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Marker-free co-selection for successive rounds of prime editing in human cells. Nat Commun 2022; 13:5909. [PMID: 36207338 PMCID: PMC9546848 DOI: 10.1038/s41467-022-33669-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 09/27/2022] [Indexed: 11/18/2022] Open
Abstract
Prime editing enables the introduction of precise point mutations, small insertions, or short deletions without requiring donor DNA templates. However, efficiency remains a key challenge in a broad range of human cell types. In this work, we design a robust co-selection strategy through coediting of the ubiquitous and essential sodium/potassium pump (Na+/K+ ATPase). We readily engineer highly modified pools of cells and clones with homozygous modifications for functional studies with minimal pegRNA optimization. This process reveals that nicking the non-edited strand stimulates multiallelic editing but often generates tandem duplications and large deletions at the target site, an outcome dictated by the relative orientation of the protospacer adjacent motifs. Our approach streamlines the production of cell lines with multiple genetic modifications to create cellular models for biological research and lays the foundation for the development of cell-type specific co-selection strategies. Prime editing enables the introduction of precise point mutations, small insertions, or short deletions without requiring donor DNA templates. Here the authors develop a co-selection strategy to facilitate prime editing in human cells and provide design principles to prevent the formation of undesired editing byproducts at the target site.
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2
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Ito K, Nagata K, Ohta S, Matsuda Y, Ukai T, Yasuda I, Ota A, Kobayashi R, Kabata M, Sankoda N, Maeda T, Woltjen K, Yang L, Maruyama R, Katayama R, Yamamoto T, Yamada Y. The oncogene-dependent resistance to reprogramming unveils cancer therapeutic targets. Cell Rep 2022; 39:110721. [PMID: 35476996 DOI: 10.1016/j.celrep.2022.110721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 12/01/2021] [Accepted: 03/31/2022] [Indexed: 11/03/2022] Open
Abstract
The resistance to transcription factor-mediated reprogramming into pluripotent stem cells is one of the distinctive features of cancer cells. Here we dissect the profiles of reprogramming factor binding and the subsequent transcriptional response in cancer cells to reveal its underlying mechanisms. Using clear cell sarcomas (CCSs), we show that the driver oncogene EWS/ATF1 misdirects the reprogramming factors to cancer-specific enhancers and thereby impairs the transcriptional response toward pluripotency that is otherwise provoked. Sensitization to the reprogramming cue is observed in other cancer types when the corresponding oncogenic signals are pharmacologically inhibited. Exploiting this oncogene dependence of the transcriptional "stiffness," we identify mTOR signaling pathways downstream of EWS/ATF1 and discover that inhibiting mTOR activity substantially attenuates the propagation of CCS cells in vitro and in vivo. Our results demonstrate that the early transcriptional response to cell fate perturbations can be a faithful readout to identify effective therapeutics targets in cancer cells.
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Affiliation(s)
- Kenji Ito
- Division of Stem Cell Pathology, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Kohei Nagata
- Division of Stem Cell Pathology, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan; Third Department of Internal Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Sho Ohta
- Division of Stem Cell Pathology, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan.
| | - Yutaka Matsuda
- Research Division, Chugai Pharmaceutical Co., Ltd., Kanagawa 247-8530, Japan
| | - Tomoyo Ukai
- Division of Stem Cell Pathology, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Ichiro Yasuda
- Third Department of Internal Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Akira Ota
- Department of Fundamental Cell Technology, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan
| | - Ryota Kobayashi
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan
| | - Mio Kabata
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan
| | - Nao Sankoda
- Division of Stem Cell Pathology, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Shizuoka 431-3192, Japan
| | - Knut Woltjen
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan
| | - Liying Yang
- Project for Cancer Epigenomics, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Reo Maruyama
- Project for Cancer Epigenomics, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Ryohei Katayama
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Takuya Yamamoto
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan; AMED-CREST, AMED, Tokyo 100-0004, Japan; Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto 606-8501, Japan; Medical-risk Avoidance Based on iPS Cells Team, RIKEN Center for Advanced Intelligence Project (AIP), Kyoto 606-8507, Japan
| | - Yasuhiro Yamada
- Division of Stem Cell Pathology, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan; AMED-CREST, AMED, Tokyo 100-0004, Japan.
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3
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Kapur P, Gao M, Zhong H, Chintalapati S, Mitui M, Barnes S, Zhou Q, Miyata J, Carrillo D, Malladi V, Rakheja D, Pedrosa I, Xu L, Kinch L, Brugarolas J. Germline and sporadic mTOR pathway mutations in low-grade oncocytic tumor of the kidney. Mod Pathol 2022; 35:333-343. [PMID: 34538873 PMCID: PMC9817016 DOI: 10.1038/s41379-021-00896-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 01/11/2023]
Abstract
Low-grade oncocytic tumor (LOT) of the kidney is a recently described entity with poorly understood pathogenesis. Using next-generation sequencing (NGS) and complementary approaches, we provide insight into its biology. We describe 22 LOT corresponding to 7 patients presenting with a median age of 75 years (range 63-86 years) and male to female ratio 2:5. All 22 tumors demonstrated prototypical microscopic features. Tumors were well-circumscribed and solid. They were composed of sheets of tumor cells in compact nests. Tumor cells had eosinophilic cytoplasm, round to oval nuclei (without nuclear membrane irregularities), focal subtle perinuclear halos, and occasional binucleation. Sharply delineated edematous stromal islands were often observed. Tumor cells were positive for PAX8, negative for CD117, and exhibited diffuse and strong cytokeratin-7 expression. Six patients presented with pT1 tumors. At a median follow-up of 29 months, four patients were alive without recurrence (three patients had died from unrelated causes). All tumors were originally classified as chromophobe renal cell carcinoma, eosinophilic variant (chRCC-eo). While none of the patients presented with known syndromic features, one patient with multiple bilateral LOTs was subsequently found to have a likely pathogenic germline TSC1 mutation. Somatic, likely activating, mutations in MTOR and RHEB were identified in all other evaluable LOTs. As assessed by phospho-S6 and phospho-4E-BP1, mTOR complex 1 (mTORC1) was activated across all cases but to different extent. MTOR mutant LOT exhibited lower levels of mTORC1 activation, possibly related to mTORC1 dimerization and the preservation of a wild-type MTOR copy (retained chromosome 1). Supporting its distinction from related entities, gene expression analyses showed that LOT clustered separately from classic chRCC, chRCC-eo, and RO. In summary, converging mTORC1 pathway mutations, mTORC1 complex activation, and a distinctive gene expression signature along with characteristic phenotypic features support LOT designation as a distinct entity with both syndromic and non-syndromic cases associated with an indolent course.
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Affiliation(s)
- Payal Kapur
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Ming Gao
- Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Department of Hematology-Oncology Division of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Hua Zhong
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Suneetha Chintalapati
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Midori Mitui
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Spencer Barnes
- Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Qinbo Zhou
- Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Jeffrey Miyata
- Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Department of Hematology-Oncology Division of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Deyssy Carrillo
- Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Department of Hematology-Oncology Division of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Venkat Malladi
- Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Dinesh Rakheja
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Ivan Pedrosa
- Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Lin Xu
- Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - Lisa Kinch
- Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - James Brugarolas
- Kidney Cancer Program at Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Hematology-Oncology Division of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Vasic V, Jones MSO, Haslinger D, Knaus LS, Schmeisser MJ, Novarino G, Chiocchetti AG. Translating the Role of mTOR- and RAS-Associated Signalopathies in Autism Spectrum Disorder: Models, Mechanisms and Treatment. Genes (Basel) 2021; 12:genes12111746. [PMID: 34828352 PMCID: PMC8624393 DOI: 10.3390/genes12111746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/25/2021] [Accepted: 10/28/2021] [Indexed: 12/23/2022] Open
Abstract
Mutations affecting mTOR or RAS signaling underlie defined syndromes (the so-called mTORopathies and RASopathies) with high risk for Autism Spectrum Disorder (ASD). These syndromes show a broad variety of somatic phenotypes including cancers, skin abnormalities, heart disease and facial dysmorphisms. Less well studied are the neuropsychiatric symptoms such as ASD. Here, we assess the relevance of these signalopathies in ASD reviewing genetic, human cell model, rodent studies and clinical trials. We conclude that signalopathies have an increased liability for ASD and that, in particular, ASD individuals with dysmorphic features and intellectual disability (ID) have a higher chance for disruptive mutations in RAS- and mTOR-related genes. Studies on rodent and human cell models confirm aberrant neuronal development as the underlying pathology. Human studies further suggest that multiple hits are necessary to induce the respective phenotypes. Recent clinical trials do only report improvements for comorbid conditions such as epilepsy or cancer but not for behavioral aspects. Animal models show that treatment during early development can rescue behavioral phenotypes. Taken together, we suggest investigating the differential roles of mTOR and RAS signaling in both human and rodent models, and to test drug treatment both during and after neuronal development in the available model systems.
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Affiliation(s)
- Verica Vasic
- Institute for Microscopic Anatomy and Neurobiology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany; (V.V.); (M.J.S.)
| | - Mattson S. O. Jones
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
| | - Denise Haslinger
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Lisa S. Knaus
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Michael J. Schmeisser
- Institute for Microscopic Anatomy and Neurobiology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany; (V.V.); (M.J.S.)
- Focus Program Translational Neurosciences (FTN), University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany
| | - Gaia Novarino
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Andreas G. Chiocchetti
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
- Correspondence: ; Tel.: +49-69-6301-80658
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High glucose-stimulated enhancer of zeste homolog-2 (EZH2) forces suppression of deptor to cause glomerular mesangial cell pathology. Cell Signal 2021; 86:110072. [PMID: 34224844 DOI: 10.1016/j.cellsig.2021.110072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/23/2021] [Accepted: 06/29/2021] [Indexed: 11/24/2022]
Abstract
Function of mTORC1 and mTORC2 has emerged as a driver of mesangial cell pathologies in diabetic nephropathy. The mechanism of mTOR activation is poorly understood in this disease. Deptor is a constitutive subunit and a negative regulator of both mTOR complexes. Mechanistic investigation in mesangial cells revealed that high glucose decreased the expression of deptor concomitant with increased mTORC1 and mTORC2 activities, induction of hypertrophy and, expression of fibronectin and PAI-1. shRNAs against deptor mimicked these pathologic outcomes of high glucose. Conversely, overexpression of deptor significantly inhibited all effects of high glucose. To determine the mechanism of deptor suppression, we found that high glucose significantly increased the expression of EZH2, resulting in lysine-27 tri-methylation of histone H3 (H3K27Me3). Employing approaches including pharmacological inhibition, shRNA-mediated downregulation and overexpression of EZH2, we found that EZH2 regulates high glucose-induced deptor suppression along with activation of mTOR, mesangial cell hypertrophy and fibronectin/PAI-1 expression. Moreover, expression of hyperactive mTORC1 reversed shEZH2-mediated inhibition of hypertrophy and expression of fibronectin and PAI-1 by high glucose. Finally, in renal cortex of diabetic mice, we found that enhanced expression of EZH2 is associated with decreased deptor levels and increased mTOR activity and, expression of fibronectin and PAI-1. Together, our findings provide a novel mechanism for mTOR activation via EZH2 to induce mesangial cell hypertrophy and matrix expansion during early progression of diabetic nephropathy. These results suggest a strategy for leveraging the intrinsic effect of deptor to suppress mTOR activity via reducing EZH2 as a novel therapy for diabetic nephropathy.
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Amemiya Y, Nakamura N, Ikeda N, Sugiyama R, Ishii C, Maki M, Shibata H, Takahara T. Amino Acid-Mediated Intracellular Ca 2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca 2+/Calmodulin. Int J Mol Sci 2021; 22:ijms22136897. [PMID: 34198993 PMCID: PMC8269083 DOI: 10.3390/ijms22136897] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 12/13/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a master growth regulator by controlling protein synthesis and autophagy in response to environmental cues. Amino acids, especially leucine and arginine, are known to be important activators of mTORC1 and to promote lysosomal translocation of mTORC1, where mTORC1 is thought to make contact with its activator Rheb GTPase. Although amino acids are believed to exclusively regulate lysosomal translocation of mTORC1 by Rag GTPases, how amino acids increase mTORC1 activity besides regulation of mTORC1 subcellular localization remains largely unclear. Here we report that amino acids also converge on regulation of the TSC2-Rheb GTPase axis via Ca2+/calmodulin (CaM). We showed that the amino acid-mediated increase of intracellular Ca2+ is important for mTORC1 activation and thereby contributes to the promotion of nascent protein synthesis. We found that Ca2+/CaM interacted with TSC2 at its GTPase activating protein (GAP) domain and that a CaM inhibitor reduced binding of CaM with TSC2. The inhibitory effect of a CaM inhibitor on mTORC1 activity was prevented by loss of TSC2 or by an active mutant of Rheb GTPase, suggesting that a CaM inhibitor acts through the TSC2-Rheb axis to inhibit mTORC1 activity. Taken together, in response to amino acids, Ca2+/CaM-mediated regulation of the TSC2-Rheb axis contributes to proper mTORC1 activation, in addition to the well-known lysosomal translocation of mTORC1 by Rag GTPases.
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7
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Saito M, Mitani A, Ishimori T, Miyashita N, Isago H, Mikami Y, Noguchi S, Tarui M, Nagase T. Active mTOR in Lung Epithelium Promotes Epithelial-Mesenchymal Transition and Enhances Lung Fibrosis. Am J Respir Cell Mol Biol 2020; 62:699-708. [PMID: 32208980 DOI: 10.1165/rcmb.2019-0255oc] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The mTOR pathway is one of the key signal cascades in the pathogenesis of idiopathic pulmonary fibrosis. Previous studies have mainly focused on this pathway in the fibroblasts and/or myofibroblasts, but not in the epithelial cells. In this study, we sought to investigate the role of the mTOR pathway in lung epithelial cells in lung fibrosis. Using Sftpc-mTORSL1+IT transgenic mice, in which active mTOR is conditionally expressed in lung epithelial cells, we assessed the effects of chronically activated mTOR in lung epithelial cells on lung phenotypes as well as bleomycin-induced lung fibrosis. Furthermore, we isolated alveolar epithelial cell type 2 from mice and performed RNA sequencing. Sftpc-mTORSL1+IT transgenic mice had no obvious abnormal findings, but, after bleomycin administration, showed more severe fibrotic changes and lower lung compliance than control mice. RNA sequencing revealed Angptl4 (angiopoietin-like protein 4) as a candidate downstream gene of the mTOR pathway. In vitro studies revealed that ANGPTL4, as well as mTOR, promoted tight junction vulnerability and epithelial-mesenchymal transition. mTOR activation in lung epithelial cells promoted lung fibrosis and the expression of ANGPTL4, a novel downstream target of the mTOR pathway, which could be related to the etiology of fibrosis.
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Affiliation(s)
- Minako Saito
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Akihisa Mitani
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Taro Ishimori
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Naoya Miyashita
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Hideaki Isago
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Yu Mikami
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Satoshi Noguchi
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Megumi Tarui
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
| | - Takahide Nagase
- Department of Respiratory Medicine, the University of Tokyo, Tokyo, Japan
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Tong K, Hu Z. FOXI1 expression in chromophobe renal cell carcinoma and renal oncocytoma: a study of The Cancer Genome Atlas transcriptome-based outlier mining and immunohistochemistry. Virchows Arch 2020; 478:647-658. [PMID: 32812119 DOI: 10.1007/s00428-020-02900-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/19/2020] [Accepted: 08/06/2020] [Indexed: 01/09/2023]
Abstract
FOXI1 is a forkhead family transcription factor that plays a key role in differentiation and functional maintenance for the renal intercalated cell (IC). The diagnostic utility of FOXI1 is rarely studied thus far. Comparative analyses of FOXI1 mRNA expression in normal kidney tissue and different renal neoplasms including chromophobe renal cell carcinoma (chRCC), renal oncocytoma (RO), and other renal cell carcinomas were conducted using transcriptomic data from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus, and single-cell RNA-seq datasets, in combination with integrative analyses using mutant data, karyotype data, and digital slides for cases with anomalous FOXI1 expression in TCGA. Formalin-fixed, paraffin-embedded whole-tissue slides of varied primary renal neoplasms (n = 367) were subjected to FOXI1 staining for validating FOXI1 transcription levels. We confirmed that FOXI1 was significantly upregulated at mRNA levels in ICs, chRCCs, and ROs compared with other renal tubule cell and renal cell carcinoma subtypes. Furthermore, most of the cases with FOXI1 expression outliers were misclassified in the TCGA kidney cancer project. An underlying novel entity with frequent mutations involved in the mTOR pathway was also found. FOXI1 immunoreactivity was consistently noted in ICs of the distal nephron. FOXI1 staining was positive in 85 of 93 chRCCs and 13 of 18 ROs, respectively. FOXI1 staining was not seen in renal neoplasms (n = 254) derived from non-ICs. In conclusion, FOXI1 expression in normal kidney tissue is restricted to ICs. This cell type-specific expression is retained during neoplastic transformation from ICs to chRCCs or ROs. FOXI1 is thereby a potential biomarker of IC-related tumors.
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Affiliation(s)
- Kuo Tong
- Department of Pathology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410078, Hunan, China.,Department of Pathology, The Bishan Hospital of Chongqing, Bishan District, Chongqing, 402760, China.,Department of Pathology, School of Basic Medical Science, Central South University, 172 Tongzi Road, Changsha, 410013, Hunan, China
| | - Zhongliang Hu
- Department of Pathology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410078, Hunan, China. .,Department of Pathology, School of Basic Medical Science, Central South University, 172 Tongzi Road, Changsha, 410013, Hunan, China.
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9
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Maity S, Das F, Kasinath BS, Ghosh-Choudhury N, Ghosh Choudhury G. TGFβ acts through PDGFRβ to activate mTORC1 via the Akt/PRAS40 axis and causes glomerular mesangial cell hypertrophy and matrix protein expression. J Biol Chem 2020; 295:14262-14278. [PMID: 32732288 DOI: 10.1074/jbc.ra120.014994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/27/2020] [Indexed: 12/21/2022] Open
Abstract
Interaction of transforming growth factor-β (TGFβ)-induced canonical signaling with the noncanonical kinase cascades regulates glomerular hypertrophy and matrix protein deposition, which are early features of glomerulosclerosis. However, the specific target downstream of the TGFβ receptor involved in the noncanonical signaling is unknown. Here, we show that TGFβ increased the catalytic loop phosphorylation of platelet-derived growth factor receptor β (PDGFRβ), a receptor tyrosine kinase expressed abundantly in glomerular mesangial cells. TGFβ increased phosphorylation of the PI 3-kinase-interacting Tyr-751 residue of PDGFRβ, thus activating Akt. Inhibition of PDGFRβ using a pharmacological inhibitor and siRNAs blocked TGFβ-stimulated phosphorylation of proline-rich Akt substrate of 40 kDa (PRAS40), an intrinsic inhibitory component of mTORC1, and prevented activation of mTORC1 in the absence of any effect on Smad 2/3 phosphorylation. Expression of constitutively active myristoylated Akt reversed the siPDGFRβ-mediated inhibition of mTORC1 activity; however, co-expression of the phospho-deficient mutant of PRAS40 inhibited the effect of myristoylated Akt, suggesting a definitive role of PRAS40 phosphorylation in mTORC1 activation downstream of PDGFRβ in mesangial cells. Additionally, we demonstrate that PDGFRβ-initiated phosphorylation of PRAS40 is required for TGFβ-induced mesangial cell hypertrophy and fibronectin and collagen I (α2) production. Increased activating phosphorylation of PDGFRβ is also associated with enhanced TGFβ expression and mTORC1 activation in the kidney cortex and glomeruli of diabetic mice and rats, respectively. Thus, pursuing TGFβ noncanonical signaling, we identified how TGFβ receptor I achieves mTORC1 activation through PDGFRβ-mediated Akt/PRAS40 phosphorylation to spur mesangial cell hypertrophy and matrix protein accumulation. These findings provide support for targeting PDGFRβ in TGFβ-driven renal fibrosis.
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Affiliation(s)
- Soumya Maity
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Falguni Das
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Balakuntalam S Kasinath
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA.,Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
| | | | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA .,Department of Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas, USA.,Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
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10
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Tarkowski B, Kuchcinska K, Blazejczyk M, Jaworski J. Pathological mTOR mutations impact cortical development. Hum Mol Genet 2020; 28:2107-2119. [PMID: 30789219 DOI: 10.1093/hmg/ddz042] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/08/2019] [Accepted: 02/11/2019] [Indexed: 02/03/2023] Open
Abstract
Several mosaic mutations of the mammalian/mechanistic target of rapamycin (mTOR) have recently been found in patients with cortical malformations, such as hemimegalencephaly (HME) and focal cortical dysplasia (FCD). Although all of them should activate mTOR signaling, comparisons of the impact of different mTOR mutations on brain development have been lacking. Also it remains unknown if any potential differences these mutations may have on cortical development are directly related to a degree of mTOR signaling increase. The present study assessed levels of mTORC1 pathway activity in cell lines and rat primary neurons overexpressing several mTOR mutants that were previously found in HME, FCD, cancer patients and in vitro mutagenesis screens. Next we introduced the mutants, enhancing mTORC1 signaling most potently, into developing mouse brains and assessed electroporated cell morphology and migratory phenotype using immunofluorescent staining. We observed the differential inhibition of neuronal progenitor cortical migration, which partly corresponded with a degree of mTORC1 signaling enhancement these mutants induced in cultured cells. The most potent quadruple mutant prevented most of the progenitors from entering the cortical plate. Cells that expressed less potent, single-point, mTOR mutants entered the cortical plate but failed to reach its upper layers and had enlarged soma. Our findings suggest a correlation between the potency of mTOR mutation to activate mTORC1 pathway and disruption of cortical migration.
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Affiliation(s)
- Bartosz Tarkowski
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Kinga Kuchcinska
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | | | - Jacek Jaworski
- International Institute of Molecular and Cell Biology, Warsaw, Poland
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11
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Nussinov R, Tsai C, Jang H. Autoinhibition can identify rare driver mutations and advise pharmacology. FASEB J 2019; 34:16-29. [DOI: 10.1096/fj.201901341r] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/18/2019] [Accepted: 10/09/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Ruth Nussinov
- Computational Structural Biology Section Basic Science Program Frederick National Laboratory for Cancer Research Frederick MD USA
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine Tel Aviv University Tel Aviv Israel
| | - Chung‐Jung Tsai
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine Tel Aviv University Tel Aviv Israel
| | - Hyunbum Jang
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine Tel Aviv University Tel Aviv Israel
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12
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Yamada S, Kamata T, Nawa H, Sekijima T, Takei N. AMPK activation, eEF2 inactivation, and reduced protein synthesis in the cerebral cortex of hibernating chipmunks. Sci Rep 2019; 9:11904. [PMID: 31417118 PMCID: PMC6695389 DOI: 10.1038/s41598-019-48172-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 07/26/2019] [Indexed: 01/10/2023] Open
Abstract
During hibernation, mammalian cells are exposed to severe environmental stressors such as low temperature, lowered O2 supply, and glucose deficiency. The cellular metabolic rate is markedly reduced for adapting to these conditions. AMP-activated protein kinase (AMPK) senses the cellular energy status and regulates metabolism. Therefore, we examined AMPK signaling in several brain regions and peripheral tissues in hibernating chipmunk. Eukaryotic elongation factor 2 (eEF2) is a downstream target of AMPK. Phosphorylation of eEF2, indicating its inactivation, is enhanced in the cerebral cortex of hibernating chipmunks. The study indicated that the sequential regulation of AMPK-mammalian target of rapamycin complex 1-eEF2 signaling was altered and protein synthesis ability was reduced in the cerebral cortex of hibernating chipmunks.
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Affiliation(s)
- Shintaro Yamada
- Department of Environmental Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata, 951-8585, Japan
| | - Taito Kamata
- Department of Environmental Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata, 951-8585, Japan
| | - Hiroyuki Nawa
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Tsuneo Sekijima
- Department of Environmental Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata, 951-8585, Japan
| | - Nobuyuki Takei
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan.
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13
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Murugan AK. mTOR: Role in cancer, metastasis and drug resistance. Semin Cancer Biol 2019; 59:92-111. [PMID: 31408724 DOI: 10.1016/j.semcancer.2019.07.003] [Citation(s) in RCA: 270] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 06/14/2019] [Accepted: 07/03/2019] [Indexed: 02/09/2023]
Abstract
Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that gets inputs from the amino acids, nutrients, growth factor, and environmental cues to regulate varieties of fundamental cellular processes which include protein synthesis, growth, metabolism, aging, regeneration, autophagy, etc. The mTOR is frequently deregulated in human cancer and activating somatic mutations of mTOR were recently identified in several types of human cancer and hence mTOR is therapeutically targeted. mTOR inhibitors were commonly used as immunosuppressors and currently, it is approved for the treatment of human malignancies. This review briefly focuses on the structure and biological functions of mTOR. It extensively discusses the genetic deregulation of mTOR including amplifications and somatic mutations, mTOR-mediated cell growth promoting signaling, therapeutic targeting of mTOR and the mechanisms of resistance, the role of mTOR in precision medicine and other recent advances in further understanding the role of mTOR in cancer.
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Affiliation(s)
- Avaniyapuram Kannan Murugan
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, PO Box 3354, Research Center (MBC 03), Riyadh, 11211, Saudi Arabia.
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14
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Murugan AK, Liu R, Xing M. Identification and characterization of two novel oncogenic mTOR mutations. Oncogene 2019; 38:5211-5226. [PMID: 30918329 PMCID: PMC6597304 DOI: 10.1038/s41388-019-0787-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 02/12/2019] [Accepted: 03/07/2019] [Indexed: 12/29/2022]
Abstract
Mammalian target of rapamycin (mTOR) signaling is often aberrantly activated, particularly when genetically altered, in human cancers. mTOR inhibitors targeting the activated mTOR signaling are highly promising anti-cancer drugs. Knowing the activating genetic change in mTOR can help guide the use of mTOR inhibitors for cancer treatment. This study was conducted to identify and characterize novel oncogenic mTOR mutations that can potentially be therapeutic targets in human cancer. We sequenced 30 exons of the mTOR gene in 12 thyroid cancer cell lines, 3 melanoma cell lines, 20 anaplastic thyroid cancer (ATC) tumors, and 23 melanoma tumors and functionally characterized the identified novel mTOR mutations in vitro and in vivo. We identified a novel point mutation A1256G in ATC cell line and G7076A in melanoma tumor in exon 9 and exon 51 of the mTOR gene, respectively. Over-expression of the corresponding mTOR mutants H419R and G2359E created through induced mutagenesis showed markedly elevated protein kinase activities associated with the activation of mTOR/p70S6K signaling in HEK293T cells. Stable expression of the two mTOR mutants in NIH3T3 cells strongly activated the mTOR/p70S6K signaling pathway and induced morphologic transformation, cell focus formation, anchorage-independent cell growth, and invasion. Inoculation of these mutant-expressing cells in athymic nude mice induced rapid tumor development, showing their driving oncogenicity. We also demonstrated that transfection with the novel mutants conferred cells high sensitivities to the mTOR inhibitor temsirolimus. We speculate that human cancers harboring these mTOR mutations, such as ATC and melanoma, may be effectively treated with inhibitors targeting mTOR.
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Affiliation(s)
- Avaniyapuram Kannan Murugan
- Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Rengyun Liu
- Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Mingzhao Xing
- Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
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15
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Hyperactivation of mTORC1 disrupts cellular homeostasis in cerebellar Purkinje cells. Sci Rep 2019; 9:2799. [PMID: 30808980 PMCID: PMC6391425 DOI: 10.1038/s41598-019-38730-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/19/2018] [Indexed: 11/08/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) is a central regulator of cellular metabolism. The importance of mTORC1 signaling in neuronal development and functions has been highlighted by its strong relationship with many neurological and neuropsychiatric diseases. Previous studies demonstrated that hyperactivation of mTORC1 in forebrain recapitulates tuberous sclerosis and neurodegeneration. In the mouse cerebellum, Purkinje cell-specific knockout of Tsc1/2 has been implicated in autistic-like behaviors. However, since TSC1/2 activity does not always correlate with clinical manifestations as evident in some cases of tuberous sclerosis, the intriguing possibility is raised that phenotypes observed in Tsc1/2 knockout mice cannot be attributable solely to mTORC1 hyperactivation. Here we generated transgenic mice in which mTORC1 signaling is directly hyperactivated in Purkinje cells. The transgenic mice exhibited impaired synapse elimination of climbing fibers and motor discoordination without affecting social behaviors. Furthermore, mTORC1 hyperactivation induced prominent apoptosis of Purkinje cells, accompanied with dysregulated cellular homeostasis including cell enlargement, increased mitochondrial respiratory activity, and activation of pseudohypoxic response. These findings suggest the different contributions between hyperactivated mTORC1 and Tsc1/2 knockout in social behaviors, and reveal the perturbations of cellular homeostasis by hyperactivated mTORC1 as possible underlying mechanisms of neuronal dysfunctions and death in tuberous sclerosis and neurodegenerative diseases.
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16
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Kim IJ, Lee J, Oh SJ, Yoon MS, Jang SS, Holland RL, Reno ML, Hamad MN, Maeda T, Chung HJ, Chen J, Blanke SR. Helicobacter pylori Infection Modulates Host Cell Metabolism through VacA-Dependent Inhibition of mTORC1. Cell Host Microbe 2018; 23:583-593.e8. [PMID: 29746831 DOI: 10.1016/j.chom.2018.04.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/15/2018] [Accepted: 04/17/2018] [Indexed: 12/15/2022]
Abstract
Helicobacter pylori (Hp) vacuolating cytotoxin (VacA) is a bacterial exotoxin that enters host cells and induces mitochondrial dysfunction. However, the extent to which VacA-dependent mitochondrial perturbations affect overall cellular metabolism is poorly understood. We report that VacA perturbations in mitochondria are linked to alterations in cellular amino acid homeostasis, which results in the inhibition of mammalian target of rapamycin complex 1 (mTORC1) and subsequent autophagy. mTORC1, which regulates cellular metabolism during nutrient stress, is inhibited during Hp infection by a VacA-dependent mechanism. This VacA-dependent inhibition of mTORC1 signaling is linked to the dissociation of mTORC1 from the lysosomal surface and results in activation of cellular autophagy through the Unc 51-like kinase 1 (Ulk1) complex. VacA intoxication results in reduced cellular amino acids, and bolstering amino acid pools prevents VacA-mediated mTORC1 inhibition. Overall, these studies support a model that Hp modulate host cell metabolism through the action of VacA at mitochondria.
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Affiliation(s)
- Ik-Jung Kim
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
| | - Jeongmin Lee
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | - Seung J Oh
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | - Mee-Sup Yoon
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801, USA; Department of Molecular Medicine, School of Medicine, Gachon University, Incheon 406-840, Republic of Korea
| | - Sung-Soo Jang
- Department of Molecular and Integrative Physiology, University of Illinois, Urbana, IL 61801, USA
| | - Robin L Holland
- Department of Pathobiology, University of Illinois, Urbana, IL 61801, USA
| | - Michael L Reno
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
| | - Mohammed N Hamad
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
| | - Tatsuya Maeda
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois, Urbana, IL 61801, USA
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801, USA
| | - Steven R Blanke
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA; Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA; Lead Contact.
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17
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Yoneyama Y, Inamitsu T, Chida K, Iemura SI, Natsume T, Maeda T, Hakuno F, Takahashi SI. Serine Phosphorylation by mTORC1 Promotes IRS-1 Degradation through SCFβ-TRCP E3 Ubiquitin Ligase. iScience 2018; 5:1-18. [PMID: 30240640 PMCID: PMC6123863 DOI: 10.1016/j.isci.2018.06.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/03/2018] [Accepted: 06/13/2018] [Indexed: 12/21/2022] Open
Abstract
The insulin receptor substrate IRS-1 is a key substrate of insulin and insulin-like growth factor (IGF) receptor tyrosine kinases that mediates their metabolic and growth-promoting actions. Proteasomal degradation of IRS-1 is induced following activation of the downstream kinase mTOR complex 1 (mTORC1) to constitute a negative feedback loop. However, the underlying mechanism remains poorly understood. Here we report that Ser 422 of IRS-1 is phosphorylated by mTORC1 and required for IRS-1 degradation induced by prolonged IGF stimulation. Phosphorylation of Ser 422 then recruits the SCFβ-TRCP E3 ligase complex, which catalyzes IRS-1 ubiquitination. Phosphorylation-dependent IRS-1 degradation contributes to impaired growth and survival responses to IGF in cells lacking TSC2, a negative regulator of mTORC1. Inhibition of IRS-1 degradation promotes sustained Akt activation in IGF-stimulated cells. Our work clarifies the nature of the IRS-1-mTORC1 feedback loop and elucidates its role in temporal regulation of IGF signaling. Ser 422 of IRS-1 is identified as a phosphorylation site by mTORC1 Phosphorylation of Ser 422 induces the binding of SCF β-TRCP E3 ligase to IRS-1 Ser 422 phosphorylation triggers the SCF β-TRCP-mediated degradation of IRS-1 The IRS-1-mTORC1 negative feedback loop determines the duration of IGF signaling
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Affiliation(s)
- Yosuke Yoneyama
- Department of Animal Resource Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tomomi Inamitsu
- Department of Animal Resource Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kazuhiro Chida
- Department of Animal Resource Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shun-Ichiro Iemura
- Translational Research Center, Fukushima Medical University, Fukushima-city, Fukushima 960-8031, Japan
| | - Tohru Natsume
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Koto-ku, Tokyo 135-0064, Japan
| | - Tatsuya Maeda
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Integrated Human Sciences, Faculty of Medicine, Hamamatsu University School of Medicine, Hamamatsu-city, Shizuoka 431-3192, Japan
| | - Fumihiko Hakuno
- Department of Animal Resource Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shin-Ichiro Takahashi
- Department of Animal Resource Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
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18
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Yang H, Jiang X, Li B, Yang HJ, Miller M, Yang A, Dhar A, Pavletich NP. Mechanisms of mTORC1 activation by RHEB and inhibition by PRAS40. Nature 2017; 552:368-373. [PMID: 29236692 PMCID: PMC5750076 DOI: 10.1038/nature25023] [Citation(s) in RCA: 330] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 11/08/2017] [Indexed: 12/13/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to nutrients, energy levels, and growth factors. It contains the atypical kinase mTOR and the RAPTOR subunit that binds to the Tor signalling sequence (TOS) motif of substrates and regulators. mTORC1 is activated by the small GTPase RHEB (Ras homologue enriched in brain) and inhibited by PRAS40. Here we present the 3.0 ångström cryo-electron microscopy structure of mTORC1 and the 3.4 ångström structure of activated RHEB-mTORC1. RHEB binds to mTOR distally from the kinase active site, yet causes a global conformational change that allosterically realigns active-site residues, accelerating catalysis. Cancer-associated hyperactivating mutations map to structural elements that maintain the inactive state, and we provide biochemical evidence that they mimic RHEB relieving auto-inhibition. We also present crystal structures of RAPTOR-TOS motif complexes that define the determinants of TOS recognition, of an mTOR FKBP12-rapamycin-binding (FRB) domain-substrate complex that establishes a second substrate-recruitment mechanism, and of a truncated mTOR-PRAS40 complex that reveals PRAS40 inhibits both substrate-recruitment sites. These findings help explain how mTORC1 selects its substrates, how its kinase activity is controlled, and how it is activated by cancer-associated mutations.
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Affiliation(s)
- Haijuan Yang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Xiaolu Jiang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Buren Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Hyo J Yang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Meredith Miller
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Angela Yang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Ankita Dhar
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Nikola P Pavletich
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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19
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Kanayama M, Hayano T, Koebis M, Maeda T, Tabe Y, Horie S, Aiba A. Hyperactive mTOR induces neuroendocrine differentiation in prostate cancer cell with concurrent up-regulation of IRF1. Prostate 2017; 77:1489-1498. [PMID: 28905415 DOI: 10.1002/pros.23425] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 08/23/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND Neuroendocrine-differentiated prostate cancer (NEPCa) is refractory to androgen deprivation therapy and shows a poor prognosis. The underlying mechanisms responsible for neuroendocrine differentiation (NED) are yet to be clarified. In this study, we investigated the role of mammalian target of rapamycin (mTOR) in NEPCa. METHODS We utilized a gain-of-function analysis by establishing a human PCa LNCaP stable line that expresses hyperactive mTOR (LNCaP-mTOR). Then, we employed a comprehensive mass spectrometric analysis to identify a key transcription factor in LNCaP-mTOR, followed by a loss-of-function analysis using CRISPR/Cas system. RESULTS The activation of mTOR induced NED. We observed significant cell growth arrest in NED of LNCaP-mTOR, which accompanied increased expression of p21WAF1/CIP1 . A comprehensive mass spectrometric analysis identified interferon regulatory factor 1 (IRF1) as a key transcription factor in growth arrest of LNCaP-mTOR. The disruption of IRF1 gene in LNCaP-mTOR reversed cell growth arrest along with the suppression of its target p21WAF1/CIP1 . These results indicate that the growth arrest in NED is at least in part dependent on IRF1 through the induction of p21WAF1/CIP1 . CONCLUSIONS We identified active mTOR as a novel inducer of NED, and elucidated a mechanism underlying the malignant transformation of NEPCa by recapitulating NED in vitro.
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Affiliation(s)
- Mayuko Kanayama
- Department of Urology, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Laboratory of Animal Resources, Center for Disease Biology and Integrated Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshiya Hayano
- Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Michinori Koebis
- Laboratory of Animal Resources, Center for Disease Biology and Integrated Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tatsuya Maeda
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Yoko Tabe
- Department of Clinical Laboratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shigeo Horie
- Department of Urology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Atsu Aiba
- Laboratory of Animal Resources, Center for Disease Biology and Integrated Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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20
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Bera A, Das F, Ghosh-Choudhury N, Mariappan MM, Kasinath BS, Ghosh Choudhury G. Reciprocal regulation of miR-214 and PTEN by high glucose regulates renal glomerular mesangial and proximal tubular epithelial cell hypertrophy and matrix expansion. Am J Physiol Cell Physiol 2017; 313:C430-C447. [PMID: 28701356 PMCID: PMC5668576 DOI: 10.1152/ajpcell.00081.2017] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 07/06/2017] [Accepted: 07/09/2017] [Indexed: 02/06/2023]
Abstract
Aberrant expression of microRNAs (miRs) contributes to diabetic renal complications, including renal hypertrophy and matrix protein accumulation. Reduced expression of phosphatase and tensin homolog (PTEN) by hyperglycemia contributes to these processes. We considered involvement of miR in the downregulation of PTEN. In the renal cortex of type 1 diabetic mice, we detected increased expression of miR-214 in association with decreased levels of PTEN and enhanced Akt phosphorylation and fibronectin expression. Mesangial and proximal tubular epithelial cells exposed to high glucose showed augmented expression of miR-214. Mutagenesis studies using 3'-UTR of PTEN in a reporter construct revealed PTEN as a direct target of miR-214, which controls its expression in both of these cells. Overexpression of miR-214 decreased the levels of PTEN and increased Akt activity similar to high glucose and lead to phosphorylation of its substrates glycogen synthase kinase-3β, PRAS40, and tuberin. In contrast, quenching of miR-214 inhibited high-glucose-induced Akt activation and its substrate phosphorylation; these changes were reversed by small interfering RNAs against PTEN. Importantly, respective expression of miR-214 or anti-miR-214 increased or decreased the mammalian target of rapamycin complex 1 (mTORC1) activity induced by high glucose. Furthermore, mTORC1 activity was controlled by miR-214-targeted PTEN via Akt activation. In addition, neutralization of high-glucose-stimulated miR-214 expression significantly inhibited cell hypertrophy and expression of the matrix protein fibronectin. Finally, the anti-miR-214-induced inhibition of these processes was reversed by the expression of constitutively active Akt kinase and hyperactive mTORC1. These results uncover a significant role of miR-214 in the activation of mTORC1 that contributes to high-glucose-induced mesangial and proximal tubular cell hypertrophy and fibronectin expression.
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Affiliation(s)
- Amit Bera
- Department of Medicine, UT Health San Antonio, San Antonio, Texas
| | - Falguni Das
- Department of Medicine, UT Health San Antonio, San Antonio, Texas
| | - Nandini Ghosh-Choudhury
- Veterans Affairs Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, Texas
- Department of Pathology, UT Health San Antonio, San Antonio, Texas; and
| | | | - Balakuntalam S Kasinath
- Department of Medicine, UT Health San Antonio, San Antonio, Texas
- Veterans Affairs Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, Texas
| | - Goutam Ghosh Choudhury
- Department of Medicine, UT Health San Antonio, San Antonio, Texas;
- Veterans Affairs Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, Texas
- Geriatric Research, Education and Clinical Research, South Texas Veterans Health Care System, San Antonio, Texas
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21
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An In Vitro TORC1 Kinase Assay That Recapitulates the Gtr-Independent Glutamine-Responsive TORC1 Activation Mechanism on Yeast Vacuoles. Mol Cell Biol 2017; 37:MCB.00075-17. [PMID: 28483912 DOI: 10.1128/mcb.00075-17] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 05/01/2017] [Indexed: 01/03/2023] Open
Abstract
Evolutionarily conserved target of rapamycin (TOR) complex 1 (TORC1) responds to nutrients, especially amino acids, to promote cell growth. In the yeast Saccharomyces cerevisiae, various nitrogen sources activate TORC1 with different efficiencies, although the mechanism remains elusive. Leucine, and perhaps other amino acids, was reported to activate TORC1 via the heterodimeric small GTPases Gtr1-Gtr2, the orthologues of the mammalian Rag GTPases. More recently, an alternative Gtr-independent TORC1 activation mechanism that may respond to glutamine was reported, although its molecular mechanism is not clear. In studying the nutrient-responsive TORC1 activation mechanism, the lack of an in vitro assay hinders associating particular nutrient compounds with the TORC1 activation status, whereas no in vitro assay that shows nutrient responsiveness has been reported. In this study, we have developed a new in vitro TORC1 kinase assay that reproduces, for the first time, the nutrient-responsive TORC1 activation. This in vitro TORC1 assay recapitulates the previously predicted Gtr-independent glutamine-responsive TORC1 activation mechanism. Using this system, we found that this mechanism specifically responds to l-glutamine, resides on the vacuolar membranes, and involves a previously uncharacterized Vps34-Vps15 phosphatidylinositol (PI) 3-kinase complex and the PI-3-phosphate [PI(3)P]-binding FYVE domain-containing vacuolar protein Pib2. Thus, this system was proved to be useful for dissecting the glutamine-responsive TORC1 activation mechanism.
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22
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Zining J, Lu X, Caiyun H, Yuan Y. Genetic polymorphisms of mTOR and cancer risk: a systematic review and updated meta-analysis. Oncotarget 2016; 7:57464-57480. [PMID: 27462867 PMCID: PMC5302868 DOI: 10.18632/oncotarget.10805] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/29/2016] [Indexed: 12/16/2022] Open
Abstract
mTOR regulates several cellular processes that are critical for tumorigenesis. However, previous studies on the association of mTOR polymorphisms with predisposition to different cancer types are somewhat contradictory. Therefore, we performed a systematic review and updated meta-analysis of the available evidence regarding the relationship between mTOR single nucleotide polymorphisms (SNPs) and cancer risk. Up to November 2015, 23 original publications were identified covering 20 mTOR SNPs, of which seven SNPs (rs2536, rs2295080, rs1883965, rs1034528, rs17036508, rs3806317 and rs1064261) were included in the final meta-analysis. We estimated the summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for mTOR polymorphisms and cancer risk, and used the model-free approach to investigate the biological effect of each polymorphism. Our meta-analysis found that rs1883965, rs1034528, and rs17036508 were correlated with increased cancer risk in the complete over-dominant model (rs1883965 GA versus GG/AA: fixed-effects OR=1.15, 95% CI 1.02-1.29; rs1034528 GC versus GG/CC: fixed-effects OR=1.30, 95% CI 1.13-1.48; rs17036508 TC versus CC/TT: fixed-effects OR=1.23, 95% CI 1.06-1.43). Stratifying analyses by cancer type, we found that the rs2295080 G allele was associated with a significantly higher risk of acute leukemia in the recessive model (GG versus GT/TT: fixed-effects OR=2.08, 95% CI 1.34-3.22) and a lower risk of genitourinary cancers in the dominant model (TG/GG versus TT: fixed-effects OR=0.77, 95% CI 0.68-0.86). Interestingly, further expression analysis showed that homozygous variant genotype carriers of rs1883965, rs1034528 and rs17036508 had lower mTOR transcript levels, based on HapMap data.
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Affiliation(s)
- Jin Zining
- Tumor Etiology and Screening Department of Cancer Institute and General Surgery, Key Laboratory of Cancer Etiology and Prevention of Liaoning Provincial Education Department, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Xu Lu
- Tumor Etiology and Screening Department of Cancer Institute and General Surgery, Key Laboratory of Cancer Etiology and Prevention of Liaoning Provincial Education Department, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - He Caiyun
- Department of Molecular Diagnostics, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Yuan Yuan
- Tumor Etiology and Screening Department of Cancer Institute and General Surgery, Key Laboratory of Cancer Etiology and Prevention of Liaoning Provincial Education Department, The First Affiliated Hospital of China Medical University, Shenyang, China
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23
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Das F, Dey N, Bera A, Kasinath BS, Ghosh-Choudhury N, Choudhury GG. MicroRNA-214 Reduces Insulin-like Growth Factor-1 (IGF-1) Receptor Expression and Downstream mTORC1 Signaling in Renal Carcinoma Cells. J Biol Chem 2016; 291:14662-76. [PMID: 27226530 DOI: 10.1074/jbc.m115.694331] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Indexed: 01/21/2023] Open
Abstract
Elevated IGF-1/insulin-like growth factor-1 receptor (IGF-1R) autocrine/paracrine signaling in patients with renal cell carcinoma is associated with poor prognosis of the disease independent of their von Hippel-Lindau (VHL) status. Increased expression of IGF-1R in renal cancer cells correlates with their potency of tumor development and progression. The mechanism by which expression of IGF-1R is increased in renal carcinoma is not known. We report that VHL-deficient and VHL-positive renal cancer cells possess significantly decreased levels of mature, pre-, and pri-miR-214 than normal proximal tubular epithelial cells. We identified an miR-214 recognition element in the 3'UTR of IGF-1R mRNA and confirmed its responsiveness to miR-214. Overexpression of miR-214 decreased the IGF-1R protein levels, resulting in the inhibition of Akt kinase activity in both types of renal cancer cells. IGF-1 provoked phosphorylation and inactivation of PRAS40 in an Akt-dependent manner, leading to the activation of mTORC1 signal transduction to increase phosphorylation of S6 kinase and 4EBP-1. Phosphorylation-deficient mutants of PRAS40 and 4EBP-1 significantly inhibited IGF-1R-driven proliferation of renal cancer cells. Expression of miR-214 suppressed IGF-1R-induced phosphorylation of PRAS40, S6 kinase, and 4EBP-1, indicating inhibition of mTORC1 activity. Finally, miR-214 significantly blocked IGF-1R-forced renal cancer cell proliferation, which was reversed by expression of 3'UTR-less IGF-1R and constitutively active mTORC1. Together, our results identify a reciprocal regulation of IGF-1R levels and miR-214 expression in renal cancer cells independent of VHL status. Our data provide evidence for a novel mechanism for IGF-1R-driven renal cancer cell proliferation involving miR-214 and mTORC1.
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Affiliation(s)
| | | | | | | | - Nandini Ghosh-Choudhury
- From Veterans Affairs Research and Geriatric Research, Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Goutam Ghosh Choudhury
- the Departments of Medicine and From Veterans Affairs Research and Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas 78229-3900 and
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24
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Ando R, Shima H, Tamahara T, Sato Y, Watanabe-Matsui M, Kato H, Sax N, Motohashi H, Taguchi K, Yamamoto M, Nio M, Maeda T, Ochiai K, Muto A, Igarashi K. The Transcription Factor Bach2 Is Phosphorylated at Multiple Sites in Murine B Cells but a Single Site Prevents Its Nuclear Localization. J Biol Chem 2015; 291:1826-1840. [PMID: 26620562 DOI: 10.1074/jbc.m115.661702] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Indexed: 12/22/2022] Open
Abstract
The transcription factor Bach2 regulates the immune system at multiple points, including class switch recombination (CSR) in activated B cells and the function of T cells in part by restricting their terminal differentiation. However, the regulation of Bach2 expression and its activity in the immune cells are still unclear. Here, we demonstrated that Bach2 mRNA expression decreased in Pten-deficient primary B cells. Bach2 was phosphorylated in primary B cells, which was increased upon the activation of the B cell receptor by an anti-immunoglobulin M (IgM) antibody or CD40 ligand. Using specific inhibitors of kinases, the phosphorylation of Bach2 in activated B cells was shown to depend on the phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) pathway. The complex of mTOR and Raptor phosphorylated Bach2 in vitro. We identified multiple new phosphorylation sites of Bach2 by mass spectrometry analysis of epitope-tagged Bach2 expressed in the mature B cell line BAL17. Among the sites identified, serine 535 (Ser-535) was critical for the regulation of Bach2 because a single mutation of Ser-535 abolished cytoplasmic accumulation of Bach2, promoting its nuclear accumulation in pre-B cells, whereas Ser-509 played an auxiliary role. Bach2 repressor activity was enhanced by the Ser-535 mutation in B cells. These results suggest that the PI3K-Akt-mTOR pathway inhibits Bach2 by both repressing its expression and inducing its phosphorylation in B cells.
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Affiliation(s)
- Ryo Ando
- From the Departments of Biochemistry,; Pediatric Surgery, and
| | - Hiroki Shima
- From the Departments of Biochemistry,; CREST, Japan Science and Technology Agency, Seiryo-machi 2-1, Sendai 980-8575, and
| | - Toru Tamahara
- From the Departments of Biochemistry,; CREST, Japan Science and Technology Agency, Seiryo-machi 2-1, Sendai 980-8575, and; the Department of Preventive Dentistry, Tohoku University Graduate School of Dentistry, Seiryo-machi 4-1, Sendai 980-8575
| | | | | | | | - Nicolas Sax
- From the Departments of Biochemistry,; CREST, Japan Science and Technology Agency, Seiryo-machi 2-1, Sendai 980-8575, and
| | - Hozumi Motohashi
- Department of Gene Expression Regulation, Institute of Development, Aging, and Cancer, Tohoku University, Seiryo-machi 4-1, Sendai 980-8575
| | - Keiko Taguchi
- Medical Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Sendai 980-8575
| | - Masayuki Yamamoto
- Medical Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Sendai 980-8575
| | | | - Tatsuya Maeda
- the Laboratory of Membrane Proteins, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Tokyo 113-0032, Japan
| | - Kyoko Ochiai
- From the Departments of Biochemistry,; CREST, Japan Science and Technology Agency, Seiryo-machi 2-1, Sendai 980-8575, and; Center for Regulatory Epigenome and Diseases, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Sendai 980-8575
| | - Akihiko Muto
- From the Departments of Biochemistry,; CREST, Japan Science and Technology Agency, Seiryo-machi 2-1, Sendai 980-8575, and
| | - Kazuhiko Igarashi
- From the Departments of Biochemistry,; CREST, Japan Science and Technology Agency, Seiryo-machi 2-1, Sendai 980-8575, and; Center for Regulatory Epigenome and Diseases, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Sendai 980-8575,.
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25
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Mroske C, Rasmussen K, Shinde DN, Huether R, Powis Z, Lu HM, Baxter RM, McPherson E, Tang S. Germline activating MTOR mutation arising through gonadal mosaicism in two brothers with megalencephaly and neurodevelopmental abnormalities. BMC MEDICAL GENETICS 2015; 16:102. [PMID: 26542245 PMCID: PMC4635597 DOI: 10.1186/s12881-015-0240-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/03/2015] [Indexed: 01/06/2023]
Abstract
Background In humans, Mammalian Target of Rapamycin (MTOR) encodes a 300 kDa serine/ threonine protein kinase that is ubiquitously expressed, particularly at high levels in brain. MTOR functions as an integrator of multiple cellular processes, and in so doing either directly or indirectly regulates the phosphorylation of at least 800 proteins. While somatic MTOR mutations have been recognized in tumors for many years, and more recently in hemimegalencephaly, germline MTOR mutations have rarely been described. Case presentation We report the successful application of family-trio Diagnostic Exome Sequencing (DES) to identify the underlying molecular etiology in two brothers with multiple neurological and developmental lesions, and for whom previous testing was non-diagnostic. The affected brothers, who were 6 and 23 years of age at the time of DES, presented symptoms including but not limited to mild Autism Spectrum Disorder (ASD), megalencephaly, gross motor skill delay, cryptorchidism and bilateral iris coloboma. Importantly, we determined that each affected brother harbored the MTOR missense alteration p.E1799K (c.5395G>A). This exact variant has been previously identified in multiple independent human somatic cancer samples and has been shown to result in increased MTOR activation. Further, recent independent reports describe two unrelated families in whom p.E1799K co-segregated with megalencephaly and intellectual disability (ID); in both cases, p.E1799K was shown to have originated due to germline mosaicism. In the case of the family reported herein, the absence of p.E1799K in genomic DNA extracted from the blood of either parent suggests that this alteration most likely arose due to gonadal mosaicism. Further, the p.E1799K variant exerts its effect by a gain-of-function (GOF), autosomal dominant mechanism. Conclusion Herein, we describe the use of DES to uncover an activating MTOR missense alteration of gonadal mosaic origin that is likely to be the causative mutation in two brothers who present multiple neurological and developmental abnormalities. Our report brings the total number of families who harbor MTOR p.E1799K in association with megalencephaly and ID to three. In each case, evidence suggests that p.E1799K arose in the affected individuals due to gonadal mosaicism. Thus, MTOR p.E1799K can now be classified as a pathogenic GOF mutation that causes megalencephaly and cognitive impairment in humans. Electronic supplementary material The online version of this article (doi:10.1186/s12881-015-0240-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cameron Mroske
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | | | | | - Robert Huether
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | - Zoe Powis
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | - Hsiao-Mei Lu
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | - Ruth M Baxter
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | | | - Sha Tang
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
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26
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Yamaguchi H, Kawazu M, Yasuda T, Soda M, Ueno T, Kojima S, Yashiro M, Yoshino I, Ishikawa Y, Sai E, Mano H. Transforming somatic mutations of mammalian target of rapamycin kinase in human cancer. Cancer Sci 2015; 106:1687-92. [PMID: 26432419 PMCID: PMC4714661 DOI: 10.1111/cas.12828] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 09/24/2015] [Accepted: 09/26/2015] [Indexed: 02/06/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) is a serine–threonine kinase that acts downstream of the phosphatidylinositol 3‐kinase signaling pathway and regulates a wide range of cellular functions including transcription, translation, proliferation, apoptosis, and autophagy. Whereas genetic alterations that result in mTOR activation are frequently present in human cancers, whether the mTOR gene itself becomes an oncogene through somatic mutation has remained unclear. We have now identified a somatic non‐synonymous mutation of mTOR that results in a leucine‐to‐valine substitution at amino acid position 2209 in a specimen of large cell neuroendocrine carcinoma. The mTOR(L2209V) mutant manifested marked transforming potential in a focus formation assay with mouse 3T3 fibroblasts, and it induced the phosphorylation of p70 S6 kinase, S6 ribosomal protein, and eukaryotic translation initiation factor 4E–binding protein 1 in these cells. Examination of additional tumor specimens as well as public and in‐house databases of cancer genome mutations identified another 28 independent non‐synonymous mutations of mTOR in various cancer types, with 12 of these mutations also showing transforming ability. Most of these oncogenic mutations cluster at the interface between the kinase domain and the FAT (FRAP, ATM, TRRAP) domain in the 3‐D structure of mTOR. Transforming mTOR mutants were also found to promote 3T3 cell survival, and their oncogenic activity was sensitive to rapamycin. Our data thus show that mTOR acquires transforming activity through genetic changes in cancer, and they suggest that such tumors may be candidates for molecularly targeted therapy with mTOR inhibitors.
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Affiliation(s)
- Hiroyuki Yamaguchi
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Second Department of Internal Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Masahito Kawazu
- Department of Medical Genomics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takahiko Yasuda
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Manabu Soda
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshihide Ueno
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shinya Kojima
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masakazu Yashiro
- Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Ichiro Yoshino
- Department of General Thoracic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yuichi Ishikawa
- Department of Pathology, The Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Eirin Sai
- Department of Medical Genomics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Mano
- Department of Cellular Signaling, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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27
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Abstract
mTOR (mechanistic target of rapamycin) functions as the central regulator for cell proliferation, growth and survival. Up-regulation of proteins regulating mTOR, as well as its downstream targets, has been reported in various cancers. This has promoted the development of anti-cancer therapies targeting mTOR, namely fungal macrolide rapamycin, a naturally occurring mTOR inhibitor, and its analogues (rapalogues). One such rapalogue, everolimus, has been approved in the clinical treatment of renal and breast cancers. Although results have demonstrated that these mTOR inhibitors are effective in attenuating cell growth of cancer cells under in vitro and in vivo conditions, subsequent sporadic response to rapalogues therapy in clinical trials has promoted researchers to look further into the complex understanding of the dynamics of mTOR regulation in the tumour environment. Limitations of these rapalogues include the sensitivity of tumour subsets to mTOR inhibition. Additionally, it is well known that rapamycin and its rapalogues mediate their effects by inhibiting mTORC (mTOR complex) 1, with limited or no effect on mTORC2 activity. The present review summarizes the pre-clinical, clinical and recent discoveries, with emphasis on the cellular and molecular effects of everolimus in cancer therapy.
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28
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Nakashima M, Saitsu H, Takei N, Tohyama J, Kato M, Kitaura H, Shiina M, Shirozu H, Masuda H, Watanabe K, Ohba C, Tsurusaki Y, Miyake N, Zheng Y, Sato T, Takebayashi H, Ogata K, Kameyama S, Kakita A, Matsumoto N. Somatic Mutations in the MTOR gene cause focal cortical dysplasia type IIb. Ann Neurol 2015; 78:375-86. [PMID: 26018084 DOI: 10.1002/ana.24444] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 05/26/2015] [Accepted: 05/26/2015] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Focal cortical dysplasia (FCD) type IIb is a cortical malformation characterized by cortical architectural abnormalities, dysmorphic neurons, and balloon cells. It has been suggested that FCDs are caused by somatic mutations in cells in the developing brain. Here, we explore the possible involvement of somatic mutations in FCD type IIb. METHODS We collected a total of 24 blood-brain paired samples with FCD, including 13 individuals with FCD type IIb, 5 with type IIa, and 6 with type I. We performed whole-exome sequencing using paired samples from 9 of the FCD type IIb subjects. Somatic MTOR mutations were identified and further investigated using all 24 paired samples by deep sequencing of the entire gene's coding region. Somatic MTOR mutations were confirmed by droplet digital polymerase chain reaction. The effect of MTOR mutations on mammalian target of rapamycin (mTOR) kinase signaling was evaluated by immunohistochemistry and Western blotting analyses of brain samples and by in vitro transfection experiments. RESULTS We identified four lesion-specific somatic MTOR mutations in 6 of 13 (46%) individuals with FCD type IIb showing mutant allele rates of 1.11% to 9.31%. Functional analyses showed that phosphorylation of ribosomal protein S6 in FCD type IIb brain tissues with MTOR mutations was clearly elevated, compared to control samples. Transfection of any of the four MTOR mutants into HEK293T cells led to elevated phosphorylation of 4EBP, the direct target of mTOR kinase. INTERPRETATION We found low-prevalence somatic mutations in MTOR in FCD type IIb, indicating that activating somatic mutations in MTOR cause FCD type IIb.
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Affiliation(s)
- Mitsuko Nakashima
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hirotomo Saitsu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Nobuyuki Takei
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Jun Tohyama
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Hiroki Kitaura
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Masaaki Shiina
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hiroshi Shirozu
- Department of Functional Neurosurgery, Epilepsy Center, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Hiroshi Masuda
- Department of Functional Neurosurgery, Epilepsy Center, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Keisuke Watanabe
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Chihiro Ohba
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yoshinori Tsurusaki
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yingjun Zheng
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Tatsuhiro Sato
- Division of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Kazuhiro Ogata
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Shigeki Kameyama
- Department of Functional Neurosurgery, Epilepsy Center, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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29
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Cho DC. Targeting the PI3K/Akt/mTOR pathway in malignancy: rationale and clinical outlook. BioDrugs 2015; 28:373-81. [PMID: 24567265 DOI: 10.1007/s40259-014-0090-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The phosphatidylinositol 3-kinase (PI3K) pathway, including major downstream effectors Akt and mammalian target of rapamycin (mTOR), plays a critical role in malignant transformation and subsequent processes of growth, proliferation, and metastases. Not surprisingly, the PI3K/Akt/mTOR pathway has emerged as an attractive drug target and numerous agents directed against various elements of the pathway are currently in clinical development. While early clinical trials with the first generations of these agents have shown limited single-agent efficacy, efforts are now focused on the development of more specific inhibitors, patient selection strategies, and combinational approaches. In this review, we discuss the PI3K/Akt/mTOR pathway in cancer, the rationale for its emergence as a therapeutic target, and progress thus far in the clinical development of inhibitors targeting its various elements.
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Affiliation(s)
- Daniel C Cho
- NYU Cancer Institute, NYU Langone Medical Center, 160 East 34th Street, New York, NY, 10016, USA,
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30
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Abstract
The ataxia-telangiectasia mutated (ATM) protein kinase is a master regulator of the DNA damage response, and it coordinates checkpoint activation, DNA repair, and metabolic changes in eukaryotic cells in response to DNA double-strand breaks and oxidative stress. Loss of ATM activity in humans results in the pleiotropic neurodegeneration disorder ataxia-telangiectasia. ATM exists in an inactive state in resting cells but can be activated by the Mre11-Rad50-Nbs1 (MRN) complex and other factors at sites of DNA breaks. In addition, oxidation of ATM activates the kinase independently of the MRN complex. This review discusses these mechanisms of activation, as well as the posttranslational modifications that affect this process and the cellular factors that affect the efficiency and specificity of ATM activation and substrate phosphorylation. I highlight functional similarities between the activation mechanisms of ATM, phosphatidylinositol 3-kinases (PI3Ks), and the other PI3K-like kinases, as well as recent structural insights into their regulation.
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Affiliation(s)
- Tanya T Paull
- Howard Hughes Medical Institute, Department of Molecular Biosciences, and Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712;
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31
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Abstract
The mammalian target of rapamycin (mTOR) has emerged as a potential target for drug development, particularly due to the fact that it plays such a crucial role in cancer biology. In addition, next-generation mTOR inhibitors have become available, marking an exciting new phase in mTOR-based therapy. However, the verdict on their therapeutic efectiveness remains unclear. Here we review phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR signaling as one of the primary mechanisms for sustaining tumor outgrowth and metastasis, recent advances in the development of mTOR inhibitors, and current studies addressing mTOR activation/inhibition in colorectal cancer (CRC). We will also discuss our recent comparative study of diferent mTOR inhibitors in a population of colon cancer stem cells (CSCs), and current major challenges for achieving individualized drug therapy using kinase inhibitors.
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32
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Patursky-Polischuk I, Kasir J, Miloslavski R, Hayouka Z, Hausner-Hanochi M, Stolovich-Rain M, Tsukerman P, Biton M, Mudhasani R, Jones SN, Meyuhas O. Reassessment of the role of TSC, mTORC1 and microRNAs in amino acids-meditated translational control of TOP mRNAs. PLoS One 2014; 9:e109410. [PMID: 25338081 PMCID: PMC4206288 DOI: 10.1371/journal.pone.0109410] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/30/2014] [Indexed: 01/02/2023] Open
Abstract
TOP mRNAs encode components of the translational apparatus, and repression of their translation comprises one mechanism, by which cells encountering amino acid deprivation downregulate the biosynthesis of the protein synthesis machinery. This mode of regulation involves TSC as knockout of TSC1 or TSC2 rescued TOP mRNAs translation in amino acid-starved cells. The involvement of mTOR in translational control of TOP mRNAs is demonstrated by the ability of constitutively active mTOR to relieve the translational repression of TOP mRNA upon amino acid deprivation. Consistently, knockdown of this kinase as well as its inhibition by pharmacological means blocked amino acid-induced translational activation of these mRNAs. The signaling of amino acids to TOP mRNAs involves RagB, as overexpression of active RagB derepressed the translation of these mRNAs in amino acid-starved cells. Nonetheless, knockdown of raptor or rictor failed to suppress translational activation of TOP mRNAs by amino acids, suggesting that mTORC1 or mTORC2 plays a minor, if any, role in this mode of regulation. Finally, miR10a has previously been suggested to positively regulate the translation of TOP mRNAs. However, we show here that titration of this microRNA failed to downregulate the basal translation efficiency of TOP mRNAs. Moreover, Drosha knockdown or Dicer knockout, which carries out the first and second processing steps in microRNAs biosynthesis, respectively, failed to block the translational activation of TOP mRNAs by amino acid or serum stimulation. Evidently, these results are questioning the positive role of microRNAs in this mode of regulation.
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Affiliation(s)
- Ilona Patursky-Polischuk
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Judith Kasir
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Rachel Miloslavski
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Zvi Hayouka
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Mirit Hausner-Hanochi
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Miri Stolovich-Rain
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Pinchas Tsukerman
- Lautenberg Center for General and Tumor Immunology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Moshe Biton
- Lautenberg Center for General and Tumor Immunology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Rajini Mudhasani
- Department of Cell Biology, University of Massachusetts Medical School, North Worcester, Massachusetts, United States of America
| | - Stephen N. Jones
- Department of Cell Biology, University of Massachusetts Medical School, North Worcester, Massachusetts, United States of America
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research – Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- * E-mail:
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33
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Bera A, Das F, Ghosh-Choudhury N, Kasinath BS, Abboud HE, Choudhury GG. microRNA-21-induced dissociation of PDCD4 from rictor contributes to Akt-IKKβ-mTORC1 axis to regulate renal cancer cell invasion. Exp Cell Res 2014; 328:99-117. [PMID: 25016284 PMCID: PMC4177976 DOI: 10.1016/j.yexcr.2014.06.022] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/27/2014] [Accepted: 06/28/2014] [Indexed: 12/13/2022]
Abstract
Renal cancer metastasis may result from oncogenic forces that contribute to the primary tumor. We have recently identified microRNA-21 as an oncogenic driver of renal cancer cells. The mechanism by which miR-21 controls renal cancer cell invasion is poorly understood. We show that miR-21 directly downregulates the proapoptotic protein PDCD4 to increase migration and invasion of ACHN and 786-O renal cancer cells as a result of phosphorylation/activation of Akt and IKKβ, which activate NFκB-dependent transcription. Constitutively active (CA) Akt or CA IKKβ blocks PDCD4-mediated inhibition and restores renal cancer cell migration and invasion. PDCD4 inhibits mTORC1 activity, which was reversed by CA IKKβ. Moreover, CA mTORC1 restores cell migration and invasion inhibited by PDCD4 and dominant negative IKKβ. Moreover, PDCD4 negatively regulates mTORC2-dependent Akt phosphorylation upstream of this cascade. We show that PDCD4 forms a complex with rictor, an exclusive component of mTORC2, and that this complex formation is reduced in renal cancer cells due to increased miR-21 expression resulting in enhanced phosphorylation of Akt. Thus our results identify a previously unrecognized signaling node where high miR-21 levels reduce rictor-PDCD4 interaction to increase phosphorylation of Akt and contribute to metastatic fitness of renal cancer cells.
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Affiliation(s)
- Amit Bera
- Department of Medicine, University of Texas Health Science Center at San Antonio, TX, USA
| | - Falguni Das
- Department of Medicine, University of Texas Health Science Center at San Antonio, TX, USA
| | - Nandini Ghosh-Choudhury
- Veterans Administration Research Service, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Pathology, University of Texas Health Science Center at San Antonio, TX, USA
| | - Balakuntalam S Kasinath
- Veterans Administration Research Service, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX, USA
| | - Hanna E Abboud
- Veterans Administration Research Service, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX, USA
| | - Goutam Ghosh Choudhury
- Veterans Administration Research Service, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX, USA; Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA.
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The structural basis for mTOR function. Semin Cell Dev Biol 2014; 36:91-101. [PMID: 25289568 DOI: 10.1016/j.semcdb.2014.09.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 01/22/2023]
Abstract
The phosphoinositide 3-kinase (PI3K) related protein kinases (PIKKs) are a family of protein kinases with a diverse range of vital cellular functions. Recent high-resolution crystal structures of the protein kinase mTOR suggest general architectural principles that are likely to be common to all of the PIKKs. Furthermore, the structures make clear the close relationship of the PIKKs to the PI3Ks. However, the structures also make clear the unique features of mTOR that enable its substrate specificity. The active site is deeply recessed and flanked by structural elements unique to the PIKKs, namely, the FRB domain, the LST8 binding element, and a C-terminal stretch of helices known as the FATC domain. The FRB has a conserved element in it that is part of a bipartite substrate recognition mechanism that is probably characteristic of all of the PIKKs. The FRB also binds the mTOR inhibitor rapamycin that has been referred to as an allosteric inhibitor, implying that this inhibitor is actually a competitive inhibitor of the protein substrate. This bipartite substrate-binding site also helps clarify how rapamycin can result in substrate-specific inhibition.
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35
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Fisher R, Horswell S, Rowan A, Salm MP, de Bruin EC, Gulati S, McGranahan N, Stares M, Gerlinger M, Varela I, Crockford A, Favero F, Quidville V, André F, Navas C, Grönroos E, Nicol D, Hazell S, Hrouda D, O’Brien T, Matthews N, Phillimore B, Begum S, Rabinowitz A, Biggs J, Bates PA, McDonald NQ, Stamp G, Spencer-Dene B, Hsieh JJ, Xu J, Pickering L, Gore M, Larkin J, Swanton C. Development of synchronous VHL syndrome tumors reveals contingencies and constraints to tumor evolution. Genome Biol 2014; 15:433. [PMID: 25159823 PMCID: PMC4166471 DOI: 10.1186/s13059-014-0433-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 08/08/2014] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Genomic analysis of multi-focal renal cell carcinomas from an individual with a germline VHL mutation offers a unique opportunity to study tumor evolution. RESULTS We perform whole exome sequencing on four clear cell renal cell carcinomas removed from both kidneys of a patient with a germline VHL mutation. We report that tumors arising in this context are clonally independent and harbour distinct secondary events exemplified by loss of chromosome 3p, despite an identical genetic background and tissue microenvironment. We propose that divergent mutational and copy number anomalies are contingent upon the nature of 3p loss of heterozygosity occurring early in tumorigenesis. However, despite distinct 3p events, genomic, proteomic and immunohistochemical analyses reveal evidence for convergence upon the PI3K-AKT-mTOR signaling pathway. Four germline tumors in this young patient, and in a second, older patient with VHL syndrome demonstrate minimal intra-tumor heterogeneity and mutational burden, and evaluable tumors appear to follow a linear evolutionary route, compared to tumors from patients with sporadic clear cell renal cell carcinoma. CONCLUSIONS In tumors developing from a germline VHL mutation, the evolutionary principles of contingency and convergence in tumor development are complementary. In this small set of patients with early stage VHL-associated tumors, there is reduced mutation burden and limited evidence of intra-tumor heterogeneity.
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Affiliation(s)
- Rosalie Fisher
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - Stuart Horswell
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Andrew Rowan
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | | | - Elza C de Bruin
- />University College London Cancer Institute, London, WC1E 6DD UK
| | - Sakshi Gulati
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Nicholas McGranahan
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
- />Centre for Mathematics & Physics in the Life Science & Experimental Biology (CoMPLEX), University College London, London, WC1E 6BT UK
| | - Mark Stares
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - Marco Gerlinger
- />Centre for Evolution and Cancer, Institute of Cancer Research, London, SW7 3RP UK
| | - Ignacio Varela
- />Instituto de Biomedicina y Biotecnología de Cantabria (CSIC-UC-Sodercan), Departamento de Biología Molecular, Universidad de Cantabria, Santander, 39011 Spain
| | - Andrew Crockford
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Francesco Favero
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
- />Cancer System Biology, Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Lyngby, DK-2800 Denmark
| | | | | | - Carolina Navas
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Eva Grönroos
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - David Nicol
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - Steve Hazell
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - David Hrouda
- />Imperial College Healthcare NHS Trust, London, W6 8RF UK
| | - Tim O’Brien
- />Guy’s and St Thomas’ NHS Foundation Trust, London, SE1 9RT UK
| | - Nik Matthews
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Ben Phillimore
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Sharmin Begum
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Adam Rabinowitz
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Jennifer Biggs
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Paul A Bates
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Neil Q McDonald
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | - Gordon Stamp
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
| | | | - James J Hsieh
- />Department of Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, 10065 USA
| | - Jianing Xu
- />Department of Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, 10065 USA
| | - Lisa Pickering
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - Martin Gore
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - James Larkin
- />Royal Marsden NHS Foundation Trust, London, SW3 6JJ UK
| | - Charles Swanton
- />Cancer Research UK London Research Institute, London, WC2A 3LY UK
- />University College London Cancer Institute, London, WC1E 6DD UK
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Kassai H, Sugaya Y, Noda S, Nakao K, Maeda T, Kano M, Aiba A. Selective activation of mTORC1 signaling recapitulates microcephaly, tuberous sclerosis, and neurodegenerative diseases. Cell Rep 2014; 7:1626-1639. [PMID: 24857653 DOI: 10.1016/j.celrep.2014.04.048] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 03/18/2014] [Accepted: 04/22/2014] [Indexed: 02/06/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) has been implicated in human neurological diseases such as tuberous sclerosis complex (TSC), neurodegeneration, and autism. However, little is known about when and how mTOR is involved in the pathogenesis of these diseases, due to a lack of animal models that directly increase mTOR activity. Here, we generated transgenic mice expressing a gain-of-function mutant of mTOR in the forebrain in a temporally controlled manner. Selective activation of mTORC1 in embryonic stages induced cortical atrophy caused by prominent apoptosis of neuronal progenitors, associated with upregulation of HIF-1α. In striking contrast, activation of the mTORC1 pathway in adulthood resulted in cortical hypertrophy with fatal epileptic seizures, recapitulating human TSC. Activated mTORC1 in the adult cortex also promoted rapid accumulation of cytoplasmic inclusions and activation of microglial cells, indicative of progressive neurodegeneration. Our findings demonstrate that mTORC1 plays different roles in developmental and adult stages and contributes to human neurological diseases.
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Affiliation(s)
- Hidetoshi Kassai
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yuki Sugaya
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Shoko Noda
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kazuki Nakao
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Tatsuya Maeda
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Atsu Aiba
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
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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.
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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
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Wagle N, Grabiner BC, Van Allen EM, Hodis E, Jacobus S, Supko JG, Stewart M, Choueiri TK, Gandhi L, Cleary JM, Elfiky AA, Taplin ME, Stack EC, Signoretti S, Loda M, Shapiro GI, Sabatini DM, Lander ES, Gabriel SB, Kantoff PW, Garraway LA, Rosenberg JE. Activating mTOR mutations in a patient with an extraordinary response on a phase I trial of everolimus and pazopanib. Cancer Discov 2014; 4:546-53. [PMID: 24625776 DOI: 10.1158/2159-8290.cd-13-0353] [Citation(s) in RCA: 232] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Understanding the genetic mechanisms of sensitivity to targeted anticancer therapies may improve patient selection, response to therapy, and rational treatment designs. One approach to increase this understanding involves detailed studies of exceptional responders: rare patients with unexpected exquisite sensitivity or durable responses to therapy. We identified an exceptional responder in a phase I study of pazopanib and everolimus in advanced solid tumors. Whole-exome sequencing of a patient with a 14-month complete response on this trial revealed two concurrent mutations in mTOR, the target of everolimus. In vitro experiments demonstrate that both mutations are activating, suggesting a biologic mechanism for exquisite sensitivity to everolimus in this patient. The use of precision (or "personalized") medicine approaches to screen patients with cancer for alterations in the mTOR pathway may help to identify subsets of patients who may benefit from targeted therapies directed against mTOR.
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Affiliation(s)
- Nikhil Wagle
- Departments of 1Medical Oncology and 2Biostatistics and Computational Biology, 3Center for Molecular Oncologic Pathology, Dana-Farber Cancer Institute; Departments of 4Medicine and 5Pathology, Brigham and Women's Hospital, Harvard Medical School; 6Division of Hematology/Oncology, Massachusetts General Hospital, Boston; 7Broad Institute of Harvard and MIT; 8Department of Biology, Whitehead Institute for Biomedical Research; 9Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts; and 10Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York
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Association of maternal mRNA and phosphorylated EIF4EBP1 variants with the spindle in mouse oocytes: localized translational control supporting female meiosis in mammals. Genetics 2013; 195:349-58. [PMID: 23852387 DOI: 10.1534/genetics.113.154005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In contrast to other species, localized maternal mRNAs are not believed to be prominent features of mammalian oocytes. We find by cDNA microarray analysis enrichment for maternal mRNAs encoding spindle and other proteins on the mouse oocyte metaphase II (MII) spindle. We also find that the key translational regulator, EIF4EBP1, undergoes a dynamic and complex spatially regulated pattern of phosphorylation at sites that regulate its association with EIF4E and its ability to repress translation. These phosphorylation variants appear at different positions along the spindle at different stages of meiosis. These results indicate that dynamic spatially restricted patterns of EIF4EBP1 phosphorylation may promote localized mRNA translation to support spindle formation, maintenance, function, and other nearby processes. Regulated EIF4EBP1 phosphorylation at the spindle may help coordinate spindle formation with progression through the cell cycle. The discovery that EIF4EBP1 may be part of an overall mechanism that integrates and couples cell cycle progression to mRNA translation and subsequent spindle formation and function may be relevant to understanding mechanisms leading to diminished oocyte quality, and potential means of avoiding such defects. The localization of maternal mRNAs at the spindle is evolutionarily conserved between mammals and other vertebrates and is also seen in mitotic cells, indicating that EIF4EBP1 control of localized mRNA translation is likely key to correct segregation of genetic material across cell types.
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Abstract
The target of rapamycin (TOR) is an evolutionarily conserved protein kinase that regulates cell growth in response to various environmental as well as intracellular cues through the formation of 2 distinct TOR complexes (TORC), TORC1 and TORC2. Dysregulation of TORC1 and TORC2 activity is closely associated with various diseases, including diabetes, cancer and neurodegenerative disorders. Over the past few years, new regulatory mechanisms of TORC1 and TORC2 activity have been elucidated. Furthermore, recent advances in the study of TOR inhibitors have revealed previously unrecognized cellular functions of TORC1. In this review, we briefly summarize the current understanding of the evolutionarily conserved TOR signalling from upstream regulators to downstream events.
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Affiliation(s)
- Terunao Takahara
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Japan
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41
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Yang H, Rudge DG, Koos JD, Vaidialingam B, Yang HJ, Pavletich NP. mTOR kinase structure, mechanism and regulation. Nature 2013; 497:217-23. [PMID: 23636326 PMCID: PMC4512754 DOI: 10.1038/nature12122] [Citation(s) in RCA: 745] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 03/26/2013] [Indexed: 12/30/2022]
Abstract
The mammalian target of rapamycin (mTOR), a phosphoinositide 3-kinase-related protein kinase, controls cell growth in response to nutrients and growth factors and is frequently deregulated in cancer. Here we report co-crystal structures of a complex of truncated mTOR and mammalian lethal with SEC13 protein 8 (mLST8) with an ATP transition state mimic and with ATP-site inhibitors. The structures reveal an intrinsically active kinase conformation, with catalytic residues and a catalytic mechanism remarkably similar to canonical protein kinases. The active site is highly recessed owing to the FKBP12-rapamycin-binding (FRB) domain and an inhibitory helix protruding from the catalytic cleft. mTOR-activating mutations map to the structural framework that holds these elements in place, indicating that the kinase is controlled by restricted access. In vitro biochemistry shows that the FRB domain acts as a gatekeeper, with its rapamycin-binding site interacting with substrates to grant them access to the restricted active site. Rapamycin-FKBP12 inhibits the kinase by directly blocking substrate recruitment and by further restricting active-site access. The structures also reveal active-site residues and conformational changes that underlie inhibitor potency and specificity.
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Affiliation(s)
- Haijuan Yang
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA
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42
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Murugan AK, Alzahrani A, Xing M. Mutations in critical domains confer the human mTOR gene strong tumorigenicity. J Biol Chem 2013; 288:6511-21. [PMID: 23322780 DOI: 10.1074/jbc.m112.399485] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that regulates cell growth, proliferation, and survival. mTOR is frequently activated in human cancers and is a commonly sought anticancer therapeutic target. However, whether the human mTOR gene itself is a proto-oncogene possessing tumorigenicity has not been firmly established. To answer this question, we mutated evolutionarily conserved amino acids, generated eight mutants in the HEAT repeats (M938T) and the FAT (W1456R and G1479N) and kinase (P2273S, V2284M, V2291I, T2294I, and E2288K) domains of mTOR, and studied their oncogenicity. On transient expression in HEK293T cells, these mTOR mutants displayed elevated protein kinase activities accompanied by activated mTOR/p70S6K signaling at varying levels, demonstrating the gain of function of the mTOR gene with these mutations. We selected P2273S and E2288K, the two most catalytically active mutants, to further examine their oncogenicity and tumorigenicity. Stable expression of the two mTOR mutants in NIH3T3 cells strongly activated mTOR/p70S6K signaling, induced cell transformation and invasion, and remarkably, caused rapid tumor formation and growth in athymic nude mice after subcutaneous inoculation of the transfected cells. This study confirms the oncogenic potential of mTOR suggested previously and demonstrates for the first time its tumorigenicity. Thus, beyond the pivotal position of mTOR to relay the oncogenic signals from the upstream phosphatidylinositol 3-kinase/Akt pathway in human cancer, mTOR is capable potentially of playing a direct role in human tumorigenesis if mutated. These results also further support the conclusion that mTOR is a major therapeutic target in human cancers.
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Affiliation(s)
- Avaniyapuram Kannan Murugan
- Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Grabinski N, Ewald F, Hofmann BT, Staufer K, Schumacher U, Nashan B, Jücker M. Combined targeting of AKT and mTOR synergistically inhibits proliferation of hepatocellular carcinoma cells. Mol Cancer 2012; 11:85. [PMID: 23167739 PMCID: PMC3545733 DOI: 10.1186/1476-4598-11-85] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 11/13/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Due to the frequent dysregulation of the PI3K/AKT/mTOR signaling pathway, mTOR represents a suitable therapeutic target in hepatocellular carcinoma (HCC). However, emerging data from clinical trials of HCC patients indicate that mTOR inhibition by RAD001 (Everolimus) alone has only moderate antitumor efficacy which may be due to the feedback activation of AKT after mTOR inhibition. In this study, we analyzed the effects of dual inhibition of mTOR and AKT on the proliferation of HCC cell lines. In addition, we measured the feedback activation of each of the AKT isoforms after mTOR inhibition in HCC cell lines and their enzymatic activity in primary samples from HCC patients. METHODS The activation status of specific AKT isoforms in human HCC samples and corresponding healthy liver tissue was analyzed using an AKT isoform specific in vitro kinase assay. AKT isoform activation after mTOR inhibition was analyzed in three HCC cell lines (Hep3B, HepG2 and Huh7), and the impact of AKT signaling on proliferation after mTOR inhibition was investigated using the novel AKT inhibitor MK-2206 and AKT isoform specific knockdown cells. RESULTS AKT isoforms become differentially activated during feedback activation following RAD001 treatment. The combination of mTOR inhibition and AKT isoform knockdown showed only a weak synergistic effect on proliferation of HCC cell lines. However, the combinatorial treatment with RAD001 and the pan AKT inhibitor MK-2206 resulted in a strong synergism, both in vitro and in vivo. Moreover, by analyzing primary HCC tissue samples we were able to demonstrate that a hotspot mutation (H1047R) of PI3KCA, the gene encoding the catalytic subunit of PI3K, was associated with increased in vitro kinase activity of all AKT isoforms in comparison to healthy liver tissue of the patient. CONCLUSION Our results demonstrate that dual targeting of mTOR and AKT by use of RAD001 and the pan AKT inhibitor MK-2206 does effectively inhibit proliferation of HCC cell lines. These data suggest that combined treatment with RAD001 and MK-2206 may be a promising therapy approach in the treatment of hepatocellular carcinoma.
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Affiliation(s)
- Nicole Grabinski
- Center for Experimental Medicine, Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Hamburg 20246, Germany
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Dey N, Ghosh-Choudhury N, Kasinath BS, Choudhury GG. TGFβ-stimulated microRNA-21 utilizes PTEN to orchestrate AKT/mTORC1 signaling for mesangial cell hypertrophy and matrix expansion. PLoS One 2012; 7:e42316. [PMID: 22879939 PMCID: PMC3411779 DOI: 10.1371/journal.pone.0042316] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/02/2012] [Indexed: 12/20/2022] Open
Abstract
Transforming growth factor-β (TGFβ) promotes glomerular hypertrophy and matrix expansion, leading to glomerulosclerosis. MicroRNAs are well suited to promote fibrosis because they can repress gene expression, which negatively regulate the fibrotic process. Recent cellular and animal studies have revealed enhanced expression of microRNA, miR-21, in renal cells in response to TGFβ. Specific miR-21 targets downstream of TGFβ receptor activation that control cell hypertrophy and matrix protein expression have not been studied. Using 3′UTR-driven luciferase reporter, we identified the tumor suppressor protein PTEN as a target of TGFβ-stimulated miR-21 in glomerular mesangial cells. Expression of miR-21 Sponge, which quenches endogenous miR-21 levels, reversed TGFβ-induced suppression of PTEN. Additionally, miR-21 Sponge inhibited TGFβ-stimulated phosphorylation of Akt kinase, resulting in attenuation of phosphorylation of its substrate GSK3β. Tuberin and PRAS40, two other Akt substrates, and endogenous inhibitors of mTORC1, regulate mesangial cell hypertrophy. Neutralization of endogenous miR-21 abrogated TGFβ-stimulated phosphorylation of tuberin and PRAS40, leading to inhibition of phosphorylation of S6 kinase, mTOR and 4EBP-1. Moreover, downregulation of miR-21 significantly suppressed TGFβ-induced protein synthesis and hypertrophy, which were reversed by siRNA-targeted inhibition of PTEN expression. Similarly, expression of constitutively active Akt kinase reversed the miR-21 Sponge-mediated inhibition of TGFβ-induced protein synthesis and hypertrophy. Furthermore, expression of constitutively active mTORC1 prevented the miR-21 Sponge-induced suppression of mesangial cell protein synthesis and hypertrophy by TGFβ. Finally, we show that miR-21 Sponge inhibited TGFβ-stimulated fibronectin and collagen expression. Suppression of PTEN expression and expression of both constitutively active Akt kinase and mTORC1 independently reversed this miR-21-mediated inhibition of TGFβ-induced fibronectin and collagen expression. Our results uncover an essential role of TGFβ-induced expression of miR-21, which targets PTEN to initiate a non-canonical signaling circuit involving Akt/mTORC1 axis for mesangial cell hypertrophy and matrix protein synthesis.
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Affiliation(s)
- Nirmalya Dey
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Nandini Ghosh-Choudhury
- Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
| | - Balakuntalam S. Kasinath
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
| | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
- * E-mail:
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45
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Chen J, Shao P, Cao Q, Li P, Li J, Cai H, Zhu J, Wang M, Zhang Z, Qin C, Yin C. Genetic variations in a PTEN/AKT/mTOR axis and prostate cancer risk in a Chinese population. PLoS One 2012; 7:e40817. [PMID: 22815832 PMCID: PMC3399895 DOI: 10.1371/journal.pone.0040817] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 06/13/2012] [Indexed: 12/11/2022] Open
Abstract
Backgroud Genetic variations in a PTEN/AKT/mTOR signaling axis may influence cellular functions including cell growth, proliferation and apoptosis, and then increase the individual’s risk of cancer. Accordingly, we explore the association between single nucleotide polymorphisms (SNPs) of these genes and prostate cancer (PCa) in our Chinese population. Methods Subjects were recruited from 666 PCa patients and 708 cancer-free controls, and eight SNPs in the PTEN/AKT/mTOR axis were determined by the TaqMan assay. Odds ratios (OR) and 95% confidence intervals (95% CI) were evaluated by logistic regression. Results We observed significant associations between PCa risk and mTOR rs2295080 [P = 0.027, OR = 0.85, 95%CI = 0.74–0.98], and AKT2 rs7254617 (P = 0.003, OR = 1.35, 95%CI = 1.11–1.64). When estimated these two SNPs together, the combined genotypes with 2–4 risk alleles (rs2295080 T and rs7254617 A alleles) were associated with an increased risk of PCa compared with 0–1 risk alleles, which was more pronounced among subgroups of age >71 years, smokers, drinkers and no family history of cancer. Results of stratified analyses by cliniopathological parameters revealed that the frequencies of the combined genotypes with 2–4 risk alleles in advanced stage were significantly higher than in localized stage(P = 0.022), but there was no significant association in Gleason score and PSA level. Conclusion Our results indicate, for the first time that the two variants in AKT2 and mTOR, particularly the joint genotypes with 2–4 risk alleles may influence PCa susceptibility and progression in Chinese, and the association appeared to be more strong in the subgroup of smokers and drinkers.
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Affiliation(s)
- Jiawei Chen
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Pengfei Shao
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qiang Cao
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Pu Li
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jie Li
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hongzhou Cai
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jian Zhu
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Meilin Wang
- Department of Molecular and Genetic Toxicology, Cancer Center of Nanjing Medical University, Nanjing, China
| | - Zhengdong Zhang
- Department of Molecular and Genetic Toxicology, Cancer Center of Nanjing Medical University, Nanjing, China
| | - Chao Qin
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- * E-mail: (CY); (CQ)
| | - Changjun Yin
- State Key Laboratory of Reproductive Medicine, Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- * E-mail: (CY); (CQ)
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Takahara T, Maeda T. TORC1 of fission yeast is rapamycin-sensitive. Genes Cells 2012; 17:698-708. [PMID: 22762302 DOI: 10.1111/j.1365-2443.2012.01618.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 05/04/2012] [Indexed: 11/30/2022]
Abstract
The target of rapamycin (TOR) protein kinase plays central roles in the regulation of cell growth in response to nutritional availability. TOR forms two distinct multiprotein complexes termed TOR complex 1 (TORC1) and TORC2. Typically, only the activity of TORC1 is inhibited by the immunosuppressant rapamycin. Although rapamycin strongly inhibits cell growth of the budding yeast Saccharomyces cerevisiae through inhibition of TORC1, growth of the fission yeast Schizosaccharomyces pombe appears to be resistant to rapamycin. Here, we demonstrate that rapamycin inhibits the kinase activity of S. pombe TORC1 in vitro in a similar manner to TORC1 of other organisms. We furthermore show that incomplete inhibition of TORC1 by rapamycin underlies the apparent rapamycin resistance of S. pombe. In the presence of caffeine, which potentially lowers TORC1 activity, the growth of wild-type S. pombe cells is sensitive to rapamycin in a TORC1-dependent manner. Moreover, treatment of S. pombe cells with rapamycin plus caffeine induces starvation-specific gene expression and autophagy, similarly to cells with reduced TORC1 activity. These results indicate that rapamycin does inhibit TORC1 in S. pombe, but the inhibition is not sufficient to cause a growth defect. These findings establish a universal action of rapamycin on TORC1 inhibition.
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Affiliation(s)
- Terunao Takahara
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Dey N, Das F, Ghosh-Choudhury N, Mandal CC, Parekh DJ, Block K, Kasinath BS, Abboud HE, Choudhury GG. microRNA-21 governs TORC1 activation in renal cancer cell proliferation and invasion. PLoS One 2012; 7:e37366. [PMID: 22685542 PMCID: PMC3368259 DOI: 10.1371/journal.pone.0037366] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 04/20/2012] [Indexed: 02/07/2023] Open
Abstract
Metastatic renal cancer manifests multiple signatures of gene expression. Deviation in expression of mature miRNAs has been linked to human cancers. Importance of miR-21 in renal cell carcinomas is proposed from profiling studies using tumor tissue samples. However, the role of miR-21 function in causing renal cancer cell proliferation and invasion has not yet been shown. Using cultured renal carcinoma cells, we demonstrate enhanced expression of mature miR-21 along with pre-and pri-miR-21 by increased transcription compared to normal proximal tubular epithelial cells. Overexpression of miR-21 Sponge to quench endogenous miR-21 levels inhibited proliferation, migration and invasion of renal cancer cells. In the absence of mutation in the PTEN tumor suppressor gene, PTEN protein levels are frequently downregulated in renal cancer. We show that miR-21 targets PTEN mRNA 3'untranslated region to decrease PTEN protein expression and augments Akt phosphorylation in renal cancer cells. Downregulation of PTEN as well as overexpression of constitutively active Akt kinase prevented miR-21 Sponge-induced inhibition of renal cancer cell proliferation and migration. Moreover, we show that miR-21 Sponge inhibited the inactivating phosphorylation of the tumor suppressor protein tuberin and attenuated TORC1 activation. Finally, we demonstrate that expression of constitutively active TORC1 attenuated miR-21 Sponge-mediated suppression of proliferation and migration of renal cancer cells. Our results uncover a layer of post-transcriptional regulation of PTEN by transcriptional activation of miR-21 to force the canonical oncogenic Akt/TORC1 signaling conduit to drive renal cancer cell proliferation and invasion.
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Affiliation(s)
- Nirmalya Dey
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Falguni Das
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Nandini Ghosh-Choudhury
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
- Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Chandi Charan Mandal
- Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Dipen J. Parekh
- Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Karen Block
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
| | - Balakuntalam S. Kasinath
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
| | - Hanna E. Abboud
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
| | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Veterans Administration Research, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
- Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, United States of America
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48
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Das F, Ghosh-Choudhury N, Dey N, Mandal CC, Mahimainathan L, Kasinath BS, Abboud HE, Choudhury GG. Unrestrained mammalian target of rapamycin complexes 1 and 2 increase expression of phosphatase and tensin homolog deleted on chromosome 10 to regulate phosphorylation of Akt kinase. J Biol Chem 2011; 287:3808-22. [PMID: 22184110 DOI: 10.1074/jbc.m111.246397] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tuberous sclerosis complex 2 (TSC2) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) function to block growth factor-induced mammalian target of rapamycin (mTOR) signaling and are mutated in autosomal dominant hamartoma syndromes. mTOR binds to a spectrum of common and different proteins to form TOR complex 1 (TORC1) and TORC2, which regulate cell growth, division, and metabolism. TSC2 deficiency induces constitutive activation of mTOR, leading to a state of insulin resistance due to a negative feedback regulation, resulting in reduced Akt phosphorylation. We have recently described an alternative mechanism showing that in TSC2 deficiency, enhanced PTEN expression contributes to reduced Akt phosphorylation. To explore the mechanism of PTEN regulation, we used rapamycin and constitutively active mTOR to show that TORC1 increases the expression of PTEN mRNA and protein. We found that in TSC2(-/-) mouse embryonic fibroblasts expression of a kinase-dead mutant of mTOR, which inhibits both TORC1 and TORC2, decreases the expression of PTEN via transcriptional mechanism. Furthermore, kinase-dead mTOR increased and decreased phosphorylation of Akt at catalytic loop site Thr-308 and hydrophobic motif site Ser-473, respectively. Moreover, inhibition of deregulated TORC1 in TSC2-null mouse embryonic fibroblasts or in 293 cells by down-regulation of raptor decreased the levels of the transcription factor Hif1α and blocked PTEN expression, resulting in enhanced phosphorylation of Akt at Thr-308 and Ser-473. Finally, knockdown of rictor or mSin1 attenuated the expression of Hif1α, which decreased transcription of PTEN. These results unravel a previously unrecognized cell-autonomous function of TORC1 and TORC2 in the up-regulation of PTEN, which prevents phosphorylation of Akt and may shield against the development of malignancy in TSC patients.
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Affiliation(s)
- Falguni Das
- Veterans Affairs Research, South Texas Veterans Health Care System, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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Loewith R, Hall MN. Target of rapamycin (TOR) in nutrient signaling and growth control. Genetics 2011; 189:1177-201. [PMID: 22174183 PMCID: PMC3241408 DOI: 10.1534/genetics.111.133363] [Citation(s) in RCA: 642] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 09/12/2011] [Indexed: 12/16/2022] Open
Abstract
TOR (Target Of Rapamycin) is a highly conserved protein kinase that is important in both fundamental and clinical biology. In fundamental biology, TOR is a nutrient-sensitive, central controller of cell growth and aging. In clinical biology, TOR is implicated in many diseases and is the target of the drug rapamycin used in three different therapeutic areas. The yeast Saccharomyces cerevisiae has played a prominent role in both the discovery of TOR and the elucidation of its function. Here we review the TOR signaling network in S. cerevisiae.
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Affiliation(s)
- Robbie Loewith
- Department of Molecular Biology and National Centers of Competence in Research and Frontiers in Genetics and Chemical Biology, University of Geneva, Geneva, CH-1211, Switzerland
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50
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Abstract
The mechanistic (or mammalian) target of rapamycin (mTOR), an evolutionarily conserved protein kinase, orchestrates cellular responses to growth, metabolic and stress signals. mTOR processes various extracellular and intracellular inputs as part of two mTOR protein complexes, mTORC1 or mTORC2. The mTORCs have numerous cellular targets but members of a family of protein kinases, the protein kinase (PK)A/PKG/PKC (AGC) family are the best characterized direct mTOR substrates. The AGC kinases control multiple cellular functions and deregulation of many members of this family underlies numerous pathological conditions. mTOR phosphorylates conserved motifs in these kinases to allosterically augment their activity, influence substrate specificity, and promote protein maturation and stability. Activation of AGC kinases in turn triggers the phosphorylation of diverse, often overlapping, targets that ultimately control cellular response to a wide spectrum of stimuli. This review will highlight recent findings on how mTOR regulates AGC kinases and how mTOR activity is feedback regulated by these kinases. We will discuss how this regulation can modulate downstream targets in the mTOR pathway that could account for the varied cellular functions of mTOR.
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Affiliation(s)
- Bing Su
- Department of Immunobiology and The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT, USA.
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