scholarly journals Activation of Downstream mTORC1 Target Ribosomal Protein S6 Kinase (S6K) Can Be Found in a Subgroup of Dutch Patients with Granulomatous Pulmonary Disease

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3545
Author(s):  
Raisa Kraaijvanger ◽  
Kees Seldenrijk ◽  
Els Beijer ◽  
Jan Damen ◽  
Jayne Louise Wilson ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
S6 Kinase ◽  
Downstream Target ◽  
Ribosomal Protein S6 ◽  
Downstream Effector ◽  
Mtorc1 Signaling ◽  
Mtorc1 Pathway ◽  
Granulomatous Disorder ◽  
Granulomatous Diseases ◽  
Mtorc1 Activation

Mechanistic target of rapamycin complex 1 (mTORC1) has been linked to different diseases. The mTORC1 signaling pathway is suggested to play a role in the granuloma formation of sarcoidosis. Recent studies demonstrated conflicting data on mTORC1 activation in patients with sarcoidosis by measuring activation of its downstream target S6 kinase (S6K) with either 33% or 100% of patients. Therefore, the aim of our study was to reevaluate the percentage of S6K activation in sarcoidosis patients in a Dutch cohort. To investigate whether this activation is specific for sarcoid granulomas, we also included Dutch patients with other granulomatous diseases of the lung. The activation of the S6K signaling pathway was evaluated by immunohistochemical staining of its downstream effector phospho-S6 in tissue sections. Active S6K signaling was detected in 32 (43%) of the sarcoidosis patients. Twelve (31%) of the patients with another granulomatous disorder also showed activated S6K signaling, demonstrating that the mTORC1 pathway may be activated in a range for different granulomatous diseases (p = 0.628). Activation of S6K can only be found in a subgroup of patients with sarcoidosis, as well as in patients with other granulomatous pulmonary diseases, such as hypersensitivity pneumonitis or vasculitis. No association between different clinical phenotypes and S6K activation can be found in sarcoidosis.

scholarly journals Prostaglandin E2 activates the mTORC1 pathway through an EP4/cAMP/PKA- and EP1/Ca2+-mediated mechanism in the human pancreatic carcinoma cell line PANC-1

2015 ◽  
Vol 309 (10) ◽  
pp. C639-C649 ◽  
Author(s):  
Hui-Hua Chang ◽  
Steven H. Young ◽  
James Sinnett-Smith ◽  
Caroline Ei Ne Chou ◽  
Aune Moro ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Pancreatic Cancer ◽  
Prostaglandin E2 ◽  
Human Pancreatic Cancer ◽  
Pancreatic Carcinoma Cell Line ◽  
Pancreatic Cancer Cells ◽  
Mtorc1 Signaling ◽  
Mtorc1 Pathway ◽  
Pka Pathway ◽  
Mtorc1 Activation

Obesity, a known risk factor for pancreatic cancer, is associated with inflammation and insulin resistance. Proinflammatory prostaglandin E2 (PGE2) and elevated insulin-like growth factor type 1 (IGF-1), related to insulin resistance, are shown to play critical roles in pancreatic cancer progression. We aimed to explore a potential cross talk between PGE2 signaling and the IGF-1/Akt/mammalian target of rapamycin complex 1 (mTORC1) pathway in pancreatic cancer, which may be a key to unraveling the obesity-cancer link. In PANC-1 human pancreatic cancer cells, we showed that PGE2 stimulated mTORC1 activity independently of Akt, as evaluated by downstream signaling events. Subsequently, using pharmacological and genetic approaches, we demonstrated that PGE2-induced mTORC1 activation is mediated by the EP4/cAMP/PKA pathway, as well as an EP1/Ca2+-dependent pathway. The cooperative roles of the two pathways were supported by the maximal inhibition achieved with the combined pharmacological blockade, and the coexistence of highly expressed EP1 (mediating the Ca2+ response) and EP2 or EP4 (mediating the cAMP/PKA pathway) in PANC-1 cells and in the prostate cancer line PC-3, which also robustly exhibited PGE2-induced mTORC1 activation, as identified from a screen in various cancer cell lines. Importantly, we showed a reinforcing interaction between PGE2 and IGF-1 on mTORC1 signaling, with an increase in IL-23 production as a cellular outcome. Our data reveal a previously unrecognized mechanism of PGE2-stimulated mTORC1 activation mediated by EP4/cAMP/PKA and EP1/Ca2+ signaling, which may be of great importance in elucidating the promoting effects of obesity in pancreatic cancer. Ultimately, a precise understanding of these molecular links may provide novel targets for efficacious interventions devoid of adverse effects.

scholarly journals Glucagon acts in a dominant manner to repress insulin-induced mammalian target of rapamycin complex 1 signaling in perfused rat liver

2009 ◽  
Vol 297 (2) ◽  
pp. E410-E415 ◽  
Author(s):  
Jamie I. Baum ◽  
Scot R. Kimball ◽  
Leonard S. Jefferson
Keyword(s):  
Protein Metabolism ◽  
Mammalian Target Of Rapamycin ◽  
Target Of Rapamycin ◽  
Perfused Rat Liver ◽  
S6 Kinase ◽  
Akt Phosphorylation ◽  
Ribosomal Protein S6 ◽  
Mtorc1 Signaling ◽  
Kinase A

The opposing actions of insulin and glucagon on hepatic carbohydrate metabolism are well documented. In contrast, relatively little is known about how the two hormones interact to regulate hepatic protein metabolism. Previously, we reported that glucagon in the absence of insulin represses signaling through the mammalian target of rapamycin complex 1 (mTORC1). In the present study, we sought to determine whether or not the action of one hormone would dominate over the other in the regulation of mTORC1 signaling. Livers were perfused in situ with medium containing either no added hormones (control), 10 nM insulin, 100 nM glucagon, or a combination of the hormones. Compared with control livers, insulin stimulated Akt phosphorylation and mTORC1 signaling, as assessed by increased phosphorylation of the mTORC1 targets eIF4E-binding protein (4E-BP)1 and ribosomal protein S6 kinase (S6K)1, and promoted assembly of the eIF4G·eIF4E complex. Glucagon alone had no effect on mTORC1 signaling but stimulated the activity of protein kinase A (PKA). In the presence of a combination of insulin and glucagon, Akt and TSC2 phosphorylation and PKA activity were all increased compared with controls. However, mTORC1 signaling was repressed compared with livers perfused with medium containing insulin alone, and this effect was associated with reduced assembly of the mTORC1·eIF3 complex. Overall, the results suggest that glucagon acts in a dominant manner to repress insulin-induced mTORC1 signaling, which is in contrast to previous studies showing a dominant action of insulin in the control of hepatic gluconeogenesis.

scholarly journals Luteinizing Hormone/Human Chorionic Gonadotropin-Mediated Activation of mTORC1 Signaling Is Required for Androgen Synthesis by Theca-Interstitial Cells

2012 ◽  
Vol 26 (10) ◽  
pp. 1732-1742 ◽  
Author(s):  
Murugesan Palaniappan ◽  
K. M. J. Menon
Keyword(s):  
Chorionic Gonadotropin ◽  
Regulatory Protein ◽  
Steroidogenic Acute Regulatory Protein ◽  
Steroidogenic Enzymes ◽  
Steroidogenic Enzyme ◽  
S6 Kinase ◽  
Ribosomal Protein S6 ◽  
Mtorc1 Signaling ◽  
Steroidogenic Acute Regulatory ◽  
I Cells

Abstract LH triggers the biosynthesis of androgens in the theca-interstitial (T-I) cells of ovary through the activation of a cAMP-dependent pathway. We have previously shown that LH/human chorionic gonadotropin (hCG) activates mammalian target of rapamycin complex 1 (mTORC1) signaling network, leading to cell proliferation. In the present study, we provide evidence that the LH/hCG-mediated activation of the mTORC1 signaling cascade is involved in the regulation of steroidogenic enzymes in androgen biosynthesis. Treatment with LH/hCG increased the expression of downstream targets of mTORC1, ribosomal protein S6 kinase 1, and eukaryotic initiation factor 4E as well as steroidogenic enzymes. LH/hCG-mediated stimulation of the steroidogenic enzyme mRNA was blocked by the mTORC1 inhibitor, rapamycin. This inhibitory effect was selective because rapamycin failed to block hCG-mediated increase in the expression of Star mRNA levels. Furthermore, pharmacological targeting of mTORC1 with rapamycin also blocked LH/hCG- or forskolin-induced expression of cAMP response element-binding protein (CREB) and steroidogenic enzymes (P450 side-chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase type 1, and 17α-hydroxylase/17,20 lyase) but produced no effect on steroidogenic acute regulatory protein levels. These results were further confirmed by demonstrating that the knockdown of mTOR using small interfering RNA selectively abrogated the LH/hCG-induced increase in steroidogenic enzyme expression, without affecting steroidogenic acute regulatory protein expression. LH/hCG-stimulated androgen production was also blocked by rapamycin. Furthermore, the pharmacological inhibition of mTORC1 or ribosomal protein S6 kinase 1 signaling prevented the LH/hCG-induced phosphorylation of CREB. Chromatin immunoprecipitation assays revealed the association of CREB with the proximal promoter of the Cyp17a1 gene in response to hCG, and this association was reduced by rapamycin treatment. Taken together, our findings show for the first time that LH/hCG-mediated activation of androgen biosynthesis is regulated by the mTORC1 signaling pathway in T-I cells.

scholarly journals IL-2– and IL-15–induced activation of the rapamycin-sensitive mTORC1 pathway in malignant CD4+ T lymphocytes

Blood ◽  
2008 ◽  
Vol 111 (4) ◽  
pp. 2181-2189 ◽  
Author(s):  
Michal Marzec ◽  
Xiaobin Liu ◽  
Monika Kasprzycka ◽  
Agnieszka Witkiewicz ◽  
Puthiyaveettil N. Raghunath ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Cell Transformation ◽  
Single Agent ◽  
Large Cell ◽  
Dependent Manner ◽  
T Cell Lymphomas ◽  
Mtorc1 Signaling ◽  
Mtorc1 Pathway ◽  
Mtorc1 Activation

We examined functional status, activation mechanisms, and biologic role of the mTORC1 signaling pathway in malignant CD4+ T cells derived from the cutaneous T-cell lymphoma (CTCL). Whereas the spontaneously growing CTCL-derived cell lines displayed persistent activation of the TORC1 as well as the PI3K/Akt and MEK/ERK pathways, the IL-2–dependent cell lines activated the pathways in response to IL-2 and IL-15 but not IL-21. Activation of mTORC1 and MEK/ERK was nutrient dependent. The mTORC1, PI3K/Akt, and MEK/ERK pathways could also be activated by IL-2 in the primary leukemic, mitogen-preactivated CTCL cells. mTORC1 activation was also detected in the CTCL tissues in the lymphoma stage–dependent manner with the highest percentage of positive cells present in the cases with a large cell transformation. Rapamycin inhibited mTORC1 signaling and suppressed CTCL cell proliferation but showed little effect on their apoptotic rate when used as a single agent. Activation of the mTORC1, PI3K/Akt, and MEK/ERK pathways was strictly dependent on the Jak3 and Jak1 kinases. Finally, mTORC1 activation was transduced preferentially through the PI3K/Akt pathway. These findings document the selective γc-signaling cytokine-mediated activation of the mTORC1 pathway in the CTCL cells and suggest that the pathway represents a therapeutic target in CTCL and, possibly, other T-cell lymphomas.

scholarly journals circRNA LDLRAD3 Enhances the Malignant Behaviors of NSCLC Cells via the miR-20a-5p-SLC7A5 Axis Activating the mTORC1 Signaling Pathway

2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
Yu Li ◽  
Guangle Qin ◽  
Jinyun Du ◽  
Peng Yue ◽  
Yanling Zhang ◽  
...  
Keyword(s):  
Western Blot ◽  
Signaling Pathway ◽  
Circular Rna ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Potential Therapeutic Target ◽  
Expression Levels ◽  
Mtorc1 Signaling ◽  
Mtorc1 Pathway ◽  
Related Proteins

Circular RNA LDLRAD3 behaved as an oncogene in several malignancies, but its effects in NSCLC and the involvement of downstream molecules and activation of signaling pathways had not been fully reported. We planned to explore how LDLRAD3 facilitated the malignancy of NSCLC. QRT-PCR was performed to evaluate the expression levels of LDLRAD3, miR-20a-5p, and SLC7A5 in NSCLC tissues and cells. si-LDLRAD3 was transfected to A549 and H1299 cells to knock down intrinsic LDLRAD3 to determine its oncogenic roles. CCK-8 assay and transwell assay were executed to assess cell proliferative, migrative, and invasive abilities. Dual-luciferase reporter (DLR) assay was manipulated to verify the ENCORI-predicted relationships between LDLRAD3 and miR-20a-5p and between miR-20a-5p and SLC7A5. Western blot, immunofluorescent assay, and immunohistochemistry were applied to explore the expression levels of SLC7A5, and the levels of mTORC1 pathway-related proteins were evaluated using western blot. Rescue experiments were conducted by transfecting si-LDLRAD3, miR-20a-5p inhibitor, and si-SLC7A5 to explore the influence of the LDLRAD3-miR-20a-5p-SLC7A5 axis on the malignant behaviors of NSCLC cells. The expression levels of LDLRAD3 and SLC7A5 were boosted, whereas miR-20a-5p was impeded in NSCLC tissues and cell lines. Knockdown of LDLRAD3 weakened the proliferation, migration, and invasion of A549 and H1299 cells. LDLRAD3 was verified to sponge miR-20a-5p and miR-20a-5p targeted SLC7A5. LDLRAD3 activated the mTORC1 singling pathway via the miR-20a-5p-SLC7A5 axis to strengthen the malignant properties of A549 and H1299 cells. We concluded that LDLRAD3 exerted oncogenic effects via the miR-20a-5p-SLC7A5 axis to activate the mTORC1 signaling pathway in NSCLC. Our findings enlightened that LDLRAD3 could become a potential therapeutic target in the treatment and management of NSCLC.

Abstract P446: Sestrin2 Suppresses Age-related Hypertrophy by Inhibiting mTORC1 Signaling Pathway

Hypertension ◽  
2017 ◽  
Vol 70 (suppl_1) ◽  
Author(s):  
Nanhu Quan ◽  
Courtney Cates ◽  
Thomas Rousselle ◽  
Ji Li
Keyword(s):  
Ex Vivo ◽  
Energy State ◽  
Critical Role ◽  
Pressure Overload ◽  
Acid Oxidation ◽  
Protein Levels ◽  
Age Related ◽  
Mtorc1 Signaling ◽  
Mtorc1 Pathway ◽  
Mtorc1 Activation

Introduction: The mechanistic target of rapamycin complex 1 (mTORC1) plays a critical role in the regulation of cell growth and energy state. A novel stress-inducible protein, Sestrin2 was recognized as a sensor for mTORC1 pathway. Hypothesis: The cardiac mTORC1 activation modulated by Sestrin2 is impaired in aging that sensitizes heart to hypertrophy. Methods: C57BL/6J young WT (4-6 months) and aged WT mice (24-26 months), and young Sestrin2 knockout mice (4-6 months) were subjected to transverse aortic constriction (TAC) for pressure overload. The ex vivo working heart perfusion was used for measuring substrate metabolism. Results: The protein levels of cardiac Sestrin2 were decreased with aging. There are no phenotypic differences in young WT, aged WT and Sesn2 KO mice under normal physiology, while aged WT and Sesn2 KO versus young WT mice exhibit bigger hearts after 4 weeks of TAC surgery. The echocardiography showed an impaired cardiac function of aged WT and Sesn2 KO hearts by pressure overload. The pressure overload-induced phosphorylation of mTOR and mTORC1 downstream effectors 4E-BP1 and p70S6K were augmented in aged WT and Sesn2 KO versus young WT hearts. The swollen mitochondria with severely disrupted cristae and higher levels of redox markers pShc 66 and 4-hydroxynonenal were observed in aged WT and Sesn2 KO versus young WT hearts by pressure overload. The rate of glucose oxidation and fatty acid oxidation were impaired in the aged WT and Sesn2 KO versus young WT hearts by pressure overload. Intriguingly, pressure overload induced an interaction between Sestrin2 and GATOR2, a complex of unknown function that positively regulates mTORC1. Moreover, the binding affinity between Sestrin2 and GATOR2 is impaired in the aged WT hearts (p<0.05 vs. young WT). Furthermore, Adeno-associated virus 9 (AAV9)-Sestrin2 were delivered into the aged WT and Sesn2 KO hearts via a coronary delivery approach that rescued the protein levels of Sestrin2, attenuated mTORC1 activation and increased the tolerance of both aged WT and Sesn2 KO hearts to pressure overload. Conclusions: Cardiac Sestrin2 is a sensor for mTORC1 pathway in response to pressure overload. Sestrin2 deficiency in aging could be a reason for an increased sensitivity to hypertrophy in the elderly.

scholarly journals Gαq activation modulates autophagy by promoting mTORC1 signaling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofía Cabezudo ◽  
Maria Sanz-Flores ◽  
Alvaro Caballero ◽  
Inmaculada Tasset ◽  
Elena Rebollo ◽  
...  
Keyword(s):  
Nutrient Status ◽  
Autophagy Induction ◽  
Pathway Activation ◽  
Mtorc1 Signaling ◽  
Different Types ◽  
Mtorc1 Pathway ◽  
Mtorc1 Activation ◽  
G Protein Coupled ◽  
Activation Status

AbstractThe mTORC1 node plays a major role in autophagy modulation. We report a role of the ubiquitous Gαq subunit, a known transducer of plasma membrane G protein-coupled receptors signaling, as a core modulator of mTORC1 and autophagy. Cells lacking Gαq/11 display higher basal autophagy, enhanced autophagy induction upon different types of nutrient stress along with a decreased mTORC1 activation status. They are also unable to reactivate mTORC1 and thus inactivate ongoing autophagy upon nutrient recovery. Conversely, stimulation of Gαq/11 promotes sustained mTORC1 pathway activation and reversion of autophagy promoted by serum or amino acids removal. Gαq is present in autophagic compartments and lysosomes and is part of the mTORC1 multi-molecular complex, contributing to its assembly and activation via its nutrient status-sensitive interaction with p62, which displays features of a Gαq effector. Gαq emerges as a central regulator of the autophagy machinery required to maintain cellular homeostasis upon nutrient fluctuations.

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