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Mohammadi MF, Tehrani Fateh S, Ganji M, Mohammadi P, Bahrami T, Ashrafi MR, Hosseinpour S, Heidari M, Garshasbi M, Tavasoli AR. Unraveling neuroimaging insights in developmental epileptic encephalopathy type 25: a comprehensive review of reported cases and a novel SLC13A5 variant. Acta Neurol Belg 2024:10.1007/s13760-024-02611-z. [PMID: 39147996 DOI: 10.1007/s13760-024-02611-z] [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: 11/27/2023] [Accepted: 07/13/2024] [Indexed: 08/17/2024]
Abstract
Developmental and epileptic encephalopathy type 25 with amelogenesis imperfecta (DEE25) is a rare autosomal recessive disorder caused by homozygous or compound heterozygous disease-causing variants in the SLC13A5. These variants can disrupt energy production and delay brain development, leading to DEE25. Key symptoms include refractory seizures, often manifesting in neonates or infants, alongside global developmental delay, intellectual disability, progressive microcephaly, ataxia, spasticity, and speech difficulties. Dental anomalies related to amelogenesis imperfecta are common. Previous studies have typically reported normal or minimally altered early-life brain magnetic resonance imaging (MRI) findings in DEE25. However, our investigation identified a homozygous splice donor variant (NM_177550.5: c.1437 + 1G >T) in SLC13A5 through whole-exome sequencing in two affected siblings (P1 and P2). They displayed developmental delay, cerebral hypotonia, speech delay, recurrent seizures, mild but constant microcephaly, and motor impairments. Significantly, P1 exhibited novel findings on brain magnetic resonance imaging at age 5, including previously unreported extensive persistent hypomyelination. Meanwhile, P2 showed substantial loss of cerebral white matter in the frontoparietal region and delayed myelination at 18 months old. These discoveries broaden the DEE25 imaging spectrum and highlight the clinical heterogeneity even within siblings sharing the same variants.
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Affiliation(s)
- Mohammad Farid Mohammadi
- Department of Cell and Molecular Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran
| | | | | | - Pouria Mohammadi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Myelin Disorders Clinic, Tehran University of Medical Sciences, Tehran, Iran
| | - Tayyeb Bahrami
- Liver and Digestive Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - Mahmoud Reza Ashrafi
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Myelin Disorders Clinic, Tehran University of Medical Sciences, Tehran, Iran
| | - Sareh Hosseinpour
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Myelin Disorders Clinic, Tehran University of Medical Sciences, Tehran, Iran
- Department of Pediatric Neurology, Vali-E-Asr Hospital, Tehran University of medical sciences, Tehran, Iran
| | - Morteza Heidari
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Myelin Disorders Clinic, Tehran University of Medical Sciences, Tehran, Iran
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
| | - Ali Reza Tavasoli
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Myelin Disorders Clinic, Tehran University of Medical Sciences, Tehran, Iran.
- Neurology Division, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA.
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Jaramillo-Martinez V, Sennoune SR, Tikhonova EB, Karamyshev AL, Ganapathy V, Urbatsch IL. Molecular phenotypes segregate missense mutations in SLC13A5 Epilepsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.23.594637. [PMID: 38826402 PMCID: PMC11142175 DOI: 10.1101/2024.05.23.594637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The sodium-coupled citrate transporter (NaCT, SLC13A5) mediates citrate uptake across the plasma membrane via an inward Na + gradient. Mutations in SLC13A5 cause early infantile epileptic encephalopathy type-25 (EIEE25, SLC13A5 Epilepsy) due to impaired citrate uptake in neurons. Despite clinical identification of disease-causing mutations, underlying mechanisms and cures remain elusive. We mechanistically classify the molecular phenotypes of six mutations. C50R, T142M, and T227M exhibit impaired citrate transport despite normal expression at the cell surface. G219R, S427L, and L488P are hampered by low protein expression, ER retention, and reduced transport. Mutants' mRNA levels resemble wildtype, suggesting post-translational defects. Class II mutations display immature core-glycosylation and shortened half-lives, indicating protein folding defects. These experiments provide a comprehensive understanding of the mutation's defects in SLC13A5 Epilepsy at the biochemical and molecular level and shed light into the trafficking pathway(s) of NaCT. The two classes of mutations will require fundamentally different treatment approaches to either restore transport function, or enable correction of protein folding defects. Summary Loss-of-function mutations in the SLC13A5 causes SLC13A5-Epilepsy, a devastating disease characterized by neonatal epilepsy. Currently no cure is available. We clarify the molecular-level defects to guide future developments for phenotype-specific treatment of disease-causing mutations.
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Alsemari A, Guzmán-Vega FJ, Meyer BF, Arold ST. Novel Homozygous Variants of SLC13A5 Expand the Functional Heterogeneity of a Homogeneous Syndrome of Early Infantile Epileptic Encephalopathy. Pediatr Neurol 2024; 151:68-72. [PMID: 38113697 DOI: 10.1016/j.pediatrneurol.2023.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/19/2023] [Accepted: 10/13/2023] [Indexed: 12/21/2023]
Abstract
BACKGROUND Early infantile epileptic encephalopathy 25 (EIEE25) is a distinct type of neonatal epileptic encephalopathy caused by autosomal recessive mutations in the SLC13A5 gene. SLC13A5 encodes a transmembrane sodium/citrate cotransporter required for regulating citrate entry into cells. METHODS Four families with recessively inherited epileptic encephalopathy were sequenced by clinically accredited laboratories using commercially available epilepsy gene panels. Patients were examined by a neurologist and were clinically diagnosed with infantile epileptic encephalopathy. RESULTS We present four families with global developmental delay, intellectual disability, and defective tooth development with four novel homozygous mutations in SLC13A5. The neurological examination showed spastic quadriplegia with increased deep tendon reflexes. Brain magnetic resonance imaging showed nonspecific signal abnormality of the bilateral hemispheric white matter. Despite similar clinical features, the conditions were based on different molecular mechanisms acting on SLC13A5 (abnormal splicing, large-scale deletions, and tandem-residue insertion). CONCLUSIONS Our results extend the landscape of autosomal recessive inherited homozygous mutations in SLC13A5 that cause a distinctive syndrome of severe neonatal epileptic encephalopathy. Our observations confirm the homogeneity of epileptic encephalopathy and dental abnormalities as a distinct clinical marker for EIEE25 despite the heterogeneous functional and mutational background.
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Affiliation(s)
- Abdulaziz Alsemari
- Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia; Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
| | - Francisco J Guzmán-Vega
- Saudi Human Genome Project, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia; Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Centre (CBRC), Thuwal, Saudi Arabia
| | - Stefan T Arold
- Saudi Human Genome Project, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
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Beltran AS. Novel Approaches to Studying SLC13A5 Disease. Metabolites 2024; 14:84. [PMID: 38392976 PMCID: PMC10890222 DOI: 10.3390/metabo14020084] [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: 11/18/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/25/2024] Open
Abstract
The role of the sodium citrate transporter (NaCT) SLC13A5 is multifaceted and context-dependent. While aberrant dysfunction leads to neonatal epilepsy, its therapeutic inhibition protects against metabolic disease. Notably, insights regarding the cellular and molecular mechanisms underlying these phenomena are limited due to the intricacy and complexity of the latent human physiology, which is poorly captured by existing animal models. This review explores innovative technologies aimed at bridging such a knowledge gap. First, I provide an overview of SLC13A5 variants in the context of human disease and the specific cell types where the expression of the transporter has been observed. Next, I discuss current technologies for generating patient-specific induced pluripotent stem cells (iPSCs) and their inherent advantages and limitations, followed by a summary of the methods for differentiating iPSCs into neurons, hepatocytes, and organoids. Finally, I explore the relevance of these cellular models as platforms for delving into the intricate molecular and cellular mechanisms underlying SLC13A5-related disorders.
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Affiliation(s)
- Adriana S Beltran
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
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5
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Brown TL, Bainbridge MN, Zahn G, Nye KL, Porter BE. The growing research toolbox for SLC13A5 citrate transporter disorder: a rare disease with animal models, cell lines, an ongoing Natural History Study and an engaged patient advocacy organization. THERAPEUTIC ADVANCES IN RARE DISEASE 2024; 5:26330040241263972. [PMID: 39091896 PMCID: PMC11292725 DOI: 10.1177/26330040241263972] [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] [Received: 01/02/2024] [Accepted: 06/06/2024] [Indexed: 08/04/2024]
Abstract
TESS Research Foundation (TESS) is a patient-led nonprofit organization seeking to understand the basic biology and clinical impact of pathogenic variants in the SLC13A5 gene. TESS aims to improve the fundamental understanding of citrate's role in the brain, and ultimately identify treatments and cures for the associated disease. TESS identifies, organizes, and develops collaboration between researchers, patients, clinicians, and the pharmaceutical industry to improve the lives of those suffering from SLC13A5 citrate transport disorder. TESS and its partners have developed multiple molecular tools, cellular and animal models, and taken the first steps toward drug discovery and development for this disease. However, much remains to be done to improve our understanding of the disorder associated with SLC13A5 variants and identify effective treatments for this devastating disease. Here, we describe the available SLC13A5 resources from the community of experts, to foundational tools, to in vivo and in vitro tools, and discuss unanswered research questions needed to move closer to a cure.
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Affiliation(s)
| | | | | | - Kim L. Nye
- TESS Research Foundation, Menlo Park, CA, USA
| | - Brenda E. Porter
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
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Ölmez TT, Moreno DF, Liu P, Johnson ZM, McGinnis MM, Tu BP, Hochstrasser M, Acar M. Sis2 regulates yeast replicative lifespan in a dose-dependent manner. Nat Commun 2023; 14:7719. [PMID: 38012152 PMCID: PMC10682402 DOI: 10.1038/s41467-023-43233-y] [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: 08/30/2022] [Accepted: 11/01/2023] [Indexed: 11/29/2023] Open
Abstract
Application of microfluidic platforms facilitated high-precision measurements of yeast replicative lifespan (RLS); however, comparative quantification of lifespan across strain libraries has been missing. Here we microfluidically measure the RLS of 307 yeast strains, each deleted for a single gene. Despite previous reports of extended lifespan in these strains, we found that 56% of them did not actually live longer than the wild-type; while the remaining 44% showed extended lifespans, the degree of extension was often different from what was previously reported. Deletion of SIS2 gene led to the largest RLS increase observed. Sis2 regulated yeast lifespan in a dose-dependent manner, implying a role for the coenzyme A biosynthesis pathway in lifespan regulation. Introduction of the human PPCDC gene in the sis2Δ background neutralized the lifespan extension. RNA-seq experiments revealed transcriptional increases in cell-cycle machinery components in sis2Δ background. High-precision lifespan measurement will be essential to elucidate the gene network governing lifespan.
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Affiliation(s)
- Tolga T Ölmez
- Department of Molecular Cellular and Developmental Biology, Yale University, 219 Prospect Street, New Haven, CT, 06511, USA
- Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT, 06516, USA
- Koç University Research Center for Translational Medicine, Koç University, Rumelifeneri Yolu, Sarıyer, İstanbul, 34450, Turkey
- Department of Basic Medical Sciences, Koc University Rumelifeneri Yolu, Sarıyer, İstanbul, 34450, Turkey
| | - David F Moreno
- Department of Molecular Cellular and Developmental Biology, Yale University, 219 Prospect Street, New Haven, CT, 06511, USA
- Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT, 06516, USA
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch-Graffenstaden, 67400, France
| | - Ping Liu
- Department of Molecular Cellular and Developmental Biology, Yale University, 219 Prospect Street, New Haven, CT, 06511, USA
- Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT, 06516, USA
| | - Zane M Johnson
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT, 06520, USA
| | - Madeline M McGinnis
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Benjamin P Tu
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Mark Hochstrasser
- Department of Molecular Cellular and Developmental Biology, Yale University, 219 Prospect Street, New Haven, CT, 06511, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT, 06520, USA
| | - Murat Acar
- Department of Molecular Cellular and Developmental Biology, Yale University, 219 Prospect Street, New Haven, CT, 06511, USA.
- Systems Biology Institute, Yale University, 850 West Campus Drive, West Haven, CT, 06516, USA.
- Department of Basic Medical Sciences, Koc University Rumelifeneri Yolu, Sarıyer, İstanbul, 34450, Turkey.
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Mapping the Metabolic Niche of Citrate Metabolism and SLC13A5. Metabolites 2023; 13:metabo13030331. [PMID: 36984771 PMCID: PMC10054676 DOI: 10.3390/metabo13030331] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/17/2023] [Accepted: 02/20/2023] [Indexed: 02/26/2023] Open
Abstract
The small molecule citrate is a key molecule that is synthesized de novo and involved in diverse biochemical pathways influencing cell metabolism and function. Citrate is highly abundant in the circulation, and cells take up extracellular citrate via the sodium-dependent plasma membrane transporter NaCT encoded by the SLC13A5 gene. Citrate is critical to maintaining metabolic homeostasis and impaired NaCT activity is implicated in metabolic disorders. Though citrate is one of the best known and most studied metabolites in humans, little is known about the consequences of altered citrate uptake and metabolism. Here, we review recent findings on SLC13A5, NaCT, and citrate metabolism and discuss the effects on metabolic homeostasis and SLC13A5-dependent phenotypes. We discuss the “multiple-hit theory” and how stress factors induce metabolic reprogramming that may synergize with impaired NaCT activity to alter cell fate and function. Furthermore, we underline how citrate metabolism and compartmentalization can be quantified by combining mass spectrometry and tracing approaches. We also discuss species-specific differences and potential therapeutic implications of SLC13A5 and NaCT. Understanding the synergistic impact of multiple stress factors on citrate metabolism may help to decipher the disease mechanisms associated with SLC13A5 citrate transport disorders.
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8
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Whitney R, Choi E, Jones KC. The neuroimaging spectrum of SLC13A5 related developmental and epileptic encephalopathy. Seizure 2023; 106:8-13. [PMID: 36701889 DOI: 10.1016/j.seizure.2023.01.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/14/2022] [Accepted: 01/18/2023] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND SLC13A5 related developmental and epileptic encephalopathy (DEE) is an autosomal recessive condition characterized by neonatal seizures, fever sensitivity, status epilepticus, developmental delay and tooth anomalies. The neuroimaging spectrum of SLC13A5 related DEE is not fully known. We present a case of SLC13A5 related DEE with distinct neuroimaging findings and review the neuroimaging findings of all published cases of SLC13A5 related DEE. METHODS A retrospective case review and focused review of the literature was completed. RESULTS A 16-month-old male with a clinical phenotype consistent with SLC13A5 related DEE and a previously reported pathogenic variant in SLC13A5, c.655G>A, p.Gly219Arg and a novel likely pathogenic variant in SLC13A5, c.202C>T, p.Pro68Ser was identified. MRI at day 5 of life revealed wide spread punctate white matter lesions (PWMLs) affecting the subcortical white matter, periventricular white matter, splenium of the corpus callosum, posterior limb of the internal capsule, corticospinal tracts, midbrain, pons and medulla, mimicking a metabolic/infectious etiology. MRI at one month showed atrophy and evolution of white matter necrosis. One hundred and five cases of SLC13A5 related DEE were identified. Initial MRI was completed in 62 cases (59%). MRI was normal in 41 cases (66%) and abnormal in 21 (34%). White matter abnormalities were most common (n=15, 71%); PWMLs occurred in 8 cases (38%). CONCLUSION Neuroimaging abnormalities may exist in a third of SLC13A5 related DEE cases. White matter abnormalities such as PWMLs appear most common. It remains unknown why some are susceptible to these lesions and how they affect long-term neurodevelopmental outcomes in SLC13A5 related DEE.
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Affiliation(s)
- Robyn Whitney
- Division of Neurology, Department of Paediatrics, McMaster University, 1200 Main Street West, Hamilton, ON, Canada.
| | - Elaine Choi
- Division of Neurology, Department of Paediatrics, McMaster University, 1200 Main Street West, Hamilton, ON, Canada
| | - Kevin C Jones
- Division of Neurology, Department of Paediatrics, McMaster University, 1200 Main Street West, Hamilton, ON, Canada
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9
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Spelbrink EM, Brown TL, Brimble E, Blanco KA, Nye KL, Porter BE. Characterizing a rare neurogenetic disease, SLC13A5 citrate transporter disorder, utilizing clinical data in a cloud-based medical record collection system. Front Genet 2023; 14:1109547. [PMID: 37025451 PMCID: PMC10072280 DOI: 10.3389/fgene.2023.1109547] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 02/22/2023] [Indexed: 04/08/2023] Open
Abstract
Introduction: SLC13A5 citrate transporter disorder is a rare autosomal recessive genetic disease that has a constellation of neurologic symptoms. To better characterize the neurologic and clinical laboratory phenotype, we utilized patient medical records collected by Ciitizen, an Invitae company, with support from the TESS Research Foundation. Methods: Medical records for 15 patients with a suspected genetic and clinical diagnosis of SLC13A5 citrate transporter disorder were collected by Ciitizen, an Invitae company. Genotype, clinical phenotypes, and laboratory data were extracted and analyzed. Results: The 15 patients reported all had epilepsy and global developmental delay. Patients continued to attain motor milestones, though much later than their typically developing peers. Clinical diagnoses support abnormalities in communication, and low or mixed tone with several movement disorders, including, ataxia and dystonia. Serum citrate was elevated in the 3 patients in whom it was measured; other routine laboratory studies assessing renal, liver and blood function had normal values or no consistent abnormalities. Many electroencephalograms (EEGs) were performed (1 to 35 per patient), and most but not all were abnormal, with slowing and/or epileptiform activity. Fourteen of the patients had one or more brain magnetic resonance imaging (MRI) reports: 7 patients had at least one normal brain MRI, but not with any consistent findings except white matter signal changes. Discussion: These results show that in addition to the epilepsy phenotype, SLC13A5 citrate transporter disorder impacts global development, with marked abnormalities in motor abilities, tone, coordination, and communication skills. Further, utilizing cloud-based medical records allows industry, academic, and patient advocacy group collaboration to provide preliminary characterization of a rare genetic disorder. Additional characterization of the neurologic phenotype will be critical to future study and developing treatment for this and related rare genetic disorders.
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Affiliation(s)
- Emily M. Spelbrink
- Stanford University School of Medicine, Department of Neurology and Neurological Sciences, Palo Alto, CA, United States
| | - Tanya L. Brown
- Treatments for Epilepsy and Symptoms of SLC13A5 Foundation, TESS Research Foundation, Menlo Park, CA, United States
| | | | - Kirsten A. Blanco
- Invitae, San Francisco, CA, United States
- Department of Genetics, Stanford University, Stanford, CA, United States
| | - Kimberly L. Nye
- Treatments for Epilepsy and Symptoms of SLC13A5 Foundation, TESS Research Foundation, Menlo Park, CA, United States
| | - Brenda E. Porter
- Stanford University School of Medicine, Department of Neurology and Neurological Sciences, Palo Alto, CA, United States
- *Correspondence: Brenda E. Porter,
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Akhtar MJ, Khan SA, Kumar B, Chawla P, Bhatia R, Singh K. Role of sodium dependent SLC13 transporter inhibitors in various metabolic disorders. Mol Cell Biochem 2022:10.1007/s11010-022-04618-7. [DOI: 10.1007/s11010-022-04618-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 11/23/2022] [Indexed: 12/14/2022]
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Gan Y, Wei Z, Liu C, Li G, Feng Y, Deng Y. Solute carrier transporter disease and developmental and epileptic encephalopathy. Front Neurol 2022; 13:1013903. [PMID: 36419532 PMCID: PMC9676364 DOI: 10.3389/fneur.2022.1013903] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 09/07/2022] [Indexed: 09/14/2023] Open
Abstract
The International League Against Epilepsy officially revised its classification in 2017, which amended "epileptic encephalopathy" to "developmental and epileptic encephalopathy". With the development of genetic testing technology, an increasing number of genes that cause developmental and epileptic encephalopathies are being identified. Among these, solute transporter dysfunction is part of the etiology of developmental and epileptic encephalopathies. Solute carrier transporters play an essential physiological function in the human body, and their dysfunction is associated with various human diseases. Therefore, in-depth studies of developmental and epileptic encephalopathies caused by solute carrier transporter dysfunction can help develop new therapeutic modalities to facilitate the treatment of refractory epilepsy and improve patient prognosis. In this article, the concept of transporter protein disorders is first proposed, and nine developmental and epileptic encephalopathies caused by solute carrier transporter dysfunction are described in detail in terms of pathogenesis, clinical manifestations, ancillary tests, and precise treatment to provide ideas for the precise treatment of epilepsy.
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Affiliation(s)
- Yajing Gan
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Zihan Wei
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Chao Liu
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Guoyan Li
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yan Feng
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yanchun Deng
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an, China
- Xijing Institute of Epilepsy and Encephalopathy, Xi'an, China
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12
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Goodspeed K, Liu JS, Nye KL, Prasad S, Sadhu C, Tavakkoli F, Bilder DA, Minassian BA, Bailey RM. SLC13A5 Deficiency Disorder: From Genetics to Gene Therapy. Genes (Basel) 2022; 13:1655. [PMID: 36140822 PMCID: PMC9498415 DOI: 10.3390/genes13091655] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Epileptic encephalopathies may arise from single gene variants. In recent years, next-generation sequencing technologies have enabled an explosion of gene identification in monogenic epilepsies. One such example is the epileptic encephalopathy SLC13A5 deficiency disorder, which is caused by loss of function pathogenic variants to the gene SLC13A5 that results in deficiency of the sodium/citrate cotransporter. Patients typically experience seizure onset within the first week of life and have developmental delay and intellectual disability. Current antiseizure medications may reduce seizure frequency, yet more targeted treatments are needed to address the epileptic and non-epileptic features of SLC13A5 deficiency disorder. Gene therapy may offer hope to these patients and better clinical outcomes than current available treatments. Here, we discuss SLC13A5 genetics, natural history, available treatments, potential outcomes and assessments, and considerations for translational medical research for an AAV9-based gene replacement therapy.
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Affiliation(s)
- Kimberly Goodspeed
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Judy S. Liu
- Warren Alpert School of Medicine, Brown University, Providence, RI 02903, USA
| | | | - Suyash Prasad
- Department of Research & Development, Taysha Gene Therapies, Dallas, TX 75247, USA
| | - Chanchal Sadhu
- Department of Research & Development, Taysha Gene Therapies, Dallas, TX 75247, USA
| | - Fatemeh Tavakkoli
- Department of Research & Development, Taysha Gene Therapies, Dallas, TX 75247, USA
| | - Deborah A. Bilder
- Division of Child & Adolescent Psychiatry, Department of Psychiatry, University of Utah, Salt Lake City, UT 84108, USA
| | - Berge A. Minassian
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Rachel M. Bailey
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX 75390, USA
- Center for Alzheimer’s and Neurodegenerative Diseases, University of Texas Southwestern, Dallas, TX 75390, USA
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13
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Metabolic and Cellular Compartments of Acetyl-CoA in the Healthy and Diseased Brain. Int J Mol Sci 2022; 23:ijms231710073. [PMID: 36077475 PMCID: PMC9456256 DOI: 10.3390/ijms231710073] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/29/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
The human brain is characterised by the most diverse morphological, metabolic and functional structure among all body tissues. This is due to the existence of diverse neurons secreting various neurotransmitters and mutually modulating their own activity through thousands of pre- and postsynaptic interconnections in each neuron. Astroglial, microglial and oligodendroglial cells and neurons reciprocally regulate the metabolism of key energy substrates, thereby exerting several neuroprotective, neurotoxic and regulatory effects on neuronal viability and neurotransmitter functions. Maintenance of the pool of mitochondrial acetyl-CoA derived from glycolytic glucose metabolism is a key factor for neuronal survival. Thus, acetyl-CoA is regarded as a direct energy precursor through the TCA cycle and respiratory chain, thereby affecting brain cell viability. It is also used for hundreds of acetylation reactions, including N-acetyl aspartate synthesis in neuronal mitochondria, acetylcholine synthesis in cholinergic neurons, as well as divergent acetylations of several proteins, peptides, histones and low-molecular-weight species in all cellular compartments. Therefore, acetyl-CoA should be considered as the central point of metabolism maintaining equilibrium between anabolic and catabolic pathways in the brain. This review presents data supporting this thesis.
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14
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Mishra D, Kannan K, Meadows K, Macro J, Li M, Frankel S, Rogina B. INDY-From Flies to Worms, Mice, Rats, Non-Human Primates, and Humans. FRONTIERS IN AGING 2022; 2:782162. [PMID: 35822025 PMCID: PMC9261455 DOI: 10.3389/fragi.2021.782162] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/24/2021] [Indexed: 01/17/2023]
Abstract
I’m Not Dead Yet (Indy) is a fly homologue of the mammalian SLC13A5 (mSLC13A5) plasma membrane citrate transporter, a key metabolic regulator and energy sensor involved in health, longevity, and disease. Reduction of Indy gene activity in flies, and its homologs in worms, modulates metabolism and extends longevity. The metabolic changes are similar to what is obtained with caloric restriction (dietary restriction). Similar effects on metabolism have been observed in mice and rats. As a citrate transporter, INDY regulates cytoplasmic citrate levels. Indy flies heterozygous for a P-element insertion have increased spontaneous physical activity, increased fecundity, reduced insulin signaling, increased mitochondrial biogenesis, preserved intestinal stem cell homeostasis, lower lipid levels, and increased stress resistance. Mammalian Indy knockout (mIndy-KO) mice have higher sensitivity to insulin signaling, lower blood pressure and heart rate, preserved memory and are protected from the negative effects of a high-fat diet and some of the negative effects of aging. Reducing mIndy expression in human hepatocarcinoma cells has recently been shown to inhibit cell proliferation. Reduced Indy expression in the fly intestine affects intestinal stem cell proliferation, and has recently been shown to also inhibit germ cell proliferation in males with delayed sperm maturation and decreased spermatocyte numbers. These results highlight a new connection between energy metabolism and cell proliferation. The overrall picture in a variety of species points to a conserved role of INDY for metabolism and health. This is illustrated by an association of high mIndy gene expression with non-alcoholic fatty liver disease in obese humans. mIndy (mSLC13A5) coding region mutations (e.g., loss-of-function) are also associated with adverse effects in humans, such as autosomal recessive early infantile epileptic encephalopathy and Kohlschütter−Tönz syndrome. The recent findings illustrate the importance of mIndy gene for human health and disease. Furthermore, recent work on small-molecule regulators of INDY highlights the promise of INDY-based treatments for ameliorating disease and promoting healthy aging.
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Affiliation(s)
- Dushyant Mishra
- Department of Genetics and Genome Sciences, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States
| | - Kavitha Kannan
- Department of Genetics and Genome Sciences, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States
| | - Kali Meadows
- Department of Genetics and Genome Sciences, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States
| | - Jacob Macro
- Department of Genetics and Genome Sciences, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States
| | - Michael Li
- Department of Genetics and Genome Sciences, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States
| | - Stewart Frankel
- Department of Biology, University of Hartford, West Hartford, CT, United States
| | - Blanka Rogina
- Department of Genetics and Genome Sciences, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States.,Institute for Systems Genomics, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States
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15
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Goodspeed K, Bailey RM, Prasad S, Sadhu C, Cardenas JA, Holmay M, Bilder DA, Minassian BA. Gene Therapy: Novel Approaches to Targeting Monogenic Epilepsies. Front Neurol 2022; 13:805007. [PMID: 35847198 PMCID: PMC9284605 DOI: 10.3389/fneur.2022.805007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 04/20/2022] [Indexed: 11/18/2022] Open
Abstract
Genetic epilepsies are a spectrum of disorders characterized by spontaneous and recurrent seizures that can arise from an array of inherited or de novo genetic variants and disrupt normal brain development or neuronal connectivity and function. Genetically determined epilepsies, many of which are due to monogenic pathogenic variants, can result in early mortality and may present in isolation or be accompanied by neurodevelopmental disability. Despite the availability of more than 20 antiseizure medications, many patients with epilepsy fail to achieve seizure control with current therapies. Patients with refractory epilepsy—particularly of childhood onset—experience increased risk for severe disability and premature death. Further, available medications inadequately address the comorbid developmental disability. The advent of next-generation gene sequencing has uncovered genetic etiologies and revolutionized diagnostic practices for many epilepsies. Advances in the field of gene therapy also present the opportunity to address the underlying mechanism of monogenic epilepsies, many of which have only recently been described due to advances in precision medicine and biology. To bring precision medicine and genetic therapies closer to clinical applications, experimental animal models are needed that replicate human disease and reflect the complexities of these disorders. Additionally, identifying and characterizing clinical phenotypes, natural disease course, and meaningful outcome measures from epileptic and neurodevelopmental perspectives are necessary to evaluate therapies in clinical studies. Here, we discuss the range of genetically determined epilepsies, the existing challenges to effective clinical management, and the potential role gene therapy may play in transforming treatment options available for these conditions.
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Affiliation(s)
- Kimberly Goodspeed
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, United States
| | - Rachel M. Bailey
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, United States
- Center for Alzheimer's and Neurodegenerative Diseases, University of Texas Southwestern, Dallas, TX, United States
| | - Suyash Prasad
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Chanchal Sadhu
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Jessica A. Cardenas
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Mary Holmay
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Deborah A. Bilder
- Division of Child and Adolescent Psychiatry, Department of Psychiatry, Huntsman Mental Health Institute, University of Utah, Salt Lake City, UT, United States
| | - Berge A. Minassian
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, United States
- *Correspondence: Berge A. Minassian
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16
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Sauer DB, Marden JJ, Sudar JC, Song J, Mulligan C, Wang DN. Structural basis of ion - substrate coupling in the Na +-dependent dicarboxylate transporter VcINDY. Nat Commun 2022; 13:2644. [PMID: 35551191 PMCID: PMC9098524 DOI: 10.1038/s41467-022-30406-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/28/2022] [Indexed: 11/21/2022] Open
Abstract
The Na+-dependent dicarboxylate transporter from Vibrio cholerae (VcINDY) is a prototype for the divalent anion sodium symporter (DASS) family. While the utilization of an electrochemical Na+ gradient to power substrate transport is well established for VcINDY, the structural basis of this coupling between sodium and substrate binding is not currently understood. Here, using a combination of cryo-EM structure determination, succinate binding and site-directed cysteine alkylation assays, we demonstrate that the VcINDY protein couples sodium- and substrate-binding via a previously unseen cooperative mechanism by conformational selection. In the absence of sodium, substrate binding is abolished, with the succinate binding regions exhibiting increased flexibility, including HPinb, TM10b and the substrate clamshell motifs. Upon sodium binding, these regions become structurally ordered and create a proper binding site for the substrate. Taken together, these results provide strong evidence that VcINDY's conformational selection mechanism is a result of the sodium-dependent formation of the substrate binding site.
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Affiliation(s)
- David B Sauer
- Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Jennifer J Marden
- Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Joseph C Sudar
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Jinmei Song
- Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | | | - Da-Neng Wang
- Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA.
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA.
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17
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Milosavljevic S, Glinton KE, Li X, Medeiros C, Gillespie P, Seavitt JR, Graham BH, Elsea SH. Untargeted Metabolomics of Slc13a5 Deficiency Reveal Critical Liver-Brain Axis for Lipid Homeostasis. Metabolites 2022; 12:metabo12040351. [PMID: 35448538 PMCID: PMC9032242 DOI: 10.3390/metabo12040351] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/29/2022] [Accepted: 04/03/2022] [Indexed: 01/17/2023] Open
Abstract
Though biallelic variants in SLC13A5 are known to cause severe encephalopathy, the mechanism of this disease is poorly understood. SLC13A5 protein deficiency reduces citrate transport into the cell. Downstream abnormalities in fatty acid synthesis and energy generation have been described, though biochemical signs of these perturbations are inconsistent across SLC13A5 deficiency patients. To investigate SLC13A5-related disorders, we performed untargeted metabolic analyses on the liver, brain, and serum from a Slc13a5-deficient mouse model. Metabolomic data were analyzed using the connect-the-dots (CTD) methodology and were compared to plasma and CSF metabolomics from SLC13A5-deficient patients. Mice homozygous for the Slc13a5tm1b/tm1b null allele had perturbations in fatty acids, bile acids, and energy metabolites in all tissues examined. Further analyses demonstrated that for several of these molecules, the ratio of their relative tissue concentrations differed widely in the knockout mouse, suggesting that deficiency of Slc13a5 impacts the biosynthesis and flux of metabolites between tissues. Similar findings were observed in patient biofluids, indicating altered transport and/or flux of molecules involved in energy, fatty acid, nucleotide, and bile acid metabolism. Deficiency of SLC13A5 likely causes a broader state of metabolic dysregulation than previously recognized, particularly regarding lipid synthesis, storage, and metabolism, supporting SLC13A5 deficiency as a lipid disorder.
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Affiliation(s)
- Sofia Milosavljevic
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
- Harvard Medical School, Boston, MA 02215, USA
| | - Kevin E. Glinton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
| | - Xiqi Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
| | - Cláudia Medeiros
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (C.M.); (P.G.); (B.H.G.)
| | - Patrick Gillespie
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (C.M.); (P.G.); (B.H.G.)
| | - John R. Seavitt
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
| | - Brett H. Graham
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (C.M.); (P.G.); (B.H.G.)
| | - Sarah H. Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
- Correspondence: ; Tel.: +1-713-798-5484
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18
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Surrer DB, Fromm MF, Maas R, König J. L-Arginine and Cardioactive Arginine Derivatives as Substrates and Inhibitors of Human and Mouse NaCT/Nact. Metabolites 2022; 12:metabo12040273. [PMID: 35448460 PMCID: PMC9026504 DOI: 10.3390/metabo12040273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/17/2022] [Accepted: 03/19/2022] [Indexed: 01/25/2023] Open
Abstract
The uptake transporter NaCT (gene symbol SLC13A5) is expressed in liver and brain and important for energy metabolism and brain development. Substrates include tricarboxylic acid cycle intermediates, e.g., citrate and succinate. To gain insights into the substrate spectrum of NaCT, we tested whether arginine and the cardioactive L-arginine metabolites asymmetric dimethylarginine (ADMA) and L-homoarginine are also transported by human and mouse NaCT/Nact. Using HEK293 cells overexpressing human or mouse NaCT/Nact we characterized these substances as substrates. Furthermore, inhibition studies were performed using the arginine derivative symmetric dimethylarginine (SDMA), the NaCT transport inhibitor BI01383298, and the prototypic substrate citrate. Arginine and the derivatives ADMA and L-homoarginine were identified as substrates of human and mouse NaCT. Transport of arginine and derivatives mediated by human and mouse NaCT were dose-dependently inhibited by SDMA. Whereas BI01383298 inhibited only human NaCT-mediated citrate uptake, it inhibits the uptake of arginine and derivatives mediated by both human NaCT and mouse Nact. In contrast, the prototypic substrate citrate inhibited the transport of arginine and derivatives mediated only by human NaCT. These results demonstrate a so far unknown link between NaCT/Nact and L-arginine and its cardiovascular important derivatives.
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Affiliation(s)
| | | | | | - Jörg König
- Correspondence: ; Tel.: +49-9131-8522077
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19
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Sauer DB, Wang B, Sudar JC, Song J, Marden J, Rice WJ, Wang DN. The ups and downs of elevator-type di-/tricarboxylate membrane transporters. FEBS J 2022; 289:1515-1523. [PMID: 34403567 PMCID: PMC9832446 DOI: 10.1111/febs.16158] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/27/2021] [Accepted: 08/16/2021] [Indexed: 01/13/2023]
Abstract
The divalent anion sodium symporter (DASS) family contains both sodium-driven anion cotransporters and anion/anion exchangers. The family belongs to a broader ion transporter superfamily (ITS), which comprises 24 families of transporters, including those of AbgT antibiotic efflux transporters. The human proteins in the DASS family play major physiological roles and are drug targets. We recently determined multiple structures of the human sodium-dependent citrate transporter (NaCT) and the succinate/dicarboxylate transporter from Lactobacillus acidophilus (LaINDY). Structures of both proteins show high degrees of structural similarity to the previously determined VcINDY fold. Conservation between these DASS protein structures and those from the AbgT family indicates that the VcINDY fold represents the overall protein structure for the entire ITS. The new structures of NaCT and LaINDY are captured in the inward- or outward-facing conformations, respectively. The domain arrangements in these structures agree with a rigid body elevator-type transport mechanism for substrate translocation across the membrane. Two separate NaCT structures in complex with a substrate or an inhibitor allowed us to explain the inhibition mechanism and propose a detailed classification scheme for grouping disease-causing mutations in the human protein. Structural understanding of multiple kinetic states of DASS proteins is a first step toward the detailed characterization of their entire transport cycle.
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Affiliation(s)
- David B. Sauer
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Bing Wang
- Cryo-Electron Microscopy Core, New York University School of Medicine, New York, NY 10016, USA
| | - Joseph C. Sudar
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Jinmei Song
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Jennifer Marden
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - William J. Rice
- Cryo-Electron Microscopy Core, New York University School of Medicine, New York, NY 10016, USA
| | - Da-Neng Wang
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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20
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AlQudairy H, AlDhalaan H, AlRuways S, AlMutairi N, AlNakiyah M, AlGhofaili R, AlBakheet A, Alomrani A, Alharbi OA, Tous E, AlSayed M, AlZaidan H, AlRasheed MM, AlOdaib A, Kaya N. Clinical, radiological, and genetic characterization of SLC13A5 variants in Saudi families: Genotype phenotype correlation and brief review of the literature. Front Pediatr 2022; 10:1051534. [PMID: 36923948 PMCID: PMC10008858 DOI: 10.3389/fped.2022.1051534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 12/14/2022] [Indexed: 03/03/2023] Open
Abstract
Background SLC13A5 (solute carrier family 13, member 5) encodes sodium/citrate cotransporter, which mainly localizes in cellular plasma membranes in the frontal cortex, retina, and liver. Pathogenic variants of the gene cause an autosomal recessive syndrome known as "developmental and epileptic encephalopathy 25 with amelogenesis imperfecta." Results Here, we have investigated six patients from three different consanguineous Saudi families. The affected individuals presented with neonatal seizures, developmental delay, and significant defects in tooth development. Some patients showed other clinical features such as muscle weakness, motor difficulties, intellectual disability, microcephaly, and speech problems in addition to additional abnormalities revealed by electroencephalography (EEGs) and magnetic resonance imaging (MRI). One of the MRI findings was related to cortical thickening in the frontal lobe. To diagnose and study the genetic defects of the patients, whole exome sequencing (WES) coupled with confirmatory Sanger sequencing was utilized. Iterative filtering identified two variants of SLC13A5, one of which is novel, in the families. Families 1 and 2 had the same insertion (a previously reported mutation), leading to a frameshift and premature stop codon. The third family had a novel splice site variant. Confirmatory Sanger sequencing corroborated WES results and indicated full segregation of the variants in the corresponding families. The patients' conditions were poorly controlled by multiple antiepileptics as they needed constant care. Conclusion Considering that recessive mutations are common in the Arab population, SLC13A5 screening should be prioritized in future patients harboring similar symptoms including defects in molar development.
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Affiliation(s)
- Hanan AlQudairy
- Translational Genomic Department, Center for Genomic Medicine, King Faisal Specialist Hospital, and Research Centre (KFSHRC), Riyadh, Saudi Arabia
| | | | - Sarah AlRuways
- Translational Genomic Department, Center for Genomic Medicine, King Faisal Specialist Hospital, and Research Centre (KFSHRC), Riyadh, Saudi Arabia.,College of Pharmacy, King Saud University (KSU), Riyadh, Saudi Arabia
| | - Nouf AlMutairi
- Translational Genomic Department, Center for Genomic Medicine, King Faisal Specialist Hospital, and Research Centre (KFSHRC), Riyadh, Saudi Arabia.,College of Pharmacy, King Saud University (KSU), Riyadh, Saudi Arabia
| | - Maha AlNakiyah
- Translational Genomic Department, Center for Genomic Medicine, King Faisal Specialist Hospital, and Research Centre (KFSHRC), Riyadh, Saudi Arabia.,College of Pharmacy, King Saud University (KSU), Riyadh, Saudi Arabia
| | - Reema AlGhofaili
- Translational Genomic Department, Center for Genomic Medicine, King Faisal Specialist Hospital, and Research Centre (KFSHRC), Riyadh, Saudi Arabia.,College of Pharmacy, King Saud University (KSU), Riyadh, Saudi Arabia
| | | | | | - Omar A Alharbi
- Department of Neurosciences, KFSHRC, Riyadh, Saudi Arabia
| | - Ehab Tous
- Department of Neurosciences, KFSHRC, Riyadh, Saudi Arabia
| | - Moeen AlSayed
- Department of Medical Genomics, Center for Genomic Medicine, KFSHRC, Riyadh, Saudi Arabia
| | - Hamad AlZaidan
- Department of Medical Genomics, Center for Genomic Medicine, KFSHRC, Riyadh, Saudi Arabia
| | - Maha M AlRasheed
- College of Pharmacy, King Saud University (KSU), Riyadh, Saudi Arabia.,Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Ali AlOdaib
- Training and Education Department, Research Centre, KFSHRC, Riyadh, Saudi Arabia
| | - Namik Kaya
- Translational Genomic Department, Center for Genomic Medicine, King Faisal Specialist Hospital, and Research Centre (KFSHRC), Riyadh, Saudi Arabia
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21
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Nasu Y, Murphy-Royal C, Wen Y, Haidey JN, Molina RS, Aggarwal A, Zhang S, Kamijo Y, Paquet ME, Podgorski K, Drobizhev M, Bains JS, Lemieux MJ, Gordon GR, Campbell RE. A genetically encoded fluorescent biosensor for extracellular L-lactate. Nat Commun 2021; 12:7058. [PMID: 34873165 PMCID: PMC8648760 DOI: 10.1038/s41467-021-27332-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 11/15/2021] [Indexed: 01/22/2023] Open
Abstract
L-Lactate, traditionally considered a metabolic waste product, is increasingly recognized as an important intercellular energy currency in mammals. To enable investigations of the emerging roles of intercellular shuttling of L-lactate, we now report an intensiometric green fluorescent genetically encoded biosensor for extracellular L-lactate. This biosensor, designated eLACCO1.1, enables cellular resolution imaging of extracellular L-lactate in cultured mammalian cells and brain tissue.
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Affiliation(s)
- Yusuke Nasu
- grid.26999.3d0000 0001 2151 536XDepartment of Chemistry, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Ciaran Murphy-Royal
- grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Cumming School of Medicine, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1 Canada ,grid.410559.c0000 0001 0743 2111Centre Hospitalier de l’Université de Montréal, Department of Neuroscience, Faculty of Medicine, University of Montreal, Montreal, QC H2X 0A9 Canada
| | - Yurong Wen
- grid.17089.37Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7 Canada ,grid.452438.c0000 0004 1760 8119Department of Talent Highland, The First Affiliated Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi 710061 China
| | - Jordan N. Haidey
- grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Cumming School of Medicine, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1 Canada
| | - Rosana S. Molina
- grid.41891.350000 0001 2156 6108Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT 59717 USA
| | - Abhi Aggarwal
- grid.443970.dJanelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147 USA
| | - Shuce Zhang
- grid.17089.37Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2 Canada
| | - Yuki Kamijo
- grid.26999.3d0000 0001 2151 536XDepartment of Chemistry, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Marie-Eve Paquet
- grid.23856.3a0000 0004 1936 8390CERVO Brain Research Center, Laval University, Québec, QC G1E 1T2 Canada ,grid.23856.3a0000 0004 1936 8390Department of Biochemistry, Microbiology and Bioinformatics, Laval University, Québec, QC G1J 2G3 Canada
| | - Kaspar Podgorski
- grid.443970.dJanelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147 USA
| | - Mikhail Drobizhev
- grid.41891.350000 0001 2156 6108Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT 59717 USA
| | - Jaideep S. Bains
- grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Cumming School of Medicine, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1 Canada
| | - M. Joanne Lemieux
- grid.17089.37Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7 Canada
| | - Grant R. Gordon
- grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Cumming School of Medicine, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1 Canada
| | - Robert E. Campbell
- grid.26999.3d0000 0001 2151 536XDepartment of Chemistry, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan ,grid.17089.37Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2 Canada
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22
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Jeong J, Lee J, Kim JH, Lim C. Metabolic flux from the Krebs cycle to glutamate transmission tunes a neural brake on seizure onset. PLoS Genet 2021; 17:e1009871. [PMID: 34714823 PMCID: PMC8555787 DOI: 10.1371/journal.pgen.1009871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 10/11/2021] [Indexed: 01/18/2023] Open
Abstract
Kohlschütter-Tönz syndrome (KTS) manifests as neurological dysfunctions, including early-onset seizures. Mutations in the citrate transporter SLC13A5 are associated with KTS, yet their underlying mechanisms remain elusive. Here, we report that a Drosophila SLC13A5 homolog, I'm not dead yet (Indy), constitutes a neurometabolic pathway that suppresses seizure. Loss of Indy function in glutamatergic neurons caused "bang-induced" seizure-like behaviors. In fact, glutamate biosynthesis from the citric acid cycle was limiting in Indy mutants for seizure-suppressing glutamate transmission. Oral administration of the rate-limiting α-ketoglutarate in the metabolic pathway rescued low glutamate levels in Indy mutants and ameliorated their seizure-like behaviors. This metabolic control of the seizure susceptibility was mapped to a pair of glutamatergic neurons, reversible by optogenetic controls of their activity, and further relayed onto fan-shaped body neurons via the ionotropic glutamate receptors. Accordingly, our findings reveal a micro-circuit that links neural metabolism to seizure, providing important clues to KTS-associated neurodevelopmental deficits.
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Affiliation(s)
- Jiwon Jeong
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jongbin Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Ji-hyung Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- * E-mail:
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23
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Brown TL, Nye KL, Porter BE. Growth and Overall Health of Patients with SLC13A5 Citrate Transporter Disorder. Metabolites 2021; 11:metabo11110746. [PMID: 34822404 PMCID: PMC8625967 DOI: 10.3390/metabo11110746] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 11/16/2022] Open
Abstract
We were interested in elucidating the non-neurologic health of patients with autosomal recessive SLC13A5 Citrate Transporter (NaCT) Disorder. Multiple variants have been reported that cause a loss of transporter activity, resulting in significant neurologic impairment, including seizures, as well as motor and cognitive dysfunction. Additionally, most patients lack tooth enamel (amelogenesis imperfecta). However, patients have not had their overall health and growth described in detail. Here we characterized the non-neurologic health of 15 patients with medical records uploaded to Ciitizen, a cloud-based patient medical records portal. Ciitizen used a query method for data extraction. Overall, the patients’ records suggested a moderate number of gastrointestinal issues related to feeding, reflux, vomiting and weight gain and a diverse number of respiratory complaints. Other organ systems had single or no abnormal diagnoses, including liver, renal and cardiac. Growth parameters were mostly in the normal range during early life, with a trend toward slower growth in the few adolescent patients with data available. The gastrointestinal and pulmonary issues may at least partially be explained by the severity of the neurologic disorder. More data are needed to clarify if growth is impacted during adolescence and if adult patients develop or are protected from non-neurologic disorders.
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Affiliation(s)
- Tanya L. Brown
- Treatments for Epilepsy and Symptoms of SLC13A5 Foundation, TESS Research Foundation, Menlo Park, CA 94026, USA;
- Correspondence:
| | - Kimberly L. Nye
- Treatments for Epilepsy and Symptoms of SLC13A5 Foundation, TESS Research Foundation, Menlo Park, CA 94026, USA;
| | - Brenda E. Porter
- Department of Neurology and Neurological Sciences, Stanford University, Palo Alto, CA 94070, USA;
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24
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Molecular Mechanisms of the SLC13A5 Gene Transcription. Metabolites 2021; 11:metabo11100706. [PMID: 34677420 PMCID: PMC8537064 DOI: 10.3390/metabo11100706] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 12/02/2022] Open
Abstract
Citrate is a crucial energy sensor that plays a central role in cellular metabolic homeostasis. The solute carrier family 13 member 5 (SLC13A5), a sodium-coupled citrate transporter highly expressed in the mammalian liver with relatively low levels in the testis and brain, imports citrate from extracellular spaces into the cells. The perturbation of SLC13A5 expression and/or activity is associated with non-alcoholic fatty liver disease, obesity, insulin resistance, cell proliferation, and early infantile epileptic encephalopathy. SLC13A5 has been proposed as a promising therapeutic target for the treatment of these metabolic disorders. In the liver, the inductive expression of SLC13A5 has been linked to several xenobiotic receptors such as the pregnane X receptor and the aryl hydrocarbon receptor as well as certain hormonal and nutritional stimuli. Nevertheless, in comparison to the heightened interest in understanding the biological function and clinical relevance of SLC13A5, studies focusing on the regulatory mechanisms of SLC13A5 expression are relatively limited. In this review, we discuss the current advances in our understanding of the molecular mechanisms by which the expression of SLC13A5 is regulated. We expect this review will provide greater insights into the regulation of the SLC13A5 gene transcription and the signaling pathways involved therein.
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25
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Kumar A, Cordes T, Thalacker-Mercer AE, Pajor AM, Murphy AN, Metallo CM. NaCT/SLC13A5 facilitates citrate import and metabolism under nutrient-limited conditions. Cell Rep 2021; 36:109701. [PMID: 34525352 PMCID: PMC8500708 DOI: 10.1016/j.celrep.2021.109701] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/19/2021] [Accepted: 08/20/2021] [Indexed: 01/11/2023] Open
Abstract
Citrate lies at a critical node of metabolism, linking tricarboxylic acid metabolism and lipogenesis via acetyl-coenzyme A. Recent studies have observed that deficiency of the sodium-dependent citrate transporter (NaCT), encoded by SLC13A5, dysregulates hepatic metabolism and drives pediatric epilepsy. To examine how NaCT contributes to citrate metabolism in cells relevant to the pathophysiology of these diseases, we apply 13C isotope tracing to SLC13A5-deficient hepatocellular carcinoma (HCC) cells and primary rat cortical neurons. Exogenous citrate appreciably contributes to intermediary metabolism only under hypoxic conditions. In the absence of glutamine, citrate supplementation increases de novo lipogenesis and growth of HCC cells. Knockout of SLC13A5 in Huh7 cells compromises citrate uptake and catabolism. Citrate supplementation rescues Huh7 cell viability in response to glutamine deprivation or Zn2+ treatment, and NaCT deficiency mitigates these effects. Collectively, these findings demonstrate that NaCT-mediated citrate uptake is metabolically important under nutrient-limited conditions and may facilitate resistance to metal toxicity.
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Affiliation(s)
- Avi Kumar
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Thekla Cordes
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anna E Thalacker-Mercer
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14850, USA; Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ana M Pajor
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anne N Murphy
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Christian M Metallo
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, University of California, San Diego, La Jolla, CA 92037, USA.
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26
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Consequences of NaCT/SLC13A5/mINDY deficiency: good versus evil, separated only by the blood-brain barrier. Biochem J 2021; 478:463-486. [PMID: 33544126 PMCID: PMC7868109 DOI: 10.1042/bcj20200877] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/07/2021] [Accepted: 01/11/2021] [Indexed: 02/08/2023]
Abstract
NaCT/SLC13A5 is a Na+-coupled transporter for citrate in hepatocytes, neurons, and testes. It is also called mINDY (mammalian ortholog of ‘I'm Not Dead Yet’ in Drosophila). Deletion of Slc13a5 in mice leads to an advantageous phenotype, protecting against diet-induced obesity, and diabetes. In contrast, loss-of-function mutations in SLC13A5 in humans cause a severe disease, EIEE25/DEE25 (early infantile epileptic encephalopathy-25/developmental epileptic encephalopathy-25). The difference between mice and humans in the consequences of the transporter deficiency is intriguing but probably explainable by the species-specific differences in the functional features of the transporter. Mouse Slc13a5 is a low-capacity transporter, whereas human SLC13A5 is a high-capacity transporter, thus leading to quantitative differences in citrate entry into cells via the transporter. These findings raise doubts as to the utility of mouse models to evaluate NaCT biology in humans. NaCT-mediated citrate entry in the liver impacts fatty acid and cholesterol synthesis, fatty acid oxidation, glycolysis, and gluconeogenesis; in neurons, this process is essential for the synthesis of the neurotransmitters glutamate, GABA, and acetylcholine. Thus, SLC13A5 deficiency protects against obesity and diabetes based on what the transporter does in hepatocytes, but leads to severe brain deficits based on what the transporter does in neurons. These beneficial versus detrimental effects of SLC13A5 deficiency are separable only by the blood-brain barrier. Can we harness the beneficial effects of SLC13A5 deficiency without the detrimental effects? In theory, this should be feasible with selective inhibitors of NaCT, which work only in the liver and do not get across the blood-brain barrier.
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27
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A home run for human NaCT/SLC13A5/INDY: cryo-EM structure and homology model to predict transport mechanisms, inhibitor interactions and mutational defects. Biochem J 2021; 478:2051-2057. [PMID: 34101804 PMCID: PMC8203205 DOI: 10.1042/bcj20210211] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 11/26/2022]
Abstract
NaCT (SLC13A5) is a Na+-coupled transporter for citrate, which is expressed in the liver, brain, testes, and bone. It is the mammalian homolog of Drosophila INDY, a cation-independent transporter for citrate, whose partial loss extends lifespan in the organism. In humans, loss-of-function mutations in NaCT cause a disease with severe neurological dysfunction, characterized by neonatal epilepsy and delayed brain development. In contrast with humans, deletion of NaCT in mice results in a beneficial metabolic phenotype with protection against diet-induced obesity and metabolic syndrome; the brain dysfunction is not readily noticeable. The disease-causing mutations are located in different regions of human NaCT protein, suggesting that different mutations might have different mechanisms for the loss of function. The beneficial effects of NaCT loss in the liver versus the detrimental effects of NaCT loss in the brain provide an opportunity to design high-affinity inhibitors for the transporter that do not cross the blood-brain barrier so that only the beneficial effects could be harnessed. To realize these goals, we need a detailed knowledge of the 3D structure of human NaCT. The recent report by Sauer et al. in Nature describing the cryo-EM structure of human NaCT represents such a milestone, paving the way for a better understanding of the structure-function relationship for this interesting and clinically important transporter.
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28
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Ozlu C, Bailey RM, Sinnett S, Goodspeed KD. Gene Transfer Therapy for Neurodevelopmental Disorders. Dev Neurosci 2021; 43:230-240. [PMID: 33882495 DOI: 10.1159/000515434] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/13/2021] [Indexed: 11/19/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) include a broad spectrum of disorders that disrupt normal brain development. Though some NDDs are caused by acquired insults (i.e., toxic or infectious encephalopathy) or may be cryptogenic, many NDDs are caused by variants in a single gene or groups of genes that disrupt neuronal development or function. In this review, we will focus on those NDDs with a genetic etiology. The exact mechanism, timing, and progression of the molecular pathology are seldom well known; however, the abnormalities in development typically manifest in similar patterns such as delays or regression in motor function, social skills, and language or cognitive abilities. Severity of impairment can vary widely. At present, only symptomatic treatments are available to manage seizures and behavioral problems commonly seen in NDDs. In recent years, there has been a rapid expansion of research into gene therapy using adeno-associated viruses (AAVs). Using AAVs as vectors to replace the non- or dysfunctional gene in vivo is a relatively simple model which has created an unprecedented opportunity for the future of NDD treatment. Advances in this field are of paramount importance as NDDs lead to a massive lifelong burden of disease on the affected individuals and families. In this article, we review the unique advantages and challenges of AAV gene therapies. We then look at potential applications of gene therapy for 3 of the more common NDDs (Rett syndrome, fragile X syndrome, and Angelman syndrome), as well as 2 less common NDDs (SLC13A5 deficiency disorder and SLC6A1-related disorder). We will review the available natural history of each disease and current state of preclinical studies including a discussion on the application of AAV gene therapies for each disease.
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Affiliation(s)
- Can Ozlu
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Rachel M Bailey
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Center for Alzheimer's and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sarah Sinnett
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kimberly D Goodspeed
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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29
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Duan R, Saadi NW, Grochowski CM, Bhadila G, Faridoun A, Mitani T, Du H, Fatih JM, Jhangiani SN, Akdemir ZC, Gibbs RA, Pehlivan D, Posey JE, Marafi D, Lupski JR. A novel homozygous SLC13A5 whole-gene deletion generated by Alu/Alu-mediated rearrangement in an Iraqi family with epileptic encephalopathy. Am J Med Genet A 2021; 185:1972-1980. [PMID: 33797191 DOI: 10.1002/ajmg.a.62192] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/10/2021] [Accepted: 03/05/2021] [Indexed: 01/05/2023]
Abstract
Biallelic loss-of-function (LoF) of SLC13A5 (solute carrier family 13, member 5) induced deficiency in sodium/citrate transporter (NaCT) causes autosomal recessive developmental epileptic encephalopathy 25 with hypoplastic amelogenesis imperfecta (DEE25; MIM #615905). Many pathogenic SLC13A5 single nucleotide variants (SNVs) and small indels have been described; however, no cases with copy number variants (CNVs) have been sufficiently investigated. We describe a consanguineous Iraqi family harboring an 88.5 kb homozygous deletion including SLC13A5 in Chr17p13.1. The three affected male siblings exhibit neonatal-onset epilepsy with fever-sensitivity, recurrent status epilepticus, global developmental delay/intellectual disability (GDD/ID), and other variable neurological findings as shared phenotypical features of DEE25. Two of the three affected subjects exhibit hypoplastic amelogenesis imperfecta (AI), while the proband shows no evidence of dental abnormalities or AI at 2 years of age with apparently unaffected primary dentition. Characterization of the genomic architecture at this locus revealed evidence for genomic instability generated by an Alu/Alu-mediated rearrangement; confirmed by break-point junction Sanger sequencing. This multiplex family from a distinct population elucidates the phenotypic consequence of complete LoF of SLC13A5 and illustrates the importance of read-depth-based CNV detection in comprehensive exome sequencing analysis to solve cases that otherwise remain molecularly unsolved.
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Affiliation(s)
- Ruizhi Duan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Nebal Waill Saadi
- College of Medicine, University of Baghdad, Baghdad, Iraq.,Children Welfare Teaching Hospital, Medical City Complex, Baghdad, Iraq
| | | | - Ghalia Bhadila
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, Maryland, USA.,Department of Pediatric Dentistry, Faculty of Dentistry, King AbdulAziz University, Jeddah, Saudi Arabia
| | - Afnan Faridoun
- Department of General Dental Practice, Faculty of Dentistry, Kuwait University, Kuwait
| | - Tadahiro Mitani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Haowei Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Jawid M Fatih
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Shalini N Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Zeynep C Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Davut Pehlivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA.,Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine & Texas Children's Hospital, Houston, Texas, USA
| | - Jennifer E Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Dana Marafi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Department of Pediatrics, Faculty of Medicine, Kuwait University, Safat, Kuwait
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
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30
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Functional analysis of a species-specific inhibitor selective for human Na+-coupled citrate transporter (NaCT/SLC13A5/mINDY). Biochem J 2021; 477:4149-4165. [PMID: 33079129 PMCID: PMC7657661 DOI: 10.1042/bcj20200592] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/12/2020] [Accepted: 10/20/2020] [Indexed: 12/14/2022]
Abstract
The Na+-coupled citrate transporter (NaCT/SLC13A5/mINDY) in the liver delivers citrate from the blood into hepatocytes. As citrate is a key metabolite and regulator of multiple biochemical pathways, deletion of Slc13a5 in mice protects against diet-induced obesity, diabetes, and metabolic syndrome. Silencing the transporter suppresses hepatocellular carcinoma. Therefore, selective blockers of NaCT hold the potential to treat various diseases. Here we report on the characteristics of one such inhibitor, BI01383298. It is known that BI01383298 is a high-affinity inhibitor selective for human NaCT with no effect on mouse NaCT. Here we show that this compound is an irreversible and non-competitive inhibitor of human NaCT, thus describing the first irreversible inhibitor for this transporter. The mouse NaCT is not affected by this compound. The inhibition of human NaCT by BI01383298 is evident for the constitutively expressed transporter in HepG2 cells and for the ectopically expressed human NaCT in HEK293 cells. The IC50 is ∼100 nM, representing the highest potency among the NaCT inhibitors known to date. Exposure of HepG2 cells to this inhibitor results in decreased cell proliferation. We performed molecular modeling of the 3D-structures of human and mouse NaCTs using the crystal structure of a humanized variant of VcINDY as the template, and docking studies to identify the amino acid residues involved in the binding of citrate and BI01383298. These studies provide insight into the probable bases for the differential effects of the inhibitor on human NaCT versus mouse NaCT as well as for the marked species-specific difference in citrate affinity.
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31
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Sauer DB, Song J, Wang B, Hilton JK, Karpowich NK, Mindell JA, Rice WJ, Wang DN. Structure and inhibition mechanism of the human citrate transporter NaCT. Nature 2021; 591:157-161. [PMID: 33597751 PMCID: PMC7933130 DOI: 10.1038/s41586-021-03230-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 01/12/2021] [Indexed: 11/16/2022]
Abstract
Citrate is most well-known as an intermediate in the TCA cycle of the cell. In addition to this essential role in energy metabolism, the tricarboxylate anion also acts as both a precursor and a regulator of fatty acid synthesis 1–3. Thus, the rate of fatty acid synthesis correlates directly with the cytosolic citrate concentration 4,5. Liver cells import citrate via the sodium-dependent citrate transporter NaCT (SLC13A5), and as a consequence this protein is a potential target for anti-obesity drugs. To understand the structural basis of its inhibition mechanism, we have determined cryo-electron microscopy structures of human NaCT in complex with citrate and with a small molecule inhibitor. These structures reveal how the inhibitor, bound at the same site as citrate, arrests the protein’s transport cycle. The NaCT-inhibitor structure also explains why the compound selectively inhibits NaCT over two homologous human dicarboxylate transporters, and suggests ways to further improve the affinity and selectivity. Finally, the NaCT structures provide a framework for understanding how various mutations abolish NaCT’s transport activity in the brain and thereby cause SLC13A5-Epilepsy in newborns 6–8.
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Affiliation(s)
- David B Sauer
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA.,Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Jinmei Song
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA.,Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Bing Wang
- Cryo-Electron Microscopy Core, New York University School of Medicine, New York, NY, USA
| | - Jacob K Hilton
- Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Nathan K Karpowich
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA.,Department of Cell Biology, New York University School of Medicine, New York, NY, USA.,Janssen Pharmaceuticals, Spring House, PA, USA
| | - Joseph A Mindell
- Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - William J Rice
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA. .,Cryo-Electron Microscopy Core, New York University School of Medicine, New York, NY, USA.
| | - Da-Neng Wang
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA. .,Department of Cell Biology, New York University School of Medicine, New York, NY, USA.
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32
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Matricardi S, De Liso P, Freri E, Costa P, Castellotti B, Magri S, Gellera C, Granata T, Musante L, Lesca G, Oertel J, Craiu D, Hammer TB, Møller RS, Barisic N, Abou Jamra R, Polster T, Vigevano F, Marini C. Neonatal developmental and epileptic encephalopathy due to autosomal recessive variants in
SLC13A5
gene. Epilepsia 2020; 61:2474-2485. [DOI: 10.1111/epi.16699] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/18/2020] [Accepted: 08/31/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Sara Matricardi
- Department of Child Neuropsychiatry Children’s Hospital Ancona Italy
| | - Paola De Liso
- Department of Neuroscience Istituto di Ricovero e Cura a Carattere Scientifico Bambino Gesù Children's Hospital Rome Italy
| | - Elena Freri
- Department of Pediatric Neuroscience Istituto di Ricovero e Cura a Carattere Scientifico Foundation Carlo Besta Neurological Institute Milan Italy
| | - Paola Costa
- Department of Neuropsychiatry Institute for Maternal and Child Health Istituto di Ricovero e Cura a Carattere Scientifico Burlo Garofolo Trieste Italy
| | - Barbara Castellotti
- Unit of Medical Genetics and Neurogenetics Istituto di Ricovero e Cura a Carattere Scientifico Foundation Carlo Besta Neurological Institute Milan Italy
| | - Stefania Magri
- Unit of Medical Genetics and Neurogenetics Istituto di Ricovero e Cura a Carattere Scientifico Foundation Carlo Besta Neurological Institute Milan Italy
| | - Cinzia Gellera
- Unit of Medical Genetics and Neurogenetics Istituto di Ricovero e Cura a Carattere Scientifico Foundation Carlo Besta Neurological Institute Milan Italy
| | - Tiziana Granata
- Department of Pediatric Neuroscience Istituto di Ricovero e Cura a Carattere Scientifico Foundation Carlo Besta Neurological Institute Milan Italy
| | - Luciana Musante
- Department of Medical Genetics Institute for Maternal and Child Health Istituto di Ricovero e Cura a Carattere Scientifico Burlo Garofolo Trieste Italy
| | - Gaetan Lesca
- Department of Medical Genetics Lyon Civil Hospices Lyon France
| | - Julie Oertel
- Department of Medical Genetics Archet Hospital 2, Nice University Hospital Center Nice France
| | - Dana Craiu
- Department of Clinical Neurosciences Carol Davila University of Medicine and Pharmacy Bucharest Bucharest Romania
- Pediatric Neurology Clinic Alexandru Obregia Hospital Bucharest Romania
| | | | - Rikke S. Møller
- Danish Epilepsy Center Filadelfia Dianalund Denmark
- Institute for Regional Health Services University of Southern Denmark Odense Denmark
| | - Nina Barisic
- Division of Child Neurology Department of Pediatrics Clinical Medical Center Zagreb University of Zagreb Medical School Zagreb Croatia
| | - Rami Abou Jamra
- Institute of Human Genetics University Medical Center Leipzig Leipzig Germany
| | - Tilman Polster
- Pediatric Epileptology Mara HospitalBethel Epilepsy Center Bielefeld Germany
| | - Federico Vigevano
- Department of Neuroscience Istituto di Ricovero e Cura a Carattere Scientifico Bambino Gesù Children's Hospital Rome Italy
| | - Carla Marini
- Department of Child Neuropsychiatry Children’s Hospital Ancona Italy
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33
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Jaramillo-Martinez V, Urbatsch IL, Ganapathy V. Functional Distinction between Human and Mouse Sodium-Coupled Citrate Transporters and Its Biologic Significance: An Attempt for Structural Basis Using a Homology Modeling Approach. Chem Rev 2020; 121:5359-5377. [PMID: 33040525 DOI: 10.1021/acs.chemrev.0c00529] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
NaCT (SLC13A5; mINDY), a sodium-coupled citrate transporter, is the mammalian ortholog of Drosophila INDY. Loss-of-function mutations in human NaCT cause severe complications with neonatal epilepsy and encephalopathy (EIEE25). Surprisingly, mice lacking this transporter do not have this detrimental brain phenotype. The marked differences in transport kinetics between mouse and human NaCTs provide at least a partial explanation for this conundrum, but a structural basis for the differences is lacking. Neither human nor mouse NaCT has been crystallized, and any information known on their structures is based entirely on what was inferred from the structure of VcINDY, a related transporter in bacteria. Here, we highlight the functional features of human and mouse NaCTs and provide a plausible molecular basis for the differences based on a full-length homology modeling approach. The transport characteristics of human NaCT markedly differ from those of VcINDY. Therefore, the modeling with VcINDY as the template is flawed, but this is the best available option at this time. With the newly deduced model, we determined the likely locations of the disease-causing mutations and propose a new classification for the mutations based on their location and potential impact on transport function. This new information should pave the way for future design and development of novel therapeutics to restore the lost function of the mutant transporters as a treatment strategy for patients with EIEE25.
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Affiliation(s)
- Valeria Jaramillo-Martinez
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Ina L Urbatsch
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States.,Center for Membrane Protein Research and Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States.,Center for Membrane Protein Research and Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
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34
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Schumann T, König J, Henke C, Willmes DM, Bornstein SR, Jordan J, Fromm MF, Birkenfeld AL. Solute Carrier Transporters as Potential Targets for the Treatment of Metabolic Disease. Pharmacol Rev 2020; 72:343-379. [PMID: 31882442 DOI: 10.1124/pr.118.015735] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The solute carrier (SLC) superfamily comprises more than 400 transport proteins mediating the influx and efflux of substances such as ions, nucleotides, and sugars across biological membranes. Over 80 SLC transporters have been linked to human diseases, including obesity and type 2 diabetes (T2D). This observation highlights the importance of SLCs for human (patho)physiology. Yet, only a small number of SLC proteins are validated drug targets. The most recent drug class approved for the treatment of T2D targets sodium-glucose cotransporter 2, product of the SLC5A2 gene. There is great interest in identifying other SLC transporters as potential targets for the treatment of metabolic diseases. Finding better treatments will prove essential in future years, given the enormous personal and socioeconomic burden posed by more than 500 million patients with T2D by 2040 worldwide. In this review, we summarize the evidence for SLC transporters as target structures in metabolic disease. To this end, we identified SLC13A5/sodium-coupled citrate transporter, and recent proof-of-concept studies confirm its therapeutic potential in T2D and nonalcoholic fatty liver disease. Further SLC transporters were linked in multiple genome-wide association studies to T2D or related metabolic disorders. In addition to presenting better-characterized potential therapeutic targets, we discuss the likely unnoticed link between other SLC transporters and metabolic disease. Recognition of their potential may promote research on these proteins for future medical management of human metabolic diseases such as obesity, fatty liver disease, and T2D. SIGNIFICANCE STATEMENT: Given the fact that the prevalence of human metabolic diseases such as obesity and type 2 diabetes has dramatically risen, pharmacological intervention will be a key future approach to managing their burden and reducing mortality. In this review, we present the evidence for solute carrier (SLC) genes associated with human metabolic diseases and discuss the potential of SLC transporters as therapeutic target structures.
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Affiliation(s)
- Tina Schumann
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Jörg König
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Christine Henke
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Diana M Willmes
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Stefan R Bornstein
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Jens Jordan
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Martin F Fromm
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
| | - Andreas L Birkenfeld
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine (T.S., C.H., D.M.W., S.R.B.), and Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine (T.S., C.H., D.M.W.), Technische Universität Dresden, Dresden, Germany; Deutsches Zentrum für Diabetesforschung e.V., Neuherberg, Germany (T.S., C.H., D.M.W., A.L.B.); Clinical Pharmacology and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (J.K., M.F.F.); Institute for Aerospace Medicine, German Aerospace Center and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany (J.J.); Diabetes and Nutritional Sciences, King's College London, London, United Kingdom (S.R.B., A.L.B.); Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany (A.L.B.); and Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany (A.L.B.)
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Hu T, Huang W, Li Z, Kane MA, Zhang L, Huang SM, Wang H. Comparative proteomic analysis of SLC13A5 knockdown reveals elevated ketogenesis and enhanced cellular toxic response to chemotherapeutic agents in HepG2 cells. Toxicol Appl Pharmacol 2020; 402:115117. [PMID: 32634519 DOI: 10.1016/j.taap.2020.115117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 06/09/2020] [Accepted: 06/12/2020] [Indexed: 12/29/2022]
Abstract
Solute carrier family 13 member 5 (SLC13A5) is an uptake transporter mainly expressed in the liver and transports citrate from blood circulation into hepatocytes. Accumulating evidence suggests that SLC13A5 is involved in hepatic lipogenesis, cell proliferation, epilepsy, and bone development in mammals. However, the molecular mechanisms behind SLC13A5-mediated physiological/pathophysiological changes are largely unknown. In this regard, we conducted a differential proteome analysis in HepG2 and SLC13A5-knockdown (KD) HepG2 cells. A total of 3826 proteins were quantified and 330 proteins showed significant alterations (fold change ≥1.5; p < .05) in the knockdown cells. Gene ontology enrichment analysis reveals that 38 biological processes were significantly changed, with ketone body biosynthetic process showing the most significant upregulation following SLC13A5-KD. Catalytic activity and binding activity were the top two molecular functions associated with differentially expressed proteins, while HMG-CoA lyase activity showed the highest fold enrichment. Further ingenuity pathway analysis predicted 40 canonical pathways and 28 upstream regulators (p < .01), of which most were associated with metabolism, cell proliferation, and stress response. In line with these findings, functional validation demonstrated increased levels of two key ketone bodies, acetoacetate and β-hydroxybutyrate, in the SLC13A5-KD cells. Additional experiments showed that SLC13A5-KD sensitizes HepG2 cells to cellular stress caused by a number of chemotherapeutic agents. Together, our findings demonstrate that knockdown of SLC13A5 promotes hepatic ketogenesis and enhances cellular stress response in HepG2 cells, suggesting a potential role of this transporter in metabolic disorders and liver cancer.
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Affiliation(s)
- Tao Hu
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States of America
| | - Weiliang Huang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States of America
| | - Zhihui Li
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States of America
| | - Maureen A Kane
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States of America
| | - Lei Zhang
- Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, Food and Drug Administration (FDA), Silver Spring, MD 20993, United States of America
| | - Shiew-Mei Huang
- Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, Food and Drug Administration (FDA), Silver Spring, MD 20993, United States of America
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States of America.
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36
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Sauer DB, Trebesch N, Marden JJ, Cocco N, Song J, Koide A, Koide S, Tajkhorshid E, Wang DN. Structural basis for the reaction cycle of DASS dicarboxylate transporters. eLife 2020; 9:e61350. [PMID: 32869741 PMCID: PMC7553777 DOI: 10.7554/elife.61350] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 08/31/2020] [Indexed: 01/09/2023] Open
Abstract
Citrate, α-ketoglutarate and succinate are TCA cycle intermediates that also play essential roles in metabolic signaling and cellular regulation. These di- and tricarboxylates are imported into the cell by the divalent anion sodium symporter (DASS) family of plasma membrane transporters, which contains both cotransporters and exchangers. While DASS proteins transport substrates via an elevator mechanism, to date structures are only available for a single DASS cotransporter protein in a substrate-bound, inward-facing state. We report multiple cryo-EM and X-ray structures in four different states, including three hitherto unseen states, along with molecular dynamics simulations, of both a cotransporter and an exchanger. Comparison of these outward- and inward-facing structures reveal how the transport domain translates and rotates within the framework of the scaffold domain through the transport cycle. Additionally, we propose that DASS transporters ensure substrate coupling by a charge-compensation mechanism, and by structural changes upon substrate release.
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Affiliation(s)
- David B Sauer
- Skirball Institute of Biomolecular Medicine, New York University School of MedicineNew YorkUnited States
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Noah Trebesch
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-ChampaignUrbanaUnited States
| | - Jennifer J Marden
- Skirball Institute of Biomolecular Medicine, New York University School of MedicineNew YorkUnited States
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Nicolette Cocco
- Skirball Institute of Biomolecular Medicine, New York University School of MedicineNew YorkUnited States
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Jinmei Song
- Skirball Institute of Biomolecular Medicine, New York University School of MedicineNew YorkUnited States
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Akiko Koide
- Perlmutter Cancer Center, New York University School of MedicineNew YorkUnited States
- Department of Medicine, New York University School of MedicineNew YorkUnited States
| | - Shohei Koide
- Perlmutter Cancer Center, New York University School of MedicineNew YorkUnited States
- Department of Medicine, New York University School of MedicineNew YorkUnited States
- Department of Biochemistry and Molecular Pharmacology, New York University School of MedicineNew YorkUnited States
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-ChampaignUrbanaUnited States
| | - Da-Neng Wang
- Skirball Institute of Biomolecular Medicine, New York University School of MedicineNew YorkUnited States
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
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37
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Zhao Y, Shen Y, Wen Y, Campbell RE. High-Performance Intensiometric Direct- and Inverse-Response Genetically Encoded Biosensors for Citrate. ACS CENTRAL SCIENCE 2020; 6:1441-1450. [PMID: 32875085 PMCID: PMC7453566 DOI: 10.1021/acscentsci.0c00518] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Indexed: 05/02/2023]
Abstract
Motivated by the growing recognition of citrate as a central metabolite in a variety of biological processes associated with healthy and diseased cellular states, we have developed a series of high-performance genetically encoded citrate biosensors suitable for imaging of citrate concentrations in mammalian cells. The design of these biosensors was guided by structural studies of the citrate-responsive sensor histidine kinase and took advantage of the same conformational changes proposed to propagate from the binding domain to the catalytic domain. Following extensive engineering based on a combination of structure guided mutagenesis and directed evolution, we produced an inverse-response biosensor (ΔF/F min ≈ 18) designated Citroff1 and a direct-response biosensor (ΔF/F min ≈ 9) designated Citron1. We report the X-ray crystal structure of Citron1 and demonstrate the utility of both biosensors for qualitative and quantitative imaging of steady-state and pharmacologically perturbed citrate concentrations in live cells.
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Affiliation(s)
- Yufeng Zhao
- Department
of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Yi Shen
- Department
of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Yurong Wen
- Department
of Talent Highland, The First Affiliated
Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
- . (Y.W.; regarding x-ray crystallography)
| | - Robert E. Campbell
- Department
of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- . (R.E.C.)
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38
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Colas C. Toward a Systematic Structural and Functional Annotation of Solute Carriers Transporters-Example of the SLC6 and SLC7 Families. Front Pharmacol 2020; 11:1229. [PMID: 32973497 PMCID: PMC7466448 DOI: 10.3389/fphar.2020.01229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022] Open
Abstract
SLC transporters are emerging key drug targets. One important step for drug development is the profound understanding of the structural determinants defining the substrate selectivity of each transporter. Recently, the improvement of computational power and experimental methods such as X-ray and cryo-EM crystallography permitted to conduct structure-based studies on specific transporters having important pharmacological impact. However, a lot remains to be discovered regarding their dynamics, transport modulation and ligand recognition. A detailed functional characterization of transporters would provide opportunities to develop new compounds targeting these key drug targets. Here, we are giving an overview of two major human LeuT-fold families, SLC6 and SLC7, with an emphasis on the most relevant members of each family for drug development. We gather the most recent understanding on the structural determinants of selectivity within and across the two families. We then use this information to discuss the benefits of a more generalized structural and functional annotation of the LeuT fold and the implications of such mapping for drug discovery.
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Affiliation(s)
- Claire Colas
- University of Vienna, Department of Pharmaceutical Chemistry, Vienna, Austria
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39
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Henke C, Töllner K, van Dijk RM, Miljanovic N, Cordes T, Twele F, Bröer S, Ziesak V, Rohde M, Hauck SM, Vogel C, Welzel L, Schumann T, Willmes DM, Kurzbach A, El-Agroudy NN, Bornstein SR, Schneider SA, Jordan J, Potschka H, Metallo CM, Köhling R, Birkenfeld AL, Löscher W. Disruption of the sodium-dependent citrate transporter SLC13A5 in mice causes alterations in brain citrate levels and neuronal network excitability in the hippocampus. Neurobiol Dis 2020; 143:105018. [PMID: 32682952 DOI: 10.1016/j.nbd.2020.105018] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/08/2020] [Accepted: 07/11/2020] [Indexed: 12/28/2022] Open
Abstract
In addition to tissues such as liver, the plasma membrane sodium-dependent citrate transporter, NaCT (SLC13A5), is highly expressed in brain neurons, but its function is not understood. Loss-of-function mutations in the human SLC13A5 gene have been associated with severe neonatal encephalopathy and pharmacoresistant seizures. The molecular mechanisms of these neurological alterations are not clear. We performed a detailed examination of a Slc13a5 deletion mouse model including video-EEG monitoring, behavioral tests, and electrophysiologic, proteomic, and metabolomic analyses of brain and cerebrospinal fluid. The experiments revealed an increased propensity for epileptic seizures, proepileptogenic neuronal excitability changes in the hippocampus, and significant citrate alterations in the CSF and brain tissue of Slc13a5 deficient mice, which may underlie the neurological abnormalities. These data demonstrate that SLC13A5 is involved in brain citrate regulation and suggest that abnormalities in this regulation can induce seizures. The present study is the first to (i) establish the Slc13a5-knockout mouse model as a helpful tool to study the neuronal functions of NaCT and characterize the molecular mechanisms by which functional deficiency of this citrate transporter causes epilepsy and impairs neuronal function; (ii) evaluate all hypotheses that have previously been suggested on theoretical grounds to explain the neurological phenotype of SLC13A5 mutations; and (iii) indicate that alterations in brain citrate levels result in neuronal network excitability and increased seizure propensity.
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Affiliation(s)
- Christine Henke
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Kathrin Töllner
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - R Maarten van Dijk
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Nina Miljanovic
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Thekla Cordes
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Friederike Twele
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Sonja Bröer
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Vanessa Ziesak
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Rostock, Germany
| | - Marco Rohde
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Rostock, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science, Helmholtz Center Munich, Neuherberg, Germany
| | - Charlotte Vogel
- Department of Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hannover, Germany
| | - Lisa Welzel
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany
| | - Tina Schumann
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Diana M Willmes
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Anica Kurzbach
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Nermeen N El-Agroudy
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Stefan R Bornstein
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany
| | | | - Jens Jordan
- Institute for Aerospace Medicine, German Aerospace Center (DLR) and Chair for Aerospace Medicine, University of Cologne, Cologne, Germany
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Christian M Metallo
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, University of California, San Diego, La Jolla, CA 92037, USA
| | - Rüdiger Köhling
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Rostock, Germany
| | - Andreas L Birkenfeld
- Section of Metabolic and Vascular Medicine, Medical Clinic III, Dresden University School of Medicine, Technische Universität Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany.
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40
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Yang QZ, Spelbrink EM, Nye KL, Hsu ER, Porter BE. Epilepsy and EEG Phenotype of SLC13A5 Citrate Transporter Disorder. Child Neurol Open 2020; 7:2329048X20931361. [PMID: 32551328 PMCID: PMC7281881 DOI: 10.1177/2329048x20931361] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/28/2020] [Accepted: 05/10/2020] [Indexed: 11/15/2022] Open
Abstract
Mutations in the SLC13A5 gene, a sodium citrate cotransporter, cause a rare autosomal recessive epilepsy (EIEE25) that begins during the neonatal period and is associated with motor and cognitive impairment. Patient's seizure burden, semiology, and electroencephalography (EEG) findings have not been well characterized. Data on 23 patients, 3 months to 29 years of age are reported. Seizures began during the neonatal period in 22 patients. Although seizures are quite severe in many patients later in life, seizure freedom was attainable in a minority of patients. Multiple patients' chronic seizure management included a few common medications, phenobarbital and valproic acid in particular. Patients EEGs had a relatively well-preserved background for age, even in the face of frequent seizures, little slowing and multiple normal EEGs and do not support an epileptic encephalopathy. Other causes for the motor and cognitive delay beyond epilepsy warrant further study.
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Affiliation(s)
- Qian-Zhou Yang
- Division of Child Neurology, Department of Neurology, Stanford University School of Medicine, CA, USA
| | - Emily M Spelbrink
- Division of Child Neurology, Department of Neurology, Stanford University School of Medicine, CA, USA
| | | | - Emily R Hsu
- TESS Research Foundation, Redwood City, CA, USA
| | - Brenda E Porter
- Division of Child Neurology, Department of Neurology, Stanford University School of Medicine, CA, USA
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Snoeijen-Schouwenaars FM, van Ool JS, Verhoeven JS, van Mierlo P, Braakman HMH, Smeets EE, Nicolai J, Schoots J, Teunissen MWA, Rouhl RPW, Tan IY, Yntema HG, Brunner HG, Pfundt R, Stegmann AP, Kamsteeg EJ, Schelhaas HJ, Willemsen MH. Diagnostic exome sequencing in 100 consecutive patients with both epilepsy and intellectual disability. Epilepsia 2018; 60:155-164. [DOI: 10.1111/epi.14618] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 11/13/2018] [Accepted: 11/13/2018] [Indexed: 12/11/2022]
Affiliation(s)
| | - Jans S. van Ool
- Department of Residential Care; Epilepsy Center Kempenhaeghe; Heeze The Netherlands
| | - Judith S. Verhoeven
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Heeze The Netherlands
| | - Petra van Mierlo
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Heeze The Netherlands
| | - Hilde M. H. Braakman
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Heeze The Netherlands
| | - Eric E. Smeets
- Department of Human Genetics; Maastricht University Medical Center; Maastricht The Netherlands
| | - Joost Nicolai
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Heeze The Netherlands
- Department of Neurology; Maastricht University Medical Center; Maastricht The Netherlands
| | - Jeroen Schoots
- Department of Human Genetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Mariel W. A. Teunissen
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Maastricht The Netherlands
| | - Rob P. W. Rouhl
- Department of Neurology; Maastricht University Medical Center; Maastricht The Netherlands
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Maastricht The Netherlands
- School for Mental Health and Neurosciences; Maastricht University; Maastricht The Netherlands
| | - In Y. Tan
- Department of Residential Care; Epilepsy Center Kempenhaeghe; Heeze The Netherlands
| | - Helger G. Yntema
- Department of Human Genetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Han G. Brunner
- Department of Human Genetics; Maastricht University Medical Center; Maastricht The Netherlands
- Department of Human Genetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Rolph Pfundt
- Department of Human Genetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Alexander P. Stegmann
- Department of Human Genetics; Maastricht University Medical Center; Maastricht The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Helenius J. Schelhaas
- Academic Center for Epileptology Kempenhaeghe/Maastricht University Medical Center; Heeze The Netherlands
| | - Marjolein H. Willemsen
- Department of Human Genetics; Maastricht University Medical Center; Maastricht The Netherlands
- Department of Human Genetics; Radboud University Medical Center; Nijmegen The Netherlands
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42
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Schlessinger A, Welch MA, van Vlijmen H, Korzekwa K, Swaan PW, Matsson P. Molecular Modeling of Drug-Transporter Interactions-An International Transporter Consortium Perspective. Clin Pharmacol Ther 2018; 104:818-835. [PMID: 29981151 PMCID: PMC6197929 DOI: 10.1002/cpt.1174] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/30/2018] [Indexed: 12/31/2022]
Abstract
Membrane transporters play diverse roles in the pharmacokinetics and pharmacodynamics of small-molecule drugs. Understanding the mechanisms of drug-transporter interactions at the molecular level is, therefore, essential for the design of drugs with optimal therapeutic effects. This white paper examines recent progress, applications, and challenges of molecular modeling of membrane transporters, including modeling techniques that are centered on the structures of transporter ligands, and those focusing on the structures of the transporters. The goals of this article are to illustrate current best practices and future opportunities in using molecular modeling techniques to understand and predict transporter-mediated effects on drug disposition and efficacy.Membrane transporters from the solute carrier (SLC) and ATP-binding cassette (ABC) superfamilies regulate the cellular uptake, efflux, and homeostasis of many essential nutrients and significantly impact the pharmacokinetics of drugs; further, they may provide targets for novel therapeutics as well as facilitate prodrug approaches. Because of their often broad substrate selectivity they are also implicated in many undesirable and sometimes life-threatening drug-drug interactions (DDIs).5,6.
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Affiliation(s)
- Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Matthew A. Welch
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD
| | - Herman van Vlijmen
- Computational Chemistry, Discovery Sciences, Janssen Research & Development, Beerse, Belgium
| | - Ken Korzekwa
- Department of Pharmaceutical Sciences, Temple University, Philadelphia, PA
| | - Peter W. Swaan
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD
| | - Pär Matsson
- Department of Pharmacy, Uppsala University, Sweden
,Address correspondence to: Pär Matsson, Department of Pharmacy, Uppsala University, Box 580, SE-75123 Uppsala, Sweden, Phone: +46-(0)18-471 46 30, Fax: +46-(0)18-471 42 23,
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Alhakeem A, Alshibani F, Tabarki B. Extending the use of stiripentol to SLC13A5-related epileptic encephalopathy. Brain Dev 2018; 40:827-829. [PMID: 29895383 DOI: 10.1016/j.braindev.2018.05.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/26/2018] [Indexed: 11/16/2022]
Abstract
INTRODUCTION SLC13A5-related epileptic encephalopathy is a recently described autosomal recessive disorder that is characterized by infantile epilepsy and developmental delay. Seizures are markedly drug resistant and often induced by fever; they mainly occur in clusters, sometimes evolving into status epilepticus. METHODS AND RESULTS We report the use of stiripentol as an adjunctive therapy in three siblings with drug-resistant SLC13A5-related epilepsy. The three patients showed remarkable improvement in the severity and frequency of seizures, status epilepticus, emergency department visits, and alertness. CONCLUSION These observations extend the use of stiripentol beyond the classical Dravet syndrome, and further studies on the use of this drug in drug-resistant epilepsy, mainly of genetic origin, are warranted.
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Affiliation(s)
- Afnan Alhakeem
- Divisions of Pediatric Neurology, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Faisal Alshibani
- Divisions of Pediatric Neurology, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Brahim Tabarki
- Divisions of Pediatric Neurology, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia.
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Analysis of naturally occurring mutations in the human uptake transporter NaCT important for bone and brain development and energy metabolism. Sci Rep 2018; 8:11330. [PMID: 30054523 PMCID: PMC6063891 DOI: 10.1038/s41598-018-29547-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/13/2018] [Indexed: 11/30/2022] Open
Abstract
The human uptake transporter NaCT is important for human brain development, brain function and energy metabolism and mediates the uptake of citrate and other intermediates of the tricarboxylic acid cycle from blood into neurons and hepatocytes. Mutations in the SLC13A5 gene encoding NaCT are associated with epileptic encephalopathy. To gain more insights into the transport mechanisms we analyzed the functional consequences of mutations in the SLC13A5 gene on NaCT-mediated transport function. Using HEK293 cells expressing wild-type and eight mutated NaCT proteins, we investigated the mRNA and protein amount as well as the protein localization of all NaCT variants. Furthermore, the impact on NaCT-mediated citrate uptake was measured. In addition, a structural model of the transport pore was generated to rationalize the consequences of the mutations on a structural basis. We demonstrated that all proteins were synthesized with an identical molecular weight as the wild-type transporter but several mutations (NaCTp.G219R, −p.G219E, −p.T227M, −p.L420P and −p.L488P) lead to a complete loss of NaCT-mediated citrate transport. This loss of transport activity can be explained on the basis of the developed structural model. This model may help in the further elucidation of the transport mechanism of this important uptake transporter.
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45
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Willmes DM, Kurzbach A, Henke C, Schumann T, Zahn G, Heifetz A, Jordan J, Helfand SL, Birkenfeld AL. The longevity gene INDY ( I 'm N ot D ead Y et) in metabolic control: Potential as pharmacological target. Pharmacol Ther 2018; 185:1-11. [DOI: 10.1016/j.pharmthera.2017.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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46
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Ogura J, Babu E, Miyauchi S, Ramachandran S, Nemeth E, Bhutia YD, Ganapathy V. Identification of a novel Na +-coupled Fe 3+-citrate transport system, distinct from mammalian INDY, for uptake of citrate in mammalian cells. Sci Rep 2018; 8:2519. [PMID: 29410496 PMCID: PMC5802838 DOI: 10.1038/s41598-018-20620-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/22/2018] [Indexed: 01/05/2023] Open
Abstract
NaCT is a Na+-coupled transporter for citrate expressed in hepatocytes and neurons. It is the mammalian ortholog of INDY (I’m Not Dead Yet), a transporter which modifies lifespan in Drosophila. Here we describe a hitherto unknown transport system for citrate in mammalian cells. When liver and mammary epithelial cells were pretreated with the iron supplement ferric ammonium citrate (FAC), uptake of citrate increased >10-fold. Iron chelators abrogated the stimulation of citrate uptake in FAC-treated cells. The iron exporter ferroportin had no role in this process. The stimulation of citrate uptake also occurred when Fe3+ was added during uptake without pretreatment. Similarly, uptake of Fe3+ was enhanced by citrate. The Fe3+-citrate uptake was coupled to Na+. This transport system was detectable in primary hepatocytes and neuronal cell lines. The functional features of this citrate transport system distinguish it from NaCT. Loss-of-function mutations in NaCT cause early-onset epilepsy and encephalopathy; the newly discovered Na+-coupled Fe3+-citrate transport system might offer a novel treatment strategy for these patients to deliver citrate into affected neurons independent of NaCT. It also has implications to iron-overload conditions where circulating free iron increases, which would stimulate cellular uptake of citrate and consequently affect multiple metabolic pathways.
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Affiliation(s)
- Jiro Ogura
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Ellappan Babu
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Seiji Miyauchi
- Department of Pharmaceutics, Toho University, Funabashi, Chiba, 274-8510, Japan
| | - Sabarish Ramachandran
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Elizebeta Nemeth
- Department of Medicine and Center for Iron Disorders, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Yangzom D Bhutia
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA.
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47
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Rogdi Defines GABAergic Control of a Wake-promoting Dopaminergic Pathway to Sustain Sleep in Drosophila. Sci Rep 2017; 7:11368. [PMID: 28900300 PMCID: PMC5595912 DOI: 10.1038/s41598-017-11941-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 09/01/2017] [Indexed: 12/12/2022] Open
Abstract
Kohlschutter-Tönz syndrome (KTS) is a rare genetic disorder with neurological dysfunctions including seizure and intellectual impairment. Mutations at the Rogdi locus have been linked to development of KTS, yet the underlying mechanisms remain elusive. Here we demonstrate that a Drosophila homolog of Rogdi acts as a novel sleep-promoting factor by supporting a specific subset of gamma-aminobutyric acid (GABA) transmission. Rogdi mutant flies displayed insomnia-like behaviors accompanied by sleep fragmentation and delay in sleep initiation. The sleep suppression phenotypes were rescued by sustaining GABAergic transmission primarily via metabotropic GABA receptors or by blocking wake-promoting dopaminergic pathways. Transgenic rescue further mapped GABAergic neurons as a cell-autonomous locus important for Rogdi-dependent sleep, implying metabotropic GABA transmission upstream of the dopaminergic inhibition of sleep. Consistently, an agonist specific to metabotropic but not ionotropic GABA receptors titrated the wake-promoting effects of dopaminergic neuron excitation. Taken together, these data provide the first genetic evidence that implicates Rogdi in sleep regulation via GABAergic control of dopaminergic signaling. Given the strong relevance of GABA to epilepsy, we propose that similar mechanisms might underlie the neural pathogenesis of Rogdi-associated KTS.
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48
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Colas C, Schlessinger A, Pajor AM. Mapping Functionally Important Residues in the Na +/Dicarboxylate Cotransporter, NaDC1. Biochemistry 2017; 56:4432-4441. [PMID: 28731330 DOI: 10.1021/acs.biochem.7b00503] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transporters from the SLC13 family couple the transport of two to four Na+ ions with a di- or tricarboxylate, such as succinate or citrate. We have previously modeled mammalian members of the SLC13 family, including the Na+/dicarboxylate cotransporter NaDC1 (SLC13A2), based on a structure of the bacterial homologue VcINDY in an inward-facing conformation with one sodium ion bound at the Na1 site. In the study presented here, we modeled the outward-facing conformation of rabbit and human NaDC1 (rbNaDC1 and hNaDC1, respectively) using an outward-facing model of VcINDY as a template and identified residues in or near the putative Na2 and Na3 cation binding sites. Guided by the structural models in both conformations, we performed site-directed mutagenesis in rbNaDC1 for residues proposed to be in the Na+ or substrate binding sites. Cysteine substitution of T474 in the predicted Na2 binding site results in an inactive protein. The M539C mutant has a low apparent affinity for both sodium and lithium cations, suggesting that M539 may form part of the putative Na3 binding site. The Y432C and T86C mutants have increased Km values for succinate, supporting their proposed location in the outward-facing substrate binding site. In addition, cysteine labeling by MTSEA-biotin shows that Y432C is accessible from the outside of the cell, and the accessibility changes in the presence or absence of Na+. The results of this study improve our understanding of substrate and ion recognition in the mammalian members of the SLC13 family and provide a framework for developing conformationally specific inhibitors against these transporters.
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Affiliation(s)
- Claire Colas
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Ana M Pajor
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego , La Jolla, California 92130-0714, United States
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Bainbridge MN, Cooney E, Miller M, Kennedy AD, Wulff JE, Donti T, Jhangiani SN, Gibbs RA, Elsea SH, Porter BE, Graham BH. Analyses of SLC13A5-epilepsy patients reveal perturbations of TCA cycle. Mol Genet Metab 2017; 121:314-319. [PMID: 28673551 PMCID: PMC7539367 DOI: 10.1016/j.ymgme.2017.06.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/20/2017] [Accepted: 06/21/2017] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To interrogate the metabolic profile of five subjects from three families with rare, nonsense and missense mutations in SLC13A5 and Early Infantile Epileptic Encephalopathies (EIEE) characterized by severe, neonatal onset seizures, psychomotor retardation and global developmental delay. METHODS Mass spectrometry of plasma, CSF and urine was used to identify consistently dysregulated analytes in our subjects. RESULTS Distinctive elevations of citrate and dysregulation of citric acid cycle intermediates, supporting the hypothesis that loss of SLC13A5 function alters tricarboxylic acid cycle (TCA) metabolism and may disrupt metabolic compartmentation in the brain. SIGNIFICANCE Our results indicate that analysis of plasma citrate and other TCA analytes in SLC13A5 deficient patients define a diagnostic metabolic signature that can aid in diagnosing children with this disease.
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Affiliation(s)
- Matthew N Bainbridge
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, United States; Codified Genomics LLC, Houston, TX, United States; Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, United States
| | - Erin Cooney
- Dept. of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Marcus Miller
- Dept. of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | | | | | - Taraka Donti
- Dept. of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Shalini N Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, United States
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, United States
| | - Sarah H Elsea
- Dept. of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Brenda E Porter
- Department of Neurology, Stanford University Medical School, Palo Alto, CA, United States
| | - Brett H Graham
- Dept. of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.
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50
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Rogina B. INDY-A New Link to Metabolic Regulation in Animals and Humans. Front Genet 2017; 8:66. [PMID: 28596784 PMCID: PMC5442177 DOI: 10.3389/fgene.2017.00066] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 05/09/2017] [Indexed: 12/02/2022] Open
Abstract
The Indy (I’m Not Dead Yet) gene encodes the fly homolog of the mammalian SLC13A5 citrate transporter. Reduced expression of the Indy gene in flies and worms extends their longevity. INDY is expressed in the plasma membrane of metabolically active tissues. Decreased expression of Indy in worms, flies, mice, and rats alters metabolism in a manner similar to calorie restriction. Reducing INDY activity prevents weight gain in flies, worms, and mice, and counteracts the negative effects of age or a high fat diet on metabolism and insulin sensitivity. The metabolic effects of reducing INDY activity are the result of reduced cytoplasmic citrate. Citrate is a key metabolite and has a central role in energy status of the cell by effecting lipid and carbohydrate metabolism and energy production. Thereby newly described drugs that reduce INDY transporting activity increase insulin sensitivity and reduce hepatic lipid levels via its effect on hepatic citrate uptake. A recent report presented the first direct link between increased hepatic levels of human INDY, insulin resistance, and non-alcoholic fatty liver disease in obese humans. Similarly increased hepatic mIndy levels were observed in non-human primates fed on a high fat diet for 2 years. This effect is mediated via the stimulatory effect of the interleukin-6/Stat3 pathway on mINDY hepatic expression. These findings make INDY a potential and very promising target for the treatment of metabolic disorders in humans.
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Affiliation(s)
- Blanka Rogina
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, School of Medicine, University of Connecticut Health Center, FarmingtonCT, United States
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