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Tang C, Wang Y, Chen D, Zhang M, Xu J, Xu C, Liu J, Kan J, Jin C. Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system. Food Res Int 2023; 172:113192. [PMID: 37689942 DOI: 10.1016/j.foodres.2023.113192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/25/2023] [Accepted: 06/27/2023] [Indexed: 09/11/2023]
Abstract
Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.
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Affiliation(s)
- Chao Tang
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Yuxin Wang
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Dan Chen
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Man Zhang
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Jingguo Xu
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Chen Xu
- Nanjing Key Laboratory of Quality and safety of agricultural product, Nanjing Xiaozhuang University, Nanjing 211171, China.
| | - Jun Liu
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Juan Kan
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Changhai Jin
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
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Glassman I, Le N, Asif A, Goulding A, Alcantara CA, Vu A, Chorbajian A, Mirhosseini M, Singh M, Venketaraman V. The Role of Obesity in Breast Cancer Pathogenesis. Cells 2023; 12:2061. [PMID: 37626871 PMCID: PMC10453206 DOI: 10.3390/cells12162061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 08/03/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023] Open
Abstract
Research has shown that obesity increases the risk for type 2 diabetes mellitus (Type 2 DM) by promoting insulin resistance, increases serum estrogen levels by the upregulation of aromatase, and promotes the release of reactive oxygen species (ROS) by macrophages. Increased circulating glucose has been shown to activate mammalian target of rapamycin (mTOR), a significant signaling pathway in breast cancer pathogenesis. Estrogen plays an instrumental role in estrogen-receptor-positive breast cancers. The role of ROS in breast cancer warrants continued investigation, in relation to both pathogenesis and treatment of breast cancer. We aim to review the role of obesity in breast cancer pathogenesis and novel therapies mediating obesity-associated breast cancer development. We explore the association between body mass index (BMI) and breast cancer incidence and the mechanisms by which oxidative stress modulates breast cancer pathogenesis. We discuss the role of glutathione, a ubiquitous antioxidant, in breast cancer therapy. Lastly, we review breast cancer therapies targeting mTOR signaling, leptin signaling, blood sugar reduction, and novel immunotherapy targets.
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Affiliation(s)
- Ira Glassman
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Nghia Le
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Aamna Asif
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Anabel Goulding
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Cheldon Ann Alcantara
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Annie Vu
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Abraham Chorbajian
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Mercedeh Mirhosseini
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
| | - Manpreet Singh
- Corona Regional Medical Center, Department of Emergency Medicine, Corona, CA 92882, USA
| | - Vishwanath Venketaraman
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA (N.L.); (A.A.); (C.A.A.); (M.M.)
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Niranjan S, Phillips BE, Giannoukakis N. Uncoupling hepatic insulin resistance - hepatic inflammation to improve insulin sensitivity and to prevent impaired metabolism-associated fatty liver disease in type 2 diabetes. Front Endocrinol (Lausanne) 2023; 14:1193373. [PMID: 37396181 PMCID: PMC10313404 DOI: 10.3389/fendo.2023.1193373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/01/2023] [Indexed: 07/04/2023] Open
Abstract
Diabetes mellitus is a metabolic disease clinically-characterized as acute and chronic hyperglycemia. It is emerging as one of the common conditions associated with incident liver disease in the US. The mechanism by which diabetes drives liver disease has become an intense topic of discussion and a highly sought-after therapeutic target. Insulin resistance (IR) appears early in the progression of type 2 diabetes (T2D), particularly in obese individuals. One of the co-morbid conditions of obesity-associated diabetes that is on the rise globally is referred to as non-alcoholic fatty liver disease (NAFLD). IR is one of a number of known and suspected mechanism that underlie the progression of NAFLD which concurrently exhibits hepatic inflammation, particularly enriched in cells of the innate arm of the immune system. In this review we focus on the known mechanisms that are suspected to play a role in the cause-effect relationship between hepatic IR and hepatic inflammation and its role in the progression of T2D-associated NAFLD. Uncoupling hepatic IR/hepatic inflammation may break an intra-hepatic vicious cycle, facilitating the attenuation or prevention of NAFLD with a concurrent restoration of physiologic glycemic control. As part of this review, we therefore also assess the potential of a number of existing and emerging therapeutic interventions that can target both conditions simultaneously as treatment options to break this cycle.
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Affiliation(s)
- Sitara Niranjan
- Department of Internal Medicine, Allegheny Health Network, Pittsburgh, PA, United States
| | - Brett E. Phillips
- Department of Internal Medicine, Allegheny Health Network, Pittsburgh, PA, United States
| | - Nick Giannoukakis
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
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Liu X, Hou S, Xiang R, Hu C, Chen Z, Li N, Yan H, Yu X, Li X, Chi Y, Yang J. Imipramine activates FAM3A-FOXA2-CPT2 pathway to ameliorate hepatic steatosis. Metabolism 2022; 136:155292. [PMID: 35995281 DOI: 10.1016/j.metabol.2022.155292] [Citation(s) in RCA: 4] [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] [Received: 05/23/2022] [Revised: 07/19/2022] [Accepted: 08/12/2022] [Indexed: 10/31/2022]
Abstract
Mitochondrial FAM3A has been revealed to be a viable target for treating diabetes and nonalcoholic fatty liver disease (NAFLD). However, its distinct mechanism in ameliorating hepatic steatosis remained unrevealed. High-throughput RNA sequencing revealed that carnitine palmityl transferase 2 (CPT2), one of the key enzymes for lipid oxidation, is the downstream molecule of FAM3A signaling pathway in hepatocytes. Intensive study demonstrated that FAM3A-induced ATP release activated P2 receptor to promote the translocation of calmodulin (CaM) from cytoplasm into nucleus, where it functioned as a co-activator of forkhead box protein A2 (FOXA2) to promote the transcription of CPT2, increasing free fatty acid oxidation and reducing lipid deposition in hepatocytes. Furthermore, antidepressant imipramine activated FAM3A-ATP-P2 receptor-CaM-FOXA2-CPT2 pathway to reduce lipid deposition in hepatocytes. In FAM3A-deficient hepatocytes, imipramine failed to activate CaM-FOXA2-CPT2 axis to increase lipid oxidation. Imipramine administration significantly ameliorated hepatic steatosis, hyperglycemia and obesity of obese mice mainly by activating FAM3A-ATP-CaM-FOXA2-CPT2 pathway in liver and thermogenesis in brown adipose tissue (BAT). In FAM3A-deficient mice fed on high-fat-diet, imipramine treatment failed to correct the dysregulated lipid and glucose metabolism, and activate thermogenesis in BAT. In conclusion, imipramine activates FAM3A-ATP-CaM-FOXA2-CPT2 pathway to ameliorate steatosis. For depressive patients complicated with metabolic disorders, imipramine may be recommended in priority as antidepressive drug.
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Affiliation(s)
- Xiangyang Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Song Hou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Rui Xiang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Chengqing Hu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Zhenzhen Chen
- Hypertension Center, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Beijing 100037, China
| | - Na Li
- Department of Central Laboratory and Institute of Clinical Molecular Biology, Peking University People's Hospital, Beijing 100044, China
| | - Han Yan
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Xiaoxing Yu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Xin Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China
| | - Yujing Chi
- Department of Central Laboratory and Institute of Clinical Molecular Biology, Peking University People's Hospital, Beijing 100044, China.
| | - Jichun Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing 100191, China.
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LncRNA-MALAT1 Regulates Cancer Glucose Metabolism in Prostate Cancer via MYBL2/mTOR Axis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:8693259. [PMID: 35557985 PMCID: PMC9086835 DOI: 10.1155/2022/8693259] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/04/2022] [Accepted: 04/09/2022] [Indexed: 12/24/2022]
Abstract
It is known that the long noncoding RNAs (lncRNA) MALAT1 is associated with tumorigenesis and progression in various cancers; however, its functions and mechanisms in prostate cancer (PCa) initiation and progression are still unknown. In the present study, our findings revealed that MALAT1 plays a critical part in regulating PCa proliferation and glucose metabolism. Knockdown of MALAT1 affects the protein and mRNA levels of MYBL2. In addition, MALAT1 enhances the phosphorylation level of mTOR pathway by upregulating MYBL2. Knockdown of MALAT1 or MYBL2 in PCa cell lines significantly inhibits their proliferation capacity. Silencing MALAT1/MYBL2/mTOR axis in PCa cell lines affects their glycolysis and lactate levels, and we verified these findings in mice. Furthermore, we explored the underlying tumorigenesis functions of MYBL2 in PCa and found that high expression of MYBL2 was positively associated with TNM stage, Gleason score, PSA level, and poor survival rate in PCa patients. Taken together, our research suggests that MALAT1 controls cancer glucose metabolism and progression by upregulating MYBL2-mTOR axis.
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Wang W, Wang Z, Zhao Y, Wang X, Li H, Zhang Y. Analysis of serum lipid parameters predicting lipid metabolic disorders in TSC-AML patients with treatment of mTOR inhibitors. J Clin Pharm Ther 2022; 47:979-985. [PMID: 35229896 DOI: 10.1111/jcpt.13631] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 11/27/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE Patients with tuberous sclerosis complex (TSC) demonstrate disrupted lipid homeostasis before and during treatment with mammalian target of rapamycin (mTOR) inhibitor. However, few previous reports focused on if the serum lipid status at baseline would influence lipid metabolic side-effects of mTOR inhibitors for TSC associated renal angiomyolipomas (TSC-AML). The present study was designed to evaluate the predictive function of serum lipid status at baseline for hyperlipidaemia by mTOR inhibitor treatment in TSC-AML patients. METHODS The clinical data of TSC-AML patients who took mTOR inhibitors in Department of Urology of Peking Union Medical College Hospital (PUMCH) from 1 January 2014 to 1 January 2021, were retrospectively analysed. The record of lipid parameters at baseline and the highest levels of total cholesterol (TC) and triglyceride (TG) after treatment at least ≥3 months were collected. The correlation of serum lipid parameters at baseline with incidence of hyperlipidaemia during mTOR inhibitor treatment was analysed. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the ability of the serum lipid parameters in predicting hyperlipidaemia. RESULTS AND DISCUSSION 19 patients experienced hyperlipidaemia and 13 patients still had normal TC and TG levels during mTOR inhibitor treatment. The levels of high-density lipoprotein cholesterol (HDL-C) (0.98 ± 0.30 mmol/L vs. 1.23 ± 0.31 mmol/L, p = 0.030), low-density lipoprotein cholesterol (LDL-C) (2.47 ± 0.69 mmol/L vs. 1.95 ± 0.53 mmol/L, p = 0.029) and apolipoprotein B (ApoB) (0.82 ± 0.21 g/L vs. 0.65 ± 0.16 g/L, p = 0.019) are higher in the patients who experienced hyperlipidaemia during mTOR inhibition therapy. TC, TG, LDL-C, ApoB and high-sensitivity C-reactive protein (hsCRP) at baseline had positive correlation with TC after treatment; ApoB at baseline had positive correlation, while HDL-C and free fat acid (FFA) at baseline had negative correlation with TG after treatment. Therefore, ApoB concentration at baseline has statistically significant correlation with both TC (p < 0.001) and TG (p = 0.012) levels after mTOR inhibitor treatment. ROC curve and AUC revealed that ApoB with a cut-off value of 0.640g/L may be the best parameter for predicting hyperlipidaemia during mTOR inhibitor treatment in TSC-AML patients. The incidence rates of hyperlipidaemia were 27.3% and 76.2% among the patients with ApoB level ≤0.640 g/L and >0.640 g/L respectively. WHAT IS NEW AND CONCLUSION Some baseline serum lipid parameters could be used for predicting incidence of hyperlipidaemia during mTOR inhibition therapy in TSC-AML patients, and ApoB with 0.640 g/L as a cut-off value may be a potentially optimal indicator, which could help for diagnosis and treatment decision-making.
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Affiliation(s)
- Wenda Wang
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zhan Wang
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yang Zhao
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xu Wang
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hanzhong Li
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yushi Zhang
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Yang L, Zhang Z, Wang D, Jiang Y, Liu Y. Targeting mTOR Signaling in Type 2 Diabetes Mellitus and Diabetes Complications. Curr Drug Targets 2022; 23:692-710. [PMID: 35021971 DOI: 10.2174/1389450123666220111115528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/21/2021] [Accepted: 12/01/2021] [Indexed: 11/22/2022]
Abstract
The mechanistic target of rapamycin (mTOR) is a pivotal regulator of cell metabolism and growth. In the form of two different multi-protein complexes, mTORC1 and mTORC2, mTOR integrates cellular energy, nutrient and hormonal signals to regulate cellular metabolic homeostasis. In type 2 diabetes mellitus (T2DM) aberrant mTOR signaling underlies its pathological conditions and end-organ complications. Substantial evidence suggests that two mTOR-mediated signaling schemes, mTORC1-p70S6 kinase 1 (S6K1) and mTORC2-protein kinase B (AKT), play a critical role in insulin sensitivity and that their dysfunction contributes to development of T2DM. This review summaries our current understanding of the role of mTOR signaling in T2DM and its associated complications, as well as the potential use of mTOR inhibitors in treatment of T2DM.
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Affiliation(s)
- Lin Yang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Zhixin Zhang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Doudou Wang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Ying Liu
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
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Low molecular weight fucoidan fraction LF2 improves metabolic syndrome via up-regulating PI3K-AKT-mTOR axis and increasing the abundance of Akkermansia muciniphila in the gut microbiota. Int J Biol Macromol 2021; 193:789-798. [PMID: 34743939 DOI: 10.1016/j.ijbiomac.2021.10.188] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/14/2021] [Accepted: 10/24/2021] [Indexed: 12/20/2022]
Abstract
Metabolic syndrome (MetS) is a pathological condition of a variety of metabolic abnormalities, which requires more urgent treatment and intervention. Fucoidan has been recommended as a supplement for health enhancement and disease management. Here, we first propose that the beneficial effect of low molecular weight fucoidan fraction LF2 in regulating metabolic syndrome induced by high-fat diet is similar to that of metformin, in terms of molecular mechanism and gut microbiota. The study found that LF2 significantly reduces fasting blood glucose, enhances insulin sensitivity and restores insulin homeostasis and lipid homeostasis. Moreover, LF2 reduced liver oxidative stress and inflammation, and improved hepatocyte steatosis. To decipher the mechanism behind this therapeutic effect, both the molecular mechanisms and gut microbiota were further analyzed. LF2 inhibited the activation of PI3K-Akt-mTOR axis and decreased the expression of SREBP-1c and PPARγ in liver. Interestingly, we found that LF2 and metformin have similar effects on gut microbiota, increasing the proportion of Verrucomicrobia and enriching the abundance of Akkermansia muciniphila, which is beneficial to host health. Collectively, our research clarifies the new application of fucoidan as a functional food for anti-MetS, and provides a new insight for fucoidan to exert systemic therapeutic effects from the perspective of molecular mechanism and gut microbiota.
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Xiao F, Guo F. Impacts of essential amino acids on energy balance. Mol Metab 2021; 57:101393. [PMID: 34785395 PMCID: PMC8829800 DOI: 10.1016/j.molmet.2021.101393] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/24/2021] [Accepted: 11/08/2021] [Indexed: 12/12/2022] Open
Abstract
Background Obesity develops due to an imbalance in energy homeostasis, wherein energy intake exceeds energy expenditure. Accumulating evidence shows that manipulations of dietary protein and their component amino acids affect the energy balance, resulting in changes in fat mass and body weight. Amino acids are not only the building blocks of proteins but also serve as signals regulating multiple biological pathways. Scope of review We present the currently available evidence regarding the effects of dietary alterations of a single essential amino acid (EAA) on energy balance and relevant signaling mechanisms at both central and peripheral levels. We summarize the association between EAAs and obesity in humans and the clinical use of modifying the dietary EAA composition for therapeutic intervention in obesity. Finally, similar mechanisms underlying diets varying in protein levels and diets altered of a single EAA are described. The current review would expand our understanding of the contribution of protein and amino acids to energy balance control, thus helping discover novel therapeutic approaches for obesity and related diseases. Major Conclusions Changes in circulating EAA levels, particularly increased branched-chain amino acids (BCAAs), have been reported in obese human and animal models. Alterations in dietary EAA intake result in improvements in fat and weight loss in rodents, and each has its distinct mechanism. For example, leucine deprivation increases energy expenditure, reduces food intake and fat mass, primarily through regulation of the general control nonderepressible 2 (GCN2) and mammalian target of rapamycin (mTOR) signaling. Methionine restriction by 80% decreases fat mass and body weight while developing hyperphagia, primarily through fibroblast growth factor 21 (FGF-21) signaling. Some effects of diets with different protein levels on energy homeostasis are mediated by similar mechanisms. However, reports on the effects and underlying mechanisms of dietary EAA imbalances on human body weight are few, and more investigations are needed in future. Dietary Essential Amino Acids (EAA) alterations affect energy homeostasis via distinct mechanisms. Alterations in dietary EAA intake can reduce fat mass and body weight. Increased circulating BCAAs have been observed in obese human and animal models.
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Affiliation(s)
- Fei Xiao
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Innovation Center for Intervention of Chronic Disease and Promotion of Health, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Feifan Guo
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Innovation Center for Intervention of Chronic Disease and Promotion of Health, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China; Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China.
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Huwatibieke B, Yin W, Liu L, Jin Y, Xiang X, Han J, Zhang W, Li Y. Mammalian Target of Rapamycin Signaling Pathway Regulates Mitochondrial Quality Control of Brown Adipocytes in Mice. Front Physiol 2021; 12:638352. [PMID: 34335285 PMCID: PMC8317026 DOI: 10.3389/fphys.2021.638352] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 05/26/2021] [Indexed: 01/13/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an important protein kinase that senses changes in extracellular and intracellular energy levels and plays a key role in regulating energy metabolism. Brown adipose tissue, which can be converted to white adipose tissue, contains a large number of mitochondria and regulates energy expenditure through thermogenesis. Because obesity is a process of fat accumulation due to chronic excessive energy intake, we attempted to determine whether the mTOR signaling pathway can affect the mitochondrial quality control of brown adipocytes through sensing energy status, thereby regulating brown/white adipocyte transformation. In the present study, through activation or inhibition of mTOR signaling, we detected mitochondrial biogenesis, dynamics, and autophagy-related markers in brown adipocytes. We found that activation of mTOR signaling downregulated the expression of mitochondrial biogenesis, dynamics, and autophagy-relevant markers and inhibited the mitochondrial quality control of brown adipocytes, indicating a phenotypic transformation of brown to white adipocytes. In contrast, inhibition of mTOR signaling upregulated the expression of mitochondrial biogenesis, dynamics, and mitophagy-relevant markers and strengthened mitochondrial quality control, suggesting an inhibition of the phenotypic transformation of brown to white adipocytes. In conclusion, the mTOR signaling pathway plays an important role in modulating the transformation of adipocytes by regulating mitochondrial quality control.
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Affiliation(s)
- Bahetiyaer Huwatibieke
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Wenzhen Yin
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Lingchao Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Yuxin Jin
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China.,Department of Integration of Chinese and Western Medicine, Tasly Microcirculation Research Center, Peking University Health Science Center, Beijing, China
| | - Xinxin Xiang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China.,Department of Pathology, Central Hospital of Zibo, Zibo, China
| | - Jingyan Han
- Department of Integration of Chinese and Western Medicine, Tasly Microcirculation Research Center, Peking University Health Science Center, Beijing, China
| | - Weizhen Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Yin Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China.,Department of Integration of Chinese and Western Medicine, Tasly Microcirculation Research Center, Peking University Health Science Center, Beijing, China
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Zhang Z, Yang D, Xiang J, Zhou J, Cao H, Che Q, Bai Y, Guo J, Su Z. Non-shivering Thermogenesis Signalling Regulation and Potential Therapeutic Applications of Brown Adipose Tissue. Int J Biol Sci 2021; 17:2853-2870. [PMID: 34345212 PMCID: PMC8326120 DOI: 10.7150/ijbs.60354] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/23/2021] [Indexed: 12/25/2022] Open
Abstract
In mammals, thermogenic organs exist in the body that increase heat production and enhance energy regulation. Because brown adipose tissue (BAT) consumes energy and generates heat, increasing energy expenditure via BAT might be a potential strategy for new treatments for obesity and obesity-related diseases. Thermogenic differentiation affects normal adipose tissue generation, emphasizing the critical role that common transcriptional regulation factors might play in common characteristics and sources. An understanding of thermogenic differentiation and related factors could help in developing ways to improve obesity indirectly or directly through targeting of specific signalling pathways. Many studies have shown that the active components of various natural products promote thermogenesis through various signalling pathways. This article reviews recent major advances in this field, including those in the cyclic adenosine monophosphate-protein kinase A (cAMP-PKA), cyclic guanosine monophosphate-GMP-dependent protein kinase G (cGMP-AKT), AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), transforming growth factor-β/bone morphogenic protein (TGF-β/BMP), transient receptor potential (TRP), Wnt, nuclear factor-κ-light-chain-enhancer of activated B cells (NF-κΒ), Notch and Hedgehog (Hh) signalling pathways in brown and brown-like adipose tissue. To provide effective information for future research on weight-loss nutraceuticals or drugs, this review also highlights the natural products and their active ingredients that have been reported in recent years to affect thermogenesis and thus contribute to weight loss via the above signalling pathways.
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Affiliation(s)
- Zhengyan Zhang
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou 510006, China.,Guangdong Metabolic Diseases Research Centre of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Di Yang
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou 510006, China.,Guangdong Metabolic Diseases Research Centre of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Junwei Xiang
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou 510006, China.,Guangdong Metabolic Diseases Research Centre of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Jingwen Zhou
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou 510006, China.,Guangdong Metabolic Diseases Research Centre of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Hua Cao
- Guangdong Cosmetics Engineering & Technology Research Center, School of Chemistry and Chemical Engneering, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Qishi Che
- Guangzhou Rainhome Pharm & Tech Co., Ltd., Guangzhou 510663, China
| | - Yan Bai
- School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510310, China
| | - Jiao Guo
- Guangdong Metabolic Diseases Research Centre of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Zhengquan Su
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou 510006, China.,Guangdong Metabolic Diseases Research Centre of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
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12
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Mallela K, Kumar A. Role of TSC1 in physiology and diseases. Mol Cell Biochem 2021; 476:2269-2282. [PMID: 33575875 DOI: 10.1007/s11010-021-04088-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/27/2021] [Indexed: 12/15/2022]
Abstract
Since its initial discovery as the gene altered in Tuberous Sclerosis Complex (TSC), an autosomal dominant disorder, the interest in TSC1 (Tuberous Sclerosis Complex 1) has steadily risen. TSC1, an essential component of the pro-survival PI3K/AKT/MTOR signaling pathway, plays an important role in processes like development, cell growth and proliferation, survival, autophagy and cilia development by co-operating with a variety of regulatory molecules. Recent studies have emphasized the tumor suppressive role of TSC1 in several human cancers including liver, lung, bladder, breast, ovarian, and pancreatic cancers. TSC1 perceives inputs from various signaling pathways, including TNF-α/IKK-β, TGF-β-Smad2/3, AKT/Foxo/Bim, Wnt/β-catenin/Notch, and MTOR/Mdm2/p53 axis, thereby regulating cancer cell proliferation, metabolism, migration, invasion, and immune regulation. This review provides a first comprehensive evaluation of TSC1 and illuminates its diverse functions apart from its involvement in TSC genetic disorder. Further, we have summarized the physiological functions of TSC1 in various cellular events and conditions whose dysregulation may lead to several pathological manifestations including cancer.
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Affiliation(s)
- Karthik Mallela
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India
| | - Arun Kumar
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India.
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13
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Pena-Leon V, Perez-Lois R, Seoane LM. mTOR Pathway is Involved in Energy Homeostasis Regulation as a Part of the Gut-Brain Axis. Int J Mol Sci 2020; 21:ijms21165715. [PMID: 32784967 PMCID: PMC7460813 DOI: 10.3390/ijms21165715] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian, or mechanic, target of rapamycin (mTOR) signaling is a crucial factor in the regulation of the energy balance that functions as an energy sensor in the body. The present review explores how the mTOR/S6k intracellular pathway is involved in modulating the production of different signals such as ghrelin and nesfatin-1 in the gastrointestinal tract to regulate food intake and body weight. The role of gastric mTOR signaling in different physiological processes was studied in depth through different genetic models that allow the modulation of mTOR signaling in the stomach and specifically in gastric X/A type cells. It has been described that mTOR signaling in X/A-like gastric cells has a relevant role in the regulation of glucose and lipid homeostasis due to its interaction with different organs such as liver and adipose tissue. These findings highlight possible therapeutic strategies, with the gut–brain axis being one of the most promising targets in the treatment of obesity.
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Affiliation(s)
- Veronica Pena-Leon
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Raquel Perez-Lois
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Luisa Maria Seoane
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence:
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14
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Iwata W, Unoki-Kubota H, Kato H, Shimizu A, Matsumoto M, Imasawa T, Igarashi A, Matsumoto K, Noda T, Terauchi Y, Nangaku M, Kasuga M, Kaburagi Y. Podocyte-specific deletion of tubular sclerosis complex 2 promotes focal segmental glomerulosclerosis and progressive renal failure. PLoS One 2020; 15:e0229397. [PMID: 32191726 PMCID: PMC7082048 DOI: 10.1371/journal.pone.0229397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 02/05/2020] [Indexed: 02/06/2023] Open
Abstract
Obesity can initiate and accelerate the progression of kidney diseases. However, it remains unclear how obesity affects renal dysfunction. Here, we show that a newly generated podocyte-specific tubular sclerosis complex 2 (Tsc2) knockout mouse model (Tsc2Δpodocyte) develops proteinuria and dies due to end-stage renal dysfunction by 10 weeks of age. Tsc2Δpodocyte mice exhibit an increased glomerular size and focal segmental glomerulosclerosis, including podocyte foot process effacement, mesangial sclerosis and proteinaceous casts. Podocytes isolated from Tsc2Δpodocyte mice show nuclear factor, erythroid derived 2, like 2-mediated increased oxidative stress response on microarray analysis and their autophagic activity is lowered through the mammalian target of rapamycin (mTOR)-unc-51-like kinase 1 pathway. Rapamycin attenuated podocyte dysfunction and extends survival in Tsc2Δpodocyte mice. Additionally, mTOR complex 1 (mTORC1) activity is increased in podocytes of renal biopsy specimens obtained from obese patients with chronic kidney disease. Our work shows that mTORC1 hyperactivation in podocytes leads to severe renal dysfunction and that inhibition of mTORC1 activity in podocytes could be a key therapeutic target for obesity-related kidney diseases.
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Affiliation(s)
- Wakiko Iwata
- Department of Diabetic Complications, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
- Department of Endocrinology and Metabolism, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan
| | - Hiroyuki Unoki-Kubota
- Department of Diabetic Complications, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Hideki Kato
- Division of Nephrology and Endocrinology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan
| | - Michihiro Matsumoto
- Department of Molecular Metabolic Regulation, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Toshiyuki Imasawa
- Kidney Center, National Hospital Organization Chiba-Higashi National Hospital, Chiba, Japan
| | - Arisa Igarashi
- Department of Allergy and Clinical Immunology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Kenji Matsumoto
- Department of Allergy and Clinical Immunology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Tetsuo Noda
- Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Yasuo Terauchi
- Department of Endocrinology and Metabolism, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masato Kasuga
- National Center for Global Health and Medicine, Tokyo, Japan
| | - Yasushi Kaburagi
- Department of Diabetic Complications, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
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15
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Cairó M, Villarroya J. The role of autophagy in brown and beige adipose tissue plasticity. J Physiol Biochem 2019; 76:213-226. [PMID: 31811543 DOI: 10.1007/s13105-019-00708-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/10/2019] [Indexed: 01/04/2023]
Abstract
Since the rediscovery of active brown and beige adipose tissues in humans a decade ago, great efforts have been made to identify the mechanisms underlying the activation and inactivation of these tissues, with the hope of designing potential strategies to fight against obesity and associated metabolic disorders such as type 2 diabetes. Active brown/beige fat increases the energy expenditure and is associated with reduced hyperglycemia and hyperlipidemia, whereas its atrophy and inactivation have been associated with obesity and aging. Autophagy, which is the process by which intracellular components are degraded within the lysosomes, has recently emerged as an important regulatory mechanism of brown/beige fat plasticity. Studies have shown that autophagy participates in the intracellular remodeling events that occur during brown/beige adipogenesis, thermogenic activation, and inactivation. The autophagic degradation of mitochondria appears to be important for the inactivation of brown fat and the transition from beige-to-white adipose tissue. Moreover, autophagic dysregulation in adipose tissues has been associated with obesity. Thus, understanding the regulatory mechanisms that control autophagy in the physiology and pathophysiology of adipose tissues might suggest novel treatments against obesity and its associated metabolic diseases.
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Affiliation(s)
- Montserrat Cairó
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Avda Diagonal 643, 08028, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBER) Fisiopatologia de la Obesidad y Nutrición, 28029, Madrid, Spain
| | - Joan Villarroya
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Avda Diagonal 643, 08028, Barcelona, Spain.
- Infectious Diseases Unit, Hospital de la Santa Creu i Sant Pau, 08041, Barcelona, Spain.
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16
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mTOR signaling in Brown and Beige adipocytes: implications for thermogenesis and obesity. Nutr Metab (Lond) 2019; 16:74. [PMID: 31708995 PMCID: PMC6836431 DOI: 10.1186/s12986-019-0404-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 10/22/2019] [Indexed: 12/18/2022] Open
Abstract
Brown and beige adipocytes are mainly responsible for nonshivering thermogenesis or heat production, despite the fact that they have distinguished features in distribution, developmental origin, and functional activation. As a nutrient sensor and critical regulator of energy metabolism, mechanistic target of rapamycin (mTOR) also plays an important role in the development and functional maintenance of adipocytes. While the recent studies support the notion that mTOR (mTORC1 and mTORC2) related signaling pathways are of great significance for thermogenesis and the development of brown and beige adipocytes, the exact roles of mTOR in heat production are controversial. The similarities and disparities in terms of thermogenesis might be ascribed to the use of different animal models and experimental systems, distinct features of brown and beige adipocytes, and the complexity of regulatory networks of mTORC1 and mTORC2 in energy metabolism.
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17
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Papadopoli D, Boulay K, Kazak L, Pollak M, Mallette FA, Topisirovic I, Hulea L. mTOR as a central regulator of lifespan and aging. F1000Res 2019; 8:F1000 Faculty Rev-998. [PMID: 31316753 PMCID: PMC6611156 DOI: 10.12688/f1000research.17196.1] [Citation(s) in RCA: 200] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/20/2019] [Indexed: 12/17/2022] Open
Abstract
The mammalian/mechanistic target of rapamycin (mTOR) is a key component of cellular metabolism that integrates nutrient sensing with cellular processes that fuel cell growth and proliferation. Although the involvement of the mTOR pathway in regulating life span and aging has been studied extensively in the last decade, the underpinning mechanisms remain elusive. In this review, we highlight the emerging insights that link mTOR to various processes related to aging, such as nutrient sensing, maintenance of proteostasis, autophagy, mitochondrial dysfunction, cellular senescence, and decline in stem cell function.
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Affiliation(s)
- David Papadopoli
- Gerald Bronfman Department of Oncology, McGill University, 5100 de Maisonneuve Blvd. West, Suite 720, Montréal, QC, H4A 3T2, Canada
- Lady Davis Institute, SMBD JGH, 3755 Chemin de la Côte-Sainte-Catherine, Montréal, QC, H3T 1E2, Canada
| | - Karine Boulay
- Lady Davis Institute, SMBD JGH, 3755 Chemin de la Côte-Sainte-Catherine, Montréal, QC, H3T 1E2, Canada
- Maisonneuve-Rosemont Hospital Research Centre, 5415 Assumption Blvd, Montréal, QC, H1T 2M4, Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, QC, H3C 3J7, Canada
| | - Lawrence Kazak
- Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montréal, QC, H3G 1Y6, Canada
- Goodman Cancer Research Centre, 1160 Pine Avenue West, Montréal, QC, H3A 1A3, Canada
| | - Michael Pollak
- Gerald Bronfman Department of Oncology, McGill University, 5100 de Maisonneuve Blvd. West, Suite 720, Montréal, QC, H4A 3T2, Canada
- Lady Davis Institute, SMBD JGH, 3755 Chemin de la Côte-Sainte-Catherine, Montréal, QC, H3T 1E2, Canada
- Goodman Cancer Research Centre, 1160 Pine Avenue West, Montréal, QC, H3A 1A3, Canada
- Department of Experimental Medicine, McGill University, 845 Sherbrooke Street West, Montréal, QC, H3A 0G4, Canada
| | - Frédérick A. Mallette
- Maisonneuve-Rosemont Hospital Research Centre, 5415 Assumption Blvd, Montréal, QC, H1T 2M4, Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, QC, H3C 3J7, Canada
- Département de Médecine, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, QC, H3C 3J7, Canada
| | - Ivan Topisirovic
- Gerald Bronfman Department of Oncology, McGill University, 5100 de Maisonneuve Blvd. West, Suite 720, Montréal, QC, H4A 3T2, Canada
- Lady Davis Institute, SMBD JGH, 3755 Chemin de la Côte-Sainte-Catherine, Montréal, QC, H3T 1E2, Canada
- Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montréal, QC, H3G 1Y6, Canada
- Department of Experimental Medicine, McGill University, 845 Sherbrooke Street West, Montréal, QC, H3A 0G4, Canada
| | - Laura Hulea
- Maisonneuve-Rosemont Hospital Research Centre, 5415 Assumption Blvd, Montréal, QC, H1T 2M4, Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, QC, H3C 3J7, Canada
- Département de Médecine, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, QC, H3C 3J7, Canada
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18
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Deng J, Guo Y, Yuan F, Chen S, Yin H, Jiang X, Jiao F, Wang F, Ji H, Hu G, Ying H, Chen Y, Zhai Q, Xiao F, Guo F. Autophagy inhibition prevents glucocorticoid-increased adiposity via suppressing BAT whitening. Autophagy 2019; 16:451-465. [PMID: 31184563 DOI: 10.1080/15548627.2019.1628537] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The mechanisms underlying glucocorticoid (GC)-increased adiposity are poorly understood. Brown adipose tissue (BAT) acquires white adipose tissue (WAT) cell features defined as BAT whitening under certain circumstances. The aim of our current study was to investigate the possibility and mechanisms of GC-induced BAT whitening. Here, we showed that one-week dexamethasone (Dex) treatment induced BAT whitening, characterized by lipid droplet accumulation, in vitro and in vivo. Furthermore, autophagy and ATG7 (autophagy related 7) expression was induced in BAT by Dex, and treatment with the autophagy inhibitor chloroquine or adenovirus-mediated ATG7 knockdown prevented Dex-induced BAT whitening and fat mass gain. Moreover, Dex-increased ATG7 expression and autophagy was mediated by enhanced expression of BTG1 (B cell translocation gene 1, anti-proliferative) that stimulated activity of CREB1 (cAMP response element binding protein 1). The importance of BTG1 in this regulation was further demonstrated by the observed BAT whitening in adipocyte-specific BTG1-overexpressing mice and the attenuated Dex-induced BAT whitening and fat mass gain in mice with BTG1 knockdown in BAT. Taken together, we showed that Dex induces a significant whitening of BAT via BTG1- and ATG7-dependent autophagy, which might contribute to Dex-increased adiposity. These results provide new insights into the mechanisms underlying GC-increased adiposity and possible strategy for preventing GC-induced side effects via the combined use of an autophagy inhibitor.Abbreviations: ACADL: acyl-Coenzyme A dehydrogenase, long-chain; ACADM: acyl-Coenzyme A dehydrogenase, medium-chain; ACADS: acyl-Coenzyme A dehydrogenase, short-chain; ADIPOQ: adiponectin; AGT: angiotensinogen; Atg: autophagy-related; BAT: brown adipose tissue; BTG1: B cell translocation gene 1, anti-proliferative; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CIDEA: cell death-inducing DNA fragmentation factor, alpha subunit-like effector A; CPT1B: carnitine palmitoyltransferase 1b, muscle; CPT2: carnitine palmitoyltransferase 2; CQ: chloroquine; Dex: dexamethasone; eWAT: epididymal white adipose tissue; FABP4: fatty acid binding protein 4, adipocyte; FFAs: free fatty acids; GCs: glucocorticoids; NRIP1: nuclear receptor interacting protein 1; OCR: oxygen consumption rate; PBS: phosphate-buffered saline; PPARA: peroxisome proliferator activated receptor alpha; PPARG: peroxisome proliferator activated receptor gamma; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; PRDM16: PR domain containing 16; PSAT1: phosphoserine aminotransferase 1; RB1: RB transcriptional corepressor 1; RBL1/p107: RB transcriptional corepressor like 1; SQSTM1: sequestosome 1; sWAT: subcutaneous white adipose tissue; TG: triglycerides; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); WT: wild-type.
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Affiliation(s)
- Jiali Deng
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yajie Guo
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Feixiang Yuan
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shanghai Chen
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hanrui Yin
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xiaoxue Jiang
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fuxin Jiao
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fenfen Wang
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hongbin Ji
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guohong Hu
- The Key Laboratory of Stem Cell Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences & Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hao Ying
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yan Chen
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qiwei Zhai
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fei Xiao
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Feifan Guo
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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19
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Liang H, Nie J, Van Skike CE, Valentine JM, Orr ME. Mammalian Target of Rapamycin at the Crossroad Between Alzheimer's Disease and Diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1128:185-225. [PMID: 31062331 DOI: 10.1007/978-981-13-3540-2_10] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Accumulating evidence suggests that Alzheimer's disease may manifest as a metabolic disorder with pathology and/or dysfunction in numerous tissues. Adults with Alzheimer's disease suffer with significantly more comorbidities than demographically matched Medicare beneficiaries (Zhao et al, BMC Health Serv Res 8:108, 2008b). Reciprocally, comorbid health conditions increase the risk of developing Alzheimer's disease (Haaksma et al, PLoS One 12(5):e0177044, 2017). Type 2 diabetes mellitus is especially notable as the disease shares many overlapping pathologies observed in patients with Alzheimer's disease, including hyperglycemia, hyperinsulinemia, insulin resistance, glucose intolerance, dyslipidemia, inflammation, and cognitive dysfunction, as described in Chap. 8 of this book (Yoshitake et al, Neurology 45(6):1161-1168, 1995; Leibson et al, Am J Epidemiol 145(4):301-308, 1997; Ott et al, Neurology 53(9):1937-1942, 1999; Voisin et al, Rev Med Interne 24(Suppl 3):288s-291s, 2003; Janson et al. Diabetes 53(2):474-481, 2004; Ristow M, J Mol Med (Berl) 82(8):510-529, 2004; Whitmer et al, BMJ 330(7504):1360, 2005, Curr Alzheimer Res 4(2):103-109, 2007; Ohara et al, Neurology 77(12):1126-1134, 2011). Although nondiabetic older adults also experience age-related cognitive decline, diabetes is uniquely associated with a twofold increased risk of Alzheimer's disease, as described in Chap. 2 of this book (Yoshitake et al, Neurology 45(6):1161-1168, 1995; Leibson et al, Am J Epidemiol 145(4):301-308, 1997; Ott et al. Neurology 53(9):1937-1942, 1999; Ohara et al, Neurology 77(12):1126-1134, 2011). Good glycemic control has been shown to improve cognitive status (Cukierman-et al, Diabetes Care 32(2):221-226, 2009), and the use of insulin sensitizers is correlated with a lower rate of cognitive decline in older adults (Morris JK, Burns JM, Curr Neurol Neurosci Rep 12(5):520-527, 2012). At the molecular level, the mechanistic/mammalian target of rapamycin (mTOR) plays a key role in maintaining energy homeostasis. Nutrient availability and cellular stress information, both extracellular and intracellular, are integrated and transduced through mTOR signaling pathways. Aberrant regulation of mTOR occurs in the brains of patients with Alzheimer's disease and in numerous tissues of individuals with type 2 diabetes (Mannaa et al, J Mol Med (Berl) 91(10):1167-1175, 2013). Moreover, modulating mTOR activity with a pharmacological inhibitor, rapamycin, provides wide-ranging health benefits, including healthy life span extension in numerous model organisms (Vellai et al, Nature 426(6967):620, 2003; Jia et al, Development 131(16):3897-3906, 2004; Kapahi et al, Curr Biol 14(10):885-890, 2004; Kaeberlein et al, Science 310(5751):1193-1196, 2005; Powers et al, Genes Dev 20(2):174-184, 2006; Harrison et al, Nature 460(7253):392-395, 2009; Selman et al, Science 326(5949):140-144, 2009; Sharp ZD, Strong R, J Gerontol A Biol Sci Med Sci 65(6):580-589, 2010), which underscores its importance to overall organismal health and longevity. In this chapter, we discuss the physiological role of mTOR signaling and the consequences of mTOR dysregulation in the brain and peripheral tissues, with emphasis on its relevance to the development of Alzheimer's disease and link to type 2 diabetes.
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Affiliation(s)
- Hanyu Liang
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Jia Nie
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Candice E Van Skike
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Joseph M Valentine
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Miranda E Orr
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- San Antonio Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA.
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, San Antonio, TX, USA.
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20
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Role of mTOR in Glucose and Lipid Metabolism. Int J Mol Sci 2018; 19:ijms19072043. [PMID: 30011848 PMCID: PMC6073766 DOI: 10.3390/ijms19072043] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 02/06/2023] Open
Abstract
The mammalian target of rapamycin, mTOR is the master regulator of a cell’s growth and metabolic state in response to nutrients, growth factors and many extracellular cues. Its dysregulation leads to a number of metabolic pathological conditions, including obesity and type 2 diabetes. Here, we review recent findings on the role of mTOR in major metabolic organs, such as adipose tissues, liver, muscle, pancreas and brain. And their potentials as the mTOR related pharmacological targets will be also discussed.
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21
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ZHANG J, WU H, MA S, JING F, YU C, GAO L, ZHAO J. Transcription Regulators and Hormones Involved in the Development of Brown Fat and White Fat Browning: Transcriptional and Hormonal Control of Brown/Beige Fat Development. Physiol Res 2018. [DOI: 10.33549/physiolres.933650] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The high prevalence of obesity and related metabolic complications has inspired research on adipose tissues. Three kinds of adipose tissues are identified in mammals: brown adipose tissue (BAT), beige or brite adipose tissue and white adipose tissue (WAT). Beige adipocytes share some characteristics with brown adipocytes such as the expression of UCP1. Beige adipocytes can be activated by environmental stimuli or pharmacological treatment, and this change is accompanied by an increase in energy consumption. This process is called white browning, and it facilitates the maintenance of a lean and healthy phenotype. Thus, promoting beige adipocyte development in WAT shows promise as a new strategy in treating obesity and related metabolic consequences. In this review, we summarized the current understanding of the regulators and hormones that participate in the development of brown fat and white fat browning.
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Affiliation(s)
| | | | | | | | | | | | - J. ZHAO
- Department of Endocrinology, Shandong Provincial Hospital affiliated with Shandong University, Jinan, Shandong, China
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22
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Wang Y, He Z, Li X. Chronic Rapamycin Treatment Improved Metabolic Phenotype but Inhibited Adipose Tissue Browning in High-Fat Diet-Fed C57BL/6J Mice. Biol Pharm Bull 2018; 40:1352-1360. [PMID: 28867720 DOI: 10.1248/bpb.b16-00946] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rapamycin (Rap) has been demonstrated to affect lipid metabolism through stimulating lipolysis, inhibiting de novo lipogenesis and reducing adiposity. In the present study, we investigated rapamycin exposure's influence on adipose tissue browning in high-fat diet-induced fatty mice. Four-week old C57BL/6J mice were fed normal chow or high-fat diet for a period of 6 weeks and then divided into three groups: (1) Nor group: mice fed with normal chow; (2) high fat diet (HFD) group: fatty mice fed with high-fat diet; (3) Rap group: high-fat diet-fed fatty mice treated intragastrically with rapamycin at a dose of 2.5 mg/kg per day for 5 weeks. Body weights and food intakes of the mice were recorded weekly. At the end of the study, blood samples were collected for glucose, lipid and insulin evaluations. Adipose tissues were weighed and lipid contents were monitored. Moreover, real-time PCR and Western blotting were applied to detect the expression levels of beige and brown fat marker genes in white adipose tissue (WAT) and brown adipose tissue (BAT). Our data demonstrated that Rap exposure significantly ameliorated metabolic defects including hyperglycaemia, dyslipidaemia and insulin resistance in the fatty mice. Furthermore, Rap treatment led to decreased tissue weights and lipid contents both in WAT and BAT. Remarkably, expression levels of BAT marker genes including uncoupling protein-1 (UCP-1), cell death-inducing DNA fragmentation factor-alpha-like effector A (CIDEA), PR-domain containing protein-16 (PRDM16) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) were significantly down-regulated in Rap-treated fatty mice. This report demonstrates Rap exposure is capable of inhibiting adipose tissue browning in high-fat diet-induced fatty mice, and provides evidence for deeper understanding of Rap's influence on lipid homeostasis.
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Affiliation(s)
- Yan Wang
- Pharmacy Department, The First People's Hospital of Foshan
| | - Zhi He
- Medical School of China Three Gorges University
| | - Xianhui Li
- Institute of Medicine, College of Medicine, Jishou University
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23
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Xiong Y, Xu Z, Wang Y, Kuang S, Shan T. Adipocyte-specific DKO of Lkb1 and mTOR protects mice against HFD-induced obesity, but results in insulin resistance. J Lipid Res 2018; 59:974-981. [PMID: 29636366 DOI: 10.1194/jlr.m081463] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 04/01/2018] [Indexed: 12/14/2022] Open
Abstract
Liver kinase B1 (Lkb1) and mammalian target of rapamycin (mTOR) are key regulators of energy metabolism and cell growth. We have previously reported that adipocyte-specific KO of Lkb1 or mTOR in mice results in distinct developmental and metabolic phenotypes. Here, we aimed to assess how genetic KO of both Lkb1 and mTOR affects adipose tissue development and function in energy homeostasis. We used Adiponectin-Cre to drive adipocyte-specific double KO (DKO) of Lkb1 and mTOR in mice. We performed indirect calorimetry, glucose and insulin tolerance tests, and gene expression assays on the DKO and WT mice. We found that DKO of Lkb1 and mTOR results in reductions of brown adipose tissue and inguinal white adipose tissue mass, but in increases of liver mass. Notably, the DKO mice developed fatty liver and insulin resistance, but displayed improved glucose tolerance after high-fat diet (HFD)-feeding. Interestingly, the DKO mice were protected from HFD-induced obesity due to their higher energy expenditure and lower expression levels of adipogenic genes (CCAAT/enhancer binding protein α and PPARγ) compared with WT mice. These results together indicate that, compared with Lkb1 or mTOR single KOs, Lkb1/mTOR DKO in adipocytes results in overlapping and distinct metabolic phenotypes, and mTOR KO largely overrides the effect of Lkb1 KO.
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Affiliation(s)
- Yan Xiong
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907; College of Life Science and Technology, Southwest Minzu University, Chengdu, Sichuan 610041, China; Joint Laboratory of Lipid Metabolism, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing 100193, China
| | - Ziye Xu
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yizhen Wang
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Shihuan Kuang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907; Joint Laboratory of Lipid Metabolism, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing 100193, China.
| | - Tizhong Shan
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; Department of Animal Sciences, Purdue University, West Lafayette, IN 47907.
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24
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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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25
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Abdullahi A, Jeschke MG. Taming the Flames: Targeting White Adipose Tissue Browning in Hypermetabolic Conditions. Endocr Rev 2017; 38:538-549. [PMID: 28938469 PMCID: PMC5716828 DOI: 10.1210/er.2017-00163] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/18/2017] [Indexed: 12/17/2022]
Abstract
In this era of increased obesity and diabetes prevalence, the browning of white adipose tissue (WAT) has emerged as a promising therapeutic target to induce weight loss and improve insulin sensitivity in this population. The browning process entails a shift in the WAT from primarily storing excess energy to the dissipation of energy as heat. However, this idealistic view of WAT browning being the savior of the metabolic syndrome has been criticized by studies in burn and cancer patients that have shown browning to be detrimental rather than beneficial. In fact, in the context of hypermetabolic states, the browning of WAT has presented with substantial clinical adverse outcomes related to cachexia, hepatic steatosis, and muscle catabolism. Therefore, the previous thought construct of understanding browning as an all-beneficial physiologic event has now been met with skepticism. In this review, we focus on current knowledge of browning of WAT and its adverse metabolic alterations during hypermetabolic states. We also discuss the regulators and signaling pathways involved in the browning process and their potential for being targeted by new or existing drugs to inhibit or alleviate browning, potentially leading to decreased hypermetabolism and improved clinical outcomes. Lastly, the imminent clinical applications of pharmacological agents are explored in the perspective of attenuating WAT browning and its associated adverse side effects reported in burn patients.
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Affiliation(s)
- Abdikarim Abdullahi
- Faculty of Medicine, University of Toronto, Canada.,Biological Sciences, Sunnybrook Research Institute, Canada.,Ross Tilley Burn Centre, Sunnybrook Hospital, Canada
| | - Marc G Jeschke
- Faculty of Medicine, University of Toronto, Canada.,Biological Sciences, Sunnybrook Research Institute, Canada.,Ross Tilley Burn Centre, Sunnybrook Hospital, Canada.,Department of Surgery, Division of Plastic Surgery and Department of Immunology, University of Toronto, Canada
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26
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Liu Y, Duan L, Tian J, Song D, Zhang M, Zhao S, Yin Z, Xiang X, Li X. Role of the Akt/mTOR signaling pathway in human papillomavirus-associated nasal and sinonasal inverted papilloma. Acta Biochim Biophys Sin (Shanghai) 2017; 49:1067-1074. [PMID: 29040365 DOI: 10.1093/abbs/gmx108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Indexed: 11/12/2022] Open
Abstract
Nasal and sinonasal inverted papilloma (NSIP) is a benign tumor in which surface epithelial cells grow downward into the underlying supportive tissue with varying degrees of metaplasia. Human papillomavirus (HPV) has been proposed as the causal agent in the pathogenesis of this disease. Many studies have shown that HPV can activate the Akt/mechanistic target of rapamycin (mTOR) signaling pathway, but the role of this pathway in HPV-associated NSIP is largely unknown. In this study, we enrolled 40 control tissue samples and 80 NSIP tissue samples. HPV genotyping showed that 47 of the 80 examined cases of NSIP were HPV-positive (58.8%), and the most common subtype was HPV11 (20/53, 37.7%). The immunohistochemistry showed statistically significant differences in phosphorylated Akt and phosphorylated S6 ribosomal protein staining among control samples, HPV-positive NSIP and HPV-negative NSIP. The HPV11 L1-L2 plasmid increased the proliferation of normal human nasopharyngeal epithelial NP69-SV40T cells and human nasopharyngeal cancer CNE1 cells. Meanwhile, rapamycin, an mTOR inhibitor, reversed the increased cell proliferation induced by the HPV11 L1-L2 plasmid. Western blot analysis showed that Akt/mTOR/S6 were overexpressed in NP69-SV40T cells and CNE1 cells infected with the HPV11 L1-L2 plasmid. These data demonstrate that HPV promotes cell proliferation through the Akt/mTOR signaling pathway in NSIP.
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Affiliation(s)
- Yongliang Liu
- Department of Otolaryngolgogy, Qilu Hospital of Shandong University, Jinan, China
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Lihua Duan
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Jie Tian
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Daoliang Song
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Min Zhang
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Shenlin Zhao
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Zhaofu Yin
- Department of Otolaryngolgogy, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Xinxin Xiang
- Central of Translation Medicine, Zibo Central Hospital affiliated to Shandong University, Zibo, China
| | - Xuezhong Li
- Department of Otolaryngolgogy, Qilu Hospital of Shandong University, Jinan, China
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27
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Liao CY, Anderson SS, Chicoine NH, Mayfield JR, Academia EC, Wilson JA, Pongkietisak C, Thompson MA, Lagmay EP, Miller DM, Hsu YM, McCormick MA, O'Leary MN, Kennedy BK. Rapamycin Reverses Metabolic Deficits in Lamin A/C-Deficient Mice. Cell Rep 2017; 17:2542-2552. [PMID: 27926859 DOI: 10.1016/j.celrep.2016.10.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 07/27/2016] [Accepted: 10/13/2016] [Indexed: 01/26/2023] Open
Abstract
The role of the mTOR inhibitor, rapamycin, in regulation of adiposity remains controversial. Here, we evaluate mTOR signaling in lipid metabolism in adipose tissues of Lmna-/- mice, a mouse model for dilated cardiomyopathy and muscular dystrophy. Lifespan extension by rapamycin is associated with increased body weight and fat content, two phenotypes we link to suppression of elevated energy expenditure. In both white and brown adipose tissue of Lmna-/- mice, we find that rapamycin inhibits mTORC1 but not mTORC2, leading to suppression of elevated lipolysis and restoration of thermogenic protein UCP1 levels, respectively. The short lifespan and metabolic phenotypes of Lmna-/- mice can be partially rescued by maintaining mice at thermoneutrality. Together, our findings indicate that altered mTOR signaling in Lmna-/- mice leads to a lipodystrophic phenotype that can be rescued with rapamycin, highlighting the effect of loss of adipose tissue in Lmna-/- mice and the consequences of altered mTOR signaling.
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Affiliation(s)
- Chen-Yu Liao
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Sydney S Anderson
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Nicole H Chicoine
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Jarrott R Mayfield
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Emmeline C Academia
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Joy A Wilson
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | | | - Morgan A Thompson
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Earl P Lagmay
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Delana M Miller
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Yueh-Mei Hsu
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Mark A McCormick
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Monique N O'Leary
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Brian K Kennedy
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA.
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28
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Liu J, Xu Z, Wu W, Wang Y, Shan T. CreRecombinase Strains Used for the Study of Adipose Tissues and Adipocyte Progenitors. J Cell Physiol 2017; 232:2698-2703. [DOI: 10.1002/jcp.25675] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/01/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Jiaqi Liu
- College of Animal Sciences; Zhejiang University; The Key Laboratory of Molecular Animal Nutrition, Ministry of Education; Zhejiang Provincial Laboratory of Feed and Animal Nutrition; Hangzhou Zhejiang China
| | - Ziye Xu
- College of Animal Sciences; Zhejiang University; The Key Laboratory of Molecular Animal Nutrition, Ministry of Education; Zhejiang Provincial Laboratory of Feed and Animal Nutrition; Hangzhou Zhejiang China
| | - Weiche Wu
- College of Animal Sciences; Zhejiang University; The Key Laboratory of Molecular Animal Nutrition, Ministry of Education; Zhejiang Provincial Laboratory of Feed and Animal Nutrition; Hangzhou Zhejiang China
| | - Yizhen Wang
- College of Animal Sciences; Zhejiang University; The Key Laboratory of Molecular Animal Nutrition, Ministry of Education; Zhejiang Provincial Laboratory of Feed and Animal Nutrition; Hangzhou Zhejiang China
| | - Tizhong Shan
- College of Animal Sciences; Zhejiang University; The Key Laboratory of Molecular Animal Nutrition, Ministry of Education; Zhejiang Provincial Laboratory of Feed and Animal Nutrition; Hangzhou Zhejiang China
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29
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Liu Y, Wang X, Zhao Y, Zhao P, Wang L, Zhai Q, Zhang X, Tian W, Xiang X, Li T. Upregulation of Tumor Necrosis Factor- α-Induced Protein 8-Like 2 mRNA Is Negatively Correlated with Serum Concentrations of Tumor Necrosis Factor- α and Interleukin 6 in Type 2 Diabetes Mellitus. J Diabetes Res 2017; 2017:4802319. [PMID: 28626770 PMCID: PMC5463106 DOI: 10.1155/2017/4802319] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a negative regulator of natural and adaptive immunity. The role of TIPE2 in type 2 diabetes mellitus (T2DM) remains unknown, although TIPE2 plays key roles in preserving inflammatory homeostasis. METHODS TIPE2 expression was measured by Western blotting and real-time polymerase chain reaction (RT-PCR) in peripheral blood mononuclear cells (PBMCs) isolated from T2DM patients and healthy controls, and tumor necrosis factor-α (TNF-α), high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), and other related biometabolic parameters were detected using a nephelometer or by ELISA. Differentiated THP-1 cells were exposed to siTIPE2 and TIPE2 adenovirus. RESULTS TIPE2 was significantly increased in PBMCs from T2DM patients compared with those from healthy controls and was negatively correlated with serum TNF-α, IL-6, and hsCRP concentrations but positively correlated with HbA1c and LDL-C in T2DM patients. High glucose treatment (50 mmol/L) can upregulate the expression of TIPE2 and cytokine secretion in differentiated THP-1 cells. siTIPE2 infection exacerbated the increased TNF-α and IL-6 concentrations in differentiated THP-1 cells under high glucose conditions (50 mmol/L), while infection with TIPE2 adenovirus reversed the increased TNF-α concentration. CONCLUSIONS The present study indicates that TIPE2 may participate in T2DM by regulating TNF-α production.
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Affiliation(s)
- Yongliang Liu
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Xinmei Wang
- Department of Pathology, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Yan Zhao
- Department of Central Laboratory, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Peiqing Zhao
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Lianqing Wang
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Qiaoli Zhai
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Xiaowei Zhang
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Wenxiu Tian
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
| | - Xinxin Xiang
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
- *Xinxin Xiang: and
| | - Tao Li
- Central of Translation Medicine, Zibo Central Hospital Affiliated to Shandong University, Zibo 255036, China
- *Tao Li:
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30
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Labbé SM, Mouchiroud M, Caron A, Secco B, Freinkman E, Lamoureux G, Gélinas Y, Lecomte R, Bossé Y, Chimin P, Festuccia WT, Richard D, Laplante M. mTORC1 is Required for Brown Adipose Tissue Recruitment and Metabolic Adaptation to Cold. Sci Rep 2016; 6:37223. [PMID: 27876792 PMCID: PMC5120333 DOI: 10.1038/srep37223] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/26/2016] [Indexed: 12/21/2022] Open
Abstract
In response to cold, brown adipose tissue (BAT) increases its metabolic rate and expands its mass to produce heat required for survival, a process known as BAT recruitment. The mechanistic target of rapamycin complex 1 (mTORC1) controls metabolism, cell growth and proliferation, but its role in regulating BAT recruitment in response to chronic cold stimulation is unknown. Here, we show that cold activates mTORC1 in BAT, an effect that depends on the sympathetic nervous system. Adipocyte-specific mTORC1 loss in mice completely blocks cold-induced BAT expansion and severely impairs mitochondrial biogenesis. Accordingly, mTORC1 loss reduces oxygen consumption and causes a severe defect in BAT oxidative metabolism upon cold exposure. Using in vivo metabolic imaging, metabolomics and transcriptomics, we show that mTORC1 deletion impairs glucose and lipid oxidation, an effect linked to a defect in tricarboxylic acid (TCA) cycle activity. These analyses also reveal a severe defect in nucleotide synthesis in the absence of mTORC1. Overall, these findings demonstrate an essential role for mTORC1 in the regulation of BAT recruitment and metabolism in response to cold.
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Affiliation(s)
- Sébastien M Labbé
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Mathilde Mouchiroud
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Alexandre Caron
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Blandine Secco
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Elizaveta Freinkman
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Guillaume Lamoureux
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Yves Gélinas
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Roger Lecomte
- Centre d'imagerie moléculaire de Sherbrooke (CIMS), Département de Médecine nucléaire et radiobiologie, Université de Sherbrooke, Sherbrooke, J1H 5N4, Canada
| | - Yohan Bossé
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada
| | - Patricia Chimin
- Department of Physiology &Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, 05508-000, Brazil
| | - William T Festuccia
- Department of Physiology &Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, 05508-000, Brazil
| | - Denis Richard
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Mathieu Laplante
- Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval, 2725 chemin Sainte-Foy, Québec, QC, G1V 4G5, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, QC, Canada
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31
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Wada S, Neinast M, Jang C, Ibrahim YH, Lee G, Babu A, Li J, Hoshino A, Rowe GC, Rhee J, Martina JA, Puertollano R, Blenis J, Morley M, Baur JA, Seale P, Arany Z. The tumor suppressor FLCN mediates an alternate mTOR pathway to regulate browning of adipose tissue. Genes Dev 2016; 30:2551-2564. [PMID: 27913603 PMCID: PMC5159669 DOI: 10.1101/gad.287953.116] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/07/2016] [Indexed: 12/20/2022]
Abstract
Noncanonical mechanistic target of rapamycin (mTOR) pathways remain poorly understood. Mutations in the tumor suppressor folliculin (FLCN) cause Birt-Hogg-Dubé syndrome, a hamartomatous disease marked by mitochondria-rich kidney tumors. FLCN functionally interacts with mTOR and is expressed in most tissues, but its role in fat has not been explored. We show here that FLCN regulates adipose tissue browning via mTOR and the transcription factor TFE3. Adipose-specific deletion of FLCN relieves mTOR-dependent cytoplasmic retention of TFE3, leading to direct induction of the PGC-1 transcriptional coactivators, drivers of mitochondrial biogenesis and the browning program. Cytoplasmic retention of TFE3 by mTOR is sensitive to ambient amino acids, is independent of growth factor and tuberous sclerosis complex (TSC) signaling, is driven by RagC/D, and is separable from canonical mTOR signaling to S6K. Codeletion of TFE3 in adipose-specific FLCN knockout animals rescues adipose tissue browning, as does codeletion of PGC-1β. Conversely, inducible expression of PGC-1β in white adipose tissue is sufficient to induce beige fat gene expression in vivo. These data thus unveil a novel FLCN-mTOR-TFE3-PGC-1β pathway-separate from the canonical TSC-mTOR-S6K pathway-that regulates browning of adipose tissue.
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Affiliation(s)
- Shogo Wada
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Michael Neinast
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Cholsoon Jang
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Chemistry and Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yasir H Ibrahim
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medicine, New York, New York, 10021, USA
| | - Gina Lee
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medicine, New York, New York, 10021, USA
| | - Apoorva Babu
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jian Li
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Atsushi Hoshino
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Glenn C Rowe
- Division of Cardiovascular Disease, University of Alabama, Birmingham, Alabama 35294, USA
| | - James Rhee
- Department of Anesthesia and Critical Care, Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - José A Martina
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20814, USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20814, USA
| | - John Blenis
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medicine, New York, New York, 10021, USA
| | - Michael Morley
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Joseph A Baur
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Patrick Seale
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Zoltan Arany
- Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Abstract
Nesfatin-1, an 82 amino acid gastric peptide, is involved in regulation of food uptake and in multiple metabolic activities. Whether nesfatin-1 modulates the differentiation and lipid metabolism of brown adipocytes remains unknown. In the present study, we found that nesfatin-1 mRNA and protein were detectable in isolated brown adipocytes and gradually decreased during differentiation (95% CI 0.6057 to 1.034, p = 0.0001). The decrease in nesfatin-1 was associated with a significant reduction in p-S6. Exposure to nesfatin-1 promoted differentiation of brown adipocytes as revealed by a significant increase in UCP1 mRNA (p = 0.03) and lipolysis-related ATGL mRNA (p = 0.04). Nesfatin-1 attenuated phosphorylation of S6K and S6 during brown adipocyte differentiation. Activation of mTOR by leucine or deletion of TSC1 decreased expression of brown adipocyte-related genes UCP1, UCP3, PGC1α and PRDM16, as well as COX8B and ATP5B. Both leucine and TSC1 deletion blocked nesfatin-1-induced up-regulation of UCP1, PGC1α, COX8B and ATP5B in differentiated brown adipocytes. In conclusion, nesfatin-1 promotes the differentiation of brown adipocytes likely through the mTOR dependent mechanism.
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Lv Y, Zhang SY, Liang X, Zhang H, Xu Z, Liu B, Xu MJ, Jiang C, Shang J, Wang X. Adrenomedullin 2 Enhances Beiging in White Adipose Tissue Directly in an Adipocyte-autonomous Manner and Indirectly through Activation of M2 Macrophages. J Biol Chem 2016; 291:23390-23402. [PMID: 27621315 DOI: 10.1074/jbc.m116.735563] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Indexed: 12/15/2022] Open
Abstract
Adrenomedullin 2 (ADM2) is an endogenous bioactive peptide belonging to the calcitonin gene-related peptide family. Our previous studies showed that overexpression of ADM2 in mice reduced obesity and insulin resistance by increasing thermogenesis in brown adipose tissue. However, the effects of ADM2 in another type of thermogenic adipocyte, beige adipocytes, remain to be understood. The plasma ADM2 levels were inversely correlated with obesity in humans, and adipo-ADM2-transgenic (tg) mice displayed resistance to high-fat diet-induced obesity with increased energy expenditure. Beiging of subcutaneous white adipose tissues (WAT) was more noticeably induced in high-fat diet-fed transgenic mice with adipocyte-ADM2 overexpression (adipo-ADM2-tg mice) than in WT animals. ADM2 treatment in primary rat subcutaneous adipocytes induced beiging with up-regulation of UCP1 and beiging-related marker genes and increased mitochondrial uncoupling respiration, which was mainly mediated by activation of the calcitonin receptor-like receptor (CRLR)·receptor activity-modifying protein 1 (RAMP1) complex and PKA and p38 MAPK signaling pathways. Importantly, this adipocyte-autonomous beiging effect by ADM2 was translatable to human primary adipocytes. In addition, M2 macrophage activation also contributed to the beiging effects of ADM2 through catecholamine secretion. Therefore, our study reveals that ADM2 enhances subcutaneous WAT beiging via a direct effect by activating the CRLR·RAMP1-cAMP/PKA and p38 MAPK pathways in white adipocytes and via an indirect effect by stimulating alternative M2 polarization in macrophages. Through both mechanisms, beiging of WAT by ADM2 results in increased energy expenditure and reduced obesity, suggesting ADM2 as a novel anti-obesity target.
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Affiliation(s)
- Ying Lv
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
| | - Song-Yang Zhang
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
| | - Xianyi Liang
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
| | - Heng Zhang
- the Department of Endocrinology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Zhi Xu
- the Department of General Surgery, Peking University Third Hospital, Beijing 100191, China, and
| | - Bo Liu
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
| | - Ming-Jiang Xu
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
| | - Changtao Jiang
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China,
| | - Jin Shang
- the Department of Cardiometabolic Disease, Merck Research Laboratories, Merck & Co, Inc., Kenilworth, New Jersey 07033
| | - Xian Wang
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
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Shan T, Zhang P, Jiang Q, Xiong Y, Wang Y, Kuang S. Adipocyte-specific deletion of mTOR inhibits adipose tissue development and causes insulin resistance in mice. Diabetologia 2016; 59:1995-2004. [PMID: 27294611 PMCID: PMC5345851 DOI: 10.1007/s00125-016-4006-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/20/2016] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS The in vivo role of mechanistic target of rapamycin (mTOR) in the development and function of adipose tissue, especially brown adipose tissue (BAT), is not well understood. Here, we aimed to assess the effect of mTOR (also known as Mtor) knockout on adipose tissues and systemic energy metabolism. METHODS We generated adipocyte-specific mTOR-knockout mice (Adipoq-mTOR) by crossing adiponectin-Cre (Adipoq-Cre) mice with mTOR (flox/flox) mice. The mice were then subjected to morphological, physiological (indirect calorimetry, glucose and insulin tolerance tests) and gene expression analyses to determine the role of mTOR in adipose tissues. RESULTS We provide in vivo evidence that mTOR is essential for adipose tissue development and growth. Deletion of mTOR decreased the mass of both BAT and white adipose tissues (WAT) and induced browning of WAT. In addition, ablation of mTOR in adipose tissues caused insulin resistance and fatty liver in the Adipoq-mTOR mice. Furthermore, mTOR was required for adipocyte differentiation in vivo and activation of PPARγ ameliorated the differentiation deficiency of the mTOR-null adipocytes. CONCLUSIONS/INTERPRETATION Our findings demonstrate that mTOR is a critical regulator of adipogenesis and systemic energy metabolism. Our study provides key insights into the role of mTOR in adipose tissues; such knowledge may facilitate the development of novel strategies with which to treat obesity and related metabolic diseases.
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Affiliation(s)
- Tizhong Shan
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, People's Republic of China.
- Department of Animal Sciences, Purdue University, 901 West State Street, West Lafayette, IN, 47907, USA.
| | - Pengpeng Zhang
- Department of Animal Sciences, Purdue University, 901 West State Street, West Lafayette, IN, 47907, USA
- College of Life Sciences, Xinyang Normal University, Xinyang, People's Republic of China
| | - Qinyang Jiang
- Department of Animal Sciences, Purdue University, 901 West State Street, West Lafayette, IN, 47907, USA
- College of animal science and technology, Guangxi University, Nanning, People's Republic of China
| | - Yan Xiong
- Department of Animal Sciences, Purdue University, 901 West State Street, West Lafayette, IN, 47907, USA
| | - Yizhen Wang
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, People's Republic of China
| | - Shihuan Kuang
- Department of Animal Sciences, Purdue University, 901 West State Street, West Lafayette, IN, 47907, USA.
- Purdue University Center for Cancer Research, West Lafayette, IN 47907, USA.
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The Mechanistic Target of Rapamycin: The Grand ConducTOR of Metabolism and Aging. Cell Metab 2016; 23:990-1003. [PMID: 27304501 PMCID: PMC4910876 DOI: 10.1016/j.cmet.2016.05.009] [Citation(s) in RCA: 367] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/17/2016] [Accepted: 05/24/2016] [Indexed: 12/21/2022]
Abstract
Since the discovery that rapamycin, a small molecule inhibitor of the protein kinase mTOR (mechanistic target of rapamycin), can extend the lifespan of model organisms including mice, interest in understanding the physiological role and molecular targets of this pathway has surged. While mTOR was already well known as a regulator of growth and protein translation, it is now clear that mTOR functions as a central coordinator of organismal metabolism in response to both environmental and hormonal signals. This review discusses recent developments in our understanding of how mTOR signaling is regulated by nutrients and the role of the mTOR signaling pathway in key metabolic tissues. Finally, we discuss the molecular basis for the negative metabolic side effects associated with rapamycin treatment, which may serve as barriers to the adoption of rapamycin or similar compounds for the treatment of diseases of aging and metabolism.
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Hu F, Xu Y, Liu F. Hypothalamic roles of mTOR complex I: integration of nutrient and hormone signals to regulate energy homeostasis. Am J Physiol Endocrinol Metab 2016; 310:E994-E1002. [PMID: 27166282 PMCID: PMC4935144 DOI: 10.1152/ajpendo.00121.2016] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/06/2016] [Indexed: 12/31/2022]
Abstract
Mammalian or mechanistic target of rapamycin (mTOR) senses nutrient, energy, and hormone signals to regulate metabolism and energy homeostasis. mTOR activity in the hypothalamus, which is associated with changes in energy status, plays a critical role in the regulation of food intake and body weight. mTOR integrates signals from a variety of "energy balancing" hormones such as leptin, insulin, and ghrelin, although its action varies in response to these distinct hormonal stimuli as well as across different neuronal populations. In this review, we summarize and highlight recent findings regarding the functional roles of mTOR complex 1 (mTORC1) in the hypothalamus specifically in its regulation of body weight, energy expenditure, and glucose/lipid homeostasis. Understanding the role and underlying mechanisms behind mTOR-related signaling in the brain will undoubtedly pave new avenues for future therapeutics and interventions that can combat obesity, insulin resistance, and diabetes.
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Affiliation(s)
- Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China;
| | - Yong Xu
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas; and
| | - Feng Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China; Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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Raptor/mTORC1 loss in adipocytes causes progressive lipodystrophy and fatty liver disease. Mol Metab 2016; 5:422-432. [PMID: 27257602 PMCID: PMC4877665 DOI: 10.1016/j.molmet.2016.04.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 12/03/2022] Open
Abstract
Objective Normal adipose tissue growth and function is critical to maintaining metabolic homeostasis and its excess (e.g. obesity) or absence (e.g. lipodystrophy) is associated with severe metabolic disease. The goal of this study was to understand the mechanisms maintaining healthy adipose tissue growth and function. Methods Adipose tissue senses and responds to systemic changes in growth factor and nutrient availability; in cells mTORC1 regulates metabolism in response to growth factors and nutrients. Thus, mTORC1 is poised to be a critical intracellular regulator of adipocyte metabolism. Here, we investigate the role of mTORC1 in mature adipocytes by generating and characterizing mice in which the Adiponectin-Cre driver is used to delete floxed alleles of Raptor, which encodes an essential regulatory subunit of mTORC1. Results RaptorAdipoq-cre mice have normal white adipose tissue (WAT) mass for the first few weeks of life, but soon thereafter develop lipodystrophy associated with hepatomegaly, hepatic steatosis, and insulin intolerance. RaptorAdipoq-cre mice are also resistant to becoming obese when consuming a high fat diet (HFD). Resistance to obesity does not appear to be due to increased energy expenditure, but rather from failed adipose tissue expansion resulting in severe hepatomegaly associated with hyperphagia and defective dietary lipid absorption. Deleting Raptor in WAT also decreases C/EBPα expression and the expression of its downstream target adiponectin, providing one possible mechanism of mTORC1 function in WAT. Conclusions mTORC1 activity in mature adipocytes is essential for maintaining normal adipose tissue growth and its selective loss in mature adipocytes leads to a progressive lipodystrophy disorder and systemic metabolic disease that shares many of the hallmarks of human congenital generalized lipodystrophy. A new model of Raptor (mTORC1) loss in adipose tissue is described. Young fat Raptor KO mice have normal WAT mass. Fat Raptor KO mice progressively develop lipodystrophy and metabolic disease. Fat Raptor KO mice resist obesity but develop severe hepatomegaly.
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Tran CM, Mukherjee S, Ye L, Frederick DW, Kissig M, Davis JG, Lamming DW, Seale P, Baur JA. Rapamycin Blocks Induction of the Thermogenic Program in White Adipose Tissue. Diabetes 2016; 65:927-41. [PMID: 26858361 PMCID: PMC4806661 DOI: 10.2337/db15-0502] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 12/26/2015] [Indexed: 12/13/2022]
Abstract
Rapamycin extends life span in mice, yet paradoxically causes lipid dysregulation and glucose intolerance through mechanisms that remain incompletely understood. Whole-body energy balance can be influenced by beige/brite adipocytes, which are inducible by cold and other stimuli via β-adrenergic signaling in white adipose depots. Induction of beige adipocytes is considered a promising strategy to combat obesity because of their ability to metabolize glucose and lipids, dissipating the resulting energy as heat through uncoupling protein 1. Here, we report that rapamycin blocks the ability of β-adrenergic signaling to induce beige adipocytes and expression of thermogenic genes in white adipose depots. Rapamycin enhanced transcriptional negative feedback on the β3-adrenergic receptor. However, thermogenic gene expression remained impaired even when the receptor was bypassed with a cell-permeable cAMP analog, revealing the existence of a second inhibitory mechanism. Accordingly, rapamycin-treated mice are cold intolerant, failing to maintain body temperature and weight when shifted to 4°C. Adipocyte-specific deletion of the mTORC1 subunit Raptor recapitulated the block in β-adrenergic signaling. Our findings demonstrate a positive role for mTORC1 in the recruitment of beige adipocytes and suggest that inhibition of β-adrenergic signaling by rapamycin may contribute to its physiological effects.
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Affiliation(s)
- Cassie M Tran
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Sarmistha Mukherjee
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Lan Ye
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - David W Frederick
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Megan Kissig
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - James G Davis
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Dudley W Lamming
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Patrick Seale
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Joseph A Baur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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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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Cai H, Dong LQ, Liu F. Recent Advances in Adipose mTOR Signaling and Function: Therapeutic Prospects. Trends Pharmacol Sci 2015; 37:303-317. [PMID: 26700098 DOI: 10.1016/j.tips.2015.11.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 11/19/2015] [Accepted: 11/20/2015] [Indexed: 12/11/2022]
Abstract
The increasing epidemic of obesity and its comorbidities has spurred research interest in adipose biology and its regulatory functions. Recent studies have revealed that the mechanistic target of rapamycin (mTOR) signaling pathway has a critical role in the regulation of adipose tissue function, including adipogenesis, lipid metabolism, thermogenesis, and adipokine synthesis and/or secretion. Given the importance of mTOR signaling in controlling energy homeostasis, it is not unexpected that deregulated mTOR signaling is associated with obesity and related metabolic disorders. In this review, we highlight current advances in understanding the roles of the mTOR signaling pathway in adipose tissue. We also provide a more nuanced view of how the mTOR signaling pathway regulates adipose tissue biology and function. Finally, we describe approaches to modulate the activity and tissue-specific function of mTOR that may pave the way towards counteracting obesity and related metabolic diseases.
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Affiliation(s)
- Huan Cai
- Institute of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China; Department of Pharmacology, UTHSCSA, San Antonio, TX, USA
| | - Lily Q Dong
- Departments of Cellular Structural Biology, UTHSCSA, San Antonio, TX, USA
| | - Feng Liu
- Institute of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China; Department of Pharmacology, UTHSCSA, San Antonio, TX, USA.
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