1
|
Pressler RM, Abend NS, Auvin S, Boylan G, Brigo F, Cilio MR, De Vries LS, Elia M, Espeche A, Hahn CD, Inder T, Jette N, Kakooza-Mwesige A, Mader S, Mizrahi EM, Moshé SL, Nagarajan L, Noyman I, Nunes ML, Samia P, Shany E, Shellhaas RA, Subota A, Triki CC, Tsuchida T, Vinayan KP, Wilmshurst JM, Yozawitz EG, Hartmann H. Treatment of seizures in the neonate: Guidelines and consensus-based recommendations-Special report from the ILAE Task Force on Neonatal Seizures. Epilepsia 2023; 64:2550-2570. [PMID: 37655702 DOI: 10.1111/epi.17745] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 09/02/2023]
Abstract
Seizures are common in neonates, but there is substantial management variability. The Neonatal Task Force of the International League Against Epilepsy (ILAE) developed evidence-based recommendations about antiseizure medication (ASM) management in neonates in accordance with ILAE standards. Six priority questions were formulated, a systematic literature review and meta-analysis were performed, and results were reported following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 standards. Bias was evaluated using the Cochrane tool and risk of Bias in non-randomised studies - of interventions (ROBINS-I), and quality of evidence was evaluated using grading of recommendations, assessment, development and evaluation (GRADE). If insufficient evidence was available, then expert opinion was sought using Delphi consensus methodology. The strength of recommendations was defined according to the ILAE Clinical Practice Guidelines development tool. There were six main recommendations. First, phenobarbital should be the first-line ASM (evidence-based recommendation) regardless of etiology (expert agreement), unless channelopathy is likely the cause for seizures (e.g., due to family history), in which case phenytoin or carbamazepine should be used. Second, among neonates with seizures not responding to first-line ASM, phenytoin, levetiracetam, midazolam, or lidocaine may be used as a second-line ASM (expert agreement). In neonates with cardiac disorders, levetiracetam may be the preferred second-line ASM (expert agreement). Third, following cessation of acute provoked seizures without evidence for neonatal-onset epilepsy, ASMs should be discontinued before discharge home, regardless of magnetic resonance imaging or electroencephalographic findings (expert agreement). Fourth, therapeutic hypothermia may reduce seizure burden in neonates with hypoxic-ischemic encephalopathy (evidence-based recommendation). Fifth, treating neonatal seizures (including electrographic-only seizures) to achieve a lower seizure burden may be associated with improved outcome (expert agreement). Sixth, a trial of pyridoxine may be attempted in neonates presenting with clinical features of vitamin B6-dependent epilepsy and seizures unresponsive to second-line ASM (expert agreement). Additional considerations include a standardized pathway for the management of neonatal seizures in each neonatal unit and informing parents/guardians about the diagnosis of seizures and initial treatment options.
Collapse
Affiliation(s)
- Ronit M Pressler
- Clinical Neuroscience, UCL-Great Ormond Street Institute of Child Health, London, UK
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Nicholas S Abend
- Departments of Neurology and Pediatrics, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stéphan Auvin
- Department Medico-Universitaire Innovation Robert-Debré, Robert Debré Hospital, Public Hospital Network of Paris, Pediatric Neurology, University of Paris, Paris, France
| | - Geraldine Boylan
- INFANT Research Centre, University College Cork, Cork, Ireland
- Department of Paediatrics and Child Health, University College Cork, Cork, Ireland
| | - Francesco Brigo
- Department of Neurology, Hospital of Merano (SABES-ASDAA), Merano, Italy
- Innovation Research and Teaching Service (SABES-ASDAA), Teaching Hospital of Paracelsus Medical Private University, Bolzano-Bozen, Italy
| | - Maria Roberta Cilio
- Division of Pediatric Neurology, Saint-Luc University Hospital, and Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Linda S De Vries
- Department of Neonatology, University Medical Center, Utrecht, the Netherlands
| | - Maurizio Elia
- Unit of Neurology and Clinical Neurophysiopathology, Oasi Research Institute-IRCCS, Troina, Italy
| | - Alberto Espeche
- Department of Neurology, Hospital Materno Infantil, Salta, Argentina
| | - Cecil D Hahn
- Department of Pediatrics, Division of Neurology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Terrie Inder
- Department of Pediatrics, Newborn Medicine, Children's Hospital of Orange County, University of California, Irvine, Irvine, California, USA
| | - Nathalie Jette
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Angelina Kakooza-Mwesige
- Department of Pediatrics and Child Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Silke Mader
- Scientific Affairs, European Foundation for the Care of Newborn Infants, Munich, Germany
| | - Eli M Mizrahi
- Departments of Neurology and Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Solomon L Moshé
- Isabelle Rapin Division of Child Neurology, Saul R. Korey Department of Neurology, Montefiore Medical Center, Bronx, New York, USA
- Departments of Neuroscience and Pediatrics, Albert Einstein College of Medicine, and Montefiore Medical Center, Bronx, New York, USA
| | - Lakshmi Nagarajan
- Children's Neuroscience Service, Department of Neurology, Perth Children's Hospital and University of Western Australia, Nedlands, Western Australia, Australia
| | - Iris Noyman
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Pediatric Neurology Unit, Pediatric Division, Soroka Medical Center, Beer-Sheva, Israel
| | - Magda L Nunes
- Pontifícia Universidade Católica do Rio Grande do Sul-PUCRS School of Medicine and the Brain Institute, Porto Alegre, Brazil
| | - Pauline Samia
- Departments of Pediatrics and Child Health, Aga Khan University, Nairobi, Kenya
- Department of Public Health and Primary Care, Ghent University, Ghent, Belgium
| | - Eilon Shany
- Department of Neonatology, Soroka Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Renée A Shellhaas
- Department of Neurology, Washington University, St. Louis, Missouri, USA
| | - Ann Subota
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Chahnez Charfi Triki
- Child Neurology Department, Hedi Chaker Hospital, Sfax Medical School, University of Sfax, Sfax, Tunisia
| | - Tammy Tsuchida
- Departments of Neurology and Pediatrics, Children's National Health System, George Washington University School of Medicine, Washington, District of Columbia, USA
| | | | - Jo M Wilmshurst
- Department of Paediatric Neurology, Red Cross War Memorial Children's Hospital, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Elissa G Yozawitz
- Isabelle Rapin Division of Child Neurology, Saul R. Korey Department of Neurology, Montefiore Medical Center, Bronx, New York, USA
| | - Hans Hartmann
- Clinic for Pediatric Kidney, Liver, and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| |
Collapse
|
2
|
Ciapaite J, van Roermund CWT, Bosma M, Gerrits J, Houten SM, IJlst L, Waterham HR, van Karnebeek CDM, Wanders RJA, Zwartkruis FJT, Jans JJ, Verhoeven-Duif NM. Maintenance of cellular vitamin B 6 levels and mitochondrial oxidative function depend on pyridoxal 5'-phosphate homeostasis protein. J Biol Chem 2023; 299:105047. [PMID: 37451483 PMCID: PMC10463200 DOI: 10.1016/j.jbc.2023.105047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/23/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023] Open
Abstract
Recently, biallelic variants in PLPBP coding for pyridoxal 5'-phosphate homeostasis protein (PLPHP) were identified as a novel cause of early-onset vitamin B6-dependent epilepsy. The molecular function and precise role of PLPHP in vitamin B6 metabolism are not well understood. To address these questions, we used PLPHP-deficient patient skin fibroblasts and HEK293 cells and YBL036C (PLPHP ortholog)-deficient yeast. We showed that independent of extracellular B6 vitamer type (pyridoxine, pyridoxamine, or pyridoxal), intracellular pyridoxal 5'-phosphate (PLP) was lower in PLPHP-deficient fibroblasts and HEK293 cells than controls. Culturing cells with pyridoxine or pyridoxamine led to the concentration-dependent accumulation of pyridoxine 5'-phosphate and pyridoxamine 5'-phosphate (PMP), respectively, suggesting insufficient pyridox(am)ine 5'-phosphate oxidase activity. Experiments utilizing 13C4-pyridoxine confirmed lower pyridox(am)ine 5'-phosphate oxidase activity and revealed increased fractional turnovers of PLP and pyridoxal, indicating increased PLP hydrolysis to pyridoxal in PLPHP-deficient cells. This effect could be partly counteracted by inactivation of pyridoxal phosphatase. PLPHP deficiency had a distinct effect on mitochondrial PLP and PMP, suggesting impaired activity of mitochondrial transaminases. Moreover, in YBL036C-deficient yeast, PLP was depleted and PMP accumulated only with carbon sources requiring mitochondrial metabolism. Lactate and pyruvate accumulation along with the decrease of tricarboxylic acid cycle intermediates downstream of α-ketoglutarate suggested impaired mitochondrial oxidative metabolism in PLPHP-deficient HEK293 cells. We hypothesize that impaired activity of mitochondrial transaminases may contribute to this depletion. Taken together, our study provides new insights into the pathomechanisms of PLPBP deficiency and reinforces the link between PLPHP function, vitamin B6 metabolism, and mitochondrial oxidative metabolism.
Collapse
Affiliation(s)
- Jolita Ciapaite
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands; United for Metabolic Diseases, The Netherlands.
| | - Carlo W T van Roermund
- United for Metabolic Diseases, The Netherlands; Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology & Metabolism, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, The Netherlands
| | - Marjolein Bosma
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands; United for Metabolic Diseases, The Netherlands
| | - Johan Gerrits
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands; United for Metabolic Diseases, The Netherlands
| | - Sander M Houten
- Department of Genetics and Genomic Sciences, Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Lodewijk IJlst
- United for Metabolic Diseases, The Netherlands; Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology & Metabolism, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, The Netherlands
| | - Hans R Waterham
- United for Metabolic Diseases, The Netherlands; Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology & Metabolism, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, The Netherlands
| | - Clara D M van Karnebeek
- United for Metabolic Diseases, The Netherlands; Departments of Pediatrics and Human Genetics, Emma Center for Personalized Medicine, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, The Netherlands; Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, BC Children's Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ronald J A Wanders
- United for Metabolic Diseases, The Netherlands; Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology & Metabolism, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, The Netherlands
| | - Fried J T Zwartkruis
- Department of Molecular Cancer Research, Center for Molecular Medicine, Oncode Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Judith J Jans
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands; United for Metabolic Diseases, The Netherlands
| | - Nanda M Verhoeven-Duif
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands; United for Metabolic Diseases, The Netherlands
| |
Collapse
|
3
|
Plecko B. On pathways and blind alleys-The importance of biomarkers in vitamin B 6 -dependent epilepsies. J Inherit Metab Dis 2023; 46:839-847. [PMID: 37428623 DOI: 10.1002/jimd.12655] [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: 05/29/2023] [Revised: 06/30/2023] [Accepted: 07/06/2023] [Indexed: 07/12/2023]
Abstract
Over the past two decades, the field of vitamin B6 -dependent epilepsies has evolved by the recognition of a growing number of gene defects (ALDH7A1, PNPO, ALPL, ALDH4A1, PLPBP as well as defects of the glycosylphosphatidylinositol anchor proteins) that all lead to reduced availability of pyridoxal 5'-phosphate, an important cofactor in neurotransmitter and amino acid metabolism. In addition, positive pyridoxine response has been observed in other monogenic defects such as MOCS2 deficiency or KCNQ2 and there may be more defects to be discovered. Most entities lead to neonatal onset pharmaco-resistant myoclonic seizures or even status epilepticus and pose an emergency to the treating physician. Research has unraveled specific biomarkers for several of these entities (PNPO deficiency, ALDH7A1 deficiency, ALDH4A1 deficiency, ALPL deficiency causing congenital hypophosphatasia and glycosylphosphatidylinositol anchoring defects with hyperphosphatasia), that can be detected in plasma or urine, while there is no biomarker to test for PLPHP deficiency. Secondary elevation of glycine or lactate was recognized as diagnostic pitfall. An algorithm for a standardized trial with vitamin B6 should be in place in every newborn unit in order not to miss these well-treatable inborn errors of metabolism. The Komrower lecture of 2022 provided me with the opportunity to tell the story about the conundrums of research into vitamin B6 -dependent epilepsies that kept some surprises and many novel insights into pathomechanisms of vitamin metabolism. Every single step had benefits for the patients and families that we care for and advocates for a close collaboration of clinician scientists with basic research.
Collapse
Affiliation(s)
- Barbara Plecko
- Division of General Pediatrics, Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Graz, Austria
| |
Collapse
|
4
|
Fiedler MK, Drechsel J, Schmidt R, Luppa PB, Bach NC, Sieber SA. Rapid Diagnostic Platform for Personalized Vitamin B6 Detection in Erythrocytes via PLP Cofactor Mimics. ACS Chem Biol 2023. [PMID: 37406307 DOI: 10.1021/acschembio.3c00279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Abstract
Personalized assessment of vitamin levels in point-of-care (POC) devices is urgently needed to advance the recognition of diseases associated with malnutrition and unbalanced diets. We here introduce a diagnostic platform, which showcases an easy and rapid readout of vitamin B6 (pyridoxal phosphate, PLP) levels in erythrocytes as a first step toward a home-use POC. The technology is based on fluorescent probes, which bind to PLP-dependent enzymes (PLP-DEs) and thereby indirectly report their occupancy with endogenous B6. For example, low vitamin levels result in high probe binding, yielding a strong signal and vice versa. Antibodies against signature human PLP-DEs were immobilized on microarrays to capture probe labeled enzymes for fluorescent detection. Calibrating the system with defined B6 levels revealed a concentration-depended readout as well as sufficient sensitivity for its detection in erythrocytes. To account for individual differences in protein expression, a second antibody was used to normalize protein abundance. This sandwiched assay correctly reported relative B6 levels in human erythrocyte samples, as confirmed by classical laboratory diagnostics. In principle, the platform layout can be easily expanded to other crucial vitamins beyond B6 via an analogous probe strategy.
Collapse
Affiliation(s)
- Michaela K Fiedler
- TUM School of Natural Sciences, Department Biosciences, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Technical University Munich (TUM), Ernst-Otto-Fischer Str. 8, Garching 85748, Germany
| | - Jonas Drechsel
- TUM School of Natural Sciences, Department Biosciences, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Technical University Munich (TUM), Ernst-Otto-Fischer Str. 8, Garching 85748, Germany
- Evotec München, Anna-Sigmund-Str. 5, Neuried 82061, Germany
| | - Ronny Schmidt
- Sciomics GmbH, Karl-Landsteiner-Straße 6, Neckargemünd bei Heidelberg 69151, Germany
| | - Peter B Luppa
- Klinikum rechts der Isar (MRI), Institute of Clinical Chemistry and Pathobiochemistry, Technical University Munich (TUM), Ismaninger Str. 22, Munich 81675, Germany
| | - Nina C Bach
- TUM School of Natural Sciences, Department Biosciences, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Technical University Munich (TUM), Ernst-Otto-Fischer Str. 8, Garching 85748, Germany
| | - Stephan A Sieber
- TUM School of Natural Sciences, Department Biosciences, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Technical University Munich (TUM), Ernst-Otto-Fischer Str. 8, Garching 85748, Germany
| |
Collapse
|
5
|
Turck D, Bohn T, Castenmiller J, de Henauw S, Hirsch‐Ernst K, Knutsen HK, Maciuk A, Mangelsdorf I, McArdle HJ, Pelaez C, Pentieva K, Siani A, Thies F, Tsabouri S, Vinceti M, Fairweather‐Tait S, Vrolijk M, Fabiani L, Titz A, Naska A. Scientific opinion on the tolerable upper intake level for vitamin B6. EFSA J 2023; 21:e08006. [PMID: 37207271 PMCID: PMC10189633 DOI: 10.2903/j.efsa.2023.8006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023] Open
Abstract
Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for vitamin B6. Systematic reviews of the literature were conducted by a contractor. The relationship between excess vitamin B6 intakes and the development of peripheral neuropathy is well established and is the critical effect on which the UL is based. A lowest-observed-effect-level (LOAEL) could not be established based on human data. A reference point (RP) of 50 mg/day is identified by the Panel from a case-control study, supported by data from case reports and vigilance data. An uncertainty factor (UF) of 4 is applied to the RP to account for the inverse relationship between dose and time to onset of symptoms and the limited data available. The latter covers uncertainties as to the level of intake that would represent a LOAEL. This leads to a UL of 12.5 mg/day. From a subchronic study in Beagle dogs, a LOAEL of 50 mg/kg body weight (bw) per day can be identified. Using an UF of 300, and a default bw of 70 kg, a UL of 11.7 mg/day can be calculated. From the midpoint of the range of these two ULs and rounding down, a UL of 12 mg/day is established by the Panel for vitamin B6 for adults (including pregnant and lactating women). ULs for infants and children are derived from the UL for adults using allometric scaling: 2.2-2.5 mg/day (4-11 months), 3.2-4.5 mg/day (1-6 years), 6.1-10.7 mg/day (7-17 years). Based on available intake data, EU populations are unlikely to exceed ULs, except for regular users of food supplements containing high doses of vitamin B6.
Collapse
|
6
|
Llop A, Labella JI, Borisova M, Forchhammer K, Selim KA, Contreras A. Pleiotropic effects of PipX, PipY, or RelQ overexpression on growth, cell size, photosynthesis, and polyphosphate accumulation in the cyanobacterium Synechococcus elongatus PCC7942. Front Microbiol 2023; 14:1141775. [PMID: 37007489 PMCID: PMC10060972 DOI: 10.3389/fmicb.2023.1141775] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 02/23/2023] [Indexed: 03/18/2023] Open
Abstract
The cyanobacterial protein PipY belongs to the Pyridoxal-phosphate (PLP)-binding proteins (PLPBP/COG0325) family of pyridoxal-phosphate-binding proteins, which are represented in all three domains of life. These proteins share a high degree of sequence conservation, appear to have purely regulatory functions, and are involved in the homeostasis of vitamin B6 vitamers and amino/keto acids. Intriguingly, the genomic context of the pipY gene in cyanobacteria connects PipY with PipX, a protein involved in signaling the intracellular energy status and carbon-to-nitrogen balance. PipX regulates its cellular targets via protein–protein interactions. These targets include the PII signaling protein, the ribosome assembly GTPase EngA, and the transcriptional regulators NtcA and PlmA. PipX is thus involved in the transmission of multiple signals that are relevant for metabolic homeostasis and stress responses in cyanobacteria, but the exact function of PipY is still elusive. Preliminary data indicated that PipY might also be involved in signaling pathways related to the stringent stress response, a pathway that can be induced in the unicellular cyanobacterium Synechococcus elongatus PCC7942 by overexpression of the (p)ppGpp synthase, RelQ. To get insights into the cellular functions of PipY, we performed a comparative study of PipX, PipY, or RelQ overexpression in S. elongatus PCC7942. Overexpression of PipY or RelQ caused similar phenotypic responses, such as growth arrest, loss of photosynthetic activity and viability, increased cell size, and accumulation of large polyphosphate granules. In contrast, PipX overexpression decreased cell length, indicating that PipX and PipY play antagonistic roles on cell elongation or cell division. Since ppGpp levels were not induced by overexpression of PipY or PipX, it is apparent that the production of polyphosphate in cyanobacteria does not require induction of the stringent response.
Collapse
Affiliation(s)
- Antonio Llop
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain
- Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions Department, Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Tübingen, Germany
| | - Jose I. Labella
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain
| | - Marina Borisova
- Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions Department, Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Tübingen, Germany
| | - Karl Forchhammer
- Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions Department, Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Tübingen, Germany
| | - Khaled A. Selim
- Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions Department, Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Tübingen, Germany
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain
- *Correspondence: Asunción Contreras,
| |
Collapse
|
7
|
Mastrangelo M, Gasparri V, Bernardi K, Foglietta S, Ramantani G, Pisani F. Epilepsy Phenotypes of Vitamin B6-Dependent Diseases: An Updated Systematic Review. CHILDREN 2023; 10:children10030553. [PMID: 36980111 PMCID: PMC10047402 DOI: 10.3390/children10030553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/12/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
Background: Vitamin B6-dependent epilepsies include treatable diseases responding to pyridoxine or pyridoxal-5Iphosphate (ALDH7A1 deficiency, PNPO deficiency, PLP binding protein deficiency, hyperprolinemia type II and hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects). Patients and methods: We conducted a systematic review of published pediatric cases with a confirmed molecular genetic diagnosis of vitamin B6-dependent epilepsy according to PRISMA guidelines. Data on demographic features, seizure semiology, EEG patterns, neuroimaging, treatment, and developmental outcomes were collected. Results: 497 published patients fulfilled the inclusion criteria. Seizure onset manifested at 59.8 ± 291.6 days (67.8% of cases in the first month of life). Clonic, tonic-clonic, and myoclonic seizures accounted for two-thirds of the cases, while epileptic spasms were observed in 7.6%. Burst-suppression/suppression-burst represented the most frequently reported specific EEG pattern (14.4%), mainly in PLPB, ALDH7A1, and PNPO deficiency. Pyridoxine was administered to 312 patients (18.5% intravenously, 76.9% orally, 4.6% not specified), and 180 also received antiseizure medications. Pyridoxine dosage ranged between 1 and 55 mg/kg/die. Complete seizure freedom was achieved in 160 patients, while a significant seizure reduction occurred in 38. PLP, lysine-restricted diet, and arginine supplementation were used in a small proportion of patients with variable efficacy. Global developmental delay was established in 30.5% of a few patients in whom neurocognitive tests were performed. Conclusions: Despite the wide variability, the most frequent hallmarks of the epilepsy phenotype in patients with vitamin B6-dependent seizures include generalized or focal motor seizure semiology and a burst suppression/suppression burst pattern in EEG.
Collapse
Affiliation(s)
- Mario Mastrangelo
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
- Department of Neuroscience/Mental Health, Azienda Ospedaliero-Universitaria Policlinico Umberto I, 00161 Rome, Italy
- Correspondence:
| | - Valentina Gasparri
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Katerina Bernardi
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Silvia Foglietta
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Georgia Ramantani
- Department of Neuropediatrics, University Children’s Hospital Zurich and University of Zurich, 8032 Zurich, Switzerland
| | - Francesco Pisani
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
- Department of Neuroscience/Mental Health, Azienda Ospedaliero-Universitaria Policlinico Umberto I, 00161 Rome, Italy
| |
Collapse
|
8
|
Liu Z, Wang L, Gao S, Xue Q, Tan F, Li Z, Gao Y. Plasma metabolomics study in screening and differential diagnosis of multiple primary lung cancer. Int J Surg 2023; 109:297-312. [PMID: 36928390 PMCID: PMC10389222 DOI: 10.1097/js9.0000000000000006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 11/28/2022] [Indexed: 03/18/2023]
Abstract
BACKGROUND Multiple primary lung cancer (MPLC) is becoming increasingly common in clinical practice. Imaging examination is sometimes difficult to differentiate from intrapulmonary metastasis (IM) or single primary lung cancer (SPLC) before surgery. There is a lack of effective blood biomarkers as an auxiliary diagnostic method. PARTICIPANTS AND METHODS A total of 179 patients who were hospitalized and operated in our department from January to June 2019 were collected, and they were divided into SPLC with 136 patients, MPLC with 24 patients, and IM with 19 patients. In total, 96 healthy people without lung cancer were enrolled. Medical history, imaging, and pathology data were assembled from all participants. Plasma metabolomics analysis was performed by quadrupole time-of-flight tandem mass spectrometry, and data were analyzed using SPSS19.0/Simca 14.1/MetaboAnalyst5.0 software. Significant metabolites were selected by variable importance in projection, P value, and fold change. The area under the receiver operating characteristic curve was used to evaluate their diagnostic ability. RESULTS There were significant differences in plasma metabolite profiles between IM and MPLC. Seven metabolites were screened out. Two metabolites had higher levels in IM, and five metabolites had higher levels in MPLC. All had favorable discriminating capacity. Phosphatidyl ethanolamine (38:5) showed the highest sensitivity (0.95) and specificity (0.92). It was followed by l -histidine with sensitivity 0.92 and specificity 0.84. l -tyrosine can be used to identify SPLC and MPLC. The panel composed of related metabolites exhibited higher diagnostic ability. Eight principal metabolites caused remarkable differences between healthy people and MPLC, and five of them had area under the curves greater than 0.85, showing good discriminating power. CONCLUSION Through the study of plasma metabolomics, it was found that there were obvious differences in the metabolite profiles of MPLC, IM, SPLC, and the healthy population. Some discovered metabolites possessed excellent diagnostic competence with high sensitivity and specificity. They had the potential to act as biomarkers for the screening and differential diagnosis of MPLCs.
Collapse
Affiliation(s)
- Zixu Liu
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Hebei Cancer Hospital, Langfang, People’s Republic of China
| | - Ling Wang
- Department of Hematology, Beijing Chuiyangliu Hospital, Beijing
| | - Shugeng Gao
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College
| | - Qi Xue
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College
| | - Fengwei Tan
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College
| | - Zhili Li
- Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College
| | - Yushun Gao
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Hebei Cancer Hospital, Langfang, People’s Republic of China
| |
Collapse
|
9
|
Cruz Marino T, Leblanc J, Pratte A, Tardif J, Thomas MJ, Fortin CA, Girard L, Bouchard L. Portrait of autosomal recessive diseases in the French-Canadian founder population of Saguenay-Lac-Saint-Jean. Am J Med Genet A 2023; 191:1145-1163. [PMID: 36786328 DOI: 10.1002/ajmg.a.63147] [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: 09/28/2022] [Revised: 01/16/2023] [Accepted: 01/30/2023] [Indexed: 02/15/2023]
Abstract
The population of the Saguenay-Lac-Saint-Jean (SLSJ) region, located in the province of Quebec, Canada, is recognized as a founder population, where some rare autosomal recessive diseases show a high prevalence. Through the clinical and molecular study of 82 affected individuals from 60 families, this study outlines 12 diseases identified as recurrent in SLSJ. Their carrier frequency was estimated with the contribution of 1059 healthy individuals, increasing the number of autosomal recessive diseases with known carrier frequency in this region from 14 to 25. We review the main clinical and molecular features previously reported for these disorders. Five of the studied diseases have a potential lethal effect and three are associated with intellectual deficiency. Therefore, we believe that the provincial program for carrier screening should be extended to include these eight disorders. The high-carrier frequency, together with the absence of consanguinity in most of these unrelated families, suggest a founder effect and genetic drift for the 12 recurrent variants. We recommend further studies to validate this hypothesis, as well as to extend the present study to other regions in the province of Quebec, since some of these disorders could also be present in other French-Canadian families.
Collapse
Affiliation(s)
- Tania Cruz Marino
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | - Josianne Leblanc
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | - Annabelle Pratte
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | - Jessica Tardif
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | | | - Carol-Ann Fortin
- Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences (FMHS), Université de Sherbrooke, Quebec, Canada
| | - Lysanne Girard
- Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences (FMHS), Université de Sherbrooke, Quebec, Canada
| | - Luigi Bouchard
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada.,Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences (FMHS), Université de Sherbrooke, Quebec, Canada
| |
Collapse
|
10
|
Obeid R, Möller C, Geisel J. Circulating pyridoxal 5′-phosphate in serum and whole blood: implications for assessment of vitamin B6 status. J LAB MED 2023. [DOI: 10.1515/labmed-2022-0081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Abstract
Objectives
Concentrations of pyridoxal 5′-phosphate (PLP) in serum and whole blood are routinely measured. The suitability of these markers in capturing vitamin B6 insufficiency is not well studied.
Methods
In 212 subjects, concentrations of PLP and thiamine pyrophosphate (TPP) were simultaneously measured in EDTA-whole blood using Chromsystems® (52052) method on HPLC devices. The whole blood PLP concentrations were compared to serum PLP concentrations measured using reagents from Immundiagnostik® (KC 2100). The whole blood TPP concentrations measured with the Chromsystems® (52052) were compared to those measured by the Chromsystems® (35000) method. Concentrations of homocysteine (tHcy) and cystathionine (Cys) were measured and used to judge the PLP methods.
Results
Serum PLP concentrations were on average 41% lower than whole blood PLP [mean (SD)=55.4 (83.0) vs. 131 (217) nmol/L]. Serum and whole blood PLP showed a strong correlation [Pearson correlation coefficient=0.724, p<0.001, n=204]. Eighty-five samples showed discrepant results for PLP status (serum PLP ≤30 nmol/L, but whole blood PLP >51 nmol/L) while 102 samples showed coherent results (reference group). The discrepancy group showed higher odds ratio for elevated tHcy >12.0 μmol/L compared to the reference group [OR (95% confidence intervals, CI)=2.1 (1.2–4.0)]. The OR (95% CI) of elevated Cys >300 nmol/L was 1.9 (1.0–3.5) in the discrepancy group compared to the reference group. TPP concentrations were 6% lower when using the Chromsystems®, 52052 compared to levels measured with Chromsystems®, 35000.
Conclusions
Serum and whole blood PLP concentrations disagree in a substantial number of samples. Serum PLP was better in reflecting elevated tHcy and Cys compared to whole blood PLP. Whole blood PLP underestimates the prevalence of vitamin B6 insufficiency. Methods of measuring TPP concentrations in whole blood were exchangeable.
Collapse
Affiliation(s)
- Rima Obeid
- Department of Clinical Chemistry and Laboratory Medicine , Saarland University Hospital , Homburg/Saar , Germany
| | - Christoph Möller
- Department of Clinical Chemistry and Laboratory Medicine , Saarland University Hospital , Homburg/Saar , Germany
| | - Jürgen Geisel
- Department of Clinical Chemistry and Laboratory Medicine , Saarland University Hospital , Homburg/Saar , Germany
| |
Collapse
|
11
|
Denise R, Babor J, Gerlt JA, de Crécy-Lagard V. Pyridoxal 5'-phosphate synthesis and salvage in Bacteria and Archaea: predicting pathway variant distributions and holes. Microb Genom 2023; 9:mgen000926. [PMID: 36729913 PMCID: PMC9997740 DOI: 10.1099/mgen.0.000926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Pyridoxal 5’-phosphate or PLP is a cofactor derived from B6 vitamers and essential for growth in all known organisms. PLP synthesis and salvage pathways are well characterized in a few model species even though key components, such as the vitamin B6 transporters, are still to be identified in many organisms including the model bacteria Escherichia coli or Bacillus subtilis. Using a comparative genomic approach, PLP synthesis and salvage pathways were predicted in 5840 bacterial and archaeal species with complete genomes. The distribution of the two known de novo biosynthesis pathways and previously identified cases of non-orthologous displacements were surveyed in the process. This analysis revealed that several PLP de novo pathway genes remain to be identified in many organisms, either because sequence similarity alone cannot be used to discriminate among several homologous candidates or due to non-orthologous displacements. Candidates for some of these pathway holes were identified using published TnSeq data, but many remain. We find that ~10 % of the analysed organisms rely on salvage but further analyses will be required to identify potential transporters. This work is a starting point to model the exchanges of B6 vitamers in communities, predict the sensitivity of a given organism to drugs targeting PLP synthesis enzymes, and identify numerous gaps in knowledge that will need to be tackled in the years to come.
Collapse
Affiliation(s)
- Rémi Denise
- Department of Microbiology and Cell Sciences, Gainesville, USA.,Present address: APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Jill Babor
- Department of Microbiology and Cell Sciences, Gainesville, USA
| | | | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Sciences, Gainesville, USA.,Genetics Institute, University of Florida, Gainesville, FL 32611, USA
| |
Collapse
|
12
|
İpek R, Çavdartepe BE, Kor D, Okuyaz Ç. Pyridoxine-dependent Epilepsy caused by a Novel homozygous mutation in PLPBP Gene. Metab Brain Dis 2022; 37:3027-3032. [PMID: 36308585 DOI: 10.1007/s11011-022-01085-3] [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: 02/18/2022] [Accepted: 09/13/2022] [Indexed: 10/31/2022]
Abstract
Seizures in newborn infants may be the first finding of hereditary metabolic diseases. Pyridoxine-dependent epilepsy (PDE) is a treatable disorder associated with defects in the one of ALDH7A1, PNPO, or PLPBP genes and it is uncommon but progresses with persistent seizures in the neonatal and infancy period. The seizures are generally resistant to traditional antiepileptic drugs and show a dramatic response to high-dose pyridoxine. In 2016, mutations were reported in PLPBP (previously known as PROSC) gene, which encodes pyridoxal phosphate homeostatic protein (PLPHP).When early-onset antiepileptic resistant seizures are not treated, clinical findings emerge including the development of encephalopathy, congenital microcephaly, and subsequent retardation of psychomotor development. The present case is a 33-month-old female infant with seizures starting from postnatal day 1, who did not respond to traditional anti-epileptic drugs but responded to pyridoxine treatment. In the genetic tests, homozygote c.695 C > T (p.Ala232Val) mutation was determined in the PLPBP gene, which has not been previously identified. Since a specific treatment was found, this case is reported with the aim of emphasizing the need to consider pyridoxine dependence, which is one of the vitamin-dependent metabolic encephalopathies, in the differential diagnosis of epilepsy patients.
Collapse
Affiliation(s)
- Rojan İpek
- Department of Pediatric Neurology, Adıyaman Training and Research Hospital, Adıyaman, Turkey.
| | - Büşra Eser Çavdartepe
- Department of Pediatric Neurology, Adıyaman Training and Research Hospital, Adıyaman, Turkey
| | - Deniz Kor
- Department of Child Nutrition and Metabolism Diseases, Çukurova University, Adana, Turkey
| | - Çetin Okuyaz
- Department of Pediatric Neurology, Mersin University, Mersin, Turkey
| |
Collapse
|
13
|
Tramonti A, Ghatge MS, Babor JT, Musayev FN, di Salvo ML, Barile A, Colotti G, Giorgi A, Paredes SD, Donkor AK, Al Mughram MH, de Crécy‐Lagard V, Safo MK, Contestabile R. Characterization of the Escherichia coli pyridoxal 5'-phosphate homeostasis protein (YggS): Role of lysine residues in PLP binding and protein stability. Protein Sci 2022; 31:e4471. [PMID: 36218140 PMCID: PMC9601805 DOI: 10.1002/pro.4471] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/04/2022] [Accepted: 07/25/2022] [Indexed: 02/04/2023]
Abstract
The pyridoxal 5'-phosphate (PLP) homeostasis protein (PLPHP) is a ubiquitous member of the COG0325 family with apparently no catalytic activity. Although the actual cellular role of this protein is unknown, it has been observed that mutations of the PLPHP encoding gene affect the activity of PLP-dependent enzymes, B6 vitamers and amino acid levels. Here we report a detailed characterization of the Escherichia coli ortholog of PLPHP (YggS) with respect to its PLP binding and transfer properties, stability, and structure. YggS binds PLP very tightly and is able to slowly transfer it to a model PLP-dependent enzyme, serine hydroxymethyltransferase. PLP binding to YggS elicits a conformational/flexibility change in the protein structure that is detectable in solution but not in crystals. We serendipitously discovered that the K36A variant of YggS, affecting the lysine residue that binds PLP at the active site, is able to bind PLP covalently. This observation led us to recognize that a number of lysine residues, located at the entrance of the active site, can replace Lys36 in its PLP binding role. These lysines form a cluster of charged residues that affect protein stability and conformation, playing an important role in PLP binding and possibly in YggS function.
Collapse
Affiliation(s)
- Angela Tramonti
- Istituto di Biologia e Patologia MolecolariConsiglio Nazionale delle RicercheRomeItaly
- Istituto Pasteur Italia‐Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”Sapienza Università di RomaRomeItaly
| | - Mohini S. Ghatge
- Institute for Structural Biology, Drug Discovery and Development, Department of Medicinal ChemistryVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Jill T. Babor
- Department of Microbiology and Cell ScienceUniversity of FloridaGainsvilleFloridaUSA
| | - Faik N. Musayev
- Institute for Structural Biology, Drug Discovery and Development, Department of Medicinal ChemistryVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Martino Luigi di Salvo
- Istituto Pasteur Italia‐Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”Sapienza Università di RomaRomeItaly
| | - Anna Barile
- Istituto di Biologia e Patologia MolecolariConsiglio Nazionale delle RicercheRomeItaly
- Istituto Pasteur Italia‐Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”Sapienza Università di RomaRomeItaly
| | - Gianni Colotti
- Istituto di Biologia e Patologia MolecolariConsiglio Nazionale delle RicercheRomeItaly
| | - Alessandra Giorgi
- Istituto Pasteur Italia‐Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”Sapienza Università di RomaRomeItaly
| | - Steven D. Paredes
- Institute for Structural Biology, Drug Discovery and Development, Department of Medicinal ChemistryVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Akua K. Donkor
- Institute for Structural Biology, Drug Discovery and Development, Department of Medicinal ChemistryVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Mohammed H. Al Mughram
- Institute for Structural Biology, Drug Discovery and Development, Department of Medicinal ChemistryVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Valérie de Crécy‐Lagard
- Department of Microbiology and Cell ScienceUniversity of FloridaGainsvilleFloridaUSA
- Genetics InstituteUniversity of FloridaGainesvilleFloridaUSA
| | - Martin K. Safo
- Institute for Structural Biology, Drug Discovery and Development, Department of Medicinal ChemistryVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Roberto Contestabile
- Istituto Pasteur Italia‐Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”Sapienza Università di RomaRomeItaly
| |
Collapse
|
14
|
Alsubhi S, Osterman B, Chrestian N, Dubeau F, Buhas D, Srour M. Case report: PLPHP deficiency, a rare but important cause of B6-responsive disorders: A report of three novel individuals and review of 51 cases. Front Neurol 2022; 13:913652. [PMID: 36324377 PMCID: PMC9618642 DOI: 10.3389/fneur.2022.913652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022] Open
Abstract
PLPHP (pyridoxal-phosphate homeostasis protein) deficiency is caused by biallelic pathogenic variants in PLPBP and is a rare cause of pyridoxine-responsive disorders. We describe three French-Canadian individuals with PLPHP deficiency, including one with unusual paroxysmal episodes lacking EEG correlation with a suspicious movement disorder, rarely reported in B6RDs. In addition, we review the clinical features and treatment responses of all 51 previously published individuals with PLPHP deficiency. Our case series underlines the importance of considering PLPBP mutations in individuals with partially B6-responsive seizures and highlights the presence of a founder effect in the French-Canadian population.
Collapse
Affiliation(s)
- Sarah Alsubhi
- Division of Pediatric Neurology, Department of Pediatrics, McGill University, Montreal, QC, Canada
| | - Bradley Osterman
- Division of Pediatric Neurology, Department of Pediatrics, McGill University, Montreal, QC, Canada
| | - Nicolas Chrestian
- Department of Pediatric Neurology, Pediatric Neuromuscular Disorder, Centre Mère Enfant Soleil, Laval University, Quebec City, QC, Canada
| | - François Dubeau
- Department of Neurology and Neurosurgery McGill University, Montreal, QC, Canada
| | - Daniela Buhas
- Division of Medical Genetics, Department of Specialized Medicine, McGill University Health Center, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Myriam Srour
- Division of Pediatric Neurology, Department of Pediatrics, McGill University, Montreal, QC, Canada
- Department of Neurology and Neurosurgery McGill University, Montreal, QC, Canada
- Child Health and Human Development Program (CHHD), McGill University Health Center Research Institute, Montreal, QC, Canada
- *Correspondence: Myriam Srour
| |
Collapse
|
15
|
The Conserved Family of the Pyridoxal Phosphate-Binding Protein (PLPBP) and Its Cyanobacterial Paradigm PipY. Life (Basel) 2022; 12:life12101622. [PMID: 36295057 PMCID: PMC9605639 DOI: 10.3390/life12101622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/05/2022] [Accepted: 10/15/2022] [Indexed: 11/16/2022] Open
Abstract
The PLPBP family of pyridoxal phosphate-binding proteins has a high degree of sequence conservation and is represented in all three domains of life. PLPBP members, of which a few representatives have been studied in different contexts, are single-domain proteins with no known enzymatic activity that exhibit the fold type III of PLP-holoenzymes, consisting in an α/β barrel (TIM-barrel), where the PLP cofactor is solvent-exposed. Despite the constant presence of cofactor PLP (a key catalytic element in PLP enzymes), PLPBP family members appear to have purely regulatory functions affecting the homeostasis of vitamin B6 vitamers and amino/keto acids. Perturbation of these metabolites and pleiotropic phenotypes have been reported in bacteria and zebrafish after PLPBP gene inactivation as well as in patients with vitamin B6-dependent epilepsy that results from loss-of-function mutations at the PLPBP. Here, we review information gathered from diverse studies and biological systems, emphasizing the structural and functional conservation of the PLPBP members and discussing the informative nature of model systems and experimental approaches. In this context, the relatively high level of structural and functional characterization of PipY from Synechococcus elongatus PCC 7942 provides a unique opportunity to investigate the PLPBP roles in the context of a signaling pathway conserved in cyanobacteria.
Collapse
|
16
|
Krey I, Platzer K, Esterhuizen A, Berkovic SF, Helbig I, Hildebrand MS, Lerche H, Lowenstein D, Møller RS, Poduri A, Sadleir L, Sisodiya SM, Weckhuysen S, Wilmshurst JM, Weber Y, Lemke JR. Current practice in diagnostic genetic testing of the epilepsies. Epileptic Disord 2022; 24:765-786. [PMID: 35830287 PMCID: PMC10752379 DOI: 10.1684/epd.2022.1448] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/10/2022] [Indexed: 01/19/2023]
Abstract
Epilepsy genetics is a rapidly developing field, in which novel disease-associated genes, novel mechanisms associated with epilepsy, and precision medicine approaches are continuously being identified. In the past decade, advances in genomic knowledge and analysis platforms have begun to make clinical genetic testing accessible for, in principle, people of all ages with epilepsy. For this reason, the Genetics Commission of the International League Against Epilepsy (ILAE) presents this update on clinical genetic testing practice, including current techniques, indications, yield of genetic testing, recommendations for pre- and post-test counseling, and follow-up after genetic testing is completed. We acknowledge that the resources vary across different settings but highlight that genetic diagnostic testing for epilepsy should be prioritized when the likelihood of an informative finding is high. Results of genetic testing, in particular the identification of causative genetic variants, are likely to improve individual care. We emphasize the importance of genetic testing for individuals with epilepsy as we enter the era of precision therapy.
Collapse
Affiliation(s)
- Ilona Krey
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Alina Esterhuizen
- Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
| | - Samuel F. Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne (Austin Health), Heidelberg, VIC, Australia
| | - Ingo Helbig
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian-Albrechts-University, Building C, Arnold-Heller-Straße 3, 24105 Kiel, Germany
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children’s Hospital of Philadelphia, Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104 USA
| | - Michael S. Hildebrand
- Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, Heidelberg and Murdoch Children’s Research Institute, Royal Children’s Hospital, Victoria, Australia
| | - Holger Lerche
- Department of Epileptology and Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
| | - Daniel Lowenstein
- Department of Neurology, University of California, San Francisco, USA
| | - Rikke S. Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Lynette Sadleir
- Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand
| | - Sanjay M. Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology London, UK and Chalfont Centre for Epilepsy, Buckinghamshire, UK
| | - Sarah Weckhuysen
- Center for Molecular Neurology, VIB-University of Antwerp, VIB, Antwerp, Belgium; Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Jo M. Wilmshurst
- Department of Paediatric Neurology, Paediatric and Child Health, Red Cross War Memorial Children’s Hospital, Neuroscience Institute, University of Cape Town, South Africa
| | - Yvonne Weber
- Department of Epileptology and Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
- Department of Epileptology and Neurology, University of Aachen, Germany
| | - Johannes R. Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
| |
Collapse
|
17
|
Ge L, Luo J, Zhang L, Kang X, Zhang D. Association of Pyridoxal 5′-Phosphate with Sleep-Related Problems in a General Population. Nutrients 2022; 14:nu14173516. [PMID: 36079774 PMCID: PMC9460331 DOI: 10.3390/nu14173516] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/19/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
The evidence on the relationship of pyridoxal 5′-phosphate (PLP) with sleep-related problems is limited and controversial. Notably, there is a lack of studies on the general population and studies of the dose–response relationship. Therefore, we conducted a cross-sectional study to examine the associations between serum PLP concentration and sleep-related problems (sleep quality and sleep duration) in adults, using the data of the National Health and Nutrition Examination Survey 2005–2010. High-performance liquid chromatography (HPLC) was used to test PLP in blood samples. Sleep quality and sleep duration were based on self-reported data, with sleep quality categorized as sleep disorder, trouble falling asleep, waking up during the night, and daytime sleepiness. The primary analyses utilized logistic regression models and restricted cubic spline. Compared with the first quartile (Q1), the odds ratios (ORs) and 95% confidence intervals (CIs) of daytime sleepiness for the Q2 and Q3 of serum PLP concentrations were 0.76 (0.59–0.99) and 0.78 (0.62–0.98), respectively. The relationship was only significant for males. Furthermore, a non-linear dose–response relationship was observed between serum PLP concentration and the risk of daytime sleepiness. Compared with the normal sleep duration group, serum PLP concentrations were negatively associated with the risks of very short, short, and long sleep duration, with relative risk ratios (RRRs) of 0.58 (0.43–0.81) (Q4), 0.71 (0.61–0.83) (Q4) and 0.62 (0.34–0.94) (Q3), respectively. The average serum PLP concentrations were higher in people with normal sleep duration, suggesting a non-linear dose–response relationship. Our study indicated that serum PLP concentrations were negatively associated with daytime sleepiness, and this association may only exist in males. Moreover, it was also inversely related to abnormal sleep duration (very short, short, long) compared to normal sleep duration.
Collapse
|
18
|
He S, Chen Y, Wang L, Bai X, Bu T, Zhang J, Lu M, Ha NC, Quan C, Nam KH, Xu Y. Structural and Functional Analysis of the Pyridoxal Phosphate Homeostasis Protein YggS from Fusobacterium nucleatum. Molecules 2022; 27:molecules27154781. [PMID: 35897955 PMCID: PMC9332261 DOI: 10.3390/molecules27154781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/15/2022] [Accepted: 07/23/2022] [Indexed: 11/16/2022] Open
Abstract
Pyridoxal 5′-phosphate (PLP) is the active form of vitamin B6, but it is highly reactive and poisonous in its free form. YggS is a PLP-binding protein found in bacteria and humans that mediates PLP homeostasis by delivering PLP to target enzymes or by performing a protective function. Several biochemical and structural studies of YggS have been reported, but the mechanism by which YggS recognizes PLP has not been fully elucidated. Here, we report a functional and structural analysis of YggS from Fusobacterium nucleatum (FnYggS). The PLP molecule could bind to native FnYggS, but no PLP binding was observed for selenomethionine (SeMet)-derivatized FnYggS. The crystal structure of FnYggS showed a type III TIM barrel fold, exhibiting structural homology with several other PLP-dependent enzymes. Although FnYggS exhibited low (<35%) amino acid sequence similarity with previously studied YggS proteins, its overall structure and PLP-binding site were highly conserved. In the PLP-binding site of FnYggS, the sulfate ion was coordinated by the conserved residues Ser201, Gly218, and Thr219, which were positioned to provide the binding moiety for the phosphate group of PLP. The mutagenesis study showed that the conserved Ser201 residue in FnYggS was the key residue for PLP binding. These results will expand the knowledge of the molecular properties and function of the YggS family.
Collapse
Affiliation(s)
- Shanru He
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
| | - Yuanyuan Chen
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
| | - Lulu Wang
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
- School of Life Science and Biotechnology, Dalian University of Technology, No. 2 Linggong Road, Dalian 116024, China
| | - Xue Bai
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
| | - Tingting Bu
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
| | - Jie Zhang
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
| | - Ming Lu
- Shandong Provincial Key Laboratory of Energy Genetics, Key Laboratory of Biofuel, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China;
| | - Nam-Chul Ha
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Gwanak-gu, Seoul 00826, Korea;
| | - Chunshan Quan
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
- Correspondence: (C.Q.); (K.H.N.); (Y.X.)
| | - Ki Hyun Nam
- Department of Life Science, Pohang University of Science and Technology, Pohang 37673, Korea
- POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 37673, Korea
- Correspondence: (C.Q.); (K.H.N.); (Y.X.)
| | - Yongbin Xu
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, China; (S.H.); (Y.C.); (L.W.); (X.B.); (T.B.); (J.Z.)
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, China
- Correspondence: (C.Q.); (K.H.N.); (Y.X.)
| |
Collapse
|
19
|
Guidotti I, Lugli L, Ori L, Roversi MF, Casa Muttini ED, Bedetti L, Pugliese M, Cavalleri F, Stefanelli F, Ferrari F, Berardi A. Neonatal seizures treatment based on conventional multichannel EEG monitoring: an overview of therapeutic options. Expert Rev Neurother 2022; 22:623-638. [PMID: 35876114 DOI: 10.1080/14737175.2022.2105698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Seizures are the main neurological emergency during the neonatal period and are mostly acute and focal. The prognosis mainly depends on the underlying etiology. Conventional multichannel video-electroencephalographic (cEEG) monitoring is the gold standard for diagnosis, but treatment remains a challenge. AREAS COVERED : This review, based on PubMed search over the last 4 decades, focuses on the current treatment options for neonatal seizures based on cEEG monitoring. There is still no consensus on seizure therapy, owing to poor scientific evidence. Traditionally, the first-line treatments are phenobarbital and phenytoin, followed by midazolam and lidocaine, but their efficacy is limited. Therefore, current evidence strongly suggests the use of alternative antiseizure medications. Randomized controlled trials of new drugs are ongoing. EXPERT OPINION : Therapy for neonatal seizures should be prompt and tailored, based on semeiology, mirror of the underlying cause, and cEEG features. Further research should focus on antiseizure medications that directly act on the etiopathogenetic mechanism responsible for seizures and are therefore more effective in seizure control.
Collapse
Affiliation(s)
- Isotta Guidotti
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Licia Lugli
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Luca Ori
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Maria Federica Roversi
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Elisa Della Casa Muttini
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Luca Bedetti
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Marisa Pugliese
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Francesca Cavalleri
- Division of Neuroradiology, Department of Neuroscience, Nuovo Ospedale Civile S. Agostino-Estense, Modena, Italy
| | - Francesca Stefanelli
- Department of Medical and Surgical Sciences of the Mothers, Children and Adults, Post Graduate School of Pediatrics, University of Modena and Reggio Emilia, Modena, Italy
| | - Fabrizio Ferrari
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Alberto Berardi
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| |
Collapse
|
20
|
Ito T. Role of the conserved pyridoxal 5'-phosphate-binding protein YggS/PLPBP in vitamin B6 and amino acid homeostasis. Biosci Biotechnol Biochem 2022; 86:1183-1191. [PMID: 35803498 DOI: 10.1093/bbb/zbac113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 06/30/2022] [Indexed: 11/14/2022]
Abstract
The YggS/PLPBP protein (also called COG0325 or PLPHP) is a conserved pyridoxal 5'-phosphate (PLP)-binding protein present in all three domains of life. Recent studies have demonstrated that disruption or mutation of this protein has multifaceted effects in various organisms, including vitamin B6-dependent epilepsy in humans. In Escherichia coli, disruption of this protein-encoded by yggS-perturbs Thr-Ile/Val metabolism, one-carbon metabolism, coenzyme A synthesis, and vitamin B6 homeostasis. This protein is critical for maintaining low levels of pyridoxine 5'-phosphate (PNP) in various organisms. In the yggS-deficient E. coli strain, inhibition of PLP-dependent enzymes, such as the glycine cleavage system by PNP is the root cause of metabolic perturbation. Our data suggest that the YggS/PLPBP protein may be involved in the balancing of B6 vitamers by mediating efficient turnover of protein-bound B6 vitamers. This paper reviews recent findings on the function of the YggS/PLPBP protein.
Collapse
Affiliation(s)
- Tomokazu Ito
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
| |
Collapse
|
21
|
Stolwijk NN, Brands MM, Smit LS, van der Wel V, Hollak CEM, van Karnebeek CD. A vitamin a day keeps the doctor away: The need for high quality pyridoxal-5'-phosphate. Eur J Paediatr Neurol 2022; 39:25-29. [PMID: 35636100 DOI: 10.1016/j.ejpn.2022.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 03/21/2022] [Accepted: 04/28/2022] [Indexed: 12/17/2022]
Abstract
BACKGROUND A rare subset of vitamin B6 responsive seizure disorders does not respond to pyridoxine, and requires the active form of vitamin B6, pyridoxal-5'-phosphate (PLP), to maintain seizure control. Patients with PLP-responsive seizures are dependent on chronic PLP treatment, yet no licensed PLP product is available. PLP food supplements, a product category regulated less stringently than medication, may prove of insufficient effectiveness and safety. Here we describe and discuss three patient scenarios which illustrate this conundrum. METHODS Medical and laboratory records were reviewed with retrospective extraction for three unrelated patients who suffered complications during treatment with PLP food supplements. RESULTS - Two cases of PNPO deficiency and one case of PLP-dependent epileptic encephalopathy without a (genetic) diagnosis are reported. These patients are critically dependent on PLP for seizure control and have suffered complications due to insufficient quality of these food supplements during the course of treatment. Complications include the occurrence of seizures following the administration of suspected low quality PLP, inactive PLP due to light exposure, a PLP intoxication, resisting administration and post-administration vomiting as a result of the ingestion of large amounts of capsules per day. CONCLUSION - This case series illustrates that the reliance on food supplements as anti-seizure therapy is not without risk. The treatment of PLP-dependent seizures exemplifies that PLP is administered as medication, thus there is a clear need for licensed vitamin products of pharmaceutical quality.
Collapse
Affiliation(s)
- N N Stolwijk
- Medicine for Society, Platform at Amsterdam University Medical Center - University of Amsterdam, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam University Medical Center - University of Amsterdam, the Netherlands
| | - M M Brands
- Department of Pediatrics & Human Genetics, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - L S Smit
- Department of Neurology, Division of Pediatric Neurology, Sophia Children's Hospital, Erasmus Medical Center, Rotterdam, the Netherlands
| | - V van der Wel
- Medicine for Society, Platform at Amsterdam University Medical Center - University of Amsterdam, the Netherlands
| | - C E M Hollak
- Medicine for Society, Platform at Amsterdam University Medical Center - University of Amsterdam, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam University Medical Center - University of Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands
| | - C D van Karnebeek
- Department of Pediatrics & Human Genetics, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, the Netherlands; United for Metabolic Diseases, the Netherlands; Emma Center for Personalized Medicine, Amsterdam Reproduction and Development, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands.
| |
Collapse
|
22
|
Jiao X, Gong P, Niu Y, Xu Z, Wu Y, Zhang Y, Yang Z. The Clinical Features and Long-Term Follow-Up of Vitamin B6-Responsive Infantile Spasms in a Chinese Cohort. Front Neurol 2022; 13:895978. [PMID: 35645976 PMCID: PMC9134116 DOI: 10.3389/fneur.2022.895978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/21/2022] [Indexed: 11/22/2022] Open
Abstract
Objective To analyze the clinical features, treatment, and prognosis of patients with vitamin B6-responsive infantile spasms (IS). Methods The clinical features, genetics, and follow-up data of 30 patients were collected and analyzed. Results The age of epileptic spasms (ES) onset was from 3 months to 12 months. They all received high doses of vitamin B6 at different times after the onset of ES, ranging from 1 day to 5 months. ES were controlled within 11 days in 93% (28/30) patients, and as late as 1 month and 2 months in the other two patients. In the course of treatment, 28 patients were seizure-free all the time, and seizures of other two patients recurred due to withdrawal of vitamin B6. The available follow-up EEG results of 28 patients were normal in 26 cases, and 81% (21/26) had suppressed epileptic discharges within 6 months. Of the 26 cases with normal follow up EEG, 4 had developmental delay and 22 had normal development. The time for EEG to return to normal in 22 patients with normal development ranged from 14 days to 2 years (mean = 111.5 days; median = 52.5 days). The time for EEG to return to normal in the other 4 patients with development delay ranged from 4 months to 2 years (mean = 375 days; median = 330 days). To the last follow-up, seizures were controlled well in 29 surviving patients, and 21 patients were able to deactivate from all medications without seizures recurrence. Sixteen patients showed varying degrees of developmental delay after onset. After seizure control, the psychomotor development was delayed in 7 patients (one died) until the last follow-up. Genetic analysis did not show any meaningful results. Conclusion An observation period of 1–2 weeks is essential to identify patients with vitamin B6-responsive IS. The treatment time could be extended according to the treatment response and EEG changes. It might take a longer time for EEG to return to normal and to stop taking drugs in patients with persistent or unimproved developmental delay. Neurodevelopmental outcomes and prognosis of vitamin B6-responsive IS were relatively favorable.
Collapse
|
23
|
Zuberi SM, Wirrell E, Yozawitz E, Wilmshurst JM, Specchio N, Riney K, Pressler R, Auvin S, Samia P, Hirsch E, Galicchio S, Triki C, Snead OC, Wiebe S, Cross JH, Tinuper P, Scheffer IE, Perucca E, Moshé SL, Nabbout R. ILAE classification and definition of epilepsy syndromes with onset in neonates and infants: Position statement by the ILAE Task Force on Nosology and Definitions. Epilepsia 2022; 63:1349-1397. [PMID: 35503712 DOI: 10.1111/epi.17239] [Citation(s) in RCA: 239] [Impact Index Per Article: 119.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 03/20/2022] [Accepted: 03/21/2022] [Indexed: 12/20/2022]
Abstract
The International League Against Epilepsy (ILAE) Task Force on Nosology and Definitions proposes a classification and definition of epilepsy syndromes in the neonate and infant with seizure onset up to 2 years of age. The incidence of epilepsy is high in this age group and epilepsy is frequently associated with significant comorbidities and mortality. The licensing of syndrome specific antiseizure medications following randomized controlled trials and the development of precision, gene-related therapies are two of the drivers defining the electroclinical phenotypes of syndromes with onset in infancy. The principal aim of this proposal, consistent with the 2017 ILAE Classification of the Epilepsies, is to support epilepsy diagnosis and emphasize the importance of classifying epilepsy in an individual both by syndrome and etiology. For each syndrome, we report epidemiology, clinical course, seizure types, electroencephalography (EEG), neuroimaging, genetics, and differential diagnosis. Syndromes are separated into self-limited syndromes, where there is likely to be spontaneous remission and developmental and epileptic encephalopathies, diseases where there is developmental impairment related to both the underlying etiology independent of epileptiform activity and the epileptic encephalopathy. The emerging class of etiology-specific epilepsy syndromes, where there is a specific etiology for the epilepsy that is associated with a clearly defined, relatively uniform, and distinct clinical phenotype in most affected individuals as well as consistent EEG, neuroimaging, and/or genetic correlates, is presented. The number of etiology-defined syndromes will continue to increase, and these newly described syndromes will in time be incorporated into this classification. The tables summarize mandatory features, cautionary alerts, and exclusionary features for the common syndromes. Guidance is given on the criteria for syndrome diagnosis in resource-limited regions where laboratory confirmation, including EEG, MRI, and genetic testing, might not be available.
Collapse
Affiliation(s)
- Sameer M Zuberi
- Paediatric Neurosciences Research Group, Royal Hospital for Children, Institute of Health & Wellbeing, Collaborating Centre of European Reference Network EpiCARE, University of Glasgow, Glasgow, UK
| | - Elaine Wirrell
- Divisions of Child and Adolescent Neurology and Epilepsy, Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Elissa Yozawitz
- Isabelle Rapin Division of Child Neurology, Saul R. Korey Department of Neurology, Montefiore Medical Center, Bronx, New York, USA
| | - Jo M Wilmshurst
- Department of Paediatric Neurology, Red Cross War Memorial Children's Hospital, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Nicola Specchio
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesu' Children's Hospital, IRCCS, Member of European Reference Network EpiCARE, Rome, Italy
| | - Kate Riney
- Neurosciences Unit, Queensland Children's Hospital, South Brisbane, Queensland, Australia.,Faculty of Medicine, University of Queensland, St Lucia, Queensland, Australia
| | - Ronit Pressler
- Clinical Neuroscience, UCL- Great Ormond Street Institute of Child Health, London, UK.,Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, Member of European Reference Network EpiCARE, London, UK
| | - Stephane Auvin
- AP-HP, Hôpital Robert-Debré, INSERM NeuroDiderot, DMU Innov-RDB, Neurologie Pédiatrique, Member of European Reference Network EpiCARE, Université de Paris, Paris, France
| | - Pauline Samia
- Department of Paediatrics and Child Health, Aga Khan University, Nairobi, Kenya
| | - Edouard Hirsch
- Neurology Epilepsy Unit "Francis Rohmer", INSERM 1258, FMTS, Strasbourg University, Strasbourg, France
| | - Santiago Galicchio
- Child Neurology Department, Victor J Vilela Child Hospital of Rosario, Santa Fe, Argentina
| | - Chahnez Triki
- Child Neurology Department, LR19ES15 Neuropédiatrie, Sfax Medical School, University of Sfax, Sfax, Tunisia
| | - O Carter Snead
- Pediatric Neurology, Hospital for Sick Children, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Samuel Wiebe
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - J Helen Cross
- Programme of Developmental Neurosciences, UCL NIHR BRC Great Ormond Street Institute of Child Health, Great Ormond Street Hospital for Children, Member of European Reference Network EpiCARE, London, UK.,Young Epilepsy, Lingfield, UK
| | - Paolo Tinuper
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Ingrid E Scheffer
- Austin Health and Royal Children's Hospital, Florey Institute, Murdoch Children's Research Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Emilio Perucca
- Department of Neuroscience, Monash University, Melbourne, Victoria, Australia.,Department of Medicine, Austin Health, University of Melbourne, Heidelberg, Victoria, Australia
| | - Solomon L Moshé
- Isabelle Rapin Division of Child Neurology, Saul R. Korey Department of Neurology, Bronx, New York, USA.,Departments of Neuroscience and Pediatrics, Albert Einstein College of Medicine, Bronx, New York, USA.,Montefiore Medical Center, Bronx, New York, USA
| | - Rima Nabbout
- Reference Centre for Rare Epilepsies, Department of Pediatric Neurology, Necker-Enfants Malades University Hospital, APHP, Member of European Reference Network EpiCARE, Institut Imagine, INSERM, UMR 1163, Université Paris cité, Paris, France
| |
Collapse
|
24
|
Jiao X, Gong P, Niu Y, Zhang Y, Yang Z. A Rare Presentation Characterized by Epileptic Spasms in ALDH7A1, Pyridox(am)ine-5′-Phosphate Oxidase, and PLPBP Deficiency. Front Genet 2022; 13:804461. [PMID: 35495162 PMCID: PMC9039010 DOI: 10.3389/fgene.2022.804461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 03/07/2022] [Indexed: 11/25/2022] Open
Abstract
Objective: To analyze the clinical feature, treatment, and prognosis of epileptic spasms (ES) in vitamin B6–dependent epilepsy, including patients with pyridoxine-dependent epilepsy (PDE) caused by ALDH7A1 mutation, pyridox(am)ine-5′-phosphate oxidase (PNPO) deficiency, and PLPBP deficiency. Methods: We analyzed data from a cohort of 54 cases with PDE, 13 cases with PNPO deficiency, and 2 cases with PLPBP deficiency and looked for the presentation of ES among them. Results: A total of 11 patients with the seizure presentation of ES have been collected. Among them, four patients carried mutations in ALDH7A1, six carried mutations in PNPO, and the remaining one carried mutation in PLPBP. The analysis of this cohort identified nine cases presenting as infantile spasms distributed in the three diseases and two cases presenting as Ohtahara syndrome diagnosed with PDE and PNPO deficiency, respectively. In the PDE and PLPBP deficiency groups, seizures were controlled by pyridoxine monotherapy, and the remaining one had refractory seizures due to secondary brain atrophy. In the groups with PNPO deficiency, one patient showed seizure-free when treated by PLP combined with valproic acid, three still had infrequent seizures treated by PLP monotherapy or pyridoxine or PLP combined with other antiseizure medications, and two died. In two cases presenting as Ohtahara syndrome, after regular treatment, one showed seizure-free, the others showed a marked decrease in seizure frequency, and they both showed an improvement in EEG. Significance: ES might be a common form of seizures in PNPO deficiency, and EEG presented as hypsarrhythmia or a burst suppression pattern. It is difficult for pyridoxine to control frequent seizures caused by secondary brain injury. In our PNPO deficiency cohort, patients with infantile spasms did not respond better to PLP than pyridoxine. Timely and correct treatment could prevent the transformation of the child’s disease from Ohtahara syndrome and infantile spasms to subsequent epileptic encephalopathy or refractory epilepsy.
Collapse
|
25
|
McLean H, Palmquist R, Nadauld LD, Malone Jenkins S, Bonkowsky J, Filloux F. On the edge—A diagnostic odyssey. Clin Case Rep 2022; 10:e05688. [PMID: 35425609 PMCID: PMC8989017 DOI: 10.1002/ccr3.5688] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 02/08/2022] [Accepted: 03/16/2022] [Indexed: 11/29/2022] Open
Abstract
The diagnostic odyssey of a child with epileptic encephalopathy was resolved by rapid whole genome sequencing. This identified a rare form of pyridoxine responsive epilepsy due to a pathogenic variant in PLPBP. Access to such potentially life‐changing diagnostic technology needs to expand in a thoughtful and equitable manner.
Collapse
Affiliation(s)
- Hailey McLean
- School of Medicine University of Utah Salt Lake City Utah USA
| | - Rachel Palmquist
- Division of Pediatric Neurology University of Utah Salt Lake City Utah USA
| | - Lincoln D. Nadauld
- Intermountain Precision Genomics Intermountain Health Care Salt Lake City Utah USA
| | | | - Joshua Bonkowsky
- Division of Pediatric Neurology University of Utah Salt Lake City Utah USA
| | - Francis Filloux
- Division of Pediatric Neurology University of Utah Salt Lake City Utah USA
| |
Collapse
|
26
|
Zimmern V, Minassian B, Korff C. A Review of Targeted Therapies for Monogenic Epilepsy Syndromes. Front Neurol 2022; 13:829116. [PMID: 35250833 PMCID: PMC8891748 DOI: 10.3389/fneur.2022.829116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 01/13/2022] [Indexed: 11/15/2022] Open
Abstract
Genetic sequencing technologies have led to an increase in the identification and characterization of monogenic epilepsy syndromes. This increase has, in turn, generated strong interest in developing “precision therapies” based on the unique molecular genetics of a given monogenic epilepsy syndrome. These therapies include diets, vitamins, cell-signaling regulators, ion channel modulators, repurposed medications, molecular chaperones, and gene therapies. In this review, we evaluate these therapies from the perspective of their clinical validity and discuss the future of these therapies for individual syndromes.
Collapse
Affiliation(s)
- Vincent Zimmern
- Division of Child Neurology, University of Texas Southwestern, Dallas, TX, United States
- *Correspondence: Vincent Zimmern
| | - Berge Minassian
- Division of Child Neurology, University of Texas Southwestern, Dallas, TX, United States
| | - Christian Korff
- Pediatric Neurology Unit, University Hospitals, Geneva, Switzerland
| |
Collapse
|
27
|
Wang Y, Zhao Y, Xia L, Chen L, Liao Y, Chen B, Liu Y, Gong W, Tian Y, Hu B. yggS Encoding Pyridoxal 5'-Phosphate Binding Protein Is Required for Acidovorax citrulli Virulence. Front Microbiol 2022; 12:783862. [PMID: 35087487 PMCID: PMC8787154 DOI: 10.3389/fmicb.2021.783862] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/06/2021] [Indexed: 11/26/2022] Open
Abstract
Bacterial fruit blotch, caused by seed-borne pathogen Acidovorax citrulli, poses a serious threat to the production of cucurbits globally. Although the disease can cause substantial economic losses, limited information is available about the molecular mechanisms of virulence. This study identified that, a random transposon insertion mutant impaired in the ability to elicit a hypersensitive response on tobacco. The disrupted gene in this mutant was determined to be Aave_0638, which is predicted to encode a YggS family pyridoxal phosphate-dependent enzyme. YggS is a highly conserved protein among multiple organisms, and is responsible for maintaining the homeostasis of pyridoxal 5′-phosphate and amino acids in cells. yggS deletion mutant of A. citrulli strain XjL12 displayed attenuated virulence, delayed hypersensitive response, less tolerance to H2O2 and pyridoxine, increased sensitivity to antibiotic β-chloro-D-alanine, and reduced swimming. In addition, RNA-Seq analysis demonstrated that yggS was involved in regulating the expression of certain pathogenicity-associated genes related to secretion, motility, quorum sensing and oxidative stress response. Importantly, YggS significantly affected type III secretion system and its effectors in vitro. Collectively, our results suggest that YggS is indispensable for A.citrulli virulence and expands the role of YggS in the biological processes.
Collapse
Affiliation(s)
- Yuanjie Wang
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Yuqiang Zhao
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-sen), Nanjing, China
| | - Liming Xia
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Lin Chen
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Yajie Liao
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Baohui Chen
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Yiyang Liu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Weirong Gong
- Plant Protection and Quarantine Station of Province, Nanjing, China
| | - Yanli Tian
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Baishi Hu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| |
Collapse
|
28
|
Mechanism of pyridoxine 5'-phosphate accumulation in PLPBP protein-deficiency. J Bacteriol 2022; 204:e0052121. [PMID: 34978460 DOI: 10.1128/jb.00521-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pyridoxal 5'-phosphate (PLP)-binding protein (PLPBP) plays an important role in vitamin B6 homeostasis. Loss of this protein in organisms such as Escherichia coli and humans disrupts the vitamin B6 pool and induces intracellular accumulation of pyridoxine 5'-phosphate (PNP), which is normally undetectable in wild-type cells. The accumulated PNP could affect diverse metabolic systems through inhibition of some PLP-dependent enzymes. In this study, we investigated the as yet unclear mechanism of intracellular accumulation of PNP by the loss of PLPBP protein encoded by yggS in E. coli. Genetic studies using several PLPBP-deficient strains of E. coli lacking known enzyme(s) in the de novo or salvage pathway of vitamin B6, which includes pyridoxine (amine) 5'-phosphate oxidase (PNPO), PNP synthase, pyridoxal kinase, and pyridoxal reductase, demonstrated that neither the flux from the de novo pathway nor the salvage pathway solely contributed to the PNP accumulation caused by the PLPBP mutation. Studies with the strains lacking both PLPBP and PNPO suggested that PNP shares the same pool with PMP, and showed that PNP levels are impacted by PMP levels and vice versa. We show that disruption of PLPBP lead to perturb PMP homeostasis, which may result in PNP accumulation in the PLPBP-deficient strains. Importance A PLP-binding protein PLPBP from the conserved COG0325 family has recently been recognized as a key player in vitamin B6 homeostasis in various organisms. Loss of PLPBP disrupts vitamin B6 homeostasis and perturbs diverse metabolisms, including amino acid and α-keto acid metabolism. Accumulation of PNP is a characteristic phenotype of the PLPBP deficiency and is suggested to be a potential cause of the pleiotropic effects, but the mechanism of the PNP accumulation was poorly understood. In this study, we show that fluxes for PNP synthesis/metabolism are not responsible for the accumulation of PNP. Our results indicate that PLPBP is involved in the homeostasis of pyridoxamine 5'-phosphate, and its disruption may lead to the accumulation of PNP in PLPBP-deficiency.
Collapse
|
29
|
McGinn RJ, Von Stein EL, Summers Stromberg JE, Li Y. Precision medicine in epilepsy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 190:147-188. [DOI: 10.1016/bs.pmbts.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
30
|
Aquilano G, Linnér A, Ygberg S, Stödberg T, Henckel E. Case report: Fatal outcome of pyridoxine-dependent epilepsy presenting as respiratory distress followed by a circulatory collapse. Front Pediatr 2022; 10:940103. [PMID: 35967578 PMCID: PMC9366515 DOI: 10.3389/fped.2022.940103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
Pyridoxine-dependent epilepsy is a rare autosomal recessive disease usually associated with neonatal seizures that do not respond to common antiseizure medications but are controlled by pyridoxine administration. Because the symptoms can mimic common neonatal disorders, the diagnosis can be initially missed or delayed. We report a fatal case of a boy who was initially diagnosed with respiratory distress, birth asphyxia, and persistent pulmonary hypertension and whose condition rapidly deteriorated during the first day of life.
Collapse
Affiliation(s)
- Giulia Aquilano
- Department of Neonatology, Karolinska University Hospital, Stockholm, Sweden
| | - Agnes Linnér
- Department of Neonatology, Karolinska University Hospital, Stockholm, Sweden.,Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Sofia Ygberg
- Department of Child Neurology, Karolinska University Hospital, Stockholm, Sweden.,Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Center for Inherited Metabolic Diseases (CMMS), Karolinska University Hospital, Stockholm, Sweden
| | - Tommy Stödberg
- Department of Child Neurology, Karolinska University Hospital, Stockholm, Sweden.,Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Ewa Henckel
- Department of Neonatology, Karolinska University Hospital, Stockholm, Sweden.,Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
31
|
Myers KA, Scheffer IE. Precision Medicine Approaches for Infantile-Onset Developmental and Epileptic Encephalopathies. Annu Rev Pharmacol Toxicol 2021; 62:641-662. [PMID: 34579535 DOI: 10.1146/annurev-pharmtox-052120-084449] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epilepsy is an etiologically heterogeneous condition; however, genetic factors are thought to play a role in most patients. For those with infantile-onset developmental and epileptic encephalopathy (DEE), a genetic diagnosis is now obtained in more than 50% of patients. There is considerable motivation to utilize these molecular diagnostic data to help guide treatment, as children with DEEs often have drug-resistant seizures as well as developmental impairment related to cerebral epileptiform activity. Precision medicine approaches have the potential to dramatically improve the quality of life for these children and their families. At present, treatment can be targeted for patients with diagnoses in many genetic causes of infantile-onset DEE, including genes encoding sodium or potassium channel subunits, tuberous sclerosis, and congenital metabolic diseases. Precision medicine may refer to more intelligent choices of conventional antiseizure medications, repurposed agents previously used for other indications, novel compounds, enzyme replacement, or gene therapy approaches. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Kenneth A Myers
- Research Institute of the McGill University Health Centre, Division of Child Neurology, Department of Pediatrics, and Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University, Montreal, Quebec H4A 3J1, Canada;
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, Heidelberg, Victoria 3084, Australia; .,Department of Paediatrics, Royal Children's Hospital, The University of Melbourne, Parkville, Victoria 3052, Australia.,The Florey Institute of Neuroscience and Mental Health and Murdoch Children's Research Institute, Parkville, Victoria 3052, Australia
| |
Collapse
|
32
|
Vu HN, Downs DM. Loss of YggS (COG0325) impacts aspartate metabolism in Salmonella enterica. Mol Microbiol 2021; 116:1232-1240. [PMID: 34498310 DOI: 10.1111/mmi.14810] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/24/2021] [Accepted: 09/07/2021] [Indexed: 12/01/2022]
Abstract
YggS is a pyridoxal 5'-phosphate (PLP)-binding protein of the conserved COG0325 family. Despite a connection with vitamin B6 homeostasis in many species, neither a precise biochemical activity nor the molecular mechanism of how YggS contributes to cellular function has been described. In a transposon mutagenesis screen, we found that insertions in aspC (encoding a PLP-dependent aspartate aminotransferase, EC 2.6.1.1) in a Salmonella enterica strain lacking yggS caused a synthetic growth defect, which could be rescued by the addition of exogenous aspartate. Characterization of spontaneous suppressors which improved the growth of the yggS aspC double mutant suggested that this synthetic aspartate limitation was dependent on TyrB, a PLP-dependent aromatic amino acid aminotransferase (EC 2.6.1.57). Genetic and biochemical data were consistent with the hypothesis that TyrB activity was inhibited by accumulated pyridoxine 5'-phosphate and α-keto acids caused by a yggS mutation. This study provides data consistent with a working model implicating YggS in modulating concentrations of B6 vitamers via transamination.
Collapse
Affiliation(s)
- Huong N Vu
- Department of Microbiology, The University of Georgia, Athens, Georgia, USA
| | - Diana M Downs
- Department of Microbiology, The University of Georgia, Athens, Georgia, USA
| |
Collapse
|
33
|
Mittal RR, Manokaran RK, James S. Treatable Cause of Refractory Seizures in an Infant with a Novel Mutation. J Pediatr Neurosci 2021; 16:69-70. [PMID: 34316313 PMCID: PMC8276961 DOI: 10.4103/jpn.jpn_68_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/07/2020] [Accepted: 07/19/2020] [Indexed: 11/18/2022] Open
Abstract
Pyridoxine-dependent epilepsy is a treatable cause of epilepsy, which is very well known. It is most commonly caused by mutations in ALDH7A1 and PNPO genes. A 5-month-old infant presented with refractory seizures. Magnetic resonance imaging (MRI) brain was normal. Clinical exome sequencing showed a novel mutation in PROSC gene. He responded very well to pyridoxine and has been seizure free since the beginning of the treatment. PROSC gene mutations have been recently described as a cause for pyridoxine-dependent epilepsy. Here, we describe a first case report of PROSC mutation from India with a rare genetic variant presenting as pyridoxine-dependent epilepsy.
Collapse
Affiliation(s)
- Ruchi R Mittal
- Department of Paediatrics, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
| | - Ranjith Kumar Manokaran
- Department of Paediatric Neurology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
| | - Saji James
- Department of Paediatrics, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
| |
Collapse
|
34
|
Scelsi HF, Barlow BM, Saccuzzo EG, Lieberman RL. Common and rare myocilin variants: Predicting glaucoma pathogenicity based on genetics, clinical, and laboratory misfolding data. Hum Mutat 2021; 42:903-946. [PMID: 34082484 DOI: 10.1002/humu.24238] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 12/12/2022]
Abstract
Rare variants of the olfactomedin domain of myocilin are considered causative for inherited, early-onset open-angle glaucoma, with a misfolding toxic gain-of-function pathogenic mechanism detailed by 20 years of laboratory research. Myocilin variants are documented in the scientific literature and identified through large-scale genetic sequencing projects such as those curated in the Genome Aggregation Database (gnomAD). In the absence of key clinical and laboratory information, however, the pathogenicity of any given variant is not clear, because glaucoma is a heterogeneous and prevalent age-onset disease, and common variants are likely benign. In this review, we reevaluate the likelihood of pathogenicity for the ~100 nonsynonymous missense, insertion-deletion, and premature termination of myocilin olfactomedin variants documented in the literature. We integrate available clinical, laboratory cellular, biochemical and biophysical data, the olfactomedin domain structure, and population genetics data from gnomAD. Of the variants inspected, ~50% can be binned based on a preponderance of data, leaving many of uncertain pathogenicity that motivate additional studies. Ultimately, the approach of combining metrics from different disciplines will likely resolve outstanding complexities regarding the role of this misfolding-prone protein within the context of a multifactorial and prevalent ocular disease, and pave the way for new precision medicine therapeutics.
Collapse
Affiliation(s)
- Hailee F Scelsi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Brett M Barlow
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Emily G Saccuzzo
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Raquel L Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| |
Collapse
|
35
|
Pal M, Lace B, Labrie Y, Laflamme N, Rioux N, Setty ST, Dugas M, Gosselin L, Droit A, Chrestian N, Rivest S. A founder mutation in the PLPBP gene in families from Saguenay-Lac-St-Jean region affected by a pyridoxine-dependent epilepsy. JIMD Rep 2021; 59:32-41. [PMID: 33977028 PMCID: PMC8100403 DOI: 10.1002/jmd2.12196] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/19/2020] [Accepted: 12/16/2020] [Indexed: 11/24/2022] Open
Abstract
Pyridoxine-dependent epilepsy (PDE) is a relatively rare subgroup of epileptic disorders. They generally present in infancy as an early onset epileptic encephalopathy or seizures, refractory to standard treatments, with rapid and variable responses to vitamin B6 treatment. Whole exome sequencing of three unrelated families identified homozygous pathogenic mutation c.370_373del, p.Asp124fs in PLPBP gene in five persons. Haplotype analysis showed a single shared profile for the affected persons and their parents, leading to a hypothesis about founder effect of the mutation in Saguenay-Lac-St-Jean region of French Canadians. All affected probands also shared one single mitochondrial haplotype T2b3 and two rare variations in the mitochondrial genome m.801A>G and m.5166A>G suggesting that a single individual female introduced PLPBP mutation c.370_373del, p.Asp124fs in Quebec. The mutation p.Asp124fs causes a severe disease phenotype with delayed myelination and cortical/subcortical brain atrophy. The most noteworthy radiological finding in this Quebec founder mutation is the presence of the temporal cysts that can be used as a marker of the disease. Also, both patients, who are alive, had a history of prenatal supplements taken by their mothers as antiemetic medication with high doses of pyridoxine. In the context of suspected PDE in patients with neonatal refractory seizures, treatment with pyridoxine and/or Pyridoxal-5-phophate has to be started immediately and continued until the results of genetic analysis received. Even with early appropriate treatment, neurological outcome of our patient is still poor.
Collapse
Affiliation(s)
- Maitou Pal
- Faculty of MedicineLaval UniversityQuébecQuébecCanada
| | - Baiba Lace
- Department of Medical GeneticsCentre Mère Enfant Soleil, Laval UniversityQuébecQuébecCanada
| | - Yvan Labrie
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| | - Nathalie Laflamme
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| | - Nadie Rioux
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| | - Samarth Thonta Setty
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| | - Marc‐Andre Dugas
- Department of PediatricsCentre Mère Enfant Soleil, Laval UniversityQuébecQuébecCanada
| | - Louise Gosselin
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| | - Arnaud Droit
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| | - Nicolas Chrestian
- Department of Pediatric Neurology, Pediatric Neuromuscular DisorderCentre Mère Enfant Soleil, Laval UniversityQuébecQuébecCanada
| | - Serge Rivest
- Centre de recherche CHU de Québec‐ Université Laval, Laval UniversityQuébecQuébecCanada
| |
Collapse
|
36
|
Hadtstein F, Vrolijk M. Vitamin B-6-Induced Neuropathy: Exploring the Mechanisms of Pyridoxine Toxicity. Adv Nutr 2021; 12:1911-1929. [PMID: 33912895 PMCID: PMC8483950 DOI: 10.1093/advances/nmab033] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 12/26/2022] Open
Abstract
Vitamin B-6 in the form of pyridoxine (PN) is commonly used by the general population. The use of PN-containing supplements has gained lots of attention over the past years as they have been related to the development of peripheral neuropathy. In light of this, the number of reported cases of adverse health effects due to the use of vitamin B-6 have increased. Despite a long history of study, the pathogenic mechanisms associated with PN toxicity remain elusive. Therefore, the present review is focused on investigating the mechanistic link between PN supplementation and sensory peripheral neuropathy. Excessive PN intake induces neuropathy through the preferential injury of sensory neurons. Recent reports on hereditary neuropathy due to pyridoxal kinase (PDXK) mutations may provide some insight into the mechanism, as genetic deficiencies in PDXK lead to the development of axonal sensory neuropathy. High circulating concentrations of PN may lead to a similar condition via the inhibition of PDXK. The mechanism behind PDXK-induced neuropathy is unknown; however, there is reason to believe that it may be related to γ-aminobutyric acid (GABA) neurotransmission. Compounds that inhibit PDXK lead to convulsions and reductions in GABA biosynthesis. The absence of central nervous system-related symptoms in PDXK deficiency could be due to differences in the regulation of PDXK, where PDXK activity is preserved in the brain but not in peripheral tissues. As PN is relatively impermeable to the blood-brain barrier, PDXK inhibition would similarly be confined to the peripheries and, as a result, GABA signaling may be perturbed within peripheral tissues, such as sensory neurons. Perturbed GABA signaling within sensory neurons may lead to excitotoxicity, neurodegeneration, and ultimately, the development of peripheral neuropathy. For several reasons, we conclude that PDXK inhibition and consequently disrupted GABA neurotransmission is the most plausible mechanism of toxicity.
Collapse
Affiliation(s)
- Felix Hadtstein
- University College Venlo, Campus Venlo, Maastricht University, Maastricht, The Netherlands
| | | |
Collapse
|
37
|
Syrbe S. Präzisionsmedizin für genetische Epilepsien – am Anfang des Weges? ZEITSCHRIFT FÜR EPILEPTOLOGIE 2021. [DOI: 10.1007/s10309-021-00409-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
38
|
Ghatge MS, Al Mughram M, Omar AM, Safo MK. Inborn errors in the vitamin B6 salvage enzymes associated with neonatal epileptic encephalopathy and other pathologies. Biochimie 2021; 183:18-29. [PMID: 33421502 PMCID: PMC11273822 DOI: 10.1016/j.biochi.2020.12.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 12/28/2022]
Abstract
Pyridoxal 5'-phosphate (PLP), the active cofactor form of vitamin B6 is required by over 160 PLP-dependent (vitamin B6) enzymes serving diverse biological roles, such as carbohydrates, amino acids, hemes, and neurotransmitters metabolism. Three key enzymes, pyridoxal kinase (PL kinase), pyridoxine 5'-phosphate oxidase (PNPO), and phosphatases metabolize and supply PLP to PLP-dependent enzymes through the salvage pathway. In born errors in the salvage enzymes are known to cause inadequate levels of PLP in the cell, particularly in neuronal cells. The resulting PLP deficiency is known to cause or implicated in several pathologies, most notably seizures. One such disorder, PNPO-dependent neonatal epileptic encephalopathy (NEE) results from natural mutations in PNPO and leads to null or reduced enzymatic activity. NEE does not respond to conventional antiepileptic drugs but may respond to treatment with the B6 vitamers PLP and/or pyridoxine (PN). In born errors that lead to PLP deficiency in cells have also been reported in PL kinase, however, to date none has been associated with epilepsy or seizure. One such pathology is polyneuropathy that responds to PLP therapy. Phosphatase deficiency or hypophosphatasia disorder due to pathogenic mutations in alkaline phosphatase is known to cause seizures that respond to PN therapy. In this article, we review the biochemical features of in born errors pertaining to the salvage enzyme's deficiency that leads to NEE and other pathologies. We also present perspective on vitamin B6 treatment for these disorders, along with attempts to develop zebrafish model to study the NEE syndrome in vivo.
Collapse
Affiliation(s)
- Mohini S Ghatge
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA; Institute for Structural Biology, Drug Discovery, and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Mohammed Al Mughram
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA; Institute for Structural Biology, Drug Discovery, and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Abdelsattar M Omar
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah, 21589, Saudi Arabia; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo, 11884, Egypt
| | - Martin K Safo
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA; Institute for Structural Biology, Drug Discovery, and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA.
| |
Collapse
|
39
|
Abstract
Vitamin B6 is an ensemble of six interconvertible vitamers: pyridoxine (PN), pyridoxamine (PM), pyridoxal (PL), and their 5'-phosphate derivatives, PNP, PMP, and PLP. Pyridoxal 5'-phosphate is a coenzyme in a variety of enzyme reactions concerning transformations of amino and amino acid compounds. This review summarizes all known and putative PLP-binding proteins found in the Escherichia coli MG1655 proteome. PLP can have toxic effects since it contains a very reactive aldehyde group at its 4' position that easily forms aldimines with primary and secondary amines and reacts with thiols. Most PLP is bound either to the enzymes that use it as a cofactor or to PLP carrier proteins, protected from the cellular environment but at the same time readily transferable to PLP-dependent apoenzymes. E. coli and its relatives synthesize PLP through the seven-step deoxyxylulose-5-phosphate (DXP)-dependent pathway. Other bacteria synthesize PLP in a single step, through a so-called DXP-independent pathway. Although the DXP-dependent pathway was the first to be revealed, the discovery of the widespread DXP-independent pathway determined a decline of interest in E. coli vitamin B6 metabolism. In E. coli, as in most organisms, PLP can also be obtained from PL, PN, and PM, imported from the environment or recycled from protein turnover, via a salvage pathway. Our review deals with all aspects of vitamin B6 metabolism in E. coli, from transcriptional to posttranslational regulation. A critical interpretation of results is presented, in particular, concerning the most obscure aspects of PLP homeostasis and delivery to PLP-dependent enzymes.
Collapse
|
40
|
Jiao X, Gong P, Wu Y, Zhang Y, Yang Z. Analysis of the Phenotypic Variability as Well as Impact of Early Diagnosis and Treatment in Six Affected Families With ALDH7A1 Deficiency. Front Genet 2021; 12:644447. [PMID: 33868381 PMCID: PMC8047191 DOI: 10.3389/fgene.2021.644447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/15/2021] [Indexed: 11/13/2022] Open
Abstract
Objective To describe the clinical characteristics of 12 patients from six families with pyridoxine-dependent epilepsy (PDE) carrying ALDH7A1 mutations, and analyze the impact of early diagnosis and treatment, as well as possible genotype–phenotype relationship. Methods Clinical and genetics data of 12 patients were collected. Results Family 1–3 presented with symptoms in the neonatal period, while family 4-6 presented during early infancy. In the same family, the age of onset was similar. The focal motor seizure appeared in all patients. The affected identical twins from family 4 were diagnosed with infantile spasms. Mutation analysis identified nine different ALDH7A1 mutations among six families. The neurodevelopment of siblings in family 1 was mild delay and normal separately due to the minor difference of delayed diagnosis time. Siblings in family 2 showed severely delayed and normal development respectively due to the significant difference of a delayed diagnosis for 4 years. In family 5, although the difference of the delayed diagnosis time is up to 7 years, the nearly normal psychomotor development in both patients might be due to infrequent seizures before the delayed diagnosis. A severe phenotype exhibited in family 3, 4, and 6. The survived affected patients presented with severe developmental delay or refractory seizures and their twins or older sisters presented a similar clinical history and died in the early days of life. Mutation analysis showed D511N and IVS11 + 1G > A in family 3, V188A and exon1 deletion in family 4, and Y354C and exon 8–13 deletion in family 6. Conclusion Patients from the same family often have the same phenotype, including onset age and seizure type. Early treatment with pyridoxine and infrequent seizures showed positive relationship with prognosis. The deletion of exon 1 and exon 8–13 might be associated with the severe phenotype.
Collapse
Affiliation(s)
- Xianru Jiao
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Pan Gong
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ye Wu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuehua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Zhixian Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| |
Collapse
|
41
|
Espinoza AC, Wright MA, Candee MS, Trandafir C, Nelson GR. Child Neurology: Late-Onset Vitamin B 6-Dependent Epilepsy Identified by Rapid Genome Sequencing. Neurology 2021; 96:911-914. [PMID: 33766999 DOI: 10.1212/wnl.0000000000011891] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- A Chris Espinoza
- From the Department of Pediatrics, Division of Pediatric Neurology, University of Utah, Salt Lake City. Cristina Trandafir is currently at Baylor College of Medicine, Houston, TX.
| | - Melissa A Wright
- From the Department of Pediatrics, Division of Pediatric Neurology, University of Utah, Salt Lake City. Cristina Trandafir is currently at Baylor College of Medicine, Houston, TX
| | - Meghan S Candee
- From the Department of Pediatrics, Division of Pediatric Neurology, University of Utah, Salt Lake City. Cristina Trandafir is currently at Baylor College of Medicine, Houston, TX
| | - Cristina Trandafir
- From the Department of Pediatrics, Division of Pediatric Neurology, University of Utah, Salt Lake City. Cristina Trandafir is currently at Baylor College of Medicine, Houston, TX
| | - Gary R Nelson
- From the Department of Pediatrics, Division of Pediatric Neurology, University of Utah, Salt Lake City. Cristina Trandafir is currently at Baylor College of Medicine, Houston, TX
| |
Collapse
|
42
|
Heath O, Pitt J, Mandelstam S, Kuschel C, Vasudevan A, Donoghue S. Early-onset vitamin B 6-dependent epilepsy due to pathogenic PLPBP variants in a premature infant: A case report and review of the literature. JIMD Rep 2021; 58:3-11. [PMID: 33728241 PMCID: PMC7932866 DOI: 10.1002/jmd2.12183] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/26/2020] [Accepted: 10/29/2020] [Indexed: 01/17/2023] Open
Abstract
Vitamin B6-dependent epilepsies are a heterogeneous group of disorders characterized by decreased availability of the active cofactor pyridoxal-5'-phosphate (PLP). While pathogenic variants in ALDH7A1 or PNPO genes account for most cases of these disorders, biallelic pathogenic variants in PLPBP have been shown to cause a form of early onset vitamin B6-dependent epilepsy (EPVB6D). PLPBP is thought to play a role in the homeostatic regulation of vitamin B6, by supplying PLP to apoenzymes while limiting side-reaction toxicity related to excess unbound PLP. Neonatal-onset intractable seizures that respond to pyridoxine and/or PLP are a predominant feature of EPVB6D in humans. Unlike other causes of vitamin B6-dependent epilepsies; however, a specific biomarker for this disorder has yet to be identified. Here we present data from a premature infant found to have pathogenic variants in PLPBP and propose that prematurity may provide an additional clue for early consideration of this diagnosis. We discuss these findings in context of previously published genotypic, phenotypic, and metabolic data from similarly affected patients.
Collapse
Affiliation(s)
- Oliver Heath
- Department of Metabolic MedicineThe Royal Children's HospitalMelbourneAustralia
| | - James Pitt
- Department of Biochemical Genetics, Victorian Clinical Genetics ServiceMurdoch Children's Research InstituteMelbourneAustralia
- Department of PaediatricsUniversity of MelbourneMelbourneAustralia
| | - Simone Mandelstam
- Department of Medical ImagingThe Royal Children's Hospital and Murdoch Children's Research InstituteMelbourneAustralia
- Department of PaediatricsUniversity of MelbourneMelbourneAustralia
- Department of RadiologyUniversity of MelbourneMelbourneAustralia
| | - Carl Kuschel
- Department of Obstetrics and GynecologyThe Royal Women's HospitalMelbourneAustralia
| | - Anand Vasudevan
- Department of GeneticsThe Royal Women's HospitalMelbourneAustralia
| | - Sarah Donoghue
- Department of Metabolic MedicineThe Royal Children's HospitalMelbourneAustralia
- Department of Biochemical Genetics, Victorian Clinical Genetics ServiceMurdoch Children's Research InstituteMelbourneAustralia
| |
Collapse
|
43
|
Chan F, Liu J. Molecular regulation of brain metabolism underlying circadian epilepsy. Epilepsia 2021; 62 Suppl 1:S32-S48. [PMID: 33395505 DOI: 10.1111/epi.16796] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 12/13/2022]
Abstract
Extensive study has demonstrated that epilepsy occurs with greater frequency at certain times in the 24-h cycle. Although these findings implicate an overlap between the circadian rhythm and epilepsy, the molecular and cellular mechanisms underlying this circadian regulation are poorly understood. Because the 24-h rhythm is generated by the circadian molecular system, it is not surprising that this system comprised of many circadian genes is implicated in epilepsy. We summarized evidence in the literature implicating various circadian genes such as Clock, Bmal1, Per1, Rev-erb⍺, and Ror⍺ in epilepsy. In various animal models of epilepsy, the circadian oscillation and the steady-state level of these genes are disrupted. The downstream pathway of these genes involves a large number of metabolic pathways associated with epilepsy. These pathways include pyridoxal metabolism, the mammalian target of rapamycin pathway, and the regulation of redox state. We propose that disruption of these metabolic pathways could mediate the circadian regulation of epilepsy. A greater understanding of the cellular and molecular mechanism of circadian regulation of epilepsy would enable us to precisely target the circadian disruption in epilepsy for a novel therapeutic approach.
Collapse
Affiliation(s)
- Felix Chan
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Judy Liu
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, USA.,Department of Neurology, Warren Alpert Medical School, Brown University, Providence, Rhode Island, USA
| |
Collapse
|
44
|
Gibaud M, Barth M, Lefranc J, Mention K, Villeneuve N, Schiff M, Maurey H, Barthez MA, Caubel I, Chouchane M, Doummar D, Kossorotoff M, Lamblin MD, Roubertie A, Nabbout R, Van Bogaert P. West Syndrome Is an Exceptional Presentation of Pyridoxine- and Pyridoxal Phosphate-Dependent Epilepsy: Data From a French Cohort and Review of the Literature. Front Pediatr 2021; 9:621200. [PMID: 33748042 PMCID: PMC7973036 DOI: 10.3389/fped.2021.621200] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 01/04/2021] [Indexed: 12/04/2022] Open
Abstract
Objective: To characterize the electro-clinical presentation of patients with pyridoxine-dependent epilepsy (PDE) and pyridoxal phosphate (PLP)-dependent epilepsy in order to determine whether some of them could be diagnosed as de novo West syndrome, i. e., West syndrome that starts after the age of 2 months without other types of seizures (focal seizures for instance) before the onset of epileptic spasms. Methods: We analyzed data from an unpublished cohort of 28 genetically confirmed cases of PDE with antiquitine (ATQ) deficiency and performed a review of the literature looking for description of West syndrome in patients with either PDE with ATQ deficiency or PLP-dependent epilepsy with Pyridox(am)ine phosphate oxidase (PNPO) deficiency. Results: Of the 28 cases from the ATQ deficiency French cohort, 5 had spasms. In four cases, spasms were associated with other types of seizures (myoclonus, focal seizures). In the last case, seizures started on the day of birth. None of these cases corresponded to de novo West syndrome. The review of the literature found only one case of PNPO deficiency presenting as de novo West syndrome and no case of ATQ deficiency. Significance: The presentation of PDE- and PLP-dependent epilepsy as de novo West syndrome is so exceptional that it probably does not justify a systematic trial of pyridoxine or PLP. We propose considering a therapeutic trial with these vitamins in West syndrome if spasms are associated with other seizure types or start before the age of 2 months.
Collapse
Affiliation(s)
- Marc Gibaud
- Service de neuropédiatrie, CHU d'Angers, Angers, France
| | - Magalie Barth
- Service de génétique médicale, CHU d'Angers, Angers, France
| | | | - Karine Mention
- Centre de référence des Maladies Héréditaires du métabolisme, Hôpital Jeanne de Flandre CHRU Lille, Lille, France
| | - Nathalie Villeneuve
- Service de neuropédiatrie, Hôpital de la Timone, APHM Marseille, Marseille, France
| | - Manuel Schiff
- Centre de référence maladies héréditaires du métabolisme Hôpital Robert Debré, APHP Paris, Paris, France
| | - Hélène Maurey
- Service de neuropédiatrie Hôpital Kremlin-Bicêtre APHP Paris, Paris, France
| | | | | | | | - Diane Doummar
- Service de neuropédiatrie, Hôpital d'Enfants Armand-Trousseau APHP Paris, Paris, France
| | - Manoëlle Kossorotoff
- Service de neuropédiatrie et maladies métaboliques, Hôpital Necker-Enfants Malades APHP Paris, Paris, France
| | - Marie-Dominique Lamblin
- Service de physiologie et explorations fonctionnelles, Hôpital Jeanne de Flandre CHRU Lille, Lille, France
| | - Agathe Roubertie
- Service de neuropédiatrie, CHU de Montpellier, Montpellier, France
| | - Rima Nabbout
- Service de neuropédiatrie et maladies métaboliques, Hôpital Necker-Enfants Malades APHP Paris, Paris, France
| | - Patrick Van Bogaert
- Service de neuropédiatrie, CHU d'Angers, Angers, France.,Laboratoire Angevin de Recherche en Ingénierie des Systèmes (LARIS), Université d'Angers, Angers, France
| |
Collapse
|
45
|
Ahmed S, DeBerardinis RJ, Ni M, Afroze B. Vitamin B6-dependent epilepsy due to pyridoxal phosphate-binding protein (PLPBP) defect - First case report from Pakistan and review of literature. Ann Med Surg (Lond) 2020; 60:721-727. [PMID: 33425341 PMCID: PMC7779953 DOI: 10.1016/j.amsu.2020.11.079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 11/28/2020] [Accepted: 11/28/2020] [Indexed: 11/16/2022] Open
Abstract
Introduction The Vitamin B6-dependent epilepsies are a heterogeneous group of autosomal recessive disorders usually characterized by neonatal onset seizures responsive to treatment with vitamin B6 available as pyridoxine (PN) or as the biologically active form pyridoxal 5-phosphate (PLP). The vitamin B6–dependent epilepsies are caused by mutations in at least five different genes involved in B6 metabolism. A literature review revealed that only 30 patients with vitamin B6-dependent epilepsy caused by PLPBP mutation have been reported worldwide. Presentation of case We report a case of baby boy born to first-cousin Pakistani parents who presented with generalized as well as focal seizures starting a few hours after birth and responsive to PLP. Whole exome sequencing revealed a homozygous pathogenic variant NM_007198.4:c.46_47insCA, NP_009129.1:p.Leu17Hisfs, causing a CA duplication resulting in a frameshift in the PLPBP gene. Discussion Vitamin B6-Dependent Epilepsy due to PLPBP defect is a rare disorder. The developmental outcomes are variable even with early therapy. Few patients are reported to achieve optimal developmental milestones with therapy. PLP has been advocated as the treatment of choice for PLPBP defect, but oral PN has also demonstrated good seizure control in some patients, including ours. Conclusion Vitamin B6-dependent epilepsy due to PLPBP defect is an important differential diagnosis to consider in patients with biochemical features suggestive of pyridoxamine 5′-phosphate Oxidase (PNPO) defect and gene testing can facilitate in reaching the correct diagnosis. Prompt diagnosis and treatment led to excellent seizure control in most patients. The Vitamin B6-dependent epilepsies are a heterogeneous group of autosomal recessive disorders. A literature review revealed that only 30 patients with PLPBP mutation have been reported. We report a case of baby boy born to first-cousin Pakistani parents responsive to pyridoxal 5-phosphate.
Collapse
Affiliation(s)
- Sibtain Ahmed
- Section of Clinical Chemistry, Department of Pathology and Laboratory Medicine, Aga Khan University, Stadium Road, P.O. Box 3500, Karachi, 74800, Pakistan
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute at UT Southwestern, Texas, USA, Howard Hughes Medical Institute, UT Southwestern Medical Center, USA
| | - Min Ni
- Children's Medical Center Research Institute at UT Southwestern, Texas, USA
| | - Bushra Afroze
- Department of Paediatrics & Child Health, Aga Khan University, Stadium Road, P.O. Box 3500, Karachi, 74800, Pakistan
| |
Collapse
|
46
|
Akiyama T, Hyodo Y, Hasegawa K, Oboshi T, Imai K, Ishihara N, Dowa Y, Koike T, Yamamoto T, Shibasaki J, Shimbo H, Fukuyama T, Takano K, Shiraku H, Takeshita S, Okanishi T, Baba S, Kubota M, Hamano SI, Kobayashi K. Pyridoxal in the Cerebrospinal Fluid May Be a Better Indicator of Vitamin B6-dependent Epilepsy Than Pyridoxal 5'-Phosphate. Pediatr Neurol 2020; 113:33-41. [PMID: 32980745 DOI: 10.1016/j.pediatrneurol.2020.08.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/26/2020] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND We aimed to demonstrate the biochemical characteristics of vitamin B6-dependent epilepsy, with a particular focus on pyridoxal 5'-phosphate and pyridoxal in the cerebrospinal fluid. METHODS Using our laboratory database, we identified patients with vitamin B6-dependent epilepsy and extracted their data on the concentrations of pyridoxal 5'-phosphate, pyridoxal, pipecolic acid, α-aminoadipic semialdehyde, and monoamine neurotransmitters. We compared the biochemical characteristics of these patients with those of other epilepsy patients with low pyridoxal 5'-phosphate concentrations. RESULTS We identified seven patients with pyridoxine-dependent epilepsy caused by an ALDH7A1 gene abnormality, two patients with pyridoxal 5'-phosphate homeostasis protein deficiency, and 28 patients with other epilepsies with low cerebrospinal fluid pyridoxal 5'-phosphate concentrations. Cerebrospinal fluid pyridoxal and pyridoxal 5'-phosphate concentrations were low in patients with vitamin B6-dependent epilepsy but cerebrospinal fluid pyridoxal concentrations were not reduced in most patients with other epilepsies with low cerebrospinal fluid pyridoxal 5'-phosphate concentrations. Increase in 3-O-methyldopa and 5-hydroxytryptophan was demonstrated in some patients with vitamin B6-dependent epilepsy, suggestive of pyridoxal 5'-phosphate deficiency in the brain. CONCLUSIONS Low cerebrospinal fluid pyridoxal concentrations may be a better indicator of pyridoxal 5'-phosphate deficiency in the brain in vitamin B6-dependent epilepsy than low cerebrospinal fluid pyridoxal 5'-phosphate concentrations. This finding is especially helpful in individuals with suspected pyridoxal 5'-phosphate homeostasis protein deficiency, which does not have known biomarkers.
Collapse
Affiliation(s)
- Tomoyuki Akiyama
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
| | - Yuki Hyodo
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Kosei Hasegawa
- Department of Pediatrics, Okayama University Hospital, Okayama, Japan
| | - Taikan Oboshi
- Department of Pediatric Neurology, Osaka Women's and Children's Hospital, Osaka, Japan; Department of Pediatrics, NHO Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan
| | - Katsumi Imai
- Department of Pediatrics, NHO Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan
| | - Naoko Ishihara
- Department of Pediatrics, Fujita Health University School of Medicine, Aichi, Japan
| | - Yuri Dowa
- Department of Neurology, Gunma Children's Medical Center, Gunma, Japan
| | - Takayoshi Koike
- Department of Pediatrics, NHO Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan
| | - Toshiyuki Yamamoto
- Institute of Clinical Genomics, Tokyo Women's Medical University, Tokyo, Japan
| | - Jun Shibasaki
- Department of Neonatology, Kanagawa Children's Medical Center, Kanagawa, Japan
| | - Hiroko Shimbo
- Clinical Institute, Kanagawa Children's Medical Center, Kanagawa, Japan
| | | | - Kyoko Takano
- Center for Medical Genetics, Shinshu University Hospital, Nagano, Japan
| | - Hiroshi Shiraku
- Department of Pediatrics, JA Toride Medical Center, Ibaraki, Japan
| | - Saoko Takeshita
- Department of Pediatrics, Yokohama City University Medical Center, Kanagawa, Japan
| | - Tohru Okanishi
- Department of Child Neurology, Comprehensive Epilepsy Center, Seirei Hamamatsu General Hospital, Shizuoka, Japan
| | - Shimpei Baba
- Department of Child Neurology, Comprehensive Epilepsy Center, Seirei Hamamatsu General Hospital, Shizuoka, Japan
| | - Masaya Kubota
- Division of Neurology, National Center for Child Health and Development, Tokyo, Japan
| | - Shin-Ichiro Hamano
- Division of Neurology, Saitama Children's Medical Center, Saitama, Japan
| | - Katsuhiro Kobayashi
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| |
Collapse
|
47
|
Voutsadakis IA. Amplification of 8p11.23 in cancers and the role of amplicon genes. Life Sci 2020; 264:118729. [PMID: 33166592 DOI: 10.1016/j.lfs.2020.118729] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/31/2020] [Accepted: 11/04/2020] [Indexed: 02/08/2023]
Abstract
Copy number alterations are widespread in cancer genomes and are part of the genomic instability underlying the pathogenesis of neoplastic diseases. Recurrent copy number alterations of specific chromosomal loci may result in gains of oncogenes or losses of tumor suppressor genes and become entrenched in the genomic framework of certain types of cancers. The locus at chromosome 8p11.23 presents recurrent amplifications most commonly in squamous lung carcinomas, breast cancers, squamous esophageal carcinomas, and urothelial carcinomas. Amplification is rare in other cancers. The amplified segment involves several described oncogenes that may promote cancer cell survival and proliferation, as well as less well characterized genes that could also contribute to neoplastic processes. Genes proposed to be "drivers" in 8p11.23 amplifications include ZNF703, FGFR1 and PLPP5. Additional genes in the locus that could be functionally important in neoplastic networks include co-chaperone BAG4, lysine methyltransferase NSD3, ASH2L, a member of another methyltransferase complex, MLL and the mRNA processing and translation regulators LSM1 and EIF4EBP1. In this paper, genes located in the amplified segment of 8p11.23 will be examined for their role in cancer and data arguing for their importance for cancers with the amplification will be presented.
Collapse
Affiliation(s)
- Ioannis A Voutsadakis
- Algoma District Cancer Program, Sault Area Hospital, Sault Ste. Marie, Ontario, Canada; Section of Internal Medicine, Division of Clinical Sciences, Northern Ontario School of Medicine, Sudbury, Ontario, Canada.
| |
Collapse
|
48
|
The Role of YggS in Vitamin B 6 Homeostasis in Salmonella enterica Is Informed by Heterologous Expression of Yeast SNZ3. J Bacteriol 2020; 202:JB.00383-20. [PMID: 32900833 DOI: 10.1128/jb.00383-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/28/2020] [Indexed: 11/20/2022] Open
Abstract
YggS (COG0325) is a pyridoxal 5'-phosphate (PLP)-binding protein proposed to be involved in homeostasis of B6 vitamers. In Salmonella enterica, lack of yggS resulted in phenotypes that were distinct and others that were similar to those of a yggS mutant of Escherichia coli Like other organisms, yggS mutants of S. enterica accumulate endogenous pyridoxine 5'-phosphate (PNP). Data herein show that strains lacking YggS accumulated ∼10-fold more PLP in growth medium than a parental strain. The deoxyxylulose 5-phosphate-dependent biosynthetic pathway for PLP and the PNP/pyridoxamine 5'-phosphate (PMP) oxidase credited with interconverting B6 vitamers were replaced with a single PLP synthase from Saccharomyces cerevisiae The impact of a yggS deletion on the intracellular and extracellular levels of B6 vitamers in this restructured strain supported a role for PdxH in PLP homeostasis and led to a general model for YggS function in PLP-PMP cycling. Our findings uncovered broader consequences of a yggS mutation than previously reported and suggest that the accumulation of PNP is not a direct effect of lacking YggS but rather a downstream consequence.IMPORTANCE Pyridoxal 5'-phosphate (PLP) is an essential cofactor for enzymes in all domains of life. Perturbations in PLP or B6 vitamer content can be detrimental, notably causing B6-dependent epilepsy in humans. YggS homologs are broadly conserved and have been implicated in altered levels of B6 vitamers in multiple organisms. The biochemical activity of YggS, expected to be conserved across domains, is not yet known. Herein, a simplified heterologous pathway minimized metabolic variables and allowed the dissection of this system to generate new metabolic knowledge that will be relevant to understanding YggS.
Collapse
|
49
|
Gawel K, Langlois M, Martins T, van der Ent W, Tiraboschi E, Jacmin M, Crawford AD, Esguerra CV. Seizing the moment: Zebrafish epilepsy models. Neurosci Biobehav Rev 2020; 116:1-20. [PMID: 32544542 DOI: 10.1016/j.neubiorev.2020.06.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/20/2020] [Accepted: 06/05/2020] [Indexed: 12/14/2022]
Abstract
Zebrafish are now widely accepted as a valuable animal model for a number of different central nervous system (CNS) diseases. They are suitable both for elucidating the origin of these disorders and the sequence of events culminating in their onset, and for use as a high-throughput in vivo drug screening platform. The availability of powerful and effective techniques for genome manipulation allows the rapid modelling of different genetic epilepsies and of conditions with seizures as a core symptom. With this review, we seek to summarize the current knowledge about existing epilepsy/seizures models in zebrafish (both pharmacological and genetic) and compare them with equivalent rodent and human studies. New findings obtained from the zebrafish models are highlighted. We believe that this comprehensive review will highlight the value of zebrafish as a model for investigating different aspects of epilepsy and will help researchers to use these models to their full extent.
Collapse
Affiliation(s)
- Kinga Gawel
- Chemical Neuroscience Group, Centre for Molecular Medicine Norway (NCMM), University of Oslo, Gaustadalléen 21, Forskningsparken, 0349, Oslo, Norway; Department of Experimental and Clinical Pharmacology, Medical University of Lublin, Jaczewskiego St. 8b, 20-090, Lublin, Poland
| | | | - Teresa Martins
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Belval, Luxembourg
| | - Wietske van der Ent
- Chemical Neuroscience Group, Centre for Molecular Medicine Norway (NCMM), University of Oslo, Gaustadalléen 21, Forskningsparken, 0349, Oslo, Norway
| | - Ettore Tiraboschi
- Chemical Neuroscience Group, Centre for Molecular Medicine Norway (NCMM), University of Oslo, Gaustadalléen 21, Forskningsparken, 0349, Oslo, Norway; Neurophysics Group, Center for Mind/Brain Sciences, University of Trento, Piazza Manifattura 1, Building 14, 38068, Rovereto, TN, Italy
| | - Maxime Jacmin
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Belval, Luxembourg
| | - Alexander D Crawford
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Belval, Luxembourg; Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | - Camila V Esguerra
- Chemical Neuroscience Group, Centre for Molecular Medicine Norway (NCMM), University of Oslo, Gaustadalléen 21, Forskningsparken, 0349, Oslo, Norway.
| |
Collapse
|
50
|
Labella JI, Cantos R, Salinas P, Espinosa J, Contreras A. Distinctive Features of PipX, a Unique Signaling Protein of Cyanobacteria. Life (Basel) 2020; 10:life10060079. [PMID: 32481703 PMCID: PMC7344720 DOI: 10.3390/life10060079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/23/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022] Open
Abstract
PipX is a unique cyanobacterial protein identified by its ability to bind to PII and NtcA, two key regulators involved in the integration of signals of the nitrogen/carbon and energy status, with a tremendous impact on nitrogen assimilation and gene expression in cyanobacteria. PipX provides a mechanistic link between PII, the most widely distributed signaling protein, and NtcA, a global transcriptional regulator of cyanobacteria. PII, required for cell survival unless PipX is inactivated or down-regulated, functions by protein–protein interactions with transcriptional regulators, transporters, and enzymes. In addition, PipX appears to be involved in a wider signaling network, supported by the following observations: (i) PII–PipX complexes interact with PlmA, an as yet poorly characterized transcriptional regulator also restricted to cyanobacteria; (ii) the pipX gene is functionally connected with pipY, a gene encoding a universally conserved pyridoxal phosphate binding protein (PLPBP) involved in vitamin B6 and amino acid homeostasis, whose loss-of-function mutations cause B6-dependent epilepsy in humans, and (iii) pipX is part of a relatively robust, six-node synteny network that includes pipY and four additional genes that might also be functionally connected with pipX. In this overview, we propose that the study of the protein–protein interaction and synteny networks involving PipX would contribute to understanding the peculiarities and idiosyncrasy of signaling pathways that are conserved in cyanobacteria.
Collapse
|