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Sun Y, Ni X, Cheng S, Yu X, Jin X, Chen L, Yang Z, Xia D, Chen Z, Hu MG, Hou X. Acteoside improves adipocyte browning by CDK6-mediated mTORC1-TFEB pathway. Biochim Biophys Acta Mol Cell Biol Lipids 2023:159364. [PMID: 37433343 DOI: 10.1016/j.bbalip.2023.159364] [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: 02/10/2023] [Revised: 06/10/2023] [Accepted: 07/04/2023] [Indexed: 07/13/2023]
Abstract
Adipocyte browning increases energy expenditure by thermogenesis, which has been considered a potential strategy against obesity and its related metabolic diseases. Phytochemicals derived from natural products with the ability to improve adipocyte thermogenesis have aroused extensive attention. Acteoside (Act), a phenylethanoid glycoside, exists in various medicinal or edible plants and has been shown to regulate metabolic disorders. Here, the browning effect of Act was evaluated by stimulating beige cell differentiation from the stromal vascular fraction (SVF) in the inguinal white adipose tissue (iWAT) and 3 T3-L1 preadipocytes, and by converting the iWAT-SVF derived mature white adipocytes. Act improves adipocyte browning by differentiation of the stem/progenitors into beige cells and by direct conversion of mature white adipocytes into beige cells. Mechanistically, Act inhibited CDK6 and mTOR, and consequently relieved phosphorylation of the transcription factor EB (TFEB) and increased its nuclear retention, leading to induction of PGC-1α, a driver of mitochondrial biogenesis, and UCP1-dependent browning. These data thus unveil a CDK6-mTORC1-TFEB pathway that regulates Act-induced adipocyte browning.
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Affiliation(s)
- Yunxia Sun
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China; Academy of Chinese Medical Science, Zhejiang Chinese Medical University, China
| | - Xintao Ni
- Academy of Chinese Medical Science, Zhejiang Chinese Medical University, China
| | - Siyao Cheng
- Academy of Chinese Medical Science, Zhejiang Chinese Medical University, China
| | - Xiaofeng Yu
- Academy of Chinese Medical Science, Zhejiang Chinese Medical University, China
| | - Xiaoqin Jin
- Academy of Chinese Medical Science, Zhejiang Chinese Medical University, China
| | - Liangxin Chen
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhenggang Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Disease, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Daozong Xia
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhe Chen
- The Second Clinical Medical College, Zhejiang Chinese Medical University, China
| | - Miaofen G Hu
- Department of Medicine, Division of Hematology and Oncology, Tufts Medical Center, Boston, MA, USA
| | - Xiaoli Hou
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China; Academy of Chinese Medical Science, Zhejiang Chinese Medical University, China.
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2
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Granata S, Mercuri S, Troise D, Gesualdo L, Stallone G, Zaza G. mTOR-inhibitors and post-transplant diabetes mellitus: a link still debated in kidney transplantation. Front Med (Lausanne) 2023; 10:1168967. [PMID: 37250653 PMCID: PMC10213242 DOI: 10.3389/fmed.2023.1168967] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 04/25/2023] [Indexed: 05/31/2023] Open
Abstract
The mammalian target of rapamycin inhibitors (mTOR-Is, Sirolimus, and Everolimus) are immunosuppressive drugs widely employed in kidney transplantation. Their main mechanism of action includes the inhibition of a serine/threonine kinase with a pivotal role in cellular metabolism and in various eukaryotic biological functions (including proteins and lipids synthesis, autophagy, cell survival, cytoskeleton organization, lipogenesis, and gluconeogenesis). Moreover, as well described, the inhibition of the mTOR pathway may also contribute to the development of the post-transplant diabetes mellitus (PTDM), a major clinical complication that may dramatically impact allograft survival (by accelerating the development of the chronic allograft damage) and increase the risk of severe systemic comorbidities. Several factors may contribute to this condition, but the reduction of the beta-cell mass, the impairment of the insulin secretion and resistance, and the induction of glucose intolerance may play a pivotal role. However, although the results of several in vitro and in animal models, the real impact of mTOR-Is on PTDM is still debated and the entire biological machinery is poorly recognized. Therefore, to better elucidate the impact of the mTOR-Is on the risk of PTDM in kidney transplant recipients and to potentially uncover future research topics (particularly for the clinical translational research), we decided to review the available literature evidence regarding this important clinical association. In our opinion, based on the published reports, we cannot draw any conclusion and PTDM remains a challenge. However, also in this case, the administration of the lowest possible dose of mTOR-I should also be recommended.
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Affiliation(s)
- Simona Granata
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Silvia Mercuri
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Dario Troise
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Loreto Gesualdo
- Renal, Dialysis and Transplantation Unit, Department of Precision and Regenerative Medicine and Ionian Area (DIMEPRE-J), University of Bari, Bari, Italy
| | - Giovanni Stallone
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Gianluigi Zaza
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
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3
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Gayatri MB, Gajula NN, Chava S, Reddy ABM. High glutamine suppresses osteogenesis through mTORC1-mediated inhibition of the mTORC2/AKT-473/RUNX2 axis. Cell Death Discov 2022; 8:277. [PMID: 35672290 PMCID: PMC9174279 DOI: 10.1038/s41420-022-01077-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/21/2022] [Accepted: 05/30/2022] [Indexed: 11/09/2022] Open
Abstract
Activation of the key nutrient cellular sensors mTORC1 and mTORC2 directs the fate of mesenchymal stromal cells (MSCs). Here, we report that glutamine regulates crosstalk between mTOR complexes and lineage commitment of MSCs independent of glucose concentration. High glutamine-induced mTORC1 hyperactivation resulted in the suppression of mTORC2, which otherwise stabilizes RUNX2 via GSK3β inhibition through pAKT-473. Activation of GSK3β resulted in the ubiquitination of RUNX2, a key transcription factor for the osteogenic commitment of MSCs. However, low glutamine conditions inhibit mTORC1 hyperactivation followed by increased mTORC2 activation and RUNX2 stabilization. Under diabetic/high-glucose conditions, glutamine-triggered hyperactivation of mTORC1 resulted in mTORC2 suppression, and active GSK3β led to suppression of RUNX2. Activation of p-AMPK by metformin inhibits high glutamine-induced mTORC1 hyperactivation and rescues RUNX2 through the mTORC2/AKT-473 axis. Collectively, our study indicates the role of glutamine in modulating MSC fate through cross-talk between mTOR complexes by identifying a critical switch in signaling. It also shows the importance of glutamine in modulating molecular cues (mTORC1/p-70S6K/mTORC2/RUNX2) that are involved in driving diabetes-induced bone adipogenesis and other secondary complications.
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Affiliation(s)
- Meher Bolisetti Gayatri
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Navya Naidu Gajula
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Suresh Chava
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Aramati B M Reddy
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India.
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4
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Liquiritigenin Inhibits Lipid Accumulation in 3T3-L1 Cells via mTOR-Mediated Regulation of the Autophagy Mechanism. Nutrients 2022; 14:nu14061287. [PMID: 35334944 PMCID: PMC8954126 DOI: 10.3390/nu14061287] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/28/2022] [Accepted: 03/16/2022] [Indexed: 02/01/2023] Open
Abstract
Liquiritigenin (LQG) is a natural flavonoid from the herb Glycyrrhiza uralensis Fisch that exhibits multiple biological activities. However, its specific role in antiobesity and its related underlying molecular mechanisms remain unknown. The primary purpose of this study is to explore the effects and regulatory mechanisms of LQG on lipid accumulation in 3T3-L1 adipocytes. The results show that LQG significantly reduced triglyceride levels and downregulated the expression of transcription factors such as CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) in 3T3-L1 adipocytes. Additionally, the expression of sterol-regulatory element-binding protein 1c (SREBP1c), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FASN) involved in lipogenesis was reduced by treatment with LQG. The protein expression levels of light chain 3B (LC3B), autophagy-related protein 7 (ATG7) and p62 were also modulated by LQG, leading to the suppression of autophagy. Further, LQG activated the phosphorylation of the mammalian target of rapamycin (mTOR), the inhibition of which was followed by the restored expression of autophagy-related proteins. Pretreatment with an mTOR inhibitor also reverted the expression of several genes or proteins involved in lipid synthesis. These results suggest that LQG inhibited lipid accumulation via mTOR-mediated autophagy in 3T3-L1 white adipocytes, indicating the role of LQG as a potential natural bioactive component for use in dietary supplements for preventing obesity.
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Kan S, Li R, Tan Y, Yang F, Xu S, Wang L, Zhang L, Sun X, Chen X, Yang Y, Shu W, Wan H, Chen ZF, Liang H, Chen M. Latexin deficiency attenuates adipocyte differentiation and protects mice against obesity and metabolic disorders induced by high-fat diet. Cell Death Dis 2022; 13:175. [PMID: 35210404 PMCID: PMC8873487 DOI: 10.1038/s41419-022-04636-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/14/2022] [Accepted: 02/10/2022] [Indexed: 12/12/2022]
Abstract
AbstractObesity is a risk factor for many chronic diseases, and is associated with increased incidence rate of type 2 diabetes, hypertension, dyslipidemia and cardiovascular diseases. Adipocyte differentiation play critical role during development of obesity. Latexin (LXN), a mammalian carboxypeptidase inhibitor, plays important role in the proliferation and differentiation of stem cells, and highlights as a differentiation-associated gene that was significantly downregulated in prostate stem cells and whose expression increases through differentiation. However, it is unclear whether LXN is involved in adipocyte differentiation. The aim of this study was to evaluate the role of LXN on adipocyte differentiation, as well as its effects on high fat-induced obesity and metabolic disorders. In this study, we determine the expression of LXN in adipose tissue of lean and fat mice by Western blot, qPCR and immunohistochemistry. We found that LXN in fat tissues was continuous increased during the development of diet-induced obesity. We fed wild-type (WT) and LXN−/−mice with high-fat diet (HFD) to study the effects of LXN on obesity and related metabolic functions. We found that mice deficient in LXN showed resistance against high-fat diet (HFD)-induced obesity, glucose tolerance, insulin tolerance and hepatic steatosis. In vitro studies indicated that LXN was highly induced during adipocyte differentiation, and positively regulated adipocyte differentiation and adipogenesis in 3T3-L1 cells and primary preadipocytes. Functional analysis revealed that the expression of LXN was positively regulated by mTOR/RXR/PPARɤ signaling pathway during the differentiation of adipocytes, while LXN deletion decreased the protein level of PPARɤ in adipocyte through enhancing FABP4 mediated ubiquitination, which led to impaired adipocyte differentiation and lipogenesis. Collectively, our data provide evidence that LXN is a key positive regulator of adipocyte differentiation, and therapeutics targeting LXN could be effective in preventing obesity and its associated disorders in clinical settings.
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6
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Li Y, Fu C, Liu L, Liu Y, Li F. mTOR and ERK1/2 signaling participate in the process of acetate regulating lipid metabolism and HSL expression. Anim Biosci 2021; 35:1444-1453. [PMID: 34727637 PMCID: PMC9449403 DOI: 10.5713/ab.21.0341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/01/2021] [Indexed: 11/27/2022] Open
Abstract
Objective Acetate plays an important role in host lipid metabolism. However, the network of acetate-regulated lipid metabolism remains unclear. Previous studies show that mitogen-activated protein kinases (MAPKs) and mechanistic target of rapamycin (mTOR) play a crucial role in lipid metabolism. We hypothesize that acetate could affect MAPKs and/or mTOR signaling and then regulate lipid metabolism. The present study investigated whether any cross talk occurs among MAPKs, mTOR and acetate in regulating lipid metabolism. Methods The ceramide C6 (an extracellular signaling-regulated kinases 1 and 2 [ERK1/2] activator) and MHY1485 (a mTOR activator) were used to treat rabbit adipose-derived stem cells (ADSCs) with or without acetate, respectively. Results It indicated that acetate (9 mM) treatment for 48 h decreased the lipid deposition in rabbit ADSCs. Acetate treatment decreased significantly phosphorylated protein levels of ERK1/2 and mTOR but significantly increased mRNA level of hormone-sensitive lipase (HSL). Acetate treatment did not significantly alter the phosphorylated protein level of p38 MAPK and c-Jun aminoterminal kinase (JNK). Activation of ERK1/2 and mTOR by respective addition in media with ceramide C6 and MHY1485 significantly attenuated decreased lipid deposition and increased HSL expression caused by acetate. Conclusion Our results suggest that ERK1/2 and mTOR signaling pathways are associated with acetate regulated HSL gene expression and lipid deposition.
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Affiliation(s)
- Yujuan Li
- Department of Animal Science, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Chunyan Fu
- Department of Animal Science, Shandong Agricultural University, Taian, Shandong 271018, China.,Poultry Institute, Shandong Academy of Agricultural Science, Jinan, Shandong 250023, China
| | - Lei Liu
- Department of Animal Science, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Yongxu Liu
- Qingdao Kangda Food Co., LTD., Qingdao, Shandong 266555, China
| | - Fuchang Li
- Department of Animal Science, Shandong Agricultural University, Taian, Shandong 271018, China
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7
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Pan J, Kothan S, Liu L, Moe ATM, Dong L, Sun Y, Yang Y. Autophagy participants in the dedifferentiation of mouse 3T3-L1 adipocytes triggered by hypofunction of insulin signaling. Cell Signal 2021; 80:109911. [PMID: 33422645 DOI: 10.1016/j.cellsig.2020.109911] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 12/28/2020] [Accepted: 12/29/2020] [Indexed: 02/07/2023]
Abstract
Our previous data indicate that both insulin and IGF-1 signallings dysfunction promotes the dedifferentiation of primary human and mouse white adipocytes. Based on the fact that insulin activates mTOR and inhibits autophagy, and autophagy deficiency can inhibit the differentiation of white adipocytes, we speculate that autophagy may be related to the dedifferentiation of white adipocytes. We investigated the underlying mechanism of autophagy during dedifferentiation of mouse 3T3-L1 adipocytes. After incomplete inhibition of insulin and IGF-1 signallings, 3T3-L1 adipocytes manifest dedifferentiation accompanied with an increase of autophagy level. If induction only of autophagy in the adipocytes, then the cells also occur somewhat dedifferentiation, and with a slight decrease of insulin signal, while its degree was weaker than insulin signal inhibited cells. Notably, after inhibition of the insulin and IGF-1 signallings and simultaneously inducing autophagy, the dedifferentiation of 3T3-L1 adipocytes was the most obvious compared with other groups, and the insulin and IGF-1 signallings decreases was greater than the cells with inhibition only of insulin signalling. If inhibition of both insulin signal and autophagy simultaneously, the dedifferentiation of the adipocytes reveals similar tendencies to the cells that insulin signal was inhibited. No significant dedifferentiation occurs of 3T3-L1 cells if only inhibition of autophagy. Taken all together, in this study, we proved that autophagy is positively related to the dedifferentiation of 3T3-L1 adipocytes and is regulated through the insulin-PI3K-AKT-mTOCR1-autophagy pathway. Autophagy may also has a certain degree of negative feedback affect on the insulin signalling of 3T3-L1 cells. Our work may help to better understand the biological properties of mature adipocytes and may help formulate anti-obesity strategies by regulating insulin and insulin signaling level.
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Affiliation(s)
- Jie Pan
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan 250014, China; Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand.
| | - Suchart Kothan
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Laihao Liu
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Aye Thidar Moe Moe
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Liwei Dong
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Yanan Sun
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Yiyi Yang
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan 250014, China
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8
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Al Dow M, Silveira MAD, Poliquin A, Tribouillard L, Fournier É, Trébaol E, Secco B, Villot R, Tremblay F, Bilodeau S, Laplante M. Control of adipogenic commitment by a STAT3-VSTM2A axis. Am J Physiol Endocrinol Metab 2021; 320:E259-E269. [PMID: 33196296 PMCID: PMC8260376 DOI: 10.1152/ajpendo.00314.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
White adipose tissue (WAT) is a dynamic organ that plays crucial roles in controlling metabolic homeostasis. During development and periods of energy excess, adipose progenitors are recruited and differentiate into adipocytes to promote lipid storage capability. The identity of adipose progenitors and the signals that promote their recruitment are still incompletely characterized. We have recently identified V-set and transmembrane domain-containing protein 2A (VSTM2A) as a novel protein enriched in preadipocytes that amplifies adipogenic commitment. Despite the emerging role of VSTM2A in promoting adipogenesis, the molecular mechanisms regulating Vstm2a expression in preadipocytes are still unknown. To define the molecular mechanisms controlling Vstm2a expression, we have treated preadipocytes with an array of compounds capable of modulating established regulators of adipogenesis. Here, we report that Vstm2a expression is positively regulated by PI3K/mTOR and cAMP-dependent signaling pathways and repressed by the MAPK pathway and the glucocorticoid receptor. By integrating the impact of all the molecules tested, we identified signal transducer and activator of transcription 3 (STAT3) as a novel downstream transcription factor affecting Vstm2a expression. We show that activation of STAT3 increased Vstm2a expression, whereas its inhibition repressed this process. In mice, we found that STAT3 phosphorylation is elevated in the early phases of WAT development, an effect that strongly associates with Vstm2a expression. Our findings identify STAT3 as a key transcription factor regulating Vstm2a expression in preadipocytes.NEW & NOTEWORTHY cAMP-dependent and PI3K-mTOR signaling pathways promote the expression of Vstm2a. STAT3 is a key transcription factor that controls Vstm2a expression in preadipocytes. STAT3 is activated in the early phases of WAT development, an effect that strongly associates with Vstm2a expression.
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Affiliation(s)
- Manal Al Dow
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
| | - Maruhen Amir Datsch Silveira
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
- Centre de recherche du CHU de Québec - Université Laval, Québec, Canada
| | - Audrée Poliquin
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
| | - Laura Tribouillard
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
| | - Éric Fournier
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
- Centre de recherche du CHU de Québec - Université Laval, Québec, Canada
- Centre de recherche en données massives de l'Université Laval, Québec, Canada
| | - Eva Trébaol
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
| | - Blandine Secco
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
- Centre de recherche du CHU de Québec - Université Laval, Québec, Canada
| | - Romain Villot
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
| | - Félix Tremblay
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
| | - Steve Bilodeau
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
- Centre de recherche du CHU de Québec - Université Laval, Québec, Canada
- Centre de recherche en données massives de l'Université Laval, Québec, Canada
- Département de biologie moléculaire, biochimie médicale et pathologie, Faculté de Médecine, Université Laval, Québec, Canada
| | - Mathieu Laplante
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada
- Centre de recherche sur le cancer de l'Université Laval, Université Laval, Québec, Canada
- Département de Médecine, Faculté de Médecine, Université Laval, Québec, Canada
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Peroxisome Proliferator-Activated Receptors as Molecular Links between Caloric Restriction and Circadian Rhythm. Nutrients 2020; 12:nu12113476. [PMID: 33198317 PMCID: PMC7696073 DOI: 10.3390/nu12113476] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/04/2020] [Accepted: 11/09/2020] [Indexed: 02/06/2023] Open
Abstract
The circadian rhythm plays a chief role in the adaptation of all bodily processes to internal and environmental changes on the daily basis. Next to light/dark phases, feeding patterns constitute the most essential element entraining daily oscillations, and therefore, timely and appropriate restrictive diets have a great capacity to restore the circadian rhythm. One of the restrictive nutritional approaches, caloric restriction (CR) achieves stunning results in extending health span and life span via coordinated changes in multiple biological functions from the molecular, cellular, to the whole-body levels. The main molecular pathways affected by CR include mTOR, insulin signaling, AMPK, and sirtuins. Members of the family of nuclear receptors, the three peroxisome proliferator-activated receptors (PPARs), PPARα, PPARβ/δ, and PPARγ take part in the modulation of these pathways. In this non-systematic review, we describe the molecular interconnection between circadian rhythm, CR-associated pathways, and PPARs. Further, we identify a link between circadian rhythm and the outcomes of CR on the whole-body level including oxidative stress, inflammation, and aging. Since PPARs contribute to many changes triggered by CR, we discuss the potential involvement of PPARs in bridging CR and circadian rhythm.
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10
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Chen Y, Zhou X. Research progress of mTOR inhibitors. Eur J Med Chem 2020; 208:112820. [PMID: 32966896 DOI: 10.1016/j.ejmech.2020.112820] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/16/2020] [Accepted: 09/03/2020] [Indexed: 12/25/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a highly conserved Serine/Threonine (Ser/Thr) protein kinase, which belongs to phosphatidylinositol-3-kinase-related kinase (PIKK) protein family. mTOR exists as two types of protein complex: mTORC1 and mTORC2, which act as central controller regulating processes of cell metabolism, growth, proliferation, survival and autophagy. The mTOR inhibitors block mTOR signaling pathway, producing anti-inflammatory, anti-proliferative, autophagy and apoptosis induction effects, thus mTOR inhibitors are mainly used in cancer therapy. At present, mTOR inhibitors are divided into four categories: Antibiotic allosteric mTOR inhibitors (first generation), ATP-competitive mTOR inhibitors (second generation), mTOR/PI3K dual inhibitors (second generation) and other new mTOR inhibitors (third generation). In this article, these four categories of mTOR inhibitors and their structures, properties and some clinical researches will be introduced. Among them, we focus on the structure of mTOR inhibitors and try to analyze the structure-activity relationship. mTOR inhibitors are classified according to their chemical structure and their contents are introduced systematically. Moreover, some natural products that have direct or indirect mTOR inhibitory activities are introduced together. In this article, we analyzed the target, binding mode and structure-activity relationship of each generation of mTOR inhibitors and proposed two hypothetic scaffolds (the inverted-Y-shape scaffold and the C-shape scaffold) for the second generation of mTOR inhibitors. These findings may provide some help or reference for drug designing, drug modification or the future development of mTOR inhibitor.
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Affiliation(s)
- Yifan Chen
- School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, China
| | - Xiaoping Zhou
- School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, China.
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11
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Yokokawa T, Sato K, Narusawa R, Kido K, Mori R, Iwanaka N, Hayashi T, Hashimoto T. Dehydroepiandrosterone activates 5'-adenosine monophosphate-activated protein kinase and suppresses lipid accumulation and adipocyte differentiation in 3T3-L1 cells. Biochem Biophys Res Commun 2020; 528:612-619. [PMID: 32505344 DOI: 10.1016/j.bbrc.2020.05.136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 11/16/2022]
Abstract
Substantial evidence has linked dehydroepiandrosterone (DHEA) levels to the anti-obesity and anti-diabetic effects of exercise. While 5'-adenosine monophosphate-activated protein kinase (AMPK) is a negative regulator of adipocyte differentiation and lipid accumulation, activation of mammalian target of rapamycin complex 1 (mTORC1), which is inhibited by AMPK, is required for adipocyte differentiation and positively regulates lipid accumulation. DHEA treatment activates the AMPK pathway in C2C12 myotubes. Hence, DHEA addition to preadipocytes and adipocytes might activate AMPK and inhibit mTORC1, resulting in the inhibition of adipogenesis and lipid accumulation. Therefore, we investigated the effect of DHEA on the AMPK pathway, mTORC1 activity, adipocyte differentiation, and lipid accumulation in 3T3-L1 cells. DHEA suppressed lipid accumulation and adipogenic marker expression during differentiation. It also activated AMPK signaling in preadipocytes and adipocytes and suppressed mTORC1 activity during differentiation. These results suggest that the activation of the AMPK pathway and inhibition of mTORC1 activity may mediate the anti-obesity effect of DHEA, providing novel molecular-level insights into its physiological functions.
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Affiliation(s)
- Takumi Yokokawa
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan; College of Gastronomy Management, Ritsumeikan University, Shiga, Japan.
| | - Koji Sato
- Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Ryoko Narusawa
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Kohei Kido
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan; Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan
| | - Risako Mori
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Nobumasa Iwanaka
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan; Faculty of Health Science, Kyoto Koka Women's University, Kyoto, Japan
| | - Tatsuya Hayashi
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
| | - Takeshi Hashimoto
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
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12
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Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity. Cells 2020; 9:cells9071708. [PMID: 32708786 PMCID: PMC7407644 DOI: 10.3390/cells9071708] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023] Open
Abstract
Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.
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13
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Pascual F, Schisler JC, Grevengoed TJ, Willis MS, Coleman RA. Modeling the Transition From Decompensated to Pathological Hypertrophy. J Am Heart Assoc 2018; 7:JAHA.117.008293. [PMID: 29622588 PMCID: PMC6015423 DOI: 10.1161/jaha.117.008293] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Long-chain acyl-CoA synthetases (ACSL) catalyze the conversion of long-chain fatty acids to fatty acyl-CoAs. Cardiac-specific ACSL1 temporal knockout at 2 months results in a shift from FA oxidation toward glycolysis that promotes mTORC1-mediated ventricular hypertrophy. We used unbiased metabolomics and gene expression analyses to examine the early effects of genetic inactivation of fatty acid oxidation on cardiac metabolism, hypertrophy development, and function. METHODS AND RESULTS Global cardiac transcriptional analysis revealed differential expression of genes involved in cardiac metabolism, fibrosis, and hypertrophy development in Acsl1H-/- hearts 2 weeks after Acsl1 ablation. Comparison of the 2- and 10-week transcriptional responses uncovered 137 genes whose expression was uniquely changed upon knockdown of cardiac ACSL1, including the distinct upregulation of fibrosis genes, a phenomenon not observed after complete ACSL1 knockout. Metabolomic analysis identified metabolites altered in hearts displaying partially reduced ACSL activity, and rapamycin treatment normalized the cardiac metabolomic fingerprint. CONCLUSIONS Short-term cardiac-specific ACSL1 inactivation resulted in metabolic and transcriptional derangements distinct from those observed upon complete ACSL1 knockout, suggesting heart-specific mTOR (mechanistic target of rapamycin) signaling that occurs during the early stages of substrate switching. The hypertrophy observed with partial Acsl1 ablation occurs in the context of normal cardiac function and is reminiscent of a physiological process, making this a useful model to study the transition from physiological to pathological hypertrophy.
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Affiliation(s)
- Florencia Pascual
- Department of Nutrition, University of North Carolina at Chapel Hill, NC
| | - Jonathan C Schisler
- Department of Pharmacology, University of North Carolina at Chapel Hill, NC.,Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, NC.,McAllister Heart Institute University of North Carolina at Chapel Hill, NC
| | | | - Monte S Willis
- Department of Pharmacology, University of North Carolina at Chapel Hill, NC.,Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, NC.,McAllister Heart Institute University of North Carolina at Chapel Hill, NC
| | - Rosalind A Coleman
- Department of Nutrition, University of North Carolina at Chapel Hill, NC
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14
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Magdalon J, Festuccia WT. Regulation of adiposity by mTORC1. ACTA ACUST UNITED AC 2018; 15:507-511. [PMID: 29364369 PMCID: PMC5875170 DOI: 10.1590/s1679-45082017rb4106] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 09/20/2017] [Indexed: 11/22/2022]
Abstract
Obesity is characterized by an excessive increase in the adipose tissue mass, and is associated with higher incidence of several chronic metabolic diseases, such as type 2 diabetes. Therefore, its increasing prevalence is a public health concern, and it is important to better understand its etiology to develop new therapeutic strategies. Evidence accumulated over the years indicates that obesity is associated with a marked activation in adipose tissue of the mechanistic target of rapamycin complex 1 (mTORC1), a signaling pathway that controls lipid metabolism, and adipocyte formation and maintenance. Curiously, mTORC1 is also involved in the control of nonshivering thermogenesis and recruitment as well as browning of white adipose tissue. In this review, we explored mTORC1 functions in adipocytes and presented evidence, suggesting that mTORC1 may either increase or reduce adiposity, depending on the conditions and activation levels.
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15
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Yang Y, Qi Q, Wang Y, Shi Y, Yang W, Cen Y, Zhu E, Li X, Chen D, Wang B. Cysteine-rich protein 61 regulates adipocyte differentiation from mesenchymal stem cells through mammalian target of rapamycin complex 1 and canonical Wnt signaling. FASEB J 2018; 32:3096-3107. [PMID: 29401606 DOI: 10.1096/fj.201700830rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Emerging evidence suggests that cysteine-rich protein 61 (CYR61) plays a role in the differentiation and development of chondrocytes, osteoblasts, and osteoclasts; however, little is known about its role in adipogenesis. The current study indicates that the expression level of Cyr61 was altered in primary cultured marrow stromal cells and the established mesenchymal cell line, C3H10T1/2, after adipogenic treatment. Overexpressing Cyr61 repressed C3H10T1/2 and primary marrow stromal cells to differentiate into mature adipocytes. Conversely, inhibition of endogenous Cyr61 induced C3H10T1/2 and primary marrow stromal cells to fully differentiate. Mechanism investigations reveal that knockdown of Cyr61 inhibited the nuclear translocation of β-catenin and decreased nuclear protein levels of β-catenin and transcription factor 7-like 2. Moreover, the silencing of Cyr61 increased protein levels of phosphorylated ribosomal protein S6 kinase B1, mammalian target of rapamycin, eukaryotic translation initiation factor 4E-binding protein 1, and ribosomal protein S6-the major components of mammalian target of rapamycin complex 1 (mTORC1) signaling-in C3H10T1/2 cells. Additional investigations demonstrated that treatment with rapamycin significantly attenuated adipocyte formation that was induced by Cyr61 small interfering RNA (siRNA) transfection. Moreover, Cyr61 siRNA also lost its ability to stimulate adipocyte formation under the background of β-catenin overexpression. Taken together, our study provides evidence that CYR61 regulates adipocyte differentiation via multiple signaling pathways that involve at least the inactivation of mTORC1 signaling and the activation of canonical Wnt signaling.-Yang, Y., Qi, Q., Wang, Y., Shi, Y., Yang, W., Cen, Y., Zhu, E., Li, X., Chen, D., Wang, B. Cysteine-rich protein 61 regulates adipocyte differentiation from mesenchymal stem cells through mammalian target of rapamycin complex 1 and canonical Wnt signaling.
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Affiliation(s)
- Yongxu Yang
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Qi Qi
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Yi Wang
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Yaru Shi
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Weili Yang
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Yunzhu Cen
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Endong Zhu
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
| | - Xiaoxia Li
- College of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Di Chen
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, USA
| | - Baoli Wang
- Collaborative Innovation Center of Tianjin Metabolic Diseases Hospital, Key Laboratory of Hormones and Development, Ministry of Health, Metabolic Diseases Hospital and Institute of Endocrinology, Tianjin Medical University, Tianjin, China.,2011 Collaborative Innovation Center for Metabolic Diseases, Metabolic Diseases Hospital, Tianjin Medical University, Tianjin, China
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16
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Armani A, Berry A, Cirulli F, Caprio M. Molecular mechanisms underlying metabolic syndrome: the expanding role of the adipocyte. FASEB J 2017; 31:4240-4255. [PMID: 28705812 DOI: 10.1096/fj.201601125rrr] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 06/12/2017] [Indexed: 02/06/2023]
Abstract
The metabolic syndrome (MetS) is defined as a cluster of 3 or more metabolic and cardiovascular risk factors and represents a serious problem for public health. Altered function of adipose tissue has a significant impact on whole-body metabolism and represents a key driver for the development of these metabolic derangements, collectively referred as to MetS. In particular, increased visceral and ectopic fat deposition play a major role in the development of insulin resistance and MetS. A large body of evidence demonstrates that aging and MetS share several metabolic alterations. Of importance, molecular pathways that regulate lifespan affect key processes of adipose tissue physiology, and transgenic mouse models with adipose-specific alterations in these pathways show derangements of adipose tissue and other metabolic features of MetS, which highlights a causal link between dysfunctional adipose tissue and deleterious effects on whole-body homeostasis. This review analyzes adipose tissue-specific dysfunctions, including metabolic alterations that are related to aging, that have a significant impact on the development of MetS.-Armani, A., Berry, A., Cirulli, F., Caprio, M. Molecular mechanisms underlying metabolic syndrome: the expanding role of the adipocyte.
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Affiliation(s)
- Andrea Armani
- Laboratory of Cardiovascular Endocrinology, Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy
| | - Alessandra Berry
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Francesca Cirulli
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Massimiliano Caprio
- Laboratory of Cardiovascular Endocrinology, Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy; .,Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
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17
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Meng W, Liang X, Chen H, Luo H, Bai J, Li G, Zhang Q, Xiao T, He S, Zhang Y, Xu Z, Xiao B, Liu M, Hu F, Liu F. Rheb Inhibits Beiging of White Adipose Tissue via PDE4D5-Dependent Downregulation of the cAMP-PKA Signaling Pathway. Diabetes 2017; 66:1198-1213. [PMID: 28242620 PMCID: PMC5860267 DOI: 10.2337/db16-0886] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/14/2016] [Indexed: 12/14/2022]
Abstract
Beiging of white adipose tissue has potential antiobesity and antidiabetes effects, yet the underlying signaling mechanisms remain to be fully elucidated. Here we show that adipose-specific knockout of Rheb, an upstream activator of mechanistic target of rapamycin complex 1 (mTORC1), protects mice from high-fat diet-induced obesity and insulin resistance. On the one hand, Rheb deficiency in adipose tissue reduced mTORC1 signaling, increased lipolysis, and promoted beiging and energy expenditure. On the other hand, overexpression of Rheb in primary adipocytes significantly inhibited CREB phosphorylation and uncoupling protein 1 (UCP1) expression. Mechanistically, fat-specific knockout of Rheb increased cAMP levels, cAMP-dependent protein kinase (PKA) activity, and UCP1 expression in subcutaneous white adipose tissue. Interestingly, treating primary adipocytes with rapamycin only partially alleviated the suppressing effect of Rheb on UCP1 expression, suggesting the presence of a novel mechanism underlying the inhibitory effect of Rheb on thermogenic gene expression. Consistent with this notion, overexpression of Rheb stabilizes the expression of cAMP-specific phosphodiesterase 4D5 (PDE4D5) in adipocytes, whereas knockout of Rheb greatly reduced cellular levels of PDE4D5 concurrently with increased cAMP levels, PKA activation, and UCP1 expression. Taken together, our findings reveal Rheb as an important negative regulator of beige fat development and thermogenesis. In addition, Rheb is able to suppress the beiging effect through an mTORC1-independent mechanism.
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Affiliation(s)
- Wen Meng
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xiuci Liang
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Hongzhi Chen
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Hairong Luo
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Juli Bai
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX
| | - Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Qinghai Zhang
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Ting Xiao
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Sijia He
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX
| | - Yacheng Zhang
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhipeng Xu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Bo Xiao
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Meilian Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Feng Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX
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18
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Morin-Doré L, Blondin P, Vigneault C, Grand FX, Labrecque R, Sirard MA. Transcriptomic evaluation of bovine blastocysts obtained from peri-pubertal oocyte donors. Theriogenology 2017; 93:111-123. [PMID: 28257859 DOI: 10.1016/j.theriogenology.2017.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/09/2016] [Accepted: 01/03/2017] [Indexed: 12/18/2022]
Abstract
Assisted reproduction technologies (ART) and high selection pressure in the dairy industry are leading towards the use of younger females for reproduction, thereby reducing the interval between generations. This situation may have a negative impact on embryo quality, thus reducing the success rate of the procedures. This study aimed to document the effects of oocyte donor age on embryo quality, at the transcriptomic level, in order to characterize the effects of using young females for reproduction purpose. Young Holstein heifers (n = 10) were used at three different ages for ovarian stimulation protocols and oocyte collections (at 8, 11 and 14 months). All of the oocytes were fertilized in vitro with the semen of one adult bull, generating three lots of embryos per animal. Each animal was its own control for the evaluation of the effects of age. The EmbryoGENE platform was used for the assessment of gene expression patterns at the blastocyst stage. Embryos from animals at 8 vs 14 months and at 11 vs 14 months were used for microarray hybridization. Validation was done by performing RT-qPCR on seven candidate genes. Age-related contrast analysis (8 vs 14 mo and 11 vs 14 mo) identified 242 differentially expressed genes (DEGs) for the first contrast, and 296 for the second. The analysis of the molecular and biological functions of the DEGs suggests a metabolic cause to explain the differences that are observed between embryos from immature and adult subjects. The mTOR and PPAR signaling pathways, as well as the NRF2-mediated oxidative stress response pathways were among the gene expression pathways affected by donor age. In conclusion, the main differences between embryos produced at peri-pubertal ages are related to metabolic conditions resulting in a higher impact of in vitro conditions on blastocyts from younger heifers.
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Affiliation(s)
- Léonie Morin-Doré
- Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Département des Sciences Animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Québec, Canada
| | | | | | | | | | - Marc-André Sirard
- Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Département des Sciences Animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Québec, Canada.
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19
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Castro JP, Grune T, Speckmann B. The two faces of reactive oxygen species (ROS) in adipocyte function and dysfunction. Biol Chem 2016; 397:709-24. [DOI: 10.1515/hsz-2015-0305] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/08/2016] [Indexed: 12/11/2022]
Abstract
Abstract
White adipose tissue (WAT) is actively involved in the regulation of whole-body energy homeostasis via storage/release of lipids and adipokine secretion. Current research links WAT dysfunction to the development of metabolic syndrome (MetS) and type 2 diabetes (T2D). The expansion of WAT during oversupply of nutrients prevents ectopic fat accumulation and requires proper preadipocyte-to-adipocyte differentiation. An assumed link between excess levels of reactive oxygen species (ROS), WAT dysfunction and T2D has been discussed controversially. While oxidative stress conditions have conclusively been detected in WAT of T2D patients and related animal models, clinical trials with antioxidants failed to prevent T2D or to improve glucose homeostasis. Furthermore, animal studies yielded inconsistent results regarding the role of oxidative stress in the development of diabetes. Here, we discuss the contribution of ROS to the (patho)physiology of adipocyte function and differentiation, with particular emphasis on sources and nutritional modulators of adipocyte ROS and their functions in signaling mechanisms controlling adipogenesis and functions of mature fat cells. We propose a concept of ROS balance that is required for normal functioning of WAT. We explain how both excessive and diminished levels of ROS, e.g. resulting from over supplementation with antioxidants, contribute to WAT dysfunction and subsequently insulin resistance.
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20
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Granata S, Dalla Gassa A, Carraro A, Brunelli M, Stallone G, Lupo A, Zaza G. Sirolimus and Everolimus Pathway: Reviewing Candidate Genes Influencing Their Intracellular Effects. Int J Mol Sci 2016; 17:ijms17050735. [PMID: 27187382 PMCID: PMC4881557 DOI: 10.3390/ijms17050735] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/21/2016] [Accepted: 05/06/2016] [Indexed: 02/07/2023] Open
Abstract
Sirolimus (SRL) and everolimus (EVR) are mammalian targets of rapamycin inhibitors (mTOR-I) largely employed in renal transplantation and oncology as immunosuppressive/antiproliferative agents. SRL was the first mTOR-I produced by the bacterium Streptomyces hygroscopicus and approved for several medical purposes. EVR, derived from SRL, contains a 2-hydroxy-ethyl chain in the 40th position that makes the drug more hydrophilic than SRL and increases oral bioavailability. Their main mechanism of action is the inhibition of the mTOR complex 1 and the regulation of factors involved in a several crucial cellular functions including: protein synthesis, regulation of angiogenesis, lipid biosynthesis, mitochondrial biogenesis and function, cell cycle, and autophagy. Most of the proteins/enzymes belonging to the aforementioned biological processes are encoded by numerous and tightly regulated genes. However, at the moment, the polygenic influence on SRL/EVR cellular effects is still not completely defined, and its comprehension represents a key challenge for researchers. Therefore, to obtain a complete picture of the cellular network connected to SRL/EVR, we decided to review major evidences available in the literature regarding the genetic influence on mTOR-I biology/pharmacology and to build, for the first time, a useful and specific “SRL/EVR genes-focused pathway”, possibly employable as a starting point for future in-depth research projects.
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Affiliation(s)
- Simona Granata
- Renal Unit, Department of Medicine, University/Hospital of Verona, 37126 Verona, Italy.
| | | | - Amedeo Carraro
- Liver Transplant Unit, Department of General Surgery and Odontoiatrics, University/Hospital of Verona, 37126 Verona, Italy.
| | - Matteo Brunelli
- Department of Pathology and Diagnostics, University of Verona, Azienda Ospedaliera Universitaria Integrata, 37126 Verona, Italy.
| | - Giovanni Stallone
- Nephrology, Dialysis and Transplantation Unit, University of Foggia, 71122 Foggia, Italy.
| | - Antonio Lupo
- Renal Unit, Department of Medicine, University/Hospital of Verona, 37126 Verona, Italy.
| | - Gianluigi Zaza
- Renal Unit, Department of Medicine, University/Hospital of Verona, 37126 Verona, Italy.
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Abstract
The synthesis of lipids in response to food intake represents a key advantage that allows organisms to survive when energy availability is limited. In mammals, circulating levels of insulin and nutrients, which fluctuate between fasting and feeding, dictate whether lipids are synthesized or catabolized by tissues. The mechanistic target of rapamycin (mTOR), a kinase that is activated by anabolic signals, plays fundamental roles in regulating lipid biosynthesis and metabolism in response to nutrition. The mTOR kinase nucleates two large protein complexes named mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Following their activation, these complexes facilitate the accumulation of triglycerides by promoting adipogenesis and lipogenesis and by shutting down catabolic processes such as lipolysis and β-oxidation. Here, we review and discuss the roles of mTOR complexes in various aspects of lipid metabolism in mammals. We also use this opportunity to discuss the implication of these relations to the maintenance of systemic lipid homeostasis.
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Affiliation(s)
- Alexandre Caron
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, Canada, G1V 4G5;
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22
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Magdalon J, Chimin P, Belchior T, Neves RX, Vieira-Lara MA, Andrade ML, Farias TS, Bolsoni-Lopes A, Paschoal VA, Yamashita AS, Kowaltowski AJ, Festuccia WT. Constitutive adipocyte mTORC1 activation enhances mitochondrial activity and reduces visceral adiposity in mice. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:430-8. [PMID: 26923434 DOI: 10.1016/j.bbalip.2016.02.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/26/2016] [Accepted: 02/24/2016] [Indexed: 10/22/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) loss of function reduces adiposity whereas partial mTORC1 inhibition enhances fat deposition. Herein we evaluated how constitutive mTORC1 activation in adipocytes modulates adiposity in vivo. Mice with constitutive mTORC1 activation in adipocytes induced by tuberous sclerosis complex (Tsc)1 deletion and littermate controls were evaluated for body mass, energy expenditure, glucose and fatty acid metabolism, mitochondrial function, mRNA and protein contents. Adipocyte-specific Tsc1 deletion reduced visceral, but not subcutaneous, fat mass, as well as adipocyte number and diameter, phenotypes that were associated with increased lipolysis, UCP-1 content (browning) and mRNA levels of pro-browning transcriptional factors C/EBPβ and ERRα. Adipocyte Tsc1 deletion enhanced mitochondrial oxidative activity, fatty acid oxidation and the expression of PGC-1α and PPARα in both visceral and subcutaneous fat. In brown adipocytes, however, Tsc1 deletion did not affect UCP-1 content and basal respiration. Adipocyte Tsc1 deletion also reduced visceral adiposity and enhanced glucose tolerance, liver and muscle insulin signaling and adiponectin secretion in mice fed with purified low- or high-fat diet. In conclusion, adipocyte-specific Tsc1 deletion enhances mitochondrial activity, induces browning and reduces visceral adiposity in mice.
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Affiliation(s)
- Juliana Magdalon
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Patricia Chimin
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Thiago Belchior
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Rodrigo X Neves
- Departmento de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Marcel A Vieira-Lara
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05500900, Brazil
| | - Maynara L Andrade
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Talita S Farias
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Andressa Bolsoni-Lopes
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Vivian A Paschoal
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Alex S Yamashita
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05500900, Brazil
| | - William T Festuccia
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508000, Brazil.
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Velloso LA, Folli F, Saad MJ. TLR4 at the Crossroads of Nutrients, Gut Microbiota, and Metabolic Inflammation. Endocr Rev 2015; 36:245-71. [PMID: 25811237 DOI: 10.1210/er.2014-1100] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Obesity is accompanied by the activation of low-grade inflammatory activity in metabolically relevant tissues. Studies have shown that obesity-associated insulin resistance results from the inflammatory targeting and inhibition of key proteins of the insulin-signaling pathway. At least three apparently distinct mechanisms-endoplasmic reticulum stress, toll-like receptor (TLR) 4 activation, and changes in gut microbiota-have been identified as triggers of obesity-associated metabolic inflammation; thus, they are expected to represent potential targets for the treatment of obesity and its comorbidities. Here, we review the data that place TLR4 in the center of the events that connect the consumption of dietary fats with metabolic inflammation and insulin resistance. Changes in the gut microbiota can lead to reduced integrity of the intestinal barrier, leading to increased leakage of lipopolysaccharides and fatty acids, which can act upon TLR4 to activate systemic inflammation. Fatty acids can also trigger endoplasmic reticulum stress, which can be further stimulated by cross talk with active TLR4. Thus, the current data support a connection among the three main triggers of metabolic inflammation, and TLR4 emerges as a link among all of these mechanisms.
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Affiliation(s)
- Licio A Velloso
- Department of Internal Medicine (L.A.V., F.F., M.J.S.), University of Campinas, 13084-970 Campinas SP, Brazil; and Department of Medicine (F.F.), Division of Diabetes, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Franco Folli
- Department of Internal Medicine (L.A.V., F.F., M.J.S.), University of Campinas, 13084-970 Campinas SP, Brazil; and Department of Medicine (F.F.), Division of Diabetes, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Mario J Saad
- Department of Internal Medicine (L.A.V., F.F., M.J.S.), University of Campinas, 13084-970 Campinas SP, Brazil; and Department of Medicine (F.F.), Division of Diabetes, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
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Watanabe M, Hisatake M, Fujimori K. Fisetin Suppresses Lipid Accumulation in Mouse Adipocytic 3T3-L1 Cells by Repressing GLUT4-Mediated Glucose Uptake through Inhibition of mTOR-C/EBPα Signaling. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:4979-4987. [PMID: 25945786 DOI: 10.1021/acs.jafc.5b00821] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
3,7,3',4'-Tetrahydroxyflavone (fisetin) is a flavonoid found in vegetables and fruits having broad biological activities. Here the effects of fisetin on adipogenesis and its regulatory mechanism in mouse adipocytic 3T3-L1 cells are studied. Fisetin inhibited the accumulation of intracellular lipids and lowered the expression of adipogenic genes such as peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein (C/EBP) α and fatty acid-binding protein 4 (aP2) during adipogenesis. Moreover, the mRNA levels of genes such as acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase involved in the fatty acid biosynthesis (lipogenesis) were reduced by the treatment with fisetin. The expression level of the glucose transporter 4 (GLUT4) gene was also decreased by fisetin, resulting in down-regulation of glucose uptake. Furthermore, fisetin inhibited the phosphorylation of the mammalian target of rapamycin (mTOR) and that of p70 ribosomal S6 kinase, a target of the mTOR complex, the inhibition of which was followed by a decreased mRNA level of the C/EBPα gene. The results obtained from a chromatin immunoprecipitation assay demonstrated that the ability of C/EBPα to bind to the GLUT4 gene promoter was reduced by the treatment with fisetin, which agreed well with those obtained when 3T3-L1 cells were allowed to differentiate into adipocytes in medium in the presence of rapamycin, an inhibitor for mTOR. These results indicate that fisetin suppressed the accumulation of intracellular lipids by inhibiting GLUT4-mediated glucose uptake through inhibition of the mTOR-C/EBPα signaling in 3T3-L1 cells.
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Affiliation(s)
- Marina Watanabe
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mitsuhiro Hisatake
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Ko Fujimori
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Wang W, Zhang Y, Lu W, Liu K. Mitochondrial reactive oxygen species regulate adipocyte differentiation of mesenchymal stem cells in hematopoietic stress induced by arabinosylcytosine. PLoS One 2015; 10:e0120629. [PMID: 25768922 PMCID: PMC4359087 DOI: 10.1371/journal.pone.0120629] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 01/28/2015] [Indexed: 01/28/2023] Open
Abstract
Objective The increase in adipocytes induced by chemotherapeutic drugs may play a negative role in hematopoietic recovery. However, the mechanism underlying adipocyte differentiation of mesenchymal stem cells (MSCs) in hematopoietic stress is still unknown. Hence, the involvement of reactive oxygen species (ROS) in adipocyte differentiation under hematopoietic stress was investigated in vitro and in vivo. Methods The roles of cellular ROS in adipogenesis were investigated in vivo through an adipocyte hyperplasia marrow model under hematopoietic stress induced by arabinosylcytosine (Ara-C) and in vitro via adipocyte differentiation of human MSCs. ROS levels were detected using the CM-H2DCFDA probe and Mito-SOX dye. Adipogenesis was evaluated by histopathology and oil red O staining, whereas detection of mRNA levels of antioxidant enzymes and adipogenesis markers was performed using quantitative real-time polymerase chain reaction analysis. Results ROS were found to play an important role in regulating adipocyte differentiation of MSCs by activating peroxisome proliferator-activated receptor gamma (PPARγ,) while the antioxidant N-acetyl-L-cysteine acts through ROS to inhibit adipocyte differentiation. The elevated ROS levels induced by Ara-C were caused by both over-generation of mitochondrial ROS and reduction of antioxidant enzymes (Cu/Zn Superoxide dismutase and catalase). Our findings suggest that a mitochondrial-targeted antioxidant could diminish adipocyte differentiation.
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Affiliation(s)
- Weimin Wang
- Department of Hematology, Peking University People's Hospital, Beijing, China
- Institute of Hematology, Peking University, Beijing, China
| | - Yao Zhang
- Department of Hematology, Peking University People's Hospital, Beijing, China
- Institute of Hematology, Peking University, Beijing, China
| | - Wenyi Lu
- Department of Hematology, Peking University People's Hospital, Beijing, China
- Institute of Hematology, Peking University, Beijing, China
| | - Kaiyan Liu
- Department of Hematology, Peking University People's Hospital, Beijing, China
- Institute of Hematology, Peking University, Beijing, China
- * E-mail:
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26
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Beg M, Shankar K, Varshney S, Rajan S, Singh SP, Jagdale P, Puri A, Chaudhari BP, Sashidhara KV, Gaikwad AN. A clerodane diterpene inhibit adipogenesis by cell cycle arrest and ameliorate obesity in C57BL/6 mice. Mol Cell Endocrinol 2015; 399:373-85. [PMID: 25450865 DOI: 10.1016/j.mce.2014.09.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 09/03/2014] [Accepted: 09/23/2014] [Indexed: 02/06/2023]
Abstract
A clerodane diterpene, 16α-Hydroxycleroda-3, 13 (14) Z-dien-15, 16-olide (compound 1) isolated from Polyalthia longifolia had previously been reported as a new structural class of HMG-CoA reductase inhibitor apart from statins. Statins are known to be anti-adipogenic in nature. The distant structural similarity between compound 1 and lovastatin (polyketide class of compound) prompted us to investigate effects of diterpene compound 1 on adipogenesis and thereby obesity. High content microscopy proved diterpene compound 1 exhibits better anti-adipogenic activity and less toxicity in differentiating adipocytes. Moreover, it reduced expression levels of PPARγ, C/EBPα and GLUT4 during differentiation in a time and concentration dependent manner. Diterpene compound 1 during early differentiation reduced MDI induced-Akt/mTOR phosphorylation and expression of cell cycle proteins, and thereby halted mitotic clonal expansion, the decisive factor in early adipogenesis. Further, its anti-adipogenic activity was validated in murine mesenchymal cell-line C3H10T1/2 and human mesenchymal stem cell models of adipogenic differentiation. When compound 1 was administered along with HFD, for another 8 weeks in 2 month HFD fed overweight mice (with BMI > 30 and impaired glucose tolerance), it attenuated weight gain and epididymal fat accumulation. It improved body glucose tolerance, reduced HFD induced increase in total cholesterol and leptin/adiponectin ratio. All these effects were comparable with standard anti-obesity drug Orlistat with added edge of potently decreasing circulating triglyceride levels comparable with normal chow fed group. Histological analysis shows that compound 1 inhibit adipocyte hypertrophy and decreased steatosis in hepatocytes. Both in vivo and in vitro results demonstrate a potential value of compound 1 as a novel anti-adipogenic and anti-obesity agent.
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Affiliation(s)
- Muheeb Beg
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Kripa Shankar
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Salil Varshney
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Sujith Rajan
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific and Innovative Research, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Suriya Pratap Singh
- Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Pankaj Jagdale
- Pathology Laboratories, CSIR-Indian Institute of Toxicology Research, M.G. Road, Lucknow 226001, India
| | - Anju Puri
- Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Bhushan P Chaudhari
- Pathology Laboratories, CSIR-Indian Institute of Toxicology Research, M.G. Road, Lucknow 226001, India
| | - Koneni V Sashidhara
- Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India.
| | - Anil Nilkanth Gaikwad
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific and Innovative Research, CSIR-Central Drug Research Institute, Lucknow 226031, India.
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27
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Seo MJ, Choi HS, Jeon HJ, Woo MS, Lee BY. Baicalein inhibits lipid accumulation by regulating early adipogenesis and m-TOR signaling. Food Chem Toxicol 2014; 67:57-64. [PMID: 24560969 DOI: 10.1016/j.fct.2014.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/06/2014] [Accepted: 02/09/2014] [Indexed: 10/25/2022]
Abstract
Baicalein is a type of flavonoid that originates from Scutellaria baicalensis. In this study, we examined how baicalein inhibits lipid accumulation during adipogenesis in 3T3-L1 cells. Our data show that baicalein inhibited lipid accumulation during adipogenesis in a dose-dependent manner. Baicalein inhibition was limited to the early adipogenic stage. Cell cycle analysis showed that baicalein induced cell cycle arrest in the G0/G1 phase through cyclin downregulation. In addition, baicalein suppressed the mRNA expression of early adipogenic factors leading to downregulation of late adipogenic factors at mRNA and protein levels. Inhibition of adipogenic factors by baicalein was correlated with downregulation of lipid synthetic enzymes. Additionally, baicalein negatively regulated the m-TOR signaling pathway involved in lipid accumulation during adipogenesis, thus inhibiting phosphorylation of m-TOR and p70S6K. In a zebrafish study, baicalein significantly reduced lipid accumulation in Nile Red staining. Consistent with a report using cell lines, mRNA expression of adipogenic factors was decreased in a dose-dependent manner by baicalein. This result reflects a reduction in total triglyceride levels based on a triglyceride assay. Our data suggest that baicalein inhibits lipid accumulation by controlling the cell cycle and m-TOR signaling in 3T3-L1 cells, and its anti-adipogenic effect was found in a zebrafish model.
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Affiliation(s)
- Min-Jung Seo
- Department of Food Science and Biotechnology, CHA University, Kyonggi 463-836, South Korea
| | - Hyeon-Son Choi
- Department of Food Science and Biotechnology, CHA University, Kyonggi 463-836, South Korea
| | - Hui-Jeon Jeon
- Department of Food Science and Biotechnology, CHA University, Kyonggi 463-836, South Korea
| | - Mi-Seon Woo
- Department of Food Science and Biotechnology, CHA University, Kyonggi 463-836, South Korea
| | - Boo-Yong Lee
- Department of Food Science and Biotechnology, CHA University, Kyonggi 463-836, South Korea.
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28
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Yoon MS, Zhang C, Sun Y, Schoenherr CJ, Chen J. Mechanistic target of rapamycin controls homeostasis of adipogenesis. J Lipid Res 2013; 54:2166-2173. [PMID: 23740969 DOI: 10.1194/jlr.m037705] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Signaling mediated by the mechanistic target of rapamycin (mTOR) is believed to play a critical and positive role in adipogenesis, based on pharmacological evidence and genetic manipulation of mTOR regulators and targets. However, there is no direct genetic evidence for an autonomous role of mTOR itself in preadipocyte differentiation. To seek such evidence, we employed a conditional knockdown approach to deplete mTOR in preadipocytes. Surprisingly, while knockdown of S6K1, a target of mTOR, impairs 3T3-L1 preadipocyte differentiation, reduction of mTOR levels leads to increased differentiation. This enhanced adipogenesis requires the remaining mTOR activity, as mTOR inhibitors abolish differentiation in the mTOR knockdown cells. We also found that mTOR knockdown elevates the levels of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ). Furthermore, partial reduction of mTOR levels alleviates inhibition of Akt by mTORC1 via IRS1, while at the same time maintaining its positive input through mTORC1 into the adipogenic program. The greater sensitivity of the IRS1-Akt pathway to mTOR levels provides a mechanism that explains the net outcome of enhanced adipogenesis through PPARγ upon mTOR knockdown. Our observations reveal an unexpected role of mTOR in suppressing adipogenesis and suggest that mTOR governs the homeostasis of the adipogenic process by modulating multiple signaling pathways.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Chongben Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Yuting Sun
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Christopher J Schoenherr
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
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29
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Fernández-Veledo S, Vázquez-Carballo A, Vila-Bedmar R, Ceperuelo-Mallafré V, Vendrell J. Role of energy- and nutrient-sensing kinases AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) in adipocyte differentiation. IUBMB Life 2013; 65:572-83. [PMID: 23671028 DOI: 10.1002/iub.1170] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/14/2013] [Indexed: 12/14/2022]
Abstract
Recent advances have demonstrated that the adipose tissue plays a central role in regulating overall energy balance. Obesity results from a chronic deregulation of energy balance, with energy intake exceeding energy expenditure. Recently, new mechanisms that control the obesity phenotype such as the equilibrium between white and brown adipose tissue function has been identified. In this context, it is becoming increasingly clear that in addition to cellular growth, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) also regulate lipid metabolism and adipogenesis. Here, we review recent advances in the understanding of the molecular mechanisms involved in white and brown differentiation programs focusing on AMPK and mTOR signaling pathways, which may play differential roles in white adipose tissue and brown adipose tissue development. In view of the worldwide epidemic of obesity and its associated metabolic disorders such as insulin resistance and type 2 diabetes, targeting these kinases may represent a potential approach for reducing adiposity and improving obesity-related diseases. © 2013 IUBMB Life, 65(7):572-583, 2013.
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Affiliation(s)
- Sonia Fernández-Veledo
- Research Unit, Hospital Universitari de Tarragona Joan XXIII. IISPV. Universitat Rovira i Virgili, Tarragona, Spain
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30
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Laplante M, Sabatini DM. Regulation of mTORC1 and its impact on gene expression at a glance. J Cell Sci 2013; 126:1713-9. [PMID: 23641065 DOI: 10.1242/jcs.125773] [Citation(s) in RCA: 437] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mechanistic (or mammalian) target of rapamycin (mTOR) is a kinase that regulates key cellular functions linked to the promotion of cell growth and metabolism. This kinase, which is part of two protein complexes termed mTOR complex 1 (mTORC1) and 2 (mTORC2), has a fundamental role in coordinating anabolic and catabolic processes in response to growth factors and nutrients. Of the two mTOR complexes, mTORC1 is by far the best characterized. When active, mTORC1 triggers cell growth and proliferation by promoting protein synthesis, lipid biogenesis, and metabolism, and by reducing autophagy. The fact that mTORC1 deregulation is associated with several human diseases, such as type 2 diabetes, cancer, obesity and neurodegeneration, highlights its importance in the maintenance of cellular homeostasis. Over the last years, several groups observed that mTORC1 inhibition, in addition to reducing protein synthesis, deeply affects gene transcription. Here, we review the connections between mTORC1 and gene transcription by focusing on its impact in regulating the activation of specific transcription factors including including STAT3, SREBPs, PPARγ, PPARα, HIF1α, YY1–PGC1α and TFEB. We also discuss the importance of these transcription factors in mediating the effects of mTORC1 on various cellular processes in physiological and pathological contexts.
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Affiliation(s)
- Mathieu Laplante
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, 2725 Chemin Ste-Foy, Québec, QC, G1V 4G5, Canada.
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31
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Li X, Wang X, Liu R, Ma Y, Guo H, Hao L, Yao P, Liu L, Sun X, He K, Cao W, Yang X. Chronic leucine supplementation increases body weight and insulin sensitivity in rats on high-fat diet likely by promoting insulin signaling in insulin-target tissues. Mol Nutr Food Res 2013; 57:1067-79. [DOI: 10.1002/mnfr.201200311] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 12/02/2012] [Accepted: 12/29/2012] [Indexed: 01/08/2023]
Affiliation(s)
- Xiang Li
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | - Xiaolei Wang
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | | | - Yan Ma
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | - Huailan Guo
- Department of Preventive Medicine; Hubei University of Medicine; Shiyan; Hubei; P. R. China
| | - Liping Hao
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | - Ping Yao
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | - Liegang Liu
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | - Xiufa Sun
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
| | - Ka He
- Department of Nutrition; Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill; Chapel Hill; NC; USA
| | - Wenhong Cao
- Department of Nutrition; Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill; Chapel Hill; NC; USA
| | - Xuefeng Yang
- Department of Nutrition and Food Hygiene and MOE Key Laboratory of Environment and Health; School of Public Health, Tongji Medical College, Huazhong University of Science and Technology; Wuhan; Hubei; P. R. China
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32
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Abstract
The target of rapamycin (TOR) is a highly conserved serine/threonine kinase that is part of two structurally and functionally distinct complexes, TORC1 and TORC2. In multicellular organisms, TOR regulates cell growth and metabolism in response to nutrients, growth factors and cellular energy. Deregulation of TOR signaling alters whole body metabolism and causes age-related disease. This review describes the most recent advances in TOR signaling with a particular focus on mammalian TOR (mTOR) in metabolic tissues vis-a-vis aging, obesity, type 2 diabetes, and cancer.
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Affiliation(s)
- Marion Cornu
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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33
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Cornu M, Albert V, Hall MN. mTOR in aging, metabolism, and cancer. Curr Opin Genet Dev 2013; 23:53-62. [PMID: 23317514 DOI: 10.1016/j.gde.2012.12.005] [Citation(s) in RCA: 354] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 12/04/2012] [Accepted: 12/12/2012] [Indexed: 12/19/2022]
Abstract
The target of rapamycin (TOR) is a highly conserved serine/threonine kinase that is part of two structurally and functionally distinct complexes, TORC1 and TORC2. In multicellular organisms, TOR regulates cell growth and metabolism in response to nutrients, growth factors and cellular energy. Deregulation of TOR signaling alters whole body metabolism and causes age-related disease. This review describes the most recent advances in TOR signaling with a particular focus on mammalian TOR (mTOR) in metabolic tissues vis-a-vis aging, obesity, type 2 diabetes, and cancer.
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Affiliation(s)
- Marion Cornu
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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34
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Laplante M, Horvat S, Festuccia WT, Birsoy K, Prevorsek Z, Efeyan A, Sabatini DM. DEPTOR cell-autonomously promotes adipogenesis, and its expression is associated with obesity. Cell Metab 2012; 16:202-12. [PMID: 22883231 PMCID: PMC3463374 DOI: 10.1016/j.cmet.2012.07.008] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 03/20/2012] [Accepted: 07/17/2012] [Indexed: 02/05/2023]
Abstract
DEP domain-containing mTOR-interacting protein (DEPTOR) inhibits the mechanistic target of rapamycin (mTOR), but its in vivo functions are unknown. Previous work indicates that Deptor is part of the Fob3a quantitative trait locus (QTL) linked to obesity/leanness in mice, with Deptor expression being elevated in white adipose tissue (WAT) of obese animals. This relation is unexpected, considering the positive role of mTOR in adipogenesis. Here, we dissected the Fob3a QTL and show that Deptor is the highest-priority candidate promoting WAT expansion in this model. Consistently, transgenic mice overexpressing DEPTOR accumulate more WAT. Furthermore, in humans, DEPTOR expression in WAT correlates with the degree of obesity. We show that DEPTOR is induced by glucocorticoids during adipogenesis and that its overexpression promotes, while its suppression blocks, adipogenesis. DEPTOR activates the proadipogenic Akt/PKB-PPAR-γ axis by dampening mTORC1-mediated feedback inhibition of insulin signaling. These results establish DEPTOR as a new regulator of adipogenesis.
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Affiliation(s)
- Mathieu Laplante
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
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35
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Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway senses and integrates a variety of environmental cues to regulate organismal growth and homeostasis. The pathway regulates many major cellular processes and is implicated in an increasing number of pathological conditions, including cancer, obesity, type 2 diabetes, and neurodegeneration. Here, we review recent advances in our understanding of the mTOR pathway and its role in health, disease, and aging. We further discuss pharmacological approaches to treat human pathologies linked to mTOR deregulation.
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36
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The multifaceted role of mTORC1 in the control of lipid metabolism. EMBO Rep 2012; 14:242-51. [PMID: 23399656 DOI: 10.1038/embor.2013.5] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 01/16/2013] [Indexed: 02/06/2023] Open
Abstract
The mechanistic target of rapamycin is a protein kinase that, as part of the mechanistic target of rapamycin complex 1 (mTORC1), senses both local nutrients and, through insulin signalling, systemic nutrients to control a myriad of cellular processes. Although roles for mTORC1 in promoting protein synthesis and inhibiting autophagy in response to nutrients have been well established, it is emerging as a central regulator of lipid homeostasis. Here, we discuss the growing genetic and pharmacological evidence demonstrating the functional importance of its signalling in controlling mammalian lipid metabolism, including lipid synthesis, oxidation, transport, storage and lipolysis, as well as adipocyte differentiation and function. Defining the role of mTORC1 signalling in these metabolic processes is crucial to understanding the pathophysiology of obesity and its relationship to complex diseases, including diabetes and cancer.
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Abstract
The Peutz-Jeghers syndrome (PJS) culprit kinase LKB1 phosphorylates and activates multiple intracellular kinases regulating cell metabolism and polarity. The relevance of each of these pathways is highly variable depending on the tissue type, but typically represents functions of differentiated cells. These include formation and maintenance of specialized cell compartments in nerve axons, swift refunneling of metabolites and restructuring of cell architecture in response to environmental cues in committed lymphocytes, and ensuring energy-efficient oxygen-based energy expenditure. Such features are often lost or reduced in cancer cells, and indeed LKB1 defects in PJS-associated and sporadic cancers and even the benign PJS polyps lead to differentiation defects, including expansion of partially differentiated epithelial cells in PJS polyps and epithelial-to-mesenchymal transition in carcinomas. This review focuses on the involvement of LKB1 in the differentiation of epithelial, mesenchymal, hematopoietic and germinal lineages.
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Affiliation(s)
- Lina Udd
- Institute of Biotechnology and Genome-Scale Biology Research Program, University of Helsinki, P.O. Box 56 (Biocenter 1), 00014, Helsinki, Finland
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38
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Kim MK, Yang S, Lee KH, Um JH, Liu M, Kang H, Park SJ, Chung JH. Promyelocytic leukemia inhibits adipogenesis, and loss of promyelocytic leukemia results in fat accumulation in mice. Am J Physiol Endocrinol Metab 2011; 301:E1130-42. [PMID: 21846906 PMCID: PMC3233778 DOI: 10.1152/ajpendo.00092.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The function of the tumor suppressor promyelocytic leukemia (PML) protein is disrupted in promyelocytic leukemia. PML has been reported to function as a negative regulator of mTOR (mammalian target of rapamycin) and nuclear Akt under some conditions. mTOR and Akt pathways regulate a diverse array of pathways, including those that control insulin signaling, energy metabolism, growth, cellular survival, and lifespan. Although the PML-mTOR/Akt link suggests that PML may have metabolic functions in the whole organism, very little is known about the metabolic functions of PML. Here we report that PML(-/-) mice did not show any significant metabolic defects. There was no impairment in the mTOR/Akt or AMPK signaling in white adipose tissue, liver, or muscle. However, despite having normal food intake and activity levels, PML(-/-) mice gained body weight faster and had more fat mass, particularly subcutaneous fat mass, in the diet-induced obesity model. Using in vitro adipogenesis models, we discovered that PML is a suppressor of adipogenesis. PML expression decreased during adipogenesis and was undetectable in fully differentiated adipocytes. Loss of PML increased expression of the adipogenic transcription factors CCAAT/enhancer binding protein-α and peroxisome proliferator-activated receptor-γ. We found that the Sirt1-NCor-SMRT corepressor complex, which represses pparg transcription, does not bind to the pparg promoter efficiently upon PML depletion. On the basis of these findings, we propose that PML is a negative regulator of the adipogenic transcription factors and that, in times of energy excess, PML may limit fat accumulation by suppressing the differentiation of preadipocytes into adipocytes.
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Affiliation(s)
- Myung K Kim
- Laboratory of Obesity and Aging Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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39
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Tormos KV, Anso E, Hamanaka RB, Eisenbart J, Joseph J, Kalyanaraman B, Chandel NS. Mitochondrial complex III ROS regulate adipocyte differentiation. Cell Metab 2011; 14:537-44. [PMID: 21982713 PMCID: PMC3190168 DOI: 10.1016/j.cmet.2011.08.007] [Citation(s) in RCA: 499] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 06/10/2011] [Accepted: 08/06/2011] [Indexed: 12/21/2022]
Abstract
Adipocyte differentiation is characterized by an increase in mitochondrial metabolism. However, it is not known whether the increase in mitochondrial metabolism is essential for differentiation or a byproduct of the differentiation process. Here, we report that primary human mesenchymal stem cells undergoing differentiation into adipocytes display an early increase in mitochondrial metabolism, biogenesis, and reactive oxygen species (ROS) generation. This early increase in mitochondrial metabolism and ROS generation was dependent on mTORC1 signaling. Mitochondrial-targeted antioxidants inhibited adipocyte differentiation, which was rescued by the addition of exogenous hydrogen peroxide. Genetic manipulation of mitochondrial complex III revealed that ROS generated from this complex is required to initiate adipocyte differentiation. These results indicate that mitochondrial metabolism and ROS generation are not simply a consequence of differentiation but are a causal factor in promoting adipocyte differentiation.
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Affiliation(s)
- Kathryn V Tormos
- Division of Pulmonary and Critical Care, Department of Medicine, Northwestern University Medical School, Chicago, IL 60611, USA
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40
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Howell JJ, Manning BD. mTOR couples cellular nutrient sensing to organismal metabolic homeostasis. Trends Endocrinol Metab 2011; 22:94-102. [PMID: 21269838 PMCID: PMC3744367 DOI: 10.1016/j.tem.2010.12.003] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 12/21/2010] [Accepted: 12/29/2010] [Indexed: 02/08/2023]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) has the ability to sense a variety of essential nutrients and respond by altering cellular metabolic processes. Hence, this protein kinase complex is poised to influence adaptive changes to nutrient fluctuations toward the maintenance of whole-body metabolic homeostasis. Defects in mTORC1 regulation, arising from either physiological or genetic conditions, are believed to contribute to the metabolic dysfunction underlying a variety of human diseases, including type 2 diabetes. We are just now beginning to gain insights into the complex tissue-specific functions of mTORC1. In this review, we detail the current knowledge of the physiological functions of mTORC1 in controlling systemic metabolism, with a focus on advances obtained through genetic mouse models.
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Affiliation(s)
| | - Brendan D. Manning
- Correspondence to: 665 Huntington Ave., SPH2-117, Boston, MA 02115, Phone: 617 432-5614, Fax: 617 432-5236,
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Zoncu R, Efeyan A, Sabatini DM. mTOR: from growth signal integration to cancer, diabetes and ageing. Nat Rev Mol Cell Biol 2010; 12:21-35. [PMID: 21157483 DOI: 10.1038/nrm3025] [Citation(s) in RCA: 3060] [Impact Index Per Article: 218.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In all eukaryotes, the target of rapamycin (TOR) signalling pathway couples energy and nutrient abundance to the execution of cell growth and division, owing to the ability of TOR protein kinase to simultaneously sense energy, nutrients and stress and, in metazoans, growth factors. Mammalian TOR complex 1 (mTORC1) and mTORC2 exert their actions by regulating other important kinases, such as S6 kinase (S6K) and Akt. In the past few years, a significant advance in our understanding of the regulation and functions of mTOR has revealed the crucial involvement of this signalling pathway in the onset and progression of diabetes, cancer and ageing.
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Affiliation(s)
- Roberto Zoncu
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, Massachusetts 02142, USA
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42
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Veilleux A, Houde VP, Bellmann K, Marette A. Chronic inhibition of the mTORC1/S6K1 pathway increases insulin-induced PI3K activity but inhibits Akt2 and glucose transport stimulation in 3T3-L1 adipocytes. Mol Endocrinol 2010; 24:766-78. [PMID: 20203102 DOI: 10.1210/me.2009-0328] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC)1 pathway has emerged as a critical signaling component in the modulation of insulin's metabolic action. This effect is triggered by a nutrient- and insulin-mediated negative feedback loop in which mTOR and S6 kinase (S6K)1 phosphorylate insulin receptor substrate (IRS)-1 on serine residues, which blunts phosphatidylinositol 3-kinase (PI3K) activation. Acute inhibition of mTORC1/S6K1 by rapamycin increases insulin signaling and glucose uptake in myocytes and adipocytes, but whether these effects can be maintained under chronic inhibition of mTORC1 or S6K1 remains unclear. Here, we analyzed the effect of chronic rapamycin inhibition or small interfering RNA-based down-regulation of specific elements of the mTORC1/S6K1 pathway on insulin signaling and glucose transport in adipocytes. Both chronic inhibition of mTORC1 by rapamycin or knockdown of either mTOR, raptor, or S6K1 reduced inhibitory serine phosphorylation of IRS-1, while increasing its insulin-stimulated tyrosine phosphorylation and associated PI3K activity. However, knockdown of either mTOR or raptor selectively blunted IRS-1 phosphorylation on Ser636/639, whereas only S6K1 knockdown was found to reduce phosphorylation of IRS-1 on Ser1101. Unexpectedly, insulin-induced activation of Akt2 and glucose transporter 4 expression were reduced after chronic disruption of the mTORC1/S6K1 pathway, impairing insulin-mediated glucose uptake despite increased PI3K activation. In conclusion, these data indicate that both mTORC1 and S6K1 are key elements of the negative feedback loop but inhibit insulin-induced PI3K activity through phosphorylation of specific serine residues in IRS-1. However, this study also shows that chronic inhibition of the mTORC1/S6K1 pathway uncouples IRS-1/PI3K signaling from insulin-induced glucose transport due to impaired activation of Akt2 and blunted glucose transporter 4 expression.
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Affiliation(s)
- Alain Veilleux
- Department of Medicine, Faculty of Medicine, Laval University Hospital Research Center, Québec, Canada
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Vila-Bedmar R, Lorenzo M, Fernández-Veledo S. Adenosine 5'-monophosphate-activated protein kinase-mammalian target of rapamycin cross talk regulates brown adipocyte differentiation. Endocrinology 2010; 151:980-92. [PMID: 20133456 DOI: 10.1210/en.2009-0810] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Brown adipose tissue (BAT) is considered of metabolic significance in mammalian physiology, because it plays an important role in regulating energy balance. Alterations in this tissue have been associated with obesity and type 2 diabetes. The molecular mechanisms modulating brown adipocyte differentiation are not fully understood. Using a murine brown preadipocyte cell line, primary cultures, and 3T3-L1 cells, we analyzed the contribution of various intracellular signaling pathways to adipogenic and thermogenic programs. Sequential activation of p38MAPK and LKB1-AMPK-tuberous sclerosis complex 2 (TSC2) as well as significant attenuation of ERK1/2 and mammalian target of rapamycin (mTOR)-p70 S6 kinase 1 (p70S6K1) activation was observed through the brown differentiation process. This study demonstrates a critical role for AMPK in controlling the mTOR-p70S6K1 signaling cascade in brown but not in 3T3-L1 adipocytes. We observed that mTOR activity is essential in the first stages of differentiation. Nevertheless, subsequent inhibition of this cascade by AMPK activation is also necessary at later stages. An in vivo study showed that prolonged 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR)-induced AMPK activation increases uncoupling protein 1 expression and induces an accumulation of brown adipocytes in white adipose tissue (WAT), as revealed by immunohistology. Moreover, the induction of brown adipogenesis in areas of white fat partially correlates with the body weight reduction detected in response to treatment with AICAR. Taken together, our study reveals that differentiation of brown adipocytes employs different signaling pathways from white adipocytes, with AMPK-mTOR cross talk a central mediator of this process. Promotion of BAT development in WAT by pharmacological activation of AMPK may have potential in treating obesity by acting on energy dissipation.
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Affiliation(s)
- Rocio Vila-Bedmar
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, Complutense University, 28040 Madrid, Spain
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44
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Abstract
Lipid biosynthesis is essential for the maintenance of cellular homeostasis. The lipids produced by cells (glycerolipids, fatty acids, phospholipids, cholesterol, and sphingolipids) are used as an energy source/reserve, as building blocks for membrane biosynthesis, as precursor molecules for the synthesis of various cellular products, and as signaling molecules. Defects in lipid synthesis or processing contribute to the development of many diseases, including obesity, insulin resistance, type 2 diabetes, non-alcoholic fatty liver disease, and cancer. Studies published over the last few years have shown that the target of rapamycin (TOR), a conserved serine/threonine kinase with an important role in regulating cell growth, controls lipid biosynthesis through various mechanisms. Here, we review these findings and briefly discuss their potential relevance for human health and disease.
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Affiliation(s)
- Mathieu Laplante
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
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Roles of Ets-1 and p70S6 kinase in chondrogenic and gliogenic specification of mouse mesencephalic neural crest cells. Mech Dev 2010; 127:169-82. [PMID: 20085809 DOI: 10.1016/j.mod.2010.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 01/06/2010] [Accepted: 01/08/2010] [Indexed: 01/03/2023]
Abstract
Fibroblast growth factors (FGFs) have been shown to promote the chondrogenic and gliogenic specification of mouse mesencephalic neural crest cells through Notch signaling [Nakanishi, K., Chan, S.Y., Ito, K., 2007. Notch signaling is required for the chondrogenic specification of mouse mesencephalic neural crest cells. Mech. Dev. 124, 190-203; Ijuin, K., Nakanishi, K., Ito, K., 2008. Different downstream pathways for Notch signaling are required for gliogenic and chondrogenic specification of mouse mesencephalic neural crest cells. Mech. Dev. 125, 462-474]. In the present study, we analyzed FGF signaling pathways in chondrogenic and gliogenic specification. The promotion of chondrogenesis by FGF-2 was significantly suppressed by U0126, an inhibitor of the extracellular signal-regulated protein kinase (Erk) pathway, and by Erk-1 siRNA. Chondrogenesis was also prevented by the dominant negative Ets-1 expression vector. In contrast, Ets-1 was irrelevant to gliogenesis. The promotion of gliogenesis by FGF-2 was not only inhibited by U0126 but also by LY294002 and rapamycin, inhibitors of the Akt pathway, and by Akt-1 siRNA. Furthermore, gliogenesis was dramatically prevented by blocking the expression of p70S6 kinase (p70S6k), which is activated by both the Erk and Akt pathways, with p70S6k siRNA. These results suggest that Ets-1 activated by the Erk pathway promotes chondrogenic specification and p70S6k activated by both the Erk and Akt pathways plays an important role in gliogenic specification.
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Insulin stimulates adipogenesis through the Akt-TSC2-mTORC1 pathway. PLoS One 2009; 4:e6189. [PMID: 19593385 PMCID: PMC2703782 DOI: 10.1371/journal.pone.0006189] [Citation(s) in RCA: 280] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 06/06/2009] [Indexed: 01/19/2023] Open
Abstract
Background The signaling pathways imposing hormonal control over adipocyte differentiation are poorly understood. While insulin and Akt signaling have been found previously to be essential for adipogenesis, the relative importance of their many downstream branches have not been defined. One direct substrate that is inhibited by Akt-mediated phosphorylation is the tuberous sclerosis complex 2 (TSC2) protein, which associates with TSC1 and acts as a critical negative regulator of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1). Loss of function of the TSC1-TSC2 complex results in constitutive mTORC1 signaling and, through mTORC1-dependent feedback mechanisms and loss of mTORC2 activity, leads to a concomitant block of Akt signaling to its other downstream targets. Methodology/Principal Findings We find that, despite severe insulin resistance and the absence of Akt signaling, TSC2-deficient mouse embryo fibroblasts and 3T3-L1 pre-adipocytes display enhanced adipocyte differentiation that is dependent on the elevated mTORC1 activity in these cells. Activation of mTORC1 causes a robust increase in the mRNA and protein expression of peroxisome proliferator-activated receptor gamma (PPARγ), which is the master transcriptional regulator of adipocyte differentiation. In examining the requirements for different Akt-mediated phosphorylation sites on TSC2, we find that only TSC2 mutants lacking all five previously identified Akt sites fully block insulin-stimulated mTORC1 signaling in reconstituted Tsc2 null cells, and this mutant also inhibits adipogenesis. Finally, renal angiomyolipomas from patients with tuberous sclerosis complex contain both adipose and smooth muscle-like components with activated mTORC1 signaling and elevated PPARγ expression. Conclusions/Significance This study demonstrates that activation of mTORC1 signaling is a critical step in adipocyte differentiation and identifies TSC2 as a primary target of Akt driving this process. Therefore, the TSC1-TSC2 complex regulates the differentiation of mesenchymal cell lineages, at least in part, through its control of mTORC1 activity and PPARγ expression.
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Rokutanda S, Fujita T, Kanatani N, Yoshida CA, Komori H, Liu W, Mizuno A, Komori T. Akt regulates skeletal development through GSK3, mTOR, and FoxOs. Dev Biol 2009; 328:78-93. [DOI: 10.1016/j.ydbio.2009.01.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 12/24/2008] [Accepted: 01/06/2009] [Indexed: 11/24/2022]
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48
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Stallone G, Infante B, Pontrelli P, Ranieri E, Loverre A, Schena A, Cormio L, Carrieri G, Schena FP, Grandaliano G, Gesualdo L. ID2-VEGF-related pathways in the pathogenesis of Kaposi's sarcoma: a link disrupted by rapamycin. Am J Transplant 2009; 9:558-66. [PMID: 19260835 DOI: 10.1111/j.1600-6143.2008.02537.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Id-proteins are a family of four related proteins implicated in the control of differentiation and cell-cycle progression. Down-regulation of Id-gene expression is essential for the differentiation of several cell types. In addition, deregulated Id2 activity inhibits the Rb tumor suppressor pathway and promotes the expression of vascular endothelial growth factor (VEGF). Several members of VEGF family could be involved in Kaposi's sarcoma (KS) development and progression. Lymphatic vascular endothelial hyaluronan receptor-1 (LYVE-1) is the first marker of lymphatic endothelial competence during development in the mature vasculature, and is also expressed on KS spindle cells. Rapamycin (RAPA), an immunosuppressive drug, has been shown to reverse KS growth and to reduce tumor angiogenesis. We evaluate, in transplantation-associated KS and in cultured KS-cells the RAPA effect on Id2 and on de novo lymphangiogenesis. Markers of lymphatic-endothelial-cells (VEGFR-3, LYVE-1) and Id2, expressed at low levels within the normal skin, were up-regulated in KS and returned to normal levels after RAPA introduction. The association between Id2 and lymphangiogenesis is suggested by co-localization of Id2, VEGFR-3 and LYVE-1. RAPA inhibition on Id2 expression was confirmed in vitro in KS-cells, both in basal conditions and upon stimulation with VEGF. In conclusion, our data would suggest a novel molecular mechanism for the antineoplastic effects of RAPA in posttransplant KS.
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Affiliation(s)
- G Stallone
- Department of Biomedical Sciences, Section of Nephrology, University of Foggia, Italy.
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Hegner B, Lange M, Kusch A, Essin K, Sezer O, Schulze-Lohoff E, Luft FC, Gollasch M, Dragun D. mTOR regulates vascular smooth muscle cell differentiation from human bone marrow-derived mesenchymal progenitors. Arterioscler Thromb Vasc Biol 2008; 29:232-8. [PMID: 19074484 DOI: 10.1161/atvbaha.108.179457] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE Vascular smooth muscle cells (VSMCs) and circulating mesenchymal progenitor cells (MSCs) with a VSMC phenotype contribute to neointima formation and lumen loss after angioplasty and during allograft arteriosclerosis. We hypothesized that phosphoinositol-Akt-mammalian target of rapamycin-p70S6 kinase (PI3K/Akt/mTOR/p70S6K) pathway activation regulates VSMC differentiation from MSCs. METHODS AND RESULTS We studied effects of PI3K/Akt/mTOR signaling on phenotypic modulation of MSC and VSMC marker expression, including L-type Ca(2+) channels. Phosphorylation of Akt and p70S6K featured downregulation of VSMC markers in dedifferentiated MSCs. mTOR inhibition with rapamycin at below pharmacological concentrations blocked p70S6K phosphorylation and induced a differentiated contractile phenotype with smooth muscle (sm)-calponin, sm-alpha-actin, and SM protein 22-alpha (SM22alpha) expression. The PI3K inhibitor Ly294002 abolished Akt and p70S6K phosphorylation and reversed the dedifferentiated phenotype via induction of sm-calponin, sm-alpha-actin, SM22alpha, and myosin light chain kinase. Rapamycin acted antiproliferative without impairing MSC viability. In VSMCs, rapamycin increased a homing chemokine for MSCs, stromal cell-derived factor-1-alpha, at mRNA and protein levels. The CXCR4-mediated MSC migration toward conditioned medium of rapamycin-treated VSMCs was enhanced. CONCLUSIONS We describe novel pleiotropic effects of rapamycin at very low concentrations that stabilized differentiated contractile VSMCs from MSCs in addition to exerting antiproliferative and enhanced homing effects.
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Affiliation(s)
- Björn Hegner
- Clinic for Nephrology and Intensive Care Medicine, Charité Campus Virchow Klinihum, Augustenburger Platz 1, 13353 Berlin, Germany
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Polak P, Cybulski N, Feige JN, Auwerx J, Rüegg MA, Hall MN. Adipose-specific knockout of raptor results in lean mice with enhanced mitochondrial respiration. Cell Metab 2008; 8:399-410. [PMID: 19046571 DOI: 10.1016/j.cmet.2008.09.003] [Citation(s) in RCA: 388] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 08/04/2008] [Accepted: 09/09/2008] [Indexed: 12/14/2022]
Abstract
raptor is a specific and essential component of mammalian TOR complex 1 (mTORC1), a key regulator of cell growth and metabolism. To investigate a role of adipose mTORC1 in regulation of adipose and whole-body metabolism, we generated mice with an adipose-specific knockout of raptor (raptor(ad-/-)). Compared to control littermates, raptor(ad-/-) mice had substantially less adipose tissue, were protected against diet-induced obesity and hypercholesterolemia, and exhibited improved insulin sensitivity. Leanness was in spite of reduced physical activity and unaffected caloric intake, lipolysis, and absorption of lipids from the food. White adipose tissue of raptor(ad-/-) mice displayed enhanced expression of genes encoding mitochondrial uncoupling proteins characteristic of brown fat. Leanness of the raptor(ad-/-) mice was attributed to elevated energy expenditure due to mitochondrial uncoupling. These results suggest that adipose mTORC1 is a regulator of adipose metabolism and, thereby, controls whole-body energy homeostasis.
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Affiliation(s)
- Pazit Polak
- Biozentrum, University of Basel, Basel, CH-4056, Switzerland
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