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1.
Int J Mol Sci ; 20(18)2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31487963

RESUMO

The TORC2 gene is a member of the transducer of the regulated cyclic adenosine monophosphate (cAMP) response element binding protein gene family, which plays a key role in metabolism and adipogenesis. In the present study, we confirmed the role of TORC2 in bovine preadipocyte proliferation through cell cycle staining flow cytometry, cell counting assay, 5-ethynyl-2'-deoxyuridine staining (EdU), and mRNA and protein expression analysis of proliferation-related marker genes. In addition, Oil red O staining analysis, immunofluorescence of adiponectin, mRNA and protein level expression of lipid related marker genes confirmed the role of TORC2 in the regulation of bovine adipocyte differentiation. Furthermore, the transcription start site and sub-cellular localization of the TORC2 gene was identified in bovine adipocytes. To investigate the underlying regulatory mechanism of the bovine TORC2, we cloned a 1990 bp of the 5' untranslated region (5'UTR) promoter region into a luciferase reporter vector and seven vector fragments were constructed through serial deletion of the 5'UTR flanking region. The core promoter region of the TORC2 gene was identified at location -314 to -69 bp upstream of the transcription start site. Based on the results of the transcriptional activities of the promoter vector fragments, luciferase activities of mutated fragments and siRNAs interference, four transcription factors (CCAAT/enhancer-binding protein C/BEP, X-box binding protein 1 XBP1, Insulinoma-associated 1 INSM1, and Zinc finger protein 263 ZNF263) were identified as the transcriptional regulators of TORC2 gene. These findings were further confirmed through Electrophoretic Mobility Shift Assay (EMSA) within nuclear extracts of bovine adipocytes. Furthermore, we also identified that C/EBP, XBP1, INSM1 and ZNF263 regulate TORC2 gene as activators in the promoter region. We can conclude that TORC2 gene is potentially a positive regulator of adipogenesis. These findings will not only provide an insight for the improvement of intramuscular fat in cattle, but will enhance our understanding regarding therapeutic intervention of metabolic syndrome and obesity in public health as well.


Assuntos
Adipócitos/metabolismo , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Adipócitos/citologia , Adipogenia , Animais , Proteínas Estimuladoras de Ligação a CCAAT/genética , Bovinos , Células Cultivadas , Regulação da Expressão Gênica no Desenvolvimento , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Regiões Promotoras Genéticas , Ativação Transcricional , Transcriptoma
2.
Nat Immunol ; 20(9): 1208-1219, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31384057

RESUMO

Regulatory T cells (Treg cells) deficient in the transcription factor Foxp3 lack suppressor function and manifest an effector T (Teff) cell-like phenotype. We demonstrate that Foxp3 deficiency dysregulates metabolic checkpoint kinase mammalian target of rapamycin (mTOR) complex 2 (mTORC2) signaling and gives rise to augmented aerobic glycolysis and oxidative phosphorylation. Specific deletion of the mTORC2 adaptor gene Rictor in Foxp3-deficient Treg cells ameliorated disease in a Foxo1 transcription factor-dependent manner. Rictor deficiency re-established a subset of Treg cell genetic circuits and suppressed the Teff cell-like glycolytic and respiratory programs, which contributed to immune dysregulation. Treatment of Treg cells from patients with FOXP3 deficiency with mTOR inhibitors similarly antagonized their Teff cell-like program and restored suppressive function. Thus, regulatory function can be re-established in Foxp3-deficient Treg cells by targeting their metabolic pathways, providing opportunities to restore tolerance in Treg cell disorders.


Assuntos
Reprogramação Celular/imunologia , Fatores de Transcrição Forkhead/genética , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteína Companheira de mTOR Insensível à Rapamicina/genética , Linfócitos T Reguladores/imunologia , Animais , Células Cultivadas , Feminino , Regulação da Expressão Gênica , Glicólise/fisiologia , Humanos , Masculino , Alvo Mecanístico do Complexo 2 de Rapamicina/antagonistas & inibidores , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação Oxidativa , Transdução de Sinais , Linfócitos T Reguladores/citologia
3.
Nat Commun ; 10(1): 3622, 2019 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-31399584

RESUMO

Caspase-2 is the most evolutionarily conserved member in the caspase family of proteases and is constitutively expressed in most cell types including neurons; however, its physiological function remains largely unknown. Here we report that caspase-2 plays a critical role in synaptic plasticity and cognitive flexibility. We found that caspase-2 deficiency led to deficits in dendritic spine pruning, internalization of AMPA receptors and long-term depression. Our results indicate that caspase-2 degrades Rictor, a key mTOR complex 2 (mTORC2) component, to inhibit Akt activation, which leads to enhancement of the GSK3ß activity and thereby long-term depression. Furthermore, we found that mice lacking caspase-2 displayed elevated levels of anxiety, impairment in reversal water maze learning, and little memory loss over time. These results not only uncover a caspase-2-mTORC2-Akt-GSK3ß signaling pathway, but also suggest that caspase-2 is important for memory erasing and normal behaviors by regulating synaptic number and transmission.


Assuntos
Caspase 2/metabolismo , Cognição/fisiologia , Glicogênio Sintase Quinase 3 beta/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de AMPA/metabolismo , Transdução de Sinais/fisiologia , Animais , Ansiedade , Comportamento Animal , Proteínas de Transporte/metabolismo , Caspase 2/genética , Espinhas Dendríticas/genética , Espinhas Dendríticas/metabolismo , Hipocampo/metabolismo , Depressão Sináptica de Longo Prazo/genética , Depressão Sináptica de Longo Prazo/fisiologia , Masculino , Aprendizagem em Labirinto , Transtornos da Memória/metabolismo , Camundongos , Camundongos Knockout , Plasticidade Neuronal , Neurônios/metabolismo , Receptores de Glutamato/metabolismo
4.
Chem Biol Interact ; 311: 108795, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31419397

RESUMO

Citreoviridin (CIT), a mycotoxin and ATP synthase inhibitor, is regarded as one of aetiology factors of cardiac beriberi and Keshan disease. Thiamine (VB1) and selenium (Se) improve the recovery of these two diseases respectively. The underlying mechanisms of cardiotoxic effect of CIT and cardioprotective effect of VB1 and Se have not been fully elucidated. In this study, we found that ectopic ATP synthase was more sensitive to CIT treatment than mitochondrial ATP synthase in H9c2 cardiomyocytes. CIT inhibited the transcriptional activity of peroxisome proliferator activated receptor gamma (PPAR-γ) in mice hearts and H9c2 cells. PPAR-γ agonist attenuated the inhibitory effect of CIT on mechanistic target of rapamycin complex 2 (mTORC2) and stimulatory effect of CIT on autophagy in cardiomyocytes. CIT induced apoptosis through lysosomal-mitochondrial axis in cardiomyocytes. PPAR-γ agonist and autophagy inhibitor alleviated CIT-induced apoptosis and accelerated cardiac biomarker. VB1 and Se accelerated the basal transcriptional activity of PPAR-γ in mice hearts and H9c2 cells. Furthermore, VB1 and Se reversed the effect of CIT on PPAR-γ, autophagy and apoptosis. Our findings defined PPAR-γ-mTORC2-autophagy pathway as the key link between CIT cardiotoxicity and cardioprotective effect of VB1 and Se. The present study would shed new light on the pathogenesis of cardiomyopathy and the cardioprotective mechanism of micronutrients.


Assuntos
Apoptose/efeitos dos fármacos , Aurovertinas/farmacologia , Autofagia/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Selênio/farmacologia , Tiamina/farmacologia , Animais , Aquaporinas/genética , Aquaporinas/metabolismo , Peso Corporal/efeitos dos fármacos , Linhagem Celular , Masculino , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Miocárdio/metabolismo , Miocárdio/patologia , PPAR gama/agonistas , PPAR gama/genética , PPAR gama/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Proteína X Associada a bcl-2/metabolismo
5.
Adv Exp Med Biol ; 1152: 283-292, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31456190

RESUMO

Based on the insights gleaned from decades of research, it seems clear that mechanistic target of rapamycin (mTOR) is an essential signaling node that integrates environmental clues for regulation of cell survival, metabolism and proliferation of the cells. However, overwhelmingly increasing scientific evidence has added a new layer of intricacy to already complicated and versatile signaling pathway of mTOR. Deregulation of spatio-temporally controlled mTOR-driven pathway played contributory role in breast cancer development and progression. Pharmacologists and molecular biologists have specifically emphasized on the identification and development of mTOR-pathway inhibitors. In this chapter we have attempted to provide an overview of the most recent findings related to therapeutic targeting of mTOR-associated mTORC1 and mTORC2 in breast cancer. We have also comprehensively summarized regulation of mTOR and its partners by microRNAs in breast cancer.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Feminino , Humanos , MicroRNAs/genética , Terapia de Alvo Molecular , Metástase Neoplásica
6.
Mol Cell ; 75(4): 807-822.e8, 2019 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-31442424

RESUMO

mTORC2 controls glucose and lipid metabolism, but the mechanisms are unclear. Here, we show that conditionally deleting the essential mTORC2 subunit Rictor in murine brown adipocytes inhibits de novo lipid synthesis, promotes lipid catabolism and thermogenesis, and protects against diet-induced obesity and hepatic steatosis. AKT kinases are the canonical mTORC2 substrates; however, deleting Rictor in brown adipocytes appears to drive lipid catabolism by promoting FoxO1 deacetylation independently of AKT, and in a pathway distinct from its positive role in anabolic lipid synthesis. This facilitates FoxO1 nuclear retention, enhances lipid uptake and lipolysis, and potentiates UCP1 expression. We provide evidence that SIRT6 is the FoxO1 deacetylase suppressed by mTORC2 and show an endogenous interaction between SIRT6 and mTORC2 in both mouse and human cells. Our findings suggest a new paradigm of mTORC2 function filling an important gap in our understanding of this more mysterious mTOR complex.


Assuntos
Adipócitos Marrons/metabolismo , Proteína Forkhead Box O1/metabolismo , Lipólise , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Sirtuínas/metabolismo , Adipócitos Marrons/citologia , Animais , Proteína Forkhead Box O1/genética , Células HEK293 , Células HeLa , Humanos , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Camundongos , Camundongos Transgênicos , Proteína Companheira de mTOR Insensível à Rapamicina/genética , Proteína Companheira de mTOR Insensível à Rapamicina/metabolismo , Sirtuínas/genética
7.
Nat Cell Biol ; 21(9): 1093-1101, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31451768

RESUMO

Mechanistic target of rapamycin (mTOR) kinase functions in two multiprotein complexes: lysosomal mTOR complex 1 (mTORC1) and mTORC2 at the plasma membrane. mTORC1 modulates the cell response to growth factors and nutrients by increasing protein synthesis and cell growth, and repressing the autophagy-lysosomal pathway1-4; however, dysfunction in mTORC1 is implicated in various diseases3,5,6. mTORC1 activity is regulated by phosphoinositide lipids7-10. Class I phosphatidylinositol-3-kinase (PI3K)-mediated production of phosphatidylinositol-3,4,5-trisphosphate6,11 at the plasma membrane stimulates mTORC1 signalling, while local synthesis of phosphatidylinositol-3,4-bisphosphate by starvation-induced recruitment of class II PI3K-ß (PI3KC2-ß) to lysosomes represses mTORC1 activity12. How the localization and activity of PI3KC2-ß are regulated by mitogens is unknown. We demonstrate that protein kinase N (PKN) facilitates mTORC1 signalling by repressing PI3KC2-ß-mediated phosphatidylinositol-3,4-bisphosphate synthesis downstream of mTORC2. Active PKN2 phosphorylates PI3KC2-ß to trigger PI3KC2-ß complex formation with inhibitory 14-3-3 proteins. Conversely, loss of PKN2 or inactivation of its target phosphorylation site in PI3KC2-ß represses nutrient signalling via mTORC1. These results uncover a mechanism that couples mTORC2-dependent activation of PKN2 to the regulation of mTORC1-mediated nutrient signalling by local lipid signals.


Assuntos
Lipídeos , Lisossomos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Transdução de Sinais/fisiologia , Proliferação de Células/fisiologia , Fibroblastos/metabolismo , Humanos , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Complexos Multiproteicos/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Serina-Treonina Quinases TOR/metabolismo
8.
Life Sci ; 232: 116665, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31323273

RESUMO

AIMS: Overexpression of the mechanistic target of rapamycin (mTOR), a member of the PIKK (phosphoinositide kinase-related kinase) family, protects cardiomyocytes from cell death induced by pathological stimuli such as ischemia. We previously reported that posttranslational modification of mTOR plays an important role in regulating cardiac mTOR expression. The aim of this study was to see if Tel2 (telomere maintenance 2), a protein that regulates the abundance of PIKKs, confers similar cardioprotective effects as mTOR. Tel2 is not well-characterized in cardiomyocytes, therefore we examined the effects of Tel2 on cardiomyocyte viability under ischemic stress conditions. MATERIALS AND METHODS: We overexpressed Tel2 or silenced Tel2 with siRNA in the HL-1 cardiomyocyte cell line to survey the effects of Tel2 overexpression and downregulation on cell survival during hypoxia. Adult mouse cardiomyocytes transfected with Tel2 adenoviruses were used to test whether Tel2 sufficiently prevented cardiomyocyte cell death against hydrogen peroxide (H2O2). KEY FINDINGS: Overexpressing Tel2 increased mTOR expression with a concomitant increase in mTOR Complex 1 (mTORC1) and mTORC2 activity in HL-1 cells. Tel2 deletion decreased mTOR expression, and mTORC1 and mTORC2 activity accordingly. In both HL-1 cells and adult mouse cardiomyocytes, Tel2 overexpression protected cardiomyocytes under ischemic stress. These effects were mTOR-dependent, as mTOR inhibitors blunted the effects of Tel2. While gene silencing of Tel2 did not affect cell survival under normoxia, Tel2 silencing made cardiomyocytes more vulnerable to cell death under hypoxia. SIGNIFICANCE: Upregulating Tel2 expression increases mTOR-mediated cardiomyocyte survival and targeting Tel2 could be another therapeutic strategy against ischemic heart disease.


Assuntos
Sobrevivência Celular/fisiologia , Miócitos Cardíacos/citologia , Proteínas de Ligação a Telômeros/fisiologia , Adenoviridae/genética , Animais , Morte Celular/efeitos dos fármacos , Linhagem Celular , Inativação Gênica , Peróxido de Hidrogênio/farmacologia , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Camundongos , Transdução de Sinais , Proteínas de Ligação a Telômeros/genética , Transfecção
9.
Nat Cell Biol ; 21(7): 867-878, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31263268

RESUMO

mTORC2 plays critical roles in metabolism, cell survival and actin cytoskeletal dynamics through the phosphorylation of AKT. Despite its importance to biology and medicine, it is unclear how mTORC2-mediated AKT phosphorylation is controlled. Here, we identify an unforeseen principle by which a GDP-bound form of the conserved small G protein Rho GTPase directly activates mTORC2 in AKT phosphorylation in social amoebae (Dictyostelium discoideum) cells. Using biochemical reconstitution with purified proteins, we demonstrate that Rho-GDP promotes AKT phosphorylation by assembling a supercomplex with Ras-GTP and mTORC2. This supercomplex formation is controlled by the chemoattractant-induced phosphorylation of Rho-GDP at S192 by GSK-3. Furthermore, Rho-GDP rescues defects in both mTORC2-mediated AKT phosphorylation and directed cell migration in Rho-null cells in a manner dependent on phosphorylation of S192. Thus, in contrast to the prevailing view that the GDP-bound forms of G proteins are inactive, our study reveals that mTORC2-AKT signalling is activated by Rho-GDP.


Assuntos
Movimento Celular/fisiologia , Dimerização , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Citoesqueleto/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Guanosina Difosfato/metabolismo , Humanos , Fosforilação/fisiologia
10.
Biomed Res Int ; 2019: 5196028, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31223619

RESUMO

The mechanistic target of rapamycin complex 2 (mTORC2) primarily functions as an effector of insulin/PI3K signaling to regulate cell proliferation and is associated with cell metabolism. However, the function of mTORC2 in lipid metabolism is not well understood. In the present study, mTORC2 was inactivated by the ATP-competitive mTOR inhibitor AZD8055 or shRNA targeting RICTOR in primary bovine mammary epithelial cells (pBMECs). MTT assay was performed to examine the effect of AZD8055 on cell proliferation. ELISA assay and GC-MS analysis were used to determine the content of lipid. The mRNA and protein expression levels were investigated by RT/real-time PCR and western blot analysis, respectively. We found that cell proliferation, mTORC2 activation, and lipid secretion were inhibited by AZD8055. RICTOR was knocked down and mTORC2 activation was specifically attenuated by the shRNA. Compared to control cells, the expression of the transcription factor gene PPARG and the lipogenic genes LPIN1, DGAT1, ACACA, and FASN was downregulated in RICTOR silencing cells. As a result, the content of intracellular triacylglycerol (TAG), palmitic acid (PA), docosahexaenoic acid (DHA), and other 16 types of fatty acid was decreased in the treated cells; the accumulation of TAG, PA, and DHA in cell culture medium was also reduced. Overall, mTORC2 plays a critical role in regulating lipogenic gene expression, lipid synthesis, and secretion in pBMECs, and this process probably is through PPARγ. This finding provides a model by which lipogenesis is regulated in pBMECs.


Assuntos
Células Epiteliais/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Lipogênese/fisiologia , Glândulas Mamárias Animais/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , PPAR gama/metabolismo , Acetil-CoA Carboxilase/biossíntese , Animais , Bovinos , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Diacilglicerol O-Aciltransferase/biossíntese , Ácido Graxo Sintase Tipo I/biossíntese , Feminino , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Lipogênese/efeitos dos fármacos , Morfolinas/farmacologia , PPAR gama/antagonistas & inibidores , Fosfatidato Fosfatase/biossíntese , Proteína Companheira de mTOR Insensível à Rapamicina/antagonistas & inibidores , Proteína Companheira de mTOR Insensível à Rapamicina/metabolismo
11.
Mol Cell ; 75(1): 26-38.e3, 2019 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-31130364

RESUMO

Growth factor signaling is initiated at the plasma membrane and propagated through the cytoplasm for eventual relay to intracellular organelles such as lysosomes. The serine/threonine kinase mTOR participates in growth factor signaling as a component of two multi-subunit complexes, mTORC1 and mTORC2. mTORC1 associates with lysosomes, and its activity depends on the positioning of lysosomes within the cytoplasm, although there is no consensus regarding the exact effect of perinuclear versus peripheral distribution. mTORC2 and its substrate kinase AKT have a widespread distribution, but they are thought to act mainly at the plasma membrane. Using cell lines with knockout of components of the lysosome-positioning machinery, we show that perinuclear clustering of lysosomes delays reactivation of not only mTORC1, but also mTORC2 and AKT upon serum replenishment. These experiments demonstrate the existence of pools of mTORC2 and AKT that are sensitive to lysosome positioning.


Assuntos
Núcleo Celular/metabolismo , Lisossomos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Proteínas Proto-Oncogênicas c-akt/genética , Fatores de Ribosilação do ADP/deficiência , Fatores de Ribosilação do ADP/genética , Sistemas CRISPR-Cas , Núcleo Celular/ultraestrutura , Meios de Cultura Livres de Soro , Endossomos/metabolismo , Endossomos/ultraestrutura , Edição de Genes , Regulação da Expressão Gênica , Células HEK293 , Células HeLa , Humanos , Cinesina/deficiência , Cinesina/genética , Lisossomos/ultraestrutura , Fatores de Transcrição MEF2/deficiência , Fatores de Transcrição MEF2/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais
12.
Cell Physiol Biochem ; 52(4): 758-768, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30933440

RESUMO

BACKGROUND/AIMS: Bromodomain-containing protein 4 (BRD4) and phosphatidylinositol 3-kinase (PI3K) are key oncogenic cascades in colorectal cancer (CRC). SF1126 is a novel and potent PI3K-BRD4 dual inhibitor. METHODS: CRC cells and human colon epithelial cells were treated with SF1126. Cell survival was tested by MTT and soft agar colony formation assays. Cell proliferation was tested by BrdU ELISA method. Cell apoptosis was tested by a TUNEL staining method and Histone DNA ELISA. Western blotting was utilized to test the signaling proteins. A HT-29 xenograft mice model was established to study the anti-tumor activity of SF1126 in vivo. RESULTS: SF1126 potently inhibited the survival, proliferation, and progression of the cell cycle in an established CRC cell line (HT-29) and primary human colon cancer cells. Significant activation of apoptosis was detected in SF1126-treated CRC cells. In CRC cells, SF1126 blocked Akt-mammalian target of rapamycin (mTOR) complex1/2 signaling and downregulated BRD4 target proteins (Myc and cyclin D1). Further studies showed that SF1126 activated p38 signaling in CRC cells. In contrast, the p38 inhibitors or p38 short hairpin RNA inhibited SF1126-induced cytotoxicity and apoptosis in CRC cells. In vivo, subcutaneous administration of SF1126 significantly inhibited HT-29 xenograft tumor growth in nude mice. CONCLUSION: SF1126 inhibits CRC cell growth possibly by targeting PI3K-Akt-mTOR, BRD4, and p38 signaling.


Assuntos
Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cromonas/farmacologia , Proteínas Nucleares/antagonistas & inibidores , Oligopeptídeos/farmacologia , Fatores de Transcrição/antagonistas & inibidores , Animais , Apoptose/efeitos dos fármacos , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Cromonas/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Camundongos , Camundongos Nus , Proteína Quinase 14 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 14 Ativada por Mitógeno/genética , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Proteínas Nucleares/metabolismo , Oligopeptídeos/uso terapêutico , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de Transcrição/metabolismo , Transplante Heterólogo
13.
PLoS One ; 14(4): e0215871, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31002704

RESUMO

Tubule-interstitial injury (TII) is a critical step in the progression of renal disease. It has been proposed that changes in proximal tubule (PT) albumin endocytosis plays an important role in the development of TII. Some reports have shown protective effects of lithium on kidney injury animal models that was correlated to proteinuria. We tested the hypothesis that lithium treatment ameliorates the development of TII due to changes in albumin endocytosis. Two experimental models were used: (1) TII induced by albumin overload in an animal model; (2) LLC-PK1 cells, a PT cell line. Lithium treatment ameliorates TII induced by albumin overload measured by (1) proteinuria; (2) collagen deposition; (3) area of tubule-interstitial space, and (4) macrophage infiltration. Lithium treatment increased mTORC2 activity leading to the phosphorylation of protein kinase B (PKB) at Ser473 and its activation. This mechanism enhanced albumin endocytosis in PT cells, which decreased the proteinuria observed in TII induced by albumin overload. This effect did not involve changes in the expression of megalin, a PT albumin receptor. In addition, activation of this pathway decreased apoptosis in LLC-PK1 cells, a PT cell line, induced by higher albumin concentration, similar to that found in pathophysiologic conditions. Our results indicate that the protective role of lithium treatment on TII induced by albumin overload involves an increase in PT albumin endocytosis due to activation of the mTORC2/PKB pathway. These results open new possibilities in understanding the effects of lithium on the progression of renal disease.


Assuntos
Túbulos Renais Proximais/efeitos dos fármacos , Carbonato de Lítio/farmacologia , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Substâncias Protetoras/farmacologia , Proteinúria/tratamento farmacológico , Proteínas Proto-Oncogênicas c-akt/genética , Albuminas/metabolismo , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Endocitose/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Regulação da Expressão Gênica , Humanos , Túbulos Renais Proximais/lesões , Túbulos Renais Proximais/metabolismo , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Alvo Mecanístico do Complexo 2 de Rapamicina/agonistas , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Proteinúria/metabolismo , Proteinúria/fisiopatologia , Proteínas Proto-Oncogênicas c-akt/agonistas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos
14.
Mol Biol Cell ; 30(12): 1555-1574, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30969890

RESUMO

Eukaryotic cell survival requires maintenance of plasma membrane (PM) homeostasis in response to environmental insults and changes in lipid metabolism. In yeast, a key regulator of PM homeostasis is target of rapamycin (TOR) complex 2 (TORC2), a multiprotein complex containing the evolutionarily conserved TOR protein kinase isoform Tor2. PM localization is essential for TORC2 function. One core TORC2 subunit (Avo1) and two TORC2--associated regulators (Slm1 and Slm2) contain pleckstrin homology (PH) domains that exhibit specificity for binding phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P2). To investigate the roles of PtdIns4,5P2 and constituent subunits of TORC2, we used auxin-inducible degradation to systematically eliminate these factors and then examined localization, association, and function of the remaining TORC2 components. We found that PtdIns4,5P2 depletion significantly reduced TORC2 activity, yet did not prevent PM localization or disassembly of TORC2. Moreover, truncated Avo1 (lacking its C-terminal PH domain) was still recruited to the PM and supported growth. Even when all three PH-containing proteins were absent, the remaining TORC2 subunits were PM-bound. Revealingly, Avo3 localized to the PM independent of both Avo1 and Tor2, whereas both Tor2 and Avo1 required Avo3 for their PM anchoring. Our findings provide new mechanistic information about TORC2 and pinpoint Avo3 as pivotal for TORC2 PM localization and assembly in vivo.


Assuntos
Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismo , Subunidades Proteicas/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas do Domínio Armadillo/química , Proteínas do Domínio Armadillo/metabolismo , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Membrana Celular/metabolismo , Domínios Proteicos , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo
15.
Mol Cell Biochem ; 457(1-2): 157-168, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30879206

RESUMO

Caffeine is commonly used in Dictyostelium to inhibit the synthesis of the chemoattractant cAMP and, therefore, its secretion and the autocrine stimulation of cells, in order to prevent its interference with the study of chemoattractant-induced responses. However, the mechanism through which caffeine inhibits cAMP synthesis in Dictyostelium has not been characterized. Here, we report the effects of caffeine on the cAMP chemoattractant signaling network. We found that caffeine inhibits phosphatidylinositol 3-kinase (PI3K) and mechanistic target of rapamycin complex 2 (mTORC2). Both PI3K and mTORC2 are essential for the chemoattractant-stimulated cAMP production, thereby providing a mechanism for the caffeine-mediated inhibition of cAMP synthesis. Our results also reveal that caffeine treatment of cells leads to an increase in cAMP-induced RasG and Rap1 activation, and inhibition of the PKA, cGMP, MyoII, and ERK1 responses. Finally, we observed that caffeine has opposite effects on F-actin and ERK2 depending on the assay and Dictyostelium strain used, respectively. Altogether, our findings reveal that caffeine considerably affects the cAMP-induced chemotactic signaling pathways in Dictyostelium, most likely acting through multiple targets that include PI3K and mTORC2.


Assuntos
Cafeína/farmacologia , Quimiotaxia/efeitos dos fármacos , AMP Cíclico/metabolismo , Dictyostelium/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas de Protozoários/metabolismo , Sistemas do Segundo Mensageiro/efeitos dos fármacos
16.
J Biol Chem ; 294(17): 6831-6842, 2019 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-30858178

RESUMO

Mitochondria are major sites of energy metabolism that influence numerous cellular events, including immunity and cancer development. Previously, we reported that the mitochondrion-specific antioxidant enzyme, manganese-containing superoxide dismutase (MnSOD), has dual roles in early- and late-carcinogenesis stages. However, how defective MnSOD impacts the chain of events that lead to cell transformation in pathologically normal epidermal cells that have been exposed to carcinogens is unknown. Here, we show that UVB radiation causes nitration and inactivation of MnSOD leading to mitochondrial injury and mitophagy. In keratinocytes, exposure to UVB radiation decreased mitochondrial oxidative phosphorylation, increased glycolysis and the expression of autophagy-related genes, and enhanced AKT Ser/Thr kinase (AKT) phosphorylation and cell growth. Interestingly, UVB initiated a prosurvival mitophagy response by mitochondria-mediated reactive oxygen species (ROS) signaling via the mammalian target of the mTOR complex 2 (mTORC2) pathway. Knockdown of rictor but not raptor abrogated UVB-induced mitophagy responses. Furthermore, fractionation and proximity-ligation assays reveal that ROS-mediated mTOC2 activation in mitochondria is necessary for UVB-induced mitophagy. Importantly, pretreatment with the MnSOD mimic MnTnBuOE-2-PyP5+ (MnP) attenuates mTORC2 activation and suppresses UVB-induced mitophagy. UVB radiation exposure also increased cell growth as assessed by soft-agar colony survival and cell growth assays, and pretreatment with MnP or the known autophagy inhibitor 3-methyladenine abrogated UVB-induced cell growth. These results indicate that MnSOD is a major redox regulator that maintains mitochondrial health and show that UVB-mediated MnSOD inactivation promotes mitophagy and thereby prevents accumulation of damaged mitochondria.


Assuntos
Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/antagonistas & inibidores , Raios Ultravioleta , Animais , Autofagia/fisiologia , Linhagem Celular , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Nitratos/metabolismo , Oxirredução , Proteína Companheira de mTOR Insensível à Rapamicina/fisiologia , Proteína Regulatória Associada a mTOR/fisiologia
17.
Nat Commun ; 10(1): 632, 2019 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-30733432

RESUMO

To reveal how cells exit human pluripotency, we designed a CRISPR-Cas9 screen exploiting the metabolic and epigenetic differences between naïve and primed pluripotent cells. We identify the tumor suppressor, Folliculin(FLCN) as a critical gene required for the exit from human pluripotency. Here we show that FLCN Knock-out (KO) hESCs maintain the naïve pluripotent state but cannot exit the state since the critical transcription factor TFE3 remains active in the nucleus. TFE3 targets up-regulated in FLCN KO exit assay are members of Wnt pathway and ESRRB. Treatment of FLCN KO hESC with a Wnt inhibitor, but not ESRRB/FLCN double mutant, rescues the cells, allowing the exit from the naïve state. Using co-immunoprecipitation and mass spectrometry analysis we identify unique FLCN binding partners. The interactions of FLCN with components of the mTOR pathway (mTORC1 and mTORC2) reveal a mechanism of FLCN function during exit from naïve pluripotency.


Assuntos
Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Via de Sinalização Wnt/fisiologia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Sistemas CRISPR-Cas/genética , Sistemas CRISPR-Cas/fisiologia , Linhagem Celular , Estrona/genética , Estrona/metabolismo , Humanos , Imunoprecipitação , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Proteômica , Receptores Estrogênicos/genética , Receptores Estrogênicos/metabolismo , Via de Sinalização Wnt/genética
18.
mBio ; 10(1)2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30755508

RESUMO

Hypoxia is linked to therapeutic resistance and poor clinical prognosis for many tumor entities, including human papillomavirus (HPV)-positive cancers. Notably, HPV-positive cancer cells can induce a dormant state under hypoxia, characterized by a reversible growth arrest and strong repression of viral E6/E7 oncogene expression, which could contribute to therapy resistance, immune evasion and tumor recurrence. The present work aimed to gain mechanistic insights into the pathway(s) underlying HPV oncogene repression under hypoxia. We show that E6/E7 downregulation is mediated by hypoxia-induced stimulation of AKT signaling. Ablating AKT function in hypoxic HPV-positive cancer cells by using chemical inhibitors efficiently counteracts E6/E7 repression. Isoform-specific activation or downregulation of AKT1 and AKT2 reveals that both AKT isoforms contribute to hypoxic E6/E7 repression and act in a functionally redundant manner. Hypoxic AKT activation and consecutive E6/E7 repression is dependent on the activities of the canonical upstream AKT regulators phosphoinositide 3-kinase (PI3K) and mechanistic target of rapamycin (mTOR) complex 2 (mTORC2). Hypoxic downregulation of E6/E7 occurs, at least in part, at the transcriptional level. Modulation of E6/E7 expression by the PI3K/mTORC2/AKT cascade is hypoxia specific and not observed in normoxic HPV-positive cancer cells. Quantitative proteome analyses identify additional factors as candidates to be involved in hypoxia-induced activation of the PI3K/mTORC2/AKT signaling cascade and in the AKT-dependent repression of the E6/E7 oncogenes under hypoxia. Collectively, these data uncover a functional key role of the PI3K/mTORC2/AKT signaling cascade for viral oncogene repression in hypoxic HPV-positive cancer cells and provide new insights into the poorly understood cross talk between oncogenic HPVs and their host cells under hypoxia.IMPORTANCE Oncogenic HPV types are major human carcinogens. Under hypoxia, HPV-positive cancer cells can repress the viral E6/E7 oncogenes and induce a reversible growth arrest. This response could contribute to therapy resistance, immune evasion, and tumor recurrence upon reoxygenation. Here, we uncover evidence that HPV oncogene repression is mediated by hypoxia-induced activation of canonical PI3K/mTORC2/AKT signaling. AKT-dependent downregulation of E6/E7 is only observed under hypoxia and occurs, at least in part, at the transcriptional level. Quantitative proteome analyses identify additional factors as candidates to be involved in AKT-dependent E6/E7 repression and/or hypoxic PI3K/mTORC2/AKT activation. These results connect PI3K/mTORC2/AKT signaling with HPV oncogene regulation, providing new mechanistic insights into the cross talk between oncogenic HPVs and their host cells.


Assuntos
Hipóxia , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteínas Oncogênicas Virais/biossíntese , Papillomaviridae/fisiologia , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Linhagem Celular Tumoral , Regulação para Baixo , Interações Hospedeiro-Patógeno , Humanos
19.
Cells ; 8(2)2019 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-30795552

RESUMO

Acute Lymphoblastic Leukemia (ALL) is an aggressive hematologic disorder and constitutes approximately 25% of cancer diagnoses among children and teenagers. Pediatric patients have a favourable prognosis, with 5-years overall survival rates near 90%, while adult ALL still correlates with poorer survival. However, during the past few decades, the therapeutic outcome of adult ALL was significantly ameliorated, mainly due to intensive pediatric-based protocols of chemotherapy. Mammalian (or mechanistic) target of rapamycin (mTOR) is a conserved serine/threonine kinase belonging to the phosphatidylinositol 3-kinase (PI3K)-related kinase family (PIKK) and resides in two distinct signalling complexes named mTORC1, involved in mRNA translation and protein synthesis and mTORC2 that controls cell survival and migration. Moreover, both complexes are remarkably involved in metabolism regulation. Growing evidence reports that mTOR dysregulation is related to metastatic potential, cell proliferation and angiogenesis and given that PI3K/Akt/mTOR network activation is often associated with poor prognosis and chemoresistance in ALL, there is a constant need to discover novel inhibitors for ALL treatment. Here, the current knowledge of mTOR signalling and the development of anti-mTOR compounds are documented, reporting the most relevant results from both preclinical and clinical studies in ALL that have contributed significantly into their efficacy or failure.


Assuntos
Terapia de Alvo Molecular , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Serina-Treonina Quinases TOR/antagonistas & inibidores , Ensaios Clínicos como Assunto , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Serina-Treonina Quinases TOR/metabolismo
20.
Mol Cell ; 73(4): 830-844.e12, 2019 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-30639242

RESUMO

Proximity-dependent biotin labeling (BioID) may identify new targets for cancers driven by difficult-to-drug oncogenes such as Ras. Therefore, BioID was used with wild-type (WT) and oncogenic mutant (MT) H-, K-, and N-Ras, identifying known interactors, including Raf and PI3K, as well as a common set of 130 novel proteins proximal to all Ras isoforms. A CRISPR screen of these proteins for Ras dependence identified mTOR, which was also found proximal to MT Ras in human tumors. Oncogenic Ras directly bound two mTOR complex 2 (mTORC2) components, mTOR and MAPKAP1, to promote mTORC2 kinase activity at the plasma membrane. mTORC2 enabled the Ras pro-proliferative cell cycle transcriptional program, and perturbing the Ras-mTORC2 interaction impaired Ras-dependent neoplasia in vivo. Combining proximity-dependent proteomics with CRISPR screening identified a new set of functional Ras-associated proteins, defined mTORC2 as a new direct Ras effector, and offers a strategy for finding new proteins that cooperate with dominant oncogenes.


Assuntos
Transformação Celular Neoplásica/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Neoplasias/metabolismo , Proteoma , Proteínas ras/metabolismo , Animais , Sítios de Ligação , Sistemas CRISPR-Cas , Células CACO-2 , Pontos de Checagem do Ciclo Celular , Proliferação de Células , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Humanos , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Camundongos Pelados , Camundongos SCID , Camundongos Transgênicos , Mutação , Neoplasias/genética , Neoplasias/patologia , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteômica/métodos , Carga Tumoral , Proteínas ras/genética
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