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Jiang X, Liu K, Luo P, Li Z, Xiao F, Jiang H, Wu S, Tang M, Yuan F, Li X, Shu Y, Peng B, Chen S, Ni S, Guo F. Hypothalamic SLC7A14 accounts for aging-reduced lipolysis in white adipose tissue of male mice. Nat Commun 2024; 15:7948. [PMID: 39261456 PMCID: PMC11391058 DOI: 10.1038/s41467-024-52059-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 08/21/2024] [Indexed: 09/13/2024] Open
Abstract
The central nervous system has been implicated in the age-induced reduction in adipose tissue lipolysis. However, the underlying mechanisms remain unclear. Here, we show the expression of SLC7A14 is reduced in proopiomelanocortin (POMC) neurons of aged mice. Overexpression of SLC7A14 in POMC neurons alleviates the aging-reduced lipolysis, whereas SLC7A14 deletion mimics the age-induced lipolysis impairment. Metabolomics analysis reveals that POMC SLC7A14 increased taurochenodeoxycholic acid (TCDCA) content, which mediates the SLC7A14 knockout- or age-induced WAT lipolysis impairment. Furthermore, SLC7A14-increased TCDCA content is dependent on intestinal apical sodium-dependent bile acid transporter (ASBT), which is regulated by intestinal sympathetic afferent nerves. Finally, SLC7A14 regulates the intestinal sympathetic afferent nerves by inhibiting mTORC1 signaling through inhibiting TSC1 phosphorylation. Collectively, our study suggests the function for central SLC7A14 and an upstream mechanism for the mTORC1 signaling pathway. Moreover, our data provides insights into the brain-gut-adipose tissue crosstalk in age-induced lipolysis impairment.
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Affiliation(s)
- Xiaoxue Jiang
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Kan Liu
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Innovation Center for Intervention of Chronic Disease and Promotion of Health, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Peixiang Luo
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Innovation Center for Intervention of Chronic Disease and Promotion of Health, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Zi Li
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Innovation Center for Intervention of Chronic Disease and Promotion of Health, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Fei Xiao
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Haizhou Jiang
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Shangming Wu
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Innovation Center for Intervention of Chronic Disease and Promotion of Health, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Min Tang
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Feixiang Yuan
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Xiaoying Li
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Yousheng Shu
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Bo Peng
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Shanghai Chen
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Shihong Ni
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China
| | - Feifan Guo
- Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200032, China.
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Xu W, Chen H, Xiao H. mTORC2: A neglected player in aging regulation. J Cell Physiol 2024:e31363. [PMID: 38982866 DOI: 10.1002/jcp.31363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/21/2024] [Accepted: 06/19/2024] [Indexed: 07/11/2024]
Abstract
Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a pivotal role in various biological processes, through integrating external and internal signals, facilitating gene transcription and protein translation, as well as by regulating mitochondria and autophagy functions. mTOR kinase operates within two distinct protein complexes known as mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which engage separate downstream signaling pathways impacting diverse cellular processes. Although mTORC1 has been extensively studied as a pro-proliferative factor and a pro-aging hub if activated aberrantly, mTORC2 received less attention, particularly regarding its implication in aging regulation. However, recent studies brought increasing evidence or clues for us, which implies the associations of mTORC2 with aging, as the genetic elimination of unique subunits of mTORC2, such as RICTOR, has been shown to alleviate aging progression in comparison to mTORC1 inhibition. In this review, we first summarized the basic characteristics of mTORC2, including its protein architecture and signaling network. We then focused on reviewing the molecular signaling regulation of mTORC2 in cellular senescence and organismal aging, and proposed the multifaceted regulatory characteristics under senescent and nonsenescent contexts. Next, we outlined the research progress of mTOR inhibitors in the field of antiaging and discussed future prospects and challenges. It is our pleasure if this review article could provide meaningful information for our readers and call forth more investigations working on this topic.
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Affiliation(s)
- Weitong Xu
- The Lab of Aging Research, National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Honghan Chen
- The Lab of Aging Research, National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Hengyi Xiao
- The Lab of Aging Research, National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
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Bugga P, Manning JR, Mushala BAS, Stoner MW, Sembrat J, Scott I. GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress. Cell Signal 2024; 116:111065. [PMID: 38281616 PMCID: PMC10922666 DOI: 10.1016/j.cellsig.2024.111065] [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: 11/07/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 01/30/2024]
Abstract
Cardiomyocyte apoptosis and cardiac fibrosis are the leading causes of mortality in patients with ischemic heart disease. As such, these processes represent potential therapeutic targets to treat heart failure resulting from ischemic insult. We previously demonstrated that the mitochondrial acetyltransferase protein GCN5L1 regulates cardiomyocyte cytoprotective signaling in ischemia-reperfusion injury in vivo and hypoxia-reoxygenation injury in vitro. The current study investigated the mechanism underlying GCN5L1-mediated regulation of the Akt/mTORC2 cardioprotective signaling pathway. Rictor protein levels in cardiac tissues from human ischemic heart disease patients were significantly decreased relative to non-ischemic controls. Rictor protein levels were similarly decreased in cardiac AC16 cells following hypoxic stress, while mRNA levels remained unchanged. The reduction in Rictor protein levels after hypoxia was enhanced by the knockdown of GCN5L1, and was blocked by GCN5L1 overexpression. These findings correlated with changes in Rictor lysine acetylation, which were mediated by GCN5L1 acetyltransferase activity. Rictor degradation was regulated by proteasomal activity, which was antagonized by increased Rictor acetylation. Finally, we found that GCN5L1 knockdown restricted cytoprotective Akt signaling, in conjunction with decreased mTOR abundance and activity. In summary, these studies suggest that GCN5L1 promotes cardioprotective Akt/mTORC2 signaling by maintaining Rictor protein levels through enhanced lysine acetylation.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Janet R Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Bellina A S Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Michael W Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - John Sembrat
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America.
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Javed S, Chang YT, Cho Y, Lee YJ, Chang HC, Haque M, Lin YC, Huang WH. Smith-Magenis syndrome protein RAI1 regulates body weight homeostasis through hypothalamic BDNF-producing neurons and neurotrophin downstream signalling. eLife 2023; 12:RP90333. [PMID: 37956053 PMCID: PMC10642964 DOI: 10.7554/elife.90333] [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] [Indexed: 11/15/2023] Open
Abstract
Retinoic acid-induced 1 (RAI1) haploinsufficiency causes Smith-Magenis syndrome (SMS), a genetic disorder with symptoms including hyperphagia, hyperlipidemia, severe obesity, and autism phenotypes. RAI1 is a transcriptional regulator with a pan-neural expression pattern and hundreds of downstream targets. The mechanisms linking neural Rai1 to body weight regulation remain unclear. Here we find that hypothalamic brain-derived neurotrophic factor (BDNF) and its downstream signalling are disrupted in SMS (Rai1+/-) mice. Selective Rai1 loss from all BDNF-producing cells or from BDNF-producing neurons in the paraventricular nucleus of the hypothalamus (PVH) induced obesity in mice. Electrophysiological recordings revealed that Rai1 ablation decreased the intrinsic excitability of PVHBDNF neurons. Chronic treatment of SMS mice with LM22A-4 engages neurotrophin downstream signalling and delayed obesity onset. This treatment also partially rescued disrupted lipid profiles, insulin intolerance, and stereotypical repetitive behaviour in SMS mice. These data argue that RAI1 regulates body weight and metabolic function through hypothalamic BDNF-producing neurons and that targeting neurotrophin downstream signalling might improve associated SMS phenotypes.
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Affiliation(s)
- Sehrish Javed
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Ya-Ting Chang
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Yoobin Cho
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Yu-Ju Lee
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Hao-Cheng Chang
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Minza Haque
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Yu Cheng Lin
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
| | - Wei-Hsiang Huang
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill UniversityMontréalCanada
- Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health CentreMontréalCanada
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5
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Bugga P, Manning JR, Mushala BA, Stoner MW, Sembrat J, Scott I. GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564170. [PMID: 37961692 PMCID: PMC10634848 DOI: 10.1101/2023.10.26.564170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Cardiomyocyte apoptosis and cardiac fibrosis are the leading causes of mortality in patients with ischemic heart disease. As such, these processes represent potential therapeutic targets to treat heart failure resulting from ischemic insult. We previously demonstrated that the mitochondrial acetyltransferase protein GCN5L1 regulates cardiomyocyte cytoprotective signaling in ischemia-reperfusion injury in vivo and hypoxia-reoxygenation injury in vitro. The current study investigated the mechanism underlying GCN5L1-mediated regulation of the Akt/mTORC2 cardioprotective signaling pathway. Rictor protein levels in cardiac tissues from human ischemic heart disease patients were significantly decreased relative to non-ischemic controls. Rictor protein levels were similarly decreased in cardiac AC16 cells following hypoxic stress, while mRNA levels remained unchanged. The reduction in Rictor protein levels after hypoxia was enhanced by the knockdown of GCN5L1, and was blocked by GCN5L1 overexpression. These findings correlated with changes in Rictor lysine acetylation, which were mediated by GCN5L1 acetyltransferase activity. Rictor degradation was regulated by proteasomal activity, which was antagonized by increased Rictor acetylation. Finally, we found that GCN5L1 knockdown restricted cytoprotective Akt signaling, in conjunction with decreased mTOR abundance and activity. In summary, these studies suggest that GCN5L1 promotes cardioprotective Akt/mTORC2 signaling by maintaining Rictor protein levels through enhanced lysine acetylation.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Janet R. Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Bellina A.S. Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Michael W. Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - John Sembrat
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
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6
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McIlwraith EK, Belsham DD. Palmitate alters miR-2137 and miR-503-5p to induce orexigenic Npy in hypothalamic neuronal cell models: Rescue by oleate and docosahexaenoic acid. J Neuroendocrinol 2023; 35:e13271. [PMID: 37208960 DOI: 10.1111/jne.13271] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/29/2023] [Accepted: 03/30/2023] [Indexed: 05/21/2023]
Abstract
MicroRNAs (miRNAs) are short noncoding RNA implicated in the pathogenesis of obesity. One cause of obesity is excess exposure to the saturated fatty acid palmitate that can alter miRNA levels in the periphery. Palmitate also promotes obesity by acting on the hypothalamus, the central coordinator of energy homeostasis, to dysregulate hypothalamic feeding neuropeptides and induce ER stress and inflammatory signaling. We hypothesized that palmitate would alter hypothalamic miRNAs that control genes involved in energy homeostasis thereby contributing to the obesity-promoting effects of palmitate. We found that palmitate upregulated 20 miRNAs and downregulated six miRNAs in the orexigenic NPY/AgRP-expressing mHypoE-46 cell line. We focused on delineating the roles of miR-2137 and miR-503-5p, as they were strongly up- and downregulated by palmitate, respectively. Overexpression of miR-2137 increased Npy mRNA levels and downregulated Esr1 levels, while increasing C/ebpβ and Atf3 mRNA. Inhibiting miR-2137 had the opposite effect, except on Npy, which was unchanged. The most downregulated miRNA by palmitate, miR-503-5p, negatively regulated Npy mRNA levels. Exposure to the unsaturated fatty acids oleate or docosahexaenoic acid completely or partially blocked the effects of palmitate on miR-2137 and miR-503-5p as well as Npy, Agrp, Esr1, C/ebpβ and Atf3. MicroRNAs may therefore contribute to palmitate actions in dysregulating NPY/AgRP neurons. Effectively combating the deleterious effects of palmitate is crucial to help prevent or reduce the impact of obesity.
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Affiliation(s)
- Emma K McIlwraith
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Denise D Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Departments of Medicine and Obstetrics and Gynecology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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7
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Blandino-Rosano M, Scheys JO, Werneck-de-Castro JP, Louzada RA, Almaça J, Leibowitz G, Rüegg MA, Hall MN, Bernal-Mizrachi E. Novel roles of mTORC2 in regulation of insulin secretion by actin filament remodeling. Am J Physiol Endocrinol Metab 2022; 323:E133-E144. [PMID: 35723227 PMCID: PMC9291412 DOI: 10.1152/ajpendo.00076.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mammalian target of rapamycin (mTOR) kinase is an essential hub where nutrients and growth factors converge to control cellular metabolism. mTOR interacts with different accessory proteins to form complexes 1 and 2 (mTORC), and each complex has different intracellular targets. Although mTORC1's role in β-cells has been extensively studied, less is known about mTORC2's function in β-cells. Here, we show that mice with constitutive and inducible β-cell-specific deletion of RICTOR (βRicKO and iβRicKO mice, respectively) are glucose intolerant due to impaired insulin secretion when glucose is injected intraperitoneally. Decreased insulin secretion in βRicKO islets was caused by abnormal actin polymerization. Interestingly, when glucose was administered orally, no difference in glucose homeostasis and insulin secretion were observed, suggesting that incretins are counteracting the mTORC2 deficiency. Mechanistically, glucagon-like peptide-1 (GLP-1), but not gastric inhibitory polypeptide (GIP), rescued insulin secretion in vivo and in vitro by improving actin polymerization in βRicKO islets. In conclusion, mTORC2 regulates glucose-stimulated insulin secretion by promoting actin filament remodeling.NEW & NOTEWORTHY The current studies uncover a novel mechanism linking mTORC2 signaling to glucose-stimulated insulin secretion by modulation of the actin filaments. This work also underscores the important role of GLP-1 in rescuing defects in insulin secretion by modulating actin polymerization and suggests that this effect is independent of mTORC2 signaling.
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Affiliation(s)
- Manuel Blandino-Rosano
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Joshua O Scheys
- Medical School, Division of Metabolism, Endocrinology, and Diabetes and Brehm Center for Diabetes Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Joao Pedro Werneck-de-Castro
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Ruy A Louzada
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Joana Almaça
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Gil Leibowitz
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | | | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
- Miami VA Healthcare System, Miami, Florida
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8
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eIF3a regulation of mTOR signaling and translational control via HuR in cellular response to DNA damage. Oncogene 2022; 41:2431-2443. [PMID: 35279705 PMCID: PMC9035104 DOI: 10.1038/s41388-022-02262-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 02/16/2022] [Accepted: 02/23/2022] [Indexed: 01/29/2023]
Abstract
eIF3a (eukaryotic translation initiation factor 3a), a subunit of the eIF3 complex, has been suggested to play a regulatory role in protein synthesis and in cellular response to DNA-damaging treatments. S6K1 is an effector and a mediator of mTOR complex 1 (mTORC1) in regulating protein synthesis and integrating diverse signals into control of cell growth and response to stress. Here, we show that eIF3a regulates S6K1 activity by inhibiting mTORC1 kinase via regulating Raptor synthesis. The regulation of Raptor synthesis is via eIF3a interaction with HuR (human antigen R) and binding of the eIF3a-HuR complex to the 5'-UTR of Raptor mRNA. Furthermore, mTORC1 may mediate eIF3a function in cellular response to cisplatin by regulating synthesis of NER proteins and NER activity. Taken together, we conclude that the mTOR signaling pathway may also be regulated by translational control and mediate eIF3a regulation of cancer cell response to cisplatin by regulating NER protein synthesis.
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9
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Oliveira LDC, Morais GP, Ropelle ER, de Moura LP, Cintra DE, Pauli JR, de Freitas EC, Rorato R, da Silva ASR. Using Intermittent Fasting as a Non-pharmacological Strategy to Alleviate Obesity-Induced Hypothalamic Molecular Pathway Disruption. Front Nutr 2022; 9:858320. [PMID: 35445066 PMCID: PMC9014844 DOI: 10.3389/fnut.2022.858320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 02/25/2022] [Indexed: 12/18/2022] Open
Abstract
Intermittent fasting (IF) is a popular intervention used to fight overweight/obesity. This condition is accompanied by hypothalamic inflammation, limiting the proper signaling of molecular pathways, with consequent dysregulation of food intake and energy homeostasis. This mini-review explored the therapeutic modulation potential of IF regarding the disruption of these molecular pathways. IF seems to modulate inflammatory pathways in the brain, which may also be correlated with the brain-microbiota axis, improving hypothalamic signaling of leptin and insulin, and inducing the autophagic pathway in hypothalamic neurons, contributing to weight loss in obesity. Evidence also suggests that when an IF protocol is performed without respecting the circadian cycle, it can lead to dysregulation in the expression of circadian cycle regulatory genes, with potential health damage. In conclusion, IF may have the potential to be an adjuvant treatment to improve the reestablishment of hypothalamic responses in obesity.
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Affiliation(s)
- Luciana da Costa Oliveira
- Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Gustavo Paroschi Morais
- Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Eduardo R. Ropelle
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - Leandro P. de Moura
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - Dennys E. Cintra
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - José R. Pauli
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - Ellen C. de Freitas
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | - Rodrigo Rorato
- Postgraduate Program in Molecular Biology, Laboratory of Stress Neuroendocrinology, Department of Biophysics, Paulista Medical School, Federal University of São Paulo, São Paulo, Brazil
- Rodrigo Rorato,
| | - Adelino Sanchez R. da Silva
- Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
- *Correspondence: Adelino Sanchez R. da Silva,
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Yang L, Zhang Z, Wang D, Jiang Y, Liu Y. Targeting mTOR Signaling in Type 2 Diabetes Mellitus and Diabetes Complications. Curr Drug Targets 2022; 23:692-710. [PMID: 35021971 DOI: 10.2174/1389450123666220111115528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/21/2021] [Accepted: 12/01/2021] [Indexed: 11/22/2022]
Abstract
The mechanistic target of rapamycin (mTOR) is a pivotal regulator of cell metabolism and growth. In the form of two different multi-protein complexes, mTORC1 and mTORC2, mTOR integrates cellular energy, nutrient and hormonal signals to regulate cellular metabolic homeostasis. In type 2 diabetes mellitus (T2DM) aberrant mTOR signaling underlies its pathological conditions and end-organ complications. Substantial evidence suggests that two mTOR-mediated signaling schemes, mTORC1-p70S6 kinase 1 (S6K1) and mTORC2-protein kinase B (AKT), play a critical role in insulin sensitivity and that their dysfunction contributes to development of T2DM. This review summaries our current understanding of the role of mTOR signaling in T2DM and its associated complications, as well as the potential use of mTOR inhibitors in treatment of T2DM.
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Affiliation(s)
- Lin Yang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Zhixin Zhang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Doudou Wang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Ying Liu
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
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Abstract
Cells metabolize nutrients for biosynthetic and bioenergetic needs to fuel growth and proliferation. The uptake of nutrients from the environment and their intracellular metabolism is a highly controlled process that involves cross talk between growth signaling and metabolic pathways. Despite constant fluctuations in nutrient availability and environmental signals, normal cells restore metabolic homeostasis to maintain cellular functions and prevent disease. A central signaling molecule that integrates growth with metabolism is the mechanistic target of rapamycin (mTOR). mTOR is a protein kinase that responds to levels of nutrients and growth signals. mTOR forms two protein complexes, mTORC1, which is sensitive to rapamycin, and mTORC2, which is not directly inhibited by this drug. Rapamycin has facilitated the discovery of the various functions of mTORC1 in metabolism. Genetic models that disrupt either mTORC1 or mTORC2 have expanded our knowledge of their cellular, tissue, as well as systemic functions in metabolism. Nevertheless, our knowledge of the regulation and functions of mTORC2, particularly in metabolism, has lagged behind. Since mTOR is an important target for cancer, aging, and other metabolism-related pathologies, understanding the distinct and overlapping regulation and functions of the two mTOR complexes is vital for the development of more effective therapeutic strategies. This review discusses the key discoveries and recent findings on the regulation and metabolic functions of the mTOR complexes. We highlight findings from cancer models but also discuss other examples of the mTOR-mediated metabolic reprogramming occurring in stem and immune cells, type 2 diabetes/obesity, neurodegenerative disorders, and aging.
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Affiliation(s)
- Angelia Szwed
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Eugene Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
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12
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Chawsheen MA, Dash PR. mTOR modulates resistance to gemcitabine in lung cancer in an MTORC2 dependent mechanism. Cell Signal 2021; 81:109934. [PMID: 33545231 DOI: 10.1016/j.cellsig.2021.109934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND Lung cancer has a poor prognosis partly due to a lack of response to treatments such as the chemotherapy drug gemcitabine. Combinations of chemotherapy drugs with signal transduction inhibitors may be more effective treatments. In this study we have investigated the impact of targeting the mTOR signalling pathway on the efficacy of gemcitabine in different cancer cell lines. METHODS Time-lapse microscopy, immuno-staining, and western blot techniques were used to evaluate the efficacy of applied treatments either in measuring phosphorylation levels of mTOR down-stream targets or in tracking down the fate of targeted cells. Reactive oxygen species and relative levels of protein phosphorylation were also quantified. For comparison between treated groups t-test and analysis of variance test were applied. RESULTS Our data showed that mTORC1 has no role in sensitising A549 lung cancer cells to gemcitabine. However, targeting mTORC1/2 with the pharmacological inhibitor torin1 or by over-expressing Deptor, the negative regulator of mTOR signalling, sensitised these cells to gemcitabine. Silencing mTORC2, but not mTORC1, induced apoptosis and significantly improved the apoptosis-inducing effects of gemcitabine. Results also suggest that Rictor is required to maintain cell survival through modulating p38α, ERK1/2, RSK1/2/3 and the transcription factor STAT3. Multiple cell line comparisons revealed that PANC-1 pancreatic cancer cells were also sensitive to mTOR inhibition, but MCF7 breast cancer, MCF10A breast epithelial and H727 lung cancer cell lines were more resistant to the treatment. CONCLUSIONS Inhibition of mTORC2 may have benefits in the treatment of gemcitabine resistant cancers, and the genetic background of the cell line may determine its response to mTOR inhibition.
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Affiliation(s)
| | - Philip R Dash
- University of Reading, School of Biological Sciences, Reading, UK
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13
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Yang AJT, Frendo-Cumbo S, MacPherson REK. Resveratrol and Metformin Recover Prefrontal Cortex AMPK Activation in Diet-Induced Obese Mice but Reduce BDNF and Synaptophysin Protein Content. J Alzheimers Dis 2020; 71:945-956. [PMID: 31450493 DOI: 10.3233/jad-190123] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Obesity, insulin resistance, and type 2 diabetes are established risk factors for the development of Alzheimer's disease (AD). Given this connection, two drugs, metformin (MET) and resveratrol (RESV), are considered for the clearance of amyloid-β peptides through AMPK-mediated activation of autophagy. However, overactivation of AMPK observed in late-stage AD brains and relationships between AMPK and neurogenesis (through mTORC1 inhibition), questions treatment with these drugs. OBJECTIVE To examine if MET and/or RESV supplementation activates brain AMPK, regulates markers of autophagy, and affects markers of neuronal health/neurogenesis. METHODS 8-week-old male C57BL/6J mice were fed a low (N = 12; 10% kcal fat; LFD) or high fat diet (N = 40; 60% kcal fat; HFD) for 9 weeks to induce insulin resistance and obesity. HFD mice were then treated with/without MET (250 mg/kg/day), RESV (100 mg/kg/day), or COMBO (MET: 250 mg/kg/day, RESV: 100 mg/kg/day) for 5 weeks. Hippocampus and prefrontal cortex were extracted for western blotting analysis. RESULTS Cortex AMPK (T172) and raptor (S792, the regulatory subunit of mTORC1) phosphorylation were upregulated following RESV, COMBO treatments. mTOR (S2448) and ULK1 (S555) activation was seen following MET, COMBO and RESV, COMBO treatments, respectively, in the cortex and hippocampus. p62 content was decreased following RESV, COMBO, with LC3 content being increased following RESV treatment in the cortex. Brain derived neurotropic factor (BDNF) was significantly decreased following RESV, COMBO, and synaptophysin following all treatment in the cortex. CONCLUSION These results demonstrate that while treatments upregulated markers of autophagy in the prefrontal cortex, reductions in neuronal health markers question the efficacy of AMPK as a therapy for AD.
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Affiliation(s)
- Alex J T Yang
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Scott Frendo-Cumbo
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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14
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You Y, Ru X, Lei W, Li T, Xiao M, Zheng H, Chen Y, Zhang L. Developing the novel bioinformatics algorithms to systematically investigate the connections among survival time, key genes and proteins for Glioblastoma multiforme. BMC Bioinformatics 2020; 21:383. [PMID: 32938364 PMCID: PMC7646399 DOI: 10.1186/s12859-020-03674-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Glioblastoma multiforme (GBM) is one of the most common malignant brain tumors and its average survival time is less than 1 year after diagnosis. RESULTS Firstly, this study aims to develop the novel survival analysis algorithms to explore the key genes and proteins related to GBM. Then, we explore the significant correlation between AEBP1 upregulation and increased EGFR expression in primary glioma, and employ a glioma cell line LN229 to identify relevant proteins and molecular pathways through protein network analysis. Finally, we identify that AEBP1 exerts its tumor-promoting effects by mainly activating mTOR pathway in Glioma. CONCLUSIONS We summarize the whole process of the experiment and discuss how to expand our experiment in the future.
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Affiliation(s)
- Yujie You
- College of Computer Science, Sichuan University, Chengdu, 610065 China
| | - Xufang Ru
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, P.R. China
| | - Wanjing Lei
- College of Computer Science, Sichuan University, Chengdu, 610065 China
| | - Tingting Li
- College of Mathematics and Statistics, Southwest University, Chongqing, 400715 P.R. China
| | - Ming Xiao
- College of Computer Science, Sichuan University, Chengdu, 610065 China
| | - Huiru Zheng
- School of Computing, Ulster University, Coleraine, Londonderry, Northern Ireland, UK
| | - Yujie Chen
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, P.R. China
| | - Le Zhang
- College of Computer Science, Sichuan University, Chengdu, 610065 China
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15
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Pena-Leon V, Perez-Lois R, Seoane LM. mTOR Pathway is Involved in Energy Homeostasis Regulation as a Part of the Gut-Brain Axis. Int J Mol Sci 2020; 21:ijms21165715. [PMID: 32784967 PMCID: PMC7460813 DOI: 10.3390/ijms21165715] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian, or mechanic, target of rapamycin (mTOR) signaling is a crucial factor in the regulation of the energy balance that functions as an energy sensor in the body. The present review explores how the mTOR/S6k intracellular pathway is involved in modulating the production of different signals such as ghrelin and nesfatin-1 in the gastrointestinal tract to regulate food intake and body weight. The role of gastric mTOR signaling in different physiological processes was studied in depth through different genetic models that allow the modulation of mTOR signaling in the stomach and specifically in gastric X/A type cells. It has been described that mTOR signaling in X/A-like gastric cells has a relevant role in the regulation of glucose and lipid homeostasis due to its interaction with different organs such as liver and adipose tissue. These findings highlight possible therapeutic strategies, with the gut–brain axis being one of the most promising targets in the treatment of obesity.
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Affiliation(s)
- Veronica Pena-Leon
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Raquel Perez-Lois
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Luisa Maria Seoane
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence:
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16
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Jung SH, Meckes JK, Schipma MJ, Lim PH, Jenz ST, Przybyl K, Wert SL, Kim S, Luo W, Gacek SA, Jankord R, Hatcher-Solis C, Redei EE. Strain Differences in Responsiveness to Repeated Restraint Stress Affect Remote Contextual Fear Memory and Blood Transcriptomics. Neuroscience 2020; 444:76-91. [PMID: 32768618 DOI: 10.1016/j.neuroscience.2020.07.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/15/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022]
Abstract
The role of stress in altering fear memory is not well understood. Since individual variations in stress reactivity exist, and stress alters fear memory, exposing individuals with differing stress-reactivity to repeated stress would affect their fear memory to various degrees. We explored this question using the average stress-reactive Fisher 344 (F344) rat strain and the Wistar-Kyoto (WKY) strain with its heightened stress-reactivity. Male F344 and WKY rats were exposed to the contextual fear conditioning (CFC) paradigm and then chronic restraint stress (CRS) or no stress (NS) was administered for two weeks before a second CFC. Both recent and reinstated fear memory were greater in F344s than WKYs, regardless of the stress status. In contrast, remote memory was attenuated only in F344s after CRS. In determining whether this strain-specific response to CRS was mirrored by transcriptomic changes in the blood, RNA sequencing was carried out. Overlapping differentially expressed genes (DEGs) between NS and CRS in the blood of F344 and WKY suggest a convergence of stress-related molecular mechanisms, independent of stress-reactivity. In contrast, DEGs unique to the F344 and the WKY stress responses are divergent in their functionality and networks, beyond that of strain differences in their non-stressed state. These results suggest that in some individuals chronic or repeated stress, different from the original fear memory-provoking stress, can attenuate prior fear memory. Furthermore, the novel blood DEGs can report on the general state of stress of the individual, or can be associated with individual variation in stress-responsiveness.
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Affiliation(s)
- Seung H Jung
- Applied Neuroscience, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | - Jeanie K Meckes
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Matthew J Schipma
- NUSeq Core, Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Patrick H Lim
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Sophia T Jenz
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Katherine Przybyl
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Stephanie L Wert
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Sarah Kim
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Wendy Luo
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Stephanie A Gacek
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Ryan Jankord
- Applied Neuroscience, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | - Candice Hatcher-Solis
- Applied Neuroscience, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
| | - Eva E Redei
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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17
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Smith HJ, Sharma A, Mair WB. Metabolic Communication and Healthy Aging: Where Should We Focus Our Energy? Dev Cell 2020; 54:196-211. [PMID: 32619405 DOI: 10.1016/j.devcel.2020.06.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/01/2020] [Accepted: 06/07/2020] [Indexed: 02/09/2023]
Abstract
Aging is associated with a loss of metabolic homeostasis and plasticity, which is causally linked to multiple age-onset pathologies. The majority of the interventions-genetic, dietary, and pharmacological-that have been found to slow aging and protect against age-related disease in various organisms do so by targeting central metabolic pathways. However, targeting metabolic pathways chronically and ubiquitously makes it difficult to define the downstream effects responsible for lifespan extension and often results in negative effects on growth and health, limiting therapeutic potential. Insight into how metabolic signals are relayed between tissues, cells, and organelles opens up new avenues to target metabolic regulators locally rather than globally for healthy aging. In this review, we discuss the pro-longevity effects of targeting metabolic pathways in specific tissues and how these interventions communicate with distal cells to modulate aging. These studies may be crucial in designing interventions that promote longevity without negative health consequences.
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Affiliation(s)
- Hannah J Smith
- Harvard T.H. Chan School of Public Health, Department of Molecular Metabolism, Boston, MA, USA
| | - Arpit Sharma
- Harvard T.H. Chan School of Public Health, Department of Molecular Metabolism, Boston, MA, USA
| | - William B Mair
- Harvard T.H. Chan School of Public Health, Department of Molecular Metabolism, Boston, MA, USA.
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18
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Chellappa K, Brinkman JA, Mukherjee S, Morrison M, Alotaibi MI, Carbajal KA, Alhadeff AL, Perron IJ, Yao R, Purdy CS, DeFelice DM, Wakai MH, Tomasiewicz J, Lin A, Meyer E, Peng Y, Arriola Apelo SI, Puglielli L, Betley JN, Paschos GK, Baur JA, Lamming DW. Hypothalamic mTORC2 is essential for metabolic health and longevity. Aging Cell 2019; 18:e13014. [PMID: 31373126 PMCID: PMC6718533 DOI: 10.1111/acel.13014] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/26/2019] [Accepted: 07/03/2019] [Indexed: 12/16/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is an evolutionarily conserved protein kinase that regulates growth and metabolism. mTOR is found in two protein complexes, mTORC1 and mTORC2, that have distinct components and substrates and are both inhibited by rapamycin, a macrolide drug that robustly extends lifespan in multiple species including worms and mice. Although the beneficial effect of rapamycin on longevity is generally attributed to reduced mTORC1 signaling, disruption of mTORC2 signaling can also influence the longevity of worms, either positively or negatively depending on the temperature and food source. Here, we show that loss of hypothalamic mTORC2 signaling in mice decreases activity level, increases the set point for adiposity, and renders the animals susceptible to diet-induced obesity. Hypothalamic mTORC2 signaling normally increases with age, and mice lacking this pathway display higher fat mass and impaired glucose homeostasis throughout life, become more frail with age, and have decreased overall survival. We conclude that hypothalamic mTORC2 is essential for the normal metabolic health, fitness, and lifespan of mice. Our results have implications for the use of mTORC2-inhibiting pharmaceuticals in the treatment of brain cancer and diseases of aging.
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Affiliation(s)
- Karthikeyani Chellappa
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Jacqueline A. Brinkman
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
| | - Sarmistha Mukherjee
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Mark Morrison
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
| | - Mohammed I. Alotaibi
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Endocrinology and Reproductive Physiology Graduate Training ProgramUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Kathryn A. Carbajal
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
| | - Amber L. Alhadeff
- Department of Biology, School of Arts and SciencesUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Isaac J. Perron
- Center for Sleep and Circadian Neurobiology, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Rebecca Yao
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Cole S. Purdy
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Denise M. DeFelice
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Matthew H. Wakai
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
| | - Jay Tomasiewicz
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Amy Lin
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Department of Dairy ScienceUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Emma Meyer
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Department of Dairy ScienceUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Yajing Peng
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Waisman CenterUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Sebastian I. Arriola Apelo
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Department of Dairy ScienceUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Luigi Puglielli
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Waisman CenterUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - J. Nicholas Betley
- Department of Biology, School of Arts and SciencesUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Georgios K. Paschos
- Center for Sleep and Circadian Neurobiology, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
- The Institute for Translational Medicine and Therapeutics, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Joseph A. Baur
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Dudley W. Lamming
- Department of MedicineUniversity of Wisconsin‐MadisonMadisonWIUSA
- William S. Middleton Memorial Veterans HospitalMadisonWIUSA
- Endocrinology and Reproductive Physiology Graduate Training ProgramUniversity of Wisconsin‐MadisonMadisonWIUSA
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19
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Higgins MG, Kenny DA, Fitzsimons C, Blackshields G, Coyle S, McKenna C, McGee M, Morris DW, Waters SM. The effect of breed and diet type on the global transcriptome of hepatic tissue in beef cattle divergent for feed efficiency. BMC Genomics 2019; 20:525. [PMID: 31242854 PMCID: PMC6593537 DOI: 10.1186/s12864-019-5906-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 06/17/2019] [Indexed: 01/07/2023] Open
Abstract
Background Feed efficiency is an important economic and environmental trait in beef production, which can be measured in terms of residual feed intake (RFI). Cattle selected for low-RFI (feed efficient) have similar production levels but decreased feed intake, while also emitting less methane. RFI is difficult and expensive to measure and is not widely adopted in beef production systems. However, development of DNA-based biomarkers for RFI may facilitate its adoption in genomic-assisted breeding programmes. Cattle have been shown to re-rank in terms of RFI across diets and age, while also RFI varies by breed. Therefore, we used RNA-Seq technology to investigate the hepatic transcriptome of RFI-divergent Charolais (CH) and Holstein-Friesian (HF) steers across three dietary phases to identify genes and biological pathways associated with RFI regardless of diet or breed. Results Residual feed intake was measured during a high-concentrate phase, a zero-grazed grass phase and a final high-concentrate phase. In total, 322 and 33 differentially expressed genes (DEGs) were identified across all diets for CH and HF steers, respectively. Three genes, GADD45G, HP and MID1IP1, were differentially expressed in CH when both the high-concentrate zero-grazed grass diet were offered. Two canonical pathways were enriched across all diets for CH steers. These canonical pathways were related to immune function. Conclusions The absence of common differentially expressed genes across all dietary phases and breeds in this study supports previous reports of the re-ranking of animals in terms of RFI when offered differing diets over their lifetime. However, we have identified biological processes such as the immune response and lipid metabolism as potentially associated with RFI divergence emphasising the previously reported roles of these biological processes with respect to RFI. Electronic supplementary material The online version of this article (10.1186/s12864-019-5906-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marc G Higgins
- Discipline of Biochemistry, National University of Ireland, Galway, Ireland.,Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland
| | - David A Kenny
- Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland
| | - Claire Fitzsimons
- Livestock Systems Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland.,Present address: Department of Agriculture, Fisheries and the Marine, Celbridge, Co. Kildare, Ireland
| | - Gordon Blackshields
- Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland
| | - Séan Coyle
- Livestock Systems Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland
| | - Clare McKenna
- Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland
| | - Mark McGee
- Livestock Systems Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland
| | - Derek W Morris
- Discipline of Biochemistry, National University of Ireland, Galway, Ireland
| | - Sinéad M Waters
- Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre Teagasc, Grange, Dunsany, Co. Meath, Ireland.
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20
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Molecular Mechanisms of Hypothalamic Insulin Resistance. Int J Mol Sci 2019; 20:ijms20061317. [PMID: 30875909 PMCID: PMC6471380 DOI: 10.3390/ijms20061317] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/07/2019] [Accepted: 03/13/2019] [Indexed: 02/06/2023] Open
Abstract
Insulin exists in the central nervous system, where it executes two important functions in the hypothalamus: the suppression of food intake and the improvement of glucose metabolism. Recent studies have shown that both are exerted robustly in rodents and humans. If intact, these functions exert beneficial effects on obesity and diabetes, respectively. Disruption of both occurs due to a condition known as hypothalamic insulin resistance, which is caused by obesity and the overconsumption of saturated fat. An enormous volume of literature addresses the molecular mechanisms of hypothalamic insulin resistance. IKKβ and JNK are major players in the inflammation pathway, which is activated by saturated fatty acids that induce hypothalamic insulin resistance. Two major tyrosine phosphatases, PTP-1B and TCPTP, are upregulated in chronic overeating. They dephosphorylate the insulin receptor and insulin receptor substrate proteins, resulting in hypothalamic insulin resistance. Prolonged hyperinsulinemia with excessive nutrition activates the mTOR/S6 kinase pathway, thereby enhancing IRS-1 serine phosphorylation to induce hypothalamic insulin resistance. Other mechanisms associated with this condition include hypothalamic gliosis and disturbed insulin transport into the central nervous system. Unveiling the precise molecular mechanisms involved in hypothalamic insulin resistance is important for developing new ways of treating obesity and type 2 diabetes.
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21
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Ouyang X, Han Y, Qu G, Li M, Wu N, Liu H, Arojo O, Sun H, Liu X, Liu D, Chen L, Zou Q, Su B. Metabolic regulation of T cell development by Sin1-mTORC2 is mediated by pyruvate kinase M2. J Mol Cell Biol 2019; 11:93-106. [PMID: 30428057 PMCID: PMC6392101 DOI: 10.1093/jmcb/mjy065] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/16/2018] [Accepted: 11/13/2018] [Indexed: 12/16/2022] Open
Abstract
Glucose metabolism plays a key role in thymocyte development. The mammalian target of rapamycin complex 2 (mTORC2) is a critical regulator of cell growth and metabolism, but its role in early thymocyte development and metabolism has not been fully studied. We show here that genetic ablation of Sin1, an essential component of mTORC2, in T lineage cells results in severely impaired thymocyte development at the CD4-CD8- double negative (DN) stages but not at the CD4+CD8+ double positive (DP) or later stages. Notably, Sin1-deficient DN thymocytes show markedly reduced proliferation and glycolysis. Importantly, we discover that the M2 isoform of pyruvate kinase (PKM2) is a novel and crucial Sin1 effector in promoting DN thymocyte development and metabolism. At the molecular level, we show that Sin1-mTORC2 controls PKM2 expression through an AKT-dependent PPAR-γ nuclear translocation. Together, our study unravels a novel mTORC2-PPAR-γ-PKM2 pathway in immune-metabolic regulation of early thymocyte development.
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Affiliation(s)
- Xinxing Ouyang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuheng Han
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guojun Qu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Man Li
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ningbo Wu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hongzhi Liu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Omotooke Arojo
- Department of Immunobiology and the Vascular Biology and Therapeutics Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Hongxiang Sun
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaobo Liu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dou Liu
- Department of Immunobiology and the Vascular Biology and Therapeutics Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Lei Chen
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiang Zou
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bing Su
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunobiology and the Vascular Biology and Therapeutics Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
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Caron A, Briscoe DM, Richard D, Laplante M. DEPTOR at the Nexus of Cancer, Metabolism, and Immunity. Physiol Rev 2018; 98:1765-1803. [PMID: 29897294 DOI: 10.1152/physrev.00064.2017] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
DEP domain-containing mechanistic target of rapamycin (mTOR)-interacting protein (DEPTOR) is an important modulator of mTOR, a kinase at the center of two important protein complexes named mTORC1 and mTORC2. These highly studied complexes play essential roles in regulating growth, metabolism, and immunity in response to mitogens, nutrients, and cytokines. Defects in mTOR signaling have been associated with the development of many diseases, including cancer and diabetes, and approaches aiming at modulating mTOR activity are envisioned as an attractive strategy to improve human health. DEPTOR interaction with mTOR represses its kinase activity and rewires the mTOR signaling pathway. Over the last years, several studies have revealed key roles for DEPTOR in numerous biological and pathological processes. Here, we provide the current state of the knowledge regarding the cellular and physiological functions of DEPTOR by focusing on its impact on the mTOR pathway and its role in promoting health and disease.
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Affiliation(s)
- Alexandre Caron
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
| | - David M Briscoe
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
| | - Denis Richard
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
| | - Mathieu Laplante
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
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23
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Gui Y, Li J, Lu Q, Feng Y, Wang M, He W, Yang J, Dai C. Yap/Taz mediates mTORC2-stimulated fibroblast activation and kidney fibrosis. J Biol Chem 2018; 293:16364-16375. [PMID: 30154246 DOI: 10.1074/jbc.ra118.004073] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 08/07/2018] [Indexed: 11/06/2022] Open
Abstract
Our previously published study demonstrated that mammalian target of rapamycin complex 2 (mTORC2) signaling mediates TGFβ1-induced fibroblast activation. However, the underlying mechanisms for mTORC2 in stimulating fibroblast activation remain poorly understood. Here, we found that TGFβ1 could stimulate mTORC2 and Yap/Taz activation in NRK-49F cells. Blocking either mTORC2 or Yap/Taz signaling diminished TGFβ1-induced fibroblast activation. In addition, blockade of mTORC2 could down-regulate the expression of Yap/Taz, connective tissue growth factor (CTGF), and ankyrin repeat domain 1 (ANKRD1). Overexpression of constitutively active Taz (Taz-S89A) could restore fibroblast activation suppressed by PP242, an mTOR kinase inhibitor in NRK-49F cells. In mouse kidneys with unilateral ureter obstructive (UUO) nephropathy, both mTORC2 and Yap/Taz were activated in the interstitial myofibroblasts. Ablation of Rictor in fibroblasts/pericytes or blockade of mTOR signaling with PP242 attenuated Yap/Taz activation and UUO nephropathy in mice. Together, this study uncovers that targeting mTORC2 retards fibroblast activation and kidney fibrosis through suppressing Yap/Taz activation.
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Affiliation(s)
- Yuan Gui
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Jianzhong Li
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Qingmiao Lu
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Ye Feng
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Mingjie Wang
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Weichun He
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Junwei Yang
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
| | - Chunsun Dai
- From the Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003, China
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Role of mTOR in Glucose and Lipid Metabolism. Int J Mol Sci 2018; 19:ijms19072043. [PMID: 30011848 PMCID: PMC6073766 DOI: 10.3390/ijms19072043] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 02/06/2023] Open
Abstract
The mammalian target of rapamycin, mTOR is the master regulator of a cell’s growth and metabolic state in response to nutrients, growth factors and many extracellular cues. Its dysregulation leads to a number of metabolic pathological conditions, including obesity and type 2 diabetes. Here, we review recent findings on the role of mTOR in major metabolic organs, such as adipose tissues, liver, muscle, pancreas and brain. And their potentials as the mTOR related pharmacological targets will be also discussed.
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25
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Who does TORC2 talk to? Biochem J 2018; 475:1721-1738. [PMID: 29794170 DOI: 10.1042/bcj20180130] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 04/19/2018] [Accepted: 04/23/2018] [Indexed: 12/21/2022]
Abstract
The target of rapamycin (TOR) is a protein kinase that, by forming complexes with partner proteins, governs diverse cellular signalling networks to regulate a wide range of processes. TOR thus plays central roles in maintaining normal cellular functions and, when dysregulated, in diverse diseases. TOR forms two distinct types of multiprotein complexes (TOR complexes 1 and 2, TORC1 and TORC2). TORC1 and TORC2 differ in their composition, their control and their substrates, so that they play quite distinct roles in cellular physiology. Much effort has been focused on deciphering the detailed regulatory links within the TOR pathways and the structure and control of TOR complexes. In this review, we summarize recent advances in understanding mammalian (m) TORC2, its structure, its regulation, and its substrates, which link TORC2 signalling to the control of cell functions. It is now clear that TORC2 regulates several aspects of cell metabolism, including lipogenesis and glucose transport. It also regulates gene transcription, the cytoskeleton, and the activity of a subset of other protein kinases.
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26
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Pinhel MADS, Nicoletti CF, Noronha NY, de Oliveira BAP, Cortes-Oliveira C, Salgado W, da Silva WA, Souza DRS, Marchini JS, Nonino CB. Mammalian target of rapamycin complex 2 signaling in obese women changes after bariatric surgery. Nutrition 2018; 54:94-99. [PMID: 29778908 DOI: 10.1016/j.nut.2018.02.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 01/29/2018] [Accepted: 02/09/2018] [Indexed: 02/06/2023]
Abstract
OBJECTIVES After bariatric surgery, modifications to signaling pathway networks including those of the metabolic regulator called mammalian or mechanistic target of rapamycin (mTOR) may lead to molecular alterations related to energy source availability, systemic nutrients, and catabolic and anabolic cellular processes. This study aimed to identify gene expression changes with regard to the mTOR complex 2 subunit signaling pathway in obese patients before and after bariatric surgery. METHODS The experimental group included 13 obese women who were examined before (preoperative) and 6 mo after (postoperative) Roux-en-Y gastric bypass (RYGB) surgery. The control group included nine apparently eutrophic women matched by age and without any other metabolic diseases (i.e., no diabetes and no liver or kidney diseases). Peripheral blood mononuclear cell samples were collected for RNA extraction and subsequent microarray analysis. RESULTS After this methodological procedure, we identified 47 000 differentially expressed genes. A subsequent bioinformatic analysis showed that three diferentially expressed genes (rapamycin-insensitive companion of mTOR [RICTOR], phosphoinositide-3-kinase regulatory subunit 1 [PIK3 R1], and hypoxia inducible factor 1 alpha subunit 1A [HIF1 A]) participated in the mTOR signaling pathway. Real-time quantitative polymerase chain reaction revealed that RICTOR, PIK3 R1, and HIF1 A were upregulated 6 mo after RYGB surgery (P <0.05). In addition, patients in the experimental group lost weight significantly and presented significant improvement in biochemical/metabolic variables. CONCLUSIONS The weight loss that was induced by RYGB surgery alters the mTOR signaling pathway and specifically the mTOR complex 2 subunit. The increased expression of genes that act in this pathway such as RICTOR, PIK3 R1, and HIF1 A reflects the induced weight loss and improved metabolic indicators (e.g., insulin resistance and lipolysis) that are evidenced in this study.
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Affiliation(s)
- Marcela Augusta de Souza Pinhel
- Department of Internal Medicine, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil; Department of Biochemistry and Molecular Biology, Sao Jose do Rio Preto Medical School, Sao Paulo, Brazil
| | - Carolina Ferreira Nicoletti
- Department of Internal Medicine, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | - Natalia Yumi Noronha
- Department of Internal Medicine, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | | | - Cristiana Cortes-Oliveira
- Department of Internal Medicine, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | - Wilson Salgado
- Department of Surgery and Anatomy, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | - Wilson Araujo da Silva
- Department of Genetics, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | - Doroteia Rossi Silva Souza
- Department of Biochemistry and Molecular Biology, Sao Jose do Rio Preto Medical School, Sao Paulo, Brazil
| | - Julio Sergio Marchini
- Department of Internal Medicine, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil
| | - Carla Barbosa Nonino
- Department of Internal Medicine, Ribeirao Preto Medical School of University of Sao Paulo, Sao Paulo, Brazil.
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27
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mTORC2 Signaling: A Path for Pancreatic β Cell's Growth and Function. J Mol Biol 2018; 430:904-918. [PMID: 29481838 DOI: 10.1016/j.jmb.2018.02.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/14/2018] [Accepted: 02/14/2018] [Indexed: 12/16/2022]
Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway is an evolutionary conserved pathway that senses signals from nutrients and growth factors to regulate cell growth, metabolism and survival. mTOR acts in two biochemically and functionally distinct complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which differ in terms of regulatory mechanisms, substrate specificity and functional outputs. While mTORC1 signaling has been extensively studied in islet/β-cell biology, recent findings demonstrate a distinct role for mTORC2 in the regulation of pancreatic β-cell function and mass. mTORC2, a key component of the growth factor receptor signaling, is declined in β cells under diabetogenic conditions and in pancreatic islets from patients with type 2 diabetes. β cell-selective mTORC2 inactivation leads to glucose intolerance and acceleration of diabetes as a result of reduced β-cell mass, proliferation and impaired glucose-stimulated insulin secretion. Thereby, many mTORC2 targets, such as AKT, PKC, FOXO1, MST1 and cell cycle regulators, play an important role in β-cell survival and function. This indicates mTORC2 as important pathway for the maintenance of β-cell homeostasis, particularly to sustain proper β-cell compensatory response in the presence of nutrient overload and metabolic demand. This review summarizes recent emerging advances on the contribution of mTORC2 and its associated signaling on the regulation of glucose metabolism and functional β-cell mass under physiological and pathophysiological conditions in type 2 diabetes.
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28
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McElroy SL, Winham SJ, Cuellar-Barboza AB, Colby CL, Ho AMC, Sicotte H, Larrabee BR, Crow S, Frye MA, Biernacka JM. Bipolar disorder with binge eating behavior: a genome-wide association study implicates PRR5-ARHGAP8. Transl Psychiatry 2018; 8:40. [PMID: 29391396 PMCID: PMC5804024 DOI: 10.1038/s41398-017-0085-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/06/2017] [Accepted: 09/13/2017] [Indexed: 12/30/2022] Open
Abstract
Bipolar disorder (BD) is associated with binge eating behavior (BE), and both conditions are heritable. Previously, using data from the Genetic Association Information Network (GAIN) study of BD, we performed genome-wide association (GWA) analyses of BD with BE comorbidity. Here, utilizing data from the Mayo Clinic BD Biobank (969 BD cases, 777 controls), we performed a GWA analysis of a BD subtype defined by BE, and case-only analysis comparing BD subjects with and without BE. We then performed a meta-analysis of the Mayo and GAIN results. The meta-analysis provided genome-wide significant evidence of association between single nucleotide polymorphisms (SNPs) in PRR5-ARHGAP8 and BE in BD cases (rs726170 OR = 1.91, P = 3.05E-08). In the meta-analysis comparing cases with BD with comorbid BE vs. non-BD controls, a genome-wide significant association was observed at SNP rs111940429 in an intergenic region near PPP1R2P5 (p = 1.21E-08). PRR5-ARHGAP8 is a read-through transcript resulting in a fusion protein of PRR5 and ARHGAP8. PRR5 encodes a subunit of mTORC2, a serine/threonine kinase that participates in food intake regulation, while ARHGAP8 encodes a member of the RhoGAP family of proteins that mediate cross-talk between Rho GTPases and other signaling pathways. Without BE information in controls, it is not possible to determine whether the observed association reflects a risk factor for BE in general, risk for BE in individuals with BD, or risk of a subtype of BD with BE. The effect of PRR5-ARHGAP8 on BE risk thus warrants further investigation.
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Affiliation(s)
- Susan L McElroy
- Lindner Center of HOPE, Mason, OH, USA
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA
| | - Stacey J Winham
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | | | - Colin L Colby
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Ada Man-Choi Ho
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Hugues Sicotte
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Beth R Larrabee
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Scott Crow
- University of Minnesota, Minneapolis, MN, USA
| | - Mark A Frye
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, USA
| | - Joanna M Biernacka
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA.
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, USA.
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29
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Xie Y, Cui C, Nie A, Wang Y, Ni Q, Liu Y, Yin Q, Zhang H, Li Y, Wang Q, Gu Y, Ning G. The mTORC2/PKC pathway sustains compensatory insulin secretion of pancreatic β cells in response to metabolic stress. Biochim Biophys Acta Gen Subj 2017; 1861:2039-2047. [DOI: 10.1016/j.bbagen.2017.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/31/2017] [Accepted: 04/18/2017] [Indexed: 12/24/2022]
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30
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Contribution of adaptive thermogenesis to the hypothalamic regulation of energy balance. Biochem J 2016; 473:4063-4082. [DOI: 10.1042/bcj20160012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 08/13/2016] [Accepted: 08/30/2016] [Indexed: 12/12/2022]
Abstract
Obesity and its related disorders are among the most pervasive diseases in contemporary societies, and there is an urgent need for new therapies and preventive approaches. Given (i) our poor social capacity to correct unhealthy habits, and (ii) our evolutionarily genetic predisposition to store excess energy as fat, the current environment of caloric surplus makes the treatment of obesity extremely difficult. During the last few decades, an increasing number of methodological approaches have increased our knowledge of the neuroanatomical basis of the control of energy balance. Compelling evidence underlines the role of the hypothalamus as a homeostatic integrator of metabolic information and its ability to adjust energy balance. A greater understanding of the neural basis of the hypothalamic regulation of energy balance might indeed pave the way for new therapeutic targets. In this regard, it has been shown that several important peripheral signals, such as leptin, thyroid hormones, oestrogens and bone morphogenetic protein 8B, converge on common energy sensors, such as AMP-activated protein kinase to modulate sympathetic tone on brown adipose tissue. This knowledge may open new ways to counteract the chronic imbalance underlying obesity. Here, we review the current state of the art on the role of hypothalamus in the regulation of energy balance with particular focus on thermogenesis.
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31
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Caron A, Richard D. Neuronal systems and circuits involved in the control of food intake and adaptive thermogenesis. Ann N Y Acad Sci 2016; 1391:35-53. [PMID: 27768821 DOI: 10.1111/nyas.13263] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 08/18/2016] [Accepted: 08/24/2016] [Indexed: 12/27/2022]
Abstract
With the still-growing prevalence of obesity worldwide, major efforts are made to understand the various behavioral, environmental, and genetic factors that promote excess fat gain. Obesity results from an imbalance between energy intake and energy expenditure, which emphasizes the importance of deciphering the mechanisms behind energy balance regulation to understand its physiopathology. The control of energy balance is assured by brain systems/circuits capable of generating adequate ingestive and thermogenic responses to maintain the stability of energy reserves, which implies a proper integration of the homeostatic signals that inform about the status of the energy stores. In this article, we overview the organization and functionality of key neuronal circuits or pathways involved in the control of food intake and energy expenditure. We review the role of the corticolimbic (executive and reward) and autonomic systems that integrate their activities to regulate energy balance. We also describe the mechanisms and pathways whereby homeostatic sensing is achieved in response to variations of homeostatic hormones, such as leptin, insulin, and ghrelin, while putting some emphasis on the prominent importance of the mechanistic target of the rapamycin signaling pathway in coordinating the homeostatic sensing process.
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Affiliation(s)
- Alexandre Caron
- Institut Universitaire de Cardiologie et de Pneumologie de Quebec and Faculty of Medicine, Department of Medicine, Université Laval, Quebec City, Quebec, Canada
| | - Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Quebec and Faculty of Medicine, Department of Medicine, Université Laval, Quebec City, Quebec, Canada
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32
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Liu DY, Zhao HM. Axis of immune response and energy metabolism mediated by Notch/mTOR signaling pathway: Pivotal mechanism of traditional Chinese medicine for preventing inflammatory bowel disease. Shijie Huaren Xiaohua Zazhi 2016; 24:2617-2624. [DOI: 10.11569/wcjd.v24.i17.2617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inflammatory bowel disease (IBD) is a kind of worldwide refractory disease with a high recurrence rate. However, traditional Chinese medicine for IBD is associated with a better therapeutic effect and a lower recurrence rate, although the mechanism is still unclear. It is known that the Notch signaling pathway interacts with mTOR and regulates the body's immune level and cell energy, which is closely related with morbidity of IBD. These hint that axis of immune response and energy metabolism mediated by the Notch/mTOR signaling pathway is possibly a pivotal mechanism for traditional Chinese medicine to prevent IBD.
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The Mechanistic Target of Rapamycin: The Grand ConducTOR of Metabolism and Aging. Cell Metab 2016; 23:990-1003. [PMID: 27304501 PMCID: PMC4910876 DOI: 10.1016/j.cmet.2016.05.009] [Citation(s) in RCA: 371] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/17/2016] [Accepted: 05/24/2016] [Indexed: 12/21/2022]
Abstract
Since the discovery that rapamycin, a small molecule inhibitor of the protein kinase mTOR (mechanistic target of rapamycin), can extend the lifespan of model organisms including mice, interest in understanding the physiological role and molecular targets of this pathway has surged. While mTOR was already well known as a regulator of growth and protein translation, it is now clear that mTOR functions as a central coordinator of organismal metabolism in response to both environmental and hormonal signals. This review discusses recent developments in our understanding of how mTOR signaling is regulated by nutrients and the role of the mTOR signaling pathway in key metabolic tissues. Finally, we discuss the molecular basis for the negative metabolic side effects associated with rapamycin treatment, which may serve as barriers to the adoption of rapamycin or similar compounds for the treatment of diseases of aging and metabolism.
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34
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Hu F, Xu Y, Liu F. Hypothalamic roles of mTOR complex I: integration of nutrient and hormone signals to regulate energy homeostasis. Am J Physiol Endocrinol Metab 2016; 310:E994-E1002. [PMID: 27166282 PMCID: PMC4935144 DOI: 10.1152/ajpendo.00121.2016] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/06/2016] [Indexed: 12/31/2022]
Abstract
Mammalian or mechanistic target of rapamycin (mTOR) senses nutrient, energy, and hormone signals to regulate metabolism and energy homeostasis. mTOR activity in the hypothalamus, which is associated with changes in energy status, plays a critical role in the regulation of food intake and body weight. mTOR integrates signals from a variety of "energy balancing" hormones such as leptin, insulin, and ghrelin, although its action varies in response to these distinct hormonal stimuli as well as across different neuronal populations. In this review, we summarize and highlight recent findings regarding the functional roles of mTOR complex 1 (mTORC1) in the hypothalamus specifically in its regulation of body weight, energy expenditure, and glucose/lipid homeostasis. Understanding the role and underlying mechanisms behind mTOR-related signaling in the brain will undoubtedly pave new avenues for future therapeutics and interventions that can combat obesity, insulin resistance, and diabetes.
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Affiliation(s)
- Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China;
| | - Yong Xu
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas; and
| | - Feng Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China; Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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Arriola Apelo SI, Lamming DW. Rapamycin: An InhibiTOR of Aging Emerges From the Soil of Easter Island. J Gerontol A Biol Sci Med Sci 2016; 71:841-9. [PMID: 27208895 DOI: 10.1093/gerona/glw090] [Citation(s) in RCA: 161] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/27/2016] [Indexed: 12/27/2022] Open
Abstract
Rapamycin (sirolimus) is a macrolide immunosuppressant that inhibits the mechanistic target of rapamycin (mTOR) protein kinase and extends lifespan in model organisms including mice. Although rapamycin is an FDA-approved drug for select indications, a diverse set of negative side effects may preclude its wide-scale deployment as an antiaging therapy. mTOR forms two different protein complexes, mTORC1 and mTORC2; the former is acutely sensitive to rapamycin whereas the latter is only chronically sensitive to rapamycin in vivo. Over the past decade, it has become clear that although genetic and pharmacological inhibition of mTORC1 extends lifespan and delays aging, inhibition of mTORC2 has negative effects on mammalian health and longevity and is responsible for many of the negative side effects of rapamycin. In this review, we discuss recent advances in understanding the molecular and physiological effects of rapamycin treatment, and we discuss how the use of alternative rapamycin treatment regimens or rapamycin analogs has the potential to mitigate the deleterious side effects of rapamycin treatment by more specifically targeting mTORC1. Although the side effects of rapamycin are still of significant concern, rapid progress is being made in realizing the revolutionary potential of rapamycin-based therapies for the treatment of diseases of aging.
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Affiliation(s)
- Sebastian I Arriola Apelo
- Department of Medicine, University of Wisconsin-Madison and William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin
| | - Dudley W Lamming
- Department of Medicine, University of Wisconsin-Madison and William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin.
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Caron A, Labbé SM, Mouchiroud M, Huard R, Lanfray D, Richard D, Laplante M. DEPTOR in POMC neurons affects liver metabolism but is dispensable for the regulation of energy balance. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1322-31. [PMID: 27097662 DOI: 10.1152/ajpregu.00549.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 04/18/2016] [Indexed: 11/22/2022]
Abstract
We have recently demonstrated that specific overexpression of DEP-domain containing mTOR-interacting protein (DEPTOR) in the mediobasal hypothalamus (MBH) protects mice against high-fat diet-induced obesity, revealing DEPTOR as a significant contributor to energy balance regulation. On the basis of evidence that DEPTOR is expressed in the proopiomelanocortin (POMC) neurons of the MBH, the present study aimed to investigate whether these neurons mediate the metabolic effects of DEPTOR. Here, we report that specific DEPTOR overexpression in POMC neurons does not recapitulate any of the phenotypes observed when the protein was overexpressed in the MBH. Unlike the previous model, mice overexpressing DEPTOR only in POMC neurons 1) did not show differences in feeding behavior, 2) did not exhibit changes in locomotion activity and oxygen consumption, 3) did not show an improvement in systemic glucose metabolism, and 4) were not resistant to high-fat diet-induced obesity. These results support the idea that other neuronal populations are responsible for these phenotypes. Nonetheless, we observed a mild elevation in fasting blood glucose, insulin resistance, and alterations in liver glucose and lipid homeostasis in mice overexpressing DEPTOR in POMC neurons. Taken together, these results show that DEPTOR overexpression in POMC neurons does not affect energy balance regulation but could modulate metabolism through a brain-liver connection.
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Affiliation(s)
- Alexandre Caron
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Sébastien M Labbé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Mathilde Mouchiroud
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Renaud Huard
- Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Damien Lanfray
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Mathieu Laplante
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
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Vernia S, Morel C, Madara JC, Cavanagh-Kyros J, Barrett T, Chase K, Kennedy NJ, Jung DY, Kim JK, Aronin N, Flavell RA, Lowell BB, Davis RJ. Excitatory transmission onto AgRP neurons is regulated by cJun NH2-terminal kinase 3 in response to metabolic stress. eLife 2016; 5:e10031. [PMID: 26910012 PMCID: PMC4798947 DOI: 10.7554/elife.10031] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 02/22/2016] [Indexed: 11/13/2022] Open
Abstract
The cJun NH2-terminal kinase (JNK) signaling pathway is implicated in the response to metabolic stress. Indeed, it is established that the ubiquitously expressed JNK1 and JNK2 isoforms regulate energy expenditure and insulin resistance. However, the role of the neuron-specific isoform JNK3 is unclear. Here we demonstrate that JNK3 deficiency causes hyperphagia selectively in high fat diet (HFD)-fed mice. JNK3 deficiency in neurons that express the leptin receptor LEPRb was sufficient to cause HFD-dependent hyperphagia. Studies of sub-groups of leptin-responsive neurons demonstrated that JNK3 deficiency in AgRP neurons, but not POMC neurons, was sufficient to cause the hyperphagic response. These effects of JNK3 deficiency were associated with enhanced excitatory signaling by AgRP neurons in HFD-fed mice. JNK3 therefore provides a mechanism that contributes to homeostatic regulation of energy balance in response to metabolic stress. DOI:http://dx.doi.org/10.7554/eLife.10031.001 Consuming the right amount of food is important for health. Eating too little for a long time causes damage to organs, and overeating can cause harm as well, in the form of conditions such as obesity and type 2 diabetes. Several signaling molecules and brain regions are linked to controlling food consumption and ensuring the body receives the correct amount of nutrients to fuel its activities. Previous studies have found that two proteins called JNK1 and JNK2, which are found in most tissues of the body, can reduce how much energy cells use. This can trigger insulin resistance and fat accumulation, and so suggests that blocking the activity of these proteins may help to treat type 2 diabetes and obesity. However, the role of another JNK protein – JNK3, which is mostly found in the brain – was not known. Now, Vernia, Morel et al. have investigated the role of JNK3 in metabolism. It was found that JNK3 reduced the amount of food consumed by mice provided with a cafeteria (high fat) diet. Mice that lacked JNK3 ate far more food and gained more weight on a high fat diet than normal mice. However, JNK3 played no role in food consumption when mice were fed a standard chow diet. Treating normal mice with leptin – an appetite-suppressing hormone – caused them to lose weight, but did not affect mice that lacked JNK3. Examining the brains of the mice revealed that in normal mice, JNK3 in a specific sub-population of neurons decreases the production of proteins that promote eating. However, the proteins continued to be produced in mice that lacked JNK3, encouraging overeating. Overall, the results suggest that blocking the activity of all the JNK proteins will not help treat obesity and diabetes as shutting down JNK3 could encourage overeating. Therefore, future investigation into treatments for these conditions should focus on drugs that specifically target JNK1 and JNK2, and not JNK3. DOI:http://dx.doi.org/10.7554/eLife.10031.002
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Affiliation(s)
- Santiago Vernia
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Caroline Morel
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Joseph C Madara
- Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, United States.,Harvard Medical School, Boston, United States
| | - Julie Cavanagh-Kyros
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States.,Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, United States
| | - Tamera Barrett
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States.,Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, United States
| | - Kathryn Chase
- Department of Medicine, Division of Endocrinology, University of Massachusetts Medical School, Worcester, United States
| | - Norman J Kennedy
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Dae Young Jung
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Jason K Kim
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States.,Department of Medicine, Division of Endocrinology, University of Massachusetts Medical School, Worcester, United States
| | - Neil Aronin
- Department of Medicine, Division of Endocrinology, University of Massachusetts Medical School, Worcester, United States
| | - Richard A Flavell
- Department of Immunobiology, Yale University School of Medicine, New Haven, United States.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Bradford B Lowell
- Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, United States.,Harvard Medical School, Boston, United States
| | - Roger J Davis
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States.,Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, United States
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Mediobasal hypothalamic overexpression of DEPTOR protects against high-fat diet-induced obesity. Mol Metab 2015; 5:102-112. [PMID: 26909318 PMCID: PMC4735664 DOI: 10.1016/j.molmet.2015.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 11/18/2015] [Accepted: 11/25/2015] [Indexed: 01/29/2023] Open
Abstract
Background/Objective The mechanistic target of rapamycin (mTOR) is a serine–threonine kinase that functions into distinct protein complexes (mTORC1 and mTORC2) that regulate energy homeostasis. DEP-domain containing mTOR-interacting protein (DEPTOR) is part of these complexes and is known to dampen mTORC1 function, consequently reducing mTORC1 negative feedbacks and promoting insulin signaling and Akt/PKB activation in several models. Recently, we observed that DEPTOR is expressed in several structures of the brain including the mediobasal hypothalamus (MBH), a region that regulates energy balance. Whether DEPTOR in the MBH plays a functional role in regulating energy balance and hypothalamic insulin signaling has never been tested. Methods We have generated a novel conditional transgenic mouse model based on the Cre-LoxP system allowing targeted overexpression of DEPTOR. Mice overexpressing DEPTOR in the MBH were subjected to a metabolic phenotyping and MBH insulin signaling was evaluated. Results We first report that systemic (brain and periphery) overexpression of DEPTOR prevents high-fat diet-induced obesity, improves glucose metabolism and protects against hepatic steatosis. These phenotypes were associated with a reduction in food intake and feed efficiency and an elevation in oxygen consumption. Strikingly, specific overexpression of DEPTOR in the MBH completely recapitulated these phenotypes. DEPTOR overexpression was associated with an increase in hypothalamic insulin signaling, as illustrated by elevated Akt/PKB activation. Conclusion Altogether, these results support a role for MBH DEPTOR in the regulation of energy balance and metabolism. Systemic (brain and peripheral) overexpression of DEPTOR promotes activity and improves glucose homeostasis. Systemic (brain and peripheral) overexpression of DEPTOR protects againts high-fat diet-induced obesity and metabolic alterations. Deptor is widely expressed in the mouse brain, with a high expression in the mediobasal hypothalamus (MBH), a key region of the brain that regulates energy balance. MBH-specific DEPTOR overexpression improves glucose metabolism and protects mice against obesity. MBH-specific DEPTOR overexpression promotes hypothalamic Akt/PKB signaling.
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39
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Labbé SM, Caron A, Lanfray D, Monge-Rofarello B, Bartness TJ, Richard D. Hypothalamic control of brown adipose tissue thermogenesis. Front Syst Neurosci 2015; 9:150. [PMID: 26578907 PMCID: PMC4630288 DOI: 10.3389/fnsys.2015.00150] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 10/20/2015] [Indexed: 12/21/2022] Open
Abstract
It has long been known, in large part from animal studies, that the control of brown adipose tissue (BAT) thermogenesis is insured by the central nervous system (CNS), which integrates several stimuli in order to control BAT activation through the sympathetic nervous system (SNS). SNS-mediated BAT activity is governed by diverse neurons found in brain structures involved in homeostatic regulations and whose activity is modulated by various factors including oscillations of energy fluxes. The characterization of these neurons has always represented a challenging issue. The available literature suggests that the neuronal circuits controlling BAT thermogenesis are largely part of an autonomic circuitry involving the hypothalamus, brainstem and the SNS efferent neurons. In the present review, we recapitulate the latest progresses in regards to the hypothalamic regulation of BAT metabolism. We briefly addressed the role of the thermoregulatory pathway and its interactions with the energy balance systems in the control of thermogenesis. We also reviewed the involvement of the brain melanocortin and endocannabinoid systems as well as the emerging role of steroidogenic factor 1 (SF1) neurons in BAT thermogenesis. Finally, we examined the link existing between these systems and the homeostatic factors that modulate their activities.
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Affiliation(s)
- Sebastien M Labbé
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Alexandre Caron
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Damien Lanfray
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Boris Monge-Rofarello
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Timothy J Bartness
- Department of Biology, Center for Obesity Reversal (COR), Georgia State University Atlanta, GA, USA
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
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40
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Abstract
TOR (target of rapamycin) and its mammalian ortholog mTOR have been discovered in an effort to understand the mechanisms of action of the immunosuppressant drug rapamycin extracted from a bacterium of the Easter Island (Rapa Nui) soil. mTOR is a serine/threonine kinase found in two functionally distinct complexes, mTORC1 and mTORC2, which are differentially regulated by a great number of nutrients such as glucose and amino acids, energy (oxygen and ATP/AMP content), growth factors, hormones, and neurotransmitters. mTOR controls many basic cellular functions such as protein synthesis, energy metabolism, cell size, lipid metabolism, autophagy, mitochondria, and lysosome biogenesis. In addition, mTOR-controlled signaling pathways regulate many integrated physiological functions of the nervous system including neuronal development, synaptic plasticity, memory storage, and cognition. Thus it is not surprising that deregulation of mTOR signaling is associated with many neurological and psychiatric disorders. Preclinical and preliminary clinical studies indicate that inhibition of mTORC1 can be beneficial for some pathological conditions such as epilepsy, cognitive impairment, and brain tumors, whereas stimulation of mTORC1 (direct or indirect) can be beneficial for other pathologies such as depression or axonal growth and regeneration.
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Affiliation(s)
- Joël Bockaert
- Centre National de la Recherche Scientifique, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; Institut National de la Santé et de la Recherche Médicale U1191, Montpellier, France; and Université de Montpellier, UMR-5203, Montpellier, France
| | - Philippe Marin
- Centre National de la Recherche Scientifique, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; Institut National de la Santé et de la Recherche Médicale U1191, Montpellier, France; and Université de Montpellier, UMR-5203, Montpellier, France
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Singh BK, Sinha RA, Zhou J, Tripathi M, Ohba K, Wang ME, Astapova I, Ghosh S, Hollenberg AN, Gauthier K, Yen PM. Hepatic FOXO1 Target Genes Are Co-regulated by Thyroid Hormone via RICTOR Protein Deacetylation and MTORC2-AKT Protein Inhibition. J Biol Chem 2015; 291:198-214. [PMID: 26453307 DOI: 10.1074/jbc.m115.668673] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Indexed: 12/21/2022] Open
Abstract
MTORC2-AKT is a key regulator of carbohydrate metabolism and insulin signaling due to its effects on FOXO1 phosphorylation. Interestingly, both FOXO1 and thyroid hormone (TH) have similar effects on carbohydrate and energy metabolism as well as overlapping transcriptional regulation of many target genes. Currently, little is known about the regulation of MTORC2-AKT or FOXO1 by TH. Accordingly, we performed hepatic transcriptome profiling in mice after FOXO1 knockdown in the absence or presence of TH, and we compared these results with hepatic FOXO1 and THRB1 (TRβ1) ChIP-Seq data. We identified a subset of TH-stimulated FOXO1 target genes that required co-regulation by FOXO1 and TH. TH activation of FOXO1 was directly linked to an increase in SIRT1-MTORC2 interaction and RICTOR deacetylation. This, in turn, led to decreased AKT and FOXO1 phosphorylation. Moreover, TH increased FOXO1 nuclear localization, DNA binding, and target gene transcription by reducing AKT-dependent FOXO1 phosphorylation in a THRB1-dependent manner. These events were associated with TH-mediated oxidative phosphorylation and NAD(+) production and suggested that downstream metabolic effects by TH can post-translationally activate other transcription factors. Our results showed that RICTOR/MTORC2-AKT can integrate convergent hormonal and metabolic signals to provide coordinated and sensitive regulation of hepatic FOXO1-target gene expression.
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Affiliation(s)
- Brijesh K Singh
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and
| | - Rohit A Sinha
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and
| | - Jin Zhou
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and
| | - Madhulika Tripathi
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and the Stroke Trial Unit, National Neuroscience Institute Singapore, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore
| | - Kenji Ohba
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and
| | - Mu-En Wang
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and the Department of Animal Science and Technology, National Taiwan University, Taipei 10617, Taiwan
| | - Inna Astapova
- the Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, and
| | - Sujoy Ghosh
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and Centre for Computational Biology, Duke-National University of Singapore Graduate Medical School, Singapore 169857, Singapore
| | - Anthony N Hollenberg
- the Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, and
| | - Karine Gauthier
- the Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, 46, Allée d'Italie 69364, Lyon Cedex 07, France
| | - Paul M Yen
- From the Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program and
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Impaired mTORC2 signaling in catecholaminergic neurons exaggerates high fat diet-induced hyperphagia. Heliyon 2015; 1:e00025. [PMID: 27441217 PMCID: PMC4939830 DOI: 10.1016/j.heliyon.2015.e00025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 08/24/2015] [Accepted: 08/24/2015] [Indexed: 01/22/2023] Open
Abstract
Objective Food intake is highly regulated by central homeostatic and hedonic mechanisms in response to peripheral and environmental cues. Neutral energy balance stems from proper integration of homeostatic signals with those “sensing” the rewarding properties of food. Impairments in brain insulin signaling causes dysregulation of feeding behaviors and, as a consequence, hyperphagia. Here, we sought to determine how the mammalian target of rapamycin complex 2 (mTORC2), a complex involved in insulin signaling, influences high fat feeding. Methods Rictor is a subunit of mTORC2, and its genetic deletion impairs mTORC2 activity. We used Cre-LoxP technology to delete Rictorin tyrosine hydroxylase (TH) expressing neurons (TH Rictor KO). We assessed food intake, body weight, body composition and DA dependent behaviors. Results TH Rictor KO mice display a high-fat diet specific hyperphagia, yet, when on low-fat diet, their food intake is indistinguishable from controls. Consistently, TH Rictor KO become obese only while consuming high-fat diet. This is paralleled by reduced brain DA content, and disruption of DA dependent behaviors including increased novelty-induced hyperactivity and exaggerated response to the psycho stimulant amphetamine (AMPH). Conclusions Our data support a model in which mTORC2 signaling within catecholaminergic neurons constrains consumption of a high-fat diet, while disruption causes high-fat diet-specific exaggerated hyperphagia. In parallel, impaired mTORC2 signaling leads to aberrant striatal DA neurotransmission, which has been associated with obesity in human and animal models, as well as with escalating substance abuse. These data suggest that defects localized to the catecholaminergic pathways are capable of overriding homeostatic circuits, leading to obesity, metabolic impairment, and aberrant DA-dependent behaviors.
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mTORC1 signaling in Agrp neurons mediates circadian expression of Agrp and NPY but is dispensable for regulation of feeding behavior. Biochem Biophys Res Commun 2015; 464:480-6. [DOI: 10.1016/j.bbrc.2015.06.161] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 06/26/2015] [Indexed: 02/04/2023]
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Abstract
Obesity ensues from an imbalance between energy intake and expenditure that results from gene-environment interactions, which favour a positive energy balance. A society that promotes unhealthy food and encourages sedentary lifestyle (that is, an obesogenic environment) has become a major contributory factor in excess fat deposition in individuals predisposed to obesity. Energy homeostasis relies upon control of energy intake as well as expenditure, which is in part determined by the themogenesis of brown adipose tissue and mediated by the sympathetic nervous system. Several areas of the brain that constitute cognitive and autonomic brain systems, which in turn form networks involved in the control of appetite and thermogenesis, also contribute to energy homeostasis. These networks include the dopamine mesolimbic circuit, as well as the opioid, endocannabinoid and melanocortin systems. The activity of these networks is modulated by peripheral factors such as hormones derived from adipose tissue and the gut, which access the brain via the circulation and neuronal signalling pathways to inform the central nervous system about energy balance and nutritional status. In this Review, I focus on the determinants of energy homeostasis that have emerged as prominent factors relevant to obesity.
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Affiliation(s)
- Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, 2725 Chemin Sainte-Foy, Québec, QC G1V 4G5, Canada
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45
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Rictor/mTORC2 signaling mediates TGFβ1-induced fibroblast activation and kidney fibrosis. Kidney Int 2015; 88:515-27. [PMID: 25970154 PMCID: PMC4558569 DOI: 10.1038/ki.2015.119] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 02/23/2015] [Accepted: 02/26/2015] [Indexed: 02/06/2023]
Abstract
The mammalian target of rapamycin (mTOR) was recently identified in two structurally distinct multiprotein complexes: mTORC1 and mTORC2. Previously, we found that Rictor/mTORC2 protects against cisplatin-induced acute kidney injury, but the role and mechanisms for Rictor/mTORC2 in TGFβ1-induced fibroblast activation and kidney fibrosis remains unknown. To study this, we initially treated NRK-49F cells with TGFβ1 and found that TGFβ1 could activate Rictor/mTORC2 signaling in cultured cells. Blocking Rictor/mTORC2 signaling with Rictor or Akt1 small interfering RNAs markedly inhibited TGFβ1-induced fibronection and α-smooth muscle actin expression. Ensuing western blotting or immunostaining results showed that Rictor/mTORC2 signaling was activated in kidney interstitial myofibroblasts from mice with unilateral ureteral obstruction. Next, a mouse model with fibroblast-specific deletion of Rictor was generated. These knockout mice were normal at birth and had no obvious kidney dysfunction or kidney morphological abnormality within 2 months of birth. Compared with control littermates, the kidneys of Rictor knockout mice developed less interstitial extracellular matrix deposition and inflammatory cell infiltration at 1 or 2 weeks after ureteral obstruction. Thus our study suggests that Rictor/mTORC2 signaling activation mediates TGFβ1-induced fibroblast activation and contributes to the development of kidney fibrosis. This may provide a therapeutic target for chronic kidney diseases.
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Haissaguerre M, Cota D. [Role of the mTOR pathway in the central regulation of energy balance]. Biol Aujourdhui 2015; 209:295-307. [PMID: 27021048 DOI: 10.1051/jbio/2016009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Indexed: 11/14/2022]
Abstract
The pathway of the mammalian (or mechanistic) target of rapamycin kinase (mTOR) responds to different signals such as nutrients and hormones and regulates many cellular functions as the synthesis of proteins and lipids, mitochondrial activity and the organization of the cytoskeleton. At the cellular level, mTOR forms two distinct complexes: mTORC1 and mTORC2. This review intends to summarize the various recent advances on the role of these two protein complexes in the central regulation of energy balance. mTORC1 activity modulates energy balance and metabolic responses by regulating the activity of neuronal populations, such as those located in the arcuate nucleus of the hypothalamus. Recent studies have shown that activity of the hypothalamic mTORC1 pathway varies according to cell and stimulus types, and that this signaling cascade regulates food intake and body weight in response to nutrients, such as leucine, and hormones like leptin, ghrelin and triiodothyronine. On the other hand, mTORC2 seems to be involved in the regulation of neuronal morphology and synaptic activity. However, its function in the central regulation of the energy balance is less known. Dysregulation of mTORC1 and mTORC2 is described in obesity and type 2 diabetes. Therefore, a better understanding of the molecular mechanisms involved in the regulation of energy balance by mTOR may lead to the identification of new therapeutic targets for the treatment of these metabolic pathologies.
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Affiliation(s)
- Magalie Haissaguerre
- Service Endocrinologie, Hôpital Haut Lévêque, CHU Bordeaux, 33600 Pessac, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33000 Bordeaux, France - Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33000 Bordeaux, France
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47
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Albert V, Hall MN. mTOR signaling in cellular and organismal energetics. Curr Opin Cell Biol 2014; 33:55-66. [PMID: 25554914 DOI: 10.1016/j.ceb.2014.12.001] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/20/2022]
Abstract
Mammalian TOR (mTOR) signaling controls growth, metabolism and energy homeostasis in a cell autonomous manner. Recent findings indicate that mTOR signaling in one tissue can also affect other organs thereby affecting whole body metabolism and energy homeostasis in a non-cell autonomous manner. It is thus not surprising that mTOR signaling mediates aging and is often deregulated in metabolic disorders, such as obesity, diabetes and cancer. This review discusses the regulation of cellular and whole body energy metabolism by mTOR, with particular focus on the non-cell autonomous function of mTOR.
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Affiliation(s)
- Verena Albert
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
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Haissaguerre M, Saucisse N, Cota D. Influence of mTOR in energy and metabolic homeostasis. Mol Cell Endocrinol 2014; 397:67-77. [PMID: 25109278 DOI: 10.1016/j.mce.2014.07.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 01/01/2023]
Abstract
The mechanistic (or mammalian) target of rapamycin couples a variety of different environmental signals, including nutrients and hormones, with the regulation of several energy-demanding cellular functions, spanning from protein and lipid synthesis to mitochondrial activity and cytoskeleton dynamics. mTOR forms two distinct protein complexes in cells, mTORC1 and mTORC2. This review focuses on recent advances made in understanding the roles played by these two complexes in the regulation of whole body metabolic homeostasis. Studies carried out in the past few years have shown that mTORC1 activity in the hypothalamus varies by cell and stimulus type, and that this complex is critically implicated in the regulation of food intake and body weight and in the central actions of both nutrients and hormones, such as leptin, ghrelin and triiodothyronine. As a regulator of cellular anabolic processes, mTORC1 activity in the periphery favors adipogenesis, lipogenesis, glucose uptake and beta-cell mass expansion. Much less is known about the function of mTORC2 in the hypothalamus, while in peripheral organs this second complex exerts roles strikingly similar to those described for mTORC1. Deregulation of mTORC1 and mTORC2 is associated with obesity, type 2 diabetes, cancer and neurodegenerative disorders. Insights on the exact relationship between mTORC1 and mTORC2 in the context of the regulation of metabolic homeostasis and on the specific molecular mechanisms engaged by these two complexes in such regulation may provide new avenues for therapy.
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Affiliation(s)
- Magalie Haissaguerre
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France
| | - Nicolas Saucisse
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France.
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Caron A, Baraboi ED, Laplante M, Richard D. DEP domain-containing mTOR-interacting protein in the rat brain: Distribution of expression and potential implication. J Comp Neurol 2014; 523:93-107. [DOI: 10.1002/cne.23668] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 08/15/2014] [Accepted: 08/18/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Alexandre Caron
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
| | - Elena-Dana Baraboi
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
| | - Mathieu Laplante
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
| | - Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
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Kleinert M, Sylow L, Fazakerley DJ, Krycer JR, Thomas KC, Oxbøll AJ, Jordy AB, Jensen TE, Yang G, Schjerling P, Kiens B, James DE, Ruegg MA, Richter EA. Acute mTOR inhibition induces insulin resistance and alters substrate utilization in vivo. Mol Metab 2014; 3:630-41. [PMID: 25161886 PMCID: PMC4142396 DOI: 10.1016/j.molmet.2014.06.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 06/20/2014] [Accepted: 06/23/2014] [Indexed: 01/12/2023] Open
Abstract
The effect of acute inhibition of both mTORC1 and mTORC2 on metabolism is unknown. A single injection of the mTOR kinase inhibitor, AZD8055, induced a transient, yet marked increase in fat oxidation and insulin resistance in mice, whereas the mTORC1 inhibitor rapamycin had no effect. AZD8055, but not rapamycin reduced insulin-stimulated glucose uptake into incubated muscles, despite normal GLUT4 translocation in muscle cells. AZD8055 inhibited glycolysis in MEF cells. Abrogation of mTORC2 activity by SIN1 deletion impaired glycolysis and AZD8055 had no effect in SIN1 KO MEFs. Re-expression of wildtype SIN1 rescued glycolysis. Glucose intolerance following AZD8055 administration was absent in mice lacking the mTORC2 subunit Rictor in muscle, and in vivo glucose uptake into Rictor-deficient muscle was reduced despite normal Akt activity. Taken together, acute mTOR inhibition is detrimental to glucose homeostasis in part by blocking muscle mTORC2, indicating its importance in muscle metabolism in vivo.
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Affiliation(s)
- Maximilian Kleinert
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Lykke Sylow
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Daniel J. Fazakerley
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
| | - James R. Krycer
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Kristen C. Thomas
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
| | - Anne-Julie Oxbøll
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Andreas B. Jordy
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E. Jensen
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Guang Yang
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
| | - Peter Schjerling
- Institute of Sports Medicine, Department of Orthopedic Surgery, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - David E. James
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
- Charles Perkins Centre, School of Molecular Bioscience, The University of Sydney, Sydney, Australia
| | | | - Erik A. Richter
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
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