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Rawat P, Thakur S, Dogra S, Jaswal K, Dehury B, Mondal P. Diet-induced induction of hepatic Serine/Threonine Kinase STK38 triggers proinflammation and hepatic lipid accumulation. J Biol Chem 2023; 299:104678. [PMID: 37028764 DOI: 10.1016/j.jbc.2023.104678] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/24/2023] [Accepted: 03/26/2023] [Indexed: 04/07/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide. Although the involvement of chronic overnutrition, systemic inflammation, and insulin resistance in the development of NAFLD is well-established, however, the associations among these remain to be elucidated. Several studies have reported that chronic overnutrition, such as excessive consumption of fats (High Fat Diet, HFD) can cause insulin resistance and inflammation. However, the mechanisms by which HFD exerts inflammation and thereby promotes insulin resistance and intrahepatic fat accumulation remain poorly understood. Here, we show that HFD induces the expression of hepatic Serine/Threonine Kinase 38 (STK38), which further induces systemic inflammation leading to insulin resistance. Notably, Ectopic expression of STK38 in mouse liver leads to lean NAFLD phenotype with hepatic inflammation, insulin resistance, intrahepatic lipid accumulation, and hypertriglyceridemia in mice fed on a regular chow diet. Further, depletion of hepatic STK38 in HFD-fed mice remarkably reduces proinflammation, improves hepatic insulin sensitivity, and decreases hepatic fat accumulation. Mechanistically, two critical stimuli are elicited by STK38 action. For one stimulus, STK38 binds to Tank-Binding protein Kinase1 (TBK1) and induces TBK1 phosphorylation to promote NF-κβ nuclear translocation that mobilizes the release of pro-inflammatory cytokines and eventually leads to insulin resistance. The second, stimulus involves intrahepatic lipid accumulation by enhanced de novo lipogenesis via reducing the AMPK-ACC signaling axis. These findings identify STK38 as a novel nutrient-sensitive pro-inflammatory and lipogenic factor in maintaining hepatic energy homeostasis, and it provides a promising target for hepatic and immune health.
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2
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Surma M, Anbarasu K, Dutta S, Olivera Perez LJ, Huang KC, Meyer JS, Das A. Enhanced mitochondrial biogenesis promotes neuroprotection in human pluripotent stem cell derived retinal ganglion cells. Commun Biol 2023; 6:218. [PMID: 36828933 PMCID: PMC9957998 DOI: 10.1038/s42003-023-04576-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
Mitochondrial dysfunctions are widely afflicted in central nervous system (CNS) disorders with minimal understanding on how to improve mitochondrial homeostasis to promote neuroprotection. Here we have used human stem cell differentiated retinal ganglion cells (hRGCs) of the CNS, which are highly sensitive towards mitochondrial dysfunctions due to their unique structure and function, to identify mechanisms for improving mitochondrial quality control (MQC). We show that hRGCs are efficient in maintaining mitochondrial homeostasis through rapid degradation and biogenesis of mitochondria under acute damage. Using a glaucomatous Optineurin mutant (E50K) stem cell line, we show that at basal level mutant hRGCs possess less mitochondrial mass and suffer mitochondrial swelling due to excess ATP production load. Activation of mitochondrial biogenesis through pharmacological inhibition of the Tank binding kinase 1 (TBK1) restores energy homeostasis, mitigates mitochondrial swelling with neuroprotection against acute mitochondrial damage for glaucomatous E50K hRGCs, revealing a novel neuroprotection mechanism.
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Affiliation(s)
- Michelle Surma
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis, IN, 46202, USA
| | - Kavitha Anbarasu
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis, IN, 46202, USA
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, IN, 46202, USA
| | - Sayanta Dutta
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis, IN, 46202, USA
| | | | - Kang-Chieh Huang
- Department of Biology, Indiana University Purdue University, Indianapolis, IN, 46202, USA
| | - Jason S Meyer
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis, IN, 46202, USA
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, IN, 46202, USA
- Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, 46202, USA
| | - Arupratan Das
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis, IN, 46202, USA.
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, IN, 46202, USA.
- Stark Neurosciences Research Institute, Indiana University, Indianapolis, IN, 46202, USA.
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3
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Wan S, Cui Z, Wu L, Zhang F, Liu T, Hu J, Tian J, Yu B, Liu F, Kou J, Li F. Ginsenoside Rd promotes omentin secretion in adipose through TBK1-AMPK to improve mitochondrial biogenesis via WNT5A/Ca 2+ pathways in heart failure. Redox Biol 2023; 60:102610. [PMID: 36652744 PMCID: PMC9860421 DOI: 10.1016/j.redox.2023.102610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
Ginsenoside Rd is an active ingredient in Panax ginseng CA Mey and can be absorbed into the adipose tissue. Adipokines play an important role in the treatment of cardiovascular diseases. However, the potential benefit of Rd on heart failure (HF) and the underlying mechanism associated with the crosstalk between adipocytes and cardiomyocytes remains to be illustrated. Here, the results identified that Rd improved cardiac function and inhibited cardiac pathological changes in transverse aortic constriction (TAC), coronary ligation (CAL) and isoproterenol (ISO)-induced HF mice. And Rd promoted the release of omentin from the adipose tissue and up-regulated omentin expression in lipopolysaccharide (LPS)-induced 3T3-L1 adipocytes. Further, Rd could increase TBK1 and AMPK phosphorylation in adipocytes. And also, the TBK1-AMPK signaling pathway regulated the expression of omentin in LPS-induced adipocytes. Moreover, the omentin mRNA expression was significantly decreased by TBK1 knockdown in LPS-induced 3T3-L1 adipocytes. Additionally, molecular docking and SPR analysis confirmed that Rd had a certain binding ability with TBK1, and co-treatment with TBK1 inhibitors or TBK1 knockdown partially abolished the effect of Rd on increasing the omentin expression and the ratio of p-AMPK to AMPK in adipocytes. Moreover, we found that circulating omentin level diminished in the HF patients compared with healthy subjects. Meanwhile, the adipose tissue-specific overexpression of omentin improved cardiac function, reduced myocardial infarct size and ameliorated cardiac pathological features in CAL-induced HF mice. Consistently, exogenous omentin reduced mtROS levels and restored ΔψM to improve oxygen and glucose deprivation (OGD)-induced cardiomyocytes injury. Further, omentin inhibited the WNT5A/Ca2+ signaling pathway and promoted mitochondrial biogenesis function to ameliorate myocardial ischemia injury. However, WNT5A knockdown inhibited the impairment of mitochondrial biogenesis and partially counteracted the cardioprotective effect of omentin in vitro. Therefore, this study indicated that Rd promoted omentin secretion from adipocytes through the TBK1-AMPK pathway to improve mitochondrial biogenesis function via WNT5A/Ca2+ signaling pathway to ameliorate myocardial ischemia injury, which provided a new therapeutic mechanism and potential drugs for the treatment of HF.
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Affiliation(s)
- Shiyao Wan
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - ZeKun Cui
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Lingling Wu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Fan Zhang
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Tao Liu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Jingui Hu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Jiangwei Tian
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Boyang Yu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Fuming Liu
- Jiangsu Province Hospital of Chinese Medicine, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, 210029, China.
| | - Junping Kou
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
| | - Fang Li
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Research Center for Traceability and Standardization of TCMs, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
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4
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Zhang YX, Ou MY, Yang ZH, Sun Y, Li QF, Zhou SB. Adipose tissue aging is regulated by an altered immune system. Front Immunol 2023; 14:1125395. [PMID: 36875140 PMCID: PMC9981968 DOI: 10.3389/fimmu.2023.1125395] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 01/30/2023] [Indexed: 02/19/2023] Open
Abstract
Adipose tissue is a widely distributed organ that plays a critical role in age-related physiological dysfunctions as an important source of chronic sterile low-grade inflammation. Adipose tissue undergoes diverse changes during aging, including fat depot redistribution, brown and beige fat decrease, functional decline of adipose progenitor and stem cells, senescent cell accumulation, and immune cell dysregulation. Specifically, inflammaging is common in aged adipose tissue. Adipose tissue inflammaging reduces adipose plasticity and pathologically contributes to adipocyte hypertrophy, fibrosis, and ultimately, adipose tissue dysfunction. Adipose tissue inflammaging also contributes to age-related diseases, such as diabetes, cardiovascular disease and cancer. There is an increased infiltration of immune cells into adipose tissue, and these infiltrating immune cells secrete proinflammatory cytokines and chemokines. Several important molecular and signaling pathways mediate the process, including JAK/STAT, NFκB and JNK, etc. The roles of immune cells in aging adipose tissue are complex, and the underlying mechanisms remain largely unclear. In this review, we summarize the consequences and causes of inflammaging in adipose tissue. We further outline the cellular/molecular mechanisms of adipose tissue inflammaging and propose potential therapeutic targets to alleviate age-related problems.
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Affiliation(s)
- Yi-Xiang Zhang
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Min-Yi Ou
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zi-Han Yang
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Sun
- Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qing-Feng Li
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuang-Bai Zhou
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Bodur C, Kazyken D, Huang K, Tooley AS, Cho KW, Barnes TM, Lumeng CN, Myers MG, Fingar DC. TBK1-mTOR Signaling Attenuates Obesity-Linked Hyperglycemia and Insulin Resistance. Diabetes 2022; 71:2297-2312. [PMID: 35983955 PMCID: PMC9630091 DOI: 10.2337/db22-0256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022]
Abstract
The innate immune kinase TBK1 (TANK-binding kinase 1) responds to microbial-derived signals to initiate responses against viral and bacterial pathogens. More recent work implicates TBK1 in metabolism and tumorigenesis. The kinase mTOR (mechanistic target of rapamycin) integrates diverse environmental cues to control fundamental cellular processes. Our prior work demonstrated in cells that TBK1 phosphorylates mTOR (on S2159) to increase mTORC1 and mTORC2 catalytic activity and signaling. Here we investigate a role for TBK1-mTOR signaling in control of glucose metabolism in vivo. We find that mice with diet-induced obesity (DIO) but not lean mice bearing a whole-body "TBK1-resistant" Mtor S2159A knock-in allele (MtorA/A) display exacerbated hyperglycemia and systemic insulin resistance with no change in energy balance. Mechanistically, Mtor S2159A knock-in in DIO mice reduces mTORC1 and mTORC2 signaling in response to insulin and innate immune agonists, reduces anti-inflammatory gene expression in adipose tissue, and blunts anti-inflammatory macrophage M2 polarization, phenotypes shared by mice with tissue-specific inactivation of TBK1 or mTOR complexes. Tissues from DIO mice display elevated TBK1 activity and mTOR S2159 phosphorylation relative to lean mice. We propose a model whereby obesity-associated signals increase TBK1 activity and mTOR phosphorylation, which boost mTORC1 and mTORC2 signaling in parallel to the insulin pathway, thereby attenuating insulin resistance to improve glycemic control during diet-induced obesity.
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Affiliation(s)
- Cagri Bodur
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Dubek Kazyken
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Kezhen Huang
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Aaron Seth Tooley
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Kae Won Cho
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, MI
| | - Tammy M. Barnes
- Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Carey N. Lumeng
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, MI
| | - Martin G. Myers
- Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Diane C. Fingar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
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6
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Zhao P, Sun X, Liao Z, Yu H, Li D, Shen Z, Glass CK, Witztum JL, Saltiel AR. The TBK1/IKKε inhibitor amlexanox improves dyslipidemia and prevents atherosclerosis. JCI Insight 2022; 7:155552. [PMID: 35917178 PMCID: PMC9536260 DOI: 10.1172/jci.insight.155552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 07/27/2022] [Indexed: 01/09/2023] Open
Abstract
Cardiovascular diseases, especially atherosclerosis and its complications, are a leading cause of death. Inhibition of the noncanonical IκB kinases TANK-binding kinase 1 and IKKε with amlexanox restores insulin sensitivity and glucose homeostasis in diabetic mice and human patients. Here we report that amlexanox improves diet-induced hypertriglyceridemia and hypercholesterolemia in Western diet-fed (WD-fed) Ldlr-/- mice and protects against atherogenesis. Amlexanox ameliorated dyslipidemia, inflammation, and vascular dysfunction through synergistic actions that involve upregulation of bile acid synthesis to increase cholesterol excretion. Transcriptomic profiling demonstrated an elevated expression of key bile acid synthesis genes. Furthermore, we found that amlexanox attenuated monocytosis, eosinophilia, and vascular dysfunction during WD-induced atherosclerosis. These findings demonstrate the potential of amlexanox as a therapy for hypercholesterolemia and atherosclerosis.
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Affiliation(s)
- Peng Zhao
- Department of Biochemistry and Structural Biology and,Mays Cancer Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.,Department of Medicine, University of California, San Diego (UCSD), La Jolla, California, USA
| | - Xiaoli Sun
- Mays Cancer Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.,Department of Medicine, University of California, San Diego (UCSD), La Jolla, California, USA.,Department of Pharmacology and,Transplant Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Zhongji Liao
- Department of Medicine, University of California, San Diego (UCSD), La Jolla, California, USA
| | - Hong Yu
- Department of Pharmacology and
| | - Dan Li
- Department of Biochemistry and Structural Biology and
| | - Zeyang Shen
- Department of Cellular and Molecular Medicine, School of Medicine;,Department of Bioengineering, Jacobs School of Engineering; and
| | - Christopher K. Glass
- Department of Medicine, University of California, San Diego (UCSD), La Jolla, California, USA.,Department of Cellular and Molecular Medicine, School of Medicine
| | - Joseph L. Witztum
- Department of Medicine, University of California, San Diego (UCSD), La Jolla, California, USA
| | - Alan R. Saltiel
- Department of Medicine, University of California, San Diego (UCSD), La Jolla, California, USA.,Department of Pharmacology, School of Medicine, UCSD, La Jolla, California, USA
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7
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Bai J, Liu F. cGAS‒STING signaling and function in metabolism and kidney diseases. J Mol Cell Biol 2021; 13:728-738. [PMID: 34665236 PMCID: PMC8718186 DOI: 10.1093/jmcb/mjab066] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 12/03/2022] Open
Abstract
The cyclic GMP‒AMP synthase (cGAS)‒stimulator of interferon genes (STING) signaling pathway senses the presence of cytosolic DNA and, in turn, triggers downstream signaling to induce the expression of inflammatory and type I interferon genes in immune cells. Whereas the innate immune function of the cGAS‒STING pathway is well studied over the past years, emerging evidence suggests that this signaling pathway may have additional functions beyond innate immune surveillance. Consistent with this notion, dysregulation of the cGAS‒STING signaling pathway in adipocytes, hepatocytes, and renal proximal tubule epithelial cells are associated with metabolic dysfunction, impaired energy homeostasis, and kidney diseases. In this review, we summarize current understanding of the cGAS‒STING pathway in several metabolic diseases such as obesity, insulin resistance, alcoholic and nonalcoholic fatty liver diseases, as well as acute kidney injury and chronic kidney disease. We also review the interaction between the cGAS‒STING pathway and lipid metabolism. Lastly, we discuss potential mechanisms by which cGAS‒STING signaling regulates metabolism and point toward future avenues of research targeting the cGAS‒STING pathway as possible means to treat common metabolic disorders.
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Affiliation(s)
- Juli Bai
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX 78229, USA.,National Clinical Research Center for Metabolic Diseases, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha 410011, China
| | - Feng Liu
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX 78229, USA.,National Clinical Research Center for Metabolic Diseases, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha 410011, China
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8
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Shaw LM. TBK1 has a new Akt. J Biol Chem 2021; 297:101244. [PMID: 34563542 PMCID: PMC8498460 DOI: 10.1016/j.jbc.2021.101244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
TANK-binding kinase 1 (TBK1) is a noncanonical IκB kinase that plays an essential role in the innate immune response to foreign pathogens. Recent studies have highlighted additional roles for TBK1 in the regulation of metabolism, although the mechanisms of this regulation have not been well characterized. In a recent issue, Tooley et al. demonstrated that TBK1-dependent activation of downstream kinase Akt is mediated via mechanistic target of rapamycin complex 2. This novel action of TBK1 reveals a key role for this kinase in the regulation of cellular metabolism and growth by diverse environmental inputs.
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Affiliation(s)
- Leslie M Shaw
- Department of Molecular, Cell & Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA.
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Tooley AS, Kazyken D, Bodur C, Gonzalez IE, Fingar DC. The innate immune kinase TBK1 directly increases mTORC2 activity and downstream signaling to Akt. J Biol Chem 2021; 297:100942. [PMID: 34245780 PMCID: PMC8342794 DOI: 10.1016/j.jbc.2021.100942] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/21/2021] [Accepted: 07/06/2021] [Indexed: 02/06/2023] Open
Abstract
TBK1 responds to microbes to initiate cellular responses critical for host innate immune defense. We found previously that TBK1 phosphorylates mTOR (mechanistic target of rapamycin) on S2159 to increase mTOR complex 1 (mTORC1) signaling in response to the growth factor EGF and the viral dsRNA mimetic poly(I:C). mTORC1 and the less well studied mTORC2 respond to diverse cues to control cellular metabolism, proliferation, and survival. Although TBK1 has been linked to Akt phosphorylation, a direct relationship between TBK1 and mTORC2, an Akt kinase, has not been described. By studying MEFs lacking TBK1, as well as MEFs, macrophages, and mice bearing an Mtor S2159A knock-in allele (MtorA/A) using in vitro kinase assays and cell-based approaches, we demonstrate here that TBK1 activates mTOR complex 2 (mTORC2) directly to increase Akt phosphorylation. We find that TBK1 and mTOR S2159 phosphorylation promotes mTOR-dependent phosphorylation of Akt in response to several growth factors and poly(I:C). Mechanistically, TBK1 coimmunoprecipitates with mTORC2 and phosphorylates mTOR S2159 within mTORC2 in cells. Kinase assays demonstrate that TBK1 and mTOR S2159 phosphorylation increase mTORC2 intrinsic catalytic activity. Growth factors failed to activate TBK1 or increase mTOR S2159 phosphorylation in MEFs. Thus, basal TBK1 activity cooperates with growth factors in parallel to increase mTORC2 (and mTORC1) signaling. Collectively, these results reveal cross talk between TBK1 and mTOR, key regulatory nodes within two major signaling networks. As TBK1 and mTOR contribute to tumorigenesis and metabolic disorders, these kinases may work together in a direct manner in a variety of physiological and pathological settings.
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Affiliation(s)
- Aaron Seth Tooley
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Dubek Kazyken
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Cagri Bodur
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ian E Gonzalez
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Diane C Fingar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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