The Lysosomal Transcription Factor TFEB regulates myelination downstream of the Rag-Ragulator complex.
Ontology highlight
ABSTRACT:
ORGANISM(S): Danio rerio
PROVIDER: GSE119332 | GEO | 2018/10/31
REPOSITORIES: GEO
Similar Datasets
Project description: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.
| S-EPMC6250074 | biostudies-literature
Project description:The transcription factor TFEB is a master regulator of lysosomal biogenesis and autophagy1. The phosphorylation of TFEB by the mechanistic target of rapamycin complex 1 (mTORC1)2-5 is unique in its mTORC1 substrate recruitment mechanism, which is strictly dependent on the amino acid-mediated activation of the RagC GTPase activating protein FLCN6,7. TFEB lacks the TOR signalling motif responsible for the recruitment of other mTORC1 substrates. We used cryogenic-electron microscopy to determine the structure of TFEB as presented to mTORC1 for phosphorylation, which we refer to as the 'megacomplex'. Two full Rag-Ragulator complexes present each molecule of TFEB to the mTOR active site. One Rag-Ragulator complex is bound to Raptor in the canonical mode seen previously in the absence of TFEB. A second Rag-Ragulator complex (non-canonical) docks onto the first through a RagC GDP-dependent contact with the second Ragulator complex. The non-canonical Rag dimer binds the first helix of TFEB with a RagCGDP-dependent aspartate clamp in the cleft between the Rag G domains. In cellulo mutation of the clamp drives TFEB constitutively into the nucleus while having no effect on mTORC1 localization. The remainder of the 108-amino acid TFEB docking domain winds around Raptor and then back to RagA. The double use of RagC GDP contacts in both Rag dimers explains the strong dependence of TFEB phosphorylation on FLCN and the RagC GDP state.
| S-EPMC9931586 | biostudies-literature
Project description:The Lysosomal Transcription Factor TFEB regulates myelination downstream of the Rag-Ragulator complex.
| PRJNA489469 | ENA
Project description:Host cells initiate cell death programs to limit pathogen infection. Inhibition of transforming growth factor-β-activated kinase 1 (TAK1) by pathogenic Yersinia in macrophages triggers receptor-interacting serine/threonine-protein kinase 1 (RIPK1)-dependent caspase-8 cleavage of gasdermin D (GSDMD) and inflammatory cell death (pyroptosis). A genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screen to uncover mediators of caspase-8-dependent pyroptosis identified an unexpected role of the lysosomal FLCN-FNIP2-Rag-Ragulator supercomplex, which regulates metabolic signalling and the mechanistic target of rapamycin complex 1 (mTORC1). In response to Yersinia infection, FADD, RIPK1 and caspase-8 were recruited to Rag-Ragulator, causing RIPK1 phosphorylation and caspase-8 activation. Pyroptosis activation depended on Rag GTPase activity and lysosomal tethering of Rag-Ragulator, but not mTORC1. Thus, the lysosomal metabolic regulator Rag-Ragulator instructs the inflammatory response to Yersinia.
| S-EPMC8769499 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2025-12-31 | GSE240635 | GEO
Project description: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.
| S-EPMC10841052 | biostudies-literature
Project description:The type I interferon (IFN) response is a pivotal transcription program in the host innate immunity against infectious viruses that induces a multitude of interferon-stimulated genes (ISGs) to antagonize every stage of viral replication. Aberrant IFN response often leads to enhanced viral susceptibility or autoimmune conditions. Accordingly, type I IFN induction is tightly regulated from viral recognition to signaling propagation and transcriptional activation to cytokine production. Lysosomes, which are essential organelles for cellular homeostasis and metabolic signaling, play an evolutionarily conserved role in viral clearance. Through their degradative capacity and recycling function, lysosomes facilitate the containment and destruction of viral particles or debris delivered via endocytic, autophagic, and phagocytic routes. Despite the central role of lysosomes in virus-host interactions, it remains unclear whether type I IFN induction requires direct lysosomal input. Here, we identified the lysosomal scaffold Ragulator as crucial for IFN-β transcriptional activation through an antiviral screen using a GFP-expressing Influenza A virus as a readout. Independent of their known roles in mTORC1 regulation, the Ragulator-dependent antiviral response requires downstream heterodimeric Rag GTPases that alter their nucleotide-loading states to establish the IFN-I gene signature. Depleting Ragulator or Rag GTPases causes exhaustion of a regulatory pool of interferon-regulator factors (IRFs), leading to abrogated Ifnb1 transcription, IFN-β secretion, and ISG response, thereby enhancing susceptibility to viral infections both in cells and in vivo. Thus, our findings reveal a new role for lysosomes in the nuclear transcription of antiviral innate immunity.
2025-12-31 | GSE240632 | GEO
Project description:The type I interferon (IFN) response is a pivotal transcription program in the host innate immunity against infectious viruses that induces a multitude of interferon-stimulated genes (ISGs) to antagonize every stage of viral replication. Aberrant IFN response often leads to enhanced viral susceptibility or autoimmune conditions. Accordingly, type I IFN induction is tightly regulated from viral recognition to signaling propagation and transcriptional activation to cytokine production. Lysosomes, which are essential organelles for cellular homeostasis and metabolic signaling, play an evolutionarily conserved role in viral clearance. Through their degradative capacity and recycling function, lysosomes facilitate the containment and destruction of viral particles or debris delivered via endocytic, autophagic, and phagocytic routes. Despite the central role of lysosomes in virus-host interactions, it remains unclear whether type I IFN induction requires direct lysosomal input. Here, we identified the lysosomal scaffold Ragulator as crucial for IFN-β transcriptional activation through an antiviral screen using a GFP-expressing Influenza A virus as a readout. Independent of their known roles in mTORC1 regulation, the Ragulator-dependent antiviral response requires downstream heterodimeric Rag GTPases that alter their nucleotide-loading states to establish the IFN-I gene signature. Depleting Ragulator or Rag GTPases causes exhaustion of a regulatory pool of interferon-regulator factors (IRFs), leading to abrogated Ifnb1 transcription, IFN-β secretion, and ISG response, thereby enhancing susceptibility to viral infections both in cells and in vivo. Thus, our findings reveal a new role for lysosomes in the nuclear transcription of antiviral innate immunity.
2025-12-31 | GSE240633 | GEO
Project description:The mTORC1 kinase promotes growth in response to growth factors, energy levels, and amino acids, and its activity is often deregulated in disease. The Rag GTPases interact with mTORC1 and are proposed to activate it in response to amino acids by promoting mTORC1 translocation to a membrane-bound compartment that contains the mTORC1 activator, Rheb. We show that amino acids induce the movement of mTORC1 to lysosomal membranes, where the Rag proteins reside. A complex encoded by the MAPKSP1, ROBLD3, and c11orf59 genes, which we term Ragulator, interacts with the Rag GTPases, recruits them to lysosomes, and is essential for mTORC1 activation. Constitutive targeting of mTORC1 to the lysosomal surface is sufficient to render the mTORC1 pathway amino acid insensitive and independent of Rag and Ragulator, but not Rheb, function. Thus, Rag-Ragulator-mediated translocation of mTORC1 to lysosomal membranes is the key event in amino acid signaling to mTORC1.
| S-EPMC3024592 | biostudies-literature
Project description:mTORC1 controls key processes that regulate cell growth, including mRNA translation, ribosome biogenesis, and autophagy. Environmental amino acids activate mTORC1 by promoting its recruitment to the cytosolic surface of the lysosome, where its kinase is activated downstream of growth factor signaling. mTORC1 is brought to the lysosome by the Rag GTPases, which are tethered to the lysosomal membrane by Ragulator, a lysosome-bound scaffold. Here, we identify c17orf59 as a Ragulator-interacting protein that regulates mTORC1 activity through its interaction with Ragulator at the lysosome. The binding of c17orf59 to Ragulator prevents Ragulator interaction with the Rag GTPases, both in cells and in vitro, and decreases Rag GTPase lysosomal localization. Disruption of the Rag-Ragulator interaction by c17orf59 impairs mTORC1 activation by amino acids by preventing mTOR from reaching the lysosome. By disrupting the Rag-Ragulator interaction to inhibit mTORC1, c17orf59 expression may represent another mechanism to modulate nutrient sensing by mTORC1.
| S-EPMC4570232 | biostudies-literature