MTORC1 Activation is not sufficient to suppress hepatic PPAR-a signalling or ketogenesis
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ABSTRACT:
PROVIDER: PRJNA695502 | ENA |
REPOSITORIES: ENA
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Project description:we examined if the activation of the anabolic program mediated by the activation of the mTorc1 complex in the fasted state could suppress the robust catabolic programing and enhanced Pparα transcriptional of mice with a liver specific defect in mitochondrial long chain fatty acid oxidation (Cpt2L-/- mice). We found that the activation of mTorc1 in the fasted state was not sufficient to repress Pparα responsive genes or ketogenesis.
2021-06-15 | GSE165701 | GEO
Project description:The mechanistic target of rapamycin (mTOR) is often referred to as a master regulator of the cellular metabolism that can integrate the growth factor and nutrient signaling. Fasting suppresses hepatic mTORC1 activity via the activity of the tuberous sclerosis complex (TSC), a negative regulator of mTORC1, to suppress anabolic metabolism. The loss of TSC1 in the liver locks the liver in a constitutively anabolic state even during fasting, which was suggested to regulate peroxisome proliferator-activated receptor alpha (PPARα) signaling and ketogenesis, but the molecular determinants of this regulation are unknown. Here, we examined if the activation of the mTORC1 complex in mice by the liver-specific deletion of TSC1 (TSC1L-/-) is sufficient to suppress PPARα signaling and therefore ketogenesis in the fasted state. We found that the activation of mTORC1 in the fasted state is not sufficient to repress PPARα-responsive genes or ketogenesis. Furthermore, we examined whether the activation of the anabolic program mediated by mTORC1 complex activation in the fasted state could suppress the robust catabolic programming and enhanced PPARα transcriptional response of mice with a liver-specific defect in mitochondrial long-chain fatty acid oxidation using carnitine palmitoyltransferase 2 (Cpt2L-/-) mice. We generated Cpt2L-/-; Tsc1L-/- double-KO mice and showed that the activation of mTORC1 by deletion of TSC1 could not suppress the catabolic PPARα-mediated phenotype of Cpt2L-/- mice. These data demonstrate that the activation of mTORC1 by the deletion of TSC1 is not sufficient to suppress a PPARα transcriptional program or ketogenesis after fasting.
| S-EPMC8294577 | biostudies-literature
Project description:The clinical benefit of current mTOR inhibitors is limited, perhaps reflecting their intrinsic pharmacological profiles. Rapamycin analogs selectively inhibit mTORC1, but fail to suppress phosphorylation of the mTORC1 substrate 4EBP1, a translational repressor that is a key driver of oncogenic mTORC1 signaling. mTOR kinase active-site inhibitors fully suppress mTORC1 and phosphorylation of its substrates, but are active against mTORC2 and additional kinases, potentially contributing to tolerability limitations. The prototype bi-steric inhibitor RapaLink-1 exploits the selective mTORC1 interactions of rapamycin and the broad mTOR kinase inhibitory effects of an active-site inhibitor, through covalent linkage of the two pharmacophores to achieve complete mTORC1/2 inhibition. We demonstrate that the anti-proliferative activity of RapaLink-1 is dependent upon mTORC1 and suppression of 4EBP1 phosphorylation. Using a rational design strategy, we tuned the affinities of the rapamycin core and ATP-mimetic moieties to create novel bi-steric inhibitors with enhanced mTORC1 selectivity and potency against 4EBP1 phosphorylation. mTORC1-selective bi-steric compounds produced durable inhibition of 4EBP1 phosphorylation in vitro and in vivo, and drove tumor regressions at well-tolerated doses in xenograft models of breast cancer.
2021-04-05 | GSE138417 | GEO
Project description:Ketone bodies, intermediates in energy metabolism and signaling, have attracted significant attention due to their role in health and disease. We performed around the clock study on ketone bodies and ketogenesis with mice on different diets. We found that caloric restriction, a dietary intervention that improves metabolism and longevity, induced high amplitude circadian rhythms in blood βOHB. The blood βOHB rhythms resulted from rhythmic ketogenesis in the liver controlled by the interaction between the circadian clock and PPAR transcriptional networks. This interaction results in transcriptional reprogramming of in beta-oxidation and ketogenesis enzymes. The reprogramming is impaired in circadian clock mutant mice. The circadian clock gated ketogenesis contributes to the diet impact on health and longevity.
2022-08-31 | GSE211975 | GEO
Project description:Selective Inhibitors of mTORC1 Activate 4EBP1 and Suppress Tumor Growth
| PRJNA575792 | ENA
Project description:Glutathione peroxidase 4 (GPX4) utilizes glutathione (GSH) to detoxify lipid peroxidation and
plays an essential role in inhibiting ferroptosis. As a selenoprotein, GPX4 protein synthesis is
highly inefficient and energetically costly. How cells coordinate GPX4 synthesis with nutrient
availability remains unclear. In this study, integrated proteomic and functional analyses reveal
that SLC7A11-mediated cystine uptake promotes not only GSH synthesis but also GPX4 protein synthesis. Mechanistically, cyst(e)ine activates mechanistic/mammalian target of rapamycin complex 1 (mTORC1) and promotes GPX4 protein synthesis at least partly through the mTORC1-4E-BP signaling axis. Pharmacologic inhibition of mTORC1 decreases GPX4 protein levels, sensitizes cancer cells to ferroptosis, and synergizes with ferroptosis inducers (FINs) to suppress patient-derived xenograft tumor growth in vivo. Together, our results reveal a hitherto unrecognized regulatory mechanism to coordinate GPX4 protein synthesis with cyst(e)ine availability and suggest to use the combination of mTORC1 inhibitors and FINs in cancer treatment.
2020-08-25 | MSV000086009 | MassIVE
Project description:In this study, we use the epidermis as a model system to elucidate the cellular effects and signaling feedback sequelae of mTORC1 loss-of-function in epithelial tissue. In mice with conditional epidermal loss of mTORC1 components Rheb or Rptor, we find that mTORC1 loss-of-function unexpectedly results in a profound skin barrier defect with epidermal abrasions, blistering and early postnatal lethality, due to a thinned epidermis with decreased desmosome expression and incomplete biochemical differentiation. Impaired cell-cell adhesion in the context of mTORC1 loss-of-function is caused by constitutive activation of Rho kinase (ROCK) signaling with increased cytoskeletal tension, and inhibition or silencing of ROCK1 is sufficient to rescue keratinocyte adhesion and biochemical differentiation. mTORC1 loss-of-function results in marked feedback up-regulation of upstream TGF-β signaling, triggering ROCK activity and its downstream effects on desmosomal gene expression. These findings elucidate a novel role for mTORC1 in the regulation of epithelial barrier formation, cytoskeletal tension and cell adhesion and underscore the complexity of signaling feedback after mTORC1 inhibition
2020-04-14 | GSE102026 | 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:To further explain pathology of mTORC1 -stimulated osteoarthritis, we have employed whole genome microarray expression profiling as a discovery platform to identify miRNAs which involved in development of mTORC1-stimulated osteoarthritis We generated Col2a1-specific deletion of Tsc1 mice. mTORC1 induced miRNAs expression in development of osteoarthritis was measured at eight weeks after birth. Independent experiments were performed using knee joint cartilage from Col2a1Tsc1KO and control mice.
2016-07-30 | E-GEOD-71484 | biostudies-arrayexpress
Project description:To screen miRNAs specifically regulated by mTORC1 or mTORC2, a global miRNA expression profile in MCF-7 cells treated with rapamycin or PP242 (mTORC1/2 kinase inhibitor) was developed using microarray. control, rapamycin or PP242 treated human MCF-7 cells were harvested 48h post-treatment and subjected to total RNA extraction.
2014-09-11 | E-GEOD-61289 | biostudies-arrayexpress