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Teuwen JTJ, van der Vorst EPC, Maas SL. Navigating the Maze of Kinases: CaMK-like Family Protein Kinases and Their Role in Atherosclerosis. Int J Mol Sci 2024; 25:6213. [PMID: 38892400 PMCID: PMC11172518 DOI: 10.3390/ijms25116213] [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: 04/13/2024] [Revised: 05/30/2024] [Accepted: 06/02/2024] [Indexed: 06/21/2024] Open
Abstract
Circulating low-density lipoprotein (LDL) levels are a major risk factor for cardiovascular diseases (CVD), and even though current treatment strategies focusing on lowering lipid levels are effective, CVD remains the primary cause of death worldwide. Atherosclerosis is the major cause of CVD and is a chronic inflammatory condition in which various cell types and protein kinases play a crucial role. However, the underlying mechanisms of atherosclerosis are not entirely understood yet. Notably, protein kinases are highly druggable targets and represent, therefore, a novel way to target atherosclerosis. In this review, the potential role of the calcium/calmodulin-dependent protein kinase-like (CaMKL) family and its role in atherosclerosis will be discussed. This family consists of 12 subfamilies, among which are the well-described and conserved liver kinase B1 (LKB1) and 5' adenosine monophosphate-activated protein kinase (AMPK) subfamilies. Interestingly, LKB1 plays a key role and is considered a master kinase within the CaMKL family. It has been shown that LKB1 signaling leads to atheroprotective effects, while, for example, members of the microtubule affinity-regulating kinase (MARK) subfamily have been described to aggravate atherosclerosis development. These observations highlight the importance of studying kinases and their signaling pathways in atherosclerosis, bringing us a step closer to unraveling the underlying mechanisms of atherosclerosis.
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Affiliation(s)
- Jules T. J. Teuwen
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany;
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
| | - Emiel P. C. van der Vorst
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany;
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
- Interdisciplinary Center for Clinical Research (IZKF), RWTH Aachen University, 52074 Aachen, Germany
- Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-Universität München, 80336 München, Germany
| | - Sanne L. Maas
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany;
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
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Salucci S, Bavelloni A, Stella AB, Fabbri F, Vannini I, Piazzi M, Volkava K, Scotlandi K, Martinelli G, Faenza I, Blalock W. The Cytotoxic Effect of Curcumin in Rhabdomyosarcoma Is Associated with the Modulation of AMPK, AKT/mTOR, STAT, and p53 Signaling. Nutrients 2023; 15:nu15030740. [PMID: 36771452 PMCID: PMC9920154 DOI: 10.3390/nu15030740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/11/2023] [Accepted: 01/28/2023] [Indexed: 02/04/2023] Open
Abstract
Approximately 7% of cancers arising in children and 1% of those arising in adults are soft tissue sarcomas (STS). Of these malignancies, rhabdomyosarcoma (RMS) is the most common. RMS survival rates using current therapeutic protocols have remained largely unchanged in the past decade. Thus, it is imperative that the main molecular drivers in RMS tumorigenesis are defined so that more precise, effective, and less toxic therapies can be designed. Curcumin, a common herbal supplement derived from plants of the Curcuma longa species, has an exceptionally low dietary biotoxicity profile and has demonstrated anti-tumorigenic benefits in vitro. In this study, the anti-tumorigenic activity of curcumin was assessed in rhabdomyosarcoma cell lines and used to identify the major pathways responsible for curcumin's anti-tumorigenic effects. Curcumin treatment resulted in cell cycle arrest, inhibited cell migration and colony forming potential, and induced apoptotic cell death. Proteome profiler array analysis demonstrated that curcumin treatment primarily influenced flux through the AKT-mammalian target of rapamycin (mTOR), signal transducer and activator of transcription (STAT), AMP-dependent kinase (AMPK), and p53 associated pathways in a rhabdomyosarcoma subtype-specific manner. Thus, the strategic, combinational therapeutic targeting of these pathways may present the best option to treat this group of tumors.
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Affiliation(s)
- Sara Salucci
- Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM), Università di Bologna, 40126 Bologna, Italy
| | - Alberto Bavelloni
- Laboratorio di Oncologia Sperimentale, IRCCS, Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
| | - Anna Bartoletti Stella
- Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES), Università di Bologna, 40126 Bologna, Italy
| | - Francesco Fabbri
- Laboratorio di Bioscienze, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Ivan Vannini
- Laboratorio di Bioscienze, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Manuela Piazzi
- ‘‘Luigi Luca Cavalli-Sforza’’ Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerca (IGM-CNR), 40136 Bologna, Italy
- IRCCS, Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
| | - Karyna Volkava
- Dipartimento di Farmacia e Biotecnologie (FABIT), Università di Bologna, 40126 Bologna, Italy
| | - Katia Scotlandi
- Laboratorio di Oncologia Sperimentale, IRCCS, Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
| | - Giovanni Martinelli
- Laboratorio di Bioscienze, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy
| | - Irene Faenza
- Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM), Università di Bologna, 40126 Bologna, Italy
- Correspondence: (I.F.); (W.B.)
| | - William Blalock
- ‘‘Luigi Luca Cavalli-Sforza’’ Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerca (IGM-CNR), 40136 Bologna, Italy
- IRCCS, Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
- Correspondence: (I.F.); (W.B.)
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Hardie DG. AMP-activated protein kinase - a journey from 1 to 100 downstream targets. Biochem J 2022; 479:2327-2343. [PMID: 36383046 PMCID: PMC9704532 DOI: 10.1042/bcj20220255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/26/2022] [Accepted: 10/26/2022] [Indexed: 11/17/2022]
Abstract
A casual decision made one evening in 1976, in a bar near the Biochemistry Department at the University of Dundee, led me to start my personal research journey by following up a paper that suggested that acetyl-CoA carboxylase (ACC) (believed to be a key regulatory enzyme of fatty acid synthesis) was inactivated by phosphorylation by what appeared to be a novel, cyclic AMP-independent protein kinase. This led me to define and name the AMP-activated protein kinase (AMPK) signalling pathway, on which I am still working 46 years later. ACC was the first known downstream target for AMPK, but at least 100 others have now been identified. This article contains some personal reminiscences of that research journey, focussing on: (i) the early days when we were defining the kinase and developing the key tools required to study it; (ii) the late 1990s and early 2000s, an exciting time when we and others were identifying the upstream kinases; (iii) recent times when we have been studying the complex role of AMPK in cancer. The article is published in conjunction with the Sir Philip Randle Lecture of the Biochemical Society, which I gave in September 2022 at the European Workshop on AMPK and AMPK-related kinases in Clydebank, Scotland. During the early years of my research career, Sir Philip acted as a role model, due to his pioneering work on insulin signalling and the regulation of pyruvate dehydrogenase.
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Affiliation(s)
- D. Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
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Liu Y, Wang TV, Cui Y, Gao S, Rao Y. Biochemical purification uncovers mammalian sterile 3 (MST3) as a new protein kinase for multifunctional protein kinases AMPK and SIK3. J Biol Chem 2022; 298:101929. [PMID: 35413286 PMCID: PMC9112001 DOI: 10.1016/j.jbc.2022.101929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/30/2022] [Accepted: 04/01/2022] [Indexed: 11/30/2022] Open
Abstract
The AMP-activated protein kinase (AMPK) and AMPK-related kinase salt-inducible kinase 3 (SIK3) regulate many important biological processes ranging from metabolism to sleep. Liver kinase B1 is known to phosphorylate and activate both AMPK and SIK3, but the existence of other upstream kinases was unclear. In this study, we detected liver kinase B1-independent AMPK-related kinase phosphorylation activities in human embryonic kidney cells as well as in mouse brains. Biochemical purification of this phosphorylation activity uncovered mammalian sterile 20-like kinase 3 (MST3). We demonstrate that MST3 from human embryonic kidney cells could phosphorylate AMPK and SIK3 in vivo. In addition, recombinant MST3 expressed in and purified from Escherichia coli could directly phosphorylate AMPK and SIK3 in vitro. Moreover, four other members of the MST kinase family could also phosphorylate AMPK or SIK3. Our results have revealed new kinases able to phosphorylate and activate AMPK and SIK3.
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Affiliation(s)
- Yuxiang Liu
- Laboratory of Neurochemical Biology, Department of Chemical Biology, College of Chemistry and Chemical Engineering, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, School of Pharmaceutical Sciences, Health Sciences Center, Peking University, Beijing, China; Chinese Institute for Brain Research, Beijing, China; School of Basic Medical Sciences, Capital Medical University, Beijing, China; Changping Laboratory, Beijing, China
| | - Tao V Wang
- Laboratory of Neurochemical Biology, Department of Chemical Biology, College of Chemistry and Chemical Engineering, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, School of Pharmaceutical Sciences, Health Sciences Center, Peking University, Beijing, China; Chinese Institute for Brain Research, Beijing, China; School of Basic Medical Sciences, Capital Medical University, Beijing, China; Changping Laboratory, Beijing, China
| | - Yunfeng Cui
- Laboratory of Neurochemical Biology, Department of Chemical Biology, College of Chemistry and Chemical Engineering, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, School of Pharmaceutical Sciences, Health Sciences Center, Peking University, Beijing, China; Chinese Institute for Brain Research, Beijing, China; School of Basic Medical Sciences, Capital Medical University, Beijing, China; Changping Laboratory, Beijing, China
| | - Shengxian Gao
- Laboratory of Neurochemical Biology, Department of Chemical Biology, College of Chemistry and Chemical Engineering, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, School of Pharmaceutical Sciences, Health Sciences Center, Peking University, Beijing, China; Chinese Institute for Brain Research, Beijing, China; School of Basic Medical Sciences, Capital Medical University, Beijing, China; Changping Laboratory, Beijing, China
| | - Yi Rao
- Laboratory of Neurochemical Biology, Department of Chemical Biology, College of Chemistry and Chemical Engineering, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, School of Pharmaceutical Sciences, Health Sciences Center, Peking University, Beijing, China; Chinese Institute for Brain Research, Beijing, China; School of Basic Medical Sciences, Capital Medical University, Beijing, China; Changping Laboratory, Beijing, China.
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Beak SH, Baik M. Comparison of transcriptome between high- and low-marbling fineness in longissimus thoracis muscle of Korean cattle. Anim Biosci 2021; 35:196-203. [PMID: 34293845 PMCID: PMC8738949 DOI: 10.5713/ab.21.0150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/11/2021] [Indexed: 11/27/2022] Open
Abstract
Objective This study compared differentially expressed genes (DEGs) between groups with high and low numbers of fine marbling particles (NFMP) in the longissimus thoracis muscle (LT) of Korean cattle to understand the molecular events associated with fine marbling particle formation. Methods The size and distribution of marbling particles in the LT were assessed with a computer image analysis method. Based on the NFMP, 10 LT samples were selected and assigned to either high- (n = 5) or low- (n = 5) NFMP groups. Using RNA sequencing, LT transcriptomic profiles were compared between the high- and low-NFMP groups. DEGs were selected at p<0.05 and |fold change| >2 and subjected to functional annotation. Results In total, 328 DEGs were identified, with 207 up-regulated and 121 down-regulated genes in the high-NFMP group. Pathway analysis of these DEGs revealed five significant (p<0.05) Kyoto encyclopedia of genes and genomes pathways; the significant terms included endocytosis (p = 0.023), protein processing in endoplasmic reticulum (p = 0.019), and adipocytokine signaling pathway (p = 0.024), which are thought to regulate adipocyte hypertrophy and hyperplasia. The expression of sirtuin4 (p<0.001) and insulin receptor substrate 2 (p = 0.043), which are associated with glucose uptake and adipocyte differentiation, was higher in the high-NFMP group than in the low-NFMP group. Conclusion Transcriptome differences between the high- and low-NFMP groups suggest that pathways regulating adipocyte hyperplasia and hypertrophy are involved in the marbling fineness of the LT.
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Affiliation(s)
- Seok-Hyeon Beak
- Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea
| | - Myunggi Baik
- Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea.,Institue of Green Bio Science and Technology, Seoul National University, Pyeongchang 25354, Korea
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Elhodaky M, Hong LK, Kadkol S, Diamond AM. Selenium-binding protein 1 alters energy metabolism in prostate cancer cells. Prostate 2020; 80:962-976. [PMID: 32511787 PMCID: PMC7473137 DOI: 10.1002/pros.24028] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 04/30/2020] [Accepted: 05/21/2020] [Indexed: 12/20/2022]
Abstract
OBJECTIVE The broad goal of the research described in this study was to investigate the contributions of selenium-binding protein 1 (SBP1) loss in prostate cancer development and outcome. METHODS SBP1 levels were altered in prostate cancer cell lines and the consequences on oxygen consumption, expression of proteins associated with energy metabolism, and cellular transformation and migration were investigated. The effects of exposing cells to the SBP1 reaction products, H2 O2 and H2 S were also assessed. In silico analyses identified potential HNF4α binding sites within the SBP1 promoter region and this was investigated using an inhibitor specific for that transcription factor. RESULTS Using in silico analyses, it was determined that the promoter region of SBP1 contains putative binding sites for the HNF4α transcription factor. The potential for HNF4α to regulate SBP1 expression was supported by data indicating that HNF4α inhibition resulted in a dose-response increase in the levels of SBP1 messenger RNA and protein, identifying HNF4α as a novel negative regulator of SBP1 expression in prostate cancer cells. The consequences of altering the levels of SBP1 were investigated by ectopically expressing SBP1 in PC-3 prostate cancer cells, where SBP1 expression attenuated anchorage-independent cellular growth and migration in culture, both properties associated with transformation. SBP1 overexpression reduced oxygen consumption in these cells and increased the activation of AMP-activated protein kinase (AMPK), a major regulator of energy homeostasis. In addition, the reaction products of SBP1, H2 O2 , and H2 S also activated AMPK. CONCLUSIONS Based on the obtained data, it is hypothesized that SBP1 negatively regulates oxidative phosphorylation (OXPHOS) in the healthy prostate cells by the production of H2 O2 and H2 S and consequential activation of AMPK. The reduction of SBP1 levels in prostate cancer can occur due to increased binding of HNF4α, acting as a transcriptional inhibitor to the SBP1 promoter. Consequently, there is a reduction in H2 O2 and H2 S-mediated signaling, inhibition of AMPK, and stimulation of OXPHOS and building blocks of biomolecules needed for tumor growth and progression. Other effects of SBP1 loss in tumor cells remain to be discovered.
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Affiliation(s)
- Mostafa Elhodaky
- Department of Pathology, College of MedicineUniversity of Illinois at ChicagoChicagoIllinois
| | - Lenny K. Hong
- Department of Pathology, College of MedicineUniversity of Illinois at ChicagoChicagoIllinois
| | - Shrinidhi Kadkol
- Department of Pathology, College of MedicineUniversity of Illinois at ChicagoChicagoIllinois
| | - Alan M. Diamond
- Department of Pathology, College of MedicineUniversity of Illinois at ChicagoChicagoIllinois
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Liu J, Wang M, Sun L, Pan NC, Zhang C, Zhang J, Zuo Z, He S, Wu Q, Wang X. Integrative analysis of in vivo recording with single-cell RNA-seq data reveals molecular properties of light-sensitive neurons in mouse V1. Protein Cell 2020; 11:417-432. [PMID: 32350740 PMCID: PMC7251024 DOI: 10.1007/s13238-020-00720-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/09/2020] [Indexed: 01/09/2023] Open
Abstract
Vision formation is classically based on projections from retinal ganglion cells (RGC) to the lateral geniculate nucleus (LGN) and the primary visual cortex (V1). Neurons in the mouse V1 are tuned to light stimuli. Although the cellular information of the retina and the LGN has been widely studied, the transcriptome profiles of single light-stimulated neuron in V1 remain unknown. In our study, in vivo calcium imaging and whole-cell electrophysiological patch-clamp recording were utilized to identify 53 individual cells from layer 2/3 of V1 as light-sensitive (LS) or non-light-sensitive (NS) by single-cell light-evoked calcium evaluation and action potential spiking. The contents of each cell after functional tests were aspirated in vivo through a patch-clamp pipette for mRNA sequencing. Moreover, the three-dimensional (3-D) morphological characterizations of the neurons were reconstructed in a live mouse after the whole-cell recordings. Our sequencing results indicated that V1 neurons with a high expression of genes related to transmission regulation, such as Rtn4r and Rgs7, and genes involved in membrane transport, such as Na+/K+ ATPase and NMDA-type glutamatergic receptors, preferentially responded to light stimulation. Furthermore, an antagonist that blocks Rtn4r signals could inactivate the neuronal responses to light stimulation in live mice. In conclusion, our findings of the vivo-seq analysis indicate the key role of the strength of synaptic transmission possesses neurons in V1 of light sensory.
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Affiliation(s)
- Jianwei Liu
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Mengdi Wang
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Le Sun
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Na Clara Pan
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Changjiang Zhang
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Junjing Zhang
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, 100875, China
| | - Zhentao Zuo
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Sheng He
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Qian Wu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, 100875, China.
- IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China.
| | - Xiaoqun Wang
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Brain-Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Advanced Innovation Center for Human Brain Protection, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China.
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Jiating L, Buyun J, Yinchang Z. Role of Metformin on Osteoblast Differentiation in Type 2 Diabetes. BIOMED RESEARCH INTERNATIONAL 2019; 2019:9203934. [PMID: 31886264 PMCID: PMC6899291 DOI: 10.1155/2019/9203934] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022]
Abstract
Metformin, an effective hypoglycemic, can modulate different points of malignant mass, polycystic ovary syndrome (PCOS), cardiovascular diseases, tuberculosis, and nerve regeneration. Recently, the effect of metformin on bone metabolism has been analyzed. Metformin relies on organic cation transporters (OCT1), a polyspecific cell membrane of the solute carrier 22A (SLC22A) gene family, to facilitate its intracellular uptake and action on complex I of the respiratory chain of mitochondria. These changes activate the cellular energy sensor AMP-activated protein kinase (AMPK). Thus, the increased cellular AMP/ATP ratio causes a dramatic and progressive activation of insulin and lysosomes, resulting in a decrease in intracellular glucose level, which promotes osteoblast proliferation and differentiation. AMPK also phosphorylates runt-related transcription factor 2 (Runx2) at S118, the lineage-specific transcriptional regulators, to promote osteogenesis. Metformin phosphorylates extracellular signal-regulated kinase (ERK), stimulates endothelial and inducible nitric oxide synthases (e/iNOS), inhibits the GSK3β/Wnt/β-catenin pathway, and promotes osteogenic differentiation of osteoblasts. The effect of metformin on hyperglycemia decreases intracellular reactive oxygen species (ROS) and advanced glycation end-products (AGEs) in collagen, and reduced serum levels of insulin-like growth factors (IGF-1) were beneficial for bone formation. Metformin has a certain effect on microangiopathy and anti-inflammation, which can induce osteoporosis, activate the activity of osteoclasts, and inhibit osteoblast activity, and has demonstrated extensive alteration in bone and mineral metabolism. The aim of this review was to elucidate the mechanisms of metformin on osteoblasts in insulin-deficient diabetes.
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Affiliation(s)
- Lin Jiating
- Department of Stomatology, The First Affiliated Hospital of Wannan Medical College, Wuhu, Anhui Province 241000, China
| | - Ji Buyun
- Department of Stomatology, The First Affiliated Hospital of Wannan Medical College, Wuhu, Anhui Province 241000, China
| | - Zhang Yinchang
- Department of Orthopedics, The First Affiliated Hospital of Wannan Medical College, Wuhu, Anhui Province 241000, China
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Zhang T, Hu J, Wang X, Zhao X, Li Z, Niu J, Steer CJ, Zheng G, Song G. MicroRNA-378 promotes hepatic inflammation and fibrosis via modulation of the NF-κB-TNFα pathway. J Hepatol 2019; 70:87-96. [PMID: 30218679 PMCID: PMC6554744 DOI: 10.1016/j.jhep.2018.08.026] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 07/25/2018] [Accepted: 08/31/2018] [Indexed: 12/25/2022]
Abstract
BACKGROUND & AIMS The progression of hepatosteatosis to non-alcoholic steatohepatitis (NASH) is a critical step in the pathogenesis of hepatocellular cancer. However, the underlying mechanism(s) for this progression is essentially unknown. This study was designed to determine the role of miR-378 in regulating NASH progression. METHODS We used immunohistochemistry, luciferase assays and immunoblotting to study the role of miR-378 in modulating an inflammatory pathway. Wild-type mice kept on a high-fat diet (HFD) were injected with miR-378 inhibitors or a mini-circle expression system containing miR-378, to study loss and gain-of functions of miR-378. RESULTS MiR-378 expression is increased in livers of dietary obese mice and patients with NASH. Further studies revealed that miR-378 directly targeted Prkag2 that encodes AMP-activated protein kinase γ 2 (AMPKγ2). AMPK signaling negatively regulates the NF-κB-TNFα inflammatory axis by increasing deacetylase activity of sirtuin 1. By targeting Prkag2, miR-378 reduced sirtuin 1 activity and facilitated an inflammatory pathway involving NF-κB-TNFα. In contrast, miR-378 knockdown induced expression of Prkag2, increased sirtuin 1 activity and blocked the NF-κB-TNFα axis. Additionally, knockdown of increased Prkag2 offset the inhibitory effects of miR-378 inhibitor on the NF-κB-TNFα axis, suggesting that AMPK signaling mediates the role of miR-378 in facilitating this inflammatory pathway. Liver-specific expression of miR-378 triggered the development of NASH and fibrosis by activating TNFα signaling. Ablation of TNFα in miR-378-treated mice impaired the ability of miR-378 to facilitate hepatic inflammation and fibrosis, suggesting that TNFα signaling is required for miR-378 to promote NASH. CONCLUSION MiR-378 plays a key role in the development of hepatic inflammation and fibrosis by positively regulating the NF-κB-TNFα axis. MiR-378 is a potential therapeutic target for the treatment of NASH. LAY SUMMARY The recent epidemic of obesity has been associated with a sharp rise in the incidence of non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanism(s) remains poorly described and effective therapeutic approaches against NAFLD are lacking. The results establish that microRNA-378 facilitates the development of hepatic inflammation and fibrosis and suggests the therapeutic potential of microRNA-378 inhibitor for the treatment of NAFLD.
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Affiliation(s)
- Tianpeng Zhang
- Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA
| | - Junjie Hu
- Key Laboratory of Chinese Medicine Resource and Compound Prescription, Ministry of Education, Hubei University of Chinese Medicine, Wuhan, Hubei Province 430065, China
| | - Xiaomei Wang
- institute for Translational Medicine, Jilin University, Changchun, Jilin Province 130021, China
| | | | - Zhuoyu Li
- institute of Biotechnology, Shanxi University, Taiyuan, Shanxi Province 030006, China
| | - Junqi Niu
- Key Laboratory of Chinese Medicine Resource and Compound Prescription, Ministry of Education, Hubei University of Chinese Medicine, Wuhan, Hubei Province 430065, China
| | - Clifford J. Steer
- Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA,Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Guohua Zheng
- Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Guisheng Song
- Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA; Key Laboratory of Chinese Medicine Resource and Compound Prescription, Ministry of Education, Hubei University of Chinese Medicine, Wuhan, Hubei Province 430065, China; Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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Miyamoto L. Molecular Pathogenesis of Familial Wolff-Parkinson-White Syndrome. THE JOURNAL OF MEDICAL INVESTIGATION 2018; 65:1-8. [PMID: 29593177 DOI: 10.2152/jmi.65.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Familial Wolff-Parkinson-White (WPW) syndrome is an autosomal dominant inherited disease and consists of a small percentage of WPW syndrome which exhibits ventricular pre-excitation by development of accessory atrioventricular pathway. A series of mutations in PRKAG2 gene encoding gamma2 subunit of 5'AMP-activated protein kinase (AMPK) has been identified as the cause of familial WPW syndrome. AMPK is one of the most important metabolic regulators of carbohydrates and lipids in many types of tissues including cardiac and skeletal muscles. Patients and animals with the mutation in PRKAG2 gene exhibit aberrant atrioventricular conduction associated with cardiac glycogen overload. Recent studies have revealed "novel" significance of canonical pathways leading to glycogen synthesis and provided us profound insights into molecular mechanism of the regulation of glycogen metabolism by AMPK. This review focuses on the molecular basis of the pathogenesis of cardiac abnormality due to PRKAG2 mutation and will provide current overviews of the mechanism of glycogen regulation by AMPK. J. Med. Invest. 65:1-8, February, 2018.
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Miyamoto L, Yamane M, Tomida Y, Kono M, Yamaoka T, Kawasaki A, Hatano A, Tsuda K, Xu W, Ikeda Y, Tamaki T, Tsuchiya K. Nitrite Activates 5′AMP-Activated Protein Kinase-Endothelial Nitric Oxide Synthase Pathway in Human Glomerular Endothelial Cells. Biol Pharm Bull 2017; 40:1866-1872. [DOI: 10.1248/bpb.b17-00316] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Licht Miyamoto
- Laboratory of Pharmacology and Physiological Sciences, Frontier Laboratory for Pharmaceutical Sciences, Institute of Biomedical Sciences, University of Tokushima Graduate School
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Megumi Yamane
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Yosuke Tomida
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Mai Kono
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Tomomi Yamaoka
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Aya Kawasaki
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Aya Hatano
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Katsunori Tsuda
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Wenting Xu
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Yasumasa Ikeda
- Department of Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Toshiaki Tamaki
- Department of Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
| | - Koichiro Tsuchiya
- Department of Medical Pharmacology, Institute of Biomedical Sciences, University of Tokushima Graduate School
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The KSHV K1 Protein Modulates AMPK Function to Enhance Cell Survival. PLoS Pathog 2016; 12:e1005985. [PMID: 27829024 PMCID: PMC5102384 DOI: 10.1371/journal.ppat.1005985] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 10/07/2016] [Indexed: 12/27/2022] Open
Abstract
Kaposi’s sarcoma herpesvirus (KSHV) is the etiologic agent of Kaposi’s sarcoma (KS) as well as two lymphoproliferative diseases, primary effusion lymphoma and multicentric Castleman’s disease. KSHV encodes viral proteins, such as K1, that alter signaling pathways involved in cell survival. Expression of K1 has been reported to transform rodent fibroblasts, and K1 transgenic mice develop multiple tumors, suggesting that K1 has an important role in KSHV pathogenesis. We found that cells infected with a KSHV virus containing a WT K1 gene had a survival advantage under conditions of nutrient deprivation compared to cells infected with KSHV K1 mutant viruses. 5’ adenosine monophosphate-activated protein kinase (AMPK) responds to nutrient deprivation by maintaining energy homeostasis, and AMPK signaling has been shown to promote cell survival in various types of cancers. Under conditions of AMPK inhibition, we also observed that cells infected with KSHV containing a WT K1 gene had a survival advantage compared to KSHV K1 mutant virus infected cells. To explore the underpinnings of this phenotype, we identified K1-associated cellular proteins by tandem affinity purification and mass spectrometry. We found that the KSHV K1 protein associates with the gamma subunit of AMPK (AMPKγ1). We corroborated this finding by independently confirming that K1 co-immunoprecipitates with AMPKγ1. Co-immunoprecipitations of wild-type K1 (K1WT) or K1 domain mutants and AMPKγ1, revealed that the K1 N-terminus is important for the association between K1 and AMPKγ1. We propose that the KSHV K1 protein promotes cell survival via its association with AMPKγ1 following exposure to stress. Infectious agents such as Kaposi’s sarcoma associated herpesvirus (KSHV) are etiologic agents of human cancer. KSHV-infected cells must survive various environmental stresses. Cells infected with KSHV express viral proteins that alter normal cellular processes to promote cell survival and viral persistence. We found that the KSHV K1 protein promotes survival under conditions of cellular stress, and that this survival advantage is at least partially dependent on the association of K1 and the cellular protein AMP-activated protein kinase (AMPK). We also observed increased AMPK activity in K1-expressing cells compared to EV following exposure to metabolic stress. Several reports suggest that AMPK signaling may contribute to tumor development by promoting cell survival. Our results suggest that KSHV K1 modulates cellular AMPK function to enhance the survival of KSHV-infected cells in order to promote viral persistence.
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Jiang S, Zhai H, Li D, Huang J, Zhang H, Li Z, Zhang W, Xu G. AMPK-dependent regulation of GLP1 expression in L-like cells. J Mol Endocrinol 2016; 57:151-60. [PMID: 27493247 DOI: 10.1530/jme-16-0099] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 08/04/2016] [Indexed: 12/25/2022]
Abstract
This study examined whether AMPK, an evolutionarily conserved sensor of cellular energy status, determines the production of glucagon-like peptide-1 (GLP1). A negative relation existed between phosphorylation of AMPKα and the expression and secretion of GLP1 during changes in energy status in STC-1 cells, an L-like cell line. High concentration of glucose (25 mmol/L) decreased AMPKα phosphorylation, whereas it stimulated the expression and secretion of GLP1 relative to 5.6 mmol/L glucose. Serum starvation upregulated AMPKα phosphorylation, whereas it reduced GLP1 production significantly. Stimulation of AMPK phosphorylation by AICAR and overexpression of wild-type AMPKα1, constitutively active AMPKα1 plasmids, or AMPKα1 lentivirus particles suppressed proglucagon mRNA and protein contents in STC-1 cells. Inactivation of AMPK by Compound C, AMPKα1 siRNA or kinase-inactive AMPKα1 mutant increased the expression and secretion of GLP1. Our results suggest that AMPKα1 may link energy supply with the production of GLP1 in L-like cells.
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Affiliation(s)
- Sushi Jiang
- Department of PhysiologySchool of Medicine, Jinan University, Guangzhou, Guangdong, China
| | - Hening Zhai
- Department of PhysiologySchool of Medicine, Jinan University, Guangzhou, Guangdong, China Endoscopy CenterThe First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China
| | - Danjie Li
- Department of PhysiologySchool of Medicine, Jinan University, Guangzhou, Guangdong, China
| | - Jiana Huang
- Department of PhysiologySchool of Medicine, Jinan University, Guangzhou, Guangdong, China
| | - Heng Zhang
- Department of PhysiologySchool of Medicine, Jinan University, Guangzhou, Guangdong, China
| | - Ziru Li
- Shenzhen University Diabetes CenterShenzhen University Health Science Center, Shenzhen, Guangdong, China
| | - Weizhen Zhang
- Endoscopy CenterThe First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China Department of SurgeryUniversity of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Geyang Xu
- Department of PhysiologySchool of Medicine, Jinan University, Guangzhou, Guangdong, China
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Fang R, Zhu X, Zhu Y, Tong X, Li K, Bai H, Li X, Ben J, Zhang H, Yang Q, Chen Q. Miltefosine Suppresses Hepatic Steatosis by Activating AMPK Signal Pathway. PLoS One 2016; 11:e0163667. [PMID: 27681040 PMCID: PMC5040442 DOI: 10.1371/journal.pone.0163667] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 09/12/2016] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE It has been accepted that AMPK (Adenosine monophosphate-activated protein kinase) activation exhibits many beneficial effects on glucolipid metabolism. Lysophosphatidylcholine (LPC) is an important lysophospholipid which can improve blood glucose levels in diabetic mice and attenuate inflammation by activating AMPK signal pathway in macrophages. Synthetic alkylphospholipids (ALPs), such as miltefosine, is used as an alternate of LPC for the clinical application. Here, we investigated whether miltefosine could have an impact on hepatic steatosis and related metabolic disorders. EXPERIMENTAL APPROACH Mice were fed with high fat diet (HFD) for 16 weeks to generate an obese model. Next, the obese mice were randomly divided into three groups: saline-treated and miltefosine-treated (2.5 or 5 mg/kg/d) groups. Miltefosine was intraperitoneally administrated into mice for additional 4 weeks plus HFD treatment. KEY RESULTS It was shown that miltefosine treatment could substantially improve glucose metabolism, prevented hepatic lipid accumulation, and inhibited liver inflammation in HFD-fed mice by activating AMPK signal pathway. In vitro, miltefosine stimulated AMPKα phosphorylation both in time and dose dependent manner and decreased lipid accumulation in liver cells. When a specific AMPK inhibitor compound C was used to treat mice, the antagonistic effects of miltefosine on HFD-induced mouse hyperlipidaemia and liver steatosis were abolished. Treatment with miltefosine also dramatically inhibited the HFD-induced liver inflammation in mice. CONCLUSIONS AND IMPLICATIONS Here we demonstrated that miltefosine might be a new activator of AMPK signal pathway in vivo and in vitro and be useful for treatment of hepatic steatosis and related metabolic disorders.
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Affiliation(s)
- Ru Fang
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Xudong Zhu
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Yaqin Zhu
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Xing Tong
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Kexue Li
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Hui Bai
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Xiaoyu Li
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Jingjing Ben
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Hanwen Zhang
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Qing Yang
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
| | - Qi Chen
- Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing 210029, People’s Republic of China
- * E-mail:
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Wang YG, Han XG, Yang Y, Qiao H, Dai KR, Fan QM, Tang TT. Functional differences between AMPK α1 and α2 subunits in osteogenesis, osteoblast-associated induction of osteoclastogenesis, and adipogenesis. Sci Rep 2016; 6:32771. [PMID: 27600021 PMCID: PMC5013406 DOI: 10.1038/srep32771] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 08/15/2016] [Indexed: 12/21/2022] Open
Abstract
The endocrine role of the skeleton-which is impaired in human diseases including osteoporosis, obesity and diabetes-has been highlighted previously. In these diseases, the role of AMPK, a sensor and regulator of energy metabolism, is of biological and clinical importance. Since AMPK’s main catalytic subunit α has two isoforms, it is unclear whether functional differences between them exist in the skeletal system. The current study overexpressed AMPKα1 and α2 in MC3T3-E1 cells, primary osteoblasts and mouse BMSCs by lentiviral transduction. Cells overexpressing AMPKα2 showed higher osteogenesis potential than AMPKα1, wherein androgen receptor (AR) and osteoactivin played important roles. RANKL and M-CSF were secreted at lower levels from cells overexpressing α2 than α1, resulting in decreased osteoblast-associated osteoclastogenesis. Adipogenesis was inhibited to a greater degree in 3T3-L1 cells overexpressing α2 than α1, which was modulated by AR. An abnormal downregulation of AMPKα2 was observed in human BMSCs exhibiting the fibrous dysplasia (FD) phenotype. Overexpression of AMPKα2 in these cells rescued the defect in osteogenesis, suggesting that AMPKα2 plays a role in FD pathogenesis. These findings highlight functional differences between AMPKα1 and α2, and provide a basis for investigating the molecular mechanisms of diseases associated with impaired functioning of the skeletal system.
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Affiliation(s)
- Yu-Gang Wang
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
| | - Xiu-Guo Han
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
| | - Ying Yang
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
| | - Han Qiao
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
| | - Ke-Rong Dai
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
| | - Qi-Ming Fan
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
| | - Ting-Ting Tang
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China
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Ding Y, Zhang M, Zhang W, Lu Q, Cai Z, Song P, Okon IS, Xiao L, Zou MH. AMP-Activated Protein Kinase Alpha 2 Deletion Induces VSMC Phenotypic Switching and Reduces Features of Atherosclerotic Plaque Stability. Circ Res 2016; 119:718-30. [PMID: 27439892 DOI: 10.1161/circresaha.116.308689] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 07/20/2016] [Indexed: 12/21/2022]
Abstract
RATIONALE AMP-activated protein kinase (AMPK) has been reported to play a protective role in atherosclerosis. However, whether AMPKα2 controls atherosclerotic plaque stability remains unknown. OBJECTIVE The aim of this study was to evaluate the impact of AMPKα2 deletion on atherosclerotic plaque stability in advanced atherosclerosis at the brachiocephalic arteries and to elucidate the underlying mechanisms. METHODS AND RESULTS Features of atherosclerotic plaque stability and the markers for contractile or synthetic vascular smooth muscle cell (VSMC) phenotypes were monitored in the brachiocephalic arteries from Apoe(-/-)AMPKα2(-/-) mice or VSMC-specific AMPKα2(-/-) mice in an Apoe(-/-) background (Apoe(-/-)AMPKα2(sm-/-)) fed Western diet for 10 weeks. We identified that Apoe(-/-)AMPKα2(-/-) mice and Apoe(-/-)AMPKα2(sm-/-) mice exhibited similar unstable plaque features, aggravated VSMC phenotypic switching, and significant upregulation of Kruppel-like factor 4 (KLF4) in the plaques located in the brachiocephalic arteries compared with those found in Apoe(-/-) and Apoe(-/-)AMPKα2(sm+/+) control mice. Pravastatin, an AMPK activator, suppressed VSMC phenotypic switching and alleviated features of atherosclerotic plaque instability in Apoe(-/-)AMPKα2(sm+/+) mice, but not in Apoe(-/-)AMPKα2(sm-/-) mice. VSMC isolated from AMPKα2(-/-) mice displayed a significant reduction of contractile proteins(smooth muscle actin-α, calponin, and SM-MHC [smooth muscle-mysion heavy chain]) in parallel with increased detection of synthetic proteins (vimentin and osteopontin) and KLF4, as observed in vivo. KLF4-specific siRNA abolished AMPKα2 deletion-induced VSMC phenotypic switching. Furthermore, pharmacological or genetic inhibition of nuclear factor-κB significantly decreased KLF4 upregulation in VSMC from AMPKα2(-/-) mice. Finally, we found that AMPKα2 deletion markedly promoted the binding of nuclear factor-κBp65 to KLF4 promoter. CONCLUSIONS This study demonstrated that AMPKα2 deletion induces VSMC phenotypic switching and promotes features of atherosclerotic plaque instability in nuclear factor-κB-KLF4-dependent manner.
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Affiliation(s)
- Ye Ding
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Miao Zhang
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Wencheng Zhang
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Qiulun Lu
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Zhejun Cai
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Ping Song
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Imoh Sunday Okon
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Lei Xiao
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.)
| | - Ming-Hui Zou
- From the Center for Molecular and Translational Medicine, Georgia State University, Atlanta (Y.D., Q.L., Z.C., P.S., I.S.O., L.X., M.-H.Z.); Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (M.Z.); and The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China (W.Z.).
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Jin S, Moujahid EME, Duan Z, Zheng J, Qu L, Xu G, Yang N, Chen S. Association of AMPK subunit gene polymorphisms with growth, feed intake, and feed efficiency in meat-type chickens. Poult Sci 2016; 95:1492-1497. [DOI: 10.3382/ps/pew081] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/03/2016] [Indexed: 12/25/2022] Open
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18
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O'Neill EC, Trick M, Hill L, Rejzek M, Dusi RG, Hamilton CJ, Zimba PV, Henrissat B, Field RA. The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry. MOLECULAR BIOSYSTEMS 2016; 11:2808-20. [PMID: 26289754 DOI: 10.1039/c5mb00319a] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30,000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (α-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol.
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Affiliation(s)
- Ellis C O'Neill
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
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19
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Fisher KW, Das B, Kim HS, Clymer BK, Gehring D, Smith DR, Costanzo-Garvey DL, Fernandez MR, Brattain MG, Kelly DL, MacMillan J, White MA, Lewis RE. AMPK Promotes Aberrant PGC1β Expression To Support Human Colon Tumor Cell Survival. Mol Cell Biol 2015; 35:3866-79. [PMID: 26351140 PMCID: PMC4609747 DOI: 10.1128/mcb.00528-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/24/2015] [Accepted: 08/28/2015] [Indexed: 11/20/2022] Open
Abstract
A major goal of cancer research is the identification of tumor-specific vulnerabilities that can be exploited for the development of therapies that are selectively toxic to the tumor. We show here that the transcriptional coactivators peroxisome proliferator-activated receptor gamma coactivator 1β (PGC1β) and estrogen-related receptor α (ERRα) are aberrantly expressed in human colon cell lines and tumors. With kinase suppressor of Ras 1 (KSR1) depletion as a reference standard, we used functional signature ontology (FUSION) analysis to identify the γ1 subunit of AMP-activated protein kinase (AMPK) as an essential contributor to PGC1β expression and colon tumor cell survival. Subsequent analysis revealed that a subunit composition of AMPK (α2β2γ1) is preferred for colorectal cancer cell survival, at least in part, by stabilizing the tumor-specific expression of PGC1β. In contrast, PGC1β and ERRα are not detectable in nontransformed human colon epithelial cells, and depletion of the AMPKγ1 subunit has no effect on their viability. These data indicate that Ras oncogenesis relies on the aberrant activation of a PGC1β-dependent transcriptional pathway via a specific AMPK isoform.
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Affiliation(s)
- Kurt W Fisher
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Binita Das
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Hyun Seok Kim
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Beth K Clymer
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Drew Gehring
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Deandra R Smith
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | | | - Mario R Fernandez
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Michael G Brattain
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - David L Kelly
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - John MacMillan
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas Texas, USA
| | - Michael A White
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Robert E Lewis
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
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20
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Borthakur G, Duvvuri S, Ruvolo V, Tripathi DN, Piya S, Burks J, Jacamo R, Kojima K, Ruvolo P, Fueyo-Margareto J, Konopleva M, Andreeff M. MDM2 Inhibitor, Nutlin 3a, Induces p53 Dependent Autophagy in Acute Leukemia by AMP Kinase Activation. PLoS One 2015; 10:e0139254. [PMID: 26440941 PMCID: PMC4595506 DOI: 10.1371/journal.pone.0139254] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 09/09/2015] [Indexed: 12/31/2022] Open
Abstract
MDM2 (mouse double minute 2) inhibitors that activate p53 and induce apoptosis in a non-genotoxic manner are in clinical development for treatment of leukemias. P53 can modulate other programmed cell death pathways including autophagy both transcriptionally and non-transcriptionally. We investigated autophagy induction in acute leukemia by Nutlin 3a, a first-in-class MDM2 inhibitor. Nutlin 3a induced autophagy in a p53 dependent manner and transcriptional activation of AMP kinase (AMPK) is critical, as this effect is abrogated in AMPK -/- mouse embryonic fibroblasts. Nutlin 3a induced autophagy appears to be pro-apoptotic as pharmacological (bafilomycin) or genetic inhibition (BECLIN1 knockdown) of autophagy impairs apoptosis induced by Nutlin 3a.
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Affiliation(s)
- Gautam Borthakur
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Seshagiri Duvvuri
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Vivian Ruvolo
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Durga Nand Tripathi
- Centre for Translational Cancer Research, Institute for Biosciences & Technology, Texas A&M Health Science Center, Houston, Texas, United States of America
| | - Sujan Piya
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Jared Burks
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Rodrigo Jacamo
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Kensuke Kojima
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Peter Ruvolo
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Juan Fueyo-Margareto
- Department of Neuro-oncology, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Marina Konopleva
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Michael Andreeff
- Section of Molecular Hematology and Therapy; Departments of Leukemia and Stem Cell Transplantation, UT MD Anderson Cancer Center, Houston, Texas, United States of America
- * E-mail:
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21
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The influence of maternal energy status during mid-gestation on beef offspring tenderness, muscle characteristics, and gene expression. Meat Sci 2015; 110:201-11. [PMID: 26253836 DOI: 10.1016/j.meatsci.2015.07.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 07/06/2015] [Accepted: 07/23/2015] [Indexed: 01/24/2023]
Abstract
The objective of this study was to determine if maternal energy status during mid-gestation influences the expression of genes regulating muscle and fat development, and muscle characteristics that may impact meat tenderness. Cows grazed dormant, native range (Positive Energy Status [PES]) or were fed at 80% of maintenance energy requirements (Negative Energy Status [NES]) during mid-gestation. Steer offspring were harvested after 21 d in the feedlot (weaning subsample) or after 208 d in the feedlot (final subsample). Greater 21-d tenderness was observed in NES steers, resulting from reduced collagen content in longissimus lumborum steaks. In the semitendinosus, NES steers had greater soluble collagen, and down-regulated expression of MHC-IIA and TIMP-3 at weaning, while MHC-IIA expression was up-regulated in NES steers in the final harvest. Data show mid-gestational maternal energy status may impact offspring tenderness and collagen, but differences were not detected in expression of genes important in myogenesis and adipogenesis in muscle samples obtained from steers at weaning or slaughter.
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Krishan S, Richardson DR, Sahni S. Adenosine Monophosphate–Activated Kinase and Its Key Role in Catabolism: Structure, Regulation, Biological Activity, and Pharmacological Activation. Mol Pharmacol 2014; 87:363-77. [DOI: 10.1124/mol.114.095810] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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23
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DiTommaso T, Jones LK, Cottle DL, Gerdin AK, Vancollie VE, Watt FM, Ramirez-Solis R, Bradley A, Steel KP, Sundberg JP, White JK, Smyth IM. Identification of genes important for cutaneous function revealed by a large scale reverse genetic screen in the mouse. PLoS Genet 2014; 10:e1004705. [PMID: 25340873 PMCID: PMC4207618 DOI: 10.1371/journal.pgen.1004705] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 08/26/2014] [Indexed: 12/15/2022] Open
Abstract
The skin is a highly regenerative organ which plays critical roles in protecting the body and sensing its environment. Consequently, morbidity and mortality associated with skin defects represent a significant health issue. To identify genes important in skin development and homeostasis, we have applied a high throughput, multi-parameter phenotype screen to the conditional targeted mutant mice generated by the Wellcome Trust Sanger Institute's Mouse Genetics Project (Sanger-MGP). A total of 562 different mouse lines were subjected to a variety of tests assessing cutaneous expression, macroscopic clinical disease, histological change, hair follicle cycling, and aberrant marker expression. Cutaneous lesions were associated with mutations in 23 different genes. Many of these were not previously associated with skin disease in the organ (Mysm1, Vangl1, Trpc4ap, Nom1, Sparc, Farp2, and Prkab1), while others were ascribed new cutaneous functions on the basis of the screening approach (Krt76, Lrig1, Myo5a, Nsun2, and Nf1). The integration of these skin specific screening protocols into the Sanger-MGP primary phenotyping pipelines marks the largest reported reverse genetic screen undertaken in any organ and defines approaches to maximise the productivity of future projects of this nature, while flagging genes for further characterisation.
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Affiliation(s)
- Tia DiTommaso
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, Australia
| | - Lynelle K. Jones
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, Australia
| | - Denny L. Cottle
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, Australia
| | | | - Anna-Karin Gerdin
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Valerie E. Vancollie
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Fiona M. Watt
- Centre for Stem Cells and Regenerative Medicine King's College London, Guy's Hospital, London, United Kingdom
| | - Ramiro Ramirez-Solis
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Allan Bradley
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Karen P. Steel
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, United Kingdom
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London, United Kingdom
| | - John P. Sundberg
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jacqueline K. White
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Ian M. Smyth
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, Australia
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Melbourne, Australia
- * E-mail:
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Harmel E, Grenier E, Bendjoudi Ouadda A, El Chebly M, Ziv E, Beaulieu JF, Sané A, Spahis S, Laville M, Levy E. AMPK in the small intestine in normal and pathophysiological conditions. Endocrinology 2014; 155:873-88. [PMID: 24424053 DOI: 10.1210/en.2013-1750] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The role of AMPK in regulating energy storage and depletion remains unexplored in the intestine. This study will to define its status, composition, regulation and lipid function, as well as to examine the impact of insulin resistance and type 2 diabetes on intestinal AMPK activation, insulin sensitivity, and lipid metabolism. Caco-2/15 cells and Psammomys obesus (P. obesus) animal models were experimented. We showed the predominance of AMPKα1 and the prevalence of α1/β2/γ1 heterotrimer in Caco-2/15 cells. The activation of AMPK by 5-aminoimidazole-4-carboxamide ribonucleoside and metformin resulted in increased phospho(p)-ACC. However, the down-regulation of p-AMPK by compound C and high glucose lowered p-ACC without affecting 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Administration of metformin to P. obesus with insulin resistance and type 2 diabetes led to 1) an up-regulation of intestinal AMPK signaling pathway typified by ascending p-AMPKα(-Thr172); 2) a reduction in ACC activity; 3) an elevation of carnitine palmitoyltransferase 1; 4) a trend of increase in insulin sensitivity portrayed by augmentation of p-Akt and phospho-glycogen synthetase kinase 3β; 5) a reduced phosphorylation of p38-MAPK and ERK1/2; and 6) a decrease in diabetic dyslipidemia following lowering of intracellular events that govern lipoprotein assembly. These data suggest that AMPK fulfills key functions in metabolic processes in the small intestine.
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Affiliation(s)
- Elodie Harmel
- Research Center (E.H., E.G., A.B.O., M.E.C., A.S., S.S., E.L.), Sainte-Justine MUHC, Montreal, Quebec, Canada, H3T 1C5; Department of Nutrition (E.H., E.G., S.S., E.L.) and Department of Biochemistry (M.E.C.), Université de Montréal, Montreal, Quebec, Canada, H3T 1C5; Diabetes Unit (E.Z.), Division of Internal Medicine, Hadassah Ein Kerem Hospital, 120 Jerusalem, Israel-91; Canadian Institutes for Health Research Team on the Digestive Epithelium (J.F.B., E.L.), Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada, J1H 5N4; and CRNH Rhône-Alpes (E.H., M.L.), Université Lyon 1, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1060, CENS, Centre Hospitalier Lyon-Sud, F-69310 Pierre Bénite, France
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25
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Swick LL, Kazgan N, Onyenwoke RU, Brenman JE. Isolation of AMP-activated protein kinase (AMPK) alleles required for neuronal maintenance in Drosophila melanogaster. Biol Open 2013; 2:1321-3. [PMID: 24337116 PMCID: PMC3863416 DOI: 10.1242/bio.20136775] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The maintenance of energetic homeostasis in the face of limited available nutrients is a complex problem faced by all organisms. One important mechanism to maintain energetic homeostasis involves the activation of the energy sensor AMP-activated protein kinase (AMPK). AMPK is a cell-autonomous energy sensor that is highly sensitive to and regulated by the ATP to ADP and ATP to AMP ratios. However, the genetic analysis of AMPK signaling in vertebrates has been complicated by the existence of multiple redundant AMPK subunits. Here, we describe the identification of mutations in the single Drosophila melanogaster AMPK catalytic subunit (AMPKα) and their implications for neural maintenance and integrity. This article provides a citation replacement for previously published ampkα alleles, transgenes and neuronal phenotypes, which remain accurate; however, they were used in a previously published study that has subsequently been retracted (Mirouse et al., 2013).
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Affiliation(s)
- Lance L Swick
- Department of Cell Biology and Physiology, and Neuroscience Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
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26
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Miyamoto L, Egawa T, Oshima R, Kurogi E, Tomida Y, Tsuchiya K, Hayashi T. AICAR stimulation metabolome widely mimics electrical contraction in isolated rat epitrochlearis muscle. Am J Physiol Cell Physiol 2013; 305:C1214-22. [PMID: 24088893 DOI: 10.1152/ajpcell.00162.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Physical exercise has potent therapeutic and preventive effects against metabolic disorders. A number of studies have suggested that 5'-AMP-activated protein kinase (AMPK) plays a pivotal role in regulating carbohydrate and lipid metabolism in contracting skeletal muscles, while several genetically manipulated animal models revealed the significance of AMPK-independent pathways. To elucidate significance of AMPK and AMPK-independent signals in contracting skeletal muscles, we conducted a metabolomic analysis that compared the metabolic effects of 5-aminoimidazole-4-carboxamide-1-β-D-ribonucleoside (AICAR) stimulation with the electrical contraction ex vivo in isolated rat epitrochlearis muscles, in which both α1- and α2-isoforms of AMPK and glucose uptake were equally activated. The metabolomic analysis using capillary electrophoresis time-of-flight mass spectrometry detected 184 peaks and successfully annotated 132 small molecules. AICAR stimulation exhibited high similarity to the electrical contraction in overall metabolites. Principal component analysis (PCA) demonstrated that the major principal component characterized common effects whereas the minor principal component distinguished the difference. PCA and a factor analysis suggested a substantial change in redox status as a result of AMPK activation. We also found a decrease in reduced glutathione levels in both AICAR-stimulated and contracting muscles. The muscle contraction-evoked influences related to the metabolism of amino acids, in particular, aspartate, alanine, or lysine, are supposed to be independent of AMPK activation. Our results substantiate the significance of AMPK activation in contracting skeletal muscles and provide novel evidence that AICAR stimulation closely mimics the metabolomic changes in the contracting skeletal muscles.
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Affiliation(s)
- Licht Miyamoto
- Laboratory of Pharmacology and Physiological Sciences, Frontier Laboratory for Pharmaceutical Sciences, Institute of Health Biosciences, University of Tokushima Graduate School, Sho-machi, Tokushima, Japan
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Fraser SA, Choy SW, Pastor-Soler NM, Li H, Davies MRP, Cook N, Katerelos M, Mount PF, Gleich K, McRae JL, Dwyer KM, van Denderen BJW, Hallows KR, Kemp BE, Power DA. AMPK couples plasma renin to cellular metabolism by phosphorylation of ACC1. Am J Physiol Renal Physiol 2013; 305:F679-90. [PMID: 23785098 DOI: 10.1152/ajprenal.00407.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Salt reabsorption is the major energy-requiring process in the kidney, and AMP-activated protein kinase (AMPK) is an important regulator of cellular metabolism. Mice with targeted deletion of the β1-subunit of AMPK (AMPK-β1(-/-) mice) had significantly increased urinary Na(+) excretion on a normal salt diet. This was associated with reduced expression of the β-subunit of the epithelial Na(+) channel (ENaC) and increased subapical tubular expression of kidney-specific Na(+)-K(+)-2Cl(-) cotransporter 2 (NKCC2) in the medullary thick ascending limb of Henle. AMPK-β1(-/-) mice fed a salt-deficient diet were able to conserve Na(+), but renin secretion increased 180% compared with control mice. Cyclooxygenase-2 mRNA also increased in the kidney cortex, indicating greater signaling through the macula densa tubular salt-sensing pathway. To determine whether the increase in renin secretion was due to a change in regulation of fatty acid metabolism by AMPK, mice with a mutation of the inhibitory AMPK phosphosite in acetyl-CoA carboxylase 1 [ACC1-knockin (KI)(S79A) mice] were examined. ACC1-KI(S79A) mice on a normal salt diet had no increase in salt loss or renin secretion, and expression of NKCC2, Na(+)-Cl(-) cotransporter, and ENaC-β were similar to those in control mice. When mice were placed on a salt-deficient diet, however, renin secretion and cortical expression of cyclooxygenase-2 mRNA increased significantly in ACC1-KI(S79A) mice compared with control mice. In summary, our data suggest that renin synthesis and secretion are regulated by AMPK and coupled to metabolism by phosphorylation of ACC1.
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Affiliation(s)
- Scott A Fraser
- 1Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia
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Damm E, Buech TRH, Gudermann T, Breit A. Melanocortin-induced PKA activation inhibits AMPK activity via ERK-1/2 and LKB-1 in hypothalamic GT1-7 cells. Mol Endocrinol 2012; 26:643-54. [PMID: 22361823 DOI: 10.1210/me.2011-1218] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
α-Melanocyte-stimulating hormone (α-MSH)-induced activation of the melanocortin-4 receptor in hypothalamic neurons increases energy expenditure and inhibits food intake. Active hypothalamic AMP-activated protein kinase (AMPK) has recently been reported to enhance food intake, and in vivo experiments suggested that intrahypothalamic injection of melanocortins decreased food intake due to the inhibition of AMPK activity. However, it is not clear whether α-MSH affects AMPK via direct intracellular signaling cascades or if the release of paracrine factors is involved. Here, we used a murine, hypothalamic cell line (GT1-7 cells) and monitored AMPK phosphorylation at Thr(172), which has been suggested to increase AMPK activity. We found that α-MSH dephosphorylated AMPK at Thr(172) and consequently decreased phosphorylation of the established AMPK substrate acetyl-coenzyme A-carboxylase at Ser(79). Inhibitory effects of α-MSH on AMPK were blocked by specific inhibitors of protein kinase A (PKA) or ERK-1/2, pointing to an important role of both kinases in this process. Because α-MSH-induced activation of ERK-1/2 was blunted by PKA inhibitors, we propose that ERK-1/2 serves as a link between PKA and AMPK in GT1-7 cells. Furthermore, down-regulation of liver kinase B-1, but not inhibition of calcium-calmodulin-dependent kinase kinase-β or TGFβ-activated kinase-1 decreased basal phosphorylation of AMPK and its dephosphorylation induced by α-MSH. Thus, we propose that α-MSH inhibits AMPK activity via a linear pathway, including PKA, ERK-1/2, and liver kinase B-1 in GT1-7 cells. Given the importance of the melanocortin system in the formation of adipositas, detailed knowledge about this pathway might help to develop drugs targeting obesity.
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Affiliation(s)
- Ellen Damm
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität, Goethestrasse 33, 80336 München, Germany
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Onyenwoke RU, Forsberg LJ, Liu L, Williams T, Alzate O, Brenman JE. AMPK directly inhibits NDPK through a phosphoserine switch to maintain cellular homeostasis. Mol Biol Cell 2011; 23:381-9. [PMID: 22114351 PMCID: PMC3258181 DOI: 10.1091/mbc.e11-08-0699] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nucleoside diphosphate kinase (NDPK) is a direct target of AMP-activated protein kinase (AMPK) and is inhibited by AMPK-mediated phosphorylation at a conserved serine residue. This serine residue in NDPK is mutated in neuroblastoma, making the enzyme constitutively active. AMP-activated protein kinase (AMPK) is a key energy sensor that regulates metabolism to maintain cellular energy balance. AMPK activation has also been proposed to mimic benefits of caloric restriction and exercise. Therefore, identifying downstream AMPK targets could elucidate new mechanisms for maintaining cellular energy homeostasis. We identified the phosphotransferase nucleoside diphosphate kinase (NDPK), which maintains pools of nucleotides, as a direct AMPK target through the use of two-dimensional differential in-gel electrophoresis. Furthermore, we mapped the AMPK/NDPK phosphorylation site (serine 120) as a functionally potent enzymatic “off switch” both in vivo and in vitro. Because ATP is usually the most abundant cellular nucleotide, NDPK would normally consume ATP, whereas AMPK would inhibit NDPK to conserve energy. It is intriguing that serine 120 is mutated in advanced neuroblastoma, which suggests a mechanism by which NDPK in neuroblastoma can no longer be inhibited by AMPK-mediated phosphorylation. This novel placement of AMPK upstream and directly regulating NDPK activity has widespread implications for cellular energy/nucleotide balance, and we demonstrate in vivo that increased NDPK activity leads to susceptibility to energy deprivation–induced death.
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Affiliation(s)
- Rob U Onyenwoke
- Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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Lee KM, Jo S, Kim H, Lee J, Park CS. Functional modulation of AMP-activated protein kinase by cereblon. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:448-55. [DOI: 10.1016/j.bbamcr.2011.01.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 12/23/2010] [Accepted: 01/03/2011] [Indexed: 11/15/2022]
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Kazgan N, Williams T, Forsberg LJ, Brenman JE. Identification of a nuclear export signal in the catalytic subunit of AMP-activated protein kinase. Mol Biol Cell 2010; 21:3433-42. [PMID: 20685962 PMCID: PMC2947478 DOI: 10.1091/mbc.e10-04-0347] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In this study, we utilized genetic and cell biological approaches to evaluate potential functions for the AMPKα C-terminus. We identify a critical new function for the carboxy-terminal amino acids of AMPKα in vivo, which affects AMPKα subcellular localization, phosphorylation, and ultimately organismal viability. The metabolic regulator AMP-activated protein kinase (AMPK) maintains cellular homeostasis through regulation of proteins involved in energy-producing and -consuming pathways. Although AMPK phosphorylation targets include cytoplasmic and nuclear proteins, the precise mechanisms that regulate AMPK localization, and thus its access to these substrates, are unclear. We identify highly conserved carboxy-terminal hydrophobic amino acids that function as a leptomycin B–sensitive, CRM1-dependent nuclear export sequence (NES) in the AMPK catalytic subunit (AMPKα). When this sequence is modified AMPKα shows increased nuclear localization via a Ran-dependent import pathway. Cytoplasmic localization can be restored by substituting well-defined snurportin-1 or protein kinase A inhibitor (PKIA) CRM1-binding NESs into AMPKα. We demonstrate a functional requirement in vivo for the AMPKα carboxy-terminal NES, as transgenic Drosophila expressing AMPKα lacking this NES fail to rescue lethality of AMPKα null mutant flies and show decreased activation loop phosphorylation under heat-shock stress. Sequestered to the nucleus, this truncated protein shows highly reduced phosphorylation at the key Thr172 activation residue, suggesting that AMPK activation predominantly occurs in the cytoplasm under unstressed conditions. Thus, modulation of CRM1-mediated export of AMPKα via its C-terminal NES provides an additional mechanism for cells to use in the regulation of AMPK activity and localization.
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Affiliation(s)
- Nevzat Kazgan
- Neuroscience Center, University of North Carolina Chapel Hill School of Medicine, Chapel Hill, NC 27599-7250, USA
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32
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Lopaschuk GD, Ussher JR, Jaswal JS. Targeting intermediary metabolism in the hypothalamus as a mechanism to regulate appetite. Pharmacol Rev 2010; 62:237-64. [PMID: 20392806 DOI: 10.1124/pr.109.002428] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The central nervous system mediates energy balance (energy intake and energy expenditure) in the body; the hypothalamus has a key role in this process. Recent evidence has demonstrated an important role for hypothalamic malonyl CoA in mediating energy balance. Malonyl CoA is generated by the carboxylation of acetyl CoA by acetyl CoA carboxylase and is then either incorporated into long-chain fatty acids by fatty acid synthase, or converted back to acetyl-CoA by malonyl CoA decarboxylase. Increased hypothalamic malonyl CoA is an indicator of energy surplus, resulting in a decrease in food intake and an increase in energy expenditure. In contrast, a decrease in hypothalamic malonyl CoA signals an energy deficit, resulting in an increased appetite and a decrease in body energy expenditure. A number of hormonal and neural orexigenic and anorexigenic signaling pathways have now been shown to be associated with changes in malonyl CoA levels in the arcuate nucleus (ARC) of the hypothalamus. Despite compelling evidence that malonyl CoA is an important mediator in the hypothalamic ARC control of food intake and regulation of energy balance, the mechanism(s) by which this occurs has not been established. Malonyl CoA inhibits carnitine palmitoyltransferase-1 (CPT-1), and it has been proposed that the substrate of CPT-1, long-chain acyl CoA(s), may act as a mediator(s) of appetite and energy balance. However, recent evidence has challenged the role of long-chain acyl CoA(s) in this process, as well as the involvement of CPT-1 in hypothalamic malonyl CoA signaling. A better understanding of how malonyl CoA regulates energy balance should provide novel approaches to targeting intermediary metabolism in the hypothalamus as a mechanism to control appetite and body weight. Here, we review the data supporting an important role for malonyl CoA in mediating hypothalamic control of energy balance, and recent evidence suggesting that targeting malonyl CoA synthesis or degradation may be a novel approach to favorably modify appetite and weight gain.
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Affiliation(s)
- Gary D Lopaschuk
- 423 Heritage Medical Research Center, University of Alberta, Edmonton, Canada T6G2S2.
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Abstract
AMP-activated protein kinase (AMPK) is a serine threonine kinase that is highly conserved through evolution. AMPK is found in most mammalian tissues including the brain. As a key metabolic and stress sensor/effector, AMPK is activated under conditions of nutrient deprivation, vigorous exercise, or heat shock. However, it is becoming increasingly recognized that changes in AMPK activation not only signal unmet metabolic needs, but also are involved in sensing and responding to 'cell stress', including ischemia. The downstream effect of AMPK activation is dependent on many factors, including the severity of the stressor as well as the tissue examined. This review discusses recent in vitro and in vivo studies performed in the brain/neuronal cells and vasculature that have contributed to our understanding of AMPK in stroke. Recent data on the potential role of AMPK in angiogenesis and neurogenesis and the interaction of AMPK with 3-hydroxy-3-methy-glutaryl-CoA reductase inhibitors (statins) agents are highlighted. The interaction between AMPK and nitric oxide signaling is also discussed.
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Affiliation(s)
- Jun Li
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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Lopaschuk GD, Ussher JR, Folmes CDL, Jaswal JS, Stanley WC. Myocardial fatty acid metabolism in health and disease. Physiol Rev 2010; 90:207-58. [PMID: 20086077 DOI: 10.1152/physrev.00015.2009] [Citation(s) in RCA: 1459] [Impact Index Per Article: 104.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
There is a constant high demand for energy to sustain the continuous contractile activity of the heart, which is met primarily by the beta-oxidation of long-chain fatty acids. The control of fatty acid beta-oxidation is complex and is aimed at ensuring that the supply and oxidation of the fatty acids is sufficient to meet the energy demands of the heart. The metabolism of fatty acids via beta-oxidation is not regulated in isolation; rather, it occurs in response to alterations in contractile work, the presence of competing substrates (i.e., glucose, lactate, ketones, amino acids), changes in hormonal milieu, and limitations in oxygen supply. Alterations in fatty acid metabolism can contribute to cardiac pathology. For instance, the excessive uptake and beta-oxidation of fatty acids in obesity and diabetes can compromise cardiac function. Furthermore, alterations in fatty acid beta-oxidation both during and after ischemia and in the failing heart can also contribute to cardiac pathology. This paper reviews the regulation of myocardial fatty acid beta-oxidation and how alterations in fatty acid beta-oxidation can contribute to heart disease. The implications of inhibiting fatty acid beta-oxidation as a potential novel therapeutic approach for the treatment of various forms of heart disease are also discussed.
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Affiliation(s)
- Gary D Lopaschuk
- Cardiovascular Research Group, Mazankowski Alberta Heart Institute, University of Alberta, Alberta T6G 2S2, Canada.
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Williams T, Forsberg LJ, Viollet B, Brenman JE. Basal autophagy induction without AMP-activated protein kinase under low glucose conditions. Autophagy 2009; 5:1155-65. [PMID: 19844161 DOI: 10.4161/auto.5.8.10090] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
When ATP levels in a cell decrease, various homeostatic intracellular mechanisms initiate attempts to restore ATP levels. As a prominent energy sensor, AMP-activated protein kinase (AMPK) represents one molecular gauge that links energy levels to regulation of anabolic and catabolic processes to restore energy balance. Although pharmacological studies have suggested that an AMPK activator, AIC AR (5-aminoimidazole-4-carboxamide ribonucleoside) may link AMPK activation to autophagy, a process that can provide short-term energy within the cell, AICAR can have AMPK-independent effects. Therefore, using a genetic-based approach we investigated the role of AMPK in cellular energy balance. We demonstrate that genetically altered cells, mouse embryonic fibroblasts (MEFs), lacking functional AMPK, display altered energy balance under basal conditions and die prematurely under low glucose-serum starvation challenge. These AMPK mutant cells appear to be abnormally reliant on autophagy under low glucose basal conditions, and therefore cannot rely further on autophagy like wild-type cells during further energetic stress and instead undergo apoptosis. This data suggests that AMPK helps regulate basal energy levels under low glucose. Further, AMPK mutant cells show increased basal phosphorylation of p53 at serine 15, a residue phosphorylated under glucose deprivation. We propose that cells lacking AMPK function have altered p53 activity that may help sensitize these cells to apoptosis under energetic stress.
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Affiliation(s)
- Tyisha Williams
- The Neuroscience Center UNC Chapel Hill School of Medicine, USA
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36
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Abstract
The function and survival of all organisms is dependent on the dynamic control of energy metabolism, when energy demand is matched to energy supply. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals that control energy balance through the regulation of multiple biochemical pathways in all eukaryotes. In this review, we begin with the discovery of the AMPK family and discuss the recent structural studies that have revealed the molecular basis for AMP binding to the enzyme's gamma subunit. AMPK's regulation involves autoinhibitory features and phosphorylation of both the catalytic alpha subunit and the beta-targeting subunit. We review the role of AMPK at the cellular level through examination of its many substrates and discuss how it controls cellular energy balance. We look at how AMPK integrates stress responses such as exercise as well as nutrient and hormonal signals to control food intake, energy expenditure, and substrate utilization at the whole body level. Lastly, we review the possible role of AMPK in multiple common diseases and the role of the new age of drugs targeting AMPK signaling.
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Affiliation(s)
- Gregory R Steinberg
- Protein Chemistry and Metabolism, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia.
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Folmes KD, Chan AYM, Koonen DPY, Pulinilkunnil TC, Baczkó I, Hunter BE, Thorn S, Allard MF, Roberts R, Gollob MH, Light PE, Dyck JRB. Distinct early signaling events resulting from the expression of the PRKAG2 R302Q mutant of AMPK contribute to increased myocardial glycogen. ACTA ACUST UNITED AC 2009; 2:457-66. [PMID: 20031621 DOI: 10.1161/circgenetics.108.834564] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Humans with an R302Q mutation in AMPKgamma(2) (the PRKAG2 gene) develop a glycogen storage cardiomyopathy characterized by a familial form of Wolff-Parkinson-White syndrome and cardiac hypertrophy. This phenotype is recapitulated in transgenic mice with cardiomyocyte-restricted expression of AMPKgamma(2)R302Q. Although considerable information is known regarding the consequences of harboring the gamma(2)R302Q mutation, little is known about the early signaling events that contribute to the development of this cardiomyopathy. METHODS AND RESULTS To distinguish the direct effects of gamma(2)R302Q expression from later compensatory alterations in signaling, we used transgenic mice expressing either the wild-type AMPKgamma(2) subunit (TGgamma(2)WT) or the mutated form (TGgamma(2)R302Q), in combination with acute expression of these proteins in neonatal rat cardiomyocytes. Although acute expression of gamma(2)R302Q induces AMPK activation and upregulation of glycogen synthase and AS160, with an associated increase in glycogen content, AMPK activity, glycogen synthase activity, and AS160 expression are reduced in hearts from TGgamma(2)R302Q mice, likely in response to the existing 37-fold increase in glycogen. Interestingly, gamma(2)WT expression has similar, yet less marked effects than gamma(2)R302Q expression in both cardiomyocytes and hearts. CONCLUSIONS Using acute and chronic models of gamma(2)R302Q expression, we have differentiated the direct effects of the gamma(2)R302Q mutation from eventual compensatory modifications. Our data suggest that expression of gamma(2)R302Q induces AMPK activation and the eventual increase in glycogen content, a finding that is masked in hearts from transgenic adult mice. These findings are the first to highlight temporal differences in the effects of the PRKAG2 R302Q mutation on cardiac metabolic signaling events.
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Affiliation(s)
- Karalyn D Folmes
- Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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38
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Garcia-Roves PM, Osler ME, Holmström MH, Zierath JR. Gain-of-function R225Q mutation in AMP-activated protein kinase gamma3 subunit increases mitochondrial biogenesis in glycolytic skeletal muscle. J Biol Chem 2008; 283:35724-34. [PMID: 18838377 DOI: 10.1074/jbc.m805078200] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a heterotrimeric complex, composed of a catalytic subunit (alpha) and two regulatory subunits (beta and gamma), that works as a cellular energy sensor. The existence of multiple heterotrimeric complexes provides a molecular basis for the multiple roles of this highly conserved signaling system. The AMPK gamma3 subunit is predominantly expressed in skeletal muscle, mostly in type II glycolytic fiber types. We determined whether the AMPK gamma3 subunit has a role in signaling pathways that mediate mitochondrial biogenesis in skeletal muscle. We provide evidence that overexpression or ablation of the AMPK gamma3 subunit does not appear to play a critical role in defining mitochondrial content in resting skeletal muscle. However, overexpression of a mutant form (R225Q) of the AMPK gamma3 subunit (Tg-AMPKgamma3(225Q)) increases mitochondrial biogenesis in glycolytic skeletal muscle. These adaptations are associated with an increase in expression of the co-activator PGC-1alpha and several transcription factors that regulate mitochondrial biogenesis, including NRF-1, NRF-2, and TFAM. Succinate dehydrogenase staining, a marker of the oxidative profile of individual fibers, was also increased in transversal skeletal muscle sections of white gastrocnemius muscle from Tg-AMPKgamma3(225Q) mice, independent of changes in fiber type composition. In conclusion, a single nucleotide mutation (R225Q) in the AMPK gamma3 subunit is associated with mitochondrial biogenesis in glycolytic skeletal muscle, concomitant with increased expression of the co-activator PGC-1alpha and several transcription factors that regulate mitochondrial proteins, without altering fiber type composition.
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Affiliation(s)
- Pablo M Garcia-Roves
- Department of Molecular Medicine and Surgery, Section Integrative Physiology, Karolinska Institutet, von Eulers Väg 4, 4th Floor, S-171 77 Stockholm, Sweden
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Khanna V, Arumugam S, Roy S, Mittra S, Bansal VS. Topiramate and type 2 diabetes: an old wine in a new bottle. Expert Opin Ther Targets 2008; 12:81-90. [PMID: 18076372 DOI: 10.1517/14728222.12.1.81] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Topiramate, a marketed antiepileptic drug, has been used to treat seizures and allied neurological problems since 1999. Recently, a series of newer findings for the use of topiramate have cropped up, which include Type 2 diabetes and obesity. In a series of clinical studies, a subset of neurological patients with Type 2 diabetes mellitus (T2DM) serendipitously showed better glycaemic control when treated with topiramate. It has since been demonstrated that topiramate can act both as an insulin secretagogue and sensitiser in T2DM animal models. Pathogenesis of Type 2 diabetes involves both beta-cell dysfunction and insulin resistance. Therefore, an agent that has dual action (insulin secretagougue and sensitisation) is preferred for T2DM. Topiramate seems to act through multiple mechanisms to ameliorate diabetic symptoms, some of them unknown. Hence, it becomes imperative to discuss its probable modes of action. Topiramate raises new hope as an antidiabetic agent or a potential new chemotype with a better safety profile for the treatment of T2DM.
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Affiliation(s)
- Vivek Khanna
- Ranbaxy Research Laboratories, Department of Pharmacology, New Drug Discovery Research, R&D III, Plot No. 20, Sector 18, Udyog Vihar Industrial Area, Gurgaon-122015, Haryana, India.
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40
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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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41
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Deshmukh AS, Treebak JT, Long YC, Viollet B, Wojtaszewski JFP, Zierath JR. Role of adenosine 5'-monophosphate-activated protein kinase subunits in skeletal muscle mammalian target of rapamycin signaling. Mol Endocrinol 2008; 22:1105-12. [PMID: 18276828 DOI: 10.1210/me.2007-0448] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an important energy-sensing protein in skeletal muscle. Mammalian target of rapamycin (mTOR) mediates translation initiation and protein synthesis through ribosomal S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). AMPK activation reduces muscle protein synthesis by down-regulating mTOR signaling, whereas insulin mediates mTOR signaling via Akt activation. We hypothesized that AMPK-mediated inhibitory effects on mTOR signaling depend on catalytic alpha2 and regulatory gamma3 subunits. Extensor digitorum longus muscle from AMPK alpha2 knockout (KO), AMPK gamma3 KO, and respective wild-type (WT) littermates (C57BL/6) were incubated in the presence of 5-aminoimidazole-4-carboxamide-1-beta-d-ribonucleoside (AICAR), insulin, or AICAR plus insulin. Phosphorylation of AMPK, Akt, and mTOR-associated signaling proteins were assessed. Insulin increased Akt Ser473 phosphorylation (P < 0.01), irrespective of genotype or presence of AICAR. AICAR increased phosphorylation of AMPK Thr172 (P < 0.01) in WT but not KO mice. Insulin stimulation increased phosphorylation of S6K1 (Thr389), ribosomal protein S6 (Ser235/236), and 4E-BP1 (Thr37/46) (P < 0.01) in WT, AMPK alpha2 KO, and AMPK gamma3 KO mice. However, in WT mice, preincubation with AICAR completely inhibited insulin-induced phosphorylation of mTOR targets, suggesting mTOR signaling is blocked by prior AMPK activation. The AICAR-induced inhibition was partly rescued in extensor digitorum longus muscle from either alpha2 or gamma3 AMPK KO mice, indicating functional alpha2 and gamma3 subunits of AMPK are required for the reduction in mTOR signaling. AICAR alone was without effect on basal phosphorylation of S6K1 (Thr389), ribosomal protein S6 (Ser235/236), and 4E-BP1 (Thr37/46). In conclusion, functional alpha2 and gamma3 AMPK subunits are required for AICAR-induced inhibitory effects on mTOR signaling.
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Affiliation(s)
- Atul S Deshmukh
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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42
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Physiological glucose is critical for optimized neuronal viability and AMPK responsiveness in vitro. J Neurosci Methods 2007; 167:292-301. [PMID: 17936912 DOI: 10.1016/j.jneumeth.2007.08.028] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Revised: 08/27/2007] [Accepted: 08/28/2007] [Indexed: 02/04/2023]
Abstract
Understanding the mechanisms that govern neuronal responses to oxidative and metabolic stress is essential for therapeutic intervention. In vitro modeling is an important approach for these studies, as the metabolic environment influences neuronal responses. Surprisingly, most neuronal culture methods employ conditions that are non-physiological, especially with regards to glucose concentrations, which often exceed 20mM. This concentration is a significant departure from physiological glucose levels, and even several-fold greater than that seen during severe hyperglycemia. The goal of this study was to establish a physiological neuronal culture system that will facilitate the study of neuronal energy metabolism and responses to metabolic stress. We demonstrate that the metabolic environment during preparation, plating, and maintenance of cultures affects neuronal viability and the response of neuronal pathways to changes in energy balance.
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Abstract
Despite the fact that the heart requires huge amounts of energy to sustain contractile function, it has limited energy reserves and must therefore continually produce large amounts of adenosine triphosphate (ATP) to sustain function. Fatty acids are the primary energy substrate of the adult heart, with more than 60% of the energy normally obtained from the oxidation of fatty acids, the remainder coming from the metabolism of carbohydrates. Alterations in both the rates of ATP production and the type of energy substrate used by the heart can have consequences on contractile function, as well as on its ability to respond to energetic stresses. Switches in myocardial substrate utilization and energy production rates have been shown to occur in various cardiomyopathies, as well as in any subsequent heart failure. Heart failure is characterized by an inefficient pumping of the heart, which fails to meet the energy requirements of the body. A number of cardiomyopathies can lead to heart failure. This paper will review the alterations in energy metabolism that occur in a number cardiomyopathies, including ischemic and diabetic cardiomyopathies, as well as hypertrophic cardiomyopathies resulting from mutations in enzymes involved in energy metabolism, such as 5' adenosine monophosphate-activated protein kinase (AMPK).
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Affiliation(s)
- Maysa Taha
- Cardiovascular Research Group, University of Alberta, Edmonton, Alberta, Canada
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44
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Pang T, Xiong B, Li JY, Qiu BY, Jin GZ, Shen JK, Li J. Conserved α-Helix Acts as Autoinhibitory Sequence in AMP-activated Protein Kinase α Subunits. J Biol Chem 2007; 282:495-506. [PMID: 17088252 DOI: 10.1074/jbc.m605790200] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK) acts as an energy sensor, being activated by metabolic stresses and regulating cellular metabolism. AMPK is a heterotrimer consisting of a catalytic alpha subunit and two regulatory subunits, beta and gamma. It had been reported that the mammalian AMPK alpha subunit contained an autoinhibitory domain (alpha1: residues 313-392) and had little kinase activity. We have found that a conserved short segment of the alpha subunit (alpha1-(313-335)), which includes a predicted alpha-helix, is responsible for alpha subunit autoinhibition. The role of the residues in this segment for autoinhibition was further investigated by systematic site-directed mutation. Several hydrophobic and charged residues, in particular Leu-328, were found to be critical for alpha1 autoinhibition. An autoinhibitory structural model of human AMPK alpha1-(1-335) was constructed and revealed that Val-298 interacts with Leu-328 through hydrophobic bonding at a distance of about 4 A and may stabilize the autoinhibitory conformation. Further mutation analysis showed that V298G mutation significantly activated the kinase activity. Moreover, the phosphorylation level of acetyl-CoA carboxylase, the AMPK downstream substrate, was significantly increased in COS7 cells overexpressing AMPK alpha1-(1-394) with deletion of residues 313-335 (Deltaalpha394) and a V298G or L328Q mutation, and the glucose uptake was also significantly enhanced in HepG2 cells transiently transfected with Deltaalpha394, V298G, or L328Q mutants, which indicated that these AMPK alpha1 mutants are constitutively active in mammalian cells and that interaction between Leu-328 and Val-298 plays an important role in AMPK alpha autoinhibitory function.
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Affiliation(s)
- Tao Pang
- Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai 201203, China
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45
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Brenman JE, Temple BRS. Opinion: alternative views of AMP-activated protein kinase. Cell Biochem Biophys 2007; 47:321-31. [PMID: 17652778 DOI: 10.1007/s12013-007-0005-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/30/2022]
Abstract
Genes most closely related to adenosine monophosphate (AMP)-activated protein kinase, including SAD kinases and Par-1 regulate cell polarity, although AMP-activated protein kinase (AMPK) modulates cellular energy status. LKB1 (Par-4) is required for normal activation of AMPK in the liver and also regulates cell polarity. AMPK is proposed to inhibit energy consuming activity while initiating energy producing activity during energy limitation. Demonstration that metformin, a common drug for Type 2 diabetes, requires LKB1 for full therapeutic benefit has increased interest in AMPK signaling. Despite the potential importance of AMPK signaling for diabetes, metabolic syndrome and even cancer, the developmental processes regulated by AMPK in genetically mutant animals require further elucidation. Mouse conditional null mutants for AMPK activity will allow genetic elucidation of AMPK function in vivo. This perspective focuses on sequence and structural moieties of AMPK and genetic analysis of AMPK mutations. Interestingly, the predicted protein structure of the carboxy-terminus of AMPKalpha resembles the carboxy-terminal KA-1 domain of MARK3, a Par-1 orthologue.
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Affiliation(s)
- Jay E Brenman
- Department of Cell and Developmental Biology and Neuroscience Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA.
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46
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Niesler CU, Myburgh KH, Moore F. The changing AMPK expression profile in differentiating mouse skeletal muscle myoblast cells helps confer increasing resistance to apoptosis. Exp Physiol 2006; 92:207-17. [PMID: 16945942 DOI: 10.1113/expphysiol.2006.034736] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
AMP-activated protein kinase (AMPK) functions as a alpha/beta/gamma heterotrimer to preserve ATP levels and so cell viability during stressful conditions. However, its role in aiding survival of adult skeletal muscle precursor cells is unclear. Using the differentiating mouse C2C12 postnatal skeletal muscle myoblast cell line, we have determined that proteins for the AMPK subunit isoforms alpha2 and gamma2 are constitutively expressed, while those for alpha1, beta1 and beta2 are undetectable in undifferentiated myoblasts but increasingly expressed with differentiation to myotubes. Although the gamma3 subunit is expressed at a low level in myoblasts, it too is expressed increasingly with differentiation to myotubes. The p50 but not the p72 isoform of the embryonic alpha subunit homologue MELK is expressed only in proliferating myoblasts, while the ARK5 alpha subunit homologue is increasingly expressed with differentiation. Myotubes displayed higher basal and stimulated alpha1/alpha2 AMPK activation than myoblasts. Furthermore, serum starvation resulted in less apoptosis of differentiated myotubes than of undifferentiated myoblasts. This reflects, in part, the increased expression of functional AMPK in the myotubes, since specific inhibition of AMPK activity with 6-[4-(2-piperidin-1-ylethoxy)-phenyl]-3-pyridin-4-ylpyrazolo[1,5-alpha] pyrimidine (Compound C) exacerbated the apoptosis resulting from serum withdrawal. If these in vitro events can also occur in vivo, they could have implications for pathologies such as muscle wasting, in which undifferentiated satellite stem cells may be easier apoptotic targets than their differentiated counterparts. Furthermore, these results suggest that when interpreting results from in vitro or in vivo experiments on AMPK, the subunit expression profile should be taken into account.
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Affiliation(s)
- Carola U Niesler
- Hormone and Metabolic Research Unit, Christian de Duve Institute of Cellular Pathology, University of Louvain Medical School, ICP-UCL 7529, Avenue Hippocrate 75, B-1200 Brussels, Belgium
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Abstract
The heart is capable of utilizing a variety of substrates to produce the necessary ATP for cardiac function. AMP-activated protein kinase (AMPK) has emerged as a key regulator of cellular energy homeostasis and coordinates multiple catabolic and anabolic pathways in the heart. During times of acute metabolic stresses, cardiac AMPK activation seems to be primarily involved in increasing energy-generating pathways to maintain or restore intracellular ATP levels. In acute situations such as mild ischemia or short durations of severe ischemia, activation of cardiac AMPK appears to be necessary for cardiac myocyte function and survival by stimulating ATP generation via increased glycolysis and accelerated fatty acid oxidation. Whereas AMPK activation may be essential for adaptation of cardiac energy metabolism to acute and/or minor metabolic stresses, it is unknown whether AMPK activation becomes maladaptive in certain chronic disease states and/or extreme energetic stresses. However, alterations in cardiac AMPK activity are associated with a number of cardiovascular-related diseases such as pathological cardiac hypertrophy, myocardial ischemia, glycogen storage cardiomyopathy, and Wolff-Parkinson-White syndrome, suggesting the possibility of a maladaptive role. Although the precise role AMPK plays in the diseased heart is still in question, it is clear that AMPK is a major regulator of cardiac energy metabolism. The consequences of alterations in AMPK activity and subsequent cardiac energy metabolism in the healthy and the diseased heart will be discussed.
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Affiliation(s)
- Vernon W Dolinsky
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
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48
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Kanellis J, Kandane RK, Etemadmoghadam D, Fraser SA, Mount PF, Levidiotis V, Kemp BE, Power DA. Activators of the energy sensing kinase AMPK inhibit random cell movement and chemotaxis in U937 cells. Immunol Cell Biol 2006; 84:6-12. [PMID: 16405649 DOI: 10.1111/j.1440-1711.2005.01388.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AMP-activated protein kinase (AMPK) is a key energy sensor, known to regulate energy metabolism in diverse cell types. Hypoxia is encountered frequently in the microenvironments of inflammatory lesions and is a critical regulator of function in inflammatory cells. Energy deficiency is one of the consequences of hypoxia, but its potential role in modulating leucocyte function has received little attention. Using micropore chemotaxis assays to assess migratory responses of the monocyte-like cell line U937, it was found that the AMPK activators AICAR and phenformin rapidly reduced random migration (chemokinesis) as well as chemotaxis due to stromal cell-derived factor (SDF)1alpha. There was an approximate 50% reduction in both chemokinesis and chemotaxis following 30 min preincubation with both AICAR and phenformin (P < 0.01), and this continued with up to 24 h preincubation. The binding of SDF1alpha to its receptor CXCR4 was unaltered, suggesting AMPK was acting on downstream intracellular signalling pathways important in cell migration. As AMPK and statins are known to inhibit HMG CoA reductase, and both reduce cell migration, the effect of mevastatin on U937 cells was compared with AMPK activators. Mevastatin inhibited cell migration but required 24 h preincubation. As expected, the inhibitory effect of mevastatin was associated with altered subcellular localization of the Rho GTPases, RhoA and cdc42, indicating decreased prenylation of these molecules. Although the effect of AMPK activation was partially reversed by mevalonate, this was not associated with altered subcellular localization of Rho GTPases. The data suggest that activation of AMPK has a general effect on cell movement in U937 cells, and this is not due to inhibition of HMG CoA reductase. These are the first data to show an effect of AMPK on cell movement, and suggest a fundamental role for energy deficiency in regulating cellular behaviour.
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Affiliation(s)
- John Kanellis
- Department of Nephrology, Austin Hospital, Melbourne, Victoria, Australia
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49
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Tosca L, Solnais P, Ferré P, Foufelle F, Dupont J. Metformin-induced stimulation of adenosine 5' monophosphate-activated protein kinase (PRKA) impairs progesterone secretion in rat granulosa cells. Biol Reprod 2006; 75:342-51. [PMID: 16760380 DOI: 10.1095/biolreprod.106.050831] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Metformin is an anti-diabetic drug commonly used to treat cycle disorders and anovulation in women with polycystic ovary syndrome. However, the effects and molecular mechanism of metformin in the ovary are not entirely understood. We investigated the effects of this drug on steroidogenesis and proliferation in rat granulosa cells. Metformin (10 mM) treatment for 48 h reduced progesterone and estradiol (E2) production in both basal conditions and under FSH stimulation. It also decreased the levels of the HSD3B, CYP11A1, STAR, and CYP19A1 proteins in response to FSH (10(-8) M) and of HSD3B in the basal state only. Metformin treatment (10 mM, 24 h) also reduced cell proliferation and the levels of CCND2 and CCNE proteins without affecting cell viability, both in the basal state and in response to FSH. Furthermore, metformin treatment for 1 h simultaneously increased the Thr172 phosphorylation of PRKAA (adenosine 5' monophosphate-activated protein kinase alpha) and the Ser79 phosphorylation of ACACA (acetyl-Coenzyme A carboxylase alpha). The adenovirus-mediated production of dominant-negative PRKAA totally abolished the effects of metformin on progesterone secretion, HSD3B and STAR protein production, and MAPK3/1 phosphorylation. Conversely, total inhibition of PRKAA Thr172 phosphorylation with the dominant-negative PRKAA adenovirus did not restore the decrease in E2 production and cell proliferation induced by metformin. Our results therefore strongly suggest that metformin reduces progesterone production via a PRKAA-dependent mechanism, whereas PRKAA activation is not essential for the decrease in E2 production and cell growth induced by metformin in rat granulosa cells.
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Affiliation(s)
- Lucie Tosca
- Unité de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
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50
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Abstract
AMP-activated protein kinase (AMPK) has emerged as a key regulator of energy metabolism in the heart. The high energy demands of the heart are primarily met by the metabolism of both fatty acids and glucose, both processes being regulated by AMPK. During myocardial ischaemia a rapid activation of AMPK occurs, resulting in an activation of both glucose uptake and glycolysis, as well as an increase in fatty acid oxidation. This activation of AMPK has the potential to increase energy production and to inhibit apoptosis, thereby protecting the heart during the ischaemic stress. However, at clinically relevant high levels of fatty acids, ischaemic-induced activation of AMPK also stimulates fatty acid oxidation during and following ischaemia. This can contribute to ischaemic injury secondary to an inhibition of glucose oxidation, which results in a decrease in cardiac efficiency. In a number of other non-cardiac tissues, AMPK has been shown to have pro-apoptotic effects. As a result, the question of whether AMPK activation benefits or harms the ischaemic heart remains controversial. The role of AMPK in cardiac hypertrophy is also controversial. Activation of AMPK inhibits protein synthesis, and may be an adaptive response to pathological cardiac hypertrophy. However, none of mouse models of AMPK deficiency (excluding those that may involve the gamma2 subunit mutations) demonstrate increased cardiac mass, suggesting that AMPK is not essential for restriction of cardiac growth. In addition to the potential effects of AMPK on myofibrillar hypertrophy associated with pressure overload, there is also controversy with respect to the cardiac hypertrophy associated with the gamma2 subunit mutations. In the cardiac hypertrophy associated with glycogen overload, both activating and inactivating mutations of AMPK in mice are associated with a marked cardiac hypertrophy. This review will address the issue of whether AMPK activation acts as an enemy or ally to the ischaemic and hypertrophied heart. Resolving this issue has important implications as to whether therapeutic approaches to protect the ischaemic heart should be developed which either activate or inhibit AMPK.
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Affiliation(s)
- Jason R B Dyck
- Cardiovascular Research Group, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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