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Alsubhi S, Berrahmoune S, Dudley RWR, Dufresne D, Simard Tremblay E, Srour M, Myers KA. Utility of genetic testing in the pre-surgical evaluation of children with drug-resistant epilepsy. J Neurol 2024; 271:2503-2508. [PMID: 38261030 DOI: 10.1007/s00415-023-12174-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/24/2023] [Accepted: 12/26/2023] [Indexed: 01/24/2024]
Abstract
We evaluated the utility of genetic testing in the pre-surgical evaluation of pediatric patients with drug-resistant focal epilepsy. This single-center retrospective study reviewed the charts of all pediatric patients referred for epilepsy surgery evaluation over a 5-year period. We extracted and analyzed results of genetic testing as well as clinical, EEG, and neuroimaging data. Of 125 patients referred for epilepsy surgical evaluation, 86 (69%) had some form of genetic testing. Of these, 18 (21%) had a pathogenic or likely pathogenic variant identified. Genes affected included NPRL3 (3 patients, all related), TSC2 (3 patients), KCNH1, CHRNA4, SPTAN1, DEPDC5, SCN2A, ARX, SCN1A, DLG4, and ST5. One patient had ring chromosome 20, one a 7.17p12 duplication, and one a 15q13 deletion. In six patients, suspected epileptogenic lesions were identified on brain MRI that were thought to be unrelated to the genetic finding. A specific medical therapy choice was allowed due to genetic diagnosis in three patients who did not undergo surgery. Obtaining a molecular diagnosis may dramatically alter management in pediatric patients with drug-resistant focal epilepsy. Genetic testing should be incorporated as part of standard investigations in the pre-surgical work-up of pediatric patients with drug-resistant focal epilepsy.
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Affiliation(s)
- Sarah Alsubhi
- Division of Child Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - Saoussen Berrahmoune
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Roy W R Dudley
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Division of Neurosurgery, Department of Pediatric Surgery, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - David Dufresne
- Division of Child Neurology, Department of Pediatrics, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Elisabeth Simard Tremblay
- Division of Child Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
- Department of Neurology & Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, 1001 Boulevard Décarie, Montreal, QC, H4A 3J1, Canada
| | - Myriam Srour
- Division of Child Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Neurology & Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, 1001 Boulevard Décarie, Montreal, QC, H4A 3J1, Canada
| | - Kenneth A Myers
- Division of Child Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada.
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
- Department of Neurology & Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, 1001 Boulevard Décarie, Montreal, QC, H4A 3J1, Canada.
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Muller M, Bélanger J, Hadj-Aissa I, Zhang C, Sephton CF, Dutchak PA. GATOR1 Mutations Impair PI3 Kinase-Dependent Growth Factor Signaling Regulation of mTORC1. Int J Mol Sci 2024; 25:2068. [PMID: 38396745 PMCID: PMC10889792 DOI: 10.3390/ijms25042068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
GATOR1 (GAP Activity TOward Rag 1) is an evolutionarily conserved GTPase-activating protein complex that controls the activity of mTORC1 (mammalian Target Of Rapamycin Complex 1) in response to amino acid availability in cells. Genetic mutations in the GATOR1 subunits, NPRL2 (nitrogen permease regulator-like 2), NPRL3 (nitrogen permease regulator-like 3), and DEPDC5 (DEP domain containing 5), have been associated with epilepsy in humans; however, the specific effects of these mutations on GATOR1 function and mTORC1 regulation are not well understood. Herein, we report that epilepsy-linked mutations in the NPRL2 subunit of GATOR1, NPRL2-L105P, -T110S, and -D214H, increase basal mTORC1 signal transduction in cells. Notably, we show that NPRL2-L105P is a loss-of-function mutation that disrupts protein interactions with NPRL3 and DEPDC5, impairing GATOR1 complex assembly and resulting in high mTORC1 activity even under conditions of amino acid deprivation. Furthermore, our studies reveal that the GATOR1 complex is necessary for the rapid and robust inhibition of mTORC1 in response to growth factor withdrawal or pharmacological inhibition of phosphatidylinositol-3 kinase (PI3K). In the absence of the GATOR1 complex, cells are refractory to PI3K-dependent inhibition of mTORC1, permitting sustained translation and restricting the nuclear localization of TFEB, a transcription factor regulated by mTORC1. Collectively, our results show that epilepsy-linked mutations in NPRL2 can block GATOR1 complex assembly and restrict the appropriate regulation of mTORC1 by canonical PI3K-dependent growth factor signaling in the presence or absence of amino acids.
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Affiliation(s)
| | | | | | | | | | - Paul A. Dutchak
- Department of Psychiatry and Neuroscience, CERVO Brain Research Centre, Université Laval, Quebec City, QC G1J 2G3, Canada
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Du S, Zeng S, Song L, Ma H, Chen R, Luo J, Wang X, Ma T, Xu X, Sun H, Yi P, Guo J, Huang Y, Liu M, Wang T, Liao WP, Zhang L, Liu JY, Tang B. Functional characterization of novel NPRL3 mutations identified in three families with focal epilepsy. Sci China Life Sci 2023; 66:2152-2166. [PMID: 37071290 DOI: 10.1007/s11427-022-2313-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/01/2023] [Indexed: 04/19/2023]
Abstract
Focal epilepsy accounts for 60% of all forms of epilepsy, but the pathogenic mechanism is not well understood. In this study, three novel mutations in NPRL3 (nitrogen permease regulator-like 3), c.937_945del, c.1514dupC and 6,706-bp genomic DNA (gDNA) deletion, were identified in three families with focal epilepsy by linkage analysis, whole exome sequencing (WES) and Sanger sequencing. NPRL3 protein is a component of the GATOR1 complex, a major inhibitor of mTOR signaling. These mutations led to truncation of the NPRL3 protein and hampered the binding between NPRL3 and DEPDC5, which is another component of the GATOR1 complex. Consequently, the mutant proteins enhanced mTOR signaling in cultured cells, possibly due to impaired inhibition of mTORC1 by GATOR1. Knockdown of nprl3 in Drosophila resulted in epilepsy-like behavior and abnormal synaptic development. Taken together, these findings expand the genotypic spectrum of NPRL3-associated focal epilepsy and provide further insight into how NPRL3 mutations lead to epilepsy.
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Affiliation(s)
- Shiyue Du
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Sheng Zeng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, 410008, China
- Department of Geriatrics, The Second Xiangya Hospital, Central South University, Changsha, 410011, China
| | - Li Song
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Hongying Ma
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Rui Chen
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Junyu Luo
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Xu Wang
- National Reference Laboratory of Veterinary Drug Residues and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, 430070, China
| | - Tingbin Ma
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xuan Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Hao Sun
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Ping Yi
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Jifeng Guo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Yaling Huang
- Department of Neurology, Union Hospital of HUST, Wuhan, 430022, China
| | - Mugen Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Tao Wang
- Department of Neurology, Union Hospital of HUST, Wuhan, 430022, China
| | - Wei-Ping Liao
- Institute of Neuroscience and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou Medical University, Guangzhou, 510260, China
| | - Luoying Zhang
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China.
| | - Jing Yu Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, 410008, China.
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, 410008, China.
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Kovačević M, Janković M, Branković M, Milićević O, Novaković I, Sokić D, Ristić A, Shamsani J, Vojvodić N. Novel GATOR1 variants in focal epilepsy. Epilepsy Behav 2023; 141:109139. [PMID: 36848747 DOI: 10.1016/j.yebeh.2023.109139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/03/2023] [Accepted: 02/05/2023] [Indexed: 02/27/2023]
Abstract
INTRODUCTION Variants in GATOR1 genes are well established in focal epilepsy syndromes. A strong association of GATOR1 variants with drug-resistant epilepsy as well as an increased risk of sudden unexplained death in epilepsy warrants developing strategies to facilitate the identification of patients who could potentially benefit from genetic testing and precision medicine. We aimed to determine the yield of GATOR1 gene sequencing in patients with focal epilepsy typically referred for genetic testing, establish novel GATOR1 variants and determine clinical, electroencephalographic, and radiological characteristics of variant carriers. PATIENTS AND METHODS Ninety-six patients with clinical suspicion of genetic focal epilepsy with previous comprehensive diagnostic epilepsy evaluation in The Neurology Clinic, University Clinical Center of Serbia, were included in the study. Sequencing was performed using a custom gene panel encompassing DEPDC5, NPRL2, and NPRL3. Variants of interest (VOI) were classified according to criteria proposed by the American College of Medical Genetics and the Association for Molecular Pathology. RESULTS Four previously unreported VOI in 4/96 (4.2%) patients were found in our cohort. Three likely pathogenic variants were determined in 3/96 (3.1%) patients, one frameshift variant in DEPDC5 in a patient with nonlesional frontal lobe epilepsy, one splicogenic DEPDC5 variant in a patient with nonlesional posterior quadrant epilepsy, and one frameshift variant in NPRL2 in a patient with temporal lobe epilepsy associated with hippocampal sclerosis. Only one VOI, a missense variant in NPRL3, found in 1/96 (1.1%) patients, was classified as a variant of unknown significance. CONCLUSION GATOR1 gene sequencing was diagnostic in 3.1% of our cohort and revealed three novel likely pathogenic variants, including a previously unreported association of temporal lobe epilepsy with hippocampal sclerosis with an NPRL2 variant. Further research is essential for a better understanding of the clinical scope of GATOR1 gene-associated epilepsy.
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Affiliation(s)
- Maša Kovačević
- Neurology Clinic, University Clinical Center of Serbia, Serbia; Faculty of Medicine, University of Belgrade, Serbia.
| | - Milena Janković
- Neurology Clinic, University Clinical Center of Serbia, Serbia
| | | | | | | | - Dragoslav Sokić
- Neurology Clinic, University Clinical Center of Serbia, Serbia; Faculty of Medicine, University of Belgrade, Serbia
| | - Aleksandar Ristić
- Neurology Clinic, University Clinical Center of Serbia, Serbia; Faculty of Medicine, University of Belgrade, Serbia
| | | | - Nikola Vojvodić
- Neurology Clinic, University Clinical Center of Serbia, Serbia; Faculty of Medicine, University of Belgrade, Serbia
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5
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Mabika M, Agbogba K, Côté S, Lippé S, Riou É, Cieuta C, Lepage JF. Neurophysiological assessment of cortical activity in DEPDC5- and NPRL3-related epileptic mTORopathies. Orphanet J Rare Dis 2023; 18:11. [PMID: 36639812 DOI: 10.1186/s13023-022-02600-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 12/19/2022] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Mutations in the GATOR1 complex genes, DEPDC5 and NPRL3, play a major role in the development of lesional and non-lesional focal epilepsy through increased mTORC1 signalling. We aimed to assess the effects of mTORC1 hyperactivation on GABAergic inhibitory circuits, in 3 and 5 individuals carrying DEPDC5 and NPRL3 mutations respectively using a multimodal approach including transcranial magnetic stimulation (TMS), magnetic resonance spectroscopy (MRS), and electroencephalography (EEG). RESULTS Inhibitory functions probed by TMS and MRS showed no effect of mutations on cortical GABAergic receptor-mediated inhibition and GABA concentration, in both cortical and subcortical regions. However, stronger EEG theta oscillations and stronger and more synchronous gamma oscillations were observed in DEPDC5 and NPRL3 mutations carriers. CONCLUSIONS These results suggest that DEPDC5 and NPRL3-related epileptic mTORopathies may not directly modulate GABAergic functions but are nonetheless characterized by a stronger neural entrainment that may be reflective of a cortical hyperexcitability mediated by increased mTORC1 signaling.
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6
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Zhang H, Deng J, Wang X, Chen C, Chen S, Dai L, Fang F. Clinical phenotypic and genotypic characterization of NPRL3-related epilepsy. Front Neurol 2023; 14:1113747. [PMID: 36937533 PMCID: PMC10018541 DOI: 10.3389/fneur.2023.1113747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/09/2023] [Indexed: 03/06/2023] Open
Abstract
Background As one of the assembly factors of the GATOR1 protein complex in the mechanism of rapamycin pathway, NPRL3 plays an important role in the pathogenesis of epilepsy. However, the correlation between genotype and clinical phenotype in patients with NPRL3-related epilepsy has not been clarified. Methods A total of 11 Chinese children with NPRL3-related epilepsy were identified through whole-exome sequencing (WES). The data from the clinical presentation, laboratory data, brain imaging findings, genetic results, and treatment methods were collected. All previously reported cases with NPRL3-related epilepsy were collected and reviewed through PubMed search. Results Among the 11 children, eight have not been reported, and two of them presented infantile spasms (ISs) as a new phenotype of NPRL3-related epilepsy. In addition, WES identified five frameshift mutations, three nonsense mutations, two missense mutations, and one exon deletion. Based on bioinformatics analysis, it was found that two missense mutation sites were highly conserved, and the c.400G>A mutation site of the NPRL3 gene caused the alteration of the protein structure. To date, 88 patients have been reported with NPRL3-related defects, including our 11 cases. The most common presentations were sleep-related hypermotor epilepsy (SHE), frontal lobe epilepsy (FLE), and temporal lobe epilepsy. A majority of patients (70%) presented normal neuroimaging results, and focal cortical dysplasia was the most common neuroimaging abnormality (62.5%). Among the NPRL3 gene mutations, loss of function (nonsense mutations, frameshift mutations, and exons deletion) was the most common genetic variation (75%). For 73% of patients with NPRL3-related epilepsy, monotherapy of sodium channel blockers was effective. Surgery was effective for 75% of children with neuroimaging abnormalities. Two cases unresponsive to surgery or anti-seizure medications were treated with ketogenic diets (KD), which were effective. One case was treated with rapamycin at an early stage of epilepsy, which was effective as well. Conclusion NPRL3-related epilepsy has high clinical and genetic heterogeneity. SHE and FLE are the most common clinical presentations. Furthermore, ISs are the new phenotypes of NPRL3-related epilepsy, while the variants c.275G>A, c.745G>A, and c.1270C>T may be the most common NPRL3 gene mutations. Sodium channel blockers, surgery, KD, and rapamycin may be the potential treatments for these patients. Our study expanded the clinical and genetic spectrum of NPRL3-related epilepsy and provided important information for the precise treatment of patients.
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Affiliation(s)
- Hongwei Zhang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
- Epilepsy Center, Children's Hospital Affiliated to Shandong University, Jinan, China
- Epilepsy Center, Jinan Children's Hospital, Jinan, China
| | - Jie Deng
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Xiaohui Wang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Chunhong Chen
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Shuhua Chen
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Lifang Dai
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Fang Fang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
- *Correspondence: Fang Fang
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Abumurad S, Issa NP, Wu S, Rose S, Taylan Esengul Y, Nordli D, Warnke PC, Tao JX. Laser interstitial thermal therapy for NPRL3-related epilepsy with multiple seizure foci: A case report. Epilepsy Behav Rep 2021; 16:100459. [PMID: 34235417 PMCID: PMC8249776 DOI: 10.1016/j.ebr.2021.100459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/02/2021] [Accepted: 05/04/2021] [Indexed: 10/28/2022] Open
Abstract
Introduction: NPRL3 gene mutations cause autosomal dominant familial focal epilepsy of variable foci (FFEVF) and is characterized by focal epilepsy arising from different brain regions including temporal, frontal, parietal and occipital lobes. About 50% of patients with NPRL3 related epilepsy are resistant to medical treatment. Method: We present a case of 27 years old man with NPRL3 related focal drug-resistant epilepsy. Stereotactic EEG showed two independent seizure foci, namely, left hippocampus and left orbitofrontal cortices. He underwent laser interstitial thermal therapy for ablating both foci in the same procedure that led to seizure cessation. Conclusion: laser interstitial thermal therapy can be an effective treatment for drug resistant NPRL3 related focal epilepsy with better tolerance and less morbidity as compared to open surgical resection, particularly in those with multiple seizure foci.
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Affiliation(s)
- Sumayyah Abumurad
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - Naoum P Issa
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - Shasha Wu
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - Sandra Rose
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - Yasar Taylan Esengul
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - Douglas Nordli
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - Peter C Warnke
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
| | - James X Tao
- Departments of Neurology, Pediatrics, and Surgery, The University of Chicago, Chicago, IL 60637, USA
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8
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Myers KA, Bennett MF, Hildebrand MS, Coleman MJ, Zhou G, Hollingsworth G, Cairns A, Riney K, Berkovic SF, Bahlo M, Scheffer IE. Transcriptome analysis of a ring chromosome 20 patient cohort. Epilepsia 2020; 62:e22-e28. [PMID: 33207017 DOI: 10.1111/epi.16766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 09/03/2020] [Accepted: 11/02/2020] [Indexed: 11/27/2022]
Abstract
Ring chromosomes occur when the ends of normally rod-shaped chromosomes fuse. In ring chromosome 20 (ring 20), intellectual disability and epilepsy are usually present, even if there is no deleted coding material; the mechanism by which individuals with complete ring chromosomes develop seizures and other phenotypic abnormalities is not understood. We investigated altered gene transcription as a contributing factor by performing RNA-sequencing (RNA-seq) analysis on blood from seven patients with ring 20, and 11 first-degree relatives (all parents). Geographic analysis did not identify altered expression in peritelomeric or other specific chromosome 20 regions. RNA-seq analysis revealed 97 genes potentially differentially expressed in ring 20 patients. These included one epilepsy gene, NPRL3, but this finding was not confirmed on reverse transcription Droplet Digital polymerase chain reaction analysis. Molecular studies of structural chromosomal anomalies such as ring chromosome are challenging and often difficult to interpret because many patients are mosaic, and there may be genome-wide chromosomal instability affecting gene expression. Our findings nevertheless suggest that peritelomeric altered transcription is not the likely pathogenic mechanism in ring 20. Underlying genetic mechanisms are likely complex and may involve differential expression of many genes, the majority of which may not be located on chromosome 20.
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Affiliation(s)
- Kenneth A Myers
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia.,Research Institute of the McGill University Medical Centre, Montreal, QC, Canada.,Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - Mark F Bennett
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia.,Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Michael S Hildebrand
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Matthew J Coleman
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Geyu Zhou
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Georgie Hollingsworth
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Anita Cairns
- Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - Kate Riney
- Queensland Children's Hospital, Brisbane, Queensland, Australia.,University of Queensland, Brisbane, Queensland, Australia
| | - Samuel F Berkovic
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Ingrid E Scheffer
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia.,Department of Paediatrics, Royal Children's Hospital, University of Melbourne, Flemington, Victoria, Australia.,Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria, Australia
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9
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Bertuzzi M, Tang D, Calligaris R, Vlachouli C, Finaurini S, Sanges R, Goldwurm S, Catalan M, Antonutti L, Manganotti P, Pizzolato G, Pezzoli G, Persichetti F, Carninci P, Gustincich S. A human minisatellite hosts an alternative transcription start site for NPRL3 driving its expression in a repeat number-dependent manner. Hum Mutat 2020; 41:807-824. [PMID: 31898848 DOI: 10.1002/humu.23974] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 11/16/2019] [Accepted: 12/24/2019] [Indexed: 12/21/2022]
Abstract
Minisatellites, also called variable number of tandem repeats (VNTRs), are a class of repetitive elements that may affect gene expression at multiple levels and have been correlated to disease. Their identification and role as expression quantitative trait loci (eQTL) have been limited by their absence in comparative genomic hybridization and single nucleotide polymorphisms arrays. By taking advantage of cap analysis of gene expression (CAGE), we describe a new example of a minisatellite hosting a transcription start site (TSS) which expression is dependent on the repeat number. It is located in the third intron of the gene nitrogen permease regulator like protein 3 (NPRL3). NPRL3 is a component of the GAP activity toward rags 1 protein complex that inhibits mammalian target of rapamycin complex 1 (mTORC1) activity and it is found mutated in familial focal cortical dysplasia and familial focal epilepsy. CAGE tags represent an alternative TSS identifying TAGNPRL3 messenger RNAs (mRNAs). TAGNPRL3 is expressed in red blood cells both at mRNA and protein levels, it interacts with its protein partner NPRL2 and its overexpression inhibits cell proliferation. This study provides an example of a minisatellite that is both a TSS and an eQTL as well as identifies a new VNTR that may modify mTORC1 activity.
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Affiliation(s)
| | - Dave Tang
- Division of Genomic Technologies, RIKEN Center for Life Science Technologies, Yokohama, Japan
| | - Raffaella Calligaris
- Area of Neuroscience, SISSA, Trieste, Italy.,Department of Medical Sciences, Neurology Unit, University of Trieste, Trieste, Italy
| | | | - Sara Finaurini
- Area of Neuroscience, SISSA, Trieste, Italy.,Department of Health Sciences, Università del Piemonte Orientale and IRCAD, Novara, Italy
| | - Remo Sanges
- Area of Neuroscience, SISSA, Trieste, Italy.,Central RNA Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | | | - Mauro Catalan
- Department of Medical Sciences, Neurology Unit, University of Trieste, Trieste, Italy
| | - Lucia Antonutti
- Department of Medical Sciences, Neurology Unit, University of Trieste, Trieste, Italy
| | - Paolo Manganotti
- Department of Medical Sciences, Neurology Unit, University of Trieste, Trieste, Italy
| | - Gilberto Pizzolato
- Department of Medical Sciences, Neurology Unit, University of Trieste, Trieste, Italy
| | - Gianni Pezzoli
- Parkinson Institute, ASST G. Pini-CTO, ex ICP, Milan, Italy
| | - Francesca Persichetti
- Department of Health Sciences, Università del Piemonte Orientale and IRCAD, Novara, Italy
| | - Piero Carninci
- Division of Genomic Technologies, RIKEN Center for Life Science Technologies, Yokohama, Japan.,Laboratory for Transcriptome Technology, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Japan
| | - Stefano Gustincich
- Area of Neuroscience, SISSA, Trieste, Italy.,Central RNA Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
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10
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Iffland PH, Carson V, Bordey A, Crino PB. GATORopathies: The role of amino acid regulatory gene mutations in epilepsy and cortical malformations. Epilepsia 2019; 60:2163-2173. [PMID: 31625153 PMCID: PMC7155771 DOI: 10.1111/epi.16370] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 09/20/2019] [Accepted: 09/20/2019] [Indexed: 12/11/2022]
Abstract
The mechanistic target of rapamycin (mTOR) pathway has been implicated in a growing number of malformations of cortical development (MCD) associated with intractable epilepsy. Mutations in single genes encoding mTOR pathway regulatory proteins have been linked to MCD such as focal cortical dysplasia (FCD) types IIa and IIb, hemimegalencephaly (HME), and megalencephaly. Recent studies have demonstrated that the GATOR1 protein complex, comprised of DEPDC5, NPRL3, and NPRL2, plays a pivotal role in regulating mTOR signaling in response to cellular amino acid levels and that mutations in DEPDC5, NPRL3, or NPRL2 are linked to FCD, HME, and seizures. Histopathological analysis of FCD and HME tissue specimens resected from individuals harboring DEPDC5, NPRL3, or NPRL2 gene mutations reveals hyperactivation of mTOR pathway signaling. Family pedigrees carrying mutations in either DEPDC5 or NPRL3 share clinical phenotypes of epilepsy and MCD, as well as intellectual and neuropsychiatric disabilities. Interestingly, some individuals with seizures associated with DEPDC5, NPRL3, or NPRL2 variants exhibit normal brain imaging suggesting either occult MCD or a role for these genes in non-lesional neocortical epilepsy. Mouse models resulting from knockdown or knockout of either Depdc5 or Nprl3 exhibit altered cortical lamination, neuronal dysmorphogenesis, and enhanced neuronal excitability as reported in models resulting from direct mTOR activation through expression of its canonical activator RHEB. The role of the GATOR1 proteins in regulating mTOR signaling suggest plausible options for mTOR inhibition in the treatment of epilepsy associated with mutations in DEPDC5, NPRL3, or NPRL2.
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Affiliation(s)
- Philip H. Iffland
- Department of Neurology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Vincent Carson
- The Clinic for Special Children, Strasburg, Pennsylvania
| | - Angelique Bordey
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut
| | - Peter B. Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, Maryland
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11
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Abstract
INTRODUCTION Dishevelled, Egl-10 and Pleckstrin (DEP) domain-containing protein 5 (DEPDC5) is a protein subunit of the GTPase-activating proteins towards Rags 1 (GATOR1) complex. GATOR1 is a recently identified modulator of mechanistic target of rapamycin (mTOR) activity. mTOR is a key regulator of cell proliferation and metabolism; disruption of the mTOR pathway is implicated in focal epilepsy, both acquired and genetic. Tuberous sclerosis is the prototypic mTOR genetic syndrome with epilepsy, however GATOR1 gene mutations have recently been shown to cause lesional and non-lesional focal epilepsy. Areas covered: This review summarizes the mTOR pathway, including regulators and downstream effectors, emphasizing recent developments in the understanding of the complex role of the GATOR1 complex. We review the epilepsy types associated with mTOR overactivity, including tuberous sclerosis, polyhydramnios megalencephaly symptomatic epilepsy, cortical dysplasia, non-lesional focal epilepsy and post-traumatic epilepsy. Currently available mTOR inhibitors are discussed, primarily rapamycin analogs and ATP competitive mTOR inhibitors. Expert opinion: DEPDC5 is an attractive therapeutic target in focal epilepsy, as effects of DEPDC5 agonists would likely be anti-epileptogenic and more selective than currently available mTOR inhibitors. Therapeutic effects might be synergistic with certain existing dietary therapies, including the ketogenic diet.
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Affiliation(s)
- Kenneth A Myers
- a Epilepsy Research Centre, Department of Medicine , The University of Melbourne, Austin Health , Heidelberg , Victoria , Australia.,b Department of Paediatrics , Royal Children's Hospital, The University of Melbourne , Flemington , Victoria , Australia
| | - Ingrid E Scheffer
- a Epilepsy Research Centre, Department of Medicine , The University of Melbourne, Austin Health , Heidelberg , Victoria , Australia.,b Department of Paediatrics , Royal Children's Hospital, The University of Melbourne , Flemington , Victoria , Australia.,c The Florey Institute of Neuroscience and Mental Health , Heidelberg , Victoria , Australia
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12
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Korenke GC, Eggert M, Thiele H, Nürnberg P, Sander T, Steinlein OK. Nocturnal frontal lobe epilepsy caused by a mutation in the GATOR1 complex gene NPRL3. Epilepsia 2016; 57:e60-3. [PMID: 26786403 DOI: 10.1111/epi.13307] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2015] [Indexed: 01/16/2023]
Abstract
Mutations in NPRL3, one of three genes that encode proteins of the mTORC1-regulating GATOR1 complex, have recently been reported to cause cortical dysplasia with focal epilepsy. We have now analyzed a multiplex epilepsy family by whole exome sequencing and identified a frameshift mutation (NM_001077350.2; c.1522delG; p.E508Rfs*46) within exon 13 of NPRL3. This truncating mutation causes an epilepsy phenotype characterized by early childhood onset of mainly nocturnal frontal lobe epilepsy. The penetrance in our family was low (three affected out of six mutation carriers), compared to families with either ion channel- or DEPDC5-associated familial nocturnal frontal lobe epilepsy. The absence of apparent structural brain abnormalities suggests that mutations in NPRL3 are not necessarily associated with focal cortical dysplasia but might be able to cause epilepsy by different, yet unknown pathomechanisms.
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Affiliation(s)
| | - Marlene Eggert
- Institute of Human Genetics, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Holger Thiele
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thomas Sander
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
| | - Ortrud K Steinlein
- Institute of Human Genetics, Ludwig-Maximilians-University Hospital, Munich, Germany
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13
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Levine TP, Daniels RD, Wong LH, Gatta AT, Gerondopoulos A, Barr FA. Discovery of new Longin and Roadblock domains that form platforms for small GTPases in Ragulator and TRAPP-II. Small GTPases 2013; 4:62-9. [PMID: 23511850 PMCID: PMC3747258 DOI: 10.4161/sgtp.24262] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Guanine nucleotide exchange factors (GEFs) control the site and extent of GTPase activity. Longin domains (LDs) are found in many Rab-GEFs, including DENNs, MON1/CCZ1, BLOC-3 and the TRAPP complex. Other GEFs, including Ragulator, contain roadblock domains (RDs), the structure of which is closely related to LDs. Other GTPase regulators, including mglB, SRX and Rags, use LDs or RDs as platforms for GTPases. Here, we review the conserved relationship between GTPases and LD/RDs, showing how LD/RD dimers act as adaptable platforms for GTPases. To extend our knowledge of GEFs, we used a highly sensitive sequence alignment tool to predict the existence of new LD/RDs. We discovered two yeast Ragulator subunits, and also a new LD in TRAPPC10 that may explain the Rab11-GEF activity ascribed to TRAPP-II.
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