Genome wide transcriptional change by GPR155/LYCHOS loss
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE196384 | GEO | 2022/09/01
REPOSITORIES: GEO
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Project description:Cholesterol and phosphoinositides (PI) are two critically important lipids that are found in cellular membranes and dysregulated in many disorders. Therefore, uncovering molecular pathways connecting these essential lipids may offer new therapeutic insights. We report that loss of function of lysosomal Niemann-Pick Type C1 (NPC1) cholesterol transporter, which leads to neurodegenerative NPC disease, initiates a signaling cascade that alters the cholesterol/phosphatidylinositol 4-phosphate (PtdIns4P) countertransport cycle between Golgi-endoplasmic reticulum (ER), as well as lysosome-ER membrane contact sites (MCS). Central to these disruptions is increased recruitment of phosphatidylinositol 4-kinases-PI4KIIα and PI4KIIIβ-which boosts PtdIns4P metabolism at Golgi and lysosomal membranes. Aberrantly increased PtdIns4P levels elevate constitutive anterograde secretion from the Golgi complex, and mTORC1 recruitment to lysosomes. NPC1 disease mutations phenocopy the transporter loss of function and can be rescued by inhibition or knockdown of either key phosphoinositide enzymes or their recruiting partners. In summary, we show that the lysosomal NPC1 cholesterol transporter tunes the molecular content of Golgi and lysosome MCS to regulate intracellular trafficking and growth signaling in health and disease.
2021-09-15 | MTBLS2612 | MetaboLights
Project description:Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a critical regulator of cell growth by integrating multiple signals (nutrients, growth factors, energy and stress) and is frequently deregulated in many types of cancer. We used a robust experimental paradigm involving the combination of two interventions, one genetic and one pharmacologic to identify genes regulated transcriptionally by mTORC1. In Tsc2+/+, but not Tsc2-/- immortalized mouse embryo fibroblasts (MEFs), serum deprivation downregulates mTORC1 activity. In Tsc2-/- cells, abnormal mTORC1 activity can be downregulated by treatment with rapamycin (sirolimus). By contrast, rapamycin has little effect on mTORC1 in Tsc2+/+ cells in which mTORC1 is already inhibited by low serum. Thus, under serum deprived conditions, mTORC1 activity is low in Tsc2+/+ cells (untreated or rapamycin treated), high in Tsc2-/- cells, but lowered by rapamycin; a pattern referred to as a M-bM-^@M-^\low/low/high/lowM-bM-^@M-^] or M-bM-^@M-^\LLHLM-bM-^@M-^]. We found that mTORC1 regulated the expression of, among other lysosomal genes, V-ATPases through the transcription factor EB (TFEB, Tcfeb in the mouse). The knockdown of Tfeb resulted in the 'flattening' of the LLHL pattern and allowed the identification of genes regulated by mTORC1 through Tfeb Mouse embryo fibroblasts (MEFs) wild type or deficient in Tsc2 expressing a Tfeb shRNA or scrambled shRNA vector were treated with 25 nM rapamycin or vehicle (methanol) for 24 h under low serum conditions (0.1% FBS)
2011-08-02 | E-GEOD-28021 | 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:Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a critical regulator of cell growth by integrating multiple signals (nutrients, growth factors, energy and stress) and is frequently deregulated in many types of cancer. We used a robust experimental paradigm involving the combination of two interventions, one genetic and one pharmacologic to identify genes regulated transcriptionally by mTORC1. In Tsc2+/+, but not Tsc2-/- immortalized mouse embryo fibroblasts (MEFs), serum deprivation downregulates mTORC1 activity. In Tsc2-/- cells, abnormal mTORC1 activity can be downregulated by treatment with rapamycin (sirolimus). By contrast, rapamycin has little effect on mTORC1 in Tsc2+/+ cells in which mTORC1 is already inhibited by low serum. Thus, under serum deprived conditions, mTORC1 activity is low in Tsc2+/+ cells (untreated or rapamycin treated), high in Tsc2-/- cells, but lowered by rapamycin; a pattern referred to as a “low/low/high/low” or “LLHL”. We found that mTORC1 regulated the expression of, among other lysosomal genes, V-ATPases through the transcription factor EB (TFEB, Tcfeb in the mouse). The knockdown of Tfeb resulted in the 'flattening' of the LLHL pattern and allowed the identification of genes regulated by mTORC1 through Tfeb
2011-08-03 | GSE28021 | GEO
Project description:The mechanistic target of rapamycin complex 1 (mTORC1) integrates inputs from growth factors and nutrients, but how mTORC1 autoregulates its activity remains unclear. The MiT/TFE transcription factors are phosphorylated and inactivated by mTORC1 following lysosomal recruitment by RagC/D GTPases in response to amino acid stimulation. We find that starvation-induced lysosomal localization of the RagC/D GAP complex, FLCN:FNIP2, is markedly impaired in a mTORC1-sensitive manner in cells with TSC2 loss, resulting in unexpected TFEB hypophosphorylation and activation upon feeding. TFEB phosphorylation in TSC2-null cells is partially restored by destabilization of the lysosomal folliculin complex (LFC) induced by FLCN mutants and is fully rescued by forced lysosomal localization of the FLCN:FNIP2 dimer. Our data indicate that a negative feedback loop constrains amino acid-induced, FLCN:FNIP2-mediated RagC activity in cells with constitutive mTORC1 signaling, and the resulting MiT/TFE hyperactivation may drive oncogenesis with loss of the TSC2 tumor suppressor.
2022-11-01 | GSE216545 | GEO
Project description:Tuberous Sclerosis Complex (TSC) is caused by germline TSC1 or TSC2 mutations, leading to hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1) and tumors in multiple organs including the brain, heart, lung (lymphangioleiomyomatosis), and kidney (angiomyolipoma and renal cell carcinoma). Previously, we found that TFEB is constitutively active in models of TSC. To determine the impact of TFEB in vivo, we generated two novel mouse models of TSC, resulting in premature death, in which kidney pathology was the primary phenotype. RNA sequencing revealed that lysosomal and proteasomal gene pathways were the most highly upregulated in the TSC2-deficient kidneys. Knockout of TFEB rescued both kidney pathology and overall survival in both models, indicating that TFEB is the primary driver of renal disease in TSC. Importantly, mTORC1 activity, which was elevated in the TSC2 knockout kidneys, was normalized by TFEB knockout. Knockdown of Rheb or treatment of TSC2-deficient cells with Rapamycin paradoxically increases TFEB phosphorylation at the mTORC1-site (S211) and relocalizes TFEB from the nucleus to the cytoplasm via a Rag-dependent mechanism. Accordingly, treatment of TSC2 knockout mice with Rapamycin normalized lysosomal gene expression, similar to TFEB knockout, suggesting that the beneficial effects of Rapamycin in TSC are TFEB-dependent. These results change the view of the mechanisms leading to mTORC1 hyperactivation in TSC and may lead to novel therapeutic avenues for the treatment of TSC.
2023-09-28 | GSE244072 | GEO
Project description:Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a critical regulator of cell growth by integrating multiple signals (nutrients, growth factors, energy and stress) and is frequently deregulated in many types of cancer. We used a robust experimental paradigm involving the combination of two interventions, one genetic and one pharmacologic to identify genes regulated transcriptionally by mTORC1. In Tsc2+/+, but not Tsc2-/- immortalized mouse embryo fibroblasts (MEFs), serum deprivation downregulates mTORC1 activity. In Tsc2-/- cells, abnormal mTORC1 activity can be downregulated by treatment with rapamycin (sirolimus). By contrast, rapamycin has little effect on mTORC1 in Tsc2+/+ cells in which mTORC1 is already inhibited by low serum. Thus, under serum deprived conditions, mTORC1 activity is low in Tsc2+/+ cells (untreated or rapamycin treated), high in Tsc2-/- cells, but lowered by rapamycin; a pattern referred to as a M-^Slow/low/high/lowM-^T or M-^SLLHLM-^T, which allowed the identification of genes regulated by mTORC1 by performing the appropriate comparisons
2011-08-02 | E-GEOD-27982 | biostudies-arrayexpress
Project description:The mammalian target of rapamycin complex 1 (mTORC1) is a key nutrient-sensing hub and a master regulator of cellular growth and metabolism. Activation of mTORC1 by amino acids and growth factors requires its recruitment to the lysosomes. Furthermore, lysosomal distribution has been shown to be intimately involved in the control of mTORC1, where localisation of lysosomes near plasma membrane increases mTORC1 activity. However, the underlying mechanisms by which lysosomal positioning impacts on mTORC1 signalling are not well understood. To understand better the spatial associations of mTORC1, we analysed the proximal ‘interactome’ of the constitutive component of mTORC1, Raptor, using BioID2-based proximity labelling and MS-based proteomics.
2021-09-08 | PXD012795 | Pride
Project description:Differentiation is critical for epithelial cell fate decisions, but the signals involved remain unclear. The kidney proximal tubule (PT) cells reabsorb disulphide-rich proteins through endocytosis, generating cystine via lysosomal proteolysis. Here we report that defective cystine mobilization from lysosomes through cystinosin (CTNS), which is mutated in cystinosis, diverts PT cells towards growth and proliferation, disrupting their functions. Mechanistically, lysosomal cystine storage stimulates Ragulator-Rag GTPase-dependent recruitment of mechanistic target of Rapamycin complex 1 (mTORC1) and its constitutive activation. Re-introduction of CTNS restores nutrient-dependent regulation of mTORC1 in knockout cells, whereas cell-permeant analogues of L-cystine, accumulating within lysosomes, render wild-type cells resistant to nutrient withdrawal. Therapeutic mTORC1 inhibition corrects lysosome and differentiation downstream of cystine storage, and phenotypes in a zebrafish model of cystinosis. Thus, cystine serves as a lysosomal signal that tailors mTORC1 signaling and metabolism to direct epithelial cell fate decisions. These results identify mechanisms and therapeutic targets for dysregulated homeostasis in cystinosis.
2023-03-08 | GSE226397 | GEO
Project description:Differentiation is critical for epithelial cell fate decisions, but the signals involved remain unclear. The kidney proximal tubule (PT) cells reabsorb disulphide-rich proteins through endocytosis, generating cystine via lysosomal proteolysis. Here we report that defective cystine mobilization from lysosomes through cystinosin (CTNS), which is mutated in cystinosis, diverts PT cells towards growth and proliferation, disrupting their functions. Mechanistically, lysosomal cystine storage stimulates Ragulator-Rag GTPase-dependent recruitment of mechanistic target of Rapamycin complex 1 (mTORC1) and its constitutive activation. Re-introduction of CTNS restores nutrient-dependent regulation of mTORC1 in knockout cells, whereas cell-permeant analogues of L-cystine, accumulating within lysosomes, render wild-type cells resistant to nutrient withdrawal. Therapeutic mTORC1 inhibition corrects lysosome and differentiation downstream of cystine storage, and phenotypes in a zebrafish model of cystinosis. Thus, cystine serves as a lysosomal signal that tailors mTORC1 signaling and metabolism to direct epithelial cell fate decisions. These results identify mechanisms and therapeutic targets for dysregulated homeostasis in cystinosis.
2023-03-08 | GSE226396 | GEO