Intracellular Galectin-3 Is a Sensor of Lipopolysaccharide that Promotes Glycolysis through Activating mTORC1
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PROVIDER: PRJNA872113 | ENA |
REPOSITORIES: ENA
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Project description:Galectin-3 is a carbohydrate binding protein implicated in cell-cell interaction and cell growth. Interestingly, recent studies suggest that galectin-3 is involved in cell metabolism and linked to diabetes and cancer. How galectin-3 might act as a diabetogenic and tumorogenic factor remains to be investigated. Here we report that intracellular galectin-3 is physically associated with Rag GTPases and Ragulator of the mTORC1 signaling machinery on lysosomes. We show that galectin-3 senses lipopolysaccharide (LPS) to facilitate the interaction of Rag GTPases and Ragulator, leading to activation of Rag GTPases thus lysosomal loading of mTOR and activation of mTORC1. Integrative genomics and transcriptomics analyses reveal that the LPS/galectin-3-Rag GTPases/Ragulator-mTORC1 axis regulates a cohort of genes including GLUT1 (glucose transporter member 1) that functions in glucose uptake and glycolysis and HK2 (hexokinase 2) and PKM2 (pyruvate kinase M2) that catalyze the first and last step of glycolysis, respectively. Indeed, galectin-3 deficiency severely compromises LPS-promoted glycolysis. Importantly, in diabetes patients, the expression of HK2 was significantly reduced, and in hepatocellular carcinoma (HCC), thyroid cancer, and prostate cancer, galectin-3 is highly expressed, and its level of expression is positively correlated with that of HK2 and PKM2 and negatively correlated with the prognosis of HCC patients. Our study unravels that galectin-3 is a sensor of LPS, an important modulator of the mTORC1 signaling, and a critical regulator of glucose metabolism, adding to the understanding of diabetogenesis and tumorigenesis.
2022-10-25 | GSE211784 | GEO
Project description:Mammalian or the mechanistic target of rapamycin complex 1 (mTORC1) is an effective therapeutic target for diseases such as cancer, diabetes, aging, and neurodegeneration. However, an efficient tool to monitor mTORC1 inhibition in living cells or tissues is lacking. We developed a genetically encoded mTORC1 sensor called TORSEL. This sensor changes its fluorescence pattern from diffuse to punctate when 4EBP1 dephosphorylation occurs and interacts with eIF4E. TORSEL can specifically sense physiological, pharmacological, and genetic inhibition of mTORC1 signaling in living cells and tissues. Importantly, TORSEL is a valuable tool for imaging-based visual screening of mTORC1 inhibitors. Using TORSEL, we identified histone deacetylase inhibitors that selectively block nutrient-sensing signaling to inhibit mTORC1. Therefore, TORSEL is a unique living cell sensor that efficiently detects the inhibition of mTORC1 activity, and histone deacetylase inhibitors such as panobinostat target mTORC1 signaling through amino acid sensing.
2024-06-26 | GSE250539 | GEO
Project description:Naïve T cells respond to antigen stimulation by exiting from quiescence into clonal expansion and functional differentiation, but the control mechanism is elusive. Here we describe that Raptor/mTORC1-dependent metabolic reprogramming is a central determinant of this transitional process. Loss of Raptor abrogates T cell priming and Th2 cell differentiation, although Raptor function is less important for continuous proliferation of actively cycling cells. mTORC1 coordinates multiple metabolic programs in T cells including glycolysis, lipid synthesis and oxidative phosphorylation to mediate antigen-triggered exit from quiescence. mTORC1 further links glucose metabolism to the initiation of Th2 differentiation by orchestrating cytokine receptor expression and cytokine responsiveness. Activation of Raptor/mTORC1 integrates T cell receptor (TCR) and CD28 co-stimulatory signals in antigen-stimulated T cells. Our studies identify a Raptor/mTORC1-dependent pathway linking signal-dependent metabolic reprogramming to quiescence exit, and this in turn coordinates lymphocyte activation and fate decisions in adaptive immunity. We used microarrays to explore the gene expression profiles differentially expressed in CD4+ T-cells from wild-type (WT) and CD4(cre) x Raptor(fl/fl) mice before and after stimulation with anti CD3/CD28 antibodies.
2014-01-27 | E-GEOD-51668 | biostudies-arrayexpress
Project description:The mammalian target of rapamycin complex 1 (mTORC1) integrates nutrients, growth factors, stress, and energy status to regulate cell growth and metabolism. Amino acids promote mTORC1 lysosomal localization and subsequent activation. However, the subcellular location or interacting proteins of mTORC1 under amino acid deficient conditions is not completely understood. Here, we identify ADP-ribosylation factor GTPase-activating protein 1 (ArfGAP1) as a crucial regulator of mTORC1. ArfGAP1 interacts with mTORC1 in the absence of amino acids and inhibits mTORC1 lysosomal localization and activation. Mechanistically, the membrane curvature sensing amphipathic lipid packing sensor (ALPS) motifs that bind to vesicle membranes, are crucial for ArfGAP1 to interact with and regulate mTORC1 activity. Importantly, ArfGAP1 represses cell growth through mTORC1 and is an independent prognostic factor for the overall survival of pancreatic cancer patients. Our study identifies ArfGAP1 as a critical regulator of mTORC1 that functions by preventing the lysosomal transport and activation of mTORC1, with potential for cancer therapeutics.
2021-04-01 | PXD024603 | Pride
Project description:Infection by the Gram-negative bacterium Pseudomonas aeruginosa is common in hospitalized immunocompromised as well as immunocompetent ventilated patients and is often life-threatening because of resistance of the bacteria to antibiotics. This prompts the question whether the host’s immune system can be educated to combat this bacterium. Bacterial lipopolysaccharide (LPS) is known to promote host resistance to bacterial infections although an understanding of the underlying mechanism is lacking. Here we show that prior exposure to a single low dose of LPS protects mice from a lethal infection by P. aeruginosa. These mice displayed expansion of a neutrophil and an interstitial macrophage population that were barely detectable in mice that did not receive LPS prior to infection. Both cell populations were distinguishable from other immune cell populations by being enriched in gene sets that included phagocytosis- and cell-killing-associated genes. The cell killing gene set in the neutrophil population uniquely expressed Lgals3, which encodes the multifunctional antibacterial protein, galectin-3. Intravital imaging of neutrophils for bacterial phagocytosis, assessment of bacterial killing and neutrophil-associated galectin-3 protein levels together with use of galectin-3-deficient mice collectively highlight neutrophils and galectin-3 as central players in LPS-mediated protection. Interrogating the relevance of these findings in hospitalized patients with acute respiratory failure revealed significantly higher galectin-3 levels in endotracheal aspirates (ETAs) of survivors compared to non-survivors, galectin-3 levels strongly correlating with a neutrophil signature in the ETAs. Taken together, our study provides impetus to harnessing the potential of galectin-3-expressing neutrophils to protect the lung from lethal infections and respiratory failure.
2024-04-15 | GSE237646 | GEO
Project description:Pancreatic beta cells (β-cells) differentiate during fetal life, but only postnatally acquire the capacity for glucose-stimulated insulin secretion (GSIS). The molecular mechanisms driving this maturation of β-cell function remain incompletely understood. Here, we show that the control of cellular signaling in β-cells fundamentally switches from the nutrient sensor target of rapamycin (mTORC1) to the energy sensor 5'-adenosine monophosphate-activated protein kinase (AMPK), and that this is critical for functional maturation. Moreover, AMPK is activated by the dietary transition taking place during weaning, and this in turn inhibits mTORC1 activity to drive the adult β-cell phenotype. While forcing constitutive mTORC1 signaling in adult β-cells relegates them to a functionally immature phenotype with characteristic transcriptional and metabolic profiles, engineering the switch from mTORC1 to AMPK signaling is sufficient to promote β-cell mitochondrial biogenesis, a shift to oxidative metabolism, and functional maturation. We also show that type 2 diabetes, a condition marked by both mitochondrial degeneration and dysregulated GSIS, is associated with a remarkable reversion of the normal AMPK-dependent adult β-cell signature to a more neonatal one characterized by mTORC1 activation. Manipulating the way in which cellular nutrient signaling pathways regulate β-cell metabolism may thus offer new targets to improve β-cell function in diabetes.
2019-06-06 | GSE132261 | GEO
Project description:Prostate cancer (PCa) causes significant mortality among men worldwide. Galectin-4 plays an important roles in regulatiog cancer metastasis and high level of galectin-4 correlated with poor survival in subpopulation of PCa patients. To further understand the galectin-4-mediated signature and develop effective treatment, we froced expressed galectin-4 in 22Rv1 and LNCaP cells, and downregulated galectin-4 in 22Rv1-M4 cells. Next, cDNA microarray were applyed to study galectin-4-mediated gene expression and cancer progression.
2018-06-30 | GSE100301 | GEO
Project description:TORSEL, a 4EBP1-based mTORC1 live-cell sensor, reveals nutrient-sensing targeting by histone deacetylase inhibitor
| PRJNA1054503 | ENA
Project description:Animals sense and respond to nutrient availability in their environments, a task coordinated in part by the mTOR complex 1 (mTORC1) pathway. mTORC1 regulates growth in response to nutrients and, in mammals, senses specific amino acids through specialized sensors that bind the GATOR1/2 signaling hub. Given that animals can occupy diverse niches, we hypothesized that the pathway might evolve distinct sensors in different metazoan phyla. Whether such customization occurs—and how the mTORC1 pathway might capture new inputs—is unknown. Here, we identify the Drosophila melanogaster protein Unmet expectations (CG11596) as a species-restricted methionine sensor that directly binds the fly GATOR2 complex in a fashion antagonized by S-adenosylmethionine (SAM). We find that in Dipterans GATOR2 rapidly evolved the capacity to bind Unmet and to thereby repurpose a previously independent methyltransferase as a SAM sensor. Thus, the modular architecture of the mTORC1 pathway allows it to co-opt preexisting enzymes to expand its nutrient sensing capabilities, revealing a mechanism for conferring evolvability on an otherwise conserved system.
2024-03-21 | PXD050288 | Pride
Project description:MiT/TFE transcriptional activity controls lysosomal biogenesis and is negatively regulated by the nutrient sensor mTORC1. Some tumors bypass this regulatory circuit via genetic alterations that drive MiT/TFE expression and activity; however, the mechanisms by which cells with intact or constitutive mTORC1 signaling maintain lysosomal catabolism remain to be elucidated. Using the murine epidermis as a model system, we find that epidermal Tsc1 deletion results in a wavy hair phenotype due to increased EGFR degradation. Unexpectedly, constitutive mTORC1 activation increases lysosomal content via up-regulated expression and activity of MiT/TFEs, while genetic or prolonged pharmacologic mTORC1 inactivation has the reverse effect. This paradoxical up-regulation of lysosomal biogenesis by mTORC1 is mediated by feedback inhibition of AKT, and a resulting suppression of AKT-induced MiT/TFE proteasomal degradation. These data suggest that oncogenic feedback loops work to restrain or maintain cellular lysosomal content during chronically inhibited or constitutively active mTORC1 signaling respectively, and reveal a mechanism by which mTORC1 regulates upstream receptor tyrosine kinase signaling.
2020-04-14 | GSE124754 | GEO