduction in the electron spin resonance signal derived from the iron-containing tyrosyl free-radical present in this subunit. Treatment of cells with 100 IU/ml of IFN-alpha decreased levels of both subunits resulting in a reduction in enzyme activity as measured by conversion of CDP to dCDP. The decrease in the amount of the large subunit was not due to a reduction in the level of its mRNA. The combination of IFN-alpha and ACV treatment of human cornea stromal cells did not result in a further reduction in amounts of ribonucleotide reductase relative to that detected with IFN-alpha alone. The IFN-alpha-induced reduction in ribonucleotide reductase activity is the likely cause of decreased levels of dGTP which we have previously demonstrated in IFN-alpha-treated, infected cells.
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Affiliation(s)
- W J O'Brien
- Department of Microbiology, Medical College of Wisconsin, Milwaukee 53266, USA
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26
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Abstract
The biological effect of type 1 interferons is proposed to arise in part from the conjugation of ubiquitin cross-reactive protein (UCRP), the ISG15 gene product, to intracellular target proteins in a process analogous to that of its sequence homolog ubiquitin, a highly conserved 8.6-kDa polypeptide whose ligation marks proteins for degradation via the 26 S proteasome. Inclusion of CoCl2 during the purification of recombinant UCRP blocks the proteolytic inactivation of the polypeptide occurring by cleavage of the carboxyl-terminal glycine dipeptide required for activation and subsequent ligation. Intact UCRP supports a low rate of ubiquitin-activating enzyme (E1)-dependent ATP:PPi exchange but fails to form a stoichiometric E1-UCRP thiol ester or undergo transfer to ubiquitin carrier protein (E2). The binding affinity of E1 for UCRP is significantly diminished relative to that of ubiquitin. These results suggest that UCRP conjugation proceeds through an enzyme pathway distinct from that of ubiquitin, at least with respect to the step of activation. This was confirmed for an in vitro conjugation assay in which 125I-UCRP could be ligated in an ATP-dependent reaction to proteins present within an A549 human lung carcinoma cell extract and could be competitively inhibited by excess unlabeled UCRP but not ubiquitin. Other results demonstrate that 125I-UCRP conjugation is significantly increased in cell extracts after 24 h of incubation in the presence of interferon-beta, consistent with the late induction of UCRP conjugating activity. Thus, interferon-responsive cells contain a pathway for UCRP ligation that is parallel but distinct from that of ubiquitin.
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Affiliation(s)
- J Narasimhan
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226, USA
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27
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Abstract
Gallium, a pharmacologically important metal which resembles iron, was shown in previous studies to inhibit ribonucleotide reductase. To better understand its mechanism of action, we have examined the interaction of gallium with the iron-dependent M2 subunit of ribonucleotide reductase. In its active form, M2 contains an iron center and a tyrosyl free radical which is detectable by ESR spectroscopy. In the present study, cytoplasmic extracts prepared from murine leukemic L1210 cells after an 18-hr incubation with 960 microM gallium nitrate displayed a > 60% inhibition in their M2 tyrosyl radical ESR signal. However, this signal was restored within 15 min to levels greater than that of controls by the addition of increasing concentrations of ferrous ammonium sulfate. Gallium citrate added directly to cytoplasmic extracts from control cells also decreased the tyrosyl radical signal, an effect which could be reversed by iron. Immunoblot analysis revealed that incubation with gallium did not diminish the amount of M2 protein in cells, thus indicating that the decrease in the tyrosyl radical signal was not due to a decrease in cellular M2 content. In immunoprecipitation studies of 59Fe-labeled M2, gallium displaced 55-60% of the 59Fe incorporated into M2. Our studies suggest that gallium displaces iron from the M2 subunit of ribonucleotide reductase, resulting in a loss of the tyrosyl radical and an accumulation of inactive M2 within the cell.
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Affiliation(s)
- J Narasimhan
- Department of Medicine, Medical College of Wisconsin, Milwaukee 53226
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28
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Chitambar CR, Narasimhan J, Guy J, Sem DS, O'Brien WJ. Inhibition of ribonucleotide reductase by gallium in murine leukemic L1210 cells. Cancer Res 1991; 51:6199-201. [PMID: 1933878] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Our previous studies of the mechanism of cell growth inhibition by gallium have suggested that the block in cellular iron uptake induced by transferrin-gallium results in an inhibition of the iron-dependent M2 subunit of ribonucleotide reductase. However, it is not known whether the inhibitory effect of gallium on ribonucleotide reductase is solely the result of limiting iron availability for enzyme activity or whether a direct effect of intracellular gallium on the enzyme is also involved. In the present study, utilizing a cell-free assay, we show that gallium nitrate directly inhibits CDP and ADP reductase activity. Inhibition of DNA synthesis by gallium nitrate thus appears to be due to a combination of a block in iron availability to ribonucleotide reductase and a direct inhibition of the enzyme by gallium.
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Affiliation(s)
- C R Chitambar
- Department of Medicine, Medical College of Wisconsin, Milwaukee 53226
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29
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Narasimhan J, Antholine WE, Chitambar CR, Petering DH. Inhibition of iron uptake in HL60 cells by 2-formylpyridine monothiosemicarbazonato Cu(II). Arch Biochem Biophys 1991; 289:393-8. [PMID: 1654860 DOI: 10.1016/0003-9861(91)90429-m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [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: 12/28/2022]
Abstract
The electron paramagnetic resonance (EPR) signal of the tyrosyl radical attributed to ribonucleoside diphosphate reductase decreases after treatment of promyelocytic leukemic HL60 cells with 2-formylpyridine thiosemicarbazonato copper(II) (CuL). According to EPR studies, CuL forms adducts with both histidine and cysteine-like Lewis bases associated with isolated membranes from HL60 cells. After the addition of CuL, the EPR signal for the cysteine-like adduct decreases substantially over a 15-min period. The reduction of signal is consistent with oxidation of thiols as shown by an analysis of sulfhydryl content. It is hypothesized that receptor-mediated transferrin internalization is inhibited by oxidation of critical thiols. Since the uptake of 59Fe-transferrin is greatly inhibited by the treatment of HL60 cells with CuL, the reduced uptake of iron by cells, in the presence of CuL, may lead to decreased iron availability for the activity of the M2 subunit of ribonucleotide reductase and a subsequent decrease in the tyrosyl radical signal of the enzyme. Moreover, the intact subunit M2 is no longer detected by EPR, even after the addition of excess iron.
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Affiliation(s)
- J Narasimhan
- National Biomedical Electron Spin Resonance Center, Medical College of Wisconsin, Milwaukee 53226
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30
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Abstract
While iron is essential for numerous intracellular processes, its critical role in DNA synthesis relates to the activity of the iron-containing M2 subunit of ribonucleotide reductase, the enzyme responsible for the synthesis of deoxyribonucleotides. Gallium, a metal which resembles iron with respect to transferrin (Tf) binding, cellular uptake by the Tf receptor and incorporation into ferritin, blocks the cellular uptake of iron and inhibits cell growth. Exposure of HL60 cells to Tf-gallium (Ga) results in decreased deoxyribonucleotide synthesis and a diminution in the electron spin resonance (ESR) spectroscopy signal of ribonucleotide reductase, findings consistent with inhibition of this enzyme. In the present study, Ga nitrate blocked the uptake of 59Fe by L1210 cells and inhibited their proliferation. The ribonucleotide reductase M2 subunit ESR signal in cell cytoplasmic extracts was markedly inhibited in Ga-treated cells; however, the signal was restored to normal within 10 min of exposure of these cytoplasmic extracts to ferrous ammonium sulfate. These results confirm that Ga inhibits DNA synthesis by specifically limiting the amount of intracellular iron needed for the activity of the M2 subunit of ribonucleotide reductase. Further studies utilizing HL60 cells made resistant to Ga showed that these cells were also more resistant to growth inhibition by an anti-Tf receptor monoclonal antibody and deferoxamine. Ga blocks cell growth through inhibition of iron-dependent DNA synthesis. Cells appear to overcome the effects of Ga through compensatory mechanisms involving cellular iron metabolism.
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Affiliation(s)
- C R Chitambar
- Department of Medicine, Medical College of Wisconsin, Milwaukee
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Chitambar CR, Zivkovic-Gilgenbach Z, Narasimhan J, Antholine WE. Development of drug resistance to gallium nitrate through modulation of cellular iron uptake. Cancer Res 1990; 50:4468-72. [PMID: 2164439] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have shown that transferrin-gallium (Tf-Ga) blocks DNA synthesis through inhibition of cellular iron incorporation and a diminution in the activity of the iron-dependent M2 subunit of ribonucleotide reductase. To examine the mechanisms of drug resistance to gallium, we developed a subline of HL60 cells (R cells) which is 29-fold more resistant to growth inhibition by gallium nitrate than the parent line (S cells). R cells displayed a 2.5-fold increase in transferrin (Tf) receptor expression, without a change in receptor affinity for Tf. The uptake and release of 67Ga were similar for both S and R cells. The uptake of 59Fe-Tf by S cells was inhibited by gallium nitrate over 24-48 h of incubation. In contrast, 59Fe-Tf uptake by R cells, although initially inhibited by gallium nitrate at 24 h, was no longer inhibited at 48 h of incubation. 59FeCl3 uptake by R cells was significantly greater than that of S cells, regardless of the time in culture. Despite the increase in 59Fe uptake by R cells, the ferritin content of these cells was lower than that of S cells. The ribonucleotide reductase electron spin resonance signal of R cells was comparable to that of S cells. R cells were not cross-resistant to Adriamycin, vincristine, cis-platinum or hydroxyurea. Resistance to gallium nitrate in this subline of HL60 cells results primarily from the ability of cells to overcome the gallium-induced block in iron incorporation. In addition, intracellular iron in R cells appears to traffic preferentially to a non-ferritin compartment.
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Affiliation(s)
- C R Chitambar
- Department of Medicine, Medical College of Wisconsin, Milwaukee 53226
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