401
|
Xu K, Liu P, Wei W. mTOR signaling in tumorigenesis. Biochim Biophys Acta Rev Cancer 2014; 1846:638-54. [PMID: 25450580 DOI: 10.1016/j.bbcan.2014.10.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 10/23/2014] [Accepted: 10/25/2014] [Indexed: 12/25/2022]
Abstract
mTOR (the mechanistic target of rapamycin) is an atypical serine/threonine kinase involved in regulating major cellular functions including growth and proliferation. Deregulation of the mTOR signaling pathway is one of the most commonly observed pathological alterations in human cancers. To this end, oncogenic activation of the mTOR signaling pathway contributes to cancer cell growth, proliferation and survival, highlighting the potential for targeting the oncogenic mTOR pathway members as an effective anti-cancer strategy. In order to do so, a thorough understanding of the physiological roles of key mTOR signaling pathway components and upstream regulators would guide future targeted therapies. Thus, in this review, we summarize available genetic mouse models for mTORC1 and mTORC2 components, as well as characterized mTOR upstream regulators and downstream targets, and assign a potential oncogenic or tumor suppressive role for each evaluated molecule. Together, our work will not only facilitate the current understanding of mTOR biology and possible future research directions, but more importantly, provide a molecular basis for targeted therapies aiming at key oncogenic members along the mTOR signaling pathway.
Collapse
Affiliation(s)
- Kai Xu
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China; Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Pengda Liu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| |
Collapse
|
402
|
Li C, Zhang E, Sun Y, Lee PS, Zhan Y, Guo Y, Osorio JC, Rosas IO, Xu KF, Kwiatkowski DJ, Yu JJ. Rapamycin-insensitive up-regulation of adipocyte phospholipase A2 in tuberous sclerosis and lymphangioleiomyomatosis. PLoS One 2014; 9:e104809. [PMID: 25347447 PMCID: PMC4210122 DOI: 10.1371/journal.pone.0104809] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/14/2014] [Indexed: 11/18/2022] Open
Abstract
Tuberous sclerosis syndrome (TSC) is an autosomal dominant tumor suppressor gene syndrome affecting multiple organs, including renal angiomyolipomas and pulmonary lymphangioleiomyomatosis (LAM). LAM is a female-predominant interstitial lung disease characterized by the progressive cyst formation and respiratory failure, which is also seen in sporadic patients without TSC. Mutations in TSC1 or TSC2 cause TSC, result in hyperactivation of mammalian target of rapamycin (mTOR), and are also seen in LAM cells in sporadic LAM. We recently reported that prostaglandin biosynthesis and cyclooxygenase-2 were deregulated in TSC and LAM. Phospholipase A2 (PLA2) is the rate-limiting enzyme that catalyzes the conversion of plasma membrane phospholipids into prostaglandins. In this study, we identified upregulation of adipocyte AdPLA2 (PLA2G16) in LAM nodule cells using publicly available expression data. We showed that the levels of AdPLA2 transcript and protein were higher in LAM lungs compared with control lungs. We then showed that TSC2 negatively regulates the expression of AdPLA2, and loss of TSC2 is associated with elevated production of prostaglandin E2 (PGE2) and prostacyclin (PGI2) in cell culture models. Mouse model studies also showed increased expression of AdPLA2 in xenograft tumors, estrogen-induced lung metastatic lesions of Tsc2 null leiomyoma-derived cells, and spontaneous renal cystadenomas from Tsc2+/- mice. Importantly, rapamycin treatment did not affect the expression of AdPLA2 and the production of PGE2 by TSC2-deficient mouse embryonic fibroblast (Tsc2-/-MEFs), rat uterine leiomyoma-derived ELT3 cells, and LAM patient-associated renal angiomyolipoma-derived "mesenchymal" cells. Furthermore, methyl arachidonyl fluorophosphate (MAFP), a potent irreversible PLA2 inhibitor, selectively suppressed the growth and induced apoptosis of TSC2-deficient LAM patient-derived cells relative to TSC2-addback cells. Our findings suggest that AdPLA2 plays an important role in promoting tumorigenesis and disease progression by modulating the production of prostaglandins and may serve as a potential therapeutic target in TSC and LAM.
Collapse
Affiliation(s)
- Chenggang Li
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Erik Zhang
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yang Sun
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Po-Shun Lee
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | | | - Yanan Guo
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Juan C. Osorio
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ivan O. Rosas
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Kai-Feng Xu
- Peking Union Medical College, Beijing, China
| | - David J. Kwiatkowski
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jane J. Yu
- Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
403
|
Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway is a crucial cellular signaling hub that, like the nervous system itself, integrates internal and external cues to elicit critical outputs including growth control, protein synthesis, gene expression, and metabolic balance. The importance of mTOR signaling to brain function is underscored by the myriad disorders in which mTOR pathway dysfunction is implicated, such as autism, epilepsy, and neurodegenerative disorders. Pharmacological manipulation of mTOR signaling holds therapeutic promise and has entered clinical trials for several disorders. Here, we review the functions of mTOR signaling in the normal and pathological brain, highlighting ongoing efforts to translate our understanding of cellular physiology into direct medical benefit for neurological disorders.
Collapse
|
404
|
Liang N, Zhang C, Dill P, Panasyuk G, Pion D, Koka V, Gallazzini M, Olson EN, Lam H, Henske EP, Dong Z, Apte U, Pallet N, Johnson RL, Terzi F, Kwiatkowski DJ, Scoazec JY, Martignoni G, Pende M. Regulation of YAP by mTOR and autophagy reveals a therapeutic target of tuberous sclerosis complex. ACTA ACUST UNITED AC 2014; 211:2249-63. [PMID: 25288394 PMCID: PMC4203941 DOI: 10.1084/jem.20140341] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Liang et al. find that the tumor suppressors TSC1 and TSC2, defects in which underlie the genetic disease Tuberous Sclerosis Complex (TSC), drive the mTOR-dependent autophagosomal destruction of the transcriptional activator YAP. Blocking YAP inhibited the abnormal proliferation of TSC1/2-deficient human cells and reversed TSC-like disease symptoms in mosaic Tsc1 mutant mice. Genetic studies have shown that the tuberous sclerosis complex (TSC) 1–TSC2–mammalian target of Rapamycin (mTOR) and the Hippo–Yes-associated protein 1 (YAP) pathways are master regulators of organ size, which are often involved in tumorigenesis. The crosstalk between these signal transduction pathways in coordinating environmental cues, such as nutritional status and mechanical constraints, is crucial for tissue growth. Whether and how mTOR regulates YAP remains elusive. Here we describe a novel mouse model of TSC which develops renal mesenchymal lesions recapitulating human perivascular epithelioid cell tumors (PEComas) from patients with TSC. We identify that YAP is up-regulated by mTOR in mouse and human PEComas. YAP inhibition blunts abnormal proliferation and induces apoptosis of TSC1–TSC2-deficient cells, both in culture and in mosaic Tsc1 mutant mice. We further delineate that YAP accumulation in TSC1/TSC2-deficient cells is due to impaired degradation of the protein by the autophagosome/lysosome system. Thus, the regulation of YAP by mTOR and autophagy is a novel mechanism of growth control, matching YAP activity with nutrient availability under growth-permissive conditions. YAP may serve as a potential therapeutic target for TSC and other diseases with dysregulated mTOR activity.
Collapse
Affiliation(s)
- Ning Liang
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Chi Zhang
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Patricia Dill
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France Department of Pediatric Neurology and Developmental Medicine, University Children's Hospital Basel, University of Basel, 4056 Basel, Switzerland
| | - Ganna Panasyuk
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Delphine Pion
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Vonda Koka
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Morgan Gallazzini
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Eric N Olson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Hilaire Lam
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | - Elizabeth P Henske
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | - Zheng Dong
- Department of Cellular Biology and Anatomy, Georgia Health Sciences University and Charlie Norwood VA Medical Center, Augusta, Georgia, GA 30192
| | - Udayan Apte
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160
| | - Nicolas Pallet
- Institut National de la Santé et de la Recherche Médicale U775 and Université Paris Descartes, 75006 Paris, France Service de Néphrologie, Hôpital Européen Georges Pompidou, F-75015 Paris, France
| | - Randy L Johnson
- Department of Biochemistry and Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Fabiola Terzi
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - David J Kwiatkowski
- Translational Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | | | - Guido Martignoni
- Department of Pathology and Diagnostic, University of Verona, 37129 Verona, Italy Pederzoli Hospital, Peschiera, 37134 Verona, Italy
| | - Mario Pende
- Institut Necker-Enfants Malades, CS 61431, Paris, France Institut National de la Santé et de la Recherche Médicale, U1151, F-75014 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| |
Collapse
|
405
|
Saxena A, Sampson JR. Phenotypes associated with inherited and developmental somatic mutations in genes encoding mTOR pathway components. Semin Cell Dev Biol 2014; 36:140-6. [PMID: 25263008 DOI: 10.1016/j.semcdb.2014.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 09/12/2014] [Accepted: 09/18/2014] [Indexed: 11/29/2022]
Abstract
Mutations affecting the genes that encode upstream components in the mammalian (or mechanistic) target of rapamycin signalling pathway are associated with a group of rare inherited and developmental disorders that show overlapping clinical features. These include predisposition to a variety of benign or malignant tumours, localized overgrowth, developmental abnormalities of the brain, neurodevelopmental disorders and epilepsy. Many of these features have been linked to hyperactivation of signalling via mammalian target of rapamycin complex 1, suggesting that inhibitors of this complex such as rapamycin and its derivatives may offer new opportunities for therapy. In this review we describe this group of inherited and developmental disorders and discuss recent progress in their treatment via mTORC1 inhibition.
Collapse
Affiliation(s)
- Anurag Saxena
- Institute of Medical Genetics, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
| | - Julian R Sampson
- Institute of Medical Genetics, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| |
Collapse
|
406
|
Chantranupong L, Wolfson RL, Orozco JM, Saxton RA, Scaria SM, Bar-Peled L, Spooner E, Isasa M, Gygi SP, Sabatini DM. The Sestrins interact with GATOR2 to negatively regulate the amino-acid-sensing pathway upstream of mTORC1. Cell Rep 2014; 9:1-8. [PMID: 25263562 DOI: 10.1016/j.celrep.2014.09.014] [Citation(s) in RCA: 309] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/03/2014] [Accepted: 09/12/2014] [Indexed: 12/21/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) kinase is a major regulator of cell growth that responds to numerous environmental cues. A key input is amino acids, which act through the heterodimeric Rag GTPases (RagA or RagB bound to RagC or RagD) in order to promote the translocation of mTORC1 to the lysosomal surface, its site of activation. GATOR2 is a complex of unknown function that positively regulates mTORC1 signaling by acting upstream of or in parallel to GATOR1, which is a GTPase-activating protein (GAP) for RagA or RagB and an inhibitor of the amino-acid-sensing pathway. Here, we find that the Sestrins, a family of poorly understood growth regulators (Sestrin1-Sestrin3), interact with GATOR2 in an amino-acid-sensitive fashion. Sestrin2-mediated inhibition of mTORC1 signaling requires GATOR1 and the Rag GTPases, and the Sestrins regulate the localization of mTORC1 in response to amino acids. Thus, we identify the Sestrins as GATOR2-interacting proteins that regulate the amino-acid-sensing branch of the mTORC1 pathway.
Collapse
Affiliation(s)
- Lynne Chantranupong
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge MA 02142, USA
| | - Rachel L Wolfson
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge MA 02142, USA
| | - Jose M Orozco
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge MA 02142, USA
| | - Robert A Saxton
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge MA 02142, USA
| | - Sonia M Scaria
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Liron Bar-Peled
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge MA 02142, USA
| | - Eric Spooner
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Marta Isasa
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - David M Sabatini
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge MA 02142, USA.
| |
Collapse
|
407
|
Huang K, Fingar DC. Growing knowledge of the mTOR signaling network. Semin Cell Dev Biol 2014; 36:79-90. [PMID: 25242279 DOI: 10.1016/j.semcdb.2014.09.011] [Citation(s) in RCA: 225] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/05/2014] [Accepted: 09/10/2014] [Indexed: 12/14/2022]
Abstract
The kinase mTOR (mechanistic target of rapamycin) integrates diverse environmental signals and translates these cues into appropriate cellular responses. mTOR forms the catalytic core of at least two functionally distinct signaling complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). mTORC1 promotes anabolic cellular metabolism in response to growth factors, nutrients, and energy and functions as a master controller of cell growth. While significantly less well understood than mTORC1, mTORC2 responds to growth factors and controls cell metabolism, cell survival, and the organization of the actin cytoskeleton. mTOR plays critical roles in cellular processes related to tumorigenesis, metabolism, immune function, and aging. Consequently, aberrant mTOR signaling contributes to myriad disease states, and physicians employ mTORC1 inhibitors (rapamycin and analogs) for several pathological conditions. The clinical utility of mTOR inhibition underscores the important role of mTOR in organismal physiology. Here we review our growing knowledge of cellular mTOR regulation by diverse upstream signals (e.g. growth factors; amino acids; energy) and how mTORC1 integrates these signals to effect appropriate downstream signaling, with a greater emphasis on mTORC1 over mTORC2. We highlight dynamic subcellular localization of mTORC1 and associated factors as an important mechanism for control of mTORC1 activity and function. We will cover major cellular functions controlled by mTORC1 broadly. While significant advances have been made in the last decade regarding the regulation and function of mTOR within complex cell signaling networks, many important findings remain to be discovered.
Collapse
Affiliation(s)
- Kezhen Huang
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, United States
| | - Diane C Fingar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, United States; Division of Metabolism, Endocrinology, and Diabetes (MEND), Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-2200, United States.
| |
Collapse
|
408
|
Dunlop EA, Tee AR. mTOR and autophagy: a dynamic relationship governed by nutrients and energy. Semin Cell Dev Biol 2014; 36:121-9. [PMID: 25158238 DOI: 10.1016/j.semcdb.2014.08.006] [Citation(s) in RCA: 342] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/04/2014] [Accepted: 08/15/2014] [Indexed: 12/11/2022]
Abstract
Mechanistic target of rapamycin (mTOR) functions as a key homeostatic regulator of cell growth and orchestrates whether anabolic or catabolic reactions are favoured. mTOR complex 1 (mTORC1) manages multiple biosynthetic pathways and promotes cell growth when nutrients are in plentiful supply. Many advances have been made over the last decade on nutrient sensing centred on mTORC1. Recent research reveals that mTORC1 maintains nutrient homeostasis through lysosomal biogenesis and autophagic processes. Cells utilise autophagy to recycle damaged or unwanted organelles and macromolecules and in so doing, generate energy and recover precursor building blocks necessary for normal growth. It is clear that mTOR and autophagy are closely integrated within cells, where defects in signalling through both pathways are known to drive the onset of a range of human diseases, such as cancer and neurodegenerative disease. This review focuses on the dynamic signalling interplay between mTOR and autophagy, which is governed by a core set of proteins that sense nutrients at lysosomal membranes.
Collapse
Affiliation(s)
- E A Dunlop
- Institute of Cancer and Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
| | - A R Tee
- Institute of Cancer and Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| |
Collapse
|
409
|
Harputlugil E, Hine C, Vargas D, Robertson L, Manning BD, Mitchell JR. The TSC complex is required for the benefits of dietary protein restriction on stress resistance in vivo. Cell Rep 2014; 8:1160-70. [PMID: 25131199 PMCID: PMC4260622 DOI: 10.1016/j.celrep.2014.07.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 06/10/2014] [Accepted: 07/14/2014] [Indexed: 02/07/2023] Open
Abstract
Protein restriction (PR) is important for the benefits of dietary restriction on longevity and stress resistance, but relevant nutrient sensors and downstream effectors in mammals remain poorly defined. We used PR-mediated protection from hepatic ischemia reperfusion injury to probe genetic requirements for the evolutionarily conserved nutrient sensors GCN2 and mTORC1 in stress resistance. One week of PR reduced free amino acids and circulating growth factors, activating GCN2 and mTORC1 repressor tuberous sclerosis complex (TSC). However, although GCN2 was dispensable for PR-induced protection, hepatic TSC1 was required. PR improved hepatic insulin sensitivity in a TSC1-dependent manner prior to ischemia, facilitating increased prosurvival signaling and reduced apoptosis after reperfusion. These benefits were partially abrogated by pharmacological PI3K inhibition or genetic deletion of the insulin receptor in hepatocytes. In conclusion, improved insulin sensitivity upon short-term PR required TSC1, facilitated increased prosurvival signaling after injury, and contributed partially to PR-mediated resistance to clinically relevant ischemia reperfusion injury.
Collapse
Affiliation(s)
- Eylul Harputlugil
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - Christopher Hine
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - Dorathy Vargas
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - Lauren Robertson
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - Brendan D Manning
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA
| | - James R Mitchell
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA.
| |
Collapse
|
410
|
Abstract
The mammalian target of rapamycin (mTOR) pathway integrates multiple signals and regulates crucial cell functions via the molecular complexes mTORC1 and mTORC2. These complexes are functionally dependent on their raptor (mTORC1) or rictor (mTORC2) subunits. mTOR has been associated with oligodendrocyte differentiation and myelination downstream of the PI3K/Akt pathway, but the functional contributions of individual complexes are largely unknown. We show, by oligodendrocyte-specific genetic deletion of Rptor and/or Rictor in the mouse, that CNS myelination is mainly dependent on mTORC1 function, with minor mTORC2 contributions. Myelin-associated lipogenesis and protein gene regulation are strongly reliant on mTORC1. We found that also oligodendrocyte-specific overactivation of mTORC1, via ablation of tuberous sclerosis complex 1 (TSC1), causes hypomyelination characterized by downregulation of Akt signaling and lipogenic pathways. Our data demonstrate that a delicately balanced regulation of mTORC1 activation and action in oligodendrocytes is essential for CNS myelination, which has practical overtones for understanding CNS myelin disorders.
Collapse
|
411
|
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.
Collapse
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.
| |
Collapse
|
412
|
Zhang L, Tschumi BO, Corgnac S, Rüegg MA, Hall MN, Mach JP, Romero P, Donda A. Mammalian target of rapamycin complex 1 orchestrates invariant NKT cell differentiation and effector function. THE JOURNAL OF IMMUNOLOGY 2014; 193:1759-65. [PMID: 25015820 DOI: 10.4049/jimmunol.1400769] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Invariant NKT (iNKT) cells play critical roles in bridging innate and adaptive immunity. The Raptor containing mTOR complex 1 (mTORC1) has been well documented to control peripheral CD4 or CD8 T cell effector or memory differentiation. However, the role of mTORC1 in iNKT cell development and function remains largely unknown. By using mice with T cell-restricted deletion of Raptor, we show that mTORC1 is selectively required for iNKT but not for conventional T cell development. Indeed, Raptor-deficient iNKT cells are mostly blocked at thymic stage 1-2, resulting in a dramatic decrease of terminal differentiation into stage 3 and severe reduction of peripheral iNKT cells. Moreover, residual iNKT cells in Raptor knockout mice are impaired in their rapid cytokine production upon αGalcer challenge. Bone marrow chimera studies demonstrate that mTORC1 controls iNKT differentiation in a cell-intrinsic manner. Collectively, our data provide the genetic evidence that iNKT cell development and effector functions are under the control of mTORC1 signaling.
Collapse
Affiliation(s)
- Lianjun Zhang
- Translational Tumor Immunology Group, Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland
| | - Benjamin O Tschumi
- Translational Tumor Immunology Group, Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland
| | - Stéphanie Corgnac
- Translational Tumor Immunology Group, Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland
| | - Markus A Rüegg
- Biozentrum, University of Basel, 4003 Basel, Switzerland; and
| | - Michael N Hall
- Biozentrum, University of Basel, 4003 Basel, Switzerland; and
| | - Jean-Pierre Mach
- Department of Biochemistry, University of Lausanne, 1066 Epalinges, Switzerland
| | - Pedro Romero
- Translational Tumor Immunology Group, Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland
| | - Alena Donda
- Translational Tumor Immunology Group, Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland;
| |
Collapse
|
413
|
Abstract
Lysosomes are key cellular organelles that play a crucial role in catabolism by degrading extracellular and intracellular material. It is, therefore, very intriguing that mTORC1 (mechanistic target of rapamycin complex 1), a major promoter of anabolic processes, localizes in its active form to the surface of lysosomes. In recent years, many exciting observations have revealed a tightly regulated crosstalk between mTORC1 activity and lysosomal function. These findings highlight the complex regulatory network that modulates energy metabolism in cells.
Collapse
|
414
|
Aramburu J, Ortells MC, Tejedor S, Buxadé M, López-Rodríguez C. Transcriptional regulation of the stress response by mTOR. Sci Signal 2014; 7:re2. [PMID: 24985347 DOI: 10.1126/scisignal.2005326] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The kinase mammalian target of rapamycin (mTOR) is a central regulator of cell growth and proliferation that integrates inputs from growth factor receptors, nutrient availability, intracellular ATP (adenosine 5'-triphosphate), and a variety of stressors. Since early works in the mid-1990s uncovered the role of mTOR in stimulating protein translation, this kinase has emerged as a rather multifaceted regulator of numerous processes. Whereas mTOR is generally activated by growth- and proliferation-stimulating signals, its activity can be reduced and even suppressed when cells are exposed to a variety of stress conditions. However, cells can also adapt to stress while maintaining their growth capacity and mTOR function. Despite knowledge accumulated on how stress represses mTOR, less is known about mTOR influencing stress responses. In this review, we discuss the capability of mTOR, in particular mTOR complex 1 (mTORC1), to activate stress-responsive transcription factors, and we outline open questions for future investigation.
Collapse
Affiliation(s)
- Jose Aramburu
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain.
| | - M Carmen Ortells
- Centre for Genomic Regulation and Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Sonia Tejedor
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Maria Buxadé
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Cristina López-Rodríguez
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain.
| |
Collapse
|
415
|
Carroll B, Korolchuk VI, Sarkar S. Amino acids and autophagy: cross-talk and co-operation to control cellular homeostasis. Amino Acids 2014; 47:2065-88. [PMID: 24965527 DOI: 10.1007/s00726-014-1775-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 05/29/2014] [Indexed: 12/13/2022]
Abstract
Maintenance of amino acid homeostasis is important for healthy cellular function, metabolism and growth. Intracellular amino acid concentrations are dynamic; the high demand for protein synthesis must be met with constant dietary intake, followed by cellular influx, utilization and recycling of nutrients. Autophagy is a catabolic process via which superfluous or damaged proteins and organelles are delivered to the lysosome and degraded to release free amino acids into the cytoplasm. Furthermore, autophagy is specifically activated in response to amino acid starvation via two key signaling cascades: the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) and the general control nonderepressible 2 (GCN2) pathways. These pathways are key regulators of the integration between anabolic (amino acid depleting) and catabolic (such as autophagy which is amino acid replenishing) processes to ensure intracellular amino acid homeostasis. Here, we discuss the key roles that amino acids, along with energy (ATP, glucose) and oxygen, are playing in cellular growth and proliferation. We further explore how sophisticated methods are employed by cells to sense intracellular amino acid concentrations, how amino acids can act as a switch to dictate the temporal and spatial activation of anabolic and catabolic processes and how autophagy contributes to the replenishment of free amino acids, all to ensure cell survival. Relevance of these molecular processes to cellular and organismal physiology and pathology is also discussed.
Collapse
Affiliation(s)
- Bernadette Carroll
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK
| | - Viktor I Korolchuk
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK.
| | - Sovan Sarkar
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA, 02142, USA.
| |
Collapse
|
416
|
Dodd KM, Yang J, Shen MH, Sampson JR, Tee AR. mTORC1 drives HIF-1α and VEGF-A signalling via multiple mechanisms involving 4E-BP1, S6K1 and STAT3. Oncogene 2014; 34:2239-50. [PMID: 24931163 PMCID: PMC4172452 DOI: 10.1038/onc.2014.164] [Citation(s) in RCA: 219] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 04/28/2014] [Accepted: 05/01/2014] [Indexed: 01/17/2023]
Abstract
Recent clinical trials using rapalogues in tuberous sclerosis complex (TSC) show regression in volume of typically vascularised tumours including angiomyolipomas (AMLs) and sub-ependymal giant cell astrocytomas (SEGAs). By blocking mechanistic/mammalian target of rapamycin complex 1 (mTORC1) signalling, rapalogue efficacy is likely to occur in part through suppression of hypoxia inducible factors (HIFs) and vascular endothelial growth factors (VEGFs). We show that rapamycin reduces HIF-1α protein levels, and to a lesser extent VEGF-A levels, in renal cystadenoma cells in a Tsc2+/− mouse model. We establish that mTORC1 drives HIF-1α protein accumulation through enhanced transcription of HIF-1α mRNA, a process that is blocked by either inhibition or knockdown of signal transducer and activation of transcription 3 (STAT3). Furthermore, we demonstrate that STAT3 is directly phosphorylated by mTORC1 on Ser727 during hypoxia, promoting HIF-1α mRNA transcription. mTORC1 also regulates HIF-1α synthesis on a translational level via co-operative regulation of both initiation factor 4E-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase-1 (S6K1), whilst HIF-1α degradation remains unaffected. We therefore propose that mTORC1 drives HIF-1α synthesis in a multi-faceted manner through 4E-BP1/eIF4E, S6K1 and STAT3. Interestingly, we observe a disconnect between HIF-1α protein levels and VEGF-A expression. While both S6K1 and 4E-BP1 regulate HIF-1α translation, VEGF-A is primarily under the control of 4E-BP1/eIF4E. S6K1 inhibition reduces HIF-1α but not VEGF-A expression, suggesting that mTORC1 mediates VEGF-A expression via both HIF-1α-dependent and -independent mechanisms. Our work has important implications for the treatment of vascularised tumours, where mTORC1 acts as a central mediator of STAT3, HIF-1α, VEGF-A and angiogenesis via multiple signalling mechanisms.
Collapse
Affiliation(s)
- K M Dodd
- Institute of Cancer and Genetics, Cardiff University, Cardiff, UK
| | - J Yang
- Institute of Cancer and Genetics, Cardiff University, Cardiff, UK
| | - M H Shen
- Institute of Cancer and Genetics, Cardiff University, Cardiff, UK
| | - J R Sampson
- Institute of Cancer and Genetics, Cardiff University, Cardiff, UK
| | - A R Tee
- Institute of Cancer and Genetics, Cardiff University, Cardiff, UK
| |
Collapse
|
417
|
Recent progress in the study of the Rheb family GTPases. Cell Signal 2014; 26:1950-7. [PMID: 24863881 DOI: 10.1016/j.cellsig.2014.05.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 05/15/2014] [Indexed: 11/20/2022]
Abstract
In this review we highlight recent progress in the study of Rheb family GTPases. Structural studies using X-ray crystallography and NMR have given us insight into unique features of this GTPase. Combined with mutagenesis studies, these works have expanded our understanding of residues that affect Rheb GTP/GDP bound ratios, effector protein interactions, and stimulation of mTORC1 signaling. Analysis of cancer genome databases has revealed that several human carcinomas contain activating mutations of the protein. Rheb's role in activating mTORC1 signaling at the lysosome in response to stimuli has been further elucidated. Rheb has also been suggested to play roles in other cellular pathways including mitophagy and peroxisomal ROS response. A number of studies in mice have demonstrated the importance of Rheb in development, as well as in a variety of functions including cardiac protection and myelination. We conclude with a discussion of future prospects in the study of Rheb family GTPases.
Collapse
|
418
|
Takei N, Nawa H. mTOR signaling and its roles in normal and abnormal brain development. Front Mol Neurosci 2014; 7:28. [PMID: 24795562 PMCID: PMC4005960 DOI: 10.3389/fnmol.2014.00028] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/30/2014] [Indexed: 11/15/2022] Open
Abstract
Target of rapamycin (TOR) was first identified in yeast as a target molecule of rapamycin, an anti-fugal and immunosuppressant macrolide compound. In mammals, its orthologue is called mammalian TOR (mTOR). mTOR is a serine/threonine kinase that converges different extracellular stimuli, such as nutrients and growth factors, and diverges into several biochemical reactions, including translation, autophagy, transcription, and lipid synthesis among others. These biochemical reactions govern cell growth and cause cells to attain an anabolic state. Thus, the disruption of mTOR signaling is implicated in a wide array of diseases such as cancer, diabetes, and obesity. In the central nervous system, the mTOR signaling cascade is activated by nutrients, neurotrophic factors, and neurotransmitters that enhances protein (and possibly lipid) synthesis and suppresses autophagy. These processes contribute to normal neuronal growth by promoting their differentiation, neurite elongation and branching, and synaptic formation during development. Therefore, disruption of mTOR signaling may cause neuronal degeneration and abnormal neural development. While reduced mTOR signaling is associated with neurodegeneration, excess activation of mTOR signaling causes abnormal development of neurons and glia, leading to brain malformation. In this review, we first introduce the current state of molecular knowledge of mTOR complexes and signaling in general. We then describe mTOR activation in neurons, which leads to translational enhancement, and finally discuss the link between mTOR and normal/abnormal neuronal growth during development.
Collapse
Affiliation(s)
- Nobuyuki Takei
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Hiroyuki Nawa
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University Niigata, Japan
| |
Collapse
|
419
|
Demetriades C, Doumpas N, Teleman AA. Regulation of TORC1 in response to amino acid starvation via lysosomal recruitment of TSC2. Cell 2014; 156:786-99. [PMID: 24529380 DOI: 10.1016/j.cell.2014.01.024] [Citation(s) in RCA: 305] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 11/12/2013] [Accepted: 01/09/2014] [Indexed: 01/09/2023]
Abstract
TOR complex 1 (TORC1) is a potent anabolic regulator of cellular growth and metabolism. When cells have sufficient amino acids, TORC1 is active due to its lysosomal localization mediated via the Rag GTPases. Upon amino acid removal, the Rag GTPases release TORC1, causing it to become cytoplasmic and inactive. We show here that, upon amino acid removal, the Rag GTPases also recruit TSC2 to the lysosome, where it can act on Rheb. Only when both the Rag GTPases and Rheb are inactive is TORC1 fully released from the lysosome. Upon amino acid withdrawal, cells lacking TSC2 fail to completely release TORC1 from the lysosome, fail to completely inactivate TORC1, and fail to adjust physiologically to amino acid starvation. These data suggest that regulation of TSC2 subcellular localization may be a general mechanism to control its activity and place TSC2 in the amino-acid-sensing pathway to TORC1.
Collapse
|
420
|
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: 572] [Impact Index Per Article: 57.2] [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.
Collapse
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.
| |
Collapse
|
421
|
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: 28] [Impact Index Per Article: 2.8] [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.
Collapse
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
| |
Collapse
|
422
|
Bar-Peled L, Sabatini DM. Regulation of mTORC1 by amino acids. Trends Cell Biol 2014; 24:400-6. [PMID: 24698685 DOI: 10.1016/j.tcb.2014.03.003] [Citation(s) in RCA: 587] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/04/2014] [Accepted: 03/05/2014] [Indexed: 12/31/2022]
Abstract
The mechanistic target of rapamycin complex I (mTORC1) is a central regulator of cellular and organismal growth, and hyperactivation of this pathway is implicated in the pathogenesis of many human diseases including cancer and diabetes. mTORC1 promotes growth in response to the availability of nutrients, such as amino acids, which drive mTORC1 to the lysosomal surface, its site of activation. How amino acid levels are communicated to mTORC1 is only recently coming to light by the discovery of a lysosome-based signaling system composed of Rags (Ras-related GTPases) and Ragulator v-ATPase, GATOR (GAP activity towards Rags), and folliculin (FLCN) complexes. Increased understanding of this pathway will not only provide insight into growth control but also into the human pathologies triggered by its deregulation.
Collapse
Affiliation(s)
- Liron Bar-Peled
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, Nine Cambridge Center, Cambridge, MA 02142, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, Cambridge MA 02142, USA.
| |
Collapse
|
423
|
Abstract
The central role of phosphoinositide 3-kinase (PI3K) activation in tumour cell biology has prompted a sizeable effort to target PI3K and/or downstream kinases such as AKT and mammalian target of rapamycin (mTOR) in cancer. However, emerging clinical data show limited single-agent activity of inhibitors targeting PI3K, AKT or mTOR at tolerated doses. One exception is the response to PI3Kδ inhibitors in chronic lymphocytic leukaemia, where a combination of cell-intrinsic and -extrinsic activities drive efficacy. Here, we review key challenges and opportunities for the clinical development of inhibitors targeting the PI3K-AKT-mTOR pathway. Through a greater focus on patient selection, increased understanding of immune modulation and strategic application of rational combinations, it should be possible to realize the potential of this promising class of targeted anticancer agents.
Collapse
|
424
|
Abstract
Target of rapamycin (TOR) forms two conserved, structurally distinct kinase complexes termed TOR complex 1 (TORC1) and TORC2. Each complex phosphorylates a different set of substrates to regulate cell growth. In mammals, mTOR is stimulated by nutrients and growth factors and inhibited by stress to ensure that cells grow only during favorable conditions. Studies in different organisms have reported localization of TOR to several distinct subcellular compartments. Notably, the finding that mTORC1 is localized to the lysosome has significantly enhanced our understanding of mTORC1 regulation. Subcellular localization may be a general principle used by TOR to enact precise spatial and temporal control of cell growth.
Collapse
Affiliation(s)
- Charles Betz
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | | |
Collapse
|
425
|
Xie J, Proud CG. Signaling crosstalk between the mTOR complexes. ACTA ACUST UNITED AC 2014; 2:e28174. [PMID: 26779402 PMCID: PMC4705829 DOI: 10.4161/trla.28174] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/12/2014] [Accepted: 02/10/2014] [Indexed: 12/16/2022]
Abstract
mTOR is a protein kinase which integrates a variety of environmental and intracellular stimuli to positively regulate many anabolic processes of the cell, including protein synthesis. It exists within two highly conserved multi-protein complexes known as mTORC1 and 2 mTORC2. Each of these complexes phosphorylates different downstream targets, and play roles in different cellular functions. They also show distinctive sensitivity to the mTOR inhibitor rapamycin. Nevertheless, despite their biochemical and functional differences, recent studies have suggested that the regulation of these complexes is tightly linked to each other. For instance, both mTORC1 and 2 share some common upstream signaling molecules, such as PI3K and tuberous sclerosis complex TSC, which control their activation. Stimulation of the mTOR complexes may also trigger both positive and negative feedback mechanisms, which then in turn either further enhance or suppress their activation. Here, we summarize some recently discovered features relating to the crosstalk between mTORC1 and 2. We then discuss how aberrant mTOR complex crosstalk mechanisms may have an impact on the development of human diseases and drug resistance.
Collapse
Affiliation(s)
- Jianling Xie
- Centre for Biological Sciences; University of Southampton; Southampton, UK
| | - Chris G Proud
- Centre for Biological Sciences; University of Southampton; Southampton, UK
| |
Collapse
|
426
|
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.
Collapse
Affiliation(s)
- Brittany L Jacobs
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI, 53706, USA
| | | | | |
Collapse
|
427
|
A novel Hap1-Tsc1 interaction regulates neuronal mTORC1 signaling and morphogenesis in the brain. J Neurosci 2014; 33:18015-21. [PMID: 24227713 DOI: 10.1523/jneurosci.2290-13.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is a leading genetic cause of autism. The TSC proteins Tsc1 and Tsc2 control the mTORC1 signaling pathway in diverse cells, but how the mTORC1 pathway is specifically regulated in neurons remains to be elucidated. Here, using an interaction proteomics approach in neural cells including neurons, we uncover the brain-enriched protein huntingtin-associated protein 1 (Hap1) as a novel functional partner of Tsc1. Knockdown of Hap1 promotes specification of supernumerary axons in primary hippocampal neurons and profoundly impairs the positioning of pyramidal neurons in the mouse hippocampus in vivo. The Hap1 knockdown-induced phenotypes in primary neurons and in vivo recapitulate the phenotypes induced by Tsc1 knockdown. We also find that Hap1 knockdown in hippocampal neurons induces the downregulation of Tsc1 and stimulates the activity of mTORC1, as reflected by phosphorylation of the ribosomal protein S6. Inhibition of mTORC1 activity suppresses the Hap1 knockdown-induced polarity phenotype in hippocampal neurons. Collectively, these findings define a novel link between Hap1 and Tsc1 that regulates neuronal mTORC1 signaling and neuronal morphogenesis, with implications for our understanding of developmental disorders of cognition.
Collapse
|
428
|
Role of the mammalian target of rapamycin (mTOR) complexes in pancreatic β-cell mass regulation. VITAMINS AND HORMONES 2014; 95:425-69. [PMID: 24559928 DOI: 10.1016/b978-0-12-800174-5.00017-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Exquisite regulation of insulin secretion by pancreatic β-cells is essential to maintain metabolic homeostasis. β-Cell mass must be accordingly adapted to metabolic needs and can be largely modified under different situations. The mammalian target of rapamycin (mTOR) complexes has been consistently identified as key modulators of β-cell mass. mTOR can be found into two different complexes, mTORC1 and mTORC2. Under systemic insulin resistance, mTORC1/mTORC2 signaling in β-cells is needed to increase β-cell mass and insulin secretion. However, type 2 diabetes arises when these compensatory mechanisms fail, being the role of mTOR complexes still obscure in β-cell failure. In this chapter, we introduce the protein composition and regulation of mTOR complexes and their role in pancreatic β-cells. Furthermore, we describe their main signaling effectors through the review of numerous animal models, which indicate the essential role of mTORC1/mTORC2 in pancreatic β-cell mass regulation.
Collapse
|
429
|
Cuyàs E, Corominas-Faja B, Joven J, Menendez JA. Cell cycle regulation by the nutrient-sensing mammalian target of rapamycin (mTOR) pathway. Methods Mol Biol 2014; 1170:113-44. [PMID: 24906312 DOI: 10.1007/978-1-4939-0888-2_7] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell division involves a series of ordered and controlled events that lead to cell proliferation. Cell cycle progression implies not only demanding amounts of cell mass, protein, lipid, and nucleic acid content but also a favorable energy state. The mammalian target of rapamycin (mTOR), in response to the energy state, nutrient status, and growth factor stimulation of cells, plays a pivotal role in the coordination of cell growth and the cell cycle. Here, we review how the nutrient-sensing mTOR-signaling cascade molecularly integrates nutritional and mitogenic/anti-apoptotic cues to accurately coordinate cell growth and cell cycle. First, we briefly outline the structure, functions, and regulation of the mTOR complexes (mTORC1 and mTORC2). Second, we concisely evaluate the best known ability of mTOR to control G1-phase progression. Third, we discuss in detail the recent evidence that indicates a new genome stability caretaker function of mTOR based on the specific ability of phosphorylated forms of several mTOR-signaling components (AMPK, raptor, TSC, mTOR, and S6K1), which spatially and temporally associate with essential mitotic regulators at the mitotic spindle and at the cytokinetic cleavage furrow.
Collapse
Affiliation(s)
- Elisabet Cuyàs
- Metabolism & Cancer Group, Translational Research Laboratory, Catalan Institute of Oncology, Girona (ICO-Girona), Hospital Dr. Josep Trueta de Girona, Ctra. França s/n, E-17007, Girona, Catalonia, Spain
| | | | | | | |
Collapse
|
430
|
Kimball SR. Integration of signals generated by nutrients, hormones, and exercise in skeletal muscle. Am J Clin Nutr 2014; 99:237S-242S. [PMID: 24284445 PMCID: PMC3862457 DOI: 10.3945/ajcn.113.068387] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This review focuses on anabolic signaling pathways through which insulin, amino acids, and resistance exercise act to regulate the protein kinase complex referred to as mechanistic target of rapamycin complex (mTORC) 1. Initially, individual pathways through which the 3 anabolic signals act to modulate mTORC1 signaling will be discussed, followed by a summation of evidence showing an additive effect of the regulators. The emphasis will be on mTORC1 signaling in skeletal muscle and its contribution to modulation of rates of protein synthesis. In addition, results from studies using cells in culture will be used to provide a more complete picture of the molecular details of the individual pathways.
Collapse
Affiliation(s)
- Scot R Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA
| |
Collapse
|
431
|
Oshiro N, Rapley J, Avruch J. Amino acids activate mammalian target of rapamycin (mTOR) complex 1 without changing Rag GTPase guanyl nucleotide charging. J Biol Chem 2013; 289:2658-74. [PMID: 24337580 PMCID: PMC3908400 DOI: 10.1074/jbc.m113.528505] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Activation of mammalian target of rapamycin complex 1 (mTORC1) by amino acids is mediated in part by the Rag GTPases, which bind the raptor subunit of mTORC1 in an amino acid-stimulated manner and promote mTORC1 interaction with Rheb-GTP, the immediate activator. Here we examine whether the ability of amino acids to regulate mTORC1 binding to Rag and mTORC1 activation is due to the regulation of Rag guanyl nucleotide charging. Rag heterodimers in vitro exhibit a very rapid, spontaneous exchange of guanyl nucleotides and an inability to hydrolyze GTP. Mutation of the Rag P-loop corresponding to Ras(Ser-17) abolishes guanyl nucleotide binding. Such a mutation in RagA or RagB inhibits, whereas in RagC or RagD it enhances, Rag heterodimer binding to mTORC1. The binding of wild-type and mutant Rag heterodimers to mTORC1 in vitro parallels that seen with transient expression, but binding to mTORC1 in vitro is entirely independent of Rag guanyl nucleotide charging. HeLa cells stably overexpressing wild-type or P-loop mutant RagC exhibit unaltered amino acid regulation of mTORC1. Despite amino acid-independent raptor binding to Rag, mTORC1 is inhibited by amino acid withdrawal as in parental cells. Rag heterodimers extracted from (32)P-labeled whole cells, or just from the pool associated with the lysosomal membrane, exhibit constitutive [(32)P]GTP charging that is unaltered by amino acid withdrawal. Thus, amino acids promote mTORC1 activation without altering Rag GTP charging. Raptor binding to Rag, although necessary, is not sufficient for mTORC1 activation. Additional amino acid-dependent steps couple Rag-mTORC1 to Rheb-GTP.
Collapse
Affiliation(s)
- Noriko Oshiro
- From the Department of Molecular Biology and Diabetes Unit, Medical Services, Massachusetts General Hospital, Boston, Massachusetts 02114 and the Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115
| | | | | |
Collapse
|
432
|
Abstract
mTORC1 (mammalian target of rampamycin complex 1) is a highly conserved protein complex regulating cell growth and metabolism via its kinase mTOR (mammalian target of rapamycin). The activity of mTOR is under the control of various GTPases, of which Rheb and the Rags play a central role. The presence of amino acids is a strict requirement for mTORC1 activity. The heterodimeric Rag GTPases localize mTORC1 to lysosomes by their amino-acid-dependent interaction with the lysosomal Ragulator complex. Rheb is also thought to reside on lysosomes to activate mTORC1. Rheb is responsive to growth factors, but, in conjunction with PLD1 (phospholipase D1), is also an integral part of the machinery that stimulates mTORC1 in response to amino acids. In the present article, we provide a brief overview of novel mechanisms by which amino acids affect the function of Rags. On the basis of existing literature, we postulate that Rheb is activated at the Golgi from where it will travel to lysosomes. Maturation of endosomes into lysosomes may be required to assure a continuous supply of GTP-bound Rheb for mTORC1 activation, which may help to drive the maturation process.
Collapse
|
433
|
Lamb CA, Yoshimori T, Tooze SA. The autophagosome: origins unknown, biogenesis complex. Nat Rev Mol Cell Biol 2013; 14:759-74. [PMID: 24201109 DOI: 10.1038/nrm3696] [Citation(s) in RCA: 980] [Impact Index Per Article: 89.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Healthy cells use autophagy as a general 'housekeeping' mechanism and to survive stress, including stress induced by nutrient deprivation. Autophagy is initiated at the isolation membrane (originally termed the phagophore), and the coordinated action of ATG (autophagy-related) proteins results in the expansion of this membrane to form the autophagosome. Although the biogenesis of the isolation membrane and the autophagosome is complex and incompletely understood, insight has been gained into the molecular processes involved in initiating the isolation membrane, the source from which this originates (for example, it was recently proposed that the isolation membrane forms from the mitochondria-associated endoplasmic reticulum (ER) membrane (MAM)) and the role of ATG proteins and the vesicular trafficking machinery in autophagosome formation.
Collapse
|
434
|
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: 539] [Impact Index Per Article: 49.0] [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.
Collapse
Affiliation(s)
- Christian C Dibble
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Systems Biology Department, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | |
Collapse
|
435
|
Boronat S, Shaaya EA, Doherty CM, Caruso P, Thiele EA. Tuberous sclerosis complex without tubers and subependymal nodules: a phenotype-genotype study. Clin Genet 2013; 86:149-54. [PMID: 23909698 DOI: 10.1111/cge.12245] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/25/2013] [Accepted: 07/29/2013] [Indexed: 11/28/2022]
Abstract
Tuberous sclerosis complex (TSC) is caused by a mutation in the TSC1 or TSC2 genes. However, 15% of patients have no mutation identified. Tubers and subependymal nodules (SENs) are the typical brain lesions in TSC and are present in 90-95% of patients. The objective of this study is to characterize the specific genotype-phenotype of patients without these lesions. We analyzed the features of 11 patients without typical TSC neuroanatomic features. Ten had TSC1/TSC2 mutational analysis, which was negative. Clinically they had lesions thought to be of neural crest (NC) origin, such as hypomelanotic macules, facial angiofibromas, cardiac rhabdomyomas, angiomyolipomas, and lymphangioleiomyomatosis. We hypothesize that patients without tubers and SENs reflect mosaicism caused by a mutation in TSC1 or TSC2 in a NC cell during embryonic development. This may explain the negative results in TSC1 and TSC2 testing in DNA from peripheral leukocytes.
Collapse
Affiliation(s)
- S Boronat
- Department of Neurology, Herscot Center for TSC, Massachusetts General Hospital, Boston, MA, USA; Department of Pediatric Neurology, Vall d' Hebron Hospital, Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | | | | | | |
Collapse
|
436
|
Liu Y, Yan X, Zhou T. TBCK influences cell proliferation, cell size and mTOR signaling pathway. PLoS One 2013; 8:e71349. [PMID: 23977024 PMCID: PMC3747267 DOI: 10.1371/journal.pone.0071349] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 06/19/2013] [Indexed: 01/31/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) is a central regulator for both cell proliferation and cell growth; however, little is known about the regulation of mTOR expression at the transcriptional level. Here, we provide evidences that a conserved human protein TBCK (TBC1 domain containing kinase) is involved in the regulation of mTOR signaling pathway. Depletion of TBCK significantly inhibits cell proliferation, reduces cell size, and disrupts the organization of actin, but not microtubule. Knockdown of TBCK induces a significant decrease in the protein levels of components of mTOR complex (mTORC), and suppresses the activity of mTOR signaling, but not MAPK or PDK1/Akt pathway. Further results show that TBCK influences the expression of mTORC components at the transcriptional level. Thus, these data suggest that TBCK may play an important role in cell proliferation, cell growth and actin organization possibly by modulating mTOR pathway.
Collapse
Affiliation(s)
- Yueli Liu
- Department of Cell Biology and Program in Molecular Cell Biology, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | | | | |
Collapse
|
437
|
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.
Collapse
|
438
|
Anttila V, Winsvold BS, Gormley P, Kurth T, Bettella F, McMahon G, Kallela M, Malik R, de Vries B, Terwindt G, Medland SE, Todt U, McArdle WL, Quaye L, Koiranen M, Ikram MA, Lehtimäki T, Stam AH, Ligthart L, Wedenoja J, Dunham I, Neale BM, Palta P, Hamalainen E, Schürks M, Rose LM, Buring JE, Ridker PM, Steinberg S, Stefansson H, Jakobsson F, Lawlor DA, Evans DM, Ring SM, Färkkilä M, Artto V, Kaunisto MA, Freilinger T, Schoenen J, Frants RR, Pelzer N, Weller CM, Zielman R, Heath AC, Madden PA, Montgomery GW, Martin NG, Borck G, Göbel H, Heinze A, Heinze-Kuhn K, Williams FM, Hartikainen AL, Pouta A, van den Ende J, Uitterlinden AG, Hofman A, Amin N, Hottenga JJ, Vink JM, Heikkilä K, Alexander M, Muller-Myhsok B, Schreiber S, Meitinger T, Wichmann HE, Aromaa A, Eriksson JG, Traynor B, Trabzuni D, Rossin E, Lage K, Jacobs SB, Gibbs JR, Birney E, Kaprio J, Penninx BW, Boomsma DI, van Duijn C, Raitakari O, Jarvelin MR, Zwart JA, Cherkas L, Strachan DP, Kubisch C, Ferrari MD, van den Maagdenberg AM, Dichgans M, Wessman M, Smith GD, Stefansson K, Daly MJ, Nyholt DR, Chasman D, Palotie A. Genome-wide meta-analysis identifies new susceptibility loci for migraine. Nat Genet 2013; 45:912-917. [PMID: 23793025 PMCID: PMC4041123 DOI: 10.1038/ng.2676] [Citation(s) in RCA: 280] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 05/30/2013] [Indexed: 12/15/2022]
Abstract
Migraine is the most common brain disorder, affecting approximately 14% of the adult population, but its molecular mechanisms are poorly understood. We report the results of a meta-analysis across 29 genome-wide association studies, including a total of 23,285 individuals with migraine (cases) and 95,425 population-matched controls. We identified 12 loci associated with migraine susceptibility (P<5×10(-8)). Five loci are new: near AJAP1 at 1p36, near TSPAN2 at 1p13, within FHL5 at 6q16, within C7orf10 at 7p14 and near MMP16 at 8q21. Three of these loci were identified in disease subgroup analyses. Brain tissue expression quantitative trait locus analysis suggests potential functional candidate genes at four loci: APOA1BP, TBC1D7, FUT9, STAT6 and ATP5B.
Collapse
Affiliation(s)
- Verneri Anttila
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Analytical and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Bendik S. Winsvold
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- Department of Neurology, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Padhraig Gormley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Tobias Kurth
- INSERM Unit 708 – Neuroepidemiology, F-33000 Bordeaux, France
- University of Bordeaux, F-33000 Bordeaux, France
- Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA
| | | | - George McMahon
- MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Mikko Kallela
- Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland
| | - Rainer Malik
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilians-Universität, Munich, Germany
| | - Boukje de Vries
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Gisela Terwindt
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Sarah E. Medland
- Queensland Institute of Medical Research, Brisbane, Queensland, Australia
| | - Unda Todt
- Institute of Human Genetics, University of Ulm, Ulm, Germany
| | - Wendy L. McArdle
- MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Lydia Quaye
- Department of Twin Research and Genetic Epidemiology, King’s College London, London, UK
| | - Markku Koiranen
- Institute of Health Sciences, University of Oulu, Oulu, Finland
| | - M. Arfan Ikram
- Genetic Epidemiology Unit, Department of Epidemiology, Erasmus University Medical Center, Rotterdam, the Netherlands
- Department of Radiology Erasmus University Medical Centre, Rotterdam, The Netherlands
- Department of Neurology Erasmus University Medical Centre, Rotterdam, The Netherlands
| | - Terho Lehtimäki
- Department of Clinical Chemistry, Fimlab Laboratories and University of Tampere School of Medicine, Tampere, Finland
| | - Anine H. Stam
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Lannie Ligthart
- Department of Biological Psychology, VU University, Amsterdam, The Netherlands
- EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Juho Wedenoja
- Department of Public Health, Hjelt Institute, University of Helsinki, Helsinki, Finland
| | - Ian Dunham
- European Bioinformatics Insitute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Benjamin M. Neale
- Analytical and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Priit Palta
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Eija Hamalainen
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Markus Schürks
- Department of Neurology, University Hospital Essen, Essen, Germany
| | - Lynda M Rose
- Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA
| | - Julie E. Buring
- Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA
| | - Paul M. Ridker
- Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA
- Harvard Medical School, Boston, MA 02215, USA
| | | | | | - Finnbogi Jakobsson
- Department of Neurology, Landspitali University Hospital, Reykjavik, Iceland
| | - Debbie A. Lawlor
- MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - David M. Evans
- MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Susan M. Ring
- MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Markus Färkkilä
- Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland
| | - Ville Artto
- Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland
| | - Mari A Kaunisto
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Folkhälsan Research Center, Helsinki, Finland
| | - Tobias Freilinger
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilians-Universität, Munich, Germany
- Department of Neurology, Klinikum der Universität München, Munich, Germany
| | - Jean Schoenen
- Headache Research Unit, Department of Neurology and Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA)-Neurosciences, Liège University, Liège, Belgium
| | - Rune R. Frants
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Nadine Pelzer
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Claudia M. Weller
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Ronald Zielman
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Andrew C. Heath
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Pamela A.F. Madden
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | - Nicholas G. Martin
- Queensland Institute of Medical Research, Brisbane, Queensland, Australia
| | - Guntram Borck
- Institute of Human Genetics, University of Ulm, Ulm, Germany
| | | | - Axel Heinze
- Kiel Pain and Headache Center, Kiel, Germany
| | | | - Frances M.K. Williams
- Department of Twin Research and Genetic Epidemiology, King’s College London, London, UK
| | - Anna-Liisa Hartikainen
- Department of Clinical Sciences/Obstetrics and Gynecology, University Hospital of Oulu, Oulu, Finland
| | - Anneli Pouta
- Institute of Health Sciences, University of Oulu, Oulu, Finland
- Department of Clinical Sciences/Obstetrics and Gynecology, University Hospital of Oulu, Oulu, Finland
- Department of Children, Young People and Families, National Institute for Health and Welfare, Helsinki, Finland
| | - Joyce van den Ende
- Genetic Epidemiology Unit, Department of Epidemiology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | | | - Albert Hofman
- Genetic Epidemiology Unit, Department of Clinical Genetics, Erasmus University Medical Centre, Rotterdam, The Netherlands
| | - Najaf Amin
- Genetic Epidemiology Unit, Department of Epidemiology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jouke-Jan Hottenga
- Department of Biological Psychology, VU University, Amsterdam, The Netherlands
| | - Jacqueline M. Vink
- Department of Biological Psychology, VU University, Amsterdam, The Netherlands
| | - Kauko Heikkilä
- Department of Public Health, Hjelt Institute, University of Helsinki, Helsinki, Finland
| | - Michael Alexander
- Department of Genomics, Life & Brain Center, University of Bonn, Bonn, Germany
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Bertram Muller-Myhsok
- Max Planck Institute of Psychiatry, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Stefan Schreiber
- Department of Clinical Molecular Biology, Christian Albrechts University, Kiel, Germany
- Department of Internal Medicine I, Christian Albrechts University, Kiel, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Helmholtz Center Munich, Neuherberg, Germany
- Institute of Human Genetics, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Heinz Erich Wichmann
- Institut für Medizinische Informationsverarbeitung, Biometrie und Epidemiologie, Ludwig-Maximilians-Universität München, Munich, Germany
- Institute of Epidemiology I, HelmholtzCenter Munich, Neuherberg, Germany
- Klinikum Großhadern, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Arpo Aromaa
- National Institute for Health and Welfare, Helsinki, Finland
| | - Johan G. Eriksson
- Folkhälsan Research Center, Helsinki, Finland
- National Institute for Health and Welfare, Helsinki, Finland
- Department of General Practice, Helsinki University Central Hospital, Helsinki, Finland
- Vaasa Central Hospital, Vaasa, Finland
- Department of General Practice and Primary Health Care, University of Helsinki, Helsinki, Finland
| | - Bryan Traynor
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Daniah Trabzuni
- Department of Molecular Neuroscience, Institute of Neurology, University College London, London, UK
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | | | | | - Elizabeth Rossin
- Analytical and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA
| | - Kasper Lage
- Analytical and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Pediatric Surgical Research Laboratories, Massachusetts General Hospital for Children, Massachusetts General Hospital, Boston, MA, USA
- Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
- Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Suzanne B.R. Jacobs
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - J. Raphael Gibbs
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
- Department of Molecular Neuroscience, Institute of Neurology, University College London, London, UK
| | - Ewan Birney
- European Bioinformatics Insitute, Wellcome Trust Genome Campus, Cambridge, UK
| | - Jaakko Kaprio
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Department of Public Health, Hjelt Institute, University of Helsinki, Helsinki, Finland
- Department of Mental Health and Alcohol Research, National Institute for Health and Welfare, Helsinki, Finland
| | - Brenda W. Penninx
- EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands
- Department of Psychiatry, University Medical Center Groningen, Groningen, The Netherlands
- Department of Psychiatry, VU University Medical Center, Amsterdam, The Netherlands
| | - Dorret I. Boomsma
- Department of Biological Psychology, VU University, Amsterdam, The Netherlands
| | - Cornelia van Duijn
- Genetic Epidemiology Unit, Department of Epidemiology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Olli Raitakari
- Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku University Hospital, Turku, Finland
- Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku, Finland
| | - Marjo-Riitta Jarvelin
- Institute of Health Sciences, University of Oulu, Oulu, Finland
- Department of Children, Young People and Families, National Institute for Health and Welfare, Helsinki, Finland
- Department of Epidemiology and Biostatistics, School of Public Health, MRC-HPA Centre for Environment and Health, Faculty of Medicine, Imperial College, London, UK
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - John-Anker Zwart
- Department of Neurology, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Lynn Cherkas
- Department of Twin Research and Genetic Epidemiology, King’s College London, London, UK
| | - David P. Strachan
- Division of Population Health Sciences and Education, St George’s, University of London, London, UK
| | | | - Michel D. Ferrari
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Arn M.J.M. van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Martin Dichgans
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilians-Universität, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Maija Wessman
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Folkhälsan Research Center, Helsinki, Finland
| | - George Davey Smith
- MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Kari Stefansson
- deCODE genetics, Reykjavik, Iceland
- School of Medicine, University of Iceland, Reykjavik, Iceland
| | - Mark J. Daly
- Analytical and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Dale R. Nyholt
- Queensland Institute of Medical Research, Brisbane, Queensland, Australia
| | - Daniel Chasman
- Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA
- Harvard Medical School, Boston, MA 02215, USA
| | - Aarno Palotie
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| |
Collapse
|
439
|
Lim KC, Crino PB. Focal malformations of cortical development: new vistas for molecular pathogenesis. Neuroscience 2013; 252:262-76. [PMID: 23892008 DOI: 10.1016/j.neuroscience.2013.07.037] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/10/2013] [Accepted: 07/10/2013] [Indexed: 12/16/2022]
Abstract
Focal malformations of cortical development (FMCD) are highly associated with several neurological disorders including intractable epilepsy and neurocognitive disabilities. Over the past decade, several FMCD subtypes have been linked to hyperactivation of the mammalian target of rapamycin (mTOR) signaling cascade. In view of the roles that mTOR plays in cell proliferation, size, motility, and stem cell phenotype, many of the features of FMCD such as cytomegaly, disorganized lamination, and expression of stem cell markers can be explained by enhanced mTOR signaling. FMCD result from several distinct and fascinating molecular mechanisms including biallelic gene inactivation, somatic mutation, and potentially, viral infection. These mechanisms have been directly linked to mTOR activation. Perhaps most compelling, pharmacological inhibition of mTOR has been implemented successfully in clinical trials for select FMCD and provides a new vista for treatment.
Collapse
Affiliation(s)
- K-C Lim
- Department of Neurology, University of Pennsylvania Medical Center, Philadelphia, PA, United States
| | | |
Collapse
|
440
|
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
|
441
|
Prizant H, Sen A, Light A, Cho SN, DeMayo FJ, Lydon JP, Hammes SR. Uterine-specific loss of Tsc2 leads to myometrial tumors in both the uterus and lungs. Mol Endocrinol 2013; 27:1403-14. [PMID: 23820898 DOI: 10.1210/me.2013-1059] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a rare disease characterized by proliferation of abnormal smooth-muscle cells in the lungs, leading to functional loss and sometimes lung transplantation. Although the origin of LAM cells is unknown, several features of LAM provide clues. First, LAM cells contain inactivating mutations in genes encoding Tsc1 or Tsc2, proteins that limit mTORC1 activity. Second, LAM tumors recur after lung transplantation, suggesting a metastatic pathogenesis. Third, LAM is found almost exclusively in women. Finally, LAM shares features with uterine leiomyomas, benign tumors of myometrial cells. From these observations, we proposed that LAM cells might originate from uterine leiomyomas containing Tsc mutations. To test our hypothesis, and to develop mouse models for leiomyoma and LAM, we targeted Tsc2 deletion primarily in uterine cells. In fact, nearly 100% of uteri from uterine-specific Tsc2 knockout mice developed myometrial proliferation and uterine leiomyomas by 12 and 24 weeks, respectively. Myometrial proliferation and mTORC1/S6 activity were abrogated by the mTORC1 inhibitor rapamycin or by elimination of sex steroid production through ovariectomy or aromatase inhibition. In ovariectomized Tsc2 null mice, mTORC1/S6 activity and myometrial growth were restored by estrogen but not progesterone. Thus, even without Tsc2, estrogen appears to be required for myometrial mTORC1/S6 signaling and proliferation. Finally, we found Tsc2 null myometrial tumors in lungs of older Tsc2 uterine-specific knockout females, suggesting that lung LAM-like myometrial lesions may indeed originate from the uterus. This mouse model may improve our understanding of LAM and leiomyomas and might lead to novel therapeutic strategies for both diseases.
Collapse
Affiliation(s)
- Hen Prizant
- Division of Endocrinology and Metabolism, Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA
| | | | | | | | | | | | | |
Collapse
|
442
|
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.
Collapse
Affiliation(s)
- Brittany L Jacobs
- T. A. Hornberger: Department of Comparative Biosciences, 2015 Linden Drive, Madison, WI 53706, USA.
| | | | | | | | | | | |
Collapse
|
443
|
Kim SG, Buel GR, Blenis J. Nutrient regulation of the mTOR complex 1 signaling pathway. Mol Cells 2013; 35:463-73. [PMID: 23694989 PMCID: PMC3887879 DOI: 10.1007/s10059-013-0138-2] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 01/03/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionally conserved kinase which exists in two distinct structural and functional complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Of the two complexes, mTORC1 couples nutrient abundance to cell growth and proliferation by sensing and integrating a variety of inputs arising from amino acids, cellular stresses, energy status, and growth factors. Defects in mTORC1 regulation are implicated in the development of many metabolic diseases, including cancer and diabetes. Over the past decade, significant advances have been made in deciphering the complexity of the signaling processes contributing to mTORC1 regulation and function, but the mechanistic details are still not fully understood. In particular, how amino acid availability is sensed by cells and signals to mTORC1 remains unclear. In this review, we discuss the current understanding of nutrient-dependent control of mTORC1 signaling and will focus on the key components involved in amino acid signaling to mTORC1.
Collapse
Affiliation(s)
- Sang Gyun Kim
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115,
USA
| | - Gwen R. Buel
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115,
USA
| | - John Blenis
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115,
USA
| |
Collapse
|
444
|
Capo-Chichi JM, Tcherkezian J, Hamdan FF, Décarie JC, Dobrzeniecka S, Patry L, Nadon MA, Mucha BE, Major P, Shevell M, Bencheikh BOA, Joober R, Samuels ME, Rouleau GA, Roux PP, Michaud JL. Disruption of TBC1D7, a subunit of the TSC1-TSC2 protein complex, in intellectual disability and megalencephaly. J Med Genet 2013; 50:740-4. [DOI: 10.1136/jmedgenet-2013-101680] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
445
|
Fernández-Veledo S, Vázquez-Carballo A, Vila-Bedmar R, Ceperuelo-Mallafré V, Vendrell J. Role of energy- and nutrient-sensing kinases AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) in adipocyte differentiation. IUBMB Life 2013; 65:572-83. [PMID: 23671028 DOI: 10.1002/iub.1170] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/14/2013] [Indexed: 12/14/2022]
Abstract
Recent advances have demonstrated that the adipose tissue plays a central role in regulating overall energy balance. Obesity results from a chronic deregulation of energy balance, with energy intake exceeding energy expenditure. Recently, new mechanisms that control the obesity phenotype such as the equilibrium between white and brown adipose tissue function has been identified. In this context, it is becoming increasingly clear that in addition to cellular growth, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) also regulate lipid metabolism and adipogenesis. Here, we review recent advances in the understanding of the molecular mechanisms involved in white and brown differentiation programs focusing on AMPK and mTOR signaling pathways, which may play differential roles in white adipose tissue and brown adipose tissue development. In view of the worldwide epidemic of obesity and its associated metabolic disorders such as insulin resistance and type 2 diabetes, targeting these kinases may represent a potential approach for reducing adiposity and improving obesity-related diseases. © 2013 IUBMB Life, 65(7):572-583, 2013.
Collapse
Affiliation(s)
- Sonia Fernández-Veledo
- Research Unit, Hospital Universitari de Tarragona Joan XXIII. IISPV. Universitat Rovira i Virgili, Tarragona, Spain
| | | | | | | | | |
Collapse
|
446
|
Laplante M, Sabatini DM. Regulation of mTORC1 and its impact on gene expression at a glance. J Cell Sci 2013; 126:1713-9. [PMID: 23641065 DOI: 10.1242/jcs.125773] [Citation(s) in RCA: 437] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mechanistic (or mammalian) target of rapamycin (mTOR) is a kinase that regulates key cellular functions linked to the promotion of cell growth and metabolism. This kinase, which is part of two protein complexes termed mTOR complex 1 (mTORC1) and 2 (mTORC2), has a fundamental role in coordinating anabolic and catabolic processes in response to growth factors and nutrients. Of the two mTOR complexes, mTORC1 is by far the best characterized. When active, mTORC1 triggers cell growth and proliferation by promoting protein synthesis, lipid biogenesis, and metabolism, and by reducing autophagy. The fact that mTORC1 deregulation is associated with several human diseases, such as type 2 diabetes, cancer, obesity and neurodegeneration, highlights its importance in the maintenance of cellular homeostasis. Over the last years, several groups observed that mTORC1 inhibition, in addition to reducing protein synthesis, deeply affects gene transcription. Here, we review the connections between mTORC1 and gene transcription by focusing on its impact in regulating the activation of specific transcription factors including including STAT3, SREBPs, PPARγ, PPARα, HIF1α, YY1–PGC1α and TFEB. We also discuss the importance of these transcription factors in mediating the effects of mTORC1 on various cellular processes in physiological and pathological contexts.
Collapse
Affiliation(s)
- Mathieu Laplante
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, 2725 Chemin Ste-Foy, Québec, QC, G1V 4G5, Canada.
| | | |
Collapse
|
447
|
Guenther GG, Liu G, Ramirez MU, McMonigle RJ, Kim SM, McCracken AN, Joo Y, Ushach I, Nguyen NL, Edinger AL. Loss of TSC2 confers resistance to ceramide and nutrient deprivation. Oncogene 2013; 33:1776-87. [PMID: 23604129 DOI: 10.1038/onc.2013.139] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 02/22/2013] [Accepted: 03/19/2013] [Indexed: 12/29/2022]
Abstract
Nutrient stress that produces quiescence and catabolism in normal cells is lethal to cancer cells, because oncogenic mutations constitutively drive anabolism. One driver of biosynthesis in cancer cells is the mammalian target of rapamycin complex 1 (mTORC1) signaling complex. Activating mTORC1 by deleting its negative regulator tuberous sclerosis complex 2 (TSC2) leads to hypersensitivity to glucose deprivation. We have previously shown that ceramide kills cells in part by triggering nutrient transporter loss and restricting access to extracellular amino acids and glucose, suggesting that TSC2-deficient cells would be hypersensitive to ceramide. However, murine embryonic fibroblasts (MEFs) lacking TSC2 were highly resistant to ceramide-induced death. Consistent with the observation that ceramide limits access to both amino acids and glucose, TSC2(-/-) MEFs also had a survival advantage when extracellular amino acids and glucose were both reduced. As TSC2(-/-) MEFs were resistant to nutrient stress despite sustained mTORC1 activity, we assessed whether mTORC1 signaling might be beneficial under these conditions. In low amino acid and glucose medium, and following ceramide-induced nutrient transporter loss, elevated mTORC1 activity significantly enhanced the adaptive upregulation of new transporter proteins for amino acids and glucose. Strikingly, the introduction of oncogenic Ras abrogated the survival advantage of TSC2(-/-) MEFs upon ceramide treatment most likely by increasing nutrient demand. These results suggest that, in the absence of oncogene-driven biosynthetic demand, mTORC1-dependent translation facilitates the adaptive cellular response to nutrient stress.
Collapse
Affiliation(s)
- G G Guenther
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - G Liu
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - M U Ramirez
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - R J McMonigle
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - S M Kim
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - A N McCracken
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Y Joo
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - I Ushach
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - N L Nguyen
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - A L Edinger
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| |
Collapse
|
448
|
Bissler JJ, Kingswood JC, Radzikowska E, Zonnenberg BA, Frost M, Belousova E, Sauter M, Nonomura N, Brakemeier S, de Vries PJ, Whittemore VH, Chen D, Sahmoud T, Shah G, Lincy J, Lebwohl D, Budde K. Everolimus for angiomyolipoma associated with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis (EXIST-2): a multicentre, randomised, double-blind, placebo-controlled trial. Lancet 2013; 381:817-24. [PMID: 23312829 DOI: 10.1016/s0140-6736(12)61767-x] [Citation(s) in RCA: 574] [Impact Index Per Article: 52.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Angiomyolipomas are slow-growing tumours associated with constitutive activation of mammalian target of rapamycin (mTOR), and are common in patients with tuberous sclerosis complex and sporadic lymphangioleiomyomatosis. The insidious growth of these tumours predisposes patients to serious complications including retroperitoneal haemorrhage and impaired renal function. Everolimus, a rapamycin derivative, inhibits the mTOR pathway by acting on the mTOR complex 1. We compared the angiomyolipoma response rate on everolimus with placebo in patients with tuberous sclerosis or sporadic lymphanioleiomyomatosis-associated angiomyolipomata. METHODS In this double-blind, placebo-controlled, phase 3 trial, patients aged 18 years or older with at least one angiomyolipoma 3 cm or larger in its longest diameter (defined by radiological assessment) and a definite diagnosis of tuberous sclerosis or sporadic lymphangioleiomyomatosis were randomly assigned, in a 2:1 fashion with the use of an interactive web response system, to receive oral everolimus 10 mg per day or placebo. The primary efficacy endpoint was the proportion of patients with confirmed angiomyolipoma response of at least a 50% reduction in total volume of target angiomyolipomas relative to baseline. This study is registered with ClinicalTrials.gov number NCT00790400. RESULTS 118 patients (median age 31·0 years; IQR 18·0–61·0) from 24 centres in 11 countries were randomly assigned to receive everolimus (n=79) or placebo (n=39). At the data cutoff, double-blind treatment was ongoing for 98 patients; two main reasons for discontination were disease progression (nine placebo patients) followed by adverse events (two everolimus patients; four placebo patients). The angiomyolipoma response rate was 42% (33 of 79 [95% CI 31–53%]) for everolimus and 0% (0 of 39 [0–9%]) for placebo (response rate difference 42% [24–58%]; one-sided Cochran-Mantel-Haenszel test p<0·0001). The most common adverse events in the everolimus and placebo groups were stomatitis (48% [38 of 79], 8% [3 of 39], respectively), nasopharyngitis (24% [19 of 79] and 31% [12 of 39]), and acne-like skin lesions (22% [17 of 79] and 5% [2 of 39]). INTERPRETATION Everolimus reduced angiomyolipoma volume with an acceptable safety profile, suggesting it could be a potential treatment for angiomyolipomas associated with tuberous sclerosis. FUNDING Novartis Pharmaceuticals.
Collapse
Affiliation(s)
- John J Bissler
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229-3039, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
449
|
Jewell JL, Guan KL. Nutrient signaling to mTOR and cell growth. Trends Biochem Sci 2013; 38:233-42. [PMID: 23465396 DOI: 10.1016/j.tibs.2013.01.004] [Citation(s) in RCA: 274] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 01/03/2013] [Accepted: 01/08/2013] [Indexed: 12/25/2022]
Abstract
The mammalian target of rapamycin (mTOR) is a conserved protein kinase involved in a multitude of cellular processes including cell growth. Increased mTOR activation is observed in multiple human cancers and inhibition of mTOR has proven efficacious in numerous clinical trials. mTOR comprises two complexes, termed mTORC1 and mTORC2. Both complexes respond to growth factors, whereas only mTORC1 is controlled by nutrients, such as glucose and amino acids. Since the discovery of mTOR, extensive studies have intricately detailed the molecular mechanisms by which mTORC1 is regulated. Somewhat paradoxically, amino acid (AA)-induced mTORC1 activation -arguably the most essential stimulus leading to mTORC1 activation - is the least understood. Here we review the current knowledge of nutrient-dependent regulation of mTORC1.
Collapse
Affiliation(s)
- Jenna L Jewell
- Department of Pharmacology and Moores Cancer Center, University of California at San Diego, La Jolla, CA 92093, USA
| | | |
Collapse
|
450
|
Crino PB. Evolving neurobiology of tuberous sclerosis complex. Acta Neuropathol 2013; 125:317-32. [PMID: 23386324 DOI: 10.1007/s00401-013-1085-x] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 01/14/2013] [Accepted: 01/19/2013] [Indexed: 11/30/2022]
Abstract
Over the past decade, there have been numerous advances in our understanding of the molecular pathogenesis of tuberous sclerosis complex (TSC). Following the identification of the TSC1 and TSC2 genes, a link to regulatory control of the mammalian target of rapamycin (mTOR) signaling pathway has paved the way for new therapeutic interventions, and now even approved therapies for TSC. Gene identification has permitted establishment of cell lines and conditional knockout mouse strains to assay how abnormalities in brain structure lead to enhanced excitability, seizures, cognitive disabilities, and other neuropsychological disorders in TSC. Furthermore, work in in vitro systems and analysis of rodent models and human tissue has allowed investigators to study how brain lesions form in TSC. Evolving questions over the next decade include understanding the high clinical variability of TSC, defining why there is a lack of clear genotype-phenotype correlations, and identifying biomarkers for prognosis and stratification. The study of TSC has in many ways reflected a paradigm "bench-to-bedside" success story that serves as a model of many other neurological disorders.
Collapse
Affiliation(s)
- Peter B Crino
- Department of Neurology, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, 6th Floor Medical Education and Research Building, 3500N. Broad Street, Philadelphia, PA 19140-4106, USA.
| |
Collapse
|