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Bouchard EL, Meireles AM, Talbot WS. Oligodendrocyte development and myelin sheath formation are regulated by the antagonistic interaction between the Rag-Ragulator complex and TFEB. Glia 2024; 72:289-299. [PMID: 37767930 PMCID: PMC10841052 DOI: 10.1002/glia.24473] [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: 03/02/2023] [Revised: 08/11/2023] [Accepted: 09/16/2023] [Indexed: 09/29/2023]
Abstract
Myelination by oligodendrocytes is critical for fast axonal conduction and for the support and survival of neurons in the central nervous system. Recent studies have emphasized that myelination is plastic and that new myelin is formed throughout life. Nonetheless, the mechanisms that regulate the number, length, and location of myelin sheaths formed by individual oligodendrocytes are incompletely understood. Previous work showed that the lysosomal transcription factor TFEB represses myelination by oligodendrocytes and that the RagA GTPase inhibits TFEB, but the step or steps of myelination in which TFEB plays a role have remained unclear. Here, we show that TFEB regulates oligodendrocyte differentiation and also controls the length of myelin sheaths formed by individual oligodendrocytes. In the dorsal spinal cord of tfeb mutants, individual oligodendrocytes produce myelin sheaths that are longer than those produced by wildtype cells. Transmission electron microscopy shows that there are more myelinated axons in the dorsal spinal cord of tfeb mutants than in wildtype animals, but no significant change in axon diameter. In contrast to tfeb mutants, oligodendrocytes in rraga mutants produce shorter myelin sheaths. The sheath length in rraga; tfeb double mutants is not significantly different from wildtype, consistent with the antagonistic interaction between RagA and TFEB. Finally, we find that the GTPase activating protein Flcn and the RagCa and RagCb GTPases are also necessary for myelination by oligodendrocytes. These findings demonstrate that TFEB coordinates myelin sheath length and number during myelin formation in the central nervous system.
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Affiliation(s)
- Ellen L. Bouchard
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ana M. Meireles
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - William S. Talbot
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Wadford DA, Baumrind N, Baylis EF, Bell JM, Bouchard EL, Crumpler M, Foote EM, Gilliam S, Glaser CA, Hacker JK, Ledin K, Messenger SL, Morales C, Smith EA, Sevinsky JR, Corbett-Detig RB, DeRisi J, Jacobson K. Implementation of California COVIDNet - a multi-sector collaboration for statewide SARS-CoV-2 genomic surveillance. Front Public Health 2023; 11:1249614. [PMID: 37937074 PMCID: PMC10627185 DOI: 10.3389/fpubh.2023.1249614] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 09/27/2023] [Indexed: 11/09/2023] Open
Abstract
Introduction The SARS-CoV-2 pandemic represented a formidable scientific and technological challenge to public health due to its rapid spread and evolution. To meet these challenges and to characterize the virus over time, the State of California established the California SARS-CoV-2 Whole Genome Sequencing (WGS) Initiative, or "California COVIDNet". This initiative constituted an unprecedented multi-sector collaborative effort to achieve large-scale genomic surveillance of SARS-CoV-2 across California to monitor the spread of variants within the state, to detect new and emerging variants, and to characterize outbreaks in congregate, workplace, and other settings. Methods California COVIDNet consists of 50 laboratory partners that include public health laboratories, private clinical diagnostic laboratories, and academic sequencing facilities as well as expert advisors, scientists, consultants, and contractors. Data management, sample sourcing and processing, and computational infrastructure were major challenges that had to be resolved in the midst of the pandemic chaos in order to conduct SARS-CoV-2 genomic surveillance. Data management, storage, and analytics needs were addressed with both conventional database applications and newer cloud-based data solutions, which also fulfilled computational requirements. Results Representative and randomly selected samples were sourced from state-sponsored community testing sites. Since March of 2021, California COVIDNet partners have contributed more than 450,000 SARS-CoV-2 genomes sequenced from remnant samples from both molecular and antigen tests. Combined with genomes from CDC-contracted WGS labs, there are currently nearly 800,000 genomes from all 61 local health jurisdictions (LHJs) in California in the COVIDNet sequence database. More than 5% of all reported positive tests in the state have been sequenced, with similar rates of sequencing across 5 major geographic regions in the state. Discussion Implementation of California COVIDNet revealed challenges and limitations in the public health system. These were overcome by engaging in novel partnerships that established a successful genomic surveillance program which provided valuable data to inform the COVID-19 public health response in California. Significantly, California COVIDNet has provided a foundational data framework and computational infrastructure needed to respond to future public health crises.
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Affiliation(s)
- Debra A. Wadford
- California Department of Public Health, Richmond, CA, United States
| | - Nikki Baumrind
- California Department of Public Health, Richmond, CA, United States
| | | | - John M. Bell
- California Department of Public Health, Richmond, CA, United States
| | | | - Megan Crumpler
- Orange County Public Health Laboratory, Santa Ana, CA, United States
| | - Eric M. Foote
- California Department of Public Health, Richmond, CA, United States
| | - Sabrina Gilliam
- California Department of Public Health, Richmond, CA, United States
| | - Carol A. Glaser
- California Department of Public Health, Richmond, CA, United States
| | - Jill K. Hacker
- California Department of Public Health, Richmond, CA, United States
| | - Katya Ledin
- California Department of Public Health, Richmond, CA, United States
| | | | | | | | | | | | - Joseph DeRisi
- University of California, San Francisco, San Francisco, CA, United States
- Chan Zuckerberg Biohub, San Francisco, CA, United States
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Meireles AM, Shen K, Zoupi L, Iyer H, Bouchard EL, Williams A, Talbot WS. The Lysosomal Transcription Factor TFEB Represses Myelination Downstream of the Rag-Ragulator Complex. Dev Cell 2019; 47:319-330.e5. [PMID: 30399334 DOI: 10.1016/j.devcel.2018.10.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [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: 03/28/2018] [Revised: 08/28/2018] [Accepted: 10/03/2018] [Indexed: 12/30/2022]
Abstract
Myelin allows for fast and efficient axonal conduction, but much remains to be determined about the mechanisms that regulate myelin formation. To investigate the genetic basis of myelination, we carried out a genetic screen using zebrafish. Here, we show that the lysosomal G protein RagA is essential for CNS myelination. In rraga-/- mutant oligodendrocytes, target genes of the lysosomal transcription factor Tfeb are upregulated, consistent with previous evidence that RagA represses Tfeb activity. Loss of Tfeb function is sufficient to restore myelination in RagA mutants, indicating that hyperactive Tfeb represses myelination. Conversely, tfeb-/- single mutants exhibit ectopic myelin, further indicating that Tfeb represses myelination during development. In a mouse model of de- and remyelination, TFEB expression is increased in oligodendrocytes, but the protein is localized to the cytoplasm, and hence inactive, especially during remyelination. These results define essential regulators of myelination and may advance approaches to therapeutic remyelination.
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Affiliation(s)
- Ana M Meireles
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kimberle Shen
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lida Zoupi
- University of Edinburgh/MS Society Centre for MS Research, MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh Bioquarter, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Harini Iyer
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ellen L Bouchard
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Anna Williams
- University of Edinburgh/MS Society Centre for MS Research, MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh Bioquarter, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - William S Talbot
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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