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Escudero-Ferruz P, Ontiveros N, Cano-Estrada C, Sutcliffe DJ, Jinnah HA, Torres RJ, López JM. A new physiological medium uncovers biochemical and cellular alterations in Lesch-Nyhan disease fibroblasts. Mol Med 2024; 30:3. [PMID: 38172668 PMCID: PMC10765874 DOI: 10.1186/s10020-023-00774-8] [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: 11/07/2023] [Accepted: 12/21/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Lesch-Nyhan disease (LND) is a severe neurological disorder caused by the genetic deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGprt), an enzyme involved in the salvage synthesis of purines. To compensate this deficiency, there is an acceleration of the de novo purine biosynthetic pathway. Most studies have failed to find any consistent abnormalities of purine nucleotides in cultured cells obtained from the patients. Recently, it has been shown that 5-aminoimidazole-4-carboxamide riboside 5'-monophosphate (ZMP), an intermediate of the de novo pathway, accumulates in LND fibroblasts maintained with RPMI containing physiological levels (25 nM) of folic acid (FA), which strongly differs from FA levels of regular cell culture media (2200 nM). However, RPMI and other standard media contain non-physiological levels of many nutrients, having a great impact in cell metabolism that does not precisely recapitulate the in vivo behavior of cells. METHODS We prepared a new culture medium containing physiological levels of all nutrients, including vitamins (Plasmax-PV), to study the potential alterations of LND fibroblasts that may have been masked by the usage of non-physiological media. We quantified ZMP accumulation under different culture conditions and evaluated the activity of two known ZMP-target proteins (AMPK and ADSL), the mRNA expression of the folate carrier SLC19A1, possible mitochondrial alterations and functional consequences in LND fibroblasts. RESULTS LND fibroblasts maintained with Plasmax-PV show metabolic adaptations such a higher glycolytic capacity, increased expression of the folate carrier SCL19A1, and functional alterations such a decreased mitochondrial potential and reduced cell migration compared to controls. These alterations can be reverted with high levels of folic acid, suggesting that folic acid supplements might be a potential treatment for LND. CONCLUSIONS A complete physiological cell culture medium reveals new alterations in Lesch-Nyhan disease. This work emphasizes the importance of using physiological cell culture conditions when studying a metabolic disorder.
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Affiliation(s)
- Paula Escudero-Ferruz
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Neus Ontiveros
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Claudia Cano-Estrada
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Diane J Sutcliffe
- Department of Neurology, Emory University School of Medicine, 101 Woodruff Circle, 6305 Woodruff Memorial Building, Atlanta, GA, 30322, USA
| | - H A Jinnah
- Department of Neurology, Emory University School of Medicine, 101 Woodruff Circle, 6305 Woodruff Memorial Building, Atlanta, GA, 30322, USA
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, 30322, USA
- Department of Pediatrics, Emory University School Medicine, Atlanta, GA, 30322, USA
| | - Rosa J Torres
- Center for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III (ISCIII), 28029, Madrid, Spain
- Department of Biochemistry, La Paz University Hospital Health Research Institute, IdiPaz, 28046, Madrid, Spain
| | - José M López
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
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2
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Cano-Estrada C, de Benito-Gómez L, Escudero-Ferruz P, Ontiveros N, Iglesias-Serret D, López JM. Purine Nucleotide Alterations in Tumoral Cell Lines Maintained with Physiological Levels of Folic Acid. Int J Mol Sci 2023; 24:12573. [PMID: 37628755 PMCID: PMC10454412 DOI: 10.3390/ijms241612573] [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: 06/28/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Most cancer cells have an increased synthesis of purine nucleotides to fulfil their enhanced division rate. The de novo synthesis of purines requires folic acid in the form of N10-formyltetrahydrofolate (10-formyl-THF). However, regular cell culture media contain very high, non-physiological concentrations of folic acid, which may have an impact on cell metabolism. Using cell culture media with physiological levels of folic acid (25 nM), we uncover purine alterations in several human cell lines. HEK293T, Jurkat, and A549 cells accumulate 5'-aminoimidazole-4-carboxamide ribonucleotide (ZMP), an intermediary of the de novo biosynthetic pathway, at physiological levels of folic acid, but not with the artificially high levels (2200 nM) present in regular media. Interestingly, HEK293T and Jurkat cells do not accumulate high levels of ZMP when AICAr, the precursor of ZMP, is added to medium containing 2200 nM folate; instead, ATP levels are increased, suggesting an enhanced de novo synthesis. On the other hand, HeLa and EHEB cells do not accumulate ZMP at physiological levels of folic acid, but they do accumulate in medium containing AICAr plus 2200 nM folate. Expression of SLC19A1, which encodes the reduced folate carrier (RFC), is increased in HEK293T and Jurkat cells compared with HeLa and EHEB, and it is correlated with the total purine nucleotide content at high levels of folic acid or with ZMP accumulation at physiological levels of folic acid. In conclusion, tumoral cell lines show a heterogenous response to folate changes in the media, some of them accumulating ZMP at physiological levels of folic acid. Further research is needed to clarify the ZMP downstream targets and their impact on cell function.
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Affiliation(s)
- Claudia Cano-Estrada
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Lidia de Benito-Gómez
- Departament de Ciències Fisiològiques, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona-IDIBELL (Institut d’Investigació Biomèdica de Bellvitge), 08907 L’Hospitalet de Llobregat, Barcelona, Spain
| | - Paula Escudero-Ferruz
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Neus Ontiveros
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Daniel Iglesias-Serret
- Departament de Ciències Fisiològiques, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona-IDIBELL (Institut d’Investigació Biomèdica de Bellvitge), 08907 L’Hospitalet de Llobregat, Barcelona, Spain
- Facultat de Medicina, Universitat de Vic-Universitat Central de Catalunya (UVic-UCC), 08500 Vic, Barcelona, Spain
| | - José M. López
- Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
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3
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Yan Y, Li M, Lin J, Ji Y, Wang K, Yan D, Shen Y, Wang W, Huang Z, Jiang H, Sun H, Qi L. Adenosine monophosphate activated protein kinase contributes to skeletal muscle health through the control of mitochondrial function. Front Pharmacol 2022; 13:947387. [PMID: 36339617 PMCID: PMC9632297 DOI: 10.3389/fphar.2022.947387] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 10/06/2022] [Indexed: 11/26/2022] Open
Abstract
Skeletal muscle is one of the largest organs in the body and the largest protein repository. Mitochondria are the main energy-producing organelles in cells and play an important role in skeletal muscle health and function. They participate in several biological processes related to skeletal muscle metabolism, growth, and regeneration. Adenosine monophosphate-activated protein kinase (AMPK) is a metabolic sensor and regulator of systemic energy balance. AMPK is involved in the control of energy metabolism by regulating many downstream targets. In this review, we propose that AMPK directly controls several facets of mitochondrial function, which in turn controls skeletal muscle metabolism and health. This review is divided into four parts. First, we summarize the properties of AMPK signal transduction and its upstream activators. Second, we discuss the role of mitochondria in myogenesis, muscle atrophy, regeneration post-injury of skeletal muscle cells. Third, we elaborate the effects of AMPK on mitochondrial biogenesis, fusion, fission and mitochondrial autophagy, and discuss how AMPK regulates the metabolism of skeletal muscle by regulating mitochondrial function. Finally, we discuss the effects of AMPK activators on muscle disease status. This review thus represents a foundation for understanding this biological process of mitochondrial dynamics regulated by AMPK in the metabolism of skeletal muscle. A better understanding of the role of AMPK on mitochondrial dynamic is essential to improve mitochondrial function, and hence promote skeletal muscle health and function.
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Affiliation(s)
- Yan Yan
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, China
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Nantong University, Nantong, China
| | - Ming Li
- Department of Laboratory Medicine, Binhai County People’s Hospital Affiliated to Kangda College of Nanjing Medical University, Yancheng, China
| | - Jie Lin
- Department of Infectious Disease, Affiliated Hospital of Nantong University, Nantong, China
| | - Yanan Ji
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Nantong University, Nantong, China
| | - Kexin Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Nantong University, Nantong, China
| | - Dajun Yan
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, China
| | - Yuntian Shen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Nantong University, Nantong, China
| | - Wei Wang
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, China
- Department of Pathology, Affiliated Hospital of Nantong University, Medical School of Nantong University, Nantong, China
| | - Zhongwei Huang
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, China
| | - Haiyan Jiang
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, China
- *Correspondence: Haiyan Jiang, ; Hualin Sun, ; Lei Qi,
| | - Hualin Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Nantong University, Nantong, China
- *Correspondence: Haiyan Jiang, ; Hualin Sun, ; Lei Qi,
| | - Lei Qi
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, China
- *Correspondence: Haiyan Jiang, ; Hualin Sun, ; Lei Qi,
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Višnjić D, Lalić H, Dembitz V, Tomić B, Smoljo T. AICAr, a Widely Used AMPK Activator with Important AMPK-Independent Effects: A Systematic Review. Cells 2021. [PMID: 34064363 DOI: 10.3390/cellsl0051095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
5-Aminoimidazole-4-carboxamide ribonucleoside (AICAr) has been one of the most commonly used pharmacological modulators of AMPK activity. The majority of early studies on the role of AMPK, both in the physiological regulation of metabolism and in cancer pathogenesis, were based solely on the use of AICAr as an AMPK-activator. Even with more complex models of AMPK downregulation and knockout being introduced, AICAr remained a regular starting point for many studies focusing on AMPK biology. However, there is an increasing number of studies showing that numerous AICAr effects, previously attributed to AMPK activation, are in fact AMPK-independent. This review aims to give an overview of the present knowledge on AMPK-dependent and AMPK-independent effects of AICAr on metabolism, hypoxia, exercise, nucleotide synthesis, and cancer, calling for caution in the interpretation of AICAr-based studies in the context of understanding AMPK signaling pathway.
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Affiliation(s)
- Dora Višnjić
- Laboratory of Cell Biology, Croatian Institute for Brain Research, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
- Department of Physiology, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
| | - Hrvoje Lalić
- Laboratory of Cell Biology, Croatian Institute for Brain Research, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
- Department of Physiology, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
| | - Vilma Dembitz
- Laboratory of Cell Biology, Croatian Institute for Brain Research, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
- Department of Physiology, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
| | - Barbara Tomić
- Laboratory of Cell Biology, Croatian Institute for Brain Research, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
- Department of Physiology, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
| | - Tomislav Smoljo
- Laboratory of Cell Biology, Croatian Institute for Brain Research, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
- Department of Physiology, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
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5
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AICAr, a Widely Used AMPK Activator with Important AMPK-Independent Effects: A Systematic Review. Cells 2021; 10:cells10051095. [PMID: 34064363 PMCID: PMC8147799 DOI: 10.3390/cells10051095] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/21/2021] [Accepted: 05/01/2021] [Indexed: 12/24/2022] Open
Abstract
5-Aminoimidazole-4-carboxamide ribonucleoside (AICAr) has been one of the most commonly used pharmacological modulators of AMPK activity. The majority of early studies on the role of AMPK, both in the physiological regulation of metabolism and in cancer pathogenesis, were based solely on the use of AICAr as an AMPK-activator. Even with more complex models of AMPK downregulation and knockout being introduced, AICAr remained a regular starting point for many studies focusing on AMPK biology. However, there is an increasing number of studies showing that numerous AICAr effects, previously attributed to AMPK activation, are in fact AMPK-independent. This review aims to give an overview of the present knowledge on AMPK-dependent and AMPK-independent effects of AICAr on metabolism, hypoxia, exercise, nucleotide synthesis, and cancer, calling for caution in the interpretation of AICAr-based studies in the context of understanding AMPK signaling pathway.
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6
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Nuwormegbe SA, Kim SW. AMPK Activation by 5-Amino-4-Imidazole Carboxamide Riboside-1-β-D-Ribofuranoside Attenuates Alkali Injury-Induced Corneal Fibrosis. Invest Ophthalmol Vis Sci 2021; 61:43. [PMID: 32561924 PMCID: PMC7415321 DOI: 10.1167/iovs.61.6.43] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Purpose Increased TGF-β1 synthesis after corneal alkali injury is implicated in corneal fibrosis, as it promotes transdifferentiation of keratocytes into myofibroblasts. The activation of 5'-adenosine monophosphate-activated protein kinase (AMPK) by 5-amino-4-imidazole carboxamide riboside-1-β-d-ribofuranoside (AICAR) inhibits TGF-β1-induced fibrosis in other cell types. We investigated the antifibrotic effect of AICAR in corneal fibroblasts after alkali injury. Methods Mouse models of corneal alkali burn, produced by placing 2-mm-diameter filter paper soaked in 0.1-N NaOH on the right cornea for 30 seconds, were treated with the test drugs 4× daily for 21 days. The central cornea was scanned by optical coherence tomography (OCT). Corneal tissues were obtained and processed for western blotting and immunohistochemistry. For in vitro analysis, primary human corneal fibroblasts were treated directly with TGF-β1 to induce fibrosis, with or without AICAR pretreatment. Myofibroblast activation and extracellular matrix (ECM) protein synthesis were detected by western blotting, real-time PCR, and collagen gel contraction assay. Signaling proteins were analyzed by western blotting. Results Alkali injury induced the upregulation of TGF-β1 expression, which led to increased α-smooth muscle actin (α-SMA) and fibronectin synthesis and myofibroblast differentiation. AMPK activation by AICAR significantly suppressed TGF-β1 and ECM protein expression. The antifibrotic effect of AICAR was AMPK dependent, as treatment with the AMPK inhibitor Compound C attenuated the antifibrotic response. Conclusions AMPK activation by AICAR suppresses the myofibroblast differentiation and ECM synthesis that occur after alkali injury in corneal fibroblasts.
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Abstract
The skeletal muscle is the largest organ in the body, by mass. It is also the regulator of glucose homeostasis, responsible for 80% of postprandial glucose uptake from the circulation. Skeletal muscle is essential for metabolism, both for its role in glucose uptake and its importance in exercise and metabolic disease. In this article, we give an overview of the importance of skeletal muscle in metabolism, describing its role in glucose uptake and the diseases that are associated with skeletal muscle metabolic dysregulation. We focus on the role of skeletal muscle in peripheral insulin resistance and the potential for skeletal muscle-targeted therapeutics to combat insulin resistance and diabetes, as well as other metabolic diseases like aging and obesity. In particular, we outline the possibilities and pitfalls of the quest for exercise mimetics, which are intended to target the molecular mechanisms underlying the beneficial effects of exercise on metabolic disease. We also provide a description of the molecular mechanisms that regulate skeletal muscle glucose uptake, including a focus on the SNARE proteins, which are essential regulators of glucose transport into the skeletal muscle. © 2020 American Physiological Society. Compr Physiol 10:785-809, 2020.
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Affiliation(s)
- Karla E. Merz
- Department of Molecular and Cellular Endocrinology, City of Hope Beckman Research Institute, Duarte, California, USA
- The Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California, USA
| | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, City of Hope Beckman Research Institute, Duarte, California, USA
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8
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Physiological levels of folic acid reveal purine alterations in Lesch-Nyhan disease. Proc Natl Acad Sci U S A 2020; 117:12071-12079. [PMID: 32430324 DOI: 10.1073/pnas.2003475117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Lesch-Nyhan disease (LND), caused by a deficient salvage purine pathway, is characterized by severe neurological manifestations and uric acid overproduction. However, uric acid is not responsible for brain dysfunction, and it has been suggested that purine nucleotide depletion, or accumulation of other toxic purine intermediates, could be more relevant. Here we show that purine alterations in LND fibroblasts depend on the level of folic acid in the culture media. Thus, physiological levels of folic acid induce accumulation of 5-aminoimidazole-4-carboxamide riboside 5'-monophosphate (ZMP), an intermediary of de novo purine biosynthetic pathway, and depletion of ATP. Additionally, Z-nucleotide derivatives (AICAr, AICA) are detected at high levels in the urine of patients with LND and its variants (hypoxanthine-guanine phosphoribosyltransferase [HGprt]-related neurological dysfunction and HGprt-related hyperuricemia), and the ratio of AICAr/AICA is significantly increased in patients with neurological problems (LND and HGprt-related neurological dysfunction). Moreover, AICAr is present in the cerebrospinal fluid of patients with LND, but not in control individuals. We hypothesize that purine alterations detected in LND fibroblasts may also occur in the brain of patients with LND.
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9
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Choi JH, Matsuzaki N, Wu J, Kotajima M, Hirai H, Kondo M, Asakawa T, Inai M, Ouchi H, Kan T, Kawagishi H. Ribosides and Ribotide of a Fairy Chemical, Imidazole-4-carboxamide, as Its Metabolites in Rice. Org Lett 2019; 21:7841-7845. [PMID: 31518147 DOI: 10.1021/acs.orglett.9b02833] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The metabolism of imidazole-4-carboxamide (ICA) in plants has been unknown. Two metabolites (1 and 2) were isolated from ICA-treated rice, and their structures were determined by spectroscopic analysis including the single-crystal X-ray diffraction technique and synthesis. The ribotide of ICA (3), whose existence was predicted, was also synthesized and detected from the treated rice by LC-MS/MS. These results indicated that rice might interconvert ICA, 1, and 3 to regulate the biological activity.
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Affiliation(s)
- Jae-Hoon Choi
- Graduate School of Integrated Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan.,Research Institute of Green Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
| | - Nobuo Matsuzaki
- Graduate School of Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
| | - Jing Wu
- Research Institute of Green Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
| | - Mihaya Kotajima
- Graduate School of Integrated Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
| | - Hirofumi Hirai
- Graduate School of Integrated Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan.,Research Institute of Green Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
| | - Mitsuru Kondo
- Research Institute of Green Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
| | - Tomohiro Asakawa
- Tokai University Institute of Innovative Science and Technology , 4-1-1 Kitakaname , Hiratsuka City , Kanagawa 259-1292 , Japan
| | - Makoto Inai
- School of Pharmaceutical Sciences , University of Shizuoka , 52-1 Yada , Suruga-ku, Shizuoka 422-8526 , Japan
| | - Hitoshi Ouchi
- School of Pharmaceutical Sciences , University of Shizuoka , 52-1 Yada , Suruga-ku, Shizuoka 422-8526 , Japan
| | - Toshiyuki Kan
- School of Pharmaceutical Sciences , University of Shizuoka , 52-1 Yada , Suruga-ku, Shizuoka 422-8526 , Japan
| | - Hirokazu Kawagishi
- Graduate School of Integrated Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan.,Research Institute of Green Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan.,Graduate School of Science and Technology , Shizuoka University , 836 Ohya , Suruga-ku, Shizuoka 422-8529 , Japan
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10
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Du L, Yang F, Fang H, Sun H, Chen Y, Xu Y, Li H, Zheng L, Zhou BBS. AICAr suppresses cell proliferation by inducing NTP and dNTP pool imbalances in acute lymphoblastic leukemia cells. FASEB J 2019; 33:4525-4537. [PMID: 30702927 DOI: 10.1096/fj.201801559rr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
It has been shown that 5-amino-4-imidazolecarboxamide riboside (AICAr) can inhibit cell proliferation and induce apoptosis in childhood acute lymphoblastic leukemia (ALL) cells. Although AICAr could regulate cellular energy metabolism by activating AMPK, the cytotoxic mechanisms of AICAr are still unclear. Here, we knocked out TP53 or PRKAA1 gene (encoding AMPKα1) in NALM-6 and Reh cells by using the clustered regularly interspaced short palindromic repeats/Cas9 system and found that AICAr-induced proliferation inhibition was independent of AMPK activation but dependent on p53. Liquid chromatography-mass spectrometry analysis of nucleotide metabolites indicated that AICAr caused an increase in adenosine triphosphate, deoxyadenosine triphosphate, and deoxyguanosine triphosphate levels by up-regulating purine biosynthesis, while AICAr led to a decrease in cytidine triphosphate, uridine triphosphate, deoxycytidine triphosphate, and deoxythymidine triphosphate levels because of reduced phosphoribosyl pyrophosphate production, which consequently impaired the pyrimidine biosynthesis. Ribonucleoside triphosphate (NTP) pool imbalances suppressed the rRNA transcription efficiency. Furthermore, deoxy-ribonucleoside triphosphate (dNTP) pool imbalances induced DNA replication stress and DNA double-strand breaks, followed by cell cycle arrest and apoptosis in ALL cells. Exogenous uridine could rebalance the NTP and dNTP pools by supplementing pyrimidine and then attenuate AICAr-induced cytotoxicity. Our data indicate that RNA transcription inhibition and DNA replication stress induced by NTP and dNTP pool imbalances might play a key role in AICAr-mediated cytotoxic effects on ALL cells, suggesting a potential clinical application of AICAr in future ALL therapy.-Du, L., Yang, F., Fang, H., Sun, H., Chen, Y., Xu, Y., Li, H., Zheng, L., Zhou, B.-B. S. AICAr suppresses cell proliferation by inducing NTP and dNTP pool imbalances in acute lymphoblastic leukemia cells.
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Affiliation(s)
- Lijuan Du
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fan Yang
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Houshun Fang
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huiying Sun
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yao Chen
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Xu
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hui Li
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Pharmacology and Chemical Biology, School of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Collaborative Innovation Center for Translational Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Liang Zheng
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bin-Bing S Zhou
- Key Laboratory of Pediatric Hematology and Oncology, Ministry of Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Pharmacology and Chemical Biology, School of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Collaborative Innovation Center for Translational Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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11
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Brooks HB, Meier TI, Geeganage S, Fales KR, Thrasher KJ, Konicek SA, Spencer CD, Thibodeaux S, Foreman RT, Hui YH, Roth KD, Qian YW, Wang T, Luo S, Torrado A, Si C, Toth JL, Mc Cowan JR, Frimpong K, Lee MR, Dally RD, Shepherd TA, Durham TB, Wang Y, Wu Z, Iversen PW, Njoroge FG. Characterization of a novel AICARFT inhibitor which potently elevates ZMP and has anti-tumor activity in murine models. Sci Rep 2018; 8:15458. [PMID: 30337562 PMCID: PMC6193938 DOI: 10.1038/s41598-018-33453-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 09/25/2018] [Indexed: 11/25/2022] Open
Abstract
AICARFT is a folate dependent catalytic site within the ATIC gene, part of the purine biosynthetic pathway, a pathway frequently upregulated in cancers. LSN3213128 is a potent (16 nM) anti-folate inhibitor of AICARFT and selective relative to TS, SHMT1, MTHFD1, MTHFD2 and MTHFD2L. Increases in ZMP, accompanied by activation of AMPK and cell growth inhibition, were observed with treatment of LY3213128. These effects on ZMP and proliferation were dependent on folate levels. In human breast MDA-MB-231met2 and lung NCI-H460 cell lines, growth inhibition was rescued by hypoxanthine, but not in the A9 murine cell line which is deficient in purine salvage. In athymic nude mice, LSN3213128 robustly elevates ZMP in MDA-MB-231met2, NCI-H460 and A9 tumors in a time and dose dependent manner. Significant tumor growth inhibition in human breast MDA-MB231met2 and lung NCI-H460 xenografts and in the syngeneic A9 tumor model were observed with oral administration of LSN3213128. Strikingly, AMPK appeared activated within the tumors and did not change even at high levels of intratumoral ZMP after weeks of dosing. These results support the evaluation of LSN3213128 as an antineoplastic agent.
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Affiliation(s)
- Harold B Brooks
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA.
| | - Timothy I Meier
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Sandaruwan Geeganage
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Kevin R Fales
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Kenneth J Thrasher
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Susan A Konicek
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Charles D Spencer
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Stefan Thibodeaux
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Robert T Foreman
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Yu-Hua Hui
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Kenneth D Roth
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Yue-Wei Qian
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Tao Wang
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Shuang Luo
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Alicia Torrado
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Chong Si
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - James L Toth
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Jefferson R Mc Cowan
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Kwame Frimpong
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Matthew R Lee
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Robert D Dally
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Timothy A Shepherd
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Timothy B Durham
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Yong Wang
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Zhipei Wu
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - Philip W Iversen
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
| | - F George Njoroge
- Eli Lilly and Company, Lilly Research Laboratories, Indianapolis, Indiana, 46285, USA
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12
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Dolinar K, Jan V, Pavlin M, Chibalin AV, Pirkmajer S. Nucleosides block AICAR-stimulated activation of AMPK in skeletal muscle and cancer cells. Am J Physiol Cell Physiol 2018; 315:C803-C817. [PMID: 30230919 DOI: 10.1152/ajpcell.00311.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
AMP-activated kinase (AMPK) is a major regulator of energy metabolism and a promising target for development of new treatments for type 2 diabetes and cancer. 5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), an adenosine analog, is a standard positive control for AMPK activation in cell-based assays. Some broadly used cell culture media, such as minimal essential medium α (MEMα), contain high concentrations of adenosine and other nucleosides. We determined whether such media alter AICAR action in skeletal muscle and cancer cells. In nucleoside-free media, AICAR stimulated AMPK activation, increased glucose uptake, and suppressed cell proliferation. Conversely, these effects were blunted or completely blocked in MEMα that contains nucleosides. Addition of adenosine or 2'-deoxyadenosine to nucleoside-free media also suppressed AICAR action. MEMα with nucleosides blocked AICAR-stimulated AMPK activation even in the presence of methotrexate, which normally markedly enhances AICAR action by reducing its intracellular clearance. Other common media components, such as vitamin B-12, vitamin C, and α-lipoic acid, had a minor modulatory effect on AICAR action. Our findings show that nucleoside-containing media, commonly used in AMPK research, block action of the most widely used pharmacological AMPK activator AICAR. Results of cell-based assays in which AICAR is used for AMPK activation therefore critically depend on media formulation. Furthermore, our findings highlight a role for extracellular nucleosides and nucleoside transporters in regulation of AMPK activation.
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Affiliation(s)
- Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia.,Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana , Ljubljana , Slovenia
| | - Vid Jan
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia
| | - Mojca Pavlin
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana , Ljubljana , Slovenia.,Institute of Biophysics, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet , Stockholm , Sweden.,National Research Tomsk State University , Tomsk , Russia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia
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13
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Philippe C, Pinson B, Dompierre J, Pantesco V, Viollet B, Daignan-Fornier B, Moenner M. AICAR Antiproliferative Properties Involve the AMPK-Independent Activation of the Tumor Suppressors LATS 1 and 2. Neoplasia 2018; 20:555-562. [PMID: 29730476 PMCID: PMC5994775 DOI: 10.1016/j.neo.2018.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/14/2018] [Accepted: 03/19/2018] [Indexed: 12/11/2022] Open
Abstract
AICAR (Acadesine) is a pharmacological precursor of purine nucleotide biosynthesis with anti-tumoral properties. Although recognized as an AMP mimetic activator of the protein kinase AMPK, the AICAR monophosphate derivative ZMP was also shown to mediate AMPK-independent effects. In order to unveil these AMPK-independent functions, we performed a transcriptomic analysis in AMPKα1/α2 double knockout murine embryonic cells. Kinetic analysis of the cellular response to AICAR revealed the up-regulation of the large tumor suppressor kinases (Lats) 1 and 2 transcripts, followed by the repression of numerous genes downstream of the transcriptional regulators Yap1 and Taz. This transcriptional signature, together with the observation of increased levels in phosphorylation of Lats1 and Yap1 proteins, suggested that the Hippo signaling pathway was activated by AICAR. This effect was observed in both fibroblasts and epithelial cells. Knockdown of Lats1/2 prevented the cytoplasmic delocalization of Yap1/Taz proteins in response to AICAR and conferred a higher resistance to the drug. These results indicate that activation of the most downstream steps of the Hippo cascade participates to the antiproliferative effects of AICAR.
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Affiliation(s)
- Chloé Philippe
- Université de Bordeaux, IBGC UMR 5095, Bordeaux, France; Centre National de la Recherche Scientifique, IBGC UMR 5095, Bordeaux, France
| | - Benoît Pinson
- Université de Bordeaux, IBGC UMR 5095, Bordeaux, France; Centre National de la Recherche Scientifique, IBGC UMR 5095, Bordeaux, France
| | - Jim Dompierre
- Université de Bordeaux, IBGC UMR 5095, Bordeaux, France; Centre National de la Recherche Scientifique, IBGC UMR 5095, Bordeaux, France
| | | | - Benoît Viollet
- INSERM U1016, Institut Cochin, Paris, France; CNRS (UMR 8104), Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Bertrand Daignan-Fornier
- Université de Bordeaux, IBGC UMR 5095, Bordeaux, France; Centre National de la Recherche Scientifique, IBGC UMR 5095, Bordeaux, France.
| | - Michel Moenner
- Université de Bordeaux, IBGC UMR 5095, Bordeaux, France; Centre National de la Recherche Scientifique, IBGC UMR 5095, Bordeaux, France.
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14
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Kjøbsted R, Wojtaszewski JFP, Treebak JT. Role of AMP-Activated Protein Kinase for Regulating Post-exercise Insulin Sensitivity. ACTA ACUST UNITED AC 2017; 107:81-126. [PMID: 27812978 DOI: 10.1007/978-3-319-43589-3_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Skeletal muscle insulin resistance precedes development of type 2 diabetes (T2D). As skeletal muscle is a major sink for glucose disposal, understanding the molecular mechanisms involved in maintaining insulin sensitivity of this tissue could potentially benefit millions of people that are diagnosed with insulin resistance. Regular physical activity in both healthy and insulin-resistant individuals is recognized as the single most effective intervention to increase whole-body insulin sensitivity and thereby positively affect glucose homeostasis. A single bout of exercise has long been known to increase glucose disposal in skeletal muscle in response to physiological insulin concentrations. While this effect is identified to be restricted to the previously exercised muscle, the molecular basis for an apparent convergence between exercise- and insulin-induced signaling pathways is incompletely known. In recent years, we and others have identified the Rab GTPase-activating protein, TBC1 domain family member 4 (TBC1D4) as a target of key protein kinases in the insulin- and exercise-activated signaling pathways. Our working hypothesis is that the AMP-activated protein kinase (AMPK) is important for the ability of exercise to insulin sensitize skeletal muscle through TBC1D4. Here, we aim to provide an overview of the current available evidence linking AMPK to post-exercise insulin sensitivity.
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Affiliation(s)
- Rasmus Kjøbsted
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark.
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15
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Liu F, Jin R, Liu X, Huang H, Wilkinson SC, Zhong D, Khuri FR, Fu H, Marcus A, He Y, Zhou W. LKB1 promotes cell survival by modulating TIF-IA-mediated pre-ribosomal RNA synthesis under uridine downregulated conditions. Oncotarget 2016; 7:2519-31. [PMID: 26506235 PMCID: PMC4823052 DOI: 10.18632/oncotarget.6224] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 10/09/2015] [Indexed: 11/29/2022] Open
Abstract
We analyzed the mechanism underlying 5-aminoimidazole-4-carboxamide riboside (AICAR) mediated apoptosis in LKB1-null non-small cell lung cancer (NSCLC) cells. Metabolic profile analysis revealed depletion of the intracellular pyrimidine pool after AICAR treatment, but uridine was the only nucleotide precursor capable of rescuing this apoptosis, suggesting the involvement of RNA metabolism. Because half of RNA transcription in cancer is for pre-ribosomal RNA (rRNA) synthesis, which is suppressed by over 90% after AICAR treatment, we evaluated the role of TIF-IA-mediated rRNA synthesis. While the depletion of TIF-IA by RNAi alone promoted apoptosis in LKB1-null cells, the overexpression of a wild-type or a S636A TIF-IA mutant, but not a S636D mutant, attenuated AICAR-induced apoptosis. In LKB1-null H157 cells, pre-rRNA synthesis was not suppressed by AICAR when wild-type LKB1 was present, and cellular fractionation analysis indicated that TIF-IA quickly accumulated in the nucleus in the presence of a wild-type LKB1 but not a kinase-dead mutant. Furthermore, ectopic expression of LKB1 was capable of attenuating AICAR-induced death in AMPK-null cells. Because LKB1 promotes cell survival by modulating TIF-IA-mediated pre-rRNA synthesis, this discovery suggested that targeted depletion of uridine related metabolites may be exploited in the clinic to eliminate LKB1-null cancer cells.
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Affiliation(s)
- Fakeng Liu
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA.,Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, P.R. China
| | - Rui Jin
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Xiuju Liu
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Henry Huang
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Scott C Wilkinson
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA.,Graduate Program in Cancer Biology, Emory University, Atlanta, GA, USA
| | - Diansheng Zhong
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA.,Department of Medical Oncology, Tianjin Medical University General Hospital, Tianjin, P.R.China
| | - Fadlo R Khuri
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Haian Fu
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Adam Marcus
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Yulong He
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, P.R. China
| | - Wei Zhou
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA.,Department of Pathology and Laboratory Medicine and Department of Human Genetics Emory University School of Medicine, Atlanta, GA, USA
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16
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Human Choline Kinase-α Promotes Hepatitis C Virus RNA Replication through Modulation of Membranous Viral Replication Complex Formation. J Virol 2016; 90:9075-95. [PMID: 27489281 PMCID: PMC5044849 DOI: 10.1128/jvi.00960-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/20/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) infection reorganizes cellular membranes to create an active viral replication site named the membranous web (MW). The role that human choline kinase-α (hCKα) plays in HCV replication remains elusive. Here, we first showed that hCKα activity, not the CDP-choline pathway, promoted viral RNA replication. Confocal microscopy and subcellular fractionation of HCV-infected cells revealed that a small fraction of hCKα colocalized with the viral replication complex (RC) on the endoplasmic reticulum (ER) and that HCV infection increased hCKα localization to the ER. In the pTM-NS3-NS5B model, NS3-NS5B expression increased the localization of the wild-type, not the inactive D288A mutant, hCKα on the ER, and hCKα activity was required for effective trafficking of hCKα and NS5A to the ER. Coimmunoprecipitation showed that hCKα was recruited onto the viral RC presumably through its binding to NS5A domain 1 (D1). hCKα silencing or treatment with CK37, an hCKα activity inhibitor, abolished HCV-induced MW formation. In addition, hCKα depletion hindered NS5A localization on the ER, interfered with NS5A and NS5B colocalization, and mitigated NS5A-NS5B interactions but had no apparent effect on NS5A-NS4B and NS4B-NS5B interactions. Nevertheless, hCKα activity was not essential for the binding of NS5A to hCKα or NS5B. These findings demonstrate that hCKα forms a complex with NS5A and that hCKα activity enhances the targeting of the complex to the ER, where hCKα protein, not activity, mediates NS5A binding to NS5B, thereby promoting functional membranous viral RC assembly and viral RNA replication. IMPORTANCE HCV infection reorganizes the cellular membrane to create an active viral replication site named the membranous web (MW). Here, we report that human choline kinase-α (hCKα) acts as an essential host factor for HCV RNA replication. A fraction of hCKα colocalizes with the viral replication complex (RC) on the endoplasmic reticulum (ER) in HCV-infected cells. NS3-NS5B expression increases ER localization of wild-type, but not D288A mutant, hCKα, and hCKα activity facilitates the transport of itself and NS5A to the ER. Silencing or inactivation of hCKα abrogates MW formation. Moreover, hCKα is recruited by NS5A independent of hCKα activity, presumably through binding to NS5A D1. hCKα activity then mediates the ER targeting of the hCKα-NS5A complex. On the ER membrane, hCKα protein, per se, induces NS5A binding to NS5B, thereby promoting membranous RC formation and viral RNA replication. Our study may benefit the development of hCKα-targeted anti-HCV therapeutics.
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17
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Jin R, Zhou W. TIF-IA: An oncogenic target of pre-ribosomal RNA synthesis. Biochim Biophys Acta Rev Cancer 2016; 1866:189-196. [PMID: 27641688 DOI: 10.1016/j.bbcan.2016.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 09/13/2016] [Accepted: 09/14/2016] [Indexed: 12/30/2022]
Abstract
Cancer cells devote the majority of their energy consumption to ribosome biogenesis, and pre-ribosomal RNA transcription accounts for 30-50% of all transcriptional activity. This aberrantly elevated biological activity is an attractive target for cancer therapeutic intervention if approaches can be developed to circumvent the development of side effects in normal cells. TIF-IA is a transcription factor that connects RNA polymerase I with the UBF/SL-1 complex to initiate the transcription of pre-ribosomal RNA. Its function is conserved in eukaryotes from yeast to mammals, and its activity is promoted by the phosphorylation of various oncogenic kinases in cancer cells. The depletion of TIF-IA induces cell death in lung cancer cells and mouse embryonic fibroblasts but not in several other normal tissue types evaluated in knock-out studies. Furthermore, the nuclear accumulation of TIF-IA under UTP down-regulated conditions requires the activity of LKB1 kinase, and LKB1-inactivated cancer cells are susceptible to cell death under such stress conditions. Therefore, TIF-IA may be a unique target to suppress ribosome biogenesis without significantly impacting the survival of normal tissues.
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Affiliation(s)
- Rui Jin
- Department of Hematology and Medical Oncology, The Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA
| | - Wei Zhou
- Department of Hematology and Medical Oncology, The Winship Cancer Institute of Emory University, Atlanta, GA 30322, USA; Department of Pathology and Laboratory Medicine and Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA.
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18
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Small-molecule activators of AMP-activated protein kinase as modulators of energy metabolism. Russ Chem Bull 2016. [DOI: 10.1007/s11172-015-1036-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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19
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Miglianico M, Nicolaes GAF, Neumann D. Pharmacological Targeting of AMP-Activated Protein Kinase and Opportunities for Computer-Aided Drug Design. J Med Chem 2015; 59:2879-93. [PMID: 26510622 DOI: 10.1021/acs.jmedchem.5b01201] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
As a central regulator of metabolism, the AMP-activated protein kinase (AMPK) is an established therapeutic target for metabolic diseases. Beyond the metabolic area, the number of medical fields that involve AMPK grows continuously, expanding the potential applications for AMPK modulators. Even though indirect AMPK activators are used in the clinics for their beneficial metabolic outcome, the few described direct agonists all failed to reach the market to date, which leaves options open for novel targeting methods. As AMPK is not actually a single molecule and has different roles depending on its isoform composition, the opportunity for isoform-specific targeting has notably come forward, but the currently available modulators fall short of expectations. In this review, we argue that with the amount of available structural and ligand data, computer-based drug design offers a number of opportunities to undertake novel and isoform-specific targeting of AMPK.
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Affiliation(s)
- Marie Miglianico
- Department of Molecular Genetics, and ‡Department of Biochemistry, CARIM School for Cardiovascular Diseases, Maastricht University , NL-6200 MD, Maastricht, The Netherlands
| | - Gerry A F Nicolaes
- Department of Molecular Genetics, and ‡Department of Biochemistry, CARIM School for Cardiovascular Diseases, Maastricht University , NL-6200 MD, Maastricht, The Netherlands
| | - Dietbert Neumann
- Department of Molecular Genetics, and ‡Department of Biochemistry, CARIM School for Cardiovascular Diseases, Maastricht University , NL-6200 MD, Maastricht, The Netherlands
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20
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ElAzzouny MA, Evans CR, Burant CF, Kennedy RT. Metabolomics Analysis Reveals that AICAR Affects Glycerolipid, Ceramide and Nucleotide Synthesis Pathways in INS-1 Cells. PLoS One 2015; 10:e0129029. [PMID: 26107620 PMCID: PMC4480354 DOI: 10.1371/journal.pone.0129029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 05/03/2015] [Indexed: 12/31/2022] Open
Abstract
AMPK regulates many metabolic pathways including fatty acid and glucose metabolism, both of which are closely associated with insulin secretion in pancreatic β-cells. Insulin secretion is regulated by metabolic coupling factors such as ATP/ADP ratio and other metabolites generated by the metabolism of nutrients such as glucose, fatty acid and amino acids. However, the connection between AMPK activation and insulin secretion in β-cells has not yet been fully elucidated at a metabolic level. To study the effect of AMPK activation on glucose stimulated insulin secretion, we applied the pharmacological activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) to an INS-1 (832/13) β-cell line. We measured the change in 66 metabolites in the presence or absence of AICAR using different stable isotopic labeled nutrients to probe selected pathways. AMPK activation by AICAR increased basal insulin secretion and reduced the glucose stimulation index. Although ATP/ADP ratios were not strongly affected by AICAR, several other metabolites and pathways important for insulin secretion were affected by AICAR treatment including long-chain CoAs, malonyl-CoA, 3-hydroxy-3 methylglutaryl CoA, diacylglycerol, and farnesyl pyrophosphate. Tracer studies using 13C-glucose revealed lower glucose flux in the purine and pyrimidine pathway and in the glycerolipid synthesis pathway. Untargeted metabolomics revealed reduction in ceramides caused by AICAR that may explain the beneficial role of AMPK in protecting β-cells from lipotoxicity. Taken together, the results provide an overall picture of the metabolic changes associated with AICAR treatment and how it modulates insulin secretion and β-cell survival.
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Affiliation(s)
- Mahmoud A. ElAzzouny
- The Department of Chemistry, University of Michigan, Ann Arbor, United States of America
- The Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Charles R. Evans
- The Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Charles F Burant
- The Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Robert T. Kennedy
- The Department of Chemistry, University of Michigan, Ann Arbor, United States of America
- The Department of Pharmacology, University of Michigan, Ann Arbor, United States of America
- * E-mail:
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21
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Kim PB, Nelson JW, Breaker RR. An ancient riboswitch class in bacteria regulates purine biosynthesis and one-carbon metabolism. Mol Cell 2015; 57:317-28. [PMID: 25616067 DOI: 10.1016/j.molcel.2015.01.001] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 10/23/2014] [Accepted: 12/29/2014] [Indexed: 12/13/2022]
Abstract
Over 30 years ago, ZTP (5-aminoimidazole-4-carboxamide riboside 5'-triphosphate), a modified purine biosynthetic intermediate, was proposed to signal 10-formyl-tetrahydrofolate (10f-THF) deficiency in bacteria. However, the mechanisms by which this putative alarmone or its precursor ZMP (5-aminoimidazole-4-carboxamide ribonucleotide, also known as AICAR) brings about any metabolic changes remain unexplained. Herein, we report the existence of a widespread riboswitch class that is most commonly associated with genes related to de novo purine biosynthesis and one-carbon metabolism. Biochemical data confirm that members of this riboswitch class selectively bind ZMP and ZTP with nanomolar affinity while strongly rejecting numerous natural analogs. Indeed, increases in the ZMP/ZTP pool, caused by folate stress in bacterial cells, trigger changes in the expression of a reporter gene fused to representative ZTP riboswitches in vivo. The wide distribution of this riboswitch class suggests that ZMP/ZTP signaling is important for species in numerous bacterial lineages.
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Affiliation(s)
- Peter B Kim
- Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - James W Nelson
- Department of Chemistry, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA; Department of Molecular Biophysics and Biochemistry, Yale University, Box 208103, New Haven, CT 06520-8103, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA.
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Wi SM, Lee KY. 5-aminoimidazole-4-carboxamide Riboside Induces Apoptosis Through AMP-activated Protein Kinase-independent and NADPH Oxidase-dependent Pathways. Immune Netw 2014; 14:241-8. [PMID: 25360075 PMCID: PMC4212085 DOI: 10.4110/in.2014.14.5.241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 09/15/2014] [Accepted: 09/22/2014] [Indexed: 12/01/2022] Open
Abstract
It is debatable whether AMP-activated protein kinase (AMPK) activation is involved in anti-apoptotic or pro-apoptotic signaling. AICAR treatment increases AMPK-α1 phosphorylation, decreases intracellular reactive oxygen species (ROS) levels, and significantly increases Annexin V-positive cells, DNA laddering, and caspase activity in human myeloid cell. AMPK activation is therefore implicated in apoptosis. However, AMPK-α1-knockdown THP-1 cells are more sensitive to apoptosis than control THP-1 cells are, suggesting that the apoptosis is AMPK-independent. Low doses of AICAR induce cell proliferation, whereas high doses of AICAR suppress cell proliferation. Moreover, these effects are significantly correlated with the downregulation of intracellular ROS, strongly suggesting that AICAR-induced apoptosis is critically associated with the inhibition of NADPH oxidase by AICAR. Collectively, our results demonstrate that in AICAR-induced apoptosis, intracellular ROS levels are far more relevant than AMPK activation.
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Affiliation(s)
- Sae Mi Wi
- Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
| | - Ki-Young Lee
- Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
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Chen KH, Hsu HH, Lee CC, Yen TH, Ko YC, Yang CW, Hung CC. The AMPK agonist AICAR inhibits TGF-β1 induced activation of kidney myofibroblasts. PLoS One 2014; 9:e106554. [PMID: 25188319 PMCID: PMC4154690 DOI: 10.1371/journal.pone.0106554] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 08/08/2014] [Indexed: 01/07/2023] Open
Abstract
Activation of interstitial myofibroblasts and excessive production of extracellular matrix proteins are common pathways that contribute to chronic kidney disease. In a number of tissues, AMP-activated kinase (AMPK) activation has been shown to inhibit fibrosis. Here, we examined the inhibitory effect of the AMPK activator, 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR), on renal fibrosis invivo and TGF-β1-induced renal fibroblasts activation invitro. A unilateral ureteral obstruction (UUO) model was induced in male BALB/c mice. Mice with UUO were administered AICAR (500 mg/Kg/day) or saline intraperitoneally 1 day before UUO surgery and daily thereafter. Both kidneys were harvested 7 days after surgery for further analysis. For the in vitro studies, NRK-49F rat fibroblasts were pre-incubated with AICAR before TGF-β1 stimulation. The inhibitory effects of AICAR on signaling pathways down-stream of TGF-β1 were analyzed. In UUO model mice, administration of AICAR attenuated extracellular matrix protein deposition and the expression of α-smooth muscle actin (α-SMA), type I collagen and fibronectin. Pre-incubation of NRK-49F cells with AICAR inhibited TGF-β1-induced myofibroblast activation. Silencing of AMPKα1 by siRNA or by blocking AMPK activation with Compound C diminished the inhibitory effect of AICAR. Moreover, the inhibitory effects of AICAR on TGF-β1-mediated myofibroblast activation were associated with down-regulation of ERK 1/2 and STAT3. Our results suggest that AICAR reduces tubulointerstitial fibrosis in UUO mice and inhibits TGF-β1-induced kidney myofibroblast activation. AMPK activation by AICAR may have therapeutic potential for the treatment of renal tubulointerstitial fibrosis.
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Affiliation(s)
- Kuan-Hsing Chen
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
| | - Hsiang-Hao Hsu
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
| | - Cheng-Chia Lee
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
| | - Tzu-Hai Yen
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
| | - Yi-Ching Ko
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
| | - Chih-Wei Yang
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
| | - Cheng-Chieh Hung
- Kidney Research Center, Chang Gung Memorial Hospital, Chang Gung University, School of Medicine, Taoyuan, Taiwan
- * E-mail:
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24
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Rana S, Blowers EC, Natarajan A. Small molecule adenosine 5'-monophosphate activated protein kinase (AMPK) modulators and human diseases. J Med Chem 2014; 58:2-29. [PMID: 25122135 DOI: 10.1021/jm401994c] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Adenosine 5'-monophosphate activated protein kinase (AMPK) is a master sensor of cellular energy status that plays a key role in the regulation of whole-body energy homeostasis. AMPK is a serine/threonine kinase that is activated by upstream kinases LKB1, CaMKKβ, and Tak1, among others. AMPK exists as αβγ trimeric complexes that are allosterically regulated by AMP, ADP, and ATP. Dysregulation of AMPK has been implicated in a number of metabolic diseases including type 2 diabetes mellitus and obesity. Recent studies have associated roles of AMPK with the development of cancer and neurological disorders, making it a potential therapeutic target to treat human diseases. This review focuses on the structure and function of AMPK, its role in human diseases, and its direct substrates and provides a brief synopsis of key AMPK modulators and their relevance in human diseases.
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Affiliation(s)
- Sandeep Rana
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
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25
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Ceschin J, Saint-Marc C, Laporte J, Labriet A, Philippe C, Moenner M, Daignan-Fornier B, Pinson B. Identification of yeast and human 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAr) transporters. J Biol Chem 2014; 289:16844-54. [PMID: 24778186 DOI: 10.1074/jbc.m114.551192] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAr) is the precursor of the active monophosphate form (AICAR), a small molecule with potent anti-proliferative and low energy mimetic properties. The molecular bases for AICAR toxicity at the cellular level are poorly understood. Here, we report the isolation and characterization of several yeast AICAr-hypersensitive mutants. Identification of the cognate genes allowed us to establish that thiamine transporters Thi7 and Thi72 can efficiently take up AICAr under conditions where they are overexpressed. We establish that, under standard growth conditions, Nrt1, the nicotinamide riboside carrier, is the major AICAr transporter in yeast. A study of AICAR accumulation in human cells revealed substantial disparities among cell lines and confirmed that AICAr enters cells via purine nucleoside transporters. Together, our results point to significant differences between yeast and human cells for both AICAr uptake and AICAR accumulation.
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Affiliation(s)
- Johanna Ceschin
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Christelle Saint-Marc
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Jean Laporte
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Adrien Labriet
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Chloé Philippe
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Michel Moenner
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Bertrand Daignan-Fornier
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Benoît Pinson
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
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26
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MondoA senses adenine nucleotides: transcriptional induction of thioredoxin-interacting protein. Biochem J 2013; 453:209-18. [PMID: 23631812 DOI: 10.1042/bj20121126] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The MondoA-Mlx transcription complex plays a pivotal role in glucose homoeostasis by activating target gene expression in response to G6P (glucose 6-phosphate), the first reaction intermediate in glycolysis. TXNIP (thioredoxin-interacting protein) is a direct and glucose-responsive target of MondoA that triggers a negative-feedback loop by restricting glucose uptake when G6P levels increase. We show in the present study that TXNIP expression is also activated by AICAR (5-amino-4-imidazolecarboxamide ribofuranoside) and adenosine. Using pharmacological inhibitors and genetic knockdowns of purine metabolic enzymes, we establish that TXNIP induction by AICAR and adenosine requires their cellular uptake and metabolism to adenine nucleotides. AICAR induction of TXNIP depended on MondoA, but was independent of AMPK (AMP-activated protein kinase) activation and calcium. The findings of the present study have two important implications. First, in addition to activating AMPK, AICAR may have AMPK-independent effects on gene expression by regulating MondoA-Mlx activity following its flux into the adenine nucleotide pool. Secondly, MondoA-Mlx complexes sense elevated levels of G6P and adenine nucleotides to trigger a TXNIP-dependent feedback inhibition of glycolysis. We propose that this mechanism serves as a checkpoint to restore metabolic homoeostasis.
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O'Neill HM, Holloway GP, Steinberg GR. AMPK regulation of fatty acid metabolism and mitochondrial biogenesis: implications for obesity. Mol Cell Endocrinol 2013; 366:135-51. [PMID: 22750049 DOI: 10.1016/j.mce.2012.06.019] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 03/13/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
Abstract
Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a major site for glucose and lipid oxidation. Obesity and type 2 diabetes are causally linked through their association with skeletal muscle insulin resistance, while conversely exercise is known to improve whole body glucose homeostasis simultaneously with muscle insulin sensitivity. Exercise activates skeletal muscle AMP-activated protein kinase (AMPK). AMPK plays a role in regulating exercise capacity, skeletal muscle mitochondrial content and contraction-stimulated glucose uptake. Skeletal muscle AMPK is also thought to be important for regulating fatty acid metabolism; however, direct genetic evidence in this area is currently lacking. This review will discuss the current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise, and highlight the potential implications in the development of insulin resistance.
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Affiliation(s)
- Hayley M O'Neill
- University of Melbourne, Department of Medicine, St. Vincent's Institute of Medical Research, Melbourne, Victoria, Australia.
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Anilkumar U, Weisová P, Düssmann H, Concannon CG, König HG, Prehn JHM. AMP-activated protein kinase (AMPK)-induced preconditioning in primary cortical neurons involves activation of MCL-1. J Neurochem 2012. [PMID: 23199202 DOI: 10.1111/jnc.12108] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neuronal preconditioning is a phenomenon where a previous exposure to a sub-lethal stress stimulus increases the resistance of neurons towards a second, normally lethal stress stimulus. Activation of the energy stress sensor, AMP-activated protein kinase (AMPK) has been shown to contribute to the protective effects of ischaemic and mitochondrial uncoupling-induced preconditioning in neurons, however, the molecular basis of AMPK-mediated preconditioning has been less well characterized. We investigated the effect of AMPK preconditioning using 5-aminoimidazole-4-carboxamide riboside (AICAR) in a model of NMDA-mediated excitotoxic injury in primary mouse cortical neurons. Activation of AMPK with low concentrations of AICAR (0.1 mM for 2 h) induced a transient increase in AMPK phosphorylation, protecting neurons against NMDA-induced excitotoxicity. Analysing potential targets of AMPK activation, demonstrated a marked increase in mRNA expression and protein levels of the anti-apoptotic BCL-2 family protein myeloid cell leukaemia sequence 1 (MCL-1) in AICAR-preconditioned neurons. Interestingly, over-expression of MCL-1 protected neurons against NMDA-induced excitotoxicity while MCL-1 gene silencing abolished the effect of AICAR preconditioning. Monitored intracellular Ca²⁺ levels during NMDA excitation revealed that MCL-1 over-expressing neurons exhibited improved bioenergetics and markedly reduced Ca²⁺ elevations, suggesting a potential mechanism through which MCL-1 confers neuroprotection. This study identifies MCL-1 as a key effector of AMPK-induced preconditioning in neurons.
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Affiliation(s)
- Ujval Anilkumar
- Department of Physiology and Medical Physics, Centre for the Study of Neurological Disorders, Royal College of Surgeons in Ireland, Dublin, Ireland
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AICAR, a small chemical molecule, primes osteogenic differentiation of adult mesenchymal stem cells. Int J Artif Organs 2012; 34:1128-36. [PMID: 22198598 DOI: 10.5301/ijao.5000007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2011] [Indexed: 12/14/2022]
Abstract
The chemical approach to controlling stem cell fates is emerging as a powerful tool, holding great promise in tissue engineering and regenerative medicine. Various small molecules have been demonstrated capable of modulating stem cell differentiation. In this paper, we studied the effects of 5-aminoimidazole-4-carboxamide-1-ß-riboside (AICAR), an activator of AMP-activated protein kinase (AMPK), on mesenchymal stem cells (MSCs). AICAR at high concentrations (1.0-2.0 mM) significantly inhibited proliferation of both human amnion-derived MSCs (hAMSCs) and rabbit bone marrow-derived MSCs (BM-MSCs). Most importantly, AICAR efficiently promoted the osteogenic differentiation of hAMSCs and BM-MSCs in both growth medium and osteogenic medium. However, Metformin, another AMPK activator, showed no such effects. Meanwhile, AICAR significantly inhibited adipogenic differentiation of hAMSCs and BM-MSCs. Our data suggests that AICAR represents a potent molecule, which can be applied in bone tissue regeneration.
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30
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5-Aminoimidazole-4-carboxamide-1-beta-D-ribofuranosyl 5'-Monophosphate (AICAR), a Highly Conserved Purine Intermediate with Multiple Effects. Metabolites 2012; 2:292-302. [PMID: 24957512 PMCID: PMC3901205 DOI: 10.3390/metabo2020292] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 03/15/2012] [Accepted: 03/16/2012] [Indexed: 12/25/2022] Open
Abstract
AICAR (5-Aminoimidazole-4-carboxamide-1-beta-D-ribofuranosyl 5'-monophosphate) is a natural metabolic intermediate of purine biosynthesis that is present in all organisms. In yeast, AICAR plays important regulatory roles under physiological conditions, notably through its direct interactions with transcription factors. In humans, AICAR accumulates in several metabolic diseases, but its contribution to the symptoms has not yet been elucidated. Further, AICAR has highly promising properties which have been recently revealed. Indeed, it enhances endurance of sedentary mice. In addition, it has antiproliferative effects notably by specifically inducing apoptosis of aneuploid cells. Some of the effects of AICAR are due to its ability to stimulate the AMP-activated protein kinase but some others are not. It is consequently clear that AICAR affects multiple targets although only few of them have been identified so far. This review proposes an overview of the field and suggests future directions.
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Langelueddecke C, Jakab M, Ketterl N, Lehner L, Hufnagl C, Schmidt S, Geibel JP, Fuerst J, Ritter M. Effect of the AMP-kinase modulators AICAR, metformin and compound C on insulin secretion of INS-1E rat insulinoma cells under standard cell culture conditions. Cell Physiol Biochem 2012; 29:75-86. [PMID: 22415077 DOI: 10.1159/000337589] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS The function of β-cells is regulated by nutrient uptake and metabolism. The cells' metabolic state can be expressed as concentration ratios of AMP, ADP and ATP. Relative changes in these ratios regulate insulin release. An increase in the intracellular ATP concentration causes closure of K(ATP) channels and cell membrane depolarization, which triggers stimulus-secretion coupling (SSC). In addition to K(ATP) channels, the AMP-dependent protein kinase (AMPK), a major cellular fuel sensor in a variety of cells and tissues, also affects insulin secretion and β-cell survival. In a previous study we found that the widely used AMPK inhibitor compound C retards proliferation and induces apoptosis in the rat β-cell line INS-1E. We therefore tested the effects of AMPK activators (AICAR and metformin), and compound C on AMPK phosphorylation, insulin secretion, K(ATP) channel currents, cell membrane potential, intracellular calcium concentration, apoptosis and cell cycle distribution of INS-1E cells under standard cell culture conditions (11 mM glucose). METHODS Western blotting, ELISA, patch-clamp, calcium imaging and flow cytometry. RESULTS We found that basal AMPK phosphorylation is enhanced by AICAR (1 mM) and metformin (1 mM) but remained unaffected by compound C (10 μM). Both AICAR and compound C stimulated basal insulin secretion whereas metformin had no effect. Pre-incubation with AICAR (1 mM) caused an inhibition of K(ATP) currents but did not significantly alter the average cell membrane potential (Vm) or the threshold potential of electrical activity. Acute administration of AICAR (300 μM) led to a depolarization of Vm, which was not due to an inhibition of the basal- or glucose-induced chloride conductance, and was not accompanied by elevations of intracellular calcium (Ca(i)). AICAR had no additive blocking effect on K(ATP) currents when applied together with tolbutamide. Compound C applied over 24 hours induced an increase in the percentage of cells positive for caspase activity, whereas AICAR (1 mM) applied for 48 hours was without effect. Medium glucose concentration <3 mM caused cell cycle arrest, caspase activation and an increase of cell granularity. CONCLUSION We conclude that under standard cell culture conditions the AMPK modulators AICAR and compound C, but not metformin, stimulate insulin secretion by AMPK-independent mechanisms.
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Magnoni LJ, Vraskou Y, Palstra AP, Planas JV. AMP-activated protein kinase plays an important evolutionary conserved role in the regulation of glucose metabolism in fish skeletal muscle cells. PLoS One 2012; 7:e31219. [PMID: 22359576 PMCID: PMC3281052 DOI: 10.1371/journal.pone.0031219] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 01/04/2012] [Indexed: 12/16/2022] Open
Abstract
AMPK, a master metabolic switch, mediates the observed increase of glucose uptake in locomotory muscle of mammals during exercise. AMPK is activated by changes in the intracellular AMP:ATP ratio when ATP consumption is stimulated by contractile activity but also by AICAR and metformin, compounds that increase glucose transport in mammalian muscle cells. However, the possible role of AMPK in the regulation of glucose metabolism in skeletal muscle has not been investigated in other vertebrates, including fish. In this study, we investigated the effects of AMPK activators on glucose uptake, AMPK activity, cell surface levels of trout GLUT4 and expression of GLUT1 and GLUT4 as well as the expression of enzymes regulating glucose disposal and PGC1α in trout myotubes derived from a primary muscle cell culture. We show that AICAR and metformin significantly stimulated glucose uptake (1.6 and 1.3 fold, respectively) and that Compound C completely abrogated the stimulatory effects of the AMPK activators on glucose uptake. The combination of insulin and AMPK activators did not result in additive nor synergistic effects on glucose uptake. Moreover, exposure of trout myotubes to AICAR and metformin resulted in an increase in AMPK activity (3.8 and 3 fold, respectively). We also provide evidence suggesting that stimulation of glucose uptake by AMPK activators in trout myotubes may take place, at least in part, by increasing the cell surface and mRNA levels of trout GLUT4. Finally, AICAR increased the mRNA levels of genes involved in glucose disposal (hexokinase, 6-phosphofructokinase, pyruvate kinase and citrate synthase) and mitochondrial biogenesis (PGC-1α) and did not affect glycogen content or glycogen synthase mRNA levels in trout myotubes. Therefore, we provide evidence, for the first time in non-mammalian vertebrates, suggesting a potentially important role of AMPK in stimulating glucose uptake and utilization in the skeletal muscle of fish.
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Affiliation(s)
- Leonardo J. Magnoni
- Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona I Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain
| | - Yoryia Vraskou
- Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona I Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain
| | - Arjan P. Palstra
- Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona I Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain
| | - Josep V. Planas
- Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona I Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain
- * E-mail:
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Wu L, Huang XJ, Yang CH, Deng SS, Qian M, Zang Y, Li J. 5'-AMP-activated protein kinase (AMPK) regulates progesterone receptor transcriptional activity in breast cancer cells. Biochem Biophys Res Commun 2011; 416:172-7. [PMID: 22093824 DOI: 10.1016/j.bbrc.2011.11.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 11/04/2011] [Indexed: 10/15/2022]
Abstract
The steroid hormone progesterone is an essential regulator of the cellular processes that are required for the development and maintenance of reproductive function. The diverse effects of progesterone are mediated by the progesterone receptor (PR). The functions of the PR are regulated not only by ligands but also by modulators of various cell signaling pathways. However, it is not clear which energy state regulates PR activity. AMP-activated protein kinase (AMPK), a serine/threonine protein kinase, is a key modulator of energy homeostasis. Once activated by an increasing cellular AMP:ATP ratio, AMPK switches off ATP-consuming processes and switches on ATP-producing processes. We found that both 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR) and metformin, traditional pharmacological activators of AMPK, inhibited the PR pathway, as evidenced by progesterone response element (PRE)-driven luciferase activity and PR target gene expression. Compound C, an inhibitor of AMPK, partly but significantly reversed the anti-PR effects of AICAR and metformin. The downregulation of endogenous AMPK by small interfering RNAs (siRNAs) stimulated PR activity. AMPK activation by AICAR decreased the progesterone-induced phosphorylation of PR at serine 294 and inhibited the recruitment of PR to an endogenous PRE. Taken together, our data suggest that AMPK, an energy sensor, is involved in the regulation of PR signaling.
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Affiliation(s)
- Li Wu
- School of Life Sciences, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
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Isebaert SF, Swinnen JV, McBride WH, Begg AC, Haustermans KM. 5-aminoimidazole-4-carboxamide riboside enhances effect of ionizing radiation in PC3 prostate cancer cells. Int J Radiat Oncol Biol Phys 2011; 81:1515-23. [PMID: 21944462 DOI: 10.1016/j.ijrobp.2011.06.1964] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 06/06/2011] [Accepted: 06/07/2011] [Indexed: 02/04/2023]
Abstract
PURPOSE The nucleoside 5-aminoimidazole-4-carboxamide riboside (AICAR) is a low-energy mimetic and adenosine monophosphate (AMP)-activated protein kinase (AMPK) agonist that can affect the phenotype of malignant cells by diminishing their anabolism. It does this by being converted to 5-aminoimidazole-4-carboxamide ribotide (ZMP), an AMP analog. We combined this promising antineoplastic agent with ionizing radiation in an attempt to increase its efficacy. METHODS AND MATERIALS The effect of AICAR on cell proliferation, cell viability, apoptosis, reactive oxygen species production, radiosensitivity, and AMPK activation was determined in the human prostate cancer cell line PC3. To elucidate the radiosensitizing mechanism, clonogenic survival assays in the presence of a drug agonist or antagonist or with small interfering RNA targeting AMPK were done, as well as measurements of ZMP production and double strand break repair. Moreover, immunoblot analysis of the radiation response signaling pathways after AICAR treatment was performed. RESULTS The incubation of human PC3 prostate cancer cells with AICAR-activated AMPK inhibited cell proliferation, decreased viability, increased apoptosis, and generated reactive oxygen species in a dose- and time-dependent manner. None of these endpoints gave more than additive effects when radiation was added. Radiosensitization was observed but only after 72 hours of treatment with 250 μM AICAR, suggesting that it was independent of AMPK activation. This finding was confirmed by small interfering RNA knockdown of AMPK. The mechanism of radiosensitization was associated with imbalanced deoxynucleotide pools owing to ZMP accumulation after AICAR administration that interfered with DNA repair. CONCLUSIONS Our findings on the favorable interaction between low doses of AICAR and ionizing radiation in PC3 cells could open new perspectives for the clinical use of this or similar compounds. However, additional research is still required to establish the ZMP pathway as being of general applicability.
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Affiliation(s)
- Sofie F Isebaert
- Department of Radiation Oncology, University Hospitals Leuven Campus Gasthuisberg, and Department of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium.
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Cieslik KA, Trial J, Entman ML. Defective myofibroblast formation from mesenchymal stem cells in the aging murine heart rescue by activation of the AMPK pathway. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:1792-806. [PMID: 21819956 DOI: 10.1016/j.ajpath.2011.06.022] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 06/16/2011] [Accepted: 06/21/2011] [Indexed: 11/18/2022]
Abstract
Aged mice in a murine model of myocardial infarction exhibit less effective myocardial repair. We hypothesized that the deficiency arises from altered lineage choice of endogenous mesenchymal stem cells (MSCs) and faulty maturation of myofibroblasts. Examination of cardiac MSCs revealed a substantial reduction in the pluripotency marker Nanog in cells from aged mice. In addition, the aged MSCs demonstrated a redirected lineage choice that favored adipocytic commitment over fibroblast or myofibroblast differentiation. Fibroblasts derived from aged MSCs demonstrated reduced expression of transforming growth factor-β (TGF-β) receptors I and II and diminished SMAD3 phosphorylation, associated with attenuated contractility and migration. Overexpression of constitutively active TGF-β receptor I in aged cardiac fibroblasts ameliorated their defective motility but did not improve their contractility. Culturing of MSCs and fibroblasts with AICAR (5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside) to activate adenosine monophosphate-activated kinase resulted in TGF-β-dependent development of myofibroblasts with markedly enhanced contractility despite no reduction in adipocytic commitment or increased expression of TGF-β receptors and SMAD3 phosphorylation. The data suggest an adenosine monophosphate-activated kinase-dependent gain of function as mediated by phosphorylation of TGF-β-activated kinase 1 and p38 mitogen-activated protein kinase, which amplifies the response to TGF-β1 via a non-canonical pathway, thus compensating for the reduced expression of TGF-β receptors.
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Affiliation(s)
- Katarzyna A Cieslik
- Division of Cardiovascular Sciences and the DeBakey Heart Center, Department of Medicine, Baylor College of Medicine and the Methodist Hospital, Houston, TX 77030, USA
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Hürlimann HC, Laloo B, Simon-Kayser B, Saint-Marc C, Coulpier F, Lemoine S, Daignan-Fornier B, Pinson B. Physiological and toxic effects of purine intermediate 5-amino-4-imidazolecarboxamide ribonucleotide (AICAR) in yeast. J Biol Chem 2011; 286:30994-31002. [PMID: 21757731 DOI: 10.1074/jbc.m111.262659] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
5-Amino-4-imidazolecarboxamide ribonucleotide 5'-phosphate (AICAR) is a monophosphate metabolic intermediate of the de novo purine synthesis pathway that has highly promising metabolic and antiproliferative properties. Yeast mutants unable to metabolize AICAR are auxotroph for histidine. A screening for suppressors of this phenotype identified recessive and dominant mutants that result in lowering the intracellular AICAR concentration. The recessive mutants affect the adenosine kinase, which is shown here to catalyze the phosphorylation of AICAR riboside in yeast. The dominant mutants strongly enhance the capacity of the alkaline phosphatase Pho13 to dephosphorylate 5-amino-4-imidazole N-succinocarboxamide ribonucleotide 5'-phosphate(SAICAR) into its non-toxic riboside form. By combining these mutants with transcriptomics and metabolomics analyses, we establish that in yeast responses to AICAR and SAICAR are clearly linked to the concentration of the monophosphate forms, whereas the derived nucleoside moieties have no effect even at high intracellular concentration. Finally, we show that AICAR/SAICAR concentrations vary under physiological conditions known to modulate transcription of the purine and phosphate pathway genes.
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Affiliation(s)
- Hans C Hürlimann
- Institut de Biochimie et Génétique Cellulaires (IBGC) Unité Mixte de Recherche (UMR) 5095, Université Ségalen, Bordeaux F-33077, France; IBGC UMR 5095, CNRS, Bordeaux F-33077, France
| | - Benoît Laloo
- Institut de Biochimie et Génétique Cellulaires (IBGC) Unité Mixte de Recherche (UMR) 5095, Université Ségalen, Bordeaux F-33077, France; IBGC UMR 5095, CNRS, Bordeaux F-33077, France
| | - Barbara Simon-Kayser
- Institut de Biochimie et Génétique Cellulaires (IBGC) Unité Mixte de Recherche (UMR) 5095, Université Ségalen, Bordeaux F-33077, France; IBGC UMR 5095, CNRS, Bordeaux F-33077, France
| | - Christelle Saint-Marc
- Institut de Biochimie et Génétique Cellulaires (IBGC) Unité Mixte de Recherche (UMR) 5095, Université Ségalen, Bordeaux F-33077, France; IBGC UMR 5095, CNRS, Bordeaux F-33077, France
| | - Fanny Coulpier
- Institut de Biologie de l'ENS, IBENS, École normale supérieure (ENS), Paris F-75005, France; INSERM, U1024, Paris F-75005, France; UMR 8197, CNRS, Paris F-75005, France
| | - Sophie Lemoine
- Institut de Biologie de l'ENS, IBENS, École normale supérieure (ENS), Paris F-75005, France; INSERM, U1024, Paris F-75005, France; UMR 8197, CNRS, Paris F-75005, France
| | - Bertrand Daignan-Fornier
- Institut de Biochimie et Génétique Cellulaires (IBGC) Unité Mixte de Recherche (UMR) 5095, Université Ségalen, Bordeaux F-33077, France; IBGC UMR 5095, CNRS, Bordeaux F-33077, France.
| | - Benoît Pinson
- Institut de Biochimie et Génétique Cellulaires (IBGC) Unité Mixte de Recherche (UMR) 5095, Université Ségalen, Bordeaux F-33077, France; IBGC UMR 5095, CNRS, Bordeaux F-33077, France
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Amato S, Liu X, Zheng B, Cantley L, Rakic P, Man HY. AMP-activated protein kinase regulates neuronal polarization by interfering with PI 3-kinase localization. Science 2011; 332:247-51. [PMID: 21436401 DOI: 10.1126/science.1201678] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Axon-dendrite polarization is crucial for neural network wiring and information processing in the brain. Polarization begins with the transformation of a single neurite into an axon and its subsequent rapid extension, which requires coordination of cellular energy status to allow for transport of building materials to support axon growth. We found that activation of the energy-sensing adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway suppressed axon initiation and neuronal polarization. Phosphorylation of the kinesin light chain of the Kif5 motor protein by AMPK disrupted the association of the motor with phosphatidylinositol 3-kinase (PI3K), preventing PI3K targeting to the axonal tip and inhibiting polarization and axon growth.
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Affiliation(s)
- Stephen Amato
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
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38
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Gaskin FS, Kamada K, Zuidema MY, Jones AW, Rubin LJ, Korthuis RJ. Isoform-selective 5'-AMP-activated protein kinase-dependent preconditioning mechanisms to prevent postischemic leukocyte-endothelial cell adhesive interactions. Am J Physiol Heart Circ Physiol 2011; 300:H1352-60. [PMID: 21239628 DOI: 10.1152/ajpheart.00944.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously demonstrated that preconditioning induced by ethanol consumption at low levels [ethanol preconditioning (EPC)] or with 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR-PC) 24 h before ischemia-reperfusion prevents postischemic leukocyte-endothelial cell adhesive interactions (LEI) by a mechanism that is initiated by nitric oxide formed by endothelial nitric oxide synthase. Recent work indicates that 1) ethanol increases the activity of AMP-activated protein kinase (AMPK) and 2) AMPK phosphorylates endothelial nitric oxide synthase at the same activation site seen following EPC (Ser1177). In light of these observations, we postulated that the heterotrimeric serine/threonine kinase, AMPK, may play a role in triggering the development of the anti-inflammatory phenotype induced by EPC. Ethanol was administered to C57BL/6J mice by gavage in the presence or absence of AMPK inhibition. Twenty-four hours later, the numbers of rolling and adherent leukocytes in postcapillary venules of the small intestine were recorded using an intravital microscopic approach. Following 45 min of ischemia, LEI were recorded after 30 and 60 min of reperfusion or at equivalent time points in control animals. Ischemia-reperfusion induced a marked increase in LEI relative to sham-operated control mice. The increase in LEI was prevented by EPC, an effect that was lost with AMPK inhibition during the period of ethanol exposure. Studies conducted in AMPK α(1)- and α(2)-knockout mice suggest that the anti-inflammatory effects of AICAR are not dependent on which isoform of the catalytic α-subunit is present because a deficiency of either isoform results in a loss of protection. In sharp contrast, EPC appears to be triggered by an AMPK α(2)-isoform-dependent mechanism.
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Affiliation(s)
- F Spencer Gaskin
- Departments of Medical Pharmacology and Physiology, University of Missouri, Columbia, 65212, USA
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Florant GL, Fenn AM, Healy JE, Wilkerson GK, Handa RJ. To eat or not to eat: the effect of AICAR on food intake regulation in yellow-bellied marmots (Marmota flaviventris). ACTA ACUST UNITED AC 2010; 213:2031-7. [PMID: 20511516 DOI: 10.1242/jeb.039131] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mammals that hibernate (hibernators) exhibit a circannual rhythm of food intake and body mass. In the laboratory during the winter hibernation period, many hibernators enter a series of multi-day torpor bouts, dropping their body temperature to near ambient, and cease to feed even if food is present in their cage. The mechanism(s) that regulates food intake in hibernators is unclear. Recently, AMP-activated protein kinase (AMPK) has been shown to play a key role in the central regulation of food intake in mammals. We hypothesized that infusing an AMPK activator, 5-aminoimidazole-4-carboxamide 1 B-D-ribofuranoside (AICAR), intracerebroventricularly (ICV) into the third ventricle of the hypothalamus would stimulate yellow-bellied marmots (Marmota flaviventris) to feed during their hibernation season. Infusion of AICAR ICV into marmots at an ambient temperature of 22 degrees C caused a significant (P<0.05) increase in food intake. In addition, animals stimulated to feed did not enter torpor during the infusion period. Marmots ICV infused with saline did not increase food intake and these animals continued to undergo torpor at an ambient temperature of 22 degrees C. Our results suggest that AICAR stimulated the food intake pathway, presumably by activating AMPK. These results support the hypothesis that AMPK may be involved in regulating food intake in hibernators and that there may be common neural pathways involved in regulating feeding and eliciting torpor.
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Affiliation(s)
- Gregory L Florant
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
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Peairs A, Radjavi A, Davis S, Li L, Ahmed A, Giri S, Reilly CM. Activation of AMPK inhibits inflammation in MRL/lpr mouse mesangial cells. Clin Exp Immunol 2009; 156:542-51. [PMID: 19438609 DOI: 10.1111/j.1365-2249.2009.03924.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Recent reports show that 5-amino-4-imidazole carboxamide riboside (AICAR), a pharmacological activator of AMP-activated protein kinase (AMPK), inhibits the lipopolysaccharide (LPS)-induced production of proinflammatory cytokines. MRL/MPJ-Fas(lpr) (MRL/lpr) mice show an intrinsic decreased threshold for the production of inflammatory mediators when stimulated. In our current studies, we sought to determine if AMPK activation would inhibit inflammatory mediator production in stimulated kidney mesangial cells. Cultured mesangial cells from MRL/lpr mice were treated with AICAR and stimulated with LPS/interferon (IFN)-gamma. AICAR decreased dose-dependently inducible nitric oxide synthase (iNOS), cyclooxygenase-2 and interleukin-6 production in LPS/IFN-gamma-stimulated mesangial cells. Mechanistically, AICAR inhibited the LPS/IFN-gamma-stimulated PI3K/Akt signalling inflammatory cascade but did not affect LPS/IFN-gamma-mediated inhibitory kappa B phosphorylation or nuclear factor (NF)-kappaB (p65) nuclear translocation. Treatment with the adenosine kinase inhibitor 5'-iodotubercidin blocked the ability of AICAR to activate AMPK and prevented AICAR from inhibiting the LPS/IFN-gamma-stimulated PI3K/Akt pathway and attenuating iNOS expression. Taken together, these observations suggest that AICAR inhibits LPS/IFN-gamma-induced Akt phosphorylation through AMPK activation and may serve as a potential therapeutic target in inflammatory diseases.
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Affiliation(s)
- A Peairs
- Virginia College of Osteopathic Medicine, Blacksburg, VA 24060, USA
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41
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Abstract
The diphosphoinositol polyphosphates ("inositol pyrophosphates") are a specialized subgroup of the inositol phosphate signaling family. This review proposes that many of the current data concerning the metabolic turnover and biological effects of the diphosphoinositol polyphosphates are linked by a common theme: these polyphosphates act as metabolic messengers. This review will also discuss the latest proposals concerning possible molecular mechanisms of action of this intriguing class of molecules.
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Affiliation(s)
- Stephen B Shears
- Inositide Signaling Group, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
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A new constitutively active mutant of AMP-activated protein kinase inhibits anoxia-induced apoptosis of vascular endothelial cell. Hypertens Res 2009; 32:133-9. [PMID: 19262472 DOI: 10.1038/hr.2008.25] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The inhibition of apoptotic changes in vascular endothelial cells is important for preventing vascular damage from hypoxia. AMP-activated protein kinase (AMPK) has recently been identified as playing a role in vascular protection. Although the chemical reagent 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) has been used to stimulate AMPK activity, AICAR has been associated with several nonspecific reactions. We therefore constructed a new constitutively active mutant of AMPK alpha 1 (NcaAMPK), which lacks the autoinhibitory domain in AMPK alpha 1 and in which threonine 172 has been replaced with aspartate. We investigated whether NcaAMPK has an anti-apoptotic effect in vascular endothelial cells under anoxic conditions. NcaAMPK, or green fluorescent protein (GFP) as a control, was overexpressed in human umbilical vein endothelial cells (HUVECs). After HUVECs were incubated for 40 h under normoxic or anoxic conditions, we examined cell viability, caspase 3/7 activity, and expression and phosphorylation levels of apoptosis-related proteins. Cell viabilities under anoxic conditions were improved in NcaAMPK-overexpressing cells. Anoxia increased caspase 3/7 activity, but NcaAMPK reduced this increase significantly. NcaAMPK overexpression increased protein kinase B/Akt Ser473 and endothelial nitric oxide synthase Ser1177 phosphorylation, but pretreatment with the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) did not decrease the viability of NcaAMPK-overexpressing HUVECs. Furthermore, co-expression of a dominant-negative Akt reduced the improvement in cell viability and the suppression of poly (ADP-ribose) polymerase cleavage by NcaAMPK under anoxic conditions. In conclusion, NcaAMPK inhibited anoxia-induced apoptosis in vascular endothelial cells through Akt activation, suggesting that activation of AMPK might protect against ischemic vascular injury.
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Jellinek M. The need for a multi-level biochemical approach to defeat cancer that will also support the host. Med Hypotheses 2008; 71:515-26. [PMID: 18752905 DOI: 10.1016/j.mehy.2008.05.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 05/16/2008] [Accepted: 05/19/2008] [Indexed: 10/21/2022]
Abstract
Cited research papers support the main hypothesis that selected publications supply sufficient information for a combined multi-level treatment strategy against cancer that will also strengthen the host. The three major elements of the proposal are: (A) metastasis being separate from tumor growth requires specific antimetastatic treatments. For this, manipulation of the composition of phospholipids will alter cellular charge characteristics which are instrumental in adhesion. (B) Formate metabolism is at the center of many activities that are controlling tumor growth. The rational and consequences of this are as follows. Supply of formate depends mainly on serine, and consumption on conversion to CO2 yielding needed NADPH. The remainder is used to complete IMP configuration with 5-aminoimidazole-4-carboxamide ribonucleotide (ZMP). At homeostasis residual ZMP activates AMP-activated protein kinase (AMPK) to curb growth promoting phosphatidylinositol-3-kinase (PI3PK). Residual ZMP also activates the oxidation of choline to betaine supplying methyl groups needed for global methylation of DNA while increased oxidation of choline also alters cellular phospholipid composition (refer to metastasis). At low formate level, increased accumulated ZMP becomes pyrophosporylated to ZTP. AMPK activation shifts to PI3PK activity for insulin action restoring formate supplied by serine derived from glycolysis. Increased NADPH-generating glucose-6-phosphate dehydrogenase is diminishing NADP+ required for dehydrogenation of formate. This is restoring the formate balance while lowering ZMP levels to that of homeostasis. Evidence suggests that transformed cells exceed up-regulation of formate thus suppressing all ZMP accumulations resulting in limited AMPK activation, cessation of choline oxidation to betaine and loss of global methylation of DNA. This scenario appears to be tied to tumor survival, a state that could be altered by metabolic interventions using mild agents as described in the research reports cited. (C) Because of a preponderance of pyrimidines in cancer supporting UTP requiring immune evasion, exogenous IMP may offset this imbalance and thus hinder tumor anti-immune activities while strengthen host immune functions. For studies to confirm the proposal, the overall expected result is that a combined administration of all these agents cited here will outperform any single agent considered so far for anticancer treatment.
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Affiliation(s)
- Max Jellinek
- The Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, 1402 South Grand Boulevard, St. Louis, MO 63104, United States.
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López JM. Is ZMP the toxic metabolite in Lesch-Nyhan disease? Med Hypotheses 2008; 71:657-63. [PMID: 18710792 DOI: 10.1016/j.mehy.2008.06.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 06/23/2008] [Accepted: 06/26/2008] [Indexed: 11/17/2022]
Abstract
The genetic deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT), located on the X chromosome, causes a severe neurological disorder in man, known as Lesch-Nyhan disease (LND). The enzyme HPRT is part of the savage pathway of purine biosynthesis and catalyzes the conversion of hypoxanthine and guanine to their respective nucleotides, IMP and GMP. HPRT deficiency is associated with a relatively selective dysfunction of brain dopamine systems. Several metabolites that accumulate in the patients (phosphoribosylpyrophosphate (PRPP), hypoxanthine, guanine, xanthine, and Z-nucleotides) have been proposed as toxic agents in LND. Some authors have pointed that Z-riboside, derived from the accumulation of ZMP, could be the toxic metabolite in LND. However, the available experimental data support a better hypothesis. I suggest that ZMP (and not Z-riboside) is the key toxic metabolite in LND. ZMP is an inhibitor of the bifunctional enzyme adenylosuccinate lyase, and a deficiency of this enzyme causes psychomotor and mental retardation in humans. Moreover, it has been reported that ZMP inhibits mitochondrial oxidative phosphorylation and induces apoptosis in certain cell types. ZMP is also an activator of the AMP-activated protein kinase (AMPK), a homeostatic regulator of energy levels in the cell. The AMPK has been implicated in the regulation of cell viability, catecholamine biosynthesis and cell structure. I propose that accumulation of ZMP will induce a pleiotropic effect in the brain by (1) a direct inhibition of mitochondrial respiration and the bifunctional enzyme adenylosuccinate lyase, and (2) a sustained activation of the AMPK which in turns would reduce cell viability, decrease dopamine synthesis, and alters cell morphology. In addition, a mechanism to explain the accumulation of ZMP in LND is presented. The knowledge of the toxic metabolite, and the way it acts, would help to design a better therapy.
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Affiliation(s)
- José M López
- Institut de Neurociencies, Departament de Bioquímica i Biología Molecular, Unitat de Bioquímica, Facultad de Medicina, Universitat Autónoma de Barcelona, 08193 Cerdanyola del Vallès. Barcelona, Spain.
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Pang T, Zhang ZS, Gu M, Qiu BY, Yu LF, Cao PR, Shao W, Su MB, Li JY, Nan FJ, Li J. Small molecule antagonizes autoinhibition and activates AMP-activated protein kinase in cells. J Biol Chem 2008; 283:16051-60. [PMID: 18321858 DOI: 10.1074/jbc.m710114200] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK) serves as an energy sensor and is considered a promising drug target for treatment of type II diabetes and obesity. A previous report has shown that mammalian AMPK alpha1 catalytic subunit including autoinhibitory domain was inactive. To test the hypothesis that small molecules can activate AMPK through antagonizing the autoinhibition in alpha subunits, we screened a chemical library with inactive human alpha1(394) (alpha1, residues 1-394) and found a novel small-molecule activator, PT1, which dose-dependently activated AMPK alpha1(394), alpha1(335), alpha2(398), and even heterotrimer alpha1beta1gamma1. Based on PT1-docked AMPK alpha1 subunit structure model and different mutations, we found PT1 might interact with Glu-96 and Lys-156 residues near the autoinhibitory domain and directly relieve autoinhibition. Further studies using L6 myotubes showed that the phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase, were dose-dependently and time-dependently increased by PT1 with-out an increase in cellular AMP:ATP ratio. Moreover, in HeLa cells deficient in LKB1, PT1 enhanced AMPK phosphorylation, which can be inhibited by the calcium/calmodulin-dependent protein kinase kinases inhibitor STO-609 and AMPK inhibitor compound C. PT1 also lowered hepatic lipid content in a dose-dependent manner through AMPK activation in HepG2 cells, and this effect was diminished by compound C. Taken together, these data indicate that this small-molecule activator may directly activate AMPK via antagonizing the autoinhibition in vitro and in cells. This compound highlights the effort to discover novel AMPK activators and can be a useful tool for elucidating the mechanism responsible for conformational change and autoinhibitory regulation of AMPK.
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Affiliation(s)
- Tao Pang
- National Center for Drug Screening, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Roche R&D Center (China) Ltd., Shanghai 201203, China
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Zang Y, Yu LF, Pang T, Fang LP, Feng X, Wen TQ, Nan FJ, Feng LY, Li J. AICAR induces astroglial differentiation of neural stem cells via activating the JAK/STAT3 pathway independently of AMP-activated protein kinase. J Biol Chem 2007; 283:6201-8. [PMID: 18077446 DOI: 10.1074/jbc.m708619200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Neural stem cell differentiation and the determination of lineage decision between neuronal and glial fates have important implications in the study of developmental, pathological, and regenerative processes. Although small molecule chemicals with the ability to control neural stem cell fate are considered extremely useful tools in this field, few were reported. AICAR is an adenosine analog and extensively used to activate AMP-activated protein kinase (AMPK), a metabolic "fuel gauge" of the biological system. In the present study, we found an unrecognized astrogliogenic activity of AICAR on not only immortalized neural stem cell line C17.2 (C17.2-NSC), but also primary neural stem cells (NSCs) derived from post-natal (P0) rat hippocampus (P0-NSC) and embryonic day 14 (E14) rat embryonic cortex (E14-NSC). However, another AMPK activator, Metformin, did not alter either the C17.2-NSC or E14-NSC undifferentiated state although both Metformin and AICAR can activate the AMPK pathway in NSC. Furthermore, overexpression of dominant-negative mutants of AMPK in C17.2-NSC was unable to block the gliogenic effects of AICAR. We also found AICAR could activate the Janus kinase (JAK) STAT3 pathway in both C17.2-NSC and E14-NSC but Metformin fails. JAK inhibitor I abolished the gliogenic effects of AICAR. Taken together, these results suggest that the astroglial differentiation effect of AICAR on neural stem cells was acting independently of AMPK and that the JAK-STAT3 pathway is essential for the gliogenic effect of AICAR.
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Affiliation(s)
- Yi Zang
- National Center for Drug Screening, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICA-riboside) as a targeting agent for therapy of patients with acute lymphoblastic leukemia: are we there and are there pitfalls? J Pediatr Hematol Oncol 2007; 29:805-7. [PMID: 18090925 DOI: 10.1097/mph.0b013e31815bbb83] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Bilodeau-Goeseels S, Sasseville M, Guillemette C, Richard FJ. Effects of adenosine monophosphate-activated kinase activators on bovine oocyte nuclear maturation in vitro. Mol Reprod Dev 2007; 74:1021-34. [PMID: 17290417 DOI: 10.1002/mrd.20574] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to examine the effects of an activator of AMPK (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR)) on bovine oocyte nuclear maturation in vitro. After 7 hr of culture, AICAR (1 mM) significantly increased the percentages of cumulus-enclosed oocytes (CEO) and denuded oocytes (DO) remaining at the germinal vesicle stage. After 22 hr of culture, AICAR significantly reduced the percentage of CEO reaching metaphase II (MII). AICAR at 1.0 mM also increased the inhibitory effect of the adenylate cyclase activator forskolin in CEO; however, at 0.05 mM, AICAR increased the percentage of oocytes at MII after 22 hr of culture compared to forskolin alone. The adenosine kinase inhibitor 5'-aminodeoxyadenosine reversed the effect of AICAR in CEO and DO showing that phosphorylation of AICAR by adenosine kinase is required for its inhibitory activity. GMP, but not AMP, inhibited meiosis in CEO and DO; however, inhibition of guanyl and adenyl nucleotides synthesis did not reverse the effect of AICAR suggesting that the inhibitory effect of AICAR is not due to increased synthesis of these nucleotides. Metformin, another activator of AMPK, also inhibited GVBD in CEO and DO. The alpha-1 isoform of the catalytic subunit of AMPK was detected in oocytes and cumulus cells, and reverse transcription-polymerase chain reaction experiments showed the presence of transcripts for alpha-1, alpha-2, beta-1, and gamma-3 isoforms of the regulatory subunits in cumulus cells and oocytes. These data show that the AMPK activator AICAR is inhibitory to nuclear maturation in bovine oocytes due to activation of AMPK.
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Favero CB, Mandell JW. A pharmacological activator of AMP-activated protein kinase (AMPK) induces astrocyte stellation. Brain Res 2007; 1168:1-10. [PMID: 17706943 PMCID: PMC2000700 DOI: 10.1016/j.brainres.2007.06.087] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 06/19/2007] [Accepted: 06/20/2007] [Indexed: 11/20/2022]
Abstract
AMP-activated protein kinase (AMPK) represents a key energy-sensing molecule in many cell types. Because astrocytes are key mediators of metabolic signaling in the brain, we have initiated studies on the expression and activation of AMPK in these cells. Treatment of cultured rat cortical astrocytes with a pharmacological AMPK activator, AICA-riboside (AICAR) resulted in a time- and concentration-dependent increase in phosphorylation of AMPK and acetyl-CoA carboxylase (ACC), a direct substrate. AICAR treatment also induced a transition from epithelioid to stellate morphology in a time- and concentration-dependent manner. As stellation is indicative of actin cytoskeletal reorganization, the formation of stress fibers and focal adhesions in response to AICAR was assessed. AICAR-induced stellation correlated with F-actin disassembly and focal adhesion dispersal. Furthermore, transient transfection of an activated RhoA construct prevented AICAR-induced stellation, indicating a mechanism upstream of RhoA. Use of pharmacological inhibitor compound C prevented AICAR-induced stellation demonstrating necessity of AMPK activity for the response. Our findings suggest that AMPK mediates morphological alterations of astrocytes in response to energy depletion.
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Affiliation(s)
- Carlita B Favero
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
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Woollhead AM, Sivagnanasundaram J, Kalsi KK, Pucovsky V, Pellatt LJ, Scott JW, Mustard KJ, Hardie DG, Baines DL. Pharmacological activators of AMP-activated protein kinase have different effects on Na+ transport processes across human lung epithelial cells. Br J Pharmacol 2007; 151:1204-15. [PMID: 17603555 PMCID: PMC2189835 DOI: 10.1038/sj.bjp.0707343] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE AMP-activated protein kinase (AMPK) is activated by metformin, phenformin, and the AMP mimetic, 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR). We have completed an extensive study of the pharmacological effects of these drugs on AMPK activation, adenine nucleotide concentration, transepithelial amiloride-sensitive (I(amiloride)) and ouabain-sensitive basolateral (I(ouabain)) short circuit current in H441 lung epithelial cells. EXPERIMENTAL APPROACH H441 cells were grown on permeable filters at air interface. I(amiloride), I(ouabain) and transepithelial resistance were measured in Ussing chambers. AMPK activity was measured as the amount of radiolabelled phosphate transferred to the SAMS peptide. Adenine nucleotide concentration was analysed by reverse phase HPLC and NAD(P)H autofluorescence was measured using confocal microscopy. KEY RESULTS Phenformin, AICAR and metformin increased AMPK (alpha1) activity and decreased I(amiloride). The AMPK inhibitor Compound C prevented the action of metformin and AICAR but not phenformin. Phenformin and AICAR decreased I(ouabain) across H441 monolayers and decreased monolayer resistance. The decrease in I(amiloride) was closely related to I(ouabain) with phenformin, but not in AICAR treated monolayers. Metformin and phenformin increased the cellular AMP:ATP ratio but only phenformin and AICAR decreased cellular ATP. CONCLUSIONS AND IMPLICATIONS Activation of alpha1-AMPK is associated with inhibition of apical amiloride-sensitive Na(+) channels (ENaC), which has important implications for the clinical use of metformin. Additional pharmacological effects evoked by AICAR and phenformin on I(ouabain), with potential secondary effects on apical Na+ conductance, ENaC activity and monolayer resistance, have important consequences for their use as pharmacological activators of AMPK in cell systems where Na+K+ATPase is an important component.
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Affiliation(s)
- A M Woollhead
- Centre for Ion Channels and Cell Signalling, Div. of Basic Medical Sciences, St George's, University of London London, UK
| | - J Sivagnanasundaram
- Centre for Ion Channels and Cell Signalling, Div. of Basic Medical Sciences, St George's, University of London London, UK
| | - K K Kalsi
- Centre for Ion Channels and Cell Signalling, Div. of Basic Medical Sciences, St George's, University of London London, UK
| | - V Pucovsky
- Centre for Ion Channels and Cell Signalling, Div. of Basic Medical Sciences, St George's, University of London London, UK
| | - L J Pellatt
- Centre for Ion Channels and Cell Signalling, Div. of Basic Medical Sciences, St George's, University of London London, UK
| | - J W Scott
- Division of Molecular Physiology, School of Life Sciences, University of Dundee Dundee, UK
| | - K J Mustard
- Division of Molecular Physiology, School of Life Sciences, University of Dundee Dundee, UK
| | - D G Hardie
- Division of Molecular Physiology, School of Life Sciences, University of Dundee Dundee, UK
| | - D L Baines
- Centre for Ion Channels and Cell Signalling, Div. of Basic Medical Sciences, St George's, University of London London, UK
- Author for correspondence:
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