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Liu Y, Dantas E, Ferrer M, Liu Y, Comjean A, Davidson EE, Hu Y, Goncalves MD, Janowitz T, Perrimon N. Tumor Cytokine-Induced Hepatic Gluconeogenesis Contributes to Cancer Cachexia: Insights from Full Body Single Nuclei Sequencing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.15.540823. [PMID: 37292804 PMCID: PMC10245574 DOI: 10.1101/2023.05.15.540823] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A primary cause of death in cancer patients is cachexia, a wasting syndrome attributed to tumor-induced metabolic dysregulation. Despite the major impact of cachexia on the treatment, quality of life, and survival of cancer patients, relatively little is known about the underlying pathogenic mechanisms. Hyperglycemia detected in glucose tolerance test is one of the earliest metabolic abnormalities observed in cancer patients; however, the pathogenesis by which tumors influence blood sugar levels remains poorly understood. Here, utilizing a Drosophila model, we demonstrate that the tumor secreted interleukin-like cytokine Upd3 induces fat body expression of Pepck1 and Pdk, two key regulatory enzymes of gluconeogenesis, contributing to hyperglycemia. Our data further indicate a conserved regulation of these genes by IL-6/JAK-STAT signaling in mouse models. Importantly, in both fly and mouse cancer cachexia models, elevated gluconeogenesis gene levels are associated with poor prognosis. Altogether, our study uncovers a conserved role of Upd3/IL-6/JAK-STAT signaling in inducing tumor-associated hyperglycemia, which provides insights into the pathogenesis of IL-6 signaling in cancer cachexia.
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Affiliation(s)
- Ying Liu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Ezequiel Dantas
- Division of Endocrinology, Department of Medicine, Weill Cornell Medicine, New York, NY 10065, USA
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10065, USA
| | - Miriam Ferrer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY 11724 USA
| | - Yifang Liu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Aram Comjean
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Emma E. Davidson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY 11724 USA
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Marcus D. Goncalves
- Division of Endocrinology, Department of Medicine, Weill Cornell Medicine, New York, NY 10065, USA
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10065, USA
| | - Tobias Janowitz
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY 11724 USA
- Northwell Health Cancer Institute, Northwell Health, New Hyde Park, New York, NY 11042 USA
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Boston, MA, USA
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2
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BCKDK Promotes Ovarian Cancer Proliferation and Migration by Activating the MEK/ERK Signaling Pathway. JOURNAL OF ONCOLOGY 2022; 2022:3691635. [PMID: 35498541 PMCID: PMC9054484 DOI: 10.1155/2022/3691635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 03/23/2022] [Accepted: 03/28/2022] [Indexed: 11/21/2022]
Abstract
Background Ovarian cancer (OC) is the most fatal gynecologic cancer. The branched-chain α-keto acid dehydrogenase kinase (BCKDK) plays an important role in many serious human diseases, including cancers. Its function in promoting cell proliferation and migration has been reported in various cancers. However, the biological role of BCKDK and its molecular mechanisms underlying OC initiation and progression are unclear. Methods First, the expression level of BCKDK in OC cell lines or tissues was determined using tissue microarray- (TMA-) based immunohistochemistry or western blotting. Then, growth curve analysis, anchorage-independent cell transformation assays, wound healing assays, cell migration assays, and tumor xenografts were used to test whether BCKDK could promote cell transformation or metastasis. Finally, the signaling pathways involved in this process were investigated by western blotting or immunoprecipitation. Results We found that the expression of BCKDK was upregulated in OC tissues and the high expression of BCKDK was correlated with an advanced pathological grade in patients. The ectopic overexpression of BCKDK promoted the proliferation and migration of OC cells, and the knockdown of BCKDK with shRNAs inhibited the proliferation and migration of OC ex vivo and in vivo. Moreover, BCKDK promoted OC proliferation and migration by activating MEK. Conclusions Our results demonstrate that BCKDK promotes OC proliferation and migration by activating the MEK/ERK signaling pathway. Targeting the BCKDK-MEK axis may provide a new therapeutic strategy for treating patients with OC.
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Abbaszade Z, Bagca BG, Avci CB. Molecular biological investigation of temozolomide and KC7F2 combination in U87MG glioma cell line. Gene 2021; 776:145445. [PMID: 33484758 DOI: 10.1016/j.gene.2021.145445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 12/25/2020] [Accepted: 01/13/2021] [Indexed: 11/25/2022]
Abstract
Glioblastom Multiforme (GBM) is the most invasive and malignant member of the IV grade of the subclass Astrocytoma according to the last assessment of the 2016 WHO report. Due to the resistance to treatment and weak response, as well as the topographical structure of the blood brain barrier, the treatment is also difficult due to the severe clinical manifestation, and new treatment methods and new therapeutic agents are needed. Temozolomide (TMZ) is widely used in the treatment of glioblastoma and is considered as the primary treatment modality. TMZ, a member of the class of cognitive agents, is currently considered the most effective drug because it can easily pass through the blood brain barrier. Glucose metabolism is a complex energy producing machine that, a glucose molecule produces 38 molecules of ATP after full glycolytic catabolism. According to Otto Warburg's numerous studies cancer cells perform the first glycolytic step without entering the mitochondrial step. These cells produce lactic acid and make the micro-media more acidic even in aerobic conditions. This phenomenon is attributed to the Warburg hypothesis and either as aerobic glycolysis. Although glycolysis enzymes are the primary actors of this phenotypic expression, some genetic and epigenetic factors are no exception. We experimentally used KC7F2 active ingredient to target cancer metabolism. In our study, we evaluated cancer metabolism in combination with the effect of TMZ chemotherapeutic agent, examining the effect of two different agents separately and in combination to observe the effects of cancer cell proliferation, survival, apoptosis and expression of metabolism genes on expression. We observed that the combined effect of reduced the effective dose of the TMZ alkylating agent and that the effect was increased and the effect of the combined teraphy is assessed from a metabolic point of view and that it suppresses aerobic glycolysis.
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Affiliation(s)
- Zaka Abbaszade
- Kazımdirik, Ege Ünv. Hst. No:9, 35100 Bornova/Izmir, Turkey.
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Chatterjee N, Pazarentzos E, Mayekar MK, Gui P, Allegakoen DV, Hrustanovic G, Olivas V, Lin L, Verschueren E, Johnson JR, Hofree M, Yan JJ, Newton BW, Dollen JV, Earnshaw CH, Flanagan J, Chan E, Asthana S, Ideker T, Wu W, Suzuki J, Barad BA, Kirichok Y, Fraser JS, Weiss WA, Krogan NJ, Tulpule A, Sabnis AJ, Bivona TG. Synthetic Essentiality of Metabolic Regulator PDHK1 in PTEN-Deficient Cells and Cancers. Cell Rep 2019; 28:2317-2330.e8. [PMID: 31461649 PMCID: PMC6728083 DOI: 10.1016/j.celrep.2019.07.063] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 06/19/2019] [Accepted: 07/18/2019] [Indexed: 12/17/2022] Open
Abstract
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor and bi-functional lipid and protein phosphatase. We report that the metabolic regulator pyruvate dehydrogenase kinase1 (PDHK1) is a synthetic-essential gene in PTEN-deficient cancer and normal cells. The PTEN protein phosphatase dephosphorylates nuclear factor κB (NF-κB)-activating protein (NKAP) and limits NFκB activation to suppress expression of PDHK1, a NF-κB target gene. Loss of the PTEN protein phosphatase upregulates PDHK1 to induce aerobic glycolysis and PDHK1 cellular dependence. PTEN-deficient human tumors harbor increased PDHK1, a biomarker of decreased patient survival. This study uncovers a PTEN-regulated signaling pathway and reveals PDHK1 as a potential target in PTEN-deficient cancers.
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Affiliation(s)
- Nilanjana Chatterjee
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Evangelos Pazarentzos
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Manasi K Mayekar
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Philippe Gui
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David V Allegakoen
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Gorjan Hrustanovic
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Victor Olivas
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Luping Lin
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Erik Verschueren
- J. David Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94158, USA
| | - Jeffrey R Johnson
- J. David Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94158, USA
| | - Matan Hofree
- Department of Bioengineering, University of California, San Diego, San Diego, CA 92093, USA
| | - Jenny J Yan
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Billy W Newton
- J. David Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94158, USA
| | - John V Dollen
- J. David Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94158, USA
| | - Charles H Earnshaw
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jennifer Flanagan
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Elton Chan
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Saurabh Asthana
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Trey Ideker
- Department of Bioengineering, University of California, San Diego, San Diego, CA 92093, USA
| | - Wei Wu
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Junji Suzuki
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Benjamin A Barad
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuriy Kirichok
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - James S Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - William A Weiss
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Nevan J Krogan
- J. David Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94158, USA
| | - Asmin Tulpule
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Amit J Sabnis
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Trever G Bivona
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94158, USA.
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5
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Zhang M, Cong Q, Zhang X, Zhang M, Lu Y, Xu C. Pyruvate dehydrogenase kinase 1 contributes to cisplatin resistance of ovarian cancer through EGFR activation. J Cell Physiol 2018; 234:6361-6370. [PMID: 30229902 DOI: 10.1002/jcp.27369] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 08/17/2018] [Indexed: 12/27/2022]
Affiliation(s)
- Meng Zhang
- Department of Gynecology, Obstetrics and Gynecology Hospital, Fudan University Shanghai China
- Department of Obstetrics and Gynecology of Shanghai Medical School Fudan University Shanghai China
| | - Qing Cong
- Department of Gynecology, Obstetrics and Gynecology Hospital, Fudan University Shanghai China
- Department of Obstetrics and Gynecology of Shanghai Medical School Fudan University Shanghai China
| | - Xiao‐Yan Zhang
- Department of Gynecology, Obstetrics and Gynecology Hospital, Fudan University Shanghai China
- Department of Obstetrics and Gynecology of Shanghai Medical School Fudan University Shanghai China
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases Shanghai China
| | - Ming‐Xing Zhang
- Department of Gynecology, Obstetrics and Gynecology Hospital, Fudan University Shanghai China
- Department of Obstetrics and Gynecology of Shanghai Medical School Fudan University Shanghai China
| | - Ying‐Ying Lu
- Department of Gynecology, Obstetrics and Gynecology Hospital, Fudan University Shanghai China
- Department of Obstetrics and Gynecology of Shanghai Medical School Fudan University Shanghai China
| | - Cong‐Jian Xu
- Department of Gynecology, Obstetrics and Gynecology Hospital, Fudan University Shanghai China
- Department of Obstetrics and Gynecology of Shanghai Medical School Fudan University Shanghai China
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases Shanghai China
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6
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Liu Y, Xie Z, Zhao D, Zhu J, Mao F, Tang S, Xu H, Luo C, Geng M, Huang M, Li J. Development of the First Generation of Disulfide-Based Subtype-Selective and Potent Covalent Pyruvate Dehydrogenase Kinase 1 (PDK1) Inhibitors. J Med Chem 2017; 60:2227-2244. [PMID: 28230989 DOI: 10.1021/acs.jmedchem.6b01245] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pyruvate dehydrogenase kinases (PDKs) are overexpressed in most cancer cells and are responsible for aberrant glucose metabolism. We previously described bis(4-morpholinyl thiocarbonyl)-disulfide (JX06, 16) as the first covalent inhibitor of PDK1. Here, on the basis of the scaffold of 16, we identify two novel types of disulfide-based PDK1 inhibitors. The most potent analogue, 3a, effectively inhibits PDK1 both at the molecular (kinact/Ki = 4.17 × 103 M-1 s-1) and the cellular level (down to 0.1 μM). In contrast to 16, 3a is a potent and subtype-selective inhibitor of PDK1 with >40-fold selectivity for PDK2-4. 3a also significantly alters glucose metabolic pathways in A549 cells by decreasing ECAR and increasing ROS. Moreover, in the xenograft models, 3a shows significant antitumor activity with no negative effect to the mice weight. Collectively, these data demonstrate that 3a may be an excellent lead compound for the treatment of cancer as a first-generation subtype-selective and covalent PDK1 inhibitor.
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Affiliation(s)
- Yifu Liu
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology , Shanghai 200237, China
| | - Zuoquan Xie
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Dan Zhao
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Jin Zhu
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology , Shanghai 200237, China
| | - Fei Mao
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology , Shanghai 200237, China
| | - Shuai Tang
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Hui Xu
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Cheng Luo
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Meiyu Geng
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Min Huang
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Jian Li
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology , Shanghai 200237, China
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7
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Dadson K, Hauck L, Hao Z, Grothe D, Rao V, Mak TW, Billia F. The E3 ligase Mule protects the heart against oxidative stress and mitochondrial dysfunction through Myc-dependent inactivation of Pgc-1α and Pink1. Sci Rep 2017; 7:41490. [PMID: 28148912 PMCID: PMC5288653 DOI: 10.1038/srep41490] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/21/2016] [Indexed: 01/03/2023] Open
Abstract
Cardiac homeostasis requires proper control of protein turnover. Protein degradation is principally controlled by the Ubiquitin-Proteasome System. Mule is an E3 ubiquitin ligase that regulates cellular growth, DNA repair and apoptosis to maintain normal tissue architecture. However, Mule’s function in the heart has yet to be described. In a screen, we found reduced Mule expression in left ventricular samples from end-stage heart failure patients. Consequently, we generated conditional cardiac-specific Mule knockout (Mule fl/fl(y);mcm) mice. Mule ablation in adult Mule fl/fl(y);mcm mice prevented myocardial c-Myc polyubiquitination, leading to c-Myc accumulation and subsequent reduced expression of Pgc-1α, Pink1, and mitochondrial complex proteins. Furthermore, these mice developed spontaneous cardiac hypertrophy, left ventricular dysfunction, and early mortality. Co-deletion of Mule and c-Myc rescued this phenotype. Our data supports an indispensable role for Mule in cardiac homeostasis through the regulation of mitochondrial function via maintenance of Pgc-1α and Pink1 expression and persistent negative regulation of c-Myc.
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Affiliation(s)
- Keith Dadson
- Toronto General Research Institute, Toronto, 100 College St., M5G 1L7, Ontario Canada
| | - Ludger Hauck
- Toronto General Research Institute, Toronto, 100 College St., M5G 1L7, Ontario Canada
| | - Zhenyue Hao
- Campbell Family Cancer Research Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Daniela Grothe
- Toronto General Research Institute, Toronto, 100 College St., M5G 1L7, Ontario Canada
| | - Vivek Rao
- Division of Cardiovascular Surgery, UHN, Toronto, ON, M5G 2C4, Canada
| | - Tak W Mak
- Campbell Family Cancer Research Institute, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Filio Billia
- Toronto General Research Institute, Toronto, 100 College St., M5G 1L7, Ontario Canada.,Division of Cardiology, University Health Network (UHN), Toronto, Ontario, Canada.,Heart and Stroke Richard Lewar Centre of Excellence, University of Toronto, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, 1 King's College Circle, Toronto, M5G 1A8, Ontario Canada
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8
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Abstract
The family of 2-oxoacid dehydrogenase complexes (2-OADC), typified by the pyruvate dehydrogenase multi-enzyme complex (PDC) as its most prominent member, are massive molecular machines (Mr, 4-10 million) controlling key steps in glucose homeostasis (PDC), citric acid cycle flux (OGDC, 2-oxoglutarate dehydrogenase) and the metabolism of the branched-chain amino acids, leucine, isoleucine and valine (BCOADC, branched-chain 2-OADC). These highly organised mitochondrial arrays, composed of multiple copies of three separate enzymes, have been widely studied as paradigms for the analysis of enzyme cooperativity, substrate channelling, protein-protein interactions and the regulation of activity by phosphorylation . This chapter will highlight recent advances in our understanding of the structure-function relationships, the overall organisation and the transport and assembly of PDC in particular, focussing on both native and recombinant forms of the complex and their individual components or constituent domains. Biophysical approaches, including X-ray crystallography (MX), nuclear magnetic resonance spectroscopy (NMR), cryo-EM imaging, analytical ultracentrifugation (AUC) and small angle X-ray and neutron scattering (SAXS and SANS), have all contributed significant new information on PDC subunit organisation, stoichiometry, regulatory mechanisms and mode of assembly. Moreover, the recognition of specific genetic defects linked to PDC deficiency, in combination with the ability to analyse recombinant PDCs housing both novel naturally-occurring and engineered mutations, have all stimulated renewed interest in these classical metabolic assemblies. In addition, the role played by PDC, and its constituent proteins, in certain disease states will be briefly reviewed, focussing on the development of new and exciting areas of medical and immunological research.
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Affiliation(s)
- Olwyn Byron
- School of Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - John Gordon Lindsay
- Institute of Molecular, Cell and Systems Biology, Davidson Building, College of Medicine, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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9
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Li X, Wang L, Li Y, Fu J, Zhen L, Yang Q, Li S, Zhang Y. Tyrosine phosphorylation of dihydrolipoamide dehydrogenase as a potential cadmium target and its inhibitory role in regulating mouse sperm motility. Toxicology 2016; 357-358:52-64. [PMID: 27289041 DOI: 10.1016/j.tox.2016.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/06/2016] [Accepted: 06/06/2016] [Indexed: 01/19/2023]
Abstract
Cadmium (Cd) is reported to reduce sperm motility and functions. However, the molecular mechanisms of Cd-induced toxicity remain largely unknown, presenting a major knowledge gap in research on reproductive toxicology. In the present study, we identified a candidate protein, dihydrolipoamide dehydrogenase (DLD), which is a post-pyruvate metabolic enzyme, exhibiting tyrosine phosphorylation in mouse sperm exposed to Cd both in vivo and in vitro. Immunoprecipitation assay demonstrated DLD was phosphorylated in tyrosine residues without altered expression after Cd treatment, which further confirmed our identified result. However, the tyrosine phosphorylation of DLD did not participate in mouse sperm capacitation and Bovine Serum Albumin (BSA) effectively prevented the tyrosine phosphorylation of DLD. Moreover, Cd-induced tyrosine phosphorylation of DLD lowered its dehydrogenase activity and meanwhile, Nicotinamide Adenine Dinucleotide Hydrogen (NADH) content, Adenosine Triphosphate (ATP) production and sperm motility were all inhibited by Cd. Interestingly, when the tyrosine phosphorylation of DLD was blocked by BSA, the decrease of DLD activity, NADH and ATP content as well as sperm motility was also suppressed simultaneously. These results suggested that Cd-induced tyrosine phosphorylation of DLD inhibited its activity and thus suppressed the tricarboxylic acid (TCA) cycle, which resulted in the reduction of NADH and hence the ATP production generated through oxidative phosphorylation (OPHOXS). Taken together, our results revealed that Cd induced DLD tyrosine phosphorylation, in response to regulate TCA metabolic pathway, which reduced ATP levels and these negative effects led to decreased sperm motility. This study provided new understanding of the mechanisms contributing to the harmful effects of Cd on the motility and function of spermatozoa.
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Affiliation(s)
- Xinhong Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China.
| | - Lirui Wang
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
| | - Yuhua Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
| | - Jieli Fu
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
| | - Linqing Zhen
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
| | - Qiangzhen Yang
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
| | - Sisi Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
| | - Yukun Zhang
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China
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10
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Abiri M, Karamzadeh R, Karimipoor M, Ghadami S, Alaei MR, Bagheri SD, Bagherian H, Setoodeh A, Noori-Daloii MR, Sirous Zeinali. Identification of six novel mutations in Iranian patients with maple syrup urine disease and their in silico analysis. Mutat Res 2016; 786:34-40. [PMID: 26901124 DOI: 10.1016/j.mrfmmm.2016.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Revised: 01/12/2016] [Accepted: 01/22/2016] [Indexed: 01/09/2023]
Abstract
Maple syrup urine disease (MSUD) is a rare inborn error of branched-chain amino acid metabolism. The disease prevalence is higher in populations with elevated rate of consanguineous marriages such as Iran. Different types of disease causing mutations have been previously reported in BCKDHA, BCKDHB, DBT and DLD genes known to be responsible for MSUD phenotype. In this study, two sets of multiplex polymorphic STR (Short Tandem Repeat) markers linked to the above genes were used to aid in homozygosity mapping in order to find probable pathogenic change(s) in the studied families. The families who showed homozygote haplotype for the BCKDHA gene were subsequently sequenced. Our findings showed that exons 2, 4 and 6 contain most of the mutations which are novel. The changes include two single nucleotide deletion (i.e. c. 143delT and c.702delT), one gross deletion covering the whole exon four c.(375+1_376-1)_(8849+1_885-1), two splice site changes (c.1167+1G>T, c. 288+1G>A), and one point mutation (c.731G>A). Computational approaches were used to analyze these two novel mutations in terms of their impact on protein structure. Computational structural modeling indicated that these mutations might affect structural stability and multimeric assembly of branched-chain α-keto acid dehydrogenase complex (BCKDC).
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Affiliation(s)
- Maryam Abiri
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Razieh Karamzadeh
- Department of Molecular Systems Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran; Department of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Morteza Karimipoor
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Shirin Ghadami
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad Reza Alaei
- Pediatric Endocrinology and Metabolism, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Samira Dabagh Bagheri
- Dr. Zeinali's Medical Genetics Laboratory, Kawsar Human Genetics Research Center, Tehran, Iran
| | - Hamideh Bagherian
- Dr. Zeinali's Medical Genetics Laboratory, Kawsar Human Genetics Research Center, Tehran, Iran
| | - Aria Setoodeh
- Department of Pediatrics, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Sirous Zeinali
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran; Dr. Zeinali's Medical Genetics Laboratory, Kawsar Human Genetics Research Center, Tehran, Iran.
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11
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Bhandary S, Aguan K. Pyruvate dehydrogenase complex deficiency and its relationship with epilepsy frequency--An overview. Epilepsy Res 2015; 116:40-52. [PMID: 26354166 DOI: 10.1016/j.eplepsyres.2015.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/29/2015] [Accepted: 07/05/2015] [Indexed: 12/18/2022]
Abstract
The pyruvate dehydrogenase complex (PDHc) is a member of a family of multienzyme complexes that provides the link between glycolysis and the tricarboxylic acid (TCA) cycle by catalyzing the physiologically irreversible decarboxylation of various 2-oxoacid substrates to their corresponding acyl-CoA derivatives, NADH and CO2. PDHc deficiency is a metabolic disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration that vary with age and gender. In this review, we aim to discuss the relationship between occurrence of epilepsy and PDHc deficiency associated with the pyruvate dehydrogenase complex (E1α subunit (PDHA1) and E1β subunit (PDHB)) and PDH phosphatase (PDP) deficiency. PDHc plays a crucial role in the aerobic carbohydrate metabolism and regulates the use of carbohydrate as the source of oxidative energy. In severe PDHc deficiency, the energy deficit impairs brain development in utero resulting in physiological and structural changes in the brain that contributes to the subsequent onset of epileptogenesis. Epileptogenesis in PDHc deficiency is linked to energy failure and abnormal neurotransmitter metabolism that progressively alters neuronal excitability. This metabolic blockage might be restricted via inclusion of ketogenic diet that is broken up by β-oxidation and directly converting it to acetyl-CoA, and thereby improving the patient's health condition. Genetic counseling is essential as PDHA1 deficiency is X-linked. The demonstration of the X-chromosome localization of PDHA1 resolved a number of questions concerning the variable phenotype displayed by patients with E1 deficiency. Most patients show a broad range of neurological abnormalities, with the severity showing some dependence on the nature of the mutation in the Elα gene, while PDHB and PDH phosphatase (PDP) deficiencies are of autosomal recessive inheritance. However, in females, the disorder is further complicated by the pattern of X-chromosome inactivation, i.e., unfavorable lyonization. Furthermore research should focus on epileptogenic animal models; this might pave a new way toward identification of the pathophysiology of this challenging disorder.
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Affiliation(s)
- Suman Bhandary
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong 793 022, India; Division of Molecular Medicine, Bose Institute, Kolkata 700 054, India
| | - Kripamoy Aguan
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong 793 022, India.
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12
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Geschwind DH, State MW. Gene hunting in autism spectrum disorder: on the path to precision medicine. Lancet Neurol 2015; 14:1109-20. [PMID: 25891009 DOI: 10.1016/s1474-4422(15)00044-7] [Citation(s) in RCA: 296] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/21/2015] [Accepted: 04/08/2015] [Indexed: 12/13/2022]
Abstract
Autism spectrum disorder is typical of the majority of neuropsychiatric syndromes in that it is defined by signs and symptoms, rather than by aetiology. Not surprisingly, the causes of this complex human condition are manifold and include a substantial genetic component. Recent developments in gene-hunting technologies and methods, and the resulting plethora of genetic findings, promise to open new avenues to understanding of disease pathophysiology and to contribute to improved clinical management. Despite remarkable genetic heterogeneity, evidence is emerging for converging pathophysiology in autism spectrum disorder, but how this notion of convergent pathways will translate into therapeutics remains to be established. Leveraging genetic findings through advances in model systems and integrative genomic approaches could lead to the development of new classes of therapies and a personalised approach to treatment.
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Affiliation(s)
- Daniel H Geschwind
- Neurogenetics Program, Department of Neurology, and Center for Autism Research and Treatment, Semel Institute, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
| | - Matthew W State
- Department of Psychiatry, Langley Porter Psychiatric Institute, University of California, San Francisco, CA, USA
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13
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Moon SS, Lee JE, Lee YS, Kim SW, Jeoung NH, Lee IK, Kim JG. Association of pyruvate dehydrogenase kinase 4 gene polymorphisms with type 2 diabetes and metabolic syndrome. Diabetes Res Clin Pract 2012; 95:230-6. [PMID: 22019269 DOI: 10.1016/j.diabres.2011.09.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 09/20/2011] [Accepted: 09/29/2011] [Indexed: 01/16/2023]
Abstract
AIMS Pyruvate dehydrogenase kinase 4 (PDK4) plays a crucial role in glucose utilization and lipid metabolism by regulating the pyruvate dehydrogenase complex (PDC) and is an emerging therapeutic target for type 2 diabetes. To date, no study has specifically examined the relationship between PDK4 gene polymorphisms and type 2 diabetes or metabolic syndrome. METHODS The association of common single nucleotide polymorphisms (SNPs) was examined in PDK4 [-208A/G (rs10085637), IVS3+192C/T (rs3779478), IVS6+31A/G (rs2301630), IVS7+514A/G (rs12668651), IVS10+75C/T (rs10247649)] with type 2 diabetes and metabolic syndrome in 651 Korean subjects with type 2 diabetes and 350 nondiabetic Korean subjects. The association of these SNPs with clinical parameters related to metabolic syndromes including obesity, hyperglycemia, hypertension, and dyslipidemia was also examined. RESULTS No significant association was found between the studied SNPs and type 2 diabetes, metabolic syndrome, or clinical parameters. The PDK4 gene haplotype ACAGC showed a modest association with type 2 diabetes. However, the significance of this association was lost after considering for multiple comparisons. CONCLUSIONS PDK4 polymorphisms may not be associated with type 2 diabetes or metabolic syndrome. Further studies utilizing a larger study population are required to confirm these results.
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Affiliation(s)
- Seong-Su Moon
- Department of Internal medicine, Dongguk University School of Medicine, Gyeongju, South Korea.
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14
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Kato M, Wynn RM, Chuang JL, Tso SC, Machius M, Li J, Chuang DT. Structural basis for inactivation of the human pyruvate dehydrogenase complex by phosphorylation: role of disordered phosphorylation loops. Structure 2009; 16:1849-59. [PMID: 19081061 DOI: 10.1016/j.str.2008.10.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 10/26/2008] [Accepted: 10/27/2008] [Indexed: 11/15/2022]
Abstract
We report the crystal structures of the phosporylated pyruvate dehydrogenase (E1p) component of the human pyruvate dehydrogenase complex (PDC). The complete phosphorylation at Ser264-alpha (site 1) of a variant E1p protein was achieved using robust pyruvate dehydrogenase kinase 4 free of the PDC core. We show that unlike its unmodified counterpart, the presence of a phosphoryl group at Ser264-alpha prevents the cofactor thiamine diphosphate-induced ordering of the two loops carrying the three phosphorylation sites. The disordering of these phosphorylation loops is caused by a previously unrecognized steric clash between the phosphoryl group at site 1 and a nearby Ser266-alpha, which nullifies a hydrogen-bonding network essential for maintaining the loop conformations. The disordered phosphorylation loops impede the binding of lipoyl domains of the PDC core to E1p, negating the reductive acetylation step. This results in the disruption of the substrate channeling in the PDC, leading to the inactivation of this catalytic machine.
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Affiliation(s)
- Masato Kato
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9038, USA
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15
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Lan J, Lei MG, Zhang YB, Wang JH, Feng XT, Xu DQ, Gui JF, Xiong YZ. Characterization of the porcine differentially expressed PDK4 gene and association with meat quality. Mol Biol Rep 2008; 36:2003-10. [PMID: 19051057 DOI: 10.1007/s11033-008-9411-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 10/27/2008] [Indexed: 01/01/2023]
Abstract
To investigate the differential expression of genes in the skeletal muscle between Yorkshire and Chinese indigenous breed Meishan pigs, suppression subtractive hybridization was carried out and many genes were proved to be expressed significantly different in the two breeds. One gene highly expressed in Meishan but lowly expressed in Yorkshire specific library, shared strong homology with human pyruvate dehydrogenase kinase 4 (PDK4). Using semi-quantity and quantity PCR, We confirmed its differential expression between the two breeds. Temporal and spatial expression analysis indicated that porcine PDK4 gene is highly expressed in skeletal muscle and the highest in neonatal pigs. Complete cDNA cloning and sequence analysis revealed that porcine PDK4 gene contains an open reading frame of 1,221 bp. The deduced amino acid sequence showed conservation in evolution. A G/A mutation in intron 9 was identified and association analysis showed that it was significantly associated with intramuscular fat, muscle water content.
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Affiliation(s)
- Jing Lan
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, People's Republic of China
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16
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Wynn RM, Kato M, Chuang JL, Tso SC, Li J, Chuang DT. Pyruvate dehydrogenase kinase-4 structures reveal a metastable open conformation fostering robust core-free basal activity. J Biol Chem 2008; 283:25305-25315. [PMID: 18658136 PMCID: PMC2533096 DOI: 10.1074/jbc.m802249200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 07/23/2008] [Indexed: 02/04/2023] Open
Abstract
Human pyruvate dehydrogenase complex (PDC) is down-regulated by pyruvate dehydrogenase kinase (PDK) isoforms 1-4. PDK4 is overexpressed in skeletal muscle in type 2 diabetes, resulting in impaired glucose utilization. Here we show that human PDK4 has robust core-free basal activity, which is considerably higher than activity levels of other PDK isoforms stimulated by the PDC core. PDK4 binds the L3 lipoyl domain, but its activity is not significantly stimulated by any individual lipoyl domains or the core of PDC. The 2.0-A crystal structures of the PDK4 dimer with bound ADP reveal an open conformation with a wider active-site cleft, compared with that in the closed conformation epitomized by the PDK2-ADP structure. The open conformation in PDK4 shows partially ordered C-terminal cross-tails, in which the conserved DW (Asp(394)-Trp(395)) motif from one subunit anchors to the N-terminal domain of the other subunit. The open conformation fosters a reduced binding affinity for ADP, facilitating the efficient removal of product inhibition by this nucleotide. Alteration or deletion of the DW-motif disrupts the C-terminal cross-tail anchor, resulting in the closed conformation and the nearly complete inactivation of PDK4. Fluorescence quenching and enzyme activity data suggest that compounds AZD7545 and dichloroacetate lock PDK4 in the open and the closed conformational states, respectively. We propose that PDK4 with bound ADP exists in equilibrium between the open and the closed conformations. The favored metastable open conformation is responsible for the robust basal activity of PDK4 in the absence of the PDC core.
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Affiliation(s)
- R Max Wynn
- Department of Biochemistry, Dallas, Texas 75390-9038; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038
| | - Masato Kato
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038
| | | | - Shih-Chia Tso
- Department of Biochemistry, Dallas, Texas 75390-9038
| | - Jun Li
- Department of Biochemistry, Dallas, Texas 75390-9038
| | - David T Chuang
- Department of Biochemistry, Dallas, Texas 75390-9038; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038.
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17
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PDK-1 regulates lactate production in hypoxia and is associated with poor prognosis in head and neck squamous cancer. Br J Cancer 2008; 98:1975-84. [PMID: 18542064 PMCID: PMC2441961 DOI: 10.1038/sj.bjc.6604356] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Here we describe the expression and function of a HIF-1-regulated protein pyruvate dehydrogenase kinase-1 (PDK-1) in head and neck squamous cancer (HNSCC). Using RNAi to downregulate hypoxia-inducible PDK-1, we found that lactate and pyruvate excretion after 16-48 h of hypoxia was suppressed to normoxic levels. This indicates that PDK-1 plays an important role in maintaining glycolysis. Knockdown had no effect on proliferation or survival under hypoxia. The immunohistochemical expression of PDK-1 was assessed in 140 cases of HNSCC. PDK-1 expression was not expressed in normal tissues but was upregulated in HNSCC and found to be predominantly cytoplasmic with occasional strong focal nuclear expression. It was strongly related to poor outcome (P=0.005 split by median). These results indicate that HIF regulation of PDK-1 has a key role in maintaining lactate production in human cancer and that the investigation of PDK-1 inhibitors should be investigated for antitumour effects.
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18
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Kato M, Li J, Chuang JL, Chuang DT. Distinct structural mechanisms for inhibition of pyruvate dehydrogenase kinase isoforms by AZD7545, dichloroacetate, and radicicol. Structure 2007; 15:992-1004. [PMID: 17683942 PMCID: PMC2871385 DOI: 10.1016/j.str.2007.07.001] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 07/10/2007] [Accepted: 07/10/2007] [Indexed: 01/07/2023]
Abstract
Pyruvate dehydrogenase kinase (PDK) isoforms are molecular switches that downregulate the pyruvate dehydrogenase complex (PDC) by reversible phosphorylation in mitochondria. We have determined structures of human PDK1 or PDK3 bound to the inhibitors AZD7545, dichloroacetate (DCA), and radicicol. We show that the trifluoromethylpropanamide end of AZD7545 projects into the lipoyl-binding pocket of PDK1. This interaction results in inhibition of PDK1 and PDK3 activities by aborting kinase binding to the PDC scaffold. Paradoxically, AZD7545 at saturating concentrations robustly increases scaffold-free PDK3 activity, similar to the inner lipoyl domain. Good DCA density is present in the helix bundle in the N-terminal domain of PDK1. Bound DCA promotes local conformational changes that are communicated to both nucleotide-binding and lipoyl-binding pockets of PDK1, leading to the inactivation of kinase activity. Finally, radicicol inhibits kinase activity by binding directly to the ATP-binding pocket of PDK3, similar to Hsp90 and Topo VI from the same ATPase/kinase superfamily.
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Affiliation(s)
- Masato Kato
- Department of Internal Medicine University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jun Li
- Department of Biochemistry University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jacinta L. Chuang
- Department of Biochemistry University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - David T. Chuang
- Department of Internal Medicine University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence:
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19
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Tso SC, Kato M, Chuang JL, Chuang DT. Structural determinants for cross-talk between pyruvate dehydrogenase kinase 3 and lipoyl domain 2 of the human pyruvate dehydrogenase complex. J Biol Chem 2006; 281:27197-204. [PMID: 16849321 DOI: 10.1074/jbc.m604339200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyruvate dehydrogenase kinase isoforms (PDK1-4) are the molecular switch that down-regulates activity of the human pyruvate dehydrogenase complex through reversible phosphorylation. We showed previously that binding of the lipoyl domain 2 (L2) of the pyruvate dehydrogenase complex to PDK3 induces a "cross-tail" conformation in PDK3, resulting in an opening of the active site cleft and the stimulation of kinase activity. In the present study, we report that alanine substitutions of Leu-140, Glu-170, and Glu-179 in L2 markedly reduce binding affinities of these L2 mutants for PDK3. Unlike wildtype L2, binding of these L2 mutants to PDK3 does not preferentially reduce the affinity of PDK3 for ADP over ATP. The inefficient removal of product inhibition associated with ADP accounts for the decreased stimulation of PDK3 activity by these L2 variants. Serial truncations of the PDK3 C-terminal tail region either impede or abolish the binding of wild-type L2 to the PDK3 mutants, resulting in the reduction or absence of L2-enhanced kinase activity. Alanine substitutions of residues Leu-27, Phe-32, Phe-35, and Phe-48 in the lipoyl-binding pocket of PDK3 similarly nullify L2 binding and L2-stimulated PDK3 activity. Our results indicate that the above residues in L2 and residues in the C-terminal region and the lipoyl-binding pocket of PDK3 are critical determinants for the cross-talk between L2 and PDK3, which up-regulates PDK3 activity.
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Affiliation(s)
- Shih-Chia Tso
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA
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20
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Sugden MC, Holness MJ. Mechanisms underlying regulation of the expression and activities of the mammalian pyruvate dehydrogenase kinases. Arch Physiol Biochem 2006; 112:139-49. [PMID: 17132539 DOI: 10.1080/13813450600935263] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The mechanisms that control mammalian pyruvate dehydrogenase complex (PDC) activity include its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDKs 1 - 4). Here we review new developments in the regulation of the activities and expression of the PDKs, in particular PDK2 and PDK4, in relation to glucose and lipid homeostasis. This review describes recent advances relating to the acute and long-term modes of regulation of the PDKs, with particular emphasis on the regulatory roles of nuclear receptors including peroxisome proliferator-activated receptor (PPAR) alpha and Liver X receptor (LXR), PPAR gamma coactivator alpha (PGC-1alpha) and insulin, and the impact of changes in PDK activity and expression in glucose and lipid homeostasis. Since PDK4 may assist in lipid clearance when there is an imbalance between lipid delivery and oxidation, it may represent an attractive target for interventions aimed at rectifying abnormal lipid as well as glucose homeostasis in disease states.
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Affiliation(s)
- Mary C Sugden
- Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, Bart's and the London, Queen Mary's School of Medicine and Dentistry, London, UK.
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21
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Krause-Buchholz U, Gey U, Wünschmann J, Becker S, Rödel G. YIL042candYOR090cencode the kinase and phosphatase of theSaccharomyces cerevisiaepyruvate dehydrogenase complex. FEBS Lett 2006; 580:2553-60. [PMID: 16643908 DOI: 10.1016/j.febslet.2006.04.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 03/16/2006] [Accepted: 04/02/2006] [Indexed: 12/01/2022]
Abstract
In Saccharomyces cerevisiae the pyruvate dehydrogenase (PDH) complex is regulated by reversible phosphorylation of its Pda1p subunit. We here provide evidence that Pda1p is phosphorylated by the mitochondrial kinase Yil042cp. Deletion of YOR090c, encoding a putative mitochondrial phosphatase, results in a decreased PDH activity, indicating that Yor090cp acts as the corresponding PDH phosphatase. We demonstrate by means of blue native gel electrophoresis and tandem affinity purification that both enzymes are associated with the PDH complex.
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Affiliation(s)
- Udo Krause-Buchholz
- Institut für Genetik, Technische Universität Dresden, 01062 Dresden, Germany.
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22
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Kato M, Chuang JL, Tso SC, Wynn RM, Chuang DT. Crystal structure of pyruvate dehydrogenase kinase 3 bound to lipoyl domain 2 of human pyruvate dehydrogenase complex. EMBO J 2005; 24:1763-74. [PMID: 15861126 PMCID: PMC1142596 DOI: 10.1038/sj.emboj.7600663] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 04/06/2005] [Indexed: 01/22/2023] Open
Abstract
The human pyruvate dehydrogenase complex (PDC) is regulated by reversible phosphorylation by four isoforms of pyruvate dehydrogenase kinase (PDK). PDKs phosphorylate serine residues in the dehydrogenase (E1p) component of PDC, but their amino-acid sequences are unrelated to eukaryotic Ser/Thr/Tyr protein kinases. PDK3 binds to the inner lipoyl domains (L2) from the 60-meric transacetylase (E2p) core of PDC, with concomitant stimulated kinase activity. Here, we present crystal structures of the PDK3-L2 complex with and without bound ADP or ATP. These structures disclose that the C-terminal tail from one subunit of PDK3 dimer constitutes an integral part of the lipoyl-binding pocket in the N-terminal domain of the opposing subunit. The two swapped C-terminal tails promote conformational changes in active-site clefts of both PDK3 subunits, resulting in largely disordered ATP lids in the ADP-bound form. Our structural and biochemical data suggest that L2 binding stimulates PDK3 activity by disrupting the ATP lid, which otherwise traps ADP, to remove product inhibition exerted by this nucleotide. We hypothesize that this allosteric mechanism accounts, in part, for E2p-augmented PDK3 activity.
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Affiliation(s)
- Masato Kato
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jacinta L Chuang
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shih-Chia Tso
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - R Max Wynn
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - David T Chuang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Departments of Biochemistry and Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA. Tel.: +1 214 648 2457; Fax: +1 214 648 8856; E-mail:
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Sugden MC, Holness MJ. Recent advances in mechanisms regulating glucose oxidation at the level of the pyruvate dehydrogenase complex by PDKs. Am J Physiol Endocrinol Metab 2003; 284:E855-62. [PMID: 12676647 DOI: 10.1152/ajpendo.00526.2002] [Citation(s) in RCA: 364] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The mitochondrial pyruvate dehydrogenase complex (PDC) catalyzes the oxidative decarboxylation of pyruvate, linking glycolysis to the tricarboxylic acid cycle and fatty acid (FA) synthesis. Knowledge of the mechanisms that regulate PDC activity is important, because PDC inactivation is crucial for glucose conservation when glucose is scarce, whereas adequate PDC activity is required to allow both ATP and FA production from glucose. The mechanisms that control mammalian PDC activity include its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDKs 1-4) and its dephosphorylation (activation, reactivation) by the pyruvate dehydrogenase phosphate phosphatases (PDPs 1 and 2). Isoform-specific differences in kinetic parameters, regulation, and phosphorylation site specificity of the PDKs introduce variations in the regulation of PDC activity in differing endocrine and metabolic states. In this review, we summarize recent significant advances in our knowledge of the mechanisms regulating PDC with emphasis on the PDKs, in particular PDK4, whose expression is linked with sustained changes in tissue lipid handling and which may represent an attractive target for pharmacological interventions aimed at modulating whole body glucose, lipid, and lactate homeostasis in disease states.
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Affiliation(s)
- Mary C Sugden
- Department of Diabetes and Metabolic Medicine, Division of General and Developmental Medicine, Bart's and the London, Queen Mary's School of Medicine and Dentistry, University of London, Mile End Road, London E1 4NS, United Kingdom.
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25
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Roche TE, Baker JC, Yan X, Hiromasa Y, Gong X, Peng T, Dong J, Turkan A, Kasten SA. Distinct regulatory properties of pyruvate dehydrogenase kinase and phosphatase isoforms. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2002; 70:33-75. [PMID: 11642366 DOI: 10.1016/s0079-6603(01)70013-x] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mammalian pyruvate dehydrogenase complex (PDC) plays central and strategic roles in the control of the use of glucose-linked substrates as sources of oxidative energy or as precursors in the biosynthesis of fatty acids. The activity of this mitochondrial complex is regulated by the continuous operation of competing pyruvate dehydrogenase kinase (PDK) and pyruvate dehydrogenase phosphatase (PDP) reactions. The resulting interconversion cycle determines the fraction of active (nonphosphorylated) pyruvate dehydrogenase (E1) component. Tissue-specific and metabolic state-specific control is achieved by the selective expression and distinct regulatory properties of at least four PDK isozymes and two PDP isozymes. The PDK isoforms are members of a family of serine kinases that are not structurally related to cytoplasmic Ser/Thr/Tyr kinases. The catalytic subunits of the PDP isoforms are Mg2+-dependent members of the phosphatase 2C family that has binuclear metal-binding sites within the active site. The dihydrolipoyl acetyltransferase (E2) and the dihydrolipoyl dehydrogenase-binding protein (E3BP) are multidomain proteins that form the oligomeric core of the complex. One or more of their three lipoyl domains (two in E2) selectively bind each PDK and PDP1. These adaptive interactions predominantly influence the catalytic efficiencies and effector control of these regulatory enzymes. When fatty acids are the preferred source of acetyl-CoA and NADH, feedback inactivation of PDC is accomplished by the activity of certain kinase isoforms being stimulated upon preferentially binding a lipoyl domain containing a reductively acetylated lipoyl group. PDC activity is increased in Ca2+-sensitive tissues by elevating PDP1 activity via the Ca2+-dependent binding of PDP1 to a lipoyl domain of E2. During starvation, the irrecoverable loss of glucose carbons is restricted by minimizing PDC activity due to high kinase activity that results from the overexpression of specific kinase isoforms. Overexpression of the same PDK isoforms deleteriously hinders glucose consumption in unregulated diabetes.
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Affiliation(s)
- T E Roche
- Department of Biochemistry, Kansas State University, Manhattan 66506-3702, USA
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26
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Sugden MC, Bulmer K, Augustine D, Holness MJ. Selective modification of pyruvate dehydrogenase kinase isoform expression in rat pancreatic islets elicited by starvation and activation of peroxisome proliferator-activated receptor-alpha: implications for glucose-stimulated insulin secretion. Diabetes 2001; 50:2729-36. [PMID: 11723055 DOI: 10.2337/diabetes.50.12.2729] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The pyruvate dehydrogenase complex (PDC) has a pivotal role in islet metabolism. The pyruvate dehydrogenase kinases (PDK1-4) regulate glucose oxidation through inhibitory phosphorylation of PDC. Starvation increases islet PDK activity (Am J Physiol Endocrinol Metab 270:E988-E994, 1996). In this study, using antibodies against PDK1, PDK2, and PDK4 (no sufficiently specific antibodies are as yet available for PDK3), we identified the PDK isoform profile of the pancreatic islet and delineated the effects of starvation (48 h) on protein expression of individual PDK isoforms. Rat islets were demonstrated to contain all three PDK isoforms, PDK1, PDK2, and PDK4. Using immunoblot analysis with antibodies raised against the individual recombinant PDK isoforms, we demonstrated increased islet protein expression of PDK4 in response to starvation (2.3-fold; P < 0.01). Protein expression of PDK1 and PDK2 was suppressed in response to starvation (by 27% [P < 0.01] and 10% [NS], respectively). We demonstrated that activation of peroxisome proliferator-activated receptor-alpha (PPAR-alpha) by the selective agonist WY14,643 for 24 h in vivo leads to specific upregulation of islet PDK4 protein expression by 1.8-fold (P < 0.01), in the absence of change in islet PDK1 and PDK2 protein expression but in conjunction with a 2.2-fold increase (P < 0.01) in islet PPAR-alpha protein expression. Thus, although no changes in islet PPAR-alpha expression were observed after the starvation protocol, activation of PPAR-alpha in vivo may be a potential mechanism underlying upregulation of islet PDK4 protein expression in starvation. We evaluated the effects of antecedent changes in PDK profile and/or PPAR-alpha activation induced by starvation or PPAR-alpha activation in vivo on glucose-stimulated insulin secretion (GSIS) in isolated islets. GSIS at 20 mmol/l glucose was modestly impaired on incubation with exogenous triglyceride (1 mmol/l triolein) ( approximately 20% inhibition; P < 0.05) in islets from fed rats. Starvation (48 h) impaired GSIS in the absence of triolein (by 57%; P < 0.001), but GSIS after the further addition of triolein did not differ significantly between islets from fed or starved rats. GSIS by islets prepared from WY14,643-treated fed rats did not differ significantly from that seen with islets from control fed rats, and the response to triolein addition resembled that of islets prepared from fed rather than starved rats. PPAR-alpha activation in vivo led to increased insulin secretion at low glucose concentrations. Our results are discussed in relation to the potential impact of changes in islet PDK profile on the insulin secretory response to lipid and of PPAR-alpha activation in the cause of fasting hyperinsulinemia.
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Affiliation(s)
- M C Sugden
- Department of Diabetes and Metabolic Medicine, Division of General and Developmental Medicine, St. Bartholomew's and the Royal London School of Medicine and Dentistry, Queen Mary, University of London, London, U.K.
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Machius M, Chuang JL, Wynn RM, Tomchick DR, Chuang DT. Structure of rat BCKD kinase: nucleotide-induced domain communication in a mitochondrial protein kinase. Proc Natl Acad Sci U S A 2001; 98:11218-23. [PMID: 11562470 PMCID: PMC58710 DOI: 10.1073/pnas.201220098] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial protein kinases (mPKs) are molecular switches that down-regulate the oxidation of branched-chain alpha-ketoacids and pyruvate. Elevated levels of these metabolites are implicated in disease states such as insulin-resistant Type II diabetes, branched-chain ketoaciduria, and primary lactic acidosis. We report a three-dimensional structure of a member of the mPK family, rat branched-chain alpha-ketoacid dehydrogenase kinase (BCK). BCK features a characteristic nucleotide-binding domain and a four-helix bundle domain. These two domains are reminiscent of modules found in protein histidine kinases (PHKs), which are involved in two-component signal transduction systems. Unlike PHKs, BCK dimerizes through direct interaction of two opposing nucleotide-binding domains. Nucleotide binding to BCK is uniquely mediated by both potassium and magnesium. Binding of ATP induces disorder-order transitions in a loop region at the nucleotide-binding site. These structural changes lead to the formation of a quadruple aromatic stack in the interface between the nucleotide-binding domain and the four-helix bundle domain, where they induce a movement of the top portion of two helices. Phosphotransfer induces further ordering of the loop region, effectively trapping the reaction product ADP, which explains product inhibition in mPKs. The BCK structure is a prototype for all mPKs and will provide a framework for structure-assisted inhibitor design for this family of kinases.
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Affiliation(s)
- M Machius
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
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Korotchkina LG, Patel MS. Probing the mechanism of inactivation of human pyruvate dehydrogenase by phosphorylation of three sites. J Biol Chem 2001; 276:5731-8. [PMID: 11092882 DOI: 10.1074/jbc.m007558200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activity of the mammalian pyruvate dehydrogenase complex (PDC) is regulated by phosphorylation-dephosphorylation of three serine residues (designated site 1, Ser-264; site 2, Ser-271; site 3, Ser-203) in the alpha subunit of the pyruvate dehydrogenase (E1) component. Substitutions of the phosphorylation sites were generated by site-directed mutagenesis. Glutamate (S1E) and aspartate (S1D) substitutions at site 1 resulted in the complete loss of PDC activity; however, these mutants were variably active in the decarboxylation and 2,6-dichlorophenolindophenol assays. S1Q had only 3% of wild-type PDC activity. The apparent K(m) values for pyruvate increased for the mutants of site 1 when determined in the 2,6-dichlorophenolindophenol assay. The substitutions at sites 2 and 3 caused only moderate reductions in activity in the three assays. S3E had a 27-fold increase in the apparent K(m) for thiamine pyrophosphate and 8-fold increase in the K(i) for pyrophosphate. Site 3 was almost completely protected from phosphorylation by thiamine pyrophosphate. The results show that the size rather than negative charge of the substituted amino acid residue affects the active site of E1 and that modification of each of the three serine residues affect the active site in a site-specific manner for its ability to bind the cofactor and substrates.
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Affiliation(s)
- L G Korotchkina
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York 14214, USA
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Wu J, Ohta N, Zhao JL, Newton A. A novel bacterial tyrosine kinase essential for cell division and differentiation. Proc Natl Acad Sci U S A 1999; 96:13068-73. [PMID: 10557274 PMCID: PMC23901 DOI: 10.1073/pnas.96.23.13068] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Protein kinases play central roles in the regulation of eukaryotic and prokaryotic cell growth, division, and differentiation. The Caulobacter crescentus divL gene encodes a novel bacterial tyrosine kinase essential for cell viability and division. Although the DivL protein is homologous to the ubiquitous bacterial histidine protein kinases (HPKs), it differs from previously studied members of this protein kinase family in that it contains a tyrosine residue (Tyr-550) in the conserved H-box instead of a histidine residue, which is the expected site of autophosphorylation. DivL is autophosphorylated on Tyr-550 in vitro, and this tyrosine residue is essential for cell viability and regulation of the cell division cycle. Purified DivL also catalyzes phosphorylation of CtrA and activates transcription in vitro of the cell cycle-regulated fliF promoter. Suppressor mutations in ctrA bypass the conditional cell division phenotype of cold-sensitive divL mutants, providing genetic evidence that DivL function in cell cycle and developmental regulation is mediated, at least in part, by the global response regulator CtrA. DivL is the only reported HPK homologue whose function has been shown to require autophosphorylation on a tyrosine, and, thus, it represents a new class of kinases within this superfamily of protein kinases.
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Affiliation(s)
- J Wu
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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Abstract
Signal transduction in microorganisms and plants is often mediated by His-Asp phosphorelay systems. Two conserved families of proteins are centrally involved: histidine protein kinases and phospho-aspartyl response regulators. The kinases generally function in association with sensory elements that regulate their activities in response to environmental signals. A sequence analysis with 348 histidine kinase domains reveals that this family consists of distinct subgroups. A comparative sequence analysis with 298 available receiver domain sequences of cognate response regulators demonstrates a significant correlation between kinase and regulator subfamilies. These findings suggest that different subclasses of His-Asp phosphorelay systems have evolved independently of one another.
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Affiliation(s)
- T W Grebe
- Department of Molecular Biology, Princeton University, NJ 08544, USA
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Schenk PW, Snaar-Jagalska BE. Signal perception and transduction: the role of protein kinases. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1449:1-24. [PMID: 10076047 DOI: 10.1016/s0167-4889(98)00178-5] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cells can react to environmental changes by transduction of extracellular signals, to produce intracellular responses. Membrane-impermeable signal molecules are recognized by receptors, which are localized on the plasma membrane of the cell. Binding of a ligand can result in the stimulation of an intrinsic enzymatic activity of its receptor or the modulation of a transducing protein. The modulation of one or more intracellular transducing proteins can finally lead to the activation or inhibition of a so-called 'effector protein'. In many instances, this also results in altered gene expression. Phosphorylation by protein kinases is one of the most common and important regulatory mechanisms in signal transmission. This review discusses the non-channel transmembrane receptors and their downstream signaling, with special focus on the role of protein kinases.
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Affiliation(s)
- P W Schenk
- Section of Cell Biology, Institute of Molecular Plant Sciences, Leiden University, P.O. Box 9505, 2300 RA, Leiden, Netherlands
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