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Lu J, Huang Y, Zhan L, Wang M, Xu L, Mullen M, Zang J, Fang G, Dou Z, Liu X, Liu W, Garcia-Barrio M, Yao X. AMPKα2 activation by an energy-independent signal ensures chromosomal stability during mitosis. iScience 2021; 24:102363. [PMID: 33898950 PMCID: PMC8059055 DOI: 10.1016/j.isci.2021.102363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 02/15/2021] [Accepted: 03/23/2021] [Indexed: 12/13/2022] Open
Abstract
AMP-activated protein kinase (AMPK) senses energy status and impacts energy-consuming events by initiating metabolism regulatory signals in cells. Accumulating evidences suggest a role of AMPK in mitosis regulation, but the mechanism of mitotic AMPK activation and function remains elusive. Here we report that AMPKα2, but not AMPKα1, is sequentially phosphorylated and activated by CDK1 and PLK1, which enables AMPKα2 to accurately guide chromosome segregation in mitosis. Phosphorylation at Thr485 by activated CDK1-Cyclin B1 brings the ST-stretch of AMPKα2 to the Polo box domain of PLK1 for subsequent Thr172 phosphorylation by PLK1. Inserting of the AMPKα2 ST-stretch into AMPKα1, which lacks the ST-stretch, can correct mitotic chromosome segregation defects in AMPKα2-depleted cells. These findings uncovered a specific signaling cascade integrating sequential phosphorylation by CDK1 and PLK1 of AMPKα2 with mitosis to maintain genomic stability, thus defining an isoform-specific AMPKα2 function, which will facilitate future research on energy sensing in mitosis. AMPKα2 is selectively activated during mitosis by CDK1 and PLK1 A conserved motif in AMPKα2 determines its interaction with and activation by PLK1 Mitotic AMPK activation contributes to maintain genomic stability in normal mitosis
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Affiliation(s)
- Jianlin Lu
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
- Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, CAS Center for Excellence in Molecular Cell Science & Hefei National Science Center for Physical Sciences at Microscale, Hefei, Anhui 230026, China
| | - Yuanyuan Huang
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
- Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, CAS Center for Excellence in Molecular Cell Science & Hefei National Science Center for Physical Sciences at Microscale, Hefei, Anhui 230026, China
| | - Li Zhan
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, 230027 Anhui, China
| | - Ming Wang
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
- Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, CAS Center for Excellence in Molecular Cell Science & Hefei National Science Center for Physical Sciences at Microscale, Hefei, Anhui 230026, China
| | - Leilei Xu
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
| | - McKay Mullen
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
| | - Jianye Zang
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, 230027 Anhui, China
| | - Guowei Fang
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
| | - Zhen Dou
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
- Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, CAS Center for Excellence in Molecular Cell Science & Hefei National Science Center for Physical Sciences at Microscale, Hefei, Anhui 230026, China
| | - Xing Liu
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
- Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, CAS Center for Excellence in Molecular Cell Science & Hefei National Science Center for Physical Sciences at Microscale, Hefei, Anhui 230026, China
- Corresponding author
| | - Wei Liu
- Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Corresponding author
| | | | - Xuebiao Yao
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, University of Science & Technology of China School of Life Sciences, Hefei 230027, China
- Corresponding author
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2
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Wei J, Xia T, Chen W, Ran P, Chen M, Li X. Glucose and lipid metabolism screening models of hepatocyte spheroids after culture with injectable fiber fragments. J Tissue Eng Regen Med 2020; 14:774-788. [PMID: 32285997 DOI: 10.1002/term.3042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 03/22/2020] [Accepted: 03/24/2020] [Indexed: 12/13/2022]
Abstract
With the rise of obesity, diabetes, and other metabolic diseases, in vitro hepatic cell and tissue models play an essential role in the identification of active pharmaceutical ingredients. Up to now, three-dimensional (3D) culture models have rarely focused on hepatic glucose and lipid metabolism. In addition, primary human liver cells suffer from limited availability and interdonor difference for establishing reproducible models. Thus, in the current study, the most available human liver cancer cell line (HepG2) and primary hepatocytes from rats (rPH) were proposed to construct 3D spheroids using injectable fiber fragments with galactose grafts (gSF) as the substrate. rPH and HepG2 spheroids show strong cell-cell and cell-fiber fragment interactions to promote the cell viability, albumin, and urea syntheses. Compared with HepG2 spheroids, rPH spheroids indicate stronger glucose metabolism abilities in terms of glucose consumption, intracellular glycogen content, gluconeogenesis rate, and sensitivity to glucose modulator hormones like insulin and glucagon. On the other hand, HepG2 spheroids display strong lipid metabolism abilities in producing significantly higher levels of total cholesterol and triglyceride. Compared with those without fiber fragments, the gSF-supported 3D culture establishes effective models for in vitro glucose (rPH spheroids) and lipid metabolisms (HepG2 spheroids). The screening models are confirmed from the respective enzyme activities and gene expressions and show significantly higher sensitivity and clinically related responses to hypoglycemic and lipid-lowering drugs. Thus, the culture configuration demonstrates a predictable in vitro platform for defining glucose and lipid metabolism profiles and screening therapeutic agents for metabolism disorders like diabetes and obesity.
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Affiliation(s)
- Jiaojun Wei
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China.,School of Bioscience and Technology, Chengdu Medical College, Chengdu, China
| | - Tian Xia
- Department of Pathology, Western Theater Command Air Force Hospital, Chengdu, China
| | - Weijia Chen
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Pan Ran
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Maohua Chen
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Xiaohong Li
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China
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3
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Bruns AN, Li S, Mohannath G, Bisaro DM. Phosphorylation of Arabidopsis eIF4E and eIFiso4E by SnRK1 inhibits translation. FEBS J 2019; 286:3778-3796. [PMID: 31120171 DOI: 10.1111/febs.14935] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/28/2019] [Accepted: 05/21/2019] [Indexed: 01/01/2023]
Abstract
Regulation of protein synthesis is critical for maintaining cellular homeostasis. In mammalian systems, translational regulatory networks have been elucidated in considerable detail. In plants, however, regulation occurs through different mechanisms that remain largely elusive. In this study, we present evidence that the Arabidopsis thaliana energy sensing kinase SnRK1, a homologue of mammalian AMP-activated kinase and yeast sucrose non-fermenting 1 (SNF1), inhibits translation by phosphorylating the cap binding proteins eIF4E and eIFiso4E. We establish that eIF4E and eIFiso4E contain two deeply conserved SnRK1 consensus target sites and that both interact with SnRK1 in vivo. We then demonstrate that SnRK1 phosphorylation inhibits the ability of Arabidopsis eIF4E and eIFiso4E to complement a yeast strain lacking endogenous eIF4E, and that inhibition correlates with repression of polysome formation. Finally, we show that SnRK1 over-expression in Nicotiana benthamiana plants reduces polysome formation, and that this effect can be counteracted by transient expression of eIF4E or mutant eIF4E containing non-phosphorylatable SnRK1 target residues, but not by a phosphomimic eIF4E. Together, these studies elucidate a novel and direct pathway for translational control in plant cells. In light of previous findings that SnRK1 conditions an innate antiviral defense and is inhibited by geminivirus pathogenicity factors, we speculate that phosphorylation of cap binding proteins may be a component of the resistance mechanism.
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Affiliation(s)
- Aaron N Bruns
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA.,Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
| | - Sizhun Li
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| | - Gireesha Mohannath
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| | - David M Bisaro
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA.,Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
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4
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Chen X, Fang L, Yang T, Yang J, Bao Z, Wu D, Zhao J. The application of degree related clustering coefficient in estimating the link predictability and predicting missing links of networks. CHAOS (WOODBURY, N.Y.) 2019; 29:053135. [PMID: 31154789 DOI: 10.1063/1.5029866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
Though a lot of valuable algorithms of link prediction have been created, it is still difficult to improve the accuracy of link prediction for some networks. Such difficulties may be due to the intrinsic topological features of these networks. To reveal the correlation between the network topology and the link predictability, we generate a group of artificial networks by keeping some structural features of an initial seed network. Based on these artificial networks and some real networks, we find that five topological measures including clustering coefficient, structural consistency, random walk entropy, network diameter, and average path length significantly show their impact on the link predictability. Then, we define a topological score that combines these important topological features. Specifically, it is an integration of structural consistency with degree-related clustering coefficient defined in this work. This topological score exhibits high correlation with the link predictability. Finally, we propose an algorithm for link prediction based on this topological score. Our experiment on eight real networks verifies good performance of this algorithm in link prediction, which supports the reasonability of the new topological score. This work could be insightful for the study of the link predictability.
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Affiliation(s)
- Xing Chen
- Fundamental Department, Army Logistic University of PLA, Chongqing 401311, China
| | - Ling Fang
- Fundamental Department, Army Logistic University of PLA, Chongqing 401311, China
| | - Tinghong Yang
- Fundamental Department, Army Logistic University of PLA, Chongqing 401311, China
| | - Jian Yang
- School of Pharmacy, Second Military Medical University, Shanghai 200433, China
| | - Zerong Bao
- Department of Military Logistic, Army Logistic University of PLA, Chongqing 401311, China
| | - Duzhi Wu
- Department of Economics, Rongzhi College of Chongqing Technology and Business University, Chongqing 401320, China
| | - Jing Zhao
- Institute of Interdisciplinary Complex Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201210, China
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5
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Bays JL, Campbell HK, Heidema C, Sebbagh M, DeMali KA. Linking E-cadherin mechanotransduction to cell metabolism through force-mediated activation of AMPK. Nat Cell Biol 2017; 19:724-731. [PMID: 28553939 PMCID: PMC5494977 DOI: 10.1038/ncb3537] [Citation(s) in RCA: 144] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 04/24/2017] [Indexed: 02/08/2023]
Abstract
The response of cells to mechanical force is a major determinant of cell behaviour and is an energetically costly event. How cells derive energy to resist mechanical force is unknown. Here, we show that application of force to E-cadherin stimulates liver kinase B1 (LKB1) to activate AMP-activated protein kinase (AMPK), a master regulator of energy homeostasis. LKB1 recruits AMPK to the E-cadherin mechanotransduction complex, thereby stimulating actomyosin contractility, glucose uptake and ATP production. The increase in ATP provides energy to reinforce the adhesion complex and actin cytoskeleton so that the cell can resist physiological forces. Together, these findings reveal a paradigm for how mechanotransduction and metabolism are linked and provide a framework for understanding how diseases involving contractile and metabolic disturbances arise.
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Affiliation(s)
- Jennifer L Bays
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Hannah K Campbell
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Christy Heidema
- Interdisciplinary Graduate Program in Molecular and Cellular Biology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Michael Sebbagh
- Centre de Recherche en Cancérologie de Marseille, Aix Marseille University UM105, Institut Paoli Calmettes, UMR7258 CNRS, U1068 INSERM, Cell Polarity, Cell signalling and Cancer-Equipe labellisée Ligue Contre le Cancer, Marseille 13273, France
| | - Kris A DeMali
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.,Interdisciplinary Graduate Program in Molecular and Cellular Biology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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Furuya Y, Denda M, Sakane K, Ogusu T, Takahashi S, Magari M, Kanayama N, Morishita R, Tokumitsu H. Identification of striated muscle activator of Rho signaling (STARS) as a novel calmodulin target by a newly developed genome-wide screen. Cell Calcium 2016; 60:32-40. [PMID: 27132186 DOI: 10.1016/j.ceca.2016.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 02/07/2023]
Abstract
To search for novel target(s) of the Ca(2+)-signaling transducer, calmodulin (CaM), we performed a newly developed genome-wide CaM interaction screening of 19,676 GST-fused proteins expressed in human. We identified striated muscle activator of Rho signaling (STARS) as a novel CaM target and characterized its CaM binding ability and found that the Ca(2+)/CaM complex interacted stoichiometrically with the N-terminal region (Ala13-Gln35) of STARS in vitro as well as in living cells. Mutagenesis studies identified Ile20 and Trp33 as the essential hydrophobic residues in CaM anchoring. Furthermore, the CaM binding deficient mutant (Ile20Ala, Trp33Ala) of STARS further enhanced its stimulatory effect on SRF-dependent transcriptional activation. These results suggest a connection between Ca(2+)-signaling via excitation-contraction coupling and the regulation of STARS-mediated gene expression in muscles.
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Affiliation(s)
- Yusui Furuya
- Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Miwako Denda
- CellFree Sciences Co., Ltd., Matsuyama, 790-8577, Japan
| | - Kyohei Sakane
- Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Tomoko Ogusu
- Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Sumio Takahashi
- Department of Biology, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Masaki Magari
- Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoki Kanayama
- Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Ryo Morishita
- CellFree Sciences Co., Ltd., Matsuyama, 790-8577, Japan
| | - Hiroshi Tokumitsu
- Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
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7
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Zhao J, Miao L, Yang J, Fang H, Zhang QM, Nie M, Holme P, Zhou T. Prediction of Links and Weights in Networks by Reliable Routes. Sci Rep 2015. [PMID: 26198206 PMCID: PMC4510530 DOI: 10.1038/srep12261] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Link prediction aims to uncover missing links or predict the emergence of future relationships from the current network structure. Plenty of algorithms have been developed for link prediction in unweighted networks, but only a few have been extended to weighted networks. In this paper, we present what we call a "reliable-route method" to extend unweighted local similarity indices to weighted ones. Using these indices, we can predict both the existence of links and their weights. Experiments on various real-world networks suggest that our reliable-route weighted resource-allocation index performs noticeably better than others with respect to weight prediction. For existence prediction it is either the highest or very close to the highest. Further analysis shows a strong positive correlation between the clustering coefficient and prediction accuracy. Finally, we apply our method to the prediction of missing protein-protein interactions and their confidence scores from known PPI networks. Once again, our reliable-route method shows the highest accuracy.
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Affiliation(s)
- Jing Zhao
- Department of Mathematics, Logistical Engineering University, Chongqing, China
| | - Lili Miao
- CompleX Lab, Web Sciences Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Jian Yang
- Department of Mathematics, Logistical Engineering University, Chongqing, China
| | - Haiyang Fang
- Department of Mathematics, Logistical Engineering University, Chongqing, China
| | - Qian-Ming Zhang
- CompleX Lab, Web Sciences Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Min Nie
- CompleX Lab, Web Sciences Center, University of Electronic Science and Technology of China, Chengdu, China
| | - Petter Holme
- Department of Energy Science, Sungkyunkwan University, Suwon, Korea
| | - Tao Zhou
- 1] CompleX Lab, Web Sciences Center, University of Electronic Science and Technology of China, Chengdu, China [2] Big Data Research Center, University of Electronic Science and Technology of China, Chengdu, China
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Mohannath G, Jackel JN, Lee YH, Buchmann RC, Wang H, Patil V, Adams AK, Bisaro DM. A complex containing SNF1-related kinase (SnRK1) and adenosine kinase in Arabidopsis. PLoS One 2014; 9:e87592. [PMID: 24498147 PMCID: PMC3907550 DOI: 10.1371/journal.pone.0087592] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 12/30/2013] [Indexed: 12/22/2022] Open
Abstract
SNF1-related kinase (SnRK1) in plants belongs to a conserved family that includes sucrose non-fermenting 1 kinase (SNF1) in yeast and AMP-activated protein kinase (AMPK) in animals. These kinases play important roles in the regulation of cellular energy homeostasis and in response to stresses that deplete ATP, they inhibit energy consuming anabolic pathways and promote catabolism. Energy stress is sensed by increased AMP:ATP ratios and in plants, 5′-AMP inhibits inactivation of phosphorylated SnRK1 by phosphatase. In previous studies, we showed that geminivirus pathogenicity proteins interact with both SnRK1 and adenosine kinase (ADK), which phosphorylates adenosine to generate 5′-AMP. This suggested a relationship between SnRK1 and ADK, which we investigate in the studies described here. We demonstrate that SnRK1 and ADK physically associate in the cytoplasm, and that SnRK1 stimulates ADK in vitro by an unknown, non-enzymatic mechanism. Further, altering SnRK1 or ADK activity in transgenic plants altered the activity of the other kinase, providing evidence for in vivo linkage but also revealing that in vivo regulation of these activities is complex. This study establishes the existence of SnRK1-ADK complexes that may play important roles in energy homeostasis and cellular responses to biotic and abiotic stress.
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Affiliation(s)
- Gireesha Mohannath
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Jamie N. Jackel
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Youn Hyung Lee
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, Korea
| | - R. Cody Buchmann
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Hui Wang
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Veena Patil
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Allie K. Adams
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - David M. Bisaro
- Department of Molecular Genetics, Center for Applied Plant Sciences, and Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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Gaskin FS, Kamada K, Zuidema MY, Jones AW, Rubin LJ, Korthuis RJ. Isoform-selective 5'-AMP-activated protein kinase-dependent preconditioning mechanisms to prevent postischemic leukocyte-endothelial cell adhesive interactions. Am J Physiol Heart Circ Physiol 2011; 300:H1352-60. [PMID: 21239628 DOI: 10.1152/ajpheart.00944.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously demonstrated that preconditioning induced by ethanol consumption at low levels [ethanol preconditioning (EPC)] or with 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR-PC) 24 h before ischemia-reperfusion prevents postischemic leukocyte-endothelial cell adhesive interactions (LEI) by a mechanism that is initiated by nitric oxide formed by endothelial nitric oxide synthase. Recent work indicates that 1) ethanol increases the activity of AMP-activated protein kinase (AMPK) and 2) AMPK phosphorylates endothelial nitric oxide synthase at the same activation site seen following EPC (Ser1177). In light of these observations, we postulated that the heterotrimeric serine/threonine kinase, AMPK, may play a role in triggering the development of the anti-inflammatory phenotype induced by EPC. Ethanol was administered to C57BL/6J mice by gavage in the presence or absence of AMPK inhibition. Twenty-four hours later, the numbers of rolling and adherent leukocytes in postcapillary venules of the small intestine were recorded using an intravital microscopic approach. Following 45 min of ischemia, LEI were recorded after 30 and 60 min of reperfusion or at equivalent time points in control animals. Ischemia-reperfusion induced a marked increase in LEI relative to sham-operated control mice. The increase in LEI was prevented by EPC, an effect that was lost with AMPK inhibition during the period of ethanol exposure. Studies conducted in AMPK α(1)- and α(2)-knockout mice suggest that the anti-inflammatory effects of AICAR are not dependent on which isoform of the catalytic α-subunit is present because a deficiency of either isoform results in a loss of protection. In sharp contrast, EPC appears to be triggered by an AMPK α(2)-isoform-dependent mechanism.
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Affiliation(s)
- F Spencer Gaskin
- Departments of Medical Pharmacology and Physiology, University of Missouri, Columbia, 65212, USA
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10
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Zhu XJ, Dai JQ, Tan X, Zhao Y, Yang WJ. Activation of an AMP-activated protein kinase is involved in post-diapause development of Artemia franciscana encysted embryos. BMC DEVELOPMENTAL BIOLOGY 2009; 9:21. [PMID: 19284883 PMCID: PMC2667496 DOI: 10.1186/1471-213x-9-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 03/16/2009] [Indexed: 11/30/2022]
Abstract
Background Cysts of Artemia can remain in a dormant state for long periods with a very low metabolic rate, and only resume their development with the approach of favorable conditions. The post-diapause development is a very complicated process involving a variety of metabolic and biochemical events. However, the intrinsic mechanisms that regulate this process are unclear. Results Herein we report the specific activation of an AMP-activated protein kinase (AMPK) in the post-diapause developmental process of Artemia. Using a phospho-AMPKα antibody, AMPK was shown to be phosphorylated in the post-diapause developmental process. Results of kinase assay analysis showed that this phosphorylation is essential for AMPK activation. Using whole-mount immunohistochemistry, phosphorylated AMPK was shown to be predominantly located in the ectoderm of the early developed embryos in a ring shape; however, the location and shape of the activation region changed as development proceeded. Additionally, Western blotting analysis on different portions of the cyst extracts showed that phosphorylated AMPKα localized to the nuclei and this location was not affected by intracellular pH. Confocal microscopy analysis of immunofluorescent stained cyst nuclei further showed that AMPKα localized to the nuclei when activated. Moreover, cellular AMP, ADP, and ATP levels in developing cysts were determined by HPLC, and the results showed that the activation of Artemia AMPK may not be associated with cellular AMP:ATP ratios, suggesting other pathways for regulation of Artemia AMPK activity. Conclusion Together, we report evidence demonstrating the activation of AMPK in Artemia developing cysts and present an argument for its role in the development-related gene expression and energy control in certain cells during post-diapause development of Artemia.
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Affiliation(s)
- Xiao-Jing Zhu
- Institute of Cell Biology and Genetics, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang 310058, PR China.
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11
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Kuga W, Tsuchihara K, Ogura T, Kanehara S, Saito M, Suzuki A, Esumi H. Nuclear localization of SNARK; its impact on gene expression. Biochem Biophys Res Commun 2008; 377:1062-6. [PMID: 18992219 DOI: 10.1016/j.bbrc.2008.10.143] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 10/17/2008] [Indexed: 12/21/2022]
Abstract
SNARK, a member of the AMPK-related kinases, has been involved in the cellular stress responses but its precise mechanisms remain unclear. Subcellular localization of SNARK protein was identified. Unlike cytoplasmic localizing AMPKalpha, SNARK was predominantly localized in the nucleus. SNARK was constitutively distributed in the nucleus even when SNARK was activated by metabolic stimuli such as AICAR and glucose-deprivation. Conserved nuclear localization signal (NLS) was identified at the N-terminal portion ((68)KKAR(71)). Deletion and point mutation of this part resulted in the cytoplasmic translocation of mutant proteins. Furthermore, GFP fused with the SNARK fragment containing (68)KKAR(71) translocated to the nucleus. A microarray analysis revealed that the nuclear localizing SNARK altered transcriptome profiles and a considerable part of these alterations were canceled by the mutation of NLS, suggesting the ability of SNARK to modulate gene expression dependent on its nuclear localization.
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Affiliation(s)
- Wataru Kuga
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
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12
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Zhou F, Ren JL, Dong J. Advances of candidate binding protein to envelope protein of hepatitis B virus. Shijie Huaren Xiaohua Zazhi 2008; 16:1788-1792. [DOI: 10.11569/wcjd.v16.i16.1788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
There are at least 4 initial coding positions in S gene of hepatitis B virus (HBV), encoding pre-pre-S, pre-S1, pre-S2 as well as major protein. There are no definite evidences to prove that envelope protein will interact with human cellular protein. This review focused on research approaches to the existing protein - protein interaction and summarized proteins of liver cells that may interact with current HBV envelope protein. However, most of currently available results need further verification.
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Suzuki A, Okamoto S, Lee S, Saito K, Shiuchi T, Minokoshi Y. Leptin stimulates fatty acid oxidation and peroxisome proliferator-activated receptor alpha gene expression in mouse C2C12 myoblasts by changing the subcellular localization of the alpha2 form of AMP-activated protein kinase. Mol Cell Biol 2007; 27:4317-27. [PMID: 17420279 PMCID: PMC1900064 DOI: 10.1128/mcb.02222-06] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leptin stimulates fatty acid oxidation in skeletal muscle through the activation of AMP-activated protein kinase (AMPK) and the induction of gene expression, such as that for peroxisome proliferator-activated receptor alpha (PPARalpha). We now show that leptin stimulates fatty acid oxidation and PPARalpha gene expression in the C2C12 muscle cell line through the activation of AMPK containing the alpha2 subunit (alpha2AMPK) and through changes in the subcellular localization of this enzyme. Activated alpha2AMPK containing the beta1 subunit was shown to be retained in the cytoplasm, where it phosphorylated acetyl coenzyme A carboxylase and thereby stimulated fatty acid oxidation. In contrast, alpha2AMPK containing the beta2 subunit transiently increased fatty acid oxidation but underwent rapid translocation to the nucleus, where it induced PPARalpha gene transcription. A nuclear localization signal and Thr(172) phosphorylation of alpha2 were found to be essential for nuclear translocation of alpha2AMPK, whereas the myristoylation of beta1 anchors alpha2AMPK in the cytoplasm. The prevention of alpha2AMPK activation and the change in its subcellular localization inhibited the metabolic effects of leptin. Our data thus suggest that the activation of and changes in the subcellular localization of alpha2AMPK are required for leptin-induced stimulation of fatty acid oxidation and PPARalpha gene expression in muscle cells.
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Affiliation(s)
- Atsushi Suzuki
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, Japan
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Suter M, Riek U, Tuerk R, Schlattner U, Wallimann T, Neumann D. Dissecting the role of 5'-AMP for allosteric stimulation, activation, and deactivation of AMP-activated protein kinase. J Biol Chem 2006; 281:32207-16. [PMID: 16943194 DOI: 10.1074/jbc.m606357200] [Citation(s) in RCA: 351] [Impact Index Per Article: 19.5] [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) is a heterotrimeric protein kinase that is crucial for cellular energy homeostasis of eukaryotic cells and organisms. Here we report on the activation of AMPK alpha1beta1gamma1 and alpha2beta2gamma1 by their upstream kinases (Ca(2+)/calmodulin-dependent protein kinase kinase-beta and LKB1-MO25alpha-STRADalpha), the deactivation by protein phosphatase 2Calpha, and on the extent of stimulation of AMPK by its allosteric activator AMP, using purified recombinant enzyme preparations. An accurate high pressure liquid chromatography-based method for AMPK activity measurements was established, which allowed for direct quantitation of the unphosphorylated and phosphorylated artificial peptide substrate, as well as the adenine nucleotides. Our results show a 1000-fold activation of AMPK by the combined effects of upstream kinase and saturating concentrations of AMP. The two AMPK isoforms exhibit similar specific activities (6 mumol/min/mg) and do not differ significantly by their responsiveness to AMP. Due to the inherent instability of ATP and ADP, it proved impossible to assay AMPK activity in the absolute absence of AMP. However, the half-maximal stimulatory effect of AMP is reached below 2 microm. AMP does not appear to augment phosphorylation by upstream kinases in the purified in vitro system, but deactivation by dephosphorylation of AMPK alpha-subunits at Thr-172 by protein phosphatase 2Calpha is attenuated by AMP. Furthermore, it is shown that neither purified NAD(+) nor NADH alters the activity of AMPK in a concentration range of 0-300 microm, respectively. Finally, evidence is provided that ZMP, a compound formed in 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside-treated cells to activate AMPK in vivo, allosterically activates purified AMPK in vitro, but compared with AMP, maximal activity is not reached. These data shed new light on physiologically important aspects of AMPK regulation.
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Affiliation(s)
- Marianne Suter
- Institute of Cell Biology, Schafmattstrasse 18, ETH Zurich, 8093 Zurich, Switzerland
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