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Rönkkö J, Rodriguez Y, Rasila T, Torregrosa-Muñumer R, Pennonen J, Kvist J, Kuuluvainen E, Bosch LVD, Hietakangas V, Bultynck G, Tyynismaa H, Ylikallio E. Human IP 3 receptor triple knockout stem cells remain pluripotent despite altered mitochondrial metabolism. Cell Calcium 2023; 114:102782. [PMID: 37481871 DOI: 10.1016/j.ceca.2023.102782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/14/2023] [Accepted: 07/13/2023] [Indexed: 07/25/2023]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are ER Ca2+-release channels that control a broad set of cellular processes. Animal models lacking IP3Rs in different combinations display severe developmental phenotypes. Given the importance of IP3Rs in human diseases, we investigated their role in human induced pluripotent stem cells (hiPSC) by developing single IP3R and triple IP3R knockouts (TKO). Genome edited TKO-hiPSC lacking all three IP3R isoforms, IP3R1, IP3R2, IP3R3, failed to generate Ca2+ signals in response to agonists activating GPCRs, but retained stemness and pluripotency. Steady state metabolite profiling and flux analysis of TKO-hiPSC indicated distinct alterations in tricarboxylic acid cycle metabolites consistent with a deficiency in their pyruvate utilization via pyruvate dehydrogenase, shifting towards pyruvate carboxylase pathway. These results demonstrate that IP3Rs are not essential for hiPSC identity and pluripotency but regulate mitochondrial metabolism. This set of knockout hiPSC is a valuable resource for investigating IP3Rs in human cell types of interest.
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Affiliation(s)
- Julius Rönkkö
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Yago Rodriguez
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Tiina Rasila
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Rubén Torregrosa-Muñumer
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Jana Pennonen
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Jouni Kvist
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Emilia Kuuluvainen
- Molecular and Integrative Bioscience Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, 00790, Finland
| | - Ludo Van Den Bosch
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute, KU Leuven - University of Leuven, 3000, Leuven, Belgium; VIB Center for Brain & Disease Research, Laboratory of Neurobiology, 3000, Leuven, Belgium
| | - Ville Hietakangas
- Molecular and Integrative Bioscience Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, 00790, Finland
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Leuven, 3000, Belgium
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, 00290, Finland.
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Terry LE, Arige V, Neumann J, Wahl AM, Knebel TR, Chaffer JW, Malik S, Liston A, Humblet-Baron S, Bultynck G, Yule DI. Missense mutations in inositol 1,4,5-trisphosphate receptor type 3 result in leaky Ca 2+ channels and activation of store-operated Ca 2+ entry. iScience 2022; 25:105523. [PMID: 36444295 PMCID: PMC9700043 DOI: 10.1016/j.isci.2022.105523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/10/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
Mutations in all subtypes of the inositol 1,4,5-trisphosphate receptor Ca2+ release channel are associated with human diseases. In this report, we investigated the functionality of three neuropathy-associated missense mutations in IP3R3 (V615M, T1424M, and R2524C). The mutants only exhibited function when highly over-expressed compared to endogenous hIP3R3. All variants resulted in elevated basal cytosolic Ca2+ levels, decreased endoplasmic reticulum Ca2+ store content, and constitutive store-operated Ca2+ entry in the absence of any stimuli, consistent with a leaky IP3R channel pore. These variants differed in channel function; when stably over-expressed the R2524C mutant was essentially dead, V615M was poorly functional, and T1424M exhibited activity greater than that of the corresponding wild-type following threshold stimulation. These results demonstrate that a common feature of these mutations is decreased IP3R3 function. In addition, these mutations exhibit a novel phenotype manifested as a constitutively open channel, which inappropriately gates SOCE in the absence of stimulation.
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Affiliation(s)
- Lara E. Terry
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - Vikas Arige
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - Julika Neumann
- KU Leuven, Department of Microbiology and Immunology, Leuven, Belgium
| | - Amanda M. Wahl
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - Taylor R. Knebel
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - James W. Chaffer
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - Sundeep Malik
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - Adrian Liston
- KU Leuven, Department of Microbiology and Immunology, Leuven, Belgium
| | | | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - David I. Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
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Rönkkö J, Molchanova S, Revah‐Politi A, Pereira EM, Auranen M, Toppila J, Kvist J, Ludwig A, Neumann J, Bultynck G, Humblet‐Baron S, Liston A, Paetau A, Rivera C, Harms MB, Tyynismaa H, Ylikallio E. Dominant mutations in ITPR3 cause Charcot-Marie-Tooth disease. Ann Clin Transl Neurol 2020; 7:1962-1972. [PMID: 32949214 PMCID: PMC7545616 DOI: 10.1002/acn3.51190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVE ITPR3, encoding inositol 1,4,5-trisphosphate receptor type 3, was previously reported as a potential candidate disease gene for Charcot-Marie-Tooth neuropathy. Here, we present genetic and functional evidence that ITPR3 is a Charcot-Marie-Tooth disease gene. METHODS Whole-exome sequencing of four affected individuals in an autosomal dominant family and one individual who was the only affected individual in his family was used to identify disease-causing variants. Skin fibroblasts from two individuals of the autosomal dominant family were analyzed functionally by western blotting, quantitative reverse transcription PCR, and Ca2+ imaging. RESULTS Affected individuals in the autosomal dominant family had onset of symmetrical neuropathy with demyelinating and secondary axonal features at around age 30, showing signs of gradual progression with severe distal leg weakness and hand involvement in the proband at age 64. Exome sequencing identified a heterozygous ITPR3 p.Val615Met variant segregating with the disease. The individual who was the only affected in his family had disease onset at age 4 with demyelinating neuropathy. His condition was progressive, leading to severe muscle atrophy below knees and atrophy of proximal leg and hand muscles by age 16. Trio exome sequencing identified a de novo ITPR3 variant p.Arg2524Cys. Altered Ca2+ -transients in p.Val615Met patient fibroblasts suggested that the variant has a dominant-negative effect on inositol 1,4,5-trisphosphate receptor type 3 function. INTERPRETATION Together with two previously identified variants, our report adds further evidence that ITPR3 is a disease-causing gene for CMT and indicates altered Ca2+ homeostasis in disease pathogenesis.
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Affiliation(s)
- Julius Rönkkö
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Svetlana Molchanova
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Molecular and Integrative Biosciences Research ProgramFaculty of Bio‐ and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Anya Revah‐Politi
- Institute for Genomic MedicineColumbia University Medical CenterNew YorkNew YorkUSA
- Precision Genomics LaboratoryColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Elaine M. Pereira
- Department of PediatricsColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Mari Auranen
- Clinical NeurosciencesNeurologyUniversity of Helsinki and Helsinki University HospitalHelsinkiFinland
| | - Jussi Toppila
- Department of Clinical NeurophysiologyMedical Imaging CenterHelsinki University Central HospitalHelsinkiFinland
| | - Jouni Kvist
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Anastasia Ludwig
- Neuroscience CenterHelsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
| | - Julika Neumann
- Department of Microbiology and ImmunologyLaboratory of Adaptive ImmunityKU LeuvenLeuvenBelgium
- VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular SignalingDepartment of Cellular and Molecular Medicine & Leuven Kanker InstituutKU LeuvenLeuvenBelgium
| | | | - Adrian Liston
- Department of Microbiology and ImmunologyLaboratory of Adaptive ImmunityKU LeuvenLeuvenBelgium
- VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- Laboratory of Lymphocyte Signalling and DevelopmentBabraham InstituteCambridgeUnited Kingdom
| | - Anders Paetau
- Department of PathologyHUSLAB and University of HelsinkiHelsinkiFinland
| | - Claudio Rivera
- Neuroscience CenterHelsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
- Institut de Neurobiologie de la Méditerranée INMED UMR901MarseilleFrance
| | | | - Henna Tyynismaa
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Neuroscience CenterHelsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
- Department of Medical and Clinical GeneticsUniversity of HelsinkiHelsinkiFinland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Clinical NeurosciencesNeurologyUniversity of Helsinki and Helsinki University HospitalHelsinkiFinland
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4
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Nakamura DS, Lin YH, Khan D, Gothié JDM, de Faria O, Dixon JA, McBride HM, Antel JP, Kennedy TE. Mitochondrial dynamics and bioenergetics regulated by netrin-1 in oligodendrocytes. Glia 2020; 69:392-412. [PMID: 32910475 DOI: 10.1002/glia.23905] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 01/01/2023]
Abstract
Mitochondria are dynamic organelles that produce energy and molecular precursors that are essential for myelin synthesis. Unlike in neurons, mitochondria in oligodendrocytes increase intracellular movement in response to glutamatergic activation and are more susceptible to oxidative stress than in astrocytes or microglia. The signaling pathways that regulate these cell type-specific mitochondrial responses in oligodendrocytes are not understood. Here, we visualized mitochondria migrating through thin cytoplasmic channels crossing myelin basic protein-positive compacted membranes and localized within paranodal loop cytoplasm. We hypothesized that local extracellular enrichment of netrin-1 might regulate the recruitment and function of paranodal proteins and organelles, including mitochondria. We identified rapid recruitment of mitochondria and paranodal proteins, including neurofascin 155 (NF155) and the netrin receptor deleted in colorectal carcinoma (DCC), to sites of contact between oligodendrocytes and netrin-1-coated microbeads in vitro. We provide evidence that Src-family kinase activation and Rho-associated protein kinase (ROCK) inhibition downstream of netrin-1 induces mitochondrial elongation, hyperpolarization of the mitochondrial inner membrane, and increases glycolysis. Our findings identify a signaling mechanism in oligodendrocytes that is sufficient to locally recruit paranodal proteins and regulate the subcellular localization, morphology, and function of mitochondria.
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Affiliation(s)
- Diane S Nakamura
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Yun Hsuan Lin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Damla Khan
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Jean-David M Gothié
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Omar de Faria
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - James A Dixon
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Heidi M McBride
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Jack P Antel
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Timothy E Kennedy
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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5
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Bortolozzi M. What's the Function of Connexin 32 in the Peripheral Nervous System? Front Mol Neurosci 2018; 11:227. [PMID: 30042657 PMCID: PMC6048289 DOI: 10.3389/fnmol.2018.00227] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 06/11/2018] [Indexed: 12/26/2022] Open
Abstract
Connexin 32 (Cx32) is a fundamental protein in the peripheral nervous system (PNS) as its mutations cause the X-linked form of Charcot–Marie–Tooth disease (CMT1X), the second most common form of hereditary motor and sensory neuropathy and a demyelinating disease for which there is no effective therapy. Since mutations of the GJB1 gene encoding Cx32 were first reported in 1993, over 450 different mutations associated with CMT1X including missense, frameshift, deletion and non-sense ones have been identified. Despite the availability of a sizable number of studies focusing on normal and mutated Cx32 channel properties, the crucial role played by Cx32 in the PNS has not yet been elucidated, as well as the molecular pathogenesis of CMT1X. Is Cx32 fundamental during a particular phase of Schwann cell (SC) life? Are Cx32 paired (gap junction, GJ) channels in myelinated SCs important for peripheral nerve homeostasis? The attractive hypothesis that short coupling of adjacent myelin layers by Cx32 GJs is required for efficient diffusion of K+ and signaling molecules is still debated, while a growing body of evidence is supporting other possible functions of Cx32 in the PNS, mainly related to Cx32 unpaired channels (hemichannels), which could be involved in a purinergic-dependent pathway controlling myelination. Here we review the intriguing puzzle of findings about Cx32 function and dysfunction, discussing possible directions for future investigation.
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Affiliation(s)
- Mario Bortolozzi
- Department of Physics and Astronomy G. Galilei, University of Padua, Padua, Italy.,Venetian Institute of Molecular Medicine (VIMM), Padua, Italy.,Padova Neuroscience Center (PNC), Padua, Italy
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6
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Poitelon Y, Matafora V, Silvestri N, Zambroni D, McGarry C, Serghany N, Rush T, Vizzuso D, Court FA, Bachi A, Wrabetz L, Feltri ML. A dual role for Integrin α6β4 in modulating hereditary neuropathy with liability to pressure palsies. J Neurochem 2018; 145:245-257. [PMID: 29315582 DOI: 10.1111/jnc.14295] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 12/14/2017] [Accepted: 12/21/2017] [Indexed: 12/23/2022]
Abstract
Peripheral myelin protein 22 (PMP22) is a component of compact myelin in the peripheral nervous system. The amount of PMP22 in myelin is tightly regulated, and PMP22 over or under-expression cause Charcot-Marie-Tooth 1A (CMT1A) and Hereditary Neuropathy with Pressure Palsies (HNPP). Despite the importance of PMP22, its function remains largely unknown. It was reported that PMP22 interacts with the β4 subunit of the laminin receptor α6β4 integrin, suggesting that α6β4 integrin and laminins may contribute to the pathogenesis of CMT1A or HNPP. Here we asked if the lack of α6β4 integrin in Schwann cells influences myelin stability in the HNPP mouse model. Our data indicate that PMP22 and β4 integrin may not interact directly in myelinating Schwann cells, however, ablating β4 integrin delays the formation of tomacula, a characteristic feature of HNPP. In contrast, ablation of integrin β4 worsens nerve conduction velocities and non-compact myelin organization in HNPP animals. This study demonstrates that indirect interactions between an extracellular matrix receptor and a myelin protein influence the stability and function of myelinated fibers.
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Affiliation(s)
- Yannick Poitelon
- Hunter James Kelly Research Institute, University at Buffalo, Buffalo, New York, USA.,Department of Biochemistry, University at Buffalo, Buffalo, New York, USA
| | - Vittoria Matafora
- Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy
| | | | - Desirée Zambroni
- Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy
| | - Claire McGarry
- Department of Biochemistry, University at Buffalo, Buffalo, New York, USA
| | - Nora Serghany
- Department of Biochemistry, University at Buffalo, Buffalo, New York, USA
| | - Thomas Rush
- Department of Biochemistry, University at Buffalo, Buffalo, New York, USA
| | - Domenica Vizzuso
- Hunter James Kelly Research Institute, University at Buffalo, Buffalo, New York, USA.,Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy
| | - Felipe A Court
- Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy.,Center for Integrative Biology, Universidad Mayor de Chile, Santiago, Chile
| | - Angela Bachi
- Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy
| | - Lawrence Wrabetz
- Hunter James Kelly Research Institute, University at Buffalo, Buffalo, New York, USA.,Department of Biochemistry, University at Buffalo, Buffalo, New York, USA.,Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy.,Department of Neurology, University at Buffalo, Buffalo, New York, USA
| | - Maria Laura Feltri
- Hunter James Kelly Research Institute, University at Buffalo, Buffalo, New York, USA.,Department of Biochemistry, University at Buffalo, Buffalo, New York, USA.,Division of Genetics and Cell Biology, San Raffaele Hospital, Milan, Italy.,Department of Neurology, University at Buffalo, Buffalo, New York, USA
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7
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Olympiou M, Sargiannidou I, Markoullis K, Karaiskos C, Kagiava A, Kyriakoudi S, Abrams CK, Kleopa KA. Systemic inflammation disrupts oligodendrocyte gap junctions and induces ER stress in a model of CNS manifestations of X-linked Charcot-Marie-Tooth disease. Acta Neuropathol Commun 2016; 4:95. [PMID: 27585976 PMCID: PMC5009701 DOI: 10.1186/s40478-016-0369-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 11/10/2022] Open
Abstract
X-linked Charcot-Marie-Tooth disease (CMT1X) is a common form of inherited neuropathy resulting from different mutations affecting the gap junction (GJ) protein connexin32 (Cx32). A subset of CMT1X patients may additionally present with acute fulminant CNS dysfunction, typically triggered by conditions of systemic inflammation and metabolic stress. To clarify the underlying mechanisms of CNS phenotypes in CMT1X we studied a mouse model of systemic inflammation induced by lipopolysaccharide (LPS) injection to compare wild type (WT), connexin32 (Cx32) knockout (KO), and KO T55I mice expressing the T55I Cx32 mutation associated with CNS phenotypes. Following a single intraperitoneal LPS or saline (controls) injection at the age of 40-60 days systemic inflammatory response was documented by elevated TNF-α and IL-6 levels in peripheral blood and mice were evaluated 1 week after injection. Behavioral analysis showed graded impairment of motor performance in LPS treated mice, worse in KO T55I than in Cx32 KO and in Cx32 KO worse than WT. Iba1 immunostaining revealed widespread inflammation in LPS treated mice with diffusely activated microglia throughout the CNS. Immunostaining for the remaining major oligodendrocyte connexin Cx47 and for its astrocytic partner Cx43 revealed widely reduced expression of Cx43 and loss of Cx47 GJs in oligodendrocytes. Real-time PCR and immunoblot analysis indicated primarily a down regulation of Cx43 expression with secondary loss of Cx47 membrane localization. Inflammatory changes and connexin alterations were most severe in the KO T55I group. To examine why the presence of the T55I mutant exacerbates pathology even more than in Cx32 KO mice, we analyzed the expression of ER-stress markers BiP, Fas and CHOP by immunostaining, immunoblot and Real-time PCR. All markers were increased in LPS treated KO T55I mice more than in other genotypes. In conclusion, LPS induced neuroinflammation causes disruption of the main astrocyte-oligodendrocyte GJs, which may contribute to the increased sensitivity of Cx32 KO mice to LPS and of patients with CMT1X to various stressors. Moreover the presence of an intracellularly retained, misfolded CMT1X mutant such as T55I induces ER stress under inflammatory conditions, further exacerbating oligodendrocyte dysfunction and pathological changes in the CNS.
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Affiliation(s)
- Margarita Olympiou
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Irene Sargiannidou
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Kyriaki Markoullis
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Christos Karaiskos
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Alexia Kagiava
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Styliana Kyriakoudi
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago, Chicago, USA
| | - Kleopas A Kleopa
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
- Neurology Clinics, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, 6 International Airport Avenue, P.O. Box 23462, , 1683, Nicosia, Cyprus.
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8
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Connexins, gap junctions and peripheral neuropathy. Neurosci Lett 2015; 596:27-32. [DOI: 10.1016/j.neulet.2014.10.033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/15/2014] [Accepted: 10/17/2014] [Indexed: 11/23/2022]
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9
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Localization of aquaporin 1 water channel in the Schmidt–Lanterman incisures and the paranodal regions of the rat sciatic nerve. Neuroscience 2015; 285:119-27. [DOI: 10.1016/j.neuroscience.2014.10.060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 10/25/2014] [Accepted: 10/28/2014] [Indexed: 01/02/2023]
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10
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Oligodendrocyte gap junction loss and disconnection from reactive astrocytes in multiple sclerosis gray matter. J Neuropathol Exp Neurol 2014; 73:865-79. [PMID: 25101702 DOI: 10.1097/nen.0000000000000106] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Gap junctions are essential for glial cell function and have been increasingly implicated in multiple sclerosis (MS). Because increasing cortical abnormalities correlate with disease progression and cognitive dysfunction, we examined the expression of oligodendrocytic connexin32 (Cx32) and Cx47 and their astrocytic partners Cx30 and Cx43 in cortical lesions and normal-appearing gray matter (NAGM) in MS patients. Postmortem brain tissue samples from 9 MS cases were compared with 10 controls using real-time polymerase chain reaction, immunoblot, and immunohistochemical analyses. Connexin32 and Cx47 gap junction formation in oligodendrocytes was reduced within lesions, whereas Cx32 loss also extended to NAGM. In contrast, astrocytic Cx30 expression was increased within cortical lesions, whereas Cx43 was elevated in both lesions and NAGM. Diffuse microglial activation and marked astrogliotic changes accompanied these connexin abnormalities. Increased expression of Cx43 correlated with inflammatory load (r = 0.828, p = 0.042), whereas Cx32 expression correlated with longer disease duration and, therefore, milder course (r = 0.825, p = 0.043). Thus, there is a loss of intramyelin and intercellular oligodendrocyte gap junctions in MS gray matter lesions and NAGM, whereas interastrocytic gap junctions are increased, reflecting astrogliosis. These changes correlate with inflammation and disease duration and suggest that disconnection of oligodendrocytes from reactive astrocytes may play a role in failed remyelination and disease progression.
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11
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Kang M, Lin N, Li C, Meng Q, Zheng Y, Yan X, Deng J, Ou Y, Zhang C, He J, Luo D. Cx43 phosphorylation on S279/282 and intercellular communication are regulated by IP3/IP3 receptor signaling. Cell Commun Signal 2014; 12:58. [PMID: 25262337 PMCID: PMC4195880 DOI: 10.1186/s12964-014-0058-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 09/11/2014] [Indexed: 11/17/2022] Open
Abstract
Background Inositol 1,4,5-trisphosphate receptor (IP3R) plays a pivotal role in the Ca2+ release process in a variety of cell types. Additionally, IP3R is distributed in ventricular intercalated discs, but its function(s) in this particular site remains unknown. Connexin (Cx43), the predominant gap junction (GJ) protein in ventricular myocardium, is linked to several signaling pathways that regulate Cx43 properties by (de)phosphorylation on multiple residues. Here, we investigated the regulatory role of IP3R in cell-cell communication and the mechanism(s) underlying this effect. Results In neonatal rat and adult mouse ventricular myocytes IP3R co-localized and co-immunoprecipitated with Cx43 in GJ plaques detected by immunostaining and western blot assays. Blocking IP3R with antagonists or silencing pan-IP3R expression with shRNA hindered the 6-carboxyfluorescein (6-CFDA) diffusion through GJs and desynchronized Ca2+ transients among confluent neonatal myocytes in culture, whereas stimulation of IP3R with IP3 ester or ATP exerted the opposite effect. Likewise, 6-CFDA propagation through GJs was modulated by IP3R activation or inhibition in cell pairs of isolated adult cardiomyocytes. Furthermore, IP3R activation or IP3R suppression promoted or suppressed, respectively, Cx43 phosphorylation on S279/282. Site-directed mutagenesis indicated that expression of a mutant Cx43-S282A (alanine) inhibited S279/282 phosphorylation and GJ permeability, while the S279A mutant showed the opposite effect in ventricular myocytes. Expression of these mutants in HEK293 cells revealed that cells with a dual S279/282 mutation failed to express exogenous Cx43, whereas cells with a single S279 or S282 mutation displayed Cx43 overexpression with increased phosphorylation of S279/282 and promotion of intercellular communication. Conclusions These results demonstrated, for the first time, that IP3R physically interacts with Cx43 and participates in the regulation of Cx43 phosphorylation on S279/282, thereby affecting GJ intercellular communication in ventricular myocytes. Electronic supplementary material The online version of this article (doi:10.1186/s12964-014-0058-6) contains supplementary material, which is available to authorized users.
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Schabhüttl M, Wieland T, Senderek J, Baets J, Timmerman V, De Jonghe P, Reilly MM, Stieglbauer K, Laich E, Windhager R, Erwa W, Trajanoski S, Strom TM, Auer-Grumbach M. Whole-exome sequencing in patients with inherited neuropathies: outcome and challenges. J Neurol 2014; 261:970-82. [PMID: 24627108 DOI: 10.1007/s00415-014-7289-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/12/2014] [Accepted: 02/14/2014] [Indexed: 01/20/2023]
Abstract
Inherited peripheral neuropathies (IPN) are one of the most frequent inherited causes of neurological disability characterized by considerable phenotypic and genetic heterogeneity. Based on clinical and electrophysiological properties, they can be subdivided into three main groups: HMSN, dHMN, and HSN. At present, more than 50 IPN genes have been identified. Still, many patients and families with IPN have not yet received a molecular genetic diagnosis because clinical genetic testing usually only covers a subset of IPN genes. Moreover, a considerable proportion of IPN genes has to be identified. Here we present results of WES in 27 IPN patients excluded for mutations in many known IPN genes. Eight of the patients received a definite diagnosis. While six of these patients carried bona fide pathogenic mutations in known IPN genes, two patients had mutations in genes known to be involved in other types of neuromuscular disorders. A further group of eight patients carried sequence variations in IPN genes that could not unequivocally be classified as pathogenic. In addition, combining data of WES and linkage analysis identified SH3BP4, ITPR3, and KLHL13 as novel IPN candidate genes. Moreover, there was evidence that particular mutations in PEX12, a gene known to cause Zellweger syndrome, could also lead to an IPN phenotype. We show that WES is a useful tool for diagnosing IPN and we suggest an expanded phenotypic spectrum of some genes involved in other neuromuscular and neurodegenerative disorders. Nevertheless, interpretation of variants in known and potential novel disease genes has remained challenging.
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Affiliation(s)
- Maria Schabhüttl
- Department of Orthopaedics, Medical University Vienna, Währingergürtel 18-20, 1090, Vienna, Austria
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Samara C, Poirot O, Domènech-Estévez E, Chrast R. Neuronal activity in the hub of extrasynaptic Schwann cell-axon interactions. Front Cell Neurosci 2013; 7:228. [PMID: 24324401 PMCID: PMC3839048 DOI: 10.3389/fncel.2013.00228] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 11/05/2013] [Indexed: 12/21/2022] Open
Abstract
The integrity and function of neurons depend on their continuous interactions with glial cells. In the peripheral nervous system glial functions are exerted by Schwann cells (SCs). SCs sense synaptic and extrasynaptic manifestations of action potential propagation and adapt their physiology to support neuronal activity. We review here existing literature data on extrasynaptic bidirectional axon-SC communication, focusing particularly on neuronal activity implications. To shed light on underlying mechanisms, we conduct a thorough analysis of microarray data from SC-rich mouse sciatic nerve at different developmental stages and in neuropathic models. We identify molecules that are potentially involved in SC detection of neuronal activity signals inducing subsequent glial responses. We further suggest that alterations in the activity-dependent axon-SC crosstalk impact on peripheral neuropathies. Together with previously reported data, these observations open new perspectives for deciphering glial mechanisms of neuronal function support.
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Affiliation(s)
- Chrysanthi Samara
- Department of Medical Genetics, University of Lausanne Lausanne, Switzerland
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Kleopa KA, Sargiannidou I, Markoullis K. Connexin pathology in chronic multiple sclerosis and experimental autoimmune encephalomyelitis. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cen3.12055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Kleopas A. Kleopa
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - Irene Sargiannidou
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - Kyriaki Markoullis
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
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15
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Markoullis K, Sargiannidou I, Gardner C, Hadjisavvas A, Reynolds R, Kleopa KA. Disruption of oligodendrocyte gap junctions in experimental autoimmune encephalomyelitis. Glia 2012; 60:1053-66. [PMID: 22461072 DOI: 10.1002/glia.22334] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/05/2012] [Indexed: 12/16/2023]
Abstract
Gap junctions (GJs) are vital for oligodendrocyte survival and myelination. In order to examine how different stages of inflammatory demyelination affect oligodendrocyte GJs, we studied the expression of oligodendrocytic connexin32 (Cx32) and Cx47 and astrocytic Cx43 in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS) induced by recombinant myelin oligodendrocyte glycoprotein. EAE was characterized by remissions and relapses with demyelination and axonal loss. Formation of GJ plaques was quantified in relation to the lesions and in normal appearing white matter (NAWM). During acute EAE at 14 days postimmunization (dpi) both Cx47 and Cx32 GJs were severely reduced within and around lesions but also in the NAWM. Cx47 was localized intracellularly in oligodendrocytes while protein levels remained unchanged, and this redistribution coincided with the loss of Cx43 GJs in astrocytes. Cx47 and Cx32 expression increased during remyelination at 28 dpi but decreased again at 50 dpi in the relapsing phase. Oligodendrocyte GJs remained reduced even in NAWM, despite increased formation of Cx43 GJs toward lesions indicating astrogliosis. EAE induced in Cx32 knockout mice resulted in an exacerbated clinical course with more demyelination and axonal loss compared with wild-type EAE mice of the same backcross, despite similar degree of inflammation, and an overall milder loss of Cx47 and Cx43 GJs. Thus, EAE causes persistent impairment of both intra- and intercellular oligodendrocyte GJs even in the NAWM, which may be an important mechanism of MS progression. Furthermore, GJ deficient myelinated fibers appear more vulnerable to CNS inflammatory demyelination.
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Affiliation(s)
- Kyriaki Markoullis
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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Markoullis K, Sargiannidou I, Schiza N, Hadjisavvas A, Roncaroli F, Reynolds R, Kleopa KA. Gap junction pathology in multiple sclerosis lesions and normal-appearing white matter. Acta Neuropathol 2012; 123:873-86. [PMID: 22484441 DOI: 10.1007/s00401-012-0978-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 03/14/2012] [Accepted: 03/28/2012] [Indexed: 11/26/2022]
Abstract
Oligodendrocyte gap junctions (GJs) are vital for central nervous system myelination, but their involvement in multiple sclerosis (MS) pathology remains unknown. The aim of this study was to examine alterations of oligodendrocyte and related astrocyte GJs in MS lesions and normal-appearing white matter (NAWM). Post-mortem brain samples from 9 MS and 11 age-matched non-MS control patients were studied. Tissue sections that included both chronic active and inactive lesions were characterized neuropathologically with Luxol Fast Blue staining and immunostaining for myelin oligodendrocyte glycoprotein (MOG) and the microglial marker Iba1. We analyzed the expression of Cx32 and Cx47 in oligodendrocytes and of Cx43, the major astrocytic partner in oligodendrocyte-astrocyte (O/A) GJs by quantitative immunoblot and real-time PCR. Formation of GJ plaques was quantified by immunohistochemistry. Compared to control brains, both Cx32 and Cx47 GJ plaques and protein levels were reduced in and around MS lesions, while Cx43 was increased as part of astrogliosis. In the NAWM, Cx32 was significantly reduced along myelinated fibers whereas Cx47 showed increased expression mainly in oligodendrocyte precursor cells (OPCs). However, OPCs showed only limited connectivity to astrocytes. Cx43 showed modestly increased levels in MS NAWM compared to controls, while GJ plaque counts were unchanged. Our findings indicate that oligodendrocyte GJs are affected not only in chronic MS lesions but also in NAWM, where disruption of Cx32 GJs in myelinated fibers may impair myelin structure and function. Moreover, limited O/A GJ connectivity of recruited OPCs in the setting of persistent inflammation and astrogliosis may prevent differentiation and remyelination.
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Affiliation(s)
- Kyriaki Markoullis
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, 1683 Nicosia, Cyprus
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Kleopa KA. The role of gap junctions in Charcot-Marie-Tooth disease. J Neurosci 2011; 31:17753-60. [PMID: 22159091 PMCID: PMC6634164 DOI: 10.1523/jneurosci.4824-11.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 10/21/2011] [Accepted: 10/24/2011] [Indexed: 01/06/2023] Open
Affiliation(s)
- Kleopas A Kleopa
- Neurology Clinics and Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics, 1683 Nicosia, Cyprus.
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Dhaunchak AS, Huang JK, De Faria O, Roth AD, Pedraza L, Antel JP, Bar-Or A, Colman DR. A proteome map of axoglial specializations isolated and purified from human central nervous system. Glia 2010; 58:1949-60. [DOI: 10.1002/glia.21064] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Vavlitou N, Sargiannidou I, Markoullis K, Kyriacou K, Scherer SS, Kleopa KA. Axonal pathology precedes demyelination in a mouse model of X-linked demyelinating/type I Charcot-Marie Tooth neuropathy. J Neuropathol Exp Neurol 2010; 69:945-58. [PMID: 20720503 PMCID: PMC3034224 DOI: 10.1097/nen.0b013e3181efa658] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The X-linked demyelinating/type I Charcot-Marie-Tooth neuropathy (CMT1X) is an inherited peripheral neuropathy caused by mutations in GJB1, the gene that encodes the gap junction protein connexin32. Connexin32 is expressed by myelinating Schwann cells and forms gap junctions in noncompact myelin areas, but axonal involvement is more prominent in X-linked compared with other forms of demyelinating Charcot-Marie-Tooth disease. To clarify the cellular and molecular mechanisms of axonal pathology in CMT1X, we studied Gjb1-null mice at early stages (i.e. 2-4 months old) of the neuropathy, when there is minimal or no demyelination. The diameters of large myelinated axons were progressively reduced in Gjb1-null mice compared with those in wild-type littermates. Furthermore, neurofilaments were relatively more dephosphorylated and more densely packed starting at 2 months of age. Increased expression of β-amyloid precursor protein, a marker of axonal damage, was also detected in Gjb1-null nerves. Finally, fast axonal transport, assayed by sciatic nerve ligation experiments, was slower in distal axons of Gjb1-null versus wild-type animals with reduced accumulation of synaptic vesicle-associated proteins. These findings demonstrate that axonal abnormalities including impaired cytoskeletal organization and defects in axonal transport precede demyelination in this mouse model of CMT1X.
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Affiliation(s)
- Natalie Vavlitou
- Neuroscience Laboratory and Neurology Clinics, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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