An mTORC1-mediated negative feedback loop constrains amino acid-induced FLCN-Rag activation downstream of TSC2 loss
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE216545 | GEO | 2022/11/01
REPOSITORIES: GEO
Similar Datasets
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
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:Cells respond to mitochondrial energetic stress with rapid activation of the AMP-activated protein kinase (AMPK), which acutely inhibits anabolism and stimulates catabolism. AMPK also induces sustained transcriptional reprogramming of metabolism. The TFEB transcription factor is a major effector of AMPK signals, inducing lysosome genes following energetic stress. Yet the molecular mechanism underlying how AMPK activates TFEB remains unresolved. We demonstrate here that AMPK directly phosphorylates five conserved serine residues in FNIP1, which suppresses the function of the FLCN/FNIP1 RagC GAP complex, in turn controlling TFEB lysosomal localization. We demonstrate that FNIP1 phosphorylation is required for AMPK to induce nuclear translocation of TFEB, which is fully separable from AMPK control of canonical mTORC1 signaling. Using a non-phosphorylatable allele of FNIP1, we show that in parallel to lysosomal biogenesis, AMPK induces mitochondrial biogenesis via TFEB-dependent induction of PGC1a mRNA. This signaling from mitochondrial stress is also independent of amino-acid control of the Rags and TFEB, which still proceed normally in cells bearing the AMPK-non phosphorylatable allele of FNIP1. Taken together, mitochondrial energetic stress triggers AMPK/FNIP1-dependent TFEB nuclear translocation, inducing transcriptional waves of lysosomal and mitochondrial biogenesis.
2023-05-08 | GSE218827 | 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:The activation of cellular quality control pathways to maintain metabolic homeostasis and mitigate diverse cellular stresses is emerging as a critical growth and survival mechanism in many cancers. Autophagy, a highly conserved cellular self-degradative process, is a key player in the initiation and maintenance of pancreatic ductal adenocarcinoma (PDA). However, the regulatory circuits that activate autophagy, and how they enable reprogramming of PDA cell metabolism are unknown. We now show that autophagy regulation in PDA occurs as part of a broader program that coordinates activation of lysosome biogenesis, function and nutrient scavenging, through constitutive activation of the MiT/TFE family of bHLH transcription factors. In PDA cells, the MiT/TFE proteins - MITF, TFE3 and TFEB - override a regulatory mechanism that controls their nuclear translocation, resulting in their constitutive activation. By orchestrating the expression of a coherent network of genes that induce high levels of lysosomal catabolic function, the MiT/TFE factors are required for proliferation and tumorigenicity of PDA cells. Importantly, unbiased global metabolite profiling reveals that MiT/TFE-dependent autophagy-lysosomal activation is specifically required to maintain intracellular AA pools in PDA. This AA flux is part of a program that is essential for metabolic homeostasis and bioenergetics of PDA but not for their non-transformed counterparts. These results identify the MiT/TFE transcription factors as master regulators of the autophagy-lysosomal system in PDA and demonstrate a central role of the autophagosome-lysosome compartment in maintaining tumor cell metabolism through alternative amino acid acquisition and utilization. Examination of mRNA levels in pancreatic ductal adenocarcinoma (PDA) cell line 8988T after treatment with siRNA for control or TFE3
2015-04-03 | E-GEOD-62077 | biostudies-arrayexpress
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 activation of cellular quality control pathways to maintain metabolic homeostasis and mitigate diverse cellular stresses is emerging as a critical growth and survival mechanism in many cancers. Autophagy, a highly conserved cellular self-degradative process, is a key player in the initiation and maintenance of pancreatic ductal adenocarcinoma (PDA). However, the regulatory circuits that activate autophagy, and how they enable reprogramming of PDA cell metabolism are unknown. We now show that autophagy regulation in PDA occurs as part of a broader program that coordinates activation of lysosome biogenesis, function and nutrient scavenging, through constitutive activation of the MiT/TFE family of bHLH transcription factors. In PDA cells, the MiT/TFE proteins - MITF, TFE3 and TFEB - override a regulatory mechanism that controls their nuclear translocation, resulting in their constitutive activation. By orchestrating the expression of a coherent network of genes that induce high levels of lysosomal catabolic function, the MiT/TFE factors are required for proliferation and tumorigenicity of PDA cells. Importantly, unbiased global metabolite profiling reveals that MiT/TFE-dependent autophagy-lysosomal activation is specifically required to maintain intracellular AA pools in PDA. This AA flux is part of a program that is essential for metabolic homeostasis and bioenergetics of PDA but not for their non-transformed counterparts. These results identify the MiT/TFE transcription factors as master regulators of the autophagy-lysosomal system in PDA and demonstrate a central role of the autophagosome-lysosome compartment in maintaining tumor cell metabolism through alternative amino acid acquisition and utilization.
2015-04-03 | GSE62077 | GEO
Project description:In an attempt to elucidate the role of MiT/TFE families in the iron-mediated phenotypic changes of macrophages, we performed DNA microarray analysis using ferric chloride-stimulated RAW264 cells transfected with Tfe3/Tfeb or GFP. A number of genes upregulated by ferric chloride treatment in siGFP-transfected RAW264 cells were decreased in siTfe3/Tfeb-transfected cells, suggesting MiT/TFE families are involved in phenotypic changes of macrophages induced by iron.
2021-01-27 | GSE157472 | GEO
Project description:Within the endolysosomal pathway in mammalian cells, ESCRT complexes facilitate degradation of membrane proteins from limiting membranes of late endosomes. Recent studies revealed that yeast ESCRT proteins also sort for degradation, ubiquitinated proteins from vacuolar membrane. However, whether mammalian ESCRTs perform similar function at lysosomes remained unknown. Here, we studied the involvement of mammalian ESCRT-I in maintaining lysosomal membrane homeostasis and its implication in lysosome-related signaling. We show that ESCRT-I restricts the size of lysosomes and promotes degradation of lysosomal Ca2+ channel, MCOLN1 protein. ESCRT-I depletion induced transcriptional response related to MiT-TFE signaling and cholesterol biosynthesis, pointing to lysosomal dysfunction. The lack of ESCRT-I promoted abnormal cholesterol accumulation on lysosomes and activated TFEB/TFE3 transcription factors in Ca2+-MCOLN1-dependent, but lipid-independent manner. Hence, our study provides evidence that ESCRT-I maintains lysosomal homeostasis and elucidates MiT-TFE regulatory mechanism activated in response to ESCRT-I deprivation
2022-03-28 | GSE178665 | GEO
Project description:Birt-Hogg-Dubè (BHD) syndrome is an inherited condition caused by loss-of-function mutations in the gene encoding the tumor-suppressor protein folliculin (FLCN) and frequently associated with kidney cysts and cancer. FLCN acts as a negative regulator of TFEB and TFE3 transcription factors, master controllers of lysosomal biogenesis and autophagy, by enabling their phosphorylation by the mechanistic Target Of Rapamycin Complex 1 (mTORC1). We previously showed that deletion of TFEB rescued the renal cystic phenotype of kidney-specific Flcn KO mice. Using Flcn/TFEB/TFE3 double and triple KO mice we now show that both TFEB and TFE3 contribute, in a differential and cooperative manner, to kidney cystogenesis. Importantly, silencing of either TFEB or TFE3 rescued tumorigenesis in patient-derived xenografts (PDXs) generated from a kidney tumor of a BHD patient. Furthermore, transcriptome analyses performed in transgenic mice, PDXs and patient tumor samples revealed TFEB/TFE3 downstream targets that may contribute to their tumorigenic activity. Our findings demonstrate in disease-relevant models that TFEB and TFE3 are key drivers of kidney tumorigenesis and suggest novel therapeutic strategies based on the inhibition of these transcription factors.
2023-04-04 | PXD035450 | Pride