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Smiles WJ, Ovens AJ, Kemp BE, Galic S, Petersen J, Oakhill JS. New developments in AMPK and mTORC1 cross-talk. Essays Biochem 2024:EBC20240007. [PMID: 38994736 DOI: 10.1042/ebc20240007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 06/27/2024] [Accepted: 06/28/2024] [Indexed: 07/13/2024]
Abstract
Metabolic homeostasis and the ability to link energy supply to demand are essential requirements for all living cells to grow and proliferate. Key to metabolic homeostasis in all eukaryotes are AMPK and mTORC1, two kinases that sense nutrient levels and function as counteracting regulators of catabolism (AMPK) and anabolism (mTORC1) to control cell survival, growth and proliferation. Discoveries beginning in the early 2000s revealed that AMPK and mTORC1 communicate, or cross-talk, through direct and indirect phosphorylation events to regulate the activities of each other and their shared protein substrate ULK1, the master initiator of autophagy, thereby allowing cellular metabolism to rapidly adapt to energy and nutritional state. More recent reports describe divergent mechanisms of AMPK/mTORC1 cross-talk and the elaborate means by which AMPK and mTORC1 are activated at the lysosome. Here, we provide a comprehensive overview of current understanding in this exciting area and comment on new evidence showing mTORC1 feedback extends to the level of the AMPK isoform, which is particularly pertinent for some cancers where specific AMPK isoforms are implicated in disease pathogenesis.
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Affiliation(s)
- William J Smiles
- Metabolic Signalling Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
- Research Program for Receptor Biochemistry and Tumour Metabolism, Department of Paediatrics, University Hospital of the Paracelsus Medical University, Salzburg, Austria
| | - Ashley J Ovens
- Protein Engineering in Immunity and Metabolism, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Bruce E Kemp
- Protein Chemistry and Metabolism, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
- Department of Medicine, University of Melbourne, Parkville, VIC 3010, Australia
- Mary Mackillop Institute for Health Research, Australian Catholic University, Fitzroy, Vic 3065, Vic. Australia
| | - Sandra Galic
- Department of Medicine, University of Melbourne, Parkville, VIC 3010, Australia
- Metabolic Physiology, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Janni Petersen
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, SA 5042, Australia
- Nutrition and Metabolism, South Australia Health and Medical Research Institute, Adelaide, SA 5000, Australia
| | - Jonathan S Oakhill
- Metabolic Signalling Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
- Department of Medicine, University of Melbourne, Parkville, VIC 3010, Australia
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Gao G, Zhao J, Ding J, Liu S, Shen Y, Liu C, Ma H, Fu Y, Xu J, Sun Y, Zhang X, Zhang Z, Xie Z. Alisol B regulates AMPK/mTOR/SREBPs via directly targeting VDAC1 to alleviate hyperlipidemia. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2024; 128:155313. [PMID: 38520833 DOI: 10.1016/j.phymed.2023.155313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 12/03/2023] [Accepted: 12/25/2023] [Indexed: 03/25/2024]
Abstract
BACKGROUND The occurrence of hyperlipidemia is significantly influenced by lipid synthesis, which is regulated by sterol regulatory element binding proteins (SREBPs), thus the development of drugs that inhibit lipid synthesis has become a popular treatment strategy for hyperlipidemia. Alisol B (ALB), a triterpenoid compound extracted from Alisma, has been reported to ameliorate no-nalcoholic steatohepatitis (NASH) and slow obesity. However, the effect of ALB on hyperlipidemia and mechanism are unclear. PURPOSE To examine the therapeutic impact of ALB on hyperlipidemia whether it inhibits SREBPs to reduce lipid synthesis. STUDY DESIGN HepG2, HL7702 cells, and C57BL/6J mice were used to explore the effect of ALB on hyperlipidemia and the molecular mechanism in vivo and in vitro. METHODS Hyperlipidemia models were established using western diet (WD)-fed mice in vivo and oleic acid (OA)-induced hepatocytes in vitro. Western blot, real-time PCR and other biological methods verified that ALB regulated AMPK/mTOR/SREBPs to inhibit lipid synthesis. Cellular thermal shift assay (CETSA), molecular dynamics (MD), and ultrafiltration-LC/MS analysis were used to evaluate the binding of ALB to voltage-dependent anion channel protein-1 (VDAC1). RESULTS ALB decreased TC, TG, LDL-c, and increased HDL-c in blood, thereby ameliorating liver damage. Gene set enrichment analysis (GSEA) indicated that ALB inhibited the biosynthesis of cholesterol and fatty acids. Consistently, ALB inhibited the protein expression of n-SREBPs and downstream genes. Mechanistically, the impact of ALB on SREBPs was dependent on the regulation of AMPK/mTOR, thereby impeding the transportation of SREBPs from endoplasmic reticulum (ER) to golgi apparatus (GA). Further investigations indicated that the activation of AMPK by ALB was independent on classical upstream CAMKK2 and LKB1. Instead, ALB resulted in a decrease in ATP levels and an increase in the ratios of ADP/ATP and AMP/ATP. CETSA, MD, and ultrafiltration-LC/MS analysis indicated that ALB interacted with VDAC1. Molecular docking revealed that ALB directly bound to VDAC1 by forming hydrogen bonds at the amino acid sites S196 and H184 in the ATP-binding region. Importantly, the thermal stabilization of ALB on VDAC1 was compromised when VDAC1 was mutated at S196 and H184, suggesting that these amino acids played a crucial role in the interaction. CONCLUSION Our findings reveal that VDAC1 serves as the target of ALB, leading to the inhibition of lipid synthesis, presents potential target and candidate drugs for hyperlipidemia.
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Affiliation(s)
- Gai Gao
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Jie Zhao
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Jing Ding
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Shuyan Liu
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Yanyan Shen
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Changxin Liu
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Huifen Ma
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Yu Fu
- College of pharmacy, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Jiangyan Xu
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China
| | - Yiran Sun
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China.
| | - Xiaowei Zhang
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China.
| | - Zhenqiang Zhang
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China.
| | - Zhishen Xie
- Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China.
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3
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Hawley SA, Russell FM, Hardie DG. AMP-activated protein kinase can be allosterically activated by ADP but AMP remains the key activating ligand. Biochem J 2024; 481:587-599. [PMID: 38592738 PMCID: PMC11088877 DOI: 10.1042/bcj20240082] [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: 02/26/2024] [Revised: 04/02/2024] [Accepted: 04/09/2024] [Indexed: 04/10/2024]
Abstract
The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status. When activated by increases in ADP:ATP and/or AMP:ATP ratios (signalling energy deficit), AMPK acts to restore energy balance. Binding of AMP to one or more of three CBS repeats (CBS1, CBS3, CBS4) on the AMPK-γ subunit activates the kinase complex by three complementary mechanisms: (i) promoting α-subunit Thr172 phosphorylation by the upstream kinase LKB1; (ii) protecting against Thr172 dephosphorylation; (iii) allosteric activation. Surprisingly, binding of ADP has been reported to mimic the first two effects, but not the third. We now show that at physiologically relevant concentrations of Mg.ATP2- (above those used in the standard assay) ADP binding does cause allosteric activation. However, ADP causes only a modest activation because (unlike AMP), at concentrations just above those where activation becomes evident, ADP starts to cause competitive inhibition at the catalytic site. Our results cast doubt on the physiological relevance of the effects of ADP and suggest that AMP is the primary activator in vivo. We have also made mutations to hydrophobic residues involved in binding adenine nucleotides at each of the three γ subunit CBS repeats of the human α2β2γ1 complex and examined their effects on regulation by AMP and ADP. Mutation of the CBS3 site has the largest effects on all three mechanisms of AMP activation, especially at lower ATP concentrations, while mutation of CBS4 reduces the sensitivity to AMP. All three sites appear to be required for allosteric activation by ADP.
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Affiliation(s)
- Simon A. Hawley
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Fiona M. Russell
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - D. Grahame Hardie
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
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Ding Y, Lv Z, Cao W, Shi W, He Q, Gao K. Phosphorylation of INF2 by AMPK promotes mitochondrial fission and oncogenic function in endometrial cancer. Cell Death Dis 2024; 15:65. [PMID: 38233384 PMCID: PMC10794193 DOI: 10.1038/s41419-024-06431-0] [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: 08/11/2023] [Revised: 12/23/2023] [Accepted: 01/03/2024] [Indexed: 01/19/2024]
Abstract
Mitochondria are highly dynamic organelles capable of altering their sizes and shapes to maintain metabolic balance through coordinated fission and fusion processes. In various cancer types, mitochondrial hyperfragmentation has been frequently observed, contributing to the progression of cancer toward metastasis. Inverted formin 2 (INF2), which resides in the endoplasmic reticulum (ER), has been found to accelerate actin polymerization and drive mitochondrial fission. In this study, we demonstrate that INF2 expression is significantly upregulated in endometrial cancer (EC) and is associated with a poor prognosis in EC patients. INF2 promotes anchorage-dependent and independent EC cell growth in part by facilitating mitochondrial fission. Furthermore, in conditions of energy stress, AMP-activated protein kinase (AMPK) phosphorylates INF2 at Ser1077, leading to increased localization of INF2 to the ER and enhanced recruitment of the dynamin-related protein 1 (DRP1) to mitochondria. This AMPK-mediated phosphorylation of INF2 at Ser1077 facilitates mitochondrial division and promotes EC cell growth. Pathological examination using immunohistochemical analyses revealed a positive correlation between AMPK activity and phosphorylated INF2 (Ser1077) in EC specimens. Collectively, our findings uncover novel molecular mechanisms involving the AMPK-INF2 axis, which regulates mitochondrial dynamics and malignant cell growth in EC.
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Affiliation(s)
- Yan Ding
- Department of Clinical Laboratory, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
| | - Zeheng Lv
- Department of Clinical Laboratory, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
| | - Wenxin Cao
- Department of Clinical Laboratory, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
| | - Wenming Shi
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, 999077, China.
| | - Qizhi He
- Department of Pathology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, PR China.
| | - Kun Gao
- Department of Clinical Laboratory, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China.
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 200092, China.
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Rahman AA, Butcko AJ, Songyekutu E, Granneman JG, Mottillo EP. Direct effects of adipocyte lipolysis on AMPK through intracellular long-chain acyl-CoA signaling. Sci Rep 2024; 14:19. [PMID: 38167670 PMCID: PMC10761689 DOI: 10.1038/s41598-023-50903-w] [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: 09/21/2023] [Accepted: 12/27/2023] [Indexed: 01/05/2024] Open
Abstract
Long-chain acyl-CoAs (LC-acyl-CoAs) are important intermediary metabolites and are also thought to function as intracellular signaling molecules; however, the direct effects of LC-acyl-CoAs have been difficult to determine in real-time and dissociate from Protein Kinase A (PKA) signaling. Here, we examined the direct role of lipolysis in generating intracellular LC-acyl-CoAs and activating AMPK in white adipocytes by pharmacological activation of ABHD5 (also known as CGI-58), a lipase co-activator. Activation of lipolysis in 3T3-L1 adipocytes independent of PKA with synthetic ABHD5 ligands, resulted in greater activation of AMPK compared to receptor-mediated activation with isoproterenol, a β-adrenergic receptor agonist. Importantly, the effect of pharmacological activation of ABHD5 on AMPK activation was blocked by inhibiting ATGL, the rate-limiting enzyme for triacylglycerol hydrolysis. Utilizing a novel FRET sensor to detect intracellular LC-acyl-CoAs, we demonstrate that stimulation of lipolysis in 3T3-L1 adipocytes increased the production of LC-acyl-CoAs, an effect which was blocked by inhibition of ATGL. Moreover, ATGL inhibition blocked AMPKβ1 S108 phosphorylation, a site required for allosteric regulation. Increasing intracellular LC-acyl-CoAs by removal of BSA in the media and pharmacological inhibition of DGAT1 and 2 resulted in greater activation of AMPK. Finally, inhibiting LC-acyl-CoA generation reduced activation of AMPK; however, did not lower energy charge. Overall, results demonstrate that lipolysis in white adipocytes directly results in allosteric activation of AMPK through the generation of LC-acyl-CoAs.
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Affiliation(s)
- Abir A Rahman
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Ave., Detroit, MI, 48202, USA
| | - Andrew J Butcko
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Ave., Detroit, MI, 48202, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - Emmanuel Songyekutu
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - Emilio P Mottillo
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Ave., Detroit, MI, 48202, USA.
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48202, USA.
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6
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Ross FA, Hawley SA, Russell FM, Goodman N, Hardie DG. Frequent loss-of-function mutations in the AMPK-α2 catalytic subunit suggest a tumour suppressor role in human skin cancers. Biochem J 2023; 480:1951-1968. [PMID: 37962491 PMCID: PMC10754287 DOI: 10.1042/bcj20230380] [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: 09/07/2023] [Revised: 11/07/2023] [Accepted: 11/13/2023] [Indexed: 11/15/2023]
Abstract
The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status activated by increases in AMP or ADP relative to ATP. Once activated, it phosphorylates targets that promote ATP-generating catabolic pathways or inhibit ATP-consuming anabolic pathways, helping to restore cellular energy balance. Analysis of human cancer genome studies reveals that the PRKAA2 gene (encoding the α2 isoform of the catalytic subunit) is often subject to mis-sense mutations in cancer, particularly in melanoma and non-melanoma skin cancers, where up to 70 mis-sense mutations have been documented, often accompanied by loss of the tumour suppressor NF1. Recently it has been reported that knockout of PRKAA2 in NF1-deficient melanoma cells promoted anchorage-independent growth in vitro, as well as growth as xenografts in immunodeficient mice in vivo, suggesting that AMPK-α2 can act as a tumour suppressor in that context. However, very few of the mis-sense mutations in PRKAA2 that occur in human skin cancer and melanoma have been tested to see whether they cause loss-of-function. We have addressed this by making most of the reported mutations and testing their activity when expressed in AMPK knockout cells. Of 55 different mis-sense mutations (representing 75 cases), 9 (12%) appeared to cause a total loss of activity, 18 (24%) a partial loss, 11 (15%) an increase in phenformin-stimulated kinase activity, while just 37 (49%) had no clear effect on kinase activity. This supports the idea that AMPK-α2 acts as a tumour suppressor in the context of human skin cancer.
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Affiliation(s)
- Fiona A. Ross
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Scotland, U.K
| | - Simon A. Hawley
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Scotland, U.K
| | - Fiona M. Russell
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Scotland, U.K
| | - Nicola Goodman
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Scotland, U.K
| | - D. Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Scotland, U.K
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7
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Steinberg GR, Hardie DG. New insights into activation and function of the AMPK. Nat Rev Mol Cell Biol 2023; 24:255-272. [PMID: 36316383 DOI: 10.1038/s41580-022-00547-x] [Citation(s) in RCA: 156] [Impact Index Per Article: 156.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2022] [Indexed: 11/06/2022]
Abstract
The classical role of AMP-activated protein kinase (AMPK) is as a cellular energy sensor activated by falling energy status, signalled by increases in AMP to ATP and ADP to ATP ratios. Once activated, AMPK acts to restore energy homeostasis by promoting ATP-producing catabolic pathways while inhibiting energy-consuming processes. In this Review, we provide an update on this canonical (AMP/ADP-dependent) activation mechanism, but focus mainly on recently described non-canonical pathways, including those by which AMPK senses the availability of glucose, glycogen or fatty acids and by which it senses damage to lysosomes and nuclear DNA. We also discuss new findings on the regulation of carbohydrate and lipid metabolism, mitochondrial and lysosomal homeostasis, and DNA repair. Finally, we discuss the role of AMPK in cancer, obesity, diabetes, nonalcoholic steatohepatitis (NASH) and other disorders where therapeutic targeting may exert beneficial effects.
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Affiliation(s)
- Gregory R Steinberg
- Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada.
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee, UK.
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8
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Hsu CC, Peng D, Cai Z, Lin HK. AMPK signaling and its targeting in cancer progression and treatment. Semin Cancer Biol 2022; 85:52-68. [PMID: 33862221 PMCID: PMC9768867 DOI: 10.1016/j.semcancer.2021.04.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/06/2021] [Accepted: 04/07/2021] [Indexed: 12/24/2022]
Abstract
The intrinsic mechanisms sensing the imbalance of energy in cells are pivotal for cell survival under various environmental insults. AMP-activated protein kinase (AMPK) serves as a central guardian maintaining energy homeostasis by orchestrating diverse cellular processes, such as lipogenesis, glycolysis, TCA cycle, cell cycle progression and mitochondrial dynamics. Given that AMPK plays an essential role in the maintenance of energy balance and metabolism, managing AMPK activation is considered as a promising strategy for the treatment of metabolic disorders such as type 2 diabetes and obesity. Since AMPK has been attributed to aberrant activation of metabolic pathways, mitochondrial dynamics and functions, and epigenetic regulation, which are hallmarks of cancer, targeting AMPK may open up a new avenue for cancer therapies. Although AMPK is previously thought to be involved in tumor suppression, several recent studies have unraveled its tumor promoting activity. The double-edged sword characteristics for AMPK as a tumor suppressor or an oncogene are determined by distinct cellular contexts. In this review, we will summarize recent progress in dissecting the upstream regulators and downstream effectors for AMPK, discuss the distinct roles of AMPK in cancer regulation and finally offer potential strategies with AMPK targeting in cancer therapy.
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Affiliation(s)
- Che-Chia Hsu
- Department of Cancer Biology, Wake Forest Baptist Medical Center, Wake Forest University, Winston-Salem, NC, 27101, USA
| | - Danni Peng
- Department of Cancer Biology, Wake Forest Baptist Medical Center, Wake Forest University, Winston-Salem, NC, 27101, USA
| | - Zhen Cai
- Department of Cancer Biology, Wake Forest Baptist Medical Center, Wake Forest University, Winston-Salem, NC, 27101, USA.
| | - Hui-Kuan Lin
- Department of Cancer Biology, Wake Forest Baptist Medical Center, Wake Forest University, Winston-Salem, NC, 27101, USA.
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Tarasiuk O, Miceli M, Di Domizio A, Nicolini G. AMPK and Diseases: State of the Art Regulation by AMPK-Targeting Molecules. BIOLOGY 2022; 11:biology11071041. [PMID: 36101419 PMCID: PMC9312068 DOI: 10.3390/biology11071041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/04/2022] [Accepted: 07/06/2022] [Indexed: 11/16/2022]
Abstract
5′-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is an enzyme that regulates cellular energy homeostasis, glucose, fatty acid uptake, and oxidation at low cellular ATP levels. AMPK plays an important role in several molecular mechanisms and physiological conditions. It has been shown that AMPK can be dysregulated in different chronic diseases, such as inflammation, diabetes, obesity, and cancer. Due to its fundamental role in physiological and pathological cellular processes, AMPK is considered one of the most important targets for treating different diseases. Over decades, different AMPK targeting compounds have been discovered, starting from those that activate AMPK indirectly by altering intracellular AMP:ATP ratio to compounds that activate AMPK directly by binding to its activation sites. However, indirect altering of intracellular AMP:ATP ratio influences different cellular processes and induces side effects. Direct AMPK activators showed more promising results in eliminating side effects as well as the possibility to engineer drugs for specific AMPK isoforms activation. In this review, we discuss AMPK targeting drugs, especially concentrating on those compounds that activate AMPK by mimicking AMP. These compounds are poorly described in the literature and still, a lot of questions remain unanswered about the exact mechanism of AMP regulation. Future investigation of the mechanism of AMP binding will make it possible to develop new compounds that, in combination with others, can activate AMPK in a synergistic manner.
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Affiliation(s)
- Olga Tarasiuk
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy;
- Correspondence:
| | - Matteo Miceli
- SPILLOproject—Innovative In Silico Solutions for Drug R&D and Pharmacology, 20037 Paderno Dugnano, Italy; (M.M.); (A.D.D.)
| | - Alessandro Di Domizio
- SPILLOproject—Innovative In Silico Solutions for Drug R&D and Pharmacology, 20037 Paderno Dugnano, Italy; (M.M.); (A.D.D.)
| | - Gabriella Nicolini
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy;
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Anti-Diabetic Effects of Cucurbitacins from Ibervillea lindheimeri on Induced Mouse Diabetes. J CHEM-NY 2022. [DOI: 10.1155/2022/3379557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mexico has a great tradition of using medicinal plants against diabetes. For example, species from the genus Ibervillea traditionally known as “wereque” in Mexican popular medicine have a long ethnobotanical history as anti-diabetic agents. Previous studies by our group indicated that ethyl acetate extract from Ibervillea lindheimeri (I. lindheimeri) roots reduced glucose in mice with chemically induced diabetes. In this work, the primary metabolites of the ethyl acetate extract of I. lindheimeri; 23,24-dihydrocucurbitacin D (1); 2-O-β glucopyranosyl-23,24-dihydrocucurbitacin D (2), and acetylated compounds (3) and (4) obtained from 1 and 2, respectively, were evaluated as anti-hyperglycemic agents in a murine model of chemically induced diabetes. Our results showed that cucurbitacins 1, 2, and 4 reduced glycemia in diabetic CD1 mice compared to the control diabetic group. In addition, the results suggest that compounds 1, 2, and 4 promote glucose transporter type 4 (Glut4) translocation to the plasma membrane (PM) mainly in epididymal adipose tissue (EAT), AMP-activated protein kinase (AMPK) activation in soleus muscle (SM) or dual activation of AMPK, and protein kinase B (AKT) in EAT in an insulin-independent manner when compared to controls. All results together indicate that the isolated cucurbitacins are responsible for the anti-diabetic properties of I. lindheimeri acting predominantly on adipose tissue and call attention to this species as a new source of anti-diabetic compounds.
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Rajan P, Natraj P, Ranaweera SS, Dayarathne LA, Lee YJ, Han CH. Anti-adipogenic effect of the flavonoids through the activation of AMPK in palmitate (PA)-treated HepG2 cells. J Vet Sci 2022; 23:e4. [PMID: 35088951 PMCID: PMC8799946 DOI: 10.4142/jvs.21256] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/20/2021] [Accepted: 11/03/2021] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Flavonoids are natural polyphenols found widely in citrus fruit and peel that possess anti-adipogenic effects. On the other hand, the detailed mechanisms for the anti-adipogenic effects of flavonoids are unclear. OBJECTIVES The present study observed the anti-adipogenic effects of five major citrus flavonoids, including hesperidin (HES), narirutin (NAR), nobiletin (NOB), sinensetin (SIN), and tangeretin (TAN), on AMP-activated protein kinase (AMPK) activation in palmitate (PA)-treated HepG2 cells. METHODS The intracellular lipid accumulation and triglyceride (TG) contents were quantified by Oil-red O staining and TG assay, respectively. The glucose uptake was assessed using 2-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose (2-NBDG) assay. The levels of AMPK, acetyl-CoA carboxylase (ACC), and glycogen synthase kinase 3 beta (GSK3β) phosphorylation, and levels of sterol regulatory element-binding protein 2 (SREBP-2) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) expression were analyzed by Western blot analysis. The potential interaction between the flavonoids and the γ-subunit of AMPK was investigated by molecular docking analysis. RESULTS The flavonoid treatment reduced both intracellular lipid accumulation and TG content in PA-treated HepG2 cells significantly. In addition, the flavonoids showed increased 2-NBDG uptake in an insulin-independent manner in PA-treated HepG2 cells. The flavonoids increased the AMPK, ACC, and GSK3β phosphorylation levels and decreased the SREBP-2 and HMGCR expression levels in PA-treated HepG2 cells. Molecular docking analysis showed that the flavonoids bind to the CBS domains in the regulatory γ-subunit of AMPK with high binding affinities and could serve as potential AMPK activators. CONCLUSION The overall results suggest that the anti-adipogenic effect of flavonoids on PA-treated HepG2 cells results from the activation of AMPK by flavonoids.
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Affiliation(s)
- Priyanka Rajan
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea
| | - Premkumar Natraj
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea
| | | | | | - Young Jae Lee
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea
| | - Chang-Hoon Han
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea.
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12
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Trefts E, Shaw RJ. AMPK: restoring metabolic homeostasis over space and time. Mol Cell 2021; 81:3677-3690. [PMID: 34547233 DOI: 10.1016/j.molcel.2021.08.015] [Citation(s) in RCA: 145] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 12/25/2022]
Abstract
The evolution of AMPK and its homologs enabled exquisite responsivity and control of cellular energetic homeostasis. Recent work has been critical in establishing the mechanisms that determine AMPK activity, novel targets of AMPK action, and the distribution of AMPK-mediated control networks across the cellular landscape. The role of AMPK as a hub of metabolic control has led to intense interest in pharmacologic activation as a therapeutic avenue for a number of disease states, including obesity, diabetes, and cancer. As such, critical work on the compartmentalization of AMPK, its downstream targets, and the systems it influences has progressed in recent years. The variegated distribution of AMPK-mediated control of metabolic homeostasis has revealed key insights into AMPK in normal biology and future directions for AMPK-based therapeutic strategies.
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Affiliation(s)
- Elijah Trefts
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Reuben J Shaw
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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13
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Yan Y, Mukherjee S, Harikumar KG, Strutzenberg TS, Zhou XE, Suino-Powell K, Xu TH, Sheldon RD, Lamp J, Brunzelle JS, Radziwon K, Ellis A, Novick SJ, Vega IE, Jones RG, Miller LJ, Xu HE, Griffin PR, Kossiakoff AA, Melcher K. Structure of an AMPK complex in an inactive, ATP-bound state. Science 2021; 373:413-419. [PMID: 34437114 DOI: 10.1126/science.abe7565] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 03/31/2021] [Accepted: 06/07/2021] [Indexed: 12/15/2022]
Abstract
Adenosine monophosphate (AMP)-activated protein kinase (AMPK) regulates metabolism in response to the cellular energy states. Under energy stress, AMP stabilizes the active AMPK conformation, in which the kinase activation loop (AL) is protected from protein phosphatases, thus keeping the AL in its active, phosphorylated state. At low AMP:ATP (adenosine triphosphate) ratios, ATP inhibits AMPK by increasing AL dynamics and accessibility. We developed conformation-specific antibodies to trap ATP-bound AMPK in a fully inactive, dynamic state and determined its structure at 3.5-angstrom resolution using cryo-electron microscopy. A 180° rotation and 100-angstrom displacement of the kinase domain fully exposes the AL. On the basis of the structure and supporting biophysical data, we propose a multistep mechanism explaining how adenine nucleotides and pharmacological agonists modulate AMPK activity by altering AL phosphorylation and accessibility.
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Affiliation(s)
- Yan Yan
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Kaleeckal G Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - Timothy S Strutzenberg
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USA
| | - X Edward Zhou
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Kelly Suino-Powell
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Ting-Hai Xu
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI 49503, USA.,Center for Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Ryan D Sheldon
- Metabolic and Nutritional Programming, Center for Cancer and Cell Biology, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Jared Lamp
- Integrated Mass Spectrometry Unit, Department of Translational Neuroscience, Michigan State University College of Human Medicine, Grand Rapids Research Center, Grand Rapids, MI 49503, USA
| | - Joseph S Brunzelle
- Life Sciences Collaborative Access Team, Northwestern University Synchrotron Research Center, Northwestern University, Argonne, IL 60439, USA
| | - Katarzyna Radziwon
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Abigail Ellis
- Metabolic and Nutritional Programming, Center for Cancer and Cell Biology, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Scott J Novick
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USA
| | - Irving E Vega
- Integrated Mass Spectrometry Unit, Department of Translational Neuroscience, Michigan State University College of Human Medicine, Grand Rapids Research Center, Grand Rapids, MI 49503, USA
| | - Russell G Jones
- Metabolic and Nutritional Programming, Center for Cancer and Cell Biology, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - H Eric Xu
- Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Patrick R Griffin
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.,Institute of Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Karsten Melcher
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI 49503, USA.
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14
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Li M, Rehman AU, Liu Y, Chen K, Lu S. Dual roles of ATP-binding site in protein kinases: Orthosteric inhibition and allosteric regulation. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 124:87-119. [PMID: 33632471 DOI: 10.1016/bs.apcsb.2020.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein kinases use ATP to phosphorylate other proteins. Phosphorylation (p) universally orchestrates a fine-tuned network modulating a multitude of biological processes. Moreover, the start of networks, ATP-binding site, has been recognized dual roles to impact protein kinases function: (i) orthosteric inhibition, via being blocked to interference ATP occupying and (ii) allosteric regulation, via being altered first to induce further conformational changes. The above two terminologies are widely used in drug design, which has acquired quite a significant progress in the protein kinases field over the past 2 decades. Most small molecular inhibitors directly compete with ATP to implement orthosteric inhibition, still exhibiting irreplaceable and promising therapeutic effects. Additionally, numerous inhibitors can paradoxically lead protein kinases to hyperphosphorylation, even activation, indicative of the allosteric regulation role of the ATP-binding site. Here, we review the quintessential examples that apply for the dual roles in diverse ways. Our work provides an insight into the molecular mechanisms under the dual roles and will be promisingly instructive for future drug development.
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Affiliation(s)
- Mingyu Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Ashfaq Ur Rehman
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Yaqin Liu
- Medicinal Chemistry and Bioinformatics Centre, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Kai Chen
- Department of Orthopedics, Changhai Hospital, Naval Military Medical University, Shanghai, China.
| | - Shaoyong Lu
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China; Medicinal Chemistry and Bioinformatics Centre, Shanghai Jiao Tong University, School of Medicine, Shanghai, China.
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15
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Ovens AJ, Scott JW, Langendorf CG, Kemp BE, Oakhill JS, Smiles WJ. Post-Translational Modifications of the Energy Guardian AMP-Activated Protein Kinase. Int J Mol Sci 2021; 22:ijms22031229. [PMID: 33513781 PMCID: PMC7866021 DOI: 10.3390/ijms22031229] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 01/13/2023] Open
Abstract
Physical exercise elicits physiological metabolic perturbations such as energetic and oxidative stress; however, a diverse range of cellular processes are stimulated in response to combat these challenges and maintain cellular energy homeostasis. AMP-activated protein kinase (AMPK) is a highly conserved enzyme that acts as a metabolic fuel sensor and is central to this adaptive response to exercise. The complexity of AMPK’s role in modulating a range of cellular signalling cascades is well documented, yet aside from its well-characterised regulation by activation loop phosphorylation, AMPK is further subject to a multitude of additional regulatory stimuli. Therefore, in this review we comprehensively outline current knowledge around the post-translational modifications of AMPK, including novel phosphorylation sites, as well as underappreciated roles for ubiquitination, sumoylation, acetylation, methylation and oxidation. We provide insight into the physiological ramifications of these AMPK modifications, which not only affect its activity, but also subcellular localisation, nutrient interactions and protein stability. Lastly, we highlight the current knowledge gaps in this area of AMPK research and provide perspectives on how the field can apply greater rigour to the characterisation of novel AMPK regulatory modifications.
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Affiliation(s)
- Ashley J. Ovens
- Metabolic Signalling Laboratory, St Vincent’s Institute of Medical Research, School of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia; (A.J.O.); (J.S.O.)
- Mary MacKillop Institute for Health Research, Australian Catholic University, Fitzroy, VIC 3000, Australia; (J.W.S.); (B.E.K.)
| | - John W. Scott
- Mary MacKillop Institute for Health Research, Australian Catholic University, Fitzroy, VIC 3000, Australia; (J.W.S.); (B.E.K.)
- Protein Chemistry & Metabolism, St Vincent’s Institute of Medical Research, School of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia;
- The Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia
| | - Christopher G. Langendorf
- Protein Chemistry & Metabolism, St Vincent’s Institute of Medical Research, School of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia;
| | - Bruce E. Kemp
- Mary MacKillop Institute for Health Research, Australian Catholic University, Fitzroy, VIC 3000, Australia; (J.W.S.); (B.E.K.)
- Protein Chemistry & Metabolism, St Vincent’s Institute of Medical Research, School of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia;
| | - Jonathan S. Oakhill
- Metabolic Signalling Laboratory, St Vincent’s Institute of Medical Research, School of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia; (A.J.O.); (J.S.O.)
- Mary MacKillop Institute for Health Research, Australian Catholic University, Fitzroy, VIC 3000, Australia; (J.W.S.); (B.E.K.)
| | - William J. Smiles
- Metabolic Signalling Laboratory, St Vincent’s Institute of Medical Research, School of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia; (A.J.O.); (J.S.O.)
- Correspondence:
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16
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Alghamdi F, Alshuweishi Y, Salt IP. Regulation of nutrient uptake by AMP-activated protein kinase. Cell Signal 2020; 76:109807. [DOI: 10.1016/j.cellsig.2020.109807] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 02/07/2023]
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17
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Ayinde KS, Olaoba OT, Ibrahim B, Lei D, Lu Q, Yin X, Adelusi TI. AMPK allostery: A therapeutic target for the management/treatment of diabetic nephropathy. Life Sci 2020; 261:118455. [PMID: 32956662 DOI: 10.1016/j.lfs.2020.118455] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/08/2020] [Accepted: 09/13/2020] [Indexed: 12/11/2022]
Abstract
Diabetic nephropathy (DN) is a chronic complication of diabetes mellitus (DM) with approximately 30-40% of patients with DM developing nephropathy, and it is the leading cause of end-stage renal diseases and diabetic morbidity. The pathogenesis of DN is primarily associated with irregularities in the metabolism of glucose and lipid leading to hyperglycemia-induced oxidative stress, which has been a major target together with blood pressure regulation in the control of DN progression. However, the regulation of 5' adenosine monophosphate-activated protein kinase (AMPK), a highly conserved protein kinase for maintaining energy balance and cellular growth and repair has been implicated in the development of DM and its complications. Therefore, targeting AMPK pathway has been explored as a therapeutic strategy for the treatment of diabetes and its complication, although most of the mechanisms have not been fully elucidated. In this review, we discuss the structure of AMPK relevant to understanding its allosteric regulation and its role in the pathogenesis and progression of DN. We also identify therapeutic agents that modulate AMPK and its downstream targets with their specific mechanisms of action in the treatment of DN.
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Affiliation(s)
| | - Olamide Tosin Olaoba
- Laboratory of Functional and Structural Biochemistry, Federal University of Sao Carlos, Sao Carlos, SP, Brazil
| | - Boyenle Ibrahim
- Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Du Lei
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou 221004, China
| | - Qian Lu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou 221004, China
| | - Xiaoxing Yin
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou 221004, China
| | - Temitope Isaac Adelusi
- Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria; Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou 221004, China.
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18
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González A, Hall MN, Lin SC, Hardie DG. AMPK and TOR: The Yin and Yang of Cellular Nutrient Sensing and Growth Control. Cell Metab 2020; 31:472-492. [PMID: 32130880 DOI: 10.1016/j.cmet.2020.01.015] [Citation(s) in RCA: 385] [Impact Index Per Article: 96.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The AMPK (AMP-activated protein kinase) and TOR (target-of-rapamycin) pathways are interlinked, opposing signaling pathways involved in sensing availability of nutrients and energy and regulation of cell growth. AMPK (Yin, or the "dark side") is switched on by lack of energy or nutrients and inhibits cell growth, while TOR (Yang, or the "bright side") is switched on by nutrient availability and promotes cell growth. Genes encoding the AMPK and TOR complexes are found in almost all eukaryotes, suggesting that these pathways arose very early during eukaryotic evolution. During the development of multicellularity, an additional tier of cell-extrinsic growth control arose that is mediated by growth factors, but these often act by modulating nutrient uptake so that AMPK and TOR remain the underlying regulators of cellular growth control. In this review, we discuss the evolution, structure, and regulation of the AMPK and TOR pathways and the complex mechanisms by which they interact.
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Affiliation(s)
- Asier González
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Sheng-Cai Lin
- School of Life Sciences, Xiamen University, Xiamen, 361102 Fujian, China
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
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19
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Steinberg GR, Carling D. AMP-activated protein kinase: the current landscape for drug development. Nat Rev Drug Discov 2020; 18:527-551. [PMID: 30867601 DOI: 10.1038/s41573-019-0019-2] [Citation(s) in RCA: 383] [Impact Index Per Article: 95.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Since the discovery of AMP-activated protein kinase (AMPK) as a central regulator of energy homeostasis, many exciting insights into its structure, regulation and physiological roles have been revealed. While exercise, caloric restriction, metformin and many natural products increase AMPK activity and exert a multitude of health benefits, developing direct activators of AMPK to elicit beneficial effects has been challenging. However, in recent years, direct AMPK activators have been identified and tested in preclinical models, and a small number have entered clinical trials. Despite these advances, which disease(s) represent the best indications for therapeutic AMPK activation and the long-term safety of such approaches remain to be established.
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Affiliation(s)
- Gregory R Steinberg
- Centre for Metabolism, Obesity and Diabetes Research, Department of Medicine and Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
| | - David Carling
- Cellular Stress Group, Medical Research Council London Institute of Medical Sciences, Hammersmith Hospital, Imperial College, London, UK
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20
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Vara-Ciruelos D, Russell FM, Hardie DG. The strange case of AMPK and cancer: Dr Jekyll or Mr Hyde? †. Open Biol 2019; 9:190099. [PMID: 31288625 PMCID: PMC6685927 DOI: 10.1098/rsob.190099] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 06/11/2019] [Indexed: 02/06/2023] Open
Abstract
The AMP-activated protein kinase (AMPK) acts as a cellular energy sensor. Once switched on by increases in cellular AMP : ATP ratios, it acts to restore energy homeostasis by switching on catabolic pathways while switching off cell growth and proliferation. The canonical AMP-dependent mechanism of activation requires the upstream kinase LKB1, which was identified genetically to be a tumour suppressor. AMPK can also be switched on by increases in intracellular Ca2+, by glucose starvation and by DNA damage via non-canonical, AMP-independent pathways. Genetic studies of the role of AMPK in mouse cancer suggest that, before disease arises, AMPK acts as a tumour suppressor that protects against cancer, with this protection being further enhanced by AMPK activators such as the biguanide phenformin. However, once cancer has occurred, AMPK switches to being a tumour promoter instead, enhancing cancer cell survival by protecting against metabolic, oxidative and genotoxic stresses. Studies of genetic changes in human cancer also suggest diverging roles for genes encoding subunit isoforms, with some being frequently amplified, while others are mutated.
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Affiliation(s)
| | | | - D. Grahame Hardie
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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21
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Zong Y, Zhang CS, Li M, Wang W, Wang Z, Hawley SA, Ma T, Feng JW, Tian X, Qi Q, Wu YQ, Zhang C, Ye Z, Lin SY, Piao HL, Hardie DG, Lin SC. Hierarchical activation of compartmentalized pools of AMPK depends on severity of nutrient or energy stress. Cell Res 2019; 29:460-473. [PMID: 30948787 DOI: 10.1038/s41422-019-0163-6] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 03/15/2019] [Indexed: 01/17/2023] Open
Abstract
AMPK, a master regulator of metabolic homeostasis, is activated by both AMP-dependent and AMP-independent mechanisms. The conditions under which these different mechanisms operate, and their biological implications are unclear. Here, we show that, depending on the degree of elevation of cellular AMP, distinct compartmentalized pools of AMPK are activated, phosphorylating different sets of targets. Low glucose activates AMPK exclusively through the AMP-independent, AXIN-based pathway in lysosomes to phosphorylate targets such as ACC1 and SREBP1c, exerting early anti-anabolic and pro-catabolic roles. Moderate increases in AMP expand this to activate cytosolic AMPK also in an AXIN-dependent manner. In contrast, high concentrations of AMP, arising from severe nutrient stress, activate all pools of AMPK independently of AXIN. Surprisingly, mitochondrion-localized AMPK is activated to phosphorylate ACC2 and mitochondrial fission factor (MFF) only during severe nutrient stress. Our findings reveal a spatiotemporal basis for hierarchical activation of different pools of AMPK during differing degrees of stress severity.
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Affiliation(s)
- Yue Zong
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Chen-Song Zhang
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Mengqi Li
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Wen Wang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023, Dalian, China.,University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Zhichao Wang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023, Dalian, China.,University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Simon A Hawley
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK
| | - Teng Ma
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Jin-Wei Feng
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Xiao Tian
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Qu Qi
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Yu-Qing Wu
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Cixiong Zhang
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Zhiyun Ye
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Shu-Yong Lin
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China
| | - Hai-Long Piao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023, Dalian, China.,University of Chinese Academy of Sciences, 100049, Beijing, China
| | - D Grahame Hardie
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK
| | - Sheng-Cai Lin
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, 361102, Fujian, China.
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22
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Synthetic energy sensor AMPfret deciphers adenylate-dependent AMPK activation mechanism. Nat Commun 2019; 10:1038. [PMID: 30833561 PMCID: PMC6399333 DOI: 10.1038/s41467-019-08938-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 02/04/2019] [Indexed: 02/07/2023] Open
Abstract
AMP-activated protein kinase AMPK senses and regulates cellular energy state. AMPK activation by increasing AMP and ADP concentrations involves a conformational switch within the heterotrimeric complex. This is exploited here for the construction of a synthetic sensor of cellular energetics and allosteric AMPK activation, AMPfret. Based on engineered AMPK fused to fluorescent proteins, the sensor allows direct, real-time readout of the AMPK conformational state by fluorescence resonance energy transfer (FRET). AMPfret faithfully and dynamically reports the binding of AMP and ADP to AMPK γ-CBS sites, competed by Mg2+-free ATP. FRET signals correlate with activation of AMPK by allosteric mechanisms and protection from dephosphorylation, attributed here to specific CBS sites, but does not require activation loop phosphorylation. Moreover, AMPfret detects binding of pharmacological compounds to the AMPK α/β-ADaM site enabling activator screening. Cellular assays demonstrate that AMPfret is applicable in vivo for spatiotemporal analysis of energy state and allosteric AMPK activation. AMP-activated protein kinase AMPK senses and regulates cellular energy state. Here the authors engineer a synthetic sensor, AMPfret, that allows direct, real-time readout of the AMPK conformational state by fluorescence resonance energy transfer (FRET).
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23
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Yan Y, Zhou XE, Novick SJ, Shaw SJ, Li Y, Brunzelle JS, Hitoshi Y, Griffin PR, Xu HE, Melcher K. Structures of AMP-activated protein kinase bound to novel pharmacological activators in phosphorylated, non-phosphorylated, and nucleotide-free states. J Biol Chem 2018; 294:953-967. [PMID: 30478170 DOI: 10.1074/jbc.ra118.004883] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 11/01/2018] [Indexed: 12/12/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an attractive therapeutic target for managing metabolic diseases. A class of pharmacological activators, including Merck 991, binds the AMPK ADaM site, which forms the interaction surface between the kinase domain (KD) of the α-subunit and the carbohydrate-binding module (CBM) of the β-subunit. Here, we report the development of two new 991-derivative compounds, R734 and R739, which potently activate AMPK in a variety of cell types, including β2-specific skeletal muscle cells. Surprisingly, we found that they have only minor effects on direct kinase activity of the recombinant α1β2γ1 isoform yet robustly enhance protection against activation loop dephosphorylation. This mode of activation is reminiscent of that of ADP, which activates AMPK by binding to the nucleotide-binding sites in the γ-subunit, more than 60 Å away from the ADaM site. To understand the mechanisms of full and partial AMPK activation, we determined the crystal structures of fully active phosphorylated AMPK α1β1γ1 bound to AMP and R734/R739 as well as partially active nonphosphorylated AMPK bound to R734 and AMP and phosphorylated AMPK bound to R734 in the absence of added nucleotides at <3-Å resolution. These structures and associated analyses identified a novel conformational state of the AMPK autoinhibitory domain associated with partial kinase activity and provide new insights into phosphorylation-dependent activation loop stabilization in AMPK.
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Affiliation(s)
- Yan Yan
- From the Center of Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan 49503.,Van Andel Research Institute-Shanghai Institute of Materia Medica (VARI-SIMM) Center, Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China
| | - X Edward Zhou
- From the Center of Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Scott J Novick
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458
| | - Simon J Shaw
- Rigel Pharmaceuticals, Inc., South San Francisco, California 94080, and
| | - Yingwu Li
- Rigel Pharmaceuticals, Inc., South San Francisco, California 94080, and
| | - Joseph S Brunzelle
- Northwestern University Synchrotron Research Center, Life Sciences Collaborative Access Team, Northwestern University, Argonne, Illinois 60439
| | - Yasumichi Hitoshi
- Rigel Pharmaceuticals, Inc., South San Francisco, California 94080, and
| | - Patrick R Griffin
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458
| | - H Eric Xu
- From the Center of Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan 49503.,Van Andel Research Institute-Shanghai Institute of Materia Medica (VARI-SIMM) Center, Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Karsten Melcher
- From the Center of Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan 49503,
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24
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Yan Y, Zhou XE, Xu HE, Melcher K. Structure and Physiological Regulation of AMPK. Int J Mol Sci 2018; 19:ijms19113534. [PMID: 30423971 PMCID: PMC6274893 DOI: 10.3390/ijms19113534] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/05/2018] [Accepted: 11/06/2018] [Indexed: 01/26/2023] Open
Abstract
Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a heterotrimeric αβγ complex that functions as a central regulator of energy homeostasis. Energy stress manifests as a drop in the ratio of adenosine triphosphate (ATP) to AMP/ADP, which activates AMPK’s kinase activity, allowing it to upregulate ATP-generating catabolic pathways and to reduce energy-consuming catabolic pathways and cellular programs. AMPK senses the cellular energy state by competitive binding of the three adenine nucleotides AMP, ADP, and ATP to three sites in its γ subunit, each, which in turn modulates the activity of AMPK’s kinase domain in its α subunit. Our current understanding of adenine nucleotide binding and the mechanisms by which differential adenine nucleotide occupancies activate or inhibit AMPK activity has been largely informed by crystal structures of AMPK in different activity states. Here we provide an overview of AMPK structures, and how these structures, in combination with biochemical, biophysical, and mutational analyses provide insights into the mechanisms of adenine nucleotide binding and AMPK activity modulation.
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Affiliation(s)
- Yan Yan
- Center for Cancer and Cell Biology, Van Andel Research Institute, 333 Bostwick Ave. N.E., Grand Rapids, MI 49503, USA.
- VARI/SIMM Center, Center for Structure and Function of Drug Targets, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - X Edward Zhou
- Center for Cancer and Cell Biology, Van Andel Research Institute, 333 Bostwick Ave. N.E., Grand Rapids, MI 49503, USA.
| | - H Eric Xu
- Center for Cancer and Cell Biology, Van Andel Research Institute, 333 Bostwick Ave. N.E., Grand Rapids, MI 49503, USA.
- VARI/SIMM Center, Center for Structure and Function of Drug Targets, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Karsten Melcher
- Center for Cancer and Cell Biology, Van Andel Research Institute, 333 Bostwick Ave. N.E., Grand Rapids, MI 49503, USA.
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25
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Abstract
Mammalian AMPK is known to be activated by falling cellular energy status, signaled by rising AMP/ATP and ADP/ATP ratios. We review recent information about how this occurs but also discuss new studies suggesting that AMPK is able to sense glucose availability independently of changes in adenine nucleotides. The glycolytic intermediate fructose-1,6-bisphosphate (FBP) is sensed by aldolase, which binds to the v-ATPase on the lysosomal surface. In the absence of FBP, interactions between aldolase and the v-ATPase are altered, allowing formation of an AXIN-based AMPK-activation complex containing the v-ATPase, Ragulator, AXIN, LKB1, and AMPK, causing increased Thr172 phosphorylation and AMPK activation. This nutrient-sensing mechanism activates AMPK but also primes it for further activation if cellular energy status subsequently falls. Glucose sensing at the lysosome, in which AMPK and other components of the activation complex act antagonistically with another key nutrient sensor, mTORC1, may have been one of the ancestral roles of AMPK.
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Affiliation(s)
- Sheng-Cai Lin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an Campus, Xiamen, Fujian 361102, China.
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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26
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Olivier S, Foretz M, Viollet B. Promise and challenges for direct small molecule AMPK activators. Biochem Pharmacol 2018; 153:147-158. [PMID: 29408352 DOI: 10.1016/j.bcp.2018.01.049] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/31/2018] [Indexed: 12/11/2022]
Abstract
AMP-activated protein kinase (AMPK) is an evolutionary conserved and ubiquitously expressed serine/threonine kinase playing a central role in the coordination of energy homeostasis. Based on the beneficial outcomes of its activation on metabolism, AMPK has emerged as an attractive target for the treatment of metabolic diseases. Identification of novel downstream targets of AMPK beyond the regulation of energy metabolism has renewed considerable attention in exploiting AMPK signaling for novel therapeutic targeting strategies including treatment of cancer and inflammatory diseases. The complexity of AMPK system with tissue- and species-specific expression of multiple isoform combination regulated by various inputs, post-traductional modifications and subcellular locations presents unique challenges for drug discovery. Here, we review the most recent advances in the understanding of the mechanism(s) of action of direct small molecule AMPK activators and the potential therapeutic opportunities.
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Affiliation(s)
- Séverine Olivier
- INSERM, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, France
| | - Marc Foretz
- INSERM, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, France
| | - Benoit Viollet
- INSERM, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, France.
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27
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Mofidifar S, Sohraby F, Bagheri M, Aryapour H. Repurposing existing drugs for new AMPK activators as a strategy to extend lifespan: a computer-aided drug discovery study. Biogerontology 2018; 19:133-143. [DOI: 10.1007/s10522-018-9744-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/04/2018] [Indexed: 11/28/2022]
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28
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Abstract
AMPK is a highly conserved master regulator of metabolism, which restores energy balance during metabolic stress both at the cellular and physiological levels. The identification of numerous AMPK targets has helped explain how AMPK restores energy homeostasis. Recent advancements illustrate novel mechanisms of AMPK regulation, including changes in subcellular localization and phosphorylation by non-canonical upstream kinases. Notably, the therapeutic potential of AMPK is widely recognized and heavily pursued for treatment of metabolic diseases such as diabetes, but also obesity, inflammation, and cancer. Moreover, the recently solved crystal structure of AMPK has shed light both into how nucleotides activate AMPK and, importantly, also into the sites bound by small molecule activators, thus providing a path for improved drugs.
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Affiliation(s)
- Daniel Garcia
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Reuben J Shaw
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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29
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Phosphorylation of AMPK by upstream kinases is required for activity in mammalian cells. Biochem J 2017; 474:3059-3073. [PMID: 28694351 PMCID: PMC5565919 DOI: 10.1042/bcj20170458] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 06/29/2017] [Accepted: 07/10/2017] [Indexed: 01/01/2023]
Abstract
AMP-activated protein kinase (AMPK) plays a major role in regulating metabolism and has attracted significant attention as a therapeutic target for treating metabolic disorders. AMPK activity is stimulated more than 100-fold by phosphorylation of threonine 172 (Thr172). Binding of AMP to the γ subunit allosterically activates the kinase. Additionally, many small molecules, e.g. 991, have been identified that bind between the kinase domain and the carbohydrate-binding module of the β subunit, stabilising their interaction and leading to activation. It was reported recently that non-phosphorylated Thr172 AMPK is activated by AMP and A769662. We present here the crystal structure of non-phosphorylated Thr172 AMPK in complex with AMP and 991. This structure reveals that the activation loop, as well as the complex overall, is similar to the Thr172 phosphorylated complex. We find that in the presence of AMP and 991 non-phosphorylated Thr172, AMPK is much less active than the Thr172 phosphorylated enzyme. In human cells, the basal level of Thr172 phosphorylation is very low (∼1%), but is increased 10-fold by treatment with 2-deoxyglucose. In cells lacking the major Thr172 kinases, LKB1 and CaMKKβ, Thr172 phosphorylation is almost completely abolished, and AMPK activity is virtually undetectable. Our data show that AMP and 991 binding to non-phosphorylated Thr172 AMPK can induce an ordered, active-like, conformation of the activation loop explaining how AMPK activity can be measured in vitro without Thr172 phosphorylation. However, in a cellular context, phosphorylation of Thr172 is critical for significant activation of AMPK.
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30
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Molecular mechanisms of appetite and obesity: a role for brain AMPK. Clin Sci (Lond) 2017; 130:1697-709. [PMID: 27555613 DOI: 10.1042/cs20160048] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 07/07/2016] [Indexed: 01/15/2023]
Abstract
Feeding behaviour and energy storage are both crucial aspects of survival. Thus, it is of fundamental importance to understand the molecular mechanisms regulating these basic processes. The AMP-activated protein kinase (AMPK) has been revealed as one of the key molecules modulating energy homoeostasis. Indeed, AMPK appears to be essential for translating nutritional and energy requirements into generation of an adequate neuronal response, particularly in two areas of the brain, the hypothalamus and the hindbrain. Failure of this physiological response can lead to energy imbalance, ultimately with extreme consequences, such as leanness or obesity. Here, we will review the data that put brain AMPK in the spotlight as a regulator of appetite.
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31
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Subversion of Host Responses to Energy Insufficiency by Us3 Supports Herpes Simplex Virus 1 Replication during Stress. J Virol 2017; 91:JVI.00295-17. [PMID: 28468873 DOI: 10.1128/jvi.00295-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/24/2017] [Indexed: 12/11/2022] Open
Abstract
Cellular stress responses to energy insufficiency can impact virus reproduction. In particular, activation of the host AMP-activated protein kinase (AMPK) by low energy could limit protein synthesis by inhibiting mTORC1. Although many herpesviruses, including herpes simplex virus 1 (HSV-1), stimulate mTORC1, how HSV-1-infected cells respond to energy availability, a physiological indicator regulating mTORC1, has not been investigated. In addition, the impact of low-energy stress on productive HSV-1 growth and viral genetic determinants potentially enabling replication under physiological stress remains undefined. Here, we demonstrate that mTORC1 activity in HSV-1-infected cells is largely insensitive to stress induced by simulated energy insufficiency. Furthermore, resistance of mTORC1 activity to low-energy-induced stress, while not significantly influenced by the HSV-1 UL46-encoded phosphatidylinositol 3-kinase (PI3K)-Akt activator, was dependent upon the Ser/Thr kinase activity of Us3. A Us3-deficient virus was hypersensitive to low-energy-induced stress as infected cell protein synthesis and productive replication were reduced compared to levels in cells infected with a Us3-expressing virus. Although Us3 did not detectably prevent energy stress-induced AMPK activation, it enforced mTORC1 activation despite the presence of activated AMPK. In the absence of applied low-energy stress, AMPK activity in infected cells was restricted in a Us3-dependent manner. This establishes that the Us3 kinase not only activated mTORC1 but also enabled sustained mTORC1 signaling during simulated energy insufficiency that would otherwise restrict protein synthesis and virus replication. Moreover, it identifies the alphaherpesvirus-specific Us3 kinase as an mTORC1 activator that subverts the host cell energy-sensing program to support viral productive growth irrespective of physiological stress.IMPORTANCE Like all viruses, herpes simplex virus type 1 (HSV-1) reproduction relies upon numerous host energy-intensive processes, the most demanding of which is protein synthesis. In response to low energy, the cellular AMP-activated protein kinase (AMPK) triggers a physiological stress response that antagonizes mTORC1, a multisubunit host kinase that controls protein synthesis. This could restrict virus protein production and growth. Here, we establish that the HSV-1 Us3 protein kinase subverts the normal response to low-energy-induced stress. While Us3 does not prevent AMPK activation by low energy, it enforces mTORC1 activation and overrides a physiological response that couples energy availability and protein synthesis. These results help explain how reproduction of HSV-1, a ubiquitous, medically significant human pathogen causing a spectrum of diseases ranging from the benign to the life threatening, occurs during physiological stress. This is important because HSV-1 reproduction triggered by physiological stress is characteristic of reactivation of lifelong latent infections.
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32
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Abstract
AMP-activated protein kinase is a family of heterotrimeric serine/threonine protein kinases that come in twelve different flavors. They serve an essential function in all eukaryotes of conserving cellular energy levels. AMPK complexes are regulated by changes in cellular AMP:ATP or ADP:ATP ratios and by a number of neutraceuticals and some of the widely-used diabetes medications such as metformin and thiazolinonediones. Moreover, biochemical activities of AMPK are tightly regulated by phosphorylation or dephosphorylation by upstream kinases and phosphatases respectively. Efforts are underway in many pharmaceutical companies to discover direct AMPK activators for the treatment of cardiovascular and metabolic diseases such as diabetes, non-alcoholic steatohepatitis (NASH) and diabetic nephropathy. Many advances have been made in the AMPK structural biology arena over the last few years that are beginning to provide detailed molecular insights into the overall topology of these fascinating enzymes and how binding of small molecules elicit subtle conformational changes leading to their activation and protection from dephosphorylation. In the brief review below on AMPK structure and function, we have focused on the recent crystallographic results especially on specific molecular interactions of direct synthetic AMPK activators which lead to biased activation of a sub-family of AMPK isoforms.
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Affiliation(s)
- Ravi G Kurumbail
- Pfizer Worldwide Research and Development, Pfizer Inc, Eastern Point Road, Groton, CT, 06340, USA.
| | - Matthew F Calabrese
- Pfizer Worldwide Research and Development, Pfizer Inc, Eastern Point Road, Groton, CT, 06340, USA
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33
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Ahalawat N, Murarka RK. Molecular Mechanism of Nucleotide-Dependent Allosteric Regulation in AMP-Activated Protein Kinase. J Phys Chem B 2017; 121:2919-2930. [PMID: 28345916 DOI: 10.1021/acs.jpcb.6b11223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The AMP-activated protein kinase (AMPK), a central enzyme in the regulation of energy homeostasis, is an important drug target for type 2 diabetes, obesity, and cancer. Binding of adenosine nucleotides to the regulatory γ-subunit tightly regulates the activity of this enzyme. Though recent crystal structures of AMPK have provided important insights into the allosteric activation of AMPK, molecular details of the regulatory mechanism of AMPK activation is still elusive. Here, we have performed extensive all-atom molecular dynamics (MD) simulations and shown that the kinase domain (KD) and γ-subunit come closer resulting in a more compact heterotrimeric AMPK complex in AMP-bound state compared to the ATP-bound state. The binding of ATP at site 3 of regulatory γ-subunit allosterically inhibits AMPK by destabilizing different regulatory regions of α-subunit: the autoinhibitory domain, the linker region, and the activation loop of the kinase core. The catalytically important residues experience a change in mechanical stress, and major rearrangements in community structure derived from residue-residue interaction energy-based network are observed in KD and α-linker region upon binding of different nucleotides. Our results also highlight the role of conserved charged residues forming an ionic network near the site 3 of γ-subunit in allosteric communications.
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Affiliation(s)
- Navjeet Ahalawat
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal , Bhopal By-pass Road, Bhauri, Bhopal 462 066, MP, India
| | - Rajesh K Murarka
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal , Bhopal By-pass Road, Bhauri, Bhopal 462 066, MP, India
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34
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Carling D. AMPK signalling in health and disease. Curr Opin Cell Biol 2017; 45:31-37. [PMID: 28232179 DOI: 10.1016/j.ceb.2017.01.005] [Citation(s) in RCA: 480] [Impact Index Per Article: 68.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 01/23/2017] [Indexed: 12/22/2022]
Abstract
In eukaryotic cells AMP-activated protein kinase (AMPK) plays a major role in regulating cellular energy balance. AMPK responds to changes in intracellular adenine nucleotide levels, being activated by an increase in AMP/ADP relative to ATP. Activation of AMPK increases the rate of catabolic (ATP-generating) pathways and decreases the rate of anabolic (ATP-utilising) pathways. In addition to its role in maintaining intracellular energy balance, AMPK regulates whole body energy metabolism. Given its key role in controlling energy homeostasis, AMPK has attracted widespread interest as a potential therapeutic target for metabolic diseases, including type 2 diabetes and, more recently, cancer. Here I review the regulation of AMPK and its potential as a target for therapeutic intervention in human disease.
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Affiliation(s)
- David Carling
- MRC London Institute of Medical Sciences, Hammersmith Hospital, Imperial College, London W12 0NN UK.
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35
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Li J, Li S, Wang F, Xin F. Structural and biochemical insights into the allosteric activation mechanism of AMP-activated protein kinase. Chem Biol Drug Des 2016; 89:663-669. [PMID: 27809416 DOI: 10.1111/cbdd.12897] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/11/2016] [Accepted: 10/23/2016] [Indexed: 12/12/2022]
Abstract
The AMP-activated protein kinase (AMPK), a complicated αβγ heterotrimer, can sense cellular energy status and maintain energy homeostasis via switching catabolic and anabolic pathways. AMPK also participates in the regulation of many other life activities, including the cell cycle, cell polarity, autophagy, and life span. Therefore, AMPK is widely studied as a potential drug target for treatment of type 2 diabetes and some other metabolic diseases, cancers, and cardiovascular diseases. Similar to other kinases, the phosphorylation of α-Thr172 in the activation loop by upstream kinases is crucial for the activation of AMPK. In addition, the binding of AMP and its analogues to the γ subunit causes further allosteric activation, which makes AMPK distinctive from other kinases. Here, we give a brief introduction to the domain constitutions of mammalian AMPK and then systematically review its allosteric activation mechanism from a structural and biochemical view.
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Affiliation(s)
- Jin Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Shuying Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Fengzhong Wang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Fengjiao Xin
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
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36
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Broeckx T, Hulsmans S, Rolland F. The plant energy sensor: evolutionary conservation and divergence of SnRK1 structure, regulation, and function. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:6215-6252. [PMID: 27856705 DOI: 10.1093/jxb/erw416] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The SnRK1 (SNF1-related kinase 1) kinases are the plant cellular fuel gauges, activated in response to energy-depleting stress conditions to maintain energy homeostasis while also gatekeeping important developmental transitions for optimal growth and survival. Similar to their opisthokont counterparts (animal AMP-activated kinase, AMPK, and yeast Sucrose Non-Fermenting 1, SNF), they function as heterotrimeric complexes with a catalytic (kinase) α subunit and regulatory β and γ subunits. Although the overall configuration of the kinase complexes is well conserved, plant-specific structural modifications (including a unique hybrid βγ subunit) and associated differences in regulation reflect evolutionary divergence in response to fundamentally different lifestyles. While AMP is the key metabolic signal activating AMPK in animals, the plant kinases appear to be allosterically inhibited by sugar-phosphates. Their function is further fine-tuned by differential subunit expression, localization, and diverse post-translational modifications. The SnRK1 kinases act by direct phosphorylation of key metabolic enzymes and regulatory proteins, extensive transcriptional regulation (e.g. through bZIP transcription factors), and down-regulation of TOR (target of rapamycin) kinase signaling. Significant progress has been made in recent years. New tools and more directed approaches will help answer important fundamental questions regarding their structure, regulation, and function, as well as explore their potential as targets for selection and modification for improved plant performance in a changing environment.
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Affiliation(s)
- Tom Broeckx
- Laboratory for Molecular Plant Biology, Biology Department, University of Leuven-KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee-Leuven, Belgium
| | - Sander Hulsmans
- Laboratory for Molecular Plant Biology, Biology Department, University of Leuven-KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee-Leuven, Belgium
| | - Filip Rolland
- Laboratory for Molecular Plant Biology, Biology Department, University of Leuven-KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee-Leuven, Belgium
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37
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Ross FA, MacKintosh C, Hardie DG. AMP-activated protein kinase: a cellular energy sensor that comes in 12 flavours. FEBS J 2016; 283:2987-3001. [PMID: 26934201 PMCID: PMC4995730 DOI: 10.1111/febs.13698] [Citation(s) in RCA: 254] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/10/2016] [Accepted: 02/29/2016] [Indexed: 12/11/2022]
Abstract
The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is expressed in essentially all eukaryotic cells, suggesting that it arose during early eukaryotic evolution. It occurs universally as heterotrimeric complexes containing catalytic α subunits and regulatory β and γ subunits. Although Drosophila melanogaster contains single genes encoding each subunit, in mammals, each subunit exists as multiple isoforms encoded by distinct genes, giving rise to up to 12 heterotrimeric combinations. The multiple isoforms of each subunit are 2R-ohnologues generated by the two rounds of whole genome duplication that occurred at the evolutionary origin of the vertebrates. Although the differential roles of these isoform combinations remain only partly understood, there are indications that they may have different subcellular locations, different inputs and outputs, and different functions. The multiple isoforms are of particular interest with respect to the roles of AMPK in cancer because the genes encoding some isoforms, such as PRKAA1 and PRKAB2 (encoding α1 and β2), are quite frequently amplified in tumour cells, whereas the genes encoding others, such as PRKAA2 (encoding α2), tend to be mutated, which, in some but not all cases, may result in a loss of function. Thus, although AMPK acts downstream of the tumour suppressor liver kinase B1, and some of its isoform combinations may act as tumour suppressors that restrain the growth and proliferation of tumour cells, other isoform combinations may paradoxically act as oncogenes, perhaps by aiding the survival of tumour cells undergoing environmental stresses such as hypoxia or nutrient deprivation.
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Affiliation(s)
- Fiona A Ross
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Scotland, UK
| | - Carol MacKintosh
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Scotland, UK
| | - D Grahame Hardie
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Scotland, UK
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38
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The yeast Hsp70 homolog Ssb: a chaperone for general de novo protein folding and a nanny for specific intrinsically disordered protein domains. Curr Genet 2016; 63:9-13. [PMID: 27230907 PMCID: PMC5274638 DOI: 10.1007/s00294-016-0610-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 05/06/2016] [Accepted: 05/09/2016] [Indexed: 12/17/2022]
Abstract
Activation of the heterotrimeric kinase SNF1 via phosphorylation of a specific residue within the α subunit is essential for the release from glucose repression in the yeast Saccharomyces cerevisiae. When glucose is available, SNF1 is maintained in the dephosphorylated, inactive state by the phosphatase Glc7-Reg1. Recent findings suggest that Bmh and Ssb combine their unique client-binding properties to interact with the regulatory region of the SNF1 α subunit and by that stabilize a conformation of SNF1, which is accessible for Glc7-Reg1-dependent dephosphorylation. Together, the 14-3-3 protein Bmh and the Hsp70 homolog Ssb comprise a novel chaperone module, which is required to maintain proper glucose repression in the yeast S. cerevisiae.
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39
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Ouyang Y, Zhu L, Li Y, Guo M, Liu Y, Cheng J, Zhao J, Wu Y. Architectural plasticity of AMPK revealed by electron microscopy and X-ray crystallography. Sci Rep 2016; 6:24191. [PMID: 27063142 PMCID: PMC4827068 DOI: 10.1038/srep24191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/22/2016] [Indexed: 12/25/2022] Open
Abstract
Mammalian AMP-activated protein kinase (AMPK) acts as an important sensor of cellular energy homeostasis related with AMP/ADP to ATP ratio. The overall architecture of AMPK has been determined in either homotrimer or monomer form by electron microscopy (EM) and X-ray crystallography successively. Accordingly proposed models have consistently revealed a key role of the α subunit linker in sensing adenosine nucleoside binding on the γ subunit and mediating allosteric regulation of kinase domain (KD) activity, whereas there are vital differences in orienting N-terminus of α subunit and locating carbohydrate-binding module (CBM) of β subunit. Given that Mg2+, an indispensable cofactor of AMPK was present in the EM sample preparation buffer however absent when forming crystals, here we carried out further reconstructions without Mg2+ to expectably inspect if this ion may contribute to this difference. However, no essential alteration has been found in this study compared to our early work. Further analyses indicate that the intra-molecular movement of the KD and CBM are most likely due to the flexible linkage of the disordered linkers with the rest portion as well as a contribution from the plasticity in the inter-molecular assembly mode, which might ulteriorly reveal an architectural complication of AMPK.
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Affiliation(s)
- Yan Ouyang
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Li Zhu
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yifang Li
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Miaomiao Guo
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yang Liu
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jin Cheng
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jing Zhao
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yi Wu
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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Hübscher V, Mudholkar K, Chiabudini M, Fitzke E, Wölfle T, Pfeifer D, Drepper F, Warscheid B, Rospert S. The Hsp70 homolog Ssb and the 14-3-3 protein Bmh1 jointly regulate transcription of glucose repressed genes in Saccharomyces cerevisiae. Nucleic Acids Res 2016; 44:5629-45. [PMID: 27001512 PMCID: PMC4937304 DOI: 10.1093/nar/gkw168] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 03/03/2016] [Indexed: 11/26/2022] Open
Abstract
Chaperones of the Hsp70 family interact with a multitude of newly synthesized polypeptides and prevent their aggregation. Saccharomyces cerevisiae cells lacking the Hsp70 homolog Ssb suffer from pleiotropic defects, among others a defect in glucose-repression. The highly conserved heterotrimeric kinase SNF1/AMPK (AMP-activated protein kinase) is required for the release from glucose-repression in yeast and is a key regulator of energy balance also in mammalian cells. When glucose is available the phosphatase Glc7 keeps SNF1 in its inactive, dephosphorylated state. Dephosphorylation depends on Reg1, which mediates targeting of Glc7 to its substrate SNF1. Here we show that the defect in glucose-repression in the absence of Ssb is due to the ability of the chaperone to bridge between the SNF1 and Glc7 complexes. Ssb performs this post-translational function in concert with the 14-3-3 protein Bmh, to which Ssb binds via its very C-terminus. Raising the intracellular concentration of Ssb or Bmh enabled Glc7 to dephosphorylate SNF1 even in the absence of Reg1. By that Ssb and Bmh efficiently suppressed transcriptional deregulation of Δreg1 cells. The findings reveal that Ssb and Bmh comprise a new chaperone module, which is involved in the fine tuning of a phosphorylation-dependent switch between respiration and fermentation.
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Affiliation(s)
- Volker Hübscher
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Kaivalya Mudholkar
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Marco Chiabudini
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Edith Fitzke
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Tina Wölfle
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Dietmar Pfeifer
- Genomics Lab, Department of Hematology, Oncology and Stem Cell Transplantation, University Medical Center, University of Freiburg, D-79106 Freiburg, Germany
| | - Friedel Drepper
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
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Hardie DG, Schaffer BE, Brunet A. AMPK: An Energy-Sensing Pathway with Multiple Inputs and Outputs. Trends Cell Biol 2016; 26:190-201. [PMID: 26616193 PMCID: PMC5881568 DOI: 10.1016/j.tcb.2015.10.013] [Citation(s) in RCA: 617] [Impact Index Per Article: 77.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/15/2015] [Accepted: 10/22/2015] [Indexed: 12/20/2022]
Abstract
AMP-activated protein kinase (AMPK) is a key regulator of energy balance expressed ubiquitously in eukaryotic cells. Here we review the canonical adenine nucleotide-dependent mechanism that activates AMPK when cellular energy status is compromised, as well as other, noncanonical activation mechanisms. Once activated, AMPK acts to restore energy homeostasis by promoting catabolic pathways, resulting in ATP generation, and inhibiting anabolic pathways that consume ATP. We also review the various hypothesis-driven and unbiased approaches that have been used to identify AMPK substrates and have revealed substrates involved in both metabolic and non-metabolic processes. We particularly focus on methods for identifying the AMPK target recognition motif and how it can be used to predict new substrates.
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Affiliation(s)
- D Grahame Hardie
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
| | - Bethany E Schaffer
- Department of Genetics and the Cancer Biology Program, Stanford University, 300 Pasteur Drive, Stanford, CA, USA
| | - Anne Brunet
- Department of Genetics and the Cancer Biology Program, Stanford University, 300 Pasteur Drive, Stanford, CA, USA
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Grahame Hardie D. Regulation of AMP-activated protein kinase by natural and synthetic activators. Acta Pharm Sin B 2016; 6:1-19. [PMID: 26904394 PMCID: PMC4724661 DOI: 10.1016/j.apsb.2015.06.002] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 05/28/2015] [Indexed: 12/11/2022] Open
Abstract
The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is almost universally expressed in eukaryotic cells. While it appears to have evolved in single-celled eukaryotes to regulate energy balance in a cell-autonomous manner, during the evolution of multicellular animals its role has become adapted so that it also regulates energy balance at the whole body level, by responding to hormones that act primarily on the hypothalamus. AMPK monitors energy balance at the cellular level by sensing the ratios of AMP/ATP and ADP/ATP, and recent structural analyses of the AMPK heterotrimer that have provided insight into the complex mechanisms for these effects will be discussed. Given the central importance of energy balance in diseases that are major causes of morbidity or death in humans, such as type 2 diabetes, cancer and inflammatory disorders, there has been a major drive to develop pharmacological activators of AMPK. Many such activators have been described, and the various mechanisms by which these activate AMPK will be discussed. A particularly large class of AMPK activators are natural products of plants derived from traditional herbal medicines. While the mechanism by which most of these activate AMPK has not yet been addressed, I will argue that many of them may be defensive compounds produced by plants to deter infection by pathogens or grazing by insects or herbivores, and that many of them will turn out to be inhibitors of mitochondrial function.
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Affiliation(s)
- David Grahame Hardie
- Division of Cell Signaling & Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
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43
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Structural insight into the mechanism of synergistic autoinhibition of SAD kinases. Nat Commun 2015; 6:8953. [PMID: 26626945 PMCID: PMC4686854 DOI: 10.1038/ncomms9953] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 10/20/2015] [Indexed: 11/10/2022] Open
Abstract
The SAD/BRSK kinases participate in various important life processes, including neural development, cell cycle and energy metabolism. Like other members of the AMPK family, SAD contains an N-terminal kinase domain followed by the characteristic UBA and KA1 domains. Here we identify a unique autoinhibitory sequence (AIS) in SAD kinases, which exerts autoregulation in cooperation with UBA. Structural studies of mouse SAD-A revealed that UBA binds to the kinase domain in a distinct mode and, more importantly, AIS nestles specifically into the KD-UBA junction. The cooperative action of AIS and UBA results in an ‘αC-out' inactive kinase, which is conserved across species and essential for presynaptic vesicle clustering in C. elegans. In addition, the AIS, along with the KA1 domain, is indispensable for phospholipid binding. Taken together, these data suggest a model for synergistic autoinhibition and membrane activation of SAD kinases. The SAD kinases contain a UBA domain that binds to the kinase domain and has a role in autoinhibition and allosteric activation of the AMPK homoenzyme. Here, the authors identify an autoinhibitory sequence in SAD and show that the UBA domain synergistically functions as an autoinhibitory domain.
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44
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Ha J, Guan KL, Kim J. AMPK and autophagy in glucose/glycogen metabolism. Mol Aspects Med 2015; 46:46-62. [PMID: 26297963 DOI: 10.1016/j.mam.2015.08.002] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/04/2015] [Indexed: 12/14/2022]
Abstract
Glucose/glycogen metabolism is a primary metabolic pathway acting on a variety of cellular needs, such as proliferation, growth, and survival against stresses. The multiple regulatory mechanisms underlying a specific metabolic fate have been documented and explained the molecular basis of various pathophysiological conditions, including metabolic disorders and cancers. AMP-activated protein kinase (AMPK) has been appreciated for many years as a central metabolic regulator to inhibit energy-consuming pathways as well as to activate the compensating energy-producing programs. In fact, glucose starvation is a potent physiological AMPK activating condition, in which AMPK triggers various subsequent metabolic events depending on cells or tissues. Of note, the recent studies show bidirectional interplay between AMPK and glycogen. A growing number of studies have proposed additional level of metabolic regulation by a lysosome-dependent catabolic program, autophagy. Autophagy is a critical degradative pathway not only for maintenance of cellular homeostasis to remove potentially dangerous constituents, such as protein aggregates and dysfunctional subcellular organelles, but also for adaptive responses to metabolic stress, such as nutrient starvation. Importantly, many lines of evidence indicate that autophagy is closely connected with nutrient signaling modules, including AMPK, to fine-tune the metabolic pathways in response to many different cellular cues. In this review, we introduce the studies demonstrating the role of AMPK and autophagy in glucose/glycogen metabolism. Also, we describe the recent advances on their contributions to the metabolic disorders.
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Affiliation(s)
- Joohun Ha
- Department of Biochemistry and Molecular Biology, Medical Research Center and Biomedical Science Institute, School of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Kun-Liang Guan
- Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Joungmok Kim
- Department of Oral Biochemistry and Molecular Biology, Research Center for Tooth and Periodontal Tissue Regeneration, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
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45
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Hardie DG. AMPK: positive and negative regulation, and its role in whole-body energy homeostasis. Curr Opin Cell Biol 2015; 33:1-7. [PMID: 25259783 DOI: 10.1016/j.ceb.2014.09.004] [Citation(s) in RCA: 338] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/08/2014] [Indexed: 12/24/2022]
Abstract
The AMP-activated protein kinase (AMPK) is a sensor of energy status that, when activated by metabolic stress, maintains cellular energy homeostasis by switching on catabolic pathways and switching off ATP-consuming processes. Recent results suggest that activation of AMPK by the upstream kinase LKB1 in response to nutrient lack occurs at the surface of the lysosome. AMPK is also crucial in regulation of whole body energy balance, particularly by mediating effects of hormones acting on the hypothalamus. Recent crystal structures of complete AMPK heterotrimers have illuminated its complex mechanisms of activation, involving both allosteric activation and increased net phosphorylation mediated by effects on phosphorylation and dephosphorylation. Finally, AMPK is negatively regulated by phosphorylation of the 'ST loop' within the catalytic subunit.
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Affiliation(s)
- D Grahame Hardie
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, UK.
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46
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Kim J, Shin J, Ha J. Screening methods for AMP-activated protein kinase modulators: a patent review. Expert Opin Ther Pat 2014; 25:261-77. [PMID: 25535089 DOI: 10.1517/13543776.2014.995626] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION AMP-activated protein kinase (AMPK) functions as a cellular energy gauge that maintains cellular homeostasis and has been suggested to play important roles in tumorigenesis, lifespan and autophagy. Accordingly, AMPK is a potential target of drugs for controlling a growing number of human diseases ranging from metabolic disorders to cancer, highlighting the need for rational and robust screening systems for identifying compounds that modulate AMPK. AREAS COVERED The relevant screening methods in the patent and scientific literature were analyzed, and key features of direct AMPK modulators are discussed in the context of their physiological relevance and the three-dimensional structure of the AMPK complex. EXPERT OPINION The mechanism of action of modulators is important in designing drugs with enhanced efficacy, specificity and stability. Most patented assay formats for identifying AMPK modulators are based on classical enzyme assays that monitor AMPK activity or changes in AMPK-dependent cellular physiology. However, these systems do not provide information about underlying mechanisms. Two patented assay systems use a specific domain or the three-dimensional structure of AMPK to identify AMPK modulators. The recent identification of two AMPK modulators, A-769662 and C-2 (or its prodrug, C-13), suggests the promise of structure-based assays in discovering more potent and specific modulators of AMPK.
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Affiliation(s)
- Joungmok Kim
- Kyung Hee University, School of Dentistry, Oral Biochemistry and Molecular Biology , Seoul , Republic of Korea
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47
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Abstract
The AMP-activated protein kinase (AMPK) is a sensor of cellular energy and nutrient status, expressed almost universally in eukaryotes as heterotrimeric complexes comprising catalytic (α) and regulatory (β and γ) subunits. Along with the mechanistic target of rapamycin complex-1 (mTORC1), AMPK may have been one of the earliest signaling pathways to have arisen during eukaryotic evolution. Recent crystal structures have provided insights into the mechanisms by which AMPK is regulated by phosphorylation and allosteric activators. Another recent development has been the realization that activation of AMPK by the upstream kinase LKB1 may primarily occur not in the cytoplasm, but at the surface of the lysosome, where AMPK and mTORC1 are regulated in a reciprocal manner by the availability of nutrients. It is also becoming clear that there is a substantial amount of crosstalk between the AMPK pathway and other signaling pathways that promote cell growth and proliferation, and this will be discussed.
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Affiliation(s)
- D Grahame Hardie
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH Scotland, UK.
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48
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Krishan S, Richardson DR, Sahni S. Adenosine Monophosphate–Activated Kinase and Its Key Role in Catabolism: Structure, Regulation, Biological Activity, and Pharmacological Activation. Mol Pharmacol 2014; 87:363-77. [DOI: 10.1124/mol.114.095810] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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49
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Li X, Wang L, Zhou XE, Ke J, de Waal PW, Gu X, Tan MHE, Wang D, Wu D, Xu HE, Melcher K. Structural basis of AMPK regulation by adenine nucleotides and glycogen. Cell Res 2014; 25:50-66. [PMID: 25412657 PMCID: PMC4650587 DOI: 10.1038/cr.2014.150] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 09/02/2014] [Accepted: 09/19/2014] [Indexed: 12/19/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a central cellular energy sensor and regulator of energy homeostasis, and a promising drug target for the treatment of diabetes, obesity, and cancer. Here we present low-resolution crystal structures of the human α1β2γ1 holo-AMPK complex bound to its allosteric modulators AMP and the glycogen-mimic cyclodextrin, both in the phosphorylated (4.05 Å) and non-phosphorylated (4.60 Å) state. In addition, we have solved a 2.95 Å structure of the human kinase domain (KD) bound to the adjacent autoinhibitory domain (AID) and have performed extensive biochemical and mutational studies. Together, these studies illustrate an underlying mechanism of allosteric AMPK modulation by AMP and glycogen, whose binding changes the equilibria between alternate AID (AMP) and carbohydrate-binding module (glycogen) interactions.
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Affiliation(s)
- Xiaodan Li
- 1] Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510530, China [2] School of Life Science, University of Science and Technology of China, Hefei, Anhui 230027, China [3] Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
| | - Lili Wang
- 1] Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510530, China [2] School of Life Science, University of Science and Technology of China, Hefei, Anhui 230027, China [3] Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
| | - X Edward Zhou
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
| | - Jiyuan Ke
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
| | - Parker W de Waal
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
| | - Xin Gu
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
| | - M H Eileen Tan
- 1] Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA [2] Department of Obstetrics & Gynecology, National University Hospital, Yong Loo Lin School of Medicine, National University of Singapore, 119074, Singapore
| | - Dongye Wang
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510530, China
| | - Donghai Wu
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510530, China
| | - H Eric Xu
- 1] Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA [2] VARI/SIMM Center, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Karsten Melcher
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave, NE, Grand Rapids, MI 49503, USA
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Hunter RW, Foretz M, Bultot L, Fullerton MD, Deak M, Ross FA, Hawley SA, Shpiro N, Viollet B, Barron D, Kemp BE, Steinberg GR, Hardie DG, Sakamoto K. Mechanism of action of compound-13: an α1-selective small molecule activator of AMPK. CHEMISTRY & BIOLOGY 2014; 21:866-79. [PMID: 25036776 PMCID: PMC4104029 DOI: 10.1016/j.chembiol.2014.05.014] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/09/2014] [Accepted: 05/30/2014] [Indexed: 12/20/2022]
Abstract
AMPK is a sensor of cellular energy status and a promising target for drugs aimed at metabolic disorders. We have studied the selectivity and mechanism of a recently described activator, C2, and its cell-permeable prodrug, C13. C2 was a potent allosteric activator of α1-complexes that, like AMP, also protected against Thr172 dephosphorylation. Compared with AMP, C2 caused only partial allosteric activation of α2-complexes and failed to protect them against dephosphorylation. We show that both effects could be fully restored by exchanging part of the linker between the autoinhibitory and C-terminal domains in α2, containing the equivalent region from α1 thought to interact with AMP bound in site 3 of the γ subunit. Consistent with our results in cell-free assays, C13 potently inhibited lipid synthesis in hepatocytes from wild-type and was largely ineffective in AMPK-knockout hepatocytes; its effects were more severely affected by knockout of α1 than of α2, β1, or β2.
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Affiliation(s)
- Roger W Hunter
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH Scotland, UK; Nestlé Institute of Health Sciences SA, EPFL Innovation Park, bâtiment G, 1015 Lausanne, Switzerland
| | - Marc Foretz
- Inserm, U1016, Institut Cochin, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris cité, 75006 Paris, France
| | - Laurent Bultot
- Nestlé Institute of Health Sciences SA, EPFL Innovation Park, bâtiment G, 1015 Lausanne, Switzerland
| | - Morgan D Fullerton
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main West Street, Hamilton ON L8N 3Z5, Canada
| | - Maria Deak
- Nestlé Institute of Health Sciences SA, EPFL Innovation Park, bâtiment G, 1015 Lausanne, Switzerland
| | - Fiona A Ross
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Simon A Hawley
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Natalia Shpiro
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH Scotland, UK
| | - Benoit Viollet
- Inserm, U1016, Institut Cochin, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France; CNRS, UMR8104, Paris, France; Université Paris Descartes, Sorbonne Paris cité, 75006 Paris, France
| | - Denis Barron
- Nestlé Institute of Health Sciences SA, EPFL Innovation Park, bâtiment G, 1015 Lausanne, Switzerland
| | - Bruce E Kemp
- Protein Chemistry and Metabolism, St. Vincent's Institute and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy VIC 3065, Australia
| | - Gregory R Steinberg
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main West Street, Hamilton ON L8N 3Z5, Canada
| | - D Grahame Hardie
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Kei Sakamoto
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH Scotland, UK; Nestlé Institute of Health Sciences SA, EPFL Innovation Park, bâtiment G, 1015 Lausanne, Switzerland.
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