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Witkowski G, Szulczyk B, Nurowska E, Jurek M, Pasierski M, Lipiec A, Charzewska A, Dawidziuk M, Milewski M, Owsiak S, Rola R, Sienkiewicz Jarosz H, Hoffman-Zacharska D. Functional Characteristics of the Nav1.1 p.Arg1596Cys Mutation Associated with Varying Severity of Epilepsy Phenotypes. Int J Mol Sci 2024; 25:1745. [PMID: 38339022 PMCID: PMC10855957 DOI: 10.3390/ijms25031745] [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: 12/29/2023] [Revised: 01/20/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Mutations of the SCN1A gene, which encodes the voltage-dependent Na+ channel's α subunit, are associated with diverse epileptic syndromes ranging in severity, even intra-family, from febrile seizures to epileptic encephalopathy. The underlying cause of this variability is unknown, suggesting the involvement of additional factors. The aim of our study was to describe the properties of mutated channels and investigate genetic causes for clinical syndromes' variability in the family of five SCN1A gene p.Arg1596Cys mutation carriers. The analysis of additional genetic factors influencing SCN1A-associated phenotypes was conducted through exome sequencing (WES). To assess the impact of mutations, we used patch clamp analysis of mutated channels expressed in HEK cells and in vivo neural excitability studies (NESs). In cells expressing the mutant channel, sodium currents were reduced. NESs indicated increased excitability of peripheral motor neurons in mutation carriers. WES showed the absence of non-SCA1 pathogenic variants that could be causative of disease in the family. Variants of uncertain significance in three genes, as potential modifiers of the most severe phenotype, were identified. The p.Arg1596Cys substitution inhibits channel function, affecting steady-state inactivation kinetics. Its clinical manifestations involve not only epileptic symptoms but also increased excitability of peripheral motor fibers. The role of Nav1.1 in excitatory neurons cannot be ruled out as a significant factor of the clinical phenotype.
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Affiliation(s)
- Grzegorz Witkowski
- First Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland; (S.O.); (H.S.J.)
- Military Institute of Aviation Medicine, Krasinskiego 54/56, 01-755 Warsaw, Poland;
| | - Bartlomiej Szulczyk
- Chair and Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, The Medical University of Warsaw, Banacha 1b, 02-097 Warsaw, Poland; (B.S.); (E.N.); (M.P.)
| | - Ewa Nurowska
- Chair and Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, The Medical University of Warsaw, Banacha 1b, 02-097 Warsaw, Poland; (B.S.); (E.N.); (M.P.)
| | - Marta Jurek
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Michal Pasierski
- Chair and Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, The Medical University of Warsaw, Banacha 1b, 02-097 Warsaw, Poland; (B.S.); (E.N.); (M.P.)
| | - Agata Lipiec
- Clinic of Pediatric Neurology, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland;
| | - Agnieszka Charzewska
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Mateusz Dawidziuk
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Michal Milewski
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Szymon Owsiak
- First Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland; (S.O.); (H.S.J.)
| | - Rafal Rola
- Military Institute of Aviation Medicine, Krasinskiego 54/56, 01-755 Warsaw, Poland;
| | - Halina Sienkiewicz Jarosz
- First Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland; (S.O.); (H.S.J.)
| | - Dorota Hoffman-Zacharska
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
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Marom R, Zhang B, Washington ME, Song IW, Burrage LC, Rossi VC, Berrier AS, Lindsey A, Lesinski J, Nonet ML, Chen J, Baldridge D, Silverman GA, Sutton VR, Rosenfeld JA, Tran AA, Hicks MJ, Murdock DR, Dai H, Weis M, Jhangiani SN, Muzny DM, Gibbs RA, Caswell R, Pottinger C, Cilliers D, Stals K, Eyre D, Krakow D, Schedl T, Pak SC, Lee BH. Dominant negative variants in KIF5B cause osteogenesis imperfecta via down regulation of mTOR signaling. PLoS Genet 2023; 19:e1011005. [PMID: 37934770 PMCID: PMC10656020 DOI: 10.1371/journal.pgen.1011005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 11/17/2023] [Accepted: 10/03/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Kinesin motor proteins transport intracellular cargo, including mRNA, proteins, and organelles. Pathogenic variants in kinesin-related genes have been implicated in neurodevelopmental disorders and skeletal dysplasias. We identified de novo, heterozygous variants in KIF5B, encoding a kinesin-1 subunit, in four individuals with osteogenesis imperfecta. The variants cluster within the highly conserved kinesin motor domain and are predicted to interfere with nucleotide binding, although the mechanistic consequences on cell signaling and function are unknown. METHODS To understand the in vivo genetic mechanism of KIF5B variants, we modeled the p.Thr87Ile variant that was found in two patients in the C. elegans ortholog, unc-116, at the corresponding position (Thr90Ile) by CRISPR/Cas9 editing and performed functional analysis. Next, we studied the cellular and molecular consequences of the recurrent p.Thr87Ile variant by microscopy, RNA and protein analysis in NIH3T3 cells, primary human fibroblasts and bone biopsy. RESULTS C. elegans heterozygous for the unc-116 Thr90Ile variant displayed abnormal body length and motility phenotypes that were suppressed by additional copies of the wild type allele, consistent with a dominant negative mechanism. Time-lapse imaging of GFP-tagged mitochondria showed defective mitochondria transport in unc-116 Thr90Ile neurons providing strong evidence for disrupted kinesin motor function. Microscopy studies in human cells showed dilated endoplasmic reticulum, multiple intracellular vacuoles, and abnormal distribution of the Golgi complex, supporting an intracellular trafficking defect. RNA sequencing, proteomic analysis, and bone immunohistochemistry demonstrated down regulation of the mTOR signaling pathway that was partially rescued with leucine supplementation in patient cells. CONCLUSION We report dominant negative variants in the KIF5B kinesin motor domain in individuals with osteogenesis imperfecta. This study expands the spectrum of kinesin-related disorders and identifies dysregulated signaling targets for KIF5B in skeletal development.
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Affiliation(s)
- Ronit Marom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children’s Hospital, Houston, Texas, United States of America
| | - Bo Zhang
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Megan E. Washington
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - I-Wen Song
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lindsay C. Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children’s Hospital, Houston, Texas, United States of America
| | - Vittoria C. Rossi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children’s Hospital, Houston, Texas, United States of America
| | - Ava S. Berrier
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anika Lindsey
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Jacob Lesinski
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Michael L. Nonet
- Department of Neuroscience, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Jian Chen
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Dustin Baldridge
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Gary A. Silverman
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - V. Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children’s Hospital, Houston, Texas, United States of America
| | - Jill A. Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Alyssa A. Tran
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - M. John Hicks
- Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - David R. Murdock
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hongzheng Dai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - MaryAnn Weis
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America
| | - Shalini N. Jhangiani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Donna M. Muzny
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Richard A. Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Richard Caswell
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom
| | - Carrie Pottinger
- All Wales Medical Genomics Service, Wrexham Maelor Hospital, Wrexham, UK
| | - Deirdre Cilliers
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Karen Stals
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom
| | | | - David Eyre
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America
| | - Deborah Krakow
- Human Genetics, Obstetrics & Gynecology, Orthopedic Surgery, University of California, Los Angeles, California, United States of America
| | - Tim Schedl
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Stephen C. Pak
- Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Brendan H. Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children’s Hospital, Houston, Texas, United States of America
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