1
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Stewart TM, Foley JR, Holbert CE, Khomutov M, Rastkari N, Tao X, Khomutov AR, Zhai RG, Casero RA. Difluoromethylornithine rebalances aberrant polyamine ratios in Snyder-Robinson syndrome. EMBO Mol Med 2023; 15:e17833. [PMID: 37702369 PMCID: PMC10630878 DOI: 10.15252/emmm.202317833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/18/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023] Open
Abstract
Snyder-Robinson syndrome (SRS) results from mutations in spermine synthase (SMS), which converts the polyamine spermidine into spermine. Affecting primarily males, common manifestations of SRS include intellectual disability, osteoporosis, hypotonia, and seizures. Symptom management is the only treatment. Reduced SMS activity causes spermidine accumulation while spermine levels are reduced. The resulting exaggerated spermidine:spermine ratio is a biochemical hallmark of SRS that tends to correlate with symptom severity. Our studies aim to pharmacologically manipulate polyamine metabolism to correct this imbalance as a therapeutic strategy for SRS. Here we report the repurposing of 2-difluoromethylornithine (DFMO), an FDA-approved inhibitor of polyamine biosynthesis, in rebalancing spermidine:spermine ratios in SRS patient cells. Mechanistic in vitro studies demonstrate that, while reducing spermidine biosynthesis, DFMO also stimulates the conversion of spermidine into spermine in hypomorphic SMS cells and induces uptake of exogenous spermine, altogether reducing the aberrant ratios. In a Drosophila SRS model characterized by reduced lifespan, DFMO improves longevity. As nearly all SRS patient mutations are hypomorphic, these studies form a strong foundation for translational studies with significant therapeutic potential.
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Affiliation(s)
- Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Cassandra E Holbert
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Maxim Khomutov
- Engelhardt Institute of Molecular BiologyRussian Academy of SciencesMoscowRussia
| | - Noushin Rastkari
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
| | - Xianzun Tao
- Department of Molecular and Cellular PharmacologyUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Alex R Khomutov
- Engelhardt Institute of Molecular BiologyRussian Academy of SciencesMoscowRussia
| | - R Grace Zhai
- Department of Molecular and Cellular PharmacologyUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Robert A Casero
- Sidney Kimmel Comprehensive Cancer CenterJohns Hopkins School of MedicineBaltimoreMDUSA
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2
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Soda K. Changes in Whole Blood Polyamine Levels and Their Background in Age-Related Diseases and Healthy Longevity. Biomedicines 2023; 11:2827. [PMID: 37893199 PMCID: PMC10604715 DOI: 10.3390/biomedicines11102827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/13/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
The relationship between polyamines and healthy longevity has received much attention in recent years. However, conducting research without understanding the properties of polyamines can lead to unexpected pitfalls. The most fundamental consideration in conducting polyamine studies is that bovine serum used for cell culture contains bovine serum amine oxidase. Bovine serum amine oxidase, which is not inactivated by heat treatment, breaks down spermine and spermidine to produce the highly toxic aldehyde acrolein, which causes cell damage and activates autophagy. However, no such enzyme activity has been found in humans. Polyamine catabolism does not produce toxic aldehydes under normal conditions, but inflammation and some pathogens provoke an inducible enzyme, spermine oxidase, which only breaks down spermine to produce acrolein, resulting in cytotoxicity and the activation of autophagy. Therefore, spermine oxidase activation reduces spermine concentration and the ratio of spermine to spermidine, a feature recently reported in patients with age-related diseases. Spermine, which is increased by a long-term, continuous high polyamine diet, suppresses aberrant gene methylation and the pro-inflammatory status that progress with age and are strongly associated with the development of several age-related diseases and senescence. Changes in spermine concentration and the spermine/spermidine ratio should be considered as indicators of human health status.
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Affiliation(s)
- Kuniyasu Soda
- Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan;
- Saitama Ken-o Hospital, Saitama 363-0008, Japan
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3
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Stewart TRM, Foley JR, Holbert CE, Khomutov MA, Rastkari N, Tao X, Khomutov AR, Zhai RG, Casero RA. Difluoromethylornithine rebalances aberrant polyamine ratios in Snyder-Robinson syndrome: mechanism of action and therapeutic potential. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.30.534977. [PMID: 37034775 PMCID: PMC10081208 DOI: 10.1101/2023.03.30.534977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Snyder-Robinson Syndrome (SRS) is caused by mutations in the spermine synthase (SMS) gene, the enzyme product of which converts the polyamine spermidine into spermine. Affecting primarily males, common manifestations of SRS include intellectual disability, osteoporosis, hypotonic musculature, and seizures, along with other more variable symptoms. Currently, medical management focuses on treating these symptoms without addressing the underlying molecular cause of the disease. Reduced SMS catalytic activity in cells of SRS patients causes the accumulation of spermidine, while spermine levels are reduced. The resulting exaggeration in spermidine-to-spermine ratio is a biochemical hallmark of SRS that tends to correlate with symptom severity in the patient. Our studies aim to pharmacologically manipulate polyamine metabolism to correct this polyamine imbalance and investigate the potential of this approach as a therapeutic strategy for affected individuals. Here we report the use of difluoromethylornithine (DFMO; eflornithine), an FDA-approved inhibitor of polyamine biosynthesis, in re-establishing normal spermidine-to-spermine ratios in SRS patient cells. Through mechanistic studies, we demonstrate that, while reducing spermidine biosynthesis, DFMO also stimulates the conversion of existing spermidine into spermine in cell lines with hypomorphic variants of SMS. Further, DFMO treatment induces a compensatory uptake of exogenous polyamines, including spermine and spermine mimetics, cooperatively reducing spermidine and increasing spermine levels. In a Drosophila SRS model characterized by reduced lifespan, adding DFMO to the feed extended lifespan. As nearly all known SRS patient mutations are hypomorphic, these studies form a foundation for future translational studies with significant therapeutic potential.
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4
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Schultz CR, Sheldon RD, Xie H, Demireva EY, Uhl KL, Agnew DW, Geerts D, Bachmann AS. New K50R mutant mouse models reveal impaired hypusination of eif5a2 with alterations in cell metabolite landscape. Biol Open 2023; 12:290754. [PMID: 36848144 PMCID: PMC10084858 DOI: 10.1242/bio.059647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 02/21/2023] [Indexed: 03/01/2023] Open
Abstract
The eukaryotic translation initiation factor 5A1 (eIF5A1) and 5A2 (eIF5A2) are important proteins in a variety of physiological and pathophysiological processes and their function has been linked to neurodevelopmental disorders, cancer, and viral infections. Here, we report two new genome-edited mouse models, generated using a CRISPR-Cas9 approach, in which the amino acid residue lysine 50 is replaced with arginine 50 (K50R) in eIF5A1 or in the closely related eIF5A2 protein. This mutation prevents the spermidine-dependent post-translational formation of hypusine, a unique lysine derivative that is necessary for activation of eIF5A1 and eIF5A2. Mouse brain lysates from homozygous eif5a2-K50R mutant mice (eif5a2K50R/K50R) confirmed the absence of hypusine formation of eIF5A2, and metabolomic analysis of primary mouse dermal fibroblasts revealed significant alterations in the metabolite landscape compared to controls including increased levels of tryptophan, kyrunenine, pyridoxine, nicotinamide adenine dinucleotide, riboflavin, flavin adenine dinucleotide, pantothenate, and coenzyme A. Further supported by new publicly available bioinformatics data, these new mouse models represent excellent in vivo models to study hypusine-dependent biological processes, hypusination-related disorders caused by eIF5A1 and eIF5A2 gene aberrations or mRNA expression dysregulation, as well as several major human cancer types and potential therapies.
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Affiliation(s)
- Chad R Schultz
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Ryan D Sheldon
- Core Technologies and Services, Mass Spectrometry Core, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Huirong Xie
- Transgenic and Genome Editing Facility, Institute for Quantitative Health Science and Engineering, Research Technology Support Facility, Michigan State University, East Lansing, MI 48824, USA
| | - Elena Y Demireva
- Transgenic and Genome Editing Facility, Institute for Quantitative Health Science and Engineering, Research Technology Support Facility, Michigan State University, East Lansing, MI 48824, USA
| | - Katie L Uhl
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Dalen W Agnew
- Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Dirk Geerts
- Department of Hematology, Amsterdam University Medical Center, Location VUMC, 1081 HV Amsterdam, The Netherlands
| | - André S Bachmann
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
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5
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Wang L, Li S, Wang K, Wang N, Liu Q, Sun Z, Wang L, Wang L, Liu Q, Song C, Yang Q. Spermine enhances antiviral and anticancer responses by stabilizing DNA binding with the DNA sensor cGAS. Immunity 2023; 56:272-288.e7. [PMID: 36724787 DOI: 10.1016/j.immuni.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 10/25/2022] [Accepted: 01/04/2023] [Indexed: 02/03/2023]
Abstract
Self-nonself discrimination is vital for the immune system to mount responses against pathogens while maintaining tolerance toward the host and innocuous commensals during homeostasis. Here, we investigated how indiscriminate DNA sensors, such as cyclic GMP-AMP synthase (cGAS), make this self-nonself distinction. Screening of a small-molecule library revealed that spermine, a well-known DNA condenser associated with viral DNA, markedly elevates cGAS activation. Mechanistically, spermine condenses DNA to enhance and stabilize cGAS-DNA binding, optimizing cGAS and downstream antiviral signaling. Spermine promotes condensation of viral, but not host nucleosome, DNA. Deletion of viral DNA-associated spermine, by propagating virus in spermine-deficient cells, reduced cGAS activation. Spermine depletion subsequently attenuated cGAS-mediated antiviral and anticancer immunity. Collectively, our results reveal a pathogenic DNA-associated molecular pattern that facilitates nonself recognition, linking metabolism and pathogen recognition.
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Affiliation(s)
- Lina Wang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Siru Li
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Kai Wang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Na Wang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Qiaoling Liu
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Zhen Sun
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Li Wang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
| | - Lulu Wang
- School of Life Science and Biotechnology, Dalian University of Technology, No. 2 Linggong Road, Dalian, Liaoning 116024, China
| | - Quentin Liu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Guangzhou 510060, China
| | - Chengli Song
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China.
| | - Qingkai Yang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China.
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6
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Akinyele O, Munir A, Johnson MA, Perez MS, Gao Y, Foley JR, Wu Y, Murray-Stewart T, Casero RA, Bayir H, Kemaladewi DU. Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a novel mouse model of Snyder-Robinson Syndrome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.15.524155. [PMID: 36711956 PMCID: PMC9882240 DOI: 10.1101/2023.01.15.524155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Polyamines (putrescine, spermidine, and spermine) are essential molecules for normal cellular functions and are subject to strict metabolic regulation. Mutations in the gene encoding spermine synthase (SMS) lead to accumulation of spermidine in an X-linked recessive disorder known as Snyder-Robinson syndrome (SRS). Presently, no treatments exist for this rare disease that manifests with a spectrum of symptoms including intellectual disability, developmental delay, thin habitus, and low muscle tone. The development of therapeutic interventions for SRS will require a suitable disease-specific animal model that recapitulates many of the abnormalities observed in patients. Here, we characterize the molecular, behavioral, and neuroanatomical features of a mouse model with a missense mutation in Sms gene that results in a glycine-to-serine substitution at position 56 (G56S) of the SMS protein. Mice harboring this mutation exhibit a complete loss of SMS protein and elevated spermidine/spermine ratio in skeletal muscles and the brain. In addition, the G56S mice demonstrate increased anxiety, impaired learning, and decreased explorative behavior in fear conditioning, Morris water maze, and open field tests, respectively. Furthermore, these mice failed to gain weight over time and exhibit abnormalities in brain structure and bone density. Transcriptomic analysis of the cerebral cortex revealed downregulation of genes associated with mitochondrial oxidative phosphorylation and ribosomal protein synthesis. Our findings also revealed impaired mitochondrial bioenergetics in fibroblasts isolated from the G56S mice, indicating a correlation between these processes in the affected mice. Collectively, our findings establish the first in-depth characterization of an SRS preclinical mouse model that identifies cellular processes that could be targeted for future therapeutic development.
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Affiliation(s)
- Oluwaseun Akinyele
- Div. of Genetic and Genomic Medicine, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Anushe Munir
- Div. of Genetic and Genomic Medicine, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
- Dept. of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, USA
| | - Marie A. Johnson
- Div. of Genetic and Genomic Medicine, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Megan S. Perez
- Div. of Genetic and Genomic Medicine, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
- Dept. of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, USA
| | - Yuan Gao
- Children’s Neuroscience Institute, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Jackson R. Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Yijen Wu
- Dept. of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Tracy Murray-Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Robert A. Casero
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Hulya Bayir
- Children’s Neuroscience Institute, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Dwi U. Kemaladewi
- Div. of Genetic and Genomic Medicine, Dept. of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, USA
- Dept. of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, USA
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7
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Mouskou S, Katerelos A, Doulgeraki A, Leka-Emiri S, Manolakos E, Papoulidis I, Ververi A, Vartzelis G, Korona A, Mastroyanni S, Voudris K. Novel Hemizygous Missense Variant of Spermine Synthase ( SMS) Gene Causes Snyder-Robinson Syndrome in a Four-Year-Old Boy. Mol Syndromol 2021; 12:194-199. [PMID: 34177437 DOI: 10.1159/000514122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 12/29/2020] [Indexed: 11/19/2022] Open
Abstract
Snyder-Robinson syndrome (SRS) is an extremely rare X-linked intellectual disability syndrome (MRXSSR; MIM #309583). The main clinical features of SRS include psychomotor delay, hypotonia, and asthenic-type body habitus - reduced body weight and bone abnormalities (osteoporosis, fractures, kyphoscoliosis). We report a case of SRS with a hemizygous missense variant in the SMS gene,c.334C>G (p.Pro112Ala), in a 4-year-old boy, who initially developed hypotonia, delayed motor skills, and subsequently epilepsy. This variant in SMS was found to be de novo. To the best of our knowledge, this novel SMS gene variant has never been previously reported in disease-related variation databases, such as ClinVar or HGMD.
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Affiliation(s)
- Stella Mouskou
- Department of Neurology, 'P & A Kyriakou' Children's Hospital, Athens, Greece
| | | | - Artemis Doulgeraki
- Department of Bone and Mineral Metabolism, Institute of Child Health, Athens, Greece
| | - Sofia Leka-Emiri
- Department of Endocrinology-Growth and Development, 'P & A Kyriakou' Children's Hospital, Athens, Greece
| | | | | | - Athina Ververi
- Access To Genome, Clinical Laboratory Genetics, Athens, Greece
| | - Georgios Vartzelis
- Department of Neurology, 'P & A Kyriakou' Children's Hospital, Athens, Greece
| | - Anastasia Korona
- Department of Neurology, 'P & A Kyriakou' Children's Hospital, Athens, Greece
| | - Sotiria Mastroyanni
- Department of Neurology, 'P & A Kyriakou' Children's Hospital, Athens, Greece
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8
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Dontaine P, Kottos E, Dassonville M, Balasel O, Catros V, Soblet J, Perlot P, Vilain C. Digestive involvement in a severe form of Snyder-Robinson syndrome: Possible expansion of the phenotype. Eur J Med Genet 2020; 64:104097. [PMID: 33186760 DOI: 10.1016/j.ejmg.2020.104097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 10/23/2020] [Accepted: 11/04/2020] [Indexed: 11/30/2022]
Abstract
Snyder-Robinson syndrome (OMIM #309583) is a rare X-linked condition, caused by mutation in the SMS gene (MIM *300105), characterized by a wide spectrum of clinical signs including developmental delay, epilepsy, asthenic habitus, dysmorphism, osteopenia, and renal or genital anomalies. Here we describe two maternal half-brothers who both presented with severe neurodevelopmental delay, seizures, hearing loss, facial dysmorphism, renal and ophthalmologic anomalies, failure to thrive and premature death. A novel p.(Gly203Asp) variant was found at the hemizygous state in the two boys, and an elevated Spermidine/Spermine ratio confirmed the diagnosis of Snyder-Robinson syndrome. One of the brothers presented with gastrointestinal symptoms, with jejunal stenosis, enteral feeding intolerance, failure to thrive due to a dysfunctional gastrointestinal system, cholestasis and exocrine pancreatic insufficiency. Although more studies will be needed to understand its mechanisms, this observation lends further support to the possibility of severe digestive involvement in Snyder Robinson syndrome.
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Affiliation(s)
- Pauline Dontaine
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium
| | - Elisa Kottos
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium
| | - Martine Dassonville
- Department of Pediatric Surgery, Hôpital Universitaire des Enfants Reine Fabiola, Universite Libre de Bruxelles, Brussels, Belgium
| | - Ovidiu Balasel
- Department of Neonatalogy, Hôpital Universitaire des Enfants Reine Fabiola, Universite Libre de Bruxelles, Brussels, Belgium
| | - Véronique Catros
- Univ Rennes, Inserm, CHU Rennes, Institut NUMECAN (Nutrition Metabolisms and Cancer), CRB Santé Rennes, F-35000, Rennes, France
| | - Julie Soblet
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium
| | - Pascale Perlot
- Department of Pediatrics, Hôpital Universitaire des Enfants Reine Fabiola, Universite Libre de Bruxelles, Brussels, Belgium
| | - Catheline Vilain
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium; Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium.
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9
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Murray Stewart T, Khomutov M, Foley JR, Guo X, Holbert CE, Dunston TT, Schwartz CE, Gabrielson K, Khomutov A, Casero RA. ( R, R)-1,12-Dimethylspermine can mitigate abnormal spermidine accumulation in Snyder-Robinson syndrome. J Biol Chem 2020; 295:3247-3256. [PMID: 31996374 DOI: 10.1074/jbc.ra119.011572] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/21/2020] [Indexed: 11/06/2022] Open
Abstract
Snyder-Robinson syndrome (SRS) is an X-linked intellectual disability syndrome caused by a loss-of-function mutation in the spermine synthase (SMS) gene. Primarily affecting males, the main manifestations of SRS include osteoporosis, hypotonic stature, seizures, cognitive impairment, and developmental delay. Because there is no cure for SRS, treatment plans focus on alleviating symptoms rather than targeting the underlying causes. Biochemically, the cells of individuals with SRS accumulate excess spermidine, whereas spermine levels are reduced. We recently demonstrated that SRS patient-derived lymphoblastoid cells are capable of transporting exogenous spermine and its analogs into the cell and, in response, decreasing excess spermidine pools to normal levels. However, dietary supplementation of spermine does not appear to benefit SRS patients or mouse models. Here, we investigated the potential use of a metabolically stable spermine mimetic, (R,R)-1,12-dimethylspermine (Me2SPM), to reduce the intracellular spermidine pools of SRS patient-derived cells. Me2SPM can functionally substitute for the native polyamines in supporting cell growth while stimulating polyamine homeostatic control mechanisms. We found that both lymphoblasts and fibroblasts from SRS patients can accumulate Me2SPM, resulting in significantly decreased spermidine levels with no adverse effects on growth. Me2SPM administration to mice revealed that Me2SPM significantly decreases spermidine levels in multiple tissues. Importantly, Me2SPM was detectable in brain tissue, the organ most affected in SRS, and was associated with changes in polyamine metabolic enzymes. These findings indicate that the (R,R)-diastereomer of 1,12-Me2SPM represents a promising lead compound in developing a treatment aimed at targeting the molecular mechanisms underlying SRS pathology.
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Affiliation(s)
- Tracy Murray Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Maxim Khomutov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Xin Guo
- Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Cassandra E Holbert
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Tiffany T Dunston
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | | | - Kathleen Gabrielson
- Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Alexey Khomutov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Robert A Casero
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287.
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10
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Biochemical features of primary cells from a pediatric patient with a gain-of-function ODC1 genetic mutation. Biochem J 2019; 476:2047-2057. [PMID: 31249027 DOI: 10.1042/bcj20190294] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 06/17/2019] [Accepted: 06/27/2019] [Indexed: 12/24/2022]
Abstract
We recently described a new autosomal dominant genetic disorder in a pediatric patient caused by a heterozygous de novo mutation in the ornithine decarboxylase 1 (ODC1) gene. The new genetic disorder is characterized by global developmental delay, alopecia, overgrowth, and dysmorphic features. We hypothesized that this new mutation (c.1342 A>T) leads to a C-terminal truncation variant of the ODC protein that is resistant to normal proteasomal degradation, leading to putrescine accumulation in cells. ODC (E.C. 4.1.1.17) is a rate-limiting enzyme in the biosynthesis of polyamines (putrescine, spermidine, and spermine) that plays a crucial role during embryogenesis, organogenesis, and tumorigenesis. In this study, we show that primary dermal fibroblasts derived from a skin biopsy of a 3-year-old patient contain large amounts of ODC protein and putrescine compared with primary dermal (neonatal and adult) fibroblast control cells. Importantly, the accumulated ODC protein variant remained functionally active as we detected exceptionally high ODC enzyme activity in both primary dermal fibroblasts (12-17-fold of controls) and red blood cells (RBCs) (125-137-fold of controls), using a specific 14C radioactive ODC activity assay. Exposure of primary dermal fibroblasts to ODC inhibitor α-difluoromethylornithine (DFMO) reduced the ODC activity and putrescine to levels observed in controls without adversely affecting cell morphology or inducing cell death. In conclusion, our patient and potentially other patients that carry a similar ODC1 gain-of-function mutation might benefit from treatment with DFMO, a drug with a good safety profile, to suppress the exceptionally high ODC activity and putrescine levels in the body.
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