1
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Trelford CB, Shepherd TG. LKB1 biology: assessing the therapeutic relevancy of LKB1 inhibitors. Cell Commun Signal 2024; 22:310. [PMID: 38844908 PMCID: PMC11155146 DOI: 10.1186/s12964-024-01689-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 05/28/2024] [Indexed: 06/10/2024] Open
Abstract
Liver Kinase B1 (LKB1), encoded by Serine-Threonine Kinase 11 (STK11), is a master kinase that regulates cell migration, polarity, proliferation, and metabolism through downstream adenosine monophosphate-activated protein kinase (AMPK) and AMPK-related kinase signalling. Since genetic screens identified STK11 mutations in Peutz-Jeghers Syndrome, STK11 mutants have been implicated in tumourigenesis labelling it as a tumour suppressor. In support of this, several compounds reduce tumour burden through upregulating LKB1 signalling, and LKB1-AMPK agonists are cytotoxic to tumour cells. However, in certain contexts, its role in cancer is paradoxical as LKB1 promotes tumour cell survival by mediating resistance against metabolic and oxidative stressors. LKB1 deficiency has also enhanced the selectivity and cytotoxicity of several cancer therapies. Taken together, there is a need to develop LKB1-specific pharmacological compounds, but prior to developing LKB1 inhibitors, further work is needed to understand LKB1 activity and regulation. However, investigating LKB1 activity is strenuous as cell/tissue type, mutations to the LKB1 signalling pathway, STE-20-related kinase adaptor protein (STRAD) binding, Mouse protein 25-STRAD binding, splicing variants, nucleocytoplasmic shuttling, post-translational modifications, and kinase conformation impact the functional status of LKB1. For these reasons, guidelines to standardize experimental strategies to study LKB1 activity, associate proteins, spliced isoforms, post-translational modifications, and regulation are of upmost importance to the development of LKB1-specific therapies. Therefore, to assess the therapeutic relevancy of LKB1 inhibitors, this review summarizes the importance of LKB1 in cell physiology, highlights contributors to LKB1 activation, and outlines the benefits and risks associated with targeting LKB1.
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Affiliation(s)
- Charles B Trelford
- The Mary &, John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer Program, 790 Commissioners Road East, Room A4‑921, London, ON, N6A 4L6, Canada.
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
| | - Trevor G Shepherd
- The Mary &, John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer Program, 790 Commissioners Road East, Room A4‑921, London, ON, N6A 4L6, Canada
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Oncology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Obstetrics and Gynaecology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
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2
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Jiang D, Yang C, Gu W, Ma X, Tong Z, Wang L, Song L. PyLKB1 regulates glucose transport via activating PyAMPKα in Yesso Scallop Patinopecten yessoensis under high temperature stress. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 153:105128. [PMID: 38163473 DOI: 10.1016/j.dci.2023.105128] [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: 12/06/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 01/03/2024]
Abstract
Liver kinase B1 (LKB1) is a classical serine/threonine protein kinase and plays an important role in maintaining energy homeostasis through phosphorylate AMP-activated protein kinase α subunit (AMPKα). In this study, a homologous molecule of LKB1 with a typical serine/threonine kinase domain and two nuclear localization sequences (NLSs) was identified in Yesso Scallop Patinopecten yessoensis (PyLKB1). The mRNA transcripts of PyLKB1 were found to be expressed in haemocytes and all the examined tissues, including gill, mantle, gonad, adductor muscle and hepatopancreas, with the highest expression level in hepatopancreas. PyLKB1 was mainly located in cytoplasm and nucleus of scallop haemocytes. At 3 h after high temperature stress treatment (25 °C), the mRNA transcripts of PyLKB1, PyAMPKα, and PyGLUT1 in hepatopancreas, the phosphorylation level of PyAMPKα at Thr170 in hepatopancreas, the positive fluorescence signals of PyLKB1 in haemocytes, glucose analogue 2-NBDG content in haemocytes, and glucose content in hepatopancreas, haemocytes and serum all increased significantly (p < 0.05) compared to blank group (15 °C). However, there was no significant difference at the protein level of PyLKB1 and PyAMPKα. After PyLKB1 was knockdown by siRNA, the mRNA expression level of PyGLUT1, and the glucose content in hepatopancreas and serum were significantly down-regulated (p < 0.05) compared with the negative control group receiving an injection of siRNA-NC. However, there were no significant difference in PyGLUT1 expression, glucose content and glucose analogue 2-NBDG content in haemocytes. These results collectively suggested that PyLKB1-PyAMPKα pathway was activated to promote glucose transport by regulating PyGLUT1 in response to high temperature stress. These results would be helpful for understanding the function of PyLKB1-PyAMPKα pathway in regulating glucose metabolism and maintaining energy homeostasis under high temperature stress in scallops.
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Affiliation(s)
- Dongli Jiang
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China
| | - Chuanyan Yang
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China.
| | - Wenfei Gu
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China
| | - Xiaoxue Ma
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China
| | - Ziling Tong
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China
| | - Lingling Wang
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China.
| | - Linsheng Song
- Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519000, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean, China
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3
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Kim CL, Lim SB, Choi SH, Kim DH, Sim YE, Jo EH, Kim K, Lee K, Park HS, Lim SB, Kang LJ, Jeong HS, Lee Y, Hansen CG, Mo JS. The LKB1-TSSK1B axis controls YAP phosphorylation to regulate the Hippo-YAP pathway. Cell Death Dis 2024; 15:76. [PMID: 38245531 PMCID: PMC10799855 DOI: 10.1038/s41419-024-06465-4] [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: 07/31/2023] [Revised: 01/05/2024] [Accepted: 01/10/2024] [Indexed: 01/22/2024]
Abstract
The Hippo pathway's main effector, Yes-associated protein (YAP), plays a crucial role in tumorigenesis as a transcriptional coactivator. YAP's phosphorylation by core upstream components of the Hippo pathway, such as mammalian Ste20 kinase 1/2 (MST1/2), mitogen-activated protein kinase kinase kinase kinases (MAP4Ks), and their substrate, large tumor suppressor 1/2 (LATS1/2), influences YAP's subcellular localization, stability, and transcriptional activity. However, recent research suggests the existence of alternative pathways that phosphorylate YAP, independent of these core upstream Hippo pathway components, raising questions about additional means to inactivate YAP. In this study, we present evidence demonstrating that TSSK1B, a calcium/calmodulin-dependent protein kinase (CAMK) superfamily member, is a negative regulator of YAP, suppressing cellular proliferation and oncogenic transformation. Mechanistically, TSSK1B inhibits YAP through two distinct pathways. Firstly, the LKB1-TSSK1B axis directly phosphorylates YAP at Ser94, inhibiting the YAP-TEAD complex's formation and suppressing its target genes' expression. Secondly, the TSSK1B-LATS1/2 axis inhibits YAP via phosphorylation at Ser127. Our findings reveal the involvement of TSSK1B-mediated molecular mechanisms in the Hippo-YAP pathway, emphasizing the importance of multilevel regulation in critical cellular decision-making processes.
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Affiliation(s)
- Cho-Long Kim
- Department of Biomedical Sciences, Graduate School, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Su-Bin Lim
- Department of Biomedical Sciences, Graduate School, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Sue-Hee Choi
- Department of Biomedical Sciences, Graduate School, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Dong Hyun Kim
- Department of Biomedical Sciences, Graduate School, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Ye Eun Sim
- Department of Biomedical Sciences, Graduate School, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Eun-Hye Jo
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, South Korea
| | - Keeeun Kim
- Institute of Medical Science, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Keesook Lee
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, South Korea
| | - Hee-Sae Park
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, South Korea
| | - Su Bin Lim
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Li-Jung Kang
- Three-Dimensional Immune System Imaging Core Facility, Ajou University, Suwon, 16499, South Korea
| | - Han-Sol Jeong
- Division of Applied Medicine, School of Korean Medicine, Pusan National University, Yangsan, 50612, South Korea
| | - Youngsoo Lee
- Institute of Medical Science, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Carsten G Hansen
- The University of Edinburgh, Institute for Regeneration and Repair, Centre for Inflammation Research, Edinburgh BioQuarter, Edinburgh, UK
| | - Jung-Soon Mo
- Department of Biomedical Sciences, Graduate School, Ajou University School of Medicine, Suwon, 16499, South Korea.
- Institute of Medical Science, Ajou University School of Medicine, Suwon, 16499, South Korea.
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Tompkins E, Mimic B, Penn RB, Pera T. The biased M3 mAChR ligand PD 102807 mediates qualitatively distinct signaling to regulate airway smooth muscle phenotype. J Biol Chem 2023; 299:105209. [PMID: 37660916 PMCID: PMC10520882 DOI: 10.1016/j.jbc.2023.105209] [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: 01/12/2023] [Revised: 08/14/2023] [Accepted: 08/22/2023] [Indexed: 09/05/2023] Open
Abstract
Airway smooth muscle (ASM) cells attain a hypercontractile phenotype during obstructive airway diseases. We recently identified a biased M3 muscarinic acetylcholine receptor (mAChR) ligand, PD 102807, that induces GRK-/arrestin-dependent AMP-activated protein kinase (AMPK) activation to inhibit transforming growth factor-β-induced hypercontractile ASM phenotype. Conversely, the balanced mAChR agonist, methacholine (MCh), activates AMPK yet does not regulate ASM phenotype. In the current study, we demonstrate that PD 102807- and MCh-induced AMPK activation both depend on Ca2+/calmodulin-dependent kinase kinases (CaMKKs). However, MCh-induced AMPK activation is calcium-dependent and mediated by CaMKK1 and CaMKK2 isoforms. In contrast, PD 102807-induced signaling is calcium-independent and mediated by the atypical subtype protein kinase C-iota and the CaMKK1 (but not CaMKK2) isoform. Both MCh- and PD 102807-induced AMPK activation involve the AMPK α1 isoform. PD 102807-induced AMPK α1 (but not AMPK α2) isoform activation mediates inhibition of the mammalian target of rapamycin complex 1 (mTORC1) in ASM cells, as demonstrated by increased Raptor (regulatory-associated protein of mTOR) phosphorylation as well as inhibition of phospho-S6 protein and serum response element-luciferase activity. The mTORC1 inhibitor rapamycin and the AMPK activator metformin both mimic the ability of PD 102807 to attenuate transforming growth factor-β-induced α-smooth muscle actin expression (a marker of hypercontractile ASM). These data indicate that PD 102807 transduces a signaling pathway (AMPK-mediated mTORC1 inhibition) qualitatively distinct from canonical M3 mAChR signaling to prevent pathogenic remodeling of ASM, thus demonstrating PD 102807 is a biased M3 mAChR ligand with therapeutic potential for the management of obstructive airway disease.
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Affiliation(s)
- Eric Tompkins
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA
| | - Bogdana Mimic
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA
| | - Raymond B Penn
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA
| | - Tonio Pera
- Department of Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Philadelphia, Pennsylvania, USA.
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5
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Hu L, Liu M, Tang B, Li Q, Pan BS, Xu C, Lin HK. Posttranslational regulation of liver kinase B1 (LKB1) in human cancer. J Biol Chem 2023; 299:104570. [PMID: 36870679 PMCID: PMC10068580 DOI: 10.1016/j.jbc.2023.104570] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/06/2023] Open
Abstract
Liver kinase B1 (LKB1) is a serine-threonine kinase that participates in multiple cellular and biological processes, including energy metabolism, cell polarity, cell proliferation, cell migration, and many others. LKB1 is initially identified as a germline-mutated causative gene in Peutz-Jeghers syndrome (PJS) and is commonly regarded as a tumor suppressor due to frequent inactivation in a variety of cancers. LKB1 directly binds and activates its downstream kinases including the AMP-activated protein kinase (AMPK) and AMPK-related kinases by phosphorylation, which has been intensively investigated for the past decades. An increasing number of studies has uncovered the posttranslational modifications (PTMs) of LKB1 and consequent changes in its localization, activity, and interaction with substrates. The alteration in LKB1 function as a consequence of genetic mutations and aberrant upstream signaling regulation leads to tumor development and progression. Here, we review current knowledge about the mechanism of LKB1 in cancer and the contributions of PTMs, such as phosphorylation, ubiquitination, SUMOylation, acetylation, prenylation, and others, to the regulation of LKB1 function, offering new insights into the therapeutic strategies in cancer.
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Affiliation(s)
- Lanlin Hu
- Department of Oncology & Cancer Institute, Sichuan Academy of Medical Sciences, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Department of Laboratory Medicine and Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Mingxin Liu
- Department of Oncology & Cancer Institute, Sichuan Academy of Medical Sciences, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Bo Tang
- Department of Oncology & Cancer Institute, Sichuan Academy of Medical Sciences, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Department of Laboratory Medicine and Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Qiang Li
- Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Bo-Syong Pan
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Chuan Xu
- Department of Oncology & Cancer Institute, Sichuan Academy of Medical Sciences, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Department of Laboratory Medicine and Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China; Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.
| | - Hui-Kuan Lin
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.
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6
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Spatial regulation of AMPK signaling revealed by a sensitive kinase activity reporter. Nat Commun 2022; 13:3856. [PMID: 35790710 PMCID: PMC9256702 DOI: 10.1038/s41467-022-31190-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 06/06/2022] [Indexed: 12/13/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics which coordinates metabolism by phosphorylating a plethora of substrates throughout the cell. But how AMPK activity is regulated at different subcellular locations for precise spatiotemporal control over metabolism is unclear. Here we present a sensitive, single-fluorophore AMPK activity reporter (ExRai AMPKAR), which reveals distinct kinetic profiles of AMPK activity at the mitochondria, lysosome, and cytoplasm. Genetic deletion of the canonical upstream kinase liver kinase B1 (LKB1) results in slower AMPK activity at lysosomes but does not affect the response amplitude at lysosomes or mitochondria, in sharp contrast to the necessity of LKB1 for maximal cytoplasmic AMPK activity. We further identify a mechanism for AMPK activity in the nucleus, which results from cytoplasmic to nuclear shuttling of AMPK. Thus, ExRai AMPKAR enables illumination of the complex subcellular regulation of AMPK signaling.
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7
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Tu-Sekine B, Kim SF. The Inositol Phosphate System-A Coordinator of Metabolic Adaptability. Int J Mol Sci 2022; 23:6747. [PMID: 35743190 PMCID: PMC9223660 DOI: 10.3390/ijms23126747] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 06/10/2022] [Accepted: 06/13/2022] [Indexed: 11/16/2022] Open
Abstract
All cells rely on nutrients to supply energy and carbon building blocks to support cellular processes. Over time, eukaryotes have developed increasingly complex systems to integrate information about available nutrients with the internal state of energy stores to activate the necessary processes to meet the immediate and ongoing needs of the cell. One such system is the network of soluble and membrane-associated inositol phosphates that coordinate the cellular responses to nutrient uptake and utilization from growth factor signaling to energy homeostasis. In this review, we discuss the coordinated interactions of the inositol polyphosphates, inositol pyrophosphates, and phosphoinositides in major metabolic signaling pathways to illustrate the central importance of the inositol phosphate signaling network in nutrient responses.
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Affiliation(s)
- Becky Tu-Sekine
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Johns Hopkins University, Baltimore, MD 21224, USA;
| | - Sangwon F. Kim
- Department of Medicine and Neuroscience, Division of Endocrinology, Diabetes and Metabolism, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA
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Brody AH, Nies SH, Guan F, Smith LM, Mukherjee B, Salazar SA, Lee S, Lam TKT, Strittmatter SM. Alzheimer risk gene product Pyk2 suppresses tau phosphorylation and phenotypic effects of tauopathy. Mol Neurodegener 2022; 17:32. [PMID: 35501917 PMCID: PMC9063299 DOI: 10.1186/s13024-022-00526-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 03/02/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic variation at the PTK2B locus encoding the protein Pyk2 influences Alzheimer's disease risk. Neurons express Pyk2 and the protein is required for Amyloid-β (Aβ) peptide driven deficits of synaptic function and memory in mouse models, but Pyk2 deletion has minimal effect on neuro-inflammation. Previous in vitro data suggested that Pyk2 activity might enhance GSK3β-dependent Tau phosphorylation and be required for tauopathy. Here, we examine the influence of Pyk2 on Tau phosphorylation and associated pathology. METHODS The effect of Pyk2 on Tau phosphorylation was examined in cultured Hek cells through protein over-expression and in iPSC-derived human neurons through pharmacological Pyk2 inhibition. PS19 mice overexpressing the P301S mutant of human Tau were employed as an in vivo model of tauopathy. Phenotypes of PS19 mice with a targeted deletion of Pyk2 expression were compared with PS19 mice with intact Pyk2 expression. Phenotypes examined included Tau phosphorylation, Tau accumulation, synapse loss, gliosis, proteomic profiling and behavior. RESULTS Over-expression experiments from Hek293T cells indicated that Pyk2 contributed to Tau phosphorylation, while iPSC-derived human neuronal cultures with endogenous protein levels supported the opposite conclusion. In vivo, multiple phenotypes of PS19 were exacerbated by Pyk2 deletion. In Pyk2-null PS19 mice, Tau phosphorylation and accumulation increased, mouse survival decreased, spatial memory was impaired and hippocampal C1q deposition increased relative to PS19 littermate controls. Proteomic profiles of Pyk2-null mouse brain revealed that several protein kinases known to interact with Tau are regulated by Pyk2. Endogenous Pyk2 suppresses LKB1 and p38 MAPK activity, validating one potential pathway contributing to increased Tau pathology. CONCLUSIONS The absence of Pyk2 results in greater mutant Tau-dependent phenotypes in PS19 mice, in part via increased LKB1 and MAPK activity. These data suggest that in AD, while Pyk2 activity mediates Aβ-driven deficits, Pyk2 suppresses Tau-related phenotypes.
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Affiliation(s)
- A Harrison Brody
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Sarah Helena Nies
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA.,Graduate School of Cellular and Molecular Neuroscience, University of Tübingen, D-72074, Tübingen, Germany
| | - Fulin Guan
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Levi M Smith
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Bandhan Mukherjee
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Santiago A Salazar
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Suho Lee
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Tu Kiet T Lam
- Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, CT, USA.,Keck MS & Proteomics Resource, Yale School of Medicine, New Haven, CT, USA
| | - Stephen M Strittmatter
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neuroscience, Yale School of Medicine, New Haven, CT, USA.
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Yue Y, Hua Y, Zhang J, Guo Y, Zhao D, Huo W, Xiong Y, Chen F, Lin Y, Xiong X, Li J. Establishment of a subcutaneous adipogenesis model and distinct roles of LKB1 regulation on adipocyte lipid accumulation in high-altitude Bos grunniens. JOURNAL OF APPLIED ANIMAL RESEARCH 2022. [DOI: 10.1080/09712119.2022.2042001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Yongqi Yue
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Yonglin Hua
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Jing Zhang
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Yu Guo
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Dan Zhao
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Wentao Huo
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Yan Xiong
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- Key Laboratory of Animal Science of National Ethnic Affairs Commission of China, Southwest Minzu University, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Fenfen Chen
- School of Life Sciences, Southwest Forestry University, Kunming, People’s Republic of China
| | - Yaqiu Lin
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- Key Laboratory of Animal Science of National Ethnic Affairs Commission of China, Southwest Minzu University, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Xianrong Xiong
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- Key Laboratory of Animal Science of National Ethnic Affairs Commission of China, Southwest Minzu University, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Jian Li
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, People’s Republic of China
- Key Laboratory of Animal Science of National Ethnic Affairs Commission of China, Southwest Minzu University, Chengdu, People’s Republic of China
- College of Animal &Veterinary Sciences, Southwest Minzu University, Chengdu, People’s Republic of China
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10
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Folliculin haploinsufficiency causes cellular dysfunction of pleural mesothelial cells. Sci Rep 2021; 11:10814. [PMID: 34031471 PMCID: PMC8144428 DOI: 10.1038/s41598-021-90184-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 05/07/2021] [Indexed: 11/10/2022] Open
Abstract
Birt–Hogg–Dubé syndrome (BHDS), an autosomal dominant inheritance disease caused by folliculin (FLCN) mutations, is associated with lung cysts and spontaneous pneumothorax. The possibility of FLCN haploinsufficiency in pleural mesothelial cells (PMCs) contributing to development of pneumothorax has not yet been clarified. Electron microscopy revealed exposed intercellular boundaries between PMCs on visceral pleura and decreased electron density around the adherens junctions in BHDS. To characterize cellular function of PMCs in BHDS patients (BHDS-PMCs), during surgery for pneumothorax, we established the flow cytometry-based methods of isolating high-purity PMCs from pleural lavage fluid. BHDS-PMCs showed impaired cell attachment and a significant decrease in proliferation and migration, but a significant increase in apoptosis compared with PMCs from primary spontaneous pneumothorax (PSP) patients (PSP-PMCs). Microarray analysis using isolated PMCs revealed a significant alteration in the expression of genes belonging to Gene Ontology terms “cell–cell adhesion junction” and “cell adhesion molecule binding”. Gene set enrichment analysis demonstrated that CDH1, encoding E-cadherin, was identified in the down-regulated leading edge of a plot in BHDS-PMCs. AMPK and LKB1 activation were significantly impaired in BHDS-PMCs compared with PSP-PMCs. Our findings indicate that FLCN haploinsufficiency may affect the E-cadherin-LKB1-AMPK axis and lead to abnormal cellular function in BHDS-PMCs.
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11
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Minini M, Senni A, Unfer V, Bizzarri M. The Key Role of IP 6K: A Novel Target for Anticancer Treatments? Molecules 2020; 25:molecules25194401. [PMID: 32992691 PMCID: PMC7583815 DOI: 10.3390/molecules25194401] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/29/2022] Open
Abstract
Inositol and its phosphate metabolites play a pivotal role in several biochemical pathways and gene expression regulation: inositol pyrophosphates (PP-IPs) have been increasingly appreciated as key signaling modulators. Fluctuations in their intracellular levels hugely impact the transfer of phosphates and the phosphorylation status of several target proteins. Pharmacological modulation of the proteins associated with PP-IP activities has proved to be beneficial in various pathological settings. IP7 has been extensively studied and found to play a key role in pathways associated with PP-IP activities. Three inositol hexakisphosphate kinase (IP6K) isoforms regulate IP7 synthesis in mammals. Genomic deletion or enzymic inhibition of IP6K1 has been shown to reduce cell invasiveness and migration capacity, protecting against chemical-induced carcinogenesis. IP6K1 could therefore be a useful target in anticancer treatment. Here, we summarize the current understanding that established IP6K1 and the other IP6K isoforms as possible targets for cancer therapy. However, it will be necessary to determine whether pharmacological inhibition of IP6K is safe enough to begin clinical study. The development of safe and selective inhibitors of IP6K isoforms is required to minimize undesirable effects.
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Affiliation(s)
- Mirko Minini
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Department of Surgery ‘P. Valdoni’, Sapienza University of Rome, 00161 Rome, Italy
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.B.)
| | - Alice Senni
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Department of Surgery ‘P. Valdoni’, Sapienza University of Rome, 00161 Rome, Italy
| | - Vittorio Unfer
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
| | - Mariano Bizzarri
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.B.)
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12
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Mossenta M, Busato D, Dal Bo M, Toffoli G. Glucose Metabolism and Oxidative Stress in Hepatocellular Carcinoma: Role and Possible Implications in Novel Therapeutic Strategies. Cancers (Basel) 2020; 12:E1668. [PMID: 32585931 PMCID: PMC7352479 DOI: 10.3390/cancers12061668] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/12/2020] [Accepted: 06/20/2020] [Indexed: 12/13/2022] Open
Abstract
Hepatocellular carcinoma (HCC) metabolism is redirected to glycolysis to enhance the production of metabolic compounds employed by cancer cells to produce proteins, lipids, and nucleotides in order to maintain a high proliferative rate. This mechanism drives towards uncontrolled growth and causes a further increase in reactive oxygen species (ROS), which could lead to cell death. HCC overcomes the problem generated by ROS increase by increasing the antioxidant machinery, in which key mechanisms involve glutathione, nuclear factor erythroid 2-related factor 2 (Nrf2), and hypoxia-inducible transcription factor (HIF-1α). These mechanisms could represent optimal targets for innovative therapies. The tumor microenvironment (TME) exerts a key role in HCC pathogenesis and progression. Various metabolic machineries modulate the activity of immune cells in the TME. The deregulated metabolic activity of tumor cells could impair antitumor response. Lactic acid-lactate, derived from the anaerobic glycolytic rate of tumor cells, as well as adenosine, derived from the catabolism of ATP, have an immunosuppressive activity. Metabolic reprogramming of the TME via targeted therapies could enhance the treatment efficacy of anti-cancer immunotherapy. This review describes the metabolic pathways mainly involved in the HCC pathogenesis and progression. The potential targets for HCC treatment involved in these pathways are also discussed.
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Affiliation(s)
- Monica Mossenta
- Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico di Aviano (CRO), IRCCS, 33081 Aviano (PN), Italy; (M.M.); (D.B.); (G.T.)
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
| | - Davide Busato
- Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico di Aviano (CRO), IRCCS, 33081 Aviano (PN), Italy; (M.M.); (D.B.); (G.T.)
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
| | - Michele Dal Bo
- Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico di Aviano (CRO), IRCCS, 33081 Aviano (PN), Italy; (M.M.); (D.B.); (G.T.)
| | - Giuseppe Toffoli
- Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico di Aviano (CRO), IRCCS, 33081 Aviano (PN), Italy; (M.M.); (D.B.); (G.T.)
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13
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Thirugnanam K, Ramchandran R. SNRK: a metabolic regulator with multifaceted role in development and disease. VESSEL PLUS 2020; 4:26. [PMID: 32968716 PMCID: PMC7508454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sucrose nonfermenting 1-related kinase (SNRK) is a serine/threonine kinase and a member of the adenosine monophosphate (AMP)-activated protein kinase (AMPK) family that is involved in the metabolic regulatory mechanisms in various cell types. SNRK is an important mediator in maintaining cellular metabolic homeostasis. In this review, we discuss the role of SNRK in metabolic tissues where it is expressed, including heart and adipose tissue. We discuss its role in regulating inflammation in these tissues and the pathways associated with regulating inflammation. We also discuss SNRK's role in vascular development and the processes associated with it. Finally, we review SNRK's potential as a target in various metabolic dysfunction-associated diseases such as cardiovascular diseases, diabetes, obesity, and cancer. This comprehensive review on SNRK suggests that it has therapeutic value in the suppression of inflammation in cardiac and adipose tissue.
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Affiliation(s)
- Karthikeyan Thirugnanam
- Department of Pediatrics, Division of Neonatology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ramani Ramchandran
- Department of Pediatrics, Division of Neonatology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.,Obstetrics and Gynecology, Medical College of Wisconsin, Developmental Vascular Biology Program, Children’s Research Institute, Milwaukee, WI 53226, USA
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14
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Ouyang C, Mu J, Lu Q, Li J, Zhu H, Wang Q, Zou MH, Xie Z. Autophagic degradation of KAT2A/GCN5 promotes directional migration of vascular smooth muscle cells by reducing TUBA/α-tubulin acetylation. Autophagy 2019; 16:1753-1770. [PMID: 31878840 DOI: 10.1080/15548627.2019.1707488] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Macroautophagy/autophagy, a fundamental process for degradation of macromolecules and organelles, occurs constitutively at a basal level and is upregulated in response to stress. Whether autophagy regulates protein acetylation and microtubule stability in vascular smooth muscle cells (VSMCs) migration, however, remains unknown. Here, we demonstrate that the histone acetyltransferase KAT2A/GCN5 (lysine acetyltransferase 2) binds directly to the autophagosome protein MAP1LC3/LC3 (microtubule associated protein 1 light chain 3) via a conserved LC3-interacting region (LIR) domain. This interaction is required for KAT2A sequestration in autophagosomes and degradation by lysosomal acid hydrolases. Suppression of autophagy results in KAT2A accumulation. KAT2A functions as an acetyltransferase to increase TUBA/α-tubulin acetylation, promote microtubule polymerization and stability, ultimately inhibiting directional cell migration. Our findings indicate that deacetylation of TUBA and perturbation of microtubule stability via selective autophagic degradation of KAT2A are essential for autophagy-promoting VSMC migration. Abbreviations: ACTB: actin beta; ATAT1: alpha tubulin acetyltransferase 1; ATG: autophagy-related; BECN1: beclin 1; CQ: chloroquine; FBS: fetal bovine serum; GST: glutathione S-transferase; H4K16ac: histone H4 lysine 16 acetylation; HASMCs: human aortic smooth muscle cells; HBSS: Hank's buffered salt solution; HDAC6: histone deacetylase 6; hMOF: human males absent on the first; IP: immunoprecipitation; KAT2A/GCN5: lysine acetyltransferase 2A; Lacta: lactacystin; LIR: LC3-interaction region; MAP1LC3: microtubule associated protein 1 light chain 3; MEFs: mouse embryonic fibroblasts; MTOC: microtubule-organizing center; PE: phosphatidylethanolamine; PtdIns3K: class III phosphatidylinositol 3-kinase; RUNX2: runt-related transcription factor 2; SIRT1: sirtuin 1; SIRT2: sirtuin 2; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1; VSMCs: vascular smooth muscle cells; WT: wild-type.
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Affiliation(s)
- Changhan Ouyang
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Jing Mu
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Qiulun Lu
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Jian Li
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Huaiping Zhu
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Qilong Wang
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Ming-Hui Zou
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
| | - Zhonglin Xie
- Center of Molecular and Translational Medicine, Georgia State University , Atlanta, GA, USA
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15
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Kari S, Vasko VV, Priya S, Kirschner LS. PKA Activates AMPK Through LKB1 Signaling in Follicular Thyroid Cancer. Front Endocrinol (Lausanne) 2019; 10:769. [PMID: 31798532 PMCID: PMC6874117 DOI: 10.3389/fendo.2019.00769] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 10/23/2019] [Indexed: 01/08/2023] Open
Abstract
Thyroid cancer affects about one percent of the population, and has seen rising incidence in recent years. Follicular thyroid cancer (FTC) comprises 10-15% of all thyroid cancers. Although FTC is often localized, it can behave aggressively with hematogenous metastasis, leading to an increased risk of cancer death. We previously described a mouse model for FTC caused by tissue-specific ablation of the Protein Kinase A (PKA) regulatory subunit Prkar1a, either by itself or in combination with knockout of Pten. Loss of Prkar1a causes enhanced activity of PKA, whereas ablation of Pten causes activation of Akt signaling. At the molecular level, these genetic manipulations caused activation of mTOR signaling, which was also observed in human FTC cases. To understand the mechanism by which PKA activates mTOR, we began by studying intracellular kinases known to modulate mTOR function. Although AMP-activated kinase (AMPK) has been characterized as a negative regulator of mTOR activity, our tumor model exhibited activation of both AMPK and mTOR. To understand the mechanism by which AMPK was turned on, we next studied kinases known to cause its phosphorylation. In this paper, we report that PKA leads to AMPK activation through the LKB1 kinase. Although LKB1 has traditionally been considered a tumor suppressor, our data indicates that it may have a complex role in the thyroid gland, where its activation appears to be frequently associated with follicular thyroid carcinoma in both mice and humans.
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Affiliation(s)
- Suresh Kari
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
| | - Vasyl V. Vasko
- Uniformed Services University of Health Sciences, Bethesda, MD, United States
| | - Shivam Priya
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
| | - Lawrence S. Kirschner
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
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16
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Wang F, Yang X, Lu Y, Li Z, Xu Y, Hu J, Liu J, Xiong W. The natural product antroalbol H promotes phosphorylation of liver kinase B1 (LKB1) at threonine 189 and thereby enhances cellular glucose uptake. J Biol Chem 2019; 294:10415-10427. [PMID: 31113861 DOI: 10.1074/jbc.ra118.007231] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/29/2019] [Indexed: 01/01/2023] Open
Abstract
Hypoglycemic drugs such as metformin increase glucose uptake and utilization by peripheral tissues to maintain glucose homeostasis, and the AMP-activated protein kinase (AMPK) signaling pathway is an important component of this pharmacological activity. Liver kinase B1 (LKB1) acts as a kinase upstream of AMPK and plays an important regulatory role in glucose metabolism. In recent years, as a tumor suppressor, LKB1's antitumor activity has been widely studied, yet its hypoglycemic activity is not clear. Here, using biochemical and cell viability assays, site-directed mutagenesis, immunoblotting, and immunofluorescence staining, we found that a natural product, antroalbol H isolated from the basidiomycete mushroom Antrodiella albocinnamomea, increases cellular glucose uptake in murine L6 myotubes and 3T3-L1 adipocytes. Of note, our results indicated that this effect is related to LKB1-mediated Thr-172 phosphorylation of AMPKα. Furthermore, we observed that antroalbol H induces the phosphorylation of LKB1 specifically at Thr-189 and changes subcellular localization of LKB1. Finally, antroalbol H treatment strikingly promoted glucose transporter type 4 (GLUT4) translocation to the plasma membrane. We conclude that antroalbol H promotes Thr-189 phosphorylation of LKB1, leading to AMPK activation, revealing this residue as a potential target for increasing glucose uptake, and that antroalbol H therefore has potential for managing hyperglycemia.
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Affiliation(s)
- Fang Wang
- From the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.,the University of the Chinese Academy of Sciences, Beijing 100049, China, and
| | - Xiaoyan Yang
- From the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.,the Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming 650201, China
| | - Yanting Lu
- From the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.,the University of the Chinese Academy of Sciences, Beijing 100049, China, and
| | - Zhenghui Li
- the School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Yuhui Xu
- From the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Jing Hu
- From the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Jikai Liu
- the School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China,
| | - Wenyong Xiong
- From the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, .,the General Hospital of Ningxia Medical University, Yinchuan 750004, China
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17
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Yang F, Qin Y, Wang Y, Meng S, Xian H, Che H, Lv J, Li Y, Yu Y, Bai Y, Wang L. Metformin Inhibits the NLRP3 Inflammasome via AMPK/mTOR-dependent Effects in Diabetic Cardiomyopathy. Int J Biol Sci 2019; 15:1010-1019. [PMID: 31182921 PMCID: PMC6535781 DOI: 10.7150/ijbs.29680] [Citation(s) in RCA: 281] [Impact Index Per Article: 56.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 01/15/2019] [Indexed: 12/22/2022] Open
Abstract
Metformin is a widely used antidiabetic drug for type 2 diabetes that can play a cardioprotective role through multiple pathways. It is a recognized agonist of AMP-activated protein kinase (AMPK) that blocks mitochondrial complex I. The NLRP3 inflammasome has been demonstrated to be activated in diabetic cardiomyopathy (DCM). However, the role of metformin in regulating the NLRP3 signaling pathway in DCM remains unclear. It has been reported that AMPK can inhibit NLRP3 by activating autophagy. The aim of this study was to investigate whether metformin can inhibit the NLRP3 inflammasome by activating the AMPK/mTOR pathway in DCM. In this study, streptozotocin-induced C57BL/6 mice and high glucose-treated primary cardiomyocytes from neonatal mice were treated with metformin or an AMPK inhibitor compound C. Echocardiography, hematoxylin-eosin and Masson staining showed that the function and morphology of the diabetic hearts were improved after metformin treatment, whereas these parameters deteriorated after intervention with an AMPK inhibitor. Immunohistochemical staining, immunofluorescence staining and western blot assays indicated that the expression levels of mTOR, NLRP3, caspase-1, IL-1β and GSDMD-N were decreased in the diabetic model treated with metformin and were reversed after the administration of an AMPK inhibitor in vivo and in vitro. Mechanistically, our results demonstrated that metformin can activate AMPK, thus improving autophagy via inhibiting the mTOR pathway and alleviating pyroptosis in DCM. Thus, we provide novel information for the treatment of DCM.
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Affiliation(s)
- Fan Yang
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Ying Qin
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Yueqiu Wang
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Songyan Meng
- Department of Geriatrics, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Huimin Xian
- Department of Cardiology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hui Che
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Jie Lv
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yang Li
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yahan Yu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Yunlong Bai
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Lihong Wang
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
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18
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Ferretti AC, Hidalgo F, Tonucci FM, Almada E, Pariani A, Larocca MC, Favre C. Metformin and glucose starvation decrease the migratory ability of hepatocellular carcinoma cells: targeting AMPK activation to control migration. Sci Rep 2019; 9:2815. [PMID: 30809021 PMCID: PMC6391381 DOI: 10.1038/s41598-019-39556-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 01/17/2019] [Indexed: 12/22/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a highly metastatic cancer with very poor prognosis. AMP activated kinase (AMPK) constitutes a candidate to inhibit HCC progression. First, AMPK is downregulated in HCC. Second, glucose starvation induces apoptosis in HCC cells via AMPK. Correspondingly, metformin activates AMPK and inhibits HCC cell proliferation. Nevertheless, the effect of AMPK activation on HCC cell invasiveness remains elusive. Here, migration/invasion was studied in HCC cells exposed to metformin and glucose starvation. Cell viability, proliferation and differentiation, as well as AMPK and PKA activation were analyzed. In addition, invasiveness in mutants of the AMPKα activation loop was assessed. Metformin decreased cell migration, invasion and epithelial-mesenchymal transition, and interference with AMPKα expression avoided metformin actions. Those antitumor effects were potentiated by glucose deprivation. Metformin activated AMPK at the same time that inhibited PKA, and both effects were enhanced by glucose starvation. Given that AMPKα(S173) phosphorylation by PKA decreases AMPK activation, we hypothesized that the reduction of PKA inhibitory effect by metformin could explain the increased antitumor effects observed. Supporting this, in AMPK activating conditions, cell migration/invasion was further impaired in AMPKα(S173C) mutant cells. Metformin emerges as a strong inhibitor of migration/invasion in HCC cells, and glucose restriction potentiates this effect.
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Affiliation(s)
- Anabela C Ferretti
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina
| | - Florencia Hidalgo
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina
| | - Facundo M Tonucci
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina
| | - Evangelina Almada
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina
| | - Alejandro Pariani
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina
| | - María C Larocca
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina
| | - Cristián Favre
- Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina.
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Martin-Hidalgo D, Hurtado de Llera A, Calle-Guisado V, Gonzalez-Fernandez L, Garcia-Marin L, Bragado MJ. AMPK Function in Mammalian Spermatozoa. Int J Mol Sci 2018; 19:ijms19113293. [PMID: 30360525 PMCID: PMC6275045 DOI: 10.3390/ijms19113293] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/16/2018] [Accepted: 10/20/2018] [Indexed: 01/03/2023] Open
Abstract
AMP-activated protein kinase AMPK regulates cellular energy by controlling metabolism through the inhibition of anabolic pathways and the simultaneous stimulation of catabolic pathways. Given its central regulator role in cell metabolism, AMPK activity and its regulation have been the focus of relevant investigations, although only a few studies have focused on the AMPK function in the control of spermatozoa's ability to fertilize. This review summarizes the known cellular roles of AMPK that have been identified in mammalian spermatozoa. The involvement of AMPK activity is described in terms of the main physiological functions of mature spermatozoa, particularly in the regulation of suitable sperm motility adapted to the fluctuating extracellular medium, maintenance of the integrity of sperm membranes, and the mitochondrial membrane potential. In addition, the intracellular signaling pathways leading to AMPK activation in mammalian spermatozoa are reviewed. We also discuss the role of AMPK in assisted reproduction techniques, particularly during semen cryopreservation and preservation (at 17 °C). Finally, we reinforce the idea of AMPK as a key signaling kinase in spermatozoa that acts as an essential linker/bridge between metabolism energy and sperm's ability to fertilize.
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Affiliation(s)
- David Martin-Hidalgo
- Research Group of Intracellular Signaling and Technology of Reproduction (SINTREP), Institute of Biotechnology in Agriculture and Livestock (INBIO G+C), University of Extremadura, 10003 Cáceres, Spain.
- Unit for Multidisciplinary Research in Biomedicine (UMIB), Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, 40050-313 Porto, Portugal.
| | - Ana Hurtado de Llera
- Research Group of Intracellular Signaling and Technology of Reproduction (SINTREP), Institute of Biotechnology in Agriculture and Livestock (INBIO G+C), University of Extremadura, 10003 Cáceres, Spain.
- Hormones and Metabolism Research Group, Faculty of Health Sciences, University of Beira Interior, 6200-506 Covilhã, Portugal.
| | - Violeta Calle-Guisado
- Research Group of Intracellular Signaling and Technology of Reproduction (SINTREP), Institute of Biotechnology in Agriculture and Livestock (INBIO G+C), University of Extremadura, 10003 Cáceres, Spain.
| | - Lauro Gonzalez-Fernandez
- Research Group of Intracellular Signaling and Technology of Reproduction (SINTREP), Institute of Biotechnology in Agriculture and Livestock (INBIO G+C), University of Extremadura, 10003 Cáceres, Spain.
| | - Luis Garcia-Marin
- Research Group of Intracellular Signaling and Technology of Reproduction (SINTREP), Institute of Biotechnology in Agriculture and Livestock (INBIO G+C), University of Extremadura, 10003 Cáceres, Spain.
| | - M Julia Bragado
- Research Group of Intracellular Signaling and Technology of Reproduction (SINTREP), Institute of Biotechnology in Agriculture and Livestock (INBIO G+C), University of Extremadura, 10003 Cáceres, Spain.
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20
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Tan X, Liao Z, Liang H, Chen X, Zhang B, Chu L. Upregulation of liver kinase B1 predicts poor prognosis in hepatocellular carcinoma. Int J Oncol 2018; 53:1913-1926. [PMID: 30226588 PMCID: PMC6192789 DOI: 10.3892/ijo.2018.4556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 08/03/2018] [Indexed: 12/15/2022] Open
Abstract
The majority of studies report that liver kinase B1 (LKB1) acts as a tumor suppressor by inhibiting cell proliferation and metastasis. The present study investigated the expression pattern of LKB1 in 2 cohorts of paired hepatocellular carcinoma (HCC) and analogous non-cancerous tissues (ANT). The results indicated that LKB1 was upregulated in HCC vs. ANT tissues, and that high expression of LKB1 was associated with a higher number of tumor foci, larger tumor size, poorer tumor differentiation, Edmondson-Steiner grade, Barcelona Clinic Liver Cancer grade and tumor-node-metastasis stage. Furthermore, high LKB1 expression was associated with poor overall survival (OS), shorter disease-free survival and early recurrence. Univariate and multivariate analyses demonstrated that high LKB1 expression may serve as an independent prognostic marker for OS, but not for recurrence. In addition, knockdown of LKB1 expression in HCC cell lines inhibited cell proliferation and subcutaneous tumor growth by promoting cell apoptosis. Therefore, the findings of the present study suggest a protooncogenic role of LKB1 in HCC.
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Affiliation(s)
- Xiaolong Tan
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Zhibin Liao
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Huifang Liang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xiaoping Chen
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Bixiang Zhang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Liang Chu
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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21
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Adachi Y, De Sousa-Coelho AL, Harata I, Aoun C, Weimer S, Shi X, Gonzalez Herrera KN, Takahashi H, Doherty C, Noguchi Y, Goodyear LJ, Haigis MC, Gerszten RE, Patti ME. l-Alanine activates hepatic AMP-activated protein kinase and modulates systemic glucose metabolism. Mol Metab 2018; 17:61-70. [PMID: 30190193 PMCID: PMC6197624 DOI: 10.1016/j.molmet.2018.08.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 08/07/2018] [Indexed: 12/11/2022] Open
Abstract
Objective AMP activated protein kinase (AMPK) is recognized as an important nutrient sensor contributing to regulation of cellular, tissue, and systemic metabolism. We aimed to identify specific amino acids which could modulate AMPK and determine effects on cellular and systemic metabolism. Methods We performed an unbiased amino acid screen to identify activators of AMPK. Detailed analysis of cellular signaling and metabolism was performed in cultured hepatoma cells, and in vivo glucose metabolism and metabolomic patterns were assessed in both chow-fed mice and mice made obese by high-fat diet feeding. Results Alanine acutely activates AMP kinase in both cultured hepatic cells and in liver from mice treated in vivo with Ala. Oral alanine administration improves systemic glucose tolerance in both chow and high fat diet fed mice, with reduced efficacy of Ala in mice with reduced AMPK activity. Our data indicate that Ala activation of AMPK is mediated by intracellular Ala metabolism, which reduces TCA cycle metabolites, increases AMP/ATP ratio, and activates NH3 generation. Conclusions Ala may serve as a distinct amino acid energy sensor, providing a positive signal to activate the beneficial AMPK signaling pathway. Unbiased amino acid screen identified alanine as a unique activator of AMP kinase. Alanine acutely activates AMP kinase in both cultured cells and in vivo. Alanine and NH3 metabolism contribute to regulation of AMP kinase activation. Effects of Ala are reduced in absence of AMP kinase. Oral alanine improves glucose tolerance in vivo in both chow and HFD-fed mice.
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Affiliation(s)
- Yusuke Adachi
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA; Institute for Innovation, Ajinomoto Co. Inc., Japan
| | | | - Ikue Harata
- Institute for Innovation, Ajinomoto Co. Inc., Japan
| | - Charlie Aoun
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA
| | - Sandra Weimer
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA
| | - Xu Shi
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Karina N Gonzalez Herrera
- Department of Cell Biology and Paul F. Glenn Laboratories for the Biological Mechanisms of Aging, Harvard Medical School, Boston, MA, USA
| | - Hirokazu Takahashi
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA
| | - Chris Doherty
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA
| | | | - Laurie J Goodyear
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA
| | - Marcia C Haigis
- Department of Cell Biology and Paul F. Glenn Laboratories for the Biological Mechanisms of Aging, Harvard Medical School, Boston, MA, USA
| | - Robert E Gerszten
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Mary-Elizabeth Patti
- Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, MA, USA.
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22
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Hapak SM, Rothlin CV, Ghosh S. PAR3-PAR6-atypical PKC polarity complex proteins in neuronal polarization. Cell Mol Life Sci 2018; 75:2735-2761. [PMID: 29696344 PMCID: PMC11105418 DOI: 10.1007/s00018-018-2828-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/03/2018] [Accepted: 04/23/2018] [Indexed: 01/01/2023]
Abstract
Polarity is a fundamental feature of cells. Protein complexes, including the PAR3-PAR6-aPKC complex, have conserved roles in establishing polarity across a number of eukaryotic cell types. In neurons, polarity is evident as distinct axonal versus dendritic domains. The PAR3, PAR6, and aPKC proteins also play important roles in neuronal polarization. During this process, either aPKC kinase activity, the assembly of the PAR3-PAR6-aPKC complex or the localization of these proteins is regulated downstream of a number of signaling pathways. In turn, the PAR3, PAR6, and aPKC proteins control various effector molecules to establish neuronal polarity. Herein, we discuss the many signaling mechanisms and effector functions that have been linked to PAR3, PAR6, and aPKC during the establishment of neuronal polarity.
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Affiliation(s)
- Sophie M Hapak
- Department of Medicine, School of Medicine, University of Minnesota, 401 East River Parkway, Minneapolis, MN, 55455, USA.
| | - Carla V Rothlin
- Department of Immunobiology, School of Medicine, Yale University, 300 Cedar Street, New Haven, CT, 06520, USA
- Department of Pharmacology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA
| | - Sourav Ghosh
- Department of Neurology, School of Medicine, Yale University, 300 George Street, New Haven, CT, 06511, USA
- Department of Pharmacology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA
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23
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Chakraborty A. The inositol pyrophosphate pathway in health and diseases. Biol Rev Camb Philos Soc 2018; 93:1203-1227. [PMID: 29282838 PMCID: PMC6383672 DOI: 10.1111/brv.12392] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 11/28/2017] [Accepted: 12/05/2017] [Indexed: 12/11/2022]
Abstract
Inositol pyrophosphates (IPPs) are present in organisms ranging from plants, slime moulds and fungi to mammals. Distinct classes of kinases generate different forms of energetic diphosphate-containing IPPs from inositol phosphates (IPs). Conversely, polyphosphate phosphohydrolase enzymes dephosphorylate IPPs to regenerate the respective IPs. IPPs and/or their metabolizing enzymes regulate various cell biological processes by modulating many proteins via diverse mechanisms. In the last decade, extensive research has been conducted in mammalian systems, particularly in knockout mouse models of relevant enzymes. Results obtained from these studies suggest impacts of the IPP pathway on organ development, especially of brain and testis. Conversely, deletion of specific enzymes in the pathway protects mice from various diseases such as diet-induced obesity (DIO), type-2 diabetes (T2D), fatty liver, bacterial infection, thromboembolism, cancer metastasis and aging. Furthermore, pharmacological inhibition of the same class of enzymes in mice validates the therapeutic importance of this pathway in cardio-metabolic diseases. This review critically analyses these findings and summarizes the significance of the IPP pathway in mammalian health and diseases. It also evaluates benefits and risks of targeting this pathway in disease therapies. Finally, future directions of mammalian IPP research are discussed.
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Affiliation(s)
- Anutosh Chakraborty
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, Saint Louis, MO 63104, U.S.A
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24
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Abstract
The tumor suppressor LKB1 is an essential serine/threonine kinase, which regulates various cellular processes such as cell metabolism, cell proliferation, cell polarity, and cell migration. Germline mutations in the STK11 gene (encoding LKB1) are the cause of the Peutz-Jeghers syndrome, which is characterized by benign polyps in the intestine and a higher risk for the patients to develop intestinal and extraintestinal tumors. Moreover, mutations and misregulation of LKB1 have been reported to occur in most types of tumors and are among the most common aberrations in lung cancer. LKB1 activates several downstream kinases of the AMPK family by direct phosphorylation in the T-loop. In particular the activation of AMPK upon energetic stress has been intensively analyzed in various diseases, including cancer to induce a metabolic switch from anabolism towards catabolism to regulate energy homeostasis and cell survival. In contrast, the regulation of LKB1 itself has long been only poorly understood. Only in the last years, several proteins and posttranslational modifications of LKB1 have been analyzed to control its localization, activity and recognition of substrates. Here, we summarize the current knowledge about the upstream regulation of LKB1, which is important for the understanding of the pathogenesis of many types of tumors.
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25
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Lu Q, Xie Z, Yan C, Ding Y, Ma Z, Wu S, Qiu Y, Cossette SM, Bordas M, Ramchandran R, Zou MH. SNRK (Sucrose Nonfermenting 1-Related Kinase) Promotes Angiogenesis In Vivo. Arterioscler Thromb Vasc Biol 2018; 38:373-385. [PMID: 29242271 PMCID: PMC5785416 DOI: 10.1161/atvbaha.117.309834] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/28/2017] [Indexed: 01/19/2023]
Abstract
OBJECTIVE SNRK (sucrose nonfermenting 1-related kinase) is a novel member of the AMPK (adenosine monophosphate-activated protein kinase)-related superfamily that is activated in the process of angiogenesis. Currently, little is known about the function of SNRK in angiogenesis in the physiological and pathological conditions. APPROACH AND RESULTS In this study, in Snrk global heterozygous knockout mice, retina angiogenesis and neovessel formation after hindlimb ischemia were suppressed. Consistently, mice with endothelial cell (EC)-specific Snrk deletion exhibited impaired retina angiogenesis, and delayed perfusion recovery and exacerbated muscle apoptosis in ischemic hindlimbs, compared with those of littermate wide-type mice. Endothelial SNRK expression was increased in the extremity vessel samples from nonischemic human. In ECs cultured in hypoxic conditions, HIF1α (hypoxia inducible factor 1α) bound to the SNRK promoter to upregulate SNRK expression. In the nuclei of hypoxic ECs, SNRK complexed with SP1 (specificity protein 1), and together, they bound to an SP1-binding motif in the ITGB1 (β1 integrin) promoter, resulting in enhanced ITGB1 expression and promoted EC migration. Furthermore, SNRK or SP1 deficiency in ECs ameliorated hypoxia-induced ITGB1 expression and, consequently, inhibited EC migration and angiogenesis. CONCLUSIONS Taken together, our data have revealed that SNRK/SP1-ITGB1 signaling axis promotes angiogenesis in vivo.
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MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Apoptosis
- Blood Flow Velocity
- Cadherins/genetics
- Cadherins/metabolism
- Cell Movement
- Cell Proliferation
- Cells, Cultured
- Disease Models, Animal
- Endothelial Cells/enzymology
- Endothelial Cells/pathology
- Gene Expression Regulation, Enzymologic
- Hindlimb
- Human Umbilical Vein Endothelial Cells/enzymology
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Integrin beta1/genetics
- Integrin beta1/metabolism
- Ischemia/enzymology
- Ischemia/genetics
- Ischemia/physiopathology
- Lung/blood supply
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Skeletal/blood supply
- Neovascularization, Physiologic
- Promoter Regions, Genetic
- Protein Serine-Threonine Kinases/deficiency
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Regional Blood Flow
- Retinal Vessels/enzymology
- Sp1 Transcription Factor/genetics
- Sp1 Transcription Factor/metabolism
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Affiliation(s)
- Qiulun Lu
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Zhonglin Xie
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Chenghui Yan
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Ye Ding
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Zejun Ma
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Shengnan Wu
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Yu Qiu
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Stephanie M Cossette
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Michelle Bordas
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee
| | - Ramani Ramchandran
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee.
| | - Ming-Hui Zou
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Q.L., Z.X., C.Y., Y.D., Z.M., S.W., Y.Q., M.-H.Z.); and Division of Neonatology, Department of Pediatrics (S.M.C., M.B., R.R.) and Obstetrics and Gynecology (OBGYN), Developmental Vascular Biology Program, Children's Research Institute (R.R.), Medical College of Wisconsin, Milwaukee.
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Deletion of endothelial cell-specific liver kinase B1 increases angiogenesis and tumor growth via vascular endothelial growth factor. Oncogene 2017; 36:4277-4287. [PMID: 28346429 PMCID: PMC5532072 DOI: 10.1038/onc.2017.61] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 01/18/2017] [Accepted: 02/09/2017] [Indexed: 12/25/2022]
Abstract
Liver kinase B1 (LKB1) is a serine/threonine protein kinase ubiquitously expressed in mammalian cells. It was first identified in Peutz-Jeghers syndrome as a tumor suppressor gene. Whether endothelial LKB1 regulates angiogenesis and tumor growth is unknown. In this study, we generated endothelial cell-specific LKB1-knockout (LKB1endo−/−) mice by crossbreeding vascular endothelial-cadherin-Cre mice with LKB1flox/flox mice. Vascular endothelial growth factor (VEGF) level was highly co-stained in endothelial cells but not macrophages in LKB1endo−/− mice. Consistently, LKB1endo−/− mouse tissues including the lung, skin, kidney, and liver showed increased vascular permeability. Tumors implanted in LKB1endo−/− mice but not macrophage-specific LKB1-knockout mice grew faster and showed enhanced vascular permeability and increased angiogenesis as compared with those implanted in wild-type mice. Injection of VEGF-neutralizing antibody but not the isotype-matched control antibody decreased endothelial-cell angiogenesis and tumor growth in vivo. Furthermore, LKB1 deletion enhanced mouse retinal and cell angiogenesis, and knockdown of VEGF by small-interfering RNA decreased endothelial cell proliferation and migration. Re-expression of LKB1 or knockdown of VEGF receptor 2 decreased the over-proliferation and -migration observed in LKB1endo−/− cells. Mechanistically, LKB1 could bind to the VEGF transcription factor, specificity protein 1 (Sp1), which then inhibited the binding of Sp1 to the VEGF promoter to reduce VEGF expression. Endothelial LKB1 may regulate endothelial angiogenesis and tumor growth by modulating Sp1-mediated VEGF expression.
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27
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Luizon MR, Eckalbar WL, Wang Y, Jones SL, Smith RP, Laurance M, Lin L, Gallins PJ, Etheridge AS, Wright F, Zhou Y, Molony C, Innocenti F, Yee SW, Giacomini KM, Ahituv N. Genomic Characterization of Metformin Hepatic Response. PLoS Genet 2016; 12:e1006449. [PMID: 27902686 PMCID: PMC5130177 DOI: 10.1371/journal.pgen.1006449] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 10/25/2016] [Indexed: 12/26/2022] Open
Abstract
Metformin is used as a first-line therapy for type 2 diabetes (T2D) and prescribed for numerous other diseases. However, its mechanism of action in the liver has yet to be characterized in a systematic manner. To comprehensively identify genes and regulatory elements associated with metformin treatment, we carried out RNA-seq and ChIP-seq (H3K27ac, H3K27me3) on primary human hepatocytes from the same donor treated with vehicle control, metformin or metformin and compound C, an AMP-activated protein kinase (AMPK) inhibitor (allowing to identify AMPK-independent pathways). We identified thousands of metformin responsive AMPK-dependent and AMPK-independent differentially expressed genes and regulatory elements. We functionally validated several elements for metformin-induced promoter and enhancer activity. These include an enhancer in an ataxia telangiectasia mutated (ATM) intron that has SNPs in linkage disequilibrium with a metformin treatment response GWAS lead SNP (rs11212617) that showed increased enhancer activity for the associated haplotype. Expression quantitative trait locus (eQTL) liver analysis and CRISPR activation suggest that this enhancer could be regulating ATM, which has a known role in AMPK activation, and potentially also EXPH5 and DDX10, its neighboring genes. Using ChIP-seq and siRNA knockdown, we further show that activating transcription factor 3 (ATF3), our top metformin upregulated AMPK-dependent gene, could have an important role in gluconeogenesis repression. Our findings provide a genome-wide representation of metformin hepatic response, highlight important sequences that could be associated with interindividual variability in glycemic response to metformin and identify novel T2D treatment candidates. Metformin is among the most widely prescribed drugs. It is used as a first line therapy for type 2 diabetes (T2D), and for additional diseases including cancer. The variability in response to metformin is substantial and can be caused by genetic factors. However, the molecular mechanisms of metformin action are not fully known. Here, we used various genomic assays to analyze human liver cells treated with or without metformin and identified in a genome-wide manner thousands of differentially expressed genes and gene regulatory elements affected by metformin. Follow up functional assays identified several novel genes and regulatory elements to be associated with metformin response. These include ATF3, a gene that showed gluconeogenesis repression upon metformin response and a potential regulatory element of the ATM gene that is associated with metformin treatment differences through genome-wide association studies. Combined, this work identifies several novel genes and gene regulatory elements that can be activated due to metformin treatment and thus provides candidate sequences in the human genome where nucleotide variation can lead to differences in metformin response. It also enables the identification and prioritization of novel candidates for T2D treatment.
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Affiliation(s)
- Marcelo R. Luizon
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- Department of General Biology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Walter L. Eckalbar
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Yao Wang
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Stacy L. Jones
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Robin P. Smith
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Megan Laurance
- Library and Center for Knowledge Management, University of California San Francisco, San Francisco, California, United States of America
| | - Lawrence Lin
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Paul J. Gallins
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Amy S. Etheridge
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Fred Wright
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Yihui Zhou
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Cliona Molony
- Merck Research Labs, Merck & Co. Inc., Kenilworth, New Jersey, United States of America
| | - Federico Innocenti
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Kathleen M. Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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28
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Zhu Q, Ghoshal S, Rodrigues A, Gao S, Asterian A, Kamenecka TM, Barrow JC, Chakraborty A. Adipocyte-specific deletion of Ip6k1 reduces diet-induced obesity by enhancing AMPK-mediated thermogenesis. J Clin Invest 2016; 126:4273-4288. [PMID: 27701146 DOI: 10.1172/jci85510] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 08/29/2016] [Indexed: 12/15/2022] Open
Abstract
Enhancing energy expenditure (EE) is an attractive strategy to combat obesity and diabetes. Global deletion of Ip6k1 protects mice from diet-induced obesity (DIO) and insulin resistance, but the tissue-specific mechanism by which IP6K1 regulates body weight is unknown. Here, we have demonstrated that IP6K1 regulates fat accumulation by modulating AMPK-mediated adipocyte energy metabolism. Cold exposure led to downregulation of Ip6k1 in murine inguinal and retroperitoneal white adipose tissue (IWAT and RWAT) depots. Adipocyte-specific deletion of Ip6k1 (AdKO) enhanced thermogenic EE, which protected mice from high-fat diet-induced weight gain at ambient temperature (23°C), but not at thermoneutral temperature (30°C). AdKO-induced increases in thermogenesis also protected mice from cold-induced decreases in body temperature. UCP1, PGC1α, and other markers of browning and thermogenesis were elevated in IWAT and RWAT of AdKO mice. Cold-induced activation of sympathetic signaling was unaltered, whereas AMPK was enhanced, in AdKO IWAT. Moreover, beige adipocytes from AdKO IWAT displayed enhanced browning, which was diminished by AMPK depletion. Furthermore, we determined that IP6 and IP6K1 differentially regulate upstream kinase-mediated AMPK stimulatory phosphorylation in vitro. Finally, treating mildly obese mice with the IP6K inhibitor TNP enhanced thermogenesis and inhibited progression of DIO. Thus, IP6K1 regulates energy metabolism via a mechanism that could potentially be targeted in obesity.
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29
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Regulation and function of AMPK in physiology and diseases. Exp Mol Med 2016; 48:e245. [PMID: 27416781 PMCID: PMC4973318 DOI: 10.1038/emm.2016.81] [Citation(s) in RCA: 701] [Impact Index Per Article: 87.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 04/23/2016] [Accepted: 04/26/2016] [Indexed: 12/18/2022] Open
Abstract
5′-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase that was originally identified as the key player in maintaining cellular energy homeostasis. Intensive research over the last decade has identified diverse molecular mechanisms and physiological conditions that regulate the AMPK activity. AMPK regulates diverse metabolic and physiological processes and is dysregulated in major chronic diseases, such as obesity, inflammation, diabetes and cancer. On the basis of its critical roles in physiology and pathology, AMPK is emerging as one of the most promising targets for both the prevention and treatment of these diseases. In this review, we discuss the current understanding of the molecular and physiological regulation of AMPK and its metabolic and physiological functions. In addition, we discuss the mechanisms underlying the versatile roles of AMPK in diabetes and cancer.
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30
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Xi G, Shen X, Rosen CJ, Clemmons DR. IRS-1 Functions as a Molecular Scaffold to Coordinate IGF-I/IGFBP-2 Signaling During Osteoblast Differentiation. J Bone Miner Res 2016; 31:1300-14. [PMID: 26773517 PMCID: PMC5228590 DOI: 10.1002/jbmr.2791] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/12/2016] [Accepted: 01/15/2016] [Indexed: 12/29/2022]
Abstract
Insulin like growth factor I (IGF-I) and insulin like growth factor binding protein-2 (IGFBP-2) function coordinately to stimulate AKT and osteoblast differentiation. IGFBP-2 binding to receptor protein tyrosine phosphatase β (RPTPβ) stimulates polymerization and inactivation of phosphatase activity. Because phosphatase and tensin homolog (PTEN) is the primary target of RPTPβ, this leads to enhanced PTEN tyrosine phosphorylation and inactivation. However RPTPβ inactivation also requires IGF-I receptor activation. The current studies were undertaken to determine the mechanism by which IGF-I mediates changes in RPTPβ function in osteoblasts. IGFBP-2/IGF-I stimulated vimentin binding to RPTPβ and this was required for RPTPβ polymerization. Vimentin serine phosphorylation mediated its binding to RPTPβ and PKCζ was identified as the kinase that phosphorylated vimentin. To determine the mechanism underlying IGF-I stimulation of PKCζ-mediated vimentin phosphorylation, we focused on insulin receptor substrate-1 (IRS-1). IGF-I stimulated IRS-1 phosphorylation and recruitment of PKCζ and vimentin to phospho-IRS-1. IRS-1 immunoprecipitates containing PKCζ and vimentin were used to confirm that activated PKCζ directly phosphorylated vimentin. PKCζ does not contain a SH-2 domain that is required to bind to phospho-IRS-1. To determine the mechanism of PKCζ recruitment we analyzed the role of p62 (a PKCζ binding protein) that contains a SH2 domain. Exposure to differentiation medium plus IGF-I stimulated PKCζ/p62 association. Subsequent analysis showed the p62/PKCζ complex was co-recruited to IRS-1. Peptides that disrupted p62/PKCζ or p62/IRS-1 inhibited IGF-I/IGFBP-2 stimulated PKCζ activation, vimentin phosphorylation, PTEN tyrosine phosphorylation, AKT activation, and osteoblast differentiation. The importance of these signaling events for differentiation was confirmed in primary mouse calvarial osteoblasts. These results demonstrate the cooperative interaction between RPTPβ and the IGF-I receptor leading to a coordinated series of signaling events that are required for osteoblast differentiation. Our findings emphasize the important role IRS-1 plays in modulating these signaling events and confirm its essential role in facilitating osteoblast differentiation. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Gang Xi
- Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, NC, USA
| | - Xinchun Shen
- College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China
| | | | - David R Clemmons
- Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, NC, USA
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Shorning BY, Clarke AR. Energy sensing and cancer: LKB1 function and lessons learnt from Peutz-Jeghers syndrome. Semin Cell Dev Biol 2016; 52:21-9. [PMID: 26877140 DOI: 10.1016/j.semcdb.2016.02.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/08/2016] [Accepted: 02/08/2016] [Indexed: 12/31/2022]
Abstract
We describe in this review increasing evidence that loss of LKB1 kinase in Peutz-Jeghers syndrome (PJS) derails the existing natural balance between cell survival and tumour growth suppression. LKB1 deletion can plunge cells into an energy/oxidative stress-induced crisis which leads to the activation of alternative and often carcinogenic pathways to maintain cellular energy levels. It therefore appears that although LKB1 deficiency can suppress oncogenic transformation in the short term, it can ultimately lead to more progressed and malignant phenotypes by driving abnormal cell differentiation, genomic instability and increased tumour heterogeneity.
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Affiliation(s)
- Boris Y Shorning
- European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, United Kingdom.
| | - Alan R Clarke
- European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, United Kingdom
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Luo X, Jia R, Yao Q, Xu Y, Luo Z, Luo X, Wang N. Docosahexaenoic acid attenuates adipose tissue angiogenesis and insulin resistance in high fat diet-fed middle-aged mice via a sirt1-dependent mechanism. Mol Nutr Food Res 2016; 60:871-85. [PMID: 26750093 DOI: 10.1002/mnfr.201500714] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/14/2015] [Accepted: 12/29/2015] [Indexed: 02/07/2023]
Abstract
SCOPE Docosahexaenoic acid (DHA; C22: 6, n-3), one of PUFAs, exerts beneficial effects on inflammatory diseases, obesity and diabetes. Angiogenesis in adipose tissue has a major role in the development of obesity and its related metabolic complications. Inhibition of angiogenesis is an emerging strategy for the novel treatment for obesity. Thus, we examined the effect of DHA on angiogenesis in adipose tissues and investigated the underlying mechanisms. METHODS AND RESULTS In high-fat diet (HFD) fed middle-aged mice, DHA inhibited the macrophage-derived inflammation and angiogenesis in adipose tissues, reduced adipocyte size and body fat composition and improved insulin sensitivity. Moreover, DHA reversed the HFD-induced reduction of Sirt1 in adipose tissues. Interestingly, the effects of DHA were attenuated by lentivirus-mediated Sirt1 knockdown with increasing expression of markers of macrophage-derived inflammation and angiogenesis, associated with impaired insulin sensitivity. CONCLUSION Overall, our findings demonstrated that DHA reduced angiogenesis of adipose tissues and attenuated insulin resistance in HFD-induced obese mice via the activation of Sirt1.
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Affiliation(s)
- Xiaoqin Luo
- Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China.,Department of Medicine, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, P.R. China
| | - Ru Jia
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, P.R. China.,Department of Prosthodontics, Stomatological Hospital, College of Stomatology, Xi'an Jiaotong University, Xi'an, PR China
| | - Qinyu Yao
- Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Yirui Xu
- Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Zhenyu Luo
- Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Xiao Luo
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, P.R. China
| | - Nanping Wang
- Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China
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Hurtado de Llera A, Martin-Hidalgo D, Gil M, Garcia-Marin L, Bragado M. New insights into transduction pathways that regulate boar sperm function. Theriogenology 2016; 85:12-20. [DOI: 10.1016/j.theriogenology.2015.05.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/04/2015] [Accepted: 05/04/2015] [Indexed: 10/23/2022]
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He C, Li H, Viollet B, Zou MH, Xie Z. AMPK Suppresses Vascular Inflammation In Vivo by Inhibiting Signal Transducer and Activator of Transcription-1. Diabetes 2015; 64:4285-97. [PMID: 25858560 PMCID: PMC4657575 DOI: 10.2337/db15-0107] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/31/2015] [Indexed: 12/14/2022]
Abstract
Activation of AMPK suppresses inflammation, but the underlying mechanisms remain poorly understood. This study was designed to characterize the molecular mechanisms by which AMPK suppresses vascular inflammation. In cultured human aortic smooth muscle cells, pharmacologic or genetic activation of AMPK inhibited the signal transducer and activator of transcription-1 (STAT1), while inhibition of AMPK had opposite effects. Deletion of AMPKα1 or AMPKα2 resulted in activation of STAT1 and in increases in proinflammatory mediators, both of which were attenuated by administration of STAT1 small interfering RNA or fludarabine, a selective STAT1 inhibitor. Moreover, AMPK activation attenuated the proinflammatory actions induced by STAT1 activators such as interferon-γ and angiotensin II (AngII). Mechanistically, we found that AMPK activation increased, whereas AMPK inhibition decreased, the levels of mitogen-activated protein kinase phosphatase-1 (MKP-1), an inducible nuclear phosphatase, by regulating proteasome-dependent degradation of MKP-1. Gene silencing of MKP-1 increased STAT1 phosphorylation and prevented 5-aminoimidazole-4-carboxyamide ribonucleoside-reduced STAT1 phosphorylation. Finally, we found that infusion of AngII caused a more severe inflammatory response in AMPKα2 knockout mouse aortas, all of which were suppressed by chronic administration of fludarabine. We conclude that AMPK activation suppresses STAT1 signaling and inhibits vascular inflammation through the upregulation of MKP-1.
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MESH Headings
- AMP-Activated Protein Kinases/antagonists & inhibitors
- AMP-Activated Protein Kinases/chemistry
- AMP-Activated Protein Kinases/genetics
- AMP-Activated Protein Kinases/metabolism
- Angiotensin II/adverse effects
- Animals
- Anti-Inflammatory Agents, Non-Steroidal/pharmacology
- Aorta, Thoracic
- Cells, Cultured
- Dual Specificity Phosphatase 1/antagonists & inhibitors
- Dual Specificity Phosphatase 1/chemistry
- Dual Specificity Phosphatase 1/genetics
- Dual Specificity Phosphatase 1/metabolism
- Enzyme Activation/drug effects
- Humans
- Interferon-gamma/adverse effects
- MAP Kinase Signaling System/drug effects
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/immunology
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Phosphorylation/drug effects
- Protein Processing, Post-Translational/drug effects
- RNA Interference
- Random Allocation
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- STAT1 Transcription Factor/agonists
- STAT1 Transcription Factor/antagonists & inhibitors
- STAT1 Transcription Factor/genetics
- STAT1 Transcription Factor/metabolism
- Vasculitis/chemically induced
- Vasculitis/immunology
- Vasculitis/metabolism
- Vasculitis/pathology
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Affiliation(s)
- Chaoyong He
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Hongliang Li
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Benoit Viollet
- INSERM U1016, Institut Cochin, Paris, France CNRS UMR 8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Ming-Hui Zou
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Zhonglin Xie
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK
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Liu Z, Dai X, Zhu H, Zhang M, Zou MH. Lipopolysaccharides Promote S-Nitrosylation and Proteasomal Degradation of Liver Kinase B1 (LKB1) in Macrophages in Vivo. J Biol Chem 2015; 290:19011-7. [PMID: 26070564 PMCID: PMC4521026 DOI: 10.1074/jbc.m115.649210] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/11/2015] [Indexed: 01/28/2023] Open
Abstract
LKB1 (liver kinase B1) plays important roles in tumor suppression, energy metabolism, and, recently, in innate immune responses. However, how LKB1 is regulated under physiological or pathological conditions is still unclear. Here, we report that LKB1 protein (but not mRNA) was decreased in both LPS-treated RAW 264.7 cells and peritoneal macrophages isolated from LPS-challenged mice. Additional LPS treatment promoted protein ubiquitination and degradation of LKB1. Pharmacological inhibition or gene silencing of inducible NOS abrogated LPS-induced LKB1 degradation, whereas exposure of RAW 264.7 cells to S-nitroso-l-glutathione, a NO donor, triggered LKB1 S-nitrosylation. Consistently, mutation of one cysteine (C430S) in LKB1 prevented LPS-induced S-nitrosylation, ubiquitination, and degradation. Moreover, S-nitrosylation and ubiquitination of LKB1 were confirmed in macrophages from LPS-challenged mice in vivo. Co-administration of the inducible NOS inhibitor S-methylisothiourea or the proteasome inhibitor MG132 prevented LPS-induced LKB1 degradation and improved the survival rate. Finally, mice lacking LKB1 in macrophages had significantly lower survival rates in response to LPS challenge compared with wild-type mice. Thus, we concluded that LKB1 is degraded by LPS treatment via S-nitrosylation-dependent proteasome pathways, and this had a protective role in LPS-induced septic shock.
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Affiliation(s)
- Zhaoyu Liu
- From the Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Xiaoyan Dai
- From the Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Huaiping Zhu
- From the Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Miao Zhang
- From the Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Ming-Hui Zou
- From the Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
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Phosphoproteomic Analysis of KSHV-Infected Cells Reveals Roles of ORF45-Activated RSK during Lytic Replication. PLoS Pathog 2015; 11:e1004993. [PMID: 26133373 PMCID: PMC4489790 DOI: 10.1371/journal.ppat.1004993] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/02/2015] [Indexed: 12/13/2022] Open
Abstract
Kaposi’s Sarcoma-Associated Herpesvirus (KSHV) is an oncogenic virus which has adapted unique mechanisms to modulate the cellular microenvironment of its human host. The pathogenesis of KSHV is intimately linked to its manipulation of cellular signaling pathways, including the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway. We have previously shown that KSHV ORF45 contributes to the sustained activation of both ERK and p90 ribosomal S6 kinase (RSK, a major functional mediator of ERK/MAPK signaling) during KSHV lytic replication. ORF45-activated RSK is required for optimal KSHV lytic gene expression and progeny virion production, though the underlying mechanisms downstream of this activation are still unclear. We hypothesized that the activation of RSK by ORF45 causes differential phosphorylation of cellular and viral substrates, affecting biological processes essential for efficient KSHV lytic replication. Accordingly, we observed widespread and significant differences in protein phosphorylation upon induction of lytic replication. Mass-spectrometry-based phosphoproteomic screening identified putative substrates of ORF45-activated RSK in KSHV-infected cells. Bioinformatic analyses revealed that nuclear proteins, including several transcriptional regulators, were overrepresented among these candidates. We validated the ORF45/RSK-dependent phosphorylation of several putative substrates by employing KSHV BAC mutagenesis, kinase inhibitor treatments, and/or CRISPR-mediated knockout of RSK in KSHV-infected cells. Furthermore, we assessed the consequences of knocking out these substrates on ORF45/RSK-dependent regulation of gene expression and KSHV progeny virion production. Finally, we show data to support that ORF45 regulates the translational efficiency of a subset of viral/cellular genes with complex secondary structure in their 5’ UTR. Altogether, these data shed light on the mechanisms by which KSHV ORF45 manipulates components of the host cell machinery via modulation of RSK activity. Thus, this study has important implications for the pathobiology of KSHV and other diseases in which RSK activity is dysregulated. Kaposi’s sarcoma-associated herpesvirus (KSHV) is a human tumor virus which hijacks the host signaling pathways in order to maintain persistent infection. We previously discovered that the KSHV protein ORF45 binds to and activates the cellular kinase RSK (p90 ribosomal S6 kinase), and that this activation is vital for optimal KSHV gene expression and virion production. Here, we performed a phosphoproteomic analysis of KSHV-infected cells to further characterize the specific substrates of ORF45-activated RSK. Bioinformatic analyses provided insights into the functional roles of these substrates. We verified the ORF45/RSK-dependent phosphorylation of a subset of these substrates by various means. Finally, we used genome editing to knock out RSK, as well as several cellular substrates identified by our screening, and characterized the consequent effect(s) on regulation of gene expression and virion production. Thus, this work further elucidates one of the key signaling nodes modulated by KSHV, and implicates ORF45-mediated activation of RSK in the regulation of viral and host gene expression during KSHV lytic replication.
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Wu Y, Song P, Zhang W, Liu J, Dai X, Liu Z, Lu Q, Ouyang C, Xie Z, Zhao Z, Zhuo X, Viollet B, Foretz M, Wu J, Yuan Z, Zou MH. Activation of AMPKα2 in adipocytes is essential for nicotine-induced insulin resistance in vivo. Nat Med 2015; 21:373-82. [PMID: 25799226 PMCID: PMC4390501 DOI: 10.1038/nm.3826] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 02/17/2015] [Indexed: 12/15/2022]
Abstract
Cigarette smoking promotes body weight reduction in humans while paradoxically also promoting insulin resistance (IR) and hyperinsulinemia. However, the mechanisms behind these effects are unclear. Here we show that nicotine, a major constituent of cigarette smoke, selectively activates AMP-activated protein kinase α2 (AMPKα2) in adipocytes, which in turn phosphorylates MAP kinase phosphatase-1 (MKP1) at serine 334, initiating its proteasome-dependent degradation. The nicotine-dependent reduction of MKP1 induces the aberrant activation of both p38 mitogen-activated protein kinase and c-Jun N-terminal kinase, leading to increased phosphorylation of insulin receptor substrate 1 (IRS1) at serine 307. Phosphorylation of IRS1 leads to its degradation, protein kinase B inhibition, and the loss of insulin-mediated inhibition of lipolysis. Consequently, nicotine increases lipolysis, which results in body weight reduction, but this increase also elevates the levels of circulating free fatty acids and thus causes IR in insulin-sensitive tissues. These results establish AMPKα2 as an essential mediator of nicotine-induced whole-body IR in spite of reductions in adiposity.
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Affiliation(s)
- Yue Wu
- 1] Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. [2] Department of Cardiology, Cardiovascular Research Center, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Ping Song
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Wencheng Zhang
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Junhui Liu
- Department of Cardiology, Cardiovascular Research Center, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Xiaoyan Dai
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Zhaoyu Liu
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Qiulun Lu
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Changhan Ouyang
- 1] Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. [2] Key Laboratory of Hubei Province on Cardio-Cerebral Diseases, Hubei University of Science and Technology, Xianning, Hubei, China
| | - Zhonglin Xie
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Zhengxing Zhao
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Xiaozhen Zhuo
- Department of Cardiology, Cardiovascular Research Center, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Benoit Viollet
- 1] INSERM, U1016, Institut Cochin, Paris, France. [2] CNRS, UMR 8104, Paris, France. [3] Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Marc Foretz
- 1] INSERM, U1016, Institut Cochin, Paris, France. [2] CNRS, UMR 8104, Paris, France. [3] Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jiliang Wu
- Key Laboratory of Hubei Province on Cardio-Cerebral Diseases, Hubei University of Science and Technology, Xianning, Hubei, China
| | - Zuyi Yuan
- Department of Cardiology, Cardiovascular Research Center, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Ming-Hui Zou
- 1] Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. [2] Key Laboratory of Hubei Province on Cardio-Cerebral Diseases, Hubei University of Science and Technology, Xianning, Hubei, China
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Shen X, Xi G, Wai C, Clemmons DR. The coordinate cellular response to insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding protein-2 (IGFBP-2) is regulated through vimentin binding to receptor tyrosine phosphatase β (RPTPβ). J Biol Chem 2015; 290:11578-90. [PMID: 25787077 DOI: 10.1074/jbc.m114.620237] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Indexed: 12/16/2022] Open
Abstract
Insulin-like growth factor-binding protein-2 (IGFBP-2) functions coordinately with IGF-I to stimulate cellular proliferation and differentiation. IGFBP-2 binds to receptor tyrosine phosphatase β (RPTPβ), and this binding in conjunction with IGF-I receptor stimulation induces RPTPβ polymerization leading to phosphatase and tensin homolog inactivation, AKT stimulation, and enhanced cell proliferation. To determine the mechanism by which RPTPβ polymerization is regulated, we analyzed the protein(s) that associated with RPTPβ in response to IGF-I and IGFBP-2 in vascular smooth muscle cells. Proteomic experiments revealed that IGF-I stimulated the intermediate filament protein vimentin to bind to RPTPβ, and knockdown of vimentin resulted in failure of IGFBP-2 and IGF-I to stimulate RPTPβ polymerization. Knockdown of IGFBP-2 or inhibition of IGF-IR tyrosine kinase disrupted vimentin/RPTPβ association. Vimentin binding to RPTPβ was mediated through vimentin serine phosphorylation. The serine threonine kinase PKCζ was recruited to vimentin in response to IGF-I and inhibition of PKCζ activation blocked these signaling events. A cell-permeable peptide that contained the vimentin phosphorylation site disrupted vimentin/RPTPβ association, and IGF-I stimulated RPTPβ polymerization and AKT activation. Integrin-linked kinase recruited PKCζ to SHPS-1-associated vimentin in response to IGF-I and inhibition of integrin-linked kinase/PKCζ association reduced vimentin serine phosphorylation. PKCζ stimulation of vimentin phosphorylation required high glucose and vimentin/RPTPβ-association occurred only during hyperglycemia. Disruption of vimetin/RPTPβ in diabetic mice inhibited RPTPβ polymerization, vimentin serine phosphorylation, and AKT activation in response to IGF-I, whereas nondiabetic mice showed no difference. The induction of vimentin phosphorylation is important for IGFBP-2-mediated enhancement of IGF-I-stimulated proliferation during hyperglycemia, and it coordinates signaling between these two receptor-linked signaling systems.
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Affiliation(s)
- Xinchun Shen
- the College of Food Science and Engineering/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, Nanjing 210023, China
| | - Gang Xi
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 and
| | - Christine Wai
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 and
| | - David R Clemmons
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 and
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Yang Y, Zhao Z, Liu Y, Kang X, Zhang H, Meng M. Suppression of oxidative stress and improvement of liver functions in mice by ursolic acid via LKB1-AMP-activated protein kinase signaling. J Gastroenterol Hepatol 2015; 30:609-18. [PMID: 25168399 DOI: 10.1111/jgh.12723] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/06/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Hepatic cirrhosis is the final stage of liver dysfunction, characterized by diffuse fibrosis, which is the main response to the liver injury. This study is to investigate the effects of ursolic acid (UA) on liver functions and fibrosis in bile duct ligation (BDL) mice and to determine the underlying mechanisms. METHODS Cultured hepatocytes were treated with lipopolysaccharide (LPS) in the presence or absence of UA. The reactive oxygen species (ROS) level, protein levels of IκBα, iNOS and Cox-2, and NF-κB activation were detected, respectively. C57/BL6 and AMP-activated protein kinase (AMPK)α2(-/-) mice were subjected to BDL for 14 days. UA was administered by gavage. The markers of liver function and oxidative stress, and liver histopathology were analyzed after treatment. RESULTS Treatment of hepatocytes with UA dose-dependently activates AMPK, which is abolished by silence of liver kinase B1 (LKB1). LPS significantly increased ROS productions, apoptosis, NF-κB activation, and expressions of iNOS and Cox-2 in cultured hepatocytes. All these effects were blocked by co-incubation with UA. Importantly, silence of LKB1, AMPK, or iNOS/Cox-2 by small interference RNA transfection reversed UA-induced effects in cultured cells. In an animal study, 14-day BDL induced liver fibrosis and liver injury, accompanied with increased oxidative stress and protein expressions of iNOS and Cox-2 in liver. Treatment of UA significantly attenuated the BDL-induced detrimental effects in wild-type mice but not in AMPKα2(-/-) mice. CONCLUSION UA via LKB1-AMPK signaling offers protective effects on BDL-induced liver injury in mice, which may be related to inhibition of oxidative stress.
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Affiliation(s)
- Yongbin Yang
- College of Life Sciences, Hebei University, Baoding, China; Health Science Center, Hebei University, Baoding, China
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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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Okon IS, Coughlan KA, Zhang C, Moriasi C, Ding Y, Song P, Zhang W, Li G, Zou MH. Protein kinase LKB1 promotes RAB7-mediated neuropilin-1 degradation to inhibit angiogenesis. J Clin Invest 2014; 124:4590-602. [PMID: 25180605 DOI: 10.1172/jci75371] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 07/25/2014] [Indexed: 12/16/2022] Open
Abstract
After internalization, transmembrane receptors (TMRs) are typically recycled back to the cell surface or targeted for degradation. Efficient TMR trafficking is critical for regulation of several processes, including signal transduction pathways, development, and disease. Here, we determined that trafficking of the angiogenic receptor neuropilin-1 (NRP-1) is abrogated by the liver kinase B1 (LKB1), a serine-threonine kinase of the calcium calmodulin family. We found that aberrant NRP-1 expression in tumor cells from patients with lung adenocarcinoma is associated with decreased levels of LKB1. In cultured lung cells, LKB1 accentuated formation of a complex between NRP-1 and RAB7 in late endosomes. LKB1 specifically bound GTP-bound RAB7, but not a dominant-negative GDP-bound form of RAB7, promoting rapid transfer and lysosome degradation of NRP-1. siRNA-mediated depletion of RAB7 disrupted the transfer of NRP-1 to the lysosome, resulting in recovery of the receptor as well as increased tumor growth and angiogenesis. Together, our findings indicate that LKB1 functions as a RAB7 effector and suppresses angiogenesis by promoting the cellular trafficking of NRP-1 from RAB7 vesicles to the lysosome for degradation. Furthermore, these data suggest that LKB1 and NRP-1 have potential as therapeutic targets for limiting tumorigenesis.
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Li H, Min Q, Ouyang C, Lee J, He C, Zou MH, Xie Z. AMPK activation prevents excess nutrient-induced hepatic lipid accumulation by inhibiting mTORC1 signaling and endoplasmic reticulum stress response. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1844-54. [PMID: 25016145 DOI: 10.1016/j.bbadis.2014.07.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/01/2014] [Accepted: 07/02/2014] [Indexed: 02/06/2023]
Abstract
Lipid accumulation is a central event in the development of chronic metabolic diseases, including obesity and type 2 diabetes, but the mechanisms responsible for lipid accumulation are incompletely understood. This study was designed to investigate the mechanisms for excess nutrient-induced lipid accumulation and whether activation of AMP-activated protein kinase (AMPK) prevents the hepatic lipid accumulation in excess nutrient-treated HepG2 cells and high fat diet (HFD)-fed mice. Exposure of HepG2 cells to high levels of glucose or palmitate induced the endoplasmic reticulum (ER) stress response, activated sterol regulatory element-binding protein-1 (SREBP-1), and enhanced lipid accumulation, all of which were sensitive to ER stress inhibitor and gene silencing of eukaryotic initiation factor 2α. The increases in ER stress response and lipid accumulation were associated with activation of mammalian target of rapamycin complex 1 (mTORC1) signaling. Inhibition of mTORC1 signaling attenuated the ER stress response and lipid accumulation induced by high glucose or by deletion of tuberous sclerosis 2. In addition, AMPK activation prevented the mTORC1 activation, ER stress response, and lipid accumulation. This effect was mimicked or abrogated, respectively, by overexpression of constitutively active and dominant-negative AMPK mutants. Finally, treatment of HFD-fed mice with 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside inhibited the mTORC1 pathway, suppressed the ER stress response, and prevented insulin resistance and hepatic lipid accumulation. We conclude that activation of AMPK prevents excess nutrient-induced hepatic lipid accumulation by inhibiting mTORC1 and ER stress response.
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Affiliation(s)
- Hongliang Li
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Qing Min
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Changhan Ouyang
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Jiyeon Lee
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Chaoyong He
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Ming-Hui Zou
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Zhonglin Xie
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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Abstract
The increased prevalence of obesity has mandated extensive research focused on mechanisms responsible for associated clinical complications. Emerging from the focus on adipose tissue biology as a vitally important adipokine is adiponectin which is now believed to mediate anti-diabetic, anti-atherosclerotic, anti-inflammatory, cardioprotective and cancer modifying actions. Adiponectin mediates these primarily beneficial effects via direct signaling effects and via enhancing insulin sensitivity via crosstalk with insulin signaling pathways. Reduced adiponectin action is detrimental and occurs in obesity via decreased circulating levels of adiponectin action or development of adiponectin resistance. This review will focus on cellular mechanisms of adiponectin action, their crosstalk with insulin signaling and the resultant role of adiponectin in cardiovascular disease, diabetes and cancer and reviews data from in vitro cell based studies through animal models to clinical observations.
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Affiliation(s)
- Michael P Scheid
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
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Klenke U, Taylor-Burds C, Wray S. Metabolic influences on reproduction: adiponectin attenuates GnRH neuronal activity in female mice. Endocrinology 2014; 155:1851-63. [PMID: 24564393 PMCID: PMC3990841 DOI: 10.1210/en.2013-1677] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Metabolic dysfunctions are often linked to reproductive abnormalities. Adiponectin (ADP), a peripheral hormone secreted by white adipose tissue, is important in energy homeostasis and appetite regulation. GnRH neurons are integral components of the reproductive axis, controlling synthesis, and release of gonadotropins. This report examined whether ADP can directly act on GnRH neurons. Double-label immunofluorescence on brain sections from adult female revealed that a subpopulation of GnRH neurons express ADP receptor (AdipoR)2. GnRH/AdipoR2+ cells were distributed throughout the forebrain. To determine the influence of ADP on GnRH neuronal activity and the signal transduction pathway of AdipoR2, GnRH neurons maintained in explants were assayed using whole-cell patch clamping and calcium imaging. This mouse model system circumvents the dispersed distribution of GnRH neurons within the forebrain, making analysis of large numbers of GnRH cells possible. Single-cell PCR analysis and immunocytochemistry confirmed the presence of AdipoR2 in GnRH neurons in explants. Functional analysis revealed 20% of the total GnRH population responded to ADP, exhibiting hyperpolarization or decreased calcium oscillations. Perturbation studies revealed that ADP activates AMP kinase via the protein kinase Cζ/liver kinase B1 pathway. The modulation of GnRH neuronal activity by ADP demonstrated in this report directly links energy balance to neurons controlling reproduction.
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Affiliation(s)
- Ulrike Klenke
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland 20892-3703
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45
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Ju C, Roth RA. PKCs: pernicious kinase culprits in acetaminophen pathogenesis. Hepatology 2014; 59:1229-31. [PMID: 24677191 DOI: 10.1002/hep.26923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/06/2013] [Accepted: 10/31/2013] [Indexed: 12/07/2022]
Affiliation(s)
- Cynthia Ju
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO
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46
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Hurtado de Llera A, Martin-Hidalgo D, Gil MC, Garcia-Marin LJ, Bragado MJ. The calcium/CaMKKalpha/beta and the cAMP/PKA pathways are essential upstream regulators of AMPK activity in boar spermatozoa. Biol Reprod 2014; 90:29. [PMID: 24389872 DOI: 10.1095/biolreprod.113.112797] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Spermatozoa successfully fertilize oocytes depending on cell energy-sensitive processes. We recently showed that the cell energy sensor, the AMP-activated protein kinase (AMPK), plays a relevant role in spermatozoa by regulating motility as well as plasma membrane organization and acrosomal integrity, and contributes to the maintenance of mitochondrial membrane potential. As the signaling pathways that control AMPK activity have been studied exclusively in somatic cells, our aim is to investigate the intracellular pathways that regulate AMPK phosphorylation at Thr(172) (activity) in male germ cells. Boar spermatozoa were incubated under different conditions in the presence or absence of Ca(2+), 8Br-cAMP, IBMX, PMA, the AMPK activator A769662, or inhibitors of PKA, PKC, or CaMKKalpha/beta. AMPK phosphorylation was evaluated by Western blot using anti-phospho-Thr(172)-AMPK antibody. Data show that AMPK phosphorylation in spermatozoa is potently stimulated by an elevation of cAMP levels through the activation of PKA, as the PKA inhibitor H89 blocks phospho-Thr(172)-AMPK. Another mechanism to potently activate AMPK is Ca(2+) that acts through two pathways, PKA (blocked by H89) and CaMKKalpha/beta (blocked by STO-609). Moreover, phospho-Thr(172)-AMPK levels greatly increased upon PKC activation induced by PMA, and the PKC inhibitor Ro-32-0432 inhibits TCM-induced AMPK activation. Different stimuli considered as cell stresses (rotenone, cyanide, sorbitol, and complete absence of intracellular Ca(2+) by BAPTA-AM) also cause AMPK phosphorylation in spermatozoa. In summary, AMPK activity in boar spermatozoa is regulated upstream by different kinases, such as PKA, CaMKKalpha/beta, and PKC, as well as by the essential intracellular messengers for spermatozoan function, Ca(2+) and cAMP levels.
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Affiliation(s)
- Ana Hurtado de Llera
- Research Group of Intracellular Signaling and Technology of Reproduction, School of Veterinary Medicine, University of Extremadura, Caceres, Spain
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Li H, Lee J, He C, Zou MH, Xie Z. Suppression of the mTORC1/STAT3/Notch1 pathway by activated AMPK prevents hepatic insulin resistance induced by excess amino acids. Am J Physiol Endocrinol Metab 2014; 306:E197-209. [PMID: 24302004 PMCID: PMC3920006 DOI: 10.1152/ajpendo.00202.2013] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nutrient overload is associated with the development of obesity, insulin resistance, and type 2 diabetes. However, the underlying mechanisms for developing insulin resistance in the presence of excess nutrients are incompletely understood. We investigated whether activation of AMP-activated protein kinase (AMPK) prevents the hepatic insulin resistance that is induced by the consumption of a high-protein diet (HPD) and the presence of excess amino acids. Exposure of HepG2 cells to excess amino acids reduced AMPK phosphorylation, upregulated Notch1 expression, and impaired the insulin-stimulated phosphorylation of Akt Ser(473) and insulin receptor substrate-1 (IRS-1) Tyr(612). Inhibition of Notch1 prevented amino acid-induced insulin resistance, which was accompanied by reduced expression of Rbp-Jk, hairy and enhancer of split-1, and forkhead box O1. Mechanistically, mTORC1 signaling was activated by excess amino acids, which then positively regulated Notch1 expression through the activation of the signal transducer and activator of transcription 3 (STAT3). Activation of AMPK by metformin inhibited mTORC1-STAT3 signaling, thereby preventing excess amino acid-impaired insulin signaling. Finally, HPD feeding suppressed AMPK activity, activated mTORC1/STAT3/Notch1 signaling, and induced insulin resistance. Chronic administration of either metformin or rapamycin inhibited the HPD-activated mTORC1/STAT3/Notch1 signaling pathway and prevented hepatic insulin resistance. We conclude that the upregulation of Notch1 expression by hyperactive mTORC1 signaling is an essential event in the development of hepatic insulin resistance in the presence of excess amino acids. Activation of AMPK prevents amino acid-induced insulin resistance through the suppression of the mTORC1/STAT3/Notch1 signaling pathway.
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Affiliation(s)
- Hongliang Li
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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48
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Okon IS, Coughlan KA, Zou MH. Liver kinase B1 expression promotes phosphatase activity and abrogation of receptor tyrosine kinase phosphorylation in human cancer cells. J Biol Chem 2013; 289:1639-48. [PMID: 24285539 DOI: 10.1074/jbc.m113.500934] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Aberrant receptor tyrosine kinase phosphorylation (pRTK) has been associated with diverse pathological conditions, including human neoplasms. In lung cancer, frequent liver kinase B1 (LKB1) mutations correlate with tumor progression, but potential links with pRTK remain unknown. Heightened and sustained receptor activation was demonstrated by LKB1-deficient A549 (lung) and HeLaS3 (cervical) cancer cell lines. Depletion (siRNA) of endogenous LKB1 expression in H1792 lung cancer cells also correlated with increased pRTK. However, ectopic LKB1 expression in A549 and HeLaS3 cell lines, as well as H1975 activating-EGF receptor mutant lung cancer cell resulted in dephosphorylation of several tumor-enhancing RTKs, including EGF receptor, ErbB2, hepatocyte growth factor receptor (c-Met), EphA2, rearranged during transfection (RET), and insulin-like growth factor I receptor. Receptor abrogation correlated with attenuation of phospho-Akt and increased apoptosis. Global phosphatase inhibition by orthovanadate or depletion of protein tyrosine phosphatases (PTPs) resulted in the recovery of receptor phosphorylation. Specifically, the activity of SHP-2, PTP-1β, and PTP-PEST was enhanced by LKB1-expressing cells. Our findings provide novel insight on how LKB1 loss of expression or function promotes aberrant RTK signaling and rapid growth of cancer cells.
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49
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Ouyang C, You J, Xie Z. The interplay between autophagy and apoptosis in the diabetic heart. J Mol Cell Cardiol 2013; 71:71-80. [PMID: 24513079 DOI: 10.1016/j.yjmcc.2013.10.014] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 10/07/2013] [Accepted: 10/21/2013] [Indexed: 11/19/2022]
Abstract
Diabetic cardiomyopathy is characterized by ventricular dysfunction that occurs in diabetic patients independent of coronary artery disease, hypertension, and any other cardiovascular diseases. Diabetic cardiomyopathy has become a major cause of diabetes-related mortality. Thus, an urgent need exists to clarify the mechanism of pathogenesis. Emerging evidence demonstrates that diabetes induces cardiomyocyte apoptosis and suppresses cardiac autophagy, indicating that the interplay between the autophagy and apoptotic cell death pathways is important in the pathogenesis of diabetic cardiomyopathy. This review highlights recent advances in the crosstalk between autophagy and apoptosis and its importance in the development of diabetic cardiomyopathy. This article is part of a Special Issue entitled "Protein Quality Control, the Ubiquitin Proteasome System, and Autophagy".
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Affiliation(s)
- Changhan Ouyang
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Jieyun You
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Zhonglin Xie
- Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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50
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Manwani B, McCullough LD. Function of the master energy regulator adenosine monophosphate-activated protein kinase in stroke. J Neurosci Res 2013; 91:1018-29. [PMID: 23463465 PMCID: PMC4266469 DOI: 10.1002/jnr.23207] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 12/24/2012] [Accepted: 01/05/2013] [Indexed: 01/09/2023]
Abstract
Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionarily conserved signaling molecule that is emerging as one of the most important energy sensors in the body. AMPK monitors cellular energy status and is activated via phosphorylation when energy stores are low. This allows for maintenance of energy homeostasis by promoting catabolic pathways for ATP production and limiting processes that consume ATP. Growing number of stimuli have been shown to activate AMPK, and AMPK has been implicated in many diverse biological processes, including cell polarity, autophagy, and senescence. The effect of AMPK activation and its biological functions are extremely diverse and depend on both the overall energy "milieu" and the location and duration of activation. AMPK has tissue- and isoform-specific functions in the brain vs. periphery. These functions and the pathways activated also appear to differ by cell location (hypothalamus vs. cortex), cell type (astrocyte vs. neuron), and duration of exposure. Short bursts of AMPK activation have been found to be involved in ischemic preconditioning and neuronal survival; however, prolonged AMPK activity during ischemia leads to neuronal cell death. AMPK may also underlie some of the beneficial effects of hypothermia, a potential therapy for ischemic brain injury. This review discusses the role of AMPK in ischemic stroke, a condition of severe energy depletion.
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Affiliation(s)
- Bharti Manwani
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Louise D. McCullough
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
- Department of Neurology, University of Connecticut Health Center, Farmington, Connecticut
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