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Elbaz B, Darwish A, Vardy M, Isaac S, Tokars HM, Dzhashiashvili Y, Korshunov K, Prakriya M, Eden A, Popko B. The bone transcription factor Osterix controls extracellular matrix- and node of Ranvier-related gene expression in oligodendrocytes. Neuron 2024; 112:247-263.e6. [PMID: 37924811 PMCID: PMC10843489 DOI: 10.1016/j.neuron.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 08/24/2023] [Accepted: 10/04/2023] [Indexed: 11/06/2023]
Abstract
Oligodendrocytes are the primary producers of many extracellular matrix (ECM)-related proteins found in the CNS. Therefore, oligodendrocytes play a critical role in the determination of brain stiffness, node of Ranvier formation, perinodal ECM deposition, and perineuronal net formation, all of which depend on the ECM. Nevertheless, the transcription factors that control ECM-related gene expression in oligodendrocytes remain unknown. Here, we found that the transcription factor Osterix (also known as Sp7) binds in proximity to genes important for CNS ECM and node of Ranvier formation and mediates their expression. Oligodendrocyte-specific ablation of Sp7 changes ECM composition and brain stiffness and results in aberrant node of Ranvier formation. Sp7 is known to control osteoblast maturation and bone formation. Our comparative analyses suggest that Sp7 plays a conserved biological role in oligodendrocytes and in bone-forming cells, where it mediates brain and bone tissue stiffness by controlling expression of ECM components.
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Affiliation(s)
- Benayahu Elbaz
- Department of Neurology, Division of Multiple Sclerosis and Neuroimmunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
| | - Alaa Darwish
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maia Vardy
- Department of Neurology, Division of Multiple Sclerosis and Neuroimmunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Sara Isaac
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Haley Margaret Tokars
- Department of Neurology, Division of Multiple Sclerosis and Neuroimmunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Yulia Dzhashiashvili
- Department of Neurology, Division of Multiple Sclerosis and Neuroimmunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Kirill Korshunov
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Amir Eden
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Brian Popko
- Department of Neurology, Division of Multiple Sclerosis and Neuroimmunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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Xu H, Dzhashiashvili Y, Shah A, Kunjamma RB, Weng YL, Elbaz B, Fei Q, Jones JS, Li YI, Zhuang X, Ming GL, He C, Popko B. m 6A mRNA Methylation Is Essential for Oligodendrocyte Maturation and CNS Myelination. Neuron 2019; 105:293-309.e5. [PMID: 31901304 DOI: 10.1016/j.neuron.2019.12.013] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 10/15/2019] [Accepted: 12/09/2019] [Indexed: 12/21/2022]
Abstract
The molecular mechanisms that govern the maturation of oligodendrocyte lineage cells remain unclear. Emerging studies have shown that N6-methyladenosine (m6A), the most common internal RNA modification of mammalian mRNA, plays a critical role in various developmental processes. Here, we demonstrate that oligodendrocyte lineage progression is accompanied by dynamic changes in m6A modification on numerous transcripts. In vivo conditional inactivation of an essential m6A writer component, METTL14, results in decreased oligodendrocyte numbers and CNS hypomyelination, although oligodendrocyte precursor cell (OPC) numbers are normal. In vitro Mettl14 ablation disrupts postmitotic oligodendrocyte maturation and has distinct effects on OPC and oligodendrocyte transcriptomes. Moreover, the loss of Mettl14 in oligodendrocyte lineage cells causes aberrant splicing of myriad RNA transcripts, including those that encode the essential paranodal component neurofascin 155 (NF155). Together, our findings indicate that dynamic RNA methylation plays an important regulatory role in oligodendrocyte development and CNS myelination.
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Affiliation(s)
- Huan Xu
- Center for Peripheral Neuropathy and Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Yulia Dzhashiashvili
- Center for Peripheral Neuropathy and Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Ankeeta Shah
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL 60637, USA; Section of Genetic Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Rejani B Kunjamma
- Center for Peripheral Neuropathy and Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Yi-Lan Weng
- Department of Neuroscience and Mahoney Institute for Neurosciences, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Benayahu Elbaz
- Center for Peripheral Neuropathy and Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Qili Fei
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Joshua S Jones
- Center for Peripheral Neuropathy and Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Yang I Li
- Section of Genetic Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Xiaoxi Zhuang
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - Guo-Li Ming
- Department of Neuroscience and Mahoney Institute for Neurosciences, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chuan He
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Brian Popko
- Center for Peripheral Neuropathy and Department of Neurology, University of Chicago, Chicago, IL 60637, USA.
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Dzhashiashvili Y, Monckton CP, Shah HS, Kunjamma RB, Popko B. The UPR-PERK pathway is not a promising therapeutic target for mutant SOD1-induced ALS. Neurobiol Dis 2019; 127:527-544. [PMID: 30923003 DOI: 10.1016/j.nbd.2019.03.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/26/2019] [Accepted: 03/24/2019] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease, characterized by motor neuron death in the brain and spinal cord. Mutations in the Cu/Zn superoxide dismutase (SOD1) gene account for ~20% of all familial ALS forms, corresponding to 1%-2% of all ALS cases. One of the suggested mechanisms by which mutant SOD1 (mtSOD1) exerts its toxic effects involves intracellular accumulation of abnormal mtSOD1 aggregates, which trigger endoplasmic reticulum (ER) stress and activate its adaptive signal transduction pathways, including the unfolded protein response (UPR). PERK, an eIF2α kinase, is central to the UPR and is the most rapidly activated pathway in response to ER stress. Previous reports using mtSOD1 transgenic mice indicated that genetic or pharmacological enhancement of the UPR-PERK pathway may be effective in treating ALS. We investigated the response to PERK haploinsufficiency, and the response to deficiency of its downstream effectors GADD34 and CHOP, in five distinct lines of mtSOD1 mice. We demonstrate that, in contrast to a previously published study, PERK haploinsufficiency has no effect on disease in all mtSOD1 lines examined. We also show that deficiency of GADD34, which enhances the UPR by prolonging the phosphorylation of eIF2α, does not ameliorate disease in these mtSOD1 mouse lines. Finally, we demonstrate that genetic ablation of CHOP transcription factor, which is known to be pro-apoptotic, does not ameliorate disease in mtSOD1 mice. Cumulatively, our studies reveal that neither genetic inhibition of the UPR via ablation of PERK, nor genetic UPR enhancement via ablation of GADD34, is beneficial for mtSOD1-induced motor neuron disease. Therefore, the PERK pathway is not a likely target for therapeutic intervention in mtSOD1-induced ALS.
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Affiliation(s)
- Yulia Dzhashiashvili
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, IL 60637, United States.
| | - Chase P Monckton
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, IL 60637, United States.
| | - Harini S Shah
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, IL 60637, United States.
| | - Rejani B Kunjamma
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, IL 60637, United States.
| | - Brian Popko
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, IL 60637, United States.
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Berthoud VM, Minogue PJ, Snabb JI, Dzhashiashvili Y, Novak LA, Zoltoski RK, Popko B, Beyer EC. Connexin23 deletion does not affect lens transparency. Exp Eye Res 2016; 146:283-288. [PMID: 27038752 DOI: 10.1016/j.exer.2016.03.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 03/24/2016] [Accepted: 03/28/2016] [Indexed: 11/25/2022]
Abstract
While connexin46 (Cx46) and connexin50 (Cx50) are crucial for maintaining lens transparency and growth, the contributions of a more recently identified lens fiber connexin, Cx23, are poorly understood. Therefore, we studied the consequences of absence of Cx23 in mouse lenses. Cx23-null mice were generated by homologous Cre recombination. Cx23 mRNA was abundantly expressed in wild type lenses, but not in Cx23-null lenses. The transparency and refractive properties of Cx23-null lenses were similar to wild type lenses when examined by darkfield microscopy. Neither the focusing ability nor the light scattering was altered in the Cx23-null lenses. While both Cx46 and Cx50 localized to appositional fiber cell membranes (as in wild type lenses), their levels were consistently (but not significantly) decreased in homozygous Cx23-null lenses. These results suggest that although Cx23 expression can influence the abundance of the co-expressed lens fiber connexins, heterozygous or homozygous expression of a Cx23-null allele does not alter lens transparency.
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Affiliation(s)
| | - Peter J Minogue
- Department of Pediatrics, University of Chicago, Chicago, IL, USA
| | - Joseph I Snabb
- Department of Pediatrics, University of Chicago, Chicago, IL, USA
| | | | | | | | - Brian Popko
- Department of Neurology, University of Chicago, Chicago, IL, USA
| | - Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL, USA
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Zhang Y, Bekku Y, Dzhashiashvili Y, Armenti S, Meng X, Sasaki Y, Milbrandt J, Salzer JL. Assembly and maintenance of nodes of ranvier rely on distinct sources of proteins and targeting mechanisms. Neuron 2012; 73:92-107. [PMID: 22243749 DOI: 10.1016/j.neuron.2011.10.016] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2011] [Indexed: 01/29/2023]
Abstract
VIDEO ABSTRACT We have investigated the source(s) and targeting of components to PNS nodes of Ranvier. We show adhesion molecules are freely diffusible within the axon membrane and accumulate at forming nodes from local sources, whereas ion channels and cytoskeletal components are largely immobile and require transport to the node. We further characterize targeting of NF186, an adhesion molecule that pioneers node formation. NF186 redistributes to nascent nodes from a mobile, surface pool. Its initial accumulation and clearance from the internode require extracellular interactions, whereas targeting to mature nodes, i.e., those flanked by paranodal junctions, requires intracellular interactions. After incorporation into the node, NF186 is immobile, stable, and promotes node integrity. Thus, nodes assemble from two sources: adhesion molecules, which initiate assembly, accumulate by diffusion trapping via interactions with Schwann cells, whereas ion channels and cytoskeletal components accumulate via subsequent transport. In mature nodes, components turnover slowly and are replenished via transport.
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Affiliation(s)
- Yanqing Zhang
- Smilow Neuroscience Program, New York University Langone Medical Center, New York, NY 10016, USA
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Dzhashiashvili Y, Zhang Y, Galinska J, Lam I, Grumet M, Salzer JL. Nodes of Ranvier and axon initial segments are ankyrin G-dependent domains that assemble by distinct mechanisms. ACTA ACUST UNITED AC 2007; 177:857-70. [PMID: 17548513 PMCID: PMC2064285 DOI: 10.1083/jcb.200612012] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Axon initial segments (AISs) and nodes of Ranvier are sites of action potential generation and propagation, respectively. Both domains are enriched in sodium channels complexed with adhesion molecules (neurofascin [NF] 186 and NrCAM) and cytoskeletal proteins (ankyrin G and βIV spectrin). We show that the AIS and peripheral nervous system (PNS) nodes both require ankyrin G but assemble by distinct mechanisms. The AIS is intrinsically specified; it forms independent of NF186, which is targeted to this site via intracellular interactions that require ankyrin G. In contrast, NF186 is targeted to the node, and independently cleared from the internode, by interactions of its ectodomain with myelinating Schwann cells. NF186 is critical for and initiates PNS node assembly by recruiting ankyrin G, which is required for the localization of sodium channels and the entire nodal complex. Thus, initial segments assemble from the inside out driven by the intrinsic accumulation of ankyrin G, whereas PNS nodes assemble from the outside in, specified by Schwann cells, which direct the NF186-dependent recruitment of ankyrin G.
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Affiliation(s)
- Yulia Dzhashiashvili
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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