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Rahman M, Nguyen TM, Lee GJ, Kim B, Park MK, Lee CH. Unraveling the Role of Ras Homolog Enriched in Brain (Rheb1 and Rheb2): Bridging Neuronal Dynamics and Cancer Pathogenesis through Mechanistic Target of Rapamycin Signaling. Int J Mol Sci 2024; 25:1489. [PMID: 38338768 PMCID: PMC10855792 DOI: 10.3390/ijms25031489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/14/2024] [Accepted: 01/17/2024] [Indexed: 02/12/2024] Open
Abstract
Ras homolog enriched in brain (Rheb1 and Rheb2), small GTPases, play a crucial role in regulating neuronal activity and have gained attention for their implications in cancer development, particularly in breast cancer. This study delves into the intricate connection between the multifaceted functions of Rheb1 in neurons and cancer, with a specific focus on the mTOR pathway. It aims to elucidate Rheb1's involvement in pivotal cellular processes such as proliferation, apoptosis resistance, migration, invasion, metastasis, and inflammatory responses while acknowledging that Rheb2 has not been extensively studied. Despite the recognized associations, a comprehensive understanding of the intricate interplay between Rheb1 and Rheb2 and their roles in both nerve and cancer remains elusive. This review consolidates current knowledge regarding the impact of Rheb1 on cancer hallmarks and explores the potential of Rheb1 as a therapeutic target in cancer treatment. It emphasizes the necessity for a deeper comprehension of the molecular mechanisms underlying Rheb1-mediated oncogenic processes, underscoring the existing gaps in our understanding. Additionally, the review highlights the exploration of Rheb1 inhibitors as a promising avenue for cancer therapy. By shedding light on the complicated roles between Rheb1/Rheb2 and cancer, this study provides valuable insights to the scientific community. These insights are instrumental in guiding the identification of novel targets and advancing the development of effective therapeutic strategies for treating cancer.
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Affiliation(s)
- Mostafizur Rahman
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Tuan Minh Nguyen
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Gi Jeong Lee
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Boram Kim
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Mi Kyung Park
- Department of BioHealthcare, Hwasung Medi-Science University, Hwaseong-si 18274, Republic of Korea
| | - Chang Hoon Lee
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
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2
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Tang J, Yang L, Guan F, Miller H, Camara NOS, James LK, Benlagha K, Kubo M, Heegaard S, Lee P, Lei J, Zeng H, He C, Zhai Z, Liu C. The role of Raptor in lymphocytes differentiation and function. Front Immunol 2023; 14:1146628. [PMID: 37283744 PMCID: PMC10239924 DOI: 10.3389/fimmu.2023.1146628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 04/28/2023] [Indexed: 06/08/2023] Open
Abstract
Raptor, a key component of mTORC1, is required for recruiting substrates to mTORC1 and contributing to its subcellular localization. Raptor has a highly conserved N-terminus domain and seven WD40 repeats, which interact with mTOR and other mTORC1-related proteins. mTORC1 participates in various cellular events and mediates differentiation and metabolism. Directly or indirectly, many factors mediate the differentiation and function of lymphocytes that is essential for immunity. In this review, we summarize the role of Raptor in lymphocytes differentiation and function, whereby Raptor mediates the secretion of cytokines to induce early lymphocyte metabolism, development, proliferation and migration. Additionally, Raptor regulates the function of lymphocytes by regulating their steady-state maintenance and activation.
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Affiliation(s)
- Jianing Tang
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Lu Yang
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Fei Guan
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Heather Miller
- Cytek Biosciences, R&D Clinical Reagents, Fremont, CA, United States
| | - Niels Olsen Saraiva Camara
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Louisa K. James
- Centre for Immunobiology, Bizard Institute, Queen Mary University of London, London, United Kingdom
| | - Kamel Benlagha
- Université de Paris, Institut de Recherche Saint-Louis, EMiLy, Paris, France
| | - Masato Kubo
- Laboratory for Cytokine Regulation, Center for Integrative Medical Science (IMS), Rikagaku Kenkyusho, Institute of Physical and Chemical Research (RIKEN) Yokohama Institute, Yokohama, Japan
| | - Steffen Heegaard
- Department of Ophthalmology, Rigshospitalet Glostrup, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Pamela Lee
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Jiahui Lei
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Hu Zeng
- Department of Immunology, Mayo Clinic, Rochester, MN, United States
- Division of Rheumatology, Department of Medicine, Mayo Clinic, Rochester, MN, United States
| | - Chengwei He
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macao SAR, China
| | - Zhimin Zhai
- Department of Hematology, The Second Hospital of Anhui Medical University, Hefei, China
| | - Chaohong Liu
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
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3
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Hussein AM, Balachandar N, Mathieu J, Ruohola-Baker H. Molecular Regulators of Embryonic Diapause and Cancer Diapause-like State. Cells 2022; 11:cells11192929. [PMID: 36230891 PMCID: PMC9562880 DOI: 10.3390/cells11192929] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022] Open
Abstract
Embryonic diapause is an enigmatic state of dormancy that interrupts the normally tight connection between developmental stages and time. This reproductive strategy and state of suspended development occurs in mice, bears, roe deer, and over 130 other mammals and favors the survival of newborns. Diapause arrests the embryo at the blastocyst stage, delaying the post-implantation development of the embryo. This months-long quiescence is reversible, in contrast to senescence that occurs in aging stem cells. Recent studies have revealed critical regulators of diapause. These findings are important since defects in the diapause state can cause a lack of regeneration and control of normal growth. Controlling this state may also have therapeutic applications since recent findings suggest that radiation and chemotherapy may lead some cancer cells to a protective diapause-like, reversible state. Interestingly, recent studies have shown the metabolic regulation of epigenetic modifications and the role of microRNAs in embryonic diapause. In this review, we discuss the molecular mechanism of diapause induction.
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Affiliation(s)
- Abdiasis M. Hussein
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Nanditaa Balachandar
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
- Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Chennai 603203, India
| | - Julie Mathieu
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
- Department of Comparative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Hannele Ruohola-Baker
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
- Correspondence:
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Liu Y, Zhong W, Zhang J, Chen W, Lu Y, Qiao Y, Zeng Z, Huang H, Cai S, Dong H. Tetrandrine Modulates Rheb-mTOR Signaling-Mediated Selective Autophagy and Protects Pulmonary Fibrosis. Front Pharmacol 2021; 12:739220. [PMID: 34880752 PMCID: PMC8645995 DOI: 10.3389/fphar.2021.739220] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 10/06/2021] [Indexed: 11/13/2022] Open
Abstract
Idiopathic pulmonary fibrosis is a progressive fatal disease characterized by interstitial remodeling, with high lethality and a lack of effective medical therapies. Tetrandrine has been proposed to present anti-fibrotic effects, but the efficacy and mechanisms have not been systematically evaluated. We sought to study the potential therapeutic effects and mechanisms of tetrandrine against lung fibrosis. The anti-fibrotic effects of tetrandrine were evaluated in bleomycin-induced mouse models and TGF-β1-stimulated murine lung fibroblasts. We performed Chromatin Immunoprecipitation (ChIP), Immunoprecipitation (IP), and mRFP-GFP-MAP1LC3B adenovirus construct to investigate the novel mechanisms of tetrandrine-induced autophagy. Tetrandrine decreased TGF-β1-induced expression of α-smooth muscle actin, fibronectin, vimentin, and type 1 collagen and proliferation in fibroblasts. Tetrandrine restored TGF-β1-induced impaired autophagy flux, accompanied by enhanced interaction of SQSTM1 and MAP1LC3-Ⅱ. ChIP studies revealed that tetrandrine induced autophagy via increasing binding of NRF2 and SQSTM1 promoter. Furthermore, tetrandrine inhibited TGF-β1-induced phosphorylation of mTOR by reducing activation of Rheb. In vivo tetrandrine suppressed the bleomycin-induced expression of fibrotic markers and improved pulmonary function. Our data suggest that protective effect of tetrandrine against lung fibrosis might be through promoting Rheb-mTOR and NRF2-SQSTM1 mediated autophagy. Tetrandrine may thus be potentially employed as a novel therapeutic medicine against IPF.
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Affiliation(s)
- Yuanyuan Liu
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Wenshan Zhong
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jinming Zhang
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Weimou Chen
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Ye Lu
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yujie Qiao
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhaojin Zeng
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Haohua Huang
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Shaoxi Cai
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hangming Dong
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, China
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5
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Koene LM, Niggl E, Wallaard I, Proietti-Onori M, Rotaru DC, Elgersma Y. Identifying the temporal electrophysiological and molecular changes that contribute to TSC-associated epileptogenesis. JCI Insight 2021; 6:150120. [PMID: 34877936 PMCID: PMC8675202 DOI: 10.1172/jci.insight.150120] [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: 03/31/2021] [Accepted: 10/27/2021] [Indexed: 11/17/2022] Open
Abstract
Tuberous sclerosis complex (TSC), caused by heterozygous mutations in TSC1 or TSC2, frequently results in intractable epilepsy. Here, we made use of an inducible Tsc1-knockout mouse model, allowing us to study electrophysiological and molecular changes of Tsc1-induced epileptogenesis over time. We recorded from pyramidal neurons in the hippocampus and somatosensory cortex (L2/L3) and combined this with an analysis of transcriptome changes during epileptogenesis. Deletion of Tsc1 resulted in hippocampus-specific changes in excitability and adaptation, which emerged before seizure onset and progressed over time. All phenotypes were rescued after early treatment with rapamycin, an mTOR inhibitor. Later in epileptogenesis, we observed a hippocampal increase of excitation-to-inhibition ratio. These cellular changes were accompanied by dramatic transcriptional changes, especially after seizure onset. Most of these changes were rescued upon rapamycin treatment. Of the genes encoding ion channels or belonging to the Gene Ontology term action potential, 27 were differentially expressed just before seizure onset, suggesting a potential driving role in epileptogenesis. Our data highlight the complex changes driving epileptogenesis in TSC, including the changed expression of multiple ion channels. Our study emphasizes inhibition of the TSC/mTOR signaling pathway as a promising therapeutic approach to target epilepsy in patients with TSC.
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De D, Mukherjee I, Guha S, Paidi RK, Chakrabarti S, Biswas SC, Bhattacharyya SN. Rheb-mTOR activation rescues Aβ-induced cognitive impairment and memory function by restoring miR-146 activity in glial cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 24:868-887. [PMID: 34094708 PMCID: PMC8141608 DOI: 10.1016/j.omtn.2021.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 04/09/2021] [Indexed: 12/22/2022]
Abstract
Deposition of amyloid beta plaques in adult rat or human brain is associated with increased production of proinflammatory cytokines by associated glial cells that are responsible for degeneration of the diseased tissue. The expression of these cytokines is usually under check and is controlled at the post-transcriptional level via several microRNAs. Computational analysis of gene expression profiles of cortical regions of Alzheimer’s disease patients’ brain suggests ineffective target cytokine mRNA suppression by existing micro-ribonucleoproteins (miRNPs) in diseased brain. Exploring the mechanism of amyloid beta-induced cytokine expression, we have identified how the inactivation of the repressive miR-146 miRNPs causes increased production of cytokines in amyloid beta-exposed glial cells. In exploration of the cause of miRNP inactivation, we have noted amyloid beta oligomer-induced sequestration of the mTORC1 complex to early endosomes that results in decreased Ago2 phosphorylation, limited Ago2-miRNA uncoupling, and retarded Ago2-cytokine mRNA interaction in rat astrocytes. Interestingly, constitutive activation of mTORC1 by Rheb activator restricts proinflammatory cytokine production by reactivating miR-146 miRNPs in amyloid beta-exposed glial cells to rescue the disease phenotype in the in vivo rat model of Alzheimer’s disease.
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Affiliation(s)
- Dipayan De
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Ishita Mukherjee
- Structural Biology and Bio-informatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Subhalakshmi Guha
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Ramesh Kumar Paidi
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Saikat Chakrabarti
- Structural Biology and Bio-informatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Subhas C Biswas
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Suvendra N Bhattacharyya
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
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7
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Birkisdóttir MB, Jaarsma D, Brandt RMC, Barnhoorn S, Vliet N, Imholz S, Oostrom CT, Nagarajah B, Portilla Fernández E, Roks AJM, Elgersma Y, Steeg H, Ferreira JA, Pennings JLA, Hoeijmakers JHJ, Vermeij WP, Dollé MET. Unlike dietary restriction, rapamycin fails to extend lifespan and reduce transcription stress in progeroid DNA repair-deficient mice. Aging Cell 2021; 20:e13302. [PMID: 33484480 PMCID: PMC7884048 DOI: 10.1111/acel.13302] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/03/2020] [Accepted: 12/07/2020] [Indexed: 12/31/2022] Open
Abstract
Dietary restriction (DR) and rapamycin extend healthspan and life span across multiple species. We have recently shown that DR in progeroid DNA repair‐deficient mice dramatically extended healthspan and trippled life span. Here, we show that rapamycin, while significantly lowering mTOR signaling, failed to improve life span nor healthspan of DNA repair‐deficient Ercc1∆/− mice, contrary to DR tested in parallel. Rapamycin interventions focusing on dosage, gender, and timing all were unable to alter life span. Even genetically modifying mTOR signaling failed to increase life span of DNA repair‐deficient mice. The absence of effects by rapamycin on P53 in brain and transcription stress in liver is in sharp contrast with results obtained by DR, and appoints reducing DNA damage and transcription stress as an important mode of action of DR, lacking by rapamycin. Together, this indicates that mTOR inhibition does not mediate the beneficial effects of DR in progeroid mice, revealing that DR and rapamycin strongly differ in their modes of action.
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Affiliation(s)
- María B. Birkisdóttir
- Princess Máxima Center for Pediatric Oncology, Genome Instability and Nutrition ONCODE Institute Utrecht The Netherlands
| | - Dick Jaarsma
- Department of Neuroscience Erasmus MC Rotterdam The Netherlands
| | | | - Sander Barnhoorn
- Department of Molecular Genetics Erasmus MC Rotterdam The Netherlands
| | - Nicole Vliet
- Department of Molecular Genetics Erasmus MC Rotterdam The Netherlands
| | - Sandra Imholz
- Centre for Health Protection National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
| | - Conny T. Oostrom
- Centre for Health Protection National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
| | - Bhawani Nagarajah
- Centre for Health Protection National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
| | - Eliana Portilla Fernández
- Division of Vascular Medicine and Pharmacology Department of Internal Medicine Erasmus MC Rotterdam The Netherlands
| | - Anton J. M. Roks
- Division of Vascular Medicine and Pharmacology Department of Internal Medicine Erasmus MC Rotterdam The Netherlands
| | - Ype Elgersma
- Department of Neuroscience Erasmus MC Rotterdam The Netherlands
| | - Harry Steeg
- Centre for Health Protection National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
| | - José A. Ferreira
- Department of Statistics, Informatics and Modelling National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
| | - Jeroen L. A. Pennings
- Centre for Health Protection National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
| | - Jan H. J. Hoeijmakers
- Princess Máxima Center for Pediatric Oncology, Genome Instability and Nutrition ONCODE Institute Utrecht The Netherlands
- Department of Molecular Genetics Erasmus MC Rotterdam The Netherlands
- CECAD Forschungszentrum Köln Germany
| | - Wilbert P. Vermeij
- Princess Máxima Center for Pediatric Oncology, Genome Instability and Nutrition ONCODE Institute Utrecht The Netherlands
| | - Martijn E. T. Dollé
- Centre for Health Protection National Institute for Public Health and the Environment (RIVM Bilthoven The Netherlands
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Song X, Zheng Y, Xue W, Li L, Shen Z, Ding X, Zhai Y, Zhao J. Identification of risk genes related to myocardial infarction and the construction of early SVM diagnostic model. Int J Cardiol 2020; 328:182-190. [PMID: 33352151 DOI: 10.1016/j.ijcard.2020.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 11/18/2022]
Abstract
BACKGROUND Myocardial Infarction (MI) is a fatal cardiovascular system disease. At present, the diagnosis of MI patients is mainly based on the patient's clinical manifestations, dynamic changes in electrocardiogram (ECG), and changes in myocardial enzymes. ECG is insufficient to diagnose an acute coronary syndrome or acute myocardial infarction, since ST-segment deviation might be also present in other conditions, such as acute pericarditis and early repolarization patterns. Given the low specificity and effectiveness of the current diagnostic strategies, an accurate diagnostic approach based on the level of gene expression is urgently needed in the clinic. METHODS AND RESULTS We compared the gene's expression between MI patients and normal samples. The RNAseq data were downloaded from the GEO database. Differentially expressed genes underwent a feature selection process, and the signatures were selected to train a machine-learning model. In this study, we identified the risk genes associated with MI as signatures and uses the SVM to establish a diagnostic model. The accuracy of the model on discovery data is 0.87, which significantly improves the diagnostic efficiency of early detection of MI patients (MIPs). Two independent datasets were applied to verify the diagnostic model. Our model can effectively distinguish the control group from the disease group. CONCLUSIONS We used risk genes to construct a diagnostic model for MI diagnosis, which can effectively distinguish MIPs from normal samples in the both of the discovery data and validation data. In the validation data, we found that percutaneous coronary intervention could indeed reverse MI to a certain extent, and the gene expression level of patients treated with percutaneous coronary intervention (PCI) was closer to the normal state.
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Affiliation(s)
- Xiaoqin Song
- Internet Medical and System Applications of National Engineering Laboratory, Zhengzhou, Henan, China; Depatment of Physical Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Yuanyuan Zheng
- Internet Medical and System Applications of National Engineering Laboratory, Zhengzhou, Henan, China; Cancer center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Wenhua Xue
- Department of Pharmacy, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Lifeng Li
- Internet Medical and System Applications of National Engineering Laboratory, Zhengzhou, Henan, China; Cancer center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Zhibo Shen
- Internet Medical and System Applications of National Engineering Laboratory, Zhengzhou, Henan, China; Cancer center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Xianfei Ding
- General ICU, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Yunkai Zhai
- Internet Medical and System Applications of National Engineering Laboratory, Zhengzhou, Henan, China.
| | - Jie Zhao
- Internet Medical and System Applications of National Engineering Laboratory, Zhengzhou, Henan, China; Department of Pharmacy, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
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Abstract
A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.
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Affiliation(s)
- Brittany Angarola
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
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10
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Zhu M, Wang XQ. Regulation of mTORC1 by Small GTPases in Response to Nutrients. J Nutr 2020; 150:1004-1011. [PMID: 31965176 DOI: 10.1093/jn/nxz301] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/07/2019] [Accepted: 11/18/2019] [Indexed: 12/15/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a highly evolutionarily conserved serine/threonine kinase that regulates cell growth and metabolism in response to multiple environmental cues, such as nutrients, hormones, energy, and stress. Deregulation of mTORC1 can lead to diseases such as diabetes, obesity, and cancer. A series of small GTPases, including Rag, Ras homolog enriched in brain (Rheb), adenosine diphosphate ribosylation factor 1 (Arf1), Ras-related protein Ral-A, Ras homolog (Rho), and Rab, are involved in regulating mTORC1 in response to nutrients, and mTORC1 is differentially regulated via these small GTPases according to specific conditions. Leucine and arginine sensing are considered to be well-confirmed amino acid-sensing signals, activating mTORC1 via a Rag GTPase-dependent mechanism as well as the Ragulator complex and vacuolar H+-adenosine triphosphatase (v-ATPase). Glutamine promotes mTORC1 activation via Arf1 independently of the Rag GTPase. In this review, we summarize current knowledge regarding the regulation of mTORC1 activity by small GTPases in response to nutrients, focusing on the function of small GTPases in mTORC1 activation and how small GTPases are regulated by nutrients.
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Affiliation(s)
- Min Zhu
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong, China
| | - Xiu-Qi Wang
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong, China
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11
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Blackwood EA, Hofmann C, Santo Domingo M, Bilal AS, Sarakki A, Stauffer W, Arrieta A, Thuerauf DJ, Kolkhorst FW, Müller OJ, Jakobi T, Dieterich C, Katus HA, Doroudgar S, Glembotski CC. ATF6 Regulates Cardiac Hypertrophy by Transcriptional Induction of the mTORC1 Activator, Rheb. Circ Res 2019; 124:79-93. [PMID: 30582446 DOI: 10.1161/circresaha.118.313854] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Endoplasmic reticulum (ER) stress dysregulates ER proteostasis, which activates the transcription factor, ATF6 (activating transcription factor 6α), an inducer of genes that enhance protein folding and restore ER proteostasis. Because of increased protein synthesis, it is possible that protein folding and ER proteostasis are challenged during cardiac myocyte growth. However, it is not known whether ATF6 is activated, and if so, what its function is during hypertrophic growth of cardiac myocytes. OBJECTIVE To examine the activity and function of ATF6 during cardiac hypertrophy. METHODS AND RESULTS We found that ER stress and ATF6 were activated and ATF6 target genes were induced in mice subjected to an acute model of transverse aortic constriction, or to free-wheel exercise, both of which promote adaptive cardiac myocyte hypertrophy with preserved cardiac function. Cardiac myocyte-specific deletion of Atf6 (ATF6 cKO [conditional knockout]) blunted transverse aortic constriction and exercise-induced cardiac myocyte hypertrophy and impaired cardiac function, demonstrating a role for ATF6 in compensatory myocyte growth. Transcript profiling and chromatin immunoprecipitation identified RHEB (Ras homologue enriched in brain) as an ATF6 target gene in the heart. RHEB is an activator of mTORC1 (mammalian/mechanistic target of rapamycin complex 1), a major inducer of protein synthesis and subsequent cell growth. Both transverse aortic constriction and exercise upregulated RHEB, activated mTORC1, and induced cardiac hypertrophy in wild type mouse hearts but not in ATF6 cKO hearts. Mechanistically, knockdown of ATF6 in neonatal rat ventricular myocytes blocked phenylephrine- and IGF1 (insulin-like growth factor 1)-mediated RHEB induction, mTORC1 activation, and myocyte growth, all of which were restored by ectopic RHEB expression. Moreover, adeno-associated virus 9- RHEB restored cardiac growth to ATF6 cKO mice subjected to transverse aortic constriction. Finally, ATF6 induced RHEB in response to growth factors, but not in response to other activators of ATF6 that do not induce growth, indicating that ATF6 target gene induction is stress specific. CONCLUSIONS Compensatory cardiac hypertrophy activates ER stress and ATF6, which induces RHEB and activates mTORC1. Thus, ATF6 is a previously unrecognized link between growth stimuli and mTORC1-mediated cardiac growth.
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Affiliation(s)
- Erik A Blackwood
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Christoph Hofmann
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.).,Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Michelle Santo Domingo
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Alina S Bilal
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Anup Sarakki
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Winston Stauffer
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Adrian Arrieta
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Donna J Thuerauf
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Fred W Kolkhorst
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Oliver J Müller
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Department of Internal Medicine III, University of Kiel, Germany, and German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany (O.J.M.)
| | - Tobias Jakobi
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III, University Hospital Heidelberg, Germany (T.J., C.D.)
| | - Christoph Dieterich
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III, University Hospital Heidelberg, Germany (T.J., C.D.)
| | - Hugo A Katus
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Shirin Doroudgar
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Christopher C Glembotski
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
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12
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Ashraf S, Kim BJ, Park S, Park H, Lee SH. RHEB gene therapy maintains the chondrogenic characteristics and protects cartilage tissue from degenerative damage during experimental murine osteoarthritis. Osteoarthritis Cartilage 2019; 27:1508-1517. [PMID: 31229684 DOI: 10.1016/j.joca.2019.05.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 05/20/2019] [Accepted: 05/24/2019] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Osteoarthritis (OA) is characterized by cartilage degeneration resulting from hypertrophic changes in chondrocytes caused by altered gene expression. The involvement of Ras homolog enriched in brain (RHEB) in OA regulation is unclear. METHODS Human knee articular cartilage samples - were analyzed for structural and biological changes by histology, immunohistochemistry, real time PCR and western blotting. OA-mouse model developed by surgical destabilization of the medial meniscus (DMM) were treated with adenovirus harboring Rheb gene to analyze onset and progression of OA. Histological scoring, immunohistochemistry, and TUNEL assay was performed to assess cartilage damage across the entire joint. RESULTS Human and mouse OA cartilage is degenerated and has markedly reduced levels of RHEB. Human OA-degenerated chondrocytes (DC) exhibited a fibroblastic phenotype and 80 % of degenerative cartilage were senescent, with higher levels of reactive oxygen species (ROS). Gene expression analysis of DC revealed almost no COL2A1 expression and reduced SOX9 and RHEB expression. Transient transfection of RHEB rescued the DC phenotype and reduced senescence and ROS levels markedly. RHEB overexpression also increased COL2A1 and SOX9 expression. In an OA-mouse model, the Rheb protein level decreased as the severity of OA increased. Ectopic expression of Rheb using adenovirus in mouse-OA cartilage suppressed surgically-induced OA pathogenesis accompanied by modulation of Adamts5, Mmp 13, Col 10, and Col2a1 expression. Rheb induction significantly reduced apoptosis in OA-cartilage. CONCLUSION RHEB plays an important role in maintaining the chondrogenic characteristics of chondrocytes, and has potential in preventing progression of OA in the destabilize the medial meniscus (DMM) mouse model of OA.
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Affiliation(s)
- S Ashraf
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - B J Kim
- Department of Medical Biotechnology, Dongguk University, Seoul, Republic of Korea
| | - S Park
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea
| | - H Park
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea.
| | - S-H Lee
- Department of Medical Biotechnology, Dongguk University, Seoul, Republic of Korea.
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13
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Child DD, Lee JH, Pascua CJ, Chen YH, Mas Monteys A, Davidson BL. Cardiac mTORC1 Dysregulation Impacts Stress Adaptation and Survival in Huntington's Disease. Cell Rep 2019; 23:1020-1033. [PMID: 29694882 PMCID: PMC5967646 DOI: 10.1016/j.celrep.2018.03.117] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/05/2018] [Accepted: 03/26/2018] [Indexed: 12/27/2022] Open
Abstract
Huntington’s disease (HD) is a dominantly inherited neurological disorder caused by CAG-repeat expansion in exon 1 of Huntingtin (HTT). But in addition to the neurological disease, mutant HTT (mHTT), which is ubiquitously expressed, impairs other organ systems. Indeed, epidemiological and animal model studies suggest higher incidence of and mortality from heart disease in HD. Here, we show that the protein complex mTORC1 is dysregulated in two HD mouse models through a mechanism that requires intrinsic mHTT expression. Moreover, restoring cardiac mTORC1 activity with constitutively active Rheb prevents mortality and relieves the mHTT-induced block to hypertrophic adaptation to cardiac stress. Finally, we show that chronic mTORC1 dysregulation is due in part to mislocalization of endogenous Rheb. These data provide insight into the increased cardiac-related mortality of HD patients, with cardiac mHTT expression inhibiting mTORC1 activity, limiting heart growth, and decreasing the heart’s ability to compensate to chronic stress.
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Affiliation(s)
- Daniel D Child
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; The Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA, USA
| | - John H Lee
- Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, CA, USA
| | - Christine J Pascua
- Division of Cardiology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Yong Hong Chen
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Alejandro Mas Monteys
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Beverly L Davidson
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; The Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA, USA.
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14
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Angarola B, Ferguson SM. Weak membrane interactions allow Rheb to activate mTORC1 signaling without major lysosome enrichment. Mol Biol Cell 2019; 30:2750-2760. [PMID: 31532697 PMCID: PMC6789162 DOI: 10.1091/mbc.e19-03-0146] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Stable localization of the Rheb GTPase to lysosomes is thought to be required for activation of mTOR complex 1 (mTORC1) signaling. However, the lysosome targeting mechanisms for Rheb remain unclear. We therefore investigated the relationship between Rheb subcellular localization and mTORC1 activation. Surprisingly, we found that Rheb was undetectable at lysosomes. Nonetheless, functional assays in knockout human cells revealed that farnesylation of the C-terminal CaaX motif on Rheb was essential for Rheb-dependent mTORC1 activation. Although farnesylated Rheb exhibited partial endoplasmic reticulum (ER) localization, constitutively targeting Rheb to ER membranes did not support mTORC1 activation. Further systematic analysis of Rheb lipidation revealed that weak, nonselective, membrane interactions support Rheb-dependent mTORC1 activation without the need for a specific lysosome targeting motif. Collectively, these results argue against stable interactions of Rheb with lysosomes and instead that transient membrane interactions optimally allow Rheb to activate mTORC1 signaling.
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Affiliation(s)
- Brittany Angarola
- Departments of Cell Biology and Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Shawn M Ferguson
- Departments of Cell Biology and Neuroscience, Yale University School of Medicine, New Haven, CT 06510
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15
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Emerging Role of mTOR Signaling-Related miRNAs in Cardiovascular Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:6141902. [PMID: 30305865 PMCID: PMC6165581 DOI: 10.1155/2018/6141902] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 07/04/2018] [Indexed: 12/21/2022]
Abstract
Mechanistic/mammalian target of rapamycin (mTOR), an atypical serine/threonine kinase of the phosphoinositide 3-kinase- (PI3K-) related kinase family, elicits a vital role in diverse cellular processes, including cellular growth, proliferation, survival, protein synthesis, autophagy, and metabolism. In the cardiovascular system, the mTOR signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of both physiological and pathological processes. MicroRNAs (miRs), a class of short noncoding RNA, are an emerging intricate posttranscriptional modulator of critical gene expression for the development and maintenance of homeostasis across a wide array of tissues, including the cardiovascular system. Over the last decade, numerous studies have revealed an interplay between miRNAs and the mTOR signaling circuit in the different cardiovascular pathophysiology, like myocardial infarction, hypertrophy, fibrosis, heart failure, arrhythmia, inflammation, and atherosclerosis. In this review, we provide a comprehensive state of the current knowledge regarding the mechanisms of interactions between the mTOR signaling pathway and miRs. We have also highlighted the latest advances on mTOR-targeted therapy in clinical trials and the new perspective therapeutic strategies with mTOR-targeting miRs in cardiovascular diseases.
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16
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Lavagi I, Krebs S, Simmet K, Beck A, Zakhartchenko V, Wolf E, Blum H. Single-cell RNA sequencing reveals developmental heterogeneity of blastomeres during major genome activation in bovine embryos. Sci Rep 2018; 8:4071. [PMID: 29511234 PMCID: PMC5840315 DOI: 10.1038/s41598-018-22248-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/16/2018] [Indexed: 12/22/2022] Open
Abstract
Embryonic development is initially controlled by maternal RNAs and proteins stored in the oocyte, until gene products gradually generated by the embryo itself take over. Major embryonic genome activation (EGA) in bovine embryos occurs at the eight- to 16-cell stage. Morphological observations, such as size of blastomeres and distribution of microvilli, suggested heterogeneity among individual cells already at this developmental stage. To address cell heterogeneity on the transcriptome level, we performed single-cell RNA sequencing of 161 blastomeres from 14 in vitro produced bovine embryos at Day 2 (n = 6) and Day 3 (n = 8) post fertilization. Complementary DNA libraries were prepared using the Single-Cell RNA-Barcoding and Sequencing protocol and sequenced. Non-supervised clustering of single-cell transcriptome profiles identified six clusters with specific sets of genes. Most embryos were comprised of cells from at least two different clusters. Sorting cells according to their transcriptome profiles resulted in a non-branched pseudo-time line, arguing against major lineage inclination events at this developmental stage. In summary, our study revealed heterogeneity of transcriptome profiles among single cells in bovine Day 2 and Day 3 embryos, suggesting asynchronous blastomere development during the phase of major EGA.
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Affiliation(s)
- Ilaria Lavagi
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, LMU Munich, Munich, Germany.,Graduate School of Quantitative Biosciences Munich (QBM), Gene Center, LMU Munich, Munich, Germany
| | - Stefan Krebs
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, LMU Munich, Munich, Germany
| | - Kilian Simmet
- Chair of Molecular Animal Breeding and Biotechnology, Gene Center and Department of Veterinary Sciences, LMU Munich, Munich, Germany
| | - Andrea Beck
- Chair of Molecular Animal Breeding and Biotechnology, Gene Center and Department of Veterinary Sciences, LMU Munich, Munich, Germany
| | - Valeri Zakhartchenko
- Chair of Molecular Animal Breeding and Biotechnology, Gene Center and Department of Veterinary Sciences, LMU Munich, Munich, Germany
| | - Eckhard Wolf
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, LMU Munich, Munich, Germany. .,Chair of Molecular Animal Breeding and Biotechnology, Gene Center and Department of Veterinary Sciences, LMU Munich, Munich, Germany.
| | - Helmut Blum
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, LMU Munich, Munich, Germany.
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17
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Mahoney SJ, Narayan S, Molz L, Berstler LA, Kang SA, Vlasuk GP, Saiah E. A small molecule inhibitor of Rheb selectively targets mTORC1 signaling. Nat Commun 2018; 9:548. [PMID: 29416044 PMCID: PMC5803267 DOI: 10.1038/s41467-018-03035-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 01/12/2018] [Indexed: 12/19/2022] Open
Abstract
The small G-protein Rheb activates the mechanistic target of rapamycin complex 1 (mTORC1) in response to growth factor signals. mTORC1 is a master regulator of cellular growth and metabolism; aberrant mTORC1 signaling is associated with fibrotic, metabolic, and neurodegenerative diseases, cancers, and rare disorders. Point mutations in the Rheb switch II domain impair its ability to activate mTORC1. Here, we report the discovery of a small molecule (NR1) that binds Rheb in the switch II domain and selectively blocks mTORC1 signaling. NR1 potently inhibits mTORC1 driven phosphorylation of ribosomal protein S6 kinase beta-1 (S6K1) but does not inhibit phosphorylation of AKT or ERK. In contrast to rapamycin, NR1 does not cause inhibition of mTORC2 upon prolonged treatment. Furthermore, NR1 potently and selectively inhibits mTORC1 in mouse kidney and muscle in vivo. The data presented herein suggest that pharmacological inhibition of Rheb is an effective approach for selective inhibition of mTORC1 with therapeutic potential.
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Affiliation(s)
- Sarah J Mahoney
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA.
| | - Sridhar Narayan
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA
| | - Lisa Molz
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA
| | - Lauren A Berstler
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA
| | - Seong A Kang
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA
| | - George P Vlasuk
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA
| | - Eddine Saiah
- Navitor Pharmaceuticals, Inc., 1030 Massachusetts Ave. #410, Cambridge, MA, 02138, USA
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18
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Kandror K. Mammalian target of rapamycin complex 1 and FoxO1 in the transcriptional control of lipolysis and de novo lipogenesis. Curr Opin Endocrinol Diabetes Obes 2017; 24:326-331. [PMID: 28841634 PMCID: PMC11210950 DOI: 10.1097/med.0000000000000352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE OF REVIEW Postprandial suppression of lipolysis in adipose tissue and stimulation of de novo lipogenesis (DNL) in the liver by insulin are essential for the metabolic homeostasis in the mammalian organism. The mechanism of coregulation of lipolysis and DNL is not clear. RECENT FINDINGS Insulin controls both lipolysis and DNL at the level of transcription via the same mammalian target of rapamycin complex 1 (mTORC1) and FoxO1-mediated signaling pathways. SUMMARY mTORC1 suppresses lipolysis in adipose tissue and activates DNL in the liver, whereas FoxO1 has the opposite effect. Individual inputs of either mTORC1 or FoxO1 in the regulation of lipid metabolism may be difficult to evaluate because of the cross talk between these pathways.
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Affiliation(s)
- K.V. Kandror
- Boston University School of Medicine, Department of Biochemistry, K123D, 715 Albany Street, Boston, MA 02118, USA. Phone: 617-638-5049
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19
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Wang Y, Guo Z, Liu M, Zhao K, Feng X, Zheng X, Wang X, Hao H, Guo X, Wang Z. Proteasome subunit beta type 1 interacts directly with Rheb and regulates the cell cycle in Cashmere goat fetal fibroblasts. Anim Cells Syst (Seoul) 2017. [DOI: 10.1080/19768354.2017.1371072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Yanfeng Wang
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Zhixin Guo
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Mingtao Liu
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Keyu Zhao
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Xue Feng
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Xu Zheng
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
- Department of Clinical Laboratory, Hulunbeir Municipal People’s Hospital, Hailar, People’s Republic of China
| | - Xiaojing Wang
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
- Department of Clinical Laboratory, Chifeng Municipal Hospital, Chifeng, People’s Republic of China
| | - Huifang Hao
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Xudong Guo
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Zhigang Wang
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
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20
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RHEB1 insufficiency in aged male mice is associated with stress-induced seizures. GeroScience 2017; 39:557-570. [PMID: 28891034 DOI: 10.1007/s11357-017-9997-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
The mechanistic target of rapamycin (mTOR), a protein kinase, is a central regulator of mammalian metabolism and physiology. Protein mTOR complex 1 (mTORC1) functions as a major sensor for the nutrient, energy, and redox state of a cell and is activated by ras homolog enriched in brain (RHEB1), a GTP-binding protein. Increased activation of mTORC1 pathway has been associated with developmental abnormalities, certain form of epilepsy (tuberous sclerosis), and cancer. Clinically, those mTOR-related disorders are treated with the mTOR inhibitor rapamycin and its rapalogs. Because the effects of chronic interference with mTOR signaling in the aged brain are yet unknown, we used a genetic strategy to interfere with mTORC1 signaling selectively by introducing mutations of Rheb1 into the mouse. We created conventional knockout (Rheb1 +/- ) and gene trap (Rheb1 Δ/+ ) mutant mouse lines. Rheb1-insufficient mice with different combinations of mutant alleles were monitored over a time span of 2 years. The mice did not show any behavioral/neurological changes during the first 18 months of age. However, after aging (> 18 months of age), both the Rheb1 +/- and Rheb1 Δ /- hybrid males developed rare stress-induced seizures, whereas Rheb1 +/- and Rheb1 Δ /- females and Rheb1 Δ/+ and Rheb1 Δ/Δ mice of both genders did not show any abnormality. Our findings suggest that chronic intervention with mTORC1 signaling in the aged brain might be associated with major adverse events.
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21
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Yu JSL, Cui W. Proliferation, survival and metabolism: the role of PI3K/AKT/mTOR signalling in pluripotency and cell fate determination. Development 2017; 143:3050-60. [PMID: 27578176 DOI: 10.1242/dev.137075] [Citation(s) in RCA: 682] [Impact Index Per Article: 97.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Phosphatidylinositide 3 kinases (PI3Ks) and their downstream mediators AKT and mammalian target of rapamycin (mTOR) constitute the core components of the PI3K/AKT/mTOR signalling cascade, regulating cell proliferation, survival and metabolism. Although these functions are well-defined in the context of tumorigenesis, recent studies - in particular those using pluripotent stem cells - have highlighted the importance of this pathway to development and cellular differentiation. Here, we review the recent in vitro and in vivo evidence for the role PI3K/AKT/mTOR signalling plays in the control of pluripotency and differentiation, with a particular focus on the molecular mechanisms underlying these functions.
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Affiliation(s)
- Jason S L Yu
- Institute of Reproductive and Developmental Biology, Department of Surgery and Cancer, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Wei Cui
- Institute of Reproductive and Developmental Biology, Department of Surgery and Cancer, Imperial College London, Du Cane Road, London W12 0NN, UK
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22
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Potheraveedu VN, Schöpel M, Stoll R, Heumann R. Rheb in neuronal degeneration, regeneration, and connectivity. Biol Chem 2017; 398:589-606. [PMID: 28212107 DOI: 10.1515/hsz-2016-0312] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 02/02/2017] [Indexed: 01/31/2023]
Abstract
The small GTPase Rheb was originally detected as an immediate early response protein whose expression was induced by NMDA-dependent synaptic activity in the brain. Rheb's activity is highly regulated by its GTPase activating protein (GAP), the tuberous sclerosis complex protein, which stimulates the conversion from the active, GTP-loaded into the inactive, GDP-loaded conformation. Rheb has been established as an evolutionarily conserved molecular switch protein regulating cellular growth, cell volume, cell cycle, autophagy, and amino acid uptake. The subcellular localization of Rheb and its interacting proteins critically regulate its activity and function. In stem cells, constitutive activation of Rheb enhances differentiation at the expense of self-renewal partially explaining the adverse effects of deregulated Rheb in the mammalian brain. In the context of various cellular stress conditions such as oxidative stress, ER-stress, death factor signaling, and cellular aging, Rheb activation surprisingly enhances rather than prevents cellular degeneration. This review addresses cell type- and cell state-specific function(s) of Rheb and mainly focuses on neurons and their surrounding glial cells. Mechanisms will be discussed in the context of therapy that interferes with Rheb's activity using the antibiotic rapamycin or low molecular weight compounds.
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Affiliation(s)
- Veena Nambiar Potheraveedu
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
| | - Miriam Schöpel
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Rolf Heumann
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
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Rapamycin efficiently promotes cardiac differentiation of mouse embryonic stem cells. Biosci Rep 2017; 37:BSR20160552. [PMID: 28396518 PMCID: PMC5463265 DOI: 10.1042/bsr20160552] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/08/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022] Open
Abstract
To investigate the effects of rapamycin on cardiac differentiation, murine embryonic stem cells (ESCs) were induced into cardiomyocytes by 10−4 M ascorbic acid (AA), 20 nM rapamycin alone or 0.01% solvent DMSO. We found that rapamycin alone was insufficient to initiate cardiomyogenesis. Then, the ESCs were treated with AA and rapamycin (20 nM) or AA and DMSO (0.01%) as a control. Compared with control, mouse ESCs (mESCs) treated with rapamycin (20 nM) and AA yielded a significantly higher percentage of cardiomyocytes, as confirmed by the percentage of beating embryonic bodies (EBs), the immunofluorescence and FACS analysis. Rapamycin significantly increased the expression of a panel of cardiac markers including Gata4, α-Mhc, β-Mhc, and Tnnt2. Additionally, rapamycin enhanced the expression of mesodermal and cardiac transcription factors such as Mesp1, Brachyury T, Eomes, Isl1, Gata4, Nkx2.5, Tbx5, and Mef2c. Mechanistic studies showed that rapamycin inhibits Wnt/β-catenin and Notch signaling but promotes the expression of fibroblast growth factor (Fgf8), Fgf10, and Nodal at early stage, and bone morphogenetic protein 2 (Bmp 2) at later stages. Sequential treatment of rapamycin showed that rapamycin promotes cardiac differentiation at the early and later stages. Interestingly, another mammalian target of rapamycin (mTOR) inhibitor Ku0063794 (1 µM) had similar effects on cardiomyogenesis. In conclusion, our results highlight a practical approach to generate cardiomyocytes from mESCs by rapamycin.
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Rheb1 deletion in myeloid cells aggravates OVA-induced allergic inflammation in mice. Sci Rep 2017; 7:42655. [PMID: 28225024 PMCID: PMC5320517 DOI: 10.1038/srep42655] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 01/12/2017] [Indexed: 12/28/2022] Open
Abstract
The small GTPase ras homolog enriched in brain (Rheb) is a downstream target of tuberous sclerosis complex 1/2 (TSC1/2) and an upstream activator of the mechanistic target of rapamycin complex 1 (mTORC1), the emerging essential modulator of M1/M2 balance in macrophages. However, the role and regulatory mechanisms of Rheb in macrophage polarization and allergic asthma are not known. In the present study, we utilized a mouse model with myeloid cell-specific deletion of the Rheb1 gene and an ovalbumin (OVA)-induced allergic asthma model to investigate the role of Rheb1 in allergic asthma and macrophage polarization. Increased activity of Rheb1 and mTORC1 was observed in myeloid cells of C57BL/6 mice with OVA-induced asthma. In an OVA-induced asthma model, Rheb1-KO mice demonstrated a more serious inflammatory response, more mucus production, enhanced airway hyper-responsiveness, and greater eosinophil numbers in bronchoalveolar lavage fluid (BALF). They also showed increased numbers of bone marrow macrophages and BALF myeloid cells, elevated M2 polarization and reduced M1 polarization of macrophages. Thus, we have established that Rheb1 is critical for the polarization of macrophages and inhibition of allergic asthma. Deletion of Rheb1 enhances M2 polarization but decreases M1 polarization in alveolar macrophages, leading to the aggravation of OVA-induced allergic asthma.
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Shahani N, Huang WC, Varnum M, Page DT, Subramaniam S. Forebrain depletion of Rheb GTPase elicits spatial memory deficits in mice. Neurobiol Aging 2016; 50:134-143. [PMID: 27960107 DOI: 10.1016/j.neurobiolaging.2016.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/20/2016] [Accepted: 11/12/2016] [Indexed: 12/19/2022]
Abstract
The precise molecular and cellular events responsible for age-dependent cognitive dysfunctions remain unclear. We report that Rheb (ras homolog enriched in brain) GTPase, an activator of mammalian target of rapamycin (mTOR), regulates memory functions in mice. Conditional depletion of Rheb selectively in the forebrain of mice obtained from crossing Rhebf/f and CamKIICre results in spontaneous signs of age-related memory loss, that is, spatial memory deficits (T-maze, Morris water maze) without affecting locomotor (open-field test), anxiety-like (elevated plus maze), or contextual fear conditioning functions. Partial depletion of Rheb in forebrain was sufficient to elicit memory defects with little effect on the neuronal size, cortical thickness, or mammalian target of rapamycin activity. Rheb depletion, however, increased the levels of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), a protein elevated in aging and Alzheimer's disease. Overall, our study demonstrates that forebrain Rheb promotes aging-associated cognitive defects. Thus, molecular understanding of Rheb pathway in brain may provide new therapeutic targets for aging and/or Alzheimer's disease-associated memory deficits.
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Affiliation(s)
- Neelam Shahani
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Wen-Chin Huang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Megan Varnum
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Damon T Page
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
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Inhibition of MAPK pathway is essential for suppressing Rheb-Y35N driven tumor growth. Oncogene 2016; 36:756-765. [PMID: 27399332 DOI: 10.1038/onc.2016.246] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/08/2016] [Accepted: 06/01/2016] [Indexed: 11/08/2022]
Abstract
Rheb is a Ras family GTPase, which binds to and activates mammalian target of rapamycin complex 1 (mTORC1) when GTP loaded. Recently, cancer genome sequencing efforts have identified recurrent Rheb Tyr35Asn mutations in kidney and endometrial carcinoma. Here we show that Rheb-Y35N causes not only constitutive mTORC1 activation, but sustained activation of the MEK-ERK pathway in a TSC1/TSC2/TBC1D7 protein complex and mTORC1-independent manner, contributing to intrinsic resistance to rapamycin. Rheb-Y35N transforms NIH3T3 cells, resulting in aggressive tumor formation in xenograft nude mice, which could be suppressed by combined treatment with rapamycin and an extracellular signal-regulated kinase (ERK) inhibitor. Furthermore, Rheb-Y35N inhibits AMPKα activation in response to nutrient depletion or 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), leading to attenuated phosphorylation of BRAF-S729 and retained mitogen-activated protein kinase (MAPK) activation. Finally, we demonstrate that Rheb-WT can bind AMPK to facilitate AMPK activation, whereas Rheb-Y35N competitively binds AMPK, impairing AMPK phosphorylation. In summary, our findings indicate that Rheb-Y35N is a dominantly active tumor driver that activates both mTORC1 and MAPK to promote tumor growth, suggesting a combination of mTORC1 and MAPK inhibitors may be of therapeutic value in patients whose cancers sustain this mutation.
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Gao Y, Gao J, Li M, Zheng Y, Wang Y, Zhang H, Wang W, Chu Y, Wang X, Xu M, Cheng T, Ju Z, Yuan W. Rheb1 promotes tumor progression through mTORC1 in MLL-AF9-initiated murine acute myeloid leukemia. J Hematol Oncol 2016; 9:36. [PMID: 27071307 PMCID: PMC4830070 DOI: 10.1186/s13045-016-0264-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 04/03/2016] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND The constitutive hyper-activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathways has frequently been associated with acute myeloid leukemia (AML). While many inhibitors targeting these pathways have been developed, the anti-leukemic effect was not as robust as expected. As part of the molecular link between PI3K/Akt and mTOR kinase, the role of Rheb1 in AML remains unexplored. Our study aims to explore the role of Rheb1 in AML and estimate whether Rheb1 could be a potential target of AML treatment. METHODS The expressions of Rheb1 and other indicated genes were analyzed using real-time PCR. AML mouse model was established by retrovirus transduction. Leukemia cell properties and related signaling pathways were dissected by in vitro and in vivo studies. The transcriptional changes were analyzed via gene chip analysis. Molecular reagents including mTOR inhibitor and mTOR activator were used to evaluate the function of related signaling pathway in the mouse model. RESULTS We observed that Rheb1 is overexpressed in AML patients and the change of Rheb1 level in AML patients is associated with their median survival. Using a Rheb1-deficient MLL-AF9 murine AML model, we revealed that Rheb1 deletion prolonged the survival of AML mice by weakening LSC function. In addition, Rheb1 deletion arrested cell cycle progression and enhanced apoptosis of AML cells. Furthermore, while Rheb1 deletion reduced mTORC1 activity in AML cells, additional rapamycin treatment further decreased mTORC1 activity and increased the apoptosis of Rheb1 (Δ/Δ) AML cells. The mTOR activator 3BDO partially rescued mTORC1 signaling and inhibited apoptosis in Rheb1 (Δ/Δ) AML cells. CONCLUSIONS Our data suggest that Rheb1 promotes AML progression through mTORC1 signaling pathway and combinational drug treatments targeting Rheb1 and mTOR might have a better therapeutic effect on leukemia.
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Affiliation(s)
- Yanan Gao
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Juan Gao
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Minghao Li
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Yawei Zheng
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Yajie Wang
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Hongyan Zhang
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Weili Wang
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Yajing Chu
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Xiaomin Wang
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China.
| | - Mingjiang Xu
- Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, USA
| | - Tao Cheng
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China
| | - Zhenyu Ju
- Institute of Aging, Hangzhou Normal University, Hangzhou, 310036, China
| | - Weiping Yuan
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Center for Stem Cell Medicine, CAMS & PUMC, Beijing, China.
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Tian Q, Smart JL, Clement JH, Wang Y, Derkatch A, Schubert H, Danilchik MV, Marks DL, Fedorov LM. RHEB1 expression in embryonic and postnatal mouse. Histochem Cell Biol 2015; 145:561-72. [PMID: 26708151 DOI: 10.1007/s00418-015-1394-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2015] [Indexed: 12/16/2022]
Abstract
Ras homolog enriched in brain (RHEB1) is a member within the superfamily of GTP-binding proteins encoded by the RAS oncogenes. RHEB1 is located at the crossroad of several important pathways including the insulin-signaling pathways and thus plays an important role in different physiological processes. To understand better the physiological relevance of RHEB1 protein, the expression pattern of RHEB1 was analyzed in both embryonic (at E3.5-E16.5) and adult (1-month old) mice. RHEB1 immunostaining and X-gal staining were used for wild-type and Rheb1 gene trap mutant mice, respectively. These independent methods revealed similar RHEB1 expression patterns during both embryonic and postnatal developments. Ubiquitous uniform RHEB1/β-gal and/or RHEB1 expression was seen in preimplantation embryos at E3.5 and postimplantation embryos up to E12.5. Between stages E13.5 and E16.5, RHEB1 expression levels became complex: In particular, strong expression was identified in neural tissues, including the neuroepithelial layer of the mesencephalon, telencephalon, and neural tube of CNS and dorsal root ganglia. In addition, strong expression was seen in certain peripheral tissues including heart, intestine, muscle, and urinary bladder. Postnatal mice have broad spatial RHEB1 expression in different regions of the cerebral cortex, subcortical regions (including hippocampus), olfactory bulb, medulla oblongata, and cerebellum (particularly in Purkinje cells). Significant RHEB1 expression was also viewed in internal organs including the heart, intestine, urinary bladder, and muscle. Moreover, adult animals have complex tissue- and organ-specific RHEB1 expression patterns with different intensities observed throughout postnatal development. Its expression level is in general comparable in CNS and other organs of mouse. Thus, the expression pattern of RHEB1 suggests that it likely plays a ubiquitous role in the development of the early embryo with more tissue-specific roles in later development.
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Affiliation(s)
- Qi Tian
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | | | - Joachim H Clement
- Department of Hematology and Oncology, Jena University Hospital, 07747, Jena, Germany
| | - Yingming Wang
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | - Alex Derkatch
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | | | - Michael V Danilchik
- Department of Integrative Biosciences, Oregon Health and Science University, Portland, OR, USA
| | - Daniel L Marks
- Department of Pediatrics, Oregon Health and Science University, Portland, OR, USA
| | - Lev M Fedorov
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
- Friedrich-Schiller-University, 07740, Jena, Germany.
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Abstract
A multifunctional microRNA, miR-155, has been recently recognized as an important modulator of numerous biological processes. In our previous in vitro studies, miR-155 was identified as a potential regulator of the endothelial morphogenesis. The present study demonstrates that in vivo inhibition of miR-155 supports cerebral vasculature after experimental stroke. Intravenous injections of a specific miR-155 inhibitor were initiated at 48 h after mouse distal middle cerebral artery occlusion (dMCAO). Microvasculature in peri-infarct area, infarct size, and animal functional recovery were assessed at 1, 2, and 3 weeks after dMCAO. Using in vivo two-photon microscopy, we detected improved blood flow and microvascular integrity in the peri-infarct area of miR-155 inhibitor-injected mice. Electron microscopy revealed that, in contrast to the control group, these animals demonstrated well preserved capillary tight junctions (TJs). Western blot analysis data indicate that improved TJ integrity in the inhibitor-injected animals could be associated with stabilization of the TJ protein ZO-1 and mediated by the miR-155 target protein Rheb. MRI analysis showed significant (34%) reduction of infarct size in miR-155 inhibitor-injected animals at 21 d after dMCAO. Reduced brain injury was confirmed by electron microscopy demonstrating decreased neuronal damage in the peri-infarct area of stroke. Preservation of brain tissue was reflected in efficient functional recovery of inhibitor-injected animals. Based on our findings, we propose that in vivo miR-155 inhibition after ischemia supports brain microvasculature, reduces brain tissue damage, and improves the animal functional recovery. Significance statement: In the present study, we investigated an effect of the in vivo inhibition of a microRNA, miR-155, on brain recovery after experimental cerebral ischemia. To our knowledge, this is the first report describing the efficiency of intravenous anti-miRNA injections in a mouse model of ischemic stroke. The role of miRNAs in poststroke revascularization has been unexplored and in vivo regulation of miRNAs during the subacute phase of stroke has not yet been proposed. Our investigation introduces a new and unexplored approach to cerebral regeneration: regulation of poststroke angiogenesis and recovery through direct modulation of specific miRNA activity. We expect that our findings will lead to the development of novel strategies for regulating neurorestorative processes in the postischemic brain.
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Abstract
PURPOSE OF REVIEW Metabolic diseases, such as type 2 diabetes, cardiac dysfunction, hypertension, and hepatic steatosis, share one critical causative factor: abnormal lipid partitioning, that redistribution of triglycerides from adipocytes to nonadipose peripheral tissues. Lipid overload of these tissues causes a number of pathological effects collectively known as lipotoxicity. If we find the way to correct lipid partitioning, we will restrain metabolic diseases, improve life quality and life expectancy and radically reduce healthcare costs. RECENT FINDINGS Lipid partitioning in the body is maintained by tightly regulated and balanced rates of de novo lipogenesis, lipolysis, adipogenesis, and mitochondrial oxidation primarily in fat and liver. Recent studies highlighted in this review have established mTOR as a central regulator of lipid storage and metabolism. SUMMARY Increased activity of mTOR in obesity may compensate for the negative consequences of overnutrition, whereas dysregulation of mTOR may lead to abnormal lipid partitioning and metabolic disease.
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Affiliation(s)
- Partha Chakrabarti
- aDivision of Cell Biology and Physiology, CSIR-Indian Institute of Chemical Biology, Kolkata, India bDepartment of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
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PAK2 is an effector of TSC1/2 signaling independent of mTOR and a potential therapeutic target for Tuberous Sclerosis Complex. Sci Rep 2015; 5:14534. [PMID: 26412398 PMCID: PMC4585940 DOI: 10.1038/srep14534] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/22/2015] [Indexed: 11/22/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is caused by inactivating mutations in either TSC1 or TSC2 and is characterized by uncontrolled mTORC1 activation. Drugs that reduce mTOR activity are only partially successful in the treatment of TSC, suggesting that mTOR-independent pathways play a role in disease development. Here, kinome profiles of wild-type and Tsc2−/− mouse embryonic fibroblasts (MEFs) were generated, revealing a prominent role for PAK2 in signal transduction downstream of TSC1/2. Further investigation showed that the effect of the TSC1/2 complex on PAK2 is mediated through RHEB, but is independent of mTOR and p21RAC. We also demonstrated that PAK2 over-activation is likely responsible for the migratory and cell cycle abnormalities observed in Tsc2−/− MEFs. Finally, we detected high levels of PAK2 activation in giant cells in the brains of TSC patients. These results show that PAK2 is a direct effector of TSC1-TSC2-RHEB signaling and a new target for rational drug therapy in TSC.
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Altman MK, Alshamrani AA, Jia W, Nguyen HT, Fambrough JM, Tran SK, Patel MB, Hoseinzadeh P, Beedle AM, Murph MM. Suppression of the GTPase-activating protein RGS10 increases Rheb-GTP and mTOR signaling in ovarian cancer cells. Cancer Lett 2015; 369:175-83. [PMID: 26319900 DOI: 10.1016/j.canlet.2015.08.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 08/14/2015] [Accepted: 08/17/2015] [Indexed: 12/15/2022]
Abstract
The regulator of G protein signaling 10 (RGS10) protein is a GTPase activating protein that accelerates the hydrolysis of GTP and therefore canonically inactivates G proteins, ultimately terminating signaling. Rheb is a small GTPase protein that shuttles between its GDP- and GTP-bound forms to activate mTOR. Since RGS10 suppression augments ovarian cancer cell viability, we sought to elucidate the molecular mechanism. Following RGS10 suppression in serum-free conditions, phosphorylation of mTOR, the eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1), p70S6K and S6 Ribosomal Protein appear. Furthermore, suppressing RGS10 increases activated Rheb, suggesting RGS10 antagonizes mTOR signaling via the small G-protein. The effects of RGS10 suppression are enhanced after stimulating cells with the growth factor, lysophosphatidic acid, and reduced with mTOR inhibitors, temsirolimus and INK-128. Suppression of RGS10 leads to an increase in cell proliferation, even in the presence of etoposide. In summary, the RGS10 suppression increases Rheb-GTP and mTOR signaling in ovarian cancer cells. Our results suggest that RGS10 could serve in a novel, and previously unknown, role by accelerating the hydrolysis of GTP from Rheb in ovarian cancer cells.
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Affiliation(s)
- Molly K Altman
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Ali A Alshamrani
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Wei Jia
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Ha T Nguyen
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Jada M Fambrough
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Sterling K Tran
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Mihir B Patel
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Pooya Hoseinzadeh
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Aaron M Beedle
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA
| | - Mandi M Murph
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, 240 W. Green Street, Athens, GA 30602, USA.
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Dibble CC, Cantley LC. Regulation of mTORC1 by PI3K signaling. Trends Cell Biol 2015; 25:545-55. [PMID: 26159692 DOI: 10.1016/j.tcb.2015.06.002] [Citation(s) in RCA: 559] [Impact Index Per Article: 62.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 06/08/2015] [Accepted: 06/08/2015] [Indexed: 11/29/2022]
Abstract
The class I phosphoinositide 3-kinase (PI3K)-mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signaling network directs cellular metabolism and growth. Activation of mTORC1 [composed of mTOR, regulatory-associated protein of mTOR (Raptor), mammalian lethal with SEC13 protein 8(mLST8), 40-kDa proline-rich Akt substrate (PRAS40), and DEP domain-containing mTOR-interacting protein (DEPTOR)] depends on the Ras-related GTPases (Rags) and Ras homolog enriched in brain (Rheb) GTPase and requires signals from amino acids, glucose, oxygen, energy (ATP), and growth factors (including cytokines and hormones such as insulin). Here we discuss the signal transduction mechanisms through which growth factor-responsive PI3K signaling activates mTORC1. We focus on how PI3K-dependent activation of Akt and spatial regulation of the tuberous sclerosis complex (TSC) complex (TSC complex) [composed of TSC1, TSC2, and Tre2-Bub2-Cdc16-1 domain family member 7 (TBC1D7)] switches on Rheb at the lysosome, where mTORC1 is activated. Integration of PI3K- and amino acid-dependent signals upstream of mTORC1 at the lysosome is detailed in a working model. A coherent understanding of the PI3K-mTORC1 network is imperative as its dysregulation has been implicated in diverse pathologies including cancer, diabetes, autism, and aging.
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Affiliation(s)
- Christian C Dibble
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lewis C Cantley
- Meyer Cancer Center, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA.
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Guan Y, Zhang L, Li X, Zhang X, Liu S, Gao N, Li L, Gao G, Wei G, Chen Z, Zheng Y, Ma X, Siwko S, Chen JL, Liu M, Li D. Repression of Mammalian Target of Rapamycin Complex 1 Inhibits Intestinal Regeneration in Acute Inflammatory Bowel Disease Models. THE JOURNAL OF IMMUNOLOGY 2015; 195:339-46. [PMID: 26026060 DOI: 10.4049/jimmunol.1303356] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 05/04/2015] [Indexed: 12/21/2022]
Abstract
The mammalian target of rapamycin (mTOR) signaling pathway integrates environmental cues to regulate cell growth and survival through various mechanisms. However, how mTORC1 responds to acute inflammatory signals to regulate bowel regeneration is still obscure. In this study, we investigated the role of mTORC1 in acute inflammatory bowel disease. Inhibition of mTORC1 activity by rapamycin treatment or haploinsufficiency of Rheb through genetic modification in mice impaired intestinal cell proliferation and induced cell apoptosis, leading to high mortality in dextran sodium sulfate- and 2,4,6-trinitrobenzene sulfonic acid-induced colitis models. Through bone marrow transplantation, we found that mTORC1 in nonhematopoietic cells played a major role in protecting mice from colitis. Reactivation of mTORC1 activity by amino acids had a positive therapeutic effect in mTORC1-deficient Rheb(+/-) mice. Mechanistically, mTORC1 mediated IL-6-induced Stat3 activation in intestinal epithelial cells to stimulate the expression of downstream targets essential for cell proliferation and tissue regeneration. Therefore, mTORC1 signaling critically protects against inflammatory bowel disease through modulation of inflammation-induced Stat3 activity. As mTORC1 is an important therapeutic target for multiple diseases, our findings will have important implications for the clinical usage of mTORC1 inhibitors in patients with acute inflammatory bowel disease.
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Affiliation(s)
- Yuting Guan
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Long Zhang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Xia Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Xinyan Zhang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Shijie Liu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Na Gao
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Liang Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Ganglong Gao
- Fengxian Hospital, Southern Medical University, Shanghai 201499, China; and
| | - Gaigai Wei
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Zhaohua Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Yansen Zheng
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Xueyun Ma
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Stefan Siwko
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030
| | - Jin-Lian Chen
- Fengxian Hospital, Southern Medical University, Shanghai 201499, China; and
| | - Mingyao Liu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China; Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030
| | - Dali Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China;
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35
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Abstract
Fibrosis is defined as an excessive accumulation of extracellular matrix components that lead to the destruction of organ architecture and impairment of organ function. Moreover, fibrosis is an intricate process attributable to a variety of interlaced fibrogenic signals and intrinsic mechanisms of activation of myofibroblasts. Being the dominant matrix-producing cells in organ fibrosis, myofibroblasts may be differentiated from various types of precursor cells. Identification of the signal pathways that play a key role in the pathogenesis of fibrotic diseases may suggest potential therapeutic targets. Here, we emphasize several intracellular signaling pathways that control the activation of myofibroblasts and matrix production.
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Affiliation(s)
- Weichun He
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, 210003 China
| | - Chunsun Dai
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, 210003 China
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36
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Fawal MA, Brandt M, Djouder N. MCRS1 binds and couples Rheb to amino acid-dependent mTORC1 activation. Dev Cell 2015; 33:67-81. [PMID: 25816988 DOI: 10.1016/j.devcel.2015.02.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 12/11/2014] [Accepted: 02/10/2015] [Indexed: 12/31/2022]
Abstract
Ras homolog enriched in brain (Rheb) is critical for mechanistic target of rapamycin complex 1 (mTORC1) activation in response to growth factors and amino acids (AAs). Whereas growth factors inhibit the tuberous sclerosis complex (TSC1-TSC2), a negative Rheb regulator, the role of AAs in Rheb activation remains unknown. Here, we identify microspherule protein 1 (MCRS1) as the essential link between Rheb and mTORC1 activation. MCRS1, in an AA-dependent manner, maintains Rheb at lysosome surfaces, connecting Rheb to mTORC1. MCRS1 suppression in human cancer cells using small interference RNA or mouse embryonic fibroblasts using an inducible-Cre/Lox system reduces mTORC1 activity. MCRS1 depletion promotes Rheb/TSC2 interaction, rendering Rheb inactive and delocalizing it from lysosomes to recycling endocytic vesicles, leading to mTORC1 inactivation. These findings have important implications for signaling mechanisms in various pathologies, including diabetes mellitus and cancer.
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Affiliation(s)
- Mohamad-Ali Fawal
- Cancer Cell Biology Programme, Growth Factors, Nutrients and Cancer Group, Centro Nacional de Investigaciones Oncológicas, CNIO, 28029 Madrid, Spain
| | - Marta Brandt
- Cancer Cell Biology Programme, Growth Factors, Nutrients and Cancer Group, Centro Nacional de Investigaciones Oncológicas, CNIO, 28029 Madrid, Spain
| | - Nabil Djouder
- Cancer Cell Biology Programme, Growth Factors, Nutrients and Cancer Group, Centro Nacional de Investigaciones Oncológicas, CNIO, 28029 Madrid, Spain.
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37
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Goorden SMI, Abs E, Bruinsma CF, Riemslagh FW, van Woerden GM, Elgersma Y. Intact neuronal function in Rheb1 mutant mice: implications for TORC1-based treatments. Hum Mol Genet 2015; 24:3390-8. [PMID: 25759467 DOI: 10.1093/hmg/ddv087] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Accepted: 03/04/2015] [Indexed: 12/16/2022] Open
Abstract
Target of rapamycin complex 1 (TORC1) is an important regulator of neuronal function. However, whereas a modest activation of the TORC1 signaling pathway has been shown to affect synaptic plasticity, learning and memory, the effect of TORC1 hypo-activation is less clear. This knowledge is particularly important since TORC1 inhibitors may hold great promise for treating a variety of disorders, including developmental disorders, aging-related disorders, epilepsy and cancer. Such treatments are likely to be long lasting and could involve treating young children. Hence, it is pivotal that the effects of sustained TORC1 inhibition on brain development and cognitive function are determined. Here, we made use of constitutive and conditional Rheb1 mutant mice to study the effect of prolonged and specific reduction in the TORC1 pathway. We show that Rheb1 mutant mice show up to 75% reduction in TORC1 signaling, but develop normally and show intact synaptic plasticity and hippocampus-dependent learning and memory. We discuss our findings in light of current literature in which the effect of pharmacological inhibition of TORC1 is studied in the context of synaptic plasticity and learning. We conclude that in contrast to TORC1 hyper-activity, cognitive function is not very sensitive to sustained and specific down-regulation of TORC1 activity.
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Affiliation(s)
- Susanna M I Goorden
- Department of Neuroscience and ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Elisabeth Abs
- Department of Neuroscience and ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Caroline F Bruinsma
- Department of Neuroscience and ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Fréderike W Riemslagh
- Department of Neuroscience and ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Geeske M van Woerden
- Department of Neuroscience and ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Ype Elgersma
- Department of Neuroscience and ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
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38
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Wang X, Wang Y, Zheng X, Hao X, Liang Y, Wu M, Wang X, Wang Z. Direct Interaction between Ras Homolog Enriched in Brain and FK506 Binding Protein 38 in Cashmere Goat Fetal Fibroblast Cells. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 27:1671-7. [PMID: 25358358 PMCID: PMC4213676 DOI: 10.5713/ajas.2014.14145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/08/2014] [Accepted: 07/14/2014] [Indexed: 11/27/2022]
Abstract
Ras homolog enriched in brain (Rheb) and FK506 binding protein 38 (FKBP38) are two important regulatory proteins in the mammalian target of rapamycin (mTOR) pathway. There are contradictory data on the interaction between Rheb and FKBP38 in human cells, but this association has not been examined in cashmere goat cells. To investigate the interaction between Rheb and FKBP38, we overexpressed goat Rheb and FKBP38 in goat fetal fibroblasts, extracted whole proteins, and performed coimmunoprecipitation to detect them by western blot. We found Rheb binds directly to FKBP38. Then, we constructed bait vectors (pGBKT7-Rheb/FKBP38) and prey vectors (pGADT7-Rheb/FKBP38), and examined their interaction by yeast two-hybrid assay. Their direct interaction was observed, regardless of which plasmid served as the prey or bait vector. These results indicate that the 2 proteins interact directly in vivo. Novel evidence is presented on the mTOR signal pathway in Cashmere goat cells.
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Affiliation(s)
- Xiaojing Wang
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Yanfeng Wang
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Xu Zheng
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Xiyan Hao
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Yan Liang
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Manlin Wu
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Xiao Wang
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
| | - Zhigang Wang
- Chifeng Municipal Hospital, Chifeng, Inner Mongolia 024000, China
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Xu K, Liu P, Wei W. mTOR signaling in tumorigenesis. Biochim Biophys Acta Rev Cancer 2014; 1846:638-54. [PMID: 25450580 DOI: 10.1016/j.bbcan.2014.10.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 10/23/2014] [Accepted: 10/25/2014] [Indexed: 12/25/2022]
Abstract
mTOR (the mechanistic target of rapamycin) is an atypical serine/threonine kinase involved in regulating major cellular functions including growth and proliferation. Deregulation of the mTOR signaling pathway is one of the most commonly observed pathological alterations in human cancers. To this end, oncogenic activation of the mTOR signaling pathway contributes to cancer cell growth, proliferation and survival, highlighting the potential for targeting the oncogenic mTOR pathway members as an effective anti-cancer strategy. In order to do so, a thorough understanding of the physiological roles of key mTOR signaling pathway components and upstream regulators would guide future targeted therapies. Thus, in this review, we summarize available genetic mouse models for mTORC1 and mTORC2 components, as well as characterized mTOR upstream regulators and downstream targets, and assign a potential oncogenic or tumor suppressive role for each evaluated molecule. Together, our work will not only facilitate the current understanding of mTOR biology and possible future research directions, but more importantly, provide a molecular basis for targeted therapies aiming at key oncogenic members along the mTOR signaling pathway.
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Affiliation(s)
- Kai Xu
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China; Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Pengda Liu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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40
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Recent progress in the study of the Rheb family GTPases. Cell Signal 2014; 26:1950-7. [PMID: 24863881 DOI: 10.1016/j.cellsig.2014.05.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 05/15/2014] [Indexed: 11/20/2022]
Abstract
In this review we highlight recent progress in the study of Rheb family GTPases. Structural studies using X-ray crystallography and NMR have given us insight into unique features of this GTPase. Combined with mutagenesis studies, these works have expanded our understanding of residues that affect Rheb GTP/GDP bound ratios, effector protein interactions, and stimulation of mTORC1 signaling. Analysis of cancer genome databases has revealed that several human carcinomas contain activating mutations of the protein. Rheb's role in activating mTORC1 signaling at the lysosome in response to stimuli has been further elucidated. Rheb has also been suggested to play roles in other cellular pathways including mitophagy and peroxisomal ROS response. A number of studies in mice have demonstrated the importance of Rheb in development, as well as in a variety of functions including cardiac protection and myelination. We conclude with a discussion of future prospects in the study of Rheb family GTPases.
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41
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Efeyan A, Schweitzer LD, Bilate AM, Chang S, Kirak O, Lamming DW, Sabatini DM. RagA, but not RagB, is essential for embryonic development and adult mice. Dev Cell 2014; 29:321-9. [PMID: 24768164 DOI: 10.1016/j.devcel.2014.03.017] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 03/10/2014] [Accepted: 03/23/2014] [Indexed: 01/08/2023]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates cues from growth factors and nutrients to control metabolism. In contrast to the growth factor input, genetic disruption of nutrient-dependent activation of mTORC1 in mammals remains unexplored. We engineered mice lacking RagA and RagB genes, which encode the GTPases responsible for mTORC1 activation by nutrients. RagB has limited expression, and its loss shows no effects on mammalian physiology. RagA deficiency leads to E10.5 embryonic death, loss of mTORC1 activity, and severe growth defects. Primary cells derived from these mice exhibit no regulation of mTORC1 by nutrients and maintain high sensitivity to growth factors. Deletion of RagA in adult mice is lethal. Upon RagA loss, a myeloid population expands in peripheral tissues. RagA-specific deletion in liver increases cellular responses to growth factors. These results show the essentiality of nutrient sensing for mTORC1 activity in mice and its suppression of PI3K/Akt signaling.
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Affiliation(s)
- Alejo Efeyan
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA; Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA; David H. Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA
| | - Lawrence D Schweitzer
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA; Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA; David H. Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA
| | - Angelina M Bilate
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Steven Chang
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA; Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA; David H. Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA
| | - Oktay Kirak
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Dudley W Lamming
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA; Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA; David H. Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA; Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA; David H. Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA.
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42
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Wu H, Han ZL, Cao YS, Lin S, Li X. Cardiac ablation of Rheb1 reduces sodium currents in infant mice. Int J Clin Exp Med 2014; 7:947-954. [PMID: 24955166 PMCID: PMC4057845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 03/12/2014] [Indexed: 06/03/2023]
Abstract
OBJECTIVE The Ras homolog enriched in brain gene (Rheb) is a center player within the insulin/Rheb/Mammalian Target of Rapamycin (mTOR) pathway, and plays a critical role in regulating cellular growth. Rheb-/- embryos have been reported to die around midgestation, due to the defects of the development of the cardiovascular system. Recent studies from ours and another group consistently showed that Rheb1 was indispensable for the cardiac hypertrophic growth after early postnatal period. Besides that, we also found that Rheb1 a-MHC-Cre (cKO) mice exhibited ventricular tachycardia. However, the precise mechanism by which Rheb1 knockout causes ventricular arrhythmia in these mice is still unclear. METHODS Mouse cardiomyocytes were isolated using 10 days suckling Rheb1 cKO and wide type mice using Collagenase Type II. Sodium currents and L-type calcium currents were recorded using the whole-cell patch clamping technique. RESULTS The sodium current density of ventricular cardiomyocytes from Rheb1 cKO mice was decreased by about 60%. Significant left shift but no slope altered was observed in activation curve with V1/2 values of -35.35 ± 1.12 mV for Rheb1 cKO group and -40.72 ± 1.18 mV for the controls. In addition, the area of window current, which refers the overlap of normalized activation and inactivation, was larger in Rheb1 cKO mice. Moreover, the sodium current, in general, was recovered much slower in Rheb1 cKO mice than that of the controls. However, L-type calcium currents were preserved in Rheb1 cKO mice. CONCLUSION Sodium currents are decreased in Rheb1 cKO mice, which might be responsible for the phenotype of arrhythima in Rheb1 cKO mice. Understanding the molecular composition of sodium ion channel complexes in the heart of these Rheb1 cKO mice will be critical to develop innovative and effective therapies for the treatment of cardiac arrhythmia.
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Affiliation(s)
- Hang Wu
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University Nanjing 210029, China ; Linhu Ward, Maanshan Municipal People's Hospital Maanshan 243021, China
| | - Zhong-Lin Han
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University Nanjing 210029, China
| | - Yun-Shan Cao
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University Nanjing 210029, China ; MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University Nanjing 210061, China
| | - Shenghui Lin
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University Nanjing 210029, China
| | - Xinli Li
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University Nanjing 210029, China
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43
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Abstract
The protein kinase mammalian or mechanistic target of rapamycin (mTOR) is an atypical serine/threonine kinase that exerts its main cellular functions by interacting with specific adaptor proteins to form 2 different multiprotein complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). mTORC1 regulates protein synthesis, cell growth and proliferation, autophagy, cell metabolism, and stress responses, whereas mTORC2 seems to regulate cell survival and polarity. The mTOR pathway plays a key regulatory function in cardiovascular physiology and pathology. However, the majority of information available about mTOR function in the cardiovascular system is related to the role of mTORC1 in the unstressed and stressed heart. mTORC1 is required for embryonic cardiovascular development and for postnatal maintenance of cardiac structure and function. In addition, mTORC1 is necessary for cardiac adaptation to pressure overload and development of compensatory hypertrophy. However, partial and selective pharmacological and genetic inhibition of mTORC1 was shown to extend life span in mammals, reduce pathological hypertrophy and heart failure caused by increased load or genetic cardiomyopathies, reduce myocardial damage after acute and chronic myocardial infarction, and reduce cardiac derangements caused by metabolic disorders. The optimal therapeutic strategy to target mTORC1 and increase cardioprotection is under intense investigation. This article reviews the information available regarding the effects exerted by mTOR signaling in cardiovascular physiology and pathological states.
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Affiliation(s)
- Sebastiano Sciarretta
- From the Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, NJ (S.S., J.S.); IRCCS Neuromed, Pozzilli, Italy (S.S., M.V.); and Division of Cardiology, Department of Clinical and Molecular Medicine, Faculty of Medicine and Psychology, University Sapienza, Rome, Italy (M.V.)
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44
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Shahani N, Pryor W, Swarnkar S, Kholodilov N, Thinakaran G, Burke RE, Subramaniam S. Rheb GTPase regulates β-secretase levels and amyloid β generation. J Biol Chem 2013; 289:5799-808. [PMID: 24368770 DOI: 10.1074/jbc.m113.532713] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The β-site amyloid precursor protein (APP)-cleaving enzyme 1 (β-secretase, BACE1) initiates amyloidogenic processing of APP to generate amyloid β (Aβ), which is a hallmark of Alzheimer disease (AD) pathology. Cerebral levels of BACE1 are elevated in individuals with AD, but the molecular mechanisms are not completely understood. We demonstrate that Rheb GTPase (Ras homolog enriched in brain), which induces mammalian target of rapamycin (mTOR) activity, is a physiological regulator of BACE1 stability and activity. Rheb overexpression depletes BACE1 protein levels and reduces Aβ generation, whereas the RNAi knockdown of endogenous Rheb promotes BACE1 accumulation, and this effect by Rheb is independent of its mTOR signaling. Moreover, GTP-bound Rheb interacts with BACE1 and degrades it through proteasomal and lysosomal pathways. Finally, we demonstrate that Rheb levels are down-regulated in the AD brain, which is consistent with an increased BACE1 expression. Altogether, our study defines Rheb as a novel physiological regulator of BACE1 levels and Aβ generation, and the Rheb-BACE1 circuitry may have a role in brain biology and disease.
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Affiliation(s)
- Neelam Shahani
- From the Department of Neuroscience, The Scripps Research Institute, Florida, Jupiter, Florida 33458
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45
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Cao Y, Tao L, Shen S, Xiao J, Wu H, Li B, Wu X, Luo W, Xiao Q, Hu X, Liu H, Nie J, Lu S, Yuan B, Han Z, Xiao B, Yang Z, Li X. Cardiac ablation of Rheb1 induces impaired heart growth, endoplasmic reticulum-associated apoptosis and heart failure in infant mice. Int J Mol Sci 2013; 14:24380-98. [PMID: 24351823 PMCID: PMC3876117 DOI: 10.3390/ijms141224380] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 11/25/2013] [Accepted: 12/03/2013] [Indexed: 11/19/2022] Open
Abstract
Ras homologue enriched in brain 1 (Rheb1) plays an important role in a variety of cellular processes. In this study, we investigate the role of Rheb1 in the post-natal heart. We found that deletion of the gene responsible for production of Rheb1 from cardiomyocytes of post-natal mice resulted in malignant arrhythmias, heart failure, and premature death of these mice. In addition, heart growth impairment, aberrant metabolism relative gene expression, and increased cardiomyocyte apoptosis were observed in Rheb1-knockout mice prior to the development of heart failure and arrhythmias. Also, protein kinase B (PKB/Akt) signaling was enhanced in Rheb1-knockout mice, and removal of phosphatase and tensin homolog (Pten) significantly prolonged the survival of Rheb1-knockouts. Furthermore, signaling via the mammalian target of rapamycin complex 1 (mTORC1) was abolished and C/EBP homologous protein (CHOP) and phosphorylation levels of c-Jun N-terminal kinase (JNK) were increased in Rheb1 mutant mice. In conclusion, this study demonstrates that Rheb1 is important for maintaining cardiac function in post-natal mice via regulation of mTORC1 activity and stress on the endoplasmic reticulum. Moreover, activation of Akt signaling helps to improve the survival of mice with advanced heart failure. Thus, this study provides direct evidence that Rheb1 performs multiple important functions in the heart of the post-natal mouse. Enhancing Akt activity improves the survival of infant mice with advanced heart failure.
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MESH Headings
- Animals
- Animals, Newborn
- Apoptosis
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/pathology
- Cells, Cultured
- Endoplasmic Reticulum/metabolism
- Heart/growth & development
- Heart/physiopathology
- Heart Failure/etiology
- Heart Failure/metabolism
- Heart Failure/pathology
- JNK Mitogen-Activated Protein Kinases/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Monomeric GTP-Binding Proteins/deficiency
- Monomeric GTP-Binding Proteins/genetics
- Monomeric GTP-Binding Proteins/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Neuropeptides/deficiency
- Neuropeptides/genetics
- Neuropeptides/metabolism
- PTEN Phosphohydrolase/metabolism
- Phosphoric Monoester Hydrolases/metabolism
- Phosphorylation
- Proto-Oncogene Proteins c-akt/metabolism
- Ras Homolog Enriched in Brain Protein
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Affiliation(s)
- Yunshan Cao
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Lichan Tao
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Shutong Shen
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Junjie Xiao
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- Regeneration Lab and Experimental Center of Life sciences, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Hang Wu
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Beibei Li
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Xiangqi Wu
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Wen Luo
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Qi Xiao
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Xiaoshan Hu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Hailang Liu
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Junwei Nie
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Shuangshuang Lu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Baiyin Yuan
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Zhonglin Han
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Bo Xiao
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; E-Mail:
| | - Zhongzhou Yang
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
- Authors to whom correspondence should be addressed; E-Mails: or (X.L.); (Z.Y.); Tel.: +86-25-8371-4511-6325 (X.L.); Fax: +86-25-8367-3396 (X.L.)
| | - Xinli Li
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- Authors to whom correspondence should be addressed; E-Mails: or (X.L.); (Z.Y.); Tel.: +86-25-8371-4511-6325 (X.L.); Fax: +86-25-8367-3396 (X.L.)
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Yang K, Shrestha S, Zeng H, Karmaus PWF, Neale G, Vogel P, Guertin DA, Lamb RF, Chi H. T cell exit from quiescence and differentiation into Th2 cells depend on Raptor-mTORC1-mediated metabolic reprogramming. Immunity 2013; 39:1043-56. [PMID: 24315998 DOI: 10.1016/j.immuni.2013.09.015] [Citation(s) in RCA: 292] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 09/23/2013] [Indexed: 12/24/2022]
Abstract
Naive T cells respond to antigen stimulation by exiting from quiescence and initiating clonal expansion and functional differentiation, but the control mechanism is elusive. Here we describe that Raptor-mTORC1-dependent metabolic reprogramming is a central determinant of this transitional process. Loss of Raptor abrogated T cell priming and T helper 2 (Th2) cell differentiation, although Raptor function is less important for continuous proliferation of actively cycling cells. mTORC1 coordinated multiple metabolic programs in T cells including glycolysis, lipid synthesis, and oxidative phosphorylation to mediate antigen-triggered exit from quiescence. mTORC1 further linked glucose metabolism to the initiation of Th2 cell differentiation by orchestrating cytokine receptor expression and cytokine responsiveness. Activation of Raptor-mTORC1 integrated T cell receptor and CD28 costimulatory signals in antigen-stimulated T cells. Our studies identify a Raptor-mTORC1-dependent pathway linking signal-dependent metabolic reprogramming to quiescence exit, and this in turn coordinates lymphocyte activation and fate decisions in adaptive immunity.
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Affiliation(s)
- Kai Yang
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Sharad Shrestha
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hu Zeng
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Peer W F Karmaus
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Geoffrey Neale
- Hartwell Center for Bioinformatics and Biotechnology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Peter Vogel
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - David A Guertin
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Richard F Lamb
- University of Liverpool Cancer Research UK Centre, 200 London Road, Liverpool L3 9TA, UK
| | - Hongbo Chi
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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Groenewoud MJ, Goorden SMI, Kassies J, Pellis-van Berkel W, Lamb RF, Elgersma Y, Zwartkruis FJT. Mammalian target of rapamycin complex I (mTORC1) activity in ras homologue enriched in brain (Rheb)-deficient mouse embryonic fibroblasts. PLoS One 2013; 8:e81649. [PMID: 24303063 PMCID: PMC3841147 DOI: 10.1371/journal.pone.0081649] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 10/15/2013] [Indexed: 11/19/2022] Open
Abstract
The Ras-like GTPase Rheb has been identified as a crucial activator of mTORC1. Activation most likely requires a direct interaction between Rheb and mTOR, but the exact mechanism remains unclear. Using a panel of Rheb-deficient mouse embryonic fibroblasts (MEFs), we show that Rheb is indeed essential for the rapid increase of mTORC1 activity following stimulation with insulin or amino acids. However, mTORC1 activity is less severely reduced in Rheb-deficient MEFs in the continuous presence of serum or upon stimulation with serum. This remaining mTORC1 activity is blocked by depleting the cells for amino acids or imposing energy stress. In addition, MEK inhibitors and the RSK-inhibitor BI-D1870 interfere in mTORC1 activity, suggesting that RSK acts as a bypass for Rheb in activating mTORC1. Finally, we show that this rapamycin-sensitive, Rheb-independent mTORC1 activity is important for cell cycle progression. In conclusion, whereas rapid adaptation in mTORC1 activity requires Rheb, a second Rheb-independent activation mechanism exists that contributes to cell cycle progression.
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Affiliation(s)
- Marlous J. Groenewoud
- Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Susan M. I. Goorden
- Department of Neuroscience, ENCORE expertise center for neuro-developmental disorders, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Jorien Kassies
- Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Wendy Pellis-van Berkel
- Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Richard F. Lamb
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Cancer Research UK Centre, Liverpool, United Kingdom
| | - Ype Elgersma
- Department of Neuroscience, ENCORE expertise center for neuro-developmental disorders, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Fried J. T. Zwartkruis
- Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Utrecht, The Netherlands
- * E-mail:
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48
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Loirand G, Sauzeau V, Pacaud P. Small G Proteins in the Cardiovascular System: Physiological and Pathological Aspects. Physiol Rev 2013; 93:1659-720. [DOI: 10.1152/physrev.00021.2012] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Small G proteins exist in eukaryotes from yeast to human and constitute the Ras superfamily comprising more than 100 members. This superfamily is structurally classified into five families: the Ras, Rho, Rab, Arf, and Ran families that control a wide variety of cell and biological functions through highly coordinated regulation processes. Increasing evidence has accumulated to identify small G proteins and their regulators as key players of the cardiovascular physiology that control a large panel of cardiac (heart rhythm, contraction, hypertrophy) and vascular functions (angiogenesis, vascular permeability, vasoconstriction). Indeed, basal Ras protein activity is required for homeostatic functions in physiological conditions, but sustained overactivation of Ras proteins or spatiotemporal dysregulation of Ras signaling pathways has pathological consequences in the cardiovascular system. The primary object of this review is to provide a comprehensive overview of the current progress in our understanding of the role of small G proteins and their regulators in cardiovascular physiology and pathologies.
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Affiliation(s)
- Gervaise Loirand
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
| | - Vincent Sauzeau
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
| | - Pierre Pacaud
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
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49
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Abs E, Goorden SMI, Schreiber J, Overwater IE, Hoogeveen-Westerveld M, Bruinsma CF, Aganović E, Borgesius NZ, Nellist M, Elgersma Y. TORC1-dependent epilepsy caused by acute biallelic Tsc1 deletion in adult mice. Ann Neurol 2013; 74:569-79. [PMID: 23720219 DOI: 10.1002/ana.23943] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 05/11/2013] [Accepted: 05/17/2013] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Seizure development in tuberous sclerosis complex (TSC) correlates with the presence of specific lesions called cortical tubers. Moreover, heterozygous TSC animal models do not show gross brain pathology and are seizure-free, suggesting that such pathology is a prerequisite for the development of epilepsy. However, cells within TSC lesions show increased activity of the target of rapamycin complex 1 (TORC1) pathway, and recent studies have implicated this pathway in non-TSC-related animal models of epilepsy and neuronal excitability. These findings imply a direct role for TORC1 in epilepsy. Here, we investigate the effect of increased TORC1 signaling induced by acute biallelic deletion of Tsc1 in healthy adult mice. METHODS Biallelic Tsc1 gene deletion was induced in adult Tsc1 heterozygous and wild-type mice. Seizures were monitored by electroencephalographic and video recordings. Molecular and cellular changes were investigated by Western blot analysis, immunohistochemistry, and electrophysiology. RESULTS Mice developed epilepsy a few days after biallelic Tsc1 deletion. Acute gene deletion was not accompanied by any obvious histological changes, but resulted in activation of the TORC1 pathway, enhanced neuronal excitability, and a decreased threshold for protein-synthesis-dependent long-term potentiation preceding the onset of seizures. Rapamycin treatment after seizure onset reduced TORC1 activity and fully abolished the seizures. INTERPRETATION Our data indicate a direct role for TORC1 signaling in epilepsy development, even in the absence of major brain pathology. This suggests that TORC1 is a promising target for treating seizures not only in TSC but also in other forms of epilepsy that result from increased TORC1 activation.
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Affiliation(s)
- Elisabeth Abs
- Department of Neuroscience, Erasmus University Medical Center, Rotterdam, the Netherlands; ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus University Medical Center, Rotterdam, the Netherlands
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50
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Jiang L, Xu L, Mao J, Li J, Fang L, Zhou Y, Liu W, He W, Zhao AZ, Yang J, Dai C. Rheb/mTORC1 signaling promotes kidney fibroblast activation and fibrosis. J Am Soc Nephrol 2013; 24:1114-26. [PMID: 23661807 DOI: 10.1681/asn.2012050476] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ras homolog enriched in brain (Rheb) is a small GTPase that regulates cell growth, differentiation, and survival by upregulating mammalian target of rapamycin complex 1 (mTORC1) signaling. The role of Rheb/mTORC1 signaling in the activation of kidney fibroblasts and the development of kidney fibrosis remains largely unknown. In this study, we found that Rheb/mTORC1 signaling was activated in interstitial myofibroblasts from fibrotic kidneys. Treatment of rat kidney interstitial fibroblasts (NRK-49F cell line) with TGFβ1 also activated Rheb/mTORC1 signaling. Blocking Rheb/mTORC1 signaling with rapamycin or Rheb small interfering RNA abolished TGFβ1-induced fibroblast activation. In a transgenic mouse, ectopic expression of Rheb activated kidney fibroblasts. These Rheb transgenic mice exhibited increased activation of mTORC1 signaling in both kidney tubular and interstitial cells as well as progressive interstitial renal fibrosis; rapamycin inhibited these effects. Similarly, mice with fibroblast-specific deletion of Tsc1, a negative regulator of Rheb, exhibited activated mTORC1 signaling in kidney interstitial fibroblasts and increased renal fibrosis, both of which rapamycin abolished. Taken together, these results suggest that Rheb/mTORC1 signaling promotes the activation of kidney fibroblasts and contributes to the development of interstitial fibrosis, possibly providing a therapeutic target for progressive renal disease.
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Affiliation(s)
- Lei Jiang
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
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