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Passchier EMJ, Bisseling Q, Helman G, van Spaendonk RML, Simons C, Olsthoorn RCL, van der Veen H, Abbink TEM, van der Knaap MS, Min R. Megalencephalic leukoencephalopathy with subcortical cysts: a variant update and review of the literature. Front Genet 2024; 15:1352947. [PMID: 38487253 PMCID: PMC10938252 DOI: 10.3389/fgene.2024.1352947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 01/29/2024] [Indexed: 03/17/2024] Open
Abstract
The leukodystrophy megalencephalic leukoencephalopathy with subcortical cysts (MLC) is characterized by infantile-onset macrocephaly and chronic edema of the brain white matter. With delayed onset, patients typically experience motor problems, epilepsy and slow cognitive decline. No treatment is available. Classic MLC is caused by bi-allelic recessive pathogenic variants in MLC1 or GLIALCAM (also called HEPACAM). Heterozygous dominant pathogenic variants in GLIALCAM lead to remitting MLC, where patients show a similar phenotype in early life, followed by normalization of white matter edema and no clinical regression. Rare patients with heterozygous dominant variants in GPRC5B and classic MLC were recently described. In addition, two siblings with bi-allelic recessive variants in AQP4 and remitting MLC have been identified. The last systematic overview of variants linked to MLC dates back to 2006. We provide an updated overview of published and novel variants. We report on genetic variants from 508 patients with MLC as confirmed by MRI diagnosis (258 from our database and 250 extracted from 64 published reports). We describe 151 unique MLC1 variants, 29 GLIALCAM variants, 2 GPRC5B variants and 1 AQP4 variant observed in these MLC patients. We include experiments confirming pathogenicity for some variants, discuss particularly notable variants, and provide an overview of recent scientific and clinical insight in the pathophysiology of MLC.
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Affiliation(s)
- Emma M. J. Passchier
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Quinty Bisseling
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Guy Helman
- Translational Bioinformatics, Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC, Australia
| | | | - Cas Simons
- Translational Bioinformatics, Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research, Sydney, NSW, Australia
| | | | - Hieke van der Veen
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Truus E. M. Abbink
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Marjo S. van der Knaap
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Rogier Min
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
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Ishikawa M, Omachi Y, Sato N, Nakagawa E. Bipolar disorder in megalencephalic leukoencephalopathy with subcortical cysts: a case report. BMC Psychiatry 2020; 20:349. [PMID: 32620087 PMCID: PMC7333431 DOI: 10.1186/s12888-020-02750-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 06/23/2020] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Megalencephalic leukoencephalopathy with subcortical cysts (MLC), or Van der Knaap disease, is a rare spongiform leukodystrophy that is characterized by macrocephaly, progressive motor dysfunction, and mild mental retardation. It is very rare for mental illness such as psychotic disorders, affective disorders and anxiety disorders to occur in MLC. CASE PRESENTATION A 17-year-old boy was admitted to our hospital after he developed symptoms of depressive state with catatonia after being diagnosed as having MLC with confirmed MLC1 mutation. His catatonic symptoms were improved with administration of olanzapine and sertraline and he was discharged after 4 months. Several months later, he became hypomanic. He was diagnosed with bipolar II disorder. Mood swings were controlled with the administration of carbamazepine. CONCLUSIONS This case is the first report of bipolar disorder during the clinical course of MLC. This case indicate the possibility that MLC influences the development of bipolar disorder in MLC, however, further studies involving more patients are required to clarify this.
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Affiliation(s)
- Masanori Ishikawa
- Department of Social Welfare Service, Faculty of Human Sciences, Mejiro University, 4-31-1 Nakaochiai, Shinjuku-ku, Tokyo, 161-8539, Japan.
| | - Yoshie Omachi
- grid.419280.60000 0004 1763 8916Department of Psychiatry, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry, Tokyo, 187-8551 Japan
| | - Noriko Sato
- grid.419280.60000 0004 1763 8916Department of Radiology, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry, Tokyo, 187-8551 Japan
| | - Eiji Nakagawa
- grid.419280.60000 0004 1763 8916Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry, Tokyo, 187-8551 Japan
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Metabolic crisis after trivial head trauma in late-onset isolated sulfite oxidase deficiency: Report of two new cases and review of published patients. Brain Dev 2020; 42:157-164. [PMID: 31806255 DOI: 10.1016/j.braindev.2019.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/25/2019] [Accepted: 11/18/2019] [Indexed: 11/23/2022]
Abstract
BACKGROUND Isolated sulfite oxidase deficiency (ISOD) is a rare autosomal recessively inherited inborn error of metabolism, caused by mutation in SUOX gene. ISOD has two kind of presentation; early and late-onset. The late-onset form is extremely rare and only 10 cases have been reported. METHODS We report two new cases of late-onset ISOD with biochemical and genetic confirmation. We did a review of the previously published cases of late-onset ISOD. RESULTS Together with the presented two cases, 12 cases were available for analysis. The median age at symptom onset and at diagnosis was 8.5 and 23 months respectively. Almost all children had acute regression of milestones followed by slow recovery. The common presenting signs and symptoms were movement disorders, seizures, ectopia lentis and hypertonia. Five children had antecedent events. Trivial trauma precipitating the metabolic crisis was unique to the two cases we report. The most common MRI feature was globus pallidi changes followed by cerebellar white matter changes, vermian hypoplasia and thinned out corpus callosum. Diffusion weighted sequence was performed in 3 children and all had diffusion restriction in the affected area. CONCLUSION Trivial trauma can precipitate metabolic crisis in late-onset ISOD. Low plasma homocysteine and involvement of globus pallidi with diffusion restriction on the MRI are important diagnostic clues. Early diagnosis and intervention with special diet may be effective in preventing long term neurodisability.
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Megalencephalic Leukoencephalopathy with Subcortical Cysts Protein-1 (MLC1) Counteracts Astrocyte Activation in Response to Inflammatory Signals. Mol Neurobiol 2019; 56:8237-8254. [DOI: 10.1007/s12035-019-01657-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 05/20/2019] [Indexed: 01/08/2023]
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Dubey M, Brouwers E, Hamilton EM, Stiedl O, Bugiani M, Koch H, Kole MH, Boschert U, Wykes RC, Mansvelder HD, van der Knaap MS, Min R. Seizures and disturbed brain potassium dynamics in the leukodystrophy megalencephalic leukoencephalopathy with subcortical cysts. Ann Neurol 2018; 83:636-649. [PMID: 29466841 PMCID: PMC5900999 DOI: 10.1002/ana.25190] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 01/12/2018] [Accepted: 02/18/2018] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Loss of function of the astrocyte-specific protein MLC1 leads to the childhood-onset leukodystrophy "megalencephalic leukoencephalopathy with subcortical cysts" (MLC). Studies on isolated cells show a role for MLC1 in astrocyte volume regulation and suggest that disturbed brain ion and water homeostasis is central to the disease. Excitability of neuronal networks is particularly sensitive to ion and water homeostasis. In line with this, reports of seizures and epilepsy in MLC patients exist. However, systematic assessment and mechanistic understanding of seizures in MLC are lacking. METHODS We analyzed an MLC patient inventory to study occurrence of seizures in MLC. We used two distinct genetic mouse models of MLC to further study epileptiform activity and seizure threshold through wireless extracellular field potential recordings. Whole-cell patch-clamp recordings and K+ -sensitive electrode recordings in mouse brain slices were used to explore the underlying mechanisms of epilepsy in MLC. RESULTS An early onset of seizures is common in MLC. Similarly, in MLC mice, we uncovered spontaneous epileptiform brain activity and a lowered threshold for induced seizures. At the cellular level, we found that although passive and active properties of individual pyramidal neurons are unchanged, extracellular K+ dynamics and neuronal network activity are abnormal in MLC mice. INTERPRETATION Disturbed astrocyte regulation of ion and water homeostasis in MLC causes hyperexcitability of neuronal networks and seizures. These findings suggest a role for defective astrocyte volume regulation in epilepsy. Ann Neurol 2018;83:636-649.
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Affiliation(s)
- Mohit Dubey
- Department of Child Neurology, Amsterdam NeuroscienceVU University Medical CenterAmsterdamThe Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
- Present address:
Current address for Mohit Dubey: Department of Axonal SignalingNetherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and SciencesAmsterdamThe Netherlands
| | - Eelke Brouwers
- Department of Child Neurology, Amsterdam NeuroscienceVU University Medical CenterAmsterdamThe Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
| | - Eline M.C. Hamilton
- Department of Child Neurology, Amsterdam NeuroscienceVU University Medical CenterAmsterdamThe Netherlands
| | - Oliver Stiedl
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
| | - Marianna Bugiani
- Department of Child Neurology, Amsterdam NeuroscienceVU University Medical CenterAmsterdamThe Netherlands
- Department of PathologyVU University Medical CenterAmsterdamThe Netherlands
| | - Henner Koch
- Department of NeurologyUniversity of Tübingen, Hertie Institute for Clinical Brain ResearchTübingenGermany
| | - Maarten H.P. Kole
- Department of Axonal SignalingNetherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and SciencesAmsterdamThe Netherlands
- Cell Biology, Faculty of ScienceUtrecht UniversityUtrechtThe Netherlands
| | - Ursula Boschert
- Translational Innovation Platform Immunology/Neurology, EMD Serono Research & Development InstituteBillericaMA
| | - Robert C. Wykes
- Department of Clinical & Experimental Epilepsy, UCL Institute of NeurologyUniversity College LondonLondonUnited Kingdom
| | - Huibert D. Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
| | - Marjo S. van der Knaap
- Department of Child Neurology, Amsterdam NeuroscienceVU University Medical CenterAmsterdamThe Netherlands
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
| | - Rogier Min
- Department of Child Neurology, Amsterdam NeuroscienceVU University Medical CenterAmsterdamThe Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam NeuroscienceVU UniversityAmsterdamThe Netherlands
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Cao B, Yan H, Guo M, Xie H, Wu Y, Gu Q, Xiao J, Shang J, Yang Y, Xiong H, Niu Z, Wu X, Jiang Y, Wang J. Ten Novel Mutations in Chinese Patients with Megalencephalic Leukoencephalopathy with Subcortical Cysts and a Long-Term Follow-Up Research. PLoS One 2016; 11:e0157258. [PMID: 27322623 PMCID: PMC4913951 DOI: 10.1371/journal.pone.0157258] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/26/2016] [Indexed: 11/21/2022] Open
Abstract
Objective Megalencephalic leukoencephalopathy with subcortical cysts (MLC, OMIM 604004) is a rare neurological deterioration disease. We aimed to clarify clinical and genetic features of Chinese MLC patients. Methods Clinical information and peripheral venous blood of 20 patients and their families were collected, Sanger-sequencing and Multiple Ligation-dependent Probe Amplification were performed to make genetic analysis. Splicing-site mutation was confirmed with RT-PCR. UPD was detected by haplotype analysis. Follow-up study was performed through telephone for 27 patients. Results Out of 20 patients, macrocephaly, classic MRI features, motor development delay and cognitive impairment were detected in 20(100%), 20(100%), 17(85%) and 4(20%) patients, respectively. 20(100%) were clinically diagnosed with MLC. 19(95%) were genetically diagnosed with 10 novel mutations in MLC1, MLC1 and GlialCAM mutations were identified in 15 and 4 patients, respectively. Deletion mutation from exon4 to exon9 and a homozygous point mutation due to maternal UPD of chromosome22 in MLC1 were found firstly. c.598-2A>C in MLC1 leads to the skip of exon8. c.772-1G>C in MLC1 accounting for 15.5%(9/58) alleles in Chinese patients might be a founder or a hot-spot mutation. Out of 27 patients in the follow-up study, head circumference was ranged from 56cm to 61cm in patients older than 5yeas old, with a median of 57cm. Motor development delay and cognitive impairment were detected in 22(81.5%) and 5(18.5%) patients, respectively. Motor and cognitive deterioration was found in 5 (18.5%) and 2 patients (7.4%), respectively. Improvements and MRI recovery were first found in Chinese patients. Rate of seizures (45.5%), transient motor retrogress (45.5%) and unconsciousness (13.6%) after head trauma was much higher than that after fever (18.2%, 9.1%, 0%, respectively). Significance It’s a clinical and genetic analysis and a follow-up study for largest sample of Chinese MLC patients, identifying 10 novel mutations, expanding mutation spectrums and discovering clinical features of Chinese MLC patients.
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Affiliation(s)
- Binbin Cao
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Huifang Yan
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Mangmang Guo
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
- Department of Pediatrics, Beijing Tian Tan Hospital, Capital Medical University Beijing 100050, China
| | - Han Xie
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Ye Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Qiang Gu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Jiangxi Xiao
- Department of Radiology, Peking University First Hospital, Beijing 100034, China
| | - Jing Shang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
- Department of Neurology, Shanxi Dayi Hospital, Taiyuan 030000, Shanxi Province, China
| | - Yanling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Hui Xiong
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Zhengping Niu
- Department of Neurology, First Hospital of Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
| | - Xiru Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
- * E-mail: (YWJ); (JMW)
| | - Jingmin Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
- * E-mail: (YWJ); (JMW)
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Lanciotti A, Brignone MS, Visentin S, De Nuccio C, Catacuzzeno L, Mallozzi C, Petrini S, Caramia M, Veroni C, Minnone G, Bernardo A, Franciolini F, Pessia M, Bertini E, Petrucci TC, Ambrosini E. Megalencephalic leukoencephalopathy with subcortical cysts protein-1 regulates epidermal growth factor receptor signaling in astrocytes. Hum Mol Genet 2016; 25:1543-58. [DOI: 10.1093/hmg/ddw032] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/03/2016] [Indexed: 01/13/2023] Open
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Brignone MS, Lanciotti A, Camerini S, De Nuccio C, Petrucci TC, Visentin S, Ambrosini E. MLC1 protein: a likely link between leukodystrophies and brain channelopathies. Front Cell Neurosci 2015; 9:66. [PMID: 25883547 PMCID: PMC4381631 DOI: 10.3389/fncel.2015.00106] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 03/09/2015] [Indexed: 01/12/2023] Open
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts (MLCs) disease is a rare inherited, autosomal recessive form of childhood-onset spongiform leukodystrophy characterized by macrocephaly, deterioration of motor functions, epileptic seizures and mental decline. Brain edema, subcortical fluid cysts, myelin and astrocyte vacuolation are the histopathological hallmarks of MLC. Mutations in either the MLC1 gene (>75% of patients) or the GlialCAM gene (<20% of patients) are responsible for the disease. Recently, the GlialCAM adhesion protein was found essential for the membrane expression and function of the chloride channel ClC-2 indicating MLC disease caused by mutation in GlialCAM as the first channelopathy among leukodystrophies. On the contrary, the function of MLC1 protein, which binds GlialCAM, its functional relationship with ClC-2 and the molecular mechanisms underlying MLC1 mutation-induced functional defects are not fully understood yet. The human MLC1 gene encodes a 377-amino acid membrane protein with eight predicted transmembrane domains which shows very low homology with voltage-dependent potassium (K+) channel subunits. The high expression of MLC1 in brain astrocytes contacting blood vessels and meninges and brain alterations observed in MLC patients have led to hypothesize a role for MLC1 in the regulation of ion and water homeostasis. Recent studies have shown that MLC1 establishes structural and/or functional interactions with several ion/water channels and transporters and ion channel accessory proteins, and that these interactions are affected by MLC1 mutations causing MLC. Here, we review data on MLC1 functional properties obtained in in vitro and in vivo models and discuss evidence linking the effects of MLC1 mutations to brain channelopathies.
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Affiliation(s)
- Maria S Brignone
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
| | - Angela Lanciotti
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
| | - Serena Camerini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
| | - Chiara De Nuccio
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
| | - Tamara C Petrucci
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
| | - Sergio Visentin
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
| | - Elena Ambrosini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità Rome, Italy
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Eight novel mutations in MLC1 from 18 Iranian patients with megalencephalic leukoencephalopathy with subcortical cysts. Eur J Med Genet 2015; 58:71-4. [DOI: 10.1016/j.ejmg.2014.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 12/04/2014] [Indexed: 11/18/2022]
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Brignone MS, Lanciotti A, Visentin S, De Nuccio C, Molinari P, Camerini S, Diociaiuti M, Petrini S, Minnone G, Crescenzi M, Laudiero LB, Bertini E, Petrucci TC, Ambrosini E. Megalencephalic leukoencephalopathy with subcortical cysts protein-1 modulates endosomal pH and protein trafficking in astrocytes: relevance to MLC disease pathogenesis. Neurobiol Dis 2014; 66:1-18. [PMID: 24561067 PMCID: PMC4003525 DOI: 10.1016/j.nbd.2014.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/20/2014] [Accepted: 02/10/2014] [Indexed: 11/28/2022] Open
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare leukodystrophy caused by mutations in the gene encoding MLC1, a membrane protein mainly expressed in astrocytes in the central nervous system. Although MLC1 function is unknown, evidence is emerging that it may regulate ion fluxes. Using biochemical and proteomic approaches to identify MLC1 interactors and elucidate MLC1 function we found that MLC1 interacts with the vacuolar ATPase (V-ATPase), the proton pump that regulates endosomal acidity. Because we previously showed that in intracellular organelles MLC1 directly binds Na, K-ATPase, which controls endosomal pH, we studied MLC1 endosomal localization and trafficking and MLC1 effects on endosomal acidity and function using human astrocytoma cells overexpressing wild-type (WT) MLC1 or MLC1 carrying pathological mutations. We found that WT MLC1 is abundantly expressed in early (EEA1(+), Rab5(+)) and recycling (Rab11(+)) endosomes and uses the latter compartment to traffic to the plasma membrane during hyposmotic stress. We also showed that WT MLC1 limits early endosomal acidification and influences protein trafficking in astrocytoma cells by stimulating protein recycling, as revealed by FITC-dextran measurement of endosomal pH and transferrin protein recycling assay, respectively. WT MLC1 also favors recycling to the plasma-membrane of the TRPV4 cation channel which cooperates with MLC1 to activate calcium influx in astrocytes during hyposmotic stress. Although MLC disease-causing mutations differentially affect MLC1 localization and trafficking, all the mutated proteins fail to influence endosomal pH and protein recycling. This study demonstrates that MLC1 modulates endosomal pH and protein trafficking suggesting that alteration of these processes contributes to MLC pathogenesis.
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Affiliation(s)
- Maria S Brignone
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Angela Lanciotti
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Sergio Visentin
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Chiara De Nuccio
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Paola Molinari
- Department of Pharmacology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Serena Camerini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Marco Diociaiuti
- Department of Technology and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Stefania Petrini
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Gaetana Minnone
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Marco Crescenzi
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Luisa Bracci Laudiero
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy; Institute of Translational Pharmacology, CNR, Via del Fosso Cavaliere 100, 00133 Rome, Italy.
| | - Enrico Bertini
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Tamara C Petrucci
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Elena Ambrosini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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Bajaj SK, Misra R, Gupta R, Chandra R, Malik A. Megalencephalic leukoencephalopathy with sub cortical cysts: An inherited dysmyelinating disorder. J Pediatr Neurosci 2013; 8:77-80. [PMID: 23772256 PMCID: PMC3680908 DOI: 10.4103/1817-1745.111438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Sunil Kumar Bajaj
- Department of Radiodiagnosis, Safdarjung Hospital and VM Medical College, New Delhi, India
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Abstract
Astrocytes are the predominant glial cell population in the central nervous system (CNS). Once considered only passive scaffolding elements, astrocytes are now recognised as cells playing essential roles in CNS development and function. They control extracellular water and ion homeostasis, provide substrates for energy metabolism, and regulate neurogenesis, myelination and synaptic transmission. Due to these multiple activities astrocytes have been implicated in almost all brain pathologies, contributing to various aspects of disease initiation, progression and resolution. Evidence is emerging that astrocyte dysfunction can be the direct cause of neurodegeneration, as shown in Alexander's disease where myelin degeneration is caused by mutations in the gene encoding the astrocyte-specific cytoskeleton protein glial fibrillary acidic protein. Recent studies point to a primary role for astrocytes in the pathogenesis of other genetic leukodystrophies such as megalencephalic leukoencephalopathy with subcortical cysts and vanishing white matter disease. The aim of this review is to summarize current knowledge of the pathophysiological role of astrocytes focusing on their contribution to the development of the above mentioned leukodystrophies and on new perspectives for the treatment of neurological disorders.
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van der Knaap MS, Boor I, Estévez R. Megalencephalic leukoencephalopathy with subcortical cysts: chronic white matter oedema due to a defect in brain ion and water homoeostasis. Lancet Neurol 2012; 11:973-85. [PMID: 23079554 DOI: 10.1016/s1474-4422(12)70192-8] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is characterised by chronic white matter oedema. The disease has an infantile onset and leads to slow neurological deterioration in most cases, but, surprisingly, some patients recover. The first disease gene, MLC1, identified in 2001, is mutated in 75% of patients. At that time, nothing was known about MLC1 protein function and the pathophysiology of MLC. More recently, HEPACAM (also called GLIALCAM) has been identified as a second disease gene. GlialCAM serves as an escort for MLC1 and the chloride channel CLC2. The defect in MLC1 has been shown to hamper the cell volume regulation of astrocytes. One of the most important consequences involves the potassium siphoning process, which is essential in brain ion and water homoeostasis. An understanding of the mechanisms of white matter oedema in MLC is emerging. Further insight into the specific function of MLC1 is necessary to find treatment targets.
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Affiliation(s)
- Marjo S van der Knaap
- Department of Pediatrics/Child Neurology, VU University Medical Centre, Amsterdam, Netherlands.
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Mancini C, Vaula G, Scalzitti L, Cavalieri S, Bertini E, Aiello C, Lucchini C, Gatti RA, Brussino A, Brusco A. Megalencephalic leukoencephalopathy with subcortical cysts type 1 (MLC1) due to a homozygous deep intronic splicing mutation (c.895-226T>G) abrogated in vitro using an antisense morpholino oligonucleotide. Neurogenetics 2012; 13:205-14. [PMID: 22552818 DOI: 10.1007/s10048-012-0331-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/16/2012] [Indexed: 11/24/2022]
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts is an autosomal recessive disease characterized by early onset macrocephaly; developmental delay; motor disability in the form of progressive spasticity and ataxia; seizures; cognitive decline; and characteristic magnetic resonance imaging findings. Mutations in two genes, MLC1 (22q13.33; 75 % of patients) or HEPACAM (11q24; 20 % of patients), are associated with the disease. We describe an adult MLC patient with moderate clinical symptoms. MLC1 cDNA analysis from lymphoblasts showed a strong transcript reduction and identified a 246-bp pseudoexon containing a premature stop codon between exons 10 and 11, due to a homozygous c.895-226 T>G deep-intronic mutation. This category of mutations is often overlooked, being outside of canonically sequenced genomic regions. The mutation c.895-226 T>G has a leaky effect on splicing leaving part of the full-length transcript. Its role on splicing was confirmed using a minigene assay and an antisense morpholinated oligonucleotide targeted to the aberrant splice site in vitro, which partially abrogated the mutation effect.
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Affiliation(s)
- Cecilia Mancini
- Department of Genetics, Biology and Biochemistry, University of Torino, via Santena, 19-10126 Torino, Italy
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Gorospe JR, Maletkovic J. Alexander disease and megalencephalic leukoencephalopathy with subcortical cysts: Leukodystrophies arising from astrocyte dysfunction. ACTA ACUST UNITED AC 2006; 12:113-22. [PMID: 16807904 DOI: 10.1002/mrdd.20101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J Rafael Gorospe
- Center for Genetic Medicine, Children's National Medical Center, Washington, District of Columbia 20010, USA.
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