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Yoneno S, Yamamoto K, Tabata K, Shimizu-Motohashi Y, Tomita A, Hayashi T, Maki H, Sato N, Inoue K, Saitsu H, Komaki H. A novel heterozygous TMEM63A variant in a familial case with early onset nystagmus, severe hypomyelination, and a favorable adult prognosis. J Hum Genet 2024:10.1038/s10038-024-01268-z. [PMID: 38951194 DOI: 10.1038/s10038-024-01268-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/03/2024]
Abstract
Heterozygous transmembrane protein 63A (TMEM63A) variants cause transient infantile hypomyelinating leukodystrophy-19, which features remarkable natural resolution of clinical and imaging findings during childhood. Previous reports have mainly described de novo variants lacking detailed familial cases. Herein, we describe the clinical course of familial cases with a TMEM63A variant. A 5-month-old girl presented with nystagmus, global hypotonia, and difficulty swallowing since birth. Brain magnetic resonance imaging at 1.5 and 5 months revealed diffuse hypomyelination. Her mother, maternal aunt, and grandfather had nystagmus and motor developmental delays in infancy, which resolved spontaneously during childhood. Compared with these cases, the proband's motor developmental delay was profound, and she was the only one with feeding difficulties, necessitating nasogastric tube feeding. Genetic testing revealed a heterozygous TMEM63A variant (NM_014698.3:c.1658G>A, p.(Gly553Asp)) in the proband and her family. This is the first three-generation familial report of a TMEM63A variant that provides insight into its history and heterogeneity.
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Affiliation(s)
- Shota Yoneno
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Kaoru Yamamoto
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan.
| | - Kenshiro Tabata
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuko Shimizu-Motohashi
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ayaka Tomita
- Department of Neonatology, Toho University Omori Medical Center, Tokyo, Japan
| | - Taiju Hayashi
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hiroyuki Maki
- Department of Radiology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Noriko Sato
- Department of Radiology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hirofumi Komaki
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
- Translational Medical Center, National Center of Neurology and Psychiatry, Tokyo, Japan
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2
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Wu X, Shang T, Lü X, Luo D, Yang D. A monomeric structure of human TMEM63A protein. Proteins 2024; 92:750-756. [PMID: 38217391 DOI: 10.1002/prot.26660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/10/2023] [Accepted: 12/19/2023] [Indexed: 01/15/2024]
Abstract
OSCA/TMEM63 is a newly identified family of mechanically activated (MA) ion channels in plants and animals, respectively, which convert physical forces into electrical signals or trigger intracellular cascades and are essential for eukaryotic physiology. OSCAs and related TMEM16s and transmembrane channel-like (TMC) proteins form homodimers with two pores. However, the molecular architecture of the mammalian TMEM63 proteins remains unclear. Here we elucidate the structure of human TMEM63A in the presence of calcium by single particle cryo-EM, revealing a distinct monomeric architecture containing eleven transmembrane helices. It has structural similarity to the single subunit of the Arabidopsis thaliana OSCA proteins. We locate the ion permeation pathway within the monomeric configuration and observe a nonprotein density resembling lipid. These results lay a foundation for understanding the structural organization of OSCA/TMEM63A family proteins.
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Affiliation(s)
- Xuening Wu
- Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, China
| | - Tiantian Shang
- Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, China
| | - Xinyi Lü
- Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, China
| | - Deyi Luo
- Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, China
| | - Dongxue Yang
- Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, China
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Dalghi MG, DuRie E, Ruiz WG, Clayton DR, Montalbetti N, Mutchler SB, Satlin LM, Kleyman TR, Carattino MD, Shi YS, Apodaca G. Expression and localization of the mechanosensitive/osmosensitive ion channel TMEM63B in the mouse urinary tract. Physiol Rep 2024; 12:e16043. [PMID: 38724885 PMCID: PMC11082094 DOI: 10.14814/phy2.16043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/23/2024] [Accepted: 04/23/2024] [Indexed: 05/12/2024] Open
Abstract
The epithelial cells that line the kidneys and lower urinary tract are exposed to mechanical forces including shear stress and wall tension; however, the mechanosensors that detect and respond to these stimuli remain obscure. Candidates include the OSCA/TMEM63 family of ion channels, which can function as mechanosensors and osmosensors. Using Tmem63bHA-fl/HA-fl reporter mice, we assessed the localization of HA-tagged-TMEM63B within the urinary tract by immunofluorescence coupled with confocal microscopy. In the kidneys, HA-TMEM63B was expressed by proximal tubule epithelial cells, by the intercalated cells of the collecting duct, and by the epithelial cells lining the thick ascending limb of the medulla. In the urinary tract, HA-TMEM63B was expressed by the urothelium lining the renal pelvis, ureters, bladder, and urethra. HA-TMEM63B was also expressed in closely allied organs including the epithelial cells lining the seminal vesicles, vas deferens, and lateral prostate glands of male mice and the vaginal epithelium of female mice. Our studies reveal that TMEM63B is expressed by subsets of kidney and lower urinary tract epithelial cells, which we hypothesize are sites of TMEM63B mechanosensation or osmosensation, or both.
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Affiliation(s)
- Marianela G. Dalghi
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Ella DuRie
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Wily G. Ruiz
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Dennis R. Clayton
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Nicolas Montalbetti
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Stephanie B. Mutchler
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Lisa M. Satlin
- Department of PediatricsIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
| | - Thomas R. Kleyman
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Chemical Biology & PharmacologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Marcelo D. Carattino
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Yun Stone Shi
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical SchoolNanjing UniversityNanjingChina
| | - Gerard Apodaca
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
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4
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Siori D, Vlachakis D, Makrythanasis P, Traeger-Synodinos J, Veltra D, Kampouraki A, Chrousos GP. A TMEM63A Nonsense Heterozygous Variant Linked to Infantile Transient Hypomyelinating Leukodystrophy Type 19? Genes (Basel) 2024; 15:525. [PMID: 38790154 PMCID: PMC11120763 DOI: 10.3390/genes15050525] [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: 03/08/2024] [Revised: 04/07/2024] [Accepted: 04/17/2024] [Indexed: 05/26/2024] Open
Abstract
Infantile onset transient hypomyelination (IOTH) is a rare form of leukodystrophy that is associated with transient motor impairment and delayed central nervous system myelination. Here, we report a case of a new mutation in the transmembrane protein 63A (TMEM63A) gene identified using Whole-Exome Sequencing (WES) in an 8.5-year-old boy with clinical symptoms similar to IOTH. The patient exhibited a mild developmental delay, including hypotonia and delayed motor milestones, as well as some notable phenotypic characteristics, such as macrocephaly and macrosomia. Despite the absence of early neuroimaging, genetic testing revealed a paternally inherited variant in TMEM63A (NM_14698.3:c.220A>T;p:(Arg74*)), potentially linked to infantile transient hypomyelinating leukodystrophy type 19. Our findings in this study and the patient's favorable clinical course underscore the potential for successful myelination even with delayed initiation and may contribute to a better understanding of the genotype-phenotype correlation in IOTH, emphasizing the importance of genetic analysis in unresolved developmental delay cases and providing critical insights for accurate diagnosis, prognosis and potential therapeutic strategies in rare leukodystrophies.
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Affiliation(s)
- Dimitra Siori
- University Research Institute of Maternal and Child Health and Precision Medicine, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece; (D.S.); (D.V.)
- Clinical and Translational Research Endocrine Unit, School of Medicine, National Kapodistrian University of Athens, 115 28 Athens, Greece
| | - Dimitrios Vlachakis
- University Research Institute of Maternal and Child Health and Precision Medicine, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece; (D.S.); (D.V.)
- Laboratory of Genetics, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece
- School of Informatics, Faculty of Natural & Mathematical Sciences, King’s College London, Bush House, Strand, London WC2R 2LS, UK
| | - Periklis Makrythanasis
- Laboratory of Medical Genetics, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece
- Department of Genetic Medicine and Development, Medical School, University of Geneva, 1211 Geneva, Switzerland
- Biomedical Research Foundation of the Academy of Athens, 115 27 Athens, Greece
| | - Joanne Traeger-Synodinos
- Laboratory of Medical Genetics, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece
| | - Danai Veltra
- Laboratory of Medical Genetics, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece
| | - Afrodite Kampouraki
- Laboratory of Medical Genetics, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece
| | - George P. Chrousos
- University Research Institute of Maternal and Child Health and Precision Medicine, School of Medicine, National Kapodistrian University of Athens, 115 27 Athens, Greece; (D.S.); (D.V.)
- Clinical and Translational Research Endocrine Unit, School of Medicine, National Kapodistrian University of Athens, 115 28 Athens, Greece
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Dei Cas M, Montavoci L, Pasini C, Caretti A, Penati S, Martinelli C, Gianelli U, Casati S, Nardecchia F, Torella A, Brunetti-Pierri N, Trinchera M. Loss of function and reduced levels of sphingolipid desaturase DEGS1 variants are both relevant in disease mechanism. J Lipid Res 2024; 65:100517. [PMID: 38342436 PMCID: PMC10940770 DOI: 10.1016/j.jlr.2024.100517] [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: 08/02/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/13/2024] Open
Abstract
The last step of ex novo ceramide biosynthesis consists of the conversion of dihydroceramide into ceramide catalyzed by sphingolipid Δ4-desaturase DEGS1. DEGS1 variants were found to be responsible for heterogeneous clinical pictures belonging to the family of hypomyelinating leukodystrophies. To investigate the mechanisms making such variants pathogenic, we designed a procedure for the efficient detection of desaturase activity in vitro using LC-MS/MS and prepared a suitable cell model knocking out DEGS1 in HEK-293T cells through CRISPR-Cas9 genome editing (KO-DES-HEK). Transfecting KO-DES-HEK cells with DEGS1 variants, we found that their transcripts were all overexpressed as much as the WT transcripts, while the levels of cognate protein were 40%-80% lower. In vitro desaturase activity was lost by many variants except L175Q and N255S, which maintain a catalytic efficiency close to 12% of the WT enzyme. Metabolic labeling of KO-DES-HEK with deuterated palmitate followed by LC-MS/MS analysis of the formed sphingolipids revealed that the ceramide/dihydroceramide and sphingomyelin/dihydrosphingomyelin ratios were low and could be reverted by the overexpression of WT DEGS1 as well as of L175Q and N255S variants, but not by the overexpression of all other variants. Similar analyses performed on fibroblasts from a patient heterozygous for the N255S variant showed very low variant DEGS1 levels and a low ratio between the same unsaturated and saturated sphingolipids formed upon metabolic labeling, notwithstanding the residual activity measured at high substrate and homogenate protein concentrations. We conclude that loss of function and reduced protein levels are both relevant in disease pathogenesis.
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Affiliation(s)
- Michele Dei Cas
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Linda Montavoci
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Claudia Pasini
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Anna Caretti
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Sara Penati
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Carla Martinelli
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Umberto Gianelli
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy; S.C. di Anatomia Patologica, ASST- Santi Paolo e Carlo, Milan, Italy
| | - Sara Casati
- Department of Biomedical, Surgical and Dental Sciences, Università degli Studi di Milano, Milan, Italy
| | - Francesca Nardecchia
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University of Rome, Italy
| | - Annalaura Torella
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Nicola Brunetti-Pierri
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy; Department of Translational Medicine, Medical Genetics, University of Naples Federico II, Naples, Italy; Scuola Superiore Meridionale (SSM, School of Advanced Studies), Genomics and Experimental Medicine Program, University of Naples Federico II, Naples, Italy
| | - Marco Trinchera
- Department of Medicine and Surgery (DMC), University of Insubria, Varese, Italy.
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6
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Garg D, Agarwal A, Garg A, Srivastava AK. Adult-onset Leukodystrophy due to TMEM63A Variant Presenting with Rapidly Progressive Dementia with Parkinsonism. Ann Indian Acad Neurol 2024; 27:105-107. [PMID: 38495226 PMCID: PMC10941901 DOI: 10.4103/aian.aian_694_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 03/19/2024] Open
Affiliation(s)
- Divyani Garg
- Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
| | - Ayush Agarwal
- Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
| | - Ajay Garg
- Department of Neuroimaging and Interventional Neuroradiology, All India Institute of Medical Sciences, New Delhi, India
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7
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Hülsmeier AJ, Toelle SP, Bellstedt P, Wentzel C, Bahr A, Kolokotronis K, Hornemann T. The atypical sphingolipid SPB 18:1(14Z);O2 is a biomarker for DEGS1 related hypomyelinating leukodystrophy. J Lipid Res 2023; 64:100464. [PMID: 37890668 PMCID: PMC10696257 DOI: 10.1016/j.jlr.2023.100464] [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: 05/11/2023] [Revised: 10/20/2023] [Accepted: 10/21/2023] [Indexed: 10/29/2023] Open
Abstract
Sphingolipids (SL) represent a structurally diverse class of lipids that are central to cellular physiology and neuronal development and function. Defects in the sphingolipid metabolism are typically associated with nervous system disorders. The C4-dihydroceramide desaturase (DEGS1) catalyzes the conversion of dihydroceramide to ceramide, the final step in the SL de-novo synthesis. Loss of function mutations in DEGS1 cause a hypomyelinating leukodystrophy, which is associated with increased plasma dihydrosphingolipids (dhSL) and with the formation of an atypical SPB 18:1(14Z);O2 metabolite. Here, we characterize two novel DEGS1 variants of unknown significance (VUS), provide a structural model with a predicted substrate binding site, and propose a regulatory link between DEGS1 and fatty acid desaturase 3 (FADS3). Both VUS involve single amino acid substitutions near the C-terminus within conserved regions of the enzyme. Patient 1 (p.R311K variant) shows severe progressive tetraspasticity, intellectual disability, and epilepsy in combination with brain magnetic resonance imaging (MRI) findings, typical for DEGS1-related leukodystrophy. Patient 2 (p.G270E variant) presents with delayed psychomotor development, oculomotor apraxia, and a normal brain MRI. Plasma from the p.R311K carrier showed a significantly elevated dhSL species and the presence of SPB 18:1(14Z);O2, while the plasma SL profile for the p.G270E variant was not altered. This suggests the p.R331K variant is pathogenic, while the p.G270E appears benign. As an increase in dihydroSL species is also seen in other pathological disorders of the SL metabolism, the SPB 18:1(14Z);O2 seems to be a more specific biomarker to discriminate between pathogenic and benign DEGS1 variants.
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Affiliation(s)
- Andreas J Hülsmeier
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Sandra P Toelle
- Department of Pediatric Neurology, University Children's Hospital, Zurich, University of Zurich, Zurich, Switzerland
| | - Peter Bellstedt
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Christian Wentzel
- Department of Women's and Children's Health, Pediatric Oncological and Neurological Research, Uppsala University, Uppsala, Sweden
| | - Angela Bahr
- Institute of Medical Genetics, University of Zurich, Schlieren, Zurich, Switzerland
| | | | - Thorsten Hornemann
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
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Chen X, Wang N, Liu JW, Zeng B, Chen GL. TMEM63 mechanosensitive ion channels: Activation mechanisms, biological functions and human genetic disorders. Biochem Biophys Res Commun 2023; 683:149111. [PMID: 37857161 DOI: 10.1016/j.bbrc.2023.10.043] [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: 07/24/2023] [Revised: 09/27/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023]
Abstract
The transmembrane 63 (TMEM63) family of proteins are originally identified as homologs of the osmosensitive calcium-permeable (OSCA) channels in plants. Mechanosensitivity of OSCA and TMEM63 proteins are recently demonstrated in addition to their proposed activation mechanism by hyper/hypo-osmolarity. TMEM63 proteins exist in all animals, with a single member in Drosophila (TMEM63) and three members in mammals (TMEM63 A/B/C). In humans, monoallelic variants of TMEM63A have been reported to cause transient hypomyelination during infancy, or severe hypomyelination and global developmental delay. Heterozygous variants of TMEM63B are found in patients with intellectual disability and abnormal motor function and brain morphology. Biallelic variants of TMEM63C are associated with hereditary spastic paraplegias accompanied by mild or no intellectual disability. Physiological functions of TMEM63 proteins clearly recognized so far include detecting food grittiness and environmental humidity in Drosophila, and supporting hearing in mice by regulating survival of cochlear hair cells. In this review, we summarize current knowledge about the activation mechanisms and biological functions of TMEM63 channels, and provide a concise reference for researchers interested in investigating more physiological and pathogenic roles of this family of proteins with ubiquitous expression in the body.
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Affiliation(s)
- Xin Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Na Wang
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Jia-Wei Liu
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.
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9
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Sun L, Lin W, Meng H, Zhang W, Hou S. A Chinese patient with POLR3A-related leukodystrophy: a case report and literature review. Front Neurol 2023; 14:1269237. [PMID: 37965164 PMCID: PMC10641775 DOI: 10.3389/fneur.2023.1269237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 10/10/2023] [Indexed: 11/16/2023] Open
Abstract
Background Leukodystrophies are hereditary white matter diseases characterized by genetic polymorphisms and considerable phenotypic variability. They can be classified into myelin and non-myelin malformations. These diseases are rare, affecting 1 out of 250,000-500,000 individuals and can manifest at any age. A subtype of leukodystrophy, associated with missense mutations in the RNA polymerase subunit III (POLR3A) gene, is inherited in an autosomal recessive manner. Case report We report and analyse a case of a 34-year-old female who presented with ataxia. Magnetic Resonance Imaging (MRI) of the brain revealed demyelinating lesions in the white matter. Genetic testing identified the c.4044C > G and c.1186-2A > G variants in the POLR3A gene. The patient was diagnosed with hypomyelinating leukodystrophy type 7 and received neurotrophic and symptomatic supportive therapy. However, after 1 month of follow-up, there was no improvement in her symptoms. Conclusion POLR3A-induced leukodystrophy is relatively rare and not well understood, making it challenging to diagnose and easy to overlook. The prognosis for this disease is generally poor, significantly impacting the quality of life of affected individuals. Currently, no cure is available for this condition, and treatment is limited to managing symptoms. Further research into new treatment methods for POLR3A-induced leukodystrophy is imperative to improve the quality of life and potentially extend the life expectancy of patients.
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Affiliation(s)
| | | | | | | | - Shuai Hou
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
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10
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Zheng W, Rawson S, Shen Z, Tamilselvan E, Smith HE, Halford J, Shen C, Murthy SE, Ulbrich MH, Sotomayor M, Fu TM, Holt JR. TMEM63 proteins function as monomeric high-threshold mechanosensitive ion channels. Neuron 2023; 111:3195-3210.e7. [PMID: 37543036 PMCID: PMC10592209 DOI: 10.1016/j.neuron.2023.07.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 05/12/2023] [Accepted: 07/08/2023] [Indexed: 08/07/2023]
Abstract
OSCA/TMEM63s form mechanically activated (MA) ion channels in plants and animals, respectively. OSCAs and related TMEM16s and transmembrane channel-like (TMC) proteins form homodimers with two pores. Here, we uncover an unanticipated monomeric configuration of TMEM63 proteins. Structures of TMEM63A and TMEM63B (referred to as TMEM63s) revealed a single highly restricted pore. Functional analyses demonstrated that TMEM63s are bona fide mechanosensitive ion channels, characterized by small conductance and high thresholds. TMEM63s possess evolutionary variations in the intracellular linker IL2, which mediates dimerization in OSCAs. Replacement of OSCA1.2 IL2 with TMEM63A IL2 or mutations to key variable residues resulted in monomeric OSCA1.2 and MA currents with significantly higher thresholds. Structural analyses revealed substantial conformational differences in the mechano-sensing domain IL2 and gating helix TM6 between TMEM63s and OSCA1.2. Our studies reveal that mechanosensitivity in OSCA/TMEM63 channels is affected by oligomerization and suggest gating mechanisms that may be shared by OSCA/TMEM63, TMEM16, and TMC channels.
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Affiliation(s)
- Wang Zheng
- Departments of Otolaryngology & Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| | - Shaun Rawson
- Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Zhangfei Shen
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Elakkiya Tamilselvan
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Harper E Smith
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Julia Halford
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Chen Shen
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Swetha E Murthy
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Maximilian H Ulbrich
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany; Internal Medicine IV, University of Freiburg Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Tian-Min Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA.
| | - Jeffrey R Holt
- Departments of Otolaryngology & Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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Wong MST, Thomas T, Lim JY, Kam S, Teo JX, Ching J, Goh CYJ, Jamuar SS, Lim WK, Koh AL. DEGS1 -related leukodystrophy: a clinical report and review of literature. Clin Dysmorphol 2023; 32:106-111. [PMID: 37195341 DOI: 10.1097/mcd.0000000000000457] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
BACKGROUND Leukodystrophies are a heterogeneous group of disorders affecting the white matter of the central nervous system, with or without affecting the peripheral nervous system. Biallelic variants in DEGS1 , coding for desaturase 1 (Des1) protein, were recently reported to be associated with hypomyelinating leukodystrophy (HLD), a subclass of leukodystrophies where the formation of the myelin sheath is affected. METHODS Genomic sequencing was performed on our index patient with severe developmental delay, severe failure to thrive, dystonia, seizures, and hypomyelination on brain imaging. Sphingolipid analysis was performed and dihydroceramide/ceramide (dhCer/Cer) ratios were obtained by the measurement of ceramide and dihydroceramide species. RESULTS A homozygous missense variant was identified in DEGS1 (c.565A > G:p Asn189Asp). The identified DEGS1 variant has been annotated as "conflicting reports of pathogenicity" on ClinVar. Follow-up sphingolipid analysis on our patient showed significantly raised dhCer/Cer and this was consistent with dysfunction of the Des1 protein, providing additional evidence to support the pathogenicity of this variant. CONCLUSION While rare, pathogenic variants in DEGS1 should be considered in patients with HLD phenotype. To date, 25 patients have been reported across four studies on DEGS1 -related HLD, and, in this report, we summarize the literature. More such reports will enable deeper phenotypic characterization of this disorder.
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Affiliation(s)
| | - Terrence Thomas
- Neurology Service, Department of Paediatrics, KK Women's and Children's Hospital
- SingHealth Duke-NUS Paediatric Academic Clinical Programme
| | - Jiin Ying Lim
- SingHealth Duke-NUS Paediatric Academic Clinical Programme
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- SingHealth Duke-NUS Genomic Medicine Centre
| | - Sylvia Kam
- SingHealth Duke-NUS Paediatric Academic Clinical Programme
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- SingHealth Duke-NUS Genomic Medicine Centre
| | | | - Jianhong Ching
- Cardiovascular and Metabolic Disorders Programme, Duke-NUS Medical School
- KK Research Centre, KK Women's and Children's Hospital
| | - Chew Yin Jasmine Goh
- Division of Nursing - Nursing Clinical Services, Genetics Specialty Nurse, KK Women's and Children's Hospital, Singapore, Singapore
| | - Saumya Shekhar Jamuar
- Lee Kong Chian School of Medicine, Nanyang Technological University
- SingHealth Duke-NUS Paediatric Academic Clinical Programme
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- SingHealth Duke-NUS Genomic Medicine Centre
- SingHealth Duke-NUS Institute of Precision Medicine
| | - Weng Khong Lim
- SingHealth Duke-NUS Genomic Medicine Centre
- SingHealth Duke-NUS Institute of Precision Medicine
| | - Ai Ling Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University
- SingHealth Duke-NUS Paediatric Academic Clinical Programme
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- SingHealth Duke-NUS Genomic Medicine Centre
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12
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Gerik-Celebi HB, Aydin H, Bolat H, Unsel-Bolat G. Clinical and Genetic Characteristics of Patients with Unexplained Intellectual Disability/Developmental Delay without Epilepsy. Mol Syndromol 2023; 14:208-218. [PMID: 37323201 PMCID: PMC10267527 DOI: 10.1159/000529018] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/05/2023] [Indexed: 10/21/2023] Open
Abstract
Introduction Global developmental delay (DD), intellectual disability (ID), and autism spectrum disorder (ASD) are mainly evaluated under the neurodevelopmental disorder framework. In this study, we aimed to determine the genetic diagnosis yield using step-by-step genetic analysis in 38 patients with unexplained ID/DD and/or ASD. Methods In 38 cases (27 male, 11 female) with unexplained ID/DD and/or ASD, chromosomal microarray (CMA) analysis, clinical exome sequencing (CES), and whole-exome sequencing (WES) analysis were applied, respectively. Results We found a diagnostic rate of only CMA analysis as 21% (8/38) presenting 8 pathogenic and likely pathogenic CNVs. The rate of patients diagnosed with CES/WES methods was 32.2% (10/31). When all pathogenic and likely pathogenic variants were evaluated, the diagnosis rate was 44.7% (17/38). A dual diagnosis was obtained in a case with 16p11.2 microduplication and de novo SNV. We identified eight novel variants: TUBA1A (c.787C>G), TMEM63A (c.334-2A>G), YY1AP1 (c.2051_2052del), ABCA13 (c.12064C>T), ABCA13 (c.13187G>A), USP9X (c.1189T>C), ANKRD17 (c.328_330dup), and GRIA4 (c.17G>A). Conclusion We present diagnostic rates of a complementary approach to genetic analysis (CMA, CES, and WES). The combined use of genetic analysis methods in unexplained ID/DD and/or ASD cases has contributed significantly to diagnosis rates. Also, we present detailed clinical characteristics to improve genotype-phenotype correlation in the literature for rare and novel variants.
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Affiliation(s)
| | - Hilal Aydin
- Department of Pediatrics, Division of Child Neurology, Balıkesir University Faculty of Medicine, Balıkesir, Turkey
| | - Hilmi Bolat
- Department of Medical Genetics, Balıkesir University Faculty of Medicine, Balıkesir, Turkey
| | - Gul Unsel-Bolat
- Department of Child and Adolescent Psychiatry, Balıkesir University Faculty of Medicine, Balıkesir, Turkey
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13
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Perrier S, Guerrero K, Tran LT, Michell-Robinson MA, Legault G, Brais B, Sylvain M, Dorman J, Demos M, Köhler W, Pastinen T, Thiffault I, Bernard G. Solving inherited white matter disorder etiologies in the neurology clinic: Challenges and lessons learned using next-generation sequencing. Front Neurol 2023; 14:1148377. [PMID: 37077564 PMCID: PMC10108901 DOI: 10.3389/fneur.2023.1148377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 02/23/2023] [Indexed: 04/05/2023] Open
Abstract
IntroductionRare neurodevelopmental disorders, including inherited white matter disorders or leukodystrophies, often present a diagnostic challenge on a genetic level given the large number of causal genes associated with a range of disease subtypes. This study aims to demonstrate the challenges and lessons learned in the genetic investigations of leukodystrophies through presentation of a series of cases solved using exome or genome sequencing.MethodsEach of the six patients had a leukodystrophy associated with hypomyelination or delayed myelination on MRI, and inconclusive clinical diagnostic genetic testing results. We performed next generation sequencing (case-based exome or genome sequencing) to further investigate the genetic cause of disease.ResultsFollowing different lines of investigation, molecular diagnoses were obtained for each case, with patients harboring pathogenic variants in a range of genes including TMEM106B, GJA1, AGA, POLR3A, and TUBB4A. We describe the lessons learned in reaching the genetic diagnosis, including the importance of (a) utilizing proper multi-gene panels in clinical testing, (b) assessing the reliability of biochemical assays in supporting diagnoses, and (c) understanding the limitations of exome sequencing methods in regard to CNV detection and region coverage in GC-rich areas.DiscussionThis study illustrates the importance of applying a collaborative diagnostic approach by combining detailed phenotyping data and metabolic results from the clinical environment with advanced next generation sequencing analysis techniques from the research environment to increase the diagnostic yield in patients with genetically unresolved leukodystrophies.
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Affiliation(s)
- Stefanie Perrier
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Kether Guerrero
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Luan T. Tran
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Mackenzie A. Michell-Robinson
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Geneviève Legault
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
| | - Bernard Brais
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Michel Sylvain
- Division of Pediatric Neurology, Centre Mère-Enfant Soleil du CHU de Québec - Université Laval, Québec City, QC, Canada
| | - James Dorman
- John H. Stroger Jr. Hospital of Cook County, Chicago, IL, United States
- Department of Neurological Sciences, Rush Medical College, Chicago, IL, United States
| | - Michelle Demos
- Division of Neurology, Department of Pediatrics, University of British Columbia, BC Children's Hospital, Vancouver, BC, Canada
| | - Wolfgang Köhler
- Leukodystrophy Center, University of Leipzig Medical Center, Leipzig, Germany
| | - Tomi Pastinen
- Genomic Medicine Center, Children's Mercy Hospital, Kansas City, MO, United States
- University of Missouri Kansas City School of Medicine, Kansas City, MO, United States
| | - Isabelle Thiffault
- Genomic Medicine Center, Children's Mercy Hospital, Kansas City, MO, United States
- University of Missouri Kansas City School of Medicine, Kansas City, MO, United States
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO, United States
- Isabelle Thiffault
| | - Geneviève Bernard
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Center, Montreal, QC, Canada
- *Correspondence: Geneviève Bernard
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14
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Singh S, Mishra A, Murthy C, Inban P, Abdefatah Ali M, Yadav AS, Intsiful TA, O Omar ZT, Lakhra S, Khan DA. A Rare Case of Hypomyelinating Leukodystrophy and Its Management: A Case Report and Literature Review. Cureus 2023; 15:e36471. [PMID: 37090362 PMCID: PMC10117409 DOI: 10.7759/cureus.36471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2023] [Indexed: 04/25/2023] Open
Abstract
A subset of hereditary white matter disorders called hypomyelinating leukodystrophies (HLD) is characterized primarily by the absence of myelin deposition. Although the clinical presentation can be mild and the development of symptoms can occur in adolescence or adulthood, the majority of severe cases present during infancy and early childhood with significant neurological impairments. The clinical features vary from muscle stiffness to seizures and developmental delay. The detailed myelination process can be seen with magnetic resonance imaging (MRI), and many patients are diagnosed using MRI pattern recognition and next-generation sequencing (NGS) in most cases. Here, we report a case of an infant suffering from the hypomyelinating leukodystrophy-13 (HLD-13) variant, whose next-generation sequencing revealed a pathogenic homozygous variant.
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Affiliation(s)
- Sonali Singh
- Pediatrics, King George's Medical University, Lucknow, IND
| | - Anshika Mishra
- Pediatrics, King George's Medical University, Lucknow, IND
| | - Chinmayee Murthy
- Internal Medicine, California Institute of Behavioral Neurosciences and Psychology, Fairfield, USA
| | - Pugazhendi Inban
- Department of General Medicine, Government Medical College, Omandurar, Chennai, IND
| | | | - Anupam S Yadav
- Psychiatry and Behavioral Sciences, Ganesh Shankar Vidyarthi Memorial (GSVM) Medical College, Kanpur, IND
| | | | | | - Sakshi Lakhra
- Internal Medicine, All Saints School of Medicine, St. Roseau, DMA
| | - Dr Aadil Khan
- Department of Internal Medicine, Lala Lajpat Rai (LLR) Hospital, Kanpur, IND
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15
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Zhang TM, Liao L, Yang SY, Huang MY, Zhang YL, Deng L, Hu SY, Yang F, Zhang FL, Shao ZM, Li DQ. TOLLIP-mediated autophagic degradation pathway links the VCP-TMEM63A-DERL1 signaling axis to triple-negative breast cancer progression. Autophagy 2023; 19:805-821. [PMID: 35920704 PMCID: PMC9980475 DOI: 10.1080/15548627.2022.2103992] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Triple-negative breast cancer (TNBC) is the most challenging breast cancer subtype to treat due to the lack of effective targeted therapies. Transmembrane (TMEM) proteins represent attractive drug targets for cancer therapy, but biological functions of most members of the TMEM family remain unknown. Here, we report for the first time that TMEM63A (transmembrane protein 63A), a poorly characterized TMEM protein with unknown functions in human cancer, functions as a novel oncogene to promote TNBC cell proliferation, migration, and invasion in vitro and xenograft tumor growth and lung metastasis in vivo. Mechanistic investigations revealed that TMEM63A localizes in endoplasmic reticulum (ER) and lysosome membranes, and interacts with VCP (valosin-containing protein) and its cofactor DERL1 (derlin 1). Furthermore, TMEM63A undergoes autophagy receptor TOLLIP-mediated autophagic degradation and is stabilized by VCP through blocking its lysosomal degradation. Strikingly, TMEM63A in turn stabilizes oncoprotein DERL1 through preventing TOLLIP-mediated autophagic degradation. Notably, pharmacological inhibition of VCP by CB-5083 or knockdown of DERL1 partially abolishes the oncogenic effects of TMEM63A on TNBC progression both in vitro and in vivo. Collectively, these findings uncover a previously unknown functional and mechanistic role for TMEM63A in TNBC progression and provide a new clue for targeting TMEM63A-driven TNBC tumors by using a VCP inhibitor.Abbreviations: ATG16L1, autophagy related 16 like 1; ATG5, autophagy related 5; ATP5F1B/ATP5B, ATP synthase F1 subunit beta; Baf-A1, bafilomycin A1; CALCOCO2/NDP52, calcium binding and coiled-coil domain 2; CANX, calnexin; DERL1, derlin 1; EGFR, epidermal growth factor receptor; ER, endoplasmic reticulum; ERAD, endoplasmic reticulum-associated degradation; HSPA8, heat shock protein family A (Hsp70) member 8; IP, immunoprecipitation; LAMP2A, lysosomal associated membrane protein 2; NBR1, NBR1 autophagy cargo receptor; OPTN, optineurin; RT-qPCR, reverse transcription-quantitative PCR; SQSTM1/p62, sequestosome 1; TAX1BP1, Tax1 binding protein 1; TMEM63A, transmembrane protein 63A; TNBC, triple-negative breast cancer; TOLLIP, toll interacting protein; VCP, valosin containing protein.
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Affiliation(s)
- Tai-Mei Zhang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China
| | - Li Liao
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China.,Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China
| | - Shao-Ying Yang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China
| | - Min-Ying Huang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China
| | - Yin-Ling Zhang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China.,Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China
| | - Ling Deng
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China
| | - Shu-Yuan Hu
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China
| | - Fan Yang
- Department of Breast Surgery, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China
| | - Fang-Lin Zhang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China.,Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China
| | - Zhi-Min Shao
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China.,Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Breast Surgery, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Shanghai Key Laboratory of Breast Cancer, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Shanghai Key Laboratory of Radiation Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China
| | - Da-Qiang Li
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai Yangpu, China.,Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Department of Breast Surgery, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Shanghai Key Laboratory of Breast Cancer, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China.,Shanghai Key Laboratory of Radiation Oncology, Shanghai Medical College, Fudan University, Shanghai, Yangpu, China
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16
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Akbari M, Ebrahimi Tapeh Z, Zaersabet M, Rahimi H, Ganji M. Novel pyrroline-5-carboxylate reductase 2 (PYCR2) mutation in an Iranian patient with hypomyelinating leukodystrophy: findings of molecular and in silico investigations. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2023. [DOI: 10.1186/s43042-023-00393-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Abstract
Background
Hypomyelinating leukodystrophy (HLD) is a specific group of leukodystrophies and is characterized by progressive postnatal growth delay that represents a type of clinically overlapping but genetically heterogeneous diseases with autosomal recessive inheritance. Loss-of-function mutations in PYCR2 are one of the main causes of HLD type 10 (HLD10), which is identified by cerebral hypomyelination, inadequate growth, brain atrophy, and movement abnormality. This study aimed to investigate the molecular etiology of HLD10 disorder in an Iranian patient from a consanguineous marriage family.
Results
The DNA samples were extracted from the patient, a 9-year-old girl, and her parents. Whole-exome sequencing was conducted for these samples and the results were eventually confirmed and segregated via Sanger sequencing. Our findings demonstrated a novel homozygous frameshift mutation in PYCR2 gene, c.135dup (NM_013328.4). The heterozygous state of this variant was confirmed in parents. Additionally, this mutation was predicted to exhibit damaging effects through protein sequence alteration.
Conclusions
Such findings are of importance for understanding the underlying pathogenicity mechanisms and for improving genetic counseling knowledge of HLD patients for families.
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17
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Peng Q, Zhang Y, Xian B, Wu L, Ding J, Ding W, Zhang X, Ding B, Li D, Wu J, Hu X, Lu G. A synonymous variant contributes to a rare Wiedemann-Rautenstrauch syndrome complicated with mild anemia via affecting pre-mRNA splicing. Front Mol Neurosci 2022; 15:1026530. [DOI: 10.3389/fnmol.2022.1026530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/11/2022] [Indexed: 11/13/2022] Open
Abstract
Wiedemann-Rautenstrauch syndrome (WDRTS) is an extremely rare autosomal recessive neonatal disorder. Currently, over 50 cases with variable phenotypes of WDRTS have been reported. In our cohort of prenatal and postnatal growth retardation, a female proband was found to have general growth retardation, neurocutaneous syndrome, and anemia. Karyotype test and array-CGH detected no obvious chromosomal aberrations. Trio-based whole-exome sequencing (Trio-WES) identified bi-allelic compound mutations in the coding sequence (CDS) of POLR3A gene (c.3342C > T, p.Ser1114 = and c.3718G > A, p.Gly1240Ser). For the mild anemia phenotype, the underlying causal genetic factors could be attributed to the compound heterozygous mutations in FANCA gene (c.2832dup, p.Ala945CysfsTer6 and c.1902 T > G, p.Asp634Glu). Mini-gene reporter assays revealed that the synonymous variant of POLR3A and the missense variant of FANCA could affect pre-mRNA splicing of each gene. For POLR3A, the synonymous mutation (c.3342C > T, p.Ser1114=) generated three types of aberrant isoforms. Therefore, the female patient was finally diagnosed as WDRTS caused by POLR3A. For FANCA, the missense variant (c.1902 T > G, p.Asp634Glu) disrupted the normal splicing between exon 21 and 22, and produced two types of abnormal isoforms, one carrying the 1902G and the other spliced between exon 21 and 23 to exclude exon 22. Network analysis showed that POLR3A and FANCA could be STRINGed, indicating both proteins might collaborate for some unknown functions. Current investigation would broaden the knowledge for clinicians and genetic counselors and remind them to interpret those synonymous or predicted “benign” variants more carefully.
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18
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Solazzi R, Moscatelli M, Sebastiano DR, Canafoglia L, Pezzoli L, Iascone M, Granata T. Severe Epilepsy and Movement Disorder May Be Early Symptoms of TMEM106B-Related Hypomyelinating Leukodystrophy. Neurol Genet 2022; 8:e200022. [PMID: 36046422 PMCID: PMC9425219 DOI: 10.1212/nxg.0000000000200022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/07/2022] [Indexed: 11/15/2022]
Abstract
ObjectiveTo report the clinical presentation of the first Italian child affected by hypomyelinating leukodystrophy (HLD) associated with the recurrent variant p.Asp252Asn in the TMEM106B gene.MethodsThe methods included clinical case description, neurophysiologic assessment, brain MRI, and whole-exome sequencing (WES).ResultsThe child presented soon after birth with nystagmus and hyperkinetic movement disorder. Focal seizures appeared from 2 months of age and recurred at high frequency, despite several antiseizure medications, and focal epileptic status frequently required IV phenytoin. Control of seizures was achieved at the age of 8 months by the association of high doses of sodium blockers. Clinical picture worsened over time and was characterized by axial hypotonia, failure to thrive requiring gastrostomy, pyramidal sings, and severe secondary microcephaly. MRI performed at ages 2, 6, and 20 months showed diffuse supratentorial and subtentorial hypomyelination; multimodal evoked potentials showed increased latency. WES performed at 6 months of age identified the p.Asp252Asn de novo variant in the TMEM106B gene.DiscussionHyperkinetic movement disorders and seizures may be early symptoms of TMEM106B-HLD. Our observation, supported by video EEG recordings, emphasizes that seizures may be difficult to recognize from movement disorders and that epilepsy may be a severe and prominent symptom of the disease. TMEM106B-HLD should be considered in the genetic screening of infants with early-onset seizures and movement disorders.
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Affiliation(s)
- Roberta Solazzi
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Marco Moscatelli
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Davide Rossi Sebastiano
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Laura Canafoglia
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Laura Pezzoli
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Maria Iascone
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Tiziana Granata
- Department of Pediatric Neuroscience (R.S., T.G.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Neuroradiology Unit (M.M.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Biomedical Sciences for Health (M.M.), University of Milan, Italy; Neurophysiology Unit (D.R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Integrated Diagnostics for Epilepsy (L.C.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; and Medical Genetics Laboratory (L.P., M.I.), ASST Papa Giovanni XXIII, Bergamo, Italy
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Fell CW, Hagelkruys A, Cicvaric A, Horrer M, Liu L, Li JSS, Stadlmann J, Polyansky AA, Mereiter S, Tejada MA, Kokotović T, Achuta VS, Scaramuzza A, Twyman KA, Morrow MM, Juusola J, Yan H, Wang J, Burmeister M, Choudhury B, Andersen TL, Wirnsberger G, Holmskov U, Perrimon N, Žagrović B, Monje FJ, Moeller JB, Penninger JM, Nagy V. FIBCD1 is an endocytic GAG receptor associated with a novel neurodevelopmental disorder. EMBO Mol Med 2022; 14:e15829. [PMID: 35916241 PMCID: PMC9449597 DOI: 10.15252/emmm.202215829] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/21/2022] Open
Abstract
Whole-exome sequencing of two patients with idiopathic complex neurodevelopmental disorder (NDD) identified biallelic variants of unknown significance within FIBCD1, encoding an endocytic acetyl group-binding transmembrane receptor with no known function in the central nervous system. We found that FIBCD1 preferentially binds and endocytoses glycosaminoglycan (GAG) chondroitin sulphate-4S (CS-4S) and regulates GAG content of the brain extracellular matrix (ECM). In silico molecular simulation studies and GAG binding analyses of patient variants determined that such variants are loss-of-function by disrupting FIBCD1-CS-4S association. Gene knockdown in flies resulted in morphological disruption of the neuromuscular junction and motor-related behavioural deficits. In humans and mice, FIBCD1 is expressed in discrete brain regions, including the hippocampus. Fibcd1 KO mice exhibited normal hippocampal neuronal morphology but impaired hippocampal-dependent learning. Further, hippocampal synaptic remodelling in acute slices from Fibcd1 KO mice was deficient but restored upon enzymatically modulating the ECM. Together, we identified FIBCD1 as an endocytic receptor for GAGs in the brain ECM and a novel gene associated with an NDD, revealing a critical role in nervous system structure, function and plasticity.
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Affiliation(s)
- Christopher W Fell
- Ludwig Boltzmann Institute for Rare and Undiagnosed DiseasesViennaAustria
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Department of NeurologyMedical University of ViennaViennaAustria
| | - Astrid Hagelkruys
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
| | - Ana Cicvaric
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and PharmacologyMedical University of ViennaViennaAustria
- Department of Psychiatry and Behavioral Sciences, Feinberg School of MedicineNorthwestern UniversityChicagoILUSA
| | - Marion Horrer
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
| | - Lucy Liu
- Department of Genetics, Harvard Medical SchoolHoward Hughes Medical InstituteBostonMAUSA
| | - Joshua Shing Shun Li
- Department of Genetics, Harvard Medical SchoolHoward Hughes Medical InstituteBostonMAUSA
| | - Johannes Stadlmann
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
- Institute of BiochemistryUniversity of Natural Resource and Life SciencesViennaAustria
| | - Anton A Polyansky
- Department of Structural and Computational Biology, Max Perutz LabsUniversity of ViennaViennaAustria
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic ChemistryRussian Academy of SciencesMoscowRussia
| | - Stefan Mereiter
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
| | - Miguel Angel Tejada
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
- Research Unit on Women's Health‐Institute of Health Research INCLIVAValenciaSpain
| | - Tomislav Kokotović
- Ludwig Boltzmann Institute for Rare and Undiagnosed DiseasesViennaAustria
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Department of NeurologyMedical University of ViennaViennaAustria
| | - Venkat Swaroop Achuta
- Ludwig Boltzmann Institute for Rare and Undiagnosed DiseasesViennaAustria
- Department of NeurologyMedical University of ViennaViennaAustria
| | - Angelica Scaramuzza
- Ludwig Boltzmann Institute for Rare and Undiagnosed DiseasesViennaAustria
- Department of NeurologyMedical University of ViennaViennaAustria
| | | | | | | | - Huifang Yan
- Department of PediatricsPeking University First HospitalBeijingChina
- Joint International Research Center of Translational and Clinical ResearchBeijingChina
| | - Jingmin Wang
- Department of PediatricsPeking University First HospitalBeijingChina
- Joint International Research Center of Translational and Clinical ResearchBeijingChina
| | - Margit Burmeister
- Michigan Neuroscience InstituteUniversity of MichiganAnn ArborMIUSA
- Departments of Computational Medicine & Bioinformatics, Psychiatry and Human GeneticsUniversity of MichiganAnn ArborMIUSA
| | - Biswa Choudhury
- Department of Cellular and Molecular MedicineUCSDLa JollaCAUSA
| | - Thomas Levin Andersen
- Clinical Cell Biology, Department of PathologyOdense University HospitalOdenseDenmark
- Pathology Research Unit, Department of Clinical Research and Department of Molecular MedicineUniversity of Southern DenmarkOdenseDenmark
| | - Gerald Wirnsberger
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
- Apeiron Biologics AG, Vienna BioCenter CampusViennaAustria
| | - Uffe Holmskov
- Cancer and Inflammation Research, Department of Molecular MedicineUniversity of Southern DenmarkOdenseDenmark
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical SchoolHoward Hughes Medical InstituteBostonMAUSA
| | - Bojan Žagrović
- Department of Structural and Computational Biology, Max Perutz LabsUniversity of ViennaViennaAustria
| | - Francisco J Monje
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and PharmacologyMedical University of ViennaViennaAustria
| | - Jesper Bonnet Moeller
- Cancer and Inflammation Research, Department of Molecular MedicineUniversity of Southern DenmarkOdenseDenmark
- Danish Institute for Advanced StudyUniversity of Southern DenmarkOdenseDenmark
| | - Josef M Penninger
- VBC – Vienna BioCenter CampusIMBA, Institute of Molecular Biotechnology of the Austrian Academy of SciencesViennaAustria
- Department of Medical Genetics, Life Science InstituteUniversity of British ColumbiaVancouverBCCanada
| | - Vanja Nagy
- Ludwig Boltzmann Institute for Rare and Undiagnosed DiseasesViennaAustria
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Department of NeurologyMedical University of ViennaViennaAustria
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20
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Yan H, Yang S, Hou Y, Ali S, Escobar A, Gao K, Duan R, Kubisiak T, Wang J, Zhang Y, Xiao J, Jiang Y, Zhang T, Wu Y, Burmeister M, Wang Q, Cuajungco MP, Wang J. Functional Study of TMEM163 Gene Variants Associated with Hypomyelination Leukodystrophy. Cells 2022; 11:cells11081285. [PMID: 35455965 PMCID: PMC9031525 DOI: 10.3390/cells11081285] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/19/2022] [Accepted: 04/06/2022] [Indexed: 02/06/2023] Open
Abstract
Hypomyelinating leukodystrophies (HLDs) are a rare group of heterogeneously genetic disorders characterized by persistent deficit of myelin observed on magnetic resonance imaging (MRI). To identify a new disease-associated gene of HLD, trio-based whole exome sequencing was performed for unexplained patients with HLD. Functional studies were performed to confirm the phenotypic effect of candidate protein variants. Two de novo heterozygous variants, c.227T>G p.(L76R) or c.227T>C p.(L76P) in TMEM163 were identified in two unrelated HLD patients. TMEM163 protein is a zinc efflux transporter localized within the plasma membrane, lysosomes, early endosomes, and other vesicular compartments. It has not been associated with hypomyelination. Functional zinc flux assays in HeLa cells stably-expressing TMEM163 protein variants, L76R and L76P, revealed distinct attenuation or enhancement of zinc efflux, respectively. Experiments using a zebrafish model with knockdown of tmem163a and tmem163b (morphants) showed that loss of tmem163 causes dysplasia of the larvae, locomotor disability and myelin deficit. Expression of human wild type TMEM163 mRNAs in morphants rescues the phenotype, while the TMEM163 L76P and L76R mutants aggravated the condition. Moreover, poor proliferation, elevated apoptosis of oligodendrocytes, and reduced oligodendrocytes and neurons were also observed in zebrafish morphants. Our findings suggest an unappreciated role for TMEM163 protein in myelin development and add TMEM163 to a growing list of genes associated with hypomyelination leukodystrophy.
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Affiliation(s)
- Huifang Yan
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
- Joint International Research Center of Translational and Clinical Research, Beijing 100191, China
- Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing 100034, China
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA; (T.K.); (M.B.)
| | - Shuyan Yang
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing 100020, China; (S.Y.); (T.Z.)
| | - Yiming Hou
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China; (Y.H.); (Q.W.)
| | - Saima Ali
- Department of Biological Science, California State University, Fullerton, CA 92831, USA; (S.A.); (A.E.)
| | - Adrian Escobar
- Department of Biological Science, California State University, Fullerton, CA 92831, USA; (S.A.); (A.E.)
| | - Kai Gao
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
| | - Ruoyu Duan
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
| | - Thomas Kubisiak
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA; (T.K.); (M.B.)
| | - Junyu Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
| | - Yu Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
| | - Jiangxi Xiao
- Department of Radiology, Peking University First Hospital, Beijing 100034, China;
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
- Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing 100034, China
- Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing 100191, China
| | - Ting Zhang
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing 100020, China; (S.Y.); (T.Z.)
| | - Ye Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
- Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing 100034, China
| | - Margit Burmeister
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA; (T.K.); (M.B.)
- Departments of Computational Medicine & Bioinformatics, Psychiatry and Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Qiang Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China; (Y.H.); (Q.W.)
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Math P. Cuajungco
- Department of Biological Science, California State University, Fullerton, CA 92831, USA; (S.A.); (A.E.)
- Center for Applied Biotechnology Studies, California State University, Fullerton, CA 92831, USA
- Correspondence: (M.P.C.); (J.W.)
| | - Jingmin Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; (H.Y.); (K.G.); (R.D.); (J.W.); (Y.Z.); (Y.J.); (Y.W.)
- Joint International Research Center of Translational and Clinical Research, Beijing 100191, China
- Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing 100034, China
- Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing 100191, China
- Correspondence: (M.P.C.); (J.W.)
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21
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Fukumura S, Hiraide T, Yamamoto A, Tsuchida K, Aoto K, Nakashima M, Saitsu H. A novel de novo TMEM63A variant in a patient with severe hypomyelination and global developmental delay. Brain Dev 2022; 44:178-183. [PMID: 34598833 DOI: 10.1016/j.braindev.2021.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/10/2021] [Accepted: 09/14/2021] [Indexed: 11/15/2022]
Abstract
BACKGROUND Heterozygous variants in TMEM63A have been recently identified as the cause of infantile-onset transient hypomyelination. To date, four TMEM63A variants have been reported in five patients. These patients exhibited favorable clinical course, developmental progress, and completion of myelination. CASE REPORT The patient was a 5-year-old girl with severe global developmental delay, absent speech, no turning over, no gazing, hypotonia, and daily episodes of autonomic seizures. Brain MRI showed hypomyelination of deep and subcortical white matter that appeared hyperintense in T2-weighted imaging from 2 months of age and that showed no change at 4 years of age. Exome sequencing of the patient and her parents revealed a novel de novo missense variant, NM_014698.3:c.1658G>T, p.(Gly553Val), in the TMEM63A gene, which was confirmed by Sanger sequencing. The variant has not been registered in public databases, and it substitutes a highly conserved glycine residue located in a pore-lining transmembrane helix. No other candidate variants were identified. CONCLUSIONS Although TMEM63A variants are generally thought to cause transient hypomyelination with favorable developmental progress, identification of a de novo TMEM63A variant in our patient suggests that the TMEM63A-related clinical spectrum is broad and includes severe developmental delay with seizures.
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Affiliation(s)
- Shinobu Fukumura
- Department of Pediatrics, Sapporo Medical University School of Medicine, Sapporo, Japan.
| | - Takuya Hiraide
- Biochemistry Department, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Akiyo Yamamoto
- Department of Pediatrics, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Kousuke Tsuchida
- Department of Pediatrics, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Kazushi Aoto
- Biochemistry Department, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Mitsuko Nakashima
- Biochemistry Department, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hirotomo Saitsu
- Biochemistry Department, Hamamatsu University School of Medicine, Hamamatsu, Japan
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22
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Naseer MI, Abdulkareem AA, Pushparaj PN, Saharti S, Muthaffar OY. Next-Generation Sequencing Reveals Novel Homozygous Missense Variant c.934T > C in POLR1C Gene Causing Leukodystrophy and Hypomyelinating Disease. Front Pediatr 2022; 10:862722. [PMID: 35685919 PMCID: PMC9171136 DOI: 10.3389/fped.2022.862722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
Leukodystrophies are a diverse group of genetically established disorders categorized by unusual white matter changes on brain imaging. Hypomyelinating leukodystrophies (HLDs) are a group of neurodevelopmental disorders that affect myelin sheath development in the brain. These disorders are categorized as developmental delay, spasticity, hypotonia, and intellectual disabilities. We describe a patient with developmental delay, cerebellar ataxia, spasticity, hypotonia, and intellectual disability from a healthy family member. Whole exome sequencing (WES) was performed to identify causative variants, which were further analyzed by bioinformatic analysis. WES was performed, and Sanger sequencing-based segregation analysis confirmed the presence of the homozygous missense variants of NM_203290.3 c.934T > C p.Ser312Pro of RNA polymerase I and III subunit C (POLR1C) gene in this patient and heterozygous variant in the unaffected carrier father and mother, supporting the pathogenicity and inheritance pattern of this variant. Furthermore, the variant identified by WES was validated in healthy controls (n = 100) using Sanger sequencing analysis. Finally, our study explained the important use of WES in disease diagnosis and provided further evidence that the variant in the POLR1C gene may play an important role in the development of hypomyelinating leukodystrophy in Saudi families.
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Affiliation(s)
- Muhammad Imran Naseer
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Angham Abdulrahman Abdulkareem
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Peter Natesan Pushparaj
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Pharmacology, Center for Transdisciplinary Research, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Chennai, India
| | - Samah Saharti
- Department of Pathology and Microbiology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Osama Y Muthaffar
- Department of Pediatrics, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
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23
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Pingault V, Zerad L, Bertani-Torres W, Bondurand N. SOX10: 20 years of phenotypic plurality and current understanding of its developmental function. J Med Genet 2021; 59:105-114. [PMID: 34667088 PMCID: PMC8788258 DOI: 10.1136/jmedgenet-2021-108105] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/19/2021] [Indexed: 12/25/2022]
Abstract
SOX10 belongs to a family of 20 SRY (sex-determining region Y)-related high mobility group box-containing (SOX) proteins, most of which contribute to cell type specification and differentiation of various lineages. The first clue that SOX10 is essential for development, especially in the neural crest, came with the discovery that heterozygous mutations occurring within and around SOX10 cause Waardenburg syndrome type 4. Since then, heterozygous mutations have been reported in Waardenburg syndrome type 2 (Waardenburg syndrome type without Hirschsprung disease), PCWH or PCW (peripheral demyelinating neuropathy, central dysmyelination, Waardenburg syndrome, with or without Hirschsprung disease), intestinal manifestations beyond Hirschsprung (ie, chronic intestinal pseudo-obstruction), Kallmann syndrome and cancer. All of these diseases are consistent with the regulatory role of SOX10 in various neural crest derivatives (melanocytes, the enteric nervous system, Schwann cells and olfactory ensheathing cells) and extraneural crest tissues (inner ear, oligodendrocytes). The recent evolution of medical practice in constitutional genetics has led to the identification of SOX10 variants in atypical contexts, such as isolated hearing loss or neurodevelopmental disorders, making them more difficult to classify in the absence of both a typical phenotype and specific expertise. Here, we report novel mutations and review those that have already been published and their functional consequences, along with current understanding of SOX10 function in the affected cell types identified through in vivo and in vitro models. We also discuss research options to increase our understanding of the origin of the observed phenotypic variability and improve the diagnosis and medical care of affected patients.
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Affiliation(s)
- Veronique Pingault
- Department of Embryology and Genetics of Malformations, INSERM UMR 1163, Université de Paris and Institut Imagine, Paris, France .,Service de Génétique des Maladies Rares, AP-HP, Hopital Necker-Enfants Malades, Paris, France
| | - Lisa Zerad
- Department of Embryology and Genetics of Malformations, INSERM UMR 1163, Université de Paris and Institut Imagine, Paris, France
| | - William Bertani-Torres
- Department of Embryology and Genetics of Malformations, INSERM UMR 1163, Université de Paris and Institut Imagine, Paris, France
| | - Nadege Bondurand
- Department of Embryology and Genetics of Malformations, INSERM UMR 1163, Université de Paris and Institut Imagine, Paris, France
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