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Maiese K. Novel nervous and multi-system regenerative therapeutic strategies for diabetes mellitus with mTOR. Neural Regen Res 2016; 11:372-85. [PMID: 27127460 PMCID: PMC4828986 DOI: 10.4103/1673-5374.179032] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Throughout the globe, diabetes mellitus (DM) is increasing in incidence with limited therapies presently available to prevent or resolve the significant complications of this disorder. DM impacts multiple organs and affects all components of the central and peripheral nervous systems that can range from dementia to diabetic neuropathy. The mechanistic target of rapamycin (mTOR) is a promising agent for the development of novel regenerative strategies for the treatment of DM. mTOR and its related signaling pathways impact multiple metabolic parameters that include cellular metabolic homeostasis, insulin resistance, insulin secretion, stem cell proliferation and differentiation, pancreatic β-cell function, and programmed cell death with apoptosis and autophagy. mTOR is central element for the protein complexes mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) and is a critical component for a number of signaling pathways that involve phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), AMP activated protein kinase (AMPK), silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), Wnt1 inducible signaling pathway protein 1 (WISP1), and growth factors. As a result, mTOR represents an exciting target to offer new clinical avenues for the treatment of DM and the complications of this disease. Future studies directed to elucidate the delicate balance mTOR holds over cellular metabolism and the impact of its broad signaling pathways should foster the translation of these targets into effective clinical regimens for DM.
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Demetriades C, Plescher M, Teleman AA. Lysosomal recruitment of TSC2 is a universal response to cellular stress. Nat Commun 2016; 7:10662. [PMID: 26868506 PMCID: PMC4754342 DOI: 10.1038/ncomms10662] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 01/08/2016] [Indexed: 02/06/2023] Open
Abstract
mTORC1 promotes cell growth and is therefore inactivated upon unfavourable growth conditions. Signalling pathways downstream of most cellular stresses converge on TSC1/2, which serves as an integration point that inhibits mTORC1. The TSC1/2 complex was shown to translocate to lysosomes to inactivate mTORC1 in response to two stresses: amino-acid starvation and growth factor removal. Whether other stresses also regulate TSC2 localization is not known. How TSC2 localization responds to combinations of stresses and other stimuli is also unknown. We show that both amino acids and growth factors are required simultaneously to maintain TSC2 cytoplasmic; when one of the two is missing, TSC2 relocalizes to lysosomes. Furthermore, multiple different stresses that inhibit mTORC1 also drive TSC2 lysosomal accumulation. Our findings indicate that lysosomal recruitment of TSC2 is a universal response to stimuli that inactivate mTORC1, and that the presence of any single stress is sufficient to cause TSC2 lysosomal localization.
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Affiliation(s)
- Constantinos Demetriades
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Monika Plescher
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Aurelio A. Teleman
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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103
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Carroll B, Maetzel D, Maddocks ODK, Otten G, Ratcliff M, Smith GR, Dunlop EA, Passos JF, Davies OR, Jaenisch R, Tee AR, Sarkar S, Korolchuk VI. Control of TSC2-Rheb signaling axis by arginine regulates mTORC1 activity. eLife 2016; 5:e11058. [PMID: 26742086 PMCID: PMC4764560 DOI: 10.7554/elife.11058] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/30/2015] [Indexed: 01/07/2023] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is the key signaling hub that regulates cellular protein homeostasis, growth, and proliferation in health and disease. As a prerequisite for activation of mTORC1 by hormones and mitogens, there first has to be an available pool of intracellular amino acids. Arginine, an amino acid essential during mammalian embryogenesis and early development is one of the key activators of mTORC1. Herein, we demonstrate that arginine acts independently of its metabolism to allow maximal activation of mTORC1 by growth factors via a mechanism that does not involve regulation of mTORC1 localization to lysosomes. Instead, arginine specifically suppresses lysosomal localization of the TSC complex and interaction with its target small GTPase protein, Rheb. By interfering with TSC-Rheb complex, arginine relieves allosteric inhibition of Rheb by TSC. Arginine cooperates with growth factor signaling which further promotes dissociation of TSC2 from lysosomes and activation of mTORC1. Arginine is the main amino acid sensed by the mTORC1 pathway in several cell types including human embryonic stem cells (hESCs). Dependence on arginine is maintained once hESCs are differentiated to fibroblasts, neurons, and hepatocytes, highlighting the fundamental importance of arginine-sensing to mTORC1 signaling. Together, our data provide evidence that different growth promoting cues cooperate to a greater extent than previously recognized to achieve tight spatial and temporal regulation of mTORC1 signaling.
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Affiliation(s)
- Bernadette Carroll
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Dorothea Maetzel
- Whitehead Institute for Biomedical ResearchMassachusetts Institute of TechnologyCambridgeUnited States
| | | | - Gisela Otten
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Matthew Ratcliff
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Graham R Smith
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Elaine A Dunlop
- Institute of Cancer and GeneticsCardiff UniversityCardiffUnited Kingdom
| | - João F Passos
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Owen R Davies
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical ResearchMassachusetts Institute of TechnologyCambridgeUnited States
| | - Andrew R Tee
- Institute of Cancer and GeneticsCardiff UniversityCardiffUnited Kingdom
| | - Sovan Sarkar
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental SciencesUniversity of BirminghamBirminghamUnited Kingdom
| | - Viktor I Korolchuk
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
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104
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Maiese K. Targeting molecules to medicine with mTOR, autophagy and neurodegenerative disorders. Br J Clin Pharmacol 2015; 82:1245-1266. [PMID: 26469771 DOI: 10.1111/bcp.12804] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Revised: 10/11/2015] [Accepted: 10/13/2015] [Indexed: 12/14/2022] Open
Abstract
Neurodegenerative disorders are significantly increasing in incidence as the age of the global population continues to climb with improved life expectancy. At present, more than 30 million individuals throughout the world are impacted by acute and chronic neurodegenerative disorders with limited treatment strategies. The mechanistic target of rapamycin (mTOR), also known as the mammalian target of rapamycin, is a 289 kDa serine/threonine protein kinase that offers exciting possibilities for novel treatment strategies for a host of neurodegenerative diseases that include Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy, stroke and trauma. mTOR governs the programmed cell death pathways of apoptosis and autophagy that can determine neuronal stem cell development, precursor cell differentiation, cell senescence, cell survival and ultimate cell fate. Coupled to the cellular biology of mTOR are a number of considerations for the development of novel treatments involving the fine control of mTOR signalling, tumourigenesis, complexity of the apoptosis and autophagy relationship, functional outcome in the nervous system, and the intimately linked pathways of growth factors, phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), AMP activated protein kinase (AMPK), silent mating type information regulation two homologue one (Saccharomyces cerevisiae) (SIRT1) and others. Effective clinical translation of the cellular signalling mechanisms of mTOR offers provocative avenues for new drug development in the nervous system tempered only by the need to elucidate further the intricacies of the mTOR pathway.
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Affiliation(s)
- Kenneth Maiese
- Cellular and Molecular Signaling, Newark, New Jersey, 07101, USA.
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105
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Abeyrathna P, Su Y. The critical role of Akt in cardiovascular function. Vascul Pharmacol 2015; 74:38-48. [PMID: 26025205 PMCID: PMC4659756 DOI: 10.1016/j.vph.2015.05.008] [Citation(s) in RCA: 288] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 05/07/2015] [Accepted: 05/16/2015] [Indexed: 12/30/2022]
Abstract
Akt kinase, a member of AGC kinases, is important in many cellular functions including proliferation, migration, cell growth and metabolism. There are three known Akt isoforms which play critical and diverse roles in the cardiovascular system. Akt activity is regulated by its upstream regulatory pathways at transcriptional and post-translational levels. Beta-catenin/Tcf-4, GLI1 and Stat-3 are some of few known transcriptional regulators of AKT gene. Threonine 308 and serine 473 are the two critical phosphorylation sites of Akt1. Translocation of Akt to the cell membrane facilitates PDK1 phosphorylation of the threonine site. The serine site is phosphorylated by mTORC2. Ack1, Src, PTK6, TBK1, IKBKE and IKKε are some of the non-canonical pathways which affect the Akt activity. Protein-protein interactions of Akt to actin and Hsp90 increase the Akt activity while Akt binding to other proteins such as CTMP and TRB3 reduces the Akt activity. The action of Akt on its downstream targets determines its function in cardiovascular processes such as cell survival, growth, proliferation, angiogenesis, vasorelaxation, and cell metabolism. Akt promotes cell survival via caspase-9, YAP, Bcl-2, and Bcl-x activities. Inhibition of FoxO proteins by Akt also increases cell survival by transcriptional mechanisms. Akt stimulates cell growth and proliferation through mTORC1. Akt also increases VEGF secretion and mediates eNOS phosphorylation, vasorelaxation and angiogenesis. Akt can increase cellular metabolism through its downstream targets GSK3 and GLUT4. The alterations of Akt signaling play an important role in many cardiovascular pathological processes such as atherosclerosis, cardiac hypertrophy, and vascular remodeling. Several Akt inhibitors have been developed and tested as anti-tumor agents. They could be potential novel therapeutics for the cardiovascular diseases.
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Affiliation(s)
- Prasanna Abeyrathna
- Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA.
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106
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Wong HT, McCartney DL, Lewis JC, Sampson JR, Howe CJ, de Vries PJ. Intellectual ability in tuberous sclerosis complex correlates with predicted effects of mutations on TSC1 and TSC2 proteins. J Med Genet 2015; 52:815-22. [DOI: 10.1136/jmedgenet-2015-103154] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 08/29/2015] [Indexed: 12/13/2022]
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107
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Agarwal S, Bell CM, Taylor SM, Moran RG. p53 Deletion or Hotspot Mutations Enhance mTORC1 Activity by Altering Lysosomal Dynamics of TSC2 and Rheb. Mol Cancer Res 2015; 14:66-77. [PMID: 26385560 DOI: 10.1158/1541-7786.mcr-15-0159] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 09/08/2015] [Indexed: 12/21/2022]
Abstract
UNLABELLED The activity of mammalian target of rapamycin complex 1 (mTORC1) is frequently enhanced in carcinomas, an effect thought to contribute to the malignant phenotype. Here, it is demonstrated that either deletion or mutation of TP53 in colon or lung carcinoma cells substantially enhances mTORC1 kinase activity by an effect downstream of and independent of AMPK. Mechanistically, it was determined that loss or mutation of p53 decreased expression of TSC2 and Sestrin2 (SESN2). Complementation of p53 null cells with TSC2 or Sestrin2 reduced mTORC1 activity to levels found in p53 wild-type (wt) cells, whereas their genetic depletion enhanced mTORC1 activity in p53 wt cells. However, the primary causal event in enhanced mTORC1 activity upon loss of p53 appeared to be a diminished distribution of TSC2 to lysosomal membranes containing mTOR. Subsequently, there was increased Rheb in the lysosomal compartment, and a higher mTOR association with Raptor. Transfection of TSC2 into p53 null cells replaced TSC2 and diminished Rheb at the lysosome, recapitulating cells with wt p53. In contrast, transfection of Sestrin2 decreased mTOR in lysosomes, but the lower levels of Sestrin2 in p53 null cells did not change lysosomal mTOR. In summary, loss of the transcriptional activity of p53, either by deletion or by key mutations in the DNA-binding domain, diminishes expression of TSC2 and Sestrin2, thus, shifting membrane-bound TSC2 out of lysosomal membranes, increasing lysosomal Rheb and increasing the kinase activity of mTORC1. IMPLICATIONS This study establishes that loss of p53 function decreases lysosomal TSC2 and increases lysosomal Rheb resulting in hyperactive mTORC1, findings that are consistent with a more malignant phenotype.
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Affiliation(s)
- Stuti Agarwal
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Catherine M Bell
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Shirley M Taylor
- Department of Microbiology and Immunology and Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia
| | - Richard G Moran
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia.
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108
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Plescher M, Teleman AA, Demetriades C. TSC2 mediates hyperosmotic stress-induced inactivation of mTORC1. Sci Rep 2015; 5:13828. [PMID: 26345496 PMCID: PMC4642562 DOI: 10.1038/srep13828] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/06/2015] [Indexed: 02/07/2023] Open
Abstract
mTOR complex 1 (mTORC1) regulates cell growth and metabolism. mTORC1 activity is regulated via integration of positive growth-promoting stimuli and negative stress stimuli. One stress cells confront in physiological and pathophysiological contexts is hyperosmotic stress. The mechanism by which hyperosmotic stress regulates mTORC1 activity is not well understood. We show here that mild hyperosmotic stress induces a rapid and reversible inactivation of mTORC1 via a mechanism involving multiple upstream signaling pathways. We find that hyperosmotic stress causes dynamic changes in TSC2 phosphorylation by upstream kinases, such as Akt, thereby recruiting TSC2 from the cytoplasm to lysosomes where it acts on Rheb, the direct activator of mTORC1. This work puts together a signaling pathway whereby hyperosmotic stress inactivates mTORC1.
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Affiliation(s)
- Monika Plescher
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Aurelio A Teleman
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Constantinos Demetriades
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
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109
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Zhang J, Tripathi DN, Jing J, Alexander A, Kim J, Powell RT, Dere R, Tait-Mulder J, Lee JH, Paull TT, Pandita RK, Charaka VK, Pandita TK, Kastan MB, Walker CL. ATM functions at the peroxisome to induce pexophagy in response to ROS. Nat Cell Biol 2015; 17:1259-1269. [PMID: 26344566 PMCID: PMC4589490 DOI: 10.1038/ncb3230] [Citation(s) in RCA: 315] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 07/24/2015] [Indexed: 12/13/2022]
Abstract
Peroxisomes are highly metabolic, autonomously replicating organelles that generate ROS as a by product of fatty acid β-oxidation. Consequently, cells must maintain peroxisome homeostasis, or risk pathologies associated with too few peroxisomes, such as peroxisome biogenesis disorders, or too many peroxisomes, inducing oxidative damage and promoting diseases such as cancer. We report that the PEX5 peroxisome import receptor binds ataxia-telangiectasia mutated (ATM) and localizes this kinase to the peroxisome. In response to reactive oxygen species (ROS), ATM signaling activates ULK1 and inhibits mTORC1 to induce autophagy. Specificity for autophagy of peroxisomes (pexophagy) is provided by ATM phosphorylation of PEX5 at Ser141, which promotes PEX5 mono-ubiquitination at K209, and recognition of ubiquitinated PEX5 by the autophagy adapter protein p62, directing the autophagosome to peroxisomes to induce pexophagy. These data reveal an important new role for ATM in metabolism as a sensor of ROS that regulates pexophagy.
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Affiliation(s)
- Jiangwei Zhang
- Center for Translational Cancer Research, Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | - Durga Nand Tripathi
- Center for Translational Cancer Research, Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | - Ji Jing
- Center for Translational Cancer Research, Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | - Angela Alexander
- Department of Experimental Radiation Oncology, UT MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jinhee Kim
- Korea Institute of Oriental Medicine, Dajeon, 305-811, South Korea
| | - Reid T Powell
- Center for Translational Cancer Research, Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | - Ruhee Dere
- Center for Translational Cancer Research, Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | | | - Ji-Hoon Lee
- The Howard Hughes Medical Institute, Department of Molecular Genetics and Microbiology, University of Texas, Austin, TX 78712
| | - Tanya T Paull
- The Howard Hughes Medical Institute, Department of Molecular Genetics and Microbiology, University of Texas, Austin, TX 78712
| | - Raj K Pandita
- Department of Radiation Oncology, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Vijaya K Charaka
- Department of Radiation Oncology, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Tej K Pandita
- Department of Radiation Oncology, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Michael B Kastan
- Departments of Oncology, St. Jude Children's Research Hospital, Memphis, TN 38105.,Pharmacology and Cancer Biology, Duke Cancer Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Cheryl Lyn Walker
- Center for Translational Cancer Research, Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
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110
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mTOR and its tight regulation for iNKT cell development and effector function. Mol Immunol 2015; 68:536-45. [PMID: 26253278 DOI: 10.1016/j.molimm.2015.07.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 06/09/2015] [Accepted: 07/19/2015] [Indexed: 12/26/2022]
Abstract
Invariant NKT (iNKT) cells, which express the invariant Vα14Jα18 TCR that recognizes lipid antigens, have the ability to rapidly respond to agonist stimulation, producing a variety of cytokines that can shape both innate and adaptive immunity. iNKT cells have been implicated in host defense against microbial infection, in anti-tumor immunity, and a multitude of diseases such as allergies, asthma, graft versus host disease, and obesity. Emerging evidence has demonstrated crucial role for mammalian target of rapamycin (mTOR) in immune cells, including iNKT. In this review we will discuss current understanding of how mTOR and its tight regulation control iNKT cell development, effector lineage differentiation, and function.
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111
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Guo H, German P, Bai S, Barnes S, Guo W, Qi X, Lou H, Liang J, Jonasch E, Mills GB, Ding Z. The PI3K/AKT Pathway and Renal Cell Carcinoma. J Genet Genomics 2015; 42:343-53. [PMID: 26233890 PMCID: PMC4624215 DOI: 10.1016/j.jgg.2015.03.003] [Citation(s) in RCA: 243] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/03/2015] [Accepted: 03/11/2015] [Indexed: 12/21/2022]
Abstract
The phosphatidylinositol 3 kinase (PI3K)/AKT pathway is genetically targeted in more pathway components and in more tumor types than any other growth factor signaling pathway, and thus is frequently activated as a cancer driver. More importantly, the PI3K/AKT pathway is composed of multiple bifurcating and converging kinase cascades, providing many potential targets for cancer therapy. Renal cell carcinoma (RCC) is a high-risk and high-mortality cancer that is notoriously resistant to traditional chemotherapies or radiotherapies. The PI3K/AKT pathway is modestly mutated but highly activated in RCC, representing a promising drug target. Indeed, PI3K pathway inhibitors of the rapalog family are approved for use in RCC. Recent large-scale integrated analyses of a large number of patients have provided a molecular basis for RCC, reiterating the critical role of the PI3K/AKT pathway in this cancer. In this review, we summarize the genetic alterations of the PI3K/AKT pathway in RCC as indicated in the latest large-scale genome sequencing data, as well as treatments for RCC that target the aberrant activated PI3K/AKT pathway.
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Affiliation(s)
- Huifang Guo
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Peter German
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shanshan Bai
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sean Barnes
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Wei Guo
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xiangjie Qi
- Department of Radiation Oncology, People's Hospital of Linzi District, Zibo 255400, China
| | - Hongxiang Lou
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology of Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Jiyong Liang
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Eric Jonasch
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Gordon B Mills
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| | - Zhiyong Ding
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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112
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Patel VA, Massenburg D, Vujicic S, Feng L, Tang M, Litbarg N, Antoni A, Rauch J, Lieberthal W, Levine JS. Apoptotic cells activate AMP-activated protein kinase (AMPK) and inhibit epithelial cell growth without change in intracellular energy stores. J Biol Chem 2015; 290:22352-69. [PMID: 26183782 DOI: 10.1074/jbc.m115.667345] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Indexed: 01/21/2023] Open
Abstract
Apoptosis plays an indispensable role in the maintenance and development of tissues. We have shown that receptor-mediated recognition of apoptotic target cells by viable kidney proximal tubular epithelial cells (PTECs) inhibits the proliferation and survival of PTECs. Here, we examined the effect of apoptotic targets on PTEC cell growth (cell size during G1 phase of the cell cycle). Using a cell culture model, we show that apoptotic cells potently activate AMP-activated protein kinase (AMPK), a highly sensitive sensor of intracellular energy stores. AMPK activation leads to decreased activity of its downstream target, ribosomal protein p70 S6 kinase (p70S6K), and concomitant inhibition of cell growth. Importantly, these events occur without detectable change in intracellular levels of AMP, ADP, or ATP. Inhibition of AMPK, either pharmacologically by compound C or molecularly by shRNA, diminishes the effects of apoptotic targets and largely restores p70S6K activity and cell size to normal levels. Apoptotic targets also inhibit Akt, a second signaling pathway regulating cell growth. Expression of a constitutively active Akt construct partially relieved cell growth inhibition but was less effective than inhibition of AMPK. Inhibition of cell growth by apoptotic targets is dependent on physical interaction between apoptotic targets and PTECs but independent of phagocytosis. We conclude that receptor-mediated recognition of apoptotic targets mimics the effects of intracellular energy depletion, activating AMPK and inhibiting cell growth. By acting as sentinels of environmental change, apoptotic death may enable nearby viable cells, especially nonmigratory epithelial cells, to monitor and adapt to local stresses.
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Affiliation(s)
- Vimal A Patel
- From the Section of Nephrology, Departments of Medicine and the Section of Nephrology, Department of Medicine, Jesse Brown Veterans Affairs Hospital, Chicago, Illinois 60612
| | - Donald Massenburg
- From the Section of Nephrology, Departments of Medicine and the Section of Nephrology, Department of Medicine, Jesse Brown Veterans Affairs Hospital, Chicago, Illinois 60612
| | - Snezana Vujicic
- From the Section of Nephrology, Departments of Medicine and the Section of Nephrology, Department of Medicine, Jesse Brown Veterans Affairs Hospital, Chicago, Illinois 60612
| | - Lanfei Feng
- From the Section of Nephrology, Departments of Medicine and the Section of Nephrology, Department of Medicine, Jesse Brown Veterans Affairs Hospital, Chicago, Illinois 60612
| | - Meiyi Tang
- the Section of Nephrology, Department of Medicine, Stony Brook University Medical Center, Stony Brook, New York 11794, the Northport Veterans Affairs Hospital, Northport, New York 11768
| | - Natalia Litbarg
- From the Section of Nephrology, Departments of Medicine and the Section of Nephrology, Department of Medicine, Jesse Brown Veterans Affairs Hospital, Chicago, Illinois 60612
| | - Angelika Antoni
- the Department of Biology, Kutztown University of Pennsylvania, Kutztown, Pennsylvania 19530, and
| | - Joyce Rauch
- the Division of Rheumatology, Department of Medicine, Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada
| | - Wilfred Lieberthal
- the Section of Nephrology, Department of Medicine, Stony Brook University Medical Center, Stony Brook, New York 11794, the Northport Veterans Affairs Hospital, Northport, New York 11768
| | - Jerrold S Levine
- From the Section of Nephrology, Departments of Medicine and the Section of Nephrology, Department of Medicine, Jesse Brown Veterans Affairs Hospital, Chicago, Illinois 60612, Microbiology and Immunology, University of Illinois, Chicago, Illinois 60612,
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113
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Dibble CC, Cantley LC. Regulation of mTORC1 by PI3K signaling. Trends Cell Biol 2015; 25:545-55. [PMID: 26159692 DOI: 10.1016/j.tcb.2015.06.002] [Citation(s) in RCA: 573] [Impact Index Per Article: 63.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 06/08/2015] [Accepted: 06/08/2015] [Indexed: 11/29/2022]
Abstract
The class I phosphoinositide 3-kinase (PI3K)-mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signaling network directs cellular metabolism and growth. Activation of mTORC1 [composed of mTOR, regulatory-associated protein of mTOR (Raptor), mammalian lethal with SEC13 protein 8(mLST8), 40-kDa proline-rich Akt substrate (PRAS40), and DEP domain-containing mTOR-interacting protein (DEPTOR)] depends on the Ras-related GTPases (Rags) and Ras homolog enriched in brain (Rheb) GTPase and requires signals from amino acids, glucose, oxygen, energy (ATP), and growth factors (including cytokines and hormones such as insulin). Here we discuss the signal transduction mechanisms through which growth factor-responsive PI3K signaling activates mTORC1. We focus on how PI3K-dependent activation of Akt and spatial regulation of the tuberous sclerosis complex (TSC) complex (TSC complex) [composed of TSC1, TSC2, and Tre2-Bub2-Cdc16-1 domain family member 7 (TBC1D7)] switches on Rheb at the lysosome, where mTORC1 is activated. Integration of PI3K- and amino acid-dependent signals upstream of mTORC1 at the lysosome is detailed in a working model. A coherent understanding of the PI3K-mTORC1 network is imperative as its dysregulation has been implicated in diverse pathologies including cancer, diabetes, autism, and aging.
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Affiliation(s)
- Christian C Dibble
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lewis C Cantley
- Meyer Cancer Center, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA.
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Zhao J, Zhao D, Poage GM, Mazumdar A, Zhang Y, Hill JL, Hartman ZC, Savage MI, Mills GB, Brown PH. Death-associated protein kinase 1 promotes growth of p53-mutant cancers. J Clin Invest 2015; 125:2707-20. [PMID: 26075823 DOI: 10.1172/jci70805] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 05/07/2015] [Indexed: 12/20/2022] Open
Abstract
Estrogen receptor-negative (ER-negative) breast cancers are extremely aggressive and associated with poor prognosis. In particular, effective treatment strategies are limited for patients diagnosed with triple receptor-negative breast cancer (TNBC), which also carries the worst prognosis of all forms of breast cancer; therefore, extensive studies have focused on the identification of molecularly targeted therapies for this tumor subtype. Here, we sought to identify molecular targets that are capable of suppressing tumorigenesis in TNBCs. Specifically, we found that death-associated protein kinase 1 (DAPK1) is essential for growth of p53-mutant cancers, which account for over 80% of TNBCs. Depletion or inhibition of DAPK1 suppressed growth of p53-mutant but not p53-WT breast cancer cells. Moreover, DAPK1 inhibition limited growth of other p53-mutant cancers, including pancreatic and ovarian cancers. DAPK1 mediated the disruption of the TSC1/TSC2 complex, resulting in activation of the mTOR pathway. Our studies demonstrated that high DAPK1 expression causes increased cancer cell growth and enhanced signaling through the mTOR/S6K pathway; evaluation of multiple breast cancer patient data sets revealed that high DAPK1 expression associates with worse outcomes in individuals with p53-mutant cancers. Together, our data support targeting DAPK1 as a potential therapeutic strategy for p53-mutant cancers.
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115
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Chua CEL, Tang BL. Role of Rab GTPases and their interacting proteins in mediating metabolic signalling and regulation. Cell Mol Life Sci 2015; 72:2289-304. [PMID: 25690707 PMCID: PMC11113524 DOI: 10.1007/s00018-015-1862-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 10/24/2022]
Abstract
The vesicular transport pathways, which shuttle materials to and from the cell surface and within the cell, and the metabolic (growth factor and nutrient) signalling pathways, which integrate a variety of extracellular and intracellular signals to mediate growth, proliferation or survival, are both important for cellular physiology. There is evidence to suggest that the transport and metabolic signalling pathways intersect-vesicular transport can affect the regulation of metabolic signals and vice versa. The Rab family GTPases regulate the specificity of vesicular transport steps in the cell. Together with their interacting proteins, Rabs would likely constitute the points of intersection between vesicular transport and metabolic signalling pathways. Examples of these points would include growth factor signalling, glucose and lipid metabolism, as well as autophagy. Many of these processes involve mechanistic/mammalian target of rapamycin (mTOR) complex 1 (mTORC1) in downstream cascades, or are regulated by TORC signalling. A general functionality of the vesicular transport processes controlled by the Rabs is also important for spatial and temporal regulation of the transmission of metabolic signals between the cell surface and the nucleus. In other cases, specific Rabs and their interacting proteins are known to function in recruiting metabolism-related proteins to target membranes, or may compete with other factors in the TORC signalling pathway as a means of metabolic regulation. We review and discuss herein examples of how Rabs and their interacting proteins can mediate metabolic signalling and regulation in cells.
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Affiliation(s)
- Christelle En Lin Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University Health System, 8 Medical Drive, Singapore, 117597, Singapore,
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Noskovičová N, Petřek M, Eickelberg O, Heinzelmann K. Platelet-Derived Growth Factor Signaling in the Lung. From Lung Development and Disease to Clinical Studies. Am J Respir Cell Mol Biol 2015; 52:263-84. [DOI: 10.1165/rcmb.2014-0294tr] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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117
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Serbus LR, White PM, Silva JP, Rabe A, Teixeira L, Albertson R, Sullivan W. The impact of host diet on Wolbachia titer in Drosophila. PLoS Pathog 2015; 11:e1004777. [PMID: 25826386 PMCID: PMC4380406 DOI: 10.1371/journal.ppat.1004777] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 03/03/2015] [Indexed: 12/31/2022] Open
Abstract
While a number of studies have identified host factors that influence endosymbiont titer, little is known concerning environmental influences on titer. Here we examined nutrient impact on maternally transmitted Wolbachia endosymbionts in Drosophila. We demonstrate that Drosophila reared on sucrose- and yeast-enriched diets exhibit increased and reduced Wolbachia titers in oogenesis, respectively. The yeast-induced Wolbachia depletion is mediated in large part by the somatic TOR and insulin signaling pathways. Disrupting TORC1 with the small molecule rapamycin dramatically increases oocyte Wolbachia titer, whereas hyper-activating somatic TORC1 suppresses oocyte titer. Furthermore, genetic ablation of insulin-producing cells located in the Drosophila brain abolished the yeast impact on oocyte titer. Exposure to yeast-enriched diets altered Wolbachia nucleoid morphology in oogenesis. Furthermore, dietary yeast increased somatic Wolbachia titer overall, though not in the central nervous system. These findings highlight the interactions between Wolbachia and germline cells as strongly nutrient-sensitive, and implicate conserved host signaling pathways by which nutrients influence Wolbachia titer.
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Affiliation(s)
- Laura R. Serbus
- Department of Biological Sciences, Florida International University Modesto A. Maidique Campus, Miami, Florida, United States of America
- Biomolecular Sciences Institute, Florida International University Modesto A. Maidique Campus, Miami, Florida, United States of America
| | - Pamela M. White
- Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Jessica Pintado Silva
- Department of Biological Sciences, Florida International University Modesto A. Maidique Campus, Miami, Florida, United States of America
- Biomolecular Sciences Institute, Florida International University Modesto A. Maidique Campus, Miami, Florida, United States of America
| | - Amanda Rabe
- Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
| | | | - Roger Albertson
- Biology Department, Albion College, Albion, Michigan, United States of America
| | - William Sullivan
- Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
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Thien A, Prentzell MT, Holzwarth B, Kläsener K, Kuper I, Boehlke C, Sonntag AG, Ruf S, Maerz L, Nitschke R, Grellscheid SN, Reth M, Walz G, Baumeister R, Neumann-Haefelin E, Thedieck K. TSC1 activates TGF-β-Smad2/3 signaling in growth arrest and epithelial-to-mesenchymal transition. Dev Cell 2015; 32:617-30. [PMID: 25727005 DOI: 10.1016/j.devcel.2015.01.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 12/19/2014] [Accepted: 01/22/2015] [Indexed: 11/27/2022]
Abstract
The tuberous sclerosis proteins TSC1 and TSC2 are key integrators of growth factor signaling. They suppress cell growth and proliferation by acting in a heteromeric complex to inhibit the mammalian target of rapamycin complex 1 (mTORC1). In this study, we identify TSC1 as a component of the transforming growth factor β (TGF-β)-Smad2/3 pathway. Here, TSC1 functions independently of TSC2. TSC1 interacts with the TGF-β receptor complex and Smad2/3 and is required for their association with one another. TSC1 regulates TGF-β-induced Smad2/3 phosphorylation and target gene expression and controls TGF-β-induced growth arrest and epithelial-to-mesenchymal transition (EMT). Hyperactive Akt specifically activates TSC1-dependent cytostatic Smad signaling to induce growth arrest. Thus, TSC1 couples Akt activity to TGF-β-Smad2/3 signaling. This has implications for cancer treatments targeting phosphoinositide 3-kinases and Akt because they may impair tumor-suppressive cytostatic TGF-β signaling by inhibiting Akt- and TSC1-dependent Smad activation.
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Affiliation(s)
- Antje Thien
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Mirja Tamara Prentzell
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands
| | - Birgit Holzwarth
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Kathrin Kläsener
- Molecular Immunology (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Molecular Immunology, Max-Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Ineke Kuper
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany
| | | | - Annika G Sonntag
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Stefanie Ruf
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Research Training Group (RTG) 1104, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Lars Maerz
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Roland Nitschke
- BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | | | - Michael Reth
- Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Molecular Immunology (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Molecular Immunology, Max-Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Gerd Walz
- Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Ralf Baumeister
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Research Training Group (RTG) 1104, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; ZBMZ Centre for Biochemistry and Molecular Cell Research (Faculty of Medicine), Albert-Ludwigs-University Freiburg, 79106 Freiburg, Germany
| | | | - Kathrin Thedieck
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany.
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Alem F, Yao K, Lane D, Calvert V, Petricoin EF, Kramer L, Hale ML, Bavari S, Panchal RG, Hakami RM. Host response during Yersinia pestis infection of human bronchial epithelial cells involves negative regulation of autophagy and suggests a modulation of survival-related and cellular growth pathways. Front Microbiol 2015; 6:50. [PMID: 25762983 PMCID: PMC4327736 DOI: 10.3389/fmicb.2015.00050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/14/2015] [Indexed: 12/16/2022] Open
Abstract
Yersinia pestis (Yp) causes the re-emerging disease plague, and is classified by the CDC and NIAID as a highest priority (Category A) pathogen. Currently, there is no approved human vaccine available and advances in early diagnostics and effective therapeutics are urgently needed. A deep understanding of the mechanisms of host response to Yp infection can significantly advance these three areas. We employed the Reverse Phase Protein Microarray (RPMA) technology to reveal the dynamic states of either protein level changes or phosphorylation changes associated with kinase-driven signaling pathways during host cell response to Yp infection. RPMA allowed quantitative profiling of changes in the intracellular communication network of human lung epithelial cells at different times post infection and in response to different treatment conditions, which included infection with the virulent Yp strain CO92, infection with a derivative avirulent strain CO92 (Pgm-, Pst-), treatment with heat inactivated CO92, and treatment with LPS. Responses to a total of 111 validated antibodies were profiled, leading to discovery of 12 novel protein hits. The RPMA analysis also identified several protein hits previously reported in the context of Yp infection. Furthermore, the results validated several proteins previously reported in the context of infection with other Yersinia species or implicated for potential relevance through recombinant protein and cell transfection studies. The RPMA results point to strong modulation of survival/apoptosis and cell growth pathways during early host response and also suggest a model of negative regulation of the autophagy pathway. We find significant cytoplasmic localization of p53 and reduced LC3-I to LC3-II conversion in response to Yp infection, consistent with negative regulation of autophagy. These studies allow for a deeper understanding of the pathogenesis mechanisms and the discovery of innovative approaches for prevention, early diagnosis, and treatment of plague.
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Affiliation(s)
- Farhang Alem
- National Center for Biodefense and Infectious Diseases and School of Systems Biology, George Mason University Manassas, VA, USA
| | - Kuan Yao
- National Center for Biodefense and Infectious Diseases and School of Systems Biology, George Mason University Manassas, VA, USA
| | - Douglas Lane
- U.S. Army Medical Research Institute of Infectious Diseases Frederick, MD, USA
| | - Valerie Calvert
- Center for Applied Proteomics and Molecular Medicine, School of Systems Biology, George Mason University Manassas, VA, USA
| | - Emanuel F Petricoin
- Center for Applied Proteomics and Molecular Medicine, School of Systems Biology, George Mason University Manassas, VA, USA
| | - Liana Kramer
- National Center for Biodefense and Infectious Diseases and School of Systems Biology, George Mason University Manassas, VA, USA
| | - Martha L Hale
- U.S. Army Medical Research Institute of Infectious Diseases Frederick, MD, USA
| | - Sina Bavari
- U.S. Army Medical Research Institute of Infectious Diseases Frederick, MD, USA
| | - Rekha G Panchal
- U.S. Army Medical Research Institute of Infectious Diseases Frederick, MD, USA
| | - Ramin M Hakami
- National Center for Biodefense and Infectious Diseases and School of Systems Biology, George Mason University Manassas, VA, USA
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120
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Jeon Y, Jung Y, Youm JK, Kang KS, Kim YK, Kim SN. Abietic acid inhibits UVB-induced MMP-1 expression in human dermal fibroblast cells through PPARα/γdual activation. Exp Dermatol 2015; 24:140-5. [DOI: 10.1111/exd.12616] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2014] [Indexed: 12/26/2022]
Affiliation(s)
- Youngsic Jeon
- Natural Skinomics Team; KIST Gangneung Institute of Natural Products; Gangneung Korea
| | - Yujung Jung
- Natural Skinomics Team; KIST Gangneung Institute of Natural Products; Gangneung Korea
| | | | - Ki Sung Kang
- College of Korean Medicine; Gachon University; Seongnam Korea
| | - Yong Kee Kim
- College of Pharmacy; Sookmyung Women's University; Seoul Korea
| | - Su-Nam Kim
- Natural Skinomics Team; KIST Gangneung Institute of Natural Products; Gangneung Korea
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121
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Gomes AP, Blenis J. A nexus for cellular homeostasis: the interplay between metabolic and signal transduction pathways. Curr Opin Biotechnol 2015; 34:110-7. [PMID: 25562138 DOI: 10.1016/j.copbio.2014.12.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 12/08/2014] [Accepted: 12/10/2014] [Indexed: 12/21/2022]
Abstract
In multicellular organisms, individual cells have evolved to sense external and internal cues in order to maintain cellular homeostasis and survive under different environmental conditions. Cells efficiently adjust their metabolism to reflect the abundance of nutrients, energy and growth factors. The ability to rewire cellular metabolism between anabolic and catabolic processes is crucial for cells to thrive. Thus, cells have developed, through evolution, metabolic networks that are highly plastic and tightly regulated to meet the requirements necessary to maintain cellular homeostasis. The plasticity of these cellular systems is tightly regulated by complex signaling networks that integrate the intracellular and extracellular information. The coordination of signal transduction and metabolic pathways is essential in maintaining a healthy and rapidly responsive cellular state.
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Affiliation(s)
- Ana P Gomes
- Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA; Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - John Blenis
- Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA; Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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122
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Maiese K. Cutting through the complexities of mTOR for the treatment of stroke. Curr Neurovasc Res 2014; 11:177-86. [PMID: 24712647 DOI: 10.2174/1567202611666140408104831] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 03/17/2014] [Accepted: 03/19/2014] [Indexed: 01/06/2023]
Abstract
On a global basis, at least 15 million individuals suffer some form of a stroke every year. Of these individuals, approximately 800,000 of these cerebrovascular events occur in the United States (US) alone. The incidence of stroke in the US has declined from the third leading cause of death to the fourth, a result that can be attributed to multiple factors that include improved vascular disease management, reduced tobacco use, and more rapid time to treatment in patients that are clinically appropriate to receive recombinant tissue plasminogen activator. However, treatment strategies for the majority of stroke patients are extremely limited and represent a critical void for care. A number of new therapeutic considerations for stroke are under consideration, but it is the mammalian target of rapamycin (mTOR) that is receiving intense focus as a potential new target for cerebrovascular disease. As part of the phosphoinositide 3-kinase (PI 3-K) and protein kinase B (Akt) cascade, mTOR is an essential component of mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) to govern cell death involving apoptosis, autophagy, and necroptosis, cellular metabolism, and gene transcription. Vital for the consideration of new therapeutic strategies for stroke is the ability to understand how the intricate and complex pathways of mTOR signaling sometimes lead to disparate clinical outcomes.
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Affiliation(s)
- Kenneth Maiese
- Cellular and Molecular Signaling, Newark, New Jersey 07101, USA.
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123
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Wang X, Johnson GA, Burghardt RC, Wu G, Bazer FW. Uterine histotroph and conceptus development. I. cooperative effects of arginine and secreted phosphoprotein 1 on proliferation of ovine trophectoderm cells via activation of the PDK1-Akt/PKB-TSC2-MTORC1 signaling cascade. Biol Reprod 2014; 92:51. [PMID: 25550342 DOI: 10.1095/biolreprod.114.125971] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The greatest limitation to reproductive performance in most mammals, including humans, is embryonic mortality, which, in general, claims 20%-40% of the embryos during the peri-implantation period of pregnancy. Both arginine and secreted phosphoprotein 1 (SPP1) are multifunctional molecules that increase significantly in ovine uterine histotroph during early pregnancy. However, little is known about the relationship and underlying mechanisms for synergistic effects of arginine and SPP1, if any, on conceptus (embryo/fetus and associated extraembryonic membranes) development. Therefore, we conducted in vitro experiments using our established ovine trophectoderm cell line (oTr1) isolated from Day 15 ovine conceptuses to determine their proliferative response to individual and synergistic effects of arginine and recombinant SPP1 (rSPP1) that contains an RGD binding sequence. At physiological concentrations, arginine (0.2 mM) stimulated oTr1 cell proliferation 1.7-fold (P < 0.05) at 48 h, whereas rSPP1 (10 ng/ml) had no such effect. However, an additive effect on oTr1 cell proliferation was induced by combination of arginine and SPP1 as compared to the control (2.1-fold increase; P < 0.01), arginine alone (1.3-fold increase; P < 0.05), and rSPP1 alone (1.5-fold increase; P < 0.01). This additive effect was mediated through cooperative activation of the PDK1-Akt/PKB-TSC2-MTORC1 cell signaling cascade. Collectively, results suggest that arginine and SPP1 in histotroph act cooperatively to enhance survival, growth, and development of ovine conceptuses.
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Affiliation(s)
- Xiaoqiu Wang
- Center for Animal Biotechnology and Genomics, Texas A&M University, College Station, Texas Department of Animal Science, Texas A&M University, College Station, Texas
| | - Greg A Johnson
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas
| | - Robert C Burghardt
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas
| | - Guoyao Wu
- Center for Animal Biotechnology and Genomics, Texas A&M University, College Station, Texas Department of Animal Science, Texas A&M University, College Station, Texas
| | - Fuller W Bazer
- Center for Animal Biotechnology and Genomics, Texas A&M University, College Station, Texas Department of Animal Science, Texas A&M University, College Station, Texas
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124
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Serine-threonine kinases in TCR signaling. Nat Immunol 2014; 15:808-14. [PMID: 25137455 DOI: 10.1038/ni.2941] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/10/2014] [Indexed: 12/13/2022]
Abstract
T lymphocyte proliferation and differentiation are controlled by signaling pathways initiated by the T cell antigen receptor. Here we explore how key serine-threonine kinases and their substrates mediate T cell signaling and coordinate T cell metabolism to meet the metabolic demands of participating in an immune response.
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Britto FA, Begue G, Rossano B, Docquier A, Vernus B, Sar C, Ferry A, Bonnieu A, Ollendorff V, Favier FB. REDD1 deletion prevents dexamethasone-induced skeletal muscle atrophy. Am J Physiol Endocrinol Metab 2014; 307:E983-93. [PMID: 25315696 DOI: 10.1152/ajpendo.00234.2014] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
REDD1 (regulated in development and DNA damage response 1) has been proposed to inhibit the mechanistic target of rapamycin complex 1 (mTORC1) during in vitro hypoxia. REDD1 expression is low under basal conditions but is highly increased in response to several catabolic stresses, like hypoxia and glucocorticoids. However, REDD1 function seems to be tissue and stress dependent, and its role in skeletal muscle in vivo has been poorly characterized. Here, we investigated the effect of REDD1 deletion on skeletal muscle mass, protein synthesis, proteolysis, and mTORC1 signaling pathway under basal conditions and after glucocorticoid administration. Whereas skeletal muscle mass and typology were unchanged between wild-type (WT) and REDD1-null mice, oral gavage with dexamethasone (DEX) for 7 days reduced tibialis anterior and gastrocnemius muscle weights as well as tibialis anterior fiber size only in WT. Similarly, REDD1 deletion prevented the inhibition of protein synthesis and mTORC1 activity (assessed by S6, 4E-BP1, and ULK1 phosphorylation) observed in gastrocnemius muscle of WT mice following single DEX administration for 5 h. However, our results suggest that REDD1-mediated inhibition of mTORC1 in skeletal muscle is not related to the modulation of the binding between TSC2 and 14-3-3. In contrast, our data highlight a new mechanism involved in mTORC1 inhibition linking REDD1, Akt, and PRAS40. Altogether, these results demonstrated in vivo that REDD1 is required for glucocorticoid-induced inhibition of protein synthesis via mTORC1 downregulation. Inhibition of REDD1 may thus be a strategy to limit muscle loss in glucocorticoid-mediated atrophy.
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Affiliation(s)
- Florian A Britto
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - Gwenaelle Begue
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - Bernadette Rossano
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - Aurélie Docquier
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - Barbara Vernus
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - Chamroeun Sar
- Institut National de la Sante et de la Recherche Medicale (INSERM) U 583, Institut de Neuroscience de Montpellier, France
| | - Arnaud Ferry
- Institut de Myologie, INSERM, U974, Centre National de la Recherche Scientifique UMR 7215, Université Pierre et Marie Curie, Paris, France; and Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Anne Bonnieu
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - Vincent Ollendorff
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France
| | - François B Favier
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, F-34000 Montpellier, France; Université Montpellier 1, F-34000 Montpellier, France; Université Montpellier 2, F-34000 Montpellier, France;
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Zheng X, Liang Y, He Q, Yao R, Bao W, Bao L, Wang Y, Wang Z. Current models of mammalian target of rapamycin complex 1 (mTORC1) activation by growth factors and amino acids. Int J Mol Sci 2014; 15:20753-69. [PMID: 25402640 PMCID: PMC4264194 DOI: 10.3390/ijms151120753] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 09/24/2014] [Accepted: 10/29/2014] [Indexed: 01/09/2023] Open
Abstract
Mammalian target of rapamycin (mTOR), which is now referred to as mechanistic target of rapamycin, integrates many signals, including those from growth factors, energy status, stress, and amino acids, to regulate cell growth and proliferation, protein synthesis, protein degradation, and other physiological and biochemical processes. The mTOR-Rheb-TSC-TBC complex co-localizes to the lysosome and the phosphorylation of TSC-TBC effects the dissociation of the complex from the lysosome and activates Rheb. GTP-bound Rheb potentiates the catalytic activity of mTORC1. Under conditions with growth factors and amino acids, v-ATPase, Ragulator, Rag GTPase, Rheb, hVps34, PLD1, and PA have important but disparate effects on mTORC1 activation. In this review, we introduce five models of mTORC1 activation by growth factors and amino acids to provide a comprehensive theoretical foundation for future research.
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Affiliation(s)
- Xu Zheng
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Yan Liang
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Qiburi He
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Ruiyuan Yao
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Wenlei Bao
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Lili Bao
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Yanfeng Wang
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Zhigang Wang
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
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Goncharova EA, James ML, Kudryashova TV, Goncharov DA, Krymskaya VP. Tumor suppressors TSC1 and TSC2 differentially modulate actin cytoskeleton and motility of mouse embryonic fibroblasts. PLoS One 2014; 9:e111476. [PMID: 25360538 PMCID: PMC4216017 DOI: 10.1371/journal.pone.0111476] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 10/02/2014] [Indexed: 01/16/2023] Open
Abstract
TSC1 and TSC2 mutations cause neoplasms in rare disease pulmonary LAM and neuronal pathfinding in hamartoma syndrome TSC. The specific roles of TSC1 and TSC2 in actin remodeling and the modulation of cell motility, however, are not well understood. Previously, we demonstrated that TSC1 and TSC2 regulate the activity of small GTPases RhoA and Rac1, stress fiber formation and cell adhesion in a reciprocal manner. Here, we show that Tsc1−/− MEFs have decreased migration compared to littermate-derived Tsc1+/+ MEFs. Migration of Tsc1−/− MEFs with re-expressed TSC1 was comparable to Tsc1+/+ MEF migration. In contrast, Tsc2−/− MEFs showed an increased migration compared to Tsc2+/+ MEFs that were abrogated by TSC2 re-expression. Depletion of TSC1 and TSC2 using specific siRNAs in wild type MEFs and NIH 3T3 fibroblasts also showed that TSC1 loss attenuates cell migration while TSC2 loss promotes cell migration. Morphological and immunochemical analysis demonstrated that Tsc1−/− MEFs have a thin protracted shape with a few stress fibers; in contrast, Tsc2−/− MEFs showed a rounded morphology and abundant stress fibers. Expression of TSC1 in either Tsc1−/− or Tsc2−/− MEFs promoted stress fiber formation, while TSC2 re-expression induced stress fiber disassembly and the formation of cortical actin. To assess the mechanism(s) by which TSC2 loss promotes actin re-arrangement and cell migration, we explored the role of known downstream effectors of TSC2, mTORC1 and mTORC2. Increased migration of Tsc2−/− MEFs is inhibited by siRNA mTOR and siRNA Rictor, but not siRNA Raptor. siRNA mTOR or siRNA Rictor promoted stress fiber disassembly in TSC2-null cells, while siRNA Raptor had little effect. Overexpression of kinase-dead mTOR induced actin stress fiber disassembly and suppressed TSC2-deficient cell migration. Our data demonstrate that TSC1 and TSC2 differentially regulate actin stress fiber formation and cell migration, and that only TSC2 loss promotes mTOR- and mTORC2-dependent pro-migratory cell phenotype.
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Affiliation(s)
- Elena A. Goncharova
- Airways Biology Initiative, Pulmonary, Allergy & Critical Care Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Melane L. James
- Airways Biology Initiative, Pulmonary, Allergy & Critical Care Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Tatiana V. Kudryashova
- Airways Biology Initiative, Pulmonary, Allergy & Critical Care Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Dmitry A. Goncharov
- Airways Biology Initiative, Pulmonary, Allergy & Critical Care Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Vera P. Krymskaya
- Airways Biology Initiative, Pulmonary, Allergy & Critical Care Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail:
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128
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Gürol G, Demiralp DÖ, Yılmaz AK, Akman Ö, Ateş N, Karson A. Comparative proteomic approach in rat model of absence epilepsy. J Mol Neurosci 2014; 55:632-43. [PMID: 25323782 DOI: 10.1007/s12031-014-0402-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 08/11/2014] [Indexed: 12/21/2022]
Abstract
The aim of this study was to investigate cellular proteins in the pathogenesis of the genetic rat model of absence epilepsy. Protein spots were identified with peptide mass fingerprinting analysis using matrix-assisted laser desorption ionization time of flight mass spectrometry. Data were gathered from the frontoparietal cortex and thalamus of Wistar Albino Glaxo/Rij (WAG/Rij) and Wistar by using two-dimensional gel electrophoresis (2D-PAGE). Six proteins (Clathrin light chain-A protein, Transmembrane EMP24 Domain-Containing Protein, Stathmin-4, Myosin Light Chain4, Rheb, phosphoserine phosphatase) were found to be differentially expressed in the frontoparietal cortex of WAG/Rij and Wistar rats in both age groups. Another set of six proteins (Protein FAM89A and Oasl1, Gemin2, NuDEL1, Pur-beta, 3-alpha HSD) were found to be differentially expressed in the thalamus of WAG/Rij and Wistar rats. Findings from the frontoparietal cortex suggest the presence of altered serine metabolism and increased vesicular trafficking in the frontoparietal cortex of WAG/Rij rats compared with Wistar rats. These differences in the protein levels might reflect the crucial role of these proteins and related pathways in the generation of absence seizures. In the thalamic specimens, age-dependent changes in protein expression were remarkable, suggesting that this phenomenon may be a precursor or a consequence of absence seizures. Our findings further highlight the potential role of the mTOR signaling pathway in absence epilepsy.
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Affiliation(s)
- Gönül Gürol
- Department of Physiology, Faculty of Medicine, Sakarya University, Sakarya, Turkey
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129
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Canal M, Romaní-Aumedes J, Martín-Flores N, Pérez-Fernández V, Malagelada C. RTP801/REDD1: a stress coping regulator that turns into a troublemaker in neurodegenerative disorders. Front Cell Neurosci 2014; 8:313. [PMID: 25324725 PMCID: PMC4183088 DOI: 10.3389/fncel.2014.00313] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 09/17/2014] [Indexed: 12/16/2022] Open
Abstract
Mechanistic target of Rapamycin (mTOR) pathway regulates essential processes directed to preserve cellular homeostasis, such as cell growth, proliferation, survival, protein synthesis and autophagy. Importantly, mTOR pathway deregulation has been related to many diseases. Indeed, it has become a hallmark in neurodegenerative disorders, since a fine-tuned regulation of mTOR activities is crucial for neuron function and survival. RTP801/REDD1/Dig2 has become one of the most puzzling regulators of mTOR. Although the mechanism is not completely understood, RTP801 inactivates mTOR and Akt via the tuberous sclerosis complex (TSC1/TSC2) in many cellular contexts. Intriguingly, RTP801 protects dividing cells from hypoxia or H2O2-induced apoptosis, while it sensitizes differentiated cells to stress. Based on experimental models of Parkinson’s disease (PD), it has been proposed that at early stages of the disease, stress-induced RTP801 upregulation contributes to mTOR repression, in an attempt to maintain cell function and viability. However, if RTP801 elevation is sustained, it leads to neuron cell death by a sequential inhibition of mTOR and Akt. Here, we will review RTP801 deregulation of mTOR in a context of PD and other neurodegenerative disorders.
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Affiliation(s)
- Mercè Canal
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Joan Romaní-Aumedes
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Núria Martín-Flores
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Víctor Pérez-Fernández
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Cristina Malagelada
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
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130
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Westin JR. Status of PI3K/Akt/mTOR pathway inhibitors in lymphoma. CLINICAL LYMPHOMA, MYELOMA & LEUKEMIA 2014; 14:335-42. [PMID: 24650973 PMCID: PMC4125533 DOI: 10.1016/j.clml.2014.01.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/21/2014] [Accepted: 01/23/2014] [Indexed: 02/07/2023]
Abstract
The phosphatidylinositol-3-kinase (PI3K) pathway is well known to regulate a wide variety of essential cellular functions, including glucose metabolism, translational regulation of protein synthesis, cell proliferation, apoptosis, and survival. Aberrations in the PI3K pathway are among the most frequently observed in cancer, and include amplifications, rearrangements, mutations, and loss of regulators. As a net result of these anomalies, the PI3K pathway is activated in many malignancies, including in Hodgkin and non-Hodgkin lymphomas, and yields a competitive growth and survival advantage, increased metastatic ability, and resistance to conventional therapy. Numerous inhibitors targeting various nodes in the PI3K pathway are undergoing clinical development, and their current status in lymphoma will be the focus of this review.
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Affiliation(s)
- Jason R Westin
- Division of Cancer Medicine, Department of Lymphoma and Myeloma, University of Texas M.D. Anderson Cancer Center, Houston, TX.
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131
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Dennis MD, Coleman CS, Berg A, Jefferson LS, Kimball SR. REDD1 enhances protein phosphatase 2A-mediated dephosphorylation of Akt to repress mTORC1 signaling. Sci Signal 2014; 7:ra68. [PMID: 25056877 DOI: 10.1126/scisignal.2005103] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The protein kinase mTOR (mechanistic target of rapamycin) in complex 1 (mTORC1) promotes cell growth and proliferation in response to anabolic stimuli, including growth factors and nutrients. Growth factors activate mTORC1 by stimulating the kinase Akt, which phosphorylates and inhibits the tuberous sclerosis complex [TSC; which is composed of TSC1, TSC2, and TBC1D7 (Tre2-Bub2-Cdc16 domain family member 7)], thereby stimulating the mTORC1 activator Rheb (Ras homolog enriched in brain). We identified the mechanism through which REDD1 (regulated in DNA damage and development 1) represses the mTORC1 signaling pathway. We found that REDD1 promoted the protein phosphatase 2A (PP2A)-dependent dephosphorylation of Akt on Thr(308) but not on Ser(473). Consistent with previous studies showing that phosphorylation of Akt on Thr(308), but not on Ser(473), is necessary for phosphorylation of TSC2, we observed a REDD1-dependent reduction in the phosphorylation of TSC2 and subsequently in the activation state of Rheb. REDD1 and PP2A coimmunoprecipitated with Akt from wild-type but not REDD1 knockout mouse embryonic fibroblasts, suggesting that REDD1 may act as a targeting protein for the catalytic subunit of PP2A. Furthermore, binding to both Akt and PP2A was essential for REDD1 to repress signaling to mTORC1. Overall, the results demonstrate that REDD1 acts not only as a repressor of mTORC1 but also as a constant modulator of the phosphorylation of Akt in response to growth factors and nutrients.
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Affiliation(s)
- Michael D Dennis
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Catherine S Coleman
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Arthur Berg
- Division of Biostatistics and Bioinformatics, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Leonard S Jefferson
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA.
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132
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Jeon Y, Jung Y, Kim MC, Kwon HC, Kang KS, Kim YK, Kim SN. Sargahydroquinoic acid inhibits TNFα-induced AP-1 and NF-κB signaling in HaCaT cells through PPARα activation. Biochem Biophys Res Commun 2014; 450:1553-9. [PMID: 25019995 DOI: 10.1016/j.bbrc.2014.07.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 07/06/2014] [Indexed: 10/25/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors and expressed in various cell types in the skin, including keratinocytes, fibroblasts and infiltrating immune cells. Thus, their ligands are targets for the treatment of various skin disorders, such as photo-aging and chronological aging of skin. Intensive studies have revealed that PPARα/γ functions in photo-aging and age-related inflammation by regulating matrix metalloproteinases (MMPs) via activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB). However, the detailed mechanism of PPARα/γ's role in skin aging has not yet been elucidated. In this study, we confirmed that sargahydroquinoic acid (SHQA) as a PPARα/γ ligand significantly decreased Tumor Necrosis Factor-alpha (TNFα)-induced MMP-2/-9 expression by downregulating TNFα-induced transcription factors, subsequently reducing IκBα degradation and blocking NF-κB p65 nuclear translocation in HaCaT human epidermal keratinocyte cells. Treatment of cells with SHQA and GW6471 (PPARα antagonist) not bisphenol A diglycidyl ether (PPARγ antagonists), reversed the effect on TNFα-induced inflammatory signaling pathway activation. Taken together, our data suggest that SHQA inhibit TNFα-induced MMP-2/-9 expression and age-related inflammation by suppressing AP-1 and NF-κB pathway via PPARα.
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Affiliation(s)
- Youngsic Jeon
- Natural Medicine Center, KIST Gangneung Institute, Gangneung 210-340, Republic of Korea
| | - Yujung Jung
- Natural Medicine Center, KIST Gangneung Institute, Gangneung 210-340, Republic of Korea
| | - Min Cheol Kim
- Natural Medicine Center, KIST Gangneung Institute, Gangneung 210-340, Republic of Korea
| | - Hak Cheol Kwon
- Natural Medicine Center, KIST Gangneung Institute, Gangneung 210-340, Republic of Korea
| | - Ki Sung Kang
- College of Korean Medicine, Gachon University, Seongnam 461-701, Republic of Korea
| | - Yong Kee Kim
- College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
| | - Su-Nam Kim
- Natural Medicine Center, KIST Gangneung Institute, Gangneung 210-340, Republic of Korea.
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Hamartin-Hsp70 Interaction Is Necessary for Akt-Dependent Tuberin Phosphorylation during Heat Shock. Biosci Biotechnol Biochem 2014; 73:2488-93. [DOI: 10.1271/bbb.90489] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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134
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Ren SY, Xu X. Role of autophagy in metabolic syndrome-associated heart disease. Biochim Biophys Acta Mol Basis Dis 2014; 1852:225-31. [PMID: 24810277 DOI: 10.1016/j.bbadis.2014.04.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 04/21/2014] [Accepted: 04/29/2014] [Indexed: 01/21/2023]
Abstract
Metabolic syndrome is a constellation of multiple metabolic risk factors including abdominal obesity, glucose intolerance, insulin resistance, dyslipidemia and hypertension. Over the past decades, the prevalence of metabolic syndrome has increased dramatically, imposing a devastating, pandemic health threat. More importantly, individuals with metabolic syndrome are at an increased risk of diabetes mellitus and overall cardiovascular diseases. One of the common comorbidities of metabolic syndrome is heart anomalies leading to the loss of cardiomyocytes, cardiac dysfunction and ultimately heart failure. Up-to-date, a plethora of cell signaling pathways have been postulated for the pathogenesis of cardiac complications in obesity including lipotoxicity, inflammation, oxidative stress, apoptosis and sympathetic overactivation although the precise mechanism of action underscoring obesity-associated heart dysfunction remains elusive. Recent evidence has indicated a potential role of protein quality control in components of metabolic syndrome. Within the protein quality control system, the autophagy-lysosome pathway is an evolutionarily conserved pathway responsible for bulk degradation of large intracellular organelles and protein aggregates. Autophagy has been demonstrated to play an indispensible role in the maintenance of cardiac geometry and function under both physiological and pathological conditions. Accumulating studies have demonstrated that autophagy plays a pivotal role in the etiology of cardiac anomalies under obesity and metabolic syndrome. In this minireview, we will discuss on how autophagy is involved in the regulation of cardiac function in obesity and metabolic syndrome. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.
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Affiliation(s)
- Sidney Y Ren
- Center for Cardiovascular Research and Alternative Medicine, School of Pharmacy, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA
| | - Xihui Xu
- Center for Cardiovascular Research and Alternative Medicine, School of Pharmacy, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA.
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135
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Moore SF, Hunter RW, Hers I. Protein kinase C and P2Y12 take center stage in thrombin-mediated activation of mammalian target of rapamycin complex 1 in human platelets. J Thromb Haemost 2014; 12:748-60. [PMID: 24612393 PMCID: PMC4238809 DOI: 10.1111/jth.12552] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 02/25/2014] [Indexed: 01/24/2023]
Abstract
BACKGROUND Rapamycin, an inhibitor of mammalian target of rapamycin complex-1 (mTORC1), reduces platelet spreading, thrombus stability, and clot retraction. Despite an important role of mTORC1 in platelet function, little is known about how it is regulated. The objective of this study was to determine the signaling pathways that regulate mTORC1 in human platelets. METHODS Mammalian target of rapamycin complex-1 activation was assessed by measuring the phosphorylation of its downstream substrate ribosomal S6 kinase 1 (p70S6K). RESULTS Thrombin or the protein kinase C (PKC) activator phorbal 12-myristate 13-acetate stimulated activation of mTORC1 in a PKC-dependent, Akt-independent manner that correlated with phosphorylation of tuberin/tuberous sclerosis 2 (TSC2) (Ser939 and Thr1462). In contrast, insulin-like growth factor 1 (IGF-1)-stimulated TSC2 phosphorylation was completely dependent on phosphoinositide 3 kinase (PI3 kinase)/Akt but did not result in any detectable mTORC1 activation. Early (Ser939 and Thr1462) and late (Thr1462) TSC2 phosphorylation in response to thrombin were directly PKC dependent, whereas later TSC2 (Ser939) and p70S6K phosphorylation were largely dependent on paracrine signaling through P2Y(12). PKC-mediated adenosine diphosphate (ADP) secretion was essential for thrombin-stimulated mTORC1 activation, as (i) ADP rescued p70S6K phosphorylation in the presence of a PKC inhibitor and (ii) P2Y(12) antagonism prevented thrombin-mediated mTORC1 activation. Rescue of mTORC1 activation with exogenous ADP was completely dependent on the Src family kinases but independent of PI3 kinase/Akt. Interestingly, although inhibition of Src blocked the ADP rescue, it had little effect on thrombin-stimulated p70S6K phosphorylation under conditions where PKC was not inhibited. CONCLUSION These results demonstrate that thrombin activates the mTORC1 pathway in human platelets through PKC-mediated ADP secretion and subsequent activation of P2Y(12), in a manner largely independent of the canonical PI3 kinase/Akt pathway.
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Affiliation(s)
- S F Moore
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, UK
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136
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Menon S, Dibble CC, Talbott G, Hoxhaj G, Valvezan AJ, Takahashi H, Cantley LC, Manning BD. Spatial control of the TSC complex integrates insulin and nutrient regulation of mTORC1 at the lysosome. Cell 2014; 156:771-85. [PMID: 24529379 DOI: 10.1016/j.cell.2013.11.049] [Citation(s) in RCA: 582] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 11/14/2013] [Accepted: 12/24/2013] [Indexed: 12/22/2022]
Abstract
mTORC1 promotes cell growth in response to nutrients and growth factors. Insulin activates mTORC1 through the PI3K-Akt pathway, which inhibits the TSC1-TSC2-TBC1D7 complex (the TSC complex) to turn on Rheb, an essential activator of mTORC1. However, the mechanistic basis of how this pathway integrates with nutrient-sensing pathways is unknown. We demonstrate that insulin stimulates acute dissociation of the TSC complex from the lysosomal surface, where subpopulations of Rheb and mTORC1 reside. The TSC complex associates with the lysosome in a Rheb-dependent manner, and its dissociation in response to insulin requires Akt-mediated TSC2 phosphorylation. Loss of the PTEN tumor suppressor results in constitutive activation of mTORC1 through the Akt-dependent dissociation of the TSC complex from the lysosome. These findings provide a unifying mechanism by which independent pathways affecting the spatial recruitment of mTORC1 and the TSC complex to Rheb at the lysosomal surface serve to integrate diverse growth signals.
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Affiliation(s)
- Suchithra Menon
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Christian C Dibble
- Department of Systems Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
| | - George Talbott
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Gerta Hoxhaj
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Alexander J Valvezan
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Hidenori Takahashi
- Department of Systems Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Lewis C Cantley
- Department of Systems Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Brendan D Manning
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
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Santiago Lima AJ, Hoogeveen-Westerveld M, Nakashima A, Maat-Kievit A, van den Ouweland A, Halley D, Kikkawa U, Nellist M. Identification of regions critical for the integrity of the TSC1-TSC2-TBC1D7 complex. PLoS One 2014; 9:e93940. [PMID: 24714658 PMCID: PMC3979717 DOI: 10.1371/journal.pone.0093940] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 03/07/2014] [Indexed: 12/23/2022] Open
Abstract
The TSC1-TSC2-TBC1D7 complex is an important negative regulator of the mechanistic target of rapamycin complex 1 that controls cell growth in response to environmental cues. Inactivating TSC1 and TSC2 mutations cause tuberous sclerosis complex (TSC), an autosomal dominant disorder characterised by the occurrence of benign tumours in various organs and tissues, notably the brain, skin and kidneys. TBC1D7 mutations have not been reported in TSC patients but homozygous inactivation of TBC1D7 causes megaencephaly and intellectual disability. Here, using an exon-specific deletion strategy, we demonstrate that some regions of TSC1 are not necessary for the core function of the TSC1-TSC2 complex. Furthermore, we show that the TBC1D7 binding site is encoded by TSC1 exon 22 and identify amino acid residues involved in the TSC1-TBC1D7 interaction.
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Affiliation(s)
| | | | | | - Anneke Maat-Kievit
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ans van den Ouweland
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Dicky Halley
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ushio Kikkawa
- Biosignal Research Center, Kobe University, Kobe, Japan
| | - Mark Nellist
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
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138
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Wu J, Shin J, Xie D, Wang H, Gao J, Zhong XP. Tuberous sclerosis 1 promotes invariant NKT cell anergy and inhibits invariant NKT cell-mediated antitumor immunity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2014; 192:2643-50. [PMID: 24532578 PMCID: PMC3965184 DOI: 10.4049/jimmunol.1302076] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Development of effective immune therapies for cancer patients requires better understanding of hurdles that prevent the generation of effective antitumor immune responses. Administration of α-galactosylceramide (α-GalCer) in animals enhances antitumor immunity via activation of the invariant NKT (iNKT) cells. However, repeated injections of α-GalCer result in long-term unresponsiveness or anergy of iNKT cells, severely limiting its efficacy in tumor eradication. The mechanisms leading to iNKT cell anergy remain poorly understood. We report in this study that the tuberous sclerosis 1 (TSC1), a negative regulator of mTOR signaling, plays a crucial role in iNKT cell anergy. Deficiency of TSC1 in iNKT cells results in resistance to α-GalCer-induced anergy, manifested by increased expansion of and cytokine production by iNKT cells in response to secondary Ag stimulation. It is correlated with impaired upregulation of programmed death-1, Egr2, and Grail. Moreover, TSC1-deficient iNKT cells display enhanced antitumor immunity in a melanoma lung metastasis model. Our data suggest targeting TSC1/2 as a strategy for boosting antitumor immune therapy.
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Affiliation(s)
- Jinhong Wu
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
- Division of Pediatric Pulmonology, Department of Internal Medicine, Shanghai Children’s Medical Center affiliated with Shanghai Jiaotong University School of Medicine, Shanghai 200127, China
| | - Jinwook Shin
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
| | - Danli Xie
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
- School of Laboratory Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Hongxia Wang
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
- Laboratory Medicine Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Jimin Gao
- School of Laboratory Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Xiao-Ping Zhong
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
- Department of Immunology, Duke University Medical Center, Durham, NC 27710
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139
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Jacobs BL, Goodman CA, Hornberger TA. The mechanical activation of mTOR signaling: an emerging role for late endosome/lysosomal targeting. J Muscle Res Cell Motil 2014; 35:11-21. [PMID: 24162376 PMCID: PMC3981920 DOI: 10.1007/s10974-013-9367-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 10/18/2013] [Indexed: 01/03/2023]
Abstract
It is well recognized that mechanical signals play a critical role in the regulation of skeletal muscle mass, and the maintenance of muscle mass is essential for mobility, disease prevention and quality of life. Furthermore, over the last 15 years it has become established that signaling through a protein kinase called the mammalian (or mechanistic) target of rapamycin (mTOR) is essential for mechanically-induced changes in protein synthesis and muscle mass, however, the mechanism(s) via which mechanical stimuli regulate mTOR signaling have not been defined. Nonetheless, advancements are being made, and an emerging body of evidence suggests that the late endosome/lysosomal (LEL) system might play a key role in this process. Therefore, the purpose of this review is to summarize this body of evidence. Specifically, we will first explain why the Ras homologue enriched in brain (Rheb) and phosphatidic acid (PA) are considered to be direct activators of mTOR signaling. We will then describe the process of endocytosis and its involvement in the formation of LEL structures, as well as the evidence which indicates that mTOR and its direct activators (Rheb and PA) are all enriched at the LEL. Finally, we will summarize the evidence that has implicated the LEL in the regulation of mTOR by various growth regulatory inputs such as amino acids, growth factors and mechanical stimuli.
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Affiliation(s)
- Brittany L Jacobs
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI, 53706, USA
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140
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Miller R, DeCandio ML, Dixon-Mah Y, Giglio P, Vandergrift WA, Banik NL, Patel SJ, Varma AK, Das A. Molecular Targets and Treatment of Meningioma. JOURNAL OF NEUROLOGY AND NEUROSURGERY 2014; 1:1000101. [PMID: 25485306 PMCID: PMC4255716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Meningiomas are by far the most common tumors arising from the meninges. A myriad of aberrant signaling pathways involved with meningioma tumorigenesis, have been discovered. Understanding these disrupted pathways will aid in deciphering the relationship between various genetic changes and their downstream effects on meningioma pathogenesis. An understanding of the genetic and molecular profile of meningioma would provide a valuable first step towards developing more effective treatments for this intracranial tumor. Chromosomes 1, 10, 14, 22, their associated genes, and other potential targets have been linked to meningioma proliferation and progression. It is presumed that through an understanding of these genetic factors, more educated meningioma treatment techniques can be implemented. Future therapies will include combinations of targeted molecular agents including gene therapy, si-RNA mediation, proton therapy, and other approaches as a result of continued progress in the understanding of genetic and biological changes associated with meningiomas. This review provides an overview of the current knowledge of the genetic, signaling and molecular profile of meningioma and possible treatments strategies associated with such profiles.
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Affiliation(s)
- Rickey Miller
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA
| | - Michele L. DeCandio
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA
| | - Yaenette Dixon-Mah
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA
| | - Pierre Giglio
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA
| | - W Alex Vandergrift
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA
| | - Naren L. Banik
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA,Ralph H. Johnson VA Medical Center, Charleston, SC, USA
| | - Sunil. J. Patel
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA
| | - Abhay K. Varma
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA,Corresponding Authors: Arabinda Das and Abhay Varma, Department of Neurosciences (Divisions of Neurology and Neurosurgery) and MUSC Brain & Spine Tumor Program, Medical University of South Carolina, Charleston, SC, 29425, USA, ,
| | - Arabinda Das
- Department of Neurosciences (Divisions of Neurology and Neurosurgery) & MUSC Brain & Spine Tumor Program Medical University of South Carolina, Charleston, SC 29425, USA,Corresponding Authors: Arabinda Das and Abhay Varma, Department of Neurosciences (Divisions of Neurology and Neurosurgery) and MUSC Brain & Spine Tumor Program, Medical University of South Carolina, Charleston, SC, 29425, USA, ,
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141
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Dhara A, Eum JH, Robertson A, Gulia-Nuss M, Vogel KJ, Clark KD, Graf R, Brown MR, Strand MR. Ovary ecdysteroidogenic hormone functions independently of the insulin receptor in the yellow fever mosquito, Aedes aegypti. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1100-8. [PMID: 24076067 PMCID: PMC3885182 DOI: 10.1016/j.ibmb.2013.09.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 09/18/2013] [Accepted: 09/18/2013] [Indexed: 05/11/2023]
Abstract
Most mosquito species must feed on the blood of a vertebrate host to produce eggs. In the yellow fever mosquito, Aedes aegypti, blood feeding triggers medial neurosecretory cells in the brain to release insulin-like peptides (ILPs) and ovary ecdysteroidogenic hormone (OEH). Theses hormones thereafter directly induce the ovaries to produce ecdysteroid hormone (ECD), which activates the synthesis of yolk proteins in the fat body for uptake by oocytes. ILP3 stimulates ECD production by binding to the mosquito insulin receptor (MIR). In contrast, little is known about the mode of action of OEH, which is a member of a neuropeptide family called neuroparsin. Here we report that OEH is the only neuroparsin family member present in the Ae. aegypti genome and that other mosquitoes also encode only one neuroparsin gene. Immunoblotting experiments suggested that the full-length form of the peptide, which we call long OEH (lOEH), is processed into short OEH (sOEH). The importance of processing, however, remained unclear because a recombinant form of lOEH (rlOEH) and synthetic sOEH exhibited very similar biological activity. A series of experiments indicated that neither rlOEH nor sOEH bound to ILP3 or the MIR. Signaling studies further showed that ILP3 activated the MIR but rlOEH did not, yet both neuropeptides activated Akt, which is a marker for insulin pathway signaling. Our results also indicated that activation of TOR signaling in the ovaries required co-stimulation by amino acids and either ILP3 or rlOEH. Overall, we conclude that OEH activates the insulin signaling pathway independently of the MIR, and that insulin and TOR signaling in the ovaries is coupled.
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Affiliation(s)
- Animesh Dhara
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jai-Hoon Eum
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Anne Robertson
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Monika Gulia-Nuss
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Department of Entomology, Purdue University, West Lafayette, IN 47907, USA
| | - Kevin J. Vogel
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | | | - Rolf Graf
- Pancreatitis Research Laboratory DL 34, Rämistrasse 100, Universitätsspital Zürich, 8091 Zürich, Switzerland
| | - Mark R. Brown
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Corresponding authors: Tel.: 706-542-2816; fax: 706-542-2279, (M. R. Brown), (M. R. Strand)
| | - Michael R. Strand
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
- Corresponding authors: Tel.: 706-542-2816; fax: 706-542-2279, (M. R. Brown), (M. R. Strand)
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142
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Dibble CC, Manning BD. Signal integration by mTORC1 coordinates nutrient input with biosynthetic output. Nat Cell Biol 2013; 15:555-64. [PMID: 23728461 DOI: 10.1038/ncb2763] [Citation(s) in RCA: 544] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Flux through metabolic pathways is inherently sensitive to the levels of specific substrates and products, but cellular metabolism is also managed by integrated control mechanisms that sense the nutrient and energy status of a cell or organism. The mechanistic target of rapamycin complex 1 (mTORC1), a protein kinase complex ubiquitous to eukaryotic cells, has emerged as a critical signalling node that links nutrient sensing to the coordinated regulation of cellular metabolism. Here, we discuss the role of mTORC1 as a conduit between cellular growth conditions and the anabolic processes that promote cell growth. The emerging network of signalling pathways through which mTORC1 integrates systemic signals (secreted growth factors) with local signals (cellular nutrients - amino acids, glucose and oxygen - and energy, ATP) is detailed. Our expanding understanding of the regulatory network upstream of mTORC1 provides molecular insights into the integrated sensing mechanisms by which diverse cellular signals converge to control cell physiology.
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Affiliation(s)
- Christian C Dibble
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Systems Biology Department, Harvard Medical School, Boston, Massachusetts 02115, USA
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143
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A tuberous sclerosis complex signalling node at the peroxisome regulates mTORC1 and autophagy in response to ROS. Nat Cell Biol 2013; 15:1186-96. [PMID: 23955302 PMCID: PMC3789865 DOI: 10.1038/ncb2822] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 07/10/2013] [Indexed: 12/12/2022]
Abstract
Subcellular localization is emerging as an important mechanism for mTORC1 regulation. We report that the tuberous sclerosis complex (TSC) signaling node, TSC1, TSC2 and Rheb, localizes to peroxisomes, where it regulates mTORC1 in response to reactive oxygen species (ROS). TSC1 and TSC2 were bound by PEX19 and PEX5, respectively, and peroxisome-localized TSC functioned as a Rheb GAP to suppress mTORC1 and induce autophagy. Naturally occurring pathogenic mutations in TSC2 decreased PEX5 binding, abrogated peroxisome localization, Rheb GAP activity, and suppression of mTORC1 by ROS. Cells lacking peroxisomes were deficient in mTORC1 repression by ROS and peroxisome-localization deficient TSC2 mutants caused polarity defects and formation of multiple axons in neurons. These data identify a role for TSC in responding to ROS at the peroxisome, and identify the peroxisome as a signaling organelle involved in regulation of mTORC1.
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144
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Oppermann FS, Klammer M, Bobe C, Cox J, Schaab C, Tebbe A, Daub H. Comparison of SILAC and mTRAQ quantification for phosphoproteomics on a quadrupole orbitrap mass spectrometer. J Proteome Res 2013; 12:4089-100. [PMID: 23898821 DOI: 10.1021/pr400417g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Advances in mass spectrometric methodology and instrumentation have promoted a continuous increase in analytical performance in the field of phosphoproteomics. Here, we employed the recently introduced quadrupole Orbitrap (Q Exactive) mass spectrometer for quantitative signaling analysis to a depth of more than 15 000 phosphorylation sites. In parallel to the commonly used SILAC approach, we evaluated the nonisobaric chemical labeling reagent mTRAQ as an alternative quantification technique. Both enabled high phosphoproteome coverage in H3122 lung cancer cells. Replicate quantifications by mTRAQ identified almost as many significant phosphorylation changes upon treatment with ALK kinase inhibitor crizotinib as found by SILAC quantification. Overall, mTRAQ was slightly less precise than SILAC as evident from a somewhat higher variance of replicate phosphosite ratios. Direct comparison of SILAC- and mTRAQ-quantified phosphosites revealed that the majority of changes were detected by either quantification techniques, but also highlighted the aspect of false negative identifications in quantitative proteomics applications. Further inspection of crizotinib-regulated phosphorylation changes unveiled interference with multiple antioncogenic mechanisms downstream of ALK fusion kinase in H3122 cells. In conclusion, our results demonstrate a strong analytical performance of the Q Exactive in global phosphoproteomics, and establish mTRAQ quantification as a useful alternative to metabolic isotope labeling.
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Affiliation(s)
- Felix S Oppermann
- Evotec München GmbH, Am Klopferspitz 19a, 82152 Martinsried, Germany
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145
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Jung CH, Kim H, Ahn J, Jeon TI, Lee DH, Ha TY. Fisetin regulates obesity by targeting mTORC1 signaling. J Nutr Biochem 2013; 24:1547-54. [DOI: 10.1016/j.jnutbio.2013.01.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 01/03/2013] [Accepted: 01/08/2013] [Indexed: 01/08/2023]
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146
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Crystal structure of the yeast TSC1 core domain and implications for tuberous sclerosis pathological mutations. Nat Commun 2013; 4:2135. [DOI: 10.1038/ncomms3135] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 06/12/2013] [Indexed: 12/12/2022] Open
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147
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Hyun S. Body size regulation and insulin-like growth factor signaling. Cell Mol Life Sci 2013; 70:2351-65. [PMID: 23508807 PMCID: PMC11113471 DOI: 10.1007/s00018-013-1313-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 02/28/2013] [Accepted: 02/28/2013] [Indexed: 12/18/2022]
Abstract
How animals achieve their specific body size is a fundamental, but still largely unresolved, biological question. Over the past decades, studies on the insect model system have provided some important insights into the process of body size determination and highlighted the importance of insulin/insulin-like growth factor signaling. Fat body, the Drosophila counterpart of liver and adipose tissue, senses nutrient availability and controls larval growth rate by modulating peripheral insulin signaling. Similarly, insulin-like growth factor I produced from liver and muscle promotes postnatal body growth in mammals. Organismal growth is tightly coupled with the process of sexual maturation wherein the sex steroid hormone attenuates body growth. This review summarizes some important findings from Drosophila and mammalian studies that shed light on the general mechanism of animal size determination.
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Affiliation(s)
- Seogang Hyun
- Department of Biological Sciences, Chung-Ang University, Seoul, 156-756, Korea.
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148
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Jacobs BL, You JS, Frey JW, Goodman CA, Gundermann DM, Hornberger TA. Eccentric contractions increase the phosphorylation of tuberous sclerosis complex-2 (TSC2) and alter the targeting of TSC2 and the mechanistic target of rapamycin to the lysosome. J Physiol 2013; 591:4611-20. [PMID: 23732640 DOI: 10.1113/jphysiol.2013.256339] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The goal of this study was to determine whether the mechanical activation of mechanistic target of rapamycin (mTOR) signalling is associated with changes in phosphorylation of tuberous sclerosis complex-2 (TSC2) and targeting of mTOR and TSC2 to the lysosome. As a source of mechanical stimulation, mouse skeletal muscles were subjected to eccentric contractions (ECs). The results demonstrated that ECs induced hyper-phosphorylation of TSC2 and at least part of this increase occurred on residue(s) that fall within RxRxxS/T consensus motif(s). Furthermore, in control muscles, we found that both mTOR and TSC2 are highly enriched at the lysosome. Intriguingly, ECs enhanced the lysosomal association of mTOR and almost completely abolished the lysosomal association of TSC2. Based on these results, we developed a new model that could potentially explain how mechanical stimuli activate mTOR signalling. Furthermore, this is the first study to reveal that the activation of mTOR is associated with the translocation of TSC2 away from the lysosome. Since a large number of signalling pathways rely on TSC2 to control mTOR signalling, our results have potentially revealed a fundamental mechanism via which not only mechanical, but also various other types of stimuli, control mTOR signalling.
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Affiliation(s)
- Brittany L Jacobs
- T. A. Hornberger: Department of Comparative Biosciences, 2015 Linden Drive, Madison, WI 53706, USA.
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149
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Abstract
In recent years, several genetic and epigenetic alterations have been identified and linked with deregulated signaling pathways that promote growth and survival of lymphoma cells. These discoveries have raised hopes that a new era of targeted therapy will eventually improve treatment outcome of lymphoma. In this focused review, we summarize emerging preclinical and clinical data supporting the development of novel agents targeting B cell receptor signaling, phosphoinositol-3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) oncogenic pathways. Furthermore, we discuss new data on targeting chromatin modulating mechanisms.
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Affiliation(s)
- Lori A Leslie
- Division of Cancer Medicine, M. D. Anderson Cancer Center , Houston, TX , USA
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150
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Leto D, Uhm M, Williams A, Chen XW, Saltiel AR. Negative regulation of the RalGAP complex by 14-3-3. J Biol Chem 2013; 288:9272-83. [PMID: 23386617 DOI: 10.1074/jbc.m112.426106] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RGC1 and RGC2 comprise a functional RalGAP complex (RGC) that suppresses RalA activity. The PI3-kinase/Akt signaling pathway activates RalA through phosphorylation-mediated inhibition of the RGC. Here we identify a novel phosphorylation-dependent interaction between 14-3-3 and the RGC. 14-3-3 binds to the complex through an Akt-phosphorylated residue, threonine 715, on RGC2. Interaction with 14-3-3 does not alter in vitro activity of the GTPase-activating protein complex. However, blocking the interaction between 14-3-3 and RGC2 in cells increases suppression of RalA activity by the RGC, suggesting that 14-3-3 inhibits the complex through a non-catalytic mechanism. Together, these data show that 14-3-3 negatively regulates the RGC downstream of the PI3-kinase/Akt signaling pathway.
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Affiliation(s)
- Dara Leto
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
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