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Mudaliar D, Mansky RH, White A, Baudhuin G, Hawkinson J, Wong H, Walters MA, Gomez-Pastor R. Discovery of a CK2α'-Biased ATP-Competitive Inhibitor from a High-Throughput Screen of an Allosteric-Inhibitor-Like Compound Library. ACS Chem Neurosci 2024; 15:2703-2718. [PMID: 38908003 DOI: 10.1021/acschemneuro.4c00062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2024] Open
Abstract
Protein kinase CK2 is a holoenzyme composed of two regulatory subunits (CK2β) and two catalytic subunits (CK2α and CK2α'). CK2 controls several cellular processes, including proliferation, inflammation, and cell death. However, CK2α and CK2α' possess different expression patterns and substrates and therefore impact each of these processes differently. Elevated CK2α participates in the development of cancer, while increased CK2α' has been associated with neurodegeneration, especially Huntington's disease (HD). HD is a fatal disease for which no effective therapies are available. Genetic deletion of CK2α' in HD mouse models has ameliorated neurodegeneration. Therefore, pharmacological inhibition of CK2α' presents a promising therapeutic strategy for treating HD. However, current CK2 inhibitors are unable to discriminate between CK2α and CK2α' due to their high structural homology, especially in the targeted ATP-binding site. Using computational analyses, we found a potential type IV ("D" pocket) allosteric site that contained different residues between CK2α and CK2α' and was distal from the ATP-binding pocket featured in both kinases. We decided to look for allosteric modulators that might interact in a biased fashion with the type IV pocket on both CK2α and CK2α'. We screened a commercial library containing ∼29,000 allosteric-kinase-inhibitor-like compounds using a CK2α' activity-dependent ADP-Glo Kinase assay. Obtained hits were counter-screened against CK2α using the ADP-Glo Kinase assay, revealing two CK2α'-biased compounds. These two compounds might serve as the basis for further medicinal chemistry optimization for the potential treatment of HD.
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Affiliation(s)
- Deepti Mudaliar
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Rachel H Mansky
- Department of Neuroscience, School of Medicine, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Angel White
- Department of Neuroscience, School of Medicine, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Grace Baudhuin
- Department of Neuroscience, School of Medicine, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | | | - Henry Wong
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Michael A Walters
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Rocio Gomez-Pastor
- Department of Neuroscience, School of Medicine, University of Minnesota, Minneapolis, Minnesota 55414, United States
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2
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Mudaliar D, Mansky RH, White A, Baudhuin G, Hawkinson J, Wong H, Walters MA, Gomez-Pastor R. Identification of CK2α' selective inhibitors by the screening of an allosteric-kinase-inhibitor-like compound library. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576328. [PMID: 38328231 PMCID: PMC10849513 DOI: 10.1101/2024.01.18.576328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Protein Kinase CK2 is a holoenzyme composed of two regulatory subunits (CK2β) and two catalytic subunits (CK2α and CK2α'). CK2 controls several cellular processes including proliferation, inflammation, and cell death. However, CK2α and CK2α' possess different expression patterns and substrates and therefore impact each of these processes differently. Elevated CK2α participates in the development of cancer, while increased CK2α' has been associated with neurodegeneration, especially Huntington's disease (HD). HD is a fatal disease for which no effective therapies are available. Genetic deletion of CK2α' in HD mouse models has ameliorated neurodegeneration. Therefore, pharmacological inhibition of CK2α' presents a promising therapeutic strategy for treating HD. However, current CK2 inhibitors are unable to discriminate between CK2α and CK2α' due to their high structural homology, especially in the targeted ATP binding site. Using computational analyses, we found a potential Type IV ("D" pocket) allosteric site on CK2α' that contained different residues than CK2α and was distal from the ATP binding pocket featured in both kinases. With this potential allosteric site in mind, we screened a commercial library containing ~29,000 allosteric-kinase-inhibitor-like compounds using a CK2α' activity-dependent ADP-Glo™ Kinase assay. Obtained hits were counter-screened against CK2α revealing two CK2α' selective compounds. These two compounds might serve as the basis for further medicinal chemistry optimization for the potential treatment of HD.
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Affiliation(s)
- Deepti Mudaliar
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Rachel H Mansky
- Department of Neuroscience, University of Minnesota, School of Medicine, Minneapolis, Minnesota 55414, United States
| | - Angel White
- Department of Neuroscience, University of Minnesota, School of Medicine, Minneapolis, Minnesota 55414, United States
| | - Grace Baudhuin
- Department of Neuroscience, University of Minnesota, School of Medicine, Minneapolis, Minnesota 55414, United States
| | - Jon Hawkinson
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Henry Wong
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Michael A Walters
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Rocio Gomez-Pastor
- Department of Neuroscience, University of Minnesota, School of Medicine, Minneapolis, Minnesota 55414, United States
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Ghildyal R, Teng MN, Tran KC, Mills J, Casarotto MG, Bardin PG, Jans DA. Nuclear Transport of Respiratory Syncytial Virus Matrix Protein Is Regulated by Dual Phosphorylation Sites. Int J Mol Sci 2022; 23:ijms23147976. [PMID: 35887322 PMCID: PMC9317576 DOI: 10.3390/ijms23147976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/02/2022] [Accepted: 07/06/2022] [Indexed: 02/04/2023] Open
Abstract
Respiratory syncytial virus (RSV) is a major cause of respiratory infections in infants and the elderly. Although the RSV matrix (M) protein has key roles in the nucleus early in infection, and in the cytoplasm later, the molecular basis of switching between the nuclear and cytoplasmic compartments is not known. Here, we show that protein kinase CK2 can regulate M nucleocytoplasmic distribution, whereby inhibition of CK2 using the specific inhibitor 4,5,6,7-tetrabromobenzo-triazole (TBB) increases M nuclear accumulation in infected cells as well as when ectopically expressed in transfected cells. We use truncation/mutagenic analysis for the first time to show that serine (S) 95 and threonine (T) 205 are key CK2 sites that regulate M nuclear localization. Dual alanine (A)-substitution to prevent phosphorylation abolished TBB- enhancement of nuclear accumulation, while aspartic acid (D) substitution to mimic phosphorylation at S95 increased nuclear accumulation. D95 also induced cytoplasmic aggregate formation, implying that a negative charge at S95 may modulate M oligomerization. A95/205 substitution in recombinant RSV resulted in reduced virus production compared with wild type, with D95/205 substitution resulting in an even greater level of attenuation. Our data support a model where unphosphorylated M is imported into the nucleus, followed by phosphorylation of T205 and S95 later in infection to facilitate nuclear export and cytoplasmic retention of M, respectively, as well as oligomerization/virus budding. In the absence of widely available, efficacious treatments to protect against RSV, the results raise the possibility of antiviral strategies targeted at CK2.
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Affiliation(s)
- Reena Ghildyal
- Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Canberra 2617, Australia
- Correspondence: ; Tel.: +612-6201-5755
| | - Michael N. Teng
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; (M.N.T.); (K.C.T.)
| | - Kim C. Tran
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; (M.N.T.); (K.C.T.)
| | - John Mills
- Faculty of Medicine, Monash University, Burnet Institute for Medical Research, The Alfred Hospital Department of Infectious Diseases, Melbourne 3004, Australia;
| | - Marco G. Casarotto
- Research School of Biology, Australian National University, Canberra 2601, Australia;
| | - Philip G. Bardin
- Monash Lung & Sleep and Hudson Institute, Monash University, Melbourne 3181, Australia;
| | - David A. Jans
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash University, Melbourne 3181, Australia;
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CK2 Regulation: Perspectives in 2021. Biomedicines 2021; 9:biomedicines9101361. [PMID: 34680478 PMCID: PMC8533506 DOI: 10.3390/biomedicines9101361] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/23/2021] [Accepted: 09/26/2021] [Indexed: 12/20/2022] Open
Abstract
The protein kinase CK2 (CK2) family encompasses a small number of acidophilic serine/threonine kinases that phosphorylate substrates involved in numerous biological processes including apoptosis, cell proliferation, and the DNA damage response. CK2 has also been implicated in many human malignancies and other disorders including Alzheimer′s and Parkinson’s diseases, and COVID-19. Interestingly, no single mechanism describes how CK2 is regulated, including activation by external proteins or domains, phosphorylation, or dimerization. Furthermore, the kinase has an elongated activation loop that locks the kinase into an active conformation, leading CK2 to be labelled a constitutively active kinase. This presents an interesting paradox that remains unanswered: how can a constitutively active kinase regulate biological processes that require careful control? Here, we highlight a selection of studies where CK2 activity is regulated at the substrate level, and discuss them based on the regulatory mechanism. Overall, this review describes numerous biological processes where CK2 activity is regulated, highlighting how a constitutively active kinase can still control numerous cellular activities. It is also evident that more research is required to fully elucidate the mechanisms that regulate CK2 and what causes aberrant CK2 signaling in disease.
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Schnitzler A, Niefind K. Structural basis for the design of bisubstrate inhibitors of protein kinase CK2 provided by complex structures with the substrate-competitive inhibitor heparin. Eur J Med Chem 2021; 214:113223. [PMID: 33571828 DOI: 10.1016/j.ejmech.2021.113223] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/20/2021] [Accepted: 01/20/2021] [Indexed: 12/27/2022]
Abstract
The Ser/Thr kinase CK2, a member of the superfamily of eukaryotic protein kinases, has an acidophilic substrate profile with the substrate recognition sequence S/T-D/E-X-D/E, and it is inhibited by polyanionic substances like heparin. The latter, a highly sulphated glucosamino glycan composed mainly of repeating 2-O-sulpho-α-l-idopyranuronic acid/N,O6-disulpho-α-d-glucosamine disaccharide units, is the longest known substrate-competitive CK2 inhibitor. The structural basis of CK2's preference for anionic substrates and substrate-competitive inhibitors is only vaguely known which limits the value of the substrate-binding region for the structure-based development of CK2 bisubstrate inhibitors. Here, a tetragonal and a monoclinic co-crystal structure of CK2α, the catalytic subunit of CK2, with a decameric heparin fragment are described. In the tetragonal structure, the heparin molecule binds to the polybasic stretch at the beginning of CK2α's helix αC, whereas in the monoclinic structure it occupies the central substrate-recognition region around the P+1 loop. Together, the structures rationalize the inhibitory efficacy of heparin fragments as a function of chain length. The monoclinic CK2α/heparin structure, in which the heparin fragment is particularly well defined, is the first CK2 structure with an anionic inhibitor of considerable size at the central part of the substrate-recognition site. The bound heparin fragment is so close to the binding site of ATP-competitive inhibitors that it can guide the design of linkers and pave the way to efficient CK2 bisubstrate inhibitors in the future.
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Affiliation(s)
- Alexander Schnitzler
- Universität zu Köln, Department für Chemie, Institut für Biochemie, Zülpicher Straße 47, D-50674 Köln, Germany
| | - Karsten Niefind
- Universität zu Köln, Department für Chemie, Institut für Biochemie, Zülpicher Straße 47, D-50674 Köln, Germany.
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D'Amore C, Salizzato V, Borgo C, Cesaro L, Pinna LA, Salvi M. A Journey through the Cytoskeleton with Protein Kinase CK2. Curr Protein Pept Sci 2019; 20:547-562. [PMID: 30659536 DOI: 10.2174/1389203720666190119124846] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/21/2018] [Accepted: 01/09/2019] [Indexed: 01/15/2023]
Abstract
Substrate pleiotropicity, a very acidic phosphorylation consensus sequence, and an apparent uncontrolled activity, are the main features of CK2, a Ser/Thr protein kinase that is required for a plethora of cell functions. Not surprisingly, CK2 appears to affect cytoskeletal structures and correlated functions such as cell shape, mechanical integrity, cell movement and division. This review outlines our current knowledge of how CK2 regulates cytoskeletal structures, and discusses involved pathways and molecular mechanisms.
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Affiliation(s)
- Claudio D'Amore
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Valentina Salizzato
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.,CNR Institute of Neurosciences, Via U. Bassi 58/B, Padova, Italy
| | - Christian Borgo
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Luca Cesaro
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Lorenzo A Pinna
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.,CNR Institute of Neurosciences, Via U. Bassi 58/B, Padova, Italy
| | - Mauro Salvi
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
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7
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Thiazole- and selenazole-comprising high-affinity inhibitors possess bright microsecond-scale photoluminescence in complex with protein kinase CK2. Bioorg Med Chem 2018; 26:5062-5068. [PMID: 30217463 DOI: 10.1016/j.bmc.2018.09.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/30/2018] [Accepted: 09/03/2018] [Indexed: 12/14/2022]
Abstract
A previously disclosed protein kinase (PK) CK2-selective inhibitor 4-(2-amino-1,3-thiazol-5-yl)benzoic acid (ATB) and its selenium-containing counterpart (ASB) revealed remarkable room temperature phosphorescence when bound to the ATP pocket of the protein kinase CK2. Conjugation of these fragments with a mimic of CK2 substrate peptide resulted in bisubstrate inhibitors with increased affinity towards the kinase. Attachment of the fluorescent acceptor dye 5-TAMRA to the conjugates led to significant enhancement of intensity of long-lifetime (microsecond-scale) photoluminescence of both sulfur- and selenium-containing compounds. The developed photoluminescent probes make possible selective determination of the concentration of CK2 in cell lysates and characterization of CK2 inhibitors by means of time-gated measurement of photoluminescence.
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8
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Viht K, Saaver S, Vahter J, Enkvist E, Lavogina D, Sinijärv H, Raidaru G, Guerra B, Issinger OG, Uri A. Acetoxymethyl Ester of Tetrabromobenzimidazole-Peptoid Conjugate for Inhibition of Protein Kinase CK2 in Living Cells. Bioconjug Chem 2015; 26:2324-35. [PMID: 26559659 DOI: 10.1021/acs.bioconjchem.5b00383] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
CK2 is a ubiquitous serine/threonine protein kinase, which has the potential to catalyze the generation of a large proportion of the human phosphoproteome. Due to its role in numerous cellular functions and general anti-apoptotic activity, CK2 is an important target of research with therapeutic potential. This emphasizes the need for cell-permeable highly potent and selective inhibitors and photoluminescence probes of CK2 for investigating the protein phosphorylation networks in living cells. Previously, we had developed bisubstrate inhibitors for CK2 (CK2-targeted ARCs) that showed remarkable affinity (KD < 1 nM) and selectivity, but lacked proteolytic stability and plasma membrane permeability. In this report, the structures of CK2-targeted ARCs were modified for the application in live cells. Based on structure-activity studies, proteolytically stable achiral oligoanionic peptoid conjugates of 4,5,6,7-tetrabromo-1H-benzimidazole (TBBz) were constructed. Affinity of the conjugates toward CK2 reached subnanomolar range. Acetoxymethyl (AM) prodrug strategy was applied for loading TBBz-peptoid conjugates into living cells. The uptake of inhibitors was visualized by live cell imaging and the reduction of the phosphorylation levels of two CK2-related phosphosites, Cdc37 pSer13 and NFκB pSer529, was demonstrated by Western blot analysis.
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Affiliation(s)
- Kaido Viht
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Siiri Saaver
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Jürgen Vahter
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Erki Enkvist
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Darja Lavogina
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Hedi Sinijärv
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Gerda Raidaru
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
| | - Barbara Guerra
- Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, DK-5230 Odense, Denmark
| | - Olaf-Georg Issinger
- Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, DK-5230 Odense, Denmark.,KinaseDetect Aps , Skovvej 22, 6340 Kruså, Denmark
| | - Asko Uri
- Institute of Chemistry, University of Tartu , Ravila 14A, 50411 Tartu, Estonia
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9
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Samukange V, Yasukawa K, Inouye K. Effects of heparin and cholesterol sulfate on the activity and stability of human matrix metalloproteinase 7. Biosci Biotechnol Biochem 2014; 78:41-8. [PMID: 25036482 DOI: 10.1080/09168451.2014.878213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Sulfated glycosaminoglycans and sulfated lipids are involved in the biological functions of human matrix metalloproteinase 7 (MMP-7). In this study, the effects of heparin and cholesterol sulfate (CS) on the activity and stability of MMP-7 in the hydrolysis of a synthetic substrate, (7-methoxycoumarin-4-yl)acetyl-l-Pro-l-Leu-Gly-l-Leu-[N(3)-(2,4-dinitrophenyl)-l-2,3-diaminopropionyl]-l-Ala-l-Arg-NH2, were examined. Heparin increased activity by decreasing Km, and the Km values for 0 and 50 μM heparin were 57 ± 8 and 19 ± 5 μM, respectively. CS decreased activity in a non-competitive inhibitory manner with a Ki value of 11 ± 3 μM. In thermal incubation at 50-70 °C, heparin increased relative activity (the ratio of kcat/Km of MMP-7 with incubation to that without it), while CS decreased relative activity. These results indicate that heparin increases the activity and stability of MMP-7, while CS decreases them.
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Affiliation(s)
- Vimbai Samukange
- a Division of Food Science and Biotechnology , Graduate School of Agriculture, Kyoto University , Kyoto , Japan
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10
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Abstract
Red blood cell invasion by the malaria parasite Plasmodium falciparum relies on a complex protein network that uses low and high affinity receptor–ligand interactions. Signal transduction through the action of specific kinases is a control mechanism for the orchestration of this process. In the present study we report on the phosphorylation of the CPD (cytoplasmic domain) of P. falciparum Rh2b (reticulocyte homologue protein 2b). First, we identified Ser3233 as the sole phospho-acceptor site in the CPD for in vitro phosphorylation by parasite extract. We provide several lines of evidence that this phosphorylation is mediated by PfCK2 (P. falciparum casein kinase 2): phosphorylation is cAMP independent, utilizes ATP as well as GTP as phosphate donors, is inhibited by heparin and tetrabromocinnamic acid, and is mediated by purified PfCK2. We raised a phospho-specific antibody and showed that Ser3233 phosphorylation occurs in the parasite prior to host cell egress. We analysed the spatiotemporal aspects of this phosphorylation using immunoprecipitated endogenous Rh2b and minigenes expressing the CPD either at the plasma or rhoptry membrane. Phosphorylation of Rh2b is not spatially restricted to either the plasma or rhoptry membrane and most probably occurs before Rh2b is translocated from the rhoptry neck to the plasma membrane.
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11
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Barry WH, Zhang XQ, Halkos ME, Vinten-Johansen J, Saegusa N, Spitzer KW, Matsuoka N, Sheets M, Rao NV, Kennedy TP. Nonanticoagulant heparin reduces myocyte Na+ and Ca2+ loading during simulated ischemia and decreases reperfusion injury. Am J Physiol Heart Circ Physiol 2009; 298:H102-11. [PMID: 19855066 DOI: 10.1152/ajpheart.00316.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Heparin desulfated at the 2-O and 3-O positions (ODSH) decreases canine myocardial reperfusion injury. We hypothesized that this occurs from effects on ion channels rather than solely from anti-inflammatory activities, as previously proposed. We studied closed-chest pigs with balloon left anterior descending coronary artery occlusion (75-min) and reperfusion (3-h). ODSH effects on [Na(+)](i) (Na Green) and [Ca(2+)](i) (Fluo-3) were measured by flow cytometry in rabbit ventricular myocytes after 45-min of simulated ischemia [metabolic inhibition with 2 mM cyanide, 0 glucose, 37 degrees C, pacing at 0.5 Hz; i.e., pacing-metabolic inhibition (PMI)]. Na(+)/Ca(2+) exchange (NCX) activity and Na(+) channel function were assessed by voltage clamping. ODSH (15 mg/kg) 5 min before reperfusion significantly decreased myocardial necrosis, but neutrophil influx into reperfused myocardium was not consistently reduced. ODSH (100 microg/ml) reduced [Na(+)](i) and [Ca(2+)](i) during PMI. The NCX inhibitor KB-R7943 (10 microM) or the late Na(+) current (I(Na-L)) inhibitor ranolazine (10 microM) reduced [Ca(2+)](i) during PMI and prevented effects of ODSH on Ca(2+) loading. ODSH also reduced the increase in Na(+) loading in paced myocytes caused by 10 nM sea anemone toxin II, a selective activator of I(Na-L). ODSH directly stimulated NCX and reduced I(Na-L). These results suggest that in the intact heart ODSH reduces Na(+) influx during early reperfusion, when I(Na-L) is activated by a burst of reactive oxygen production. This reduces Na(+) overload and thus Ca(2+) influx via NCX. Stimulation of Ca(2+) extrusion via NCX later after reperfusion may also reduce myocyte Ca(2+) loading and decrease infarct size.
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Affiliation(s)
- William H Barry
- School of Medicine, Division of Cardiology, University of Utah Medical Center, Salt Lake City, UT 84132, USA.
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12
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Lombardo VA, Armas P, Weiner AMJ, Calcaterra NB. In vitro embryonic developmental phosphorylation of the cellular nucleic acid binding protein by cAMP-dependent protein kinase, and its relevance for biochemical activities. FEBS J 2006; 274:485-97. [PMID: 17166179 DOI: 10.1111/j.1742-4658.2006.05596.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The zinc-finger cellular nucleic acid binding protein (CNBP) is a strikingly conserved single-stranded nucleic acid binding protein essential for normal forebrain formation during mouse and chick embryogenesis. CNBP cDNAs from a number of vertebrates have been cloned and analysed. CNBP is mainly conformed by seven retroviral Cys-Cys-His-Cys zinc-knuckles and a glycine/arginine rich region box. CNBP amino acid sequences show a putative Pro-Glu-Ser-Thr site of proteolysis and several putative phosphorylation sites. In this study, we analysed CNBP phosphorylation by embryonic kinases and its consequences on CNBP biochemical activities. We report that CNBP is differentially phosphorylated by Danio rerio embryonic extracts. In vitro CNBP phosphorylation is basal and constant at early embryonic developmental stages, it begins to increase after mid-blastula transition stage reaching the highest level at 48 hours postfertilization stage, and decreases thereafter to basal levels at 5 days postfertilization. The cAMP-dependent protein kinase (PKA) was identified as responsible for phosphorylation on the unique CNBP conserved putative phosphorylation site. Site-directed mutagenesis replacing the PKA phospho-acceptor amino acid residue impairs CNBP phosphorylation, suggesting that phosphorylation may not only exist in D. rerio but also in other vertebrates. CNBP phosphorylation does not change single-stranded nucleic acid binding capability. Instead, it promotes in vitro the annealing of complementary oligonucleotides representing the CT element (CCCTCCCC) from the human cellular myelocytomatosis oncogene (c-myc) promoter, an element responsible for c-myc enhancer transcription. Our results suggest that phosphorylation might be a conserved post-translational modification that allows CNBP to perform a fine tune expression regulation of a group of target genes, including c-myc, during vertebrate embryogenesis.
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Affiliation(s)
- Verónica A Lombardo
- División Biología del Desarrollo, IBR-CONICET, Area Biología General, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
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13
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Onorato TM, Chakraborty S, Haldar D. Phosphorylation of Rat Liver Mitochondrial Glycerol-3-phosphate Acyltransferase by Casein Kinase 2. J Biol Chem 2005; 280:19527-34. [PMID: 15778226 DOI: 10.1074/jbc.m410422200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously shown rat liver mitochondrial glycerol-3-phosphate acyltransferase (mtGAT), which catalyzes the first step in de novo glycerolipid biosynthesis, is stimulated by casein kinase 2 (CK2) and that a phosphorylated protein of approximately 85 kDa is present in CK2-treated mitochondria. In this paper, we have identified the (32)P-labeled 85-kDa protein as mtGAT. We have also investigated whether the phosphorylation of mtGAT is because of CK2. Mitochondria were treated with CK2 and [gamma-(32)P]GTP as the phosphate donor. Autoradiography, Western blot, and immunoprecipitation results showed mtGAT was phosphorylated by CK2. Next, we incubated mitochondria with CK2 and either ATP or GTP, in the presence of heparin, a known inhibitor of CK2. Heparin inhibited CK2-induced stimulation of mtGAT activity; this inhibition resulted in decreased (32)P-labeling of mtGAT. Additionally, mitochondria were treated with CK2 and [gamma-(32)P]ATP in the presence of staurosporine (a serine/threonine protein kinase inhibitor), genistein (a tyrosine kinase inhibitor), and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB, a CK2 inhibitor). Only DRB, the CK2 inhibitor, greatly reduced the amount of (32)P-incorporation into mtGAT by CK2. Finally, isolated mitochondrial outer membrane was incubated with cytosol in the presence of [gamma-(32)P]GTP; (32)P-labeled mtGAT was detected. Collectively, these data suggest that CK2 phosphorylates mtGAT. The impact of our results in the regulation of mtGAT and other anabolic processes is discussed.
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Affiliation(s)
- Thomas M Onorato
- Department of Biological Sciences, St. John's University, Queens, New York 11439, USA
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Gilcrease MZ, Zhou X, Welch K. Adhesion-independent alpha6beta4 integrin clustering is mediated by phosphatidylinositol 3-kinase. Cancer Res 2004; 64:7395-8. [PMID: 15492261 DOI: 10.1158/0008-5472.can-04-1809] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Clustering of cell-surface integrins is known to augment integrin-mediated signal transduction, but mechanisms of integrin clustering are poorly understood. Here we report that adhesion-independent clustering of alpha6beta4 integrin, known to be important in mediating tumor cell motility, is driven by phosphatidylinositol 3-kinase (PI3K) but does not require activation of the PI3K-Akt pathway. We observed clustering of alpha6beta4 in breast carcinoma cells after adhesion-independent cross-linking of the beta4 integrin subunit. Clustering was significantly blocked when cross-linking was performed in the presence of PI3K inhibitors LY294002 and wortmannin. In contrast, no significant inhibition of clustering was observed with protein kinase C inhibitor GF109203X, rapamycin, or heparin. Although alpha6beta4 clustering was blocked by PI3K inhibitors, clustering was not associated with increased PI3K lipid kinase activity or increased phosphorylation of Akt. A novel role for PI3K in alpha6beta4 integrin clustering is proposed.
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15
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Asensio CJA, Garcia RC. Determination of a large number of kinase activities using peptide substrates, P81 phosphocellulose paper arrays and phosphor imaging. Anal Biochem 2003; 319:21-33. [PMID: 12842103 DOI: 10.1016/s0003-2697(03)00282-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To perform phosphoproteomics and signal transduction studies, a number of protein kinase activities and levels must be simultaneously analyzed in different cell samples and correlated with phosphoprotein patterns to obtain conclusions with regard to the regulation of kinase networks. We describe here a miniaturized format of the classical phosphocellulose (P81) paper binding assay with which up to 594 kinase reactions can be simultaneously analyzed. Kinase peptide substrates possessing a minimum of three consecutive basic residues were subjected to phosphorylation in 96-well plates and aliquots of the phosphorylation reactions were spotted on arrays printed on P81 papers. Phosphorylation levels were quantified using a storage phosphor system imager. The versatility of the procedure was validated by analyzing casein kinase 2, protein kinase C, and p34cdc2/cyclin B in cell extracts and testing the effect of known inhibitors and activators on kinase activities. This improved, miniaturized version of the classical P81 paper method combines simplicity, high sensitivity, high reproducibility, high reliability, and optimal Z factors and takes into account possible sources of background signals. We discuss the possibility of automation and the advantages over other methods.
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Affiliation(s)
- Cristian J A Asensio
- Leukocyte Biology Unit, International Centre for Genetic Engineering and Biotechnology, Area Science Park, 34012 Trieste, Italy
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16
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Reimer T, Weiwad M, Schierhorn A, Ruecknagel PK, Rahfeld JU, Bayer P, Fischer G. Phosphorylation of the N-terminal domain regulates subcellular localization and DNA binding properties of the peptidyl-prolyl cis/trans isomerase hPar14. J Mol Biol 2003; 330:955-66. [PMID: 12860119 DOI: 10.1016/s0022-2836(03)00713-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human parvulin 14 (hPar14) is a folding helper enzyme belonging to the parvulin family of peptidyl-prolyl cis/trans isomerases (PPIases). This enzyme is thought to play a role in cell-cycle and chromatin remodeling. Although hPar14 was nuclearly localized and bound to double-stranded DNA, the molecular basis of the subcellular localization and the functional regulation remained unknown. Here we show that subcellular localization and DNA-binding ability of hPar14 is regulated by posttranslational modification of its N-terminal domain. As proved by MALDI-TOF mass spectrometry and MS/MS fragmentation, hPar14 is phosphorylated at Ser19 in vitro and in vivo. In human HeLa cells the protein is most likely modified by casein kinase 2 (CK2). Phosphorylation of hPar14 is inhibited both in vitro and in vivo by 5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole (DRB), a specific inhibitor of CK2 activity. Mutation of Ser19 to Ala abolishes phosphorylation and alters the subcellular localization of hPar14 from predominantly nuclear to significantly cytoplasmic. Immunostaining shows that a Glu19 mutant of hPar14, which mimics the phosphorylated state of Ser19, is localized around the nuclear envelope, but does not penetrate into the nucleoplasm. In contrast to wild-type hPar14, the in vitro DNA-binding affinity of the Glu19 mutant is strongly reduced, suggesting that only the dephosphorylated protein is the active DNA-binding form of hPar14 in the nucleus.
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Affiliation(s)
- Tatiana Reimer
- Max Planck Research Unit, Enzymology of Protein Folding, Weinbergweg 22, D-06120 Halle, Germany
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17
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Grasselli E, Noviello G, Rando C, Nicolini C, Vergani L. Expression, purification and characterisation of a novel mutant of the human protein kinase CK2. Mol Biol Rep 2003; 30:97-106. [PMID: 12841580 DOI: 10.1023/a:1023934805326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The recombinant catalytic subunit of human protein kinase CK2 bas been mutagenised at the C-terminal region in an attempt to induce this tail to fold. We suppose in fact that this unstructured C-terminus just might be responsible for the high degradability of the human enzyme. On the basis of theoretical calculations we choose to substitute two distal prolines with alanines (PA 382-384). The mutant bas been purified to the electrophoretic homogeneity by means of three chromatographic steps. By circular dichroism Spectroscopy we verified if the double amino acids substitution reflected on the secondary structure of the recombinant a subunit. According to our theoretical predictions, we observed that the alpha-helix content of the protein increased when the two distal prolines were substituted by alanines. Moreover the mutant catalytic subunit shows a reduced ability to bind a classical inhibitor such as heparin.
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Affiliation(s)
- Elena Grasselli
- Department of Biophysical Sciences and Technologies M.&O., School of Medicine, University of Genova, Genova, Italy
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18
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Delorme V, Cayla X, Faure G, Garcia A, Tardieux I. Actin dynamics is controlled by a casein kinase II and phosphatase 2C interplay on Toxoplasma gondii Toxofilin. Mol Biol Cell 2003; 14:1900-12. [PMID: 12802063 PMCID: PMC165085 DOI: 10.1091/mbc.e02-08-0462] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Actin polymerization in Apicomplexa protozoa is central to parasite motility and host cell invasion. Toxofilin has been characterized as a protein that sequesters actin monomers and caps actin filaments in Toxoplasma gondii. Herein, we show that Toxofilin properties in vivo as in vitro depend on its phosphorylation. We identify a novel parasitic type 2C phosphatase that binds the Toxofilin/G-actin complex and a casein kinase II-like activity in the cytosol, both of which modulate the phosphorylation status of Toxofilin serine53. The interplay of these two molecules controls Toxofilin binding of G-actin as well as actin dynamics in vivo. Such functional interactions should play a major role in actin sequestration, a central feature of actin dynamics in Apicomplexa that underlies the spectacular speed and nature of parasite gliding motility.
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Affiliation(s)
- Violaine Delorme
- Departement des Maladies Infectieuses, Centre National de la Recherche Scientifique Unité Mixte Recherche 8104, Institut Cochin, 75014 Paris, France
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19
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Hsia E, Richardson TP, Nugent MA. Nuclear localization of basic fibroblast growth factor is mediated by heparan sulfate proteoglycans through protein kinase C signaling. J Cell Biochem 2003; 88:1214-25. [PMID: 12647303 DOI: 10.1002/jcb.10470] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Understanding the process of wound healing will provide valuable insight for the development of new strategies to treat diseases associated with improper regeneration, such as blindness induced by corneal scarring. Heparan sulfate proteoglycans (HSPG) are not normally expressed in the corneal stroma, but their presence at sites of injury suggests their involvement in the wound healing response. Primary cultured corneal stromal fibroblasts constitutively express HSPG and represent an injured phenotype. Recently, nuclear localization of HSPG was shown to increase in corneal stromal fibroblasts plated on fibronectin (FN), an extracellular matrix protein whose appearance in the corneal stroma correlates with injury. One possible role for the nuclear localization of HSPG is to function as a shuttle for the nuclear transport of heparin-binding growth factors, such as basic fibroblast growth factor (FGF-2). Once in the nucleus, these growth factors might directly modulate cellular activities. To investigate this hypothesis, cells were treated with (125)I-labelled FGF-2 under various conditions and fractionated. Our results show that nuclear localization of FGF-2 was increased in cells plated on FN compared to those on collagen type I (CO). Interestingly, FGF-2-stimulated proliferation was increased in cells plated on FN compared to CO and this effect was absent in the presence of heparinase III. Furthermore, pre-treatment with heparinase III decreased nuclear FGF-2, and CHO cells defective in the ability to properly synthesize heparan sulfate chains showed reduced nuclear FGF-2 indicating that the heparan sulfate chains of HSPG are critical for this process. HSPG signaling, particularly through the cytoplasmic tails of syndecans, was investigated as a potential mechanism for the nuclear localization of FGF-2. Treatment with phorbol 12-myristate-13-acetate (PMA), under conditions that caused downregulation of protein kinase Calpha (PKCalpha), decreased nuclear FGF-2. Using pharmacological inhibitors of specific PKC isozymes, we elucidated a potential mode of regulation whereby PKCalpha mediates the nuclear localization of FGF-2 and PKCdelta inhibits it. Our studies suggest a novel mechanism in which FGF-2 translocates to the nucleus in response to injury.
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Affiliation(s)
- Edward Hsia
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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20
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Ehrnsperger C, Volknandt W. Major vault protein is a substrate of endogenous protein kinases in CHO and PC12 cells. Biol Chem 2001; 382:1463-71. [PMID: 11727830 DOI: 10.1515/bc.2001.180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Major vault protein (MVP) is the predominant member of a large cytosolic ribonucleoprotein particle, termed vault. We have previously shown that MVP derived from electric ray electric organ becomes phosphorylated by protein kinase C in vitro and by tyrosine kinase in vivo. Here we show that MVP from two mammalian cell lines (CHO and PC12 cell) becomes highly phosphorylated by endogenous protein kinases in cell-free systems. The susceptibility to protein kinases differs substantially from those observed in MVP derived from electric organ. Phosphorylation of MVP depends on the presence of Mg2+ and can be inhibited by the chelating agent EDTA. Inhibitors of casein kinase II attenuate the phosphorylation of MVP. In contrast to CHO cells, addition of recombinant casein kinase II enhances the phosphorylation of MVP in PC12 cells. Endogenous kinase activity is of particulate nature and copurifies with vault particles. Immuno-affinity purified vaults containing recombinant tagged MVP expressed in CHO cells reveal no autophosphorylation, suggesting that protein kinase activity is not an intrinsic property of vaults. Our results suggest that cell-specific phosphorylation of MVP may play a critical role in vault function.
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Affiliation(s)
- C Ehrnsperger
- Biozentrum der Johann-Wolfgang Goethe-Universität, AK Neurochemie, Frankfurt am Main, Germany
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21
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Loog M, Uri A, Järv J, Ek P. Bi-substrate analogue ligands for affinity chromatography of protein kinases. FEBS Lett 2000; 480:244-8. [PMID: 11034338 DOI: 10.1016/s0014-5793(00)01948-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel affinity ligands, consisting of ATP-resembling part coupled with specificity determining peptide fragment, were proposed for purification of protein kinases. Following this approach affinity sorbents based on two closely similar ligands AdoC-Aoc-Arg4-Lys and AdoC-Aoc-Arg4-NH(CH2)6NH2, where AdoC stands for adenosine-5'-carboxylic acid and Aoc for amino-octanoic acid, were synthesized and tested for purification of recombinant protein kinase A catalytic subunit directly from crude cell extract. Elution of the enzyme with MgATP as well as L-arginine yielded homogeneous protein kinase A preparation in a single purification step. Also protein kinase A from pig heart homogenate was selectively isolated using MgATP as eluting agent. Protein kinase with acidic specificity determinant (CK2) as well as other proteins possessing nucleotide binding site (L-type pyruvate kinase) or sites for wide variety of different ligands (bovine serum albumin) did not bind to the column, pointing to high selectivity of the bi-functional binding mode of the affinity ligand.
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Affiliation(s)
- M Loog
- Institute of Chemical Physics, Tartu University, Estonia.
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